Pathogenic bacterium

Microbes Infect, 1999 Jul, 1(8), 621 - 32
Perturbation and exploitation of host cell cytoskeleton by periodontal pathogens; Ellen RP; Some periodontal pathogens disrupt epithelial barriers and cellular adhesion to the extracellular matrix, which affects the cytoskeleton . Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans exploit the cytoskeleton during their uptake by epithelial cells . Treponema denticola perturbs actin and actin-regulating pathways in host cells . Cytoskeletal dysfunction due to pathogenic bacteria may impair physiologic remodeling and wound repair in the periodontium.

Microbes Infect, 1999 Jul, 1(8), 609 - 14
Myristic acid analogs are inhibitors of Junin virus replication; Cordo SM et al.; The effects of two myristic acid analogs on Junin virus (JV) replication were investigated . The compounds chosen for the study were DL-2-hydroxymyristic acid (2OHM), an inhibitor of N-myristoyltransferase (NMT), which binds the enzyme and blocks protein myristoylation, and 13-oxamyristic acid (13OM), a competitive inhibitor of NMT which incorporates into the protein instead of myristic acid . Both types of analogs achieved dose-dependent inhibition of viral multiplication at concentrations not affecting cell viability . The 50% inhibitory concentration values determined by a virus-yield inhibition assay for different strains of JV, including a human pathogenic strain, and for the related arenavirus, Tacaribe, were in the range 1.6 to 20.1 microM, with 13OM as the most active compound . From time of addition and removal experiments, it can be concluded that both analogs inhibit a late stage in the JV replicative cycle, and their effect was partially reversible . The cytoplasmic and surface expression of JV glycoproteins was not affected in the presence of the compounds, as revealed by immunofluorescence staining, suggesting that JV glycoprotein myristoylation would not be essential for the intracellular transport of the envelope proteins, but it may have an important role in their interaction with the plasma membrane during virus budding.

Curr Opin Biotechnol, 1999 Dec, 10(6), 571 - 8
Searching for drug targets in microbial genomes; Galperin MY et al.; Comparative analysis of the complete genome sequences of 10 bacterial pathogens available in the public databases offers the first insights into the drug discovery approaches of the near future . Genes that are conserved in different genomes often turn out to be essential, which makes them attractive targets for new broad-spectrum antibiotics . Subtractive genome analysis reveals the genes that are conserved in all or most of the pathogenic bacteria but not in eukaryotes; these are the most obvious candidates for drug targets . Species-specific genes, on the other hand, may offer the possibility to design drugs against a particular, narrow group of pathogens.

Trop Anim Health Prod, 1999 Dec, 31(6), 347 - 61
Impact of mastitis control measures on milk production and mastitis indicators in smallholder dairy farms in Kiambu district, Kenya; Omore AO et al.; Bovine mastitis and mastitis control were investigated on smallholder farms in central Kenya . After an initial observational study, a clinical trial to assess the impact of three different mastitis control strategies--(1) improved udder hygiene, (2) treatment of subclinical cases, and (3) a combination of these--was conducted on 100 randomly selected farms with 332 lactating cows . Before the implementation of control measures, the milk yield was low (mean 6.5 kg/day; median 6 kg/day) and somatic cell counts (SCC) were high, with 80% and 43% of cows having milk with SCC greater than 250 x 10(3) cells/ml and 600 x 10(3) cells/ml, respectively . Infectious pathogens were also commonly isolated, with 63% of cows being positive for pathogenic bacteria . Neither intervention strategy alone had any effect on mastitis indicators or milk yield . In combination, the measures had some impact, lowering the prevalence of contagious pathogens by 18%, but this was not reflected in a significantly increased milk yield, lowered SCC or reduced incidence of clinical mastitis.

Mol Cells, 1999 Oct 31, 9(5), 491 - 6
Cloning of a cysteine proteinase gene from Acanthamoeba culbertsoni; Yun HC et al.; Free living amoeba, including pathogenic Acanthamoeba culbertsoni, are widely distributed in soil and fresh water . It has been found that cysteine proteinases are more active in pathogenic strains of amoeba whereas serine proteinases are found in both pathogenic and nonpathogenic strains . Cysteine proteinases thus play important roles in the pathogenesis of several parasitic infections and have been proposed as targets for the structure-based strategy of drug design . As the first step toward applying this strategy to design inhibitors as antiparasitic agents for A . culbertsoni, we isolated and sequenced the full length clone of a cysteine proteinase gene from A . culbertsoni by performing reverse transcription-polymerase chain reaction (RT-PCR) with degenerate oligonucleotide primers derived from conserved cysteine proteinase sequences . The 5' and the 3' regions of the cysteine proteinase gene were amplified using the PCR protocol for the rapid amplification of cDNA ends (RACE) . It has an open reading frame of 1359 bp . The deduced amino acid sequence has the sequence homology with the cysteine proteinase genes of Paragonimus westermani metacercaria, Schistosoma mansoni, human cathepsin L and Fasciola hepatica, each by 45.3%, 45.9%, 57.9% and 50.8% respectively . Sequence analysis and alignment showed significant similarity to other eukaryotic cysteine proteinases, including the conservation of the cysteine, histidine, and asparagine residues that form the catalytic triad . A 1.5 kbp mRNA was detected on Northern blot analysis using full-length cysteine proteinase cDNA as a probe . The A . culbertsoni cysteine proteinase gene (AcCP2) was found to contain Ex3Rx3Wx2N at the proregion and also a proline/threonine-rich C-terminal extension . Therefore, it has cathepsin L-like characteristics . Phylogenetic analysis based on the amino acid sequences of cysteine proteinase indicated that AcCP2 was closely related with papaya, while it was remotely related with those of Schistosoma.

Anaesthesia, 1999 Dec, 54(12), 1183 - 97
Ventilator-associated pneumonia . Diagnosis, pathogenesis and prevention; Young PJ et al.; Ventilator-associated pneumonia is common, difficult to diagnose, affects the most vulnerable of patients and carries a high mortality . During prolonged mechanical ventilation the oropharynx, sinuses, dentition and stomach of critically ill patients become colonised with pathogenic bacteria . Colonised secretions pool in the oropharynx and subglottic space . These secretions repeatedly gain access to the lower airways by leakage past the tracheal tube cuff . If host defence mechanisms are overwhelmed, multiplication occurs in the lower respiratory tract producing an inflammatory response in the bronchioles and alveoli . The inflammatory response is characterised by capillary congestion, leucocyte and macrophage infiltration and fibrinous exudation into the alveolar spaces . If this inflammatory response occurs more than 48 h after intubation, it is called ventilator-associated pneumonia . Prevention depends on reducing upper airway and gastrointestinal reservoirs of bacteria, reducing or abolishing aspiration of these bacteria past the tracheal tube cuff and enhancing bacterial clearance from the lower airways.

J Med Primatol, 1999 Aug-Oct, 28(4-5), 181 - 9
Antigen-specific cytokine responses in vaccinated Macaca nemestrina; Mulvania T et al.; We describe a new surrogate assay for CD8 + T lymphocyte activity that has the capability of discriminating between cytotoxic T lymphocyte (CTL) activity and cytokine-mediated suppressive activity . We applied this approach to two groups of Macaca nemestrina vaccinated with a minimally pathogenic strain of human immunodeficiency virus type 2 {HIV-2 (HIV-2(KR))} as a model of an attenuated virus vaccine . Group 1 was then inoculated with a non-infectious stock of a pathogenic strain, HIV-2287 . Both groups 1 and 2 were subsequently challenged with an infectious stock of HIV-2287 . Five out of six group 1 animals were protected against CD4 decline, whereas three out of six animals in group 2 were protected . Analysis of CTL responses demonstrated strong activity against HIV-2(KR)-Gag in group 1 . It was determined that strong CTL responses correlate with antigen-specific T-helper (Th) type 1 responses . This antigen-specific cytokine assay has the potential to better elucidate the functional mechanisms of CD8 + T-cell-mediated protection than traditional methods to date.

J Microbiol Immunol Infect, 1997 Feb, 30(1), 55 - 9
{Pathogenic strains of Escherichia coli in Taiwan}; Lee CL et al.; From July 1994 through June 1996, 28 strains of Escherichia coli were isolated from 1,260 patients with acute diarrhea . These strains were further differentiated with serotypes and virulence factors . Enterotoxigenic E . coli (ETEC), enteropathogenic E . coli (EPEC), enterohemorrhagic E . coli (EHEC), and enteroinvasive E . coli (EIEC) were accounted for 53.6 (15 of 28 strains), 28.6 (8 of 28), 10.7 (3 of 28) and 7.1% (2 of 28), respectively . Therefore, ETEC and EPEC are playing an important role in food-borne illness in Taiwan . Escherichia coli O157:H7, a new emerging pathogen of food-borne disease, has not been isolated in this study.

Clin Infect Dis, 1999 Oct, 29(4), 888 - 911
The body louse as a vector of reemerging human diseases; Raoult D et al.; The body louse, Pediculus humanus humanus, is a strict human parasite, living and multiplying in clothing . Louse infestation is associated with cold weather and a lack of hygiene . Three pathogenic bacteria are transmitted by the body louse . Borrelia recurrentis is a spirochete, the agent of relapsing fever, recently cultured on axenic medium . Historically, massive outbreaks have occurred in Eurasia and Africa, but currently the disease is found only in Ethiopia and neighboring countries . Bartonella quintana is now recognized as an agent of bacillary angiomatosis bacteremia, trench fever, endocarditis, and chronic lymphadenopathy among the homeless . Rickettsia prowazekii is the agent of epidemic typhus . The most recent outbreak (and the largest since World War II) was observed in Burundi . A small outbreak was also reported in Russia in 1997 . Louse infestation appears to become more prevalent worldwide, associated with a decline in social and hygienic conditions provoked by civil unrest and economic instability.

Pediatrics, 1999 Dec, 104(6), 1321 - 6
Tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 levels in febrile, young children with and without occult bacteremia; Strait RT et al.; OBJECTIVE: To determine the utility of plasma levels of tumor necrosis factor-alpha (TNF), interleukin 1 beta (IL-1), and interleukin 6 (IL-6) in the prediction of occult bacteremia in febrile, young children . STUDY DESIGN: Prospective, case-control study conducted in a large, urban, children's hospital emergency department . Eligibility criteria were: 0 to 36 months of age, febrile, nontoxic appearing, immunocompetent, no apparent bacterial source for fever on physical examination, and blood culture obtained . Additional blood, procured at the time of the blood culture, was analyzed by enzyme-linked immunosorbent assay for TNF, IL-1, and IL-6 . Children with positive blood cultures for pathogenic bacteria served as cases . Two age-matched controls for each case were selected from the children with negative cultures . RESULTS: Out of 1329 enrollees, 33 cases and 66 controls were evaluated . IL-6 levels were significantly higher for the cases than controls but with moderate overlap in their ranges . TNF and IL-1 levels were not significantly different between cases and controls . Height of fever, duration of fever, acute illness observation score, absolute band count, and white blood cell count were all much less predictive of bacteremia than either IL-6 or absolute neutrophil count (ANC) . The optimum IL-6 threshold value had a sensitivity of 88%, a specificity of 70%, a positive predictive value (PPV) of 7.0%, a negative predictive value (NPV) of 99.6%, and an odds ratio (OR) of 16.7 (95% confidence interval {CI}, 4.8-71.6) . The optimum ANC threshold value had a sensitivity of 82%, a specificity of 74%, a PPV of 7.5%, a NPV of 99.4%, and an OR of 12.8 (95% CI, 3.2-59.7) . The best predictor was a combination of IL-6 and ANC . It had a sensitivity of 100%, a specificity of 78%, a PPV of 10.4%, a NPV of 100%, and an OR which is undefined because of the 100% sensitivity (95% CI, 33.0-infinity) . For comparison, a WBC >15 x 10(9) cells/L had a sensitivity of 48%, a specificity of 79%, a PPV of 5.5%, a NPV of 98.3%, and an OR of 3 . 5 (95% CI, 1.1-10.7) . CONCLUSIONS: In febrile children 0 to 36 months of age, IL-6 levels may be helpful in the prediction of occult bacteremia, but TNF and IL-1 levels are not . IL-6 levels alone or notably when combined with an ANC were more predictive of occult bacteremia than traditional tests and clinical criteria . The wide range in the IL-6 values for cases and controls detracts from the precision of the findings . The lack of rapid processing and clinical availability of IL-6 assays hampers its present application . However, despite these drawbacks and given the poor ability of traditional clinical and laboratory criteria to predict occult bacteremia, these results suggest a possible future role for IL-6 in predicting occult bacteremia when rapid assays become available.

Am J Rhinol, 1999 Sep-Oct, 13(5), 349 - 55
The relationship of nasal polyps, infection, and inflammation; Norlander T et al.; The role of infection as cause or effect in nasal polyps is debated . In experimentally induced sinusitis in rabbits, polyps are frequent . The initial polyp formation sequence involves multiple epithelial disruptions with proliferating granulation tissue . Regenerating epithelial branches spread into the underlying connective tissue, where intraepithelial microcavities give rise to a polyp body from the adjacent mucosa . Clinical as well as experimental studies indicate that nasal polyp formation and growth are activated and perpetuated by an integrated process of mucosal epithelium, matrix, and inflammatory cells, which in turn may be initiated by both infectious and noninfectious inflammation . The complexity of the pathophysiologic events in nasal polyposis is reinforced by the finding that epithelial desquamation, combined with infection or inflammation, will initiate polyp formation . Systemic glucocorticosteroids inhibit polyp formation as well as growth of pathogenic bacteria in the sinuses of rabbits with experimental infection . Therapeutic use of corticosteroids in polyp disease, combined with antibiotics or surgery, should be modified in relation to long-term progression, intensity variations, and predisposing conditions.

Crit Care Med, 1999 Nov, 27(11), 2399 - 406
The effect of acidified enteral feeds on gastric colonization in critically ill patients: results of a multicenter randomized trial . Canadian Critical Care Trials Group; Heyland DK et al.; OBJECTIVE: To evaluate the effect of acidified enteral feeds on gastric colonization in critically ill patients compared with a standard feeding formula . DESIGN: Randomized, double-blind, multicenter trial . SETTING: Eight mixed intensive care units at tertiary care hospitals . PATIENTS: We recruited mechanically ventilated critically ill patients expected to remain ventilated for >48 hrs . We excluded patients with gastrointestinal bleeding, acidemia, and renal failure requiring dialysis . We enrolled 120 patients; 38% were female, age (mean +/- SD) was 57.6+/-19.3 yrs, and Acute Physiology and Chronic Health Evaluation II score (mean +/- SD) was 21.6+/-7.6 . INTERVENTIONS: Vital High Nitrogen (Abbott Laboratories, Ross Products Division, Columbus, OH) was used as the standard feeding formula for the control group (pH = 6.5) . Hydrochloric acid was added to Vital High Nitrogen to achieve a pH of 3.5 in the experimental group . MEASUREMENTS AND MAIN RESULTS: The main outcome measure was gastric colonization . Secondary outcomes included gastric pH, pneumonia, and mortality . The mean gastric pH in patients receiving acid feeds was lower (pH = 3.3) compared with controls (pH = 4.6; p<.05) . One patient (2%) on acid feeds was colonized in the stomach with pathogenic bacteria, compared with 20 patients (43%) in the control group (p<.001) . There was no difference in the incidence of pneumonia (6.1% in the acid feeds group vs . 15% in the control group; p = .19) . Overall, there were 15 deaths in the acid feeds group and seven in the control group (p = .10); four patients in the acid feeds group and three in the control group died during the study period (p not significant) . CONCLUSIONS: Acidified enteral feeds preserve gastric acidity and substantially reduce gastric colonization in critically ill patients . Larger studies are needed to examine its effect on ventilator-associated pneumonia and mortality.

Int J Parasitol, 1999 Aug, 29(8), 1307 - 19
Pathogenicity of selected Toxoplasma gondii isolates in young pigs; Jungersen G et al.; The pathogenicity in 7-week-old pigs to five different Toxoplasma gondii strains of various host species origin was compared after i.v . inoculation of 10(4) tachyzoites . Additionally, one group of pigs was inoculated i.v . with 10(6) tachyzoites of the reference strain, SSI 119 . In response to the infection a significant effect of T . gondii tachyzoite inoculation dose as well as differences among strains could be observed in several parameters . The 10(6)-dose inoculated pigs showed variable degrees of clinical illness and recurrent episodes of fever 4-17 days p.i., while pigs of four of the 10(4) tachyzoite inoculated groups experienced a short-lived rise in body temperature from day 6-8 p.i . without any apparent illness or inappetence . Control pigs and pigs infected with the least pathogenic strain had normal body temperature throughout the experiment . In all inoculated pigs, T . gondii-specific IgM and IgG antibodies appeared from day 8-10 and 10-17 p.i., respectively . Serum levels of alkaline phosphatase and the acute phase protein haptoglobin were decreased or increased, respectively, in response to the infection . Differential leukocyte count on peripheral blood revealed a significant lymphocytopenia on day 6 p.i . equal to both CD4+ and CD8+ T-cells, but shifting towards a reduced ratio of CD4+/CD8+ T-cells from day 8-14 p.i . In the 10(6)-dose inoculated pigs a considerable increase in zymosan induced and spontaneous oxidative burst capacity of peripheral blood leukocytes was observed from 6 days p.i . compared with control pigs . Oxidative burst capacity was not examined for other pigs . In conclusion, several useful parameters to identify differences in T . gondii pathogenicity other than mortality were identified . Furthermore, even at low doses, significant differences between recently collected Danish T . gondii field isolates were demonstrated after i.v . inoculation in young pigs.

Eur J Biochem, 1999 Dec, 266(2), 484 - 92
Conformations in solution of the fuscopeptins . Phytotoxic metabolites of Pseudomonas fuscovaginae; Bare S et al.; Fuscopeptins are phytotoxic amphiphilic lipodepsipeptides containing 19 amino acid residues . They are produced by the plant pathogenic bacterium Pseudomonas fuscovaginae in two forms, A and B, which differ only in the number of methylene groups in the fatty acid chain . Their covalent structure and biological properties have been reported previously . CD and NMR spectroscopy investigations in solution revealed the absence of identifiable elements of secondary and tertiary structure for these molecules . Fuscopeptin B appears to be completely unstructured in aqueous solution, and has a large molecular flexibility . A dramatic conformational change was observed upon addition of trifluoroethanol . This study reports the complete interpretation of the two-dimensional NMR spectra and the NOE results obtained for fuscopeptin B in water/trifluoroethanol solutions; the signals relative to the peptidic moiety are identical to those observed for fuscopeptin A . The results of this investigation were used to determine the solution structure of fuscopeptin B by computer simulations applying distance geometry and simulated annealing procedures . In water/trifluoroethanol solutions the peptidic region appears to have a partly helical structure . The lactonic ring assumes defined conformations very similar to those already reported for other lipodepsipeptides . The structure for fuscopeptin B in solution is also valid for fuscopeptin A because of the negligible structural difference between the two metabolites.

J Virol, 1999 Dec, 73(12), 10346 - 58
Use of a gp120 binding assay to dissect the requirements and kinetics of human immunodeficiency virus fusion events; Doranz BJ et al.; Binding of the extracellular subunit of human immunodeficiency type 1 (HIV-1) envelope (Env) glycoprotein (gp120) to CD4 triggers the induction or exposure of a highly conserved coreceptor binding site in gp120 that helps mediate membrane fusion . Characterizing the structural features involved in gp120-coreceptor binding and the conditions under which binding occurs is important for understanding the fusion process, the evolution of pathogenic strains in vivo, the identification of novel anti-HIV compounds, and the development of HIV vaccines that utilize triggered structures of Env . Here we use the kinetics of interaction between CCR5 and gp120 to understand temporal and structural changes that occur during viral fusion . Using saturation binding and homologous competition analysis, we estimated the K(d) of interaction between CCR5 and gp120 from the macrophage tropic HIV-1 strain JRFL to be 4 nM . Unlike Env-mediated fusion, gp120 binding to CCR5 did not require divalent cations or elevated temperatures . Binding was not significantly affected by the pH of binding, G-protein coupling of CCR5, or partial gp120 deglycosylation . Oligomeric, uncleaved JRFL gp140 failed to bind CCR5 despite its ability to bind CD4 and monoclonal antibody 17b, suggesting that the uncleaved ectodomain of gp41 interferes with full exposure of the chemokine receptor binding site . Exposure of the chemokine receptor binding site on gp120 could be induced rapidly by CD4, but exposure of this site was lost upon CD4 dissociation from gp120, indicating that the conformational changes in gp120 induced by CD4 binding are fully reversible . The functional gp120-soluble CD4 complex was remarkably stable over time and temperature ranges, offering the possibility that complexes in which the highly conserved coreceptor binding site in gp120 is exposed can be used for vaccine development.

Int J Syst Bacteriol, 1999 Oct, 49 Pt 4, 1577 - 89
Janthinobacterium agaricidamnosum sp . nov., a soft rot pathogen of Agaricus bisporus; Lincoln SP et al.; A novel bacterium has been found that causes a soft rot disease of Agaricus bisporus, the cultivated mushroom . It has been characterized using nutritional, physiological, chemical and molecular techniques . Based on these data, it was shown to have many characteristics in common with members of the genus Janthinobacterium . Despite similarities to the only described species within this genus, Janthinobacterium lividum, there were a number of differences between the mushroom pathogen isolated and this species . Despite the high degree of genotypic similarity between members of the genus Janthinobacterium and Herbaspirillum, as evidenced by DNA-RNA hybridization, and the high degree of 16S rDNA sequence similarity between members of the genera Janthinobacterium, Herbaspirillum, Oxalobacter and Duganella, as well as the generically misnamed Pseudomonas lemoignei, it was possible to show that members of the genus Janthinobacterium could be easily distinguished from these taxa . The data also indicated that the mushroom pathogenic strains represent a novel species within the genus Janthinobacterium for which the name Janthinobacterium agaricidamnosum sp . nov . is proposed . The type strain of this species has been deposited in the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany, as DSM 9628T and at the National Collection of Plant-pathogenic bacteria, UK, as NCPPB 3945T . To aid practical control of the disease, the effect of the relative humidity on symptom expression on Agaricus bisporus was determined.

Anal Biochem, 1999 Nov 1, 275(1), 1 - 5
A method for extraction of high-quality and high-quantity genomic DNA generally applicable to pathogenic bacteria; Kalia A et al.; In this study, we report a modified procedure for extraction of high-quality genomic DNA that is rapid, simple, biologically nonhazardous, and generally applicable to pathogenic bacteria . Bacterial cells were pretreated with 70% ethanol prior to enzymatic digestion with lysozyme . Exposure of bacterial cells to 70% ethanol sterilized the cultures, making the process biologically safe and increased the susceptibility of the cells to lysozyme-induced lysis . Consistently high yields of genomic DNA (mean average yield, 0.5-2.5 mg/ml) were obtained from 465 isolates representing over 30 clinically important bacterial species . Genomic DNA obtained was determined to be suitable for further analysis, including bacterial fingerprinting techniques like restriction endonuclease analysis, Southern hybridization, and repetitive PCR . Availability of a generally applicable procedure for extraction of high-quality and high-quantity genomic DNA would be immensely beneficial for laboratories engaged in molecular surveillance of nosocomial and community-based outbreaks .

Acta Crystallogr D Biol Crystallogr, 1999 Nov, 55(11), 1925 - 7
Crystallization and preliminary x-ray structure determination of Lupinus luteus PR10 protein; Biesiadka J et al.; The pathogenesis-related protein of the PR10 class from Lupinus luteus (yellow lupin), LlPR10.1A, is constitutively expressed in roots . It is also accumulated in leaves treated with a suspension of pathogenic bacteria as a response to stress . Recombinant yellow-lupin LlPR10.1A protein has been overexpressed in Escherichia coli as a fusion product with maltose-binding protein . LlPR10.1A crystallizes in the orthorhombic P2(1)2(1)2(1) space group and the crystals diffract to 2.45 A resolution . The structure has been solved by molecular replacement, using the structure of a birch-pollen allergen protein as a model.

Microbiol Immunol, 1999, 43(7), 717 - 21
Phenotypic and genotypic homogeneity of the strains of Rickettsia japonica isolated from patients with Oriental spotted fever; Uchiyama T; Nine pathogenic strains of Rickettsia japonica isolated from patients with Oriental spotted fever were compared phenotypically and genotypically . Constitution and antigenicity of the proteins demonstrated to be the same among strains . Polymerase chain reaction (PCR) amplification of the two major outer membrane protein genes (ompA and ompB) and an intracellular spotted fever group-common antigen protein gene (rps120) produced the same sizes of products for all strains . Restriction fragment length polymorphism of the PCR products showed the same pattern among strains with each endonuclease . Thus, these strains belong to a single type, the same as the type strain YH (=ATCC VR-1363).

Scand J Infect Dis, 1999, 31(4), 383 - 5
Free-living amoebae protecting Legionella in water: the tip of an iceberg?
Winiecka-Krusnell J, Linder E.
Bacteria are a main food source for free-living amoebae inhabiting aquatic systems . Some bacteria however, have the ability to prevent intracellular destruction and can survive and grow in amoebic cells as endosymbionts . Free-living amoebae are well adapted to their hostile environmental conditions and are resistant to both desiccation, elevated temperatures and various disinfectants . For their endosymbionts, amoebae represent perfect vectors, providing both protection against adverse environmental conditions and transportation . There is increasing interest in the potential role of free-living amoebae as reservoirs and vectors of pathogenic bacteria . The best known of such pathogenic bacteria is Legionella, and several studies provide evidence for the importance of the amoeba-bacterium relationship in the biology and epidemiology of pneumonia caused by this pathogen . Although the relative importance of endosymbiosis of this kind is unknown when it comes to other human bacterial infections and the exact role of amoebic hosts in bacterial survival, multiplication and transmission in the environment is still poorly understood, naming free-living amoebae the "Trojan horses" of the microbial world is appropriate.

J Biol Chem, 1999 Oct 22, 274(43), 30697 - 706
The COOH terminus of aminoglycoside phosphotransferase (3')-IIIa is critical for antibiotic recognition and resistance; Thompson PR et al.; The aminoglycoside phosphotransferases (APHs) are widely distributed among pathogenic bacteria and are employed to covalently modify, and thereby detoxify, the clinically relevant aminoglycoside antibiotics . The crystal structure for one of these aminoglycoside kinases, APH(3')-IIIa, has been determined in complex with ADP and analysis of the electrostatic surface potential indicates that there is a large anionic depression present adjacent to the terminal phosphate group of the nucleotide . This region also includes a conserved COOH-terminal alpha-helix that contains the COOH-terminal residue Phe(264) . We report here mutagenesis and computer modeling studies aimed at examining the mode of aminoglycoside binding to APH(3')-IIIa . Specifically, seven site mutants were studied, five from the COOH-terminal helix (Asp(261), Glu(262), and Phe(264)), and two additional residues that line the wall of the anionic depression (Tyr(55) and Arg(211)) . Using a molecular modeling approach, six ternary complexes of APH(3')-IIIa.ATP with the antibiotics, kanamycin, amikacin, butirosin, and ribostamycin were independently constructed and these agree well with the mutagenesis data . The results obtained show that the COOH-terminal carboxylate of Phe(264) is critical for proper function of the enzyme . Furthermore, these studies demonstrate that there exists multiple binding modes for the aminoglycosides, which provides a molecular basis for the broad substrate- and regiospecificity observed for this enzyme.

Clin Chest Med, 1999 Sep, 20(3), 653 - 70
Epidemiology and risk factors for nosocomial pneumonia . Emphasis on prevention; Kollef MH; VAP is a complex nosocomial infection, the disease expression and resulting patient outcome of which is dependent on host factors, the causative organism, the timing and adequacy of treatment, and the presence of intrinsic or inducible antibiotic resistance . Significant improvements have been achieved in our ability to reduce the occurrence of VAP in the hospital setting . Clinicians caring for mechanically ventilated patients should strive to develop focused programs for the prevention of VAP, other nosocomial infections, and the occurrence of antibiotic-resistant infections at their institutions . The benefits of such programs are well demonstrated . The components of a PDSA (Plan-Do-Study-Act) model that can be simply employed to develop a VAP prevention program are as follows: Stages Plan: 1 . Identify potentially modifiable risk factors for VAP at the institutional level . 2 . Develop a strategy to modify or prevent the occurrence of these risk factors . {figure: see text} Do: 1 . Carry out the planned intervention strategy . 2 . Identify problems in the implementation of the designed intervention . 3 . Update the intervention with solutions for the identified problems . 4 . Collect basic data (e.g., VAP rates, severity of illness) . Study: 1 . Analyze data . 2 . Summarize the results . Act: 1 . Determine the overall success or failure of the intervention . 2 . Identify potential modifications to improve the intervention strategy . 3 . Prepare for next PDSA cycle . Inherent in the development and application of such programs is the concept that they are continuous processes striving to improve clinical performance over time (Fig . 3) . At any given institution, the most likely approach to the prevention of NP and VAP will be a multifaceted one, employing interventions aimed at reducing the occurrence of aerodigestive tract colonization with pathogenic bacteria and aspiration . To be successful, such quality improvement programs must be embraced at the institutional level . Only in this way can hospitals hope to successfully reduce their rates of VAP and sustain or improve upon those efforts over time.

J Med Assoc Thai, 1999 Jul, 82(7), 643 - 7
Prevalence of disseminated Mycobacterium avium complex infection in Thai AIDS patients; Chuchottaworn C et al.; Infections caused by nontuberculous mycobacteria (NTM), although rare in immuno-competent individuals, can potentially produce problems in immunocompromised patients such as those with acquired immunodeficiency syndrome (AIDS) . In this study, hemocultures for mycobacteria using radiometric BACTEC 13A media were taken from 334 patients with known human immunodeficiency virus infection admitted to four referral hospitals with fever of unknown site of infection and negative blood cultures for pathogenic bacteria . The mycobacterial hemocultures were positive for Mycobacterium avium complex (MAC) in 58 patients (17.4%) and positive for Mycobacterium tuberculosis in 34 patients (10.2%) . The results of this study have proved that MAC infection, indeed, exists among Thai AIDS patients . The prevalence of MAC infection in Thailand is very high and comparable to that in the western countries . Physicians taking care of AIDS patients in Thailand should be aware of potential MAC infection, particularly in advanced cases . Considering the high prevalence of infection, primary prophylaxis against MAC infection in advanced AIDS patients is recommended.

J Antimicrob Chemother, 1999 Sep, 44(3), 337 - 41
Faropenem enhances superoxide anion production by human neutrophils in vitro; Sato K et al.; Neutrophils are important cellular components in the defence against infections and many studies in vitro have shown that some antibiotics affect neutrophil function . We examined the effect of faropenem, a new oral penem antibiotic on neutrophil killing function by determining the generation of superoxide anion in vitro . The production of superoxide anion was measured by chemiluminescence amplified by a Cypridina luciferin analogue in the presence of N-formyl-Met-Leu-Phe (fMLP) . Faropenem significantly enhanced chemiluminescence in a dose-dependent manner . The effect of faropenem was maximal at 5 min of incubation time and continued for at least 30 min . The effect of faropenem was also observed when neutrophils were stimulated by a calcium ionophore (ionomycin), while the effect of faropenem did not change in the presence of 12-O-tetra-decanoylphorbolmyristate acetate . Cytosol Ca2+ concentration ({Ca2+}i) monitored with Fura-2 increased in response to fMLP, however, faropenem did not influence the response of {Ca2+}i to fMLP . Our results suggest that faropenem enhanced the generation of superoxide anion by neutrophils, probably at the site where cytosol Ca2+ regulates NADPH oxidase . Faropenem might be potentially advantageous in the treatment of infections because a synergic interaction of antibodies and cytocidal neutrophils is necessary for the early eradication of the pathogenic bacteria.

Nat Biotechnol, 1999 Oct, 17(10), 1021 - 4
Engineered detoxification confers resistance against a pathogenic bacterium; Zhang L et al.; We generated transgenic sugarcane plants that express an albicidin detoxifying gene (albD), which was cloned from a bacterium that provides biocontrol against leaf scald disease . Plants with albicidin detoxification capacity equivalent to 1-10 ng of AlbD enzyme per mg of leaf protein did not develop chlorotic disease symptoms in inoculated leaves, whereas all untransformed control plants developed severe symptoms . Transgenic lines with high AlbD activity in young stems were also protected against systemic multiplication of the pathogen, which is the precursor to economic disease . We have shown that genetic modification to express a toxin-resistance gene can confer resistance to both disease symptoms and multiplication of a toxigenic pathogen in its host.

Infect Control Hosp Epidemiol, 1999 Sep, 20(9), 626 - 8
Bacterial contamination of hospital physicians' stethoscopes; Bernard L et al.; Because stethoscopes might be potential vectors of nosocomial infections, this study, conducted in a 450-bed general hospital, was devised to evaluate the bacterial contamination of stethoscopes; bacterial survival on stethoscope membranes; the kinetics of the bacterial load on stethoscope membranes during clinical use; and the efficacy of 70% alcohol or liquid soap for membrane disinfection . Among the 355 stethoscopes tested, 234 carried > or =2 different bacterial species; 31 carried potentially pathogenic bacteria . Although some bacteria deposited onto membranes could survive 6 to 18 hours, none survived after disinfection.

Avian Dis, 1999 Jul-Sep, 43(3), 414 - 23
Pathologic study of specific-pathogen-free chicks and hens inoculated with adenovirus isolated from hydropericardium syndrome; Nakamura K et al.; The mortality and pathology caused by serotype 4 adenovirus, isolated from chickens with hydropericardium syndrome (HPS) in Japan, was investigated in specific-pathogen-free (SPF) chickens . One-day-old to 15-mo-old SPF chickens were inoculated intramuscularly, orally, and intranasally with liver homogenates from HPS chickens or isolated serotype 4 adenovirus . There were no clinical signs before death . The mortality rate in all groups of 1-day-old chicks was 100%, irrespective of the inoculum or inoculation route . Four-week-old chickens inoculated with liver homogenate also had a 100% mortality rate . Five-week-old chickens inoculated with cell culture of HPS adenovirus had a 40% mortality rate . The mortality rates of 7-mo-old hens inoculated with liver homogenates intramuscularly and orally were 75% and 25%, respectively . In 15-mo-old hens inoculated with liver homogenates intramuscularly, the mortality rate was 70% . Gross lesions were hydropericardium and swelling and congestion of the liver with occasional petechial hemorrhages . Histologically, the liver had diffuse or multifocal hepatic necrosis and hemorrhage with intranuclear inclusion bodies noted within hepatocytes . In the spleen, macrophages containing erythrocytes and yellow pigment were prominent in the red pulp . In the lung, a moderate diffuse macrophage infiltration was noted throughout the lung parenchyma, and these macrophages contained yellow pigment . In the pancreas of the chicks inoculated at 1 day old, there was multifocal necrosis of glands with intranuclear inclusion bodies . Intranuclear inclusion bodies were seen also in the gizzard, proventriculus, duodenum, cecum, kidney, and lung of the chicks inoculated at 1 day old . Immunohistochemically, the intranuclear inclusion bodies of various organs showed positive reactions against group I avian adenovirus . Adenovirus was recovered from the liver of chickens with HPS . This study indicates that HPS adenovirus is able to reproduce HPS lesions and mortality in SPF chicks and even adult chickens and that it is a highly pathogenic strain.

Indian J Exp Biol, 1999 May, 37(5), 429 - 33
Role of bio-metal Fe(III) in anticancer behaviour of tamoxifen; Shukla J et al.; Physicochemical, microbial and pharmacological studies on Fe (III)--Tamoxifen complex have been carried out in solid and aqueous phases . On the basis of elemental analysis, polarographic studies, amperometric titrations and IR spectral studies the probable formula for the complex has been worked out to be 1:1, Fe(III)--Tamoxifen . A tentative structure has been suggested to the complex . The metal ligand interaction has been studied using polarographic method at 27 degrees +/- 1 degree C and at ionic strength of mu = 1.0 (KCl) . Microbial studies on the complex was carried out against various pathogenic bacteria and fungi using Raper's method . Mouse sarcoma cell line 180 and Balb/C mice were used for the anticancer screening of solid complex, in vitro and in vivo, respectively . The results of microbial and pharmacological studies with the M:Drug complex revealed that the complex is more potent as compared to the pure drug as regards to its anticancer activity . As such Fe (III) Tamoxifen complex may be recommended to the therapeutic experts for its possible use as more potent anticancer drug.

Dtsch Tierarztl Wochenschr, 1999 Aug, 106(8), 319 - 25
{Seafood transmitted diseases}; Feldhusen F; This paper reviews seafood related bacterial, viral and parasitological hazards for consumers worldwide . Seafood from Europe is generally regarded as safe . Food safety risks associated with aquaculture products results from contamination with biological agents, which are greater in freshwater and coastal ecosystems than in open seas . Due to the consumption conditions and the intensive investigations of imported products with contamination of pathogenic bacteria there are little seafood risks in Europe . Viral infections are associated with consumption of raw or recontaminated shellfish . There has been speculation that more than 50% of the outbreaks of unknown aethiology are due to viruses . Foodborne parasitic hazards are associated with the consumption of raw (sushi) or insufficiently heated, marinated and salted seafood.

J Clin Microbiol, 1999 Oct, 37(10), 3159 - 66
Molecular analysis of riboflavin synthesis genes in Bartonella henselae and use of the ribC gene for differentiation of Bartonella species by PCR; Bereswill S et al.; The biosynthesis pathway for riboflavin (vitamin B(2)), the precursor of the essential cofactors flavin mononucleotide and flavin adenine dinucleotide, is present in bacteria and plants but is absent in vertebrates . Due to their conservation in bacterial species and their absence in humans, the riboflavin synthesis genes should be well suited either for detection of bacterial DNA in human specimens or for the differentiation of pathogenic bacteria by molecular techniques . A DNA fragment carrying the genes ribD, ribC, and ribE, which encode homologues of riboflavin deaminase (RibD) and subunits of riboflavin synthetase (RibC and RibE), respectively, was isolated from a plasmid-based DNA library of the human pathogen Bartonella henselae by complementation of a ribC mutation in Escherichia coli . Sequence analysis of the ribC gene region in strains of B . henselae, which were previously shown to be genetically different, revealed that the ribC gene is highly conserved at the species level . PCR amplification with primers derived from the ribC locus of B . henselae was used to isolate the corresponding DNA regions in B . bacilliformis, B . clarridgeiae, and B . quintana . Sequence analysis indicated that the riboflavin synthesis genes are conserved and show the same operon-like genetic organization in all four Bartonella species . Primer oligonucleotides designed on the basis of localized differences within the ribC DNA region were successfully used to develop species-specific PCR assays for the differentiation of B . henselae, B . clarridgeiae, B . quintana, and B . bacilliformis . The results obtained indicate that the riboflavin synthesis genes are excellent targets for PCR-directed differentiation of these emerging pathogens . The PCR assays developed should increase our diagnostic potential to differentiate Bartonella species, especially B . henselae and the newly recognized species B . clarridgeiae.

J Biotechnol, 1999 Aug 20, 73(2-3), 251 - 60
Pigs aerogenously immunized with genetically inactivated (ghosts) or irradiated Actinobacillus pleuropneumoniae are protected against a homologous aerosol challenge despite differing in pulmonary cellular and antibody responses; Katinger A et al.; Aerosol immunization is a safe way to induce complete protection against pleuropneumonia in pigs caused by the lung pathogenic bacterium Actinobacillus pleuropneumoniae . In order to determine the local immune responses of vaccinees in concomitant with protection, lung lining fluid before and 3 weeks after immunization from pigs immunized three times with aerosols of either genetically inactivated ghosts which represent whole cell envelope preparations, or irradiated bacteria were examined following an homologous aerosol challenge . Specific antibody isotypes in the bronchoalveolar lavage were assayed by whole cell ELISAs . Total and relative numbers of cells including lymphocyte subsets were determined . In both vaccinated groups a net influx of plasma cells and lymphocytes, as well as a significant increase of specific IgG occurred . Concurrently, the CD4+/CD8+ ratio was found to increase after aerosol immunization . The lymphocyte subsets of IgG+ and IgA+ cells were found significantly higher in the group immunized with irradiated bacteria when compared to pigs immunized with bacterial ghosts . The latter group showed a significant increase of IgA, IgM, and a net influx of lymphoid blasts and granulocytes in the bronchoalveolar lining fluid . Although differences between the local immune responses of both immunized groups occurred, a significant increase of specific IgG and a net influx of plasma cells and lymphocytes were found to be associated with complete protection against a homologous aerosol challenge infection.

FEMS Microbiol Lett, 1999 Oct 1, 179(1), 73 - 8
Apoptosis of murine peritoneal macrophages induced by an avian pathogenic strain of Escherichia coli; Rodrigues VS et al.; The mechanisms used by avian strains of Escherichia coli to invade the respiratory epithelia, leading to septicemia in poultry, are not well-established . In this work, we show that resident murine peritoneal macrophages infected in vitro with an avian strain of E . coli underwent apoptosis 4 h after infection (55.6% of apoptosis in infected cells versus 3.5% in non-infected cells) . Heat-inactivated bacteria did not induce apoptosis and the inhibition of phagocytosis by pretreatment of cells with cytochalasin D reduced the number of apoptotic cells from 55.6 to 13.9% (P<0.05), showing that the bacteria must be intracellularly located and viable to induce apoptosis . Therefore, these data suggest that induction of macrophage apoptosis may be a pathogenic mechanism employed by avian E . coli to circumvent the host defences and invade the respiratory epithelia.

Acta Anaesthesiol Scand, 1999 Aug, 43(7), 760 - 3
Halothane decreases bacterial adherence in vitro; Batai I et al.; BACKGROUND: Adherence of pathogenic bacteria to host epithelial cells is thought to be the initial step in infection, while the presence of the commensal flora is an important host defence mechanism . Anything altering bacterial adherence to human epithelial cells may contribute to bacterial infections . The impact of anaesthesia on this first step to infection is not known . In this study the effect of halothane on bacterial adherence was investigated . METHODS: Human epithelial cells (HEp-2) and two strains of Escherichia coli were exposed to halothane 2% for 2 h . Then HEp-2 cells were coincubated with bacteria for 3 h . Bacteria attached to the epithelial cells were evaluated by light microscopy . RESULTS: Compared to the control, bacterial adherence was reduced by 37% to 56% with the different strains when HEp-2 cells were exposed to halothane . No significant difference was found when only bacteria were treated with halothane . CONCLUSION: Our results show that halothane reduces bacterial adherence to human epithelial cells in vitro . Reduced number or function of epithelial cell surface receptors may be responsible for the reduced adherence as no changes were observed when only the bacteria were exposed to halothane.

Am J Vet Res, 1999 Aug, 60(8), 937 - 41
Response of embryonic chicken lymphocytes to in ovo exposure to lymphotropic viruses; St Hill CA et al.; OBJECTIVE: To examine effects of virus exposure on embryonic lymphoid organ structure, apoptosis, and lymphoid cell subpopulations . ANIMALS: Eggs of specific pathogen free (SPF) White Leghorn chickens at embryonation day (ED) 17 . PROCEDURES: Eggs were inoculated with 2,000 plaque-forming units (PFU) of serotype 1 herpesvirus (Marek's disease virus {MDV 1}), 2,000 PFU of herpesvirus of turkeys (MDV 3), or 1,000 embryo infectious doses (EID50) of infectious bursal disease virus (IBDV) . On post-inoculation days (PID) 3 and 5, lymphoid organ to body weight ratios were determined, and bursa of Fabricius, thymus, and spleen were evaluated for lesions and apoptosis . Proportions of lymphoid cell subpopulations of PID-3 chicken embryos and 7- to 10-day-old chicks were quantitated by flow cytometry . RESULTS: Lymphoid organ weights were similar in virus-free, MDV1, and IBDV groups . Embryos inoculated with 2,000 PFU MDV 3/egg had lower bursal weights than virus-free controls . In a repeated trial, MDV 3 (1,000 PFU to 4,000 PFU) did not reduce bursal weights among groups . Histologic changes were seen in bursae after MDV 1 and IBDV inoculation . Apoptosis was greater in bursae of MDV 1-infected embryos than controls . Lymphoid cell subpopulations were similar among all groups with the exception of CD8+ and IgM+ cells in spleens of IBDV-infected 10-day-old chicks . CONCLUSIONS AND CLINICAL RELEVANCE: Infection with pathogenic strains of MDV 1 and IBDV did not alter lymphocyte subpopulations in embryos or cause complete destruction of lymphoid organs . Changes in lymphoid cell subpopulations exposed as embryos to IBDV were seen only after hatching.

J Med Microbiol, 1999 Aug, 48(8), 741 - 9
Molecular fingerprinting of Porphyromonas gingivalis by PCR of repetitive extragenic palindromic (REP) sequences and comparison with other fingerprinting methods; Teanpaisan R et al.; Knowledge of the genetic structure of populations of potentially pathogenic bacteria is important in understanding the epidemiology of diseases . Porphyromonas gingivalis is thought to be an important aetiological agent in periodontal diseases and several methods have been used for typing strains of this species . Here, PCR with primers to repetitive extragenic palindromic sequences (REP-PCR) was compared with three other widely used molecular fingerprinting techniques -- restriction endonuclease analysis (REA), ribotyping and PCR with arbitrary primers (AP-PCR) -- to type P . gingivalis isolates from healthy and diseased periodontal sites . The data obtained with all four methods were in broad agreement and, with one exception, each subject harboured a single unique genotype of P . gingivalis . REP-PCR of P . gingivalis resulted in the production of 5-10 amplicons, which gave unique electrophoretic patterns in each individual (10 REP-PCR types in 10 patients) and similar results were obtained with AP-PCR . Two isolates from one subject appeared identical by REP-PCR and AP-PCR, but could be differentiated by ribotyping, although there was only minor polymorphism . Thus, ribotyping and REA were the most discriminating methods; however, these are time-consuming and expensive relative to the PCR-based techniques . REP-PCR has the advantage that the same pair of primers is used for all species, whereas AP-PCR needs to be optimised by screening a range of primers . These results show that REP-PCR is a useful and rapid technique for typing P . gingivalis.

Rinsho Byori, 1999 Jul, 47(7), 669 - 75
{Invasive amebiasis at an institution for the mentally retarded in Hyogo Prefecture}; Ono K et al.; An outbreak of amebiasis caused by Entamoeba histolytica occurred at an institution for mentally retarded persons in Hyogo Prefecture . Twelve out of a total of 49 admitted persons exhibited E . histolytica cysts in their stool, and 13 including persons in whom no cysts had been detected showed positive serological reactions for E . histolytica infection . However, neither the cyst nor the antibody against the organism was detected in the staff members of the institution . Indirect fluorescence antibody test and sandwich enzyme-linked immunosorbent assay with a monoclonal antibody specific for pathogenic strains of E . histolytica revealed that all trophozoite strains grown from cysts in stool samples from five patients were pathogenic . Epidemiological analysis strongly suggested that a patient in the institution had been infected with an organism from a patient outside the institution, and that infection may have spread among the admitted persons due to abnormal behavior . Administration of metronidazole resulted in effective elimination of the cysts from the stool of the cyst-carriers.

Biochem Biophys Res Commun, 1999 Aug 11, 261(3), 598 - 602
Rapid and efficient inactivation of IL-6 gingipains, lysine- and arginine-specific proteinases from Porphyromonas gingivalis; Banbula A et al.; Deregulation of the cytokine network is an important adaptation of pathogenic bacteria to modulate and evade a host immune response . Here we describe that IL-6 is rapidly and efficiently cleaved and inactivated by the arginine- and lysine-specific proteinases from Porphyromonas gingivalis, referred to as RGP-A, RGP-B, and KGP . One of the primary cleavage sites for RGPs has been mapped between R18 and Q19 within the N-terminal region of the IL-6 polypeptide chain; however, both KGP and RGPs cleave IL-6 within the C-terminal region of the polypeptide chain . After these initial proteolytic cleavages, IL-6 is further degraded by each of the enzymes tested . Although KGP is the most potent IL-6-degrading proteinase, the initial C-terminal cleavage of IL-6 mediated by all gingipains is already sufficient to inactivate this cytokine . Our data are consistent with the observation that in periodontitis the IL-6 concentration is lowest in the gingival tissue adjacent to bacterial plaque, whereas significantly elevated concentrations of this cytokine are detected around the infected area . Degradation of IL-6 by gingipains may, therefore, represent an additional mechanism which influences the balance between pro- and anti-inflammatory reactions at distal versus proximal sites from the periodontal plaque .

J Periodontol, 1999 Jul, 70(7), 793 - 802
Role of oral bacteria in respiratory infection; Scannapieco FA; An association between oral conditions such as periodontal disease and several respiratory conditions has been noted . For example, recent evidence has suggested a central role for the oral cavity in the process of respiratory infection . Oral periodontopathic bacteria can be aspirated into the lung to cause aspiration pneumonia . The teeth may also serve as a reservoir for respiratory pathogen colonization and subsequent nosocomial pneumonia . Typical respiratory pathogens have been shown to colonize the dental plaque of hospitalized intensive care and nursing home patients . Once established in the mouth, these pathogens may be aspirated into the lung to cause infection . Other epidemiologic studies have noted a relationship between poor oral hygiene or periodontal bone loss and chronic obstructive pulmonary disease . Several mechanisms are proposed to explain the potential role of oral bacteria in the pathogenesis of respiratory infection: 1 . aspiration of oral pathogens (such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, etc.) into the lung to cause infection; 2 . periodontal disease-associated enzymes in saliva may modify mucosal surfaces to promote adhesion and colonization by respiratory pathogens, which are then aspirated into the lung; 3 . periodontal disease-associated enzymes may destroy salivary pellicles on pathogenic bacteria to hinder their clearance from the mucosal surface; and 4 . cytokines originating from periodontal tissues may alter respiratory epithelium to promote infection by respiratory pathogens.

Mol Ecol, 1999 Jun, 8(6), 1055 - 61
Natural selection promotes divergence of transferrin among salmonid species; Ford MJ et al.; Transferrin is an iron-binding protein that plays an important role in iron metabolism and resistance to bacterial infection in a variety of organisms . A comparison of transferrin coding sequences from four salmonid species shows that the rate of evolution at nonsynonymous sites is significantly higher than the rate at synonymous sites, suggesting that positive natural selection for new alleles has played an important role in the evolution of transferrin in some salmon species . We hypothesize that the selective agent driving rapid divergence is interactions between host transferrin and the iron-scavenging proteins of pathogenic bacteria.

Parasitol Res, 1999 Aug, 85(8-9), 692 - 9
Iron enhancement of experimental infection of mice by Tritrichomonas foetus; Kulda J et al.; The ability of a microbial invader to acquire iron from its vertebrate host has been recognized as an important virulence mechanism in some pathogenic bacteria . We examined the involvement of similar mechanisms in an experimental infection of mice by a protozoan pathogen of cattle, Tritrichomonas foetus . In a series of experiments, outbred ICR mice were inoculated intraperitoneally with two strains of T . foetus, the moderately virulent KV-1 (approximately 5% mortality rate) and the highly virulent LUB-1MIP (approximately 80% mortality rate) . Treatment of mice with ferric ammonium citrate (FeAC) (100 mg/kg per day intraperitoneally) increased the mortality rate caused by the KV-1 infection up to the level determined for the highly virulent strain . The treatment effect was dose dependent and required early administration of FeAC after inoculation of parasites and its continued supply for at least 3 subsequent days . Daily sampling of peritoneal exudate showed that the infection-enhancing effect of iron overload was associated with a stimulation of parasite multiplication, which in the case of KV-1 infection was strongly suppressed in untreated mice . Consistent with these findings, the strain of lower virulence (KV-1) showed considerably lower efficiency accumulating radiolabeled iron from transferrin and a low-molecular source {Fe(III)nitrilotriacetic acid} in vitro . The results indicate an involvement of iron uptake mechanisms by the parasite as a virulence factor in T . foetus infection.

Structure Fold Des, 1999 Jul 15, 7(7), 745 - 56
Structure of L-aspartate oxidase: implications for the succinate dehydrogenase/fumarate reductase oxidoreductase family; Mattevi A et al.; BACKGROUND: Given the vital role of NAD+ in cell metabolism, the enzymes involved in bacterial de novo NAD+ biosynthesis are possible targets for drug design against pathogenic bacteria . The first reaction in the pathway is catalysed by L-aspartate oxidase (LASPO), a flavoenzyme that converts aspartate to iminoaspartate using either molecular oxygen or fumarate as electron acceptors . LASPO has considerable sequence homology with the flavoprotein subunits of succinate dehydrogenase (SDH) and fumarate reductase (FRD) . RESULTS: The crystal structure of the apoform of LASPO from Escherichia coli has been determined to 2.2 A resolution . The enzyme shows a novel fold for an FAD-dependent protein, comprising a three-domain structure: an FAD-binding domain with the dinucleotide-binding fold, a C-terminal three-helical bundle domain, and an alpha + beta capping domain, which is topologically similar to the small subunit of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase . The interface between the FAD-binding and capping domains defines a cleft in which the active site is located . CONCLUSIONS: A number of strictly conserved residues present in all three domains indicate that LASPO, SDH and FRD share the same overall folding topology . Many of these conserved residues are in the FAD-binding site and active centre, suggesting a similar catalytic mechanism . Thus, LASPO, SDH and FRD form a class of functionally and structurally related oxidoreductases that are all able to reduce fumarate and to oxidise a dicarboxylate substrate.

Virology, 1999 Aug 1, 260(2), 295 - 307
Derivation and biological characterization of a molecular clone of SHIV(KU-2) that causes AIDS, neurological disease, and renal disease in rhesus macaques; Liu ZQ et al.; Previously, we described the derivation of a pathogenic strain of simian-human immunodeficiency virus (SHIV(KU-2)) consisting of the tat, rev, vpu, and env genes of HIV-1 (strain HXB2) in a genetic background of SIV(mac)239 that causes AIDS and productive infection of the CNS in rhesus macaques (Macca mulatta) (Raghavan et al., 1997, Brain Pathol . 7, 851-861) . We report here on the characterization of a molecular clone of SHIV(KU-2), designated SHIV(KU-2MC4), that caused CD4(+) T cell loss as well as neurological and renal disease in macaques . DNA sequence analysis of selected SIV regions of SHIV(KU-2MC4) revealed 10 nucleotide changes in the LTR, whereas Gag, Vif, Vpr, Vpx, and Nef had 1, 1, 1, 2, and 13 predicted amino acid substitutions, respectively, compared to SIV(mac)239 . DNA sequence analysis of HIV-1 derived regions of SHIV(KU-2MC4) revealed 2, 1, 2, and 18 predicted amino acid substitutions in the Tat, Rev, Vpu, and Env proteins, respectively, when compared to SHIV-4 . Unlike the parental SHIV-4, which is not tropic for macrophages, SHIV(KU-2MC4) replicated efficiently in macrophage cultures as determined by p27 assays . However, despite the numerous changes in the Env protein and newly acquired tropism for macrophages, SHIV(KU-2MC4), like the parental SHIV-4, used CXCR4 exclusively as its coreceptor for entry into susceptible cells . Inoculation of SHIV(KU-2MC4) into two rhesus macaques resulted in severe infection in which the numbers of circulating CD4(+) T cells in the blood declined rapidly by 2 weeks postinoculation and virus producing cells in the peripheral blood mononuclear cells were identified throughout the course of infection . At the time of euthanasia (20 and 22 weeks), both macaques had lost a significant amount of weight and had no circulating CD4(+) T cells . In addition, one macaque developed intension tremors and uncoordinated movements . Virological examination of tissues at necropsy revealed active virus replication in both lymphoid and nonlymphoid tissues such as the lung and brain . Histological examination revealed that the induced immunodeficiency was associated with lymphoid depletion of the lymph nodes and spleen, opportunistic infections, lentiviral encephalitis, and severe glomerulosclerosis of the kidney . This molecular clone will serve as the basis for analyzing the molecular determinants through which SHIV(KU-2) causes severe CD4(+) T cell loss, neurological disease, and SHIV nephropathy in rhesus macaques .

Vaccine, 1999 May 4, 17(18), 2265 - 74
Baculovirus-derived hemagglutinin vaccines protect against lethal influenza infections by avian H5 and H7 subtypes; Crawford J et al.; Baculoviruses were engineered to express hemagglutinin (HA) genes of recent avian influenza (AI) isolates of the H5 and H7 subtypes . The proteins were expressed as either intact (H7) or slightly truncated versions (H5) . In both cases purified HA proteins from insect cell cultures retained hemagglutination activity and formed rosettes in solution, indicating proper folding . Although immunogenic in this form, these proteins were more effective when administered subcutaneously in a water-in-oil emulsion . One or two-day-old specific pathogen free (SPF) White Rock chickens, free of maternal AI antibodies, responded with variable serum HI titers, but in some cases the titers were comparable to those achieved using whole virus preparations . Vaccination of three-week-old chickens with 1.0 microg of protein per bird generated a more consistent serum antibody response with an average geometric mean titer (GMT) of 121 (H5) and 293 (H7) at 21 days postvaccination . When challenged with highly pathogenic strains of the corresponding AI subtypes, the vaccinated birds were completely protected against lethal infection and in some cases exhibited reduced or no cloacal shedding at 3 days postinfection . Vaccine protocols employing these recombinant HA proteins will not elicit an immune response against internal AI proteins and thus will not interfere with epidemiological surveys of natural influenza infections in the field.

Mol Gen Mikrobiol Virusol, 1999, (2), 22 - 9
{Participation of mobile elements in formation of properties of pathogenic bacteria}; Romanova IuM et al.; Published reports about structural organization of genes coding for pathogenicity factors are reviewed . Many of such genes are often united into "virulence blocks" or "pathogenicity islands" and are surrounded by mobile genetic elements, promoting their transposition between related bacteria genomes and leading to changes in virulence in the course of evolution . Data on the similarity of nucleotide sequences of virulence genes in different bacteria are presented, despite differences in their localization in the relevant genomes . The role of rRNA genes in dissemination of virulence genes among different bacteria during transduction or conjugation is shown.

Curr Biol, 1999 Jul 1, 9(13), 703 - 6
A missing metabolic pathway in the cattle tick Boophilus microplus; Braz GR et al.; Heme proteins are involved in a wide variety of biological reactions, including respiration, oxygen transport and oxygen metabolism {1} . The heme prosthetic group is synthesized in almost all living organisms except for a few pathogenic bacteria and trypanosomatids that use blood as food {2} {3} . There is a general belief that all nucleated animal cells synthesize heme {1} {4} . However, blood-feeding arthropods ingest enormous amounts of vertebrate blood in a single meal and the heme pathway has not been studied in these animals . We have examined heme synthesis in two hematophagous arthropods - the blood-sucking bug Rhodnius prolixus and the cattle tick Boophilus microplus . We show that R . prolixus makes heme and has a fully operative heme biosynthetic pathway, while B . microplus does not . To our knowledge, this is the first report of an animal that does not synthesize its own heme and relies solely on the recovery of heme present in the diet . Because of the inability of Boophilus to synthesize heme and its ability to deal efficiently with large amounts of free heme, we propose this organism as a good model for studying heme transport and reutilization in animal cells.

J Mol Biol, 1999 Jul 9, 290(2), 459 - 70
3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin; Reyrat JM et al.; Pathogenic strains of Helicobacter pylori produce a potent exotoxin, VacA, which intoxicates gastric epithelial cells and leads to peptic ulcer . The toxin is released from the bacteria as a high molecular mass homo-oligomer of a 95 kDa polypeptide which undergoes specific proteolytic cleavage to 37 kDa and 58 kDa subunits . We have engineered a strain of H . pylori to delete the gene sequence coding for the 37 kDa subunit . The remaining 58 kDa subunit is expressed efficiently and exported as a soluble dimer that is non-toxic but binds target cells in a manner similar to the holotoxin . A 3D reconstruction of the molecule from electron micrographs of quick-freeze, deep-etched preparations reveals the contribution of each building block to the structure and permits the reconstruction of the oligomeric holotoxin starting from individual subunits . In this model P58 subunits are assembled in a ring structure with P37 subunits laying on the top . The data indicate that the 58 kDa subunit is capable of folding autonomously into a discrete structure recognizable within the holotoxin and containing the cell binding domain .

Biochemistry, 1999 Jun 29, 38(26), 8304 - 12
Solution structure of the N-terminal F1 module pair from human fibronectin; Potts JR et al.; Multiple sites within the N-terminal domain (1-5F1) of fibronectin have been implicated previously in fibronectin matrix assembly, heparin binding, and binding to cell surface proteins of pathogenic bacteria . The solution structure of 1F1(2)F1, the N-terminal F1 module pair from human fibronectin, has been determined using NMR spectroscopy . Both modules in the pair conform to the F1 consensus fold . In 4F1(5)F1, the only other F1 module pair structure available, there is a well-defined intermodule interface; in 1F1(2)F1, however, there is no detectable interface between the modules . Comparison of the backbone 15N- inverted question mark1H inverted question mark NOE values for both module pairs confirms that the longer intermodule sequence in 1F1(2)F1 is flexible and that the stabilization of the 4F1 C-D loop observed in 4F1(5)F1, as a result of the intermodule interface, is not observed in 1F1(2)F1.

Ital J Gastroenterol Hepatol, 1999 Apr, 31(3), 186 - 91
Food allergy and Helicobacter pylori infection; Figura N et al.; BACKGROUND: Most antigens reach the immune system through mucosae . Gastrointestinal mucosa is a barrier for alimentary antigens . Inflammatory processes, such as Helicobacter pylori-associated gastritis, could alter the integrity of the gastric barrier, increase the mucosal permeability, and enhance crossing of food antigens which may stimulate allergic reactions . PURPOSE: The aim of this study was to establish whether patients with symptomatic food allergy and detectable immunoglobulin E (IgE) to alimentary antigens were infected by Helicobacter pylori more often than controls, and to determine the phenotype of the infecting Helicobacter pylori . PATIENTS AND METHODS: Thirty-eight consecutive patients with symptomatic food allergy and serum IgE to alimentary antigens, and 53 consecutive age-matched controls (subjects without food allergy and detectable levels of IgE anti-alimentary antigens) living in the same area and attending the same institution were investigated serologically to determine the prevalence of Helicobacter pylori infection, and an immune response to CagA, a marker of the most pathogenic strains . IgE to alimentary allergens were measured by a commercial kit . RESULTS: The prevalence of Helicobacter pylori infection in patients with food allergy and controls was similar (42.1% and 47.1%, respectively) . Anti-CagA antibodies in Helicobacter pylori-infected persons were detected in 62.5% of patients with food allergy, and 28.0% of controls (p = 0.030, odds ratio = 4.29, RR = 2.23) . The mean IgE level to the most common alimentary antigens was increased in CagA-positive, with respect to the CagA-negative, patients . CONCLUSIONS: The enhanced mucosal and inflammatory lesions commonly found in individuals infected by CagA-positive Helicobacter pylori strains could increase the epithelial permeability and render non-selective the passage of allergens which, in atopic persons, could directly stimulate an IgE response . Infection by CagA-positive Helicobacter pylori may increase the risk of food allergy.

Yale J Biol Med, 1998 Mar-Apr, 71(2), 63 - 73
Structure, function and localization of Helicobacter pylori urease; Dunn BE et al.; Helicobacter pylori is the causative agent of most cases of gastritis . Once acquired, H . pylori establishes chronic persistent infection; it is this long-term infection that, is a subset of patients, leads to gastric or duodenal ulcer, gastric cancer or gastric MALT lymphoma . All fresh isolates of H . pylori express significant urease activity, which is essential to survival and pathogenesis of the bacterium . A significant fraction of urease is associated with the surface of H . pylori both in vivo and in vitro . Surface-associated urease is essential for H . pylori to resist exposure to acid in the presence of urea . The mechanism whereby urease becomes associated with the surface of H . pylori is unique . This process, which we term "altruistic autolysis," involves release of urease (and other cytoplasmic proteins) by genetically programmed autolysis with subsequent adsorption of the released urease onto the surface of neighboring intact bacteria . To our knowledge, this is the first evidence of essential communal behavior in pathogenic bacteria; such behavior is crucial to understanding the pathogenesis of H . pylori.

FEBS Lett, 1999 Jun 4, 452(1-2), 16 - 21
Molecular and cellular activities of Helicobacter pylori pathogenic factors; Montecucco C et al.; Stomach infection with pathogenic strains of Helicobacter pylori causes in some patients severe gastroduodenal diseases . These bacteria produce various virulence factors and, here, we review the recent acquisition on the biochemical mode of action of three major factors . We discuss the role of urease both as buffer of the stomach pH and as source of ammonia . The vacuolating toxin alters the endocytic pathway of non-polarized cells, inducing the release of acid hydrolases, the depression of extracellular ligand degradation and of antigen processing and, in the presence of ammonia, swelling of late-prelysosomal compartments . In polarized epithelial monolayers, vacuolating toxin induces an increase of the paracellular permeability, independent of vacuolation . The neutrophil activating protein induces the production of oxygen radicals in human neutrophils and could contribute to the damage of the stomach mucosa . The activities of these factors are discussed in terms of the need of the bacterium of increasing the supply of nutrients from the stomach lumen and from the mucosa.

Trop Anim Health Prod, 1999 Apr, 31(2), 75 - 81
Susceptibility of local Nigerian and exotic chickens to infectious bursal disease by contact exposure; Okoye JO et al.; One hundred 6-week-old susceptible cockerels were inoculated with a pathogenic strain of infectious bursal disease virus (IBDV) and kept in the same pen as 100 each of 6-week-old pullets, local chickens and broilers . The cockerels developed depression and diarrhoea on day 3 post inoculation (PI) and most of the pullets and some of the local chickens and broilers showed similar signs on day 4 PI . Loss in weight was severe and similar in the pullets and local chickens, being significantly greater than that in the broilers from days 3-11 PI . The total mortality was 85%, 66.7%, 30% and 20% for the pullets, cockerels, local chickens and broilers, respectively . The lesions were more severe in the pullets and local chickens than in the broilers . IBDV antigen and antibody were detected, respectively, in all the bursal and serum samples from the infected chickens tested . The contact exposure method used in this study simulates better what happens in nature than inoculation with IBDV . The reduced mortality observed among the local chickens, compared with that (61.5%) seen in earlier studies using intraocular inoculation of IBDV, may have been due to behavioural differences that tend to result in their ingesting a relatively low dose of the virus.

Rapid Commun Mass Spectrom, 1999, 13(11), 1067 - 71
Fingerprinting of Helicobacter pylori strains by matrix-assisted laser desorption/ionization mass spectrometric analysis; Nilsson CL; Helicobacter pylori is an important human gastrointestinal pathogenic bacterium which is believed to colonize approximately one-half of the world's population . Different strains of H . pylori possess virulence proteins for tissue colonization, host evasion and tissue damage . The bacteria display genomic instabilities that include gene rearrangements and gene exchange . Recently, methods for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) have been established for monitoring biomarkers in bacterial extracts . In order to establish a set of H . pylori specific biomarkers as well as a set of strain-specific biomarkers, we examined lysates and extracts from six different strains of this bacterium . Three different MALDI matrices, alpha-cyano-4-hydroxycinnamic acid, sinapinic acid, and ferulic acid were tested for sensitivity of analysis . Also, the effects of solubilizing analytes with the detergent n-octyl-beta-D-glucopyranoside were explored . It was found that a set of H . pylori specific, and a probable set of strain-specific, biomarkers could be established using MALDI-TOFMS . The use of H . pylori fingerprinting by MALDI may be useful for typing of these bacteria, or for studying genetic drift at the phenotypic level in specific strains.

Virology, 1999 Jun 20, 259(1), 166 - 75
Pathogenicity and comparative evolution in vivo of the transitional quasispecies SIVsmmPBj8; Tao B et al.; During 14 months of infection of a pig-tailed macaque, the acutely lethal simian immunodeficiency virus SIVsmmPBj14 (SIV-PBj14) evolved from the minimally pathogenic strain SIVsmm9 . The virus isolated at 8 months (SIV-PBj8) exhibited properties of both SIVsmm9 and SIV-PBj14, indicating that a phenotypic transition occurred between 6 and 10 months . To assess the influence that this new composition of biologic properties might have on pathogenicity, three pig-tailed macaques were inoculated intravenously with SIV-PBj8 . Although no animals developed the severe acute disease syndrome typical of SIV-PBj14, all had high levels of viremia and died of AIDS at 4, 10 . 5, and 32 months . Characterization of the SIV-PBj8-derived quasispecies that evolved in these macaques showed that at 4 days after inoculation, viruses from all three animals exhibited in vitro properties different from those of the inoculum . By 4 months, the initial phenotypic profiles had changed, with the quasispecies in plasma from the animal (J90232) that died at this time most closely resembling SIV-PBj14, not SIV-PBj8 . Phylogenetic trees of the gp41/Nef region of viruses in 4-month plasma from J90232 revealed three distinct populations with high bootstrap values: one group branched with SIVsmm9, one with SIV-PBj14, and one with SIV-PBj8 (ratio of clones, 5:9:5) . Nucleotide sequence analysis suggested that some members of the original SIV-PBj8 quasispecies may have been evolving toward a SIV-PBj14-like genotype at the time macaque J90232 died . The use of SIV-PBj8, which was more pathogenic than SIVsmm9, but less pathogenic than SIV-PBj14, may provide the optimal genetic background on which to identify the minimal, multigenic determinants of the SIV-PBj14 phenotype . The results of our studies on SIV-PBj14 indicate that in some, but not all, cases of primate lentivirus infection more pathogenic variants evolve, selectively proliferate, and more than likely contribute to disease progression .

Br J Nurs, 1999 Mar 11-24, 8(5), 313 - 7
Algosteril calcium alginate dressing for moderate/high exudate; Williams C; Algosteril is a new alginate dressing manufactured by Les Laboratoires BROTHIER and distributed by Beiersdorf Medical . It is a natural, pure, non-woven dressing made from calcium alginate fibres . It complements other products in the Beiersdorf wound care family such as Cutinova, Cutifilm and Cutisorb . Algosteril rapidly absorbs and retains wound fluid to form an integral gellified structure, thereby maintaining an ideal moist wound healing environment . It traps and immobilizes pathogenic bacteria in the network of gellified fibres, stimulates macrophage activity and activates platelets, resulting in haemostasis and accelerated wound healing.

AIDS Res Hum Retroviruses, 1999 May 20, 15(8), 721 - 9
Sequential analysis of apoptosis induction in peripheral blood mononuclear cells and lymph nodes in the early phase of pathogenic and nonpathogenic SIVmac infection; Iida T et al.; To investigate the role of apoptosis in the early phase of HIV infection, we used macaques infected with simian immunodeficiency virus strain mac (SIVmac) as a primate model and examined sequentially the characteristics of apoptosis of lymphocytes in peripheral blood mononuclear cells (PBMCs) and lymph nodes in the early phase of SIVmac infection . Five macaques infected with a pathogenic strain of SIV, SIVmac239, were analyzed during the first 4 weeks after infection . Peripheral CD4+ and CD8+ cells transiently decreased at 1 week postinfection . The percentage of apoptotic cells in cultured PBMCs increased from about 2 weeks postinfection . The number of apoptotic cells in lymph node sections was higher on days 13 and 28 postinfection than before infection and on day 5 postinfection . Fas antigen expression on peripheral lymphocytes was upregulated from day 8 postinfection . These results indicate that apoptosis is induced about 2 weeks after SIVmac239 infection, following the upregulation of Fas antigen expression on lymphocytes . Since apoptosis was induced about 1 week after the decrease in peripheral CD4+ and CD8+ cell counts, it appears that the apoptosis induction does not play an important role in the transient lymphopenia in the early phase of SIVmac infection . In macaques infected with a nonpathogenic derivative of SIVmac239, SIVmac delta nef, apoptosis of lymphocytes was induced as it was in SIVmac239-infected macaques, but to a lesser degree, suggesting a correlation between the extent of apoptosis induction in lymphocytes in the early phase of SIVmac infection and the pathogenicity of SIVmac.

J Gen Intern Med, 1999 Jun, 14(6), 373 - 5
Adhesive tape and intravascular-catheter-associated infections; Redelmeier DA et al.; Adhesive tape is placed in close contact with intravascular catheters for extended periods and could theoretically contribute to local infections . We found that 74% of specimens of tape collected in one hospital were colonized by pathogenic bacteria . However, only 5% of specimens had significant growth from an inner layer obtained by discarding the outside layer from each roll . We suggest that adhesive tape is a potential source of pathogenic bacteria and that discarding the outer layer from a partially used roll might be a simple method for reducing the risk of infection to patients.

Infect Immun, 1999 Jun, 67(6), 3066 - 72
Acute clinical disease in cats following infection with a pathogenic strain of Bartonella henselae (LSU16); O'Reilly KL et al.; Bartonella henselae is the causative agent of human cat scratch disease as well as several serious sequelae of infections, including bacillary angiomatosis and bacillary peliosis . Conflicting reports describe the pathogenesis of B . henselae in the cat . In this study, we characterized a strain of B . henselae termed LSU16 . This strain was isolated on rabbit blood agar from a naturally infected 10-month-old female cat during a recurrent episode of bacteremia . The bacterial species was confirmed by PCR-restriction fragment length polymorphism analysis . Nine cats were infected intradermally with 5 x 10(7) CFU of LSU16, and clinical signs, antibody responses, and bacteremia were monitored . All nine cats developed raised, erythematous areas at the site of inoculation within 72 h postinoculation; the swelling peaked at 14 days postinfection and was not palpable by 28 days postinfection . Fever developed in all nine cats between 6 and 16 days postinfection and lasted for 1 to 8 days . Between 6 and 16 days postinfection, all nine cats experienced lethargy which persisted 5 to 18 days . Seven of nine cats were bacteremic by day 7, and all nine cats had become bacteremic by 14 days postinfection . Bacteremia peaked at 14 to 28 days postinfection in all cats . In six of the nine infected cats, bacterial numbers reached nondetectable levels during the 7th week postinfection; however, a single animal maintained bacteremia to 18 weeks postinfection . All nine cats developed strong antibody responses to B . henselae, as determined by Western blot analysis and enzyme-linked immunosorbent assay . Subsequently, three naive cats were injected intradermally with blood from cats infected with LSU16 from a pure culture, and five naive cats were injected with feces from fleas which had been feeding on cats infected with a pure culture of LSU16 . These cats developed signs similar to those described in the previous experiment and were euthanized at 5 weeks postinfection . We conclude that B . henselae LSU16 is a virulent strain of B . henselae in cats and propose that the virulence of B . henselae in cats is strain dependent.

Infect Immun, 1999 Jun, 67(6), 2841 - 6
Inhibition of osteoblastic cell differentiation by lipopolysaccharide extract from Porphyromonas gingivalis; Kadono H et al.; Lipopolysaccharide from Porphyromonas gingivalis (P-LPS), an important pathogenic bacterium, is closely associated with inflammatory destruction of periodontal tissues . P-LPS induces the release of cytokines and local factors from inflammatory cells, stimulates osteoclastic-cell differentiation, and causes alveolar bone resorption . However, the effect of P-LPS on osteoblastic-cell differentiation remains unclear . In this study, we investigated the effect of P-LPS extract prepared by the hot-phenol-water method, on the differentiation of primary fetal rat calvaria (RC) cells, which contain a subpopulation of osteoprogenitor cells, into osteoblastic cells . P-LPS extract significantly inhibited bone nodule (BN) formation and the activity of alkaline phosphatase (ALPase), an osteoblastic marker, in a dose-dependent manner (0 to 100 ng of P-LPS extract per ml) . P-LPS extract (100 ng/ml) significantly decreased BN formation to 27% of the control value and inhibited ALPase activity to approximately 60% of the control level on days 10 to 21 but did not affect RC cell proliferation and viability . P-LPS extract time-dependently suppressed the expression of ALPase mRNA, with an inhibitory pattern similar to that of enzyme activity . The expression of mRNAs for osteocalcin and osteopontin, matrix proteins related to bone metabolism, was markedly suppressed by P-LPS extract . Furthermore, P-LPS extract increased the expression of mRNAs for CD14, LPS receptor, and interleukin-1beta in RC cells . These results indicate that P-LPS inhibits osteoblastic-cell differentiation and suggest that LPS-induced bone resorption in periodontal disease may be mediated by effects on osteoblastic as well as osteoclastic cells.

APMIS, 1999 May, 107(5), 455 - 73
Infection, inflammation and sleep: more pieces to the puzzle of sudden infant death syndrome (SIDS); Blackwell CC et al.; Risk factors for sudden infant death syndrome (SIDS) parallel those for respiratory tract infections; however, infectious agents suggested to be involved in SIDS do not fulfil Koch's postulates . No single agent has been identified in all cases and there is no suitable animal model for SIDS which could be used to test the candidate organisms . Based on epidemiological and experimental work by our group and others, we suggested some SIDS deaths are due to pathophysiological responses elicited by combinations of microbial products and/or cigarette smoke during a developmental stage when infants' endocrine responses are less able to "damp down" the effects of inflammatory mediators . Here we review evidence from studies on interactions between developmental and environmental risk factors that could affect 1) mucosal colonization of infants by potentially pathogenic bacteria, and 2) induction and control of infants', inflammatory responses to infectious agents . New evidence suggests that there are genetic factors involved in the induction of inflammatory responses to some bacterial antigens implicated in SIDS . Further investigation of the role of infection, exposure to cigarette smoke and inflammation in infants, particularly differences in ethnic groups at increased risk of SIDS, could lead to new insights into the events leading to a fatal outcome and perhaps to new intervention schemes to reduce further the incidence of these deaths.

Int Endod J, 1997 Mar, 30(2), 102 - 14
Tissue response to potential root-end filling materials in infected root canals; Chong BS et al.; The tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol) were compared with that to amalgam . In 27 premolar teeth of beagle dogs (54 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periapical lesions . On each root, an apicectomy was performed and root-end cavities prepared to receive fillings of each material . The teeth and surrounding jaw were removed after 8 weeks (24 roots) and 4 weeks (30 roots); and they were prepared for histological examination . The tissue response to amalgam fillings after 4 and 8 weeks was marked by moderate or severe inflammation on all roots, and extended > 0.5 mm in 10 out of 18 roots . In contrast, after 8 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation while the tissue response to Vitrebond was the best of the three materials, and was also less extensive . After 4 weeks, the overall best tissue response was with Kalzinol, followed closely by Vitrebond . The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were statistically significant (P < 0.01) . Similarly, the differences between materials for both time periods with no inflammation or inflammation extending < 0.2 mm when compared with that with inflammation extending > 0.2 mm (< or = 0.5 mm or > 0.5 mm) were statistically significant (P < 0.01) . Both Vitrebond and Kalzinol have potential as root-end filling materials as the tissue response was considerably more favourable than that to amalgam.

Lakartidningen, 1999 Apr 21, 96(16), 1965 - 6
{Fluoroquinolone resistance of human pathogenic bacteria . Resistant E coli now appearing in Sweden}; Osterlund A et al.; Fluoroquinolone-resistance is a growing international problem . Warnings have earlier been issued concerning the risk of resistance development due to excessive fluoroquinolone prescription . The development of resistance among E . coli strains isolated from primary care patients with UTI is now apparent in Sweden . So far the majority of these strains manifest only low-level resistance . However, in view of the risk of high-level resistance developing among these strains further exposed to fluoroquinolones, it is important to think twice before prescribing these drugs.

Acta Crystallogr D Biol Crystallogr, 1999 Jun, 55 ( Pt 6), 1198 - 200
Crystallization and preliminary X-ray diffraction analysis of a biologically active fragment of CD55; Lea S et al.; Crystals have been grown of two of the domains of CD55 . This is the first report of crystallization of a short consensus repeat (SCR) domain containing protein . CD55 is a widely expressed polymorphic glycoprotein, which functions as a complement regulator by inhibiting assembly and promoting destruction of C3 and C5 convertases . As a key regulator of complement, CD55 is implicated in the hyperacute rejection of xenografts from pigs into primates . It is also commonly hijacked as a receptor by viruses (e.g . medically important echoviruses and coxsackieviruses) and bacterial pathogens (e.g . certain pathogenic strains of Escherichia coli) . Here, crystallization of a virus-binding fragment expressed in yeast, consisting of two of the four extracellular SCR domains of CD55, is reported . The recombinant domains have been crystallized in 30% polyethylene glycol (PEG), 0.2 M sodium acetate, 0.1 M sodium acetate trihydrate pH 4.6 using the sitting-drop vapour-diffusion method . Two crystal forms are observed (orthorhombic and monoclinic) and a native data set to 1.65 A resolution has been collected from the monoclinic form at the Synchrotron Radiation Source, Daresbury, UK.

J Esthet Dent, 1998, 10(5), 265 - 71
Periodontal diseases and dental implants in older adults; Wilson TG Jr et al.; Older adults present special problems for the dentist trying to establish or reestablish esthetics . Periodontal diseases are of concern for this population since tooth loss from these widespread problems increases with age . In general, this loss occurs because of increased exposure time to pathogenic bacteria, not some change inherent in the body brought on by the aging process . The profession has begun to place more emphasis on systemic risk factors and their role in modifying periodontal inflammation . The current thinking is that bacteria are necessary to initiate and sustain periodontal diseases, but the clinical manifestation is dictated to a significant extent by systemic factors . Smoking, diabetes, and being positive for the interleukin-1 genotype predispose the patient to developing more severe disease . For those older adults who lose teeth, dental implants have emerged as reliable replacements, and concerns about placing these devices in patients who have lost teeth as a result of periodontitis appear to be largely unfounded.

Front Biosci, 1999 May 01, 4, D433 - 56
Conjugative transfer in the dissemination of beta-lactam and aminoglycoside resistance; Waters VL; The dissemination of antibiotic resistance among pathogenic bacteria can be attributed largely to conjugative DNA transfer . The general category of conjugative transfer includes both bacterial plasmid conjugation and the transfer of nonreplicative conjugative transposons . Prototypes for these two systems are the plasmid RK2 and the conjugative transposon Tn916 . To address the long-term problem of the increasing prevalence and severity of antibiotic resistance, strategies aimed against conjugative transfer are needed, but their development will require a greater understanding of conjugative resistance gene acquisition . Overviews of the two conjugative transfer systems are presented, to summarize and compare current concepts . Observations regarding transfer of conjugative transposons is consistent with the prevailing model for plasmid conjugation, that is, by the transfer of a single-stranded DNA molecule from the donor to the recipient bacterium, and the generation of the single strand by rolling circle DNA replication . The relevance of vegetative plasmid replication and host range to the spread of multiple drug resistance is discussed, and clinical examples of conjugative transfer of multiple antibiotic resistance illustrate the severity of the current situation . Possible directions, traditional and innovative, are offered to address the conjugative transfer problem in drug resistance, and potentially to break the cycle of antibiotic development followed by the bacterial resistance gene acquisition.

J Clin Periodontol, 1999 Apr, 26(4), 257 - 60
Tissue necrosis after subgingival irrigation with fluoride solution; Sjostrom S et al.; Irrigation of periodontal pockets with fluoride solution after scaling and root planing is occasionally recommended to inhibit the growth of pathogenic bacteria in the periodontal pocket . At the same time, irrigation enables mechanical removal of loosely adhering plaque and debris . Due to its toxicity, fluoride solution deposited in the periodontium may lead to tissue damage . We report in this paper, a case of extensive periodontal tissue necrosis and permanent loss of alveolar bone after irrigation of periodontal pockets with stannous fluoride solution . The literature on the toxic effects of fluoride on the local tissues is briefly reviewed and arguments for a re-evaluation of the use of stannous fluoride for pocket irrigation are provided.

Trends Microbiol, 1999 Mar, 7(3), 111 - 5
Bacterial tellurite resistance; Taylor DE; Tellurium compounds are used in several industrial processes, although they are relatively rare in the environment . Genes associated with tellurite resistance (TeR) are found in many pathogenic bacteria . Tellurite can be detoxified through interactions with cellular thiols, such as glutathione, or a methyltransferase-catalyzed reaction, although neither process appears involved in plasmid-mediated TeR.

Virology, 1999 Apr 25, 257(1), 15 - 23
Hyaluronan synthesis in virus PBCV-1-infected chlorella-like green algae; Graves MV et al.; We previously reported that the chlorella virus PBCV-1 genome encodes an authentic, membrane-associated glycosyltransferase, hyaluronan synthase (HAS) . Hyaluronan, a linear polysaccharide chain composed of alternating beta1,4-glucuronic acid and beta1, 3-N-acetylglucosamine groups, is present in vertebrates as well as a few pathogenic bacteria . Studies of infected cells show that the transcription of the PBCV-1 has gene begins within 10 min of virus infection and ends at 60-90 min postinfection . The hyaluronan polysaccharide begins to accumulate as hyaluronan-lyase sensitive, hair-like fibers on the outside of the chlorella cell wall by 15-30 min postinfection; by 240 min postinfection, the infected cells are coated with a dense fibrous network . This hyaluronan slightly reduces attachment of a second chlorella virus to the infected algae . An analysis of 41 additional chlorella viruses indicates that many, but not all, produce hyaluronan during infection .

J Periodontal Res, 1999 Feb, 34(2), 70 - 8
In vitro studies of lymphocyte apoptosis induced by the periodontal pathogen Porphyromonas gingivalis; Geatch DR et al.; Apoptosis has a physiological role in lymphocyte development and function serving to remove self-reactive T-cells in the thymus as well as activated peripheral T-cells when they are no longer required in the immune response . Evidence from the study of several pathogenic bacteria indicate that induction of premature cell death by apoptosis may be an important pathogenic mechanism promoting infection, inflammation and concomitant disease . In this paper we demonstrate that cultures of the periodontal pathogen Porphyromonas gingivalis (P . gingivalis) promote lymphocyte apoptosis in peripheral blood mononuclear cells (PBMC) . We have used assays designed to investigate the different molecular and cellular changes associated with apoptosis . Thus flow cytometry revealed that whole cultures of P . gingivalis promoted cell shrinkage in the lymphocyte fraction of PBMC and analysis of hypodiploidy confirmed that the cellular changes were associated with nuclear changes characteristic of apoptosis . We also found that apoptosis was promoted in PBMC exposed to both whole P . gingivalis cultures and culture supernatant but not washed bacterial cells; this indicates that molecule(s) secreted into the medium were responsible for this activity and not a factor intrinsic to the bacterial cell . Furthermore heat treatment has no effect on the ability of P . gingivalis cultures to induce lymphocyte apoptosis . In summary, a soluble heat stable component of the supernatant from P . gingivalis cultures promotes lymphocyte apoptosis . These data establish the principle that bacteria-induced apoptosis may be an important feature of the pathogenesis of periodontal disease.

Nat Struct Biol, 1999 Apr, 6(4), 366 - 73
NMR structure of the Tn916 integrase-DNA complex; Wojciak JM et al.; The integrase protein catalyzes the excision and integration of the Tn916 conjugative transposon, a promiscuous genetic element that spreads antibiotic resistance in pathogenic bacteria . The solution structure of the N-terminal domain of the Tn916 integrase protein bound to its DNA-binding site within the transposon arm has been determined . The structure reveals an interesting mode of DNA recognition, in which the face of a three-stranded antiparallel beta-sheet is positioned within the major groove . A comparison to the structure of the homing endonuclease I-Ppol-DNA complex suggests that the three-stranded sheet may represent a new DNA-binding motif whose residue composition and position within the major groove are varied to alter specificity . The structure also provides insights into the mechanism of conjugative transposition . The DNA in the complex is bent approximately 35 degrees and may, together with potential interactions between bound integrase proteins at directly repeated sites, significantly bend the arms of the transposon.

J Bacteriol, 1999 Apr, 181(8), 2477 - 84
Isolation of Helicobacter pylori genes that modulate urease activity; McGee DJ et al.; Helicobacter pylori urease, a nickel-requiring metalloenzyme, hydrolyzes urea to NH3 and CO2 . We sought to identify H . pylori genes that modulate urease activity by constructing pHP8080, a plasmid which encodes both H . pylori urease and the NixA nickel transporter . Escherichia coli SE5000 and DH5alpha transformed with pHP8080 resulted in a high-level urease producer and a low-level urease producer, respectively . An H . pylori DNA library was cotransformed into SE5000 (pHP8080) and DH5alpha (pHP8080) and was screened for cotransformants expressing either lowered or heightened urease activity, respectively . Among the clones carrying urease-enhancing factors, 21 of 23 contained hp0548, a gene that potentially encodes a DNA helicase found within the cag pathogenicity island, and hp0511, a gene that potentially encodes a lipoprotein . Each of these genes, when subcloned, conferred a urease-enhancing activity in E . coli (pHP8080) compared with the vector control . Among clones carrying urease-decreasing factors, 11 of 13 clones contained the flbA (also known as flhA) flagellar biosynthesis/regulatory gene (hp1041), an lcrD homolog . The LcrD protein family is involved in type III secretion and flagellar secretion in pathogenic bacteria . Almost no urease activity was detected in E . coli (pHP8080) containing the subcloned flbA gene . Furthermore, there was significantly reduced synthesis of the urease structural subunits in E . coli (pHP8080) containing the flbA gene, as determined by Western blot analysis with UreA and UreB antiserum . Thus, flagellar biosynthesis and urease activity may be linked in H . pylori . These results suggest that H . pylori genes may modulate urease activity.

Virology, 1999 Apr 10, 256(2), 340 - 50
The genome nucleotide sequence of a contemporary wild strain of measles virus and its comparison with the classical Edmonston strain genome; Takeda M et al.; The only complete genome nucleotide sequences of measles virus (MeV) reported to date have been for the Edmonston (Ed) strain and derivatives, which were isolated decades ago, passaged extensively under laboratory conditions, and appeared to be nonpathogenic . Partial sequencing of many other strains has identified >/=15 genotypes . Most recent isolates, including those typically pathogenic, belong to genotypes distinct from the Edmonston type . Therefore, the sequence of Ed and related strains may not be representative of those of pathological measles circulating at that or any time in human populations . Taking into account these issues as well as the fact that so many studies have been based upon Ed-related strains, we have sequenced the entire genome of a recently isolated pathogenic strain, 9301B . Between this recent isolate and the classical Ed strain, there were 465 nucleotide differences (2.93%) and 114 amino acid differences (2.19%) . Computation of nonsynonymous and synonymous substitutions in open reading frames as well as direct comparisons of noncoding regions of each gene and extracistronic regulatory regions clearly revealed the regions where changes have been permissible and nonpermissible . Notably, considerable nonsynonymous substitutions appeared to be permissible for the P frame to maintain a high degree of sequence conservation for the overlapping C frame . However, the cause and the effect were largely unclear for any substitution, indicating that there is a considerable gap between the two strains that cannot be filled . The sequence reported here would be useful as a reference of contemporary wild-type MeV .

J Eur Acad Dermatol Venereol, 1999 Jan, 12(1), 25 - 9
Altered sperm function or sperm antibodies are not associated with chlamydial antibodies in infertile men with leucocytospermia; Habermann B et al.; OBJECTIVE: Leucocytospermia, defined as a concentration of more than 10(6) leucocytes/ml of seminal fluid in patients without clinical symptoms due to an adnexitis, is seen in about 10% of patients in an infertility department . Infection with Chlamydia trachomatis is possibly relevant as other pathogenic bacteria were not cultured from the semen in significant numbers . SETTING: University Clinic, Department of Andrology . PATIENTS: Two hundred and seven patients attending the department for male infertility investigation . METHODS: Analysis on each semen sample included determination of leucocyte count and the MAR test for the detection of sperm antibodies . Chlamydial antibodies in semen were determined using an on-slide enzyme immunoassay . RESULTS: No differences between leucocyte counts in patients with and without chlamydial antibodies were detected . In addition, no differences in the sperm parameters or results of MAR-tests in these two groups was seen . There were no correlations between the leucocyte count and sperm parameters, including the MAR-test results . CONCLUSIONS: We conclude that antibodies to chlamydiae in semen are not associated with leucocytospermia . Leucocytospermia per se does not appear to be significant for the sperm functions and immune responses to sperm.

J Appl Biomater, 1992 Summer, 3(2), 99 - 115
Polypropylene IUCD retrieval fibers: surface morphology, material properties, microbial attachment, and migration; Coughlin RW et al.; Highly drawn and oriented polypropylene fibers used for the retrieval thread of the Cu-7 intrauterine contraceptive device (IUCD) are compared as to surface morphology and crystallinity with polypropylene fibers prepared under different conditions . A series of experiments also demonstrates the colonization of the surface of polyolefin fibers by pathogenic bacteria that are often found in the human vagina . Moreover, it is demonstrated that the retrieval threads appear to encourage pathogenic bacteria to migrate across the surface of agar . The results also indicate that control of drawing and annealing can avoid the surface fibrillation and tendency to fail by separation into a bundle of multifilaments that are observed with the IUCD retrieval threads.

J Immunol, 1999 Mar 15, 162(6), 3519 - 26
Modulation of endocytosis in nuclear factor IL-6(-/-) macrophages is responsible for a high susceptibility to intracellular bacterial infection; Pizarro-Cerda J et al.; Activated macrophages kill bacteria, a function known to depend on the expression of NF-IL-6 . Here, it is demonstrated that the attenuated Brucella abortus vaccine strain 19 replicates much better in NF-IL-6-/- than in NF-IL-6(+/+) and NF-IL-6(+/+)-activated murine macrophages and at levels comparable to those observed in normal macrophages infected with the pathogenic strain 2308 . The role of NF-IL-6 in the inhibition of intracellular bacterial replication is related to its control of endocytosis and membrane fusion between endosomes and Brucella-containing phagosomes . Addition of the granulocyte-CSF (G-CSF), whose induction is impaired in NF-IL-6(-/-) macrophages, restores both endocytosis and the morphology of endosomes, together with bactericidal activity . Regulation of membrane traffic in endocytosis by G-CSF whose expression is controlled by NF-IL-6 may explain how a host cell can control intracellular bacterial replication.

Lab Anim Sci, 1999 Feb, 49(1), 35 - 41
Lymphoid organ alterations enhanced by sub-lethal doses of coronaviruses in experimentally induced Trypanosoma cruzi infection in mice; Verinaud L et al.; The effect of sub-lethal doses of coronaviruses on the course of disease in CBA mice experimentally infected with a mildly pathogenic strain of Trypanosoma cruzi was investigated . Mice were inoculated with either T . cruzi, 0.1 median lethal dose (LD50) of coronavirus (mouse hepatitis virus {MHV-3} or virus X), or both pathogens . Levels of parasitemia, mortality, and the extent of pathologic alterations in lymphoid organs were determined . Mice inoculated with T . cruzi had mild alterations in their lymphoid organs and survived infection . In contrast, mice inoculated with both pathogens died, and had significantly higher levels of parasitemia and profound alterations in lymphoid organs . These results indicate that the pathologic profile of T . cruzi infection can be profoundly altered by subclinical infection with coronaviruses.

Curr Opin Plant Biol, 1998 Aug, 1(4), 329 - 35
Determinants of pathogenicity and avirulence in plant pathogenic bacteria; Collmer A; Many plant pathogenic bacteria possess a conserved protein secretion system that is thought to transfer Avr (avirulence) proteins, with potential activities in both parasitism and defense elicitation, into plant cells . avr genes may be acquired horizontally by these bacteria, and avr gene compositions are highly variable . In the past year, heterologous expression experiments have revealed that the products of avr genes can be interchanged among different genera of bacteria with retention of secretion, pathogenicity, and avirulence activities, suggesting mechanisms for rapid coevolution of these parasites with changing plant hosts.

Curr Opin Microbiol, 1998 Feb, 1(1), 17 - 26
In vivo and ex vivo regulation of bacterial virulence gene expression; Cotter PA et al.; Bacteria are remarkably adaptable organisms that are able to survive and multiply in diverse and sometimes hostile environments . Adaptability is determined by the complement of genetic information available to an organism and by the mechanisms that control gene expression . In general, gene products conferring a growth or survival advantage in a particular situation are expressed, while unnecessary or deleterious functions are not . Expression of virulence gene products that allow pathogenic bacteria to multiply on and within host cells and tissues are no exception to this rule . Being of little or no use to the bacterium except during specific stages of the infectious cycle, these accessory factors are nearly always subject to tight and coordinate regulation . As a result of recent advances, we are beginning to appreciate the complexities of the interactions between bacteria and their hosts . The ability to probe virulence gene regulation in vivo has broadened our perspectives on pathogenesis.

Indian J Gastroenterol, 1999 Jan-Mar, 18(1), 18 - 21
Isoenzyme and molecular characterization of Entamoeba histolytica and Entamoeba dispar isolates from symptomatic and asymptomatic subjects; Sinha P et al.; AIM: To correlate the clinical features of amebic infections with the characteristics of Entamoeba culture isolates of stools . METHODS: Isolates from seven irritable bowel syndrome (IBS) patients, four asymptomatic cyst passers (ACP) and five patients with invasive amebic disease were subjected to hexokinase polyacrylamide electrophoresis (HK-PAGE) and their DNA subjected to restriction fragment (RF) analysis of amplified polymerase chain reaction (PCR) products . These findings were correlated with anti-amebic serology . Two axenic pathogenic strains (HM1:IMSS, NIH:200) and one xenic nonpathogenic strain (SAW1734) were used as standards . RESULTS: All isolates from IBS patients as well as ACP had slow-moving (nonpathogenic) band pattern, whereas those from patients with invasive disease had fast-moving (pathogenic) band pattern on HK-PAGE . Serological data using EIA and RF patterns of PCR-amplified genome corroborated these results . CONCLUSIONS: Our results support the view that there are two species of Entamoeba infecting humans--E . histolytica(pathogenic) and E . dispar (nonpathogenic), and HK-PAGE of culture isolates can differentiate between them.

Proc Natl Acad Sci U S A, 1999 Mar 2, 96(5), 2001 - 6
The vacuolating toxin from Helicobacter pylori forms hexameric pores in lipid bilayers at low pH; Czajkowsky DM et al.; Pathogenic strains of Helicobacter pylori secrete a cytotoxin, VacA, that in the presence of weak bases, causes osmotic swelling of acidic intracellular compartments enriched in markers for late endosomes and lysosomes . The molecular mechanisms by which VacA causes this vacuolation remain largely unknown . At neutral pH, VacA is predominantly a water-soluble dodecamer formed by two apposing hexamers . In this report, we show by using atomic force microscopy that below pH approximately 5, VacA associates with anionic lipid bilayers to form hexameric membrane-associated complexes . We propose that water-soluble dodecameric VacA proteins disassemble at low pH and reassemble into membrane-spanning hexamers . The surface contour of the membrane-bound hexamer is strikingly similar to the outer surface of the soluble dodecamer, suggesting that the VacA surface in contact with the membrane is buried within the dodecamer before protonation . In addition, electrophysiological measurements indicate that, under the conditions determined by atomic force microscopy for membrane association, VacA forms pores across planar lipid bilayers . This low pH-triggered pore formation is likely a critical step in VacA activity.

Biochim Biophys Acta, 1999 Feb 16, 1444(2), 263 - 8
Kinetoplast DNA minicircles of Leishmania donovani express a protein product; Singh N et al.; We describe an unprecedented finding of an open reading frame present in the variable region in one of the minicircle sequence classes of a human pathogenic strain of Leishmania donovani (MHOM/IN/90/RMRI 68) which is transcribed and translated . The encoded protein showed homologies to known transport proteins.

Prev Vet Med, 1999 Jan 1, 38(1), 1 - 9
Quarter-milk somatic cell count at calving and at the first six milkings after calving; Barkema HW et al.; Thirty cows were studied during the first six milkings after calving . Quarter foremilk samples were collected by the farmers at calving and at six subsequent milkings . Geometric-mean somatic cell count (SCC) decreased from 593,000 at calving to 126,000 cells/ml at the sixth milking after calving . In quarters infected with major pathogenic bacteria, geometric-mean SCC was 3,229,000 cells/ml at calving, and 1,257,000 cells/ml at the sixth milking after calving . In quarters infected with minor pathogenic bacteria, geometric-mean SCC was 1,000,000 cells/ml at calving, and 170,000 cells/ml at the sixth milking after calving . In culture-negative quarters, geometric-mean SCC decreased from 306,000 at calving to 42,000 cells/ml at the sixth milking after calving . Quarter SCC can be used early postpartum to give an indication of intra-mammary infection status.

FEBS Lett, 1999 Jan 22, 443(1), 11 - 6
Expression of functional Na+/H+ antiporters of Helicobacter pylori in antiporter-deficient Escherichia coli mutants; Inoue H et al.; An open reading frame with a sequence homologous to Escherichia coli Na+/H+ antiporter A (ENhaA) was found in the total genomic sequence of Helicobacter pylori, a pathogenic bacterium of gastric inflammation, and was named HNhaA . The primary sequences and the hydropathy profiles of ENhaA and HNhaA were very homologous except for one additional region found in HNhaA . This sequence has about 40 hydrophilic amino acid residues inserted at the position next to residue 235 of ENhaA which corresponds to residue 245 of HNhaA . HNhaA was expressed in E . coli mutants deficient in Na+/H+ antiporters and complemented the salt-sensitive phenotype of the mutants . Membrane vesicles prepared from these transformants of HNhaA using mutants deficient in the antiporters had the antiporter activities . Surprisingly, the antiporter activity in the transformant membranes was high at acidic and neutral pH, while ENhaA did not function at these pHs . A hydrophilic region around residue 235 in ENhaA and the additional hydrophilic region of about 40 residues in the same region found in HNhaA might be responsible for this difference in activity by acting as putative pH sensors.

J Rheumatol, 1999 Jan, 26(1), 141 - 5
Osteoarticular complications of brucellosis in an Atlantic area of Spain; Gonzalez-Gay MA et al.; OBJECTIVE: To assess the frequency and clinical manifestations of osteoarticular brucellosis in an Atlantic area of Spain . METHODS: The case histories of all patients older than 14 years of age with active brucellosis diagnosed at the Hospital Xeral-Calde, Lugo, Spain, between October 1979 and October 1997 were reviewed . Diagnosis of brucellosis was by one of the following criteria: isolation of brucella species in blood or other fluids or tissue samples; or a clinical picture compatible with brucellosis in the presence of raised titers of specific antibodies by seroagglutination or Rose-Bengal plate agglutination tests . RESULTS: Forty-four patients (34 men, 10 women) of the 158 patients diagnosed with brucellosis (27.8%) had osteoarticular complications . Spondylitis (20/44; 45.5%) and sacroiliitis (15/44; 34.1%) were the most common complications . Patients with spondylitis were older and had a more chronic disease course than those with sacroiliitis or peripheral arthritis . Brucella abortus was the pathogenic strain responsible for human brucellosis in this region of Spain . CONCLUSION: In the Lugo region of Northwestern Spain osteoarticular brucellosis principally affects males and mainly involves spine and sacroiliac joints.

Infect Immun, 1999 Feb, 67(2), 546 - 53
The link between phylogeny and virulence in Escherichia coli extraintestinal infection; Picard B et al.; Previous studies suggesting a link between Escherichia coli phylogenetic groups and extraintestinal virulence have been hampered by the difficulty in establishing the intrinsic virulence of a bacterial strain . Indeed, unidentified virulence factors do exist, and the susceptibility of the host to infection is highly variable . To overcome these difficulties, we have developed a mouse model of extraintestinal virulence to test the virulence of the strains under normalized conditions . We then assessed the phylogenetic relationships compared to the E . coli reference (ECOR) collection, the presence of several known virulence determinants, and the lethality to mice of 82 human adult E . coli strains isolated from normal feces and during the course of extraintestinal infections . Commensal strains belong mainly to phylogenetic groups A and B1, are devoid of virulence determinants, and do not kill the mice . Strains exhibiting the same characteristics as the commensal strains can be isolated under pathogenic conditions, thus indicating the role of host-dependent factors, such as susceptibility linked to underlying disease, in the development of infection . Some strains of phylogenetic groups A, B1, and D are able to kill the mice, their virulence being most often correlated with the presence of virulence determinants . Lastly, strains of the B2 phylogenetic group represent a divergent lineage of highly virulent strains which kill the mice at high frequency and possess the highest level of virulence determinants . The observed link between virulence and phylogeny could correspond to the necessity of virulence determinants in a genetic background that is adequate for the emergence of a virulent clone, an expression of the interdependency of pathogenicity and metabolic activities in pathogenic bacteria.

Curr Opin Chem Biol, 1998 Dec, 2(6), 695 - 700
Oligosaccharide receptors for bacteria: a view to a kill; Lingwood CA; Oligosaccharide recognition is a major means of bacterial-host cell attachment . Bacterial-host receptor binding can subvert host signaling pathways to cause pathology . In addition, pathogenic bacteria can utilize more than one recognition system to bind host cells . Recent studies of Helicobacter pylori illustrate both these points . Together with this redundancy in recognition, the importance of multivalent sugar binding has become apparent . Multivalent sugar receptor analogs have been used to both prevent and detach adherent bacteria . Several new chemical technologies for the generation of bioactive glycopolymers have been developed and may be successfully adapted to address both these issues.

FEBS Lett, 1998 Dec 28, 441(3), 361 - 5
Identification of the active site of legumain links it to caspases, clostripain and gingipains in a new clan of cysteine endopeptidases; Chen JM et al.; We show by site-directed mutagenesis that the catalytic residues of mammalian legumain, a recently discovered lysosomal asparaginycysteine endopeptidase, form a catalytic dyad in the motif His-Gly-spacer-Ala-Cys . We note that the same motif is present in the caspases, aspartate-specific endopeptidases central to the process of apoptosis in animal cells, and also in the families of clostripain and gingipain which are arginyl/lysyl endopeptidases of pathogenic bacteria . We propose that the four families have similar protein folds, are evolutionarily related in clan CD, and have common characteristics including substrate specificities dominated by the interactions of the S1 subsite.

Proc R Soc Lond B Biol Sci, 1998 Dec 7, 265(1412), 2341 - 6
The spatial dynamics of prion disease; Payne RJ et al.; An important component of the latency period of the transmissible spongiform encephalopathies (prion diseases) can be attributed to delays during the propagation of the infectious prion isoform, PrPSc, through peripheral nervous tissues . A growing body of data report that the host prion protein, PrPC, is required in both peripheral and central nervous tissues for susceptibility to infection . We introduce a mathematical model, which treats the PrPSc as a mobile infectious pathogen, and show how peripheral delays can be understood in terms of the intercellular dispersal properties of the PrPSc strain, its decay rate, and its efficiency at transforming the PrPC . It has been observed that when two pathogenic strains co-infect a host, the presence of the first inoculated strain can slow down, or stop completely, the spread of the second strain . This is thought to result from a reduced concentration of host protein available for conversion by the second strain . Our model can explain the mechanisms of such interstrain competition and the time-course of the increased delay . The model provides a link between those data suggesting a role for a continuous chain of PrP-expressing tissue linking peripheral sites to the brain, and data on prion strain competition.

Eur J Pediatr, 1998 Dec, 157(12), 1004 - 11
Ureaplasma urealyticum colonization and bronchopulmonary dysplasia: a comparative prospective multicentre study; Abele-Horn M et al.; To determine the role of tracheal colonization at birth with Ureaplasma urealyticum and other pathogenic bacteria with regard to the development of bronchopulmonary dysplasia (BPD), 97 premature infants with very low birth weight (< 1500 g) were followed prospectively over 30 days in a multicentre study . Of those infants, 35 were colonized with Ureaplasma urealyticum (group Ia), 22 with other pathogenic bacteria (group Ib) and 40 infants with sterile tracheal aspirates served as controls (group II) . Colonization with Ureaplasma urealyticum or with pathogenic bacteria independently increased the risk of developing BPD as compared to the controls (OR 2.55; 95% CI {1.11, 5.87}) . Among Ureaplasma urealyticum and bacterial colonized infants, duration of mechanical ventilation and oxygen requirement were significantly longer than among controls (P < 0.05); during the interval of 11 to 35 days of life, every additional day of ventilation significantly increased the risk of BPD (OR 1.22; CI {1.12, 1.32}) . The rate of oxygen supplementation, which was similar in both groups during the first 2 weeks of life, was significantly higher among the colonized infants at day 21 (0.38+/-0.18 and 0.39+/-0.16 vs 0.31+/-0.13, P < 0.05) and at day 28 (0.38+/-0.21 and 0.34+/-0.15 vs 0.28+/-0.12, P < 0.05) . For infants still ventilated at age of 28 days, Ureaplasma urealytricum and bacterial colonization were associated with a significant higher risk for BPD than for uncolonized controls (OR 5.53; {1.27, 24.02} . Association of Ureaplasma urealyticum and of bacterial colonization and BPD was not weakened after adjustments were made in a multivariate analysis for other significant risk factors . CONCLUSION: Ureaplasma urealyticum colonization is as an important risk factor in the development of bronchopulmonary dysplasia as bacterial colonization even after treatment with surfactant.

Plant Mol Biol, 1998 Dec, 38(6), 1225 - 34
Cloning of genes by mRNA differential display induced during the hypersensitive reaction of soybean after inoculation with Pseudomonas syringae pv . glycinea; Seehaus K et al.; Soybean (Glycine max {L.} Merr.) cell suspension cultures (cv . Williams 82) inoculated with the pathogenic bacteria Pseudomonas syringae pv . glycinea respond with a hypersensitive reaction (HR) when the bacteria express the avirulence gene avrA . A mRNA differential display was established for this system to allow the identification of genes induced during the HR . Six PCR-fragments (DD1-DD6) from the differential display analysis were identified, which are induced during the HR . Database searches revealed that the fragment DD1 encodes chalcone isomerase and DD2 was identified as ubiquitin . The fragment DD3 shares significant homology to the signalling molecule 14-3-3 . The partial DD4 product is homologous to the enhancer of rudimentary from Drosophila and an uncharacterized homologue of it from Arabidopsis . The fragment DD5 is similar to glucose-6-phosphate dehydrogenase which provides NADPH to the cell . The PCR-product DD6 seems to be a new leucine-rich-repeat disease resistance gene from soybean, which is significantly induced during the HR . All of the identified genes are clearly induced during a HR in infected plants of the same cultivar, indicating that results from the cell culture model system can be transferred to intact plants . These studies show that complex mRNA differential display is a powerful tool to identify new induced gene in plant-pathogen interactions.

Infect Immun, 1999 Jan, 67(1), 230 - 6
Type-specific contributions to chromosome size differences in Escherichia coli; Rode CK et al.; The Escherichia coli genome varies in size from 4.5 to 5.5 Mb . It is unclear whether this variation may be distributed finely throughout the genome or is concentrated at just a few chromosomal loci or on plasmids . Further, the functional correlates of size variation in different genome copies are largely unexplored . We carried out comparative macrorestriction mapping using rare-restriction-site alleles (made with the Tn10dRCP2 family of elements, containing the NotI, BlnI, I-CeuI, and ultra-rare-cutting I-SceI sites) among the chromosomes of laboratory E . coli K-12, newborn-sepsis-associated E . coli RS218, and uropathogenic E . coli J96 . These comparisons showed just a few large accessory chromosomal segments accounting for nearly all strain-to-strain size differences . Of 10 sepsis-associated and urovirulence genes, previously isolated from the two pathogens by scoring for function, all were colocalized exclusively with one or more of the accessory chromosomal segments . The accessory chromosomal segments detected in the pathogenic strains from physical, macrorestriction comparisons may be a source of new virulence genes, not yet isolated by function.

J Am Vet Med Assoc, 1998 Dec 1, 213(11), 1586 - 9, 1570
Serologic and molecular characterization of an abortigenic strain of equine arteritis virus isolated from infective frozen semen and an aborted equine fetus; Balasuriya UB et al.; A virus isolated from an aborted equine fetus was determined to be antigenically distinct from several other strains of equine arteritis virus (EAV) by use of a neutralization assay with a large panel of neutralizing monoclonal antibodies . The virus was readily neutralized by polyclonal equine anti-EAV serum . Comparative nucleotide and amino acid sequence analyses indicated that the virus (WA97) isolated from the aborted fetus was virtually identical to a virus (S1971) isolated from imported semen used to inseminate another mare on the farm . Phylogenetic analysis indicated that the WA97/S1971 virus was more related to European than to North American strains of EAV . These sensitive molecular procedures may be useful for epidemiologic investigations of EAV infections . Screening and certification of stallions and frozen equine semen would prevent dissemination of pathogenic strains of EAV.

Eur J Biochem, 1998 Oct 15, 257(2), 449 - 56
Solution conformation of the Pseudomonas syringae MSU 16H phytotoxic lipodepsipeptide Pseudomycin A determined by computer simulations using distance geometry and molecular dynamics from NMR data; Coiro VM et al.; Pseudomycin A is a cyclic lipodepsinonapeptide phytotoxin produced by a strain of the plant pathogenic bacterium Pseudomonas syringae . Like other members of this family of bacterial metabolites, it is characterised by a fatty acylated cyclic peptide with mixed chirality and lactonic closure . Several biological activities of Pseudomycin A are lower than those found for some of its congeners, a difference which might depend on the diverse number and distribution of charged residues in the peptide moiety . Hence, it was of interest to investigate its conformation in solution . After the complete interpretation of the two-dimensional NMR spectra, NOE data were obtained and the structure was determined by computer simulations, applying distance geometry and molecular dynamics procedures . The conformation of the large ring of Pseudomycin A in solution includes three rigid structural regions interrupted by three short flexible regions that act as hinges . The overall three-dimensional structure of the cyclic moiety is similar to that of previously studied bioactive lipodepsinonapeptides produced by other pseudomonads.

Mol Gen Mikrobiol Virusol, 1998, (3), 3 - 8
{Uncultured status of pathogenic bacteria: known and possible factors of reversible process induction}; Romanova IuM et al.; Reviews published reports and authors' own data on the properties of unculturable bacteria, effects of environmental factors on the time course of transition in an unculturable state of different bacterial cells . Special attention is paid to reverse transfer of bacteria from unculturable to normal vegetative state . Conditions of inducing reverse transfer in in vitro laboratory conditions under different conditions of culturing and in vivo and injection of inoculates of uncultured forms of initially virulent bacteria to susceptible hosts are discussed . Probable role of some cytokinetic factors inducing transfer of bacteria from uncultured to cultured state during their transition from the environment into a host is discussed.

J Infect, 1998 Jan, 36(1), 23 - 7
The bacteriological screening of donated human milk: laboratory experience of British Paediatric Association's published guidelines; Wright KC et al.; This study was undertaken to assess the application of the British Paediatric Association's (BPA) published guidelines to the bacteriological screening of breast milk donated to a District General Hospital milk bank . Samples of donated milk were subjected to bacterial counts and provisional identification after both 24 and 48 h incubation on cysteine lactose electrolyte-deficient (CLED) and Columbia blood agar . 21.8% (76 out of 348) donations of milk failed to reach the BPA acceptable criteria . The organisms responsible for the rejection of these samples were all evident within 24 h incubation, and were not significantly confined to one medium . A large percentage of rejected samples originated from a small number of donor mothers; 63.2% came from one donor . In applying BPA guidelines, both CLED and Columbia blood agar were found to be equally effective in screening for unacceptable organisms in prepasteurization donated breast milk . The 24 h period allowed for bacteriological screening, prior to pasteurization of milk samples, was sufficient to allow the growth of all potentially pathogenic bacteria in this study . To prevent the donation of consistently contaminated milk, more active communication between the milk bank staff and the donor is recommended.

J Virol, 1998 Dec, 72(12), 10281 - 5
A pathogenic threshold of virus load defined in simian immunodeficiency virus- or simian-human immunodeficiency virus-infected macaques; Ten Haaft P et al.; To determine if a specific pathogenic threshold of plasma viral RNA could be defined irrespective of virus strain, RNA levels in the plasma of more than 50 infected rhesus macaques (Macaca mulatta) were measured . Animals were inoculated intravenously with either simian immunodeficiency virus (SIV) or simian-human immunodeficiency virus (SHIV) strains of known pathogenic potential (SIV8980, SIVsmm-3, SIVmac32H/J5, SIVmac32H/1XC, reverse transcriptase-SHIV, SHIV89.6p) or with attenuated strains (SHIVW6.1D, SHIVsf13, SHIVhan-2, SIVmacDeltanef, SHIVsf33) . In animals inoculated with nonpathogenic strains, shortly after the primary peak of viremia viral RNA levels declined and remained below 10(4) RNA equivalents/ml of plasma between 6 and 12 weeks postinoculation . Animals infected with documented pathogenic strains maintained viral RNA levels higher than 10(5) RNA equivalents/ml of plasma . In animals infected with strains with low virulence, a decline in plasma RNA levels was observed, but with notable individual variation . Our results demonstrate that the disease-causing potential was predicted and determined by a threshold plasma virus load which remained greater than 10(5) RNA equivalents/ml of plasma 6 to 12 weeks after inoculation . A threshold virus load value which remained below 10(4) RNA equivalents/ml of plasma was indicative of a nonpathogenic course of infection.

Mikrobiol Z, 1998 May-Jun, 60(3), 56 - 62
{A biological model study of the effect of Aerococcus viridans on pathogenic bacteria}; Zhurylo OA et al.; Morphological researches studies showed that the treatment of infected skin wounds with Aerobact quickly eliminated inflammation, promoted regeneration of damaged tissues, that actively stimulated formation of granulations . A decrease of S . aureus virulence which completely or partially loose lethal and necrotic activity is one of the reasons of the observed phenomenon . On the model of S . typhimurium infection the expressed protective action of bacteria of Aerococcus genus was shown; this gives us a good prospect in the expansion of the indications for application of probiotic Aerobact.

J Immunol, 1998 Oct 15, 161(8), 4301 - 8
Effect of cytotoxic necrotizing factor-1 on actin cytoskeleton in human monocytes: role in the regulation of integrin-dependent phagocytosis; Capo C et al.; Cytotoxic necrotizing factor-1 (CNF1) is isolated from pathogenic strains of Escherichia coli and catalyzes the activation of Rho GTPases by the deamidation of a glutamine residue . This toxin induces stress fiber formation, cell spreading, and membrane folding and promotes phagocytosis competence in epithelial cells . We show that CNF1 induces morphologic changes in monocytic cells: polarized-like shape in THP-1 cells, lamellipodia, and cell spreading in adherent monocytes . CNF1 also increased filamentous actin (F-actin) content in a time- and dose-dependent manner . In addition, the toxin profoundly reorganized the actin cytoskeleton: redistribution of F-actin in polarized deformations of THP-1 cells and disorganization of microfilament network in monocytes . We also studied the effects of CNF1 on phagocytosis . It markedly impaired the ingestion of unopsonized zymosan involving CR type 3 . However, CNF1 had no effect on the uptake of iC3b-coated zymosan or IgG-mediated phagocytosis of SRBC . In addition, CNF1 induced clustering of CR3 and Fc gammaRII (CD32) but selectively impaired the colocalization of CR3 with F-actin . It is likely that CNF1-induced reorganization of actin cytoskeleton down-modulates integrin activation-dependent phagocytosis by preventing the codistribution of CR3 with F-actin . CNF1 may control some features of integrin-dependent phagocytosis in myeloid cells through its action on Rho GTP binding proteins and cytoskeletal organization.

Mol Plant Microbe Interact, 1998 Oct, 11(10), 960 - 7
nec1, a gene conferring a necrogenic phenotype, is conserved in plant-pathogenic Streptomyces spp . and linked to a transposase pseudogene; Bukhalid RA et al.; We are investigating the genetic basis for, and evolution of, plant pathogenicity in Streptomyces spp . The plant-pathogenic species S . scabies, S . acidiscabies, and S . turgidiscabies cause the scab disease of potato and produce the phytotoxins, thaxtomins . Forty-three Streptomyces strains representing the three species were evaluated; all thaxtomin A-producing Streptomyces strains were pathogenic on potato tubers and all but one hybridized to nec1 and ORFtnp, two genes previously cloned from S . scabies ATCC 41973 . nec1 confers a pathogenic phenotype on S . lividans TK24, a nonpathogen, and ORFtnp is a transposase pseudogene located 5' to nec1 . The eight nonpathogenic strains tested neither produced thaxtomin A nor hybridized to nec1 . ORFtnp and nec1 occurred on a single PvuII restriction fragment in all thaxtomin A-producing Streptomyces strains . The nucleotide sequences of the homologs of nec1 and ORFtnp from two pathogenic strains each of S . scabies, S . acidiscabies, and S . turgidiscabies were identical; oligonucleotide primers specific to this gene amplified homologs from all strains that hybridized to nec1 . We propose that nec1 and ORFtnp have been horizontally mobilized from S . scabies to S . acidiscabies and S . turgidiscabies, and that nec1 is involved in pathogenicity and physically linked to the thaxtomin A biosynthetic genes.

Res Microbiol, 1998 Feb, 149(2), 145 - 54
PCR-based detection of verotoxin-producing Escherichia coli (VTEC) in ground beef; Gilgen M et al.; Pathogenic strains of Escherichia coli producing verotoxins (VTs) have been recognized as a cause of human disease, and rapid and sensitive detection tests are urgently needed to ensure the safety of food, especially ground beef . We applied two nested polymerase chain reaction (PCR) assays to detect the genes encoding VT1 and VT2 irrespective of the bacterial serotype . In combination with a direct sample preparation protocol, we were able to uncover the presence of about 110 CFU of verotoxinogenic E . coli (VTEC) in 10 g of ground beef . When a six-hour enrichment was included, we found the detection limit to be in the range of 1 to 10 bacterial cells per 10 g of ground beef . To evaluate our detection system, we tested 30 ground beef samples originating from butcher shops in Berne, Switzerland . One sample yielded positive PCR results for both the VT1 and VT2 genes, indicating the presence of verotoxinogenic E . coli . Finally, 20 food homogenates, shown to contain E . coli strains by standard culture, were analysed with our method, and the gene encoding VT2 was detected in one cheese sample . The results suggest that the described PCR method can serve as a valuable tool for the surveillance of VTEC contamination of foods.

Res Microbiol, 1998 Jul-Aug, 149(7), 473 - 85
Colonization ability and pathogenic properties of a fim- mutant of an avian strain of Escherichia coli; Marc D et al.; Several studies suggest that the expression of type 1 fimbriae is involved in the virulence of Escherichia coli in chickens, by promoting adhesion of bacteria to the respiratory tract, which is most probably the first step to occur in the infection, and by interacting with the immune response . In order to determine to what extent type 1 fimbriae were involved in the pathogenic process, the fim cluster of an avian pathogenic strain of E . coli, MT78 (O2:K1:H+), was modified in vitro and reintroduced in the parent strain via allele exchange using suicide vector pCVD442 . The mutant strain thus generated (DM34) had its entire fim cluster removed . Its pathogenic properties were compared to those of the parent strain in an experimental reproduction of avain colibacillosis in 15-day-old chickens, after primary infection with infectious bronchitis virus followed by intratracheal inoculation of the challenge strain . In specific-pathogen-free (SPF) animals, mutant DM34 was less pathogenic than the parent strain and colonized the lungs of infected animals to a lower level . In germ-free chickens, although DM34 was less pathogenic than MT78 according to the differences in weight gains, it colonized the trachea, lungs and internal organs to the same extent as MT78 . Our results suggest that, whereas type 1 fimbriae are not strictly required in colonization of the respiratory tract of germ-free chickens, they might be important in establishing a bacterial population in the lungs of SPF animals . The difference regularly observed in weight gains between mutant- and wild-type-inoculated chickens reflects a decreased pathogenicity of the fim- mutant . However, the isolation of E . coli in target organs and the observation of colibacillosis symptoms and lesions in mutant-inoculated chickens suggest that type 1 fimbriae by themselves play a limited role in pathogenicity.

Otolaryngol Pol, 1997, 51 Suppl 25, 171 - 4
{Practical implications of bacterial resistance to antibiotics . Attempts to fight it}; Denys A; Generation of strains resistant to antibiotics, its genetic mechanisms and the role of incompetent administration of these drugs are presented in the paper . The resistance is characterised mainly by the generation of extracellular enzymes which cause the breakdown of beta-lactam ring Pathogenic bacteria which cause changes in the respiratory system are discussed . The use of beta-lactam antibiotics with beta-lactam inhibitors is a way to prevent generation of resistant strains, the combination of amoxycillin and clavulanic acid is of particular importance.

Parasite, 1998 Mar, 5(1), 27 - 36
The in vitro effects of crystal violet on the pathogenic haemoflagellate Cryptobia salmositica Katz, 1951 (Sarcomastigophora: Kinetoplastida); Ardelli BF et al.; Crystal violet does not inhibit in vitro multiplication of a nonpathogenic strain of Cryptobia salmositica at low concentrations (0.01 microM and 0.001 microM) but multiplication is inhibited at higher concentrations (> or = 0.05 microM) . In contrast, the pathogenic strain of C . salmositica does not multiply in vitro when incubated with crystal violet (0.001 microM, 0.01 microM and 0.05 microM) . The infectivity of the pathogenic strain is significantly reduced after in vitro exposure to crystal violet . Crystal violet lyses C . salmositica (100.0 microM) and causes lesions on mitochondrial and nuclear membranes of the parasite . Pathogenic strains of Cryptobia salmositica and C . bullocki are more susceptible to lysis after in vitro exposure to crystal violet than are nonpathogenic strains of Cryptobia salmositica and C . catostomi.

J Appl Microbiol, 1998 Aug, 85(2), 365 - 71
Preliminary description of biocidal (syringomycin) activity in fluorescent plant pathogenic Pseudomonas species; Hu FP et al.; Strains representing the fluorescent plant pathogenic Pseudomonas spp., Ps . agarici, Ps . asplenii, Ps . avellanae, Ps . beteli, Ps . caricapapayae, Ps . cichorii, Ps . corrugata, Ps . ficuserectae, Ps . flectens, Ps . fuscovaginae, Ps . marginalis, Ps . meliae, Ps . savastanoi, Ps . syringae, Ps . tolaasii and Ps . viridiflava were tested for biocidal activity using Aspergillus niger as assay organism . Inhibitory behaviour was found in strains of Ps . asplenii, Ps . blatchfordae, Ps . cichorii, Ps . corrugata, Ps . fuscovaginae, Ps . marginalis, Ps . marginalis pv . pastinacea, Ps . syringae pv . syringae, Ps . syringae pv . aptata, Ps . syringae pv . atrofaciens, Ps . syringae pv . lapsa, Ps . tolaasii, and strains of a Pseudomonas sp . pathogenic to Actinidia, in the Ps . savastanoi genomic sp . Antifungal activity could be identified with the production of members of the syringomycin family of toxins by strains in Ps . syringae, Ps . asplenii and Ps . fuscovaginae . These toxin reactions support suggestions made elsewhere of the synonym of the latter two species . In a preliminary characterization using tests for stability to heat, protease, acid and alkaline treatments, unknown toxins consistent with syringomycin-like toxins the strains from Actinidia species . The toxins from Ps . cichorii and from Ps . corrugata differed in their reactions from all other agents . Pseudomonas tolaasii produces the antifungal compound tolaasin . The white line reaction with Ps . reactions, a test for tolaasin production by strains of Ps . tolaasii, was confirmed as specific for this compound . Some of these low molecular weight toxins may be produced by some of these plant pathogenic strains.

J Appl Microbiol, 1998 Aug, 85(2), 357 - 64
Applicability of a model for non-pathogenic Escherichia coli for predicting the growth of pathogenic Escherichia coli; Salter MA et al.; A model was developed for the temperature dependence of growth rate of a non-pathogenic Escherichia coli strain . The suitability of that model for predicting the growth rate of pathogenic E . coli strains was assessed . Growth rates of pathogenic strains were found to be adequately described by the model . Model predictions were also found to describe sufficiently well-published growth rate data for non-pathogenic E . coli on mutton carcase surfaces and E . coli O157:H7 in ground roasted beef, milk, and on cantaloupes and water melons . In addition, E . coli O157:H7 was found to grow in the region of 44-45 degrees celsius.

Brain Res, 1998 Aug 17, 802(1-2), 175 - 83
Effect of neutrophil depletion in acute cerebritis; Lo WD et al.; Inhibition of the host's neutrophil response has been proposed as one means to reduce tissue damage in acute inflammation . If this approach can be applied in acute central nervous system (CNS) infection, the long-term morbidity, which occurs in CNS infection, might be reduced . Previous studies in models of CNS infection yielded conflicting results whether neutrophil depletion might be protective . To determine whether neutrophil depletion reduces tissue necrosis and cerebrovascular injury in experimental bacterial cerebritis, we depleted circulating neutrophils with an IgM monoclonal antibody, RP3, given after the start of the infection . RP3 treatment successfully depleted circulating neutrophils and reduced the extent of neutrophil influx into the cerebritis region . The extent of tissue necrosis, measured histologically, and the regional increase of blood-brain barrier (BBB) permeability were not inhibited by neutrophil depletion, and in animals treated with RP3 alone, the extent of tissue necrosis and BBB permeability tended to be larger than in S . aureus inoculated controls . We conclude that host neutrophils do not add to the tissue and cerebrovascular damage created by the intracerebral inoculation of a pathogenic bacteria, and the neutrophils serve to diminish local damage in the setting of a cerebritis.

Vet Clin North Am Equine Pract, 1998 Aug, 14(2), 349 - 63, vii
Dental sepsis; Mueller PO et al.; Dental sepsis or periapical abscess formation constitutes a large percentage of dental conditions that afflict horses . Dental sepsis occurs when the pulp chamber of the tooth is exposed to the oral cavity or external environment, allowing bacterial localization with resulting infection . Although acute, primary, septic pulpitis in horses is rare, dental sepsis often results from colonization of the pulp chamber with pathogenic bacteria secondary to maleruption or impaction of teeth with secondary alveolar bone lysis, primary fractures of the tooth, mandible, or maxilla, periodontal disease, or infundibular necrosis . The sequela to pulpal infection are extensions into the periradicular tissues and mandibular or maxillary periapical abscess formation.

Korean J Intern Med, 1998 Jul, 13(2), 104 - 9
Antigenic diversity and serotypes of Helicobacter pylori associated with peptic ulcer diseases; Park SM et al.; OBJECTIVES: Clinical presentation of Helicobacter pylori (H . pylori) infection has marked variation mainly due to the strain diversity and host susceptibility . Although H . pylori is identified as a major risk factor for gastric and duodenal ulcers, the ulcerogenic or pathogenic strain has not been documented yet . The objective of this study was to investigate antigenic types of the ulcerogenic strain of H . pylori . METHODS: The sera of 64 patients were tested by Western blot using Helicoblot 2.0 for six major anti-H . pylori antibodies, together with CLO test and histological examination of gastric biopsy tissues . Thirty-five, nine and 20 patients had duodenal ulcer, gastric ulcer and chronic active gastritis, respectively . The antigenic types of H . pylori were analyzed in 54 patients with positive H . pylori infection . In this study, H . pylori was divided into four serotypes according to the presence and absence of CagA and VagA: type I; CagA (+) and VacA(+), type Ia: CagA (+) and VacA(-), type Ib: CagA(-) and VacA(+), and type II: CagA(-) and VacA(-) . RESULTS: There was no difference in the number of bands for six antigens: 3.2 +/- 1.4, 3.0 +/- 1.2 and 3.1 +/- 1.4 in 35 duodenal ulcer, 7 gastric ulcer and 12 chronic gastritis, respectively . The band with 119 kDa was 90.7%, which was the most common band with the order of 35, 30, 26.5, 89 and 19.5 kDa . Type I, la and Ib were positive in 22.2, 42.6 and 27.8%, respectively, which were significantly higher than type II (p < 0.05) . There was no difference in the positive rates of four urease subtypes between the four serotypes.

J Virol, 1998 Oct, 72(10), 7871 - 84
Genetic variation in a human immunodeficiency virus type 2 live-virus Macaca nemestrina vaccine model; Radaelli A et al.; Four pigtailed macaques were inoculated with an infectious, apathogenic human immunodeficiency virus type 2 (HIV-2) molecular clone (HIV-2KR) and subsequently challenged with a highly pathogenic strain, HIV-2287, together with two naive control animals . After challenge, two animals inoculated with a high dose of the immunizing strain were protected from CD4 decline and immunodeficiency . To examine the role of genetic heterogeneity in protection, fragments of the env gene were amplified from peripheral blood mononuclear cell DNA and plasma RNA of challenged animals by PCR, examined by using a heteroduplex tracking assay (HTA), and sequenced . By HTA, variation was detected principally within the V1 and V2 regions of envelope . Extent of variation in viral DNA clones as assessed by HTA correlated with inoculum size, as did the degree of variation in sequences of clones derived from viral DNA . Conversely, a rapid reduction in the number of plasma viral RNA variants was noted by HTA at 8 weeks postinfection in protected animals; this reduction was not present in naive or unprotected macaques . Sequences derived from plasma viral RNA were found to be more closely related than corresponding viral DNA sequences, and protection correlated with a significant reduction in variation in plasma RNA sequences in animals given the identical inocula of HIV-2287 . Nonsynonymous mutations were significantly less prevalent in the protected animals . An additional potential glycosylation site was predicted to be present in the V2 region in all but one clone, and amino acid signatures related to protection were identified in viral DNA and RNA clones within both the V1 and V2 regions . Examination of the role of viral variation in this HIV-2 live-virus vaccine model may provide valuable insights into immunopathogenesis.

J Mol Evol, 1998 Sep, 47(3), 258 - 67
Diversifying selection governs sequence polymorphism in the major adhesin proteins fimA, papA, and sfaA of Escherichia coli; Boyd EF et al.; Fimbriae or pili are essential adherence factors usually found in pathogenic bacteria to aid colonization of host cells . Three major structural pilin genes, fimA, sfaA, and papA, from Escherichia coli natural isolates were examined and nucleotide sequence data revealed elevated levels of both synonymous and nonsynonymous site variation at these loci . Examination of synonymous site variation shows a fivefold increase in fimA sites, relative to the housekeeping gene mdh; and similarly the sfaA and papA genes have increased synonymous sites variation relative to fimA . Nonsynonymous site variation is also elevated at all three loci but, in particular, at the papA locus (kN = 0.44) . The kN/kS ratio for the three genes are among the highest yet reported for E . coli genes . Regional variation in nucleotide polymorphism within each of the genes reveal hypervariable segments where nonsynonymous substitutions exceed synonymous substitutions . We propose that at the fimA, papA, and sfaA genes, diversifying selection has brought about the increase levels of polymorphism.

J Submicrosc Cytol Pathol, 1998 Jul, 30(3), 425 - 33
Differential pathogenic effect of two Helicobacter-like organisms in dog gastric mucosa; Peyrol S et al.; Two forms of Helicobacter were detected in the gastric mucosa of twelve healthy beagle dogs . According to ultrastructural criteria they could be classified as Helicobacter bizzozeronii-like and Helicobacter felis-like species . In five animals, the light fundic load of Helicobacter bizzozeronii-like did not affect the integrity of the glandular epithelium . In three animals, the heavy bacterial load extended in the lumens of antral glands and coincided with increased intraepithelial lymphoid infiltrate . The heavy bacterial load observed in 4 animals was mixed (Helicobacter bizzozeronii-like and Helicobacter felis-like), fundic and antral, luminal and intracellular . Adherence of Helicobacter felis-like to epithelial cells and intracellular penetration were responsible for focal necrosis, and glandular atrophy might be observed . Helicobacter bizzozeronii-like thus appeared non pathogenic in beagle dogs, even when the heavy bacterial load extended to the antrum . By contrast, Helicobacter felis-like showed a constant pathogenic effect linked to its properties of adhesion and penetration into epithelial cells . A wider comparative study in humans and domestic carnivorous will determine if the latter may play a role of reservoir-host for pathogenic bacteria.

J Clin Invest, 1998 Aug 15, 102(4), 813 - 20
Selective increase of the permeability of polarized epithelial cell monolayers by Helicobacter pylori vacuolating toxin; Papini E et al.; The effects of the vacuolating toxin (VacA) released by pathogenic strains of Helicobacter pylori on several polarized epithelial monolayers were investigated . Trans-epithelial electric resistance (TER) of monolayers formed by canine kidney MDCK I, human gut T84, and murine mammary gland epH4, was lowered by acid-activated VacA . Independent of the cell type and of the starting TER value, VacA reduced it to a minimal value of 1,000-1,300 Omega x cm2 . TER decrease was paralleled by a three- to fourfold increase of {14C}-mannitol (molecular weight 182.2) and a twofold increase of {14C}-sucrose (molecular weight 342.3) transmonolayer flux . On the contrary, transmembrane flux of the proinflammatory model tripeptide {14C}-N-formyl-Met-Leu-Phe (molecular weight 437.6), of {3H}-inuline (molecular weight 5,000) and of HRP (molecular weight 47,000) did not change . These data indicate that VacA increases paracellular epithelial permeability to molecules with molecular weight < 350-440 . Accordingly, the epithelial permeability of Fe3+ and Ni2+ ions, essential for H . pylori survival in vivo, was also increased by VacA . High-resolution immunofluorescence and SDS-PAGE analysis failed to reveal alterations of junctional proteins ZO-1, occludin, cingulin, and E-cadherin . It is proposed that induction by VacA of a selective permeabilization of the epithelial paracellular route to low molecular weight molecules and ions may serve to supply nutrients, which favor H . pylori growth in vivo.

Microbiology, 1998 Jul, 144 ( Pt 7), 1931 - 43
Reiterated repeat region variability in the ciliary adhesin gene of Mycoplasma hyopneumoniae; Wilton JL et al.; Mycoplasma hyopneumoniae is a highly prevalent pathogen which colonizes the ciliated epithelial lining of the porcine respiratory tract . Expression libraries constructed from genomic DNA of the non-pathogenic strain M . hyopneumoniae J were screened with porcine hyperimmune antiserum against M . hyopneumoniae . One clone expressed a 28 kDa protein which was also reactive with monospecific antiserum raised against a putative M . hyopneumoniae-specific 94 kDa antigen derived from strain J . Trypsin digestion of whole M . hyopneumoniae cells showed the 94 kDa antigen to be surface-accessible . DNA sequence analysis of the gene encoding the 94 kDa antigen revealed greater than 90% homology to two adhesin genes, encoding P97 and Mhp1, cloned from pathogenic strain 232 and strain P5722 of M . hyopneumoniae, respectively . Two regions of repetitive DNA sequence were identified in the gene encoding the 94 kDa antigen . The first encoded the deduced amino acid sequence A(T)-K-P-E(V)-A(T) arranged as nine tandem repeats (RR1) . The second region of repetitive DNA sequence encoded the deduced amino acid sequence G-A(E,S)-P-N(S)-Q-G-K-K-A-E arranged as five tandem repeats (RR2) . Comparison of the three M . hyopneumoniae adhesin genes revealed that the genes encoding P97 and Mhp1, and the strain J gene encoding the 94 kDa antigen contained 15, 12 and 9 tandem repeats, respectively, in RR1, and 4, 5 and 5 tandem repeats, respectively, in RR2 . Southern hybridization analysis of EcoRI-digested genomic DNA probed with an 820 bp fragment spanning RR1 and RR2 identified a strongly hybridizing fragment ranging in size from 2.15 to 2.30 kb among seven geographically diverse strains of M . hyopneumoniae but failed to hybridize with DNA from four strains of Mycoplasma hyorhinis or Mycoplasma flocculare strain Ms42 . PCR primers flanking the DNA sequence encoding RR1 and RR2 were used to amplify DNA from the seven strains of M . hyopneumoniae and DNA sequence analysis of the amplification products showed that the number of tandem amino acid repeats in RR1 varied considerably between strains . RR1 from M . hyopneumoniae strains YZ, Beaufort, Sue, OMZ407 and C1735/2 comprised 11, 15, 12, 15 and 8 tandem copies, respectively, of the 5-aa repeat whilst RR2 comprised 4, 3, 4, 3 and 4 tandem copies, respectively, of the 10-aa repeat . Two putative integrin binding sites (L-E-T and R-X-X-X-D) were identified in the 94 kDa ciliary adhesin . Variability in the number of amino acid repeats in RR1 amongst strains of M . hyopneumoniae may influence ciliary binding.

Vet Q, 1998, 20 Suppl 3, S78 - 81
Probiotics and E . coli infections in man; Lodinova-Zadnikova R et al.; After oral administration of live oral vaccines COLINFANT and MUTAFLOR prepared from non-enteropathogenic E . coli strains, both strains colonized effectively the intestine in full-term and preterm infants and remained for many weeks showing, that they were capable to establish themselves as a resident strain in the infant's gut . The presence of E . coli stimulated significantly antibody production in gut, saliva and serum of colonized infants . An early induction of secretory IgA production is important particularly in formula-fed infants, where it partly replaces the lacking immunoglobulin supplied with mother milk . In full-term and premature infants the early presence of non-pathogenic E . coli strains in the intestine decreased significantly the presence of pathogenic bacterial strains in the intestine but also other mucosal surfaces of the body . The COLINFANT strain decreased the number of nosocomial infections, mortality rate in connection with infection, and the need for antibiotics . Both strains replaced successfully pathogenic strains in carriers after treatment with antibiotics.

Proc Natl Acad Sci U S A, 1998 Aug 4, 95(16), 9202 - 7
Catalytic mechanism of the phospholipase D superfamily proceeds via a covalent phosphohistidine intermediate; Gottlin EB et al.; The phospholipase D (PLD) superfamily includes enzymes of phospholipid metabolism, nucleases, as well as ORFs of unknown function in viruses and pathogenic bacteria . These enzymes are characterized by the invariant sequence motif, H(X)K(X)4D . The endonuclease member Nuc of the PLD family was over-expressed in bacteria and purified to homogeneity . Mutation of the conserved histidine to an asparagine in the endonuclease reduced the kcat for hydrolysis by a factor of 10(5), suggesting that the histidine residue plays a key role in catalysis . In addition to catalyzing hydrolysis, a number of phosphohydrolases will catalyze a phosphate (oxygen)-water exchange reaction . We have taken advantage of this observation and demonstrate that a 32P-labeled protein could be trapped when the enzyme was incubated with 32P-labeled inorganic phosphate . The phosphoenzyme intermediate was stable in 1 M NaOH and labile in 1 M HCl and 1 M hydroxylamine, suggesting that the enzyme forms a phosphohistidine intermediate . The pH-stability profile of the phosphoenzyme intermediate was consistent with phosphohistidine and the only radioactive amino acid found after alkaline hydrolysis was phosphohistidine . These results suggest that the enzymes in the PLD superfamily use the conserved histidine for nucleophilic attack on the substrate phosphorus atom and most likely proceed via a common two-step catalytic mechanism.

Arch Virol, 1998, 143(6), 1055 - 62
Viruses produced from complementary DNA of virulent and avirulent strains of swine vesicular disease viruses retain the in vivo and in vitro characteristics of the parental strain; Kanno T et al.; A full-length cDNA copy of the genome of the pathogenic strain, J1'73, of swine vesicular disease virus (SVDV) was constructed and inserted into the plasmid pSVL to generate a recombinant plasmid pSVLSJ1 . Infectious virus was produced following transfection of cultured mammalian cells with the plasmid . The recovered virus had the same in vitro properties as the parental strain with regard to antigenicity, plaque size on IBRS-2 cells and single-step growth . Pigs were experimentally infected with the parental virus, J1'73 strain, and viruses recovered from cells transfected with the plasmids pSVLSJ1 and pSVLS00 {Inoue T, Yamaguchi S, Saeki T, Sekiguchi K, J Gen Virol 71: 1,835-1,838 (1990)} corresponding to the pathogenic (J1'73) and non-pathogenic (H/3'76) Japanese strains of the SVDV, respectively . All pigs inoculated with the virus recovered from pSVLSJ1 produced clinical signs of similar severity to those inoculated with the parental J1'73 strain . In contrast, pigs inoculated with the virus recovered from pSVLS00 did not show any clinical signs . Viruses recovered from cells transfected with either pSVLSJ1 or pSVLS00 therefore retained the in vitro characteristics and the in vivo pathogenicity of their respective parental strains.

Am J Med Sci, 1998 Jul, 316(1), 21 - 8
Medical management of sinusitis; Kaliner M; Sinusitis is both prevalent and costly, affecting more than 14% of the population and costing more than $3.5 billion . The signs and symptoms of sinusitis can be subtle: a night cough, chronic nasal congestion, postnasal drip, or recurring headaches . Diagnosis requires a comprehensive understanding of nasal physiology, anatomy, and allergic and immunologic abnormalities, and sinonasal microbiology . The most common events leading to sinusitis are colds, allergic and nonallergic rhinitis, and anatomic defects which interfere with the sinus outflow tracks . Treatment involves drainage of the congested sinuses and elimination of the pathogenic bacteria . Drainage can be accomplished medically by opening the sinus ostia through the use of decongestants and topical corticosteroids; bacteria are effectively eliminated by washing the sinuses with saline and through use of appropriate antibiotics . In patients with recurrent disease, it may be appropriate to continue nasal washing and topical corticosteroids for extended periods of time, or even permanently . With proper medical treatments, most patients do extremely well and do not require surgery . Surgery is aimed at facilitating sinus drainage by widening the outflow tracks and removing anatomic obstructions to adequate drainage . Although we now understand some of the dynamics of sinusitis, more research is needed to clarify our unanswered questions.

Ann N Y Acad Sci, 1998 Jun 29, 849, 146 - 51
Vaccination against contagious bovine pleuropneumonia and the use of molecular tools in epidemiology; Thiaucourt F et al.; Contagious bovine pleuropneumonia is a serious threat to cattle not only in Africa but also in southern Europe and possibly Asia . It is now present in countries that had been free of the disease for many years, giving rise to doubts about the efficiency of the control strategies . In Africa CBPP is controlled mainly by a vaccination policy that uses variant strains of Mycoplasma mycoides subsp mycoides biotype SC, called T1/44 or T1sr . Until recently, it was not possible to differentiate the various strains within the biotype and consequently to identify the vaccine strains . Restriction analysis of mycoplasma DNA with HindIII and Pst1 has been applied to 24 strains of African origin and one European strain . Each enzyme gave rise to different restriction profiles and the combination of the results permitted subdivision of these strains into 9 groups . Interestingly, some profiles of pathogenic strains seem to be restricted to certain geographical areas . The profile of the poorly immunogenic vaccinal strain KH3J is also very peculiar, and it is easily distinguished from that of the other vaccine strains originating from T1 . This technique is simple once the strains are isolated . Efforts are now under way to use molecular tools based on PCR products to alleviate the difficulty of isolation.

Eur Respir J, 1998 Jun, 11(6), 1405 - 8
Serial sputum cell counts in the management of chronic airflow limitation; Parameswaran K et al.; This case study illustrates the usefulness of serial induced sputum cell counts from cytospins to investigate the nature of airway inflammation in a patient presumed to have prednisone-dependent asthma for 30 yrs . She had bronchiectasis and chronic airflow limitation . Exacerbations of breathlessness were associated with an increase in chronic airflow limitation with little or no sputum . Induced sputum showed elevated total cell and neutrophil counts at each exacerbation with no increase in the proportion of eosinophils . Pathogenic bacteria were cultured at each flare-up . The dose of prednisone was reduced progressively and each exacerbation was treated with an appropriate antibiotic without increasing the dose of prednisone, as was the case previously . The infections were associated with bronchiectasis of the right upper lobe which was removed . Examination of the specimen confirmed neutrophilic infiltration and did not show the usual airway structural changes of asthma . These results provide further evidence of the value of sputum cell counts in practice, in this case to prevent overtreatment with prednisone in a patient with recurrent deteriorations in airflow which were due to recurrent infections.

Curr Opin Periodontol, 1997, 4, 64 - 8
Can surgery be justified for patients with periodontitis?
Wilson TG Jr.
There is a debate concerning the role that surgical procedures should play in the treatment of inflammatory periodontal diseases . This review details some of the situations in which surgery can be of benefit . Benefits include obtaining shallower probing depths and therefore reducing the areas that are hospitable to pathogenic bacteria associated with disease . Also, removal of tooth-accumulated materials such as plaque and calculus in probing depths greater than 5 mm is more predictable with surgery . In some forms of aggressive periodontitis, elimination of potentially pathogenic bacteria is found more frequently with surgical procedures . Regeneration of lost bone and attachment apparatus are predictable only with surgery.

Curr Opin Periodontol, 1997, 4, 119 - 26
Prosthodontic and periodontal considerations for implant-supported dental restorations; Cooper L et al.; In the past two years, many reports concerning the outcome of treatment using dental implants have included more detailed data which allow insight into prosthodontic and periodontal considerations that affect success . It has become evident that unique biomechanical sequelae reflect the screw-joint character of the dental implant prosthesis . The relative stability of the screw joint and the biomechanical integrity of the components and prostheses themselves are new issues to contend with for restorative dentistry . The biologic sequelae of maintaining the implant-supported prostheses are revealed by bone maintenance and peri-implant mucosal health . The microbiologic similarity of tooth and implant-associated plaque at inflamed sites suggests that infected teeth are sources of potentially pathogenic bacteria at implants . However, the pathogenesis of inflammatory disease at implants is not fully defined . The evaluation and prognostic criteria of peri-implant inflammation remain controversial topics . The present aggregate data indicate that the long-term evaluation of implant-supported dental prosthesis must be performed with cautious optimism and attention to general biomechanical and biologic factors.

Toxicon, 1998 Apr, 36(4), 665 - 85
Interactions between bacterial toxins and intestinal cells; Popoff MR; Bacterial toxins which act on intestinal cells display a great diversity of size, structure and mode of action . Some toxins interact with the cell by transducing a signal across the membrane leading to stimulation of intracellular second messenger (E . coli heat stable enterotoxin), others form pores (C . perfringens enterotoxin, ...) permitting the leakage of cellular components and cell lysis . The most sophisticated toxins comprise at least two functional domains or components, one being a binding domain permitting the internalization into the cell of an enzymatic domain which modifies an intracellular target . The enzymatic modification (ADP-ribosylation, UDP-glucosylation, glycohydrolysis, proteolysis, ...) of a specific target (heterotrimeric G-protein, small G-protein, monomeric actin, ribosomal RNA, ...) alters the cell physiology (increase of ions and water secretion, cytoskeleton rearrangement, protein synthesis inhibition, apoptosis, ...) and tissue organization (modification of barrier permeability, necrosis, ...) . The study of bacterial toxins leads to the understanding of the interactions between pathogenic bacteria and their hosts and constitutes also a new approach in cell biology, by facilitating the exploration of certain regulatory pathways such as that controlling actin polymerization.

Rev Inst Med Trop Sao Paulo, 1997 Jul-Aug, 39(4), 203 - 7
Differentiation of pathogenic and non-pathogenic leptospires by means of the polymerase chain reaction; Parma AE et al.; A polymerase chain reaction was carried out to detect pathogenic leptospires isolated from animals and humans in Argentina . A double set of primers (G1/G2, B64-I/B64-II), described before, were used to amplify by PCR a DNA fragment from serogroups belonging to Leptospira interrogans but did not allow to detect saprophytic strains isolated from soil and water (L . biflexa) . This fact represents an advantage since it makes possible the differentiation of pathogenic from non-pathogenic leptospires in cultures . The sensitivity of this assay has been determined, allowing to detect just only 10 leptospires in the reaction tube . Those sets of primers generated either a 285 bp or 360 bp fragment, depending on the pathogenic strain.

Plant J, 1998 Apr, 14(2), 247 - 57
Glucocorticoid-inducible expression of a bacterial avirulence gene in transgenic Arabidopsis induces hypersensitive cell death; McNellis TW et al.; Pathogenic strains of Pseudomonas syringae pv . tomato carrying the avrRpt2 avirulence gene specifically induce a hypersensitive cell death response in Arabidopsis plants that contain the complementary RPS2 disease resistance gene . Transient expression of avrRpt2 in Arabidopsis plants having the RPS2 gene has been shown to induce hypersensitive cell death . In order to analyze the effects of conditional expression of avrRpt2 in Arabidopsis plants, transgenic lines were constructed that contained the avrRpt2 gene under the control of a tightly regulated, glucocorticoid-inducible promoter . Dexamethasone-induced expression of avrRpt2 in transgenic lines having the RPS2 gene resulted in a specific hypersensitive cell death response that resembled a Pseudomonas syringae-induced hypersensitive response and also induced the expression of a pathogenesis-related gene (PR1) . Interestingly, high level expression of avrRpt2 in a mutant rps2-101C background resulted in plant stress and ultimately cell death, suggesting a possible role for avrRpt2 in Pseudomonas syringae virulence . Transgenic RPS2 and rps2 plants that contain the glucocorticoid-inducible avrRpt2 gene will provide a powerful new tool for the genetic, physiological, biochemical, and molecular dissection of an avirulence gene-specified cell death response in both resistant and susceptible plants.

J Theor Biol, 1998 Feb 21, 190(4), 379 - 87
On the origin of plasmid-borne, extended-spectrum, antibiotic resistance mutations in bacteria; Bastarrachea F; Many antibiotic resistance mutations arise in pathogenic bacteria that harbor plasmids (R-plasmids) . Resistance to third generation cephalosporins, for instance, largely occurs by one or more point mutations in plasmid bla genes that expand the resistance spectrum of beta-lactamases . Here I review relevant evidence underlying the worldwide emergence of extended spectrum beta-lactamases (ESBLs) . The conclusion reached is that the origin of these resistance-conferring mutations cannot be explained by a series of single point mutation and selection events . Instead, highly advantageous stochastic processes might exist that generate alterations in the sequence or the conformation of particular regions in chromosomal or plasmid genomes such as bla, i.e., recombination or mutation . Several explanations for the origin of ESBLs are reviewed but direct experimental evidence to support or to invalidate them is still lacking . The cellular conditions under which ESBLs arise are unknown; however, involvement of nutritional stresses inside natural animal hosts and of plasmid conjugal functions appear likely .

Vojnosanit Pregl, 1998 Jan-Feb, 55(1), 87 - 90
{Successful treatment of people with severe body injuries caused rabid animal bites}; Golubovic S; Seven patients were presented with severe injuries seeking medical help 3-10 days after being bitten by rabid animals . Just one of those subjects underwent timely and correct surgical management . Three patients were with complete, and four with incomplete antirabic prophylaxis . Two patients did not receive human rabies immunoglobulin, and another two did not receive HDC-RV vaccine . At least 3 patients were expected to develop rabies, but it did not happen . The course of these cases could be explained by the existence of less pathogenic strains of virus in Banja Luka region.

Microbiology, 1998 May, 144 ( Pt 5), 1197 - 203
Characterization of novel immunodominant antigens of Mycobacterium tuberculosis; Amara RR et al.; Seven novel antigens of Mycobacterium tuberculosis, which had previously been identified based on reactivity to sera from patients with tuberculosis, were characterized . Nucleotide sequence analysis of the genes encoding these seven antigens identified one of them as the FtsH and a second as the aminoimidazole ribotide synthase of M . tuberculosis . Antisera raised to the recombinant forms of each of these seven antigens were used to study the distribution of these proteins within mycobacterial species as well as to determine their subcellular localization and hydrophobicity . Four of the seven antigens were conserved only among pathogenic strains of mycobacteria . Of the seven proteins studied, FtsH and a second protein of unknown identity were localized in membranes . Two were cytosolic, while two others, which had a high proline contents, were tightly associated with the cell wall . One protein was secreted . This secreted protein could be identified by serum from a majority of tuberculosis patients but not BCG-vaccinated individuals, suggesting its potential use in the immunodiagnosis of tuberculosis.

Clin Diagn Lab Immunol, 1998 May, 5(3), 299 - 302
Differentiation of F18ab+ from F18ac+ Escherichia coli by single-strand conformational polymorphism analysis of the major fimbrial subunit gene (fedA); Bosworth BT et al.; Toxin-producing Escherichia coli expressing F18 fimbriae colonizes the small intestines of weaned pigs and causes diarrhea, edema disease, or both . The F18 family is composed of two antigenic variants, F18ab and F18ac . Because many strains do not express F18 fimbriae in vitro, identification and differentiation of these two variants are difficult . Single-strand conformational polymorphism (SSCP) analysis is a rapid method for identifying genetic mutations and polymorphisms . The F18 major fimbrial subunit genes (fedA) of 138 strains were amplified by PCR, and genetic differences were detected by SSCP analysis . The SSCP analysis of the fedA gene differentiated F18ab+ strains from F18ac+ strains . Most strains classified as F18ab+ by SSCP analysis contained Shiga toxin 2e and enterotoxin genes . Most strains classified as F18ac+ by SSCP analysis contained only enterotoxin genes . The SSCP analysis was a useful method for predicting the antigenicity of F18+ E . coli and could also be used for analysis of other virulence genes in E . coli and other pathogenic bacteria.

Protein Sci, 1998 May, 7(5), 1259 - 61
Crystallization and preliminary X-ray diffraction analysis of gingipain R2 from Porphyromonas gingivalis in complex with H-D-Phe-Phe-Arg-chloromethylketone; Banbula A et al.; Gingipain R2 is a 50 kDa proteinase from the oral pathogenic bacterium Porphyromonas gingivalis . This proteinase, which displays no significant sequence homology to any protein previously analyzed by X-ray crystallography, has been crystallized using the vapor diffusion method . Two different crystal forms were obtained from a solution containing polyethylene glycol (MW 8,000) (space group P2(1)2(1)2(1)) or magnesium sulfate (space group R3) as precipitating agent . Complete diffraction data sets have been collected up to 2.0 and 2.9 A resolution, respectively . Cell dimensions are a = 51.9 A, b = 79.9 A, and c = 99.6 A (P2(1)2(1)2(1)), and a = b = 176.6 A, and c = 143.4 A (R3) . Considerations of the possible values of Vm accounts for the presence of one monomer per asymmetric unit in the case of the orthorhombic crystal form, whereas the rhombohedral crystal form, together with the analysis of the self-rotation function, could accommodate a tetramer in the asymmetric unit.

Inflammation, 1998 Jun, 22(3), 253 - 67
Activation of transcription factors and IL-8 expression in neutrophils stimulated with lipopolysaccharide from Porphyromonas gingivalis; Sugita N et al.; DNA binding activity of NF-kappa B and AP-1 were examined in neutrophils stimulated with LPS purified from P . gingivalis, a major pathogenic bacteria of periodontitis lesion . Porphyromonas gingivalis LPS enhanced the activity reaching a peak at a concentration of 500 ng/ml in the absence of serum . The NF-kappa B activation stimulated with 10 ng/ml of P . gingivalis LPS was suppressed approximately 44% by treatment of neutrophils with anti-CD14 antibody under the presence of serum . Increase in the steady-state IL-8 mRNA level was concomitantly observed by stimulation of neutrophils with 500 ng/ml of P . gingivalis LPS under the absence of serum . These results indicate that P . gingivalis LPS activates NF-kappa B and AP-1 in both serum-dependent and -independent manners, followed by increased IL-8 transcription in neutrophils, and suggested a role for P . gingivalis LPS in IL-8 synthesis by neutrophils in inflamed gingiva and GCF.

Br Med Bull, 1998, 54(1), 105 - 20
H . pylori virulence factors; Atherton JC; Among people infected with Helicobacter pylori, the virulence of the infecting strain is a major determinant of who develops disease . Strains producing vacuolating cytotoxin activity are more commonly isolated from people with peptic ulcers than without . The gene encoding the toxin, vacA, varies between strains, especially in its signal sequence and mid regions . vacA genotype influences cytotoxin activity, and signal sequence type correlates closely with peptic ulceration . Infection with strains possessing cagA (cytotoxin associated gene A) is more common among people with peptic ulceration or gastric adenocarcinoma than without . cagA is a marker for the cag pathogenicity island, which includes genes necessary for the enhanced inflammation induced by pathogenic strains . Serological detection of infection with cagA+ strains is at present the best practical test for virulence . However, before a strategy of screening and selective treatment can be considered, it is important to assess whether cagA- strains are entirely non-pathogenic.

Exp Parasitol, 1998 May, 89(1), 71 - 7
Entamoeba histolytica HM1:IMSS: hemoglobin-degrading neutral cysteine proteases; Serrano-Luna JJ et al.; Entamoeba histolytica HMI:IMSS trophozoites were able to utilize human hemoglobin but not hemin as a sole iron source to grow in vitro . Proteases from crude extracts of E . histolytica degraded human, porcine, and bovine hemoglobins at pH 7.0 . These proteolytic activities were found by electrophoresis in SDS-polyacrylamide gels copolymerized with hemoglobin, with apparent molecular weights of 116, 82, and 21 kDa, the 82-kDa protein being the most active protease against this substrate . The proteases were classified in the cysteine group since the activities were inhibited by l-trans-epoxysuccinylleucylamido(4-guanidino)butane, p-hydroxymercuribenzoate, iodoacetate, and N-ethylmaleimide and activated with dithiothreitol . Other pathogenic strains of E . histolytica showed the same pattern of hemoglobinases . These hemoglobin-degrading proteases could be playing an important role in iron acquisition by E . histolytica.

Res Virol, 1998 Mar-Apr, 149(2), 75 - 86
Nitric oxide synthesis during acute SIV mac251 infection of macaques; Blond D et al.; During HIV1 infection, nitric oxide (NO) could significantly contribute to immune dysregulation by its multiple effects on the modulation of the host immune response . The in vivo regulation of NO production is attributable to several nitric oxide synthases, one of which is a cytokine-inducible enzyme (iNOS) . In vitro experiments suggest that iNOS expression in macrophages may be directly modulated by HIV infection . Acute infection of macaques with a pathogenic strain of the simian immunodeficiency virus (SIV) represents a relevant animal model for the in vivo study of the relationships between iNOS expression and lentiviral replication . Indeed, acute infection in this model is characterized by high rates of viral replication associated with early cytokine dysregulations, in the absence of opportunistic infection . In our experiment, two cynomolgus macaques were inoculated intravenously with a pathogenic isolate of SIVmac251, and iNOS gene expression was investigated ex vivo during acute infection in mononuclear cells obtained from bronchoalveolar lavage (BALMCs) . An enhancement of this gene expression was observed as early as the second week of infection, at the time of peak of systemic viraemia, and increased until day 31 p.i . This overexpression was concomitant with a marked linear increase in IFN gamma expression in BALMCs . At the time of systemic viral load peak, the production of NO in plasma of these two monkeys was evidenced by the detection of large amounts of nitrate.

Curr Genet, 1998 Mar, 33(3), 225 - 30
A cutinase-encoding gene from Phytophthora capsici isolated by differential-display RT-PCR; Munoz CI et al.; To detect and ultimately isolate genes of Phytophthora capsici the expression of which is induced during its interaction with pepper, a comparative analysis of gene expression in the wild-type pathogenic fungus with expression in a non-pathogenic (Nop) mutant reduced in cutinase and esterase activities was performed by the differential display of mRNAs . Discrimination of fungal genes induced in planta, from plant genes induced in response to the pathogen, was accomplished by exposure of the mycelium to bare-rooted seedlings of pepper (Capsicum annuum) in sterile water, to allow the initiation of infection, and then physical removal of the induced mycelium . With six sets of primer combinations, eight cDNA fragments (representing fungal genes) were present in planta only for the pathogenic strain . RNA-blot analysis showed that the transcripts detected accumulated to detectable levels only at early stages of the interaction . Sequence analysis and database searches revealed homology of one of the cDNA clones to fungal cutinases . The 218 amino-acid sequence predicted from sequencing a genomic clone of P . capsici suggested a protein of molecular weight of 23 980 Da with similarity to fungal cutinases previously characterized . These results indicated that differential-display analysis is sufficiently sensitive to be applied for the detection and isolation of fungal genes induced during a plant-pathogen interaction.

J Parasitol, 1998 Apr, 84(2), 311 - 5
Vaccination of mice with Neospora caninum: response to oral challenge with Toxoplasma gondii oocysts; Lindsay DS et al.; Neospora caninum is a protozoan parasite that can cause severe disease in mammals . Two experiments were conducted to examine the effects of subcutaneous (s.c.) vaccination with Hank's balanced salt solution (HBSS), 1 x 10(5) N . caninum NC-1 strain tachyzoites or 1 x 10(5) Toxoplasma gondii TS-4 strain tachyzoites on challenge oral infections in mice with sporulated VEG strain T . gondii oocysts (1 X 10(3) oocysts exp . 1 and 5 x 10(3) oocysts exp . 2) . An additional study, experiment 3, evaluated s.c . challenge with 2.5 X 10(3) tachyzoites of the highly virulent RH strain of T . gondii after vaccination with HBSS, NC-1 tachyzoites, or TS-4 tachyzoites . Mice vaccinated with NC-1 strain tachyzoites survived significantly (P < 0.05) longer than mice given HBSS in experiment 1, but not in experiments 2 and 3 . Mice vaccinated with TS-4 strain tachyzoites survived significantly longer than HBSS-vaccinated mice in experiments 1, 2, and 3 and significantly longer than mice vaccinated with the NC-1 strain in experiments 2 and 3 . Toxoplasma gondii tissue cyst numbers were significantly lower for mice vaccinated with TS-4 strain tachyzoites than mice vaccinated with HBSS or the NC-1 strain tachyzoites in experiment 1 . No difference was observed in tissue cyst numbers in mice vaccinated with HBSS or NC-1 strain tachyzoites in experiment 1 . No HBSS-vaccinated mice survived experiment 2, and the numbers of T . gondii tissue cysts were significantly lower for mice vaccinated with the TS-4 strain tachyzoites compared to NC-1 strain tachyzoites . No HBSS- or NC-1-vaccinated mice survived RH strain challenge in experiment 3 . Results of these experiments indicate that infection with N . caninum provides some protection against fatal oral infection with T gondii oocysts of a moderately pathogenic strain but not tachyzoites of a highly pathogenic strain . The protection provided by N . caninum is much less than that provided by previous exposure to T . gondii, and the numbers of tissue cysts in the brains of mice are not significantly (P > 00.5) lowered.

J Eukaryot Microbiol, 1998 Mar-Apr, 45(2), 28S - 33S
Molecular changes in Entamoeba histolytica in response to bacteria; Bhattacharya A et al.; Entamoeba histolytica, the protozoan parasite, is the causative agent of amoebiasis . The degree of virulence, as inferred from invasiveness, of potentially pathogenic strains may be regulated by both host and parasite factors that determine the gut environment . One such factor that plays an important role is the bacterial flora in the gut . Previous studies have clearly shown that bacterial flora is an important determinant of virulence in E . histolytica . However, the exact nature of changes induced in E . histolytica in response to bacteria and their role in virulence is not clear . In this study the levels of a number of molecules potentially important in virulence mechanisms were determined in E . histolytica cells grown with and without normal human bacterial flora, using enzyme-linked immunosorbent assay . Significant changes were observed only after the E . histolytica cells had been adapted to grow with bacterial flora for a number of generations, and not in short term culture.

Endod Dent Traumatol, 1997 Aug, 13(4), 176 - 9
Radiological assessment of the effects of potential root-end filling materials on healing after endodontic surgery; Chong BS et al.; The effects of three root-end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere . The materials compared were a light-cured glass ionomer cement (Vitrebond), a reinforced zinc oxide-eugenol cement (Kalzinol) and amalgam . The root canals of 27 two-rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions . The roots were apicected and root-end cavities filled with the tested filling materials . The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots) . Radiographs were taken of each jaw section and subjected to image analysis . Healing was evaluated based on measurements of the size of the periradicular radiolucent areas . ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials . These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported . The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.

Int Endod J, 1997 Jul, 30(4), 240 - 9
Short-term tissue response to potential root-end filling materials in infected root canals; Chong BS et al.; The short-term tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol), were compared with that to amalgam using a previously devised experimental model . In 24 premolar teeth of beagle dogs (47 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periradicular lesions . On each root, an apicoectomy was performed and root-end cavities prepared to receive fillings of each material . The teeth and surrounding jaw were removed after 2 weeks (23 roots) and 1 week (24 roots); they were then prepared for histological examination . The tissue response to amalgam fillings after 2 weeks and 1 week was marked by moderate or severe inflammation on all roots, and extended to < or = 0.5 mm or > 0.5 mm in 15 out of 16 roots . In contrast, after 2 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation, while the tissue response to Vitrebond was the best of the three materials, and was also the least extensive . After 1 week, the overall best tissue response was with Vitrebond, followed by Kalzinol . The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were not statistically significant (P < 0.02) . However, the differences between materials for both time periods with no inflammation or inflammation extending < 0.2 mm when compared with that with inflammation extending > 0.2 mm (< or = 0.5 mm or > 0.5 mm) were statistically significant (P < 0.01) . Apart from amalgam, in which healing was marked by the persistence of a localized focus of inflammation adjacent to the root-end filling, even though there were intersample variations, there was little overall difference in the temporal and qualitative healing response to Vitrebond and Kalzinol . Both Vitrebond and Kalzinol have potential as root-end filling materials, as the tissue response was considerably more favourable than that to amalgam even in the short-term.

Curr Eye Res, 1998 Mar, 17(3), 225 - 30
An immortalized hamster corneal epithelial cell line for studies of the pathogenesis of Acanthamoeba keratitis; Halenda RM et al.; PURPOSE: The protozoan Acanthamoeba produces a severe keratitis in a small percentage of people, especially contact lens-wearers . The purpose of this work was to develop and characterize an immortalized line of hamster corneal epithelial cells to be used in studies of the pathogenesis of Acanthamoeba keratitis . METHODS: Hamster corneal epithelial cells were maintained in primary culture and immortalized using simian virus 40 (SV40) . Foci of transformed cells were cloned and subsequently characterized by phase-contrast microscopy and immunocytochemistry . Growth characteristics of the clone that were analyzed included loss of dependence on conditioned medium and ability to grow in soft agar . Cytotoxicity experiments were performed, to determine whether the selected clone was susceptible to Acanthamoeba infection in vitro . RESULTS: A cell line which exhibited epithelial morphology, as determined by phase contrast microscopy, was selected and cloned . Immunocytochemistry demonstrated the presence of keratin in the cloned cells, confirming the epithelial nature of the cell line . Immortalization was shown by loss of dependence on fibroblast-conditioned medium, ability to form colonies in soft agar and no apparent senescence following numerous passages in culture . This cell line was found to be sensitive to the cytotoxic effects of a pathogenic strain of Acanthamoeba . CONCLUSIONS: An immortalized line of hamster corneal epithelial cells was developed . This clone is susceptible to infection with Acanthamoeba and will be a useful tool with which to investigate the pathogenesis of Acanthamoeba keratitis.

Rev Sci Tech, 1997 Apr, 16(1), 79 - 82
{Risk for the transmission of Newcastle disease by contaminated poultry products}; Guittet M et al.; Poultry products contaminated with pathogenic strains of Newcastle disease virus are a source of virus transmission to susceptible poultry flocks . The probability of contamination varies according to the type of product . Research conducted by various laboratories in Europe has shown that pathogenic virus can be isolated from the carcasses of chickens, whether vaccinated or not, during a brief period after experimental infection . Eggs laid by hens infected with Newcastle disease virus present a very low risk . Furthermore, feathers, bones, blood and offal present potential risks if they are incorporated in poultry feed . Finally, poultry droppings used as a fertiliser can present a major risk of infection in certain circumstances.

Proc Natl Acad Sci U S A, 1998 Mar 3, 95(5), 2044 - 9
Multiple evolutionary origins of the fungus causing Panama disease of banana: concordant evidence from nuclear and mitochondrial gene genealogies; O'Donnell K et al.; Panama disease of banana, caused by the fungus Fusarium oxysporum f . sp . cubense, is a serious constraint both to the commercial production of banana and cultivation for subsistence agriculture . Previous work has indicated that F . oxysporum f . sp . cubense consists of several clonal lineages that may be genetically distant . In this study we tested whether lineages of the Panama disease pathogen have a monophyletic origin by comparing DNA sequences of nuclear and mitochondrial genes . DNA sequences were obtained for translation elongation factor 1alpha and the mitochondrial small subunit ribosomal RNA genes for F . oxysporum strains from banana, pathogenic strains from other hosts and putatively nonpathogenic isolates of F . oxysporum . Cladograms for the two genes were highly concordant and a partition-homogeneity test indicated the two datasets could be combined . The tree inferred from the combined dataset resolved five lineages corresponding to "F . oxysporum f . sp . cubense" with a large dichotomy between two taxa represented by strains most commonly isolated from bananas with Panama disease . The results also demonstrate that the latter two taxa have significantly different chromosome numbers . F . oxysporum isolates collected as nonpathogenic or pathogenic to other hosts that have very similar or identical elongation factor 1alpha and mitochondrial small subunit genotypes as banana pathogens were shown to cause little or no disease on banana . Taken together, these results indicate Panama disease of banana is caused by fungi with independent evolutionary origins.

Biochem Biophys Res Commun, 1998 Feb 24, 243(3), 804 - 7
Overexpression of a hydrogen peroxide-resistant periplasmic Cu,Zn superoxide dismutase protects Escherichia coli from macrophage killing; Battistoni A et al.; We have studied the effect of H2O2 on the activity of the Escherichia coli Cu,ZnSOD showing that, unlike the bovine enzyme, this bacterial Cu,ZnSOD is highly resistant to inactivation by hydrogen peroxide . In view of the key role played by oxygen radicals in bacterial killing by phagocytes, we have tested the ability of E . coli strains expressing different amounts of Cu,ZnSOD in the periplasmic space to survive the phagocytic attack of activated macrophages . Overexpression of the enzyme effectively protected the bacterial cell from macrophage killing . The results obtained support the hypothesis that in pathogenic bacteria periplasmic Cu,ZnSOD may reduce the oxyradical damages induced by the respiratory burst and therefore be important in virulence.

Mol Microbiol, 1998 Jan, 27(1), 99 - 106
Differences in chromosome number and genome rearrangements in the genus Brucella; Jumas-Bilak E et al.; We have studied the genomic structure and constructed the SpeI, PacI and I-CeuI restriction maps of the four biovars of the pathogenic bacterium Brucella suis . B . suis biovar 1 has two chromosomes of 2.1 Mb and 1.15 Mb, similar to those of the other Brucella species: B . melitensis, B . abortus, B . ovis and B . neotomae . Two chromosomes were also observed in the genome of B . suis biovars 2 and 4, but with sizes of 1.85 Mb and 1.35 Mb, whereas only one chromosome with a size of 3.1 Mb was found in B . suis biovar 3 . We show that the differences in chromosome size and number can be explained by rearrangements at chromosomal regions containing the three rrn genes . The location and orientation of these genes confirmed that these rearrangements are due to homologous recombination at the rrn loci . This observation allows us to propose a scheme for the evolution of the genus Brucella in which the two chromosome-containing strains can emerge from an hypothetical ancestor with a single chromosome, which is probably similar to that of B . suis biovar 3 . As the genus Brucella is certainly monospecific, this is the first time that differences in chromosome number have been observed in strains of the same bacterial species.

Vet Microbiol, 1997 Dec, 59(1), 79 - 87
Adherence pili of pathogenic strains of avian Escherichia coli; Vidotto MC et al.; Fifty strains of Escherichia coli isolated from colisepticemic chickens in Londrina, Brazil, were examined for presence of gene sequences for pil and pap, hemagglutination, and adherence to chicken tracheal cells . Forty-one strains were pil+ and 22 of these showed mannose sensitive (MS) hemagglutination (MSHA) of guinea-pig erythrocytes, indicating that they possessed only type 1 pili . Seven strains were pap+ and 6 of these caused mannose resistant (MR) hemagglutination (MRHA) of human erythrocytes . Twenty-four strains (17 of which caused MSHA) showed MS-adherence to chicken tracheal cells and the remaining 26 showed MR-adherence . The former typically adhered to the mucus layer whereas the latter usually adhered to the mucosal epithelium . It is concluded that MS adherence to chicken tracheal cells is correlated with expression of type 1 fimbriae and that MR-adherence to chicken tracheal cells cannot always be attributed to P pili.

Int Dent J, 1997 Apr, 47(2), 61 - 87
Risk assessment for periodontal diseases; Page RC et al.; Assessment of risk for periodontitis is still in its infancy . Nevertheless, a sufficient amount of dependable information exists to begin using risk assessment in the day to day practice of dentistry . The purpose of this paper is to summarise existing information about risks for periodontitis in a manner that is useful to practitioners . Risks for moderate to severe periodontitis that have been identified include cigarette smoking, advancing age, diabetes mellitus and certain other systemic conditions . These include, osteoporosis and HIV infection and conditions such as irradiation and immunosuppressive drugs that interfere with normal host defences, specific pathogenic bacteria in the subgingival flora, microbial deposits and poor oral hygiene status, bleeding on probing, previous disease experience and severity, and inheritance . Some risks such as pathogenic bacteria in the subgingival flora are strongly linked to causation of the disease while others such as bleeding on probing may indicate enhanced risk for future disease but are not known to be involved in causation and still others such as advancing age may be background factors that enhance susceptibility . While some risks such as cigarette smoking can be modified to lower the level of risk, others such as ageing are immutable and cannot be modified but need to be considered in overall risk assessment . A goal of periodontal diagnosis, treatment planning and therapy is to lower risk for future periodontal deterioration to the maximal extent . One approach to achieving this goal is described.

Trends Microbiol, 1997 Dec, 5(12), 489 - 95
Hrp-controlled interkingdom protein transport: learning from flagellar assembly?
He SY.
Plant pathogenic bacteria appear to deliver avirulence and virulence proteins through the cell wall and into the host cells via an Hrp (hypersensitive reaction and pathogenicity)-encoded type III secretion system . Recent results suggest that there is a similarity between this secretion system and the flagellum assembly apparatus.

Am J Physiol, 1997 Dec, 273(6 Pt 1), G1349 - 58
Translocation of verotoxin-1 across T84 monolayers: mechanism of bacterial toxin penetration of epithelium; Philpott DJ et al.; Verotoxin-producing Escherichia coli (VTEC) are pathogenic bacteria associated with diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome . Verotoxins (VTs) elaborated by these organisms produce cytopathic effects on a restricted number of cell types, including endothelial cells lining the microvasculature of the bowel and the kidney . Because human intestinal epithelial cells lack the globotriaosylceramide receptor for VT binding, it is unclear how the toxin moves across the intestinal mucosa to the systemic circulation . The aims of this study were to determine the effects of VT-1 on intestinal epithelial cell function and to characterize VT-1 translocation across monolayers of T84 cells, an intestinal epithelial cell line . VT-1 at concentrations up to 1 microgram/ml had no effect on the barrier function of T84 monolayers as assessed by measuring transmonolayer electrical resistance (102 +/- 8% of control monolayers) . In contrast, both VT-positive and VT-negative VTEC bacterial strains lowered T84 transmonolayer resistance (45 +/- 7 and 38 +/- 6% of controls, respectively) . Comparable amounts of toxin moved across monolayers of T84 cells, exhibiting high-resistance values, as monolayers with VTEC-induced decreases in barrier function, suggesting a transcellular mode of transport . Translocation of VT-1 across T84 monolayers paralleled the movement of a comparably sized protein, horseradish peroxidase . Immunoelectron microscopy confirmed transcellular transport of VT-1, since the toxin was observed within endosomes and associated with specific intracellular targets, including the Golgi network and endoplasmic reticulum . These data present a mode of VT-1 uptake by toxin-insensitive cells and suggest a general mechanism by which bacterial toxins lacking specific intestinal receptors can penetrate the intestinal epithelial barrier.

Biochem Biophys Res Commun, 1997 Dec 18, 241(2), 341 - 6
Hinderance of apoptosis and phagocytic behaviour induced by Escherichia coli cytotoxic necrotizing factor 1: two related activities in epithelial cells; Fiorentini C et al.; Several microbial factors are recognized able to modulate apoptosis . In this work, we analyze the activity of a toxin from pathogenic strains of Escherichia coli, the Cytotoxic Necrotizing Factor 1 (CNF1), which influences epithelial cell structure and function . This toxin activates the Rho GTP-binding protein leading to actin filament reorganization, membrane ruffling and multinucleation . Functionally, CNF1 induces a phagocytic activity in non-professional phagocytes . Surprisingly, we found that the increase of phagocytic activity induced by CNF1 corresponds to a decrease of apoptotic cell death . We therefore hypothesize that the two activities together might have a finalistic role in the pathogenesis of bacterial infection.

J Virol, 1998 Jan, 72(1), 405 - 14
Evolution of a simian immunodeficiency virus pathogen; Edmonson P et al.; Analysis of disease induction by simian immunodeficiency viruses (SIV) in macaques was initially hampered by a lack of molecularly defined pathogenic strains . The first molecularly cloned SIV strains inoculated into macaques, SIVmacBK28 and SIVmacBK44 (hereafter designated BK28 and BK44, respectively), were cases in point, since they failed to induce disease within 1 year postinoculation in any inoculated animal . Here we report the natural history of infection with BK28 and BK44 in inoculated rhesus macaques and efforts to increase the pathogenicity of BK28 through genetic manipulation and in vivo passage . BK44 infection resulted in no disease in four animals infected for more than 7 years, whereas BK28 induced disease in less than half of animals monitored for up to 7 years . Elongation of the BK28 transmembrane protein (TM) coding sequence truncated by prior passage in human cells marginally increased pathogenicity, with two of four animals dying in the third year and one dying in the seventh year of infection . Modification of the BK28 long terminal repeat to include four consensus nuclear factor SP1 and two consensus NF-kappaB binding sites enhanced early virus replication without augmenting pathogenicity . In contrast, in vivo passage of BK28 from the first animal to die from immunodeficiency disease (1.5 years after infection) resulted in a consistently pathogenic strain and a 50% survival time of about 1.3 years, thus corresponding to one of the most pathogenic SIV strains identified to date . To determine whether the diverse viral quasispecies that evolved during in vivo passage was required for pathogenicity or whether a more virulent virus variant had evolved, we generated a molecular clone composed of the 3' half of the viral genome derived from the in vivo-passaged virus (H824) fused with the 5' half of the BK28 genome . Kinetics of disease induction with this cloned virus (BK28/H824) were similar to those with the in vivo-passaged virus, with four of five animals surviving less than 1.7 years . Thus, evolution of variants with enhanced pathogenicity can account for the increased pathogenicity of this SIV strain . The genetic changes responsible for this virulent transformation included at most 59 point mutations and 3 length-change mutations . The critical mutations were likely to have been multiple and dispersed, including elongation of the TM and Nef coding sequences; changes in RNA splice donor and acceptor sites, TATA box sites, and Sp1 sites; multiple changes in the V2 region of SU, including a consensus neutralization epitope; and five new N-linked glycosylation sites in SU.

Acad Radiol, 1994 Nov, 1(3), 249 - 52
Effects of radiographic contrast media on leukocyte phagocytosis; Farrow R et al.; RATIONALE AND OBJECTIVES: Differences in leukocyte phagocytosis following exposure to different classes of radiographic contrast media (RCM) may help in the development of less toxic alternatives and be useful as a guide to contrast selection in certain patient groups . The effect of RCM on leukocyte phagocytosis of Escherichia coli was examined . METHODS: Cell population phagocytosis and individual cell phagocytic activity were assessed in a control group and in samples exposed both to the ionic RCM diatrizoate and ioxaglate and to the nonionic RCM iohexol and iotrolan by using a flow cytometer . RESULTS: The percentage of granulocytes undergoing phagocytosis was 88.4% in the control population . Following exposure to RCM, this value fell to 79.2% with iohexol, 77.6% with iotrolan, 70.5% with diatrizoate, and 68.7% with ioxaglate . The number of bacteria phagocytosed by active leukocytes was not affected by RCM . CONCLUSION: RCM adversely affect the percentage of granulocytes involved in phagocytosis but not the number of pathogenic bacteria that are phagocytosed by individual granulocytes.

Rev Environ Contam Toxicol, 1998, 154, 1 - 53
Food preservation using ionizing radiation; Andrews LS et al.; Irradiation processing has been researched extensively and is now in use worldwide for many food commodities . Irradiation has been successfully used to reduce pathogenic bacteria, eliminate parasites, decrease postharvest sprouting, and extend the shelf life of fresh perishable foods . Although food irradiation is widely accepted in world food markets, U.S . markets have been slower to accept the idea of irradiated food products . For fruits and vegetables, irradiation is not a cure for shelf life problems; cost and quality problems damage preclude its general use . It appears that the most likely use of irradiation in fruits and vegetables is as an insect control in those commodities for which there is no effective alternative method . For grains such as rice and wheat, irradiation has been used primarily to control insect infestation when insects have been shown to develop resistance to the traditional fumigation methods . Treatment of spices with irradiation doses of 10 kGy has proved to extend shelf life without causing significant changes in sensory or chemical quality . Higher doses that effectively sterilize spices, however, may cause undesirable chemical and sensorial changes . For meat, especially red meat, irradiation is considered a viable alternative in the effort to improve the safety of meat products . With time, the authors believe that economic realities and the technical superiority of irradiation for specific poultry products will lead to public acceptance of the process . Irradiation of seafood products is still being considered for approval by the USFDA, although it is currently used in Asian and European markets, especially for shrimp . It is our belief that scientifically based research in food irradiation and the positive results thereof will also prove economical in the twenty-first century . As we move to a more peaceful world with reduced threat of nuclear holocaust, these valid opinions will prevail and will overshadow the distortions and misinformation generated by the opponents of irradiation.

Science, 1997 Dec 5, 278(5344), 1800 - 3
Hyaluronan synthase of chlorella virus PBCV-1; DeAngelis PL et al.; Sequence analysis of the 330-kilobase genome of the virus PBCV-1 that infects a chlorella-like green algae revealed an open reading frame, A98R, with similarity to several hyaluronan synthases . Hyaluronan is an essential polysaccharide found in higher animals as well as in a few pathogenic bacteria . Expression of the A98R gene product in Escherichia coli indicated that the recombinant protein is an authentic hyaluronan synthase . A98R is expressed early in PBCV-1 infection and hyaluronan is produced in infected algae . These results demonstrate that a virus can encode an enzyme capable of synthesizing a carbohydrate polymer and that hyaluronan exists outside of animals and their pathogens.

Proc R Soc Lond B Biol Sci, 1997 Nov 22, 264(1388), 1629 - 38
The transmission dynamics of antibiotic-resistant bacteria: the relationship between resistance in commensal organisms and antibiotic consumption; Austin DJ et al.; We propose a mathematical model of the transmission dynamics of colonization by commensal bacteria within a human community subject to varying levels of antibiotic use designed to control morbidity induced by pathogenic strains of the normally commensal organisms . Colonization is assumed not to induce morbidity in the majority of cases, and antibiotic use is assumed to be related to the arrival and growth of pathogenic strains that give rise to infections including clinical symptoms of disease . In the absence of antibiotic resistance, the model shows how the pattern of antibiotic prescription and use can eliminate the non-pathogenic commensal strains from the host community if the fraction of people taking antibiotics with a defined efficacy exceeds some critical level . The model is extended to take account of the evolution of antibiotic resistance in the commensal population . We assume resistance may be either plasmid-mediated or conferred by selection of low-level pre-existing mutants, and that resistant organisms may experience reduced reproductive fitness . Invasion of the host community by drug-resistant commensals is possible if certain antibiotic prescribing patterns pertain . We calculate these conditions in terms of the transmission parameter of the organism and the level of antibiotic prescription and use . The model is employed to address the issues of how best to use antibiotics in populations harbouring resistant organisms, and when resistant bacteria will out-compete sensitive strains.

Laryngoscope, 1997 Dec, 107(12 Pt 1), 1579 - 85
Acute sinusitis in the rabbit: a new rhinogenic model; Marks SC; The objective of this study was to create a rhinogenic model of sinusitis using an implanted foreign body in the nasal cavity of the rabbit . The study design was a prospective controlled trial of the experimental design . In this model an obstructing foreign body was placed into the nasal cavity and then impregnated with pathogenic bacteria . This model was studied histologically using whole-mount techniques . Quantitative assessment of the degree of inflammation was made for the maxillary and ethmoid sinus and for overall effect for each animal . Bacteriologic study was performed in a limited number of animals . The results indicated that a significant infection develops in about half of animals . This peaks in intensity between 1 and 2 weeks after implantation and subsequently subsides with some evidence of long-term changes present after 4 weeks . It is concluded that this is a viable and perhaps preferable animal model to study sinusitis . Further investigation is necessary to completely characterize this model.

Acta Chir Belg, 1997 Oct, 97(5), 215 - 6
Bacterial contamination of pneumoperitoneum gas in peritonitis and controls: a prospective laparoscopic study; Taffinder NJ et al.; There is a theoretical risk that the pneumoperitoneum gas could carry bacteria in aerosol form and spread infection throughout the peritoneal cavity during laparoscopy for infective conditions such as appendicitis . The aim of this study was to attempt to culture bacteria from the pneumoperitoneum gas during laparoscopy for potentially infected cases and a group of controls . A total of 53 consecutive laparoscopies were studied, of which 21 were potentially infected and 32 served as controls . A lavage of the operative site was positive for pathogenic bacteria in almost 30% of the potentially infected group and only 3% of the control group . The pneumoperitoneum gas was bubbled through blood culture medium at the beginning and the end of the procedure, but only one of the 106 bottles grew any bacteria, and the specimen was a likely contaminant . In conclusion, we were unable to grow any significant bacteria from any of our cases despite using a sensitive method and demonstrating pathogenic bacteria in the peritoneal lavages . The pneumoperitoneum itself is unlikely to disperse bacteria.

J Perinatol, 1997 Sep-Oct, 17(5), 383 - 8
Alteration of normal gastric flora in neonates receiving ranitidine; Cothran DS et al.; OBJECTIVES: To determine if the administration of ranitidine to neonates leads to an increase in gastric pH to > or = 4 and if this increase in gastric pH correlates with gastric colonization . STUDY DESIGN: 628 pH measurements and 276 gastric cultures were obtained from 86 neonates . Twenty-three patients received ranitidine and 63 patients served as controls . RESULTS: Treated patients had a mean gastric pH of 5.6 compared with a control mean pH of 4.4 (p < 0.0001) . Gastric pH was significantly affected by feeding and postnatal age . 54 patients were colonized with pathogenic bacteria and/or yeast (n = 20 treated, n = 34 control) . Length of hospitalization (p < 0.0001), increase in gastric pH (p < 0.01), days of antibiotics before culture (p < 0.0001), and ranitidine use (p < 0.0001) were associated with an increased rate of colonization . CONCLUSIONS: The use of ranitidine did lead to a significant increase in gastric pH and with this increase in gastric pH gastric colonization rates increased . No increased frequency of infection was found in ranitidine-treated infants.

Appl Environ Microbiol, 1997 Oct, 63(10), 4069 - 74
Hydroxyapatite adherence as a means to concentrate bacteria; Berry ED et al.; Adherence to hydroxyapatite (HA) was examined as a method to concentrate bacteria from foods . Using HA at a level of 10% and suspensions of an Escherichia coli strain containing 10(9), 10(6), and 10(3) cells per ml, kinetic studies revealed that maximum adherence was attained within 5 min for all cell concentrations and that comparable log reductions (1.0 to 1.5) of cells in suspension were seen regardless of initial cell concentration . Eleven species of spoilage and pathogenic bacteria were found to adhere to HA, with seven species adhering at proportions of greater than 95% . Fluorescent viability staining revealed that cells bound to HA remained viable . There was greater than 92% adherence of indigenous bacteria to HA from three of five 1:10 dilutions of ground beef, indicating promise for the use of HA for concentrating bacteria from meat and other food samples.

J Parasitol, 1997 Oct, 83(5), 908 - 12
Mast cell hyperplasia and increased macromolecular uptake in an animal model of giardiasis; Hardin JA et al.; Giardiasis has been associated with an increase in allergic disease following infection suggesting an alteration in mucosal immune function . Jejunal in vivo and in vitro macromolecular transport, epithelial permeability, and mucosal and connective tissue mast cell counts were examined in Mongolian gerbils (35-45 g) orogastrically inoculated (I) with a pathogenic strain of Giardia lamblia and compared to age- and weight-matched, sham-treated controls (C) 6 and 21 days postinoculation . Macromolecular uptake was significantly increased in infected tissue at 6 days both in vivo (I 134 +/- 19 vs . C 74 +/- 17 ng/hr; n = 8; P < 0.05) and in vitro (I 125 +/- 17 vs . C 67 +/- 8 ng/hr/cm; n = 12; P < 0.05) . Macromolecular uptake did not differ between groups at 21 days . Infection had no effect on mucosal permeability of {51Cr}EDTA . Mucosal mast cell counts did not differ at 6 days but were significantly elevated in infected tissue at 21 days (I 33.3 +/- 6.8 vs . C 2.7 +/- 0.4 per high magnification field; n = 5; P < 0.01) as were connective tissue mast cell counts (I 1.7 +/- 0.2 vs . C 1.0 +/- 0.1 per high magnification field; n = 13; P < 0.005) . The findings indicate that during the peak phase of giardiasis, jejunal active antigen uptake is increased leading to a delayed recruitment of mucosal and connective tissue mast cells . These changes may play a role in the increased incidence of hypersensitivity reactions associated with Giardia infection.

Transplantation, 1997 Sep 27, 64(6), 936 - 7
First report of invasive amebiasis in an organ transplant recipient; Palau LA et al.; T-cell mediated immunity is an important defense mechanism against amebiasis . However, organ transplant recipients with severe T-cell immunosuppression are not at increased risk of having Entamoeba histolytica invasive disease . The reasons are unclear and probably multifactorial, but it is likely that the absence of intestinal colonization with pathogenic strains in countries where transplants occur and the judicious intake of possible contaminated food and water are important contributing factors . We describe the first report of a liver transplant recipient with severe E . histolytica colitis who was successfully treated with metronidazole without modifying his immunosuppression therapy.

Korean J Parasitol, 1997 Sep, 35(3), 203 - 10
{cDNAs encoding the antigenic proteins in pathogenic strain of Entamoeba histolytica}; Im KI et al.; The differential display reverse transcription polymerase chain reaction (DDRT-PCR) analysis was performed to identify the pathogenic strain specific amplicons . mRNAs were purified from the trophozoites of the pathogenic strain YS-27 and the non-pathogenic strain S 16, respectively . Three kinds of first stranded cDNAs were reverse transcribed from the mRNAs by one base anchored oligo-dT11M (M: A, C, or G) primers . Each cDNA template was used for DDRT-PCR analysis . A total of 144 pathogenic strain specific amplicons was observed in DDRT-PCR analysis using primer combinations of the 11 arbitrary primers and the 3 one base anchored oligo-dT11M primers . Of these, 31 amplicons were verified as the amplicons amplified only from the mRNAs of the pathogenic strain by DNA slot blot hybridization . Further characterization of the 31 pathogenic strain specific amplicons by DNA slot blot hybridization analysis using biotin labeled probes of the PCR amplified DNA of cysteine proteinase genes revealed that 21 of them were amplified from the mRNAs of the cysteine proteinase genes . Four randomly selected amplicons out of the rest 10 amplicons were used for screening of cDNA library followed by immunoscreening and all of them were turned out to be amplified from the mRNA.

Int J Food Microbiol, 1997 Jul 22, 37(2-3), 163 - 73
Acid habituation of Escherichia coli and the potential role of cyclopropane fatty acids in low pH tolerance; Brown JL et al.; A reversible adaptive tolerance to low pH termed 'acid habituation' is demonstrated for five strains of Escherichia coli . Superimposed upon the intrinsic acid tolerance of individual strains, acid habituation significantly enhances the survival of exponential phase cultures exposed to a lethal acid challenge (pH 3.0), and minimises inter-strain variability in acid tolerance . The fatty acid composition of acid habituated, non-habituated, and de-habituated exponential phase cultures is also reported . During acid habituation, monounsaturated fatty acids (16:1 omega 7c and 18:1 omega 7c) present in the phospholipids of E . coli are either converted to their cyclopropane derivatives (cy17:0 and cy19:0), or replaced by saturated fatty acids . The acid tolerance of individual strains of E . coli appears to be correlated with membrane cyclopropane fatty acid content and, thus, it is postulated that increased levels of cyclopropane fatty acids may enhance the survival of microbial cells exposed to low pH . The results presented illustrate the remarkable capacity of E . coli to adapt to environmental challenges, and have significant implications for the survival of spoilage and pathogenic bacteria, and hence for food safety.

Rev Inst Med Trop Sao Paulo, 1996 Nov-Dec, 38(6), 407 - 12
Isoenzyme profile as parameter to differentiate pathogenic strains of Entamoeba histolytica in Brazil; de Martinez AM et al.; The isoenzyme profiles (IP) of 33 strains of Entamoeba histolytica isolated from patients and carriers of two regions in Brazil (Amazonia and Southeast) were determined . The enzymes phosphoglucomutase, glucose-phosphate isomerase, hexokinase and malic enzyme were considered . IP of the strains was correlated with culture conditions, time of maintenance in laboratory and clinical history of patients . The strains were maintained under polyxenic, monoxenic and axenic culture conditions: 27 polyxenic, 1 polyxenic and monoxenic, 1 polyxenic, monoxenic and axenic and 4 axenic only . The patients were symptomatic and asymptomatic . The symptomatic patients presented either non dysenteric (NDC) or dysenteric colitis (DC), associated or not with hepatic abscess (HA) . One patient presented anal amoeboma (AM) . The analysis of IP for isolates maintained in polyxenic culture showed non pathogenic IP (I) for strains from carriers and patients with NDC, while the strains isolated from patients presenting DC, HA and AM resulted in isolates II or XIX pathogenic IP . This parameter was not able to differentiate strains from carriers from symptomatic patients when these strains were found in axenic or monoxenic culture . All these strains displayed pathogenic IP (II), demonstrating the inability of this parameter to classifying for virulence since it showed identical IP for strains isolated from carriers or symptomatic patients.

J Cell Biochem, 1997 Sep 15, 66(4), 500 - 11
Epitope conservation and immunohistochemical localization of the guanylin/stable toxin peptide receptor, guanylyl cyclase C; Nandi A et al.; The heat-stable enterotoxins (ST) are a family of cysteine-rich low-molecular weight peptides produced by pathogenic bacteria, and are one of the major causes of watery diarrhea all over the world . These toxins mediate their action by binding to an intestinal cell surface receptor that is a membrane-associated guanylyl cyclase (GCC) . This receptor also serves as the receptor for the recently characterised endogenous ligand, guanylin . We have expressed various domains of the receptor in Escherichia coli and used purified proteins for the generation of both polyclonal and monoclonal antibodies . While polyclonal antibodies were able to partially inhibit ST binding to the native receptor present in the T84 human colonic cell line, GCC:B10 monoclonal antibody did not interfere with ligand binding . Western blot analysis, using membranes prepared from human colonic T84 cells, detected two bands of size 160 and 140 kDa, representing alternately glycosylated forms of the receptor . Using the recombinant proteins, we could map the epitope of GCC:B10 monoclonal antibody to the intracellular domain of the receptor . We used the antibody to localize the receptor throughout the rat intestine, and in the porcine and bonnet monkey colon . We could detect receptor expression in the villus and the crypts of the duodenum, jejunum, ileum, and caecum, and in the crypts of the colon . Receptor expression was observed in cells that had earlier been shown to express cGMP-dependent kinase, but not the cystic fibrosis transmembrane regulator, a known downstream target of cGMP/G-kinase, which suggests that GCC/ cGMP could regulate additional cellular signal transduction machinery.

Anal Chem, 1997 Aug 15, 69(16), 3321 - 8
On-line detection of nonspecific protein adsorption at artificial surfaces; Siegel RR et al.; A detailed understanding of the interaction of proteins with artificial surfaces is essential for many applications in medicine and biochemistry . The affinity of surfaces toward proteins may, for instance, remove pharmacological proteins from media or control the adherence of pathogenic bacteria to protheses . Only a few analytical techniques now exist that can be used to study the binding process in real time, using unlabeled proteins . By investigating the adsorption kinetics of fibrinogen at differently terminated self-assembled monolayers (SAMs) of alkanethiols on thin gold films, it is demonstrated that acoustic plate-mode sensors are a promising analytical tool for studying the adsorption of proteins . In agreement with previous studies for fibrinogen, it is shown in situ that hexa(ethylene glycol)-terminated SAMs (HS(CH2)11 (OCH2CH2)6OH) exhibit very low protein adsorption and that methyl-terminated SAMs (HS(CH2)11CH3) tend to absorb large amounts of protein nonspecifically . The observed adsorption kinetics deviate from classical Langmuir behavior; these kinetics are compatible with a mechanism that involves an unfolding of fibrinogen after adsorption . Film quality is controlled by IR, XPS, and contact angle measurements.

Nutr Rev, 1997 Aug, 55(8), 306 - 7
Importance of adequate vitamin A status during iron supplementation; Ribaya-Mercado JD; Nutritional deficiencies, including iron deficiency, may promote infection by lowering the body's resistance to infectious diseases . However, it has been shown that administration of iron in developing countries can result in increased morbidity, because pathogenic bacteria may compete effectively for iron in the circulation, resulting in an exacerbation of existing infections . Improved vitamin A status may protect against this potentially harmful effect of iron supplementation in environments where infections are highly prevalent.

Acta Otolaryngol, 1997 Jul, 117(4), 569 - 73
Early post-tympanostomy otorrhea in children under 17 months of age; Valtonen H et al.; A total number of 281 consecutive children with recurrent acute otitis media (RAOM) or otitis media with effusion (OME) was treated with ventilation tubes (VT), inserted under local anesthesia . Patients were prospectively followed-up for post-tympanostomy otorrhea, classified as "early" if observed within 7 days of the tympanostomy procedure . The age of children ranged from 5 to 16 months (average 10.1 months) . VT were placed bilaterally in 279 of 281 children . The average length of otitis media (OM) history prior to tympanostomy was 3.4 months . An episode of OM had been diagnosed 1-2 times in 18.9%, 3-4 times in 68.0%, and at least 5 times in 13.1% of the children . Middle ear effusion (MEE), most often classified as mucoid was present in 65.8% of the ears . Cultures were positive for bacteria in 41 of the 185 ears with MEE (22.2%) . The mastoid air cell system was radiographically normal in 9.6% and markedly clouded in 56.6% . Early post-tympanostomy otorrhea was observed in 16.0% of ears, occurring more often when MEE, especially mucopurulent, was present at tympanostomy (p < 0.01) . The risk of otorrhea was significantly increased by a positive culture for pathogenic bacteria in MEE (p < 0.01) and highly significantly by the advanced opacification of the mastoid air cell system (p < 0.001) . It is concluded that early post-tympanostomy otorrhea in young children is caused by the advanced infectious process in the middle ear cleft, including mastoid cell system rather than by the tympanostomy procedure itself . It may indicate the need for more active treatment in this age group.

Hum Reprod, 1997 Jul, 12(7), 1464 - 75
Chlamydial serology in 1303 asymptomatic subfertile couples; Eggert-Kruse W et al.; The clinical significance of antichlamydial antibodies (Chlam Ab) was determined in a total of 1303 subfertile couples consulting for infertility investigation and treatment . Median age of the women was 30 (range 22-44) years and of the men 33 (range 21-53) years . The median duration of infertility was 4 (range 1-21) years . All patients were asymptomatic for genital tract infection . A comprehensive infertility investigation included examination of the endocrine, cervical, and tubal factor, and semen analysis, antisperm antibody (ASA) testing, sperm-mucus interaction testing in vitro using a standardized protocol, and post-coital testing (PCT) . Screening for Chlam IgG Ab was performed in serum of both partners, obtained at the same time . Simultaneous microbial cultures in genital secretions of both partners included a broad spectrum of potentially pathogenic bacteria . Elevated titres of Chlam IgG Ab as seromarker for previous infection were found in 20.8% of all women, and in 12.6% of men . Chlam Ab were significantly more frequent in partners of seropositive patients (in 51.8% of women with a Chlam Ab positive partner, compared to 15.8% of the other women) . Microbial screening outcome was not significantly related to results of chlamydial serology in both partners . In women, elevated titres of Chlam Ab were significantly associated with a tubal factor, but were not related to reduced quality of the endocervical mucus (CM), including the in-vitro penetrability of the CM (using partners' or donors' spermatozoa) . In males, Chlam Ab were not significantly related to the outcome of semen analysis, including screening for ASA (IgG and/or IgA) in semen, and several parameters of sperm functional capacity . After exclusion of couples with tubal disease, subsequent male fertility did not significantly differ in males with or without Chlam Ab . The results suggest that during basic infertility investigation, positive chlamydial serology as an easy screening procedure indicates a higher risk for a tubal infertility factor . However, in asymptomatic patients, Chlam IgG Ab in serum are not associated with a cervical factor or with the male factor, using several determinants for evaluation of semen quality including subsequent fertilizing capacity.

Toxicol Ind Health, 1997 Jul-Aug, 13(4), 519 - 26
Prevalence of pathogenic Acanthamoeba (Protozoa:Amoebidae) in the atmosphere of the city of San Luis Potosi, Mexico; Rodriguez-Zaragoza S et al.; Several species of pathogenic Acanthamoeba cause infections to humans, but amoebic keratitis is more frequently found than any other due to the increasing number of contact lens wearers in the world . Cysts and trophozoites of these amebas are airborne and may pollute water from the air . We investigated the proportion of pathogenic Acanthamoeba from the atmosphere of the city of San Luis Potosi . Samples were taken by the impinger method, every month during one year . We isolated 23 strains of Acanthamoeba, 61% of them were non-pathogenic, 31% were non-pathogenic with invasive capacity and 8% were pathogenic to mice . Almost 40% of these strains represent danger of infections to humans . The isolations were more abundant during the dry season in the south (urban) and west (suburban) stations, which means that the sanitary conditions around stands may enhance the proportion of pathogenic strains in the surroundings.

Scand J Immunol, 1997 Jul, 46(1), 35 - 40
Experimental infection of Balb/c mice with Leishmania panamensis and Leishmania mexicana: induction of early IFN-gamma but not IL-4 is associated with the development of cutaneous lesions; Guevara-Mendoza O et al.; Resistance to the Leishmaniae is associated with interferon (IFN)-gamma mediated activation of macrophages . In this study, Balb/c mice were infected with three Leishmania strains that cause progressively growing cutaneous lesions without obvious dissemination: L . mexicana mexicana giving rise to rapidly growing lesions, and L . (Viannia) panamensis and L . mexicana-like, which both cause slowly developing lesions . The rate of lesion growth was compared to induction of early local and systemic IFN-gamma responses . All the three parasite strains induced increased levels of IFN-gamma transcripts 24 h after infection . Infection with the more aggressive strain resulted in a notably lower IFN-gamma response when compared to infection with the two low pathogenic strains . Interleukin-4 (IL-4) mRNA appeared 7 days after infection with L . (Viannia) panamensis and L . mexicana-like but not with L . mexicana mexicana . Thus, virulence of these Leishmania strains could not be associated with induction of IL-4 during the first week after infection . In addition, none of the Leishmania strains induced detectable mRNA for IL-12 or inducible nitric oxide synthase (iNOS) . These data present a picture somewhat different from that which has been described in L . major experimental infection.

FEMS Microbiol Lett, 1997 Jul 1, 152(1), 101 - 8
The adhesin related 30-kDa protein of Mycoplasma pneumoniae exhibits size and antigen variability; Layh-Schmitt G et al.; Mycoplasma pneumoniae is a pathogenic bacterium colonizing epithelial cells of the human respirator tract . Using an erythrocyte binding assay we isolated a cytadsorption negative mutant designated M7 which has lost 12 of a total of 13 repetitive sequences of a proline rich C-terminal region of the adhesin related 30-kDa protein . The truncated adhesin related protein of 22 kDa showed reduced antigenicity compared to the corresponding wild-type protein . Moreover, the mutant M7 proved incapable of adhering to erythrocytes and to a human colon carcinoma cell line indicating that the repetitive C-terminal region of the 30-kDa protein is essential for effective cytadherence . The adhesin related 30-kDa protein as well as the truncated forms of the corresponding protein were accessible to carboxypeptidase Y which clearly shows surface exposure of the C-terminus of this protein.

J Gen Virol, 1997 Jul, 78 ( Pt 7), 1543 - 9
Secondary structure of the 3'-untranslated region of yellow fever virus: implications for virulence, attenuation and vaccine development; Proutski V et al.; A genetic algorithm-based RNA secondary structure prediction was combined with comparative sequence analysis to construct models of folding for the distal 380 nucleotides of the 3'-untranslated region (3'-UTR) of yellow fever virus (YFV) . A number of structural elements that are thermodynamically stable, conserved in shape, and confirmed by compensatory mutations were revealed . At the same time structural polymorphisms were observed among strains of YFV . These polymorphisms showed an association with virulence: all wild and pathogenic strains were likely to be folded in a significantly different way from vaccine strains with reduced virulence . Structural divergence was also found among vaccine strains, with 17DD, the most virulent in the mouse model, exhibiting an intermediate pattern of folding, combining structural features of both wild and vaccine strains . The observation of a strong association between secondary structure of the 3'-UTR and virulence of YFV may help elucidate the molecular mechanisms of virus attenuation and lead to new strategies of vaccine development directed towards rational modification of secondary structure of the 3'-UTR.

Pediatr Res, 1997 Jul, 42(1), 128 - 36
The administration of complement component C9 enhances the survival of neonatal rats with Escherichia coli sepsis; Lassiter HA et al.; To determine the significance of neonatal C9 deficiency, an animal model was developed in the rat . By rocket immunoelectrophoresis, the concentration of C9 in pooled adult rat serum was 224 +/- 7.2 microg/mL . In contrast, the concentration of C9 in pooled serum from 1-d-old rats was only 43 +/- 3.8 microg/mL and increased during the first 3 wk of life to 170 +/- 20 microg/mL . Similarly, the capacities of neonatal rat serum to kill two pathogenic strains of Escherichia coli and to lyse sensitized sheep erythrocytes were diminished compared with adult serum but increased during the first 3 wk of life . Supplemental human C9 significantly enhanced the bactericidal and hemolytic activity of neonatal rat serum . The capacity of neonatal rats to survive after the intrapulmonary injection of E . coli was positively correlated with the serum C9 concentration, bactericidal activity, and hemolytic activity . In 2-d-old rats infected with E . coli, the intraperitoneal administration of human C9 significantly enhanced survival and also enhanced the protective effect of intraperitoneal human IgG antibodies . The data indicate that C9 deficiency predisposed neonatal rats to invasion by E . coli . The neonatal rat appears to be a suitable model with which to investigate the significance of C9 deficiency.

Int J Clin Pharmacol Ther, 1997 Jun, 35(6), 245 - 9
Use of flurythromycin ethylsuccinate in infections of lower airways due to sensitive germs: multicenter comparative study with clarithromycin; Vagliasindi M; We have conducted a trial according to double-blind, double-dummy conditions, comparing flurythromycin ethylsuccinate with clarithromycin treatments . Sensitive pathogenic bacteria were isolated according to the Kirby Bauer method from sputum cultures of 152 patients affected by acute infections of lower airways (bronchitis, bronchopneumonia, etc.) . The activities of the 2 drugs were investigated on the basis of a main bacteriological evaluation and of several secondary criteria; the 2 treatments were effective and tolerated to the same extent . It can be concluded that in the treatment of infections of lower respiratory airways the use of flurythromycin offers some advantages.

J Clin Microbiol, 1997 Jun, 35(6), 1337 - 43
Rapid identification and fingerprinting of Candida krusei by PCR-based amplification of the species-specific repetitive polymorphic sequence CKRS-1; Carlotti A et al.; A PCR method was developed to identify and fingerprint Candida krusei isolates simply and rapidly . The primer pair Arno1 and Arno2 was designed to amplify the polymorphic species-specific repetitive sequence CKRS-1 (C . krusei repeated sequence 1) that we identified in the nontranscribed intergenic regions (IGRs) of rRNA genes in C . krusei LMCK31 . The specificity, sensitivity, reproducibility, and fingerprinting ability of the PCR assay were evaluated . Amplification products were obtained from all 131 C . krusei isolates studied . No other yeast species of medical importance (n = 26), including species similar to C . krusei, species of pathogenic filamentous fungi, or a variety of pathogenic bacteria, yielded a PCR product with these primers . This PCR assay allowed for the identification of C . krusei in less than 6 h . The PCR assay was sensitive enough to detect as little as 10 to 100 fg of C . krusei-purified DNA and proved to be reproducible . Since amplification products varied both in number and in molecular weight according to the strains, PCR patterns allowed strains to be distinguished . To ascertain the epidemiological usefulness of this PCR fingerprinting, the patterns of the 131 isolates were compared . A total of 95 types which corresponded to 95 independent strains were delineated (discriminatory power = 1 with n = 95) . Comparison of the results of PCR fingerprinting and those of fingerprinting with the CkF1,2 probe showed that they concurred . In addition, this work yields insights into the mechanisms involved in generating polymorphisms in the IGRs of C . krusei . Since this method is simpler and faster than established identification and genotyping methods of this important pathogenic species, it is a critical improvement for clinical microbiology laboratories relevant not only to diagnosis but also to epidemiology.

Science, 1997 May 2, 276(5313), 718 - 25
Exploitation of mammalian host cell functions by bacterial pathogens; Finlay BB et al.; Interest in bacterial pathogenesis has recently increased because of antibiotic resistance, the emergence of new pathogens and the resurgence of old ones, and the lack of effective therapeutics . The molecular and cellular mechanisms of microbial pathogenesis are currently being defined, with precise knowledge of both the common strategies used by multiple pathogenic bacteria and the unique tactics evolved by individual species to help establish infection . What is emerging is a new appreciation of how bacterial pathogens interact with host cells . Many host cell functions, including signal transduction pathways, cytoskeletal rearrangements, and vacuolar trafficking, are exploited, and these are the focus of this review . A bonus of this work is that bacterial virulence factors are providing new tools to study various aspects of mammalian cell functions, in addition to mechanisms of bacterial disease . Together these developments may lead to new therapeutic strategies.

Z Gastroenterol, 1997 May, 35(5), 337 - 46
Immune responses towards intestinal bacteria--current concepts and future perspectives; Duchmann R et al.; The intestinal mucosa constitutes an important barrier as it separates each individual from a large array of antigens within the bowel lumen . These luminal antigens may either be derived from pathogens or may be derived from harmless constituents such as ingested food or the normal intestinal flora . The dichotomy of potentially harmful and potentially harmless antigens encountered by the mucosal immune system poses the important task that, with regard to bacteria-derived antigens, the gut associated immune system is required to mount an efficient host defense against pathogenic bacteria but to maintain at the same time the regulatory control mechanisms which protect the human organism from hyperresponsiveness, and thus chronic inflammation, towards antigens from the normal intestinal flora . In the present review, we discuss variable host and bacterial factors which are likely to determine whether the immune response to pathogenic or normal intestinal bacteria will have beneficial or detrimental consequences for the human organism . Using infections with the prototype enteropathogens V . cholerae and enteropathogenic E . coli (ETEC), Y . enterocolitica induced reactive arthritis (ReA) and in more detail, inflammatory bowel diseases (IBD) as exemplary clinical situations, we review current hypotheses of how bacteria or their products are encountered by cellular components of the specific immune system and how this may relate to disease pathogenesis and the development of new treatment strategies.

Nippon Rinsho, 1997 May, 55(5), 1219 - 24
{Appearance of extended-spectrum beta-lactamases}; Iyobe S; Extended-spectrum beta-lactamases (ESBLs) are enzymes which hydrolyze broad-spectrum beta-lactam antibiotics by expanding the substrate spectra into the so-called anti-beta-lactamase beta-lactams such as oxyimino-cephalosporins, cephamycins, oxacephems, carbapenems and monobactams, conferring resistance to many kinds of beta-lactams on pathogenic bacteria . Recently, ESBLs have been demonstrated from various types of beta-lactamases phylogenetically belonging to the molecular class, A, B, C, or D . The genes coding for ESBLs are chromosome- or plasmid-mediated and some of them have developed by point or insertion mutations in the parental genes coding for the narrow-spectrum beta-lactamase . If the genes are plasmid-mediated, the dissemination among various species of pathogenic bacteria would cause hospital-acquired infections by ESBL-producing bacteria.

Nippon Rinsho, 1997 May, 55(5), 1179 - 84
{Mechanism of acquiring drug-resistance genes in pathogenic bacteria}; Iyobe S; Pathogenic bacteria acquire resistance to chemotherapeutic agents by mutational events in the intrinsic genes or by incorporating foreign resistance genes . The resistance genes to various drugs were transferred among bacteria by transformation with free DNA, phage-mediated transduction, or cell to cell conjugation . Plasmids are capable of self-replication and self-transfer by conjugation . Drug-resistance genes are incorporated into plasmids by transposable elements, transposons . Several kinds of transposons carrying resistance genes to various drugs, or some transposons carrying multiresistance genes, are mobile among genetic elements and confer multiresistance on pathogenic bacteria . There is a specific element, integron, on transposons or plasmids . The integron has the gene and the site for incorporating resistance genes as cassettes and allows expression of the genes.

J Math Biol, 1997 May, 35(5), 503 - 22
The effects of females' susceptibility on the coexistence of multiple pathogen strains of sexually transmitted diseases; Castillo-Chavez C et al.; We study the dynamics of sexually transmitted pathogens in a heterosexually active population, where females are divided into two different groups based on their susceptibility to two distinct pathogenic strains . It is assumed that a host cannot be invaded simultaneously by both disease agents and that when symptoms appear--a function of the pathogen, strain, virulence, and an individual's degree of susceptibility--then individuals are treated and/or recover . Heterogeneity in susceptibility to the acquisition of infection and/or in variability in the length of the infection period of the female subpopulations is incorporated . Pathogens' coexistence is highly unlikely on homogeneously mixing female and male populations with no heterogeneity among individuals of either gender . Variability in susceptibility in the female subpopulation makes coexistence possible albeit under a complex set of circumstances that must include differences in contact/mixing rates between the groups of females and the male population as well as differences in the lengths of their average periods of infectiousness for the three groups.

Microb Pathog, 1997 Apr, 22(4), 247 - 52
Mutations in the f165(1)A and f165(1)E fimbrial genes and regulation of their expression in an Escherichia coli strain causing septicemia in pigs; Daigle F et al.; Transposon (TnphoA) mutagenesis was used to study the expression of F165(1) fimbriae, related to Prs fimbriae, in the pathogenic Escherichia coli strain 5131 (O115:K "V165":F165) . This strain causes septicemia in swine and also expresses F165(2) fimbriae, related to F1C . Adhesin-defective mutants from the wild-type pathogenic strain were produced and TnphoA insertions were localized either in the f165(1)A gene, which encodes the major fimbrial subunit or in the f165(1)E, gene, which encodes a minor fimbrial subunit . TnphoA gene fusions were used to measure expression of F165(1) fimbrial genes . Similar pattern of regulation of expression was observed in both f165(1)A and f165(1)E genes . Optimal expression of F165(1) fimbriae was obtained on solid minimal medium . Production of F165(1) fimbriae was negatively regulated by addition of glucose, leucine or alanine to the media, by growth at 18 degrees C, and by pH above or below 7.0.

J Zoo Wildl Med, 1997 Mar, 28(1), 80 - 8
Amikacin pharmacokinetics and the effects of ambient temperature on the dosage regimen in ball pythons (Python regius); Johnson JH et al.; The serum concentration of amikacin following intracardiac and i.m . administration of amikacin (3.48 mg/kg) in 12 ball pythons (Python regius) housed at 25 degrees C and 37 degrees C was studied . Blood samples were collected by cardiocentesis at intervals up to 144 hr after administration of amikacin . Drug concentration-versus-time curves following intracardiac administration at both temperatures best fit a two-compartment open model . For snakes housed at 37 degrees C, the extrapolated time 0 concentration (mean +/- SD) was 17.64 +/- 3.5 micrograms/ml with a median elimination half-life of 4.5 days . The maximum concentrations were 11.98 +/- 1.67 micrograms/ml and 13.87 +/- 2.61 micrograms/ml for snakes housed at 25 degrees C and 37 degrees C respectively . There were no significant pharmacokinetic differences among the snakes housed at 25 degrees C and 37 degrees C . Model-independent parameters were area under the curve, 69,900 +/- 0.011 micrograms.min/ml, apparent volume of distribution at steady state, 410 +/- 106 ml/kg, clearance, 0.036 +/- 0.009 ml/min/kg, and mean residence time, 3,530 +/- 273.7 minutes . Mean serum amikacin concentrations did not reach the recommended therapeutic peak concentrations for mammals (25 micrograms/ml) . In addition, the amikacin serum concentration did not fall below the recommended therapeutic trough concentrations (2 micrograms/ml) by 6 days . The serum amikacin concentrations were efficacious based on the area under the curve . Therefore, amikacin (3.48 mg/kg) administered i.m . to ball pythons should produce maximum serum concentrations against most pathogenic bacteria . In this study, it would have taken another half-life, or 4.5 days, before trough concentrations of 2 micrograms/ml were achieved . To prevent accumulation, a one-time administration of amikacin may be appropriate.

FEMS Microbiol Lett, 1997 Mar 1, 148(1), 27 - 34
Oligonucleotides specific for pathogenic and saprophytic leptospira occurring in water; Murgia R et al.; Sets of primers specific for both pathogenic (SPL) and saprophytic (SSL) Leptospira were designed from ribosomal 16S genes (rrs) available in databases . They were used as two sets of primer pairs for the PCR amplification of known pathogenic and saprophytic strains . It was possible to identify pathogenic strains by the use of SPL primers and saprophytic ones by SSL primers . Serovars from L . meyeri, of controversial pathogenicity status, confirmed the heterogeneity of the species representatives in this respect . Serovars ranarum, sofia and perameles were amplified by SPL and not SSL . Conversely, serovar semaranga was amplified by SSL and not SPL . In order to use SPL primers for the detection of pathogenic leptospires from a natural water environment, we set up an additional semi-nested PCR by employing a second internal primer which succeeded in detecting as few as 5 pathogenic leptospires per ml of water.

J Biol Chem, 1997 Feb 28, 272(9), 5533 - 8
Quantitative analysis of bacterial toxin affinity and specificity for glycolipid receptors by surface plasmon resonance; MacKenzie CR et al.; The primary virulence factors of many pathogenic bacteria are secreted protein toxins which bind to glycolipid receptors on host cell surfaces . The binding specificities of three such toxins for different glycolipids, mainly from the ganglioside series, were determined by surface plasmon resonance (SPR) using a liposome capture method . Unlike microtiter plate and thin layer chromatography overlay assays, the SPR/liposome methodology allows for real time analysis of toxin binding under conditions that mimic the natural cell surface venue of these interactions and without any requirement for labeling of toxin or receptor . Compared to conventional assays, the liposome technique showed more restricted oligosaccharide specificities for toxin binding . Cholera toxin demonstrated an absolute requirement for terminal galactose and internal sialic acid residues (as in GM1) with tolerance for substitution with a second internal sialic acid (as in GD1b) . Escherichia coli heat-labile enterotoxin bound to GM1 and tolerated removal or extension of the internal sialic acid residue (as in asialo-GM1 and GD1b, respectively) but not substitution of the terminal galactose of GM1 . Tetanus toxin showed a requirement for two internal sialic acid residues as in GD1b . Extension of terminal galactose with a single sialic acid was tolerated to some extent . The SPR analyses also yielded rate and affinity constants which are not attainable by conventional assays . Complex binding profiles were observed in that the association and dissociation rate constants varied with toxin:receptor ratios . The sub-nanomolar affinities of cholera toxin and heat-labile enterotoxin for liposome-anchored gangliosides were attributable largely to very slow dissociation rate constants . The SPR/liposome technology should have general applicability in the study of glycolipid-protein interactions and in the evaluation of reagents designed to interfere with these interactions.

Infect Immun, 1997 Feb, 65(2), 798 - 800
Protection against infection in mice vaccinated with a Brucella abortus mutant; Boschiroli ML et al.; This study determines whether a genetically engineered mutant of Brucella abortus, strain M-1, possesses differences in protective properties compared to the parental strain, vaccine S19 . M-1 is a mutant unable to express BP26, a periplasmic protein with potential use in diagnosis . Mice vaccinated with S19 developed antibodies against BP26, while those vaccinated with M-1 did not . However, mice vaccinated with S19 or M-1 were similarly protected against challenge with pathogenic strain 2308, suggesting that the lack of BP26 does not affect the induction of the protective immune response exerted by S19 . These and previous results showing that bacterial invasion and growth or replication in mouse spleens were indistinguishable between strains M-1 and S19 could indicate that the mutant is an attenuated strain which maintains the same protective properties as S19.

Infect Immun, 1997 Feb, 65(2), 514 - 8
Identification, characterization, and immunogenicity of the lactoferrin-binding protein from Helicobacter pylori; Dhaenens L et al.; Iron acquisition plays an important role in bacterial virulence . Different studies have been initiated to define the mechanism by which Helicobacter pylori acquires iron . We had previously demonstrated that human lactoferrin (HLf) supported full growth of the bacteria in media lacking other iron sources . The ability of H . pylori to use HLf as an iron source had been found to be dependent on cell-to-protein contact . Since lactoferrin has been found in significant amounts in human stomach resection specimens from patients with superficial or atrophic gastritis, the iron uptake of H . pylori via a specific HLf receptor may play a major role in the virulence of H . pylori infection . In this study, by using affinity chromatography with biotinylated HLf and streptavidin-agarose, we identified a 70-kDa lactoferrin-binding protein (Lbp) from outer membrane proteins of H . pylori . This Lbp was only present when H . pylori was grown in an iron-starved medium, suggesting that it serves in iron uptake . Direct binding assays with increasing concentrations of biotinylated HLf demonstrated that the lactoferrin interaction with the outer membrane of H . pylori grown in iron-restricted medium was saturable . Competitive binding experiments with bovine and human lactoferrin and with transferrin of horse, bovine, and human origin indicated that this Lbp appeared highly specific for HLf . A number of other studies have focused on the importance of transferrin and lactoferrin receptors in pathogenic bacteria and their specificity with the host species . This observation might explain the very strict human specificity of H . pylori.

Acta Otolaryngol Suppl, 1997, 529, 153 - 7
Radiological findings in the maxillary sinuses of symptomless young men; Savolainen S et al.; The maxillary sinuses were examined radiologically by occipitomental projection (Waters' view) in 404 conscripts without any symptoms of sinusitis . Abnormalities were found in 188 (23.3%) of all 808 sinuses, the most common being mucosal thickening of > 6 mm (12.3% of the sinuses), cysts or polyps (7.2%), and completely opacified sinus (3.3%) . Normal x-ray findings were more common in the conscripts examined during the summer months and mucosal thickening was more frequently encountered in winter than in summer . Nasal bacteria were studied in 100 cases . Findings of normal bacterial flora and of pathogenic bacteria were equally frequent among subjects with normal sinus x-ray (score 0 and 1) and subjects with severe abnormalities (scores 3-6), but mucosal cysts (score 2) was more often combined with pathogens in the nose . Mucosal thickening was more often observed in non-allergic than in allergic persons; thus allergy did not seem to increase radiological abnormalities . Of young men engaged in outdoor activities, about one fifth seem to have significant chronic mucous membrane abnormalities in the maxillary antra without clinical symptoms . In 1-2% of cases secretion is detected in the maxillary sinus indicating a subclinical sinusitis.

Parasitol Res, 1997, 83(4), 345 - 8
Identification of two genetic markers that distinguish pathogenic and nonpathogenic strains of Acanthamoeba spp; Howe DK et al.; Species-level identification of Acanthamoeba isolates is difficult and gives little or no indication of the isolate's pathogenicity . We identified two amplification-based genetic markers that were highly correlated with pathogenicity in Acanthamoeba spp . One marker, designed to amplify a 485-bp fragment of the small-subunit ribosomal RNA gene (ssrDNA), was preferentially amplified from the nonpathogenic strains; amplifications from the pathogenic strains yielded anomalous fragments of 650 and 900 bp . A second marker was developed on the basis of the anomalous 650-bp fragment . Primers to this sequence preferentially amplified a noncoding locus (called Ac6) only from the pathogenic strains . These two genetic markers may be useful for identification of pathogenic Acanthamoeba spp . strains.

Arch Virol, 1997, 142(2), 255 - 70
Modified activity of a VP2-located neutralizing epitope on various vaccine, pathogenic and hypervirulent strains of infectious bursal disease virus; Eterradossi N et al.; Nine monoclonal antibodies (Mabs) to a vaccine strain of infectious bursal disease virus (IBDV) of intermediate virulence were characterized in Western-blot, radioimmunoprecipitation, ELISA additivity, and neutralization assays . At least two distinct serotype 1-specific conformation-dependent overlapping neutralizing antigenic domains were shown to be present on IBDV-VP2, and were respectively probed by Mabs 3 and 4, and by Mabs 6 and 7 . Ten serotype 1 vaccine or pathogenic IBDV strains were tested for neutralization . Most mild or intermediate vaccine strains were efficiently neutralized by all Mabs, whereas US variant A, European pathogenic strain Faragher 52/70 and French hypervirulent isolate 89163 were not neutralized by Mabs 3 and 4 . In addition, these two Mabs were shown to bind to the Faragher 52/70 strain, but not to the 89163 isolate, in an antigen-capture ELISA . These results suggest that a neutralizing epitope is possibly modified in European pathogenic IBDV strains, and that Mabs 3 and 4 may prove useful for antigenic differentiation between European classical and hypervirulent isolates.

J Virol Methods, 1997 Jan, 63(1-2), 27 - 35
Molecular characteristics of Junin virus; Bushar G et al.; Results suggest that protein, glycerophospolipid, galactoside, and sialyl glycoside residues are present in Junin virus (JV), are accessible to enzymatic digestion, and play an important role in infection . Four major protein bands with molecular masses (Mr) 64 +/- 2, 56 +/- 2, 52 +/- 3 (mean +/- standard deviation, n = 4) and approximately 12-18 kDa were consistently detected after denaturing gel electrophoresis analysis of purified attenuated JV . The 52 kDa protein showed a diffuse tail in the 52-56 kDa range and was considered to be the JV glycoprotein . By Western blotting, the 64 kDa protein bound a JV neutralizing antibody and was considered to be the viral nucleoprotein . Additional bands corresponding to larger proteins (approximately 200, 96, 86, and 78 80 kDa in size), as well as fainter and broader bands in the 23-44 kDa region were also present in purified JV preparations . The relative resistance of virus infectivity to RNase digestion demonstrates that the genome of JV is protected from enzymatic attack . Analysis of purified JV virions by electrophoresis resolved the viral small (S) RNA and large (L) RNA species, 3636 +/- 54 bases and 7667 +/- 154 bases long, respectively (average length +/- range, in four determinations) . The (S) RNA of attenuated JV appeared slightly larger than that reported for a pathogenic strain, ruling out a large sequence deletion as a reason for attenuation.

Semin Gastrointest Dis, 1997 Jan, 8(1), 2 - 11
The immunobiology of Helicobacter pylori gastritis; Genta RM; Helicobacter pylori is the major causative agent of chronic gastritis . It is associated with duodenal and gastric ulcer and with the majority of primary gastric B-cell lymphomas; furthermore, there is a strong epidemiological association with gastric cancer . One intriguing aspect of this infection is the ability of H pylori to persist despite the vast array of host immune responses . This article reviews what is known about the immune responses against H pylori, emphasizing what is generally accepted and applicable while highlighting areas of controversy . The first section delineates the genesis of the inflammatory responses, which initiate with the production of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1, IL-6, and IL-8 and continue with the recruitment of neutrophilic polymorphonuclear cells, lymphocytes, plasma cells, macrophages and eosinophils, and later with the development and recruitment of specifically committed cells (lymphocytes sensitized to H pylori antigens and B cells producing immunoglobulin (Ig)A, IgG, and possibly IgE antibodies against a variety of H pylori surface and flagellar proteins as well as bacterial toxins) . The second part of the article focuses on the development of lymphoid follicles in the gastric mucosa, a phenomenon that for the first time links an immune response (the recruitment of mucosa-associated lymphoid tissue {MALT} to the gastric mucosa in response to H pylori infection) with the development of a neoplastic growth (the development of gastric MALT lymphomas) . The local and systemic antibody responses are discussed in the light of their potential application in the development of diagnostic tests and vaccines . Particular emphasis is placed on the controversies surrounding the significance of antibodies directed against a 120 to 140 kDa protein apparently associated with more "aggressive" (sometimes also called "ulcerogenic" or "pathogenic") strains of H pylori.

Appl Environ Microbiol, 1997 Jan, 63(1), 115 - 21
Obligate intracellular bacterial parasites of acanthamoebae related to Chlamydia spp; Amann R et al.; The phylogeny of obligate intracellular coccoid parasites of acanthamoebae isolated from the nasal mucosa of humans was analyzed by the rRNA approach . The primary structures of the 16S and 23S rRNA molecules of one strain were determined in almost full length . In situ hybridization with a horseradish peroxidase-labeled oligonucleotide probe targeted to a unique signature site undoubtedly correlated the retrieved 16S rRNA sequence to the respective intracellular parasite . This probe also hybridized with the second strain, suggesting a close relationship between the two intracellular parasites . Comparative sequence analysis demonstrated a distinct relationship to the genus Chlamydia . With 16S rRNA similarities of 86 to 87% to the hitherto-sequenced Chlamydia species, the intracellular parasites are likely not new species of this genus but representatives of another genus in the family of the Chlamydiaceae . Consequently, it is proposed to provisionally classify the endoparasite of Acanthamoeba sp . strain Bn9 as "Candidatus Parachlamydia acanthamoebae." From an epidemiological perspective, the results suggest that small amoebae could be environmental reservoirs and vectors for a variety of potentially pathogenic bacteria including members of the Chlamydiaceae.

Infect Immun, 1997 Jan, 65(1), 133 - 43
An iron- and fur-repressed Legionella pneumophila gene that promotes intracellular infection and encodes a protein with similarity to the Escherichia coli aerobactin synthetases; Hickey EK et al.; Legionella pneumophila, a parasite of alveolar macrophages, requires iron for intra- and extracellular growth . Although its mechanisms for iron assimilation are poorly understood, this bacterium produces Fur, a protein that can repress gene transcription in response to iron concentration . Because iron- and Fur-regulated genes are important for infection in other bacteria, the identification of similar genes in L . pneumophila was undertaken . A wild-type strain of L . pneumophila was randomly mutated with a mini-Tn10' lacZ transposon, and the resulting gene fusions were tested for iron regulation by assessing beta-galactosidase production in the presence and absence of iron chelators . Of the initial six mutants with iron-repressed lacZ fusions, two strains, NU229 and NU232, possessed fusions that were stably iron regulated . To assay for Fur regulation, the levels of beta-galactosidase were measured in strains no longer producing Fur . As in a number of pathogenic bacteria, L . pneumophila fur could not be insertionally inactivated, but spontaneous Fur- derivatives were generated by selecting for manganese resistance . Strain NU229 contained a Fur-repressed fusion based on derepression of lacZ expression in its manganese-resistant derivative . Extracellular growth of NU229 in bacteriological media was similar to that of wild-type strain 130b . To assess the role of an iron- and Fur-regulated (frgA) gene in intracellular infection, the ability of NU229 to grow within U937 cell monolayers was tested . Quantitative infection assays demonstrated that intracellular growth of NU229 was impaired as much as 80-fold . Reconstruction of the mutant by allelic exchange proved that the infectivity defect in NU229 was due to the inactivation of frgA and not to a second-site mutation . Subsequently, complementation of the interrupted gene by an intact plasmid-encoded gene demonstrated that the infectivity defect was due to the loss of frgA and not to a polar effect . Nucleotide sequence analysis revealed that the 63-kDa FrgA protein has homology with the aerobactin synthetases IucA and IucC of Escherichia coli, raising the possibility that L . pneumophila encodes a siderophore which is required for optimal intracellular replication . Southern hybridization analysis determined that frgA is specific to L . pneumophila.

Schweiz Med Wochenschr, 1996 Dec 28, 126(51-52), 2223 - 33
{Acute otitis media with effusion: an overview of the pathogenesis and recommendations for therapy}; Linder T et al.; Otitis media is one of the most common diseases in infants and young children . A combination of important factors contributes to the pathogenesis of acute otitis media and otitis media with effusion . These are poor tubal function, the degree of mastoid pneumatization, nasopharyngeal colonization with pathogenic bacteria and viruses, the ascending infectious pathway along the Eustachian tube, the immune status of the host, allergic and environmental factors, and genetic predisposition . Only correct diagnosis and understanding of they underlying pathophysiology enables the clinician to target treatment of the various forms of otitis media . We review the current concepts regarding evaluation and management of the diseased child and focus on the indication and selection of antibiotic therapy, bearing in mind the resistance rate within Switzerland . Most patients can be treated medically . "Otitis prone" individuals and children suffering from chronic otitis media with effusion with documented hearing loss clearly benefit from surgical intervention . We analyze the different treatment modalities and present a step-wise treatment algorithm . Newer vaccination trials indicate immunogenic effects even in young infants and show promising results in experimental and clinical studies.

Tidsskr Nor Laegeforen, 1996 Dec 10, 116(30), 3630 - 2
{The isolation hospital on Katten in Bergen}; Oeding P; In 1864 the Board of Health in Bergen, Norway, feared that an epidemic of smallpox might break out in the city . A house on the bastion Katten (Norwegian for "the cat") on the Fredriksberg fortress was adapted and made a provisional smallpox hospital . Later on it also served as a cholera hospital during a minor cholera epidemic in 1873, and as an isolation hospital for patients suffering from scarlet fever . The hospital housed only five to seven patients and two nurses . The doctor and hospital orderlies were isolated in an adjacent house . The Board of Health presented several plans for enlarging the hospital . Only in 1891 was the hospital on Katten replaced by a new and larger isolation hospital in another part of the city (Sandviken) . At first, the Board of Health introduced rigid isolation regulations which were difficult to satisfy . When the pathogenic bacteria were discovered and the spread of infection was better understood, the view on isolation and other measures became more rational.

Kansenshogaku Zasshi, 1996 Dec, 70(12), 1220 - 6
{Detection and genotyping of astroviruses by RT-PCR and sequencing}; Yue HJ et al.; Three primer pairs, AV244Mon and 82b, AV-15Gr and AV-12Gr, and Beg and End, were used for the detection of standard astroviruses (serotype 1 to serotype 7) in cell culture and astroviruses isolated from 89 diarrheal stool specimens negative for pathogenic bacteria, rotavirus and adenovirus by the reverse transcription-polymerase chain reaction (RT-PCR) . All the standard strains and two isolates were detected by primer pairs AV244Mon and 82b, and AV-15Gr and AV-12Gr . All serotypes except serotype 4 were detected by the primer pair Beg and End . The molecular sizes of the RT-PCR products obtained by Beg and End were almost the same among the different serotypes except serotype 6 . Sequence analyses of the nucleic acid in the regions between the primer pairs AV244Mon and 82b, and between Beg and End from PCR products of the standard strains and from the isolates of the two stool specimens revealed that each serotype had a unique sequence . These results indicate that the RT-PCR is useful for detecting and genotyping astroviruses.

J Parasitol, 1996 Dec, 82(6), 893 - 9
Acid phosphatase in the pathogenic and nonpathogenic hemoflagellates, Cryptobia spp., of fishes; Zuo X et al.; Acid phosphatase (ACP) was detected in whole-cell lysates, membrane-bound and water-soluble fractions of Cryptobia salmositica (pathogenic and nonpathogenic vaccine strains), Cryptobia bullocki, and Cryptobia catostomi using p-nitro-phenylphosphate as the substrate . High activities were in acidic pH (3.0-5.5) and the optimal pH was 5.0 Highest ACP activity was in the membrane-bound fraction . The pathogenic strain of C . salmositica had significantly higher total ACP activity than the vaccine strain and the other 2 species . However, the activity in the pathogenic C . salmositica decreased significantly with prolonged in vitro cultivation . The membrane-bound ACP of the pathogenic C . salmositica had highest resistance to the ACP inhibitor, sodium tartrate.

J Hosp Infect, 1996 Dec, 34(4), 291 - 9
Preoperative bacterial colonization and its influence on postoperative wound infections in plastic surgery; Andenaes K et al.; During two separate periods a total of 654 patients were included in a clinical study relating preoperative bacterial colonization to occurrence of postoperative wound infection in plastic surgery . During the second period one half of the patients were randomized to receive prophylactic azithromycin . Bacteriological samples were collected from the nasal vestibulum during both periods, and additionally from the surgical field during the second period . All patients had preoperative chlorhexidine bathing . The bacteriological findings were categorized as either normal flora or potentially pathogenic bacteria, and as either having no growth . Surgical wounds were divided into four contamination classes . Postoperative follow-up was 30 days, and assessment of wound infection was based on a graded scale . We did not find any statistically significant relation between preoperative bacterial colonization and postoperative wound infection, regardless of place of sample collection, method of bacterial classification, class of contamination or use of prophylactic azithromycin.

J Med Microbiol, 1996 Dec, 45(6), 433 - 9
Binding of human plasminogen and lactoferrin by Helicobacter pylori coccoid forms; Khin MM et al.; The interactions between Helicobacter pylori spiral and coccoid forms, extracellular matrix (ECM) and plasma proteins were studied in an 125I-labelled protein assay . The range of binding of collagen V, plasminogen, human lactoferrin (HLf) and vitronectin to coccoid forms of H . pylori NCTC 11637 was 26-48% . In contrast, binding of radiolabelled fibronectin and collagen types I and III was low (3-8%) . The coccoid forms of 14 strains of H . pylori showed significant HLf binding (median 26%) . With plasminogen, no significant difference was found between binding to the coccoid (median = 13%) and spiral (median = 12%) forms, of 13 of the 14 strains of H . pylori tested; the exception was strain NCTC 11637 . 125I-plasminogen showed a dose-dependent binding to both the coccoid and spiral forms . Plasminogen binding to both forms was specific; the binding was inhibited by non-labelled plasminogen, plasmin, lysine, EACA (epsilon-aminocaproic acid) but not by fetuin or various carbohydrates . Similarly, HLf binding was found to be specific and was inhibited by non-labelled HLf and BLf . The coccoid forms showed either similar or enhanced ECM binding capabilities compared with the spiral forms . As the binding of ECM proteins may be an important mechanism of tissue adhesion for various pathogenic bacteria, the coccoid differentiated form of H . pylori can be considered as an infective form in the pathogenesis of helicobacter infection and type B gastritis.

J Clin Microbiol, 1996 Dec, 34(12), 3101 - 7
O serogroups, biotypes, and eae genes in Escherichia coli strains isolated from diarrheic and healthy rabbits; Blanco JE et al.; A total of 305 Escherichia coli strains isolated from diarrheic and healthy rabbits in 10 industrial fattening farms from different areas of Spain were serotyped, biotyped, and tested for the presence of the eae gene and toxin production . The characteristics found in strains isolated from healthy rabbits were generally different from those observed in E . coli strains associated with disease . Thus, strains with the eae gene (74% versus 22%); strains belonging to serogroups O26, O49, O92, O103, and O128 (64% versus 12%); rhamnose-negative strains (51% versus 5%); and rhamnose-negative O103 strains with eae genes present (41% versus 1%) were significantly (P < 0.001 in all cases) more frequently detected in isolates from diarrheic animals than in those from healthy rabbits . Whereas a total of 35 serogroups and 17 biotypes were distinguished, the majority of the strains obtained from diarrheic rabbits belonged to only four serobiotypes, which in order of frequency were O103:B14 (72 strains), O103:B6 (16 strains), O26:B13 (12 strains), and O128:B30 (12 strains) . These four serobiotypes accounted for 48% (112 of 231) and 5% (4 of 74) of the E . coli strains isolated from diarrheic and healthy rabbits, respectively . Only six strains were toxigenic (three CNF1+, two CNF2+, and one VT1+) . We conclude that enteropathogenic E . coli strains that possess the eae gene are a common cause of diarrhea in Spanish rabbit farms and that the rhamnose-negative highly pathogenic strains of serotype O103:K-:H2 and biotype B14 are especially predominant . Detection of the eae gene is a useful method for the identification of enteropathogenic E . coli strains from rabbits . However, a combination of serogrouping and biotyping may be sufficient to accurately identify the highly pathogenic strains for rabbits.

J Clin Microbiol, 1996 Dec, 34(12), 2980 - 4
Shiga toxin-producing Escherichia coli strains from bovines: association of adhesion with carriage of eae and other genes; Wieler LH et al.; Out of 174 bovine Shiga toxin-producing Escherichia coli (STEC) strains isolated from diarrheic calves in Germany and Belgium, 122 strains (70.1%) were selected because of their reactivity with the eae (E . coli attaching and effacing gene) probe ECW1-ECW2 . One hundred seven of these eae-positive strains (87.7%) harbored stx1 genes, 13 strains (10.7%) had stx2 genes, and 2 strains (1.6%) had both stx genes . The strains displayed 17 different O types, the majority (97 strains) {79.5%}) belonging to O5 (5 strains), O26 (21 strains), O111 (13 strains) O118 (36 strains), O145 (9 strains), and O157 (13 strains) . In the HEp-2 cell adhesion assay, 99 strains (81.1%) showed a localized adhesion, and 80 strains (65.6%) stimulated actin accumulation, as determined in the fluorescence actin staining test . None of the strains harbored genes coding for bundle-forming pili (bfpA), clearly differentiating them from enteropathogenic . E . cole . espB gene sequences were only detectable in 23 (18.9%) of the eae-positive bovine STEC strains . Three different PCRs were established, differentiating between eae sequences of enteropathogenic E . coli strain E2348/69 (O127:H6) and STEC strain EDL933 (O157: H7) . Primers matching in the more heterologous downstream eae sequences gave amplicons in only 8 of the 17 O types (O84:H-, O103:H2, O111:H-, O111:H2, O119:H25, O128:H-, O145:H28, and O157:H-) . Only 15 STEC strains, belonging to serotypes O111H:-, O111H:2, O145:H28, and O157:H-, gave amplicons in all three eae-specific PCRs . These data demonstrate that bovine STEC strains are a heterogeneous group of pathogenic bacteria, a lot of which share virulence markers with STEC strains causing infections in humans . However, in contrast to human STEC strains, bovine eae-positive STEC strains are mainly restricted to the stx1 genotype . The observation that espB sequences are not highly conserved might have consequences for the serological recognition of the ESPB protein in patients . Like in human STEC strains, eae-related sequences are closely associated with certain E . coli O groups; however, they are not serotype specific.

Vet Parasitol, 1996 Nov 15, 66(3-4), 251 - 5
Prophylactic treatment of experimental canine babesiosis (Babesia canis) with doxycycline; Vercammen F et al.; Doxycycline provided satisfactory prophylaxis against experimental infection with a highly pathogenic strain of Babesia canis . Rectal temperature, parasitaemia, packed cell volume and serology were monitored for evaluation of the prophylactic effect . Although a daily dose of 5 mg kg-1 of doxycycline did not completely prevent clinical disease, symptoms remained moderate and a full recovery was obtained within 1 week . At a dose of 20 mg kg-1 day-1 no clinical symptoms were observed, but asymptomatic infection could not be ruled out.

Proc Natl Acad Sci U S A, 1996 Nov 12, 93(23), 12890 - 5
Development of pilus organelle subassemblies in vitro depends on chaperone uncapping of a beta zipper; Bullitt E et al.; The major subassemblies of virulence-associated P pili, the pilus rod (comprised of PapA) and tip fibrillum (comprised of PapE), were reconstituted from purified chaperone-subunit complexes in vitro . Subunits are held in assembly-competent conformations in chaperone-subunit complexes prior to their assembly into mature pili . The PapD chaperone binds, in part, to a conserved motif present at the C terminus of the subunits via a beta zippering interaction . Amino acid residues in this conserved motif were also found to be essential for subunit-subunit interactions necessary for the formation of pili, thus revealing a molecular mechanism whereby the PapD chaperone may prevent premature subunit-subunit interactions in the periplasm . Uncapping of the chaperone-protected C terminus of PapA and PapE was mimicked in vitro by freeze-thaw techniques and resulted in the formation of pilus rods and tip fibrillae, respectively . A mutation in the leading edge of the beta zipper of PapA produces pilus rods with an altered helical symmetry and azimuthal disorder . This change in the number of subunits per turn of the helix most likely reflects involvement of the leading edge of the beta zipper in forming a right-handed helical cylinder . Organelle development is a fundamental process in all living cells, and these studies shed new light on how immunoglobulin-like chaperones govern the formation of virulence-associated organelles in pathogenic bacteria.

Dev Comp Immunol, 1996 Nov-Dec, 20(6), 365 - 81
Immunogenetics of disease resistance in fish: a comparative approach; Wiegertjes GF et al.; The study of the genetic regulation of infectious disease resistance depends on the availability of inbred lines or selection lines of the species under investigation . The small numbers of such lines of fish has limited the strategy in teleosts to studies of associations between disease and immune/health traits . Attempts to correlate genetic differences in immune responsiveness with survival after experimental challenge with pathogenic bacteria have failed to define immune parameters that can substantially aid selection for genetic resistance to infectious diseases . Advantages and disadvantages of selection strategies as illustrated by mouse and chicken models are discussed . In this study we summarize the present situation in fish as well as our attempts to develop gynogenetic lines of carp for immunogenetic research.

Acta Histochem, 1996 Nov, 98(4), 399 - 409
Localization of G-proteins in macrophages and E . coli during phagocytosis; Didenko LW et al.; Heterotrimeric GTP-binding proteins (G-proteins) have been shown to play an important role in cellular signalling . However, G-protein involvement in the intracellular spreading of bacterial pathogens is still poorly understood . In this study, antibodies, that recognize G-protein alpha-subunits (anti-G alpha), were used to investigate the localization of G-proteins in the macrophage-like cell line P388D1 and E . coli, also in their L-forms, during phagocytosis . In E . coli, anti-G alpha-binding sites were detected preferably in the cell wall and septa of the whole bacterial forms as well as in the cytoplasm of L-forms . Western blotting of bacterial lysates demonstrated protein bands with positive immunoreaction to antibodies against Gs alpha, Gi alpha, and Gcommon alpha with a higher affinity to the antibody against Gs alpha . Immunoreaction with the anti-Gs alpha-antibody was markedly higher in pathogenic strains of E . coli . Because of the conserved structure in all GTP-binding proteins which seem to derive from a single primordial protein involved in signal transduction mechanisms, it is reasonable to assume that some anti-Ga-positive proteins in E . coli might be related to G-proteins of higher organisms . A putative candidate for bacterial G-proteins seems to be a 36 kDa protein . Enhancement in G-protein immunostaining in the cytoplasm of macrophages around the internalized bacteria testifies to the involvement of G-proteins in mediation of endocytosis responses of phagocytes.

J Bacteriol, 1996 Nov, 178(22), 6435 - 42
Molecular cloning and characterization of nlpH, encoding a novel, surface-exposed, polymorphic, plasmid-encoded 33-kilodalton lipoprotein of Borrelia afzelii; Theisen M; Borrelia burgdorferi sensu lato organisms, comprising B . burgdorferi sensu stricto, Borrelia afzelii, and Borrelia garinii, are tick-borne pathogens causing Lyme borreliosis in humans . To identify putative virulence determinants, a B . afzelii DNA library was screened for Congo red dye binding, a property associated with virulence in pathogenic bacteria . One clone was found to carry a 663-nucleotide-long open reading frame encoding a Congo red dye-binding protein with a calculated molecular mass of 25,660 Da . The amino acid sequence deduced from its nucleotide sequence was found to include a consensus bacterial lipidation site present at residues 15 to 18 (Leu-Ser-Gly-Cys) . The lipoprotein nature was demonstrated by incorporation of radioactive palmitate; hence, this protein has been termed NlpH, for new lipoprotein H . NlpH is located on the surface of B . afzelii, and the nlpH gene is found on a circular plasmid . The nlpH gene is also found in B . burgdorferi sensu stricto and B . garinii . Immediately upstream of nlpH is located a smaller reading frame encoding a polypeptide containing the casein kinase II phosphorylation recognition sequence, (Ser/Thr)-X-Y-(Glu/Asp), repeated 10 times.

J Med Microbiol, 1996 Nov, 45(5), 344 - 8
Occurrence of plasmids in pathogenic strains of Nocardia; Provost F et al.; The purpose of the present study was to determine the relative distribution of plasmids in 87 clinical isolates of Nocardia, belonging to the five major pathogenic species . A correlation between plasmid content and the site of infection within the host, resistance to antibiotics and enzymic profiles was also investigated . The plasmid extraction procedure of Kado and Liu was used . Electrophoretic analysis revealed one-to-four plasmid bands, ranging in size from <8 to >50 kb, in 27 strains (31%) . Based on the number of isolates tested, the incidence of plasmid-bearing strains was significantly higher among N . farcinica than N . asteroides strains . Within N . farcinica, the incidence of plasmids was higher among strains isolated in the Paris area than in strains isolated elsewhere, such as in the French provinces or outside France . A statistically significant correlation was demonstrated between the cutaneous localisation of infections and the incidence of plasmid-bearing strains . The presence of plasmids in nocardiae could not be associated with specific phenotypic traits such as resistance to antibiotics or enzymic activity . The fact that the majority of Nocardia clinical isolates (60 of 87) did not contain plasmids suggests that plasmids are not involved directly in virulence and that there is no selective pressure for plasmid acquisition.

Biophys J, 1996 Oct, 71(4), 1869 - 76
Reversible adsorption and nonreversible insertion of Escherichia coli alpha-hemolysin into lipid bilayers; Bakas L et al.; Alpha-Hemolysin is an extracellular protein toxin (107 kDa) produced by some pathogenic strains of Escherichia coli . Although stable in aqueous medium, it can bind to lipid bilayers and produce membrane disruption in model and cell membranes . Previous studies had shown that toxin binding to the bilayer did not always lead to membrane lysis . In this paper, we find that alpha-hemolysin may bind the membranes in at least two ways, a reversible adsorption and an irreversible insertion . Reversibility is detected by the ability of liposome-bound toxin to induce hemolysis of added horse erythrocytes; insertion is accompanied by an increase in the protein intrinsic fluorescence . Toxin insertion does not necessarily lead to membrane lysis . Studies of alpha-hemolysin insertion into bilayers formed from a variety of single phospholipids, or binary mixtures of phospholipids, or of phospholipid and cholesterol, reveal that irreversible insertion is favored by fluid over gel states, by low over high cholesterol concentrations, by disordered liquid phases over gel or ordered liquid phases, and by gel over ordered liquid phases . These results are relevant to the mechanism of action of alpha-hemolysin and provide new insights into the membrane insertion of large proteins.

Commun Dis Rep CDR Rev, 1996 Sep 13, 6(10), R136 - 9
An outbreak of viral gastroenteritis following a wedding reception; Hicks NJ et al.; Thirty-five people developed gastrointestinal symptoms after a wedding reception attended by 147 guests and served by eight catering staff . A retrospective cohort study showed that illness was associated independently with consumption of a pasta dish and spring rolls . The descriptive epidemiology, obtained from interviews with the guests about foods they had eaten and the onset and duration of symptoms, suggested that the outbreak was likely to have been caused by a small round structured virus (SRSV) . No pathogenic bacteria were isolated from cases or samples of food served at the reception . Electron microscopy of three stool specimens revealed no viruses, but SRSV was subsequently identified by reverse transcriptase polymerase chain reaction in one of two stool specimens . Environmental investigation in the kitchen revealed a number of deficiencies.

Mikrobiol Z, 1996 Sep-Oct, 58(5), 51 - 8
{Phagolysates of cyanobacteria: their biocidal properties and use}; Gol'din EB et al.; Data on the biological activity of cyanobacterial phagolysates were obtained in experiments . They concern the organisms of different evolutional level, such as some conventional pathogenic bacteria, plant and root parasitic nematodes and phytophagous insects . The authors suppose the specific mechanism of biocidal and inhibitory action of cyanobacteria and their phagolysates in respect to different living systems . These facts are very important for the elaboration of practical aspects of algal metabolites employment in agriculture and medicine.

Virus Res, 1996 Aug, 43(2), 111 - 24
Equine herpesvirus-1 strain KyA, a candidate vaccine strain, reduces viral titers in mice challenged with a pathogenic strain, RacL; Colle CF 3rd et al.; The equine herpesvirus type-1 (EHV-1) strain Kentucky A (KyA) has a long history of repeated passage either in vivo in the Syrian hamster or in vitro in mouse L-M fibroblast tissue culture . This repeated passage in cells other than those of the natural host has caused genomic alterations of the KyA chromosome resulting in deletion of several genes or portions of open reading frames (ORFs) . This report presents in vivo data from a mouse model of EHV-1 infection demonstrating the attenuated nature of EHV-1 strain KyA and that intranasal infection with KyA protects animals from subsequent challenge with a pathogenic strain, RacL, by reducing RacL viral titers in the lungs of the challenged animals . Mice infected with KyA exhibit no clinical manifestations of EHV-1 disease and do not experience the wasting that occurs with RacL infection . KyA-infected mice clear virus from the lung by day 5 post-infection (p.i.), whereas RacL infected mice have substantial virus titers (5 x 10(5) pfu/lung) at this time point . Intranasal infection with KyA followed by a challenge with RacL 4 weeks post-KyA infection resulted in a significant (P = 0.0079) reduction in the lung titers of the RacL virus . RacL was identified as the virus present in the lungs of the challenged mice by a PCR assay employing primers to amplify the EUS4 gene which differs in size by 1.2 kilobase pairs (kbp) in the two strains . Importantly, the protection afforded by KyA is long lasting in that challenge with RacL 15 months after KyA infection, results in reduced virus titers and viral clearance by day 5 post-challenge . These results support the further consideration of EHV-1 KyA as a live virus vaccine.

Kekkaku, 1996 Aug, 71(8), 477 - 94
{Respiratory infections--pathogenesis of acute and chronic infections}; Matsumoto K; Respiratory infections in Japan have rapidly changed, because pathogenesis has also changed by the increase of compromised hosts and aged people with the development of chemotherapeutic agents and another medical progresses . Various respiratory infections have been accumulated in our clinical department and clinical investigations were done for these diseases during almost 20 years . Firstly, pneumonias in adult T cell leukemia have been very severe and these diseases have occurred with load from pathogenic orophayngeal bacteria to lower respiratory airway . With another clinical studies, these pathogenesis which firstly pathogenic bacteria attach to orophayngeal epithelial cells and would move to lower respiratory airway to infect were given very clear evidences especially for Branhamella and Pneumococcus infections with chronic respiratory infections . The exact clearance of pathogenic orophayngeal bacteria using povidon iode solution was very useful for prevention of these acute or chronic respiratory infections . Although acute bronchitis is very popular, the secondary bacterial pathogens remained to be unknown, in the world . We showed that H . influenzae, S.pneumoniae and B.catarrhalis were common major pathogens as the secondary invading bacteria of acute bronchitis in Japan, Thailand and Bangladesh . Recently, the pathogenesis of severe chronic respiratory infections such as diffuse panbronchiolitis is focused after the development of erythromycin therapy . We gave some evidences of macrolides effectiveness which these drugs inhibited IL-8 production . We described the importance of inflammatory cell classification in sputa or bronchial secretions for deep understanding of inflammatory situation in broncho-bronchiolar airway.(ABSTRACT TRUNCATED)

Dtsch Tierarztl Wochenschr, 1996 Jul, 103(7), 250 - 6
{Risks due to the medication of feed and water in animal facilities}; Kamphues J; Goal of this contribution was a review concerning the different risks of application of drugs in food producing animals, excluding the development of resistance in pathogenic bacteria . Especially the risks of displacements of drugs and additives during the process of production of medicated feeds and its use under field conditions are concerned . Furthermore water medication and its problems of risks are presented . The onset of drug residues in food--inspite of the use of unmedicated feeds and water--is discussed for example as a consequence of contamination of feeds (especially in wet feeding systems in pigs), the surrounding and/or litters.

J Periodontal Res, 1996 Jul, 31(5), 345 - 54
Chymotrypsin-like enzyme secretion is stimulated in cultured epithelial cells during proliferation and in response to Actinobacillus actinomycetemcomitans; Firth JD et al.; A chymotrypsin-like enzyme was partially purified from culture medium of epithelial cells of human skin, human gingiva and porcine periodontal ligament by aprotinin-affinity chromatography . The enzyme levels from all three cell types were low in quiescent cultures but increased markedly when the cells were allowed to proliferate . The biphasic elution profile of the enzyme from the affinity column closely matched that of alpha-chymotrypsin and the protein comigrated with it on polyacrylamide gels at 27,000 ML . Synthetic substrate tests of purified fractions showed strong chymotrypsin-like but no trypsin-like or elastase-like activity . Inhibition of protease activity and pH optimum in the range of 7.5-8.0 were consistent with chymotrypsin-like enzymes . Secreted activity was found to be significantly increased by phorbol myristate acetate treatment in a time-course that differed from that of elastase-like activity . Keratinocyte growth factor and epidermal growth factor but not transforming growth factor-beta increased the chymotrypsin-like activity in a concentration-dependent manner . The enzyme secretion by epithelial cells was strongly elevated by exposure to 5 of 6 Actinobacillus actinomycetemcomitans strains isolated from plaque samples of juvenile periodontitis patients . These results indicate that chymotrypsin-like enzymes are secreted by proliferative phenotypes of normal epithelial cells . This enzyme may, therefore, play a role in epithelial physiology and in cell response to certain pathogenic bacteria.

Antiviral Res, 1996 Jul, 31(3), 149 - 58
Inhibition of arenavirus multiplication in vitro by phenotiazines; Candurra NA et al.; Trifluoperazine (TFP) and chlorpromazine (CPZ), two pharmacologically active phenotiazine derivatives, were evaluated for their inhibitory activity on the replication of the arenaviruses Junin (JV), the etiological agent of Argentine hemorrhagic fever, Tacaribe virus and Pichinde virus . Both compounds achieved a concentration-dependent inhibition of viral multiplication at concentrations not affecting cell viability . The 50% inhibitory concentration (IC50) values determined by a virus yield inhibition assay for several strains of JV, including a human pathogenic strain, were in the range of 7.7-23.0 microM and the 90% inhibitory concentration (IC90) fluctuated between 16.6 and 35.2 microM . From time of addition and removal experiments, it can be concluded that CPZ inhibited an early stage in the replicative cycle of JV, probably viral entry . TFP also affected JV penetration when present soon after virus adsorption, and also interfered with a later step of viral maturation when added after 7 h of infection . The expression of viral antigens in the cytoplasm of infected cells was highly reduced in the presence of the compounds, as revealed by immunofluorescence staining, whereas no JV proteins were detected at the cell membrane . The distribution pattern of viral proteins was altered in the few cells exhibiting positive fluorescence after treatment with the phenotiazines . The TFP-induced inhibitory effect on JV multiplication was significantly reversed in the presence of 5 microM calmodulin . These data indicate that TFP and CPZ inhibit JV replication in vitro . Our findings suggest that the integrity of the actin microfilaments may be required for optimal arenavirus multiplication.

Kansenshogaku Zasshi, 1996 Jul, 70(7), 717 - 26
{The effect of herbal medicines on the immunodeficient animals by injecting cancer chemotherapeutic agent-special reference to age related recovery of the function}; Li AL et al.; The acquired immunodeficiency of the host plays an essential role in the occurrence of infections even with low pathogenic bacteria . The increase of cases with MRSA and/or pseudomonas infection is one of the serious problems in hospital management in Japan for the elderly as well as pediatric patients . In the present study, mitomycin C (MMC)-treated hosts were prepared in young, adult and old mice to test the immunopotentiating action of the promising Chinese herbal medicine, Tohki-Rikuoh-Toh (TRT), Hotyu-Ekki-Toh (HET) and Juzen-Taiho-Toh (JTT) . The effect of these herbal medicines on organ structure and its function in the MMC-treated hosts is clarified and discussed for medical use . 4-5, 8-10 and over 50 week old male C57BL/6 (Clea Japan Inc.) were injected with MMC at a dosage of 3 to 5 mg/kg to inhibit the bone marrow, thus creating a mouse model with reduced immunopotential . A powder extract of TRT, HET and JTT was administrated orally at a dosage of 500 mg/kg/day for seven consecutive days . The white cell number and the subset analysis were carried out by the FACS method . The bactericidal effect of the host was monitored by NBT reduction test . Peritoneal macrophages were prepared by the adherence technique . The macrophage phagocytic activity was examined by an ACAS system . After the administration of TRT, HET and JTT, the body weights recovered as much as 90%, especially in young animals which had been reduced to 75% of their normal values . After MMC-treatment, with the herbal medicines, HET was good for young mice while JTT was effective for the old ones . As for the effect on B cells, the plaque-forming cells (PFC) of spleen cells were compared among the groups . As a result, PFC in the HET group was 184% and the other two were 80 approximately 95% as compared to 76% in the MMC-treated ones . The number of white blood cells in the MMC-treated mice returned to 80% of their normal value . In addition, the phagocytic activity of macrophages increased to 50% although that of the non-treated group was only 20% . The phagocytic activity also recovered in the JTT and TRT of 131% to 95%, respectively compared to 11% in the MMC-treated control . When TRT, HET and JTT were administered orally to mouse models whose immunopotential had been inhibited, the herbal medicines activated both quantitatively and qualitatively, showing themselves to be effective interstitial medicines . In addition, the data from the animal models showed no side effects, confirming the complete efficacy of the drug . Moreover, there was no direct anti-bactericidal effect from these medicines, suggesting that the immunomodulating action of this medicine is host-mediated . It is interesting that quantitative and qualitative recovery were seen when HET was administered to MMC-treated young hosts while JTT was good for the old . With this investigation, the effective components are still unknown for different generations, and we need to clarify this aspect for better understanding of the efficacy of herbal medicines.

Infect Immun, 1996 Jul, 64(7), 2680 - 6
Clonal structure and virulence factors in strains of Escherichia coli of the classic serogroup O55; Rodrigues J et al.; Virulence properties and genetic variation as determined by multilocus enzyme electrophoresis were studied in 70 strains of Escherichia coli 055, a common serogroup of enteropathogenic E . coli (EPEC), a major cause of infantile diarrhea in developing countries . Nearly 40% of the strains were originally isolated in Brazil and represented serotypes 055:H6, 055:H7, and 055:H51 and nonmotile (055:H-) strains . The analysis of electrophoretic variants of 20 enzymes defined seven distinct electrophoretic types (ETs) . ET 1 was represented by 41% of the strains, including strains which usually hybridized with DNA probes for the intimin gene (eaeA), the EPEC adherence plasmid (EAF), and the gene for the pilin subunit of the bundle-forming pilus (bfpA) . The ET 1 strains were also typically serotype 055:H6, displayed localized adherence (LA) in tissue culture assays, and were positive in the fluorescent-actin staining test for intimate cell adherence . These same characteristics were observed in the closely related ETs 2 to 4, which clustered in the same branch as ET 1 . No known virulence marker could be identified in ET 6 . ET 5 included 23 strains, all of which carried the eaeA gene but otherwise displayed a striking array of distinct virulence traits . This ET was represented by 055:H7 strains with phenotypes as diverse as the simultaneous expression of LA and diffuse adherence and the ability to form a newly described adherence pattern, called LA-like adherence . The results suggest that ET 5 marks a special pathogenic clone with a propensity to acquire virulence factors which may facilitate the emergence of new pathogenic strains.

Mol Cell Biol, 1996 Jul, 16(7), 3490 - 503
The lipopolysaccharide-binding protein is a secretory class 1 acute-phase protein whose gene is transcriptionally activated by APRF/STAT/3 and other cytokine-inducible nuclear proteins; Schumann RR et al.; Acute-phase reactants (APRs) are proteins synthesized in the liver following induction by interleukin-1 (IL-1), IL-6, and glucocorticoids, involving transcriptional gene activation . Lipopolysaccharide-binding protein (LBP) is a recently identified hepatic secretory protein potentially involved in the pathogenesis of sepsis, capable of binding the bacterial cell wall product endotoxin and directing it to its cellular receptor, CD14 . In order to examine the transcriptional induction mechanisms by which the LBP gene is activated, we have investigated the regulation of expression of its mRNA in vitro and in vivo as well as the organization of 5' upstream regulatory DNA sequences . We show that induction of LBP expression is transcriptionally regulated and is dependent on stimulation with IL-1beta, IL-6, and dexamethasone . By definition, LBP thus has to be viewed as a class 1 acute-phase protein and represents the first APR identified which is capable of detecting pathogenic bacteria . Furthermore, cloning of the LBP promoter revealed the presence of regulatory elements, including the common APR promoter motif APRE/STAT-3 (acute-phase response element/signal transducer and activator of transcription 3) . Luciferase reporter gene assays utilizing LBP promoter truncation and point mutation variants indicated that transcriptional activation of the LBP gene required a functional APRE/STAT-3 binding site downstream of the transcription start site, as well as an AP-1 and a C/EBP (CCAAT enhancer-binding protein) binding site . Gel retardation and supershift assays confirmed that upon cytokine stimulation APRF/STAT-3 binds to its recognition site, leading to strong activation of the LBP gene . Unraveling of the mechanism of transcriptional activation of the LBP gene, involving three known transcription factors, may contribute to our understanding of the acute-phase response and the pathophysiology of sepsis and septic shock.

Microb Ecol, 1996 Jul, 32(1), 1 - 10
Genetic Nature, Stability, and Improved Virulence of Hybrids from Protoplast Fusion in Beauveria
Couteaudier Y, Viaud M, Riba G.
Genetic improvement of two different strains of the entomopathogenic fungus Beauveria bassiana for more effective control of Ostrinia nubilalis and Leptinotarsa decemlineata was obtained by crosses with the insecticidal toxin-producing strain Beauveria sulfurescens . Protoplast fusion between diauxotrophic mutants resulted in the recovery of some stable prototrophic fusion products . The low levels of virulence of the wild type strain B . bassiana 28 isolated originally from L . decemlineata were enhanced both on L . decemlineata and O . nubilalis for one of the hybrids obtained (FP 8) from the cross B . bassiana 28xB . sulfurescens 2 . Fusion product 25 obtained from the cross between B . sulfurescens and the highly pathogenic strain B . bassiana 147 showed a three-day reduction in the LT50 towards O . nubilalis . Southern blot hybridization with nine probe-enzyme combinations were conducted on genomic DNAs from the original wild strains, parental mutant strains, and fusion products . Additive banding patterns or unique banding pattern of either parental strain was observed in five hybrids, indicating their status as recombinant and/or partially diploid . Combination of RFLP markers indicative of both parental genomes was never observed with fusion product FP 25 . The stability of the virulence following passage through insect-host and stability of molecular structure for the fusion products FP 8 and FP 25 suggest that asexual genetic recombination by protoplast fusion may provide an attractive method for the genetic improvement of biocontrol efficiency in entomopathogenic fungi.

Nature, 1996 Jun 20, 381(6584), 661 - 6
Identification of a major co-receptor for primary isolates of HIV-1; Deng H et al.; Entry of HIV-1 into target cells requires cell-surface CD4 and additional host cell cofactors . A cofactor required for infection with virus adapted for growth in transformed T-cell lines was recently identified and named fusin . However, fusin does not promote entry of macrophage-tropic viruses, which are believed to be the key pathogenic strains in vivo . The principal cofactor for entry mediated by the envelope glycoproteins of primary macrophage-tropic strains of HIV-1 is CC-CKR-5, a receptor for the beta-chemokines RANTES, MIP-1alpha and MIP-1beta.

Biochem Biophys Res Commun, 1996 Jun 5, 223(1), 104 - 11
Purification of Escherichia coli chromosomal segments without cloning; Bloch CA et al.; Pairs of genomic insertions made with elements carrying any one of several frequently used rare restriction sites allow physical purification of insertion delimited genes . However, native rare restriction sites can, either by causing (i) fragmentation of targeted intervals or (ii) generation of additional fragments that overlap electrophoretically with targeted ones, place severe limitations on this approach . We present a series of Escherichia coli mini-Tn10 insertions containing the rare-cutting polylinker 2 (RCP2) of rare restriction sites, which includes the 18-base-pair I-SceI site (absent from native E . coli sequences) . Pulsed-field gel purification from RCP2 double insertion mutants of both an I-SceI fragment from strain K-12 (containing approximately 90-95 min) and an allelic I-SceI fragment from a pathogenic strain is demonstrated . The complete series of RCP2 insertions, containing different antibiotic resistances at intervals of approximately 35 kb in prototype K-12 strain MG1655, allows rapid purification of the genes from any E . coli chromosomal interval as an isolated I-SceI fragment.

EMBO J, 1996 Jun 3, 15(11), 2613 - 24
A pathogenic bacterium triggers epithelial signals to form a functional bacterial receptor that mediates actin pseudopod formation; Rosenshine I et al.; Enteropathogenic E . coli (EPEC) belongs to a group of bacterial pathogens that induce actin accumulation beneath adherent bacteria . We found that EPEC adherence to epithelial cells mediates the formation of fingerlike pseudopods (up to 10 microm) beneath bacteria . These actin-rich structures also contain tyrosine phosphorylated host proteins concentrated at the pseudopod tip beneath adherent EPEC . Intimate bacterial adherence (and pseudopod formation) occurred only after prior bacterial induction of tyrosine phosphorylation of an epithelial membrane protein, Hp90, which then associates directly with an EPEC adhesin, intimin . These interactions lead to cytoskeletal nucleation and pseudopod formation . This is the first example of a bacterial pathogen that triggers signals in epithelial cells which activates receptor binding activity to a specific bacterial ligand and subsequent cytoskeletal rearrangement.

Mol Biochem Parasitol, 1996 Jun, 78(1-2), 47 - 54
A homologue of the cysteine proteinase gene (ACP1 or Eh-CPp3) of pathogenic Entamoeba histolytica is present in non-pathogenic E . dispar strains; Mirelman D et al.; One of the three cysteine proteinase genes, ACP1 (or CP 3), has been reported to be missing in non-pathogenic strains of Entamoeba histolytica (or Entamoeba dispar as recently labeled) . Unexpectedly, a gene fragment very similar in its sequence (95% homology) to ACP1 of pathogenic strains was obtained by use of the polymerase chain reaction from genomic DNA and cDNA of various cloned non-pathogenic strains as well as in 23 clinical isolates from asymptomatic carriers . The finding of the ACP1 homologue in non-pathogenic or E . dispar strains rules out the proposed use of its absence for diagnostic purposes.

Eur J Immunol, 1996 Jun, 26(6), 1359 - 64
Human and rodent interferon-gamma as a growth factor for Trypanosoma brucei; Bakhiet M et al.; An example for the bidirectional exchange of activating signals between a pathogen and immunocompetent cells in the host is presented . Trypanosoma brucei, which include subspecies that cause African sleeping sickness, secrete a molecule that triggers lymphocytes to produce interferon (IFN)-gamma . We now report that proliferation of T . brucei is stimulated in axenic cultures by IFN-gamma . The growth-enhancing effect on the pathogen is inhibited by anti-IFN-gamma receptor (R) antibodies and does not occur after exposure to other cytokines, i.e . IFN-alpha, IFN-beta and tumor necrosis factor (TNF)-alpha . While rodent-pathogenic T . brucei strains are stimulated by rat IFN-gamma, human pathogenic strains are more potently stimulated by human IFN-gamma . Rat and human IFN-gamma can partially block each others effects . Mice with disrupted IFN-gamma genes have reduced parasitemia and prolonged survival, while the outcome is reversed in mice that lack the IFN-gamma R gene.

Ann Emerg Med, 1996 Jun, 27(6), 721 - 5
Utility of blood cultures in pediatric patients found to have pneumonia in the emergency department; Hickey RW et al.; STUDY OBJECTIVE: To determine the prevalence of bacteremia in pediatric patients with radiographic evidence of pneumonia in whom blood cultures were obtained . METHODS: We carried out a retrospective review of the radiology log of a tertiary care children's hospital to identify patients with radiographic evidence of pneumonia seen between August 1991 and July 1992 . These patients were cross-referenced with the hospital laboratory information system, yielding results of any CBC or blood cultures . RESULTS: We found 939 patients with chest radiography findings consistent with pneumonia . Blood culturing was performed in 409 (44%) . Eleven of these cultures (2.7%) grew pathogenic bacteria . Review of the medical records revealed no changes in clinical management made on the basis of the results of the blood cultures . CONCLUSION: Blood cultures are uncommonly positive in outpatients diagnosed with pneumonia.

Mycoses, 1996 May-Jun, 39(5-6), 233 - 5
Phospholipase activity in Malassezia furfur pathogenic strains; Riciputo RM et al.; The lipophilic dimorphic yeast Malassezia furfur is a common skin commensal and the aetiological agent of pityriasis versicolor . A source of lipids is essential for its growth, and there are already demonstrations of in vitro lipase and lipoxygenase production . In eight wild strains, isolated from patients with pityriasis versicolor, we showed a phospholipase activity using a medium containing egg yolk emulsion as the only source of lipids; in this medium M . furfur grows and produces a phospholipase zone . Adding manganese sulphate, an unspecific inhibitor of phospholipase activity, M . furfur does not grow, because the lipophilic fungus cannot utilize the egg yolk as a source of fatty acids . Adding Tween 60 to the same medium, M . furfur also grows in presence of manganese sulphate.

Curr Biol, 1996 May 1, 6(5), 504 - 7
A virus joins the movement . Intracellular pathogens; Strauss EJ; Vaccinia virus has recently been shown to induce inside its host cells the formation of actin tails very similar to those which facilitate the cell-to-cell spread of several pathogenic bacteria.

Mol Plant Microbe Interact, 1996 May, 9(4), 252 - 60
Phenotypic expression of Pseudomonas syringae avr genes in E . coli is linked to the activities of the hrp-encoded secretion system; Pirhonen MU et al.; The specific recognition of elicitors produced by plant pathogenic bacteria carrying avirulence (avr) genes is postulated to initiate cellular defense responses in plants expressing corresponding resistance genes . The biochemical functions of most avr genes, however, are not known . A heterologous system was developed to phenotypically express Pseudomonas syringae avr genes in Escherichia coli cells that required the P . syringae hrp cluster . E . coli MC4100 transformants carrying the plasmic-borne P . syringae pv . syringae Pss61 hrp cluster and p . syringae pv . glycinea avrB expressed from a triple lacUV5 promoter gained the ability to elicit the hypersensitive response in soybean cultivars expressing Rpg1 and in an Arabidopsis thaliana accession expressing RPM1 . Inactivation of energy transducing or outer membrane components of the hrp-encoded secretion system blocked phenotypic expression expression of avrB in E . coli, but deletions abolishing harpinPSS production had little effect on the production of the AvrB phenotype by the E . coli transformants . Phenotypic expression of avrA, AvrPto, avrRpm1, avrRpt2, and avrPph3 in E . coli was also shown to require the hrp cluster . The results indicate that generation of the Avr phenotype in P . syringae strains is specifically dependent on the secretion activities of the hrp cluster.

J Bacteriol, 1996 May, 178(10), 2775 - 84
Analysis of 0.5-kilobase-pair repeats in the Mycoplasma hominis lmp gene system and identification of gene products; Ladefoged SA et al.; Mycoplasma hominis, an opportunistic pathogenic bacterium of humans, has a small genome of 700 kb . Despite this, multiple copies of gene sequences with similarities to the structural gene (lmp1) of a 135-kDa surface-located membrane protein (Lmp1) have been identified on the genome of M . hominis PG21 (lmp2, lmp3, and lmp4) . The distance between the lmp1-lmp2 region and the lmp3-lmp4 region was more than 110 kb . lmp3-lmp4 of M . hominis PG21 was sequenced and found to contain two putative genes . The gene region of 6.5 kb contained a 5' unique region and a 3' unique region separated by 9 0.5-kb repeats with 51 to 90% similarity to 10 similar repeats found in the lmp1-lmp2 region . The 0.5-kb DNA repeats thus comprised about 1% of the entire genome . In both regions, a base change in one of the repeats gave rise to a stop codon, and thereby lmp2 and lmp4 occurred . By PCR amplification of reverse-transcriptase-generated cDNA it was shown that all four genes were transcribed . By use of Lmp-specific antibodies we showed that both lmp1 and lmp3 were translated into proteins (Lmp1 and Lmp3) . Each of the four lmp genes represented by their unique cloned segments was used as a probe to analyze the presence, distribution, and organization of the genes within the genome in 13 M . hominis isolates . The repetitive element was detected at one or two locations on the chromosome for all isolates . The lmp3-specific element was present in all isolates, and lmp1- and lmp2-specific elements were present in all but one isolate . The lmp4-specific element was present in about half the isolates tested . For five M . hominis isolates the chromosomal location of the lmp genes was mapped.

Clin Otolaryngol, 1996 Apr, 21(2), 158 - 61
The incidence of bacteria in middle ear effusions; Hinton A et al.; Otitis media with effusion (OME) is a common condition in paediatric ENT practice . Whilst surgical management is in many cases the mainstay of treatment for resistant OME, the use of antibiotics has been advocated by some authorities . Over one quarter of middle ear effusions analysed in this study contained potentially pathogenic bacteria . Antibiotics may be of value in the treatment of OME in these children.

Infect Immun, 1996 Apr, 64(4), 1265 - 71
Ultrastructural changes in avian Chlamydia psittaci serovar A-, B-, and D-infected Buffalo Green Monkey cells; Vanrompay D et al.; In order to find an explanation for the observed differences in levels of pathogenicity in turkeys of Chlamydia psittaci 84/55 (avian serovar A), 89/1326 (avian serovar B), 92/1293 (avian serovar D), and the Texas Turkey strain (avian serovar D) (P.B . Wyrick, J . Choong, S.T . Knight, D . Goyeau, E.S . Stuart, and A.B . MacDonald, Immunol . Infect . Dis . 4:131-141, 1994), the reproductive cycles of organisms of the four strains were studied in Buffalo Green Monkey cells by transmission electron microscopy, immunoelectron microscopy, and flow cytometry . Organisms of strains most pathogenic in turkeys, namely, the serovar A strain and the 92/1293 serovar D strain, (i) replicated faster, since at 50 h postinoculation significantly larger inclusions with more numerous infectious organisms were observed than with the less pathogenic strains; (ii) were often found devoid of inclusion membranes scattered throughout the cytoplasms; and (iii) induced severe degenerative changes in Buffalo Green Monkey cells . By immunoelectron microscopy and flow cytometry, chlamydial antigens could not be detected in the plasma membranes of infected host cells . However, the presence of chlamydial antigens in inclusion membranes was demonstrated by immunoelectron microscopy.

Parasite Immunol, 1996 Mar, 18(3), 133 - 7
Evidence for the existence of ganglioside molecules in the antigen of Entamoeba histolytica; Sorice M et al.; Gangliosides were found to be present in Entamoeba histolytica . They were extracted from lyophilized trophozoites of the pathogenic strain HM-1:IMSS and purified by high performance thin-layer chromatography . Two resorcinol-positive bands, comigrating with GM2 and GD1a were demonstrated, revealing the existence of ganglioside molecules in Entamoeba histolytica . The GM2 content, determined as lipid-bound sialic acid, was 1.5 micrograms/10(8) amoebae, the content of the GD1a comigrating band was 0.32 microgram/10(8) amoebae . The identity of the GM2 comigrating band was confirmed by TLC immunostaining, using the monoclonal anti-GM2 antibody GMB28 . Furthermore, six out of ten anti-amoeba positive sera selectively reacted with the GM2 comigrating band, as revealed by immunostaining on TLC plates . Absorption tests revealed that preincubation of anti-amoeba positive sera with standard GM2 was followed by a significant decrease in the reaction with amoeba trophozoites by indirect immunofluorescence . These results demonstrate that a GM2 comigrating component of Entamoeba histolytica may be one of the antigens responsible for the appearance of circulating antibodies in patients with amoebiasis.

Rev Sci Tech, 1996 Mar, 15(1), 323 - 35
Validity of using serological tests for diagnosis of diseases in wild animals; Gardner IA et al.; Transposition of diagnostic tests used in domestic livestock species to free-ranging and captive wildlife species has two problems . First, most existing tests have not been adequately validated in domestic livestock . Second, assumptions that a serological test will perform identically in wildlife and livestock species may not be correct, due to differences in pathogenic strains and serovars, host serological responses, and exposure to organisms of similar antigenic structure which produce cross-reacting antibodies . Some assays require species-specific reagents/test components which might not be commercially available, and most assays have not been standardized . The authors outline the principles involved in the evaluation of a serological diagnostic test, and provide examples of how knowledge of test sensitivity and specificity can be used to estimate true prevalence, to determine whether a population is infected, and to facilitate management decisions with regard to animal translocations.

Int J Oral Maxillofac Implants, 1996 Mar-Apr, 11(2), 245 - 50
Histologic study of failed hollow implants; Takeshita F et al.; Nine hollow dental implants that were removed from patients were examined histologically to determine whether there was a common mechanism of failure with this implant design . When a hollow implant showed saucerized bone loss at the neck portion radiologically, the hollow portion was divided histologically into soft tissue and bone tissue . In advanced cases, stratified flattened epithelium that had invaded the hollow and the dead space at the top was observed . The condition of bone tissue located in the bottom of the basket can be adversely affected by an unfavorable crown-root ratio . The presence of an empty basket may cause fracture of the basket portion . The hollow portion can foster the growth of pathogenic bacteria . The hollow-type implant may not be suitable for immediate placement because surrounding soft tissues can invade the basket immediately.

Plant Mol Biol, 1996 Mar, 30(5), 995 - 1008
Molecular cloning of a sulfotransferase in Arabidopsis thaliana and regulation during development and in response to infection with pathogenic bacteria; Lacomme C et al.; A cDNA clone (RaRO47) encoding a sulfotransferase (ST) has been isolated from Arabidopsis cell suspensions . The deduced polypeptide of 302 amino acids is highly related to plant flavonol sulfotransferases (FSTs), characterized for the first time in Flaveria, and also to STs from animal tissue . The expression of the Arabidopsis ST gene(s) corresponding to RaR047 was examined during different developmental stages . It was found that, at the level of steady-state mRNA, expression of gene(s) encoding this ST was rapidly induced in the aerial parts of young seedlings, and during growth of Arabidopsis cell cultures . No expression could be detected in roots . Treatment of Arabidopsis seedlings with hormonal or stress-related compounds, showed that RaR047 mRNA accumulation was more particularly induced in response to salicylic acid and methyl jasmonate . Furthermore, in the leaves of mature plants or in cell suspensions, accumulation of RaR047 mRNA was observed upon infection with bacterial pathogens . This expression was observed preferentially in response to avirulent pathogens causing an hypersensitive reaction, as compared to virulent pathogens, which lead to disease.

Ophthalmology, 1996 Mar, 103(3), 485 - 94
Amebic keratitis in a wearer of disposable contact lenses due to a mixed Vahlkampfia and Hartmannella infection; Aitken D et al.; PURPOSE: To support the hypothesis that Acanthamoeba is not a unique cause of amebic keratitis, we report a case of amebic keratitis in which viable Acanthamoeba could not be isolated from corneal tissue . Vahlkampfia and Hartmannella, two other genera of free-living ameba, were isolated, however, using prolonged culture . METHODS: A 24-year-old wearer of soft contact lenses had keratitis . Extensive histologic and microbiologic investigations were performed on corneal scrape, biopsy, and keratoplasty tissue . Contact lenses, storage case, and the home water supply, where contact lens hygiene was practiced, were examined for the presence of micro-organisms . RESULTS: No viruses, pathogenic bacteria, or fungi were detected from corneal tissue samples . Amebae were observed using light and electron microscopy, but these could not be unequivocally classified using immunocytochemical staining . Viable Vahlkampfia and Hartmannella, but no Acanthamoeba, were isolated from the corneal biopsy sample . Indirect immunofluorescence with a range of polyclonal rabbit antisera raised against axenically cultivated stains of the three amebal genera was unhelpful because of cross-reactivity . A diverse range of micro-organisms was present within the storage case, including the three amebal species . Amebic cysts also were associated with the contact lens . CONCLUSION: A mixed non-Acanthamoeba amebic keratitis has been identified in a wearer of soft contact lenses where lack of storage case hygiene provided the opportunity for the free-living protozoa Vahlkampfia and Hartmannella to be introduced to the ocular surface . When Acanthamoeba-like keratitis occurs, but where Acanthamoeba cannot be isolated using conventional laboratory culture methods, alternate means should be used to identify other amebae that may be present . Polyclonal immunofluorescent antibody staining was unreliable for generic identification of pathogenic free-living amebae in corneal tissue.

Med Microbiol Immunol (Berl), 1996 Feb, 184(4), 195 - 201
Diversity of OspA and OspC among cerebrospinal fluid isolates of Borrelia burgdorferi sensu lato from patients with neuroborreliosis in Germany; Wilske B et al.; Neuroborreliosis is the most frequent manifestation of the second stage of Lyme borreliosis in Europe . However, only few isolates from the cerebrospinal fluid (CSF) have been characterized with controversial results . A large panel of 36 CSF isolates isolated over a 10-year period in Munich has now been analyzed for their OspA and OspC type, resulting in at least eight different types, respectively . Representatives of the different types cultivated from CSF in Munich have also been isolated from other geographical regions in Europe from CSF or ticks, suggesting a widespread distribution of pathogenic strains . A certain OspA type (type 4) was frequently observed in adults but rarely in children or ticks . Since OspA and OspC are the most promising candidates for a Borrelia vaccine, the considerable heterogeneity found among CSF isolates has important implications for development of a vaccine in Europe.

Rev Prat, 1996 Jan 15, 46(2), 177 - 83
{Infectious diarrhea in young children and infants}; Quinet B; Acute diarrhoea is one of the major causes of outpatient paediatric consultation, especially during infancy . An infectious cause should be suspected on the acute onset of diarrhoea associated with fever . The specific pathogen is seldom investigated and individualized . Rotavirus has been recognized as the most important enteric pathogen, particularly in infants during winter months . It may be responsible for nosocomial infections in hospital and outbreaks in day-care centers . Bacteria may cause a diarrhoea by elaboration of enterotoxins, by invasiveness, or both . Use of antibiotic is usually not necessary even in bacterial infections because they are self-limited . Choice of the antibiotic is complicated by the rapid emergence of resistant pathogenic strains . The first step is rapid assessment of the hydratation status of the patient . Fluid and electrolytes replacement is the mainstay in the treatment of infectious diarrhoea of any cause.

Vestn Ross Akad Med Nauk, 1996, (8), 18 - 22
{Protective features of pore-forming proteins of pathogenic bacteria}; Supotnitskii MB; The paper analyzes the results of investigations of the protective properties of pore-forming proteins (porins) from pathogenic bacteria . The high immunogenicity of porins is shown to allow them to use as components of chemical vaccines to combat infectious disease pathogens against which effective agents for specific prophylaxis could not be designed . It is suggested that bacterial pore-forming proteins play the same role in the infectious process as virus-confluent proteins do and can make a ligand-receptor interaction with the eukaryotic cellular membranous surface . These two properties may be also used to design new agents for the treatment and prevention of infectious diseases.

J Thorac Imaging, 1996 Spring, 11(2), 92 - 108
Types and mechanisms of pulmonary atelectasis; Woodring JH et al.; Atelectasis is one of the most commonly encountered abnormalities in chest radiology and remains a daily diagnostic challenge . At times atelectasis can be overlooked, particularly when pulmonary opacification is minimal or absent, and at other times it might be interpreted as being some other form of intrathoracic pathology, particularly pneumonia . The direct signs of atelectasis are crowded pulmonary vessels, crowded air bronchograms, and displacement of the interlobar fissures . Indirect signs of atelectasis are pulmonary opacification; elevation of the diaphragm; shift of the trachea, heart, and mediastinum; displacement of the hilus; compensatory hyperexpansion of the surrounding lung; approximation of the ribs; and shifting granulomas . For descriptive purposes, atelectasis can be divided into the following types: segmental, lobar, or whole lung; subsegmental; platelike, linear, or discoid; round; and generalized or diffuse . Resorption atelectasis is caused by resorption of alveolar air distal to obstructing lesions of the airways; adhesive atelectasis stems from surfactant deficiency; passive atelectasis is caused by simple pneumothorax, diaphragmatic dysfunction, or hypoventilation; compressive atelectasis is due to tension pneumothorax, space-occupying intrathoracic lesions, or abdominal distention; cicatrization atelectasis stems from pulmonary fibrosis; and gravity-dependent atelectasis is the result of gravity-dependent alterations in alveolar volume . Whenever signs of volume loss are present on a chest radiograph, the radiograph should be interpreted as showing atelectasis . By understanding the various mechanisms leading to atelectasis, and by considering the underlying conditions, the radiologist should be able to develop an appropriate list of the possible causes of atelectasis . The diagnosis of atelectatic pneumonia should be based upon the presence of clinical signs and symptoms of pneumonia coupled with the identification of pathogenic bacteria in sputum, tracheal aspirates, or protected bronchoalveolar lavage or bronchial brush specimens rather than on the radiographic identification of atelectasis alone.

Crit Rev Microbiol, 1996, 22(2), 67 - 100
Functions of bacterial flagella; Moens S et al.; Many bacterial species are motile by means of flagella . The structure and implantation of flagella seems related to the specific environments the cells live in . In some cases, the bacteria even adapt their flagellation pattern in response to the environmental conditions they encounter . Swarming cell differentiation is a remarkable example of this phenomenon . Flagella seem to have more functions than providing motility alone . For many pathogenic species, studies have been performed on the contribution of flagella to the virulence, but the result is not clear in all cases . Flagella are generally accepted as being important virulence factors, and expression and repression of flagellation and virulence have in several cases been shown to be linked . Providing motility is always an important feature of flagella of pathogenic bacteria, but adhesive and other properties also have been attributed to these flagella . In nonpathogenic bacterial colonization, flagella are important locomotive and adhesive organelles as well . In several cases where competition between several bacterial species exists, motility by means of flagella is shown to provide a specific advantage for a bacterium . This review gives an overview of studies that have been performed on the significance of flagellation in a wide variety of processes where flagellated bacteria are involved.

Chir Organi Mov, 1996 Jan-Mar, 81(1), 55 - 61
Evaluation of prognostic significance of circulating interleukin-6 in patients with accident spine injuries; Honorati MC et al.; Our study aimed to verify whether patients with spine accident injury present altered plasma levels of IL-6 and whether the levels of this cytokine are related with the production of acute phase proteins which are elevated after trauma and infection . 34 subjects admitted to an Intensive Care Unit for spine injuries were examined: 26 presented fever over 38.5 degrees C and in 13 of them blood or local cultures were positive for pathogenic bacteria . IL-6, C-reactive protein (CRP), haptoglobin (HPT), alpha 2-macroglobulin (alpha 2Mg), C3c and C4 Complement factors were determined on admission and in the course of their hospital stay . No changes in IL-6 systemic levels were present in the subjects examined and only CRP was constantly high . Although within the normal range IL-6 levels inversely correlated with fever . Our results show the difficulty to utilize the IL-6 circulating levels as prognosis parameter in patients subjected to spine accident injuries.

Infect Agents Dis, 1996 Jan, 5(1), 1 - 7
Pathogenicity islands and the evolution of bacterial pathogens; Lee CA; The term pathogenicity island has been used to refer to large chromosomal regions in pathogenic bacteria that encode virulence genes . This article reviews the recent history of this term and considers what characteristics define a pathogenicity island . It appears that pathogenicity islands can confer complex virulence phenotypes and were acquired by bacteria from unrelated organisms, leading to interesting hypotheses about how bacterial pathogens evolved . It is likely that mechanisms that generate pathogenicity islands continue to operate and may contribute to the emergence of bacterial pathogens with new virulence properties.

Vet Parasitol, 1996 Jan, 61(1-2), 15 - 20
Light microscopy diagnosis of Babesia bovis and Babesia bigemina kinetes in the haemolymph of artificially infected Boophilus microplus engorged female ticks; Guglielmone AA et al.; The length, width and position of the nucleus of Babesia bovis and Babesia bigemina kinetes from the haemolymph of Boophilus microplus engorged female ticks were recorded . Additionally, the shape of Babesia bovis kinetes were registered as curved, semi-curved or straight . To this aim Boophilus microplus tick larvae from a colony free of Babesia were fed on splenectomised calves artificially infected with either Babesia bovis or Babesia bigemina pathogenic strains . Six engorged female ticks showing an infection of at least ten mature kinetes of Babesia bovis in a sample of haemolymph 5 days after detachment were also monitored 7, 9 and 10 days after collection . The same procedure was followed with six engorged female ticks infected with Babesia bigemina . One hundred and twenty kinetes of each species of Babesia were evaluated . The mean length +/- standard deviation and ranges for Babesia bovis kinetes were 14.30 +/- 0.922 microns and 11.9-16.3 microns, while the corresponding measures for the kinetes of Babesia bigemina were 11.27 +/- 0.900 microns and 9.0-13.1 microns (P < 0.001, t-test) . The width was 3.33 +/- 0.315 microns, 2.6-4.0 microns for Babesia bovis and 2.24 +/- 0.287 microns, 1.5-2.8 microns for Babesia bigemina kinetes (P < 0.001) . The most common position of the nucleus was central for both species of Babesia . A total of 58% of Babesia bovis kinetes showed the typical curved tail . No effect of time post-collection and individual host ticks in the kinete of Babesia bigemina was found while an unexpected influence of individual host tick in the width of Babesia bovis kinetes was detected (P < 0.01, analysis of variance) . The overlap in the sizes of kinetes from both species of Babesia makes it difficult to apply the results to ticks of unknown babesial infection status . This finding is further complicated by the intra-specific size variations of Babesia kinetes from different geographical origins.

Recent Prog Horm Res, 1996, 51, 405 - 14; discussion 415
Protein tyrosine phosphatases: their roles in signal transduction; Dixon JE; Protein tyrosine phosphatases play critical roles in a number of cellular signal transduction pathways . Receptor-like PTPases such as CD45 are essential for antigen-induced proliferative responses of T-cells . Intracellular PTPases have been shown to associate with specific growth factor receptors and this association has a dramatic effect on receptor signaling mechanisms . Other phosphatases (e.g., the product of the CDC25 gene) are essential for cell cycle progression . It appears that the cellular location of the intracellular PTPases plays an important role in defining the substrate specificity . Phosphatases are also present in both pathogenic bacteria and viruses . These PTPases most likely function to disrupt important signal transduction pathways present in the host . More than 30 different phosphatases have been cloned and characterized . A detailed understanding of their catalytic properties suggests that all PTPases use a common mechanism for removing phosphatase from various phosphoproteins . Two PTPase structures recently have been determined . The structural information along with biochemical and kinetic data provides a basis for understanding the catalytic properties of these enzymes.

Can J Microbiol, 1996 Jan, 42(1), 27 - 37
Influence of disease-suppressive strains of Streptomyces on the native Streptomyces community in soil as determined by the analysis of cellular fatty acids; Bowers JH et al.; Analysis of cellular fatty acid profiles was used to distinguish among introduced pathogen- suppressive strains and indigenous strains of Streptomyces spp . isolated from soil of field plots established to test the efficacy of Streptomyces strains PonSSII and PonR in the biological control of potato scab . Reference libraries of fatty acid profiles were developed for a collection of known pathogenic strains and the introduced suppressive strains . Population densities of pathogen-related, suppressive, and saprophytic Streptomyces strains were determined from the relationship of field isolates to mean library profiles using cluster analysis and the unweighted pair-group method using arithmetic averages . Community diversity was similarly determined . Streptomyces strains PonSSII and PonR were distinguished from each other and from the pathogen group (which clustered together) based on fatty acid profiles . The introduced, suppressive strains successfully colonized the soil and represented 2-19% of the isolates sampled over 2 years . The introduction of the suppressive strains inhibited the population of strains related to the pathogen library at each sample date; the pathogen population was substantially lower in soil from treatments where the suppressive strains were introduced compared with the nonamended control . At harvest, the pathogen-related population was suppressed 85-93 and 36-44% in 1991 and 1992, respectively, in treatments with the suppressive strains compared with the nonamended control . Diversity of the community was not affected by the introduced strains, and diversity and equitability indices were similar among treatments at any sample time . The inhibition of the pathogen-related population was correlated with a reduction of scab symptoms observed in the field plots into which the suppressive strains were introduced . Implications of a fundamental shift in the pathogen-related population in response to the introduction of the suppressive strains for long-term biological control of potato scab are encouraging.

Am J Med, 1996 Jan, 100(1), 65 - 70
Is presentation of bacteremia in the elderly the same as in younger patients?
Chassagne P, Perol MB, Doucet J, Trivalle C, Menard JF, Manchon ND, Moynot Y, Humbert G, Bourreille J, Bercoff E.
OBJECTIVE: To compare the presentation of bacteremia in young and elderly patients . PATIENTS AND METHODS: Seventy-one elderly (mean age 80.4 years) and 34 younger inpatients (mean age 45.7 years) with bacteremia were prospectively studied . These were compared with a control group of 187 geriatric patients (mean age 81.3 years) with clinical signs of bacteremia but in whom blood cultures were negative . Bacteremia was defined as one or more positive blood cultures showing a pathogenic bacteria in patients with clinical signs of bacteremia . In all 105 patients with bacteremia, 16 common clinical or biological signs of the disease were immediately investigated after blood culture . Patients were classified into three groups: elder patients and young patients with bacteremia and elderly patients without bacteremia . RESULTS: Only three clinical findings of the 16 studied were found in at least 70% of the bacteremic elderly patients: fever, increased erythrocyte sedimentation rate, and a clinical indication of the source of infection . These three signs were found statistically more often in bacteremic elderly compared with nonbacteremic elderly patients (P < 0.01) . Seven other signs (hypothermia, altered mental state, leukopenia, and lymphopenia) had a specificity above 80% . On a logistic regression analysis, four variables were significantly and independently associated with bacteremia in the elderly: rapid onset of infection (defined as a period < or = 48 hours between the earliest manifestation of bacteremia and the time of blood blood sample), fever, altered general state, and clinical indication of the source of infection . Younger infected patients had more chills, sweating, alter general state, altered mental state or lymphopenia than did the bacteremic elderly patients . Bacteremic elderly patients had statistically few symptoms than the young infected patients (P < 0.001) . CONCLUSIONS: In elderly patients with early stage bacteremia, most of the signs or symptoms that are considered typical in the literature appear irregularly . None appeared pathognomonic . Elderly patients with bacteremia had fewer signs or symptoms than younger infected patients.

J Med Microbiol, 1996 Jan, 44(1), 65 - 9
Lack of interference between IgA-binding proteins and IgA proteases of human pathogenic bacteria; Stenberg L et al.; Some human bacterial pathogens produce specific immunoglobulin A1 (IgA1) proteases that cleave the heavy chain of human IgA1, generating intact Fab and Fc fragments . Other pathogenic bacterial species express surface proteins which bind to the Fc part of human IgA in a non-immune manner . To analyse whether IgA-binding proteins affect the activity of IgA1 proteases, the ability of seven different IgA1 proteases to hydrolyse IgA1 in the presence of either of two different bacterial IgA-binding proteins was tested . Data obtained in two different types of experiment suggest that IgA1 bound to IgA-binding proteins still functions as a substrate for IgA1 proteases . As Fc fragments produced by cleaving IgA1 with IgA1 proteases still bind to IgA-binding proteins, we conclude that these two types of bacterial protein act independently of each other.

Eur J Biochem, 1995 Dec 15, 234(3), 747 - 58
Solution conformation of the Pseudomonas syringae pv . syringae phytotoxic lipodepsipeptide syringopeptin 25-A . Two-dimensional NMR, distance geometry and molecular dynamics; Ballio A et al.; Syringopeptin 25-A is a phytotoxic amphiphilic lipodepsipeptide containing 25 amino acid residues, produced by some isolates of the plant pathogenic bacterium Pseudomonas syringae pv . syringae . Previous papers have reported its covalent structure and some of its biological properties . Attention has now been directed to define its conformation in solution, a structural feature regarded as important for understanding its possible role in the bacterial colonization of host plants, and its toxic action on the plant cell . Here we report the stereochemistry of its amino acid components, the complete interpretation of the two-dimensional NMR spectra and NOE data, and finally the structure obtained by computer simulations applying distance geometry and molecular dynamics procedures . The conformation of syringopeptin 25-A in aqueous solution includes three different structural regions interrupted by rigid 2,3-dehydro-2-aminobutyric acid residues: a loop from residue 2 to 6, a helicoidal zone from 8 to 15, and the lactone ring from 18 to 25 . The three-dimensional structure of the lactone moiety is very similar to that of two previously studied bioactive lipodepsinonapeptides . Preliminary circular dichroism evidence of conformational variations in solution of trifluoroethanol, which stimulates a membrane-like environment, are also reported.

Mol Cell Probes, 1995 Dec, 9(6), 405 - 14
Typing of Legionella pneumophila serogroup 1 isolates by degenerate (D-)RAPD fingerprinting; Sakallah S et al.; A new method to identify clonal strains of pathogenic bacteria has been developed recently in this laboratory . The method utilizes degenerate random amplified polymorphic DNA primers (D-RAPD) to amplify random fragments in crude bacterial lysates, generating reproducible DNA banding profiles or fingerprints . We use this method to type outbreak and non-outbreak isolates of Legionella pneumophila serogroup 1 from four hospitals near to, and affiliated with the University of Pittsburgh Medical Center . Patient isolates from a large outbreak, and nearly half of the contemporaneous environmental isolates showed the same DNA profile . Other isolates derived from non-outbreak patients showed easily distinguishable profiles . Other Legionella isolates collected between 1984 and 1994 were also analysed by this method . Our studies demonstrate that four strains were common among patient and environmental isolates at the four hospitals . These strains were also found to be different from a limited number of isolates from outside the Pittsburgh area . Because of its speed, simplicity and powerful discriminating ability, we believe that the D-RAPD approach provides epidemiologists and hospital infection control teams with a powerful tool in their efforts in analysing and terminating infection outbreaks.

FEMS Immunol Med Microbiol, 1995 Dec, 12(3-4), 265 - 72
Helicobacter pylori interacts with heparin and heparin-dependent growth factors; Ascencio F et al.; The pathogenic bacterium Helicobacter pylori, which causes active, chronic type B gastritis and peptic ulcer disease, and increases the risk for development of gastric cancer, could tentatively interfere with growth factors and growth factor receptors of importance for the gastroduodenal mucosa, e.g . heparin-binding FGFs (fibroblast growth factors) . H . pylori binds FGF with an extremely strong affinity (3.8 x 10(-12)M), and also heparan sulfate and heparin with higher affinity (Kd 9 x 10(-9)M) than FGFs bind to heparin (10(-8) - 10(-9)M) . FGF receptors are also dependent on heparin for their activation . Heparan sulfate binding proteins (HSBP) are exposed on and shed from the surface of H . pylori, which often are localised close to the epithelial stem cells in the gastroduodenal glands . H . pylori could thus efficiently interfere with growth factors and growth factor receptors, tentatively resulting in disturbance of the delicate balance that control the renewal, maintenance and repair of the gastroduodenal mucosa . This mode of action has previously not been considered, but may constitute part of its pathogenic mechanisms . Such a dynamic mode of action of H . pylori may explain the reason for that infected victims may either suffer from gastrointestinal symptoms or lack clinical evidence of disease or discomfort.

Antimicrob Agents Chemother, 1995 Dec, 39(12), 2689 - 91
In vitro activity of a new pneumocandin antifungal agent, L-733,560 against azole-susceptible and -resistant Candida and Torulopsis species; Vazquez JA et al.; The activity of a new water-soluble pneumocandin, L-733,560, was evaluated with 107 pathogenic strains of Candida and Torulopsis, which included 23 strains with known multi-azole resistance patterns . In vitro evaluation of L-733,560 activity was performed by a broth microdilution method, and the activity was compared with the activities of amphotericin B, fluconazole, ketoconazole, itraconazole, and flucytosine . The mean MICs of L-733,560 were 0.15 microgram/ml for C . lusitaniae, 0.72 microgram/ml for C . parapsilosis, 0.78 micrograms/ml for C . krusei, and 1.25 micrograms/ml for C . guilliermondii . The results indicate that the new antifungal agent L-733,560 demonstrated the best activity with the lowest MICs against C . albicans, T . glabrata, C . tropicalis, and C . kefyr, less activity against C . krusei, C . lusitaniae, and C . parapsilosis, and the least activity against C . guilliermondii . L-733,560 also demonstrated good activity against the various multi-azole-resistant Candida and T . glabrata isolates.

Infect Immun, 1995 Dec, 63(12), 4924 - 7
Identification of a mutation in the pst-phoU operon that reduces pathogenicity of an Escherichia coli strain causing septicemia in pigs; Daigle F et al.; We used transposon (TnphoA) mutagenesis to study the role of virulence factors of pathogenic Escherichia coli strains associated with septicemia in calves and piglets . We have produced an avirulent and serum-sensitive mutant of wild-type pathogenic strain 5131 O115:K"V165":F165 and have localized and identified the TnphoA insertion in the pstC gene of the pst-phoU operon . This operon encodes the PstSCAB transporter and PhoU protein that negatively regulate the phosphate (Pho) regulon . This mutation is pleiotropic and could have an effect on pathogenicity and on the production of the surface polysaccharides of strain 5131 . The mutant demonstrated restored repressibility of alkaline phosphatase and regained the capacity to resist serum and to survive systemically for at least 5 days in experimentally inoculated pigs when complemented with plasmid pAN92, bearing the pst-phoU operon.

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