Rev Prat, 2000 Sep 1, 50(13), 1427 - 30 {Helicobacter pylori and gastric neoplasms: adenocarcinoma and lymphoma}; Sobhani I; Helicobacter pylori is a risk factor for gastric carcinoma and an established carcinogenic bacterium . The relative risk to induce a gastric cancer is estimated to be 3 to 6 compared to that of individuals without H . pylori . Gastric atrophy and intestinal metaplasia in gastric mucosa are 2 well recognized precancerous lesions . Their occurrence and evolution are multifactorial depending on age at first infection, duration of infection and host's genetic characteristics . Prevention using H . pylori eradication is recommended only in individuals with high risk of cancer . Gastric lymphoma, although less frequent, may be due to H . pylori infection . Only in low grade lymphoma H . pylori eradication and periodic surveillance are recommended. Rev Prat, 2000 Sep 1, 50(13), 1414 - 7 {Epidemiology, acquisition and transmission of Helicobacter pylori}; Megraud F et al.; Helicobacter pylori infection is a chronic infection essentially acquired during childhood . Its prevalence in developed countries like France has decreased according to the year of birth all along the twentieth century, reflecting the progressive improvement of socio-economic and environmental conditions . The incidence of acquisition in adulthood is lower than 0.5% per year . In developing countries, the prevalence is still very high, even in early childhood . H . pylori is a strictly human bacterium . Its reservoir is essentially the stomach . Transmission most likely occurs between humans by an oro-oral or a gastro-oral transmission . Faeco-oral transmission, either direct or via the environment, is possible but seems to be rare in France. Eur J Clin Microbiol Infect Dis, 2000 Aug, 19(8), 608 - 11 Isolation of Kingella kingae from synovial fluids using four commercial blood culture bottles; Host B et al.; According to the literature, Kingella kingae may be an underdiagnosed cause of joint and bone infections in children . The use of the Bactec blood culture system for culture of joint fluids has dramatically improved the isolation of this fastidious bacterium . The aim of this study was to test the recovery rate and detection time of four commercial blood culture systems: three different BacT/Alert (Organon Teknika, USA) bottles and one Bactec (Becton Dickinson Microbiology Systems, USA) bottle, all inoculated with Kingella kingae strains mixed with pooled synovial fluids . For each strain the same inoculum and volume of synovial fluid was distributed into each of the four bottles . All 24 strains tested grew in the BacT/Alert Aerobic (100%) and the BacT/Alert Pedi-BacT (100%) bottles . Twenty-one strains grew in the BacT/Alert FAN aerobic (88%) bottle, and 15 strains grew in the Bactec Plus Aerobic F (63%) bottle, in both systems within 12 days (P<0.01) . The Kingella kingae strains were first detected in the BacT/Alert Pedi-BacT bottles (P<0.001) . The results were reproducible . The BacT/Alert blood culture bottles were superior to previously described blood culture systems in isolating Kingella kingae from synovial fluid, even with small inoculums and small volumes of synovial fluid. Appl Environ Microbiol, 2000 Oct, 66(10), 4514 - 7 Bacterial activity in South Pole snow; Carpenter EJ et al.; Large populations (200 to 5,000 cells ml(-1) in snowmelt) of bacteria were present in surface snow and firn from the south pole sampled in January 1999 and 2000 . DNA isolated from this snow yielded ribosomal DNA sequences similar to those of several psychrophilic bacteria and a bacterium which aligns closely with members of the genus Deinococcus, an ionizing-radiation- and desiccation-resistant genus . We also obtained evidence of low rates of bacterial DNA and protein synthesis which indicates that the organisms were metabolizing at ambient subzero temperatures (-12 to -17 degrees C). Appl Environ Microbiol, 2000 Oct, 66(10), 4497 - 502 Metabolic engineering of an aerobic sulfate reduction pathway and its application to precipitation of cadmium on the cell surface; Wang CL et al.; The conversion of sulfate to an excess of free sulfide requires stringent reductive conditions . Dissimilatory sulfate reduction is used in nature by sulfate-reducing bacteria for respiration and results in the conversion of sulfate to sulfide . However, this dissimilatory sulfate reduction pathway is inhibited by oxygen and is thus limited to anaerobic environments . As an alternative, we have metabolically engineered a novel aerobic sulfate reduction pathway for the secretion of sulfides . The assimilatory sulfate reduction pathway was redirected to overproduce cysteine, and excess cysteine was converted to sulfide by cysteine desulfhydrase . As a potential application for this pathway, a bacterium was engineered with this pathway and was used to aerobically precipitate cadmium as cadmium sulfide, which was deposited on the cell surface . To maximize sulfide production and cadmium precipitation, the production of cysteine desulfhydrase was modulated to achieve an optimal balance between the production and degradation of cysteine. Appl Environ Microbiol, 2000 Oct, 66(10), 4334 - 9 Involvement of an extracellular protease in algicidal activity of the marine bacterium Pseudoalteromonas sp . strain A28; Lee SO et al.; The marine bacterium Pseudoalteromonas sp . strain A28 was able to kill the diatom Skeletonema costatum strain NIES-324 . The culture supernatant of strain A28 showed potent algicidal activity when it was applied to a paper disk placed on a lawn of S . costatum NIES-324 . The condensed supernatant, which was prepared by subjecting the A28 culture supernatant to ultrafiltration with a 10,000-M(w)-cutoff membrane, showed algicidal activity, suggesting that strain A28 produced extracellular substances capable of killing S . costatum cells . The condensed supernatant was then found to have protease and DNase activities . Two Pseudoalteromonas mutants lacking algicidal activity, designated NH1 and NH2, were selected after N-methyl-N'-nitrosoguanidine mutagenesis . The culture supernatants of NH1 and NH2 showed less than 15% of the protease activity detected with the parental strain, A28 . The protease was purified to homogeneity from A28 culture supernatants by using ion-exchange chromatography followed by preparative gel electrophoresis . Paper-disk assays revealed that the purified protease had potent algicidal activity . The purified protease had a molecular mass for 50 kDa, and the N-terminal amino acid sequence was determined to be Ala-Thr-Pro-Asn-Asp-Pro . The optimum pH and temperature of the protease were found to be 8.8 and 30 degrees C, respectively, by using succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as a substrate . The protease activity was strongly inhibited by phenylmethylsulfonyl fluoride, diisopropyl fluorophosphate, antipain, chymostatin, and leupeptin . No significant inhibition was detected with EDTA, EGTA, phenanthroline or tetraethylenepentamine . These results suggest that Pseudoalteromonas sp . strain A28 produced an extracellular serine protease which was responsible for the algicidal activity of this marine bacterium. Appl Environ Microbiol, 2000 Oct, 66(10), 4300 - 4 Cloning, expression, and characterization of the katG gene, encoding catalase-peroxidase, from the polycyclic aromatic hydrocarbon-degrading bacterium Mycobacterium sp . strain PYR-1; Wang RF et al.; A 81-kDa protein from Mycobacterium sp . strain PYR-1 was expressed in response to exposure of the strain to the polycyclic aromatic hydrocarbon pyrene and recovered by two-dimensional gel electrophoresis . The N-terminal sequence of the protein indicated that it was similar to catalase-peroxidase . An oligonucleotide probe designed from this sequence was used to screen a genomic library of Mycobacterium sp . strain PYR-1, and a positive clone, containing a part of the gene encoding the 81-kDa protein, was isolated . A gene-walking technique was used to sequence the entire gene, which was identified as katG for catalase-peroxidase . The deduced KatG protein sequence showed significant homology to KatGII of Mycobacterium fortuitum and clustered with catalase-peroxidase proteins from other Mycobacterium species in a phylogenetic tree . The katG gene was expressed in Escherichia coli to produce a protein with catalase-peroxidase activity . Since the induction of this catalase-peroxidase occurred in pyrene-induced cultures and the exposure of these cultures to hydrogen peroxide reduced pyrene metabolism, our data suggest that this enzyme plays a role in polycyclic aromatic hydrocarbon metabolism by strain PYR-1. J Biotechnol, 2000 Sep 29, 83(1-2), 33 - 6 Helicobacter pylori gastritis: a Th1 mediated disease? Lohoff M, Rollinghoff M, Sommer F. Helicobacter pylori is now considered to be the main cause for most stomach diseases including ulcer, MALT lymphoma, adenocarcinoma and gastritis . The infection with this bacterium is chronic despite a local and systemic immune response towards it . Among the cellular infiltrate that arises during H . pylori-mediated gastritis, there is a considerable frequency of CD4+ Th1 cells producing IFNgamma, but not of Th2 cells producing IL-4 . Since IFNgamma may induce binding of H . pylori to gastric epithelial cells followed by apoptosis of these cells, one may speculate that H . pylori-mediated diseases are in part autoimmune diseases initiated by H . pylori-specific Th1 cells infiltrating the gastric mucosa . Recent support for this hypothesis comes from an animal model in which mice are infected with H . pylori and display strongly reduced gastritis in the absence of IFNgamma. Mol Microbiol, 2000 Sep, 37(6), 1357 - 71 Social motility in Myxococcus xanthus requires FrzS, a protein with an extensive coiled-coil domain; Ward MJ et al.; Gliding motility in the developmental bacterium Myxococcus xanthus involves two genetically distinct motility systems, designated adventurous (A) and social (S) . Directed motility responses, which facilitate both vegetative swarming and developmental aggregation, additionally require the 'frizzy' (Frz) signal transduction pathway . In this study, we have analysed a new gene (frzS), which is positioned upstream of the frzA-F operon . Insertion mutations in frzS caused both vegetative spreading and developmental defects, including 'frizzy' aggregates in the FB strain background . The 'frizzy' phenotype was previously considered to result only from defective directed motility responses . However, deletion of the frzS gene in an A-S+ motility background demonstrated that FrzS is a new component of the S-motility system, as the A-frzS double mutant was non-spreading (A-S-) . Compared with known S-motility mutants, the frzS mutants appear similar to pilT mutants, in that both produce type IV pili, extracellular fibrils and lipopolysaccharide (LPS) O-antigen, and both agglutinate rapidly in a cohesion assay . The FrzS protein has an unusual domain composition for a bacterial protein . The N-terminal domain shows similarity to the receiver domains of the two-component response regulator proteins . The C-terminal domain is composed of up to 38 heptad repeats (a b c d e f g)38, in which residues at positions a and d are predominantly hydrophobic, whereas residues at positions e and g are predominantly charged . This periodic disposition of specific residues suggests that the domain forms a long coiled-coil structure, similar to those found in the alpha-fibrous proteins, such as myosin . Overexpression of this domain in Escherichia coli resulted in the formation of an unusual striated protein lattice that filled the cells . We speculate on the role that this novel protein could play in gliding motility. Neurosci Res, 2000 Sep, 38(1), 71 - 83 Durations and frequencies of free locomotion in wild type and GABAergic mutants of Caenorhabditis elegans; Shingai R; We investigated how much time wild-type Caenorhabditis elegans (Bristol N2) nematodes and the GABA-deficient unc25 mutant and the vesicular GABA transporter-deficient unc47 mutant spent moving . The worms were allowed to move freely on the surface of agarose plates either with or without the food bacterium OP50 . We identified forward movement, backward movement, resting and turns by watching images on video and computer displays . Forward movement lasted longer and rests were briefer without, than with, bacteria . Frequency distributions except for backward movement fitted a sum of two exponential functions . The duration of backward movement was not strongly influenced by exposure to bacteria, whereas the frequency of backward movements increased in their presence . The duration of forward movement of unc25 nematodes had no long component, thus differing from that of N2 and unc47 strain nematodes in treatments with and without bacteria . The durations of resting in these mutants were much longer than in the N2 strain, especially in the absence of bacteria . The turn frequency of unc47 nematodes had a higher short component than that of the wild type N2 and unc25 nematodes, in the absence of bacteria . A neural network model is discussed in conjunction with the features of mutants and current knowledge of GABAergic neural transmission. Rev Med Panama, 1998 Jan-May, 23(1), 28 - 31 {Helicobacter pylori infection in children without dyspepsia in Curundu and Parque Lefevre}; Halphen GM et al.; A study of seroprevalence of Helicobacter pylori determined by ELISA IgG, was conducted in 83 consecutive healthy children . The majority of the children (55%) had the bacterium . Seropositivity was demonstrated in 55% of the age group 0-5 years old, in 47% of 6-10, and in 67%, of the group 11 to 15 . Of the children without sanitary inside their homes 86% were seropositive, versus 47% of the children with sanitary in their homes. J Agric Food Chem, 2000 Sep, 48(9), 4428 - 31 Residues of spinosad in meat, milk, and eggs; Rutherford BS et al.; Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and has a high level of activity against insects that infest a variety of crops . Dairy and poultry feeding studies were conducted to determine the magnitude of spinosad residues in animal products that would result from the consumption of typical feed commodities containing residues of spinosad . Dairy cows were dosed for 28 days with spinosad at rates equivalent to 0, 1, 3, and 10 microg/g in the diet . Chicken hens were dosed for 42 days with spinosad at rates equivalent to 0, 0.1, 0.3, 1, and 5 microg/g in the diet . Milk, eggs, and tissue samples were analyzed by high-performance liquid chromatography and/or immunoassay methods . Spinosad residues occurred in all of the sample types but were lowest in eggs, skim milk, and lean meat and were highest in the fat. Schweiz Med Wochenschr, 2000 Jul 1, 130(26), 984 - 7 {Helicobacter pylori and Meckel's diverticulum}; Groebli Y et al.; One quarter of Meckel's diverticula are covered by ectopic gastric mucosa and many may present histological inflammatory changes . Helicobacter pylori grows preferentially on an acid ground but has been found in different parts of the gastrointestinal tract . A prior hypothesis of a pathogenic role for this bacterium in some of Meckel's diverticula with ectopic mucosa is not confirmed by this study covering 21 cases. Infect Immun, 2000 Oct, 68(10), 5979 - 90 Structural and functional lesions in brush border of human polarized intestinal Caco-2/TC7 cells infected by members of the Afa/Dr diffusely adhering family of Escherichia coli; Peiffer I et al.; Diffusely adhering Escherichia coli (DAEC) strains expressing F1845 fimbrial adhesin or Dr hemagglutinin belonging to the Afa/Dr family of adhesins infect cultured polarized human intestinal cells through recognition of the brush border-associated decay-accelerating factor (DAF; CD55) as a receptor . The wild-type Afa/Dr DAEC strain C1845 has been shown to induce brush border lesions by an adhesin-dependent mechanism triggering apical F-actin rearrangements . In the present study, we undertook to further characterize cell injuries following the interaction of wild-type Afa/Dr DAEC strains C1845 and IH11128 expressing fimbrial F1845 adhesin and Dr hemagglutinin, respectively, with polarized, fully differentiated Caco-2/TC7 cells . In both cases, bacterium-cell interaction was followed by rearrangement of the major brush border-associated cytoskeletal proteins F-actin, villin, and fimbrin, proteins which play a pivotal role in brush border assembly . In contrast, distribution of G-actin, actin-depolymerizing factor, and tubulin was not modified . Using draE mutants, we found that a mutant in which cysteine replaces aspartic acid at position 54 conserved binding capacity but failed to induce F-actin disassembly . Accompanying the cytoskeleton injuries, we found that the distribution of brush border-associated functional proteins sucrase-isomaltase (SI), dipeptidylpeptidase IV (DPPIV), glucose transporter SGLT1, and fructose transporter GLUT5 was dramatically altered . In parallel, SI and DPPIV enzyme activity decreased. Infect Immun, 2000 Oct, 68(10), 5970 - 8 Transcriptional activation of the htrA (High-temperature requirement A) gene from Bartonella henselae; Resto-Ruiz SI et al.; Bacterial htrA genes are typically activated as part of the periplasmic stress response and are dependent on the extracytoplasmic sigma factor rpoE . A putative promoter region, P1, of the sigma(E)-type heat-inducible promoters has previously been identified upstream of the htrA gene of Bartonella henselae . Further analysis of the htrA mRNA by primer extension demonstrated that transcription initiates from P1 and a second region downstream of P1 . This second promoter region, termed P2, had no sequence identity to sigma(E)-type heat-inducible promoters . Promoter regions were cloned individually and in tandem into pANT3 upstream of a promoterless version of the green fluorescent protein (GFP) gene (gfpmut3) and transformed into B . henselae by electroporation . The contiguous promoter region containing both P1 and P2 were necessary for the optimal transcriptional activation of the htrA gene . Promoter activity at 37 degrees C was distinctively higher than at 27 degrees C . However, thermal induction at 47 degrees C did not increase expression of gfpmut3 . Invasion of human microvascular endothelial cells (HMEC-1) by B . henselae resulted in the formation of well-defined vacuoles containing clusters of bacteria exhibiting marked expression of gfpmut3 transcribed from the P1-P2 region . In addition, a moderate yet significant increase in the ratio of bacterial GFP to DNA was detected for intracellular bacteria compared to extracellular bacteria, indicating upregulation of htrA upon invasion of HMEC-1 . The activation of specific genes in the intracellular environment may help us better understand the novel pathogenic mechanisms used by this bacterium. Infect Immun, 2000 Oct, 68(10), 5943 - 52 Isolation and characterization of mini-Tn5Km2 insertion mutants of enterohemorrhagic Escherichia coli O157:H7 deficient in adherence to Caco-2 cells; Tatsuno I et al.; Adherence of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelium is essential for initiation of the infection . To identify genes involved in adherence, an EHEC O157:H7 strain (O157Sakai) was mutagenized by mini-Tn5Km2, where Km refers to kanamycin resistance, and 4,677 insertion mutants were screened for their ability to form microcolonies (MC) on Caco-2 cells . The less adherent mutants were divided into three groups: those with no adherent ability (designated as class 1 mutants, n = 10), those less adherent than the wild type (class 2 mutants, n = 16), and those unable to form MC but which adhered in a diffuse manner (class 3 mutants, n = 1) . The sites of insertion in class 1 mutants were all found within genes of the locus for enterocyte effacement (LEE) thought to be required for type III protein secretion . Indeed, the class 1 mutants failed to secrete type III secreted proteins such as EspA and Tir into the culture medium . The insertions in class 2 mutants were outside the LEE, and all the mutants except one were able to secrete type III proteins into the culture medium . The class 3 mutant had the insertion in the tir gene in the LEE and was deficient in Tir and intimin expression, suggesting that in the absence of intimin-Tir, O157Sakai can still adhere to Caco-2 cells but in a diffused manner . This was confirmed by construction of a nonpolar eae (encoding intimin) mutant . Examination of the eae mutant together with O157Sakai and one of the class 1 mutants for the ability to form MC revealed that EHEC initially adhered diffusely at 1.5 h after infection . Following washing out of the nonadherent bacteria, while wild-type EHEC bacteria developed MC for another 2 to 3 h on Caco-2 cells, the eae mutant diffusely adhered throughout the infection without forming MC . MC with O157Sakai but not the diffusely adherent eae mutant could evoke F-actin condensation beneath the bacterium . Our results suggest that EHEC encodes additional adherence-associated loci and that the type III secreted proteins are involved in the initial diffuse adherence, while the intimin-Tir interaction is required for the subsequent development of MC. Spectrochim Acta A Mol Biomol Spectrosc, 2000 Sep, 56A(10), 2001 - 10 Electronic energy transfer involving carotenoid pigments in chlorosomes of two green bacteria: Chlorobium tepidum and Cholroflexus aurantiacus; Melo TB et al.; Electronic energy transfer processes in chlorosomes isolated from the green sulphur bacterium Chlorobium tepidum and from the green filamentous bacterium Chloroflexus aurantiacus have been investigated . Steady-state fluorescence excitation spectra and time-resolved triplet-minus-singlet (TmS) spectra, recorded at ambient temperature and under non-reducing or reducing conditions, are reported . The carotenoid (Car) pigments in both species transfer their singlet excitation to bacteriochlorophyll c (BChlc) with an efficiency which is high (between 0.5 and 0.8) but smaller than unity; BChlc and bacteriochlorophyll a (BChla) transfer their triplet excitation to the Car's with nearly 100% efficiency . The lifetime of the Car triplet states is approximately 3 micros, appreciably shorter than that of the Car triplets in the light-harvesting complex II (LHCII) in green plants and in other antenna systems . In both types of chlorosomes the yield of BChlc triplets (as judged from the yield of the Car triplets) remains insensitive to the redox conditions . In notable contrast the yield of BChlc singlet emission falls, upon a change from reducing to non-reducing conditions, by factors of 4 and 35 in Cfx . aurantiacus and Cb . tepidum, respectively . It is possible to account for these observations if one postulates that the bulk of the BChlc triplets originate either from a large BChlc pool which is essentially non-fluorescent and non-responsive to changes in the redox conditions, or as a result of a process which quenches BChlc singlet excitation and becomes more efficient under non-reducing conditions . In chlorosomes from Cfx . aurantiacus whose Car content is lowered, by hexane extraction, to 10% of the original value, nearly one-third of the photogenerated BChlc triplets still end up on the residual Car pigments, which is taken as evidence of BChlc-to-BChlc migration of triplet excitation; the BChlc triplets which escape rapid static quenching contribute a depletion signal at the long-wavelength edge of the Qy absorption band, indicating the existence of at least two pools of BChlc. Arch Microbiol, 2000 Jul-Aug, 174(1-2), 50 - 8 Phylogenetic affiliation of the bacteria that constitute phototrophic consortia; Frostl JM et al.; The phylogenetic affiliation of epibionts occurring in three morphologically distinct types of green-colored phototrophic consortia was investigated . Intact consortia of the types "Chlorochromatium aggregatum", "C . glebulum", and a third previously undescribed type, tentatively named "C . magnum" were mechanically separated from accompanying bacteria by either micromanipulation or by chemotactic accumulation in sulfide-containing capillaries . A 540-base-pair-long fragment of the 16S rRNA gene of the epibionts was amplified employing PCR primers specific for green sulfur bacteria . DNA fragments were separated by denaturing gradient gel electrophoresis and subsequently sequenced . The results of this phylogenetic analysis indicated that the symbiotic epibionts, together with only a few free-living strains, form a cluster within the green sulfur bacterial radiation which is only distantly related to the majority of known representatives of this phylum . Consortia with identical morphology but different origin exhibited significant differences in their partial 16S rRNA gene sequences, which could be confirmed by analysis of the 16S rRNA secondary structure . The phylogenetic affiliation of the chemotrophic central rod-shaped bacterium of "C . aggregatum" and "C . magnum" was analyzed by fluorescent in situ hybridization . According to our results and contrary to earlier assumptions, the central bacterium is a member of the beta-subgroup of the Proteobacteria. Arch Microbiol, 2000 Jul-Aug, 174(1-2), 18 - 27 Rhodobaca bogoriensis gen . nov . and sp . nov., an alkaliphilic purple nonsulfur bacterium from African Rift Valley soda lakes; Milford AD et al.; From enrichment cultures established for purple nonsulfur bacteria using water and sediment samples from Lake Bogoria and Crater Lake, two soda lakes in the African Rift Valley, three strains of purple nonsulfur bacteria were isolated; strain LBB1 was studied in detail . Cells of strain LBB1 were motile and spherical to rod-shaped, suggesting a relationship to Rhodobacter or Rhodovulum species, and the organism was capable of both phototrophic and chemotrophic growth on a wide variety of organic compounds . Phototrophically grown cultures were yellow to yellow-brown in color and grew optimally at pH 9 (pH range 7.5-10) and 1% NaCl (range 0-10%) . In physiological studies of strain LBB1, neither photoautotrophy (H2- or sulfide-dependent) nor nitrogen fixation was observed . Absorption spectra revealed that all three strains contained bacteriochlorophyll a and carotenoids of the spheroidene pathway and synthesized only a light-harvesting (LH) I-type photosynthetic antenna complex . Electron microscopy of cells of strain LBB1 revealed a vesicular intracytoplasmic membrane system, although only a few vesicles were observed per cell . The G+C content of strain LBB1 DNA was 59 mol%, significantly lower than that of known Rhodobacter and Rhodovulum species, and its phylogeny as determined by ribosomal RNA gene sequencing placed it within the Rhodobacter/Rhodovulum clade yet distinct from all described species of either of these genera . The unique assemblage of properties observed in strain LBB1 warrants its inclusion in a new genus of purple nonsulfur bacteria and the name Rhodobaca bogoriensis is proposed herein, the genus name reflecting morphological characteristics and the species epithet referring to the habitat. J Econ Entomol, 2000 Aug, 93(4), 1269 - 75 Insecticide resistance and cross-resistance in the house fly (Diptera: Muscidae); Liu N et al.; A house fly strain, ALHF, was collected from a poultry farm in Alabama after a control failure with permethrin, and further selected in the laboratory with permethrin for five generations . The level of resistance to permethrin in ALHF was increased rapidly from an initial 260-fold to 1,800-fold after selection . Incomplete suppression of permethrin resistance by piperonyl butoxide (PBO) and S,S,S,-tributylphosphorotrithioate (DEF) reveals that P450 monooxygenase- and hydrolase-mediated detoxication, and one or more additional mechanisms are involved in resistance to permethrin . The ALHF strain showed a great ability to develop resistance or cross-resistance to different insecticides within and outside the pyrethroid group including some relatively new insecticides . Resistance to beta-cypermethrin, cypermethrin, deltamethrin, and propoxur (2,400-4,200-, 10,000-, and > 290-fold, respectively, compared with a susceptible strain, aabys) in ALHF house flies was partially or mostly suppressed by PBO and DEF, indicating that P450 monooxygenases and hydrolases are involved in resistance to these insecticides . Partial reduction in resistance with PBO and DEF implies that multiresistance mechanisms are responsible for resistance . Fifteen- and more than fourfold resistance and cross-resistance to chlorpyrifos and imidacloprid, respectively, were not effected by PBO or DEF, indicating that P450 monooxygenases and hydrolases are not involved in resistance to these two insecticides . Forty-nine-fold cross-resistance to fipronil was mostly suppressed by PBO and DEF, revealing that monooxygenases are a major mechanism of cross-resistance to fipronil . Multiresistance mechanisms in the ALHF house fly strain, however, do not confer cross-resistance to spinosad, a novel insecticide derived from the bacterium Saccharopolyspora spinosa . Thus, we propose that spinosad be used as a potential insecticide against house fly pests, especially resistant flies. FEBS Lett, 2000 Aug 18, 479(3), 111 - 7 Characterization of the AfaD-like family of invasins encoded by pathogenic Escherichia coli associated with intestinal and extra-intestinal infections; Garcia MI et al.; The afimbrial adhesive sheath, encoded by the afa-3 gene cluster, is composed of two proteins with different roles in bacterium-HeLa cell interactions . AfaE is required for adhesion and AfaD for internalization . In this study, we found that the AfaD invasin was structurally and functionally conserved among human afa-expressing strains, independently of AfaE subtype and clinical origin of the Escherichia coli isolate . The AggB protein from enteroaggregative E . coli was also found to be an AfaD-related invasin . These data suggest that AfaD is the prototype of a family of invasins encoded by adhesion-associated operons in pathogenic E . coli. Curr Gastroenterol Rep, 2000 Aug, 2(4), 299 - 304 Toward a new understanding of Whipple's disease; Flemmer MC et al.; Since the first successful antibiotic treatment of Whipple's disease in 1952, many breakthroughs have occurred in the diagnosis and treatment of this disease that was once thought fatal . This article provides a historic overview and highlights recent encouraging discoveries regarding this underdiagnosed disease, including the use of polymerase chain reaction techniques and the recent cultivation of the Tropheryma whippelii bacterium. Science, 2000 Sep 8, 289(5485), 1724 - 30 Molecular evidence for the early evolution of photosynthesis; Xiong J et al.; The origin and evolution of photosynthesis have long remained enigmatic due to a lack of sequence information of photosynthesis genes across the entire photosynthetic domain . To probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium Chlorobium tepidum and the green nonsulfur bacterium Chloroflexus aurantiacus . A total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/porphyrin biosynthesis, carotenoid biosynthesis, and photosynthetic electron transfer were identified in about 100 kilobase pairs of genomic sequence . Phylogenetic analyses of multiple magnesium-tetrapyrrole biosynthesis genes using a combination of distance, maximum parsimony, and maximum likelihood methods indicate that heliobacteria are closest to the last common ancestor of all oxygenic photosynthetic lineages and that green sulfur bacteria and green nonsulfur bacteria are each other's closest relatives . Parsimony and distance analyses further identify purple bacteria as the earliest emerging photosynthetic lineage . These results challenge previous conclusions based on 16S ribosomal RNA and Hsp60/Hsp70 analyses that green nonsulfur bacteria or heliobacteria are the earliest phototrophs . The overall consensus of our phylogenetic analysis, that bacteriochlorophyll biosynthesis evolved before chlorophyll biosynthesis, also argues against the long-held Granick hypothesis. Mol Gen Mikrobiol Virusol, 2000, (3), 7 - 12 {Species- and genus-specific antigenic epitopes of Francisella tularensis lipopolysaccharides}; Pavlovich NV et al.; Lipopolysaccharide (LPS) antigenic epitopes of natural virulent and isogenic avirulent Francisella tularensis strains and other species of the Francisella genus (F . novicida, F . novicida-like, and F . philomiragia) were studied by dot and immunoblotting . Polyclonal rabbit and human sera to virulent F . tularensis strains and monoclonal antibodies to F . tularensis LPS O-side chain were used for detecting species- and genus-specific LPS epitopes . Typical virulent F . tularensis strains produce two types of S-LPS with different antigenic specificity simultaneously . Antigenic determinants of two LPS types were located in LPS O-polysaccharide but not in the core oligosaccharide . The epitopes of the first LPS type were characterized by species specificity for F . tularensis in contrast to determinants of the second LPS type, which had epitopes common with F . novicida . Cross exhaustion of human and rabbit antitularemic sera by F . tularensis and F . novicida LPS showed that F . novicida LPS molecules contained at least two epitopes--highly specific for F . novicida and common with the second type of F . tularensis LPS . The immune response of rabbits and humans to F . tularensis LPS epitopes was different in principle . Sera from rabbits immunized with vaccine and virulent F . tularensis strains contained antibodies "recognizing" antigenic epitopes of two S-LPS forms of the bacterium: type 1 species-specific (in high titers) and type 2 epitopes common with F . novicida LPS (in low titers) . In addition to these, sera from patients with tularemia contain immunoglobulins to species-specific epitopes of F . novicida LPS in high titers . Experiments on avirulent mutants showed that in some cases attenuation of F . tularensis can involve loss of species-specific LPS form, while S-LPS with epitopes common with F . novicida LPS will be retained . The difference in specificity of human and rabbit antitularemic antibodies is due to individual features in the host immune system. Mol Microbiol, 2000 Aug, 37(4), 913 - 25 Three temporal classes of gene expression during the Chlamydia trachomatis developmental cycle; Shaw EI et al.; The obligate intracellular bacterium Chlamydia trachomatis has a unique developmental cycle that involves functionally and morphologically distinct cell types adapted for extracellular survival and intracellular multiplication . Infection is initiated by an environmentally resistant cell type called an elementary body (EB) . Over the first several hours of infection, EBs differentiate into a larger replicative form, termed the reticulate body (RB) . Late in the infectious process, RBs asynchronously begin to differentiate back to EBs, which accumulate within the lumen of the inclusion until released from the host cell for subsequent rounds of infection . In an effort to characterize temporal gene expression in relation to the chlamydial developmental cycle, we have used quantitative-competitive polymerase chain reaction (QC-PCR) and reverse transcription (RT)-PCR techniques . These analyses demonstrate that C . trachomatis double their DNA content every 2-3 h, with synthesis beginning between 2 and 4 h after infection . We determined the onset of transcription of specific temporal classes of developmentally expressed genes . RT-PCR analysis was performed on several genes encoding key enzymes or components of essential biochemical pathways and functions . This comparison encompassed approximately 8% of open reading frames on the C . trachomatis genome . In analysis of total RNA samples harvested at 2, 6, 12 and 20 h after infection, using conditions under which a single chlamydial transcript per infected cell is detected, three major temporal classes of gene expression were resolved . Initiation of transcription appears to occur in three temporal classes which we have operationally defined as: early, which are detected by 2 h after infection during the germination of EBs to RBs; mid-cycle, which appear between 6 and 12 h after infection and represent transcripts expressed during the growth and multiplication of RBs; or late, which appear between 12 and 20 h after infection and represent those genes transcribed during the terminal differentiation of RBs to EBs . Collectively, the data suggest that chlamydial early gene functions are weighted toward initiation of macromolecular synthesis and the establishment of their intracellular niche by modification of the inclusion membrane . Surprisingly, representative enzymes of intermediary metabolism and structural proteins do not appear to be transcribed until 10-12 h after infection; coinciding with the onset of observed binary fission of RBs . Late gene functions appear to be predominately those associated with the terminal differentiation of RBs back to EBs. Extremophiles, 2000 Aug, 4(4), 189 - 200 Thermotoga maritima AglA, an extremely thermostable NAD+-, Mn2+-, and thiol-dependent alpha-glucosidase; Raasch C et al.; The gene for the alpha-glucosidase AglA of the hyperthermophilic bacterium Thermotoga maritima MSB8, which was identified by phenotypic screening of a T . maritima gene library, is located within a cluster of genes involved in the hydrolysis of starch and maltodextrins and the uptake of maltooligosaccharides . According to its primary structure as deduced from the nucleotide sequence of the gene, AglA belongs to family 4 of glycosyl hydrolases . The enzyme was recombinantly expressed in Escherichia coli, purified, and characterized . The T . maritima alpha-glucosidase has the unusual property of requiring NAD+ and Mn2+ for activity . Co2+ and Ni2+ also activated AglA, albeit less efficiently than Mn2+ . T . maritima AglA represents the first example of a maltodextrin-degrading alpha-glucosidase with NAD+ and Mn2+ requirement . In addition, AglA activity depended on reducing conditions . This third requirement was met by the addition of dithiothreitol (DTT) or beta-mercaptoethanol to the assay . Using gel permeation chromatography, T . maritima AglA behaved as a dimer (two identical 55-kDa subunits), irrespective of metal depletion or metal addition, and irrespective of the presence or absence of NAD+ or DTT . The enzyme hydrolyzes maltose and other small maltooligosaccharides but is inactive against the polymeric substrate starch . AglA is not specific with respect to the configuration at the C-4 position of its substrates because glycosidic derivatives of D-galactose are also hydrolyzed . In the presence of all cofactors, maximum activity was recorded at pH 7.5 and 90 degrees C (4-min assay) . AglA is the most thermoactive and the most thermostable member of glycosyl hydrolase family 4 . When incubated at 50 degrees C and 70 degrees C, the recombinant enzyme suffered partial inactivation during the first hours of incubation, but thereafter the residual activity did not drop below about 50% and 20% of the initial value, respectively, within a period of 48 h. Nurse Pract, 2000 Aug, 25(8), 40, 43 - 4, 47-8 passim; quiz 54-5 Helicobacter pylori: an emerging infectious disease; McManus TJ; Helicobacter pylori is the most common chronic bacterial infection in the world, colonizing the stomachs of more than 50% of the human population . The discovery of this bacterium has changed the concept of care and management for peptic ulcer disease, mucosa-associated lymphomas, gastritis, and gastric carcinoma . Although the mode of transmission is not definitively known, person-to-person contact is suspected . This article discusses H . pylori, the associated clinical syndromes and diseases, risk factors, and current pharmacologic management. J Clin Microbiol, 2000 Sep, 38(9), 3399 - 403 Characterization of Actinomyces isolates from infected root canals of teeth: description of Actinomyces radicidentis sp . nov; Collins MD et al.; Two strains of a previously undescribed Actinomyces-like bacterium were recovered in pure culture from infected root canals of teeth . Analysis by biochemical testing and polyacrylamide gel electrophoresis of whole-cell proteins indicated that the strains closely resembled each other phenotypically but were distinct from previously described Actinomyces and Arcanobacterium species . Comparative 16S rRNA gene-sequencing studies showed the bacterium to be a hitherto unknown subline within a group of Actinomyces species which includes Actinomyces bovis, the type species of the genus . Based on phylogenetic and phenotypic evidence, we propose that the unknown bacterium isolated from human clinical specimens be classified as Actinomyces radicidentis sp . nov . The type strain of Actinomyces radicidentis is CCUG 36733. Biophys J, 2000 Sep, 79(3), 1561 - 72 High-pressure and stark hole-burning studies of chlorosome antennas from Chlorobium tepidum; Wu HM et al.; Results from high-pressure and Stark hole-burning experiments on isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum are presented, as well as Stark hole-burning data for bacteriochlorophyll c (BChl c) monomers in a poly(vinyl butyral) copolymer film . Large linear pressure shift rates of -0.44 and -0.54 cm(-1)/MPa were observed for the chlorosome BChl c Q(y)-band at 100 K and the lowest Q(y)-exciton level at 12 K, respectively . It is argued that approximately half of the latter shift rate is due to electron exchange coupling between BChl c molecules . The similarity between the above shift rates and those observed for the B875 and B850 BChl a rings of the light-harvesting complexes of purple bacteria is emphasized . For BChl c monomer, fDeltamu++ = 0.35 D, where Deltamu+ is the dipole moment change for the Q(y) transition and f is the local field correction factor . The data establish that Deltamu+ is dominated by the matrix-induced contribution . The change in polarizability (Deltaalpha) for the Q(y) transition of the BChl c monomer is estimated at 19 A(3), which is essentially identical to that of the Chl a monomer . Interestingly, no Stark effects were observed for the lowest exciton level of the chlorosomes (maximum Stark field of 10(5) V/cm) . Possible explanations for this are given, and these include consideration of structural models for the chlorosome BChl c aggregates. Biophys J, 2000 Sep, 79(3), 1171 - 9 Cumulant analysis of charge recombination kinetics in bacterial reaction centers reconstituted into lipid vesicles; Palazzo G et al.; The kinetics of charge recombination between the primary photoxidized donor (P(+)) and the secondary reduced quinone acceptor (Q(B)(-)) have been studied in reaction centers (RCs) from the purple photosynthetic bacterium Rhodobacter sphaeroides incorporated into lecithin vesicles containing large ubiquinone pools over the temperature range 275 K </= T </= 307 K . To account for the non-exponential kinetics of P(+) re-reduction observed following a flash, a new approach has been developed, based on the following assumptions: 1) the exchange of quinone between different vesicles is negligible; 2) the exchange of quinone between the Q(B) site of the RC and the quinone pool within each single vesicle is faster than the return of the electron from the primary reduced acceptor Q(A)(-) to P(+); 3) the size polydispersity of proteoliposomes and the distribution of quinone molecules among them result in a quinone concentration distribution function, P(Q) . The first and second moments of P(Q) have been evaluated from the size distribution of proteoliposomes probed by quasi-elastic light scattering (mean radius, <R> = (50 +/- 15) nm) . Following these premises, we describe the kinetics of P(+)Q(B)(-) recombination with a truncated cumulant expansion and relate it to P(Q) and to the free energy changes for Q(A)(-)Q(B) --> Q(A)Q(B)(-) electron transfer (DeltaG(AB)(o)) and for quinone binding (DeltaG(bind)(o)) at Q(B) . The model accounts well for the temperature and quinone dependence of the charge recombination kinetics, yielding DeltaG(AB)(o) = -7.67 +/- 0.05 kJ mol(-1) and DeltaG(bind)(o) = -14.6 +/- 0.6 kJ mol(-1) at 298 K. Appl Microbiol Biotechnol, 2000 Aug, 54(2), 206 - 11 Changes in the physiological and agricultural characteristics of peat-based Bradyrhizobium japonicum inoculants after long-term storage; Revellin C et al.; Commercial soybean inoculants processed with sterilised peat and stored at 20 degrees C for 1-8 years were used as experimental materials to assess the changes in the physiological activity of Bradyrhizobium japonicum after storage . Viable counts decreased and physiological characteristics of the bacterium changed during storage, with an increase in the time taken for colony appearance on a medium without yeast extract, an increase in the lag time for nodule appearance on soybean grown in glass tubes and a decrease in survival on seeds . All the inoculants produced a significant increase in grain yield in a field experiment . The percentage of efficient cells in the field (relative to the plate counts) decreased as the length of storage increased . These results suggest that the physiological activity of B . japonicum cells changes after storage . Practical implications for inoculant quality control are discussed. J Biol Inorg Chem, 2000 Aug, 5(4), 505 - 13 The 1.9 A crystal structure of the "as isolated" rubrerythrin from Desulfovibrio vulgaris: some surprising results; Sieker LC et al.; Rubrerythrin is a non-heme iron dimeric protein isolated from the sulfate-reducing bacterium Desulfovibrio vulgaris . Each monomer has one mononuclear iron center similar to rubredoxin and one dinuclear metal center similar to hemerythrin or ribonucleotide reductase . The 1.88 A X-ray structure of the "as isolated" molecule and a uranyl heavy atom derivative have been solved by molecular replacement techniques . The resulting model of the native "as isolated" molecule, including 164 water molecules, has been refined giving a final R factor of 0.197 (R(free) = 0.255) . The structure has the same general protein fold, domain structure, and dimeric interactions as previously found for rubrerythrin {1, 2}, but it also has some interesting undetected differences at the metal centers . The refined model of the protein structure has a cis peptide between residues 78 and 79 . The Fe-Cys4 center has a previously undetected strong seventh N-H...S hydrogen bond in addition to the six N-H...S bonds usually found in rubredoxin . The dinuclear metal center has a hexacoordinate Fe atom and a tetracoordinate Zn atom . Each metal is coordinated by a GluXXHis polypeptide chain segment . The Zn atom binds at a site distinctly different from that found in the structure of a diiron rubrerythrin . Difference electron density for the uranyl derivative shows an extremely large peak adjacent to and replacing the Zn atom, indicating that this particular site is capable of binding other atoms . This feature/ability may give rise to some of the confusing activities ascribed to this molecule. Appl Environ Microbiol, 2000 Sep, 66(9), 4161 - 7 Plant genome complexity may be a factor limiting in situ the transfer of transgenic plant genes to the phytopathogen Ralstonia solanacearum; Bertolla F et al.; The development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment . Ralstonia solanacearum is a plant pathogen that is also a naturally transformable bacterium that can develop the competence state during infection of its host . We have attempted to determine whether this bacterium could become the recipient of plant genes . We initially demonstrated that plant DNA was released close to the infecting bacteria . We constructed and tested various combinations of transgenic plants and recipient bacteria to show that the effectiveness of such transfers was directly related to the ratio of the complexity of the plant genome to the number of copies of the transgene. Appl Environ Microbiol, 2000 Sep, 66(9), 4136 - 8 Starvation alters the apparent half-saturation constant for methane in the type II methanotroph Methylocystis strain LR1; Dunfield PF et al.; When cells of a type II methanotrophic bacterium (Methylocystis strain LR1) were starved of methane, both the K(m(app)) and the V(max(app)) for methane decreased . The specific affinity (a(o)(s)) remained nearly constant . Therefore, the decreased K(m(app)) in starved cells was probably not an adjustment to better utilize low-methane concentrations. Appl Environ Microbiol, 2000 Sep, 66(9), 3743 - 9 Direct and Fe(II)-mediated reduction of technetium by Fe(III)-reducing bacteria; Lloyd JR et al.; The dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens reduced and precipitated Tc(VII) by two mechanisms . Washed cell suspensions coupled the oxidation of hydrogen to enzymatic reduction of Tc(VII) to Tc(IV), leading to the precipitation of TcO(2) at the periphery of the cell . An indirect, Fe(II)-mediated mechanism was also identified . Acetate, although not utilized efficiently as an electron donor for direct cell-mediated reduction of technetium, supported the reduction of Fe(III), and the Fe(II) formed was able to transfer electrons abiotically to Tc(VII) . Tc(VII) reduction was comparatively inefficient via this indirect mechanism when soluble Fe(III) citrate was supplied to the cultures but was enhanced in the presence of solid Fe(III) oxide . The rate of Tc(VII) reduction was optimal, however, when Fe(III) oxide reduction was stimulated by the addition of the humic analog and electron shuttle anthaquinone-2,6-disulfonate, leading to the rapid formation of the Fe(II)-bearing mineral magnetite . Under these conditions, Tc(VII) was reduced and precipitated abiotically on the nanocrystals of biogenic magnetite as TcO(2) and was removed from solution to concentrations below the limit of detection by scintillation counting . Cultures of Fe(III)-reducing bacteria enriched from radionuclide-contaminated sediment using Fe(III) oxide as an electron acceptor in the presence of 25 microM Tc(VII) contained a single Geobacter sp . detected by 16S ribosomal DNA analysis and were also able to reduce and precipitate the radionuclide via biogenic magnetite . Fe(III) reduction was stimulated in aquifer material, resulting in the formation of Fe(II)-containing minerals that were able to reduce and precipitate Tc(VII) . These results suggest that Fe(III)-reducing bacteria may play an important role in immobilizing technetium in sediments via direct and indirect mechanisms. Protein Eng, 2000 Aug, 13(8), 593 - 601 Characterization of function and activity of domains A, B and C of xylanase C from Fibrobacter succinogenes S85; Marrone L et al.; Xylanase C from the ruminant bacterium Fibrobacter succinogenes is comprised of two catalytic domains, A and B, and a third domain, C, of unknown function . The DNA coding for domains A and B of xylanase C were separately cloned and expressed in Escherichia coli as fusion proteins with glutathione-S:-transferase . The fusion proteins were isolated by affinity chromatography on glutathione-Sepharose 4B, cleaved with thrombin and the released xylanase C catalytic domains A and B were purified to apparent homogeneity by anion-exchange chromatography on Mono Q . Electrospray mass spectrometry provided a molecular mass of 27 818 Da (expected, 27 820 Da) for domain B . The pH and temperature optima for activity of domain B on oat spelt xylan were 5.0 and 52 degrees C, respectively . A kinetic analysis of the activity of the catalytic domain A on oat spelt xylan, birch wood xylan and xylooligomers at pH 6.5 and 37 degrees C provided data significantly different to those obtained previously with a protease-derived form of the enzyme {Zhu et al . (1994) J . Bacteriol . 176, 3885-3894} . The isolated domain A was more active on barley-glucan than the protease-derived form and its affinity for birch wood xylan was enhanced resulting in greater overall catalytic efficiency as reflected by k(cat)/K:(M) values . Likewise, significant differences in the Michaelis-Menten parameters K:(M), k(cat) and k(cat)/K:(M) were obtained with domain B compared with values previously reported with this domain attached to domain C . In general, the presence of domain C appeared to decrease the overall efficiency of domain B 7- and 36-fold with birch wood xylan and xylopentaose as substrates, respectively, as reflected by values of k(cat)/K:(M) . The removal of domain C also affected the mode of action of domain B such that it more closely resembled that of catalytic domain A . However, no change in either pH and temperature optima or stability were found with domain B compared with the combined domains B and C . The function of domain C remains unknown, but hydrophobic cluster analysis indicated that it may belong to a class of dockerin domains involved in the protein-protein interactions of cellulolytic and xylanolytic complexes. Protein Eng, 2000 Aug, 13(8), 589 - 92 Phages from landscape libraries as substitute antibodies; Petrenko VA et al.; In 'landscape' phage, as in traditional phage-display constructs, foreign peptides or proteins are fused to coat proteins on the surface of a filamentous phage particle . Unlike conventional constructs, however, each virion displays thousands of copies of the peptide in a repeating pattern, subtending a major fraction of the viral surface . The phage body serves as an interacting scaffold to constrain the peptide into a particular conformation, creating a defined organic surface structure ('landscape') that varies from one phage clone to the next . By testing landscape libraries with three representative antigens (streptavidin from the bacterium Streptomyces avidinii, avidin from chicken egg white and beta-galactosidase from Escherichia coli) we have shown that landscape phages may be used as a new type of substitute antibodies-filaments that can bind protein and glycoprotein antigens with nanomolar affinities and high specificity . In many ways these substitute antibodies are more convenient than their natural immunoglobulin counterparts. Clin Ther, 2000 Mar, 22(3), 266 - 80; discussion 265 The proton-pump inhibitors: similarities and differences; Horn J; OBJECTIVE: This paper examines the clinical pharmacology of the proton-pump inhibitors (PPIs) and briefly reviews some comparative studies of these agents . BACKGROUND: PPIs have emerged as the treatment of choice for acid-related diseases, including gastroesophageal reflux disease (GERD) and peptic ulcer disease . Although these drugs-omeprazole, lansoprazole, pantoprazole, and rabeprazole-share a common structure (all are substituted benzimidazoles) and mode of action (inhibition of H+,K+-adenosine triphosphatase {ATPase}), each differs somewhat in its clinical pharmacology . RESULTS: In comparative clinical trials found in MEDLINE, PPIs administered once daily produced endoscopic evidence of healing in >90% of patients with duodenal ulcer after 4 weeks of treatment, in >90% of those with gastric ulcer after 6 weeks of treatment, and in >90% of those with ulcerative or erosive GERD after 8 weeks of treatment . Maintenance therapy with daily doses of a PPI has been shown to be an effective means of preventing GERD relapse . PPIs also inhibit the growth of Helicobacter pylori, now recognized as an important factor in peptic ulcer disease, and, when administered in combination with antibiotics, provide the best treatment for eradication of the bacterium . Rabeprazole has a more rapid onset of H+,K+-ATPase inhibition than the other PPIs and, compared with omeprazole, a greater effect on intragastric pH after the first dose . Omeprazole and lansoprazole have a greater potential for drug-drug interactions than do pantoprazole and rabeprazole . CONCLUSION: Although the individual PPIs have similar efficacy in many cases, differences between them should be considered when choosing a treatment regimen. Microbes Infect, 2000 Jul, 2(8), 979 - 80 'Infectious web'; Kotra LP et al.; Infections by Helicobacter pylori are responsible for duodenal and gastric ulcers and are a significant risk factor for the development of gastric adenocarcinoma . H . pylori was discovered in 1983, but many institutes in Canada, Europe, and the United States are already involved in programs to understand and treat the infections, as reflected by the growing number of internet sites devoted to this bacterium . Most AIDS patients and about 20% of children with acute lymphoblastic leukemia develop Pneumocystis carinii pneumoniae . Information on clinical symptoms and treatment, as well as the P . carinii genome sequencing project, are described at several web sites . Students and researchers wishing to understand the correlation between telomere length and AIDS may turn to web sites of the University of Colorado and Washington University School of Medicine for the latest on telomeres and telomerase, and their function in aging and cancer. Microbes Infect, 2000 Jul, 2(8), 867 - 75 Signal transduction in the protozoan host Hartmannella vermiformis upon attachment to Legionella pneumophila; Venkataraman C et al.; Intracellular replication of the Legionnaires' disease bacterium, Legionella pneumophila, within protozoa plays a major role in bacterial ecology and pathogenesis . Invasion of the protozoan host Hartmannella vermiformis by L . pneumophila is mediated by attachment to the Gal/GalNAc lectin receptor, which is similar to the beta(2) integrin transmembrane receptors of mammalian cells . Bacterial invasion is associated with induction of a protein tyrosine phosphatase (PTPase) activity in H . vermiformis that results in tyrosine dephosphorylation of the lectin receptor and several cytoskeletal proteins . In this report, we show that entry of L . pneumophila into H . vermiformis is not required to induce tyrosine dephosphorylation of one of the cytoskeletal proteins, paxillin . Tyrosine dephosphorylation of paxillin is mediated at the level of bacterial attachment to the lectin receptor, and is blocked by inhibiting bacterial attachment to the lectin receptor . Attachment of L . pneumophila to the lectin receptor is not mediated by the type IV pilus, which is one of the bacterial ligands involved in attachment to protozoa . Interestingly, the lectin receptor in resting H . vermiformis is associated with several phosphorylated proteins that are dissociated upon bacterial attachment and invasion . We show that the L . pneumophila-induced PTPase activity in H . vermiformis and the associated tyrosine dephosphorylation of host proteins can be mimicked by the cytoskeletal disrupting agent, cytochalasin D . Taken together, our data indicate that attachment of L . pneumophila to the lectin receptor of H . vermiformis induces a PTPase activity, tyrosine dephosphorylation of the lectin and cytoskeletal proteins, dissociation of the lectin from its associated phosphorylated proteins, and most probably disassembly of the cytoskeleton . This novel L . pneumophila-protozoa interaction may be a bacterial strategy to invade protozoa and to be trafficked into a replicative 'niche', or to block differentiation of the protozoan host into a cyst in which L . pneumophila cannot replicate. Scand J Infect Dis, 2000, 32(4), 427 - 30 Endocarditis caused by Stenotrophomonas maltophilia; Aydin K et al.; Stenotrophomonas maltophilia is frequently isolated from hospital environments . In recent years, it has been reported that this bacterium is causing hospital infections at increasing rates and is gaining importance because of its multiple resistance . Although it has been related to several infections, endocarditis caused by S . maltophilia is rarely encountered . In this case study, endocarditis in a 40-y-old man with a history of aortic valve replacement is presented . Blood cultures revealed S . maltophilia to be the aetiological agent, which showed multiresistance to various antibiotics . Ticarcillin-clavulanate and trimethoprim-sulfamethoxazole were used in the treatment. Mediators Inflamm, 2000, 9(2), 115 - 20 Th1 and Th2 cytokine profile in patients with early onset periodontitis and their healthy siblings; Bartova J et al.; Early onset periodontitis (EOP) is a chronic inflammatory periodontal disease with a strong genetic link affecting individuals aged 17 to 25 . In the familial studies we tested the hypothesis about the role of Th1 and Th2 cytokines in the pathogenesis of EOP disease . The study involved 6 individuals with EOP disease and their 6 siblings with healthy periodontium . Actinobacillus actinomycetemcomitans (A . a), a bacterium typical for EOP, was detected in all people studied . Th1 and Th2 cytokine production was measured after in vitro stimulation . Peripheral blood mononuclear cells (PBMC) were isolated and cultivated for 24 h and 7 days with PWM, A . a . or Escherichia coli . The levels of IL-4, IFN-gamma, IgA, IgG and IgM were measured by ELISA methods . After in vitro stimulation of PBMC, a significantly higher production of IL-4 and significantly lower production of IFN-gamma were found in the group of patients compared with their healthy siblings . The increased level of IL-4 in patients was in good agreement with an increased level of IgM after stimulation of lymphocytes with E . coli . These results support Seymour's hypothesis according to which patients with progressive disease primarily activate Th2 lymphocytes while non-susceptible individuals activate Th1 lymphocytes. Biochemistry, 2000 Aug 22, 39(33), 10172 - 6 Oxidation-reduction properties of disulfide-containing proteins of the Rhodobacter capsulatus cytochrome c biogenesis system; Setterdahl AT et al.; Oxidation-reduction titrations for the active-site disulfide/dithiol couples of the helX- and ccl2-encoded proteins involved in cytochrome c biogenesis in the purple non-sulfur bacterium Rhodobacter capsulatus have been carried out . The R . capsulatus HelX and Ccl2 proteins are predicted to function as part of a dithiol/disulfide cascade that reduces a disulfide on the apocytochromes c so that two cysteine thiols are available to form thioether linkages between the heme prosthetic group and the protein . Oxidation-reduction midpoint potential (E(m)) values, at pH 7.0, of -300 +/- 10 and -210 +/- 10 mV were measured for the HelX and Ccl2 (a soluble, truncated form of Ccl2) R . capsulatus proteins, respectively . Titrations of the disulfide/dithiol couple of a peptide designed to serve as a model for R . capsulatus apocytochrome c(2) have also been carried out, and an E(m) value of -170 +/- 10 mV was measured for the model peptide at pH 7.0 . E(m) versus pH plots for HelX, Ccl2, and the apocytochrome c(2) model peptide were all linear over the pH range from 5.0 to 8.0, with the -59 mV/pH unit slope expected for a reaction in which two protons are taken up for each disulfide that is reduced . These results provide thermodynamic support for the proposal that HelX reduces Ccl2 and that reduced Ccl2, in turn, serves as the reductant for the production of the two thiols of the CysXxxYyyCysHis heme-binding motif of the apocytochromes. Microbes Infect, 2000 Jun, 2(7), 829 - 35 Invasion and intracellular trafficking of Brucella abortus in nonphagocytic cells; Pizarro-Cerda J et al.; Brucella abortus is a facultative intracellular parasite that promotes its own internalization in nonphagocytic cells . The bacterium initially interacts with compartments of the early endocytic cascade, then rapidly segregates from this intracellular pathway and associates with the autophagocytic cascade . During the late stages of infection, Brucella proliferates within the endoplasmic reticulum of host cells. Microbes Infect, 2000 Jun, 2(7), 761 - 72 Phage infection of the obligate intracellular bacterium, Chlamydia psittaci strain guinea pig inclusion conjunctivitis; Hsia R et al.; The infectious cycle of phiCPG1, a bacteriophage that infects the obligate intracellular pathogen, Chlamydia psittaci strain Guinea Pig Inclusion Conjunctivitis, was observed using transmission electron microscopy of phage-hyperinfected, Chlamydia-infected HeLa cells . Phage attachment to extracellular, metabolically dormant, infectious elementary bodies and cointernalisation are demonstrated . Following entry, phage infection takes place as soon as elementary bodies differentiate into metabolically active reticulate bodies . Phage-infected bacteria follow an altered developmental path whereby cell division is inhibited, producing abnormally large reticulate bodies, termed maxi-reticulate bodies, which do not mature to elementary bodies . These forms eventually lyse late in the chlamydial developmental cycle, releasing abundant phage progeny in the inclusion and, upon lysis of the inclusion membrane, into the cytosol of the host cell . Structural integrity of the hyperinfected HeLa cell is markedly compromised at late stages . Released phage particles attach avidly to the outer leaflet of the outer membranes of lysed and unlysed Chlamydiae at different stages of development, suggesting the presence of specific phage receptors in the outer membrane uniformly during the chlamydial developmental cycle . A mechanism for phage infection is proposed, whereby phage gains access to replicating chlamydiae by attaching to the infectious elementary body, subsequently subverting the chlamydial developmental cycle to its own replicative needs . The implications of phage infection in the context of chlamydial infection and disease are discussed. Microbes Infect, 2000 Jun, 2(7), 727 - 36 Coinfection of fibroblasts with Coxiella burnetti and Toxoplasma gondii: to each their own; Sinai AP et al.; Intracellular pathogens have evolved distinct strategies to subvert host cell defenses . At diametrically opposed ends of the spectrum with regard to the host endosomal/lysosomal defenses are the obligate intracellular protozoan Toxoplasma gondii and the bacterium Coxiella burnetti . While the intracellular replication of T . gondii requires complete avoidance of the host endocytic cascade, C . burnetti actively subverts it . This results in these organisms establishing and growing in very different vacuolar compartments . In this study we examined the potential interaction between these distinct compartments following coinfection of mammalian fibroblasts . When present within the same cell, these organisms exhibit minimal interaction with each other . Colocalization of T . gondii and C . burnetti within the same vacuole occurs at a low frequency in doubly infected cells . In such instances only one of the organisms appears to be replication competent, emphasizing the different requirements for survival and/or intracellular growth . The potential basis for both the lack of interaction between these distinct pathogen-containing compartments, and the mechanisms to address their low frequency of colocalization are discussed in the context of our understanding of the biology of the organisms and membrane traffic in eukaryotic cells. Respir Med, 2000 Aug, 94(8), 791 - 9 Interaction of Bordetella pertussis with human respiratory mucosa in vitro; Soane MC et al.; The human respiratory tract pathogen Bordetella pertussis is the major cause of whooping cough in infants and young children, and also causes chronic cough in adults . B . pertussis infection damages ciliated epithelium in the respiratory tract . However, the interaction of the bacterium with the respiratory mucosa is poorly understood, and previous studies have either utilized animal tissue which may not be appropriate, or isolated cell systems which lack the complexity of the respiratory mucosa . We have studied the interaction of B . pertussis strain BP536 with human nasal turbinate tissue in an air-interface organ culture over 5 days . We have also compared infection by BP536 with two other strains, Tohama I and CN2992, to determine whether the interactions observed with BP536 are consistent, and, in both nasal turbinate and adenoid organ cultures at 24 h, to determine whether there were differences between tissue from different parts of the respiratory tract . BP536 adhered to cilia, most commonly at their base, and disorganized their spatial arrangement, they also adhered to damaged tissue and mucus, but very rarely to unciliated cells . Within the first 24 h there was a five-fold increase in bacterial density on ciliated cells, and the total number of adherent bacteria increased up to 96 h . Infection caused increased mucus at 24h and an increase in damaged epithelium from 72 h which involved both ciliated and unciliated cells . The number of residual ciliated cells did not decrease after 72 h . The three different strains of B . pertussis exhibited similar interactions with the mucosa, and there was no tissue specificity for adenoid or turbinate tissue . We conclude that B . pertussis adhered to multiple sites on the mucosa and caused hypersecretion and epithelial damage which are the pathological changes described in vivo. Am J Vet Res, 2000 Aug, 61(8), 892 - 9 Effects of intranasal inoculation of porcine reproductive and respiratory syndrome virus, Bordetella bronchiseptica, or a combination of both organisms in pigs; Brockmeier SL et al.; OBJECTIVE: To examine effects of co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and Bordetella bronchiseptica in pigs . ANIMALS: Forty 3-week-old pigs . Procedure-30 pigs (10 pigs/group) were inoculated with PRRSV, B bronchiseptica, or both . Ten noninoculated pigs were control animals . RESULTS: Clinical signs, febrile response, and decreased weight gain were most severe in the group inoculated with both organisms . The PRRSV was isolated from all pigs in both groups inoculated with virus . All pigs in both groups that received PRRSV had gross and microscopic lesions consistent with interstitial pneumonia . Bordetella bronchiseptica was cultured from all pigs in both groups inoculated with that bacterium . Colonization of anatomic sites by B bronchiseptica was comparable between both groups . Pigs in the group that received only B bronchiseptica lacked gross or microscopic lung lesions, and B bronchiseptica was not isolated from lung tissue . In the group inoculated with B bronchiseptica and PRRSV, 3 of 5 pigs 10 days after inoculation and 5 of 5 pigs 21 days after inoculation had gross and microscopic lesions consistent with bacterial bronchopneumonia, and B bronchiseptica was isolated from the lungs of 7 of those 10 pigs . CONCLUSIONS AND CLINICAL RELEVANCE: Clinical disease was exacerbated in co-infected pigs, including an increased febrile response, decreased weight gain, and B bronchiseptica-induced pneumonia . Bordetella bronchiseptica and PRRSV may circulate in a herd and cause subclinical infections . Therefore, co-infection with these organisms may cause clinical respiratory tract disease and leave pigs more susceptible to subsequent infection with opportunistic bacteria. Semin Gastrointest Dis, 2000 Jul, 11(3), 134 - 41 Helicobacter pylori, gastric MALT lymphoma, and adenocarcinoma of the stomach; Go MF et al.; The discovery of Helicobacter pylori and its relationship to upper gastrointestinal tract diseases has emphasized the significance of infectious pathogens in clinical disease . Severe manifestations of H . pylori-associated diseases include gastric adenocarcinoma and the recently described gastric mucosa-associated lymphoid tissue (MALT) lymphoma . Ongoing worldwide investigations of the interactions of H . pylori and the host response are rapidly clarifying the role of this bacterium in multiple gastrointestinal diseases . This review will address diagnosis, management, and follow-up of the patient presenting with gastric MALT lymphoma, including a discussion of the issues related to premalignant lesions associated with gastric adenocarcinoma . Prospective trials and long-term follow-up studies are in progress and will guide appropriate management of these diseases. MMW Fortschr Med, 1999 Dec 16, 141(51-52), 48 - 51 {Crohn disease, ulcerative colitis . When bacteria attack the intestinal wall....}; Duchmann R et al.; Crohn's disease (CD) and ulcerative colitis (UC) are clinical entities characterized by spontaneous relapses and are thought to be caused in large part by a dysregulated immune response to inflammatory stimuli . Specific infectious agents or antigens inducing or perpetuating inflammation, however, are not known . Recent results in contrast support the hypothesis, that the normal intestinal flora plays a central role in the pathogenesis of both diseases . Studies performed with E . coli Nissle 1917 demonstrated that this bacterium can positively affect the course of disease in UC and CD patients . The clinical efficacy of probiotics can yield valuable information about disease pathogenesis and, as a modification of current standard therapy, opens new and interesting therapeutic alternatives. Infect Immun, 2000 Sep, 68(9), 5277 - 83 ankA: an Ehrlichia phagocytophila group gene encoding a cytoplasmic protein antigen with ankyrin repeats; Caturegli P et al.; Human granulocytic ehrlichiosis (HGE) is a potentially fatal, tick-borne disease caused by a bacterium related or identical to Ehrlichia phagocytophila . To identify and characterize E . phagocytophila group-specific protein antigen genes, we prepared and screened HGE agent and Ehrlichia equi genomic DNA expression libraries using polyclonal equine E . equi antibodies . Two clones, one each from HGE agent and E . equi, that were recognized specifically by antibodies to the E . phagocytophila group ehrlichiae had complete open reading frames of 3,693 and 3,615 nucleotides, respectively . The two clones were 96.6% identical and predicted a protein with at least 11 tandemly repeated ankyrin motifs . Thus, the gene was named ank (for ankyrin) . When the encoded protein, named AnkA, was expressed in Escherichia coli, it was recognized by antibodies from rabbits and mice immunized with the HGE agent, sera from humans convalescent from HGE, and sera from horses convalescent from HGE and E . equi infection . Monospecific AnkA antibodies reacted with proteins in HGE agent immunoblots, and AnkA monoclonal antibodies detected cytoplasmic antigen in E . phagocytophila group bacteria and also detected antigen associated with chromatin in infected but not uninfected HL-60 cell cultures . These results suggest that this Ehrlichia protein may influence host cell gene expression. Infect Immun, 2000 Sep, 68(9), 4872 - 6 Coincubation of human spermatozoa with Chlamydia trachomatis in vitro causes increased tyrosine phosphorylation of sperm proteins; Hosseinzadeh S et al.; Elementary bodies (EBs) of the obligate intracellular bacterium Chlamydia trachomatis are responsible for the first step of attachment to host cells . We have studied the effects of EBs on human sperm protein tyrosine phosphorylation, which is important to sperm function . Indirect immunofluorescence using antiphosphotyrosine antibodies showed that serovar E, but not LGV, caused increased tyrosine phosphorylation which was localized to the sperm tail region . Immunoblotting revealed that serovar E caused a marked increase in tyrosine phosphorylation of 80- and 95-kDa sperm proteins, whereas serovar LGV caused increased phosphorylation of only the 80-kDa moiety . Considering the importance of tyrosine phosphorylation for sperm capacitation and other aspects of sperm function, we conclude that EBs may affect these events. Eur J Clin Microbiol Infect Dis, 2000 Jun, 19(6), 477 - 80 Use of the ligase detection reaction-polymerase chain reaction to identify point mutations in extended-spectrum beta-lactamases; Niederhauser C et al.; The aim of this study was to detect point mutations in extended-spectrum beta-lactamase (ESBL) genes in a background of wild-type (non-ESBL-producing) bacteria using a highly sensitive and specific method developed for this purpose . The ligase detection reaction-polymerase chain reaction (LDR-PCR) method was used to test different ESBL-producing strains and clinical isolates for a specific point mutation in the bla SHV-ESBL gene (glycine to serine mutation at position 238) and was compared with the commercially available E test ESBL (AB Biodisk, Sweden) . Nine of the 40 clinical isolates tested were positive for the bla SHV-ESBL point mutation when tested by the LDR-PCR method but negative when tested by the E test . In contrast to the E test or other molecular genetic tests, the LDR-PCR method is able to identify a single bacterium with a point mutation in a background of 100,000 wild-type (non-ESBL-producing) bacteria. Immunopharmacol Immunotoxicol, 2000 Aug, 22(3), 555 - 74 Effects of treatment with amphetamine and diazepam on Mycobacterium bovis-induced infection in hamsters; Domingues-Junior M et al.; Tuberculosis is an example of an infection with an intracellular bacterium in which sensitivity is determined mainly by the host response . Macrophages are the architectural and functional units of the granulomas described in tuberculosis . Treatment with amphetamine (AMPH) and diazepam has been reported to decrease macrophage activity . The present experiment was undertaken to investigate the effects of AMPH and/or diazepam given alone or in combination on hamster resistance to Mycobacterium bovis . The effects of these treatments on serum cortisol levels were also studied . Adult hamsters were treated i.p . with AMPH (group E1 = 1.0 or 2.0 mg/kg/day), with AMPH (group E2 = 1.0 or 2.0 mg/kg/day) plus diazepam (2.0 mg/kg/day), with diazepam (group E3 = 2.0 mg/kg/day), or with control vehicles (1.0 ml/kg/day) for 40 days . Six days after the beginning of the treatments, the animals received identical inoculum concentrations of M . bovis . Hamsters treated with AMPH plus diazepam exhibited: 1) increased weight loss; 2) increased mortality; 3) increased scores of M . bovis colony forming units (CFU) isolated from liver, lung and spleen; 4) increased granuloma areas measured in the liver, lung and spleen . These effects were not induced by AMPH (1.0 or 2.0 mg/kg/day) given alone and were produced by diazepam (2.0 mg/kg/day) treatment per se . Furthermore, AMPH (2.0 mg/kg/day) and diazepam (2.0 mg/kg/day) given alone or in combination for 20 days increased the serum levels of cortisol in relation to control hamsters, with the effect being higher in the animals treated with both drugs . The present data, which demonstrate an impaired defense against M . bovis in hamsters treated with AMPH plus diazepam or with diazepam alone, were tentatively explained on the basis of a direct and/or indirect action of the drugs on macrophage/lymphocyte activity . In the former case, the effects may be related to stimulation of peripheral benzodiazepine receptor sites (PBR) present on macrophages/lymphocytes and/or to a direct effect of ACTH on immune cells, while in the latter they may be mediated by cortisol via PBR and ACTH stimulation of the adrenals. J Food Prot, 2000 Aug, 63(8), 1032 - 7 A multiplex polymerase chain reaction assay for rapid detection and identification of Escherichia coli O157:H7 in foods and bovine feces; Fratamico PM et al.; A multiplex polymerase chain reaction (PCR) assay was designed to simplify detection of Escherichia coli O157:H7 and to identify the H serogroup and the type of Shiga toxin produced by this bacterium . Primers for a plasmid-encoded hemolysin gene (hly933), and chromosomal flagella (fliCh7; flagellar structural gene of H7 serogroup), Shiga toxins (stx1, stx2), and attaching and effacing (eaeA) genes were used in a multiplex PCR for coamplification of the corresponding DNA sequences from enterohemorrhagic E . coli (EHEC) O157:H7 . Enrichment cultures of ground beef, blue cheese, mussels, alfalfa sprouts, and bovine feces, artificially inoculated with various levels of E . coli O157:H7 strain 933, were subjected to a simple DNA extraction step prior to the PCR, and the resulting amplification products were analyzed by agarose gel electrophoresis . Sensitivity of the assay was < or = 1 CFU/g of food or bovine feces (initial inoculum level), and results could be obtained within 24 h . Similar detection levels were obtained with ground beef samples that underwent enrichment culturing immediately after inoculation and samples that were frozen or refrigerated prior to enrichment . The multiplex PCR facilitates detection of E . coli O157:H7 and can reduce the time required for confirmation of isolates by up to 3 to 4 days. Int J Dermatol, 2000 Jun, 39(6), 446 - 52 Helicobacter pylori and idiopathic chronic urticaria; Dauden E et al.; BACKGROUND: Different studies have shown a high prevalence of Helicobacter pylori (HP) infection in patients with chronic urticaria (CU), and occasional remission of the skin lesions after eradication therapy . Recent investigations, however, have failed to find a significant relationship between the two conditions . We designed a case-control study to assess the prevalence of HP infection and the effect of bacterium eradication on the outcome of the skin disease in patients affected by CU . The literature is reviewed . METHODS: Twenty-five patients diagnosed with CU were included . Information about their medical history and a complete laboratory investigation ruled out other diseases or situations suspected to cause CU . Twenty-five healthy volunteers from a census-based, randomized sample were used as controls . HP infection was assessed by the (13)C-urea breath test (UBT) . Eradication therapy included oral amoxicillin, omeprazole, and clarithromycin for 1 week . RESULTS: The high prevalence of HP infection (68%) and mean titer of UBT (24.13) in our patients with idiopathic CU do not differ from the general population . Marked differences were observed in the mean age of the CU patients with positive UBT (45.52years) vs . those without HP infection (35.25 years) . After eradication therapy, only one patient showed a complete remission of urticaria and two showed a partial remission . CONCLUSIONS: Our results support a lack of relationship between HP infection and the course of idiopathic CU. Cent Eur J Public Health, 2000 Jul, 8 Suppl, 62 - 4 Evaluation of a Hungarian acaricide original molecule based on its environmental toxicological studies; Szamosi D et al.; The results of the environmental toxicological investigations and their results of a new hungarian acaricide molecule (SZI-121) developed by the CHINOIN were summarized . The toxicological effects of the test item on different ecotoxicological test systems were investigated in the following tests: Bacterium, alga, and plant growth inhibition tests, acute immobilization and 21 days reproduction tests on Daphnia magna, acute fish test, closed bottle test, mobility, aerob degradation and adsorption/desorption tests on three different soils . No toxic effect was found in the bacterium, alga, plant growth inhibition and acute fish tests in the highest concentrations used . In the Daphnia immobilization test 0.14 mg/l LC50 value was established in the concentration range of 0.0128-40 mg/l applied . The test item showed similar characteristics as the reference item during the mobility test in soils, the adsorption/desorption study and the degradation investigations . In order to determine the environmental degradation rate further degradation investigations, as well as the nitrogen mineralization test and the model of concentration change in natural waters were performed. Cent Eur J Public Health, 2000 Jul, 8 Suppl, 61 - 2 Analytical and biological data to the environmental-toxicological behaviour of Verbutin pesticide; Halasz-Laky V et al.; Ecotoxicological characteristics of a new insecticide synergist, MBB-599 (proposed common name: Verbutin) was investigated . The studies included the determination of the hydrolysis, the biodegradability, the adsorption and desorption characteristics in soil and the effects on living systems (bacterium, alga, Daphnia, and fish) as well. J Wildl Dis, 2000 Jul, 36(3), 484 - 8 Safety of Brucella abortus strain RB51 in bull elk; Cook WE et al.; Some of the elk (Cervus elaphus nelsoni) of the Greater Yellowstone Area (Wyoming, Idaho, Montana; USA) are infected with Brucella abortus, the bacterium that causes bovine brucellosis . Brucella abortus strain RB51 vaccine is being considered as a means to control B . abortus induced abortions in cow elk . However, the most probable vaccination strategies for use in free-ranging elk might also result in some bull elk being inoculated, thus, it is important to insure that the vaccine is safe in these animals . In the winter of 1995, 10 free-ranging bull elk calves were captured, tested for B . abortus antibodies, and intramuscularly inoculated with 1.0 x 10(9) colony forming units (CFU) of B . abortus strain RB51 . Blood was collected for hemoculture and serology every 2 wk after inoculation for 14 wk . Beginning 4 mo postinoculation and continuing until 10 mo postinoculation elk were serially euthanized, necropsied, and tissues collected for culture and histopathology . These elk cleared the organism from the blood within 6 wk and from all tissues within 10 mo . No lesions attributable to B . abortus were found grossly and only minimal to mild lymphoplasmacytic epididymitis was found in a few elk on histologic examination . In a separate study, six adult bull elk from Wind Cave National Park (South Dakota, USA) were taken to a ranch near Carrington (North Dakota, USA) . Three were orally inoculated with approximately 1.0 x 10(10) CFU of RB51 and three were inoculated with corn syrup and saline . Ninety days post-inoculation semen was examined and cultured from these bulls . Strain RB51 was not cultured from their semen at that time . There were no palpable abnormalities in the genital tract and all elk produced viable sperm . Although they contain small sample sizes, these studies suggest that B . abortus strain RB51 is safe in bull elk. Int J Syst Evol Microbiol, 2000 Jul, 50 Pt 4, 1547 - 51 Actinomyces canis sp . nov., isolated from dogs; Hoyles L et al.; Three strains of a previously undescribed catalase-positive Actinomyces-like bacterium were isolated from dogs . Biochemical testing and PAGE analysis of whole-cell proteins indicated that the strains were phenotypically highly related to each other but different from previously described Actinomyces and Arcanobacterium species . Sequencing of 16S rRNA showed that the unknown bacterium represents a new subline within a cluster of species which includes Actinomyces hyovaginalis, Actinomyces georgiae, Actinomyces meyeri, Actinomyces odontolyticus, Actinomyces radingae and Actinomyces turicensis . On the basis of phenotypic evidence and 16S rRNA sequence divergence levels (greater than 5% with recognized Actinomyces species) it is proposed that the unknown strains from canine sources be classified as a new species with the name Actinomyces canis sp . nov . The type strain of Actinomyces canis is CCUG 41706T (= CIP 106351T). Mol Biol Rep, 2000 Mar, 27(1), 27 - 33 Characterization of the cys gene locus from Allochromatium vinosum indicates an unusual sulfate assimilation pathway; Neumann S et al.; Homologues of the genes cysB, cysI, cysH, cysD, cysN, and selD were identified in the genome of the phototrophic purple sulfur bacterium Allochromatium vinosum (formerly Chromatium vinosum) . On the basis of amino acid comparisons these genes encode a ferredoxin-dependent siroheme-sulfite reductase (CysI), a plant-type assimilatory APS reductase without thioredoxin domain (CysH), the two different subunits of heterodimeric ATP sulfurylase (CysDN), a transcriptional regulator (CysB) and a selenophosphate synthase (SelD) . cysIHDN appear to form an operon and are preceded by cysB which is transcribed in the opposite direction . SelD is situated downstream of cysN and transcribed divergently to cysIHDN . The lack of a gene for APS kinase and presence of a gene for an assimilatory APS reductase implies that assimilatory sulfate reduction in A . vinosum proceeds along the pathway suggested for higher plants without intermediary formation of PAPS . Two completely separate pathways involving specialized enzymes are used for assimilatory sulfate reduction and dissimilatory sulfur oxidation in A . vinosum . The presence of cysB indicates that the genes for assimilatory sulfate reduction are expressed only in the absence of reduced sulfur compounds. J Mol Microbiol Biotechnol, 2000 Apr, 2(2), 235 - 43 DNA binding of wild type RegA protein and its differential effect on the expression of pigment binding proteins in Rhodobacter capsulatus; Hemschemeier SK et al.; The transcription of genes encoding pigment binding proteins in the facultative photosynthetic bacterium Rhodobacter capsulatus is regulated in response to oxygen partial pressure . Previous results identified RegA and RegB as members of a two component system involved in oxygen dependent synthesis of the photosynthetic apparatus . Here we demonstrate that RegA differentially controls the transcription of the puf and pucoperons which encode proteins of the LHI and LHII antenna complexes, respectively . In a regA mutant strain the level of puf specific mRNA reaches about 30% of the wild type levels and transcription is still responsive to oxygen tension . In contrast, the level of puc specific mRNA is very low and is no longer oxygen regulated . RegA binds to DNA sequences upstream of both the puf and puc operons, although with different affinities . We provide experimental evidence that a putative helix-turn-helix motif in the C-terminal region of RegA is responsible for its specific binding to the puf and puc promoter regions . In contrast to many other response regulators, the affinity of RegA for the target DNA is only slightly modified by phosphorylation. J Exp Bot, 2000 Feb, 51(343), 177 - 85 Improved tolerance to salinity and low temperature in transgenic tobacco producing glycine betaine; Holmstrom KO et al.; Glycine betaine is an osmoprotectant found in many organisms, including bacteria and higher plants . The bacterium Escherichia coli produces glycine betaine by a two-step pathway where choline dehydrogenase (CDH), encoded by betA, oxidizes choline to betaine aldehyde which is further oxidized to glycine betaine by the same enzyme . The second step, conversion of betaine aldehyde into glycine betaine, can also be performed by the second enzyme in the pathway, betaine aldehyde dehydrogenase (BADH), encoded by betB . Transformation of tobacco (Nicotiana tabacum), a species not accumulating glycine betaine, with the E . coli genes for glycine betaine biosynthesis, resulted in transgenic plants accumulating glycine betaine . Plants producing CDH were found to accumulate glycine betaine as did F1 progeny from crosses between CDH- and BADH-producing lines . Plants producing both CDH and BADH generally accumulated higher amounts of glycine betaine than plants producing CDH alone, as determined by 1H NMR analysis . Transgenic tobacco lines accumulating glycine betaine exhibited increased tolerance to salt stress as measured by biomass production of greenhouse-grown intact plants . Furthermore, experiments conducted with leaf discs from glycine betaine-accumulating plants indicated enhanced recovery from photoinhibition caused by high light and salt stress as well as improved tolerance to photoinhibition under low temperature conditions . In conclusion, introduction of glycine betaine production into tobacco is associated with increased stress tolerance probably partly due to improved protection of the photosynthetic apparatus. J Mol Microbiol Biotechnol, 2000 Jul, 2(3), 291 - 300 In vivo and in vitro analysis of RegA response regulator mutants of Rhodobacter capsulatus; Hemschemeier SK et al.; In the facultative photosynthetic bacterium Rhodobacter capsulatus, the transcription of genes encoding pigment binding proteins is tightly regulated in response to the oxygen partial pressure by the RegB/ RegA two component system . After a shift from high to low oxygen tension, the response regulator RegA enhances transcription of the puf and puc operon coding for the reaction center, light-harvesting complex I (LHI), and LHII proteins . Various regA mutant strains were analyzed in this study . In a RegA deficient strain, activation of puf and puc transcription is severely impaired which consequently leads to the synthesis of only a few photosynthetic complexes . Strains carrying a mutation in the helix-turn-helix domain of RegA or a mutation of the phosphorylation site, Asp63, show a phenotype like the RegA deficient mutant, although the RegA(D63K) mutant protein showed the same DNA binding behavior as the wild type protein . In contrast, the puf and puc mRNAs still reach about 50-70 % of the wild type level after reduction of oxygen tension in strains which synthesize the C-terminal RegA activator domain only or a hybrid protein composed of the RegA activator and the FixJ receiver domain, while both mutant proteins are impaired in DNA binding . Our data suggest that phosphorylation is not required for DNA binding but rather plays a role for efficient initiation of transcription. J Biol Chem, 2000 Nov 10, 275(45), 35499 - 505 iota-Carrageenases constitute a novel family of glycoside hydrolases, unrelated to that of kappa-carrageenases; Barbeyron T et al.; iota-Carrageenases are polysaccharide hydrolases that cleave the beta-1,4 linkages between the d-galactose-4-sulfate and 3, 6-anhydro-d-galactose-2-sulfate residues in the red algal galactans known as iota-carrageenans . We report here on the purification of iota-carrageenase activity from the marine bacterium Zobellia galactanovorans and on the characterization of iota-carrageenase structural genes . Genomic libraries from this latter bacterium as well as from Alteromonas fortis were functionally screened for the presence of iota-carrageenase(+) clones . The Z . galactanovorans and A . fortis iota-carrageenase genes encode homologous proteins of 53.4 and 54.8 kDa, respectively . Based on hydrophobic cluster analysis and on the (1)H NMR monitoring of the products of the overexpressed A . fortis iota-carrageenase, these enzymes appear to form a new family of glycoside hydrolases, unrelated to that of kappa-carrageenases and with an inverting mechanism of hydrolysis . They both feature a 45-amino acid-long N-terminal segment with sequence similarity to the N-terminal region of several other polysaccharidases . In those for which a three-dimensional structure is available, this conspicuous segment, also deemed "glycanase motif" (Chua, J . E . H., Manning, P . A., and Morona, R . (1999) Microbiology (Reading) 145, 1649-1659), corresponds to a strand-helix-strand "cap" that covers the N-terminal end of a common, right-handed beta-helical fold. Rev Latinoam Microbiol, 1996 Jul-Dec, 38(3-4), 207 - 17 {Non-specific resistance in Brucella infection}; Moreno-Lafont MC et al.; Brucellosis is still a critical public health problem in many countries around the world . In humans, the infection is mainly acquired through the ingestion of milk-derived products from infected cattle . After the penetration of the bacteria in the body, several serum components are activated, and the immediate consequence is the attraction of phagocytic cells . The evolution of the disease often courses to a long lasting form, with frequent relapses . This appears to be due to the capability of Brucella's of surviving and, even more, multiplying within the mononuclear phagocytic cells . First, the intracellular location protects the bacteria from the effect of antibiotics . On the other hand, several studies have shown alterations in the phagocytic function . In some cases, the defects in phagocytosis are intrinsic to the host . However, Brucella organisms also display many mechanisms to evade the intracellular killing, which appears to be the reason for the success of the bacterium in dwelling within macrophages. Proc Natl Acad Sci U S A, 2000 Aug 15, 97(17), 9642 - 7 Genomewide insertional mutagenesis in Streptomyces coelicolor reveals additional genes involved in morphological differentiation; Gehring AM et al.; The filamentous soil bacterium Streptomyces coelicolor undergoes a complex cycle of morphological differentiation involving the formation of an aerial mycelium and the production of pigmented antibiotics . We have developed a procedure for generating insertional mutants of S . coelicolor based on in vitro transposition of a plasmid library of cloned S . coelicolor DNAs . The insertionally mutated library was introduced into S . coelicolor, and transposon insertions were recovered at widely scattered locations around the chromosome . Many of the insertions revealed previously uncharacterized genes, and several caused novel mutant phenotypes, such as altered pigment production, enhanced antibiotic sensitivity, delayed or impaired formation of aerial hyphae, and a block in spore formation . The sporulation mutant harbored an insertion in one of three adjacent genes that are apparently unique to Streptomyces but are each represented by at least 20 paralogs at dispersed locations in the chromosome . Individual members of the three families often are found grouped together in a characteristic arrangement, suggesting that they have a common function. Mol Microbiol, 2000 Jul, 37(2), 274 - 86 Iron acquisition and virulence in Helicobacter pylori: a major role for FeoB, a high-affinity ferrous iron transporter; Velayudhan J et al.; The genome sequence of Helicobacter pylori suggests that this bacterium possesses several Fe acquisition systems, including both Fe2+- and Fe3+-citrate transporters . The role of these transporters was investigated by generating insertion mutants in feoB, tonB, fecA1 and fecDE . Fe transport in the feoB mutant was approximately 10-fold lower than in the wild type (with 0.5 microM Fe), irrespective of whether Fe was supplied in the Fe2+ or Fe3+ form . In contrast, transport rates were unaffected by the other mutations . Complementation of the feoB mutation fully restored both Fe2+ and Fe3+ transport . The growth inhibition exhibited by the feoB mutant in Fe-deficient media was relieved by human holo-transferrin, holo-lactoferrin and Fe3+-dicitrate, but not by FeSO4 . The feoB mutant had less cellular Fe and was more sensitive to growth inhibition by transition metals in comparison with the wild type . Biphasic kinetics of Fe2+ transport in the wild type suggested the presence of high- and low-affinity uptake systems . The high-affinity system (apparent Ks = 0.54 microM) is absent in the feoB mutant . Transport via FeoB is highly specific for Fe2+ and was inhibited by FCCP, DCCD and vanadate, indicating an active process energized by ATP . Ferrozine inhibition of Fe2+ and Fe3+ uptake implied the concerted involvement of both an Fe3+ reductase and FeoB in the uptake of Fe supplied as Fe3+ . Taken together, the results are consistent with FeoB-mediated Fe2+ uptake being a major pathway for H . pylori Fe acquisition . feoB mutants were unable to colonize the gastric mucosa of mice, indicating that FeoB makes an important contribution to Fe acquisition by H . pylori in the low-pH, low-O2 environment of the stomach. FEMS Microbiol Lett, 2000 Aug 15, 189(2), 149 - 54 The modification of the membrane of Oceanomonas baumannii when subjected to both osmotic and organic solvent stress; Brown GR et al.; Oceanomonas baumanniioff a novel halotolerant bacterium which was isolated from the estuary of the river Wear (Sunderland, UK) . When grown in tryptone soya broth it can tolerate high levels of phenol, which is not utilised as a carbon source in this medium . However, the level of tolerance was reduced from 35 mM to 3 mM phenol as salinity increased from 1% to 12% NaCl (w/v) . Increasing salinity up to 12% NaCl also decreased the growth rate 8-fold and caused modifications to the cytoplasmic membrane particularly anionic phosphatidylglycerol levels, which doubled at the expense of zwitterionic phosphatidylethanolamine . In addition, changes in the phospholipid fatty acid composition were noted, cis-vaccenic acid decreased significantly at higher salinities . Intracellular solute levels also increased with increasing salinity and there was an accumulation of the compatible solutes ectoine, glycine betaine and glutamate . The addition of phenol to osmotically compromised cultures led to a further modification of the cytoplasmic membrane phospholipid composition, in particular, that the decrease in zwitterionic phosphatidylethanolamine and the increase of anionic phospholipid species was much less pronounced . A further decrease in unsaturation, particularly in the proportion of cis-vaccenic acid, and the mean chain length of the fatty acids suggested that this response was important in maintaining membrane integrity in the presence of phenol. Gastroenterology, 2000 Aug, 119(2), 358 - 67 Acid-dependent adherence of Helicobacter pylori urease to diverse polysaccharides; Icatlo FC et al.; BACKGROUND & AIMS: The significance of acid-primed recognition of ligands by Helicobacter pylori urease is unknown . This study aimed to further characterize the specificity of urease adherence in vitro and verify whether specific inhibition will translate into in vivo suppression of colonization . METHODS: A highly sensitive competitive enzyme-linked ligand capture assay was used to quantify the capacity of each test inhibitor to compete with labeled mucin for binding sites on immobilized native urease . A model polymer that strongly bound urease was used in an in vivo trial using euthymic hairless mice as an infection model . RESULTS: The blockage of urease-gastric mucin interaction by certain inhibitors revealed an acid-functional lectin-like activity by urease, specifically recognizing bacterial lipopolysaccharides and certain species of polysaccharides, nonbacterial glycolipids, and glycoproteins . Dextran sulfate significantly (P < 0.01) suppressed colonization of mice by H . pylori when given before and/or after challenge . CONCLUSIONS: The acid-driven high-affinity adherence of H . pylori urease to mucin and lipopolysaccharides contributes to gastric mucosal colonization by the bacterium based on in vivo targeting experiments using specific polysaccharides in a mouse model with acute infection . Acid-functional urease-homing polysaccharides that can interfere with urease-mucin or H . pylori whole cell-mucin interaction in vitro can significantly interfere with colonization by the bacterium in vivo. Artif Cells Blood Substit Immobil Biotechnol, 2000 Jul, 28(4), 347 - 63 Study on the physiology and degradation of dye with immobilized algae; Huang G et al.; Immobilization of chlorella (pyrenoidosa) with calcium alginate was carried out . Both algal growth and physiological activity increased after immobilization . Algal size and initial density have little influence on cell growth and physiological activity . Algal cell division inside the support was restricted without bubbling air containing 2% CO2 . Individual algal cell increased and algal distribution inside the support was not homogeneous, indicating that within the support the resistance of mass transfer of CO2 was the limiting factor for the growth and cell division of immobilized algae . After bubbling 2% CO2, algal growth, the cell division considerably increased and individual cell size restored normally . Study of the degradation of dye (direct brown NM) by immobilized algae was better than that of free algae . Bubbling air containing 2% CO2 in the culture solution was more favorable for increasing decolorization rate . Preliminary study of co-immobilization of algae plus bacterium illustrated that the addition of bacterium increased the anabolic activity of algae, thus increased the decolorization capacity if immobilized algae for dye. Med Hypotheses, 2000 Aug, 55(2), 119 - 25 Is Helicobacter pylori a cause of infantile hypertrophic pyloric stenosis? Paulozzi LJ. My hypothesis is that infantile hypertrophic pyloric stenosis (IHPS) is caused in some cases by Helicobacter pylori (HP) a bacterium commonly found in the human stomach . IHPS is an idiopathic condition of infancy . It occurs at about 5 weeks of age in 3 per 1000 newborns . Children with IHPS have structurally normal pylori at birth and do not resemble children with congenital anomalies . Some nonspecific evidence (temporal distribution, seasonality, familial clustering, leukocytic infiltrates, and increased risk with bottle feeding) are compatible with an infectious etiology . Some other epidemiologic features of IHPS, such as its strong male predominance, its racial and social class variation, and a possible drop in its incidence, are also features of HP infection . Clinical features of IHPS, such as vomiting, hematemesis, and esophagitis, are also consistent with HP . Finally, children with IHPS appear to be more likely to develop chronic conditions, such as peptic ulcers, now known to be caused by HP . Biochim Biophys Acta, 2000 Jul 20, 1459(1), 169 - 78 Diphenylene iodonium as an inhibitor for the hydrogenase complex of Rhodobacter capsulatus . Evidence for two distinct electron donor sites; Magnani P et al.; The photosynthetic bacterium Rhodobacter capsulatus synthesises a membrane-bound {NiFe} hydrogenase encoded by the H2 uptake hydrogenase (hup)SLC structural operon . The hupS and hupL genes encode the small and large subunits of hydrogenase, respectively; hupC encodes a membrane electron carrier protein which may be considered as the third subunit of the uptake hydrogenase . In Wolinella succinogenes, the hydC gene, homologous to hupC, has been shown to encode a low potential cytochrome b which mediates electron transfer from H2 to the quinone pool of the bacterial membrane . In whole cells of R . capsulatus or intact membrane preparation of the wild type strain B10, methylene blue but not benzyl viologen can be used as acceptor of the electrons donated by H2 to hydrogenase; on the other hand, membranes of B10 treated with Triton X-100 or whole cells of a HupC- mutant exhibit both benzyl viologen and methylene blue reductase activities . We report the effect of diphenylene iodonium (Ph2I), a known inhibitor of mitochondrial complex I and of various monooxygenases on R . capsulatus hydrogenase activity . With H2 as electron donor, Ph2I inhibited partially the methylene blue reductase activity in an uncompetitive manner, and totally benzyl viologen reductase activity in a competitive manner . Furthermore, with benzyl viologen as electron acceptor, Ph2I increased dramatically the observed lagtime for dye reduction . These results suggest that two different sites exist on the electron donor side of the membrane-bound {NiFe} hydrogenase of R . capsulatus, both located on the small subunit . A low redox potential site which reduces benzyl viologen, binds Ph2I and could be located on the distal {Fe4S4} cluster . A higher redox potential site which can reduce methylene blue in vitro could be connected to the high potential {Fe3S4} cluster and freely accessible from the periplasm. Appl Environ Microbiol, 2000 Aug, 66(8), 3574 - 85 Spatial and temporal variations in chitinolytic gene expression and bacterial biomass production during chitin degradation; Baty AM 3rd et al.; Growth of the chitin-degrading marine bacterium S91 on solid surfaces under oligotrophic conditions was accompanied by the displacement of a large fraction of the surface-derived bacterial production into the flowing bulk aqueous phase, irrespective of the value of the surface as a nutrient source . Over a 200-h period of surface colonization, 97 and 75% of the bacterial biomass generated on biodegradable chitin and a nonnutritional silicon surface, respectively, detached to become part of the free-living population in the bulk aqueous phase . Specific surface-associated growth rates that included the cells that subsequently detached from the substrata varied depending on the nutritional value of the substratum and during the period of surface colonization . Specific growth rates of 3.79 and 2.83 day(-1) were obtained when cells first began to proliferate on a pure chitin film and a silicon surface, respectively . Later, when cell densities on the surface and detached cells as CFU in the bulk aqueous phase achieved a quasi-steady state, specific growth rates decreased to 1.08 and 0.79 day(-1) on the chitin and silicon surfaces, respectively . Virtually all of the cells that detached from either the chitin or the silicon surfaces and the majority of cells associated with the chitin surface over the 200-h period of surface colonization displayed no detectable expression of the chitin-degrading genes chiA and chiB . Cells displaying high levels of chiA-chiB expression were detected only on the chitin surface and then only clustered in discrete areas of the surface . Surface-associated, differential gene expression and displacement of bacterial production from surfaces represent adaptations at the population level that promote efficient utilization of limited resources and dispersal of progeny to maximize access to new sources of energy and maintenance of the population. Appl Environ Microbiol, 2000 Aug, 66(8), 3566 - 73 Differentiation of chitinase-active and non-chitinase-active subpopulations of a marine bacterium during chitin degradation; Baty AM 3rd et al.; The ability of marine bacteria to adhere to detrital particulate organic matter and rapidly switch on metabolic genes in an effort to reproduce is an important response for bacterial survival in the pelagic marine environment . The goal of this investigation was to evaluate the relationship between chitinolytic gene expression and extracellular chitinase activity in individual cells of the marine bacterium Pseudoalteromonas sp . strain S91 attached to solid chitin . A green fluorescent protein reporter gene under the control of the chiA promoter was used to evaluate chiA gene expression, and a precipitating enzyme-linked fluorescent probe, ELF-97-N-acetyl-beta-D-glucosaminide, was used to evaluate extracellular chitinase activity among cells in the bacterial population . Evaluation of chiA expression and ELF-97 crystal location at the single-cell level revealed two physiologically distinct subpopulations of S91 on the chitin surface: one that was chitinase active and remained associated with the surface and another that was non-chitinase active and released daughter cells into the bulk aqueous phase . It is hypothesized that the surface-associated, non-chitinase-active population is utilizing chitin degradation products that were released by the adjacent chitinase-active population for cell replication and dissemination into the bulk aqueous phase. Appl Environ Microbiol, 2000 Aug, 66(8), 3474 - 80 Cloning of the spoT gene of "Candidatus Phlomobacter fragariae" and development of a PCR-restriction fragment length polymorphism assay for detection of the bacterium in insects