Am J Gastroenterol, 1998 Sep, 93(9), 1425 - 31 Reversal of fundic atrophy after eradication of Helicobacter pylori; Tucci A et al.; OBJECTIVES: We sought to evaluate the effect of Helicobacter pylori eradication in patients with fundic atrophic gastritis . METHODS: Acid secretion, gastric emptying, and histology were evaluated in 20 patients with fundic atrophic gastritis and H . pylori infection . After investigation, 10 patients (Group 1) received an eradicating treatment and 10 (Group 2) did not receive any treatment . One year later, the baseline investigations were repeated . Subsequently, patients in Group 2 received the same treatment given to patients in Group 1 and were reevaluated 12 months later . A further follow-up was performed in both groups 36 months after the treatment . RESULTS: At 1-yr follow-up, all the patients in Group 1 were H . pylori negative whereas all the patients in Group 2 were still infected . In Group 1, there was a significant improvement of both fundic atrophy and acid secretion, compared with baseline (p < 0.01) . In Group 2, no substantial modification of either histological or functional parameters was observed at the first follow-up; conversely, a significant (p < 0.01) improvement of fundic atrophy and acid secretion was detected in these patients 12 months after eradication of the bacterium . Histological pattern remained unchanged at 36 months of follow-up in both groups . Gastric emptying remained, on the average, unaffected by the treatment; however, three patients with delayed gastric emptying at entry had normal gastric emptying after eradication of H . pylori . CONCLUSIONS: Our data suggest that mucosal atrophy can be reduced or even reversed by the eradication of H . pylori, and this is associated with a recovery of gastric function. Int J Syst Bacteriol, 1998 Apr, 48 Pt 2, 431 - 40 Pelistega europaea gen . nov., sp . nov., a bacterium associated with respiratory disease in pigeons: taxonomic structure and phylogenetic allocation; Vandamme P et al.; Twenty-four strains isolated mainly from infected respiratory tracts of pigeons were characterized by an integrated genotypic and phenotypic approach . An extensive biochemical examination using conventional tests and several API microtest systems indicated that all isolates formed a phenotypically homogeneous taxon with a DNA G + C content between 42 and 43 mol% . Whole-cell protein and fatty acid analysis revealed an unexpected heterogeneity which was confirmed by DNA-DNA hybridizations . Four main genotypic sub-groups (genomovars) were delineated . 16S rDNA sequence analysis of a representative strain indicated that this taxon belongs to the beta-subclass of the Proteobacteria with Taylorella equigenitalis as its closest neighbour (about 94.8% similarity) . A comparison of phenotypic and genotypic characteristics of both taxa suggested that the pigeon isolates represented a novel genus for which the name Pelistega is proposed . In the absence of differential phenotypic characteristics between the genomovars, it was preferred to include all of the isolates into a single species, Pelistega europaea, and strain LMG 10982 was selected as the type strain . The latter strain belongs to fatty acid cluster I and protein electrophoretic sub-group 1, which comprise 13 and 5 isolates, respectively . It is not unlikely that the name P . europaea will be restricted in the future to organisms belonging to fatty acid cluster I, or even to protein electrophoretic sub-group 1, upon discovery of differential diagnostic features. BMJ, 1998 Sep 5, 317(7159), 637 - 42 Understanding the culture of prescribing: qualitative study of general practitioners' and patients' perceptions of antibiotics for sore throats; Butler CC et al.; OBJECTIVES: To better understand reasons for antibiotics being prescribed for sore throats despite well known evidence that they are generally of little help . DESIGN: Qualitative study with semi-structured interviews . SETTING: General practices in South Wales . SUBJECTS: 21 general practitioners and 17 of their patients who had recently consulted for a sore throat or upper respiratory tract infection . MAIN OUTCOME MEASURES: Subjects' experience of management of the illness, patients' expectations, beliefs about antibiotic treatment for sore throats, and ideas for reducing prescribing . RESULTS: Doctors knew of the evidence for marginal effectiveness yet often prescribed for good relationships with patients . Possible patient benefit outweighed theoretical community risk from resistant bacteria . Most doctors found prescribing "against the evidence" uncomfortable and realised this probably increased workload . Explanations of the distinction between virus and bacterium often led to perceived confusion . Clinicians were divided on the value of leaflets and national campaigns, but several favoured patient empowerment for self care by other members of the primary care team . Patient expectations were seldom made explicit, and many were not met . A third of patients had a clear expectation for antibiotics, and mothers were more likely to accept non-antibiotic treatment for their children than for themselves . Satisfaction was not necessarily related to receiving antibiotics, with many seeking reassurance, further information, and pain relief . CONCLUSIONS: This prescribing decision is greatly influenced by considerations of the doctor-patient relationship . Consulting strategies that make patient expectations explicit without damaging relationships might reduce unwanted antibiotics . Repeating evidence for lack of effectiveness is unlikely to change doctors' prescribing, but information about risk to individual patients might . Emphasising positive aspects of non-antibiotic treatment and lack of efficacy in general might be helpful. Appl Environ Microbiol, 1998 Sep, 64(9), 3429 - 36 Assessment of reductive acetogenesis with indigenous ruminal bacterium populations and Acetitomaculum ruminis; Le Van TD et al.; The objective of this study was to evaluate the role of reductive acetogenesis as an alternative H2 disposal mechanism in the rumen . H2/CO2-supported acetogenic ruminal bacteria were enumerated by using a selective inhibitor of methanogenesis, 2-bromoethanesulfonic acid (BES) . Acetogenic bacteria ranged in density from 2.5 x 10(5) cells/ml in beef cows fed a high-forage diet to 75 cells/ml in finishing steers fed a high-grain diet . Negligible endogenous acetogenic activity was demonstrated in incubations containing ruminal contents, NaH13CO3, and 100% H2 gas phase since {U-13C}acetate, as measured by mass spectroscopy, did not accumulate . Enhancement of acetogenesis was observed in these incubations when methanogenesis was inhibited by BES and/or by the addition of an axenic culture of the rumen acetogen Acetitomaculum ruminis 190A4 (10(7) CFU/ml) . To assess the relative importance of population density and/or H2 concentration for reductive acetogenesis in ruminal contents, incubations as described above were performed under a 100% N2 gas phase . Both selective inhibition of methanogenesis and A . ruminis 190A4 fortification (>10(5) CFU/ml) were necessary for the detection of reductive acetogenesis under H2-limiting conditions . Under these conditions, H2 accumulated to 4, 800 ppm . In contrast, H2 accumulated to 400 ppm in incubations with active methanogenesis (without BES) . These H2 concentrations correlated well with the pure culture H2 threshold concentrations determined for A . ruminis 190A4 (3,830 ppm) and the ruminal methanogen 10-16B (126 ppm) . The data demonstrate that ruminal methanogenic bacteria limited reductive acetogenesis by lowering the H2 partial pressure below the level necessary for H2 utilization by A . ruminis 190A4. Appl Environ Microbiol, 1998 Sep, 64(9), 3166 - 74 Analysis of Escherichia coli O157:H7 survival in ovine or bovine manure and manure slurry; Kudva IT et al.; Farm animal manure or manure slurry may disseminate, transmit, or propagate Escherichia coli O157:H7 . In this study, the survival and growth of E . coli O157:H7 in ovine or bovine feces under various experimental and environmental conditions were determined . A manure pile collected from experimentally inoculated sheep was incubated outside under fluctuating environmental conditions . E . coli O157:H7 survived in the manure for 21 months, and the concentrations of bacteria recovered ranged from <10(2) to 10(6) CFU/g at different times over the course of the experiment . The DNA fingerprints of E . coli O157:H7 isolated at month 1 and month 12 were identical or very similar . A second E . coli O157:H7-positive ovine manure pile, which was periodically aerated by mixing, remained culture positive for 4 months . An E . coli O157:H7-positive bovine manure pile was culture positive for 47 days . In the laboratory, E . coli O157:H7 was inoculated into feces, untreated slurry, or treated slurry and incubated at -20, 4, 23, 37, 45, and 70 degreesC . E . coli O157:H7 survived best in manure incubated without aeration at temperatures below 23 degreesC, but it usually survived for shorter periods of time than it survived in manure held in the environment . The bacterium survived at least 100 days in bovine manure frozen at -20 degreesC or in ovine manure incubated at 4 or 10 degreesC for 100 days, but under all other conditions the length of time that it survived ranged from 24 h to 40 days . In addition, we found that the Shiga toxin type 1 and 2 genes in E . coli O157:H7 had little or no influence on bacterial survival in manure or manure slurry . The long-term survival of E . coli O157:H7 in manure emphasizes the need for appropriate farm waste management to curtail environmental spread of this bacterium . This study also highlights the difficulties in extrapolating laboratory data to on-farm conditions. Appl Environ Microbiol, 1998 Sep, 64(9), 3134 - 9 Signal transduction in the protozoan host Hartmannella vermiformis upon attachment and invasion by Legionella micdadei; Abu Kwaik Y et al.; The intracellular pathogens Legionella micdadei and Legionella pneumophila are the two most common Legionella species that cause Legionnaires' disease . Intracellular replication within pulmonary cells is the hallmark of Legionnaires' disease . In the environment, legionellae are parasites of protozoans, and intracellular bacterial replication within protozoans plays a major role in the transmission of Legionnaires' disease . In this study, we characterized the initial host signal transduction mechanisms involved during attachment to and invasion of the protozoan host Hartmannella vermiformis by L . micdadei . Bacterial attachment prior to invasion of H . vermiformis by L . micdadei is associated with tyrosine dephosphorylation of multiple host cell proteins, including a 170-kDa protein . We have previously shown that this 170-kDa protein is the galactose N-acetylgalactosamine (Gal/GalNAc)-inhibitable lectin receptor that mediates attachment to and invasion of H . vermiformis by L . pneumophila . Subsequent bacterial entry targets L . micdadei into a phagosome that is not surrounded by the rough endoplasmic reticulum (RER) . In contrast, uptake of L . pneumophila mediated by attachment to the Gal/GalNAc lectin is followed by targeting of the bacterium into an RER-surrounded phagosome . These results indicate that despite similarities in the L . micdadei and L . pneumophila attachment-mediated signal transduction mechanisms in H . vermiformis, the two bacterial species are targeted into morphologically distinct phagosomes in their natural protozoan host. J Immunol, 1998 Sep 1, 161(5), 2407 - 13 B7-1, but not CD28, is crucial for the maintenance of the CD4+ T cell responses in human leprosy; Schlienger K et al.; We used human leprosy as a model to compare patterns of costimulatory molecule expression in respect to the clinical/immunologic spectrum of disease . We found that B7-1, B7-2, and CD28 transcripts dominated in tuberculoid leprosy patients, who have potent T cell responses to Mycobacterium leprae . In contrast, CTLA-4 was more strongly expressed in lesions from lepromatous patients, who manifest specific T cell anergy to the leprosy bacterium . T cell clones from tuberculoid lesions were CD4+CD28+ or CD4+CD28-, and T cell clones from lepromatous lesions were predominantly CD8+CD28- . The M . leprae-specific recall response of CD4+ T cell clones from tuberculoid lesions was blocked by anti-B7-1 mAb, but not by anti-B7-2 mAb or CTLA-Ig . However, anti-CD28 and anti-CTLA-4 mAbs did not block activation of clones from tuberculoid lesions, suggesting that B7-1 may utilize another costimulatory pathway . Peripheral blood T cell responses in the lepromatous form were strongly regulated by CD28 during T cell activation, in contrast to the tuberculoid form . Thus, B7-1 costimulation could play a role in maintaining a strong immune response to the pathogen. Biochemistry, 1998 Sep 1, 37(35), 12293 - 300 Membrane-bound cytochrome cz couples quinol oxidoreductase to the P840 reaction center complex in isolated membranes of the green sulfur bacterium Chlorobium tepidum; Oh-oka H et al.; The reaction of quinol oxidoreductase and membrane-bound c-type cytochromes was studied in chlorosome-depleted membranes isolated from Chlorobium tepidum . Rapid oxidations of c-type cytochromes were detected after flash excitation . Their re-reductions occurred in parallel with the reduction of cytochrome b, especially in the presence of antimycin A, whereas reductions of both cytochromes c and b were suppressed by added stigmatellin . These results indicate the tight coupling between the photosynthetic reaction center and quinol oxidoreductase . Turnovers of two types of cytochromes c were detected . One was assigned to the monoheme-type cytochrome c (designated cytochrome cz), which is known to be tightly bound to the reaction center complex . The other was a new c-type cytochrome, cytochrome c-556, which functions the same as cytochrome c1 . The steps of electron-transfer scheme, menaquinol --> Rieske FeS center --> cytochrom c-556 --> cytochrome cz --> P840, are estimated to have reaction times of 20 ms and 560, 150, and 40 microseconds, respectively . We conclude that quinol oxidoreductase and the reaction center complex in Chlorobium tepidum are linked by two distinct membrane-bound cytochromes, cz and c-556, with no involvement of water-soluble cytochromes. Dig Dis Sci, 1998 Aug, 43(8), 1641 - 5 Helicobacter pylori eradication ameliorates primary Raynaud's phenomenon; Gasbarrini A et al.; Raynaud's phenomenon is defined by an intermittent vasospasm of the arterioles of the distal limbs . Helicobacter pylori infection has been recently associated with Raynaud's phenomenon . The aim of this study was to assess the effects of H . pylori eradication on Raynaud's attacks . Forty-six patients affected by primary Raynaud's phenomenon were evaluated . H . pylori infection was assessed by {13C}urea breath test . Eradication therapy was given to infected patients for seven days . Discomfort and the duration and frequency of attacks of Raynaud's phenomenon per week were assessed . Thirty-six subjects were infected with H . pylori; the bacterium was eradicated in 83% of these after therapy . Attacks of Raynaud's phenomenon completely disappeared in 17% of the patients with H . pylori eradication . Discomfort and the duration and frequency of attacks of Raynaud's phenomenon were significantly reduced in 72% of the remaining patients . Conversely, attacks of Raynaud's disease did not change significantly during the 12-week follow-up period either in the H . pylori-negative patients or in the infected subjects in whom the bacterium was not eradicated by therapy . The study shows that H . pylori eradication causes a significant decrease in clinical attacks of Raynaud's disease . The reduction of vasoactive substances determined by the eradication of the bacterium may be the pathogenetic mechanism underlying the phenomenon. Proc R Soc Lond B Biol Sci, 1998 Aug 7, 265(1404), 1447 - 52 Widespread occurrence of the micro-organism Wolbachia in ants; Wenseleers T et al.; For more than 20 years, sex allocation in hymenopteran societies has been a major topic in insect sociobiology . A recurring idea was that relatedness asymmetrics arising from their haplodiploid sex determination system would lead to various parent-offspring conflicts over optimal reproduction . A possible weakness of existing theory is that only interests of nuclear genes are properly accounted for . Yet, a diversity of maternally transmitted elements manipulate the reproduction of their host in many solitary arthropod groups . The bacterium Wolbachia is a striking example of such a selfish cytoplasmic element, with effects ranging from reproductive incompatibility between host strains, induction of parthenogenesis and feminization of males . This paper reports on a first PCR-based Wolbachia screening in ants . Out of 50 Indo-Australian species, 50% screened positive for an A-group strain . One of these species also harboured a B-group strain in a double infection . Various factors that might explain the unusually high incidence of Wolbachia in ants are discussed . In general, Wolbachia may represent a widespread and previously unrecognized party active in the conflicts of interest within social insect colonies. J Bacteriol, 1998 Sep, 180(17), 4325 - 31 Parallel and divergent genotypic evolution in experimental populations of Ralstonia sp; Nakatsu CH et al.; Genetic rearrangements within a population of bacteria were analyzed to understand the degree of divergence occurring after experimental evolution . We used 18 replicate populations founded from Ralstonia sp . strain TFD41 that had been propagated for 1,000 generations with 2,4-dichlorophenoxyacetic acid (2,4-D) as the carbon source . Genetic divergence was examined by restriction fragment length polymorphism analysis of the incumbent plasmid that carries the 2,4-D catabolic genes and by amplification of random regions of the genome via PCR . In 18 evolved clones examined, we observed duplication within the plasmid, including the tfdA gene, which encodes a 2,4-D dioxygenase that catalyzes the first step in the 2,4-D catabolic pathway . In 71 of 72 evolved clones, a common 2.4-kb PCR product was lost when genomic fingerprints produced by PCR amplification using degenerate primers based on repetitive extragenic palindromic (REP) sequences (REP-PCR) were compared . The nucleotide sequence of the 2.4-kb PCR product has homology to the TRAP (tripartite ATP-independent periplasmic) solute transporter gene family . Hybridization of the 2 . 4-kb REP-PCR product from the ancestor to genomic DNA from the evolved populations showed that the loss of the PCR product resulted from deletions in the genome . Deletions in the plasmid and presence and/or absence of other REP-PCR products were also found in these clones but at much lower frequencies . The common and uncommon genetic changes observed show that both parallel and divergent genotypic evolution occurred in replicate populations of this bacterium. Appl Microbiol Biotechnol, 1998 Jul, 50(1), 55 - 64 Analysis of the gene for beta-fructosidase (invertase, inulinase) of the hyperthermophilic bacterium Thermotoga maritima, and characterisation of the enzyme expressed in Escherichia coli; Liebl W et al.; This is the first report describing the gene structure and the enzymatic properties of a beta-fructosidase of a hyperthermophilic organism . The bfrA gene of the ancestral bacterium Thermotoga maritima MSB8 codes for a 432-residue, polypeptide of about 50 kDa, with significant sequence similarity to other beta-fructosidases . On the basis of its primary structure, BfrA can be assigned to glycosyl hydrolase family 32 . The bfrA gene was expressed in Escherichia coli and the recombinant enzyme was purified and characterised . BfrA was specific for the fructose moiety and the beta-anomeric configuration of the glycosidic linkages of its substrates . The enzyme released fructose from sucrose and raffinose, and the fructose polymer inulin was hydrolysed quantitatively in an exo-type fashion . BfrA displayed similar catalytic efficiencies for the hydrolysis of sucrose and inulin with Kcat/K(m) values (at 75 degrees C, pH 5.5) of about 4.1 x 10(4) M-1S-1 and 3.1 x 10(4) M-1S-1 respectively . BfrA had an optimum temperature of 90-95 degrees C (10-min assay) and was extremely insensitive to thermo-inactivation . During 5 h at temperatures up to 80 degrees C at pH 7, the enzyme retained at least 85% of its initial activity . Thus, BfrA is the most thermostable beta-fructosidase and also the most thermostable inulinase described to date . In conclusion, the T . maritima enzyme can be classified as an exo-beta-D-fructofuranosidase (EC 3.2.1.26) with invertase and inulinase activity . Its catalytic properties along with the extreme thermostability recommend it for use in biotechnology. Microbiology, 1998 Aug, 144 ( Pt 8), 2263 - 9 Phototrophic oxidation of ferrous iron by a Rhodomicrobium vannielii strain; Heising S et al.; Oxidation of ferrous iron was studied with the anaerobic phototrophic bacterial strain BS-1 . Based on morphology, substrate utilization patterns, arrangement of intracytoplasmic membranes and the in vivo absorption spectrum, this strain was assigned to the known species Rhodomicrobium vannielii . Also, the type strain of this species oxidized ferrous iron in the light . Phototrophic growth of strain BS-1 with ferrous iron as electron donor was stimulated by the presence of acetate or succinate as cosubstrates . The ferric iron hydroxides produced precipitated on the cell surfaces as solid crusts which impeded further iron oxidation after two to three generations . The complexing agent nitrilotriacetate stimulated iron oxidation but the yield of cell mass did not increase stoichiometrically under these conditions . Other complexing agents inhibited cell growth . Ferric iron was not reduced in the dark, and manganese salts were neither oxidized nor reduced . It is concluded that ferrous iron oxidation by strain BS-1 is only a side activity of this bacterium that cannot support growth exclusively with this electron source over prolonged periods of time. Microbiology, 1998 Aug, 144 ( Pt 8), 2195 - 202 Lysogenic bacteriophage M1 from Selenomonas ruminantium: isolation, characterization and DNA sequence analysis of the integration site; Cheong JP et al.; Bacteriophage M1 from the ruminal bacterium Selenomonas ruminantium strain ML12 comprises a 30 nm icosahedral capsid, a 25 nm tail and 48 kb of linear dsDNA with cohesive ends . A restriction map of the phage genome has been constructed . The presence of bacteriophage M1 in the rumen has been demonstrated by PCR amplification and Southern blot analysis of DNA from rumen bacterial samples obtained from ten different sheep . Lysogeny was demonstrated by hybridization of M1 DNA to host chromosomal DNA and by identification and cloning of a 2.3 kb region of the phage containing the predicted attP domain which promotes chromosomal integration . DNA sequencing of the attP region demonstrated two major ORFs surrounding the predicted attP site and structural analysis of this region revealed a motif comprising three different inverted repeats surrounding a 12 bp palindrome . Analysis of the translated amino acid sequence upstream of the attP site demonstrated the presence of conserved residues found within integrase proteins of several temperate phages of different bacterial species. Biochim Biophys Acta, 1998 Jul 31, 1393(1), 57 - 62 Novel glycine containing glucolipids from the alkane using bacterium Alcanivorax borkumensis; Abraham WR et al.; The polar lipids from the hydrocarbon using and biosurfactant-producing bacterium Alcanivorax borkumensis were isolated and identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy . The biosurfactant produced by this species is an anionic glucose lipid with a tetrameric oxyacyl side chain . The glycolipids extracted from the cell wall consist of this biosurfactant N-terminally esterified with glycine . Ten different derivatives of this lipid type were identified and their structures elucidated by MSMS . They vary by the chain length of one or two of the four beta-hydroxy fatty acids (C6, C8 and C10) and by the location of these different fatty acids within the molecule . All compounds are reported here for the first time . In addition to these glycolipids, three different phosphatidylglycerols were identified . While these lipids were found in all strains of A . borkumensis, the relative abundances of the different lipids vary between the strains. J Food Prot, 1998 Aug, 61(8), 929 - 33 Effect of environmental and substrate factors on survival and growth of Helicobacter pylori; Jiang X et al.; The effect of temperature (4 to 42 degrees C), NaCl concentration (0.5 to 7.5%), NaNO2 concentration (0 to 400 micrograms/ml), water activity (aw level of 0.6 to 0.995), pH (3.5 to 7.3) and urea (8 mM) on the survival and growth of Helicobacter pylori in a nutrient-rich laboratory culture medium was investigated . Under microaerobic conditions (5% O2, 10% CO2, and 85% N2), the organism grew well in brain heart infusion broth supplemented with 7% horse serum and antibiotics (BHI-HS-TVA) in a temperature range of 30 to 37 degrees C with agitation . H . pylori (initial population of ca . 5 x 10(3) CFU/ml) survived for 14 days at 4 degrees C, for 2 days at 25 degrees C, and for less than 1 day at 40 and 42 degrees C . The optimal NaCl concentration for growth of H . pylori was 0.5 to 1.0%; 2.0% NaCl inhibited growth . Up to 400 micrograms of NaNO2 per ml did not prevent growth . The minimum aw (adjusted with glycerol) and pH (acidified with HCl) for growth of H . pylori was 0.98 and 4.5, respectively . The addition of urea to broth greatly enhanced the growth of H . pylori at both pH 4.5 and 5.5 . Although H . pylori did not grow at pH 3.5, the presence of urea in broth enhanced its survival . Considering the apparent fastidious conditions for growth of H . pylori in BHI-HS-TVA broth, H . pylori is unlikely to grow well, if at all, in most foods . The bacterium may, however, survive for extended periods of time in low acid-high moisture environments under refrigerated storage. Infect Immun, 1998 Sep, 66(9), 4450 - 60 Early events in phagosome establishment are required for intracellular survival of Legionella pneumophila; Wiater LA et al.; During infection, the Legionnaires' disease bacterium, Legionella pneumophila, survives and multiplies within a specialized phagosome that is near neutral pH and does not fuse with host lysosomes . In order to understand the molecular basis of this organism's ability to control its intracellular fate, we have isolated and characterized a group of transposon-generated mutants which were unable to kill macrophages and were subsequently found to be defective in intracellular multiplication . These mutations define a set of 20 genes (19 icm {for intracellular multiplication} genes and dotA {for defect in organelle trafficking}) . In this report, we describe a quantitative assay for phagosome-lysosome fusion (PLF) and its use to measure the levels of PLF in cells that have been infected with either wild-type L . pneumophila or one of several mutants defective in different icm genes or dotA . By using quantitative confocal fluorescence microscopy, PLF could be scored on a per-bacterium basis by determining the extent to which fluorescein-labeled L . pneumophila colocalized with host lysosomes prelabeled with rhodamine-dextran . Remarkably, mutations in the six genes that were studied resulted in maximal levels of PLF as quickly as 30 min following infection . These results indicate that several, and possibly all, of the icm and dotA gene products act at an early step during phagosome establishment to determine whether L . pneumophila-containing phagosomes will fuse with lysosomes . Although not ruled out, subsequent activity of these gene products may not be necessary for successful intracellular replication. Infect Immun, 1998 Sep, 66(9), 4050 - 5 Expression of mucin-type glycoprotein K88 receptors strongly correlates with piglet susceptibility to K88(+) enterotoxigenic Escherichia coli, but adhesion of this bacterium to brush borders does not; Francis DH et al.; Three antigenic variants of the K88 fimbrial adhesin exist in nature, K88ab, K88ac, and K88ad . Enterotoxigenic Escherichia coli (ETEC) strains that produce these fimbriae cause life-threatening diarrhea in some but not all young pigs . The susceptibility of pigs to these organisms has been correlated with the adherence of bacteria to isolated enterocyte brush borders . Whether that correlation holds for multiple K88 variants and over a broad genetic base of pigs is unknown and was the impetus for this study . We also desired to examine the correlation of the expression of a porcine intestinal brush border mucin-type glycoprotein (IMTGP) which binds K88ab and K88ac with the susceptibility of piglets to K88(+) ETEC . Of 31 neonatal gnotobiotic pigs inoculated with K88ab+ or K88ac+ ETEC, 13 developed severe diarrhea, became dehydrated, and died or became moribund . Another pig became severely lethargic but not dehydrated . In vitro brush border adherence analysis was not possible for 10 of the severely ill pigs due to colonization by challenge strains . However, of the 17 pigs that did not become severely ill, 8 (47%) had brush borders that supported the adherence of K88ab+ and K88ac+ bacteria in vitro, suggesting a poor correlation between in vitro brush border adherence and piglet susceptibility to K88(+) ETEC . By contrast, the expression of IMTGP was highly correlated with susceptibility to K88(+) ETEC . Of the 12 pigs that produced IMTGP, 11 developed severe diarrhea . The other pig that produced IMTGP became lethargic but not severely diarrheic . Only 2 of 18 pigs that did not produce IMTGP became severely diarrheic . Colonizing bacteria were observed in histologic sections of intestines from all pigs that expressed IMTGP except for the one that did not develop severe diarrhea . However, colonizing bacteria were observed in histologic sections from only one pig that did not produce IMTGP . The bacterial concentration in the jejuna and ilea of pigs expressing IMTGP was significantly greater (P < 0.005) than that in pigs not expressing IMTGP . These observations suggest the IMTGP is a biologically relevant receptor for K88ab+ and K88ac+ E . coli or a correlate for expression for such a receptor. Infect Immun, 1998 Sep, 66(9), 4030 - 5 Route of infection that induces a high intensity of gamma interferon-secreting T cells in the genital tract produces optimal protection against Chlamydia trachomatis infection in mice; Igietseme JU et al.; The induction of local T helper type 1 (Th1)-mediated cellular immunity is crucial for resistance of mice to genital infection by the obligate intracellular bacterium Chlamydia trachomatis . We tested the hypothesis that the route of immunization that elicits relatively high numbers of chlamydia-specific, gamma interferon (IFN-gamma)-secreting T lymphocytes (ISTLs) in the genital tract would induce optimal protective immunity against reinfection . Female BALB/c mice were infected intravaginally (i.v.), intranasally (i.n.), orally (p.o.), or subcutaneously (s.c.) with C . trachomatis . At days 7, 14, 21, and 28 postinfection, T cells isolated from the genital tract tissues were restimulated with chlamydial antigen in vitro, and the amounts of IFN-gamma induced were measured by a sandwiched enzyme-linked immunosorbent assay method . At day 7 postinfection, i.n.- and i.v.-immunized mice had high levels of chlamydia-specific ISTLs in their genital tracts (203.58 +/- 68.1 and 225.5 +/- 12.1 pg/ml, respectively) . However, there were no detectable ISTLs in the genital tracts of p.o.- or s.c.-infected mice . When preinfected mice were challenged i.v . 70 days later, animals preexposed by the i.n . route were highly resistant to reinfection, with greatly reduced chlamydial burden, and suffered an attenuated infection that resolved by day 6 postchallenge . Animals preexposed by the i.v . route were modestly protected, whereas p.o . and s.c . groups were indistinguishable in this regard from control mice . The resistance of i.n.-immunized mice (and to some extent the i.v.-exposed mice) to reinfection was associated with early appearance (within 24 h) of high levels of genital ISTLs compared with mice preinfected by other routes . Furthermore, although i.n . and i.v.-immunized mice had comparable levels of chlamydia-specific immunoglobulin A (IgA) antibodies in their vaginal washes, the levels of IgG2a were four- sixfold higher in i.n.-immunized mice than in any of the other groups . The results suggested that immunization routes that foster rapid induction of vigorous genital mucosal cell-mediated immune (CMI) effectors (e.g., IFN-gamma), the CMI-associated humoral effector, IgG2a, and to some extent secretory IgA produce protective immunity against chlamydial genital infection . Therefore, i.n . immunization is a potential delivery route of choice in the development of a vaccine against Chlamydia. Biochim Biophys Acta, 1998 Jul 20, 1365(3), 435 - 42 Stopped-flow kinetic studies of low potential electron carriers of the photosynthetic bacterium, Rhodobacter capsulatus: ferredoxin I and NifF; Hallenbeck PC et al.; The kinetics of electron-transfer reactions involving nif-specific proteins from Rhodobacter capsulatus; ferredoxin I, NifF, Fe-protein of nitrogenase and dithionite were studied using stopped-flow spectrophotometry . Kinetic evidence was obtained for the formation of a tight (0.44 microM) complex between NifF and Fe-protein . Under the same conditions, FdI interacted only weakly (Kd > 325 microM) with Fe-protein . There was no evidence for complex formation between NifF and FdI since the reaction NifFSQ + FdIred had a bimolecular rate constant of 12.5 +/- 1.2 x 10(3) M-1 s-1 . These results suggest that NifF, which is present in only small quantities in the cell, can make a significant contribution to the overall rate of nitrogen fixation due its high reactivity with Fe-protein . Moreover, the apparent lack of specific interaction between NifF and FdI suggest that they act in vivo in parallel to reduce Fe-protein and not in series. Fold Des, 1998, 3(4), 229 - 38 Fold and function predictions for Mycoplasma genitalium proteins; Rychlewski L et al.; BACKGROUND: Uncharacterized proteins from newly sequenced genomes provide perfect targets for fold and function prediction . RESULTS: For 38% of the entire genome of Mycoplasma genitalium, sequence similarity to a protein with a known structure can be recognized using a new sequence alignment algorithm . When comparing genomes of M . genitalium and Escherichia coli, > 80% of M . genitalium proteins have a significant sequence similarity to a protein in E . coli and there are > 40 examples that have not been recognized before . For all cases of proteins with significant profile similarities, there are strong analogies in their functions, if the functions of both proteins are known . The results presented here and other recent results strongly support the argument that such proteins are actually homologous . Assuming this homology allows one to make tentative functional assignments for > 50 previously uncharacterized proteins, including such intriguing cases as the putative beta-lactam antibiotic resistance protein in M . gentalium . CONCLUSIONS: Using a new profile-to-profile alignment algorithm, the three-dimensional fold can be predicted for almost 40% of proteins from a genome of the small bacterium M . genitalium, and tentative function can be assigned to almost 80% of the entire genome . Some predictions lead to new insights about known functions or point to hitherto unexpected features of M . genitalium. FEBS Lett, 1998 Jul 31, 432(1-2), 27 - 30 The effect of chemical oxidation on the fluorescence of the LH1 (B880) complex from the purple bacterium Rhodobium marinum; Law CJ et al.; The effect of chemical oxidation on the absorption and fluorescence emission spectra of the LH1 complex from Rhodobium marinum was investigated . Mild chemical oxidation of the LH1 complex, by addition of 10 mM potassium ferricyanide, caused a 2-3% bleaching of the 880-nm Qy absorption band . In contrast, at the same ferricyanide concentration, fluorescence emission intensity of the LH1 complex was quenched by about 50% . This result demonstrates that oxidation of very few bacteriochlorophyll (BChl) molecules in the LH1 ring is enough to completely quench its fluorescence. J Membr Biol, 1998 Sep 1, 165(1), 65 - 76 Characterization of fumarate transport in Helicobacter pylori; Mendz GL et al.; The fumarate transport system of the bacterium Helicobacter pylori was investigated employing radioactive tracer analysis . The transport of fumarate at micromolar concentrations was saturable with a KM of 220 +/- 21 micron and Vmax of 54 +/- 2 nmole/min/mg protein at 20 degrees C, depended on temperature between 4 and 40 degrees C, and was susceptible to inhibitors, suggesting the presence of one or more fumarate carriers . The release of fumarate from cells was also saturable with a KM of 464 +/- 71 micron and Vmax of 22 +/- 2 nmol/min/mg protein at 20 degrees C . The rates of fumarate influx at millomolar concentrations increased linearly with permeant concentration, and depended on the age of the cells . The transport system was specific for dicarboxylic acids suggesting that fumarate is taken up via dicarboxylate transporters . Succinate and fumarate appeared to form an antiport system . The properties of fumarate transport were elucidated by investigating the effects of amino acids, monovalent cations, pH and potential inhibitors . The results provided evidence that influx and efflux of fumarate at low concentrations from H . pylori cells was a carrier-mediated secondary transport with the driving force supplied by the chemical gradient of the anion . The anaerobic C4-dicarboxylate transport protein identified in the genome of the bacterium appeared to be a good candidate for the fumarate transporter. J Biol Chem, 1998 Aug 21, 273(34), 21669 - 74 The bacterial irr protein is required for coordination of heme biosynthesis with iron availability; Hamza I et al.; Heme is a ubiquitous macromolecule that serves as the active group of proteins involved in many cellular processes . The multienzyme pathway for heme formation culminates with the insertion of iron into a protoporphyrin ring . The cytotoxicity of porphyrins suggests the need for coordination of its biosynthesis with iron availability . We isolated a mutant strain of the bacterium Bradyrhizobium japonicum that, under iron limitation, accumulated protoporphyrin and showed aberrantly high expression of hemB, an iron-regulated gene encoding the heme synthesis enzyme delta-aminolevulinic acid dehydratase . The strain carries a loss of function mutation in irr, a newly described gene that encodes a putative member of the GntR family of bacterial transcriptional regulators . Irr accumulated only under iron limitation, and turned over rapidly upon an increase in iron availability . A separate role for Irr in controlling the cellular iron level was inferred based on a deficiency in high affinity iron transport activity in the irr strain, and suggests that regulation of the heme pathway is coordinated with iron homeostasis . A high level of protoporphyrin accumulation is not a normal consequence of nutritional iron deprivation, thus a mechanism for iron-dependent control of heme biosynthesis may be present in other organisms. Biochem Biophys Res Commun, 1998 Jul 30, 248(3), 505 - 10 Induction of KDNase Sm, a deaminoneuraminic acid (KDN) residue-specific sialidase from Sphingobacterium multivorum, using synthetic KDN-glycosides; Fuchizawa S et al.; Various aryl and alkyl alpha-glycosides of KDN were synthesized and tested as substrates for their susceptibility to a deaminoneuraminic acid (KDN)-specific sialidase from Sphingobacterium multivorum, designated KDNase Sm . The synthetic KDN-glycosides were all hydrolyzed by the action of KDNase Sm . A hydroxyl group at C-5 position of KDN was required for the recognition by the enzyme, and was shown not to be replaced by an amino- or an acylamino group for the enzymatic recognition . These synthetic KDN-glycosides were also examined for their inducing activity of KDNase in S . multivorum and were shown to induce the KDNase activity effectively when the bacterium was cultured minimum salt medium containing both 0.1% glucose and 0.1% various KDN-glycosides . No KDNase activity was induced by the KDN-glycosides without 0.1% glucose . This is the first case of using synthetic KDN-glycosides as inducers of KDNase Sm. Invasion Metastasis, 1997, 17(3), 138 - 48 Bacterium-assisted invasion of Entamoeba histolytica through human enteric epithelia in two-compartment chambers; Leroy A et al.; Entamoeba histolytica trophozoites initiate amebiasis by invasion into the enteric mucosa . It is the aim of our experiments to understand how bacteria and leukocytes act during amebic invasion through enteric cell layers . Cocultures were established in two-compartment chambers and studied by measurement of transepithelial electrical resistance (TER) and by histological examination . Trophozoites caused a decrease in TER that was followed by formation of holes in the enteric cell layer and transfilter migration of trophozoites . Phagocytosed bacteria activated trophozoites that opened the intracellular junctions and provided access for the invasion of bacteria . Leukocytes had no effect on the different steps of invasion of the trophozoites through the human enteric cell layers . We conclude that trophozoites, eventually assisted by enteric bacteria, disrupt enterocytic tight junctions before they open the enteric cell layer and invade through it. Aliment Pharmacol Ther, 1998 Feb, 12 Suppl 1, 25 - 36 Review article: Relationship between Helicobacter pylori, atrophic gastritis and gastric cancer; Kuipers EJ; Helicobacter pylori causes chronic active inflammation of the gastric mucosa in the majority of infected patients . In a considerable number of them, this will eventually lead to a loss of gastric glands, and thus the establishment of atrophic gastritis . This is associated with the development of intestinal metaplasia and dysplasia . These consecutive conditions increase the risk for gastric cancer . particularly of the intestinal type . We reviewed the evidence that H . pylori plays an important role in this sequence of events that can lead to gastric cancer . This paper focuses on the difficulties in staging atrophic gastritis, the incidence and prevalence of this condition and the relation with H . pylori infection . Furthermore, it describes the evidence for the role of this organism and gastric mucosal atrophy in the aetiology of gastric cancer and focuses on the life-time incidence of gastric cancer in the presence of this bacterium. Dev Comp Immunol, 1998 Jul-Aug, 22(4), 417 - 32 Production of a macrophage growth factor(s) by a goldfish macrophage cell line and macrophages derived from goldfish kidney leukocytes; Neumann NF et al.; We recently established a spontaneously proliferating macrophage cell line from the goldfish (GMCL), and in this report demonstrate the production of a macrophage-specific growth factor(s) (MGFs) by these cells . The supernatants from GMCL cultures induced proliferation and differentiation of macrophage-like cells from kidney hematopoietic tissues of goldfish . Kidney leukocytes cultured at 6.25 x 10(4)cells/ml in the presence of GMCL-derived MGFs proliferated during two weeks of cultivation, whereas those cultured without the MGFs did not . Leukocytes cultured at higher densities (2.5 x 10(5) cells/ml) proliferated in the absence of exogenous growth factor, but not to the same extent as those stimulated with GMCL-derived MGFs, suggesting that kidney leukocytes may produce endogenous MGFs . At higher cell density (1 x 10(6) cells/ml), kidney leukocytes multiplied extensively over a two-week cultivation period in the absence of exogenous GMCL-derived MGFs . The supernatants from these cultures restored the proliferative ability of leukocytes cultured at low densities, providing direct evidence of MGFs production by kidney leukocytes . The predominant cell-type in cultures grown in the presence of GMCL or kidney leukocyte-MGFs was the macrophage based on the following criteria: (1) non-specific esterase staining; (2) morphologic similarity to GMCL; (3) phagocytosis of the bacterium, A . salmonicida; (4) production of reactive oxygen and nitrogen intermediates in response to stimulation with macrophage activating factors and/or bacterial lipopolysaccharide; and (5) flow cytometric analyses . Both in vitro-derived kidney macrophage (IVDKM) and GMCL cultures contained three distinct populations of cells, (determined by flow cytometry), suggesting that these macrophage cultures are comprised of cells arrested at distinct differentiation junctures in macrophage development . Production of MGFs by macrophages and kidney leukocytes may play an important role in regulating macrophage hematopoiesis in fish. Braz J Med Biol Res, 1998 Mar, 31(3), 373 - 6 Mouse inoculation for the detection of non-cultivable gastric tightly spiralled bacteria; Mendes EN et al.; In the present study we compared the inoculation of swine gastric mucus into the stomach of mice, the ureas test and carbolfuchsin-stained smears for the diagnosis of the infection with "Gastrospirillum suis" ("Helicobacter heilmannii" type 1), an uncultivated tightly spiralled gastric bacterium . Fragments obtained from the antral and oxyntic mucosa of the stomach of 50 slaughtered pigs were used for urease test, for carbolfuchsin-stained smears and for obtaining scrapings of mucus for mouse inoculation . The mice were killed by spinal dislocation 10 days after inoculation and fragments of the antral and oxyntic mucosa were used for spiral bacterium identification (urease test and carbolfuchsin-stained smears) . Among the methods employed for the diagnosis of "H . heilmannii" infection, the inoculation of gastric mucus into the stomach of mice was the most sensitive and demonstrated bacterial positivity in 31 (62.0%) swine . Direct examination showed tightly spiralled bacteria in the gastric mucosa of only 4 (8.0%) of the 50 pigs studied . Among them, 3 (6.0%) presented a positive preformed urease test . Spiral bacteria were not seen in the gastric mucosa of any control mice . These results show that the use of the mouse inoculation method improved the detection of "H . heilmannii" in swine. Clin Exp Immunol, 1998 Jul, 113(1), 105 - 10 Characteristics of Prevotella intermedia-specific CD4+ T cell clones from peripheral blood of a chronic adult periodontitis patient; Wassenaar A et al.; Periodontitis is a chronic destructive inflammatory disease associated with periodontopathic bacteria . In addition, autoantigens such as collagen and heat shock proteins (hsp) have been suggested to play a role . Established periodontal lesions are characterized by dense infiltrations of immune cells such as cytokine-producing CD4+ and CD8+ T cells . CD4+ T cells specific for Prevotella intermedia can be isolated from lesional gingiva, suggesting an active role for CD4+ T cells in the response to this bacterium . We therefore investigated the characteristics of a panel of 13 P . intermedia-specific CD4+ T cells generated from the peripheral blood of a patient with chronic adult periodontitis . All 13 P . intermedia-specific CD4+ T cells recognized the antigens in the context of HLA-DR . The T cell clones were mainly classified as Th0, producing comparable amounts of interferon-gamma (IFN-gamma) and IL-4, and Th2, producing high amounts of IL-4 and almost no IFN-gamma . None of the P . intermedia-specific T cell clones recognized antigens of the periodontopathic bacteria Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis and of the autoantigens collagen and hsp . The reactivity profile of the T cell clones to size-fractionated cell envelope antigens of P . intermedia indicated that P . intermedia-specific CD4+ T cell clones recognize probably five different antigen specificities in the context of the MHC class II molecules, DR7 or DR15 . These results suggest that a broad panel of cell-associated protein antigens play a role in the induction of P . intermedia-specific CD4+ T cell response. Microbiology, 1998 Jul, 144 ( Pt 7), 1881 - 94 Sirohaem sulfite reductase and other proteins encoded by genes at the dsr locus of Chromatium vinosum are involved in the oxidation of intracellular sulfur; Pott AS et al.; The sequence of the dsr gene region of the phototrophic sulfur bacterium Chromatium vinosum D (DSMZ 180) was determined to clarify the in vivo role of 'reverse' sirohaem sulfite reductase . The dsrAB genes encoding dissimilatory sulfite reductase are part of a gene cluster, dsrABEFHCMK, that encodes four small, soluble proteins (DsrE, DsrF, DsrH and DsrC), a transmembrane protein (DsrM) with similarity to haem-b-binding polypeptides and a soluble protein (DsrK) resembling {4Fe-4S}-cluster-containing heterodisulfide reductase from methanogenic archaea . Northern hybridizations showed that expression of the dsr genes is increased by the presence of reduced sulfur compounds . The dsr genes are not only transcribed from a putative promoter upstream of dsrA but primary transcripts originating from (a) transcription start site(s) downstream of dsrB are also formed . Polar insertion mutations immediately upstream of dsrA, and in dsrB, dsrH and dsrM, led to an inability of the cells to oxidize intracellularly stored sulfur . The capability of the mutants to oxidize sulfide, thiosulfate and sulfite under photolithoautotrophic conditions was unaltered . Photoorganoheterotrophic growth was also unaffected . 'Reverse' sulfite reductase and DsrEFHCMK are, therefore, not essential for oxidation of sulfide or thiosulfate, but are obligatory for sulfur oxidation . These results, together with the finding that the sulfur globules of C . vinosum are located in the extracytoplasmic space whilst the dsr gene products appear to be either cytoplasmic or membrane-bound led to the proposal of new models for the pathway of sulfur oxidation in this phototrophic sulfur bacterium. Microbiology, 1998 Jul, 144 ( Pt 7), 1869 - 79 Evidence of past recombination events among the genes encoding the Erp antigens of Borrelia burgdorferi; Stevenson B et al.; A single Borrelia burgdorferi bacterium may contain six or more different 32 kb circular plasmids (cp32s) . Although these plasmids are homologous throughout much of their sequences, two loci have been identified at which they can vary significantly . The cp32 plasmids and their relatives each contain two adjacent genes, orfC and orf3, that vary in sequence between plasmids found within clones of individual bacteria . The orfC gene product is homologous to proteins involved in partitioning of bacterial plasmids, and the differences at this locus between plasmids may account for their compatibility . The orfC-orf3 loci are located approximately 5 kb from another variable locus called erp . The orfC-orf3 loci were used as physically linked markers to assess genetic rearrangements in the erp loci; this revealed examples of recombination involving both individual genes and entire erp loci . Recombination of the genes encoding the Erp antigens might contribute to the evasion of the mammalian immune response and could play roles in the establishment and persistence of B . burgdorferi infections in mammalian hosts. Parasitology, 1998 Jul, 117 ( Pt 1), 15 - 9 Horizontal transfer of parasitic sex ratio distorters between crustacean hosts; Dunn AM et al.; Parasitic sex distorters were artificially transferred within and between crustacean host species in order to study the effects of parasitism on host fitness and sex determination and to investigate parasite host specificity . Implantation of Nosema sp . to uninfected strains of its Gammarus duebeni host resulted in an active parasite infection in the gonad of recipient females and subsequent transovarial parasite transmission . The young of artificially infected females were feminized by the parasite, demonstrating that Nosema sp . is a cause of a sex ratio distortion in its host . In contrast, we were unable to cross-infect Armadillidium vulgare with the feminizing microsporidian from G . duebeni or to cross-infect G . duebeni with the feminizing bacterium Wolbachia sp . from A . vulgare. Ophthalmologica, 1998, 212(5), 344 - 6 Bilateral optic papillitis following mycoplasma pneumoniae pneumonia; Milla E et al.; Mycoplasma pneumoniae is an atypical bacterium that can cause a great variety of respiratory infections and be responsible for ocular involvement such as conjunctivitis, anterior uveitis and very rarely optic neuropathy . We report herein an additional case of bilateral optic disc swelling with profound visual loss following Mycoplasma pneumoniae pneumonia and review the world literature on the ocular manifestations associated with this pathogen. Digestion, 1998 Jul-Aug, 59(4), 314 - 20 Helicobacter pylori infection decreases gastric alcohol dehydrogenase activity and first-pass metabolism of ethanol in man; Simanowski UA et al.; BACKGROUND/AIMS: Ethanol is metabolized by alcohol dehydrogenase in the human stomach . This metabolism contributes to the so-called first-pass metabolism of ethanol which is affected by gender, medication, and morphological alterations of the gastric mucosa . Recently, it has been shown that Helicobacter pylori is capable to oxidize ethanol to acetaldehyde in vitro . Since H . pylori also injures gastric mucosa, the present study examines the effect of this bacterium on gastric alcohol dehydrogenase activity and systemic availability of ethanol in vivo . METHODS: Thirteen volunteers (7 men and 6 women, aged 18-52 years) with gastric H . pylori infection diagnosed by a positive CLO test and positive gastric histology received ethanol (0.225 g/kg) either orally or intravenously before and after H . pylori elimination to determine systemic availability of ethanol . In addition, gastric biopsy specimens were taken from all subjects before and after H . pylori elimination for histological assessment of mucosal alterations and determinations of gastric alcohol dehydrogenase activity and phenotype of the enzyme . RESULTS: In the presence of H . pylori the first-pass metabolism of ethanol was found to be significantly reduced (625 +/- 234 vs . 1,155 +/- 114 mg/dl/min, p = 0.046) . This reduction of first-pass metabolism of ethanol was associated with a significant decrease in alcohol dehydrogenase activity (4.8 +/- 1.5 vs . 12.1 +/- 2.3 nmol/mg protein x min, p < 0.05) and an increase in the severity of mucosal damage as determined by a histological score (p < 0.05) . CONCLUSIONS: H . pylori infection leads to gastric mucosal injury which is associated with a decrease in gastric alcohol dehydrogenase activity and first-pass metabolism of ethanol . Ethanol metabolism by H . pylori does not play an important role in vivo . However, gastric morphology is one important factor determining systemic availability of ethanol in man. Biochemistry, 1998 Jul 28, 37(30), 10792 - 7 Excited states and trapping in reaction center complexes of the green sulfur bacterium Prosthecochloris aestuarii; Neerken S et al.; The excited states of bacteriochlorophyll (BChl) a were studied by pump-probe transient absorption spectroscopy in reaction center core (RCC), Fenna-Matthews-Olson (FMO) and FMO-RCC complexes of the green sulfur bacterium Prosthecochloris aestuarii . Excitation at 790 or 835 nm resulted in rapid equilibration of the energy between the BChl a molecules of the RCC complex: within 1 ps, most of the excitations had relaxed to the lowest energy level (835 nm), as a result of strong interactions between the BChls . Excitation of chlorophyll a 670 resulted in energy transfer to BChl a with a time constant of 1.2 ps, followed by thermal equilibration . Independent of the wavelength of excitation, the decay at 835 nm could be fitted with a time constant of about 25 ps, comparable to the 30 ps measured earlier with membrane fragments, which is ascribed to trapping in the reaction centers . Similar results were obtained with the FMO-RCC complex upon excitation at 835 or 670 nm, but the results upon 790 nm excitation were quite different . Again an equilibrium was rapidly reached, but now most of the excitations remained within the FMO complex, with a maximum bleaching at 813 nm, the same as observed in the isolated FMO . Even after 100 ps there was no bleaching at 835 nm and no evidence for charge separation . We conclude that there is no equilibration of the energy between the FMO and the RCC complex and that the efficiency of energy transfer from FMO to the reaction center core is low. Biosci Biotechnol Biochem, 1998 Jun, 62(6), 1138 - 43 Isolation and chemical composition of the sheath of Sphaerotilus natans; Takeda M et al.; A sheathed bacterium, Sphaerotilus natans, was cultured with vigorous shaking in a medium containing peptone . Then the biomass was harvested and treated with lysozyme, sodium dodecyl sulfate, and protease . With treatment, 1.6 mg of sheaths was obtained from 15 mg of biomass . For the preparation of sheaths of high purity, cultivation must be in the absence of glucose with sufficient aeration to prevent poly(3-hydroxybutyrate) accumulation . Carbohydrate (54.1%), protein (12.2%), and lipid (1-3%) were detected in the sheaths by colorimetric reactions and solvent extraction . Gas-liquid chromatography showed glucose and galactosamine to be present in the molar ratio of 1:4 . The most abundant amino acids in the sheath protein were glycine (49.2 mol%) and cysteine (24.6 mol%) . The sheaths were resistant to agents that reduce disulfide bonds (dithiothreitol and 2-mercaptoethanol) and to protease . However, sheathes were degraded completely by hydrazine, and a heteropolysaccharide composed of glucose and galactosamine (1:4) was released . The weight-average molecular weight of the polysaccharide was estimated to be 1.2 x 10(5) by gel filtration chromatography with a low-angle laser-light scattering photometer and a rotation index detector . A ladder of 1.5-kDa peptides separable by sodium dodecyl sulfate gel electrophoresis was obtained by partial hydrolysis of sheaths, suggesting the sheath protein has repeating units of 1.5 kDa. Biosci Biotechnol Biochem, 1998 Jun, 62(6), 1081 - 6 Isolation and some properties of cytochrome c oxidase purified from a bisulfite ion resistant Thiobacillus ferrooxidans strain, OK1-50; Iwahori K et al.; Sulfite ion (HSO3-) is one of the products when elemental sulfur is oxidized by the hydrogen sulfide:ferric ion oxidoreductase of Thiobacillus ferrooxidans AP19-3 . Under the conditions in which HSO3- is accumulated in the cells, the iron oxidase of this bacterium was strongly inhibited by HSO3- . Since cytochrome c oxidase is one of the most important components of the iron oxidase enzyme system in T . ferrooxidans, effects of HSO3- on cytochrome c oxidase activity were studied with the plasma membranes of HSO3(-)-resistant and -sensitive strains of T . ferrooxidans, OK1-50 and AP19-3 . The enzyme activity of AP19-3 compared with OK1-50 was strongly inhibited by HSO3- . To investigate the inhibition mechanism of HSO3- in T . ferrooxidans, cytochrome c oxidases were purified from both strains to an electrophoretically homogeneous state . Cytochrome c oxidase activity of a purified OK1-50 enzyme was not inhibited by 5 mM HSO3- . In contrast, the same concentration of HSO3- inhibited the enzyme activity of AP19-3 50%, indicating that the cytochrome c oxidase of OK1-50 was more resistant to HSO3- than that of AP19-3 . Cytochrome c oxidases purified from both strains were composed of three subunits . However, the molecular weight of the largest subunit differed between OK1-50 and AP19-3 . Apparent molecular weights of the three subunits of cytochrome c oxidases were 53,000, 24,000, and 19,000 for strain AP19-3 and 55,000, 24,000, and 19,000 for strain OK1-50, respectively. Biosci Biotechnol Biochem, 1998 Jun, 62(6), 1068 - 74 alpha-L-rhamnosidase of Sphingomonas sp . R1 producing an unusual exopolysaccharide of sphingan; Hashimoto W et al.; A soil bacterium with alpha-L-rhamnosidase was isolated from a cumulative mixed culture containing a polysaccharide of gellan as a carbon source and identified to be Sphingomonas paucimobilis, known as a potent producer of gellan . The isolate (designated Sphingomonas sp . R1) produced an unusual exopolysaccharide of sphingan (denoted HWR1) distinct from gellan . The rhamnose in gellan was replaced with mannose in HWR1 . The bacterium had a peculiar cell surface covered with many complicated plaits . alpha-L-Rhamnosidase purified from Sphingomonas sp . R1 grown in the presence of naringin was a monomer with a molecular mass of 110 kDa and most active at pH 8.0 and 50 degrees C . The enzyme required divalent metal ions for the activity and released L-rhamnose from various rhamnosyl glycosides. Biosci Biotechnol Biochem, 1998 Jun, 62(6), 1061 - 7 Gene cloning and characterization of an acidic xylanase from Acidobacterium capsulatum; Inagaki K et al.; The gene xynA encoding an acid endo-beta-1,4-xylanase from an acidophilic bacterium, Acidobacterium capsulatum 161, was cloned and expressed in Eschrichia coli . The nucleotide sequence of the 1.6-kb DNA fragment containing xynA was analyzed, revealing an open reading frame of 1,215 bp encoding a peptide of 405 amino acid residues . The deduced amino acid sequence of XynA was very similar to other xylanases that are from the glycosyl hydrolase family 10 . XynA was purified to homogeneity by SDS-polyacrylamide gel electrophoresis from E . coli transformants . The molecular mass and isoelectric point of XynA were 41 kDa and 7.3, respectively . The xylanase activity of the cloned XynA is an endo-acting enzyme that shows optimal activity at pH 5.0 and 65 degrees C, and is stable pH between 3.0 and 8.0 . The K(m) and Vmax with oat spelt xylan as a substrate at pH 5.0 and 30 degrees C are 3.5 mg/ml and 403 mumol/min/mg. Gut, 1998 Jun, 42(6), 768 - 71 Reactive oxygen species activity and lipid peroxidation in Helicobacter pylori associated gastritis: relation to gastric mucosal ascorbic acid concentrations and effect of H pylori eradication; Drake IM et al.; BACKGROUND: Helicobacter pylori is an independent risk factor for gastric cancer, and this association may be due to the bacterium causing reactive oxygen species mediated damage to DNA in the gastric epithelium . High dietary ascorbic acid intake may protect against gastric cancer by scavenging reactive oxygen species . AIMS: To assess reactive oxygen species activity and damage in gastric mucosa in relation to gastric pathology and mucosal ascorbic acid level, and to determine the effect of H pylori eradication on these parameters . PATIENTS: Gastric biopsy specimens were obtained for analysis from 161 patients undergoing endoscopy for dyspepsia . METHODS: Reactive oxygen species activity and damage was assessed by luminol enhanced chemiluminescence and malondialdehyde equivalent estimation respectively . Ascorbic acid concentrations were measured using HPLC . RESULTS: Chemiluminescence and malondialdehyde levels in gastric mucosa were higher in patients with H pylori gastritis than in those with normal histology . Successful eradication of the bacterium led to decreases in both parameters four weeks after treatment was completed . Gastric mucosal ascorbic acid and total vitamin C concentrations were not related to mucosal histology, but correlated weakly with reactive oxygen species activity (chemiluminescence and malodialdehyde levels) . CONCLUSIONS: Data suggest that reactive oxygen species play a pathological role in H pylori gastritis, but mucosal ascorbic acid is not depleted in this condition. Curr Microbiol, 1998 Sep, 37(3), 172 - 6 Anaerobic degradation and transformation of p-toluidine by the sulfate-reducing bacterium Desulfobacula toluolica; Raber T et al.; The ability of the strictly anaerobic sulfate-reducing bacterium Desulfobacula toluolica (strain Tol2) to cometabolically degrade p-toluidine (p-methylaniline) while using toluene as the primary source of carbon and energy has been studied . This organism has been shown to modify and degrade toluidine in dense cell suspensions when no other source of carbon and energy is added . The metabolism led to the formation of a variety of metabolites . From these metabolites a biphenyl-like compound as well as phenylacetic acid have been identified by means of HPLC/MS techniques . The probable conversion of p-toluidine to p-aminophenylacetic acid and phenylacetic acid as dead end products suggested that this organism initiates p-toluidine degradation by the carboxylation of the methyl group . If this could be validated in further experiments, it would be the first time that a toluidine was carboxylated at the methyl moiety by an anaerobic, sulfate-reducing bacterium. FEBS Lett, 1998 Jul 3, 430(3), 323 - 6 Excitation delocalization in the bacteriochlorophyll c antenna of the green bacterium Chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy; Savikhin S et al.; Room temperature absorption difference spectra were measured on the femtosecond through picosecond time scales for chlorosomes isolated from the green bacterium Chloroflexus aurantiacus . Anomalously high values of photoinduced absorption changes were revealed in the BChl c Qy transition band . Photoinduced absorption changes at the bleaching peak in the BChl c band were found to be 7-8 times greater than those at the bleaching peak in the BChl a band of the chlorosome . This appears to be the first direct experimental proof of excitation delocalization over many BChl c antenna molecules in the chlorosome. Eur J Biochem, 1998 Jun 15, 254(3), 602 - 9 The hydroxylase component of soluble methane monooxygenase from Methylococcus capsulatus (Bath) exists in several forms as shown by electrospray-ionisation mass spectrometry; Buzy A et al.; The hydroxylase of the soluble methane monooxygenase from the bacterium Methylococcus capsulatus (Bath) has been investigated by means of electrospray-ionisation mass spectrometry (ESI-MS) and liquid chromatography ESI-MS (LC/ESI-MS) . The hydroxylase is a non-heme diiron protein consisting of three pairs of non-identical subunits (alpha approximately 60 kDa, beta approximately 45 kDa and gamma approximately 20 kDa) . Liquid chromatographic separation of the hydroxylase subunits was required before MS analysis in order to detect the alpha-subunit . The masses measured for the three subunits were found to disagree with those calculated from their gene sequences . Experiments involving the use of CNBr and trypsin cleavage followed by LC/ESI-MS and MS/MS analyses permitted the location and correction of errors in the sequences deduced from the use of cDNA . The ESI-MS results also showed that the alpha-subunit of the hydroxylase exists in multiple forms which result from cleavage of the protein . This observation explains a number of enigmatic features of the protein previously reported in the literature and illustrates the pivotal role of ESI-MS in complementing data obtained from molecular biology for the characterisation of the primary sequence of proteins. Eur J Biochem, 1998 Jun 15, 254(3), 480 - 9 Sequence-alignment modelling and molecular docking studies of the epoxygenase component of alkene monooxygenase from Nocardia corallina B-276; Gallagher SC et al.; Whole cells of Nocardia corallina B-276 catalyse the stereoselective epoxygenation of alkenes to chiral epoxides . The bacterium expresses an enzyme, alkene monooxygenase, which catalyses the epoxygenation reaction stereoselectively . The enzyme consists of a terminal oxygenase (epoxygenase), an NADH-dependent reductase (reductase) and a regulatory component (coupling protein) . The epoxygenase component contains a bridged diiron centre similar to that found in the hydroxylase component of soluble methane monooxygenase . Sequence-alignment modelling, supported by chemical modification and fluorescence probing, identified a hydrophobic oxygen/substrate binding site within the epoxygenase . The diiron centre was coordinated by the two His and two Glu residues from two conserved Glu-Xaa-Xaa-His sequences and by two further Glu residues . Molecular docking of substrates and products into the proposed active-site model of the epoxygenase suggested that Ala91 and Ala185 were responsible for the stereoselectivity exerted by AMO . It is proposed that these residues clamped the intermediate and/or product of the reaction, thereby controlling the configuration of the epoxide produced . In soluble methane monooxygenase these residues are replaced by two Gly residues which do not provide sufficient steric hindrance to prevent rotation of the intermediate in the active site and, therefore, the product of the reaction catalysed by this enzyme is achiral. J Exp Med, 1998 Aug 3, 188(3), 505 - 14 Identification of putative cytoskeletal protein homologues in the protozoan host Hartmannella vermiformis as substrates for induced tyrosine phosphatase activity upon attachment to the Legionnaires' disease bacterium, Legionella pneumophila; Venkataraman C et al.; The Legionnaires' disease bacterium, Legionella pneumophila, is a facultative intracellular pathogen that invades and replicates within two evolutionarily distant hosts, free living protozoa and mammalian cells . Invasion and intracellular replication within protozoa are thought to be major factors in the transmission of Legionnaires' disease . We have recently reported the identification of a galactose/N-acetyl-D-galactosamine (Gal/GalNAc) lectin in the protozoan host Hartmannella vermiformis as a receptor for attachment and invasion by L . pneumophila (Venkataraman, C., B.J . Haack, S . Bondada, and Y.A . Kwaik . 1997 . J . Exp . Med . 186:537-547) . In this report, we extended our studies to the effects of bacterial attachment and invasion on the cytoskeletal proteins of H . vermiformis . We first identified the presence of many protozoan cytoskeletal proteins that were putative homologues to their mammalian counterparts, including actin, pp125(FAK), paxillin, and vinculin, all of which were basally tyrosine phosphorylated in resting H . vermiformis . In addition to L . pneumophila-induced tyrosine dephosphorylation of the lectin, bacterial attachment and invasion was associated with tyrosine dephosphorylation of paxillin, pp125(FAK), and vinculin, whereas actin was minimally affected . Inhibition of bacterial attachment to H . vermiformis by Gal or GalNAc monomers blocked bacteria-induced tyrosine dephosphorylation of detergent-insoluble proteins . In contrast, inhibition of bacterial invasion but not attachment failed to block bacteria-induced tyrosine dephosphorylation of H . vermiformis proteins . This was further supported by the observation that 10 mutants of L . pneumophila that were defective in invasion of H . vermiformis were capable of inducing tyrosine dephosphorylation of H . vermiformis proteins . Entry of L . pneumophila into H . vermiformis was predominantly mediated by noncoated receptor-mediated endocytosis (93%) but coiling phagocytosis was infrequently observed (7%) . We conclude that attachment but not invasion by L . pneumophila into H . vermiformis was sufficient and essential to induce protein tyrosine dephosphorylation in H . vermiformis . These manipulations of host cell processes were associated with, or followed by, entry of the bacteria by a noncoated receptor-mediated endocytosis . A model for attachment and entry of L . pneumophila into H . vermiformis is proposed. Appl Environ Microbiol, 1998 Aug, 64(8), 2882 - 7 Deletion of the rbo gene increases the oxygen sensitivity of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough; Voordouw JK et al.; The rbo gene of Desulfovibrio vulgaris Hildenborough encodes rubredoxin oxidoreductase (Rbo), a 14-kDa iron sulfur protein; forms an operon with the gene for rubredoxin; and is preceded by the gene for the oxygen-sensing protein DcrA . We have deleted the rbo gene from D . vulgaris with the sacB mutagenesis procedure developed previously (R . Fu and G . Voordouw, Microbiology 143:1815-1826, 1997) . The absence of the rbo-gene in the resulting mutant, D . vulgaris L2, was confirmed by PCR and protein blotting with Rbo-specific polyclonal antibodies . D . vulgaris L2 grows like the wild type under anaerobic conditions . Exposure to air for 24 h caused a 100-fold drop in CFU of L2 relative to the wild type . The lag times of liquid cultures of inocula exposed to air were on average also greater for L2 than for the wild type . These results demonstrate that Rbo, which is not homologous with superoxide dismutase or catalase, acts as an oxygen defense protein in the anaerobic, sulfate-reducing bacterium D . vulgaris Hildenborough and likely also in other sulfate-reducing bacteria and anaerobic archaea in which it has been found. Appl Environ Microbiol, 1998 Aug, 64(8), 2806 - 13 Algicidal effects of a novel marine pseudoalteromonas isolate (class Proteobacteria, gamma subdivision) on harmful algal bloom species of the genera Chattonella, Gymnodinium, and Heterosigma; Lovejoy C et al.; During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species . This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin . This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo) . It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h . Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans . The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating . Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects . The minimum concentrations of strain Y required to kill G . catenatum were higher than the mean concentrations found in nature under nonbloom conditions . However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms . These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms. J Appl Toxicol, 1998 May-Jun, 18(3), 179 - 85 Ibuprofen affects arylamine N-acetyltransferase activity in Helicobacter pylori from peptic ulcer patients; Chang SH et al.; Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene and p-aminobenzoic acid were determined in the bacterium Helicobacter pylori collected from peptic ulcer patients . Cytosols or suspensions of H . pylori with or without specific concentrations of ibuprofen co-treatment showed different percentages of 2-aminofluorene and p-aminobenzoic acid acetylation . The data indicate that there was decreased NAT activity associated with increased levels of ibuprofen in H . pylori cytosols . Inhibition of growth studies on H . pylori demonstrated that ibuprofen elicited a dose-dependent bactericide effect in H . pylori cultures, i.e . the greater the concentration of ibuprofen, the greater the inhibition of growth to H . pylori . For the cytosol and intact bacteria examinations, the apparent values of Km and Vmax were decreased after co-treatment with 40 microM ibuprofen . This report is the first demonstration of ibuprofen inhibition of arylamine N-acetyltransferase activity and ibuprofen inhibition of growth in the bacterium H . pylori. FEBS Lett, 1998 Jul 10, 431(1), 34 - 8 The 49-kDa subunit of NADH-ubiquinone oxidoreductase (Complex I) is involved in the binding of piericidin and rotenone, two quinone-related inhibitors; Darrouzet E et al.; Piericidin is a potent inhibitor of the mitochondrial and bacterial type I NADH-ubiquinone oxidoreductases (Complex I) and is considered to bind at or close to the ubiquinone binding site(s) of the enzyme . Piericidin-resistant mutants of the bacterium Rhodobacter capsulatus have been isolated and the present work demonstrates that a single missense mutation at the level of the gene encoding the peripheral 49-kDa/NUOD subunit of Complex I is definitely associated with this resistance . Based on this original observation, we propose a model locating the binding site for piericidin (and quinone) at the interface between the hydrophilic and hydrophobic domains of Complex I. Int J Clin Pract . 1998 Apr-May;52(3):205. Fatal septicaemia in a previously healthy man following a dog bite; Saab M et al.; A rare case of fatal septicaemia after a dog bite in a previously healthy individual is presented and discussed . Capnocytophaga canimorsus (DF-2 bacterium) was isolated from blood cultures . Our case shows the importance of immediate antibiotic treatment for all dog and cat bites, regardless of severity. Dis Aquat Organ, 1998 Jun 19, 33(2), 101 - 9 Pathology attributed to Mycobacterium chelonae infection among farmed and laboratory-infected Atlantic salmon Salmo salar; Bruno DW et al.; This study was promoted following concern over increasing mortality on 2 farms rearing Atlantic salmon Salmo salar in the Shetland Isles, Scotland . A Mycobacterium sp . was isolated from moribund, market-sized Atlantic salmon . Biochemical tests, lipid analysis and PCR (polymerase chain reaction) techniques confirmed the bacterium to be Mycobacterium chelonae . Multiple greyish-white miliary granuloma-like nodules were observed in several tissues . Dense hard-packed nodules contained abundant acid-fast bacteria . Atlantic salmon injected with M . chelonae remained sub-clinically infected, demonstrating the chronic nature of this disease . The source of the pathogen was not identified. Hepatogastroenterology, 1998 May-Jun, 45(21), 765 - 70 Beneficial effects of Helicobacter pylori eradication on migraine; Gasbarrini A et al.; BACKGROUND/AIMS: Migraine is a commonly unilateral throbbing headache, which has been associated with disorders of the vascular tone . Helicobacter pylori, the most relevant cause of gastritis and peptic ulcer, has been recently associated with a typical functional vascular disorder such as primary Raynaud phenomenon . The aim of this study was to assess the prevalence of H . pylori for patients affected by migraine and the effects of H . pylori eradication on migraine symptoms . METHODOLOGY: Two-hundred and twenty-five patients were consecutively enrolled between October 1996 and January 1997 . H . pylori was assessed by 13C-urea breath test . Infected subjects were eradicated of the bacterium; frequency, intensity and duration of attacks of migraine were assessed during a 6 month follow-up period . RESULTS: H . pylori was detected in 40% of the patients . Eighty-three percent of the patients who underwent therapy were eradicated . Intensity, duration and frequency of attacks of migraine were significantly reduced in all eradicated patients . CONCLUSIONS: H . pylori is common in subjects with migraine . Bacterium eradication causes a significant decrease in attacks of migraine . The reduction of vasoactive substances produced during infection may be the pathogenetic mechanism underlying the phenomenon. Clin Immunol Immunopathol, 1998 Jul, 88(1), 80 - 3 Distribution of IgA subclass response to Coxiella burnetii in patients with acute and chronic Q fever; Camacho MT et al.; The progression of Coxiella burnetii infection to acute or chronic Q fever has been attributed to biological characteristics of the bacterium and to the host immune response . We measured whether serum levels of total and specific subclasses IgA1 and IgA2 could be correlated with the course of disease in acute and chronic Q fever infections, and with the occurrence of endocarditis . In patients with chronic infection, total IgA2 levels were significantly increased . Q-fever-specific IgA1 antibodies were detectable in both acute and chronic infections, but only patients with endocarditis had IgA2 antibodies to C . burnetii phase II antigens . These findings indicate that the measurement of IgA subclasses may be a useful aid in the serological diagnosis of Q fever . Our results reinforce the idea that immunologically mediated host factors are important in the pathogenesis of Q fever and in the disease outcome of this infection . FEMS Microbiol Lett, 1998 Jul 15, 164(2), 375 - 82 Properties of aspartate transcarbamylase from TAD1, a psychrophilic bacterial strain isolated from Antarctica; Sun K et al.; TAD1 is a psychrophilic strain isolated from continental frozen water in Antarctica . Study of aspartate transcarbamylase in the bacterium shows an impressive activity of this enzyme at low temperature . At 0 degree C, its activity is up to 26% of its maximal activity observed at 30 degrees C . In comparison with the Escherichia coli enzyme, some of its kinetic properties suggest that this high activity at low temperature results from an increased catalytic efficiency . This property might result from a discrete modification localized at the catalytic site, since this psychrophilic enzyme is as stable as its Escherichia coli homologue at high temperature. Extremophiles, 1997 Nov, 1(4), 183 - 91 Shuttle vectors for hyperthermophilic archaea; Aravalli RN et al.; Progress in understanding the basic molecular, biochemical, and physiological characteristics of archaeal hyperthermophiles has been limited by the lack of suitable expression vectors . Here, we report the construction of versatile shuttle vectors that can be maintained, and selected for, in both archaea and bacteria . The primary construct, pAG1, was produced by ligating portions of the archaeal cryptic plasmid pGT5 and the bacterial plasmid pUC19, both of which exhibit high copy numbers . A second vector construct, pAG2, was generated, with a reduced copy number in Escherichia coli, by introducing the Rom/Rop gene from pBR322 into pAG1 . After transformation, both pAG1 and pAG2 were stably maintained and propagated in the euryarchaeote Pyrococcus furiosus, the crenarchaeote Sulfolobus acidocaldarius, and in Escherichia coli . An archaeal selective marker, the alcohol dehydrogenase gene from Sulfolobus solfataricus, was isolated by polymerase chain reaction (PCR) amplification and cloned into the two constructs . They were stably maintained and expressed in the two archaea and conferred resistance to butanol and benzyl alcohol . However, the vector pAG21, deriving from pAG2, proved the more stable in E . coli probably due to its lower copy number in the bacterium . Conditions are presented for the use of the vectors which, potentially, can be used for other hyperthermophilic archaea. Mol Microbiol, 1998 Jun, 28(6), 1283 - 93 N-terminal characterization of the Bordetella pertussis filamentous haemagglutinin; Lambert-Buisine C et al.; The major adhesin of Bordetella pertussis, filamentous haemagglutinin (FHA), is produced and secreted at high levels by the bacterium . Mature FHA derives from a large precursor, FhaB, that undergoes several post-translational maturations . In this work, we demonstrate by site-directed mutagenesis that the N-terminal signal peptide of FHA is composed of 71 amino acids, including a 22-residue-long 'N-terminal extension' sequence . This sequence, although highly conserved in various other secretory proteins, does not appear to play an essential part in FHA secretion, as shown by deletion mutagenesis . The entire N-terminal signal region of FhaB is removed in the course of secretion by proteolytic cleavage at a site that corresponds to a Lep signal peptidase recognition sequence . After this maturation, the N-terminal glutamine residue is modified to a pyroglutamate residue . This modification is not crucial for heparin binding, haemagglutination or secretion . Interestingly, however, the modification is absent from Escherichia coli secreted FHA derivatives . In addition, it is dependent in B . pertussis on the presence of all three cysteines contained in the signal peptide of FhaB . These observations suggest that it does not occur spontaneously but perhaps requires a specific enzymatic machinery. Biochem Mol Biol Int, 1998 Jun, 45(2), 355 - 62 Pigment organization and exciton dynamics in the B808-866 antenna of the green bacterium Chloroflexus aurantiacus; Novoderezhkin V et al.; The model for the B808-866 antenna of the green photosynthetic bacterium Chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed . The three-dimensional structure of the B808-866 antenna is assumed to be similar to the structure of the B800-850 antenna of purple bacteria, i.e . it has the form of two concentric rings of N strongly coupled BChl866 pigments and of N/2 weakly coupled BChl808 monomers . The Qy transition dipoles of BChl808 and BChl866 molecules form the angles 43 degrees +/- 3 degrees and 8 degrees +/- 4 degrees, respectively, with the plane of the corresponding rings . The lowest limit of the BChl866 aggregate size is N = 18 . The anomalously high bleaching value of the BChl866 band with respect to the monomeric BChl808 band provides evidence for a high degree of exciton delocalization . To account for this phenomenon, the exciton model describing exciton dynamics in the spectrally disordered circular BChl866 aggregate is developed . According to this model, the effective exciton size in this antenna (Neff) is 6-8. J Food Prot, 1998 Jul, 61(7), 910 - 2 Thermal inactivation analysis of mesophiles using the Arrhenius and z-value models; Fujikawa H et al.; The Arrhenius and z-value models were compared for thermal inactivation analysis of a mesophilic bacterium . The models produced a linear curve for the thermal inactivation data . Concerning the rate constant of inactivation, the D and k values predicted by the models at a constant temperature were similar . For extrapolated temperatures the z-value model predicted an insignificant decrease in the survival ratio compared to the Arrhenius model . The dynamic temperature survival curves predicted by the models were similar, and the models characterized the results . These results demonstrated that the models can be used for thermal inactivation analysis of mesophiles at various temperatures. FEMS Microbiol Lett, 1998 Jul 1, 164(1), 215 - 8 Partial purification and characterization of RalF40I, a class II restriction endonuclease from Ruminococcus albus F-40, which recognizes and cleaves 5'-/GATC-3'; Miyagi T et al.; Restriction endonuclease RalF40I was purified from cell-free extracts of the rumen cellulolytic bacterium Ruminococcus albus F-40 heparin-Sepharose chromatography . The preparation was active only on DNA substrates that were not Dammethylated . RalF401 recognizes the 4-bp palindrome, 5'-/GATC-3', and cleaves DNA at the 5' side of G in the sequence, producing 5' tetranucleotide protruding ends . RalF40I is a class II restriction endonuclease and an isoschizomer of MboI and DpnII. Ital J Gastroenterol Hepatol, 1998 Apr, 30(2), 153 - 9 Epithelial-cell apoptosis and proliferation in Helicobacter pylori-related chronic gastritis; Anti M et al.; BACKGROUND: Several studies have shown that Helicobacter pylori infection is associated with enhanced gastric epithelial-cell proliferation, which is thought to be involved in its apparent carcinogenicity . This hyperproliferation is believed to be related to the inflammatory effects of the bacterium . The role of Helicobacter pylori in gastric epithelial apoptosis, however, is less clear . AIM: We attempted to identify the effect of Helicobacter pylori infection on apoptosis in the gastric epithelium and its possible relation to epithelial-cell proliferation and mucosal inflammation . PATIENTS AND METHODS: We studied cell proliferation (via bromodeoxyuridine labelling), apoptosis (using in situ TdT-mediated dUTP-biotin nick end labelling of DNA strand breaks) and mononuclear and polymorphonuclear cell infiltrates (computer-assisted image analysis) in gastric antral biopsies obtained from 37 gastritis patients (20 Helicobacter pylori-positive, 17 Helicobacter pylori-negative) . RESULTS: Helicobacter pylori-positives displayed significantly enhanced proliferation within the gastric epithelium that was positively correlated with both acute and chronic inflammatory-cell densities . Apoptotic indexes were similar in both groups and showed no correlation with any of the parameters under consideration . CONCLUSIONS: Enhanced epithelial cell proliferation and an altered distribution of cycling cells within the gastric glands are a common feature of chronic superficial gastritis caused by Helicobacter pylori . In vivo immunohistochemically detected apoptosis of gastric epithelial cells does not seem to be affected by Helicobacter pylori infection . Further study is needed to clarify the effect of this infection on programmed cell death within gastric glands. J Appl Microbiol, 1998 May, 84(5), 889 - 94 Iron deficiency-induced tetracycline production in submerged cultures by Streptomyces aureofaciens; Bechet M et al.; Streptomyces aureofaciens ATCC 10762 grown in rotary-shaken submerged cultures produced substantial amounts of tetracycline only when the defined medium was deprived of iron . The biosynthesis of tetracycline was inhibited either by free iron at concentrations above 1-2 mumol l-1, or by chelated iron provided by the siderophores of this bacterial strain . Late static iron-containing cultures allowed cell differentiation and sporulation and led to tetracyclines synthesis . A nitrosoguanidine-induced mutant able to synthesize tetracycline in the presence of iron in shaken submerged cultures was isolated and compared to the wild-type strain . However, no constitutive siderophore-mediated iron transport occurred in the mutant . These results suggest the involvement of a putative iron-controlled repressor in the biosynthesis of these secondary metabolites during vegetative growth and primary metabolism of the bacterium. Extremophiles, 1998 May, 2(2), 93 - 9 Purification of a ccb-type quinol oxidase specifically induced in a deep-sea barophilic bacterium, Shewanella sp . strain DB-172F; Qureshi MH et al.; We investigated for the first time the respiratory chain system of a deep-sea barophilic bacterium, Shewanella sp . strain DB-172F . A membrane-bound ccb-type quinol oxidase, from cells grown at 60 MPa pressure, was purified to an electrophoretically homogeneous state . The purified enzyme complex consisted of four kinds of subunits with molecular masses of 98, 66, 18.5, and 15kDa, and it contained 0.96 mol of protoheme and 1.95mol of covalently bound heme c per mol of enzyme . Only protoheme in the enzyme reacted with CO and CN-, and the catalytic activity of the enzyme was 50% inhibited by 4 microM CN- . The isoelectric point of the native enzyme complex was determined to be 5.0 . This enzyme was specifically induced only under conditions of elevated hydrostatic pressure, and high levels were expressed in cells grown at 60 MPa . The membranes isolated from cells grown at atmospheric pressure (0.1 MPa) exhibited high levels of both cytochrome c oxidase and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPDH2)-oxidase activity . These results suggest the presence of two kinds of respiratory chains regulated in response to pressure in the deep-sea bacterium DB-172F. J Mol Biol, 1998 Jul 31, 280(5), 775 - 84 Pathways for transcriptional activation of a glutathione-dependent formaldehyde dehydrogenase gene; Barber RD et al.; The widespread occurrence of glutathione-dependent formaldehyde dehydrogenases (GSH-FDH) suggests that this enzyme serves a conserved function in preventing the cytogenetic and potentially lethal interaction of formaldehyde with nucleic acids, proteins and other cell constituents . Despite this potential role of GSH-FDH, little is known about how its expression is regulated . Here, we identify metabolic and genetic signals that activate transcription of a GSH-FDH gene (adhI) in the bacterium Rhodobacter sphaeroides . Activity of the adhI promoter is increased by both exogenous formaldehyde and metabolic sources of this toxin . Elevated adhI promoter activity in DeltaGSH-FDH mutants implicates formaldehyde or the glutathione adduct that serves as a GSH-FDH substrate, S-hydroxymethylglutathione, as a transcriptional effector . From studying adhI expression in different host mutants, we find that the photosynthetic response regulator PrrA and the trans-acting spd-7 mutation increase function of this promoter . The behavior of a nested set of adhI::lacZ fusions indicates that activation by formaldehyde, PrrA and spd-7 requires only sequences 55 bp upstream of the start of transcription . A working model is presented to explain how GSH-FDH expression responds to formaldehyde and global signals generated from the reduced pyridine nucleotide produced by the activity of this enzyme . Microbios, 1998, 93(374), 7 - 16 Isolation and characterization of S-layer proteins from a vent prosthecate bacterium; Shen N et al.; MWapp 116,000 and 29,000 proteins (p116 and p29), major outer membrane proteins of Hyphomonas jannaschiana reproductive cells, were extracted from cell envelopes by dialysis against EDTA, 2 M urea or distilled water . These proteins were precipitated by divalent cations and resolubilized by EDTA-Na, reflecting alternate monomer, multimer states . From two-dimensional gel electrophoresis it was determined that p116 and p29 had a pl of 4.5 . Both were glycoproteins . Results suggest that p116 and p29 are surface layer (S-layer) proteins, with p116 a tetramer of the p29 . The S-layer could protect the adherent H . jannaschiana reproductive cell from exoenzyme activity, antibiotics and other bacteriocidal molecules produced in the bacterial films formed on many marine surfaces. Biochemistry (Mosc), 1998 Jun, 63(6), 625 - 8 Photophosphorylation in alkalophilic halobacterial cells containing halorhodopsin: chloride-ion cycle? Avetisyan AV, Kaulen AD, Skulachev VP, Feniouk BA. Light-driven ATP synthesis is found in cells of the alkalophilic bacterium Natronobacterium pharaonis containing halorhodopsin but deficient in H+-pumping bacteriorhodopsin . Photophosphorylation occurs with cyanide-inhibited respiratory chain as well as without cyanide in conditions with low C1- concentration in the incubation medium . Increase in C1- concentration from 0.1 to 2.35 M in the incubation medium leads to inhibition of photophosphorylation . Continuous illumination increases membrane Delta Psi if respiration is inhibited by cyanide . This effect is stimulated by DCCD, an ATPase inhibitor . These data can be explained if one suggests that halorhodopsin pumps C1- into the cells whereas C1- release from the cells through C1--ATP-synthase is coupled with the ATP synthesis (chloride-ion cycle). J Mol Biol, 1998 Jul 17, 280(3), 323 - 6 Homology-based fold predictions for Mycoplasma genitalium proteins; Huynen M et al.; Homology search techniques based on the iterative PSI-BLAST method in combination with various filters for low sequence complexity are applied to assign folds to all Mycoplasma genitalium proteins . The resulting procedure (implemented as a web server) is able to predict at least one domain in 37% of these proteins automatically, with an estimated accuracy higher than 98% . Taking structural features such as coiled coil or transmembrane regions aside, folds can be assigned to more than half of the globular proteins in a bacterium just by iterative sequence comparison . FEBS Lett, 1998 Jun 16, 429(3), 295 - 8 Characterisation of a new rubredoxin isolated from Desulfovibrio desulfuricans 27774: definition of a new family of rubredoxins; LeGall J et al.; A new rubredoxin from the sulphate-reducing bacterium Desulfovibrio desulfuricans ATCC 27774, grown with nitrate as terminal electron acceptor, was isolated and characterised . The protein is an 8.5 kDa monomer containing one iron atom per molecule, with a reduction potential of 25 +/- 5 mV at pH 7.6 . Like the recombinant Rdl protein from D . vulgaris, expressed in Escherichia coli {Lumpio, H.L., Shenvi, N.V., Garg, R.P., Summers, A.O . and Kurtz, D.M., J . Bacteriol . 179 (1997) 4607-4615}, it contains an unusual spacing of four amino acids between the first two of the iron coordinating cysteinyl residues . This difference is reflected in the structure of the iron centre, as observed by visible and EPR spectroscopies . All together, these features make these proteins the first members of a new family of rubredoxins. J Biol Chem, 1998 Jul 17, 273(29), 18509 - 13 DNA binding characteristics of RegA . A constitutively active anaerobic activator of photosynthesis gene expression in Rhodobacter capsulatus; Du S et al.; In the purple non-sulfur bacterium Rhodobacter capsulatus, RegA and RegB comprise a two-component regulatory system that is required for maximal anaerobic transcription of key photosynthesis genes . RegB is a sensor kinase that uses ATP to phosphorylate its cognate response regulator, RegA . The mechanism under which RegA approximately P influences transcription of target genes has been unclear given that past attempts to demonstrate DNA binding activity by isolated RegA have failed . This led to a model invoking a role for RegA approximately P as an intermediate in a more complex multicomponent phosphoryl transfer cascade . In the present study, we describe the isolation of a mutant version of RegA (RegA*) which promotes high level expression of photosynthesis genes independent of RegB . DNase I footprint analyses show that purified RegA* binds to the promoters of the puf and puc operons at locations that are consistent with RegA functioning as a transcriptional activator for these operons . We conclude that RegA functions, like most members of the response regulator family, as a DNA-binding protein that directly affects the expression of its target genes. Biochim Biophys Acta, 1998 May 19, 1384(2), 345 - 55 Purification and primary structure analysis of two cytochrome c2 isozymes from the purple phototrophic bacterium Rhodospirillum centenum; Samyn B et al.; The isolation and amino acid sequences of two cytochromes c-552 from the thermotolerant bacterium Rhodospirillum (R.) centenum have been determined . They are very similar to one another with 85% identity . They are homologous to the cytochromes c2 from purple bacteria with approximately 67% identity to that from Rhodopseudomonas (Rps.) palustris compared to only 42% identity with others of the c2 subclass . In addition, they share an unusual six-residue insertion with Rps . palustris cytochrome c2 not found in any other cytochrome . The relationship with Rps . palustris is thus highly significant . The redox potentials of the R . centenum isozymes are 293 and 316 mV . Although the proteins have strongly different iso-electric points, both have three conserved lysine residues at the proposed site of electron transfer . These results suggest that they may be functionally interchangeable. Eur J Biochem, 1998 Apr 15, 253(2), 437 - 44 The reductase RedA2 of the multi-component dioxin dioxygenase system of Sphingomonas sp . RW1 is related to class-I cytochrome P450-type reductases; Armengaud J et al.; The first step in the oxidation of the diaryl ethers dibenzo-p-dioxin and dibenzofuran by the bacterium Sphingomonas sp . RW1 is carried out by an atypical multi-component ring hydroxylating dioxygenase . This heteromeric enzyme requires the participation of a flavoprotein, reductase A2, and an iron-sulfur protein, Fdx1, to mediate the transfer of electrons from NADH to the dioxygenase for oxygen activation {Bunz, P . V . & Cook, A . M . (1993) J . Bacteriol . 175, 6467-6475} . From the type of ferredoxin (Fd) and flavoprotein, this complex is presumed to belong to the class-IIA dioxygenase system which has not been genetically analysed so far . The gene encoding the flavoprotein was identified by screening a genomic library constructed in pLAFR3 with a probe generated by PCR amplification . The nucleotide sequence of a 2.0-kb DNA fragment encompassing the reductase gene, redA2, was determined . The specified protein shares 37-40% identity with class-I cytochrome P450 reductases and 27-35% identity with reductases acting with class-IIB dioxygenases . An FAD-binding amino acid consensus sequence, as well as an NADH-binding site were detected by analogy beginning at residues 10 and 153, respectively . The redA2 gene is not linked to the dioxin dioxygenase cistrons . The rare start codon, GTG, of the reductase was changed to ATG and the modified gene hyperexpressed in Escherichia coli using the strong T7 polymerase promoter . The recombinant reductase was purified to homogeneity with an approximate yield of 3.3 mg/g wet mass cells . Flavin analysis confirmed the presence of 1 FAD/mol protein . The Km values for NADH and Fdx1 are 22 (+/- 3) microM and 3.7 (+/- 0.4) microM, respectively. J Infect Dis, 1998 Jul, 178(1), 274 - 7 High prevalence of Chlamydia pneumoniae DNA in peripheral blood mononuclear cells in patients with cardiovascular disease and in middle-aged blood donors; Boman J et al.; Nested polymerase chain reaction (nPCR) demonstrated the presence of Chlamydia pneumoniae-specific DNA in peripheral blood mononuclear cells (PBMC) . PBMC samples were obtained from 103 consecutive patients (62 male, 41 female) aged 22-85 years (mean, 64) admitted for coronary angiography because of suspected coronary heart disease and from 52 blood donors (43 male, 9 female) aged 40-64 years (mean, 49) . Of the 101 evaluable patients, 60 (59%) were identified by nPCR assay as C . pneumoniae DNA carriers; C . pneumoniae-specific microimmunofluorescence (MIF) serology confirmed exposure to the bacterium in 57 (95%) of the 60 nPCR-positive patients . Among the 52 blood donors, the nPCR assay identified 24 (46%) C . pneumoniae DNA carriers, all of whom were positive by C . pneumoniae-specific serology . Thirty-two patients (32%) and 23 blood donors (44%) were MIF antibody-positive but repeatedly nPCR-negative; Bartonella henselae- or Bartonella quintana-specific antibodies were not detected among any of these subjects . In this study, C . pneumoniae DNA was common in PBMC of patients with coronary heart disease and in middle-aged blood donors. Dig Dis Sci, 1998 Jun, 43(6), 1226 - 9 Beneficial effects of Helicobacter pylori eradication on idiopathic chronic urticaria; Di Campli C et al.; Helicobacter pylori, the most important cause of gastritis and peptic ulcer, recently has been associated with several extradigestive diseases . The aim of this study was to assess the prevalence of Helicobacter pylori infection and the effects of bacterium eradication in 42 consecutive patients affected by idiopathic chronic urticaria . Helicobacter pylori was assessed by {13C}urea breath test . Amoxicillin, clarithromycin, and lansoprazole were given to infected patients for seven days . Urticaria and gastrointestinal symptoms were assessed on enrollment and after eradication . Fifty-five percent of patients proved to be infected by Helicobacter pylori . Prevalence of gastrointestinal symptoms did not differ between infected and uninfected patients . Eighty-eight percent of infected patients in whom the bacterium was eradicated after therapy showed a total or partial remission of urticaria symptoms . Conversely, symptoms remained unchanged in all uninfected patients . In conclusion, Helicobacter pylori affects a high percentage of patients with idiopathic chronic urticaria; however, typical gastrointestinal symptoms do not identify infection status . Bacterium eradication is associated with a remission of urticaria symptoms, suggesting a possible role of Helicobacter pylori in the pathogenesis of this skin disorder. Br J Rheumatol, 1998 May, 37(5), 520 - 4 Bacteria-specific lymphocyte proliferation in peripheral blood in reactive arthritis and related diseases; Fendler C et al.; The cellular immune response seems to be important for the pathogenesis of reactive arthritis (ReA) and a bacteria-specific lymphocyte proliferation (LP) is often found in synovial fluid (SF) of ReA patients . However, the role of the bacteria-specific LP in peripheral blood (PB) is less well defined . In this study, we investigated 215 paired samples of SF and PB from patients with ReA (n = 65), undifferentiated oligoarthritis (n = 133) and undifferentiated spondylarthropathy (n = 17) to analyse the LP in PB and SF in relation to time . In 24 out of 87 patients (27.6%) with a bacteria-specific LP in synovial fluid, a positive LP to the same bacterium was also found in PB . While a positive LP in SF was found most frequently in the first week of the arthritis, a positive LP in PB was detected in 45% of patients when investigated between weeks 2 and 4 after the onset of arthritis, but was rarely found very early and late in the course of the arthritis . The time point seems to be crucial for the investigation of an LP in PB in patients with ReA. Appl Microbiol Biotechnol, 1998 May, 49(5), 552 - 9 Identification of tandemly repeated type VI cellulose-binding domains in an endoglucanase from the aerobic soil bacterium Cellvibrio mixtus; Fontes CM et al.; Cellulose-binding domains (CBD) play a pivotal role during plant cell wall hydrolysis by cellulases and xylanases from aerobic soil bacteria . Recently we have reported the molecular characterisation of a single-domain endoglucanase from Cellvibrio mixtus, suggesting that some cellulases produced by this aerobic bacterium preferentially hydrolyse soluble cellulosic substrates . Here we describe the complete nucleotide sequence of a second cellulase gene, celB, from the soil bacterium C . mixtus . It revealed an open reading frame of 1863 bp that encoded a polypeptide, defined as cellulase B (CelB) with a predicted Mr of 66 039 . CelB contained a glycosyl hydrolase family 5 catalytic domain at its N terminus followed by two repeated domains, which exhibited sequence identity with type VI CBD previously found in xylanases . Full-length CelB bound to cellulose while catalytically active truncated cellulase derivatives were unable to bind the polysaccharide, confirming that CelB is a modular enzyme and that the type VI CBD homologues were functional . Analysis of the biochemical properties of CelB revealed that the enzyme hydrolyses a range of cellulosic substrates, although it was unable to depolymerise Avicel . We propose that type VI CBD, usually found in xylanases, provide an additional mechanism by which cellulases can accumulate on the surface of the plant cell wall, although they do not potentiate cellulase activity directly . The results demonstrate that C . mixtus, in common with other aerobic bacteria, is able to produce cellulases that are directed to the hydrolysis of cellulose in its natural environment, the plant cell wall. MMWR Morb Mortal Wkly Rep, 1998 Jun 19, 47(23), 476 - 80 Statewide surveillance for ehrlichiosis--Connecticut and New York, 1994-1997; DNA analysis of temperate bacteriophage Aa(phi)23 isolated from actinobacillus actinomycetemcomitans; Institute of Preventive Dentistry and Oral Microbiology, Dental Center, University of Basel, SwitzerlandThe DNA of the temperate bacteriophage Aaphi23 isolated from the oral bacterium Actinobacillus actinomycetemcomitans was examined structurally both in the phage head and in the prophage . The DNA in phage particles comprises 44 kb linear molecules with a terminal redundancy of 1.6 kb, which represent circular permutations . Thus, DNA is packaged into phage heads by the headful mechanism . The Aaphi23 prophage is integrated into the host chromosome. Appl Environ Microbiol, 1998 Jul, 64(7), 2380 - 5 Molecular cloning, sequencing, and expression of a chemoreceptor gene from Leptospirillum ferrooxidans; Delgado M et al.; We have cloned and sequenced a 2,262-bp chromosomal DNA fragment from the chemolithoautotrophic acidophilic bacterium Leptospirillum ferrooxidans . This DNA contained an open reading frame for a 577-amino-acid protein showing several characteristics of the bacterial chemoreceptors and, therefore, we named this gene lcrI for Leptospirillum chemotaxis receptor I . This is the first sequence reported for a gene from L . ferrooxidans encoding a protein . The lcrI gene showed both sigma 28-like and sigma 70-like putative promoters . The LcrI deduced protein contained two hydrophobic regions most likely corresponding to the two transmembrane regions present in all of the methyl-accepting chemotaxis proteins (MCPs) which make them fold with both periplasmic and cytoplasmic domains . We have proposed a cytoplasmic domain for LcrI, which also contains the highly conserved domain (HCD region), present in all of the chemotactic receptors, and two probable methylation sites . The in vitro expression of a DNA plasmid containing the 2,262-bp fragment showed the synthesis of a 58-kDa protein which was immunoprecipitated by antibodies against the Tar protein (an MCP from Escherichia coli), confirming some degree of antigenic conservation . In addition, this 58-kDa protein was expressed in E . coli, being associated with its cytoplasmic membrane fraction . It was not possible to determine a chemotactic receptor function for LcrI expressed in E . coli . This was most likely due to the fact that the periplasmic pH of E . coli, which differs by 3 to 4 pH units from that of acidophilic chemolithotrophs, does not allow the right conformation for the LcrI periplasmic domain. Tierarztl Prax Ausg K Klientiere Heimtiere, 1998 May, 26(3), 154 - 9 {Relevance of Helicobacter pylori infection in the development of gastric tumors}; Bartram HP; Helicobacter pylori plays an important role in the pathogenesis of peptic ulcer disease . Besides, epidemiological studies indicate that helicobacter may be involved in the development of gastric cancer and MALT-lymphoma by inducing gastritis and accumulation of lymph follicles in the gastric mucosa . The carcinogenic effect of helicobacter pylori can be explained by various pathogenetic factors which are produced by the bacterium itself . Furthermore, influences of helicobacter pylori on the vitamin C content of gastric mucosa might play a role . Currently, Hp-eradication therapies for the treatment of gastric MALT lymphomas are already under investigation in controlled studies . Concerning gastric cancer prevention, however, the available data are not sufficient to warrant a general recommendation for eradication-therapies of all Hp-infected persons . However, further studies must show whether Hp-eradication of high-risk subjects, i.e . members of gast