| neonatal fc receptor for igg (fcrn) expressed in the gastric epithelium regulates bacterial infection in mice. | neonatal fc receptors for immunoglobulin (ig)g (fcrn) assume a central role in regulating host igg levels and igg transport across polarized epithelial barriers. we have attempted to elucidate the contribution of fcrn in controlling helicobacter infection in the stomach. c57bl/6j wild-type or fcrn(-/-) mice were infected with helicobacter heilmannii, and gastric lesions, bacterial load and the levels of antigen-specific igg in serum and gastric juice were analyzed. the elevated levels of anti-h. ... | 2012 | 22089027 |
| crystal structure and enzymatic characterization of thymidylate synthase x (thyx) from helicobacter pylori strain ss1. | thymidylate synthase x (thyx) catalyzes the methylation of dump to form dtmp in bacterial life cycle and is regarded as a promising target for antibiotics discovery. helicobacter pylori is a human pathogen associated with a number of human diseases. here we cloned and purified the thyx enzyme from h. pylori ss1 strain (hpthyx). the recombinant hpthyx was discovered to exhibit the maximum activity at ph 8.5, and k(m) values of the two substrates dump and ch(2) h(4) folate were determined to be 15 ... | 2011 | 21633987 |
| enzymatic characterization and crystal structure analysis of the d-alanine-d-alanine ligase from helicobacter pylori. | d-alanine-d-alanine ligase is the second enzyme in the d-ala branch of bacterial cell wall peptidoglycan assembly, and recognized as an attractive antimicrobial target. in this work, the d-ala-d-ala ligase of helicobacter pylori strain ss1 (hpddl) was kinetically and structurally characterized. the determined apparent k(m) of atp (0.87 microm), the k(m1) (1.89 mm) and k(m2) of d-ala (627 mm), and the k(cat) (115 min(-1)) at ph 8.0 indicated its relatively weak binding affinity and poor catalytic ... | 2008 | 18320587 |
| accelerated progression of gastritis to dysplasia in the pyloric antrum of tff2 -/- c57bl6 x sv129 helicobacter pylori-infected mice. | trefoil factor family 2 (tff2) is up-regulated in helicobacter spp.-infected gastric tissues of both humans and mice. to ascertain the biological effects of tff2 in vivo, tff2(-/-) c57bl/6 x sv129 and wild-type (wt) c57bl/6 x sv129 mice were orally infected with helicobacter pylori ss1. mice were evaluated for gastric h. pylori colonization, pathology, and cytokine profiles at 6 and 19 months post inoculation (pi). at 6 months pi, there was a significant difference (p < 0.05) for epithelial crit ... | 2007 | 17982128 |
| enzymatic characterization and inhibitor discovery of a new cystathionine {gamma}-synthase from helicobacter pylori. | cystathionine gamma-synthase (cgs) catalyses the first step of the transsulfuration pathway that converts l-cysteine to l-homocysteine in bacteria, whereas this pathway is absent in human. in this report, we identified a new metb gene from helicobacter pylori strain ss1, and the recombinant h. pylori cystathionine gamma-synthase (hpcgs) was successfully cloned, expressed and purified in escherichia coli system. enzymatic study of hpcgs indicated that the k(m) and k(cat)/k(m) values against the s ... | 2008 | 17981822 |
| helicobacter pylori acyl carrier protein: expression, purification, and its interaction with beta-hydroxyacyl-acp dehydratase. | acyl carrier protein (acp) is an essential component in the type ii fatty acid biosynthesis (fas ii) process and is responsible for the acyl group transfer within a series of related enzymes. in this work, the acp from helicobacter pylori strain ss1 was cloned and the gene sequence of hpacp was deposited in the genbank database (accession no.: ay904356). two forms of hpacp (apo, holo) were successfully purified and characterized. the thermal stability of these two forms was quantitatively invest ... | 2007 | 17049879 |
| biochemical characterization and inhibitor discovery of shikimate dehydrogenase from helicobacter pylori. | shikimate dehydrogenase (sdh) is the fourth enzyme involved in the shikimate pathway. it catalyzes the nadph-dependent reduction of 3-dehydroshikimate to shikimate, and has been developed as a promising target for the discovery of antimicrobial agent. in this report, we identified a new aroe gene encoding sdh from helicobacter pylori strain ss1. the recombinant h. pylori shikimate dehydrogenase (hpsdh) was cloned, expressed, and purified in escherichia coli system. the enzymatic characterization ... | 2006 | 16972983 |
| evidence for interleukin-1-independent stimulation of interleukin-12 and down-regulation by interleukin-10 in helicobacter pylori-infected murine dendritic cells deficient in the interleukin-1 receptor. | helicobacter pylori infection is characterized by infiltration of cells of the immune system, including dendritic cells, into the gastric mucosa. during chronic inflammation with helicobacter pylori infection, a variety of cytokines are secreted into the mucosa, including interleukin-1beta (il-1beta). the role of il-1 in h. pylori infection was investigated using bone-marrow-derived dendritic cells from wild-type and il-1 receptor-deficient (il-1r-/-) mice. dendritic cells were incubated with h. ... | 2006 | 16872378 |
| characterization and inhibitor discovery of one novel malonyl-coa: acyl carrier protein transacylase (mcat) from helicobacter pylori. | type ii fatty acid synthesis (fas ii) is an essential process for bacteria survival, and malonyl-coa:acyl carrier protein transacylase (mcat) is a key enzyme in fas ii pathway, which is responsible for transferring the malonyl group from malonyl-coa to the holo-acp by forming malonyl-acp. in this work, we described the cloning, characterization and enzymatic inhibition of a new mcat from helicobacter pylori strain ss1 (hpmcat), and the gene sequence of hpfabd was deposited in the genbank databas ... | 2006 | 16413022 |
| helicobacter pylori tissue tropism: mouse-colonizing strains can target different gastric niches. | studies with the mouse-adapted helicobacter pylori strain ss1 had supported an idea that infections by this pathogen start in the gastric antrum and spread to the corpus after extensive mucosal damage. this paper shows that the unrelated strain x47 colonizes the corpus preferentially. differences between strains in preferred gastric region were detected by co-inoculating mice with a mixture of ss1 and x47, and genotyping h. pylori recovered after 2-8 weeks of infection by vaca s allele pcr and r ... | 2003 | 12855741 |
| catalase (kata) and kata-associated protein (kapa) are essential to persistent colonization in the helicobacter pylori ss1 mouse model. | helicobacter pylori infects the human gastric mucosa and elicits an aggressive inflammatory response. despite the severity of the inflammatory response, the bacterium is able to persist and cause a chronic infection. it is believed that antioxidant defence mechanisms enable this organism to persist. wild-type h. pylori strain ss1, and kata- and kapa-deficient mutants, were used to infect c57/bl6 mice to test this hypothesis. neither kata nor kapa was essential for the initial colonization of h. ... | 2003 | 12634335 |
| gastric helicobacter species infection in murine and gerbil models: comparative analysis of effects of h. pylori and h. felis on gastric epithelial cell proliferation. | c57bl/6 mice and mongolian gerbils were infected with helicobacter felis and helicobacter pylori ss1 strain to investigate the effects of different helicobacter species on gastric inflammation and epithelial cell proliferation in different animal models. at 4 weeks, gerbils infected with h. pylori or h. felis developed antral gastritis. onset of gastritis varied between the models, with mice infected with h. pylori having minimal inflammation at 8 weeks. in mice, h. felis, but not h. pylori, ind ... | 2002 | 12402207 |
| the mouse colonizing helicobacter pylori strain ss1 may lack a functional cag pathogenicity island. | | 2002 | 11966874 |
| effects of metronidazole, tetracycline, and bismuth-metronidazole-tetracycline triple therapy in the helicobacter pylori ss1 mouse model after 1 day of dosing: development of an h. pylori lead selection model. | we evaluated the effect of optimized doses and dosing schedules of metronidazole, tetracycline, and bismuth-metronidazole-tetracycline (bmt) triple therapy with only 1 day of dosing on helicobacter pylori ss1 titers in a mouse model. a reduction of bacterial titers was observable with 22.5 and 112.5 mg of metronidazole per kg of body weight (as well as bmt) given twice daily and four times daily (qid). two hundred milligrams of tetracycline per kilogram, given qid, resulted in only a slight redu ... | 2002 | 11959579 |
| in vivo behavior of a helicobacter pylori ss1 nixa mutant with reduced urease activity. | helicobacter pylori mutants devoid of urease activity fail to colonize the gastric mucosa of mice; however, the effect of decreased levels of urease on colonization has not been examined. the nixa gene, required for full urease activity, encodes a cytoplasmic membrane nickel transporter that imports nickel ions and leads to incorporation of nickel ions into apourease. a nixa mutant of the sydney strain of h. pylori (ss1) was constructed by disruption of the nixa gene with a kanamycin resistance ... | 2002 | 11796600 |
| characterization of virulence factors of mouse-adapted helicobacter pylori strain ss1 and effects on gastric hydrophobicity. | gastric infection with helicobacter pylori results in chronic active gastritis and in some individuals is associated with complications such as peptic ulceration and gastric cancers. a balance between bacterial factors and host responses may determine disease outcome. the mouse-adapted h. pylori strain ss1 has been utilized as a model to study disease pathogenesis. although chronic gastritis is observed in this murine model of h. pylori infection, other complications of disease seen in the human ... | 2001 | 11575447 |
| mouse-colonizing helicobacter pylori ss1 is unusually susceptible to metronidazole due to two complementary reductase activities. | in most strains of helicobacter pylori, mutational inactivation of the rdxa (hp0954) gene, which encodes a nitroreductase that converts metronidazole (mtz) from a harmless prodrug to a mutagenic and bacteriocidal product, is sufficient to make this pathogen resistant to clinically significant levels of mtz. here we report that ss1, a strain with the special ability to colonize mice, is unusual in being susceptible to very low concentrations of mtz (0.5 microgram/ml) and in being especially diffi ... | 2000 | 11036035 |
| exposure to metronidazole in vivo readily induces resistance in helicobacter pylori and reduces the efficacy of eradication therapy in mice. | the helicobacter pylori ss1 mouse model was used to characterize the development of resistance in h. pylori after treatment with metronidazole monotherapy and to examine the effect of prior exposure to metronidazole on the efficacy of a metronidazole-containing eradication regimen. mice colonized with the metronidazole-sensitive h. pylori ss1 strain were treated for 7 days with either peptone trypsin broth or the mouse equivalent of 400 mg of metronidazole once a day or three times per day (tid) ... | 1999 | 10103180 |
| immune responses of specific-pathogen-free mice to chronic helicobacter pylori (strain ss1) infection. | a model permitting the establishment of persistent helicobacter pylori infection in mice was recently described. to evaluate murine immune responses to h. pylori infection, specific-pathogen-free swiss mice (n = 50) were intragastrically inoculated with 1.2 x 10(7) cfu of a mouse-adapted h. pylori isolate (strain ss1). control animals (n = 10) received sterile broth medium alone. animals were sacrificed at various times, from 3 days to 16 weeks postinoculation (p.i.). quantitative culture of gas ... | 1998 | 9529052 |