TIMOTHY COVER

..pylori...

..In this study, we investigated whether and how LuxS controls motility of H. pylori, specifically if it has its effects via luxS-required cysteine metabolism or via AI-2 synthesis only...

..To test this hypothesis, we introduced eight deletion mutations (each corresponding to a single coil within a beta-helical segment spanning VacA amino acids 433-628) into the H. pylori chromosomal vacA gene...

..In this study, we analyzed the genome sequences of an H. pylori strain (98-10) isolated from a patient with gastric cancer and an H. pylori strain (B128) isolated from a patient with gastric ulcer disease...

..The actions of H. pylori VacA represent a paradigm for how bacterial secreted toxins contribute to colonization and virulence in multiple ways...

..Downregulation of T cell responses by VacA may allow H. pylori to evade the adaptive immune response and establish persistent infection...

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..pylori grown under low salt conditions. Up-regulation of H. pylori cagA expression in response to high salt concentrations may be a factor that contributes to the development of gastric adenocarcinoma...

..Geographic variation in the genetic characteristics of H. pylori strains may be a factor contributing to geographic variation in gastric cancer incidence...

..It is speculated that inappropriate waning of the innate immune response during early stages of infection may be a factor that contributes to H. pylori persistence...

..Molecular modeling of an ArsR-DBD-DNA complex permits identification of protein elements that are predicted to bind target DNA sequences and thereby regulate gene transcription in H. pylori...

..pylori-infected persons may result from strain-dependent variations in VacA structure...

..Identifying the epitopes recognized by these neutralizing antibodies constitutes an important first step in the development of therapeutic agents that could be used to counter the effects of the epsilon-toxin...

..In contrast to many chronic inflammatory diseases in which IL-17RA signaling promotes an inflammatory response, IL-17RA signaling down-regulates the chronic mononuclear inflammation elicited by H. pylori infection...

..Here, we purify and characterize 2 secreted LGG proteins that regulate intestinal epithelial cell antiapoptotic and proliferation responses...

..These data indicate that in some strains of H. pylori, the HopQ protein can attenuate bacterial adherence to gastric epithelial cells...

..Because EGFR signaling regulates cell survival, we investigated whether activation of EGFR following H pylori infection promotes gastric epithelial survival...

..tuberculosis were negative for IS6110. We provide evidence that one of a variety of Mycobacterium species, especially organisms resembling M. tuberculosis, is found in most patients with sarcoidosis...

..pylori strains. Further studies in multiple populations of patients are indicated to evaluate the usefulness of this approach for distinguishing potentially ulcerogenic H. pylori strains from less virulent strains...

..pylori transcript abundance at acid pH. These studies document the complex response of H. pylori to environmental pH changes, and provide insight into mechanisms used for intragastric survival...

..Helicobacter pylori inhabits a highly restricted ecological niche in the human gastric mucosa. Microbial gene expression in the context of persistent infection remains largely uncharacterized...

..These results provide further definition of the ArsRS regulon and underscore the importance of the ArsRS system in regulating expression of H. pylori proteins during bacterial growth at both neutral pH and acidic pH...

..This suggests that the resistance of primary murine CD4+ T cells to VacA is attributable, at least in part, to impaired VacA binding to these cells...

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..Taken together, these results indicate that positive selection has shaped the phylogenetic structure of VacA and CagA, and each of these virulence determinants has evolved separately from the core genome...

..pylori resists immune clearance and also are relevant for understanding the pathogenesis of diseases caused by H. pylori (peptic ulcer disease, gastric adenocarcinoma, and gastric lymphoma)...

..We propose that the immunomodulatory actions of VacA on T and B lymphocytes, the major effectors of the adaptive immune response, may contribute to the ability of H. pylori to establish a persistent infection in the human gastric mucosa...

..Docking of the p55 structure into a 19-A cryo-EM map of a VacA dodecamer allows us to propose a model for how VacA monomers assemble into oligomeric structures capable of membrane channel formation...

..Mutating the luxS gene eliminates growth-phase-dependent control of flaA, and this growth phase dependence is restored when the luxS mutant strain is complemented with the wild-type luxS gene...

..These results indicate that intact HP0165 and HP1364 histidine kinases are required for acid resistance in H. pylori...

..Protein-protein interactions among Cag proteins are likely to have an important role in the assembly of the H. pylori type IV secretion apparatus...

..Heterogeneity among H. pylori strains in expression of the BabA protein may be a factor that contributes to differing clinical outcomes among H. pylori-infected humans...

..We speculate that VacA-induced alterations in late endocytic membrane traffic contribute to the capacity of H. pylori to persistently colonize the human gastric mucosa...

..These data indicate that the assembly of functional oligomeric VacA complexes is dependent on specific sequences, including amino acids 346 and 347, within the p55 amino-terminal subdomain...

..These results suggest that VacA inhibits T-cell activation and HIV infection via a novel mechanism. Identifying the host cell targets of VacA could be useful for elucidating the HIV life cycle within primary T cells...

..In addition, these are the first examples of mutant VacA proteins that have defects in vacuolating activity despite exhibiting channel activities similar to those of wild-type VacA...

..We suggest that VacA may inhibit the clonal expansion of T cells that have already been activated by H. pylori antigens, thereby allowing H. pylori to evade the adaptive immune response and establish chronic infection...

..These results provide evidence that interactions between p-33 and p-55 domains play an important role in VacA assembly into oligomeric structures...

..The capacity to analyze VacA in this heterologous-expression system should greatly facilitate efforts to elucidate the structure and function of this toxin...

..We propose that the oligomerization observed in these experiments mimics the process by which VacA oligomerizes when in contact with membranes of host cells...

..Reconstitution of toxin activity from two separate domains, as described here for VacA, has rarely been described for pore-forming bacterial toxins, which suggests that VacA is a pore-forming toxin with unique structural properties...

..Helicobacter pylori infection is a risk factor for the development of gastric cancer, and the bacterial oncoprotein CagA contributes to gastric carcinogenesis...

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..These data indicate that VacA associates with lipid raft microdomains in the absence of GPI-anchored proteins and suggest that association of the toxin with lipid rafts is important for VacA cytotoxicity...

..These findings indicate that L-Arg is rate limiting for iNOS translation and suggest that the levels of L-Arg that occur in vivo do not permit sufficient NO generation by the host to kill H. pylori...

..pylori-induced inhibition of acid secretion. Our results indicate that VacA disrupts the apical membrane-cytoskeletal interactions in gastric parietal cells and thereby causes hypochlorhydria...

..These results provide more insight into how H. pylori and MAPK modulate AP-1 subcomponents in gastric epithelial cells to alter the expression of downstream target genes and affect cellular functions...

..In an Asian-American population, serologic responses to VacA m region-specific antigens were not able to predict the risk of development of gastric cancer...

..Strain-dependent variations in differential expression were also detected. These results indicate that the signal transduction circuit utilizing HK0164 controls the transcription of at least seven genes in H. pylori...

..These findings are the first to show that H. pylori alters [Ca2+]i in normal GMEC through a Ca2+ release/influx mechanism that depends on expression of cagA and picB/cagE genes...

..Altogether, these data suggest that antigens derived from apoptotic and necrotic cells require access to the cytosol to intersect with the conventional MHC class I pathway for presentation of cytosolic proteins...

..These results indicate that VacA is able to undergo major conformational changes, accompanied by major changes in its state of oligomerization, under different natural and experimental conditions...

..A low G+C content of these two genes suggests they were acquired by horizontal transfer events...

..pylori strains. Also tenable is a model in which AI-2 affects other microbes in H. pylori's gastric ecosystem and thereby modulates the gastric environment in ways to which certain H. pylori strains are particularly sensitive...

..As a result, VacA can perturb, but not necessarily abolish, the homeostatic ionic imbalance across a membrane and so change cellular physiology without necessarily jeopardizing vitality...

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..These data indicate that there is marked heterogeneity among H. pylori strains in babA genetic content and BabA expression...

..Therefore it is probable that the association of VacA with rafts in DOPC/SM/cholesterol bilayers represents a useful model for understanding the interactions of VacA with membranes in vivo...

..These data indicate that cellular vacuolation and mitochondrial cytochrome c release are two independent outcomes of VacA intoxication and that both effects are dependent on the formation of anion-selective membrane channels...

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..Introduction of anion channel activity into glial cells might provide a novel approach for treating cerebral edema, which is associated with lactacidosis in cerebral ischemia or head injury...

..Ultimately, these studies may lead to advances in the treatment or prevention of H. pylori-associated human diseases. ..

..These studies should result in a better understanding of the H. pylori factors that help to determine clinical outcome, and ultimately, may lead to advances in the treatment or prevention of H. pylori-associated human diseases. ..

..This research seeks to understand how a bacterial infection can lead to these diseases, and seeks to develop new approaches for the prevention and therapy of stomach cancer and peptic ulcer disease. ..

..This research seeks to understand how a bacterial infection can lead to these diseases. The long-term goals are to develop effective means for the prevention and treatment of stomach cancer and peptic ulcer disease. ..

..This research seeks to understand how a bacterial infection can lead to these diseases, and seeks to develop new approaches for the prevention and therapy of stomach cancer and peptic ulcer disease. ..

..This research seeks to understand how a bacterial infection can lead to these diseases. The long-term goals are to develop effective means for the prevention and treatment of stomach cancer and peptic ulcer disease. ..

..Understanding the structure and regulation of the vacuolating cytotoxin may aid in the development of strategies to prevent and treat H. pylori-associated gastroduodenal illnesses. ..

..Understanding the mechanisms whereby VacA binds to and enters cells may ultimately result in the development of strategies to prevent and treat H. pylori-associated gastroduodenal illnesses. ..

..This research seeks to understand how a bacterial infection can lead to these diseases, and seeks to develop new approaches for the prevention and therapy of stomach cancer and peptic ulcer disease. ..