Genome Evolution and Virulence in H. Pylori PDF Download
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Author: Elvire Berthenet
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Elvire Berthenet
Publisher:
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Category :
Languages : en
Pages :
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Author: Nicole Tegtmeyer
Publisher: Springer
ISBN: 3319505203
Category : Medical
Languages : en
Pages : 364
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This volume reviews the current state of research concerning bacterial virulence factors and the infection biology of Helicobacter pylori, which is the leading cause of peptic ulcers and gastric cancer worldwide. The chapters include cutting-edge findings on this fascinating microbe and discuss the general strategies of H. pylori infection and persistence, news on important H. pylori virulence factors, crosstalk with the microbiota, hot novel models and signaling mechanisms, risk factors of gastric disease and stomach cancer, and the impact of H. pylori infection on non-gastric diseases. Written by internationally respected scientists, this book will appeal to clinicians, researchers and advanced students alike.
Author:
Publisher:
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Category :
Languages : en
Pages : 0
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Author: Shigeru Kamiya
Publisher: Springer Nature
ISBN: 303021916X
Category : Medical
Languages : en
Pages : 284
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This book gathers a wealth of contributions on the virulence factors and pathogenic mechanism of Helicobacter pylori, prepared by leading international experts. In addition, it explores the epidemiology, diagnosis, treatment with drugs and probiotics, and prophylaxis by vaccination, reflecting the latest advances. H. pylori is a Gram negative microaerophilic bacterium that can produce various gastric diseases including gastritis, gastroduodenal ulceration, gastric cancer and gastric MALT lymphoma. Although efforts to combat H. pylori using a combination of proton pump inhibitor and several antimicrobial drugs have significantly decreased the burden of these gastric diseases, the microbial epidemiology and gastric pathogenesis following H. pylori infection are still not fully understood. Given its scope, the book offers a valuable resource not only for basic microbiologists, but also for researchers in the fields of pathology, biochemistry and genomics, as well as medical students/scientists.
Author: Montserrat Palau de Miguel
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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"In the past decades, Helicobacter pylori has received the attention of many researchers because of its known relation with gastric cancer. Although many studies have tried to decipher the exact relation between the bacteria and cancer state, and several virulence factors have been discovered, an exact answer has not been found yet. Further work should be made in order to study more accurately the genome of this bacterium and to understand its precise involvement. The bacterium is characterised for a highly genetic diversity, meaning it is continuously changing in order to adapt itself to its hostile niche, the human stomach.Infection by H. pylori is estimated to affect half of the world's population, being more extended in developing countries than in developed ones, possibly due to the high consumption of antibiotics and the increased level of sanitation in the latest. It has been demonstrated that the gastric lumen can be colonized by more than just one strain of the bacterium, sometimes these strains could have evolved from the same 'mother' strain, or they could come from unrelated strains. The study of these situations is important in order to elucidate if there is just one strain who is responsible for starting the pathogenic cascade, and what are the specific differences between the different strains that inhabit the human stomach.On the first work of this thesis, our group studied the usefulness of six housekeeping genes for the detection of H. pylori infection and the characterization of various strains isolated from gastric isolates, studying as well their phylogeny. In some cases, the distance value between the strains was high, indicating and event of multiple infection. In other cases, small differences were found between clones, suggesting events of microevolution rather than multiple infection.This work was further extended with the study of the usefulness of amplicon sequencing of these housekeeping genes in the detection of microevolution and mixed infections from gastric biopsies of patients with dyspeptic symptoms and different histopathological findings (from atrophy to adenocarcinoma). Five gastric biopsies from four patients infected by H. pylori were involved in this study. We detected in all the analyzed gastric biopsies multiple H. pylori infections with a predominant strain. These results suggest that H. pylori colonizes the human stomach through diverse infection circumstances that lead to a gastric multi-infection with a predominant strain together alongside other minority strains. Furthermore, it was shown that mixed infections are the main status in the colonization of the human gastric mucosa.The last part of this thesis started with a preliminary study of 51 complete sequencedH. pylori genomes and further focused on three genomes obtained from the same patient in order to analyse and compare them. Particularly, these isolates were sampled at the same time from a stomach with adenocarcinoma, one strain was from the non- tumoral tissue, and the other two were isolated from the tumoral tissue. They all lacked from the most noticeable virulence factor, the cag pathogenicity island; one of the most studied and the main factor related to the malignancy of the bacterium. On the other hand, we found differences in the genotype of the vacuolating cytotoxin gene (vacA) and in genes related with urease, the outer membrane and flagella.Despite the contributions made in this thesis, further studies are needed to find better genetic markers of H. pylori related to virulence and progression to gastric cancer." -- TDX.
Author: J. Hacker
Publisher: Springer
ISBN: 9783540426820
Category : Medical
Languages : en
Pages : 444
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It has been known for a number of years that not only pathogenicity islands but also plasmids and bacteriophages are able to carry genes whose products are involved in pathogenic processes. Accordingly, such elements and their products play an important role in pathogenesis due to the intestinal E. coli as well to Shigellae. Another interesting aspect which is reflected in different articles is that genomes evolve by acquisition of new pieces of DNA following gene transfer, but also by genome reduction. Different mechanisms include the deletion of sequences or the elimination of functions by the accumulation of point mutations or rearrangements.
Author: James Luke Hale
Publisher:
ISBN:
Category : Helicobacter pylori
Languages : en
Pages : 470
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Author: Amelia M. Bothwell
Publisher:
ISBN:
Category : Helicobacter pylori
Languages : en
Pages : 126
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"Helicobacter pylori is a spiral, gram-negative bacterium that colonizes the stomachs of approximately 50% of the World's population overall and is a major etiological agent of human gastric adenocarcinoma. Of infected individuals, only 10-15% develop severe gastric disease due to environmental factors, host genetic factors, and more significantly, genetic differences in the infecting H pylori strains. Type I strains of H pylori contain a 40-kb cytotoxin-associated pathogenicity island (cag PAl) that encodes and secretes the CagA protein into host epithelial cells via a type IV secretion system. To date, CagA is the only identified effector protein of the cag PAI. The goal of this study was to identify novel H pylori virulence factors, to further elucidate their role in H pylori virulence and their potential as novel effectors of the cag PAI. In the work presented here, we generated an H pylori genomic plasmid library and screened this library in Saccharomyces cerevisiae for toxic effects. We initially identified 2 candidate H pylori virulence factors, however, after further analysis these candidates were not toxic to S. cerevisiae and are no longer genes of interest. To identify novel H pylori virulence factors, others in the lab are addressing pitfalls found in this study to conduct a better-structured screen that we believe will be successful in identifying H pylori genes of interest"--Document.
Author: Kalyani Putty
Publisher:
ISBN:
Category : Helicobacter pylori
Languages : en
Pages : 242
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Background: Helicobacter pylori (Hp) establishes life-long gastric infection in billions of humans, and is often responsible for diseases such as peptic ulcer and gastric cancer. Cumulative actions of genetic drift and natural selection over several millennia sculpted the present Hp population structure, which is characterized by extreme genetic diversity and striking geographic clustering of genotypes. Natural selection is more commonly imprinted in DNA sequences of Hp proteins that interact with host components; however, in most instances biological relevance of selection during Hp infection remains unknown. Here, I attempted to elucidate the consequence of natural selection in two different contexts: (1) on the preservation of duplicated genes in Hp genome; and (2) lineage-specific adaptive evolution in Hp virulence protein HepC. Principle Findings: I characterized the molecular evolutionary dynamics of paralogs, hcpC and hcpG, which belong to the Hp Sell-like gene family. hcpG genomic analyses identified three distinct states in natural Hp populations, whereby hcpG was either deleted, pseudogenized or encoded highly polymorphic alleles. In contrast, full-length hcpC alleles were conserved in all genomes. Although positive selection was detected in the phylogenies of hcpG and hcpC indicating that both genes had evolved under pressure to diversify, the intensity of selection was much stronger on hcpG than hcpC. The contribution of hcpC to Hp fitness, in the AGS cell culture infection model, was significantly greater than hcpG; however, both genes together demonstrated an additive effect on Hp fitness during infection (24 hrs pj.: S.1hcpc= 0.264 vs. S.1hcpG= 0.074, P
Author: Ricky V.L Chan
Publisher: Springer Science & Business Media
ISBN: 1597451525
Category : Medical
Languages : en
Pages : 276
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The first bacterial genome, Haemophilus influenzae, was completely sequenced, annotated, and published in 1995. Today, more than 200 prokaryotic (archaeal and bacterial) genomes have been completed and over 500 prokaryotic genomes are in va- ous stages of completion. Seventeen eukaryotic genomes plus four eukaryotic chro- somes have been completed. The concept of achieving better understanding of an organism through knowledge of the complete genomic sequence was first demonstrated in 1978 when the first bacteriophage genome, X174, was sequenced. Complete genomic sequences of prokaryotes have led to a better understanding of the biology and evolution of the microbes, and, for pathogens, facilitated identification of new vaccine candidates, putative virulence genes, targets for antibiotics, new strategy for rapid diagnosis, and investigation of bacteria–host interactions and disease mec- nisms. Recent increased interest in microbial pathogens and infectious diseases is largely attributed to the re-emergence of infectious diseases like tuberculosis, emergence of new infectious diseases like AIDS and severe acute respiratory syndrome, the problem of an increasing rate of emergence of antibiotic-resistant variants of pathogens, and the fear of bioterrorism. Microbes are highly diverse and abundant in the biosphere. Less than 1% of these morphologically identified microbes can be cultured in vitro using standard techniques and conditions. With such abundance of microbes in nature, we can expect to see new variants and new species evolve and a small number will emerge as pathogens to humans.
