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Author: Montserrat Palau de Miguel
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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Book Description
"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: Montserrat Palau de Miguel
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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Book Description
"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: Manabesh Nath
Publisher: GRIN Verlag
ISBN: 3668730148
Category : Science
Languages : en
Pages : 29
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Book Description
Seminar paper from the year 2013 in the subject Biology - Miscellaneous, grade: 8.30, Amity University (Amity Institute of Biotechnology), course: Master of Technology, language: English, abstract: Helicobacter pylori is a gram-negative pathogen whose ecological niche is the human stomach that colonizes over half the world’s population and causes a spectrum of gastric diseases including gastritis, ulcers, and gastric carcinoma. The H. pylori species exhibits unusually high levels of genetic variation between strains. H pylori infection is more frequent in less developed Asian countries like India, Bangladesh, Pakistan, and Thailand and is acquired at early age than in more developed Asian countries like Japan and China. Helicobacter pylori is one of the most diverse bacterial species that chronically infects more than 70% of Indian population. The most commonly recognized manifestation of H. pylori infection in India is peptic ulcer disease, particularly duodenal ulcer disease, which outnumbers gastric ulcers between 8:1 and 30:1. Helicobacter pylori was the first organism for which the genome sequence of multiple isolates was determined, revealing a great deal of genetic variation at both the sequence and gene content levels. While the core genes encode most metabolic and cellular processes, the strain-specific genes include genes unique to H. pylori, restriction modification genes, transposases, and genes encoding cell surface proteins, which may aid the bacteria under specific circumstances during their long-term infection of genetically diverse hosts. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host–pathogen interaction. It is thought that the persistent accumulation of mutations within the genome may make an important contribution to the extraordinary genetic diversity of H. pylori and allow adaptation to new environmental challenges within the stomach. The overall picture depicts H pylori as a causative organism for peptic and gastric ulcers including carcinomas with wide range of variation amongst its genes; having characteristic genome variability and hence, with a very high prevalence in developing countries including India. The genetic diversification holds the key towards adaptation and interaction of H. pylori with the human host.
Author: Hervé Tettelin
Publisher: Springer Nature
ISBN: 3030382818
Category : Science
Languages : en
Pages : 311
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Book Description
This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book’s respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics.
Author: Michel Tibayrenc
Publisher: Elsevier
ISBN: 0123848903
Category : Medical
Languages : en
Pages : 773
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Book Description
Genetics and Evolution of Infectious Diseases is at the crossroads between two major scientific fields of the 21st century: evolutionary biology and infectious diseases. The genomic revolution has upset modern biology and has revolutionized our approach to ancient disciplines such as evolutionary studies. In particular, this revolution is profoundly changing our view on genetically driven human phenotypic diversity, and this is especially true in disease genetic susceptibility. Infectious diseases are indisputably the major challenge of medicine. When looking globally, they are the number one killer of humans and therefore the main selective pressure exerted on our species. Even in industrial countries, infectious diseases are now far less under control than 20 years ago. The first part of this book covers the main features and applications of modern technologies in the study of infectious diseases. The second part provides detailed information on a number of the key infectious diseases such as malaria, SARS, avian flu, HIV, tuberculosis, nosocomial infections and a few other pathogens that will be taken as examples to illustrate the power of modern technologies and the value of evolutionary approaches. Takes an integrated approach to infectious diseases Includes contributions from leading authorities Provides the latest developments in the field
Author:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 1796
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Book Description
Author: Didier Raoult
Publisher: Springer Science & Business Media
ISBN: 3540758550
Category : Science
Languages : en
Pages : 228
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Book Description
This fascinating new volume comes complete with color illustrations and features the methodology and main achievements in the emerging field of paleomicrobiology. It’s an area research at the intersection of microbiology and evolution, history and anthropology. New molecular approaches have already provided exciting results, such as confirmation of a single biotype of Yersinia pestis as the cause of historical plague pandemics. An absorbing read for scientists in related fields.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 652
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Book Description
Author: Institute of Medicine
Publisher: National Academies Press
ISBN: 0309264324
Category : Medical
Languages : en
Pages : 633
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Book Description
Beginning with the germ theory of disease in the 19th century and extending through most of the 20th century, microbes were believed to live their lives as solitary, unicellular, disease-causing organisms . This perception stemmed from the focus of most investigators on organisms that could be grown in the laboratory as cellular monocultures, often dispersed in liquid, and under ambient conditions of temperature, lighting, and humidity. Most such inquiries were designed to identify microbial pathogens by satisfying Koch's postulates.3 This pathogen-centric approach to the study of microorganisms produced a metaphorical "war" against these microbial invaders waged with antibiotic therapies, while simultaneously obscuring the dynamic relationships that exist among and between host organisms and their associated microorganisms-only a tiny fraction of which act as pathogens. Despite their obvious importance, very little is actually known about the processes and factors that influence the assembly, function, and stability of microbial communities. Gaining this knowledge will require a seismic shift away from the study of individual microbes in isolation to inquiries into the nature of diverse and often complex microbial communities, the forces that shape them, and their relationships with other communities and organisms, including their multicellular hosts. On March 6 and 7, 2012, the Institute of Medicine's (IOM's) Forum on Microbial Threats hosted a public workshop to explore the emerging science of the "social biology" of microbial communities. Workshop presentations and discussions embraced a wide spectrum of topics, experimental systems, and theoretical perspectives representative of the current, multifaceted exploration of the microbial frontier. Participants discussed ecological, evolutionary, and genetic factors contributing to the assembly, function, and stability of microbial communities; how microbial communities adapt and respond to environmental stimuli; theoretical and experimental approaches to advance this nascent field; and potential applications of knowledge gained from the study of microbial communities for the improvement of human, animal, plant, and ecosystem health and toward a deeper understanding of microbial diversity and evolution. The Social Biology of Microbial Communities: Workshop Summary further explains the happenings of the workshop.
Author: Institute of Medicine
Publisher: National Academies Press
ISBN: 0309268192
Category : Science
Languages : en
Pages : 429
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Book Description
Over the past several decades, new scientific tools and approaches for detecting microbial species have dramatically enhanced our appreciation of the diversity and abundance of the microbiota and its dynamic interactions with the environments within which these microorganisms reside. The first bacterial genome was sequenced in 1995 and took more than 13 months of work to complete. Today, a microorganism's entire genome can be sequenced in a few days. Much as our view of the cosmos was forever altered in the 17th century with the invention of the telescope, these genomic technologies, and the observations derived from them, have fundamentally transformed our appreciation of the microbial world around us. On June 12 and 13, 2012, the Institute of Medicine's (IOM's) Forum on Microbial Threats convened a public workshop in Washington, DC, to discuss the scientific tools and approaches being used for detecting and characterizing microbial species, and the roles of microbial genomics and metagenomics to better understand the culturable and unculturable microbial world around us. Through invited presentations and discussions, participants examined the use of microbial genomics to explore the diversity, evolution, and adaptation of microorganisms in a wide variety of environments; the molecular mechanisms of disease emergence and epidemiology; and the ways that genomic technologies are being applied to disease outbreak trace back and microbial surveillance. Points that were emphasized by many participants included the need to develop robust standardized sampling protocols, the importance of having the appropriate metadata, data analysis and data management challenges, and information sharing in real time. The Science and Applications of Microbial Genomics summarizes this workshop.
Author: Hervé Tettelin
Publisher:
ISBN: 9781013277078
Category : Science
Languages : en
Pages : 310
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Book Description
This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book's respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.
