No description available.

Thesis (M. Sc.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 169-189). Also available via the World Wide Web.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Surgery / Master / Master of Surgery

Helicobacter pylori yra unikali bakterija. Ji gyvena skrandyje ir dvylikapirštėje žarnoje bei yra viena iš dažniausiai žmogų infekuojančių mikroorganizmų rūšių. H. pylori buvo antras mikroorganizmas, kurio genomo seka buvo pilnai iššifruota ir paskelbta. Tačiau daugelio H.pylori J99 atviro skaitymo rėmelių funkcijų vis dar nėra nustatytos, be to, nėra duomenų apie jų reikšmę bakterijos gyvybingumui. Esminio geno produktas, kuris yra būtinas šios bakterijos išgyvenimui, gali tapti nauju antimikrobiniu taikiniu efektyvių vakcinų gamyboje arba gali būti panaudotas cheminių inhibitorių, kurie iššauktų mikroorganizmo žūtį, kūrime. Galutinis mūsų darbo tikslas yra nustatyti neesminius Helicobacter pylori J99 bakterijos genus, pritaikant naują Biotechnologijos institute Prokariotų genų inžinerijos laboratorijoje sukurtą metodiką, kuri įgalina gana greitai ir pigiai atlikti bakterijų genomų analizę. Magistrinio darbo tikslas buvo - sukonstruoti reprezentatyvų Helicobacter pylori J99 mutantų rinkinį, atlikti jo pirminę analizę ir sukonstruoti mutacijos taškus genome reprezentuojančius DNR žymenis, kuriuos ateityje numatoma panaudoti neesminių H.pylori J99 genų nustatymui. Tikslo pasiekimui buvo sukonstruota reprezentatyvi H.pylori J99 genomo fragmentų klonoteka, kuri perdengė šios bakterijos genomą ~175 kartus. Taip pat buvo sukonstruota speciali DNR kasetė turinti atsparumą chloramfenikolui sąlygojantį geną. Ši kasetė buvo įterpta į gautos H.pylori J99 klonotekos plazmides per... [toliau žr. visą tekstą] / The availability of total genome sequence information from a variety of bacterial genera has facilitated a dramatic increase in loss of function analysis technologies for pathogenic species of clinical relevance. Elucidation of essential metabolic and biosynthetic pathways in pathogenic organisms is critical for identification of new antimicrobial targets. From a pharmaceutical standpoint, it is the ability to rapidly identify essential genes where loss of function is coincident with loss of viability that is driving force behind genomics-based targets validation. The aim of this work was to construct the mutant‘s pool of Helicobacter pylori J99 for identification of nonessential genes and to prepare large amount of DNA tags representing sites for nonessential genes. To achieve this goal we constructed representable H.pylori J99 DNA library which was composed from 240,000 independent clones and overlap H.pylori J99 genome many times. In parallel, special DNA cassette containing chloramphenicol acetyl transferase gene (cat) which confers the chloramphenicol resistance to the H.pylori was constructed and inserted into cloned H.pylori J99 DNA fragments. At least 12,000 different clones containing correct insertions of DNA cassette were selected. Then total plasmid preparation was used for genetic transformation of H.pylori J99 strain. Cells that survived the allelic exchange were selected on agar media containing chloramphenicol. As allelic exchange results DNA cassette... [to full text]

Infection with the gut-pathogen Helicobacter pylori is the single, most important risk factor in the development of gastric cancer. Although there is a rising incidence in mortality resulting from this malignancy, the exact mechanism underlying the initiation and progression of bacterial-induced gastric tumorigenesis is still not completely understood. Several studies implicate the activation of the Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway as a cellular trigger for promoting carcinogenes. In this thesis, I studied the role of the STAT3 signaling pathway in H. pylori mediated tumorigenesis, and attempted to delineate mechanisms involved. I have found that H. pylori activates the STAT3 signaling pathway both in vitro and in vivo, to promote carcinogenesis. Pivotal for H. pylori mediated STAT3 activation are the bacterial effector protein CagA and host receptor components, the gp130 and the IL-6αR subunits. Further investigation into the mechanism of STAT3 induction identified a key role for cholesterol-enriched membrane lipid rafts. Bacterial invasion and CagA injection into host cells was also dependent on lipid raft integrity. Co-fractionation via the use of sucrose gradients, which permits the isolation of lipid rafts, identified H. pylori CagA to be associated with these membrane microdomains. CagA, once injected into the cell, appears to interact with the inner leaflet of the host plasma membrane via a charge association that either directly or indirectly anchors it to the negatively charged anionic lipids in the cytoplasmic membrane. In addition, janus kinases were recruited to rafts upon H. pylori infection. In this thesis, I present a dynamic model of STAT3 activation, which requires the interaction of lipid raft associated proteins, H. pylori CagA and recruited JAKs with non-lipid raft receptor components to support STAT3 signaling. This study is significant since it provides insight into the possible mechanisms by which H. pylori induces gastric cancer and furthermore, it facilitates the development of novel therapeutic targets directed against bacterial induced carcinogenesis.

No description available.

Thesis (Ph. D.)--University of New South Wales, 2003. / Also available online.

Tübingen, Univ., Diss., 2008.