George Louis Mendz

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Helicobacter hepaticus causes chronic hepatitis and liver cancer in mice. It is the prototype enterohepatic Helicobacter species and a close relative of Helicobacter pylori, also a recognized carcinogen. Here we report the complete genome sequence of H. hepaticus ATCC51449. H. hepaticus has a circular chromosome of 1,799,146 base pairs, predicted to encode(More)
The antimicrobial effect of nitric oxide (NO) is an essential part of innate immunity. The vigorous host response to the human gastric pathogen Helicobacter pylori fails to eradicate the organism, despite up-regulation of inducible NO synthase (iNOS) in the gastric mucosa. Here we report that wild-type strains of H. pylori inhibit NO production by activated(More)
The publication of the complete sequence of Helicobacter pylori 26695 in 1997 and more recently that of strain J99 has provided new insight into the biology of this organism. In this review, we attempt to analyze and interpret the information provided by sequence annotations and to compare these data with those provided by experimental analyses. After a(More)
Utilization of aminoacids during growth by laboratory adapted and wild type Helicobacter pylori strains was investigated employing nuclear magnetic resonance spectroscopy and aminoacid analysis. All H. pylori strains tested showed growth rates with doubling times of approx. 11.5 hr in liquid cultures with semi-defined media or with defined aminoacid broth(More)
The urea cycle enzyme arginase (EC 3.5.3.1) hydrolyzes l-arginine to l-ornithine and urea. Mammalian arginases require manganese, have a highly alkaline pH optimum and are resistant to reducing agents. The gastric human pathogen, Helicobacter pylori, also has a complete urea cycle and contains the rocF gene encoding arginase (RocF), which is involved in the(More)
Campylobacter jejuni is a pathogen that colonizes the intestinal tract of humans and some animals. The in vitro responses of the bacterium to ox-bile were studied using proteomics to understand the molecular mechanisms employed by C. jejuni to survive bile stress. Its in vitro tolerance to bile was determined by growing the bacterium for 18 h in liquid(More)
Disulphide reductases play an important role in maintaining intracellular redox potential. Three disulphide reductase activities were identified in Helicobacter pylori, which used dithiobis-2-nitrobenzoic acid, glutathione or l-cystine and ferredoxin as substrates. The kinetic parameters of these activities were determined and it was demonstrated that the(More)
The metabolism of pyruvate by Helicobacter pylori was investigated employing one- and two-dimensional 1H and 13C nuclear magnetic resonance spectroscopy. Generation of pyruvate from l-serine in incubations with whole cell lysates indicated the presence of serine dehydratase activity in the bacterium. Pyruvate was formed also in cell suspensions and lysates(More)
BACKGROUND There is no general consensus about the specific oxygen and carbon dioxide requirements of the human pathogen Helicobacter pylori. This bacterium is considered a microaerophile and consequently, it is grown under atmospheres at oxygen tensions 5-19% and carbon dioxide tensions 5-10%, both for clinical and basic and applied research purposes. The(More)