Effect of omeprazole on intragastric bacterial counts, nitrates, nitrites, and N-nitroso compounds.

Verdú, Elena F.; Viani, F.; Armstrong, David; Fraser, Robert; Siegrist, Hans H.; Pignatelli, Brigitte; Idström, Jan‐Peter; Cederberg, Christer; Blum, A. L.; Fried, Michael

doi:10.1136/gut.35.4.455

Cited by 127 publications

(80 citation statements)

References 35 publications

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“…In the stomach, E. coli must survive high levels of inorganic acid and both inorganic and organic acids in the small intestine. In the stomach of a healthy human who fasts, the pH is typically about 2.0 (43). Under acidic conditions, the need to maintain cytoplasmic pH homeostasis may be mitigated by the pH gradient that exists across the cytoplasmic membrane serving as a source of energy, decreasing the fitness load caused by limited nutrient availability (19).…”

Section: Discussionmentioning

confidence: 99%

The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

2003

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Escherichia coli cells that are aged in batch culture display an increased fitness referred to as the growth advantage in stationary phase, or GASP, phenotype. A common early adaptation to this culture environment is a mutant rpoS allele, such as rpoS819, that results in attenuated RpoS activity. However, it is important to note that during long-term batch culture, environmental conditions are in flux. To date, most studies of the GASP phenotype have focused on identifying alleles that render an advantage in a specific environment, Luria-Bertani broth (LB) batch culture. To determine what role environmental conditions play in rendering relative fitness advantages to E. coli cells carrying either the wild-type or rpoS819 alleles, we performed competitions under a variety of culture conditions in which either the available nutrients, the pH, or both were manipulated. In LB medium, we found that while the rpoS819 allele confers a strong competitive fitness advantage at basic pH, it confers a reduced advantage under neutral conditions, and it is disadvantageous under acidic conditions. Similar results were found using other media. rpoS819 conferred its greatest advantage in basic minimal medium in which either glucose or Casamino Acids were the sole source of carbon and energy. In acidic medium supplemented with either Casamino Acids or glucose, the wild-type allele conferred a slight advantage. In addition, populations were dynamic under all pH conditions tested, with neither the wild-type nor mutant rpoS alleles sweeping a culture. We also found that the strength of the fitness advantage gained during a 10-day incubation is pH dependent.

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Section: Discussionmentioning

confidence: 99%

The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

2003

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“…The conditions used in our study are similar to those occurring in natural H. pylori infection, where H. pylori and other organisms enter the stomach through the mouth (4,23). Before reaching the gastric mucosa, H. pylori encounters the acidic (pH 1 to 6) stomach contents.…”

Section: ϫ8mentioning

confidence: 93%

Pretreatment with Urea-Hydrochloric Acid Enhances the Isolation of Helicobacter pylori from Contaminated Specimens

et al. 2001

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Human saliva seeded with H. pylori was incubated in urea-HCl and then cultured on nonselective media. Pretreatment with 0.06 N HCl-0.08 M urea for 5 min at 37°C resulted in reproducible isolation of H. pylori, even at low inocula (<10 2 CFU/ml of saliva), despite the presence of large numbers of contaminating organisms.The transmission route and source of Helicobacter pylori infection remain unclear. The presence of H. pylori DNA in the oral cavity, feces, and water has been demonstrated using PCR (7,10,17,21), but the culture of H. pylori from these specimens using established methods is quite difficult (1,2,6,18,22). These specimens may contain low numbers of H. pylori organisms (20), which are likely to be overgrown by more abundant populations of rapidly growing competing microorganisms even on selective media. Urease is found in the cytoplasm and on the membrane of H. pylori cells (5,8). Compared to other ureasepositive microorganisms, H. pylori produces larger quantities of highly active urease (5,9,19). Urease hydrolyzes urea, creating a basic "ammonia cloud" around the bacteria, thereby allowing H. pylori to survive at low pH in the presence of urea under conditions similar to those in the stomach (3,12,16). The aim of this study was to develop a new method using short-duration exposures to hydrochloric acid (HCl) plus urea to facilitate the isolation of H. pylori from highly contaminated specimens.Local institutional review board approval for specimen collection was obtained, and patients gave informed written consent. Saliva was obtained from an H. pylori-negative volunteer. Primary H. pylori cultures were obtained from patients undergoing upper endoscopy. H. pylori type strain ATCC 43504 was grown on heart infusion agar with 5% rabbit blood (BBL, Cockeysville, Md.) for 48 h at 37°C under microaerobic conditions (85% N 2 , 10% CO 2 , 5% O 2 ) and then suspended in normal saline for the following assays. First, pure cultures of H. pylori were tested to determine survival in various urea-HCl concentration ranges. Ten microliters of the diluted suspension (ϳ10 5 CFU of H. pylori) was incubated with 5 l of urea and 10 l of HCl at various concentrations for 5 min at room temperature and then serially diluted in 1 ml of phosphatebuffered saline (PBS). One-hundred-microliter aliquots of each dilution were then plated onto heart infusion agar. After the 5-day microaerobic incubation, colonies were counted. Control cultures were carried out using PBS instead of ureaHCl under the same conditions. Additional experiments were conducted to assess incubation time and temperature (4 to 37°C) effects on the survival of H. pylori exposed to urea-HCl. Second, saliva spiked with different concentrations of H. pylori was tested using the procedures above. Optimal urea and HCl concentrations were determined based on H. pylori survival and minimal growth of other microorganisms. Third, the minimum number of H. pylori CFU that could be inoculated into saliva and successfully recovered was determined using the optimal urea-HC...

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“…56,57 The first hint came in the early 1960s from Norway, when sheep died of liver toxicity after feeding nitrite-preserved herring meal. 57,58 The effect of nitrate, nitrite, and NOCs on human health has been a recurrent issue with respect to cancer [59][60][61][62] due to unawareness of the general population exposure to NOCs, namely, diethylnitrosamine (DEN), present in foods, beverages, tobacco smoke, 57,[63][64][65] drinking water, and industrial pollution. 66,67 Endogenous synthesis of NOCs are also mentioned for being responsible for 45%-75% of total exposure.…”

Section: Experimentally Induced Liver Tumorsmentioning

confidence: 99%

Animal models as a tool in hepatocellular carcinoma research: A Review

2017

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Cancer is the first cause of death in developed countries and the second in developing countries. Concerning the most frequent worldwide-diagnosed cancer, primary liver cancer represents approximately 4% of all new cancer cases diagnosed globally. However, among primary liver cancer, hepatocellular carcinoma is by far the most common histological subtype. Notwithstanding the health promotion and disease prevention campaigns, more than half a million new hepatocellular carcinoma cases are reported yearly, being estimated to growth continuously until 2020. Taking this scenario under consideration and the fact that some aspects concerning hepatocellular carcinoma evolution and metastasize process are still unknown, animal models assume a crucial role to understand this disease. The animal models have also provided the opportunity to screen new therapeutic strategies. The present review was supported on research and review papers aiming the complexity and often neglected chemically induced animal models in hepatocarcinogenesis research. Despite the ongoing debate, chemically induced animal models, namely, mice and rat, can provide unique valuable information on the biotransformation mechanisms against xenobiotics and apprehend the deleterious effects on DNA and cell proteins leading to carcinogenic development. In addition, taking under consideration that no model achieves all hepatocellular carcinoma research purposes, criteria to define the "ideal" animal model, depending on the researchers' approach, are also discussed in this review.

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Effect of omeprazole on intragastric bacterial counts, nitrates, nitrites, and N-nitroso compounds.

Cited by 127 publications

References 35 publications

The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

The Growth Advantage in Stationary-Phase PhenotypeConferred by rpoS Mutations Is Dependent on the pH andNutrientEnvironment

Pretreatment with Urea-Hydrochloric Acid Enhances the Isolation of Helicobacter pylori from Contaminated Specimens

Animal models as a tool in hepatocellular carcinoma research: A Review

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