Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Helicobacter pylori (HP) has been shown to possibly be a pathogen of gastric carcinoma. HP has urease activity and produces ammonia in the stomach. In this study, the role of ammonia on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in rats. After 24 weeks pretreatment with MNNG (83 mg/l), 0.01% ammonia or tap water as a drinking water was administered for 24 weeks. The ammonia-treated rats showed a significantly higher incidence of gastric cancer (percent of animals with tumors and number of tumors per rat). Ammonia would thus appear to have an important role in HP-related human gastric carcinogenesis.
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PMID:Ammonia: a possible promotor in Helicobacter pylori-related gastric carcinogenesis. 151 5

NH2-terminal amino acid sequence of the pS2 protein produced and secreted by human gastric cancer cells, MKN-45, was determined to be identical to that of MCF-7 cells. A clone encoding pS2 protein was isolated from the cDNA library constructed from MKN-45 cells. The nucleotide sequence was identical to that of pS2 cDNA previously isolated from human breast cancer cells, MCF-7, except for one nucleotide in the 3' untranslated region. Thus, in this cell line, the pS2 gene product is translated and secreted as in MCF-7 cells. RNA blot hybridization analysis revealed that pS2 gene was expressed well in two (MKN-45 and KATO-III; derived from poorly differentiated adenocarcinoma) but not in three cell lines (MKN-1, MKN-28 and MKN-74; from well differentiated adenocarcinoma), suggesting that expression of the pS2 gene depends on the state of cell differentiation. These results suggest that pS2 is expressed in human gastric cancer cells in an estrogen-independent manner and is possibly associated with the malignant state of cells.
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PMID:Expression of the pS2 gene in human gastric cancer cells derived from poorly differentiated adenocarcinoma. 231 59

It has been suggested that endogenously formed N-nitroso compounds are involved in the aetiology of gastric cancer. In the model of gastric carcinogenesis postulated by Correa, gastric atrophy is an important early stage in the progression to carcinoma which results in the loss of stomach acidity, and colonization of the stomach by bacteria. As a consequence of the metabolic activity of these bacteria intragastric nitrite (a precursor to N-nitroso compounds) and possibly carcinogenic N-nitroso compounds become elevated, which may hasten the progression to carcinoma. Vitamin C has been shown to be an effective inhibitor of acid-catalysed N-nitroso compound formation, in vivo and in vitro, and this has been attributed to its relatively rapid reaction with nitrite in contrast to the slower rates of reaction of nitrite with secondary amines. However, N-nitroso compound formation in the achlorhydric stomach must proceed by mechanisms which operate at neutral pH values. One potential mechanism involves the enzymatic catalysis of N-nitrosation by a subpopulation of the bacteria colonizing the achlorhydric stomach which catalyse these reactions and in particular denitrifying organisms. In this study, we examined the effect of vitamin C on the formation of N-nitrosomorpholine from morpholine and nitrite when mediated by cells of an actively N-nitrosating denitrifying bacterium (Pseudomonas aeruginosa, BM1030) at neutral pH. Despite the fact that vitamin C ordinarily shows little reactivity towards nitrite at neutral pH it did prove to be a potent inhibitor of bacterial N-nitrosamine formation. This study provides some justification for the use of vitamin C as an inhibitor of endogenous N-nitrosation regardless of gastric pH.
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PMID:The inhibition of bacterially mediated N-nitrosation by vitamin C: relevance to the inhibition of endogenous N-nitrosation in the achlorhydric stomach. 249 12

In this study, 17 patients with advanced gastric cancer were randomized into 3 groups to investigate the changes of protein metabolism-and the nitrogen sparing effect of both hypo-and hypercaloric nutrition after radical gastrectomy. Group 1, as control (n = 6) receiving 14 +/- 1.2 kcal/kg/d with no protein; Group 2, as hypercaloric (n = 6) receiving 32 +/- 3.8 kcal/kg/d(by Harris Benedict Equation) and 1.23 g/kg/d of protein; Group 3, hypocaloric (n = 5) with less than 50% of calories and the same amount of protein as in Group 2. 15N-glycine was used to evaluate the protein synthesis and breakdown rates, and the nitrogen balance, nitrogen retention, plasma proteins (albumin, fibronectin), protein catabolic parameters such as nitrogen, creatinine, 3-MH excretion in the urine, and CPK in serum were evaluated. It was found that although in all three groups there was significant protein catabolism after surgery, there was significant reduction of negative nitrogen balance in Group 2 (-2.7 +/- 2.1 g/d) and Group 3 (-2.8 +/- 3.1 g/d) as compared with Group 1 (-9.6 +/- 1.73 g/d). Nitrogen retention rate was 75 +/- 4.5% in Group 3 and 78.6 +/- 3.9% in Group 2. Postoperative fibronectin concentration in Group 1 was also statistically different from Group 2 or Group 3. Protein synthesis was increased by 57.7% and 60.6%, and breakdown by 14.9% and 18.9% respectively in Group 2 and 3. It was concluded that hypocaloric nutrition was as effective as hypercaloric support in this situation.
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PMID:[Effect of hypocaloric nutritional support on protein metabolism in patients with gastric cancer after radical gastrectomy]. 251 72

Human whole saliva protects the oral environment in many different ways from invading pathogenic microorganisms. Human saliva is also capable of inactivating mutagenic and carcinogenic agents by various mechanisms. The peroxidation of these agents is likely to be one of the degrading reactions. However, under certain circumstances some potentially carcinogenic compounds, such as N-nitrosamines, may be generated in whole saliva or--even more likely--in the saliva-gastric juice mixture after swallowing. The formation of N-nitroso compounds requires relatively high intake of nitrate e.g. from vegetable juices. Nitrate is partly reduced to nitrite by oral bacterial enzymes. The nitrosation of various secondary amines is favoured by high salivary (or gastric) concentration of thiocyanate and by low pH. The endogenous generation of N-nitroso compounds may be causally related to the development of oral or gastric cancer.
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PMID:The biochemistry of nitrates, nitrites, nitrosamines and other potential carcinogens in human saliva. 309 50

Pre and postoperative metabolism of electrolytes and protein were studied in gastric cancer patients. Eight patients who underwent distal subtotal gastrectomy for gastric cancer, were treated with total parenteral nutrition (TPN) from the third day before surgery to the tenth day after surgery. Twelve patients who underwent total gastrectomy for gastric cancer were treated with enteral nutrition (EN, T-330, ED-AC) and TPN in the early postoperative phase. The results were as follows. 1) P which existed in intracellular space showed a decrease in the plasma level and a negative balance in the early postoperative phase. Thereafter, the plasma level of P ion increased and a positive balance was observed. 2) Ca showed a positive balance during the observation period. 3) The level of prealbumin and retinol-binding protein decreased to some extent after surgery, but came up to the preoperative level on the seventh postoperative day in enteral nutrition (T-330) after total gastrectomy. 4) Nitrogen balance was observed to show a positive balance on the seventh postoperative day. There was no statistical difference between the three groups. 5) There were significant relationships between the serum albumin level and the development of postoperative complications.
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PMID:[Pre- and postoperative nutritional management in gastric cancer patients]. 313 84

Nitrosation of dietary components has been combined with the 4-(para-nitrobenzyl)pyridine (NBP) colorimetric test for screening alkylating agents and with the Ames test for the detection of mutagenic activity. This allowed the investigation of short-lived nitrosation products of dietary components which generate electrophilic degradation products requiring no metabolic activation (natural amino acids and some derivatives, ureas, guanidines, primary alkyl and aryl amines). In a first system, precursor, nitrous acid and NBP were present simultaneously. All amino acids tested, except glutamic acid and glutamine, gave positive results. The reactivities spanned more than three orders of magnitude, with the aromatic amino acids and methionine the most active; two primary amines, tryptamine and histamine, were also strongly reactive. All guanidines tested, except the amino acid arginine, gave negative results. A second system consisted of two phases: NBP was added only after destruction of residual nitrite and adjustment of the pH to neutrality. This system was useful for the study of ureas, which are stable in acid but not in neutral media. The range of responses covered more than two orders of magnitude. Most amino acids and primary amines also gave positive results, but could be assessed only after analysing the kinetics of the competing reactions and choosing appropriate reaction times. In a third system, Salmonella typhimurium strain TA100 replaced NBP. Representatives of the class of amino acids, ureas, the primary amine tryptamine, and aniline became highly mutagenic upon nitrosation. Methylguanidine was only weakly mutagenic under the present assay conditions. The results indicate that further studies with unstable nitrosation products of dietary components are required to understand more thoroughly the role of endogenous nitrosation in gastric cancer.
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PMID:In-vitro assays to detect alkylating and mutagenic activities of dietary components nitrosated in situ. 367 75

It has been hypothesized that dietary nitrate and nitrite are converted in the stomach to nitrous acid, which reacts with secondary amines and amides to form nitrosamines and nitrosamides, compounds frequently demonstrated to be carcinogenic in animals, and that vitamins C and E inhibit N-nitroso product formation by chemically reducing nitrous acid. This hypothesis and others were tested in a case-control study (controls were individually matched by age, sex and area of residence), utilizing a standardized, quantitative, dietary history questionnaire interview. Daily nutrient consumption values were calculated from interview responses, and continuous conditional logistic regression was used for the data analysis. Significant findings are as follows: (1) Average daily consumption of nitrite, chocolate and carbohydrate was associated with increasing trends in risk. (2) While citrus fruit intake appeared to be somewhat protective, any protective effect of vitamin C intake was less apparent, and of vitamin E, not at all apparent. (3) Consumption of dietary fibre was negatively associated with gastric cancer risk. These findings appear to implicate a number of dietary components, including nitrite consumption, in the genesis of gastric cancer in humans.
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PMID:Consumption of precursors of N-nitroso compounds and human gastric cancer. 367 29

Young adult male Sprague-Dawley rats were given 30 mumol/kg body weight [14C]methylamine hydrochloride and 700 mumol/kg body weight sodium nitrite by oral gavage. DNA isolated from the stomach and from the first 15 cm of the small intestine was methylated, containing 7-methylguanine (7mG) at a level of one 7mG molecule per 5 X 10(6) and 1 X 10(7) nucleotides, respectively. No 7mG was found in the liver at a limit of detection of one 7mG molecule per 2 X 10(8) nucleotides. In a second experiment, the excised stomachs were incubated with deoxyribonuclease before the isolation of the DNA in order to degrade DNA in the lumen and in the uppermost lining cells. This treatment resulted in a 30% decrease in the yield of DNA and a 90% reduction in the level of 7mG formation. The results show that nitrosation of a primary alkylamine yields a precursor of an alkylating agent which has a long enough lifetime to diffuse towards and react with intracellular DNA. A correlation of DNA methylation in the stomach with the corresponding tumor formation by the methylating carcinogen N-methyl-N'-nitro-N-nitroso-guanidine was used to estimate the role of DNA damage resulting from endogenous nitrosation of dietary methylamine in man. It was concluded that the risk resulting from this single amine must be negligible but that a similar evaluation of other primary amines is required before the over-all role of primary amine nitrosation in the etiology of human gastric cancer can be assessed.
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PMID:Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite. 649 25

The levels of the common secondary amines in various squid, in octopus and in 17 other seafoods were determined by HPLC. Ammonia and dimethylamine were found in all of the seafoods tested and some of them also contained methylamine and/or ethylamine. Particularly high levels of dimethylamine (946-2043 ppm) and methylamine (38-255 ppm) were detected in various species of squid and in the octopus. Reaction of nitrite in acidic medium with aqueous extract of squid yielded appreciable amounts of N-nitrosodimethylamine. The optimum pH for this reaction was around 2.4. Dimethylamine in dried squid tissues was readily extracted with water or 1% sodium carbonate solution. Heat treatment of dried squid at 200 degrees C was found to increase its amine content dramatically. It appeared that pyrolytic decarboxylation of some amino acids might cause this increase. Squid is a popular seafood in Japan and other oriental countries. The high incidence of stomach cancer in Japan and China is thought by epidemiologists to be associated with traditional Japanese and Chinese diets. Our present finding that squid and other seafoods contain unusually high levels of dimethylamine and other amines adds to the evidence that dietary factors may have an important role in the aetiology of stomach cancer and other gastro-intestinal tumours.
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PMID:High concentrations of dimethylamine and methylamine in squid and octopus and their implications in tumour aetiology. 668 76


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