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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To test the hypothesis that excessive intake of sodium chloride is a factor in gastric carcinogenesis, urinary excretion of sodium and creatinine was measured in Colombian subjects. Age, sex, weight, and height regression slopes for creatinine excretion were more similar in Colombia than in other countries. Sodium/creatinine (S/C) ratios correlated with 24-h urinary excretion of sodium revealed higher sodium excretion in populations with higher gastric cancer rates. The S/C ratios were not affected by circadial rhythms, making it possible to use single urine samples to investigate interpopulation differences in sodium excretion.
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PMID:Sodium intake and gastric cancer. 397 84

Fasting human gastric juice was treated in vitro, at pH 2-7 and 37 degrees C for 2 h, with 5-100 microM sodium nitrite. Under these conditions (which simulated those occurring in vivo in normal or hypochlorhydric individuals), the formation of total N-nitroso compounds had the following characteristics: (i) it increased greatly at pH less than 3; (ii) it showed first-order dependence on nitrite concentration; (iii) it was faster at pH 7 than at pH 5. These observations are compatible with the N-nitroso compounds formed by the interaction of nitrite with gastric juice being N-nitrosamides or related compounds. Furthermore, based on the results of this study, it is suggested that in order for hypochlorhydria to give rise to increased formation of N-nitroso compounds in the stomach, it would be necessary for it to be accompanied by a greater than 5- to 10-fold increase in gastric nitrite concentration relative to that found in the normal population, a condition which is not necessarily fulfilled in all hypochlorhydric individuals or populations. The implications of this conclusion for the assessment of the role on gastric N-nitroso compounds in the etiology of gastric cancer are discussed.
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PMID:Studies in gastric carcinogenesis. III. The kinetics of nitrosation of gastric-juice components in vitro and their implications for the in vivo formation of N-nitroso compounds in normal and in hypochlorhydric populations. 401 84

Various lines of evidence indicate that aldosterone and prostaglandins may play physiological roles in protecting the gastric mucosa. This would suggest that low-sodium, high-potassium diets, and supplementation with essential fatty acids that are efficient prostaglandin precursors (as in evening primrose oil), may have value in the prevention and treatment of gastric ulcer and gastritis. A low-sodium, high-potassium diet may also reduce the risk of gastric cancer.
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PMID:Nutritional modulation of mineralocorticoid and prostaglandin production: potential role in prevention and treatment of gastric pathology. 635 85

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

Nitrosomethylurea (NMU) formation was measured radioactively in the stomach contents of rats fed 3H-methylurea and sodium nitrite, mostly in semi-synthetic diets. When methylurea and sodium nitrite were added to various diets, the NMU concentration, averaged over 1-4 hours after the food was presented, was 4.6 micrograms/kg stomach contents for low-protein, 2.7 for control semi-synthetic, 2.4 for high-fat, 1.26 for bran, 1.24 for high-protein and 0.54 for the commercial diet. With the low-protein diet, the amount of NMU after 1 hour was 36.6 micrograms, corresponding to 5.3% conversion of methylurea. The decrease in yield as protein content increased was attributed to buffering action and competition for nitrite by the protein, as well as to the effects of the latter on consistency. It may also be correlated with the observation that human gastric cancer is associated with high-starch low-protein diets. Nitrite in diet was more effective in producing NMU than the same nitrite concentration in drinking water, except with sodium nitrite concentrations less than or equal to 0.5 g/kg vehicle, where the position was reversed. Sodium ascorbate added to a semi-synthetic diet at a level of 2.9 g/kg inhibited NMU production by 50%.
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PMID:Dietary and other factors affecting nitrosomethylurea (NMU) formation in the rat stomach. 722 57

Chemical synthesis of N-nitrosamide and influences on it by bacteria and fungi isolated from human gastric juice were studied with trace analysis method to explore the pathway of its endogenous formation. Results showed in synthesis of N-methyl-N-nitrosourea (MNU) with precursors of methylurea (0.42 mmol/L) and sodium nitrite (25 mmol/L) in a condition simulating human stomach, pH of the reaction system played an important role in the synthesis, the amount of synthetic chemical maximized at a pH of 1-3 and almost no synthesis was found at pH of 5-7. A study on the ability to synthesize MNU catalyzed by bacteria isolated from the patients with stomach cancer living in a high-risk area showed its synthesis could be accelerated by Pseudomonas aeruginosa at pH of 6-7 with its catalyzing activity existed in heat liable component of living bacteria. This is the first report showing microorganisms to catalyze the formation of N-nitrosamide from its precursors.
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PMID:[Preliminary studies on microbe-mediated N-nitrosamide synthesis]. 758 63

The purpose of this study was to investigate the peculiarities of hormonal regulation of adenylate cyclase (AC) of blood lymphocytes in colorectal cancer patients and to compare these peculiarities with hormone sensitivity of AC of colorectal tumors and normal colonic mucosa. Basal and stimulated lymphocyte AC activity was studied in 51 healthy persons and 52 cancer patients (14 with colon cancer, 21 with rectal cancer and 17 with stomach cancer) aged 20-75 years. In 31 of 35 patients with colorectal cancer the AC activity was studied simultaneously in lymphocytes, tumor tissue and normal colonic mucosa. To evaluate basal and stimulated AC activity the measurement of c-AMP (Amersham kits) formed in the presence of ATP regenerating system was used. Basal and by VIP, pentagastrin and sodium fluoride stimulated AC activity in lymphocytes of gastrointestinal cancer patients was lower than in lymphocytes of healthy subjects of similar age. Stage dependence of the parameters under study was not found. There was a tendency for higher basal and stimulated lymphocyte AC activity in colon cancer patients as compared to stomach and rectal cancer patients. In colorectal cancer patients the peculiarities of lymphocyte AC reactions to stimulation were closer to those in tumor tissue but not to those in normal colonic mucosa. The reaction of lymphocyte AC to VIP and glucagon coincided more frequently with tumor AC reactions to the same hormones in case of hormone nonsensitive tumors. Thus, basal and stimulated lymphocyte AC activity in colorectal cancer patients was modified to some degree by tumor factors. Lymphocyte AC reactions to VIP and glucagon may be considered as indirect markers of hormone sensitivity of colonic tumors. Moreover, the probability of discovery of hormone nonsensitive tumors by this way is more reliable than hormone sensitive ones.
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PMID:Hormonal regulation of adenylate cyclase activity in circulating lymphocytes and its interrelationship with hormone sensitivity of tumor tissue in colorectal cancer patients. 761 78

Porfimer sodium (Photofrin II) is a photosensitizer which distributes selectively to tumor tissues, and causes tumor cell death by combination with light irradiation. Photodynamic therapy (PDT) by combination of porfimer sodium and laser was developed as a new cancer therapy. Tumor selectivity of porfimer sodium are based on the following reasons; 1) high affinity for lipoprotein, especially, low density lipoprotein (LDL), 2) elevation of LDL receptor activity in cancer tissue, and 3) lack or imcompleteness of lymphatic system in cancer tissue. Porfimer sodium is activated by laser irradiation at 630 nm, which can reacts with tissue oxygen to produce highly reactive excited siglet oxygen (1O2). This highly reactive molecule is subsequently capable of killing tumor cells through oxidation of cellular component like mitochondrial enzymes. In addition, this highly reactive intermediate causes destruction of the tumor capillaries, which accelerates tumor cell death. The growth suppression or lethal damage to tumor cells by PDT of porfimer sodium and excimer dye laser were observed in experimental tumor models. In human clinical trials, the rates of complete response (CR) for roentgenographically occult lung cancer, stage I lung cancer, superficial esophageal cancer, superficial gastric cancer and carcinoma in situ or dysplasia of the cervix were 84.8%, 50.0%, 90.0%, 87.5% and 94.4%, respectively. The major side effects were cutaneous symptoms e.g. photosensitivity, pigmentation, increasing GOT, GPT but these symptoms were not severe. PDT using porfimer sodium and excimer dye laser must be clinically useful for the treatment of inoperable early cancer or conservation of organ functions.
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PMID:[Porfimer sodium (Photofrin-II)]. 766 80

The study was made of the effect of apple, grapefruit, orange and beet juices on in vitro formation of N-nitrosodimethylamine (NDMA) from sodium nitrite and amidopirin in human gastric juice (GJ). Experimental samples of GJ from outpatients attending the outpatient department of the AMS Cancer Research Center were used. The patients had various forms of gastritis and gastric cancer. It was found that fruit and beet juices may inhibit or enhance NDMA formation depending on the GJ composition, pH in particular. In acid medium (pH-1.3-3.4) there was a trend to inhibition of NDMA synthesis, while in neutral and alkaline (pH = 7.4-8.5) medium NDMA synthesis is activated. Practical implications of the findings are discussed.
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PMID:[Effect of fruit and vegetable juices on the changes in the production of carcinogenic N-nitroso compounds in human gastric juice]. 807 94


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