摘要:

AbstractWe examined the effect of dietary fat and colon tumorigenesis on the morphology and function of the rat mesenteric lymph node (MLN) and spleen at two stages of tumor development. Male Sprague‐Dawley rats were fed semipurified diets of varying fat content (5% mixed fat, 24% beef fat, 24% corn oil, or 24% Crisco) and treated for five weeks with either the colon carcinogen 1,2‐dimethylhydrazine (DMH) or the vehicle (saline). Animals consuming high‐fat diets had an increased incidence of splenic follicular and germinal center hyperplasia. Carcinogen treatment had no significant effect on the histological morphology of the spleen. MLN morphology was not dramatically affected by either diet or DMH treatment. At this time period, the splenic lymphocyte transformation response induced by concanavalin A (Con A), phytohemagglutinin, or pokeweed mitogen was significantly depressed in the group fed 24% corn oil (vehicle‐treated) and in the DMH‐treated groups fed 5 %fat compared with the vehicle‐treated group fed 5% fat. In contrast, the MLN transformation response was elevated in the group fed 24% Crisco. DMH treatment did not significantly influence the MLN response. Four months after carcinogen or vehicle treatment, at the point of colon tumor development, no statistically significant differences were seen in the splenic or MLN blastogenic responses of DMH‐or saline‐treated animals. Splenic natural killer cell cytotoxic activity wasalso not significantly affected by dietary fat, carcinogen treatment, or tumor development.

ISSN:0163-5581    

DOI:10.1080/01635588609513879

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractThe effects of feeding mice raw or heated soy flours or casein in the presence and absence of injected azaserine were investigated over a peiod of 18 months. Although the feeding of raw soy flour (compared with heated soy flour or casein) caused a significant inhibition of growth and an enlargement of the pancreas, there was no macroscopic evidence of pancreatic nodules in any of the six experimental groups. Microscopic examination of the pancreas revealed a somewhat higher (not significant) incidence of atypical acinar cell nodules in all animals injected with azaserine, but this difference was little influenced by the diets themselves. We concluded that raw soy flour itself has no carcinogenic effect on the mouse pancreas and does not enhance the sensitivity of the mouse pancreas to azaserine. Thus, it cannot be assumed that the appearance of pancreatic nodules constitutes an obligatory sequela of pancreatic hypertrophy and/or hyperplasia in all species of animals.

ISSN:0163-5581    

DOI:10.1080/01635588609513880

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractThe effect of two levels and types of dietary fats on the susceptibility of colonic cells to the nuclear‐damaging effect of 1,2‐dimethylhydrazine dihydrochloride (DMH), 2‐amino‐3, 4‐dimethylimidazo(4,5‐f)quinoline (MelQ), and gamma‐radiation was investigated. Corn oil and beef tallow were added to the semisynthetic diet at 5% and 20% levels (weight/weight). A diet‐related effect was not evident until after two weeks of feeding. Animals (C57BL/6J female mice) that were given the 20% corn oil or beef tallow diets had significantly (p<0.05) more nuclear aberrations in their colons 24 hours following treatment with DMH (5 mg or 10 mg/kg body wt or MelQ (100 mg/kg body weight) than did those given low‐fat diets (5% corn oil or beef tallow). The nuclear‐damaging effect of gamma radiation was unaffected by dietary treatments. A high‐fat diet had the most pronounced effect on DMH‐treated animals, and maximum nuclear aberrations were observed 24 hours following the treatment. Thus, we concluded that increased levels of dietary fats elevate the toxicity of DMH and MelQ to colonic epithelial cells.

ISSN:0163-5581    

DOI:10.1080/01635588609513881

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractVitamin E was found to have a stimulatory effect on the growth in culture of an epidermoid carcinoma cell line derived from chemically induced tumors of hamster buccal pouch. This effect was found to be dose related, with a maximum stimulatory effect at 10μM. At a concentration of 100μM, there was an inhibitory effect on both cell turnover and colony formation.

ISSN:0163-5581    

DOI:10.1080/01635588609513882

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractThe relationship between an index of dietary vitamin A and cancer risk at 25 sites was assessed in retrospective case‐control studies. Common control groups for males and females were used in all analyses. Relative risk estimates were derived from multiple logistic regression analyses that controlled for age, alcohol consumption, and smoking exposure. We found that among males, dietary vitamin A is associated with lower risk for cancers of the tongue, floor and other mouth, pharynx, larynx, esophagus, and lung but higher risk for Hodgkin's disease and leukemia. Among females, we found that dietary vitamin A had less effect on risk generally but was associated with lower risk for bladder cancer. These findings are consistent with previous research that showed dietary vitamin A to be associated with decreased risk of squamous epithelial cancers. The association of dietary vitamin A and increased risk of Hodgkin's disease and leukemia among males in addition to the disparity in effect of dietary vitamin A on risk between males and females are areas worthy of further research.

ISSN:0163-5581    

DOI:10.1080/01635588609513883

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractThe effects were determined of dietary fat and selenium (Se) levels on prostaglandin (PG) production in rat blood, kidney, and colon mucosa. For 30 weeks, male Wistar‐derived MRC rats were prefed diets containing low (6 g/367 kcal) or high (20 g/367 kcal) levels of fat with one of three Se supplements from sodium selenite: 0.0, 0.1, or 2.0 ppm Se. PG production was stopped by adding aspirin immediately following removal of the blood, kidney, and colon samples. Separate samples were allowed to incubate 10 or 60 minutes before blockage of PG production for determination ofex vivoPG production. Prostaglandin E2(PGE2), thromboxane B2, and 6‐keto‐prostaglandin F1α(6‐keto‐PGF1α) were measured by radioimmunoassay following separation on silicic acid columns. Basal levels of the three PGs were not influenced by diet. PGE2production in the colon was highest in the group fed the high‐fat diet that contained 2.0 ppm Se at 10 and 60 minutes, but PGE2production in the blood and kidney were not altered by diet. Thromboxane B2production in the rats’blood was higher in those prefed high‐fat diets, but it was not influenced by dietary Se. Production of 6‐keto‐PGF1αin the blood and thromboxane B2and 6‐keto‐PGF1αproduction by the kidney and colonic mucosa were not influenced by either dietary fat or Se.

ISSN:0163-5581    

DOI:10.1080/01635588609513884

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractFor 30 days, male weanling rats were fed a semipurified, fiber‐free diet or a diet that contained 5, 15, or 30% (wt/wt) wheat bran. The activities of four cecal microbial enzymes were determined. Wheat bran significantly increased the wet weight content of the cecum and total bacterial count per cecum at the intermediate‐and high‐treatment levels, but it had no effect on bacterial concentration per gram wet weight of cecal contents. Totalβ‐glucosidase andβ‐glucuronidase activities per cecum were generally increased. Wheat bran decreased total nitrate reductase activity, but there was no change in total nitroreductase activity. Wheat bran significantly decreased enzyme activities for nitro‐and nitrate reduction per gram of cecal contents but increasedβ‐glucosidase activity. The activities of the enzymes per 1011bacteria followed a similar pattern to that noted per gram of cecal contents. Such fiber‐dependent changes in enzyme activity may alter the steady‐state concentration of toxic and genotoxic chemicals in the lumen of the hindgut.

ISSN:0163-5581    

DOI:10.1080/01635588609513885

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractSodium saccharin (NaSacc) has been shown to be a protease inhibitor and to induce an increase in urinary indican, which is a product that is dependent on microbial metabolism of tryp‐tophan. These findings suggest that urinary indican might provide a noninvasive marker of increased pancreatic acinar cell size associated with plant trypsin inhibitor ingestion. The results demonstrate the 7.5% of dietary NaSacc, which increases urinary indican, also increases relative pancreas mass (g/kg body weight), and that these effects are not induced by intravenous infusion of NaSacc. Dietary soybean trypsin inhibitor in the dose range of 17–713 mg/100 g diet was associated with parallel dose‐dependent increases in urinary indican and pancreatic acinar cell size (assessed histologically). These findings suggest that measurement of relative urinary indican excretion (μg/g diet ingested) can provide a noninvasive marker of increased pancreatic acinar cell size in rats that ingest compounds which inhibit digestive proteases.

ISSN:0163-5581    

DOI:10.1080/01635588609513886

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

摘要:

AbstractThein vitrobinding of estrone, estradiol‐17β, estriol, testosterone, dihydrotestosterone, and estrone‐3‐glucuronide by wheat, oat, and corn brans, oat hulls, cellulose, lignin, and chole‐styramine resin wasmeasured. The extent of steroid sequestration was characteristic and reproducible for each hormone. Cholestyramine bound an average of 90% of all the steroids tested, whereas cellulose bound the least (12%). Of the other substances tested, each bound the following percentage of unconjugated hormones: lignin, 87% wheat and oat brans, 45 % each; corn bran 44% and oat hulls, 32%. The conjugated steroid was less likely to bind than the unconjugated steroids. Lignin appeared to be an important component in the interaction with steroid hormones. The results support the hydrophobic nature of adsorption and suggest that the components of fiber in diet should be considered separately when evaluatingin vivometabolic effects.

ISSN:0163-5581    

DOI:10.1080/01635588609513887

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor

ISSN:0163-5581    

DOI:10.1080/01635588609513878

出版商:Taylor&Francis Group    

年代:1986

数据来源: Taylor