摘要:

AbstractMammalian tissue DNA has recently been found, via32P postlabeling, to contain complex profiles of age‐dependent bulky carcinogen adductlike covalent modifications, which have been termed I‐compounds, referring to their apparent indigenous origin without exposure to exogenous carcinogens. I‐compound patterns are highly species, sex, tissue, and diet specific. As shown here, the presence of certain plant ingredients in diet, i.e., ground oats and alfalfa meal, significantly contributed to the formation of these DNA derivatives.Six groups of weanling female Sprague‐Dawley rats were fed one of the following diets for three months: a natural ingredient diet containing neither oats nor alfalfa (Wayne MRH 22/5 Rodent Blox), Wayne diet supplemented with oats or alfalfa or both, a purified semisynthetic diet (AIN‐76A), and AIN diet supplemented with oats. The natural ingredient diet produced more complex patterns and higher levels of I‐compounds than purified diet in both liver and kidney DNA. Supplementation of either diet with oats elicited the formation of four additional oats‐specific I‐compounds in liver DNA. Oats and alfalfa, individually and in combination, tended to significantly raise nonpolar and diminish polar I‐compound levels.To determine whether the oats‐related extra spots were derived from mycotoxin contamination, two groups of rats were fed either Wayne diet or Wayne diet containing zearalenone (0.05 mg/kg) for three weeks. Zearalenone significantly increased the uterine weight but did not induce any DNA adduct formation. These findings establish a novel link between specific natural food ingredients and carcinogen adductlike DNA derivatives and may provide a model to investigate events occurring at the juncture of nutrition, metabolism, gene expression, aging, and cancer.

ISSN:0163-5581    

DOI:10.1080/01635589209514189

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractC57BL/Ka mice were fed diets rich inω3 orω6 polyunsaturated fatty acids and inoculated with the thymic lymphoma‐inducing retrovirus RadLV. Mice receiving theω3 diet died significantly sooner than those receiving theω6 diet. Of the three known mechanisms by which fatty acids can exert antiviral activity, namely, modification of membrane fluidity, modulation of immune response, and synthesis of metabolites with antiviral activity, the first two can be eliminated in the model under study. It is therefore concluded that differences in survival are due to fatty acid metabolites with distinct antiviral activities.

ISSN:0163-5581    

DOI:10.1080/01635589209514190

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractPromotion of chemically induced esophageal cancer by ethanol may include the generation of highly reactive free radicals and thus may be preventable by the antioxidant vitamin E. In the present study, female C57BL/6 mice received N‐nitrosomethylbenzylamine (NMBzA, 0.2 mg/kg ig) three times a week for three weeks. After this esophageal carcinogenic treatment, mice were fed a nutritionally adequate liquid diet with 30% of the calories supplied by ethanol or an isocaloric carbohydrate with or without supplementalα‐tocopherol (142 mg/kg diet). As a marker of in vivo lipid peroxidation, exhaled ethane was collected and measured 24 hours“before”; the mice were killed after 20 weeks of dietary treatment. Hepatic malondial‐dehyde, lipid fluorescence, and conjugated dienes were determined as markers of products of lipid peroxidation and serum aminotransferases as indexes of liver toxicity. Hepatic liver concentrations of vitamins A and E and the size and frequency of esophageal tumors were also assessed. Ethanol consumption after NMBzA administration significantly increased (p<0.05) the size and frequency of esophageal tumors. These ethanol‐promoted effects were accompanied by increases in indexes of in vivo and accumulated products of lipid peroxidation. Similarly treated animals that received supplemental dietary vitamin E showed significant reductions (p<0.05) in mean tumor size and frequency of tumors as well as a decrease in the indexes of hepatic lipid peroxidation. The results suggest that promotion of NMBzA‐induced esophageal tumors by ethanol may in part result from increased lipid peroxidation and that vitamin E reduces carcinogenicity of NMBzA or ethanol promoter effects by inhibiting lipid peroxidation.

ISSN:0163-5581    

DOI:10.1080/01635589209514191

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractReports that protein kinase C is inhibited by sphingosine and other long‐chain amines and the suggestion that promotion of mammary carcinogenesis by dietary fat is mediated by protein kinase C prompted us to investigate the effects of a long‐chain amine, 1‐octa‐decylamine, on mammary carcinogenesis induced by 7,12‐dimethylbenz[a]anthracene in rats fed a high‐fat diet. Rats fed the amine sulfate at a level of 0.01% in a semipurified diet containing 20% corn oil developed more tumors than those fed the high‐fat diet alone, although body weight gain was inhibited slightly. Rats fed the amine sulfate at 0.1% of the diet developed very few tumors compared with those fed either the high‐fat diet or a low‐fat diet containing 5% corn oil. At the higher level, the C18 amine also caused a marked inhibition of body weight gain.

ISSN:0163-5581    

DOI:10.1080/01635589209514192

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractReactive oxygen metabolites (ROM) have been postulated to contribute to the development of various carcinomas, including colon cancer. Indeed, the effects of ROM scavengers are being tested for chemoprevention of adenocarcinoma of the colon. However, there has been no evidence to indicate that high levels of ROM are indeed present in cancerous tissue. In this study, we used a chemiluminescence probe to estimate ROM levels in cancerous and neighboring noncancerous colonic tissues from seven patients with colon cancer. Cancerous tissues contained significantly (p<0.05) more luminol‐enhanced chemiluminescence (4,808±2,282 counts/min/mg protein) than neighboring noncancerous tissues (2,175±1,111). The addition of an ROM scavenger, catalase (2, 4, and 8μg/ml), to the tissue suspension inhibited chemiluminescence produced by both noncancerous (—74%,—85%, and—71%) and cancerous (—11%,—61%, and—53 %) tissues. This study shows that colonic cancerous tissue contains high levels of ROM, which may play an important role in the pathogenesis of colon cancer.

ISSN:0163-5581    

DOI:10.1080/01635589209514193

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractThe modifying effect of a dietary fiber, Fibeta (beet fiber), on experimentally induced colorectal cancer was studied in Wistar rats. The rats were fed a powdered semisynthetic casein‐based diet in which the carbohydrate pool was substituted with Fibeta as the sole source of fiber. Dimethylhydrazine dihydrochloride (DMH‐2HCI) was used as initiator in a dose of 20 mg/kg body wt and given by gavage once a week for 10 weeks. Throughout the experiment the rats were offered the diets with different levels of fiber in a preinitiation period of 8 weeks, during the initiation, or in a 30‐week postinitiation period. The study was terminated after one year.A protective effect of the fiber was not found at any stage of the colorectal carcinogenic process. Even though differences (not statistically significant) in tumor incidences were seen, these did not reflect any effect of the high or low fiber intake during the study.Analysis for volatile fatty acids in cecal content showed that continuous feeding with a fiber‐rich diet resulted in significant increase in most of the volatile fatty acids. The relative change was highest for butyric acid. These findings do not support the hypothesis that butyric acid has a protective effect on colorectal cancer. The tumor yield in the present study was low compared with that reported in the literature, and possible causes for this are discussed.

ISSN:0163-5581    

DOI:10.1080/01635589209514194

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractA case‐control study was conducted to examine the influence of dietary factors on the risk of developing lung cancer among women who have never smoked cigarettes. This study included 124 cases of histologically confirmed carcinoma of the lung and 263 community‐based controls. Dietary data were collected utilizing the reduced version of the National Cancer Institute (Block) food frequency questionnaire. The results of this analysis, adjusted for age, education, and total calories, indicated a strong protective effect associated with total vegetable consumption and intake of carotene. Individuals in the highest quartile of vegetable consumption experienced the greatest decreased risk with an odds ratio (OR) of 0.2, [confidence interval (CI) 0.1–0.5]. The effect of all vegetables combined was greater than that of green and yellow vegetables alone (highest quartile OR 0.4, CI 0.2–0.7). Similarly, the protective effect of total carotene (highest quartile OR 0.3, CI 0.1–0.6) was somewhat greater than that ofß‐carotene alone (highest quartile OR 0.4, CI 0.2–0.8). Retinol intake was not associated with a decreased risk of lung cancer in our population. There was an inverse association between lung cancer risk and vitamin C intake, which was not significant, although a statistically significant trend was noted.

ISSN:0163-5581    

DOI:10.1080/01635589209514195

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractThe relationship between the occurrence of breast cancer and dietary intake, in particular a high‐fat diet, has attracted much attention in recent years. In addition, the prognosis of breast cancer patients on the basis of dietary intake is also an interesting subject. The present study utilized breast cancer patients whose dietary intake was carefully assessed about one decade previously in a case‐control study to determine whether dietary intake was indeed related to the patients’prognosis. The study included 212 patients who underwent a surgical operation between 1975 and 1978. They were followed‐up until 1987, and a total of 47 breast cancer deaths were certified. The 5‐and 10‐year relative survival rates were 78.5% and 75.3%, respectively. The older patients tended to ingest smaller amounts of all nutrients, except animal fat from fish. Height was significantly correlated with total animal protein intake, whereas there was no significant correlation between body mass index and intake of any nutrient. Although the age‐adjusted mean values of the nutrient intakes, other than vegetable fat, decreased with advancing stage, the differences were statistically insignificant. The results of multivariate analyses, in which some confounding factors (e.g., clinical stage) were adjusted using a proportional hazards model, showed that all hazards ratios in each nutrient were close to unity, and no dose‐response relationship was seen. The present investigation did not provide any support for the hypothesis that a high‐fat diet is a survival determinant for breast cancer patients. It should be qualified, however, that these negative results were obtained from the study on Japanese women, who develop breast cancer at an earlier age and consume relatively small amounts of fat.

ISSN:0163-5581    

DOI:10.1080/01635589209514196

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractThe anticarcinogenic activities of regular (soil‐grown) garlic and selenium‐enriched garlic (cultivated in the greenhouse) were evaluated using the 7,12‐dimethylbenz[&]anthracene‐(DMBA) induced mammary tumor model in rats. In Experiment 1, milled regular garlic powder was added to the basal AIN‐76A diet at 20 g/kg. The results from different schedules of supplementation suggested that a continuous treatment, which started before DMBA and persisted for the entire duration of the study, was most effective in tumor suppression. In Experiment 2, selected allyl group‐containing sulfides that are normal constituents of garlic extract were given by gavage in three single doses immediately before DMBA. Several structurally related compounds were found to be protective during the initiation phase in the mammary cancer model. Although the present study was not designed specifically to elucidate the structure‐activity relationship with respect to sulfur chain length or alkyl versus alkenyl substitution, our data showed that diallyl disulfide was more active than diallyl sulfide or allyl methyl sulfide. In Experiment 3, the anticarcinogenic activity of selenium‐enriched garlic (containing 150 ppm Se dry weight from growth in a selenium‐fertilized medium) was compared with that of regular garlic as well as selenite. Animals given the selenium‐enriched garlic (final concentration 3 ppm Se in the diet) developed the fewest mammary tumors. Tissue selenium levels, however, were lower in these animals than in those fed the same amount of selenium from selenite. Our study demonstrated the feasibility of achieving cancer prevention with the use of a selenium‐rich food system. It also suggested that the incorporation of selenium into a plant that is a good source of sulfur compounds may enhance its potential attributes in cancer protection.

ISSN:0163-5581    

DOI:10.1080/01635589209514197

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor

摘要:

AbstractFour carotenoids, canthaxanthin,β‐carotene, 8'‐apo‐β‐carotenal, and 8'‐apo‐β‐carotene methylester were tested for their ability to suppress the mutagenicity of 1‐methyl‐3‐nitro‐1‐nitrosoguanidine and benzo[a]pyrene (BP) in Salmonella typhimurium tester strain TA 100. The anticarcinogenic efficacy of the four carotenoids was further assessed in the BP‐induced forestomach tumor model in female Swiss mice. The effect of dietary palm oil was also examined in BP‐induced neoplasia in the female Haffkine Swiss mouse strain. Canthaxanthin,ß‐carotene, 8'‐apo‐ß‐carotenal, and 8'‐apo‐ß‐carotene methylester showed a dose‐dependent decrease in the mutagenicity compared with 1‐methyl‐3‐nitro‐1‐nitrosoguanidine and BP in strain TA 100. In the BP‐induced forestomach tumor model, all four carotenoids showed a similar significant anticarcinogenic effect. Dietary administration of palm oil showed a dose‐dependent antitumor activity in the animals. Our results show that the intrinsic antimutagenic and anticarcinogenic properties of the carotenoids are not significantly influenced by their conversion to vitamin A.

ISSN:0163-5581    

DOI:10.1080/01635589209514198

出版商:Taylor&Francis Group    

年代:1992

数据来源: Taylor