ISSN:0163-5581    

DOI:10.1080/01635588509513800

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractThe chemopreventive effects ofβ‐carotene and 13‐cis‐retinoic acid (RA) on chemically induced salivary gland tumors were studied in rats. Young male Sprague‐Dawley rats were injected in one of the submandibular salivary glands with 1 mg of dimethylbenzanthracene (DMBA) dissolved in olive oil. The contralateral gland was injected with the vehicle alone. Rats were divided into four groups and were fed ad libitum a semisynthetic diet supplemented with 0 or 100 mgβ‐carotene/kg diet, or 20 or 100 mg RA/kg diet. Rats were killed at 22 weeks after the DMBA treatment, and tumors were examined histologically. Tumors were generally found to be squamous cell carcinomas or poorly differentiated neoplasms resembling squamous cell carcinomas. The tumor incidence was slightly lower in rats fed the diet supplemented withβ‐carotene. RA had no appreciable effect on tumor incidence. A high activity ofγ‐glutamyl transpeptidase was histochemically demonstrated in the tumors. There were some mortalities in theβ‐carotene and RA supplemented groups, especially in the group fed high levels of RA. This mortality appeared to be related to vitamin K becoming somewhat limited.

ISSN:0163-5581    

DOI:10.1080/01635588509513801

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractAlthough experimental studies in animals show that selenium may prevent cancer, case‐control studies of internal human cancers have been difficult to interpret because neoplastic tissue sequesters selenium. We therefore conducted a case‐control study to examine the association between plasma selenium level and skin cancer, a neoplasm with minimal tumor mass at the time of diagnosis. The mean selenium level among patients with either basal cell epithelioma (N=142), squamous cell carcinoma (N=48), or both (N=50) was 0.141μg/g. This was significantly lower than the mean plasma selenium level of the 103 control subjects, which was 0.155μg/g. The noncancer control groups were drawn from current clinic patients and past clinic patients. The logistic estimate of the odds ratio for the lowest versus the highest decile of selenium for all cases combined versus the group of current patient controls was 4.39; for all cases combined versus the past patient controls, the logistic estimate of the odds ratio was 5.81.

ISSN:0163-5581    

DOI:10.1080/01635588509513802

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractFemale Sprague‐Dawley rats were given 7,12‐dimethylbenz(a)anthracene at 50 days of age to induce mammary tumors, and beginning one week later were fed a high‐fat, semipurified diet containing 20% sunflowerseed oil to promote tumor development. After another 7 weeks, when one third of the rats had palpable mammary tumors, the rats were randomly assigned to five groups of 31 animals each, with the same number of tumor‐bearers in each group. One group was continued on the high‐fat diet, another was given a fat‐free diet, and the three remaining groups were fed diets containing 10% lard, butter, or coconut oil, respectively. During the next 29 weeks, rats fed the diets containing 0% or 10% fat developed significantly fewer tumors than those continued on the 20% fat diet. The diets containing 10% fat suppressed tumorigenesis at least as effectively as the fat‐free diet. Rats fed the 10% butter and 10% lard diets had growth rates comparable to those fed the 20% sunflowerseed‐oil diet throughout, and evidence of essential fatty acid deficiency was seen only in rats on the fat‐free diet. These results provide additional evidence that high‐fat diets promote development of mammary cancer and suggest that reducing the level of dietary fat might help to prevent the development and recurrence of breast cancer in humans.

ISSN:0163-5581    

DOI:10.1080/01635588509513803

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractA branched chain amino acid (BCAA) solution was infused for 2 weeks following major hepatic resection in patients with malignant tumors of the liver. The infusion caused a significant reduction in plasma concentrations of phenylalanine, tyrosine, methionine, and ammonia as compared with the control patients. The BCAA infusion also prevented a marked fall in the molar ratio of valine, leucine, and isoleucine to phenylalanine and tyrosine. No untoward effects of the treatment were found. Although further studies are necessary to determine an ideal dose of BCAAs from the viewpoint of nitrogen balance, the BCAA solution seems to be a useful nutri‐tional element after major hepatic resection if given with hypertonic glucose.

ISSN:0163-5581    

DOI:10.1080/01635588509513804

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractWartime changes in flour milling have been estimated to have more than doubled the intake of cereal fiber in England and Wales, Ireland, and Switzerland for periods of at least 6 years. These circumstances were used to test the hypothesis that cereal fiber inhibits colon carcinogenesis.Age‐standardized rates for deaths attributed to bowel cancer were plotted from 1931 to the mid‐1970s for England and Wales, Ireland, Switzerland, New Zealand, the US, and Australia. The ratio of the mortality rate observed 11 to 15 years after the change in extraction rates to that predicted from the prewar trend correlated with the increase in estimated cereal fiber consumption. The slope of the regression line suggested that any protective effect from cereal fiber was more modest than that inferred from other studies. The disparity between studies would be less if cereal fiber inhibited more than one stage of the process of carcinogenesis. Trends in six other countries with insufficient data for quantitative analysis were generally consistent (with the exception of those for Norway). The limitations of historical cause‐of‐death registrations as measures of cancer onset rates and the multiplicity of other changes during wartime require that our results be interpreted with caution.

ISSN:0163-5581    

DOI:10.1080/01635588509513805

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractA case‐control study was undertaken to determine the dietary intake of vitamin A in women having abnormal uterocervical cytology. The study groups (87 cases and 82 controls) were drawn from a population of women who received a screening Pap test in the ambulatory health care section of a large municipal hospital center. A subset of cases (with abnormal cytology) were matched to controls for age, ethnicity, socioeconomic status, and parity. Nutrient intake and retinol binding protein concentrations were determined; epidemiological data were also obtained.It was found that the subset of cases with severe dysplasia or carcinoma in situ (CIS) were more likely to have a total dietary vitamin A intake below the pooled median (3,450 IU) and/or aβ‐carotene intake below the pooled median (2,072 IU) than were normal controls (p<0.05 andp<0.025, respectively). Odds ratios revealed approximately a 3‐fold greater risk for severe dysplasia or CIS in women with lowered vitamin A orβ‐carotene intake. In addition, retinol binding protein was either absent or undetectable in 78.8% of the dysplastic tissue samples, versus 23.5% of the normal tissue samples (p<0.005).

ISSN:0163-5581    

DOI:10.1080/01635588509513806

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

摘要:

AbstractInitiation of chemical carcinogenesis involves the intracellular formation of a highly reactive electrophile that can attack many chemical nucleophiles in the cell, including DNA, a process that seems to be the central mechanism of initiation. Competing chemical nucleophiles in the cell, such as endogenous glutathione, can act as protecting or blocking agents against the attack on DNA. There are chemical substances in our food supply that may act as anticarcinogens or antimutagens by blocking or trapping ultimate‐carcinogen electrophiles in a nucleophilic chemical reaction, to form innocuous products. A continuous input of these substances could serve as an additional buffer against DNA damage, supplementing the natural systems qualitatively and quantitatively. Certain plant phenolics can be effective inhibitors of chemical mutagens and/or carcinogens. Certain tetrapyrroles and por‐phyrins, both plant and animal, can also act as blocking agents. Both plant phenolics and porphyrins are primarily active against aromatic carcinogens. They are unlikely to be effective as blocking agents against nonaromatic carcinogens, or those with no aromatic groups in close proximity to the ultimate‐carcinogen electrophilic group.

ISSN:0163-5581    

DOI:10.1080/01635588509513807

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor

ISSN:0163-5581    

DOI:10.1080/01635588509513799

出版商:Taylor&Francis Group    

年代:1985

数据来源: Taylor