摘要:

AbstractMicronutrients, such asβ‐carotene and vitamins A and ?, are potential chemopreventive agents; however, their concentrations in human target tissues are largely unknown. Because these micro‐nutrients may exert their action at the site of target tissues, the tissue concentrations of the micronutrients need to be determined. In this cross‐sectional study, we have measured the concentrations of seven carotenoids, two retinoids, and two tocopherols in paired plasma, buccal mucosal cells (BMC), and skin samples from 96 healthy subjects (ages 26–82 yrs). The plasma‐tissue, as well as the diet‐plasma and diet‐tissue relationships of the micronutrients, and the impact of various potential confounders on the micronutrient concentrations were evaluated. The micro‐nutrient concentrations of plasma and BMC used in the evaluation were the average of three measurements over a one‐month period. Our data indicated that 1) the correlations between the plasma and BMC (Spearman r = 0.40–0.91, p<0.05) and the plasma and skin (r = 0.24–0.75, p<0.05) concentrations of most micronutrients were significant in all subjects, suggesting that the status of these micronutrients in the BMC and skin may be estimated from their plasma concentrations; 2) the correlations between the diet and plasma/tissue concentrations of the micronutrients were generally not as strong as the plasma‐tissue relationships; the diet‐plasma and diet‐tissue relationships of the carotenoids were particularly poor in the smokers; 3) the plasma and tissue concentrations of most micronutrients were lower in smokers than in nonsmokers and higher in vitamin supplement users than in nonsupplement users; the differences remained significant after adjustment for age, gender, and diet intake estimates; 4) among the seven carotenoids examined, lycopene was unique, because its concentration was not lower in smokers or higher in supplement users but was inversely associated with age.

ISSN:0163-5581    

DOI:10.1080/01635589509514378

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractUsing 63 healthy subjects, we conducted an observational study to assess associations between colonic epithelial cell proliferation and dietary intake of selected nutrients. Study subjects exhibited no personal or family history of colon carcinoma, familial polyposis coli, sporadic adenomas, or chronic inflammatory bowel diseases. In this study population, a negative association between the tritiated thymidine‐labeling index and dietary intake of calcium (p<0.003) was found after the effects of age, sex, body mass index (kglm2), dietary fat, and total energy were controlled in a linear regression model. The association for calcium indicated that a daily calcium intake of 1,200 mg was associated with a predicted thymidine‐labeling index of 6%. In the same model, a positive association with the thymidine‐labeling index was found for body mass index (p<0.002) and was suggested for female gender (p<0.09). No association was found between the thymidine‐labeling index and intake of fat, protein, carbohydrate, retinol, ascorbic acid, phosphorus, or iron. Repeat measures of diet in this investigation were used to estimate a subject's daily intake of selected nutrients.

ISSN:0163-5581    

DOI:10.1080/01635589509514379

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractThe effects of soybean saponins (SS) and gypsophilla saponin (GS) on the growth and viability of colon tumor (HCT‐15) cells in culture were investigated. Cells were incubated in various concentrations of saponins for 1 hour (short term) or 48 hours (long term). Cell growth and viability were monitored at 24 and 48 hours. SS and GS inhibited cell growth and reduced cell viability in a dose‐dependent manner in long‐term treatment. The viability of cells was also reduced by short‐term treatment with GS. The saponins differed in their effects on cell surface morphology: GS induced a rough and granular cell surface, whereas SS‐treated cells displayed only minor morphological alterations. Changes in membrane permeability were assessed by measuring leakage of the cytoplasmic enzyme lactate dehydrogenase from cells. GS showed a concentration‐dependent increase in lactate dehydrogenase leakage, whereas SS did not exhibit this effect. These results suggest that SS and GS have a significant growth‐inhibitory effect on colon tumor cells in culture. However, it would appear that they are acting through different mechanisms.

ISSN:0163-5581    

DOI:10.1080/01635589509514380

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractThermolyzed casein is known to promote the growth of aberrant crypt foci (ACF) and colon cancer when it is fed to rats that have been initiated with azoxymethane. We speculated that the promotion was a consequence of increased colonic protein fermentation (i.e., that the thermolysis of the casein decreases its digestibility, increases the amount of protein reaching the colon, and increases colonic protein fermentation and that the potentially toxic products of this fermentation promote colon carcinogenesis). We found that the thermolysis of casein reduces its digestibility and increases colonic protein fermentation, as assessed by fecal ammonium and urinary phenol, cresol, and indol‐3‐ol. Thermolysis of two other proteins, soy and egg white protein, also increases colonic protein fermentation with increased fecal ammonia and urinary phenols, and thermolysis of all three proteins increases the levels of ammonia and butyric, valeric, and i‐valeric acids in the cecal contents. We found, however, that the increased protein fermentation observed with thermolysis is not associated with promotion of colon carcinogenesis. With casein, the kinetics of protein fermentation with increasing thermolysis time are clearly different from the kinetics of promotion of ACF growth. The formation of the fermentation products was highest when the protein was thermolyzed for one hour, whereas promotion was highest for protein that had been thermolyzed for two or more hours. With soy and egg white, thermolysis increased colonic protein fermentation but did not promote colon carcinogenesis. Thus, although thermolysis of dietary casein increases colonic protein fermentation, products of this fermentation do not appear to be responsible for the promotion of colon carcinogenesis. Indeed, the results suggest that protein fermentation products do not play an important role in colon cancer promotion.

ISSN:0163-5581    

DOI:10.1080/01635589509514381

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractHigh fat consumption has been implicated as a risk factor for breast cancer. Experimental mammary carcinogenesis studies have demonstrated that the effect of high fat consumption is mainly exerted on the postinitiation stage of the disease process. We report data that have resulted in the formulation of a new hypothesis about the effect of dietary fat on mammary carcinogenesis, namely, that it promotes the development of a subpopulation of cells lacking a specific pathogenetic characteristic. In comparison with animals fed a low‐fat diet, female Sprague‐Dawley rats fed high‐fat diets during the promotional stage developed significantly more (number and proportion) 1‐methyl‐1‐nitrosourea‐induced mammary adenocarcinomas that did not contain a codon 12 GGA? GAA mutation in the c‐Ha‐ras protooncogene. The effect was independent of the types of fat fed, i.e., corn oil vs. fish oil. A model is presented to account for the preferential promotional effect of high fat consumption on 1‐methyl‐1‐nitrosourea‐initiated mammary epithelial cells. The hypothesis that the level of dietary fat consumed affects the proportion of mammary carcinomas that occur with a particular pathogenetic characteristic, in this case, the presence or absence of a Ha‐ras point mutation, has important implications on the direction of future investigations concerning fat and cancer risk.

ISSN:0163-5581    

DOI:10.1080/01635589509514382

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractTo determine whether patients with colon cancer metabolizeβ‐carotene differently from benign colon polyp patients, a normal control group (n = 13) and groups of resected colon polyp patients (n = 29) or resected colon cancer patients (Dukes A and BI, n = 21) were supplemented with placebo orβ‐carotene (30 mglday) taken with their morning meals for three months. Serum samples at zero and three months of the study were anlayzed blindly for retinoic acid andβ‐carotene. The results showed thatβ‐carotene levels in the serum of colon polyp and colon cancer groups were 8‐to 12‐fold higher than in the untreated control or the placebo‐treated groups. The benign polyp subjects (n = 17) receivingβ‐carotene showed a significant rise in serum trans‐retinoic acid at three months compared with Time 0. The trans‐retinoic acid values from the colon cancer group receivingβ‐carotene (n = 11) or placebo (n = 10) were significantly lower than the values from theβ‐carotene‐supplemented colon polyp group. It appears that trans‐retinoic acid levels in response toβ‐carotene supplementation are different between treated cancer and benign patients because of different body demands for retinoic acid.

ISSN:0163-5581    

DOI:10.1080/01635589509514383

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractAccuracy of methods to assess past diet in retrospective studies is of concern. Adjustment of current intake for subjects’perceptions of change is one alternative to estimate past intake. The authors studied the potential utility of perceived change in diet in residents of a rural Japanese community who participated in three sequential surveys with self‐administered questionnaires. Frequencies of consumption for 27 foods were investigated in the first and second questionnaires administered in 1988 and 1993 (n = 451), and perceived changes in their frequencies during this period were asked in the second and third questionnaires surveyed within two weeks (n = 214). Perceptions of change in diet were highly reproducible. At a group‐level analysis, they were consistent with the changes in food frequencies in 21 of the 27 items. Nevertheless, whereas current diet adjusted for perceived change correlated better with past intake than did current intake alone in 17 foods, improvement in Pearson's correlations was only marginal (median = 0.02). Perceptions of change in diet would therefore be of limited utility in improving estimate of past intake among individuals in retrospective studies.

ISSN:0163-5581    

DOI:10.1080/01635589509514384

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractThe purpose of this study was to assess the effect of energy expenditure, via voluntary exercise, on growth of xenografts of human breast carcinomas in athymic nude mice. Sedentary and exercising athymic nude mice bearing subcutaneous grafts of MDA‐MB231 human breast carcinomas were fed daily a purified high‐fat diet at 10% less than ad libitum to ensure an equal quantity of diet (energy) consumption for each sedentary and exercising mouse. The sedentary and exercising mice were housed singly; the exercising mice had, in addition, access to an activity wheel (24 hrslday). Growth of human breast carcinomas (carcinoma volumes) was evaluated during a five‐week period. Mean running activities of individual mice over the five‐week period ranged from<1 to 7.9 miles/day. Growth of the human breast carcinomas was significantly inversely correlated with the mean number of miles that each mouse ran per day (p4.7 miles/day, carcinoma growth was 83% of sedentary controls in the former group (p = 0.305) and 59% of sedentary controls in the latter group (p = 0.039). These results provide evidence that energy expenditure, via voluntary use of an activity wheel, can reduce significantly the growth of human breast carcinomas maintained in athymic nude mice.

ISSN:0163-5581    

DOI:10.1080/01635589509514385

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

摘要:

AbstractEpidemiological studies suggest that carotenoids may play a role in human breast carcinogenesis. To identify an anticarcinogenic mechanism, a laboratory model for examination of biologic effects is required. Efficacy of tetrahydrofuran (THF) for delivery ofβ‐carotene to a human mammary epithelial cell line has not been reported, and biologic effects of carotenoids on normal mammary epithelial cells or mammary epithelial cell lines have not been described. In these studies, we examined MCF‐10A cells treatedwith 0.04%, 0.10%, and 0.35% THF (vol/vol) for morphological signs of toxcity and determined effects of THF on cell proliferation over a seven‐day period. Cells treated with THF demonstrated a reduction in mean number of cells per dish (p<0.05) but still underwent a 3.2‐to 4.0‐fold increase in cell number over the seven days. MCF‐10A cells were also treated with a 7μmolll solution ofβ‐carotene and examined for morphological changes and effects on cell growth. Exposure to this concentration of carotenoid did not significantly affect proliferation but did induce the formation of cytoplasmic vacuoles similar to those seen in differentiating mammary epithelial cells. High‐performance liquid chromatography analysis revealed aβ‐carotene concentration of 0.004 nmol/106cells in the treatment group. The effects ofβ‐carotene and the non‐provitamin A carotenoid canthaxanthin were also examined in the in vitro cultures of primary human mammary epithelial cells obtained from reduction mammoplasties of two individuals. Exposure to these carotenoids induced morphological changes consistent with cellular differentiation and had a dramatic effect on the proliferative life span of these cells. Thus carotenoids may directly affect the proliferative capacity and differentiation of mammary epithelial cells, which may be among the chemoprotective activities of these compounds.

ISSN:0163-5581    

DOI:10.1080/01635589509514386

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor

ISSN:0163-5581    

DOI:10.1080/01635589509514377

出版商:Taylor&Francis Group    

年代:1995

数据来源: Taylor