摘要:

AbstractExperiments were conducted to determine the effect ofβ‐carotene on human colon cancer cells in vitro.β‐Carotene solubilized in tetrahydrofuran (THF) was determined to be cytotoxic for three different cell lines: LS 180, SW620, and HCT‐15. The number of LS 180 and SW 620 cells surviving treatment with 2.9μ?β‐carotene was significantly reduced relative to THF‐treated cells, and a similar reduction was achieved in HCT‐15 cells with use of 5.8μ?β‐carotene. These concentrations are in the range achieved in serum of individuals supplemented withβ‐carotene at 30 mg/day. There was noβ‐carotene cytotoxicity in the concentration range that characterizes serum of unsupplemented individuals. Vitamin ? at>200μ? was not cytotoxic and at higher concentrations slightly stimulated proliferation of all three cell lines. Exposure of cells to vitamin ? did not diminish the cytotoxicity ofβ‐carotene, suggesting that the toxic effect ofβ‐carotene is not due to prooxidant activity. Percent cytotoxicity was increased by extending the duration of exposure of cells toβ‐carotene. Interestingly,β‐carotene cytotoxicity decreased with increasing cell density. This density‐dependent toxicity was attributable to a higherβ‐carotene concentration per cell for cells plated at lower densities. Thus toxicity ofβ‐carotene for colon cancer cells is dose, time, and cell density dependent and occurs in vitro at concentrations that can be achieved safely in humans.

ISSN:0163-5581    

DOI:10.1080/01635589609514446

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractGrowth and metastasis to the lung of the human breast cancer cell line MDA‐MB‐435 in nude mice fed a high‐fat (20% wt/wt) high‐linoleic acid (LA; 12% wt/wt) diet were significantly reduced by the addition of the cyclooxygenase inhibitor indomethacin to the drinking water at a dose of 10μg/ml (approximately 1 mg/kg body wt). No toxicity was observed in these mice; at 20μg/ml indomethacin, gastric ulcerations occurred. After necropsy, tumor eicosanoids were measured by radioimmunoassay in the control and 10μg/ml indomethacin treatment groups. Levels of the cyclooxygenase products prostaglandin (PG) E (PGE), 6‐keto‐PGFlα, and thromboxane B2(TxB2) were significantly reduced in indomethacin‐treated mice compared with controls; however, the 6‐keto‐PGF1α‐to‐TxB2ratio was significantly increased. Two lipoxygenase products, 5‐hy‐droxyeicosatetraenoic acid (5‐HETE) and 15‐HETE, were unaffected, but the 12‐HETE levels were increased compared with the untreated high‐LA‐fed group. Metastases to the lungs in mice fed a high‐fat low‐LA (2% wt/wt) diet were also reduced compared with those in the high‐LA‐fed control mice, but whereas tumor cyclooxygenase and lipoxygenase product levels were reduced, no change in the 6‐keto‐PGF1α‐to‐TxB2ratio was observed. The use of selective cyclooxygenase inhibitors may prevent LA‐mediated progression of breast cancer at several levels of the metastatic cascade, among which may be interference with tumor cell‐vascular endothelial cell interaction and with angiogenesis.

ISSN:0163-5581    

DOI:10.1080/01635589609514447

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractGarlic organosulfur compounds exert chemopreventive effects at several organ sites in rodents after administration of chemical carcinogens, possibly by inhibiting carcinogen activation via cytochrome P‐450‐mediated oxidative metabolism. It has been suggested that the variability in potency of tumor inhibition by garlic sulfur compounds is due to structural differences, such as the number of allyl and sulfur groups. In this study, diallyl sulflde (DAS), diallyl disulfide (DADS), and allyl methyl sulfide (AMS) were administered to acetone‐treated adult male Sprague‐Dawley rats by gastric gavage at a dose of 1.75 mmol/kg in cottonseed oil. After 15 hours, hepatic microsomal cytochrome P‐450 activity and content were examined. The activity of p‐nitrophenol (pNP) hydroxylase (E.C. 1.14.13.29) was significantly decreased by all garlic compounds, whereas benzphetamine N‐demethylase and ethoxyresorufin O‐deethylase activities were not changed The activity of pNP hydroxylase was decreased to 31%, 54%, and 65% of control activity, and immunodetectable CYP2E1 protein levels were decreased in a similar manner by DAS, DADS, and AMS, respectively. Additional acetone‐treated rats were given 4‐methyl pyrazole, a ligand specific for CYP2E1, intraperitoneally five hours after garlic compound administration. Ten hours later, pNP hydroxylase activity was decreased to 73%, 78%, and 67% of control levels by DAS, DADS, and AMS, respectively. Further studies are needed to determine whether the variable potency of inhibition of CYP2E1 enzyme activity is related to chemopreventive efficacy of garlic sulfur compounds.

ISSN:0163-5581    

DOI:10.1080/01635589609514448

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractIn the two‐stage protocol of skin carcinogenesis, the carcinogen 7,12‐dimethylbenz[a]anthracene (DMBA) is applied to the skin of mice at around seven weeks of age. We previously performed DMBA initiation at three weeks of age to study the effect of pharmacological (30μg/g diet) dietary retinoic acid (RA) on skin carcinogenesis. In this study we asked whether dietary pharmacological RA is equally effective against skin carcinogenesis when mice are initiated with (DMBA) at 7 weeks of age and then subjected to weekly applications of the tumor promoter 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) or mezerein (MEZ) for 20 weeks. Similar to the three‐week initiation protocol, high dietary RA inhibited papilloma incidence and yield in MEZ‐but not in TPA‐promoted female SENCAR mice. In addition, carcinoma incidence and yield were decreased by high dietary RA in TPA‐as well as MEZ‐treated mice. These data demonstrate that the high dietary RA diet is as effective in inhibiting papilloma and carcinoma formation when the DMBA is applied at seven weeks of age as at three weeks.

ISSN:0163-5581    

DOI:10.1080/01635589609514449

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractThis study evaluates the reproducibility of nutrient intake in a 45‐item food frequency questionnaire (FFQ). The FFQ was mailed in 1980 to persons eligible to participate in a large cohort study on diet and cancer risk; a follow‐up version with 75 food items was mailed in 1988 to selected original participants. A random sample of 500 men and 500 women from the New York State general population was selected from individuals who responded to both waves of the study. The subjects’1988 responses were compared with their original 1980 responses; Pearson's correlations ranged from 0.25 for retinol to 0.55 for vitamin C with or without supplements and vitamin E with supplements in women. Reproducibility of nutrient intake in this questionnaire indicates that brief FFQs may be a useful tool to study nutrient intake and chronic disease relationships, although they are subject to substantial measurement error and dietary change.

ISSN:0163-5581    

DOI:10.1080/01635589609514450

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractComposition of diets may influence growth, diseases, tumor rates, and responses to chemical treatment. For two years, Fischer 344 rats were fed the NIH‐07 open‐formula nonpurified diet (∼23% protein,∼5%fat, and∼3.5% fiber) and nonpurified experimental diets (NTP‐90, NTP‐91, and NTP‐92) containing lower protein and higher fat and fiber (14.6–15.3% protein, 7.2–8.5% fat, and 9.4–14% fiber) than the NIH‐07 diet. Rats were evaluated for growth patterns, survival, hematology, serum chemistry, nephropathy, and tumor incidences. Growth patterns were similar in rats fed the experimental diets and in those fed the NIH‐07 diet. However, in rats fed the experimental diets, the adult body weights were significantly (6–9%) lower and the survival at 110 weeks of age was significantly higher (15–20%) than in rats fed the NIH‐07 diet. Lower protein content of experimental diets decreased the severity of nephropathy. Higher fat content of experimental diets appears to have decreased the incidence or delayed the development of leukemia and associated mortality in males. Higher fiber content of experimental diets appears to have delayed the development of mammary tumors and associated mortality in females. Higher fat and/or fiber of the experimental diets decreased the incidence of pheochromocytomas in males. The lower protein and higher fat and fiber contents of the experimental diets decreased the spontaneous tumor burden in two‐year studies. These studies indicate that diets for rats in long‐term studies could be modified to decrease the severity of nephropathy and to decrease/delay the development of spontaneous tumors.

ISSN:0163-5581    

DOI:10.1080/01635589609514451

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractAmong patients with breast cancer, tumors that contain estrogen receptors (ER) are associated with improved survival and better response to hormone therapy than those not expressing these receptors. The purpose of these case comparison studies was to examine the relationship between carotenoids, vitamin A, and the tumor ER status in women at diagnosis of primary breast cancer. The focus of the first study was the relationship between dietary intake and ER status, and the focus of the second study was the relationship between ER status and the plasma carotenoid, retinol, and tocopherol concentrations. We evaluated tumor ER status and self‐reported dietary intake in 142 women and plasma concentrations of carotenoids, retinol, and tocopherols in 149 women, at diagnosis of breast cancer, before any medical or surgical treatment. In the first study the overall odds of ER‐positive status were increased in relation to number of mammograms in the past five years, number of breast‐fed babies, dietary carotenoid intake, and more frequent intake of yellow and green vegetables. Overall odds of ER‐positive status were decreased in relation to years of oral contraceptive use and preformed vitamin A intake. In the second study older women, women with higher plasma lutein concentration, and women not usingβ‐carotene supplements were more likely to be ER positive, when data were adjusted for body mass index and factors that may influence breast cancer risk or hormonal status. Significant independent relationships between plasma retinol or tocopherol concentrations and ER status were not observed. The strong and independent relationships between carotenoid intake, plasma lutein concentration, and ER status may relate to observations linking a carotenoid‐rich diet with improved prognosis after diagnosis of breast cancer.

ISSN:0163-5581    

DOI:10.1080/01635589609514452

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractTo examine whether vegetable and fruit intake modify colorectal cancer risk, a case‐control study was conducted in Uruguay. Dietary patterns were assessed in detail (for cases before diagnosis or symptoms occurred) by use of a food frequency questionnaire on 61 food items, which allowed the calculation of total energy intake. Nutrient residuals were calculated through regression analysis. After adjustment for potential confounders (which included body mass index, total energy, and total alcohol intake), a reduction in risk for total vegetable intake, total fruit intake, and lettuce, apple, and banana consumption was observed. The strongest protection was observed for banana intake (odds ratio 0.28; 95% confidence level 0.16–0.50) for consumption in the third tertile compared with the first.

ISSN:0163-5581    

DOI:10.1080/01635589609514453

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractThe reproducibility of the widely used Health Habits and History Questionnaire (HHHQ) for estimating“usual past‐year”nutrient intake was examined. The HHHQ was self‐administered on three occasions during three different seasons; 68 women (avg age 43 yrs) provided usable data for all three questionnaires in the appropriate seasons. Intraclass correlations (ICC) among the three administrations ranged from 0.56 (carotene) to 0.82 (fat as percentage of energy), with a median of 0.72. Thus, reliability was moderate to good, and season of administration/ordinality generally had little impact on ranking of individuals. The point estimates of intake of energy and a number of nutrients were higher in the first administration (winter). Except for dietary fiber and possibly carotene, most differences disappeared when adjusted for energy using a nutrient density approach, as well as using repeated‐measures regression models. The higher intake in the first administration may be due more to either learning or fatigue effects rather than an effect of seasonal food availability on perceptions of“usual”intake. These data should be used in conjunction with validity data in the future to help evaluate the gain in precision of group means (and changes in these means) and improved estimates of odds ratios and correlations between nutrients and factors such as serum values, if a questionnaire is administered more than once.

ISSN:0163-5581    

DOI:10.1080/01635589609514454

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor

摘要:

AbstractWe hypothesized that alteration of the dietary arginine‐methionine balance might inhibit tumor growth and suggest nutritional strategies for cancer therapy. The Morris hepatoma 3924A was subcutaneously transplanted in ACI rats. Control diets containing normal levels of arginine, methionine, and other amino acids in replacement of protein (24%), carbohydrates (59%), fat (10%), and fiber, vitamins, and minerals (7%) were fed for 28 days. Six experimental diets were adjusted to maintain amino acids at 23–25% and carbohydrates at 58–60% these diets were 1%‐2% deficient in arginine or supplemented with 1–2% arginine (expressed as percent amino acid content of diet) in combination with normal, deficient, and supplementary levels of methionine. Daily food intake was unaffected by the experimental diets. The control groups gained 26.4±2.8 g body weight, and small body weight decrements ranged from 3.5% to 8.4% in the groups fed the experimental diets. Tumor weight of controls was 8.5±1.5% of body weight. The experimental diets that produced significant tumor growth inhibition (TGI) were 1) the arginine‐methionine‐deficient diet, 2) the arginine‐excess‐methionine‐deficient diet, 3) the arginine‐deficient diet, and 4) the excess‐arginine diet. Diets containing excess methionine failed to produce TGI. TGI resulted in tumor weights 41–46% of control values. TGI was associated with significantly lower blood urea nitrogen, plasma protein, and tumor spermidine‐to‐spermine ratio than in tumor‐bearing controls. It is concluded that dietary alteration of a single amino acid, arginine, might be a potentially useful nutritional strategy for controlling tumor growth.

ISSN:0163-5581    

DOI:10.1080/01635589609514455

出版商:Taylor&Francis Group    

年代:1996

数据来源: Taylor