摘要:

AbstractThis study examined the effect of increasing dietary vitamin D on chemically induced colon carcinogenesis. Male Fischer 344 rats were first injected with 1,2‐dimethylhydrazine (200 mg/kg) and then fed one of five dietary levels of vitamin D as cholecalciferol (250, 1,000, 2,000, 4,000, and 10,000 IU/kg diet) for nine months. Dietary vitamin D3had no effect on weight gain. Plasma 25‐hydroxyvitamin D3levels were similar for the 1,000 and 2,000 IU/kg groups but varied in a dose‐related manner for the other groups. Vitamin D did not significantly alter the tumor incidence in either the distal or the proximal colon. No significant differences in the labeling index were found in either the proximal or the distal colon. Within the distal colon, the proliferative zone increased in a dose‐related manner. Distribution of labeled cells within the crypt compartments was not affected by dietary vitamin D. Bone and serum minerals in general were unaffected by dietary vitamin D. This study shows that, at this level of dietary calcium, vitamin D did not affect 1,2‐dimethylhydrazine‐induced colon carcinogenesis.

ISSN:0163-5581    

DOI:10.1080/01635589309514242

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractUltraviolet B (UV‐B) irradiation of C3H/HeN mice induces skin cancer. In this study, the ability of dietary d‐a‐tocopheryl acetate to reduce photocarcinogenesis was tested in this murine model. Skin cancers developed in 67.5% of UV‐B∼irradiated mice by 31 weeks after the first UV exposure. Supplementation with 100 or 200 IU of d‐α‐tocopheryl acetate per kilogram of diet led to a reduction of the incidence to 46% and 19%, respectively. The latter value was significantly different from that found in mice fed the basal diet (p = 0.039, one‐sided P value by log‐rank test). Skin levels ofα‐tocopherol varied with the dietary dose of d‐a‐tocopheryl acetate. No toxicity was evident in unirradiated mice fed the vitamin E‐supplemented diet, but 40% of the UV‐B‐irradiated mice fed 200 IU of vitamin E per kilogram of diet died by 31 weeks after the first UV‐B treatment. Decreased relative spleen weight was observed in the UV‐B‐irradiated mice fed the vitamin E‐supplemented diet. In summary, oral d‐a‐tocopheryl acetate prevented photocarcinogenesis, but at doses that were toxic to inbred C3H/HeN mice after exposure to 8.6×105J/m2of UV‐B irradiation.

ISSN:0163-5581    

DOI:10.1080/01635589309514243

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractOmega‐3 fatty acids, abundant in fish oil, are reported to alter membrane properties when incorporated into membrane phospholipids. We report that dietary omega‐3 fatty acids, incorporated into tumor cell membranes, alter tumor recognition and cytolysis by the immune system. Mice were fed diets rich in corn oil, hydrogenated coconut oil, or menhaden (fish) oil. T27A leukemia cells were grown as an ascites tumor in these mice and harvested for biochemical and immunologic assays. The incorporation of the long‐chain omega‐3 fatty acid docosahexaenoic acid (22: 6) into tumor plasma membranes correlated with an increased susceptibility to tumor cytolysis by alloreactive cytotoxic T lymphocytes and decreased expression of a class I major histocompatibility complex epitope, monitored by complement‐mediated lysis and radioimmunoas‐say. Thus the immunologic phenotype of this ascites tumor reflected the source of oil present in the diet during tumor growth.

ISSN:0163-5581    

DOI:10.1080/01635589309514244

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractDocosahexaenoic acid (DHA, 22: 6) is a long‐chain omega‐3 fatty acid abundant in cold water fish; it is the most unsaturated fatty acid found in biologic systems and is reported to alter membrane structure. To explore DHA's effect on membrane function, we have fused tumor cells with synthetic phosphatidylcholine (PC) containing stearic acid in the sn‐1 position and DHA in the sn‐2 position (18: 0, 22: 6 PC) and have found the lipid‐modified tumor cells to be more sensitive to cytolysis by alloreactive cytotoxic T lymphocytes. Cold target competition experiments suggested that fusion of tumor plasma membranes with 18: 0, 22: 6 PC produced a qualitative change in expression of surface antigens recognized by cytotoxic T lymphocytes. We monitored the expression of various epitopes on tumor cells by complement‐mediated lysis and radioimmu‐noassay with monoclonal antibodies against H‐2 class I antigens. Our results suggest that membrane‐bound DHA increases the expression of some epitopes while decreasing the expression of others and that different tumor lines vary in the magnitude of DHA's effect. Our findings are consistent with a model in which DHA‐containing phospholipids segregate into membrane domains, in turn altering the expression of membrane proteins.

ISSN:0163-5581    

DOI:10.1080/01635589309514245

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractOne hundred four consecutive patients with newly diagnosed small cell lung cancer, metastatic breast cancer, and ovarian cancer in good physical functional condition (performance rating 0–1 on Eastern Cooperative Oncology Group scale) were divided into a weight‐losing group (>5% unintentional weight loss within 3 mo; n = 48) and a weight‐stable group (n = 56). Dietary intakes in relation to fat‐free mass were not different in the two groups. According to the Quality of Life index and the General Health Questionnaire, weight‐losing patients had significantly lower quality of life than weight‐stable patients. In patients with weight loss, daily intakes of energy and protein correlated significantly with scores on the General Health Questionnaire. This study has shown that many ambulatory cancer patients do not eat enough to maintain weight and that even a moderate weight loss is associated with psychological distress and lower quality of life.

ISSN:0163-5581    

DOI:10.1080/01635589309514246

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractUsing data from 59 countries, we conducted an international comparison study to identify nutritional predictors of age‐adjusted oral and esophageal cancer mortality rates. Statistical models accounted for per capita tobacco disappearance data, alcohol consumption, and various measures of socioeconomic status. For oral cancer, stepwise regression results showed protective effects for milk/dairy products (B =‐0.030, p<0.0001) and cabbage consumption (B =‐0.391, p = 0.01) and increased risk from vegetable oil (B = 0.072, p = 0.04) and excess animal fat calories (B = 0.344, p<0.0001) as well as marginally increased risk from cereals (B = 0.008, p = 0.08). Results were obtained after accounting for all background factors, including sex (model R2= 0.52). For esophageal cancer, stepwise results indicated protective effects for fruit (B =‐0.046, p = 0.0006) and total caloric intake (B =‐0.013, p<0.0001) and increased risk from vegetable oil (B = 0.061, p = 0.04) and meat (B = 0.031, p<0.0001) consumption (model R2= 0.55). When analyzed separately by sex, results were similar, indicating that the risk factors are probably the same in both sexes, even though women consistently have fewer deaths, on average, from these cancers. On the basis of results from stepwise regression models, we also fitted general linear models for mortality rates of each cancer site, and results were similar in terms of magnitude and direction of effects. Although the evidence provided by this type of analysis using data aggregated by country is limited in terms of control for potential confounding effects and modeling of possible effect modification, an effect of high meat, animal product, or vegetable oil and low fruit and cabbage consumption is consistent with the known biology of these tumors.

ISSN:0163-5581    

DOI:10.1080/01635589309514247

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractThe present study was designed to investigate the role of membrane fatty acid (FA) composition on inositol phosphate (InsP) release by a human colon tumor cell line. Cells were supplemented for five days in culture with 0,10, 30, or 100μM sodium stearate (18: 0), linoleate [18: 2(ω‐6)], or linolineate [18: 3(ω‐3)]. These FAs were supplied as a complex with FA‐free bovine serum albumin. InsP release was examined in these cells with or without stimulation with deoxycholic acid (DCA) after they were labeled with [3H]myoinositol. FA enrichment was found to influence inositol incorporation into membrane lipids. Although 18: 0 had no effect, 18: 2(ω‐6) decreased the incorporation. On the other hand, 18: 3((ω‐3) increased the incorporation of inositol compared with the cells supplemented with the other FAs, but they were not different from control. Basal release of total InsP was elevated only with supplementation of 10 and 30μM 18: 3(ω‐3). FA supplementation with 18: 0 at 30 \iM and 18: 2 at 30 and 100μM resulted in downregulation of basal release of InsP. Enrichment of HT‐29 cell membranes with polyunsaturated FAs resulted in a significant increase in stimulated release of InsP, but this was not seen with saturated FA supplementation. At 10μM supplementation, 18: 2 had the greatest effect on stimulated InsP release. This effect of 18: 2 disappeared at 30μM. However, the increase in the stimulated InsP release caused by 18: 3 occurred at 10 and 30μM. DCA‐stimulated release of InsP was not downregulated by any FA supplementation. This study showed that enrichment of the membranes with polyunsaturated FAs increases the response of the phosphatidylinositol cycle to DCA stimulation. In addition, enrichment with 18: 3(ω‐3) increases the basal turnover of InsP. It is concluded that alteration of membrane FAs has a profound effect on the phosphatidylinositol cycle.

ISSN:0163-5581    

DOI:10.1080/01635589309514248

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractWe studied the ability of a soybean extract containing the Bowman‐Birk protease inhibitor (BBI), referred to as BBI concentrate (BBIC), purified BBI (PBBI), and the chymotrypsin inhibitor from potatoes to suppress oral carcinogenesis in hamsters induced by 7,12‐dimethyl‐benz[a]anthracene (DMBA). Application of 1% solutions of BBIC and PBBI five times per week to DMBA‐treated hamster cheek pouches were highly effective in suppressing oral carcinogenesis, whereas a 1% solution of the chymotrypsin inhibitor from potatoes did not lead to a significant suppression of carcinogenesis. BBIC and PBBI suppressed carcinogenesis at concentrations ranging from 1% to 0.01% and were equally effective when given as a 1% solution five times per week, three times per week, or once per week. A 1% solution of BBIC suppressed oral carcinogenesis when given at the following times during the assay period: 0–180, 0–90, 14–90, and 45–135 days. Thus, protease inhibitor treatment could be started as late as 45 days after the beginning of the carcinogen exposure and have an irreversible suppressive effect on the carcinogenic process.

ISSN:0163-5581    

DOI:10.1080/01635589309514249

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractIncreased colonic cell proliferation (CCP) has been reported in patients with colonic neoplasia. Previous studies in rats suggest that increased CCP is closely related to increased reactive oxygen metabolite (ROM) production. We hypothesized that, in humans, ROM production is also involved in increased CCP. Using a chemiluminescence probe, we estimated the levels of ROMs in the rectal mucosa of 37 patients who previously had colonic neoplasia (14 with cancer and 23 with polyps) and 20 control subjects who had normal colonoscopic examination and no history of colonic neoplasia. Normal‐appearing rectal mucosa of patients with colonic neoplasia contained significantly higher levels of luminol‐enhanced chemiluminescence (LECL) than rectal mucosa of control subjects (p<0.01). There was no difference in LECL levels between patients with polyps and patients with cancer. Four of 20 controls and 31 of 37 patients had LECL levels 1,000 cpm/mg protein (positive and negative predictive values of 89% and 73%, respectively). Addition of indomethacin, a specific cyclooxygenase inhibitor, to the tissue suspension significantly decreased LECL levels. These preliminary data suggest that 1) ROMs may be involved in both the rate of CCP and the process of malignant cellular transformation, 2) oxidation of arachidonic acid via the cyclooxygenase pathway significantly contributes to the production of ROMs in rectal mucosa, and 3) measurement of the levels of LECL produced by the rectal mucosa may be a sensitive marker to screen for colonic neoplasia.

ISSN:0163-5581    

DOI:10.1080/01635589309514250

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractWe previously showed that daily intake ofβ‐carotene, a nontoxic antioxidant, reduces lipid peroxidation as assessed by serum lipid peroxide levels. An alternative method to detect lipid peroxidation is the measurement of pentane in breath. Pentane is a five‐carbon hydrocarbon that is released when an omega‐6 unsaturated fatty acid undergoes peroxidation. The aim of this study was to see whether graded doses ofβ‐carotene would affect breath pentane excretion in normal subjects placed on a carotenoid‐free liquid diet for two weeks. The subjects were then repleted with either 15 (n = 7) or 120 mg (n = 8) ofβ‐carotene daily for four weeks while continuing the same diet. Serumβ‐carotene and breath pentane were measured before and afterβ‐carotene refeeding. Lipid peroxidation, as assessed by gas‐chromatographic measurement of breath pentane, was significantly (p<0.05) reduced by daily supplements of 120 mgβ‐carotene (from 3.7±0.9 to 2.2 + 1.4 nmol/l). However, the decline in pentane exhalation observed with the 15‐mgβ‐carotene dose did not achieve statistical significance (p = 0.13).

ISSN:0163-5581    

DOI:10.1080/01635589309514251

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor