摘要:

AbstractHere we report that genistein, a soybean isoflavone, strongly inhibits tumor promoter‐induced H2O2formation both in vivo and in vitro. Genistein suppressed H2O2production by 12‐O‐tetrade‐canoylphorbol‐13‐acetate‐(TPA) stimulated human polymorphonuclear leukocytes (PMNs) and HL‐60 cells in a dose‐dependent manner over the concentration range 1–150μM. Human PMNs were more sensitive to the inhibitory effect of genistein than HL‐60 cells (50% inhibitory concentration 14.8 and 30.2μM, respectively). In addition, genistein moderately inhibited Superoxide anion formation by HL‐60 cells and scavenged exogenously added H2O2under the same conditions as in cell culture. However, the H2O2‐scavenging effect of genistein was about 50% lower than its inhibition of cell‐derived H2O2formation at all concentrations. In the CD‐1 mouse skin model, genistein strongly inhibited TPA‐induced oxidant formation, edema, and PMN infiltration in mouse skin. Inhibition of TPA‐mediated H2O2in vivo may result from decreased cell‐derived H2O2formation, scavenging of H2O2produced, and/or suppression of PMN infiltration into the dermis. The antioxidant properties of genistein may be responsible for its anticarcinogenic effects, and the dietary availability of genistein makes it a promising candidate for the prevention of human cancers.

ISSN:0163-5581    

DOI:10.1080/01635589309514265

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractTo determine correlates of the geographic variation in colon cancer mortality within China, dietary variables, biochemical markers, and other factors from an ecological survey in 49 Chinese rural counties were examined. High consumption of animal foods, salt‐preserved vegetables, and beer was associated with increased mortality of colon cancer, whereas the rates were significantly inversely related with intake of green vegetables. Serum levels of total cholesterol, urea nitrogen, and lipid peroxide were positively correlated with colon cancer mortality, after adjustment for each other and for other blood nutrients. No appreciable associations, however, were found between colon cancer and serum levels ofβ‐carotene,α‐tocopherol, vitamin C, and selenium. In addition, prevalence of schistosomiasis was significantly correlated with increased colon cancer mortality. This ecological study indicates that observations from earlier analytic investigations in Western societies may apply to a Chinese rural population and suggests that schistosomiasis and dietary factors may contribute to the remarkable geographic variation of colon cancer in China.

ISSN:0163-5581    

DOI:10.1080/01635589309514266

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractFlavonoids are strong antioxidants that occur naturally in foods and can inhibit carcinogenesis in rodents. Accurate data on population‐wide intakes of flavonoids are not available. Here, using data of the Dutch National Food Consumption Survey 1987–1988, we report the intake of the potentially anticarcinogenic flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin among 4,112 adults. The flavonoid content of vegetables, fruits, and beverages was determined by high‐performance liquid chromatography. In all subjects, average intake of all flavonoids combined was 23 mg/day. The most important flavonoid was theflavonol quercetin (mean intake 16 mg/day). The most important sources of flavonoids were tea (48% of total intake), onions (29%), and apples (7%). Flavonoid intake did not vary between seasons; it was not correlated with total energy intake (r = 0.001), and it was only weakly correlated with the intake of vitamin A (retinol equivalents, r = 0.14), dietary fiber (r = 0.21), and vitamin C (r = 0.26). Our use of new analytic technology suggests that in the past flavonoid intake has been overestimated fivefold. However, on a milligram‐per‐day basis, the intake of the antioxidant flavonoids still exceeded that of the antioxidantsβ‐carotene and vitamin E. Thus flavonoids represent an important source of antioxidants in the human diet.

ISSN:0163-5581    

DOI:10.1080/01635589309514267

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractThe levels of S‐adenosylmethionine (SAM) were determined in the livers of male weanling rats fed six different forms of selenium for five weeks. The following forms of selenium were administrated in the diet in logarithmic doses: sodium selenite, sodium selenate, sodium selenide, selenomethionine, selenocystine, and selenium sulfide. An overall increase in hepatic SAM was observed, and all compounds resulted in at least one observation where SAM was significantly elevated (p<0.01). No dose‐response relationship was found to exist, however. A comparison of the relative toxicity of each of the selenicals was based on a dose of 10 ppm dietary selenium for each chemical form. The elevation of SAM resulting from the subchronic administration of selenium may be one mechanism involved in the well‐known chemopreventive effects in experimental models.

ISSN:0163-5581    

DOI:10.1080/01635589309514268

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractThe effect of rice bran hemicellulose (RBH) on 1,2‐dimethylhydrazine‐(DMH) induced intestinal carcinogenesis was studied in male Fischer 344 rats. Rats were fed a basal control diet or a diet containing 2% or 4% RBH at five weeks of age. At 6 weeks of age, all animals were given an intraperitoneal injection of DMH (20 mg/kg body wt) at weekly intervals for 20 weeks and autopsied 7 weeks after the last injection. The incidence of DMH‐induced colon tumors was significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p<0.05). The number of colon tumors per rat was also significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p<0.05). The present study suggested that the water‐soluble RBH played a preventive role in DMH‐induced large bowel carcinogenesis in Fischer 344 rats.

ISSN:0163-5581    

DOI:10.1080/01635589309514269

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractTo evaluate the relationship between cervical intraepithelial neoplasia (CIN) and undemutrition, a pair‐matched case‐control study was conducted in a low‐income urban population. As a broad measure of nutritional status, serum albumin, serum ferritin, hematocrit, percent desirable weight, and percent calories consumed as protein were examined. Cases (n = 102) had biopsy‐confirmed CIN I, II, or III, and clinic controls (n = 102), matched on age, race, and clinic, had normal Pap smears. Survey‐collected data and frozen serum were utilized to study the hypothesized association.Crude and adjusted odds ratios and 95% confidence intervals were estimated using conditional logistic regressions. Results suggest a protective role for serum ferritin for those in the highest quartile relative to those in the lowest quartile. Controlling for smoking and monthly personal income, an adjusted odds ratio of 0.2 with a corresponding 95% confidence interval of 0.1–0.7 was observed. Similar findings were noted when all other available CIN risk factors were controlled. In addition, a dose gradient was present for dietary iron intake (p = 0.01). No associations were observed between each of the other undemutrition indexes and CIN.Although only high levels of serum ferritin were associated with a protective effect against CIN, when coupled with the results from other studies that suggest carotenoids, folates, and vitamin C to be protective, the overall hypothesis that poor nutriture is associated with CIN remains viable. Lack of an association with the other nutritional indexes may reflect the relatively sufficient nutritional status of low‐income individuals residing in the United States, as opposed to the undernourished population of the Third World.

ISSN:0163-5581    

DOI:10.1080/01635589309514270

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractA case‐control study was conducted in Melbourne, Australia. Forty‐one men with histologically confirmed squamous cell oral or pharyngeal cancer were compared with 398 male community controls. A statistically significant increase in risk was found for alcohol (ethanol) consumption and for smoking, and there was a synergistic effect for these two exposures. Statistically significant protection was noted with increasing intake of dietary vitamin C, dietaryß‐carotene, fruit, vegetables, and dietary fiber. The mean serum levels ofß‐carotene and vitamin A were statistically significantly lower when the cases were compared with another set of 88 male controls of a similar age who were hospitalized for minor surgical operations. This study confirms a causal effect of smoking and alcohol and a protective role for a high dietary intake of fruit, vegetables, cereals, and, particularly,ß‐carotene‐and vitamin C‐containing foods.

ISSN:0163-5581    

DOI:10.1080/01635589309514271

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractSurvey reports indicate that women perceive that their diets have changed in ways consistent with dietary guidelines recommended by national agencies. We have attempted to determine whether perceived change in food intake is a useful tool for estimation of either past intake or pattern of change in food consumption. Twin sisters of breast cancer patients, at obvious high risk of breast cancer, were aware of dietary guidelines concerning cancer, as indicated by beliefs about specific foods that should be increased or decreased to prevent cancer. Perception of change, as reported by them, was not found to be a reliable indicator of actual change in food frequency, as measured by the difference between sequential food frequency questionnaires. Consumption of high‐fat foods was observed to have decreased over the interval, regardless of perceived change in consumption. Moreover, prediction of past food frequency on the basis of perceived change and current intake combined resulted in a less accurate appraisal of past diet than did the use of current intake alone. Perceived change in food frequency appears to be biased in different ways for different foods and seems to be influenced by beliefs about the role of diet in cancer. Studies of etiology should probably not rely on such methods.

ISSN:0163-5581    

DOI:10.1080/01635589309514272

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractThis study was performed to evaluate the relative efficacy of Maharishi Amrit Kalash ambrosia (MAK‐5) and Maharishi Amrit Kalash nectar (MAK‐4) on murine (B‐16) and human (SK‐Mel) melanoma cells in culture. Ethanol extract (EE) of MAK‐5 (EE‐MAK‐5) induced morphological differentiation (enlargement of soma and nuclei and formation of long dendritic processes) and growth inhibition in mouse melanoma cells, whereas EE‐MAK‐5 inhibited only growth in human melanoma cells. Murine melanoma cells were more sensitive (about 3 times) than human melanoma cells in culture to EE‐MAK‐5; the aqueous extract (AE) of MAK‐5 (AE‐MAK‐5) was ineffective in both cells. Boiling EE‐MAK‐5 for 10 minutes or exposing it to light at room temperature for 72 hours did not alter growth‐inhibiting potency. Ethanol extract of another herbal agent, MAK‐4 (EE‐MAK‐4), inhibited growth in human melanoma cells but not in mouse melanoma cells. AE‐MAK‐4 was ineffective for both cells. These results suggest that murine and human melanoma cells respond differently to MAK‐5 and MAK‐4 and that human melanoma growth‐inhibiting agents are present in both EE‐MAK‐5 and EE‐MAK‐4.

ISSN:0163-5581    

DOI:10.1080/01635589309514273

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

AbstractThe protective role of dietary fibers on tumorigenic effects of 1,2‐dimethylhydrazine (DMH) on the rat colon was studied using histochemical, immunohistochemical, and biochemical analyses. Rats were injected with DMH (20 mg/kg sc) for five weeks, once a week, and were fed laboratory chow (Control I), semisynthetic fiber‐free diet (Control II), or 18% or 25% assorted fiber (cellulose, beans, corn) diet. The rats were sacrificed 12, 16, and 24 weeks after the carcinogenic injections. Adenomatous tumors developed in 90–100% of the animals fed chow or fiber‐free diets. A diet with high concentrations (25%) of corn dietary fiber significantly decreased the tumor incidence (40% and 42%) and tumor yield (p<0.01). Diets with lower concentrations of fibers (18%) did not protect against tumorigenic effects of DMH. No differences were found in pathological parameters of tumors obtained from different dietary groups: the damage index (percentage of damaged cells per section) was very similar in all groups studied. Diets enriched with dietary fibers (25%) had a significant protective effect in DMH‐induced rat colon cancer.

ISSN:0163-5581    

DOI:10.1080/01635589309514274

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor