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1.
In the prairie dog model of cholesterol cholelithiasis, a high incidence of gallstones is achieved by feeding a semipurified lithogenic diet containing 0.4% cholesterol for 2 mo. On occasion, we noted a decrease in the percentage of animals with gallstones from 90–100% to 50–55%. To explain this phenomenon, we studied the effect of dietary history on gallstone formation. After weaning, animals were fed either rodent chow or alfalfa plus corn (mo 0–3) followed by a cross-over experiment at mo 4–6. Gallstone formation then was studied by feeding the lithogenic diet from mo 7 to 8. At sacrifice, the incidences of gallstones, biliary lipids and tissue cholesterol levels were correlated with dietary history. The incidence of gallstones was 100% only in animals fed the alfalfa-corn diet from weaning to 3 mo. In addition, the feeding of the alfalfa-corn diet at mo 4–6 increased gallstone incidence from 65% to 86%. The lithogenic index of all groups was highest when the animals received only alfalfa-corn prior to the lithogenic stimulus. The activity of hepatic HMG-CoA reductase was elevated in animals fed alfalfa-corn from weaning to 8 mo, suggesting that this diet stimulates hepatic cholesterol synthesis, leading to increased biliary cholesterol secretion. It is concluded that previous nutritional conditioning affects the incidence of gallstones. The prairie dog is a useful model of cholesterol cholelithiasis, but the dietary history of the animals plays an important role in lithogenesis.  相似文献   

2.
Serum total cholesterol, high density lipoprotein (HDL) cholesterol, and triglyceride levels were studied in healthy male and female subjects consuming for one-week periods a diet of conventional food (CF) providing 42% of energy as fat, principally butter fat, and then in random order nutritionally complete, defined formula diets of moderate (32%) to very low (1%) fat content. Compared to CF, the formula with 32% of energy as corn oil lowered serum cholesterol by 25% and the ratio of total to HDL-cholesterol by 13%. Low (9%) and very low (1–3%) fat formulas reduced HDL-cholesterol by as much as 40%, raised the total: HDL-cholesterol ratio by about 20% and raised serum triglyceride levels by as much as 100%. When low and very low fat formulas were ingested for three weeks, these effects persisted although maximal responses occurred during the first week. These results demonstrated that a moderate fat formula diet with a high P/S ratio had a more favorable effect on serum lipid levels than various low fat formulas. Low fat conventional food diets should be studied in long-term controlled metabolic experiments before such diets are recommended to the general population for coronary heart disease or cancer prevention.  相似文献   

3.
The lipid concentration and fatty acid composition of the whole liver and of cultured hepatocytes isolated from the livers of rats fed ad libitum (fed), fasted for 24 hr (fasted), or fasted for 48 hr and then refed a fat-free, high carbohydrate diet for 48 hr (refed) was studied. Hepatocytes were maintained as monolayer cultures in serum-free, lipid-free media and their fatty acid composition was analyzed at 3, 24, 48, 72 and 96 hr. The livers of fed animals, as well as their hepatocytes, contained less total lipid than those from animals on either of the other dietary regimes. Livers of fasted animals had three times the amount of lipid found in the livers of fed animals, and the livers of refed animals contained five times the amount of lipid as the livers of fed animals (all based on mg lipid/g wet weight of liver). The fatty acid composition of hepatocytes after 3 hr of culturing was very similar to that of fresh liver when compared in each of the dietary regimes. However, while the fatty acid compositions of livers and hepatocytes from fed and fasted animals were similar, the pattern in liver of refed animals was quite distinct from that of the fed animals. In the fed and fasted animals palmitic acid (16∶0), stearic acid (18∶0), oleic acid (18∶1[n-9]), linoleic acid (18∶2[n-6]) and arachidonic acid (20∶4[n-6]) were the major fatty acids of the liver; in refed animals 16∶0, palmitoleic acid (16∶1[n-7]), 18∶0, 18∶1(n-9) andcis-vaccenic acid (the n-7 isomer of oleic acid) were the major fatty acids. During maintenance in culture the 18∶1(n-9) content of the hepatocytes increased in cells from livers of animals on all three dietary regimes. The polyunsaturated fatty acid content was similar in fresh livers and isolated hepatocytes in all samples when compared on the basis of μg fatty acid/mg of hepatocyte or liver protein. It was also found that the polyunsaturated fatty acid content of hepatocytes was remarkedly stable with time of culture when the cells were incubated in serum-free, lipid-free medium. Thus, isolated hepatocytes maintained in serum-free medium appear to be a possible system for the evaluation of the effects of prior nutritional status on fatty acid metabolism in the whole animal, not subject to hormonal and other somatic influences which often complicate the interpretation of such nutritional studies.  相似文献   

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5.
介绍了我国煤系常见共伴生矿物的种类及分布情况,重点分析了煤系高岭土、硫铁矿、石英岩类矿物、膨润土和硅藻土的加工利用方法,提出要充分利用开采煤矿的有利条件,采用新技术加快煤系常见共伴生矿物的开发和利用。  相似文献   

6.
7.
综述了炭黑、白炭黑等无机矿物做橡胶填料的发展历程、现状及展望,分析了无机矿物的补强机理。  相似文献   

8.
The purpose of this study was to propose a new dietary index to evaluate the nutritional quality of common dishes and diets: the index of nutritional quality per volume (INQV). In its expression, this index takes into account the nutrient density (amount of nutrient/1,000 g of diet) and the nutrient density per reference volume. The last one is the ratio between the recommended allowances of the nutrient and the volume that it is possible to consume during the day, when the diet is offered freely. Zinc was used as example in the analysis. A total of 14 dishes of habitual consumption in Chile were studied in relation to its consumption by 30 preschool children. The volume that children were able to consume was determined by differential weighing between the amount offered and the amount left on the dish, during a period of 180 days. The percentage of water and energy value were established by means of chemical analysis performed according to the AOAC, and the zinc concentration by atomic absorption spectrophotometry. The results of the INQV were then compared with those of the index of nutritional quality (INQ), which considers zinc density/1,000 kcal, and zinc and energy requirements. This comparison demonstrated that the INQV values were lower than those of the INQ in dishes with energy densities lower than 1.0 kcal/g. The opposite tendency was observed in the case of those dishes with energy densities higher than 1.0 kcal/g. The analysis herein presented demonstrates the usefulness of the INQV in diets which are voluminous and with low energy densities, commonly consumed by the low socioeconomic strata of developing countries.  相似文献   

9.

Background  

children affected by refractory epilepsy could be at risk of malnutrition because of feeding difficulties (anorexia, chewing, swallowing difficulties or vomiting) and chronic use of anticonvulsants, which may affect food intake and energy metabolism. Moreover, their energy requirement may be changed as their disabilities would impede normal daily activities. The aim of the present study was to evaluate nutritional status, energy metabolism and food intake in children with refractory epilepsy.  相似文献   

10.
Guatemala provides an example of epidemiological superposition, in which health problems typical of developed countries and developing countries are both observed. Nutritional deficiencies in some micronutrients like vitamin A and iron coexist alongside chronic diseases such as diabetes type II and cardiovascular diseases. The importance of black beans in the normal Guatemala diet is well known:70g per capita of black beans are consumed daily. Black beans are an important sources of protein and energy in the diet. They contain "lente" digestion carbohydrates and a high proportion of non-digested carbohydrates that may be fermented in the large intestine. Theses types of carbohydrates are associated with a low glycemic response, low serum cholesterol levels, and a decrease of colon cancer risk factors. These physiological effects may be related to colonic fermentation end products (propionic and butyric acids). Black beans also contain several antinutritional compounds (enzymatic inhibitors, haemaglutenins, saponins and phytic acid, etc.), some of them thermolabiles that are partially eliminated during culinary processes and may modify the nutritional quality of beans. Black beans play a crucial role in the etiology of several diseases in Guatemala.  相似文献   

11.
Coals high in carbonate minerals show abnormally high VM on dmmf basis. This abnormality has been shown to be due to the presence of iron carbonate. Effects of the presence of different carbonate minerals on VM have been estimated, and a formula is advanced for estimating VM on dmmf basis of a coal having a particular distribution of carbonate minerals: VM on dmmf basis = As analysed VM ? 0.1 Ash ? 1.3 CO2100 ? (MM + Moisture) × 100  相似文献   

12.
Physical activity is affected by nutritional modifications and, in turn, influences growth, cognition, social behavior, work performance and other functions. Studies in preschool children showed that: 1. A decrease in energy intake during four to seven days reduced the time allocated to energy-demanding activities and increased sedentary activities. 2. Children with mild weight deficit were more sedentary than well-nourished counterparts. 3. Children became more active when nutritional status improved. 4. A 10% reduction in energy intake reduced total energy expenditure by 15% without affecting weight gain nor basal metabolism. Studies of men working in non-mechanized agriculture showed that: 1. Dietary improvements led to faster salaried work, reduction of napping time and greater physical activity after work. 2. An increase in energy intake increased total daily energy expenditure, tending to maintain energy balance and relatively stable body weight within the cyclic variations of the agricultural year. 3. Food supplementation did not necessarily improve productivity. Other labor incentives without dietary improvements increased energy expenditure during working hours, which resulted in weight loss. In conclusion, good health and nutrition provide the biological basis for adequate physical activity that may improve cognitive development, social interactions, economic productivity and the quality of life of an individual or a population, but other incentives are required for the optimal expression of that biologic potential.  相似文献   

13.
利用热重分析仪研究了水蒸气气氛下霍林河褐煤焦和脱灰褐煤焦的气化动力学特性,并考察了脱灰前后褐煤焦孔结构的变化。结果表明:褐煤原焦气化反应速率在反应初始阶段(转化率30%)高于脱灰褐煤焦,但在反应后期低于脱灰焦,这是因为煤焦中灰分的脱除一方面去除了矿物质的催化作用,另一方面增大了煤焦的孔径,因而减小了气化剂的扩散阻力。灰层扩散控制的缩核模型可以描述褐煤焦水蒸气气化过程,而脱灰后褐煤焦水蒸气气化过程用均相模型可以很好地表示。  相似文献   

14.
Apigeninidin, a 3-deoxyanthocyanidin present in sorghum, was chemically synthesized and effectively purified by extracting impurities from aqueous 2 N HC1 into ethyl acetate. Apigeninidin (50mol) applied to filter paper disks inhibited the growth on agar plates of selected gram-positive bacteria (Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, andStreptococcus faecalis) and to a lesser extent gram-negative bacteria (Escherichia coli, Serratia marcens, andShigella flexneri). Apigeninidin was not mutagenic based on the Ames assay. The ability of apigeninidin to precipitate proteins from plant extracts could be physiologically important if it can be shown to bind to specific plant proteins.  相似文献   

15.
Our goal was to analyze the concordances and non-concordances of the nutritional classification in pregnant women and to evaluate their effectiveness when different BMI classification methodologies were applied. The study consisted of 314 adult healthy pregnant women in their first trimester, of socioeconomic status IV. In all of them, two nutritional classification criteria were applied: the integral nutritional diagnosis (IND) and different BMI reference values (Institute of Medicine, FAO/OMS, Frisancho, Bray, and Atalah). Kappa, concordance and nonconcordance, sensitivity, specificity, positive and negative predictive values were calculated. The highest frequency of concordance between IND and the analyzed classification criteria in comparing four and three nutritional categories was Frisancho's with the following results 89.2%, Kappa = 0.81 in the first case, and 91.4, Kappa = 0.84 in the second case. In deficit, the Bray and Atalah classification criteria were the highest sensitivities. In excess, FAO/ OMS, Frisancho, and Bray had a high sensitivity (1 - 0.99). Frisancho, in addition, had a high specificity with respect to FAO/OMS and Bray. Frisancho's classification criteria are the best choice for diagnosing adult pregnant women's nutritional status during the first trimester within population groups with these characteristics.  相似文献   

16.
Latin America is a region where countries have various levels of socioeconomic development. Thus, the living standards and health status of its people differ significantly in the midst of a mosaic of social, ethnic, cultural and economic realities. Social inequalities and extreme poverty determine significant differences, not only in the magnitude of health indicators, but also in the type of pathology prevalent. People in the high socioeconomic levels are affected by nutritional diseases characterized by excessive food intake, while people from the low socioeconomic levels are affected by undernutrition and its associated pathology. Undernutrition occurs fundamentally among the age groups at higher risk in the population segments with low income, low food intake, illiteracy and poor access to the health care and preventive medicine centers. Among families exposed to undernutrition, women are usually in worse condition than men. This is due to the long working hours and the increased nutritional requirements caused by frequent gestations and prolonged lactation. It is estimated that one fourth of newborns in Latin America are affected by low birth weight, which has been associated to adolescent mothers, their excessive physical work, anemia, low maternal pregestational weight, low weight gain during gestation, and frequent maternal infections. Nutritional anemia due to iron deficiency is highly prevalent among pregnant women in Latin America. In some countries, the prevalence of folate deficiency during pregnancy appears to have increased significantly in the past 15 years and is becoming a nutritional problem that needs preferential attention. Diets generally are inadequate and, in the case of pregnant and lactating women, usually deficient in calories, protein, iron and folic acid. It is urgent that the health and nutritional status of Latin American women of low socioeconomic condition be given special attention, particularly mothers during gestation and lactation. Otherwise, women will not be able to altogether fulfill their important role in the home and within the family, nor will they successfully participate in the economic development of their countries.  相似文献   

17.
The purposes of this study are to explore the mechanisms of Cu element in clinker burning and hydration processes and to make effective use of waste containing copper in cement production. The effect of CuO on clinker mineral composition, C3S polymorph and size, Cu element distribution and state, compressive strengths, hydration products, non-evaporable water quantity and hydration heat release rate was analyzed by XRD, SEM, DTA, isothermal heat-conduction calorimetry, etc. Results show that as the amount of CuO increases the formation and growth of C3S grain are accelerated, R C3S is gradually transformed into M3 and the content of C4AF increases; a small quantity of CuO increases the 3-day and 28-day strengths and the hydration degree of clinker, but excessive CuO has adverse effects. Those effects of CuO on clinker burning process are attributed to the formation of low-melting Cu2O and the dissolution of CuO in C4AF which decrease the formation temperature of liquid phase and increase its quantity. The effects on hydration process result from the combined action of the following factors: the induction period is prolonged; the hydration reactions in the initial and acceleration periods are accelerated.  相似文献   

18.
The type of diet formulation was considered in our study on the effects of wheat bran on some parameters obtained in a biological assay, for 28 days. Weanling, male Holtzman rats were divided in three groups. Two of them were fed ad libitum on diets containing 25% of wheat bran, prepared in two ways: balanced (FB) and conventional (FC). In the first case, the fiber source was added at the expense of every other ingredient, whereas in the second, only of starch. The control group received a wheat bran-free diet. Comparison among the groups showed the highest weight gain for group FB, and the lowest protein efficiency ratio (PER) for group FC. Fecal weight and the weight of the cecal contents were significantly higher for the test groups. Mean activity of the alkaline phosphatase from the jejunal mucosa was lower in group FB than in the other two. The activities of this enzyme in serum, were significantly higher for groups FB and FC. Serum cholesterol level was slightly lower for the group fed the balanced diet, than for the one receiving the conventional diet. Therefore, some parameters such as weight gain, PER, alkaline phosphatase activity of the intestinal mucosa, and serum cholesterol, were influenced by the type of diet formulation. Nevertheless, these results are not enough to substantiate a conclusive answer to the question: which diet formulation is more adequate for biological assays, when using wheat bran as a fiber source?  相似文献   

19.
Artificial weathering devices are used extensively by the plastics industry to aid in the prediction of the weatherability of plastic matrials. Correlations between the results of outdoor and artificial weathering, however, are poor for lack of control and understanding of the exposure variables in these devices. This work summarizs some of the results of an experimental program designed to analyze the effects of variables in artificial weathering on the preoperies of selected commercial plastics. In addition to the presentation of data establishing the importance of each of the variables in artificial weathering, a discussion of the significance of these data with regard to the selection of optimum exposure cycles is given. Furthermore, some new approaches are proposed with regard to obtaining inproved correlations between the results of outdoor and artificial exposure. Model calculations based on the proposed approaches yield a surprisingly high degree of correlation between the two types of exposure.  相似文献   

20.

Background  

Western diets are considered acidogenic due to the high dietary acid load and a low intake of base-forming dietary minerals such as potassium, magnesium or calcium. In the present study we investigated the effect of a multimineral supplement (MMS) rich in alkaline minerals on acute and chronic regulation of acid-base balance with the pH of blood, urine and saliva as potential surrogate markers.  相似文献   

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