Nutrition and metabolism最新文献

Plasma cholesterol esterifying activity has been measured in guinea pigs fed either a control diet or the same diet supplemented with 1% cholesterol. The extent of esterification was found to be similar in the cholesterol-fed and control guinea pigs and somewhat lower than in rats. The initial rate of esterification was also of the same magnitude as that found in rats and humans, and unaffected by dietary cholesterol if autologous plasma was used as substrate. However, LCAT activity from cholesterol-fed guinea pigs was significantly higher than that of control plasma when acting on either control or cholesterol-fed substrate. This suggests that dietary cholesterol increases the amount (or activity) of LCAT but that the substrate is unsuitable or that a necessary cofactor is present in limiting amounts. Heat treatment of guinea pig plasma seems to alter substrate availability to varying degrees. The implications of these findings in relation to substrate specificity and cofactor requirements of guinea pig LCAT are discussed.

During the fermentation of animal protein by Lactobacillus plantarum, highly volatile and less volatile antimicrobial substances are formed. The antimicrobial effect of the latter fraction depends on the content of alpha-hydroxyacids in the fermentation product. These acids were isolated from the fermentation mixture and identified by chemical methods. The main components are racemic forms of lactic, alpha-hydroxyisovaleric and alpha-hydroxyisocaproic acids.

Male Wistar rats were fed a purified basal diet with 20% lard and corn oil (3:1), sunflower oil, poppyseed oil, low-erucic rapeseed oil from Brassica napus, cultivar Tower, or mixtures of these oils, for 1 or 26 weeks. None of the hearts exhibited lipidosis at 1 week. At 26 weeks, the level of serum triglycerides was higher in rats fed the mixture of lard and corn oil than in those fed only vegetable oil, and the incidence of cardiac necrosis and fibrosis was higher in rats fed the rapeseed oil than in the other animals. Cardiac phospholipids in rats fed the rapeseed oil contained an elevated level of omega 3 docosahexaenoic acid, particularly in phosphatidylethanolamine. Poppyseed oil exhibited properties similar to those of sunflower oil, was absorbed as well as olive oil, and appeared to be a promising oil for human consumption.

Three groups of 33 90-day-old female Sprague-Dawley rats were fed, ad libitum, the following diets for 2 weeks before breeding. Diet 1 (D1) contained 20% protein from casein, diet 2 (D2) had the same level of protein from Tower rapeseed (Brassica napus) protein concontrate (RPC) and diet 3 (D3) was the same as D2 with a zinc supplement (70 mg/l) in the drinking water. From each group 6 animals were killed before breeding and 5-9 animals were killed at 1 and 2 weeks of gestation and post-partum. From each rat, blood, thyroids, liver and femur were collected for the determination of zinc, copper, iron, manganese, calcium and magnesium. As a measure of the reproductive performance, body weight, number of pups in the uterus or delivered live or dead, and gestations days before parturition were recorded. The pups were examined for obvious deformities and also analysed for the above mineral elements by atomic absorption spectroscopy. In group D2, levels of zinc in maternal serum, liver, femur and in the pups were significantly lower than the comparable levels in the other two groups. The zinc supplemented RPC-fed group did not show the anorexia experienced by the unsupplemented group and there was neither a significant difference between reproductive performances of groups D1 and D3 nor was there any significant difference between the zinc levels determined. It was concluded that the toxic symptoms caused by RPC feeding was attributable to zinc deficiency probably caused by the high phytate level in the RPC.

The role of zinc in some metabolic functions in man was investigated in 14 healthy male volunteers with primarily high or low serum zinc. In all the subjects, results of laboratory tests reflecting blood picture, metabolism of carbohydrates, fats and proteins and thyroid function as well as serum calcium and phosphate levels varied within the normal range. Significant differences between the subjects classified by serum zinc were found in alpha1-globulins. Serm thyroxins, effective thyroxine ratio and the immunoglobulins IgA showed a tendency to lower levels in subjects with low serum zinc. Substitution with zinc sulphate resulted in an increase of alpha 1-globulins, serum thyroxine and effective thyroxine ratio, and a decrease of albumin. Other tests remained by the therapy. The results suggest that there is a relationship between zinc and some metabolic functions in healthy subjects without symptoms of zinc deficiency.

Metabolic reactions during long-time intravenous infusion of glucose in dosages according to basal energy requirements of man were investigated. Infusion of 0.2-0.4 g glucose/kg body weight/h led to the typical behaviour of blood glucose with an initial peak and a subsequent steady state. The steady state was dose-dependent and always higher than the starting value. Insulin always rose significantly with increasing scattering of the individual values with higher glucose loads. With 0.1 g glucose/kg/h, the steady state of blood glucose, after a minimal initial peak, was lower than the starting value, and no change of insulin in the peripheral venous blood could be observed. Free fatty acid levels initially always decreased, but rose again under low glucose loads (0.1 and 0.2g/kg/h). In all experiments, with an increase of insulin, a decrease of serum potassium was found. Sodium, calcium, bilirubin, creatinine and urea-N did not show any typical changes.

Adenine nucleotide content and adenine nucleotide transport were evaluated in rats deficient in essential fatty acids (EFA) and in control rats. ADP uptake by EFA-deficient mitochondria was altered in a manner similar to the alteration produced by treatment of normal mitochondria with uncoupler. The uptake of ATP by EFA-deficient mitochondria was more rapid than that of normal mitochondria, but similar to that of normal mitochondria treated with uncoupler (DNP). Both uptake of ADP and uptake of ATP by EFA-deficient mitochondria were atractyloside sensitive. Total adenine nucleotide content of liver mitochondria from EFA-deficient rats was similar to that of liver mitochondria from control animals, but the content of ATP in EFA-deficient mitochondria was significantly higher than that of normal mitochondria. There was a negative correlation between the concentration of linoleic acid in total mitochondria lipids and ATP content of mitochondria.

10 patients with primary, endogenous hypertriglyceridemia (type IV hyperlipoproteinemia) underwent three different isocaloric dietary regimes of 10 days duration each. The diets contained either 30, 43 or 79% of calories as carbohydrate with 20% of calories from protein. Analyses of insulin, blood sugar and free fatty acids were conducted on the last day of each dietary period, at frequent intervals. There were no differences in either fasting or diurnal blood sugars with the different diets. Insulin levels were positively correlated with the amount of carbohydrate in the diet and there was an inverse correlation between the carbohydrate contents of the diets and circulating free fatty acid levels during waking hours. Since glucose tolerance is maintained, and diurnal plasma lipid levels are lowest with the low fat regime, such diets may be advantageously used for patients with endogenous hypertriglyceridemia.

The enzyme activities of the isocitrate, glucose-6-phosphate and malate dehydrogenases and of malic enzyme in liver, of lactate dehydrogenase in serum, and of alkaline phosphatase in bone and serum were determined in early-weaned rats given different Mn supplies. The activities of malate dehydrogenase were reduced by 16 and 18% during suboptimum and deficient Mn supply, respectively, the values of alkaline phosphatase in serum and bone were elevated by 29 and 35%, respectively. The enzyme values of the glucose-6-phosphate and lactate dehydrogenases were elevated only during Mn deficiency (by 40 and 65%, respectively), while a suboptimum Mn supply had no noticeable influence on these enzymes. The activities of isocitrate dehydrogenase and of malic enzyme, which were described to be activated by Mn++ in vitro, did not respond in vivo to Mn deficiency.