摘要:

Feeding a fat-free diet for 3 weeks decreases the activity of ascorbate:ferricytochrome b5oxidoreductase and increases NADH:monodehydroascorbate oxidoreductase in rat liver microsomes. Contrary to Vmax, the apparent Km for monodehydroascorbate of the first enzyme was not depressed. The activity of ascorbate:ferricytochrome b5oxidoreductase is increased by incubation with microsomal lipid extract, thus showing that the loss of activity results from dietary-induced changes of microsomal fatty acid composition.

ISSN:0250-6807    

DOI:10.1159/000176815

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The present study was performed in order to quantitate the uptake and excretion of a number of metabolic substrates by the sheep uterus as well as the fetus during the fed and fasted states within the same animals. 5 dated Suffolk sheep were studied initially at least 7 days after surgical placement of catheters in the fetal umbilical artery and vein, as well as the uterine veins and maternal artery. During the fed state and after 5 days of complete maternal fasting, measurements were made of uterine and umbilical blood flow by the steady-state anti-pyrine method, and the concentrations of whole blood glucose, oxygen, ammonia, 23 amino acids and plasma urea nitrogen were assessed. The results indicate that free amino acids and glucose comprise the major substrates required by the fetal lamb during both the fed and fasted states. While a number of amino acids changed in concentration in both the maternal and fetal circulations, few amino acids demonstrated a significant change in uptake in either the umbilical or uterine circulations. Similarly, no changes were observed in the uptake of oxygen by either the fetus or the uterus, while glucose consumption by the fetus decreased substantially with a concomitant increase in urea production. Consumption of both glucose and oxygen by the uteroplacenta remained unchanged during fasting. Leucine is one of several amino acids which is metabolized to a significant extent within the uteroplacenta, and theoretically may play a role in modulating glucose metabolism within the placenta and fetus.

ISSN:0250-6807    

DOI:10.1159/000176816

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The rate of albumin synthesis has been estimated in hepatocytes prepared from groups of rats maintained on diets of different protein content. These diets were fed either ad libitum or at 50% restriction of ad libitum consumption. The data show that the physiological capacity of hepatocytes to synthesize albumin varies with dietary intake. Albumin production by cells prepared from animals fed ad libitum was directly related to the protein energy:total energy ratio of the food. Restricting consumption of the control diet to 50% of ad libitum intake did not reduce albumin synthesis rates, and similar restriction of the low protein diets ameliorated some of the depression in albumin production observed in hepatocytes isolated from animals fed the same diets ad libitum. The results are discussed with reference to the occurrence of hypoalbuminaemia in children with protein-energy malnutrition.

ISSN:0250-6807    

DOI:10.1159/000176817

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The aim of the present study was to gather information on the utilisation of methionine sulphoxide as a source of methionine in the rat, and to find out where and to what extent reduction of methionine sulphoxide takes place. Carcass analysis of rats fed methionine sulphoxide and cystine as the only sulphur-containing amino acids showed that methionine had been formed. This is taken as evidence for reduction and utilisation of methionine sulphoxide in rats. Enzymatic reduction of methionine sulphoxide in different rat tissues was not detected using various reducing agents and assay conditions. Bacteria were found to reduce methionine sulphoxide, with eventual secretion of methionine into the medium. The reduction was stereospecific as only L-methionine-l-sulphoxide was reduced. Weight gain and content of methionine sulphoxide in blood plasma and intestine were similar in rats fed in the presence or absence of antibiotics, indicating that bacteria in the intestine were not responsible for the utilisation of methionine sulphoxide in the rat.

ISSN:0250-6807    

DOI:10.1159/000176818

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

In experiments with male wistar rats the influence of dl-α-tocopherol as well as dl-γ-tocopherol on both the respiration of liver mitochondria and membrane lipid peroxidation has been investigated. For a test period of 8 weeks the animals were fed isoenergetic diets containing either no vitamin E or 46 mg d-α-tocopherol equivalents/kg diet as dl-α-tocopherol (60 ppm) or dl-γ-tocopherol (480 ppm). The diets contained 6 % of a synthetic triglyceride mixture rich in polyunsaturated fatty acids (about 60%). The measurements of the P/O ratios and corresponding respiratory control index (RCI) values for several substrates (α-ketoglutarate, malate/glutamate, succinate) indicated that under vitamin E-deficient conditions the mitochondria showed an increased respiratory intensity accompanied with an elevated lipid peroxidation. The oxidative phosphorylation itself was not affected. These deficiency symptoms could be normalized by the applied amounts of both tocopherols. In this respect dl-γ-tocopherol showed a more distinct bioactivity than previously proposed. Based on the investigated parameters we calculated for dl-γ-tocopherol an average bioactivity of 28% compared to that of dl-α-to

ISSN:0250-6807    

DOI:10.1159/000176819

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

In the present study insulin and C-peptide responses to oral glucose as well as C-peptide to insulin ratios and relations were evaluated in 10 nondiabetic obese female subjects with reactive hypoglycemia and in 10 age- and weight-matched controls. Insulin levels and incremental areas did not differ significantly in the two groups, whereas C-peptide concentrations and incremental areas were significantly higher in the obese group with reactive hypoglycemia. C-peptide to insulin molar ratio increments after glucose load as well as relations between incremental areas of the two peptides were significantly higher in obese subjects with reactive hypoglycemia than in controls. Our results suggest that B-cell response to oral glucose as well as insulin uptake by the liver in obese subjects with reactive hypoglycemia are greater than in controls.

ISSN:0250-6807    

DOI:10.1159/000176820

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The effects of excess dietary cystine on the cholesterol and protein contents of rat plasma lipoproteins are described. 5 % L-cystine was added to a semisynthetic diet containing 23% casein and 0.05% cholesterol, to the same diet enriched with 1 % cholesterol or containing tristearin instead of lard. Rats were fed the diets during 2 months. The addition of cystine led to an increase in the plasma cholesterol level of the rats fed with the basal diet (from 0.92 to 1.56 mg/mi). But it produced a reduction of this level in cholesterol-fed rats (from 1.71 to 1.49 mg/ml). These different changes in the total plasma cholesterol level are explained by the specific effects of cystine on each lipoprotein: whatever the diet, cystine supplementation reduced the chylomicron and VLDL cholesterol contents and increased that of LDL (especially LDL2: density 1.040–1.063) and HDL. This study allowed us to compare 2 conditions which lead to hypercholesterolemia but which have opposite effects on hepatic cholesterogenesis: the supplementation of the same basal diet with 1 % cholesterol or 5% cystine. In cholesterol-fed rats, the major part (49%) of plasma cholesterol was found in the chylomicrons and VLDL while the LDL2 cholesterol content was low (0.07 mg/ml plasma). Conversely, cystine-fed rats had a low chylomicron and VLDL plasma content (both enriched in apoprotein E), whereas up to 33% of the plasma cholesterol were carried by LDL2. Thus the production of LDL2 in cholesterol and cystine-fed rats could be related to hepatic cholesterogenesi

ISSN:0250-6807    

DOI:10.1159/000176821

出版商:S. Karger AG    

年代:1984

数据来源: Karger