Nutrition and metabolism最新文献

Short-term starvation in the obese induces metabolic acidosis and increased calciuria resulting in severe negative Ca balance. Oral administration of 5 g Ca-lactate daily is capable of correcting acidosis, reducing calciuria and providing the body with 650 mg Ca daily, thereby maintaining a positive Ca balance throughout the period of starvation. We therefore propose administering this amount of the preparation to obese individuals during starvation as a simple and cheap preventive measure against bone demineralisation.

N-acetyl-(14C)neuraminosyl-(alpha,2 leads to 3)lactose enzymatically prepared of CMP-NeuNAc and lactose by a particulate enzyme fraction from lactating rat mammary gland was applied orally to newborn rats and examined for uptake and distribution in relation to those of free N-acetyl-(14C)neuraminic acid. The neonates were allowed to stay with their mother before and during the incubation time up to 6 h. Within this time 70% of the given dose was excreted while 30% was retained in the body. (14C)NeuNAc-lactose activity appeared 1.5 h after application in blood, urine, and tissues and attained maximum values after 3 and 6 h, respectively. The highest uptake occurred in liver, spleen, and brain. The absorption of the trisaccharide was delayed by 30 min compared with free (14C)NeuNAc. The time courses of the curves show a slower but higher accumulation in the tissues suggesting a better utilization of the (14C)NeuNAc from (14C)NeuNAc-lactose or pecularities in the absorption of the trisaccharide by the organs.

Biotin deficiency was induced in newborn rats by feeding pregnant rats a biotin-deficient, avidin-rich diet. Signs typical of biotin deficiency are seen as soon as the young rat develops its fur. Deficiency of pyruvate carboxylase (PC) activity in the brains of the young animals (70%) is higher than has been reported before. The highest PC activity is found in the brain stem of control and biotin-deficient rats. Normally fed rats show, shortly after birth, a maximum in liver PC activity, which is absent in biotin-deficient animals. The biochemical changes observed in these rats seem to indicate that a specific deficiency of PC activity was induced as exemplified by hyperlactatemia and hypoglycemia and the absence of increased plasma concentrations of propionic acid and beta-methylcrotonic acid. This offers the possibility to use biotin deficiency in the rat as an animal model for patients with lactic acidosis in whom PC deficiency has been postulated.

Male rats suckled in large litters (more than 12 pups, group A) had significantly higher levels of spontaneous physical activity and temporarily increased food intake (g/100 g body weight) than male rats from small litters (less than 6 pups, group B). Females did not differ. Epididymal fat pads were significantly lighter in males in group A. The concentration of total lipids in the small intestine was significantly higher in females from group A, and the synthesis of lipids was higher in the animals of both sexes from group A. The synthesis of fatty acids in the intestines was significantly greater in both males and females from group A. Cholesterol concentration in the liver and carcass was the same in all groups. Cholesterogenesis was higher in the liver only in males from group B, and in the carcass in the animals of both sexes from group B.

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.

In normal weanling male rats, the intraperitoneal administration of zinc sulphate (ZnSO4) resulted in a decreased hepatic and an increased plasa concentration of vitamin A after 2 h. In an in vitro study, the vitamin A concentrations of liver homogenates were markedly increased when homogenized livers were treated with ZnSO4, ZnSO4, however, did not show any effect on plasma and liver concentrations of vitamin E. These results indicate that zinc may be specifically involved in mobilizing vitamin A from liver to the circulation of normal animals within a short period. The trace element, therefore, could be used only to treat cases of depressed vitamin A in plasma but also to treat hepatic toxicity from hypervitaminosis A.

Transcription was determined in liver chromatin from rats fed for 6 days, an optimal (20%) or suboptimal (3%) amount of high-quality protein. Transcription by Escherichia coli RNA polymerase (EC 2.7.7.6) was lower after prolonged incubation with chromatin from rats fed 3% as compared with 20% protein. Differences were detected in the transcripts of the two types of chromatin after analysis by sucrose density gradient centrifugation. But no measurable differences were found in the melting profiles at low ionic strength of the two chromatin preparations. Transcription per milligram chromatin DNA was 25-fold higher using E. coli RNA polymerase instead of rat liver RNA polymerase II. The use of UTP as radioactive precursor in the absence of ATP, GTP and CTP resulted in a low labelling of RNA. One [lambda32P]UTP nucleotide was incorporated/8 UMP nucleotides. The product obtained was sensitive to ribonuclease treatment. In the presence of ATP, GTP and CTP [lambda-32P]UTP nucleotide incorporation was reduced and that of UMP nucleotide was increased giving a ratio of 1:188.

Ascorbic acid mixed with the diet of guinea pigs achieved substantially higher maximum tissue concentrations of ascorbate than when ascorbic acid was administered orally once a day. A 0.5% w/w of ascorbic acid in the diet ensured a state close to maximal tissue steady-state levels of ascorbate. In guinea pigs fed a diet with a high content of saturated fatty acids or with 0.2% w/w of cholesterol, the highest rate of cholesterol transformation into bile acids and the lowest concentration of total lipids, cholesterol and triglycerides in blood serum and liver were found in the group fed a diet with 0.5% w/w of ascorbic acid as compared to the marginal-deficiency group and the group receiving 0.05% w/w of ascorbic acid in the diet. Maximal tissue steady-state levels of vitamin C are probably optimal for the guinea pigs' health.

The effects of treadmill exercise on hepatic cholesterogenesis and fecal steroid excretion were studied using male Wistar rats fed a commercial pellet ration. Exercise, in comparison with ad libitum or pair-feeding sedentary groups, caused the following significant changes: (i) a reduction in the concentration of plasma triglyceride, phospholipid and cholesterol; (ii) a reduction in liver weight; (iii) increases in hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity and incorporation of mevalonate into digitonin precipitable sterol; (iv) increases in excretion of neutral and acidic steroids into the feces; (v) the increase in lipoprotein lipase activity in the cardiac muscle, and (vi) the decrease in the concentration of carcass triglyceride but not of cholesterol. These data suggest that the mechanism responsible for the plasma cholesterol-lowering effect of exercise is attributable to an increase in exretion of fecal neutral and acidic steroids accompanied by an acceleration of cholesterol turnover in the body.

The dose relationship of hemiglobin iron absorption has been investigated in subjects with normal and depleted iron stores and was found to fit a linear regression in a bilogarithmic presentation of hemiglobin iron dose and iron absorption. Identical regression coefficients but different intercepts of regression were estimated for subjects with normal and depleted iron stores indicating a constant proportional increase of hemiglobin iron absorption in subjects with depleted iron stores in the full dose range of 0.10-50 mg hemiglobin iron.