摘要:

The interrelationship and possible causality of polyamine synthesis and the transmethylation pathway in the growth-retarding effects of inadequate or excess dietary methionine was studied in young male rats. Feeding the rats for 2 weeks diets containing toxic concentrations of methionine had no effect on polyamine and S-adenosylmethionine metabolism in skeletal muscle, but resulted in markedly elevated concentrations of S-adenosylmethionine and S-adenosylhomocysteine and slightly decreased accumulation of spermine and RNA in the liver. These changes were accompanied by liver-specific stimulation of methionine adenosyltransferase and reduction of spermine synthase activities. Inadequate arginine feeding or supplementation of the diets with ornithine or excess arginine resulted in no apparent changes in tissue methionine or polyamine metabolism and did not alleviate the effects of varied dietary methionine supply. Inhibition of putrescine synthesis by supplementing the diets with 2-difluoromethylornithine did not modify the effects of toxic concentrations of dietary methionine. It is suggested that although hepatic spermine synthase is sensitive to excess methionine feeding, methionine toxicity is not mediated by defective polyamine metabolism.

ISSN:0250-6807    

DOI:10.1159/000177260

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

A significant impairment in growth rate, food efficiency and weight of the gastrocnemius muscle was observed in rats fed a raw legume as the source of protein compared to casein-fed animals. No appreciable differences in chemical composition of the carcass were found. The source of dietary protein did not influence the ratio protein/DNA, DNA concentration or protein-synthesizing capacity (RNA/protein). The slower weight gain of animals fed the legume diet was attributed to a lower muscle protein synthesis, mediated by a depression of muscle RNA activity (grams protein synthesized/gram RNA) rather than changes in myofibrillar protein breakdown. In contrast liver protein synthesis appeared to be slightly increased in the legume-fed animals.

ISSN:0250-6807    

DOI:10.1159/000177261

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Very-low-calorie diets ( < 500 kcal/day; VLCD) are widely used for the treatment of severe obesity. We report the effects of such diets, consisting of proteins only or proteins and carbohydrates (CH), on nitrogen balance and protein nutritional status of morbidly obese patients. Cumulative nitrogen loss, serum albumin, transferrin, prealbumin (PA) and retinol-binding protein (RBP) concentrations, and plasma amino acid profile were determined in two groups of obese patients: 5 subjects (3 women, 2 men: BMI 55.3 ± 2.2 kg/m2) subjected for 4 weeks to a protein VLCD (40 g protein + 2 g fat) and 7 others (4 women, 3 men: BMI 45.6 ± 2.8 kg/m2) received for the same length of time a protein + CH VLCD (34 g protein + 26 g CH). Nitrogen balance was determined weekly whilst plasma and serum variables were measured on days 0, 3, 5, 10,20 and 28 of treatment. Nitrogen balance did not significantly differ between the two groups of patients throughout the treatment. Serum PA and RBP concentrations decreased from day 5 and day 10, respectively, in both groups. Plasma amino acids showed a similar pattern in the protein and protein + CH groups. Alanine gradually decreased below baseline values; after a peak value on day 5, branched-chain amino acids (valine, leucine, isoleucine) returned to baseline values in both groups. In conclusion, in severely obese patients subjected to VLCD, nitrogen balance, labile protein concentrations and plasma amino acid profile are not significantly affected by adding CH to protein

ISSN:0250-6807    

DOI:10.1159/000177262

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Rats were fed for 8 weeks high fat diets containing 20% of either palm oil (PO) or linoleic-supplemented partially hydrogenated marine oil (PHMO). Hepatocytes were isolated from rats fasted overnight. Incubations were performed with albumin bound [10–14C] oleic acid and [14–14C] erucic acid, respectively, for 15 or 60 min. The cell viability was better than 90% after 60 min of incubation. The incorporation of radioactive metabolites into lipids of the cells and of the secreted products was determined. The uptake and channelling of 18:1 and 22:1 into various lipid classes in the hepatocytes were different, but were little influenced by the diets. Erucic acid disappeared more rapidly from the incubation medium than 18:1 at both incubation times and for both dietary groups, and was mainly incorporated into the hepatocyte triglycerides and found in the free fatty acid pool, whereas only small amounts of labelling were detected in the phospholipids. Oleic acid, however, was readily incorporated into both phospholipids and triglycerides, and little was found in the free fatty acid pool. For both the triglycerides and the free fatty acids more than 90% of the radioactivity was represented by the incubation fatty acid. Chain-shortened products were found in the phospholipids, especially after incubation with 22:1. The chain-shortening capacity was somewhat higher in the PHMO group, relative to the PO group. At both incubation times, the major part (80–90%) of the total radioactivity was found in the lipid-soluble fraction of the incubation medium, and for both groups 60–80% still as the original incubation fatty acid. 20–30% of the radioactivity was found in the triglycerides secreted from the cells. Phospholipids were secreted in minor amounts (1–5%). Water soluble products constituted 3–7% at 15 min of incubation, increasing to 10–12% at 60 min, highest when incubating with 22:1 and similar for both

ISSN:0250-6807    

DOI:10.1159/000177263

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Twenty-four male, 6- to 8-week-old Sprague-Dawley rats were fed one of two skim-milk-based diets or stock laboratory diet for 100–120 days to assess the effect of dietary and infused lactose on intestinal lymph lipids. One skim-milk-based diet had its lactose enzymatically hydrolyzed by commercial beta-galactosidase to its constituent monosaccharides galactose and glucose, while the second skim milk diet was unaltered. Serum triglycerides, but not serum cholesterol, were higher in the lactose- versus the glucose-/galactose-adapted rats at 90 days. There was no diet-associated qualitative difference in serum lipoproteins as analyzed by agarose gel electrophoresis. After the rats had consumed the diets for 100–120 days, 0.9% saline and 20% solutions of lactose, and equimolar mixtures of glucose/galactose, glucose and maltose were infused sequentially via a duodenal cannula, then intestinal lymph was collected via a mesenteric lymph duct cannula. the only significant difference was a 134% increase in lymph cholesterol, but not lymph triglyceride output, when lactose was infused into lactose-adapted r

ISSN:0250-6807    

DOI:10.1159/000177265

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Lactose synthetase (LS) is a complex of α-lactalbumin and N-acetylglucosamine galactosyl transferase (GT). LS is the rate-limiting enzyme in lactose biosynthesis. Lactose is the main osmotic component of milk and may thereby affect milk volume. Dietary protein inadequacy reduces milk volume and lactose content. The study investigates the role of LS activity in these phenomena. Lactating rats were fed adequate and inadequate amounts of protein of high (milk protein) and low (cereal protein) quality. After 14 days LS and GT activity of mammary tissue was measured. Milk volume and lactose content was determined. While GT activity was unaffected by diet, LS activity was reduced by low dietary protein quality. Addition of bovine α-lactalbumin to tissue incubates largely restored the reduced LS activities. Milk volume was affected in a parallel manner to LS activity. A highly significant positive correlation existed between LS activity and total lactose production (r = 0.794; p < 0.001). Dietary protein inadequacy indirectly reduces milk volume by means of a direct effect on the lactalbumin part of the LS complex and, subsequently, lactose biosynthesi

ISSN:0250-6807    

DOI:10.1159/000177266

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The effects of vitamin E on platelet function and erythrocyte membrane rigidity are extensively described. Little is known, however, about the vitamin E status in an obese population and about the effect of weight loss on it. This study evaluates the changes in vitamin E status during obesity treatment in 8 morbidly obese females. They received a protein-sparing modified fast (PSMF) diet for a period of 5 weeks; mean vitamin E supplementation did not exceed the recommended daily allowance (8 mg of α-tocopherol equivalents). During the investigated period plasma vitamin E levels increased (p < 0.02), while there was a slight decrease in plasma cholesterol. The rise in total tocopherol/total cholesterol ratio was highly significant (p < 0.002). Both the experimental design and the results are comparable with previously reported data in hypothalamic obese mice. It is, therefore, suggested that the hypothalamic obese mouse is a convenient animal model for the study of vitamin E nutritional status in obesity

ISSN:0250-6807    

DOI:10.1159/000177267

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The urinary and blood levels of riboflavin and erythrocyte glutathione reductase (EGR) activity and its stimulation with FAD (EGR-AC) were examined in preschool children suffering from either measles or other upper respiratory infections and matched controls. Patients showed significantly higher levels of urinary riboflavin (per unit creatinine), erythrocyte riboflavin and EGR activity and lower EGR-AC values. This trend reversed after treatment. Mobilization of riboflavin from a labile tissue pool during infections may produce artefactual changes in the biochemical indices of riboflavin status. It would also prevent tissue saturation despite supplementation.

ISSN:0250-6807    

DOI:10.1159/000177268

出版商:S. Karger AG    

年代:1987

数据来源: Karger