Nutrition and metabolism最新文献

The effect of a carbohydrate-free protein-fat (PF) diet compared with a mixed diet (CPF diet) on the energy metabolism was studied in a changeover trial with mature sows. The PF diet contained two thirds of its metabolizable energy as protein and one third as fat; in the CPF diet the relationship was 3.5 carbohydrate: 1 protein: 0.2 fat. Under the conditions of undernutrition and neutral temperature nitrogen, carbon and energy balance were assessed as parameters according to the procedures of indirect calorimetry in four 24-hour measurements each for the gaseous exchange of the animals. At isocaloric supply of metabolizable energy, no differences were found in the N, C and energy retention. The mean heat production amounted to 23.6 MJ/day in both dietary groups. Also, no dietary influence could be observed with regards to the daily time pattern of heat production nor to the physical activity of the animals. Computation of the nutrient utilization on the basis of potential ATP formation resulted in a turnover of 304 mol ATP/day for the mixed diet and in 275 mol ATP for the carbohydrate-free diet. The discrepancy is discussed. Overall, the results show that an increased heat production, providing the possibility of an augmented loss of body energy, could not be induced by the carbohydrate-free protein-fat diet in the course of undernutrition.

The contamination of dietary fats and oils can have various origins: contamination of the raw materials that could not be eliminated by the industrial process; refining completely eliminates this type of contamination; contamination with one of the processing aids can occur if the process is not properly conducted; contamination with packaging materials will increase with the storage duration of the finished product (in the case of vinyl chloride monomer and styrene contamination); only the strict control and adequate choice of the materials and packaging conditions will allow complete elimination of this contamination type. The presence of small amounts of another fat (in vegetable margarines for instance) should also be mentioned although it is not a real contamination. The secondary reactions that may occur during the processing of dietary fats are primarily due to unwanted chemical reactions leading to the formation of fatty acid or native glyceride isomers (e.g. formation of geometric isomers during deodorization, formation of position isomers during hydrogenation). In the present stage of knowledge, it is fairly easy to avoid secondary reactions during deodorization, those that take place during hydrogenation are not yet under control, however.

The combined administration of follicle-stimulating hormone and testosterone to sexually mature male rats whose testes were in the early stages of damage from retinol deficiency did not prevent the continued degeneration of the germinal epithelium. It is concluded that the action of retinol on the testis is probably not mediated through, nor influenced by, the pituitary or steroid hormones.

140 adult hospitalized Thai patients were assessed for their nutritional status. The prevalence of protein-calorie malnutrition in these patients based on various parameters was as follows: 73.2% according to weight-height, 80.0% accroding to triceps skinfold thickness, 60.7% according to upper arm muscle circumference, 50.4% according to hair root morphology and 66.2% according to serum albumin level. These data reflected the disproportionate loss of the patients' body tissues. Severity of protein-calorie malnutrition was also detected by physical signs. Anemia and vitamin deficiencies were present in some of the patients. This study signifies that intensive nutritional management should be done to combat hospital malnutrition.

Changes in body composition have been studied in patients with ischemic heart disease over a 2-year period, commencing 3--12 months after a well-documented myocardial infarction. Findings have been related to diet, the exercise undertaken (random allocation of volunteers to high intensity and low intensity exercise programmes) and the recurrence of myocardial infarcation. When first recruited, subjects were not much more obese than other middle-aged men. In contrast with experience in the "healthy" middle-aged exerciser, compliance of postcoronary patients with the required regimen was uninfluenced by body build. Over the 2 years of observation, both high and low intensity exercise groups showed small losses of fat and gains of lean mass. It is suggested that these changes reflect responses to dietary regulation and an increase of physical activity rather than a specific effect of the prescribed effort; the potential advantage of the high intensity exercise programme was lost through a larger food intake. Patients who sustained a recurrence of their infarction had an average percentage of body fat, but a low excess weight and lean mass; although isometric exercise is not frequently implicated in the recurrence of an infarction, the development of muscle mass might be advantageous to patients who must continue to work in occupations that demand sustained isometric muscular activity.

Tyrosine and tryptophan have been assayed spectrofluorometrically in postmortem human brain areas of patients with Parkinson's disease treated orally with or without 3,4-dihydroxyphenylalanine (L-dopa) plus the peripherally acting decarboxylase inhibitor benserazide. Tyrosine as well as tryptophan decrease significantly after treatment with L-dopa, thus showing a competitive action of L-dopa to other aromatic amino acids on human brain uptake. It is suggested that some of the side effects of L-dopa treatment in Parkinson's disease are due to a disturbance in the brain and neural uptake of other, specially aromatic and branched-chain amino acids. An influence of L-dopa administration on protein synthesis also cannot be excluded.

The influences of dietary sunflower seed oil and lard on coronary flow rate and external left ventricular work were studied in the isolated Langendorff-perfused and working rat heart. For 1, 4 or 6 weeks, rats were fed diets containing 25--50% of the total digestible energy as fat, 23% as casein an 52--27% as starch. The coronary flow rate and the maximum left ventricular work of hearts of rats fed sunflower seed oil were higher than those of hearts of rats fed lard (about 15 and 10%, respectively). The maximum left ventricular work was achieved at a left ventricular filling pressure of 10--12 mm Hg: this value was not affected by the type of dietary fat. The effect of dietary fat on coronary flow rare is already seen after 1 week of feeding, and on left ventricular work after 4 weeks of feeding. Analysis of variance shows a positive relationship between the maximum left ventricular work and the amount of sunflower seed oil. It is concluded that dietary fats affect coronary flow rate and left ventricular work in the isolated rat heart. The increase in left ventricular work may be caused by an increase in contractility.

A role for calciferol in zinc homeostasis was investigated by radioisotope uptake and compartmental analysis techniques. cholecalciferol was injected into rats 4-5 days prior to radioisotopic study of rapidly exchangeable pools (< 4 h). Kidney, liver, and duodenum had significant increases in zinc uptake rates. Bone and skeletal muscle had significant decreases. No other tissues had significant differences. Compartmental analysis models generated by the SAAM-25 digital computer program suggested a decrease in the fractional tissue to plasma coefficient to be the mechanism for the observed changes in the serum zinc concentration and tissue zinc accumulation rates. It is not clear whether this is a specific effect of calciferol on zinc homeostasis or is a nonspecific response which may reflect some role for zinc in calciferol metabolism.

Urea synthesis was examined in experimental uremia using the isolated perfused rat liver in order to assure strict control of substrate (NH4Cl) presented to the liver. Acute uremia was created in female Sprague-Dawley rats by bilateral nephrectomy (n = 7) 48 h prior to studies. Chronic uremia (8--14 weeks) was produced by right nephrectomy and segmental infarction of the left kidney in 7 rats. At infusion rates of NH4Cl (8.3 mumol/min) which resulted in prehepatic perfusate ammonia levels approximately twice the previously described Km value, livers of chronically uremic rats had slightly higher rates of urea production than controls (controls: 0.41 +/- 0.03; chronic uremia: 0.54 +/- 0.04 mumol/min/g of wet liver weight; p less than 0.02). In acute uremia, urea production was higher (0.66 +/- 0.05 mumol/min/g) than in sham-operated rats (0.59 +/- 0.05 mumol/min/g) but the differences did not achieve statistical significance. Simultaneously performed taurocholate transport studies did not reveal significant functional differences between the livers of uremic and control animals. The data suggest that urea production by livers of uremic rats is increased when compared to that of control animals.