Effect of essential amino acids on mouse embryo viability and ammonium production.
(33/363)
PURPOSE: To examine the effect of essential amino acids concentrations on mouse embryo development. METHODS: Mouse embryos were cultured in medium with different concentrations of essential amino acids and development to the blastocyst stage and viability assessed. Ammonium production resulting from medium breakdown and amino acid metabolism by embryos were also assessed. RESULTS: Reducing the essential amino acid concentration significantly increased blastocyst development and cell numbers. Lowering the essential amino acid concentration decreased ammonium production in the medium. CONCLUSIONS: Culture media for the development of preimplantation embryos should have a reduced essential amino acid concentration to facilitate embryo development. (+info)
Protein requirements of man: comparative nitrogen balance response within the submaintenance-to-maintenance range of intakes of wheat and beef proteins.
(34/363)
Sixteen young male students participated in two studies designed to determine the nitrogen balance response to beef or stone-ground, whole wheat protein over the submaintenance-to-maintenance range of protein intake. The objective of the studies was to evaluate the relative capacities of these proteins to meet the minimum protein needs in young adult males. A modified Latin-square design was used to allocate subjects to the four 15-day metabolic balance diet periods in each study. The last 10 days were used for fecal nitrogen determination and the last 5 days for evaluation of urinary nitrogen excretion. The diet periods were separated by a 4-day break period and began with 1 day on a "protein-free" diet. The levels of protien (N times 6.25) intake tested were 0.2, 0.3, 0.4, and 0.5 g/kg body weight/day in the beef study. The results have been compared with those obtained in a previous similar study with egg protein. The regression of estimated "true" nitrogen balance (Y) (mg N/kg/day) on nitrogen intake (X) (mg N/kg/day) was: Y equals 0.51(plus or minus 0.08)X minus 41.9(plus or minus 4.6) for beef and Y equals 0.27(plus or minus 0.06)X minus 33.6(plus or minus 5.0) for whole wheat protein. The amounts of beef and wheat proteins estimated to be requried to support body nitrogen balance in 97.5% of the population supplied 96 and 178 mg N/kg/day, respectively. The relative protein value of beef and wheat proteins, in comparison with egg protein, was 78 plus or minus 12 and 41 plus or minus 10, respectively. It is concluded that the variations in dietary protein quality should be taken into account in assessing the protein adequacy of diets for individuals and population groups. (+info)
Evaluation of various protein sequences on the nutritional carry-over from gestation to lactation with first-litter sows.
(35/363)
First-litter sows and their progeny were used to evaluate the interaction effects of three gestation crude protein levels (9, 13, or 17%) and two lactation protein levels (12 or 18%) on sow reproduction and litter performance. Diets were formulated to contain the desired protein level by altering the ratio of corn and soybean meal. Daily rations of 1.82 kg were individually fed during gestation and were offered ad libitum to the sows by 7 days postpartum. Litters were equalized to eight pigs each by 1 week of age and held constant to weaning (28 days). Sows fed the 9% protein diet gained less during gestation than those fed the 13 or 17% protein diets. Progeny parturition data were similar for the three gestation protein levels. Sows fed the 18% protein lactation diet and their litters performed similarly in regards to feed intake and progeny performance regardless of previous gestation protein level, while those sows fed the 12% protein lactation diet had decreasing lactation weight losses, but increasing fed intakes and litter gains as the level of gestation protein increased from 9 to 17%. There were significant gestation by lactation protein level sequence interactions on sow feed intakes and litter gains, suggesting a nutritional carry-over effect from gestation to lactation. Sows fed the 17% protein gestation diet had the greatest tissue buffer while those fed the 9% protein gestation diet had the least. These results further demonstrate that dams fed a 9% protein gestation diet perform similarly to those fed higher gestation diets, if the lactation dietary protein level is adequate to meet the lactation amino acid requirements. (+info)
Amino acid composition of the diet in a region of Southern Tunisia.
(36/363)
As part of a study of the effects of lysine supplementation of wheat products in Southern Tunisia one qualitative and four quantitative surveys of food consumption were carried out. The average diet provided 7.1 MJ (1,670 kcal), 42 g of protein and 1,280 mg of lysine per person per day. The overall dietary protein thus supplied only 31 mg of lysine/g of protein, or about 56% of the level recommended by the FAO/WHO Expert Committee on Protein Requirements. Addition of lysine to all wheat products to a final effective concentration of 0.2% would raise the dietary lysine level to 45 mg/g protein, or 82% of the FAO/WHO recommended level, at which time threonine would become limiting. Irrespective of whether the FAO/WHO pattern of 1973, breast milk, cow's milk, whole egg or a modification of the FAO pattern of 1957 was used to assess the quality of the protein in the diet, lysine was the first, and threonine the second limiting amino acid (except in comparison with breast milk, which showed tryptophan as the second limiting amino acid). In no case did there appear to be any problem with the sulfur-containing amino acids. (+info)
Free amino acids in plasma, red blood cells, polymorphonuclear leukocytes, and muscle in normal and uraemic children.
(37/363)
BACKGROUND: The aims of this study were to investigate free amino acid (AA) concentrations in plasma, red blood cells (RBC), polymorphonuclear granulocytes (PMN), and muscle, sampled at the same time, in normal and uraemic children. METHODS: Twelve apparently well-nourished chronically uraemic children (five females) aged a mean of 9.4+/-4.8 (range 1.7--17.7) years and 13 age-matched normal children were studied. Venous blood and muscle samples for AA analyses were taken simultaneously after an overnight fast. RESULTS: The intracellular AA patterns in the three cellular compartments were qualitatively similar, but the absolute intracellular concentrations were higher in muscle than in PMN, which had higher values than in RBC. The AA patterns in plasma, RBC, PMN, and muscle in the uraemic children have many similarities; typical features being low branched-chain AA (BCAA), tyrosine, and serine concentrations and variably high concentrations of some non-essential AA. Among the individual AA, there were only few correlations between their concentrations in the three cell compartments. CONCLUSIONS: The lack of correlation between the concentrations in RBC, PMN, and muscle for most of the AA indicates that there is no close association in the same subject between individual free AA concentrations in various types of cells, presumably because of differences in metabolism and function. Consequently, one should be cautious in assuming that AA concentrations, determined in RBC or PMN, reflect the concentrations in muscle cells. Therefore, these preliminary observations do not support the hypothesis that RBC and PMN AA analysis can be considered as a suitable alternative to muscle AA determination. (+info)
Sulfur in human nutrition and applications in medicine.
(38/363)
Because the role of elemental sulfur in human nutrition has not been studied extensively, it is the purpose of this article to emphasize the importance of this element in humans and discuss the therapeutic applications of sulfur compounds in medicine. Sulfur is the sixth most abundant macromineral in breast milk and the third most abundant mineral based on percentage of total body weight. The sulfur-containing amino acids (SAAs) are methionine, cysteine, cystine, homocysteine, homocystine, and taurine. Dietary SAA analysis and protein supplementation may be indicated for vegan athletes, children, or patients with HIV, because of an increased risk for SAA deficiency in these groups. Methylsulfonylmethane (MSM), a volatile component in the sulfur cycle, is another source of sulfur found in the human diet. Increases in serum sulfate may explain some of the therapeutic effects of MSM, DMSO, and glucosamine sulfate. Organic sulfur, as SAAs, can be used to increase synthesis of S-adenosylmethionine (SAMe), glutathione (GSH), taurine, and N-acetylcysteine (NAC). MSM may be effective for the treatment of allergy, pain syndromes, athletic injuries, and bladder disorders. Other sulfur compounds such as SAMe, dimethylsulfoxide (DMSO), taurine, glucosamine or chondroitin sulfate, and reduced glutathione may also have clinical applications in the treatment of a number of conditions such as depression, fibromyalgia, arthritis, interstitial cystitis, athletic injuries, congestive heart failure, diabetes, cancer, and AIDS. Dosages, mechanisms of action, and rationales for use are discussed. The low toxicological profiles of these sulfur compounds, combined with promising therapeutic effects, warrant continued human clinical trails. (+info)
Renewable and nonrenewable resources: amino acid turnover and allocation to reproduction in Lepidoptera.
(39/363)
The allocation of nutritional resources to reproduction in animals is a complex process of great evolutionary significance. We use compound-specific stable isotope analysis of carbon (GC/combustion/isotope ratio MS) to investigate the dietary sources of egg amino acids in a nectar-feeding hawkmoth. Previous work suggests that the nutrients used in egg manufacture fall into two classes: those that are increasingly synthesized from adult dietary sugar over a female's lifetime (renewable resources), and those that remain exclusively larval in origin (nonrenewable resources). We predict that nonessential and essential amino acids correspond to these nutrient classes and test this prediction by analyzing egg amino acids from females fed isotopically distinct diets as larvae and as adults. The results demonstrate that essential egg amino acids originate entirely from the larval diet. In contrast, nonessential egg amino acids were increasingly synthesized from adult dietary sugars, following a turnover pattern across a female's lifetime. This study demonstrates that female Lepidoptera can synthesize a large fraction of egg amino acids from nectar sugars, using endogenous sources of nitrogen. However, essential amino acids derive only from the larval diet, placing an upper limit on the use of adult dietary resources to enhance reproductive success. (+info)
Food intake regulation in the weanling rat: effects of the most limiting essential amino acids of gluten, casein, and zein on the self-selection of protein and energy.
(40/363)
The effects of altering the quality of the dietary protein source on the self-selection of protein and energy by the weanling rat simultaneously offered a choice of two diets differing only in protein concentration were tested. The protein-energy selected was measured when the first limiting amino acid lysine was added to gluten; when lysine, methionine, or the first four limiting amino acids were added to gluten or to casein; or when the nutritional quality of zein was altered by manipulation of the content of tryptophan, lysine, or the four most limiting amino acids. The additions of lysine to gluten caused a decrease in the protein-energy selected and an increase in growth rate of the weanling rat. However, improving the amino acid balance of casein or zein did not have this effect. It was concluded that the selection of protein and energy by weanling rats is not related to the nutritional quality of the protein fed. (+info)