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At least 19 recordsLinked to original sources
PubMed1976

Biochemical selection systems for mammalian cells: the essential amino acids.

The essential amino acid requirement of cultured mammalian cells can be satisfied by 19 amino acid derivatives. This finding (a) confirms the results of animal nutritional studies and (b) identifies 19 essential amino acid derivatives and should permit the isolation of a new class of auxotrophic mutants. Five naturally occurring auxotrophic markers have been detected in this survey; namely, inability to utilize cystathionine and citrulline in Chinese hamster ovary (CHO) cells, inability to metabolize citrulline by HTC+hepatoma cells, and confirmation of Eagle's observation that KB cells can utilize homocystine in place of methionine or cystine and D-cystine in place of L-cystine.

Amino Acids↗
PubMed1976

Response to lactating dairy cows to abomasal infusion of amino acids.

Essential amino acids most limiting for milk production and/or secretion of milk protein were determined in five trials involving infusion of amino acids into the abomasum of lactating Holstein cows. Cows were fed corn-based rations containing 10.7 to 11.5% crude protein (dry matter basis) which exceeded standard allowances for energy. All trials were Latin-square designs with 9-day periods. The abomasal infusion of methionine had no effect on secretion of milk, milk protein, or milk fat. Lysine infusion resulted in 16% of the total response in yield of milk protein that was obtained with either the 10 essential amino acids or sodium caseinate while infusion of lysine and methionine together accounted for 43% of the total response. This suggested that lysine and methionine were first and second limiting, or co-limiting, for secretion of milk protein when rations consisting primarily of corn, corn silage, and alfalfa-grass hay were fed. The primary effect was on content of milk protein rather than milk yield. In general, amino acid infusions had no effect on feed intake, milk fat, and nonprotein nitrogen content of milk. Little change occurred in concentrations in plasma of other amino acids when lysine and methionine were infused together. When concentrations were lowered, indicating increased protein synthesis, changes were too small to be statistically significant.

Abomasum↗
PubMed1978

Comparison of the effects of keto acid analogues and essential amino acids on nitrogen homeostasis in uremic patients on moderately protein-restricted diets.

Comparisons of isonitrogenous supplements (1.2 g N) of essential amino acids and five keto acid analogues with four essential amino acids were made in seven patients with stable chronic renal failure (creatinine clearance, 4.6 to 16 ml/min) on moderately protein-restricted diets (4.60 to 7.8 g N per day). Full nitrogen balance data on the four patients who have already completed studies lasting 24 weeks are presented. No benefits of keto acid over amino acid supplements were observed. Two transient episodes of hypercalcemia occurred during keto acid treatment. There was no improvement of renal function with keto acids. Also, no carry-over effects were seen after keto acid treatment. It is concluded that any beneficial effects of keto acids in patients with chronic renal failure are only likely to occur in those taking a diet of less than 30 g protein daily.

Adult↗
PubMed1977

Albumin synthesis in cultured hempatoma cells. Regulation by essential amino acids.

The effects of essential amino acids on albumin synthesis by a mouse hepatoma cell line have been investigated. The amino acids tested were tryptophan, phenylalanine, histidine, isoleucine and leucine. Cellular rates of synthesis (molecules albumin/cell per min) were determined from rates of [3H]leucine incorporation into immunoprecipitable albumin in the culture medium. The effects of amino acids on albumin synthesis fall into three distinct groups. The concentration of tryptophan producing half-maximal synthesis is 4 micronM. The corresponding concentration for leucine is 100 micronM. Histidine, phenylalanine and isoleucine were very similar, the half-maximal concentrations being approximately 15 micronM. The concentrations of amino acids producing half-maximal synthesis correlate directly with the amino acid composition of albumin. The levels of these essential amino acids necessary to saturate albumin synthesis have been compared with amino acid levels in normal plasma.

Albumins↗
PubMed1978

Intracellular free amino acids in muscle tissue of patients with chronic uraemia: effect of peritoneal dialysis and infusion of essential amino acids.

1. Free amino acids were determined in the plasma and in the muscle tissue of 14 patients with chronic uraemia; eight were not on dialysis and six were having regular peritoneal dialysis. The concentration of each amino acid in muscle water was calculated with the chloride method. 2. In both groups of patients there were low intracellular concentrations of threonine, valine, tyrosine and carnosine, and high glycine/valine and phenylalanine/tyrosine ratios. Both groups of patients had increased amounts of 1- and 3-methyl-histidine in plasma and in muscle water. 3. The non-dialysed patients had low intracellular concentrations of lysine, and the dialysed patients had high intracellular concentrations of lysine, isoleucine, leucine and of some of the non-essential amino acids. 4. After peritoneal dialysis for 22 h, the plasma concentration of several amino acids decreased but the intracellular concentrations of most amino acids did not change significantly. 5. Intravenous administration of essential amino acids and histidine during the last 4 h of dialysis increased in muscle the total free amino acids, the ratio of essential to non-essential amino acids and the valine and phenylalanine concentrations. 6. The results demonstrated that the plasma and muscle concentrations of several amino acids are grossly abnormal in chronic uraemia. Non-dialysed and dialysed patients exhibit important differences, especially in the intracellular amino acid patterns. Infusion of essential amino acids may result in enhancement of protein synthesis.

Amino Acids↗
PubMed1977

[Culex pipiens fatigans: labeling of tissues of normal and infected (Plasmodium cathemerium) females after feeding on tritiated amino acids (author's transl)].

Normal and infected Culex females were fed 11 different amino acids. These substances were labeled with tritium and each was given separately in glucose solution. After the uptake the marker appears first in crop, cardia and midgut. Later on the other tissues get labeled more or less. It seems that the labeling follows a characteristic pattern for each amino acid. Essential amino acids are taken up intensively; for example leucine not only in the midgut epithelium but also in the ovary and the fat body. There is nearly no uptake of the non-essential amino acids alanine, glutamic acid and DOPA by the tissues of both groups of females. These amino acids are only seen in the midgut area and not in the other tissues. In infected mosquitos the uptake of the essential acid, phenylalanine, corresponds only to that of a non-essential amino acid.

Amino Acids↗
PubMed1976

Responses of laying hens to a low-protein diet supplemented with essential amino acids, L-glutamic acid and/or intact protein.

1. Three sequential experiments, each lasting 8 weeks, were carried out on 576 singly-caged light hybrids. 2. In experiment 1 egg production was 84% using a conventional control diet, 61% with a basal low-protein diet, and 79% with the basal diet supplemented with 10 essential amino acids+L-glutamic acid (GA). 3. In experiment 2 supplementation with lysine and methionine (L+M) alone increased egg production significantly from 54 to 72%, compared with 83% with the conventional diet. 4. In experiment 3 egg production was 55% with the basal diet, 71% with the basal diet+L+M, 75% with a diet containing 141 g protein/kg+L+M, and 73% with the conventional diet. 5. In all three experiments supplementation with GA alone either gave no significant response or a depression in production. 6. Daily intakes of 1-24 g nitrogen as non-essential amino acids and 13 to 14 g total crude protein per bird resulted in good egg production. Supplementation of the basal diet with L+M resulted in a daily intake of 413 mg methionine/bird day which was considered adequate, and a daily intake of 710 mg lysine which was considered slightly inadequate.

Amino Acids, Essential↗
PubMed1978

Evaluation of essential amino acids and keto acids in uremic patients on low-protein diet.

The effectiveness of a mixture of five analogues of essential amino acids and the remaining four essential amino acids as compared to a preceeding treatment period of the nine essential amino acids was evaluated in 16 chronic uremic patients fed a low-protein diet. During amino acid analogues supplementation, there was a tendency for blood urea nitrogen to fall whereas creatinine did not change. Serum phosphate decreased in most patients, whereas serum calcium rose in some subjects. Protein metabolism, as judged by serum transferrin, Clq, C3c, total complement activity, was improved. Furthermore, the concentrations of prealbumin and retinol-binding protein, which are elevated in uremia, showed a further increase that might favor a vitamin A intoxication.

Adult↗
PubMed1975

Effects of essential amino acids on central neurons.

Effects of eleven essential amino acids ejected by means of electrophoresis through five barrel glass microelectrodes on the frequency of extracellularly recorded action potentials of brain cells were determined. Data were collected on 129 cells from four different parts of the brains of 22 female hooded rats anesthetized with a mixture of chloralose and urethan. Eleven cells were tested in the cerebral cortex, 57 in the thalamus, 33 in the zona incerta, and 28 in the lateral hypothalamus. Of the eleven amino acids tested, cells of the zona incerta and lateral hypothalamus appear to be the most responsive and increases in discharge frequency were observed for all the amino acids except lysine and cystine. Cystine seems to be unusual in that it is the only amino acid tested which produces a decrease in the spontaneous discharge frequency. Cells of the cerebral cortex were not considered responsive in terms of the criteria of this study and displayed relatively high thresholds to all the essential amino acids. These results indicate some differential sensitivity of certain cells of the brain to essential amino acids which might be related to the centrally mediated anorexia which develops when rats are fed disproportionate amounts of these same amino acids in the diet.

Amino Acids↗
PubMed1975

Plasma amino acids and protein levels in chronic renal failure and changes caused by oral supplements of essential amino acids.

1. Plasma amino acids and six proteins have been measured in patients with chronic renal failure receiving low protein diets before and after oral supplementation with essential amino acids. 2. All the patients on low protein diets had a lower percentage of essential amino acids in their plasma than normal subjects but after supplementation, plasma levels increased significantly with minimal increase in non-essential amino acids or urea nitrogen. 3. Mean levels of plasma transferrin, complement C3 and globulin Gc were lower and plasma prealbumin higher in patients than in normal subjects. Plasma complement C4 and albumin were not different from normal. 4. Seven out of nine patients who tolerated the supplementation showed a significant increase in plasma transferrin, prealbumin and complement C3 but not in complement C4, globulin Gc or albumin. 5. Correlations between the percentage of essential amino acids and each of plasma transferrin, prealbumin and complement C3 and also between several of the plasma proteins further substantiate their value in the assessment of dietary intake in chronic renal failure. 6. The value of amino acid supplementation on low protein diets in chronic renal failure is discussed in relation to these observations.

Adult↗
PubMed1977

Influence of essential amino acids and keto acids on protein metabolism and the anaemia of patients on chronic intermittent haemodialysis.

Ten patients were treated with 10 g essential amino acids per day orally; 9 patients received 9.5 g of a mixture of essential amino acids (Lys, Thr, Try, His, Tyr) and ketoanalogues of Ile, Leu, Phe, Val, Met per day and a control group of 11 patients received no supplementation. All patients were on a liberal food intake amounting to 1g protein/kg body weight and 31 kcal/kg body weight daily. Before and three months after the beginning of supplementation the following parameters were measured: serum concentrations of albumin, transferrin, urea, creatinine, blood haemoglobin content and haematocrit, activities of the enzymes delta-aminolevulinic acid dehydrase and porpho-bilinogen desaminase, and globin synthesis in peripheral red blood cells. After treatment with either essential amino acids or keto acids a significant stimulation of globin synthesis occurred. None of the other parameters was altered. It is concluded that in well-nourished patients supplements of essential amino acids or keto acids are ineffective.

Amino Acids, Essential↗
PubMedDate not supplied

Evidence for an anabolic action of essential amino acid analogues in uremia and starvation.

Nitrogen-free analogues of essential amino acids, when administered with those essential amino acids for which analogues are ineffective or unavailable, exert three actions that may be beneficial in protein-deficient or protein-intolerant subjects. First, they bring about an increase in the concentrations of essential amino acids in the blood at the expense of the concentrations of certain non-essential amino acids, notably alanine and glutamine. This effect is most readily demonstrated in children with congenital defects of the urea cycle enzymes, but can also be seen during daily therapy of adults with portal-systemic encephalopathy. Second, these compounds promote nitrogen balance through their suppressive effect on urea synthesis (an effect not attributable to re-utilization of ammonia derived from urease action in the gut). This action is demonstrable in obese subjects who are already conserving nitrogen maximally at the end of a prolonged fast and can also be shown in the first week of fasting when the branched-chain keto acids alone are administered. In both situations, improved nitrogen conservation persists long after the analogues are metabolized, suggesting enzyme adaptations. In chronic uremics, nitrogen balance can be maintained in some (but not all) patients on very low nitrogen intakes. Third, these mixtures may delay or reverse the progressive decline in glomerular filtration rate characteristic of chronic renal failure in some cases: thus, for example, 5 of 6 patients taken off chronic dialysis have maintained lower serum urea concentrations without evidence of protein malnutrition for periods of 2-24 months.

Amino Acids↗
PubMed1978

Nitrogen retention of young men who consumed selection patterns of essential amino acids at a constant nitrogen intake.

Six patterns of essential amino acids were devised to represent different sources or combinations of protein based on a daily intake of 6.0 g of nitrogen from these sources. In each diet, cereals furnished 70% and a specially designed amino acid mixture 30% of the total nitrogen. Nitrogen retention of young men who consumed amino acids equivalent to combinations of rice and soy or egg and potato did not differ from the pattern of egg, and these patterns were superior to a combination of rice and wheat; egg also was superior to corn plus beans and wheat plus milk. Relative amounts and proportions of essential amino acids could be modified without depressing nitrogen retention until one amino acid became limiting or the pattern became imbalanced. Therefore, more than one pattern of amino acids should be recognized as useful for adult human subjects; both minimal and total amounts of essential amino acids need to be considered.

Adult↗
PubMed1978

Prophylactic trials for stroke in stroke-prone SHR. (3) Amino acid analysis of various diets and their prophylactic effect.

This study confirmed again that high protein diet feeding decreased the incidence of stroke, and high fish protein diet did attenuate severe hypertension but high soybean protein diet did not affect the hypertension. Dietary amino acid analyses indicated that increases in total amino acids, essential amino acids and nonpolar amino acids but not acid or basic amino acids were significantly related to the reduction of stroke incidence. Among essential amino acids, lysine, threonine, isoleucine, and leucine contents were inversely related to stroke incidence, and methionine content was significantly related to the dietary antihypertensive effect of high protein diets. The prophylactic effect of high protein diets may be ascribed to some amino acid constituent.

Amino Acids↗
PubMed1992

Taurine: an essential amino acid to prevent cholestasis in neonates?

OBJECTIVE: To review the evidence that taurine can prevent cholestasis in neonates. DATA SOURCES: MEDLINE and EMBASE searches were conducted to identify both animal and human data regarding taurine's role in bile acid conjugation and liver disease (key terms: taurine, children less than two years old). STUDY SELECTION: Emphasis was placed on human data supplemented by relevant animal data. DATA SYNTHESIS: Taurine appears to more effectively conjugate bile acids than glycine, and the end-products of conjugation are more soluble. Taurine deficiency may increase glyco-conjugates of bile acids and result in cholestasis. Although the cause of neonatal cholestasis probably is multifactorial, there are data indicating that adequate taurine may prevent cholestasis in neonates. CONCLUSIONS: Taurine should be considered an essential amino acid for neonates and should be included in total parenteral nutrition solutions for these patients.

Amino Acids, Essential↗