PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “AMINO ACID MIXTURES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed1972

Physiological studies on Vitreoscilla stercoraria.

Vitreoscilla stercoraria ATCC 15218 was studied to elucidate some of its physiological characteristics. The initial optimal pH for the organism was found to be 7.5 to 7.7. The characteristics of the growth curve of the organism showed that its growth in shake cultures is by increasing trichome number up to approximately 15 hr and by increasing trichome length after 15 hr. Nutritional studies indicated that it is auxotrophic for biotin, thiamine, and l-arginine, and it appears to be an obligate amino acid utilizer because only protein hydrolysates or known amino acid mixtures would support growth.

Amino Acids↗
PubMed1984

Treatment of congenital hyperammonemias.

A rapid recognition of congenital hyperammonemia, a clear diagnostic workup and institution of a combined treatment without delay, by restriction of nitrogen supply, adequate caloric supply, substitution of missing metabolites, and use of alternate routes of nitrogen excretion will help to control hyperammonemic crises and improve the prognosis. For long-term treatment the use of essential amino acid mixtures and perhaps of antiserotoninergic agents is needed.

Amino Acid Metabolism, Inborn Errors↗
PubMed1999

Oral amino acids stimulate muscle protein anabolism in the elderly despite higher first-pass splanchnic extraction.

Muscle protein synthesis and breakdown and amino acid transport were measured in 7 healthy young (30 +/- 2 yr) and 8 healthy elderly (71 +/- 2 yr) volunteers in the postabsorptive state and during the oral administration of an amino acid mixture with L-[ring-(2)H(5)]phenylalanine infusion, femoral artery and vein catheterization, and muscle biopsies. Phenylalanine first-pass splanchnic extraction was measured by adding L-[ring-(13)C(6)]phenylalanine to the mixture. In the postabsorptive state, no differences in muscle amino acid kinetics were detected between young and elderly volunteers. Phenylalanine first-pass splanchnic extraction was significantly higher in the elderly (P < 0. 003) during ingestion of amino acids, but the delivery to the leg increased to the same extent in both groups. Phenylalanine transport into the muscle, muscle protein synthesis, and net balance increased significantly (P < 0.01) and similarly in both the young and the elderly. We conclude that, despite an increased splanchnic first-pass extraction, muscle protein anabolism can be stimulated by oral amino acids in the elderly as well as in the young.

Administration, Oral↗
PubMed2002

Pentoxifylline acutely reduces protein catabolism in chronically uremic patients.

BACKGROUND: We investigated the ability of pentoxifylline, a drug with hemorheological actions known to block tumor necrosis factor-alpha (TNF-alpha) release, to modulate whole-body protein kinetics in undialyzed patients with chronic uremia. METHODS: Leucine rate of appearance (Ra) from proteolysis and leucine oxidation, a marker of net protein loss, were determined by infusing l-[1-13C]leucine and using the reciprocal pool model for calculations. RESULTS: Intravenous infusion of pentoxifylline in the postabsorptive state (1 mg/kg within 3 hours) decreased the intracellular leucine Ra from proteolysis by -16% +/- 4% versus -3% +/- 2% of saline (P = 0.02) and leucine oxidation by -16% +/- 4% versus +4% +/- 2% of saline (P = 0.003). Combined infusions of pentoxifylline and a balanced amino acid mixture (0.2 mg/kg/min) decreased whole-body proteolysis by -53% +/- 7% versus -26% +/- 6% of amino acid infusion alone (P = 0.02). Circulating levels of TNF-alpha and TNF-alpha soluble receptors (sTNF-Rs) were elevated (P < 0.001) in patients compared with healthy controls. Pentoxifylline infusion did not significantly affect TNF-alpha levels, but decreased sTNF-Rs both in the postabsorptive state and during hyperaminoacidemia. CONCLUSION: Pentoxifylline acutely decreased whole-body proteolysis in chronically uremic patients. Potential explanations for these pharmacological effects may include downregulation of the TNF-alpha system or other mechanisms related to the rheological action of the drug (eg, increased amino acid or insulin delivery to target cells).

Amino Acids↗
PubMed2002

Methionine supply to growing steers affects hepatic activities of methionine synthase and betaine-homocysteine methyltransferase, but not cystathionine synthase.

The effects of supplemental methionine (Met), supplied abomasally, on the activities of methionine synthase (MS), cystathionine synthase (CS) and betaine-homocysteine methyltransferase (BHMT) were studied in growing steers. Six Holstein steers (205 kg) were used in a replicated 3 x 3 Latin square experiment. Steers were fed 2.6 kg dry matter daily of a diet containing 83% soybean hulls and 8% wheat straw. Ruminal infusions of 180 g/d acetate, 180 g/d propionate, 45 g/d butyrate, and abomasal infusion of 300 g/d dextrose provided additional energy. An amino acid mixture (299 g/d) limiting in Met was infused into the abomasum to ensure that nonsulfur amino acids did not limit growth. Treatments were infused abomasally and included 0, 5 or 10 g/d L-Met. Retained N (20.5, 26.9 and 31.6 g/d for 0, 5 and 10 g/d L-Met, respectively) increased (P < 0.01) linearly with increased supplemental Met. Hepatic Met, vitamin B-12, S-adenosylmethionine and S-adenosylhomocysteine were not affected by Met supplementation. Hepatic folates tended (P = 0.07) to decrease linearly with Met supplementation. All three enzymes were detected in hepatic tissue of our steers. Hepatic CS activity was not affected by Met supplementation. Hepatic MS decreased (P < 0.01) linearly with increasing Met supply, and hepatic BHMT activity responded quadratically (P = 0.04), with 0 and 10 g/d Met being higher than the intermediate level. Data from this experiment indicate that sulfur amino acid metabolism may be regulated differently in cattle than in other tested species.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2002

De novo synthesis of amino acids by the ruminal anaerobic fungi, Piromyces communis and Neocallimastix frontalis.

Anaerobic fungi are an important component of the cellulolytic ruminal microflora. Ammonia alone as N source supports growth, but amino acid mixtures are stimulatory. In order to evaluate the extent of de novo synthesis of individual amino acids in Piromyces communis and Neocallimastix frontalis, isotope enrichment in amino acids was determined during growth on (15)NH(4)Cl in different media. Most cell N (0.78 and 0.63 for P. communis and N. frontalis, respectively) and amino acid N (0.73 and 0.59) continued to be formed de novo from ammonia when 1 g l(-1) trypticase was added to the medium; this concentration approximates the peak concentration of peptides in the rumen after feeding. Higher peptide/amino acid concentrations decreased de novo synthesis. Lysine was exceptional, in that its synthesis decreased much more than other amino acids when Trypticase or amino acids were added to the medium, suggesting that lysine synthesis might limit fungal growth in the rumen.

Amino Acids↗
PubMed1981

Late nonstructural 100,000- and 33,000-dalton proteins of adenovirus type 2. II. Immunological and protein chemical analysis.

For an immunological analysis of the late adenovirus type 2 nonstructural 100,000-dalton (100K) and 33K proteins, we prepared antisera against sodium dodecyl sulfate-denatured, gel-purified 100K and 33K proteins. These antisera were tested for potential cross-reactivity, since according to a previous report (Axelrod, Virology 87:366--383, 1978) these two proteins exhibit extensive amino acid homologies. However, immunoprecipitations of 100K and 33K proteins, as well as a sensitive immune replica technique, did not reveal any immunological relationship between these proteins. Therefore, using fingerprint peptide analysis, we investigated the structural relationship between 100K and 33K proteins labeled with a 14C-amino acid mixture or with [14C]proline after digestion with trypsin. We detected only minor, if any, amino acid homologies, indicating that the 100K and 33K proteins are not structurally related.

Adenoviridae↗
PubMed1981

Effects of dietary protein or amino acids in the perfusion medium on amino acid metabolism in perfused adult rat liver.

To elucidate the response of amino acid metabolism in the liver to dietary protein and plasma amino acids, the livers of adult rats fed on diet containing 10% (control) or 3% (low-protein) egg protein for 3 weeks were perfused for 120 min with amino acid-free medium in Experiment 1 or medium containing an amino acid mixture simulating that in plasma in Experiment 2. During perfusion about 40% of the free amino acids were lost from the liver in Exp. 1, and about 30% in Exp. 2. During this period, in Exp. 1 the releases of free amino acids and urea into the medium were 140 mumol and 2.52 mg, respectively, in the control group and 207 mumol and 1.10 mg respectively, in the low-protein group. Thus release was greater than decrease in free amino acids in the liver. Essential amino acids, particularly lysine and branched chain amino acids, were released preferentially. The results suggest that the amount of breakdown of liver protein in the two groups was similar, but that the nitrogen was mainly released as free amino acids in the low-protein group, and as urea in the control group. On the contrary, in Exp. 2 the amount of nitrogen released from the liver was comparable to the decrease in amino acids in the liver, and the releases of urea were also less, being 1.83 mg in the control group and 0.54 mg in low-protein group. The results show that amino acid metabolism in the liver is greatly affected by the nutritional state of the animal and the amino acid content of the perfusion fluid.

Amino Acids↗
PubMed1979

[Nutritional requirements and parenteral feeding].

1. The nutritional needs of man are governed by the law of the minimum (structural and protective substances) and the isodynamic rule (exchangeability of various energy carriers) There is a tendency to abandon the traditional concept of requirement as an absolute value (g or mg/day) and replace it by 3 graded parameters (minimal - lowest acceptable - desirable supply). Today nutrient density is of utmost importance in the planning and evaluation of food formulas, i.e. the content per 1000 kcal or per MJ = mega-Joule. 2. The metabolism of nutrients proceeds (simplified) in 3 phases: a) digestion (comminution); b) coordination and conversion in intermediary metabolism; c) direct use in synthetic or oxidation processes. This creates problems of balance, of co-ordination and regulation. In the phases b and c the same conformities apply for oral and parenteral feeding. 3. Particular features of parenteral feeding: Exclusion of intestinal flora, limited capacity of uptake by the circulation and, especially, the lowered capacity of biochemical regulatory mechanisms (homeostasis) in patients requiring parenteral feeding necessitate optimal coordination of supply and effective needs. Attempts to comply are made by continuous infusions, diversification of the substrate supply and optimisation of the different components. In principle, priority is given to those nutritional factors which promote anabolism (tissue formation) and counteract catabolism (tissue breakdown). 4. Example: protein needs. --Recapitulation of quantitative and qualitative requirements regarding protein and amino acid supply. --Discussion of the different recommendations and guidelines. --Discussion of the criteria for evaluation and the composition of an optimal amino acid mixture (nitrogen balance and growth as criteria). 5. Conclusions for parenteral feeding. The supply of amino acids should be on the generous side because there is an increased requirement in the "acute phase" and in convalescence. The amino acid composition should correspond to the pattern of a high quality food protein. The E/T ratio (essential AS versus total AS supply) is an indicator. The value proposed as a guideline is E/T approximately 3. However, an exaggerated amino acid cosmetic is not recommended. 6. Diagnostic problems. In the interest of optimal results of treatment, foremost attention should be given to the detection of latent deficiency states and the improvement of nutrition at large. The list of indicators given in the figures should be consulted whenever there is evidence of undersupply. The so-called "hospital malnutrition", as described in recent studies, should obviously not occur.

Amino Acids↗
PubMed1984

[Determination of 2-6-diaminopimelic acid in samples of bacteria isolated from the rumen of sheep using an automatic amino acid analyzer].

The method of the use of the HD 1200-E automatic amino acid analyzer for the separation of amino acids was modified for the determination of 2-6-diaminopimelic acid (DAPA) as a bacterial marker, besides the other amino acids in the acid hydrolyzates of samples of bacteria isolated from the rumen of sheep. The reproducibility of the determination of DAPA in a standard amino acid mixture found in the tests corresponded with the reproducibility of the determination of the other amino acids as indicated by the manufacturer of the apparatus. The lower limit of DAPA determination sensitivity is between 2 and 5 nmol. In samples of bacteria isolated from rumen wall, from feed particles of rumen contents and from rumen fluid, different contents of nitrogen and DAPA were obtained; this is ascribed to the different proportions of bacterial species in the bacterial populations having different functions.

Amino Acids, Diamino↗
PubMedDate not supplied

Glutamine supplementation for low-birth-weight and very low-birth-weight infants.

Glutamine is a conditionally essential amino acid for low-birth-weight (LBW) and very low-birth-weight (VLBW) infants by virtue of its ability to serve as a primary respiratory fuel for proliferating cells, a carrier of nitrogen between tissues, maintain acid-base balance, promote the growth and integrity of the gastrointestinal tract and promote immunologic responses. While adults can synthesize glutamine in the muscles and brain to meet essential requirements under normal state of health, the LBW and VLBW infants may not be able to do so since the enzymes (glutamine synthetase and glutaminase) activities are low. In addition, these infants are under stress due to conditions like the respiratory distress syndrome, acid-base imbalances, infections, and inadequate immunologic responses. Current amino acid mixtures and formula preparations are inadequate to meet the needs of these infants for this amino acid. Thus supplementation of parenteral and enteral nutrition with glutamine would be beneficial.

Dietary Supplements↗
PubMed1976

Effect of ammonia via prepyriform cortex on regulation of food intake in the rat.

Studies were made on whether ammonia, which is an obligatory intermediate of amino acid metabolism, depresses the food intake of rats fed a low-casein (basal) diet containing imbalanced amino acid mixtures (imbalanced diets). Bilateral lesions in the prepyriform cortex caused normalization of food intake of rats fed amino acid-imbalanced diets, confirming the work of Leung and Rogers (Am. J. Physiol. 221:929-935, 1971). Unlike normal rats, animals with prepyriform cortical lesions consumed as much of a diet containing 3% NH4Cl as they did of the basal diet. However, like normal rats, they rejected a diet containing a mixture of keto acids. Unilateral injection of NH4Cl into prepyriform cortical areas reduced the food intake to a greater extent than injection of NaCl into these areas or injection of NH4Cl into other parts of the brain. These results suggest that ammonium ions influence the appetite through their effect on prepyriform cortical areas.

Amino Acids↗
PubMed1977

[Modification of urea-N and creatinine levels using need-adapted amino acids during parenteral nutrition in patients under intensive care].

The present retrospective study concerns two sub-groups of patients having normal serum creatinine levels, adequate 24-hour urine volumes and no pathological changes in the serum or urine osmolarity. There are differences in the initial values of the serum urea nitrogen, the higher (with almost 60 mg%) being already in the azotemia range. Both sub-groups received 100 g of an amino acid mixture adapted to requirements in addition to comparable parenteral nutrition. This did not lead to non-physiological changes in urea nitrogen or any of the other parameters measured in either of the groups. The findings obtained allow the following conclusions to be drawn: Parenteral administration of a quantity of essential and non-essential amino acids adapted to requirements did not bring about a rise in urea nitrogen in either the patients with normal or raised urea nitrogen values. Hence there are not grounds for assuming that in the post-operative or post-traumatic phase the use of a mixture of essential amino acids is necessary to reduce potentially occurring azotemia.

Adult↗
PubMed1975

Amino acid transport in placental slices. Mechanism of increased accumulation by prolonged incubation.

The accumulation of alpha-aminoisobutyric acid by placental slices is increased dramatically upon prior incubation of the slices in amino acid-free, buffered saline. This increase is inhibited by inhibitors of protein synthesis and is accompanied by an increased V for the transport process. While alternative explanations are discussed, these data suggest that the incubation effect may be mediated through an increase in the number of available transport sites which are synthesized during the incubation period. Incubation with an amino acid mixture diminishes the increase as well as general protein synthesis, suggesting that a reduced availability of amino acids may initiate compensatory changes in the synthesis of cellular transport proteins.

Amino Acids↗
PubMed1982

Interconversion of leukotrienes catalyzed by purified gamma-glutamyl transpeptidase: concomitant formation of leukotriene D4 and gamma-glutamyl amino acids.

The reversible conversion of leukotriene C4 to leukotriene D4 and of the latter to leukotriene E4 were studied with highly purified homogeneous preparations of gamma-glutamyl transpeptidase, dipeptidase, and aminopeptidase M. The conversion of leukotriene C4 to leukotriene D4, catalyzed by gamma-glutamyl transpeptidase, is significantly more rapid when carried out in the presence of an amino acid mixture a closely approximating that found in blood plasma and is accompanied by gamma-glutamyl amino acid formation. Because gamma-glutamyl transpeptidase is bound to the external surface of cell membranes and thus is readily accessible to plasma amino acids, it appears that conversion of leukotriene C4 to leukotriene D4 under physiological conditions is coupled with the formation of gamma-glutamyl amino acids. The apparent Km value for leukotriene C4 in this reaction is about 6 X 10(-6) M, a value close to that found for glutathione. Conversion of leukotriene D4 to leukotriene C4 is effectively catalyzed by gamma-glutamyl transpeptidase in the presence of relatively low concentrations of glutathione. The conversion of leukotriene D4 to leukotriene E4 is catalyzed much more rapidly by renal dipeptidase than by renal aminopeptidase M. Incubation of leukotriene E4 with gamma-glutamyl transpeptidase and glutathione leads to formation of a compound with the properties of gamma-glutamyl leukotriene E4; this reaction is analogous to that shown previously in which gamma-glutamyl cystine is formed by transpeptidation between glutathione and cystine.

Aminopeptidases↗
PubMed1987

Parenteral nutrition with an amino acid solution containing a mixture of dipeptides. Evidence for efficient utilization of dipeptides in man.

Ten healthy human subjects received parenteral nutrition consisting of 80 g of a dipeptide-amino acid mixture and 900 carbohydrate calories infused over a period of 12 h, and then fasted for another period of 12 h. The dipeptides included in the mixture were: glycyl-L-glutamine, glycyl-L-tyrosine, glycyl-L-leucine, glycyl-L-isoleucine, and glycyl-L-valine. Parenteral nutrition with the dipeptide-amino acid mixture was without any adverse reaction in any of the subjects. The urinary excretion of the 5 dipeptides during parenteral nutrition ranged between 1 and 2% of the amount infused. Plasma concentrations of dipeptides during parenteral nutrition, which ranged from 8-96 microM reflected their plasma half-lives. Glycyl-L-glutamine had the longest half-life, glycyl-L-leucine and glycyl-L-tyrosine the shortest half-lives. During parenteral nutrition there were increases in plasma amino acid concentrations including those of glutamine and tyrosine. Discontinuation of parenteral nutrition resulted in the disappearance of dipeptides from plasma, and the dissipation of increased plasma amino acid concentrations. In conclusion, the present results show efficient utilization of glycyl-dipeptides as substrates for parenteral nutrition in man. The results further show that the structure of amino acids in the C-terminal position has a significant influence on the metabolism of dipeptides.

Adult↗