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Results for “AMINO ACID METABOLISM”

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At least 649 records · Page 36Linked to original sources
PubMed1977

[Protein and amino acid metabolism in laying hens receiving N-15 labeled casein. 6. Patterns of N-15 incorporation into the N fraction and amino acids of the follicles and residual ovaries].

4 experimental hens were fed labelled casein as sole protein source for a period of 6 days. The dietary nitrogen contained a 15N excess of 0.69 atom%. Hens 1 and 2 were slaughtered 2 days and hens 3 and 4 four days after receiving the last 15N' dose. 10 follicles with diameters more than 6 mm were investigated for their content of N, for the TCE-soluble portion of N (TCE=trichloracetic acid) and for the content of different amino acids in protein. The corresponding 15N' data were established and the same analyses were carried out with the residual ovaries. The mean proportion of the TCE soluble N fraction in the total amount of N was 90% in the follicles and 88% in the residual ovaries. The content of certain kinds of amino acids in follicular protein depends on the degree of maturity of the follicles. There were differences in the percentage composition of amino acids between the follicles and residual ovaries. The mean percentage of lysine contained in follicular protein was 7,2%, that in the residual ovaries 7,9%. Corresponding data for arginine were 6,9% and 7,9%, those for glutamic acid 11,5% and 13,8%, for glycine 3,1% and 5,7%, for alanine 5,0% and 6,1%, for methionine 2,8% and 1,7% and for cystine 3,7% and 2,4%. Less than half of the 15N' atom % and less than half of the percentage of 15N' in the total amount of N and of the amount of amino acids in both the follicles and the residual ovaries were found in the hens killed 144 hrs after the last 15N dose than in the hens slaughtered 48 hrs after the last 15N intake. The atom % of 15N' in the N contained in the amino acids serine, threonine, glutamic acid, proline and leucine decreased with the process of ageing of the follicles. On an average, 88% of the total quantity of 15N' contained in the follicle samples were found as amino acid N, while in the residual ovaries 90% were found.

Amino Acids↗
PubMed1987

Amino acid metabolism in Ancylostoma ceylanicum and Nippostrongylus brasiliensis.

Ancylostoma ceylanicum and Nippostrongylus brasiliensis decarboxylated most of the amino acids examined, but only a few at significant rates. The former nematode in general possessed higher activities. Striking differences between the two parasites were, however, noticed regarding the metabolism of some of the amino acids. For instance, while alanine followed by aspartate produced highest amounts of 14CO2 in the presence of A. ceylanicum, proline exhibited maximum decarboxylation in case of N. brasiliensis. Tyrosine and lysine, on the other hand, did not liberate detectable CO2 with either parasite. Likewise, although large number of amino acids underwent transamination with 2-oxoglutarate, only some of them elicited appreciable activity for any of the two parasites.

Amino Acids↗
PubMed2004

Amino acid metabolism in leg muscle after an endotoxin injection in healthy volunteers.

Decreased plasma amino acid concentrations and increased net release of amino acids from skeletal muscle, especially for glutamine, are common features in critically ill patients. A low dose of endotoxin administered to healthy volunteers was used as a human model for the initial phase of sepsis to study the early metabolic response to sepsis. Six healthy male volunteers were studied in the postabsorptive state. Blood samples from the forearm artery and femoral vein were taken during 4 h before and 4 h after an intravenous endotoxin injection (4 ng/kg body wt). In addition, muscle biopsies from the leg muscle were taken. Plasma concentration of the total sum of amino acids decreased by 19% (P = 0.001) and of glutamine by 25% (P = 0.004) the 3rd h after endotoxin administration. At the same time, muscle concentrations of the sum of amino acids and glutamine decreased by 11% (P = 0.05) and 9% (P = 0.09), respectively. In parallel, the efflux from the leg increased by 35% (P = 0.004) for the total sum of amino acids and by 43% (P = 0.05) for glutamine. In conclusion, intravenous endotoxin administration to healthy volunteers, used as a model for the initial phase of sepsis, resulted in a decrease in plasma amino acid concentrations. At the same time, amino acid concentrations in muscle tissue decreased, whereas the efflux of amino acids from leg skeletal muscle increased.

Adult↗
PubMed2006

Use of the flux model of amino acid metabolism of Escherichia coli.

A program implementing a flux model of Escherichia coli metabolism was used to analyze the effects of the addition of amino acids (tryptophan, tyrosine, phenylalanine, leucine, isoleucine, valine, histidine, lysine, threonine, cysteine, methionine, arginine, proline) to minimal medium or media lacking nitrogen, carbon, or both. The overall response of the metabolic system to the addition of various amino acids to the minimal medium is similar. Glycolysis and the synthesis of pyruvate with its subsequent degradation to acetate via acetyl-CoA become more efficient, whereas the fluxes through the pentose phosphate pathway and the TCA cycle decrease. If amino acids are used as the sole source of carbon, nitrogen, or both, the changes in the flux distribution are determined mainly by the carbon limitation. The phosphoenolpyruvate to glucose-6-phosphate flux increases; the flux through the pentose phosphate path is directed towards ribulose-5-phosphate. Other changes are determined by the compounds that are the primary products of catabolism of the added amino acid.

Amino Acids↗
PubMed1985

Protein and amino acid metabolism after severe cerebral trauma.

Fourteen patients (20-48 years) suffering from severe head injury were followed for changes in amino acid and protein metabolism during the first 8 days after trauma. All patients received a standardized intravenous nutrition containing 15.7 g of nitrogen per day and additional carbohydrates. Electrolytes, free water, and blood constituents were given as needed. Additional treatment included surgical decompression of space-occupying hematomas, high dose dexamethasone therapy, and controlled hyperventilation for at least 5 days. Gross changes of protein metabolism were observed particularly on the days 5 and 6. The duration and chronological sequence of these changes are different from those usually found in patients with multiple injuries.

Adult↗
PubMed1995

[The characteristics of amino acid metabolism in premature infants on different types of feeding].

Analysis of the free amino acids (AA) in a blood plasma of premature infants receiving kinds of baby food has allowed to reveal a feature of AA metabolism. A significant increasing of sum of the free AA and stable contents of aromatic AA have been found in blood of premature infants fed Prepiltti [correction of 'Prepilti'] that testified to adequacy of protein in Prepiltti [correction of 'Prepiltu'] to requirements of premature infants. Also it has been established different changes of concentration methionine and cystine in this group of the babies that confirms a hypothesis about immature of liver enzymes catabolizing a methionine.

Aging↗
PubMed2001

Distribution of key enzymes of branched-chain amino acid metabolism in glial and neuronal cells in culture.

Transamination of branched-chain amino acids (BCAAs) catalyzed by the branched chain aminotransferase isoenzymes (BCATs) is believed to play an important role in nitrogen shuttling and excitatory neurotransmitter glutamate metabolism in brain. Recently, we have shown that the mitochondrial isoenzyme (BCATm) is the predominant form found in cultured astrocytes. In this study we used immunocytochemistry to examine the distribution of BCAT isoenzymes in cultured rat neurons and microglial cells. The cytoplasm of neurons displayed intense staining for the cytosolic isoenzyme (BCATc), whereas BCATm staining was not detectable in neurons. In contrast, microglial cells expressed BCATm in high concentration. BCATc appeared to be absent in this cell type. The second and committed step in the BCAA catabolic pathway is oxidative decarboxylation of the alpha-keto acid products of BCAT catalyzed by the branched-chain alpha-keto acid dehydrogenase (BCKD) enzyme complex. Because the presence of BCKD should provide an index of the ability of a cell to oxidize BCAA, we have also immunocytochemically localized BCKD in neuron and glial cell cultures from rat brain. Our results suggest ubiquitous expression of this BCKD enzyme complex in cultured brain cells. BCKD immunoreactivity was detected in neurons and in astroglial and microglial cells. Therefore, the expression of BCAT isoenzymes shows cell-specific localization, which is consistent with the operation of an intercellular nitrogen shuttle between neurons and astroglia. On the other hand, the ubiquitous expression of BCKD suggests that BCAA oxidation can probably take place in all types of brain cells and is most likely regulated by the activity state of BCKD rather than by its cell-specific localization.

Amino Acids, Branched-Chain↗
PubMed1992

Insulin action on glucose and branched-chain amino acid metabolism in cancer cachexia: differential effects of insulin.

In addition to the maintenance of glucose homeostasis, insulin plays a major role in the regulation of branched-chain amino acid (BCAA) metabolism. We investigated insulin action on glucose turnover rates, arterial BCAA concentrations, and forearm BCAA flux in cancer cachexia. Six weight-losing patients with localized gastrointestinal malignancy and five age-matched control subjects underwent sequential 120-minute euglycemic insulin infusions. Steady-state insulin concentrations were 50 +/- 5, 97 +/- 14, and 435 +/- 14 microU/ml in patients and 44 +/- 4, 95 +/- 6, and 495 +/- 42 microU/ml in control subjects at the insulin infusion rates of 0.5, 1.0, and 4.0 mU/kg.min, respectively. During the 0.5 and 1.0 mU/kg.min insulin infusions, a primed, continuous infusion of D-[3-3H] glucose was used to quantify endogenous glucose production. Total body glucose uptake was decreased in patients with cancer compared with control subjects at the 0.5 mU/kg.min (2.9 +/- 0.4 vs 3.6 +/- 1.2 mg/kg.min), 1.0 mU/kg.min (5.3 +/- 0.3 vs 8.7 +/- 0.8 mg/kg.min; p less than 0.05), and 4.0 mU/kg.min (10.9 +/- 0.9 vs 13.7 +/- 1.1 mg/kg.min) insulin infusion rates, consistent with a state of insulin resistance. Progressive euglycemic insulin infusion induced a marked, comparable insulin-dependent decrease in arterial plasma BCAA concentrations in both patients with cancer and control subjects. There was no change in postabsorptive forearm BCAA flux with progressive hyperinsulinemia. Insulin-induced branched-chain hypoaminoacidemia is unimpaired in this group of patients manifesting resistance to insulin action on glucose metabolism, thereby providing evidence of a differential resistance to insulin action on glucose metabolism versus insulin action on BCAA concentrations in cancer cachexia. Peripheral BCAA flux is not affected by systemic insulin infusion, suggesting that skeletal muscle is not a major site of BCAA disposal during insulin-mediated hypoaminoacidemia.

Amino Acids↗