scholarly journals Low Protein Formula: Consequences of Quantitative Effects of Pre-analytical Factors on Amino Acid Concentrations in Plasma of Healthy Infants

2016 ◽  
pp. 59-67 ◽  
Author(s):  
Claude Bachmann ◽  
Alexander Kainz ◽  
Elisabeth Haschke-Becher
Keyword(s):  
Amino Acid ◽  
Low Protein ◽  
Healthy Infants ◽  
Amino Acid Concentrations

Plasma Insulin and Amino Acid Concentrations in Rats Given an Adequate or Low Protein Diet

1973 ◽  
Vol 103 (5) ◽  
pp. 720-729 ◽  
Author(s):  
Vernon R. Young ◽  
Gaston Vilaire ◽  
Paul M. Newberne ◽  
Robert B. Wilson
Keyword(s):  
Amino Acid ◽  
Plasma Insulin ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Low Protein ◽  
Amino Acid Concentrations

Variation in the apparent sensitivity of the insulin-mediated inhibition of proteolysis to amino acid supply determines the efficiency of protein utilization

1998 ◽  
Vol 95 (6) ◽  
pp. 725-733 ◽  
Author(s):  
Amelia FEREDAY ◽  
Neil R. GIBSON ◽  
Malcolm COX ◽  
Paul J. PACY ◽  
D. Joe MILLWARD
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Insulin Level ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Low Protein ◽  
Normal Individuals ◽  
Protein Feeding ◽  
Amino Acid Concentrations ◽  
Stimulation Of

1. The variability between normal individuals in the efficiency of postprandial protein utilization (PPU), a determinant of the apparent protein requirement, was examined in relation to the relative responses of protein synthesis and proteolysis to protein feeding by means of [1–13C]leucine turnover and balance studies. 2. Twenty-five healthy adults were infused intravenously with l-[1-13C]leucine continuously for 9 h. This was started in the postabsorptive state (PA, 3 h) and followed by low-protein feeding (LP, 3 h), and then by isoenergetic high-protein feeding (HP, 3 h). This allowed protein intake to be varied against a constant postprandial insulin level so that the extent of any amino-acid-mediated responses which were additional to those exerted by insulin could be investigated. Leucine oxidation, O, and balance (intake-oxidation), protein synthesis, S, and degradation, D, were calculated from plasma [1-13C]α-ketoisocaproic acid enrichment and 13CO2 excretion. 3. PPUprotein, calculated as change in leucine balance/change in intake (HP-LP), varied from 0.58 to 0.99 (mean = 0.81±0.10), independently of age or sex. PPUprotein varied directly with the inhibition of D and inversely with the increase in leucine concentration and stimulation of O and S. 4. Efficient PPU, as demonstrated by the top quintile of individuals categorized in terms of PPUprotein, involves maximal inhibition of D by protein feeding with minimal increases in free amino acid concentrations, O and S. Lesser inhibition of D and greater stimulation of S and O characterized the lower, less efficient quintile. This indicates that the efficiency of protein utilization in individuals, and a component of their apparent protein requirement, is determined by the sensitivity of the insulin-mediated inhibition of proteolysis to amino acid supply.

RELATIONSHIP BETWEEN DIETARY PROTEIN CONTENT AND PLASMA AMINO ACIDS IN SHEEP FED PURIFIED DIETS

1973 ◽  
Vol 53 (3) ◽  
pp. 455-464
Author(s):  
A. CECYRE ◽  
G. M. JONES ◽  
J.-M. GAUDREAU
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Time Intervals ◽  
Dietary Nitrogen ◽  
Low Protein ◽  
Limiting Amino Acid ◽  
Nonessential Amino Acids ◽  
Amino Acid Concentrations

Semipurified diets, varying in crude protein (CP) content (6, 10, 15, and 22% CP), were each fed to one wether and plasma amino acid (PAA) concentrations were determined at 0, 15, 30, 60, 120, 240, and 360 min postfeeding. Total essential amino acid concentrations for the 6, 10, and 15% CP rations were 47.2, 76.4, and 72.9 μmol/ml, while nonessential amino acids totalled 88.3, 110.0, and 104.9 μmol/ml, respectively. In general, PAA concentrations were depressed by the low protein diet, except for glycine, which was elevated, and threonine and alanine, which were not affected. PAA concentrations gradually decreased with time after feeding. There was no evident relationship between PAA levels and amount of feed consumed at these time intervals. Lysine was probably the most limiting amino acid, based upon PAA concentrations on the low protein diet compared to average PAA levels for all diets. PAA concentrations reflected dietary nitrogen content. The results suggest that PAA levels were not involved in the regulation of voluntary intake when the diet contained sufficient protein to meet the requirements of the animal.

scholarly journals Nutritional aspects of amino acid metabolism

1972 ◽  
Vol 27 (2) ◽  
pp. 233-247 ◽  
Author(s):  
D. L. Bloxam
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Essential Amino Acids ◽  
Blood Levels ◽  
Low Protein ◽  
Extrahepatic Tissues ◽  
D Values ◽  
Liver Changes ◽  
Amino Acid Concentrations

1. Concentrations of the amino acids in the plasma of blood from the portal vein and hepatic vein and in the liver of fed rats and rats starved for 1 d or 3 d were measured. The 1 d values were compared with the equilibrium concentrations of the amino acids found in the perfusion medium during perfusion of livers from rats starved for 1 d.2. The measurements of portal–venous differences in amino acid concentrations confirmed the idea that postprandially and during starvation most of the amino acids flow from extrahepatic tissues to the liver but also showed that during starvation tryptophan, cystine, ornithine, valine, leucinc and isoleucine flow in the opposite direction, from liver to extrahepatic tissues.3. The blood levels of the non-essential amino acids fell markedly during starvation while those of the essential ones tended to be maintained. This contrasts with the pattern of changes known to take place in rats and man given low-protein diets. In the liver, changes in amino acid concentrations were generally related to those in the blood but not strictly parallel. The relative changes in amino acid concentrations in blood and liver indicate that as starvation progresses the concentrative ability of the liver is enhanced for most of the amino acids which are taken up and that the increased output of those which are released is also due to changed membrane transport.4. The changes in plasma amino acid concentrations in the blood passing through livers of rats starved for 1 d were, except for tryptophan and perhaps cystine, consistent with the extracellular changes found during perfusion of livers form rats straved for 1 d, indicating that the perfused liver influences concentrations of extracellular amino acids substantially as it does in vivo.5. The results suggest of mechanism wherby the liver may control the maintenance of the essential amino acids during starvation.

Correlations between amino acid concentrations in brains of seizure-susceptible and seizure-resistant rats

1982 ◽  
Vol 4 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Ryan J. Huxtable ◽  
Hugh Laird ◽  
Douglas Bonhaus ◽  
A. Cole Thies
Keyword(s):  
Amino Acid ◽  
Amino Acid Concentrations
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