A model for determination of total body protein synthesis based upon compartmental analysis of the plasma [15N] glycine decay curve

Metabolism ◽  
1983 ◽  
Vol 32 (7) ◽  
pp. 646-653 ◽  
Author(s):  
Itzhak Nissim ◽  
Marc Yudkoff ◽  
Stanton Segal
Keyword(s):  
Protein Synthesis ◽  
Decay Curve ◽  
Compartmental Analysis ◽  
Body Protein ◽  
Total Body

scholarly journals Determining Ideal Balance Among Branched-Chain Amino Acids (BCAA) as a Proof of Concept Study in Healthy Children

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1068-1068
Author(s):  
Haneen Saleemani ◽  
Rajavel Elango ◽  
Gabriella Horvath ◽  
Sylvia Stockler
Keyword(s):  
Protein Synthesis ◽  
Future Research ◽  
Acid Oxidation ◽  
P Value ◽  
Healthy Children ◽  
Proof Of Concept ◽  
Body Protein ◽  
Wide Range ◽  
Medical Foods ◽  
Total Body

Abstract Objectives Medical foods for children with in-born errors of metabolism (propionic academia, PROP) are formulated with imbalanced mixture of the BCAA (high leucine, to minimal or no valine and isoleucine), and therefore their use is controversial. The objective of the current study was to determine an ideal BCAA ratio at which total body protein synthesis is optimized in healthy children using the indicator amino acid oxidation (IAAO) method. Methods The study design was based on the oxidation of the stable isotope L-[1–,13C] phenylalanine to ,13CO2 to compare protein synthesis among seven different BCAA ratios. Leucine intake was gradually reduced from current high doses in medical foods; isoleucine and valine were kept constant. This study was done as a proof of concept in healthy children, to allow characterization of the metabolic responses to wide range of leucine test intakes, to help design narrow BCAA ratio range to test in children with PROP. Results A total of 8 healthy children were studied, completing 42 study days. ANOVA showed significant differences in F13CO2 with different BCAA ratios; P value <0.001. A BCAA ratio of (leucine: Isoleucine: Valine = 1:0:0) was associated with the highest F13CO2 compared to other ratios (p value <0.001), indicating low total body protein synthesis. By reducing leucine intake, with BCAA ratio between (1: 0.26: 0.28 to 1:0.35:0.4) protein synthesis was optimized. Conclusions Using the IAAO method in healthy children, we tested for the first time the effect of different BCAA ratios on protein synthesis. Results from this study confirmed that the BCAA ratio of (leucine: Isoleucine: Valine = 1:0:0), which is similar to the ratio in medical foods, limited total body protein synthesis. Furthermore, a balanced BCAA ratio that optimized protein synthesis was found to be between (1: 0.26: 0.28) and (1: 0.35:0.4). Thus, we propose reformulating the BCAA mixture in medical foods, by reducing leucine content by 50%. Future research in children with PROP with our proposed BCAA ratio is necessary to confirm improved patient growth outcomes. Funding Sources Faculty of Applied Medical Sciences, Department of Clinical Nutrition, King Abdulaziz University and BC Children's Hospital Research Institute.

scholarly journals Whole body and tissue fractional protein synthesis in the ovine fetusin utero

1984 ◽  
Vol 52 (2) ◽  
pp. 359-369 ◽  
Author(s):  
A. L. Schaefer ◽  
C. R. Krishnamurti
Keyword(s):  
Protein Synthesis ◽  
Activity Ratio ◽  
Specific Activity ◽  
Whole Body ◽  
Absolute Rate ◽  
Body Protein ◽  
Tissue Protein ◽  
Fractional Rate ◽  
Tyrosine Concentration

1. Whole-body and tissue fractional protein synthesis rates were determined in chronically-catheterized ovine fetuses at 120–130 d of gestation following an 8 h continuous infusion of L-[U-14C]-or L-[2, 3, 5, 6-3H]tyrosine.2. From the net utilization of tyrosine by the fetus, corrected for apparent oxidation, and tyrosine concentration in the fetal carcass protein, whole-body protein synthesis was estimated to be 63 g/d per kg.3. Following 8 h of infusion of labelled tyrosine the ewes were killed and fetal tissues were removed for the determination of tyrosine specific activity. The fractional rate of protein synthesis (k3) was calculated from the specific activity ratio, protein bound: intracellular free tyrosine. Tissue k, values for the liver, kidney, lungs, brain, skeletal muscle and small intestine were 78, 45, 65, 37, 26 and 93% /d respectively.4. The absolute rate of synthesis was calculated by multiplying the tissue protein content by k2. Muscles, gastrointestinal tract, liver and lungs contributed approximately 20.5, 20.5, 14.4 and 9.4% respectively to whole- body protein synthesis.5. The efficiency of protein synthesis as expressed by the RNA activity was higher in liver, lung and brain followed by kidney, skeletal and cardiac muscle.

Nephrotic proteinuria has no net effect on total body protein synthesis: Measurements with 13C valine

2000 ◽  
Vol 35 (6) ◽  
pp. 1149-1154 ◽  
Author(s):  
Monique G.M. de Sain-van der Velden ◽  
Kees de Meer ◽  
Wim Kulik ◽  
Christian F. Melissant ◽  
Ton J. Rabelink ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Body Protein ◽  
Nephrotic Proteinuria ◽  
Total Body

Effect of testosterone on muscle mass and muscle protein synthesis

1989 ◽  
Vol 66 (1) ◽  
pp. 498-503 ◽  
Author(s):  
R. C. Griggs ◽  
W. Kingston ◽  
R. F. Jozefowicz ◽  
B. E. Herr ◽  
G. Forbes ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Total Body Potassium ◽  
Body Protein ◽  
Total Body

We have studied the effect of a pharmacological dose of testosterone enanthate (3 mg.kg-1.wk-1 for 12 wk) on muscle mass and total-body potassium and on whole-body and muscle protein synthesis in normal male subjects. Muscle mass estimated by creatinine excretion increased in all nine subjects (20% mean increase, P less than 0.02); total body potassium mass estimated by 40K counting increased in all subjects (12% mean increase, P less than 0.0001). In four subjects, a primed continuous infusion protocol with L-[1–13C]leucine was used to determine whole-body leucine flux and oxidation. Whole-body protein synthesis was estimated from nonoxidative flux. Muscle protein synthesis rate was determined by measuring [13C]leucine incorporation into muscle samples obtained by needle biopsy. Testosterone increased muscle protein synthesis in all subjects (27% mean increase, P less than 0.05). Leucine oxidation decreased slightly (17% mean decrease, P less than 0.01), but whole-body protein synthesis did not change significantly. Muscle morphometry showed no significant increase in muscle fiber diameter. These studies suggest that testosterone increases muscle mass by increasing muscle protein synthesis.

scholarly journals GRAVIMETRIC METHODS FOR THE DETERMINATION OF TOTAL BODY PROTEIN AND ORGAN PROTEIN

1936 ◽  
Vol 113 (2) ◽  
pp. 497-504
Author(s):  
T. Addis ◽  
L.J. Poo ◽  
W. Lew ◽  
D.W. Yuen
Keyword(s):  
Body Protein ◽  
Total Body

Total Protein Synthesis in Elderly People: A Comparison of Results with [15N]glycine and [14C]leucine

1977 ◽  
Vol 53 (3) ◽  
pp. 277-288 ◽  
Author(s):  
M. H. N. Golden ◽  
J. C. Waterlow
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Specific Radioactivity ◽  
The Elderly ◽  
Synthesis Rate ◽  
Total N ◽  
Body Protein ◽  
Total Body ◽  
Plasma Leucine ◽  
The Individual

1. Total body protein turnover was studied in six elderly patients. 2. During the study they were fed by continuous infusion of a liquid formula through a nasogastric tube. l-[1-14C]Leucine and [15N]glycine were infused at a constant rate for 30 h. The labelled glycine was infused into the intragastric line; the labelled leucine was given either by this route or intravenously. 3. The specific radioactivity of free leucine in plasma and the rate of output of 14CO2 in expired air both reached a plateau at 10 h, and remained constant until the end of the infusion at 30 h. 4. The 15N abundance in urinary urea and total N was very similar. In neither was a plateau reached by 30 h but in four out of the six patients the abundance in urinary NH4+ had attained a plateau by the end of the infusion. 5. Flux rates and rates of protein synthesis were calculated in four ways: (A) from the specific radioactivity of plasma leucine at plateau; (B) from the proportion of dose excreted as 14CO2 at plateau; (C) from the final rates of 15N excretion in urea or total urinary N; (D) from the final or plateau rates of 15N excretion in urinary NH4+. 6. On average, the estimates of synthesis rate obtained by methods B and C agreed closely; those given by methods A and D were lower. Methods A, B and D ranked the individual patients in almost identical order. 7. The comparison of methods makes it possible to examine the validity of the assumptions on which the different methods depend. Method B is probably theoretically the most satisfactory and, of the methods used in this work, probably gives the best estimate of the absolute turnover rate. The other methods can be used for comparative purposes. 8. The results suggest that the rate of protein turnover is reduced in the elderly, compared with younger subjects.

Measurement of Muscle Protein Synthetic Rate from Serial Muscle Biopsies and Total Body Protein Turnover in Man by Continuous Intravenous Infusion of l-[α-15N]lysine

1975 ◽  
Vol 49 (6) ◽  
pp. 581-590 ◽  
Author(s):  
D. Halliday ◽  
R. O. McKeran
Keyword(s):  
Protein Synthesis ◽  
Continuous Infusion ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis Muscle ◽  
Body Protein ◽  
Day Range ◽  
Synthetic Rate ◽  
Total Body

1. Five healthy male subjects were studied by continuous infusion of l-[α-15N]lysine over 20–30 h with timed blood and urine samples, and two or three percutaneous needle biopsies of vastus lateralis muscle. 2. A standard creatine-free diet, quantitatively related to body surface area, was given for 5 days before the infusion. The [15N]lysine was administered at a constant rate in an amino acid solution with a nitrogen content of 0·96 mol/l, which constituted the sole source of exogenous nitrogen during the infusion. 3. A plateau level of plasma free [15N]lysine enrichment was achieved after infusion for 14 h. The total plasma lysine flux calculated from the plateau was 7·3 mmol/h (range 4·8–9·6). Total body protein turnover calculated from the lysine flux was 3·5 g day−1 kg body wt.−1 (range 2·5–5·0). 4. Muscle sarcoplasmic and myofibrillar fractions were separated, purified and the 15N enrichment was measured. The sarcoplasmic protein fractional synthetic rate was calculated as 3·8%/day (range 2·2–5·1). The myofibrillar protein synthetic rate was 1·46%/day (range 1·09–2·44). 5. Muscle mass, calculated from 24 h creatinine excretion, was 33·7 kg (range 28·8–37·4), which represented 500% of body weight (range 38·9–58·1). Total muscle protein synthesis was calculated to account for 53·2% (range 39·5–62·1) of total body protein synthesis. 6. The advantages and limitations of using continuous infusion of [15N]lysine in human subjects are discussed.

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