scholarly journals Whole Body Protein Oxidation Unaffected after a Protein Restricted Diet in Healthy Young Males

Nutrients ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 115 ◽  
Author(s):  
Gerlof A.R. Reckman ◽  
Gerjan J. Navis ◽  
Wim P. Krijnen ◽  
Cees P. Van der Schans ◽  
Roel J. Vonk ◽  
...  
Keyword(s):  
Body Weight ◽  
G Protein ◽  
Protein Oxidation ◽  
Protein Metabolism ◽  
Protein Intake ◽  
Milk Protein ◽  
Whole Body ◽  
Restricted Diet ◽  
Body Protein ◽  
Protein Restricted Diet

Protein oxidation may play a role in the balance between anabolism and catabolism. We assessed the effect of a protein restricted diet on protein oxidation as a possible reflection of whole body protein metabolism. Sixteen healthy males (23 ± 3 years) were instructed to use a 4-day isocaloric protein restricted diet (0.25 g protein/kg body weight/day). Their habitual dietary intake was assessed by a 4-day food diary. After an overnight fast, a 30 g 13C-milk protein test drink was administered, followed by 330 min breath sample collection. Protein oxidation was measured by Isotope Ratio Mass Spectrometry. To assess actual change in protein intake from 24-h urea excretion, 24-h urine was collected. During the 4-day protein restricted diet, the urinary urea:creatinine ratio decreased by 56 ± 9%, which is comparable to a protein intake of ~0.65 g protein/kg body weight/day. After the protein restricted diet, 30.5 ± 7.3% of the 30 g 13C-milk protein was oxidized over 330 min, compared to 31.5 ± 6.4% (NS) after the subject’s habitual diet (1.3 ± 0.3 g protein/kg body weight/day). A large range in the effect of the diet on protein oxidation (−43.2% vs. +44.0%) was observed. The residual standard deviation of the measurements was very small (0.601 ± 0.167). This suggests that in healthy males, protein oxidation is unaffected after a protein restricted diet. It is uncertain how important the role of fluctuations in short-term protein oxidation is within whole body protein metabolism.

Leucine and protein metabolism in the lactating dairy cow mammary gland: responses to supplemental dietary crude protein intake

1996 ◽  
Vol 63 (2) ◽  
pp. 209-222 ◽  
Author(s):  
Brian J. Bequette ◽  
John A. Metcalf ◽  
Diane Wray-Cahen ◽  
F. R. Colette Backwell ◽  
John D. Sutton ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Protein Intake ◽  
Crude Protein ◽  
Milk Protein ◽  
Protein Supplementation ◽  
Whole Body ◽  
Body Protein

SummaryMammary gland protein metabolism, determined by an arteriovenous difference technique, was monitored in four Holstein-Friesian dairy cows in response to supplemental dietary protein (provided as rumen-protected soyabean meal) during late lactation (weeks 24–30). Each cow was offered two isoenergetic diets composed of grass silage (170 g crude protein/kg dry matter) plus either a low (108 g/kg) or medium (151 g/kg) crude protein concentrate in a single crossover design involving two 21 d periods. On day 21, arteriovenous measurements across the mammary gland were made during a 13 h continuous i.v. infusion of [1-13C]leucine and with frequent (2 hourly) milk sampling during the final 6 h. Although total milk yield was slightly increased (+1 kg/d) by protein supplementation, milk protein yield was not significantly affected. Whole body protein flux (protein synthesis plus oxidation) was not significantly affected by supplementation. Total mammary gland protein synthesis (milk plus non-milk protein) was also not affected by supplementation but on both diets gland synthesis was always greater (by 20–59%) than milk protein output. The fractional oxidation rate of leucine by the mammary gland was significantly increased by protein supplementation (0·047 v. 0·136). Although the enrichment of leucine in secreted milk protein continued to increase, the final value (at 13 h) was 0·94 of the arterial plasma free leucine plateau value (not significantly different), suggesting almost exclusive use of plasma free leucine for milk protein synthesis. Based on current feeding schemes for dairy cattle, a fixed proportion (0·65–0·75) of the additional protein intake (+490 g/d) should have been partitioned into milk protein. Instead, leucine oxidation by the mammary gland was increased. Whether oxidation of other amino acids was also enhanced is unknown but if amino acid oxidation and the ‘additional’ non-milk protein synthesis occurring in the gland are not crucial to milk synthesis, then by reducing such activities improvements in the efficiency of converting absorbed amino acid into milk protein can be achieved.

scholarly journals Protein metabolism in glucocorticoid excess: study in Cushing's syndrome and the effect of treatment

2007 ◽  
Vol 292 (5) ◽  
pp. E1426-E1432 ◽  
Author(s):  
Morton G. Burt ◽  
James Gibney ◽  
Ken K. Y. Ho
Keyword(s):  
Body Composition ◽  
Cushing’S Syndrome ◽  
Protein Oxidation ◽  
Protein Metabolism ◽  
Cushing's Syndrome ◽  
Whole Body ◽  
Constant Infusion ◽  
Leucine Incorporation ◽  
Body Protein ◽  
The Impact

How protein metabolism is perturbed during chronic glucocorticoid excess is poorly understood. The aims were to investigate the impact of chronic glucocorticoid excess and restoration of eucortisolemia in Cushing's syndrome (CS) on whole body protein metabolism. Eighteen subjects with CS and 18 normal subjects (NS) underwent assessment of body composition using DEXA and whole body protein turnover with a 3-h constant infusion of l-[13C]leucine, allowing calculation of rates of leucine appearance (leucine Ra), leucine oxidation (Lox), and leucine incorporation into protein (LIP). Ten subjects with CS were restudied after restoration of eucortisolemia. Percentage FM was greater (43.9 ± 1.6 vs. 33.8 ± 2.4%, P = 0.002) and LBM lower (52.7 ± 1.6 vs. 62.1 ± 2.3%, P = 0.002) in CS. LBM was significantly correlated ( r2 > 0.44, P < 0.005) to leuceine Ra, Lox, and LIP in both groups. After correcting for LBM, leucine Ra (133 ± 5 vs. 116 ± 5 μmol/min, P = 0.02) and Lox (29 ± 1 vs. 24 ± 1 μmol/min, P = 0.01) were greater in CS. FM significantly correlated ( r2 = 0.23, P < 0.05) with leucine Ra and LIP, but not Lox in CS. In multiple regression, LBM was an independent determinant of all three indexes of leucine turnover, FM of leucine Ra, and LIP and CS of Lox. Following restoration of eucortisolemia, Lox was reduced (Δ−7.5 ± 2.6 μmol/min, P = 0.02) and LIP increased (Δ+15.2 ± 6.2 μmol/min, P = 0.04). In summary, whole body protein metabolism in CS is influenced by changes in body composition and glucocorticoid excess per se, which increases protein oxidation. Enhanced protein oxidation is a likely explanation for the reduced protein mass in CS. Successful treatment of CS reduces protein oxidation and increases protein synthesis to prevent ongoing protein loss.

Weight loss in postmenopausal obesity: no adverse alterations in body composition and protein metabolism

2000 ◽  
Vol 279 (1) ◽  
pp. E124-E131 ◽  
Author(s):  
Dympna Gallagher ◽  
Albert J. Kovera ◽  
Gaynelle Clay-Williams ◽  
Denise Agin ◽  
Patricia Leone ◽  
...  
Keyword(s):  
Weight Loss ◽  
Body Composition ◽  
Body Weight ◽  
Postmenopausal Women ◽  
Body Mass ◽  
Protein Metabolism ◽  
Cell Mass ◽  
Whole Body ◽  
Healthy Weight ◽  
Body Protein

We sought to determine if decrements in the mass of fat-free body mass (FFM) and other lean tissue compartments, and related changes in protein metabolism, are appropriate for weight loss in obese older women. Subjects were 14 healthy weight-stable obese (BMI ≥30 kg/m2) postmenopausal women >55 yr who participated in a 16-wk, 1,200 kcal/day nutritionally complete diet. Measures at baseline and 16 wk included FFM and appendicular lean soft tissue (LST) by dual-energy X-ray absorptiometry; body cell mass (BCM) by 40K whole body counting; total body water (TBW) by tritium dilution; skeletal muscle (SM) by whole body MRI; and fasting whole body protein metabolism through l-[1-13C]leucine kinetics. Mean weight loss (±SD) was 9.6 ± 3.0 kg ( P < 0.0001) or 10.7% of initial body weight. FFM decreased by 2.1 ± 2.6 kg ( P = 0.006), or 19.5% of weight loss, and did not differ from that reported (2.3 ± 0.7 kg). Relative losses of SM, LST, TBW, and BCM were consistent with reductions in body weight and FFM. Changes in [13C]leucine flux, oxidation, and synthesis rates were not significant. Follow-up of 11 subjects at 23.7 ± 5.7 mo showed body weight and fat mass to be below baseline values; FFM was nonsignificantly reduced. Weight loss was accompanied by body composition and protein kinetic changes that appear appropriate for the magnitude of body mass change, thus failing to support the concern that diet-induced weight loss in obese postmenopausal women produces disproportionate LST losses.

Effect of increased protein intake and nutritional status on whole-body protein metabolism of aids patients with weight loss

Metabolism ◽  
1995 ◽  
Vol 44 (9) ◽  
pp. 1159-1165 ◽  
Author(s):  
Oliver Selberg ◽  
Ulrich Suttmann ◽  
Ariane Melzer ◽  
Helmuth Deicher ◽  
Manfred-James Müller ◽  
...  
Keyword(s):  
Weight Loss ◽  
Nutritional Status ◽  
Protein Metabolism ◽  
Protein Intake ◽  
Whole Body ◽  
Aids Patients ◽  
Body Protein

scholarly journals Impact of Acute and Chronic Low-Dose Glucocorticoids on Protein Metabolism

2007 ◽  
Vol 92 (10) ◽  
pp. 3923-3929 ◽  
Author(s):  
Morton G. Burt ◽  
Gudmundur Johannsson ◽  
A. Margot Umpleby ◽  
Donald J. Chisholm ◽  
Ken K. Y. Ho
Keyword(s):  
Protein Oxidation ◽  
Protein Metabolism ◽  
Normal Subjects ◽  
Whole Body ◽  
Metabolic Adaptation ◽  
High Dose ◽  
Protein Breakdown ◽  
Protein Loss ◽  
Body Protein ◽  
Significant Difference

Abstract Context: High-dose glucocorticoids cause acute protein loss by increasing protein breakdown and oxidation. Whether lower glucocorticoid doses, typical of therapeutic use, induce sustained catabolism has not been studied. Objective: Our objective was to assess the effect of acute and chronic therapeutic glucocorticoid doses on protein metabolism. Design and Setting: We conducted an open longitudinal and a cross-sectional study at a clinical research facility. Patients and Intervention: Ten healthy subjects were studied before and after a short course of prednisolone (5 and 10 mg/d sequentially for 7 d each). Twelve subjects with inactive polymyalgia rheumatica receiving chronic (&gt;12 months) prednisone (mean = 5.0 ± 0.8 mg/d) were compared with 12 age- and gender-matched normal subjects. Main Outcome Measure: Whole-body protein metabolism was assessed using a 3-h primed constant infusion of 1-[13C]leucine, from which rates of leucine appearance (leucine Ra, an index of protein breakdown), leucine oxidation (Lox, index of protein oxidation) and leucine incorporation into protein (LIP, index of protein synthesis) were estimated. Results: Prednisolone induced an acute significant increase in Lox (P = 0.008) and a fall in LIP (P = 0.08) but did not affect leucine Ra. There was no significant difference between the effects of the 5- and 10-mg prednisolone doses on leucine metabolism. In subjects receiving chronic prednisone therapy, leucine Ra, Lox, and LIP were not significantly different from normal subjects. Conclusion: Glucocorticoids stimulate protein oxidation after acute but not chronic administration. This time-related change suggests that glucocorticoid-induced stimulation of protein oxidation does not persist but that a metabolic adaptation occurs to limit protein loss.

Resting metabolic rate and protein turnover in apparently healthy elderly Gambian men

1995 ◽  
Vol 268 (6) ◽  
pp. E1083-E1088 ◽  
Author(s):  
C. Benedek ◽  
P. Y. Berclaz ◽  
E. Jequier ◽  
Y. Schutz
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Protein Synthesis ◽  
G Protein ◽  
Protein Turnover ◽  
The Elderly ◽  
Young Group ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein

Body composition, resting energy expenditure (REE), and whole body protein metabolism were studied in 26 young and 28 elderly Gambian men matched for body mass index during the dry season in a rural village in The Gambia. REE was measured by indirect calorimetry (hood system) in the fasting state and after five successive meals. Rates of whole body nitrogen flux, protein synthesis, and protein breakdown were determined in the fed state from the level of isotopic enrichment of urinary ammonia over a period of 12 h after a single oral dose of [15N]glycine. Expressed in absolute value, REE was significantly lower in the elderly compared with the young group (3.21 +/- 0.07 vs. 4.04 +/- 0.07 kJ/min, P < 0.001) and when adjusted to body weight (3.29 +/- 0.05 vs. 3.96 +/- 0.05 kJ/min, P < 0.0001) and fat-free mass (FFM; 3.38 +/- 0.01 vs. 3.87 +/- 0.01 kJ/min, P < 0.0001). The rate of protein synthesis averaged 207 +/- 13 g protein/day in the elderly and 230 +/- 13 g protein/day in the young group, whereas protein breakdown averaged 184 +/- 13 g protein/day in the elderly and 203 +/- 13 g protein/day in the young group (nonsignificant). When values were adjusted for body weight or FFM, they did not reveal any difference between the two groups. It is concluded that the reduced REE adjusted for body composition observed in elderly Gambian men is not explained by a decrease in protein turnover.

scholarly journals How Is Whole Body Protein Turnover Perturbed in Growth Hormone-Deficient Adults?1

1998 ◽  
Vol 83 (12) ◽  
pp. 4344-4349
Author(s):  
David M. Hoffman ◽  
Robert Pallasser ◽  
Mark Duncan ◽  
Tuan V. Nguyen ◽  
Ken K. Y. Ho
Keyword(s):  
Protein Synthesis ◽  
Protein Oxidation ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Gh Deficiency ◽  
Normal Subjects ◽  
Whole Body ◽  
Leucine Incorporation ◽  
Body Protein ◽  
Independent Determinant

Adult patients with GH deficiency have reduced lean body mass (LBM), muscle mass, and muscle strength, suggesting an underlying abnormality of protein metabolism. As acute GH administration has previously been reported to decrease protein oxidation and increase protein synthesis in GH-deficient (GHD) adults, we investigated whether the converse might occur in untreated GH deficiency by undertaking studies of whole body protein turnover in 10 GHD and 13 normal subjects using a 3-h primed constant infusion of 1-[13C]leucine. Dual energy x-ray absorptiometry was used to quantify LBM and fat mass (FM). In normal subjects, LBM was the major, independent determinant of leucine appearance (Ra; r = 0.80; P = 0.0009), leucine oxidation (r = 0.81; P = 0.0008), and leucine incorporation into protein (r = 0.75; P = 0.003). However, in an analysis of covariance, FM was also a significant independent determinant of leucine Ra (P = 0.002) and leucine incorporation into protein (P = 0.003). After correcting for LBM and FM, GHD patients had significantly reduced rates of leucine Ra (109.9 ± 4.4 vs. 125.5 ± 3.7 μmol/min, respectively; P = 0.02) and leucine incorporation into protein (87.0 ± 3.9 vs. 100.3 ± 3.3 mmol/min; P = 0.02) compared to normal subjects. There was no significant difference in the corrected rates of leucine oxidation between the two groups (22.9 ± 1.3 vs. 25.2± 1.0, GHD vs. normal; P = 0.20). In summary, GHD adults have reduced rates of protein synthesis and protein breakdown, but normal rates of irreversible oxidative loss; these findings are discordant with what was predicted from the acute changes in protein metabolism observed with GH administration. We conclude that normalization of protein oxidation may be a homeostatic mechanism that operates to constrain protein loss in GHD adults.

scholarly journals Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults

2015 ◽  
Vol 308 (1) ◽  
pp. E21-E28 ◽  
Author(s):  
Il-Young Kim ◽  
Scott Schutzler ◽  
Amy Schrader ◽  
Horace Spencer ◽  
Patrick Kortebein ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
G Protein ◽  
Protein Intake ◽  
Muscle Protein ◽  
Distribution Patterns ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Balance ◽  
Body Protein ◽  
Net Protein

To examine whole body protein turnover and muscle protein fractional synthesis rate (MPS) following ingestions of protein in mixed meals at two doses of protein and two intake patterns, 20 healthy older adult subjects (52–75 yr) participated in one of four groups in a randomized clinical trial: a level of protein intake of 0.8 g (1RDA) or 1.5 g·kg−1·day−1 (∼2RDA) with uneven (U: 15/20/65%) or even distribution (E: 33/33/33%) patterns of intake for breakfast, lunch, and dinner over the day (1RDA-U, 1RDA-E, 2RDA-U, or 2RDA-E). Subjects were studied with primed continuous infusions of l-[2H5]phenylalanine and l-[2H2]tyrosine on day 4 following 3 days of diet habituation. Whole body protein kinetics [protein synthesis (PS), breakdown, and net balance (NB)] were expressed as changes from the fasted to the fed states. Positive NB was achieved at both protein levels, but NB was greater in 2RDA vs. 1RDA (94.8 ± 6.0 vs. 58.9 ± 4.9 g protein/750 min; P = 0.0001), without effects of distribution on NB. The greater NB was due to the higher PS with 2RDA vs. 1RDA (15.4 ± 4.8 vs. −18.0 ± 8.4 g protein/750 min; P = 0.0018). Consistent with PS, MPS was greater with 2RDA vs. 1RDA, regardless of distribution patterns. In conclusion, whole body net protein balance was greater with protein intake above recommended dietary allowance (0.8 g protein·kg−1·day−1) in the context of mixed meals, without demonstrated effects of protein intake pattern, primarily through higher rates of protein synthesis at whole body and muscle levels.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

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