The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Robert R. Wolfe - One of the best experts on this subject based on the ideXlab platform.
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Muscle Protein synthesis in cancer patients can be stimulated with a specially formulated medical food
Clinical Nutrition, 2011Co-Authors: Nicolaas E P Deutz, Arny A Ferrando, A M Safar, Scott Schutzler, R G Memelink, Horace J Spencer, Ardy Van Helvoort, Robert R. WolfeAbstract:Summary Objective Maintenance of Muscle mass is crucial to improving outcome and quality of life in cancer patients. Stimulating Muscle Protein synthesis is the metabolic basis for maintaining Muscle mass, but in cancer patients normal dietary intake has minimal effects on Muscle Protein synthesis. Adding leucine to high Protein supplements stimulates Muscle Protein synthesis in healthy older subjects. The objective was to determine if a specially formulated medical food, high in leucine and Protein, stimulates Muscle Protein synthesis acutely in individuals with cancer to a greater extent than a conventional medical food. Design A randomized, controlled, double-blind, parallel-group design was used in 25 patients with radiographic evidence of cancer. Patients were studied before their cancer treatment was started or 4 weeks after their treatment was completed or halted. The fractional rate of Muscle Protein synthesis (FSR) was measured using the tracer incorporation technique with L-[ring- 13 C 6 ]-phenylalanine. The experimental group ( n = 13) received a medical food containing 40 g Protein, based on casein and whey Protein and enriched with 10% free leucine and other specific components, while the control group ( n = 12) was given a conventionally used medical food based on casein Protein alone (24 g). Blood and Muscle samples were collected in the basal state and 5h hours after ingestion of the medical foods. Results The cancer patients were in an inflammatory state, as reflected by high levels of C-reactive Protein (CRP), IL-1β and TNF-α, but were not insulin resistant (HOMA). After ingestion of the experimental medical food, plasma leucine increased to about 400 μM as compared to the peak value of 200 μM, after the control medical food ( p p = 0.0269). In contrast, ingestion of the control medical food did not increase Muscle FSR; 0.073 (SD: 0.022) and 0.065 (SD: 0.028) %/h. Conclusions In cancer patients, conventional nutritional supplementation is ineffective in stimulating Muscle Protein synthesis. This anabolic resistance can be overcome with a specially formulated nutritional supplement.
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amino acid repletion does not decrease Muscle Protein catabolism during hemodialysis
American Journal of Physiology-endocrinology and Metabolism, 2007Co-Authors: Oladipo Adeniyi, Elizabeth A Dominic, Sandra Mcclelland, Lawrence P Gonzales, Antonios H. Tzamaloukas, Michel Boivin, Nancy Morgan, Robert R. Wolfe, Arny A FerrandoAbstract:Intradialytic Protein catabolism is attributed to loss of amino acids in the dialysate. We investigated the effect of amino acid infusion during hemodialysis (HD) on Muscle Protein turnover and ami...
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atrophy and impaired Muscle Protein synthesis during prolonged inactivity and stress
The Journal of Clinical Endocrinology and Metabolism, 2006Co-Authors: Douglas Paddonjones, Melanie G Cree, Melinda Sheffieldmoore, Asle Aarsland, Robert R. Wolfe, Susan J Hewlings, Arny A FerrandoAbstract:Context: We recently demonstrated that 28-d bed rest in healthy volunteers results in a moderate loss of lean leg mass and strength. Objective: The objective of this study was to quantify changes in Muscle Protein kinetics, body composition, and strength during a clinical bed rest model reflecting both physical inactivity and the hormonal stress response to injury or illness. Design: Muscle Protein kinetics were calculated during a primed, continuous infusion (0.08 μmol/kg·min) of 13C6-phenylalanine on d 1 and 28 of bed rest. Setting: The setting for this study was the General Clinical Research Center at the University of Texas Medical Branch. Participants: Participants were healthy male volunteers (n = 6, 28 ± 2 yr, 84 ± 4 kg, 178 ± 3 cm). Intervention: During bed rest, hydrocortisone sodium succinate was administered iv (d 1 and 28) and orally (d 2–27) to reproduce plasma cortisol concentrations consistent with trauma or illness (∼22 μg/dl). Main Outcome Measures: We hypothesized that inactivity and hyp...
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milk ingestion stimulates net Muscle Protein synthesis following resistance exercise
Medicine and Science in Sports and Exercise, 2006Co-Authors: Tabatha A Elliot, Melanie G Cree, Arthur P Sanford, Robert R. Wolfe, Kevin D TiptonAbstract:ABSTRACTPurpose:Previous studies have examined the response of Muscle Protein to resistance exercise and nutrient ingestion. Net Muscle Protein synthesis results from the combination of resistance exercise and amino acid intake. No study has examined the response of Muscle Protein to ingestion of pr
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insulin resistance of Muscle Protein metabolism in aging
The FASEB Journal, 2006Co-Authors: Blake B. Rasmussen, Satoshi Fujita, Bettina Mittendorfer, Robert R. Wolfe, Vincent L Rowe, Elena VolpiAbstract:A reduced response of older skeletal Muscle to anabolic stimuli may contribute to the development of sarcopenia. We hypothesized that Muscle Proteins are resistant to the anabolic action of insulin in the elderly. We examined the effects of hyperinsulinemia on Muscle Protein metabolism in young (25±2 year) and older (68±1 year) healthy subjects using stable isotope tracer techniques. Leg blood flow was higher in the young at baseline and increased during hyperinsulinemia, whereas it did not change in the elderly. Glucose concentrations and Muscle uptake were not different between groups at baseline and during hyperinsulinemia. Leg phenylalanine net balance was not different at baseline and significantly increased in both groups with hyperinsulinemia (P<0.05) but to a greater extent in the young (P<0.05). Muscle Protein synthesis increased only in the young during hyperinsulinemia. Muscle Protein breakdown did not significantly change in either group, although it tended to decrease in the elderly. Changes in Muscle Protein synthesis were correlated with changes in leg amino acid delivery (R=0.89; P=0.0001) and blood flow (R=0.90; P<0.0001). In conclusion, skeletal Muscle Protein synthesis is resistant to the anabolic action of insulin in older subjects, which may be an important contributor to the development of sarcopenia.
Elena Volpi - One of the best experts on this subject based on the ideXlab platform.
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endothelial function and the regulation of Muscle Protein anabolism in older adults
Nutrition Metabolism and Cardiovascular Diseases, 2013Co-Authors: Kyle L Timmerman, Elena VolpiAbstract:Sarcopenia, the loss of skeletal Muscle mass and function with aging, is a major contributor to frailty and morbidity in older adults. Recent evidence has emerged suggesting that endothelial dysfunction and insulin resistance of Muscle Protein metabolism may significantly contribute to the development of sarcopenia. In this article we review: 1) recent studies and theories on the regulation of skeletal Muscle Protein balance in older adults; 2) the link between insulin resistance of Muscle Protein synthesis and endothelial dysfunction in aging; 3) mechanisms for impaired endothelial responsiveness in aging; and 4) potential treatments that may restore the endothelial responsiveness and Muscle Protein anabolic sensitivity in older adults.
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addition of carbohydrate or alanine to an essential amino acid mixture does not enhance human skeletal Muscle Protein anabolism
Journal of Nutrition, 2013Co-Authors: Erin L Glynn, Micah J Drummond, Elena Volpi, Kyle L Timmerman, Christopher S Fry, Blake B. RasmussenAbstract:In humans, essential amino acids (EAAs) stimulate Muscle Protein synthesis (MPS) with no effect on Muscle Protein breakdown (MPB). Insulin can stimulate MPS, and carbohydrates (CHOs) and insulin decrease MPB. Net Protein balance (NB; indicator of overall anabolism) is greatest when MPS is maximized and MPB is minimized. To determine whether adding CHO or a gluconeogenic amino acid to EAAs would improve NB compared with EAA alone, young men and women (n = 21) ingested 10 g EAA alone, with 30 g sucrose (EAA+CHO), or with 30 g alanine (EAA+ALA). The fractional synthetic rate and phenylalanine kinetics (MPS, MPB, NB) were assessed by stable isotopic methods on Muscle biopsies at baseline and 60 and 180 min following nutrient ingestion. Insulin increased 30 min postingestion in all groups and remained elevated in the EAA+CHO and EAA+ALA groups for 60 and 120 min, respectively. The fractional synthetic rate increased from baseline at 60 min in all groups (P < 0.05; EAA = 0.053 ± 0.018 to 0.090 ± 0.039% · h(-1); EAA+ALA = 0.051 ± 0.005 to 0.087 ± 0.015% · h(-1); EAA+CHO = 0.049 ± 0.006 to 0.115 ± 0.024% · h(-1)). MPS and NB peaked at 30 min in the EAA and EAA+CHO groups but at 60 min in the EAA+ALA group and NB was elevated above baseline longer in the EAA+ALA group than in the EAA group (P < 0.05). Although responses were more robust in the EAA+CHO group and prolonged in the EAA+ALA group, AUCs were similar among all groups for fractional synthetic rate, MPS, MPB, and NB. Because the overall Muscle Protein anabolic response was not improved in either the EAA+ALA or EAA+CHO group compared with EAA, we conclude that Protein nutritional interventions to enhance Muscle Protein anabolism do not require such additional energy.
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a moderate acute increase in physical activity enhances nutritive flow and the Muscle Protein anabolic response to mixed nutrient intake in older adults
The American Journal of Clinical Nutrition, 2012Co-Authors: Kyle L Timmerman, Erin L Glynn, Micah J Drummond, Blake B. Rasmussen, Shaheen Dhanani, Christopher S Fry, Kristofer Jennings, Elena VolpiAbstract:Background: Nutrient stimulation of Muscle Protein anabolism is blunted with aging and may contribute to the development and progression of sarcopenia in older adults. This is likely due to insulin resistance of Protein metabolism and/or endothelial dysfunction with a reduction in nutritive flow, both of which can be improved by aerobic exercise. Objective: Our objective was to determine whether increasing physical activity can enhance the Muscle Protein anabolic effect of essential amino acid (EAA) + sucrose intake in older subjects by improving nutritive flow and/or insulin signaling. Design: Using a randomized crossover design, we measured in older subjects [n = 6, 70 ± 3 y of age, BMI (in kg/m2) of 25 ± 1] the acute effects of increasing physical activity with aerobic exercise, as compared with normal sedentary lifestyle, on the response of blood flow, microvascular perfusion, insulin signaling, and Muscle Protein kinetics to EAA+sucrose intake. Results: No differences between treatment groups were found in the basal state. The change from the basal state in blood flow, Muscle perfusion, phenylalanine delivery, net balance, and Muscle Protein synthesis during the consumption of EAA+sucrose was significantly higher after the exercise than after the control treatment (P < 0.05). Insulin signaling increased during EAA+sucrose ingestion in both groups (P < 0.05). Conclusions: Our data indicate that a prior bout of aerobic exercise increases the anabolic effect of nutrient intake in older adults. This effect appears to be mediated by an exercise-induced improvement in nutrient-stimulated vasodilation and nutrient delivery to Muscle rather than to improved insulin signaling. This trial was registered at clinicaltrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT00690534","term_id":"NCT00690534"}}NCT00690534.
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mammalian target of rapamycin complex 1 activation is required for the stimulation of human skeletal Muscle Protein synthesis by essential amino acids
Journal of Nutrition, 2011Co-Authors: Jared M Dickinson, Erin L Glynn, Micah J Drummond, Elena Volpi, Kyle L Timmerman, Shaheen Dhanani, Christopher S Fry, David M Gundermann, Dillon K Walker, Blake B. RasmussenAbstract:The relationship between mammalian target of rapamycin complex 1 (mTORC1) signaling and Muscle Protein synthesis during instances of amino acid surplus in humans is based solely on correlational data. Therefore, the goal of this study was to use a mechanistic approach specifically designed to determine whether increased mTORC1 activation is requisite for the stimulation of Muscle Protein synthesis following L-essential amino acid (EAA) ingestion in humans. Examination of Muscle Protein synthesis and signaling were performed on vastus lateralis Muscle biopsies obtained from 8 young (25 ± 2 y) individuals who were studied prior to and following ingestion of 10 g of EAA during 2 separate trials in a randomized, counterbalanced design. The trials were identical except during 1 trial, participants were administered a single oral dose of a potent mTORC1 inhibitor (rapamycin) prior to EAA ingestion. In response to EAA ingestion, an ~60% increase in Muscle Protein synthesis was observed during the control trial, concomitant with increased phosphorylation of mTOR (Ser(2448)), ribosomal S6 kinase 1 (Thr(389)), and eukaryotic initiation factor 4E binding Protein 1 (Thr(37/46)). In contrast, prior administration of rapamycin completely blocked the increase in Muscle Protein synthesis and blocked or attenuated activation of mTORC1-signaling Proteins. The inhibition of Muscle Protein synthesis and signaling was not due to differences in either extracellular or intracellular amino acid availability, because these variables were similar between trials. These data support a fundamental role for mTORC1 activation as a key regulator of human Muscle Protein synthesis in response to increased EAA availability. This information will be useful in the development of evidence-based nutritional therapies targeting mTORC1 to counteract Muscle wasting associated with numerous clinical conditions.
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pharmacological vasodilation improves insulin stimulated Muscle Protein anabolism but not glucose utilization in older adults
Diabetes, 2010Co-Authors: Kyle L Timmerman, Hans C Dreyer, Satoshi Fujita, Micah J Drummond, Melinda Sheffieldmoore, Blake B. Rasmussen, Shaheen Dhanani, Elena VolpiAbstract:OBJECTIVE Skeletal Muscle Protein metabolism is resistant to the anabolic action of insulin in healthy, nondiabetic older adults. This defect is associated with impaired insulin-induced vasodilation and mTORC1 signaling. We hypothesized that, in older subjects, pharmacological restoration of insulin-induced capillary recruitment would improve the response of Muscle Protein synthesis and anabolism to insulin. RESEARCH DESIGN AND METHODS Twelve healthy, nondiabetic older subjects (71 ± 2 years) were randomized to two groups. Subjects were studied at baseline and during local infusion in one leg of insulin alone (Control) or insulin plus sodium nitroprusside (SNP) at variable rate to double leg blood flow. We measured leg blood flow by dye dilution; Muscle microvascular perfusion with contrast enhanced ultrasound; Akt/mTORC1 signaling by Western blotting; and Muscle Protein synthesis, amino acid, and glucose kinetics using stable isotope methodologies. RESULTS There were no baseline differences between groups. Blood flow, Muscle perfusion, phenylalanine delivery to the leg, and intracellular availability of phenylalanine increased significantly ( P P −1 · 100 ml · leg −1 ) increased significantly ( P CONCLUSIONS Pharmacological enhancement of Muscle perfusion and amino acid availability during hyperinsulinemia improves the Muscle Protein anabolic effect of insulin in older adults.
Blake B. Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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addition of carbohydrate or alanine to an essential amino acid mixture does not enhance human skeletal Muscle Protein anabolism
Journal of Nutrition, 2013Co-Authors: Erin L Glynn, Micah J Drummond, Elena Volpi, Kyle L Timmerman, Christopher S Fry, Blake B. RasmussenAbstract:In humans, essential amino acids (EAAs) stimulate Muscle Protein synthesis (MPS) with no effect on Muscle Protein breakdown (MPB). Insulin can stimulate MPS, and carbohydrates (CHOs) and insulin decrease MPB. Net Protein balance (NB; indicator of overall anabolism) is greatest when MPS is maximized and MPB is minimized. To determine whether adding CHO or a gluconeogenic amino acid to EAAs would improve NB compared with EAA alone, young men and women (n = 21) ingested 10 g EAA alone, with 30 g sucrose (EAA+CHO), or with 30 g alanine (EAA+ALA). The fractional synthetic rate and phenylalanine kinetics (MPS, MPB, NB) were assessed by stable isotopic methods on Muscle biopsies at baseline and 60 and 180 min following nutrient ingestion. Insulin increased 30 min postingestion in all groups and remained elevated in the EAA+CHO and EAA+ALA groups for 60 and 120 min, respectively. The fractional synthetic rate increased from baseline at 60 min in all groups (P < 0.05; EAA = 0.053 ± 0.018 to 0.090 ± 0.039% · h(-1); EAA+ALA = 0.051 ± 0.005 to 0.087 ± 0.015% · h(-1); EAA+CHO = 0.049 ± 0.006 to 0.115 ± 0.024% · h(-1)). MPS and NB peaked at 30 min in the EAA and EAA+CHO groups but at 60 min in the EAA+ALA group and NB was elevated above baseline longer in the EAA+ALA group than in the EAA group (P < 0.05). Although responses were more robust in the EAA+CHO group and prolonged in the EAA+ALA group, AUCs were similar among all groups for fractional synthetic rate, MPS, MPB, and NB. Because the overall Muscle Protein anabolic response was not improved in either the EAA+ALA or EAA+CHO group compared with EAA, we conclude that Protein nutritional interventions to enhance Muscle Protein anabolism do not require such additional energy.
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a moderate acute increase in physical activity enhances nutritive flow and the Muscle Protein anabolic response to mixed nutrient intake in older adults
The American Journal of Clinical Nutrition, 2012Co-Authors: Kyle L Timmerman, Erin L Glynn, Micah J Drummond, Blake B. Rasmussen, Shaheen Dhanani, Christopher S Fry, Kristofer Jennings, Elena VolpiAbstract:Background: Nutrient stimulation of Muscle Protein anabolism is blunted with aging and may contribute to the development and progression of sarcopenia in older adults. This is likely due to insulin resistance of Protein metabolism and/or endothelial dysfunction with a reduction in nutritive flow, both of which can be improved by aerobic exercise. Objective: Our objective was to determine whether increasing physical activity can enhance the Muscle Protein anabolic effect of essential amino acid (EAA) + sucrose intake in older subjects by improving nutritive flow and/or insulin signaling. Design: Using a randomized crossover design, we measured in older subjects [n = 6, 70 ± 3 y of age, BMI (in kg/m2) of 25 ± 1] the acute effects of increasing physical activity with aerobic exercise, as compared with normal sedentary lifestyle, on the response of blood flow, microvascular perfusion, insulin signaling, and Muscle Protein kinetics to EAA+sucrose intake. Results: No differences between treatment groups were found in the basal state. The change from the basal state in blood flow, Muscle perfusion, phenylalanine delivery, net balance, and Muscle Protein synthesis during the consumption of EAA+sucrose was significantly higher after the exercise than after the control treatment (P < 0.05). Insulin signaling increased during EAA+sucrose ingestion in both groups (P < 0.05). Conclusions: Our data indicate that a prior bout of aerobic exercise increases the anabolic effect of nutrient intake in older adults. This effect appears to be mediated by an exercise-induced improvement in nutrient-stimulated vasodilation and nutrient delivery to Muscle rather than to improved insulin signaling. This trial was registered at clinicaltrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT00690534","term_id":"NCT00690534"}}NCT00690534.
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mammalian target of rapamycin complex 1 activation is required for the stimulation of human skeletal Muscle Protein synthesis by essential amino acids
Journal of Nutrition, 2011Co-Authors: Jared M Dickinson, Erin L Glynn, Micah J Drummond, Elena Volpi, Kyle L Timmerman, Shaheen Dhanani, Christopher S Fry, David M Gundermann, Dillon K Walker, Blake B. RasmussenAbstract:The relationship between mammalian target of rapamycin complex 1 (mTORC1) signaling and Muscle Protein synthesis during instances of amino acid surplus in humans is based solely on correlational data. Therefore, the goal of this study was to use a mechanistic approach specifically designed to determine whether increased mTORC1 activation is requisite for the stimulation of Muscle Protein synthesis following L-essential amino acid (EAA) ingestion in humans. Examination of Muscle Protein synthesis and signaling were performed on vastus lateralis Muscle biopsies obtained from 8 young (25 ± 2 y) individuals who were studied prior to and following ingestion of 10 g of EAA during 2 separate trials in a randomized, counterbalanced design. The trials were identical except during 1 trial, participants were administered a single oral dose of a potent mTORC1 inhibitor (rapamycin) prior to EAA ingestion. In response to EAA ingestion, an ~60% increase in Muscle Protein synthesis was observed during the control trial, concomitant with increased phosphorylation of mTOR (Ser(2448)), ribosomal S6 kinase 1 (Thr(389)), and eukaryotic initiation factor 4E binding Protein 1 (Thr(37/46)). In contrast, prior administration of rapamycin completely blocked the increase in Muscle Protein synthesis and blocked or attenuated activation of mTORC1-signaling Proteins. The inhibition of Muscle Protein synthesis and signaling was not due to differences in either extracellular or intracellular amino acid availability, because these variables were similar between trials. These data support a fundamental role for mTORC1 activation as a key regulator of human Muscle Protein synthesis in response to increased EAA availability. This information will be useful in the development of evidence-based nutritional therapies targeting mTORC1 to counteract Muscle wasting associated with numerous clinical conditions.
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pharmacological vasodilation improves insulin stimulated Muscle Protein anabolism but not glucose utilization in older adults
Diabetes, 2010Co-Authors: Kyle L Timmerman, Hans C Dreyer, Satoshi Fujita, Micah J Drummond, Melinda Sheffieldmoore, Blake B. Rasmussen, Shaheen Dhanani, Elena VolpiAbstract:OBJECTIVE Skeletal Muscle Protein metabolism is resistant to the anabolic action of insulin in healthy, nondiabetic older adults. This defect is associated with impaired insulin-induced vasodilation and mTORC1 signaling. We hypothesized that, in older subjects, pharmacological restoration of insulin-induced capillary recruitment would improve the response of Muscle Protein synthesis and anabolism to insulin. RESEARCH DESIGN AND METHODS Twelve healthy, nondiabetic older subjects (71 ± 2 years) were randomized to two groups. Subjects were studied at baseline and during local infusion in one leg of insulin alone (Control) or insulin plus sodium nitroprusside (SNP) at variable rate to double leg blood flow. We measured leg blood flow by dye dilution; Muscle microvascular perfusion with contrast enhanced ultrasound; Akt/mTORC1 signaling by Western blotting; and Muscle Protein synthesis, amino acid, and glucose kinetics using stable isotope methodologies. RESULTS There were no baseline differences between groups. Blood flow, Muscle perfusion, phenylalanine delivery to the leg, and intracellular availability of phenylalanine increased significantly ( P P −1 · 100 ml · leg −1 ) increased significantly ( P CONCLUSIONS Pharmacological enhancement of Muscle perfusion and amino acid availability during hyperinsulinemia improves the Muscle Protein anabolic effect of insulin in older adults.
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Muscle Protein breakdown has a minor role in the Protein anabolic response to essential amino acid and carbohydrate intake following resistance exercise
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2010Co-Authors: Erin L Glynn, Hans C Dreyer, Micah J Drummond, Elena Volpi, Shaheen Dhanani, Christopher S Fry, Blake B. RasmussenAbstract:Muscle Protein breakdown (MPB) is increased following resistance exercise, but ingestion of carbohydrate during postexercise recovery can decrease MPB with no effect on Muscle Protein synthesis (MPS). We sought to determine whether a combination of essential amino acids (EAA) with low carbohydrate or high carbohydrate could effectively reduce MPB following resistance exercise and improve Muscle Protein net balance (NB). We hypothesized that higher levels of carbohydrate and resulting increases in circulating insulin would inhibit MPB and associated signaling, resulting in augmented NB. Thirteen male subjects were assigned to one of two groups receiving equivalent amounts of EAA (approximately 20 g) but differing carbohydrate levels (low = 30, high = 90 g). Groups ingested nutrients 1 h after an acute bout of leg resistance exercise. Leg phenylalanine kinetics (e.g., MPB, MPS, NB), signaling Proteins, and mRNA expression were assessed on successive Muscle biopsies using stable isotopic techniques, immunoblotting, and real-time quantitative PCR, respectively. MPB tended to decrease (P < 0.1) and MPS increased (P < 0.05) similarly in both groups following nutrient ingestion. No group differences were observed, but Muscle ring finger 1 (MuRF1) Protein content and MuRF1 mRNA expression increased following resistance exercise and remained elevated following nutrient ingestion, while autophagy marker (light-chain 3B-II) decreased after nutrient ingestion (P < 0.05). Forkhead box-O3a phosphorylation, total Muscle atrophy F-box (MAFbx) Protein, and MAFbx and caspase-3 mRNA expression were unchanged. We conclude that the enhanced Muscle Protein anabolic response detected when EAA+carbohydrate are ingested postresistance exercise is primarily due to an increase in MPS with minor changes in MPB, regardless of carbohydrate dose or circulating insulin level.
Luc J C Van Loon - One of the best experts on this subject based on the ideXlab platform.
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aging is accompanied by a blunted Muscle Protein synthetic response to Protein ingestion
PLOS ONE, 2015Co-Authors: Benjamin T Wall, Lex B Verdijk, Rene Koopman, Stefan H.m. Gorissen, Bart Pennings, Bart B L Groen, Luc J C Van LoonAbstract:Purpose Progressive loss of skeletal Muscle mass with aging (sarcopenia) forms a global health concern. It has been suggested that an impaired capacity to increase Muscle Protein synthesis rates in response to Protein intake is a key contributor to sarcopenia. We assessed whether differences in post-absorptive and/or post-prandial Muscle Protein synthesis rates exist between large cohorts of healthy young and older men.
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The Muscle Protein synthetic response to food ingestion
Meat Science, 2015Co-Authors: Stefan H.m. Gorissen, Didier Remond, Luc J C Van LoonAbstract:Preservation of skeletal Muscle mass is of great importance for maintaining both metabolic health and functional capacity. Muscle mass maintenance is regulated by the balance between Muscle Protein breakdown and synthesis rates. Both Muscle Protein breakdown and synthesis rates have been shown to be highly responsive to physical activity and food intake. Food intake, and Protein ingestion in particular, directly stimulates Muscle Protein synthesis rates. The postprandial Muscle Protein synthetic response to feeding is regulated on a number of levels, including dietary Protein digestion and amino acid absorption, splanchnic amino acid retention, postprandial insulin release, skeletal Muscle tissue perfusion, amino acid uptake by Muscle, and intramyocellular signaling. The postprandial Muscle Protein synthetic response to feeding is blunted in many conditions characterized by skeletal Muscle loss, such as aging and Muscle disuse. Therefore, it is important to define food characteristics thatmodulate postprandial Muscle Proteinsynthesis. Previouswork has shownthat the Muscle Protein synthetic response to feeding can be modulated by changing the amount of Protein ingested, the source of dietary Protein, as well as the timing of Protein consumption. Most of this work has studied the postprandial response to the ingestion of isolated Protein sources. Only few studies have investigated the postprandial Muscle Protein synthetic response to the ingestion of Protein dense foods, such as dairy and meat. The current review will focus on the capacity of Proteins and Protein dense food products to stimulate postprandial Muscle Protein synthesis and identifies food characteristics that may modulate the anabolic properties.
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carbohydrate coingestion delays dietary Protein digestion and absorption but does not modulate postprandial Muscle Protein accretion
The Journal of Clinical Endocrinology and Metabolism, 2014Co-Authors: Stefan H.m. Gorissen, Nicholas A Burd, Annemie P Gijsen, Bart B L Groen, Henrike M Hamer, Luc J C Van LoonAbstract:Background: Dietary Protein digestion and absorption is an important factor modulating Muscle Protein accretion. However, there are few data available on the effects of coingesting other macronutrients with Protein on digestion and absorption kinetics and the subsequent Muscle Protein synthetic response. Objective: The objective of the study was to determine the impact of carbohydrate coingestion with Protein on dietary Protein digestion and absorption and Muscle Protein accretion in healthy young and older men. Design: Twenty-four healthy young (aged 21± 1 y, body mass index 21.8 ±0.5 kg/m2) and 25 older (aged 75 ± 1 y, body mass index 25.4 ± 0.6 kg/m2) men received a primed continuous L-[ring-2H5]-phenylalanine and L-[ring-3,5-2H2]-tyrosine infusion and ingested 20 g intrinsically L-[1-13C]-phenylalanine-labeled Protein with (Pro+CHO) or without (Pro) 60 g carbohydrate. Plasma samples and Muscle biopsies were collected in a postabsorptive and postprandial state. Results: Carbohydrate coingestion delayed...
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disuse impairs the Muscle Protein synthetic response to Protein ingestion in healthy men
The Journal of Clinical Endocrinology and Metabolism, 2013Co-Authors: Benjamin T Wall, Lex B Verdijk, Tim Snijders, Joan M G Senden, Chris Lp P Ottenbros, Annemie P Gijsen, Luc J C Van LoonAbstract:Background: Disuse leads to rapid skeletal Muscle atrophy, which brings about numerous negative health consequences. Muscle disuse atrophy is, at least in part, attributed to a decline in basal (postabsorptive) Muscle Protein synthesis rates. However, it remains to be determined whether Muscle disuse also impairs the Muscle Protein synthetic response to dietary Protein ingestion. Purpose: We assessed Muscle Protein synthesis rates after Protein ingestion before and after a period of disuse in humans. Methods: Twelve healthy young (24 ± 1 year) men underwent a 14-day period of one-legged knee immobilization by way of a full leg cast. Before and after the immobilization period, quadriceps cross-sectional area, Muscle strength, skeletal Muscle Protein synthesis rates, and associated im (intramuscular) molecular signaling were assessed. Continuous infusions of l-[ring-2H5]phenylalanine were applied to assess mixed-Muscle Protein fractional synthetic rates after the ingestion of 20 g dietary Protein. Results: ...
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anabolic resistance of Muscle Protein synthesis with aging
Exercise and Sport Sciences Reviews, 2013Co-Authors: Nicholas A Burd, Stefan H.m. Gorissen, Luc J C Van LoonAbstract:Aging has been associated with a reduced Muscle Protein synthetic response to Protein intake, termed “anabolic resistance.” Physical activity performed before Protein intake increases the use of Protein-derived amino acids for postprandial Muscle Protein accretion in senescent Muscle. Thus, the leve
Stuart M. Phillips - One of the best experts on this subject based on the ideXlab platform.
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skeletal Muscle Protein metabolism in the elderly interventions to counteract the anabolic resistance of ageing
Nutrition & Metabolism, 2011Co-Authors: Leigh Breen, Stuart M. PhillipsAbstract:Age-related Muscle wasting (sarcopenia) is accompanied by a loss of strength which can compromise the functional abilities of the elderly. Muscle Proteins are in a dynamic equilibrium between their respective rates of synthesis and breakdown. It has been suggested that age-related sarcopenia is due to: i) elevated basal-fasted rates of Muscle Protein breakdown, ii) a reduction in basal Muscle Protein synthesis (MPS), or iii) a combination of the two factors. However, basal rates of Muscle Protein synthesis and breakdown are unchanged with advancing healthy age. Instead, it appears that the Muscles of the elderly are resistant to normally robust anabolic stimuli such as amino acids and resistance exercise. Ageing Muscle is less sensitive to lower doses of amino acids than the young and may require higher quantities of Protein to acutely stimulate equivalent Muscle Protein synthesis above rest and accrue Muscle Proteins. With regard to dietary Protein recommendations, emerging evidence suggests that the elderly may need to distribute Protein intake evenly throughout the day, so as to promote an optimal per meal stimulation of MPS. The branched-chain amino acid leucine is thought to play a central role in mediating mRNA translation for MPS, and the elderly should ensure sufficient leucine is provided with dietary Protein intake. With regards to physical activity, lower, than previously realized, intensity high-volume resistance exercise can stimulate a robust Muscle Protein synthetic response similar to traditional high-intensity low volume training, which may be beneficial for older adults. Resistance exercise combined with amino acid ingestion elicits the greatest anabolic response and may assist elderly in producing a 'youthful' Muscle Protein synthetic response provided sufficient Protein is ingested following exercise.
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effect of glycogen availability on human skeletal Muscle Protein turnover during exercise and recovery
Journal of Applied Physiology, 2010Co-Authors: Krista R Howarth, Stuart M. Phillips, Maureen J Macdonald, Douglas Richards, Natalie A Moreau, Martin J GibalaAbstract:We examined the effect of carbohydrate (CHO) availability on whole body and skeletal Muscle Protein utilization at rest, during exercise, and during recovery in humans. Six men cycled at ∼75% peak ...
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the role of milk and soy based Protein in support of Muscle Protein synthesis and Muscle Protein accretion in young and elderly persons
Journal of The American College of Nutrition, 2009Co-Authors: Stuart M. Phillips, Jason E Tang, Daniel R MooreAbstract:The balance between Muscle Protein synthesis (MPS) and Muscle Protein breakdown (MPB) is dependent on Protein consumption and the accompanying hyperaminoacidemia, which stimulates a marked rise in MPS and mild suppression of MPB. In the fasting state, however, MPS declines sharply and MPB is increased slightly. Ultimately, the balance between MPS and MPB determines the net rate of Muscle growth. Accretion of new Muscle mass beyond that of normal growth can occur following periods of intense resistance exercise. Such Muscle accretion is an often sought-after goal of athletes. There needs to be, however, an increased appreciation of the role that preservation of Muscle can play in offsetting morbidities associated with the sarcopenia of aging, such as type 2 diabetes and declines in metabolic rate that can lead to fat mass accumulation followed by the onset or progression of obesity. Emerging evidence shows that consumption of different types of Proteins can have different stimulatory effects on the amplitude and possibly duration that MPS is elevated after feeding; this may be particularly significant after resistance exercise. This effect may be due to differences in the fundamental amino acid composition of the Protein (i.e., its amino acid score) and its rate of digestion. Milk Proteins, specifically casein and whey, are the highest quality Proteins and are quite different in terms of their rates of digestion and absorption. New data suggest that whey Protein is better able to support MPS than is soy Protein, a finding that may explain the greater ability of whey Protein to support greater net Muscle mass gains with resistance exercise. This review focuses on evidence showing the differences in responses of MPS, and ultimately Muscle Protein accretion, to consumption of milk- and soy-based supplemental Protein sources in humans.
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minimal whey Protein with carbohydrate stimulates Muscle Protein synthesis following resistance exercise in trained young men
Applied Physiology Nutrition and Metabolism, 2007Co-Authors: Jason E Tang, Daniel R Moore, Joshua J Manolakos, Greg Kujbidag W W Kujbida, Paul J Lysecki, Stuart M. PhillipsAbstract:Whey Protein is a supplemental Protein source often used by athletes, particularly those aiming to gain Muscle mass; however, direct evidence for its efficacy in stimulating Muscle Protein synthesis (MPS) is lacking. We aimed to determine the impact of consuming whey Protein on skeletal Muscle Protein turnover in the post-exercise period. Eight healthy resistance-trained young men (age = 21 ± 1 .0 years; BMI = 26.8 ± 0.9 kg/m2 (means ± SE)) participated in a double-blind randomized crossover trial in which they performed a unilateral leg resistance exercise workout (EX: 4 sets of knee extensions and 4 sets of leg press; 8–10 repetitions/set; 80% of maximal), such that one leg was not exercised and acted as a rested (RE) comparator. After exercise, subjects consumed either an isoenergetic whey Protein plus carbohydrate beverage (WHEY: 10 g Protein and 21 g fructose) or a carbohydrate-only beverage (CHO: 21 g fructose and 10 g maltodextran). Subjects received pulse-tracer injections of l-[ring-2H5]phenylala...
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Consumption of fluid skim milk promotes greater Muscle Protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-Protein beverage
American Journal of Clinical Nutrition, 2007Co-Authors: Sarah B. Wilkinson, Jay R. Macdonald, Maureen J Macdonald, Mark A Tarnopolsky, David Armstrong, Stuart M. PhillipsAbstract:Background:Resistance exercise leads to net Muscle Protein accretion through a synergistic interaction of exercise and feeding. Proteins from different sources may differ in their ability to support Muscle Protein accretion because of different patterns of postprandial hyperaminoacidemia. Objective:We examined the effect of consuming isonitrogenous, isoenergetic, and macronutrient-matched soy or milk beverages (18 g Protein, 750 kJ) on Protein kinetics and net Muscle Protein balance after resistance exercise in healthy young men. Our hypothesis was that soy ingestion would result in larger but transient hyperaminoacidemia compared with milk and that milk would promote a greater net balance because of lower but prolonged hyperaminoacidemia. Design:Arterial-venous amino acid balance and Muscle fractional synthesis rates were measured in young men who consumed fluid milk or a soy-Protein beverage in a crossover design after a bout of resistance exercise. Results:Ingestion of both soy and milk resulted in a positive net Protein balance. Analysis of area under the net balance curves indicated an overall greater net balance after milk ingestion (P < 0.05). The fractional synthesis rate in Muscle was also greater after milk consumption (0.10 {+/-} 0.01%/h) than after soy consumption (0.07 {+/-} 0.01%/h; P = 0.05). Conclusions:Milk-based Proteins promote Muscle Protein accretion to a greater extent than do soy-based Proteins when consumed after resistance exercise. The consumption of either milk or soy Protein with resistance training promotes Muscle mass maintenance and gains, but chronic consumption of milk Proteins after resistance exercise likely supports a more rapid lean mass accrual.\n
