We recently demonstrated that muscle protein synthesis was stimulated to a similar extent in young and elderly subjects during a 3-h amino acid infusion. We sought to determine if a more practical bolus oral ingestion would also produce a similar response in young (34 Ϯ 4 yr) and elderly (67 Ϯ 2 yr) individuals. Arteriovenous blood samples and muscle biopsies were obtained during a primed (2.0 mol/kg) constant infusion (0.05Muscle protein kinetics and mixed muscle fractional synthetic rate (FSR) were calculated before and after the bolus ingestion of 15 g of essential amino acids (EAA) in young (n ϭ 6) and elderly (n ϭ 7) subjects. After EAA ingestion, the rate of increase in femoral artery phenylalanine concentration was slower in elderly subjects but remained elevated for a longer period. EAA ingestion increased FSR in both age groups by ϳ0.04%/h (P Ͻ 0.05). However, muscle intracellular (IC) phenylalanine concentration remained significantly higher in elderly subjects at the completion of the study (young: 115.6 Ϯ 5.4 nmol/ml; elderly: 150.2 Ϯ 19.4 nmol/ml). Correction for the free phenylalanine retained in the muscle IC pool resulted in similar net phenylalanine uptake values in the young and elderly. EAA ingestion increased plasma insulin levels in young (6.1 Ϯ 1.2 to 21.3 Ϯ 3.1 IU/ml) but not in elderly subjects (3.0 Ϯ 0.6 to 4.3 Ϯ 0.4 IU/ml). Despite differences in the time course of plasma phenylalanine kinetics and a greater residual IC phenylalanine concentration, amino acid supplementation acutely stimulated muscle protein synthesis in both young and elderly individuals.

No abstract

Integra can be used for immediate wound coverage in children with severe burns without the associated risks of cadaver skin.

It is recognized that both whey protein and essential amino acids (EAA) are stimuli for muscle protein anabolism. The aim of the present study was to determine if the effects of whey protein ingestion on muscle protein accrual in elderly are due solely to its constituent EAA content. Fifteen elderly humans were randomly assigned to ingest a bolus of either 15 g of whey protein (WY), 6.72 g of essential amino acids (EAA), or 7.57 g of non-essential amino acids (NEAA). We utilized the leg arterio-venous model to measure the leg phenylalanine balance (PB), which is an index of muscle protein accrual. PB (nmol·min−1·kg lean leg mass−1) during the 3.5 hours following the bolus ingestion improved in the WY (−216 ± 14 vs −105 ± 19; P < .05) but not in the EAA (−203 ± 21 vs −172 ± 38; P > .05) or NEAA groups (−203 ± 19 vs −204 ± 21; P > .05). The insulin response (ulU·ml−1 210 min−1) during the same period was lower in both the NEAA (48 ± 40) and EAA (213 ± 127) when compared to the WY (1073 ± 229; P < .05). In conclusion, whey protein ingestion improves skeletal muscle protein accrual through mechanisms that are beyond those attributed to its essential amino acid content. This finding may have practical implications for the formulation of nutritional supplements to enhance muscle anabolism in older individuals.

orrhagic coagulopathy is involved in the morbidity and mortality of trauma patients. Nonetheless, many aspects of the mechanisms underlying this disorder are poorly understood. We have therefore investigated changes in fibrinogen metabolism and coagulation function after a moderate hemorrhagic shock, using a new stable isotope approach. Twelve pigs were randomly divided into the control (C) and hemorrhage (H) groups. Hemorrhage was induced by bleeding 35% total blood volume over a 30-min period. A primed constant infusion of [1-13 C]phenylalanine (Phe), d5-phenylalanine, and ␣-[1-13 C]-ketoisocaproate (KIC) was given to quantify fibrinogen synthesis and breakdown, together with measurements of circulating liver enzyme activities and coagulation function. Mean arterial pressure was decreased by hemorrhage from 89 Ϯ 4 mmHg in C to 47 Ϯ 4 mmHg in H (P Ͻ 0.05), followed by a rebound to 68 Ϯ 5 mmHg afterward. Fibrinogen fractional synthesis rate increased from 2.7 Ϯ 0.2%/h in C to 4.2 Ϯ 0.4%/h in H by Phe (P Ͻ 0.05) and from 3.1 Ϯ 0.4%/h in C to 4.4 Ϯ 0.5%/h in H by KIC (P Ͻ 0.05). Fibrinogen fractional breakdown rate increased from 3.6 Ϯ 1.0%/h in C to 12.9 Ϯ 1.8%/h in H (P Ͻ 0.05). The absolute breakdown rate accelerated from 3.0 Ϯ 0.4 mg ⅐ kg Ϫ1 ⅐ h Ϫ1 in C to 5.4 Ϯ 0.6 mg ⅐ kg Ϫ1 ⅐ h Ϫ1 in H (P Ͻ 0.05), but the absolute synthesis rate remained unchanged. These metabolic changes were accompanied by a reduction in blood clotting time to 92.7 Ϯ 1.6% of the baseline value by hemorrhage (P Ͻ 0.05). No changes were found in liver enzyme activities. We conclude that the observed changes in coagulation after hemorrhagic shock are mechanistically related to the acute acceleration of fibrinogen degradation. stable isotopes; fibrinogen metabolism; hemorrhage; coagulation HEMORRHAGIC COAGULOPATHY (without neurological injury) constitutes 40% of injury-related death in civilian hospitals and on the battlefield (1,3,15,18). Hemorrhagic coagulopathy includes an initial hypercoagulable state that may result in consumptive depletion of fibrinogen and progress to disseminated intravascular coagulation (DIC; see Refs. 2,7,8,11,12,18,22). DIC results in a paradoxical situation in which patients are hypocoagulable in terms of hemostasis and therefore cannot stop bleeding, and yet inappropriately deposit fibrin in the microvasculature, contributing to later organ failure in patients that survive the initial hemorrhagic insults. It appears that the availability and metabolism of fibrinogen may play a role in the development of the pathophysiological process. However, the relation between changes in fibrinogen metabolism to the development of clotting defects is poorly understood. The complexity of the clinical settings, such as tissue injury, blood loss, blood transfusion, and resuscitation, makes it difficult to clarify the mechanism contributing to the development of clotting disorders. Therefore, we have used an animal model that allowed us to define changes in fibrinogen metabolism under hemorrhage shock.The essence of the coagulat...