Showing papers by "Elena Volpi published in 2001"

Basal muscle amino acid kinetics and protein synthesis in healthy young and older men.

Abstract: ContextSarcopenia is associated with loss of strength and function, eventually leading to loss of independence. Some studies suggest that basal muscle protein turnover is reduced with aging, but other studies do not confirm this finding.ObjectiveTo determine if aging per se affects basal muscle protein turnover in men.Design and SettingCross-sectional study conducted from June 1997 to July 2000 in a general US community.ParticipantsTwenty-six young (mean [SE] age, 28 [2] years) and 22 older (mean [SE] age, 70 [1] years) men, who were healthy and independent based on activities of daily living, physical examinations, and screening tests. Subjects were excluded if they had cardiac, pulmonary, liver, or kidney disease; any impairment in activities of daily living; or steroid use.Main Outcome MeasuresWe measured basal muscle protein and amino acid kinetics, based on stable isotope techniques with femoral arteriovenous catheterization and muscle biopsies. Three models (arteriovenous balance, three-pool, and fractional synthesis rate) were used to estimate the metabolic parameters.ResultsMean (SE) total leg volume was 9.60 (0.32) L in older men vs 10.83 (0.43) L in younger men, which suggests muscle loss in the older men. Net muscle protein balance was similar in both groups (older men, − 19 [2] nmol/min per 100 mL of leg volume vs younger men, − 21 [2] nmol/min per 100 mL of leg volume; P = .51). Small differences were found in mean (SE) muscle protein synthesis in comparisons of older vs younger men: arteriovenous balance, 48 (5) nmol/min per 100 mL of leg volume vs 32 (3) nmol/min per 100 mL of leg volume; P = .004; three-pool, 58 (5) nmol/min per 100 mL of leg volume vs 43 (4) nmol/min per 100 mL of leg volume; P = .04; and fractional synthesis rate, 0.0601 (0.0046) %/h vs 0.0578 (0.0047) %/h; P = .73. Small differences were also found in mean (SE) muscle protein breakdown: arteriovenous balance, 66 (5) nmol/min per 100 mL of leg volume in older vs 53 (4) nmol/min per 100 mL of leg volume in younger men, P = .045; and three-pool, 76 (6) nmol/min per 100 mL of leg volume vs 64 (5) nmol/min per 100 mL of leg volume, P = .14.ConclusionDifferences in basal muscle protein turnover between older and younger men do not appear to explain muscle loss that occurs with age.

Whole body and skeletal muscle glutamine metabolism in healthy subjects

Abstract: We measured glutamine kinetics usingl-[5-15N]glutamine andl-[ring-2H5]phenylalanine infusions in healthy subjects in the postabsorptive state and during ingestion of an amino acid mixture that incl...

Insulin and Protein Metabolism

Abstract: The sections in this article are: 1 Molecular Basis of Insulin Action on Protein Metabolism 1.1 Protein Synthesis 1.2 Protein Breakdown 1.3 Transmembrane Amino Acid Transport 2 Physiological Effects of Insulin at the Whole-Body Level 3 Effects of Insulin on Muscle Tissue 4 Physiological Effects of Insulin on Other Tissues 4.1 Liver 4.2 Gut 4.3 Heart 4.4 Skin 5 Effect of Insulin on Transport in vivo 6 Insulin Resistance 6.1 Diabetes 6.2 Critical Illness 7 Exercise 8 Conclusion

Ethanol and protein metabolism.

Abstract: This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Carol C. Cunningham and Victor R. Preedy. The presentations were (1) Ribosomal content, ribosomal localization and the levels of ribosomal protein mRNA and rRNA in rat skeletal muscle exposed to ethanol, by Alistair G. Paice, John E. Hesketh, Timothy J. Peters, and Victor R. Preedy; (2) Altered hepatic mitochondrial ribosome structure after chronic ethanol administration, by Vinood B. Patel and Carol C. Cunningham; (3) Clinical aspects of hepatic protein metabolism and alcohol, by Elena Volpi; and (4) Effects of oral intake of alanine plus glutamine on ethanol metabolism and ethanol-related depression in motor activity, by Kazunori Mawatari, H. Masaki, M. Mori, and Kunio Torii.