Calorie restriction accelerates the catabolism of lean body mass during 2 wk of bed rest.

Background: Muscle inactivity and low energy intake commonly occur in persons with acute or chronic disease, in astronauts during space flight, and during aging.

Objective: We used a crossover design to investigate the effects of the interactions of inactivity and calorie restriction on whole-body composition and protein kinetic regulation in 9 healthy volunteers.

Design: Lean body mass (LBM) was measured by using dual-energy X-ray absorptionmetry before and at the end of 14-d periods of bed rest (B) and controlled ambulation (A) in patients receiving eucaloric (E) or hypocaloric (H) (approximately 80% of total energy expenditure) diets.

Relationships between desacylated and acylated ghrelin and insulin sensitivity in the metabolic syndrome.

Context: Metabolic syndrome shows clustered metabolic abnormalities with major roles for insulin resistance and obesity. Ghrelin is a gastric hormone whose total plasma concentration (T-Ghr) is associated positively with insulin sensitivity and is reduced in obesity. Ghrelin circulates in acylated (A-Ghr) and desacylated (D-Ghr) forms, but their potential differential associations with insulin resistance and whether they are differentially altered in obesity remain undefined.

Response of muscle protein and glutamine kinetics to branched-chain-enriched amino acids in intensive care patients after radical cancer surgery.

Objective: Patients with cancer are characterized by decreased muscle protein synthesis and glutamine availability that contribute to an impaired immune response. These abnormalities worsen after surgical stress. We tested the hypothesis that pharmacologic doses of branched-chain amino acids would improve the early metabolic response after major cancer surgery.

Muscle glutamine depletion in the intensive care unit.

Glutamine is primarily synthesized in skeletal muscle and enables transfer of nitrogen to splanchnic tissues, kidneys and immune system. Discrepancy between increasing rates of glutamine utilization at whole body level and relative impairment of de novo synthesis in skeletal muscle leads to systemic glutamine deficiency and characterizes critical illness. Glutamine depletion at whole body level may contribute to gut, liver and immune system disfunctions, whereas its intramuscular deficiency may directly contribute to lean body mass loss.