| Popis: |
Degenerative changes in body composition characterized by reduced muscle and bone mass decrease physical performance in the elderly. These decremental somatic changes correlate with reduced serum growth hormone (GH) concentrations. Limited availability of cadaver-derived hormone before the advent of recombinant gene technology precluded testing the functional relationship between GH deficiency and senescence. However, when bioengineered GH became available for experimentation, its administration to old men significantly increased serum IGF-I concentrations, urinary nitrogen retention, body weight gain, lean body mass, bone density, renal function, and improved quality of life (1–3). Thus, aberrant patterns of spontaneous GH secretion and low serum GH concentrations during aging (4–7) did not necessarily represent loss of GH efficacy. Furthermore, the experimental observations suggested a causal relationship between anatomical senescence and GH insufficiency (3, 4, 8, 9). |
