Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate specific effects of androgens on whole body metabolism, we studied six healthy lean men (mean +/- SEM age, 23.2 +/- 0.5 yr) before and after gonadal steroid suppression with a GnRH analog (Lupron), given twice, 3 weeks apart. Primed infusions of [13C]leucine, indirect calorimetry, isokinetic dynamometry, growth factor measurements, and percutaneous muscle biopsies were performed at baseline (D1) and after 10 weeks of treatment (D2); each subject served as his own control. Testosterone concentrations were markedly suppressed after 10 weeks of treatment (D1, 535 +/- 141 ng/dL; D2, 31 +/- 9). Leucine's rate of appearance (index of proteolysis) was markedly suppressed after 10 weeks of hypogonadism (-13%; P = 0.01) as well as the nonoxidative leucine disposal, an index of whole body protein synthesis (-13%; P = 0.01) without any changes in plasma amino acid concentrations. All subjects studied after 10 weeks showed a decrease in fat-free mass, as measured by skinfold calipers and dual emission x-ray absortiometry scans (D1, 56.5 +/- 2.9 kg; D2, 54.4 +/- 2.5; P = 0.005), and an increase in percent fat mass (D1, 19.2 +/- 2.5%; D2, 22.2 +/- 2.5; P = 0.001). Rates of lipid oxidation decreased (-31%; P = 0.05) after treatment, with parallel changes in resting energy expenditure (-9%; P = 0.05). Mean and peak GH concentrations (measured every 10 min for 6 h) and GH production rates did not decrease after testosterone deficiency, with an actual increase in basal secretion (P < 0.02). Plasma insulin-like growth factor I (IGF-I) concentrations did not change significantly after 10 weeks of treatment (D1, 227 +/- 44 micrograms/L; D2, 291 +/- 60; P = 0.08). Isokinetic dynamometry of leg extensors at 60 degrees and 180 degrees/s was also decreased after 10 weeks of hypogonadism. Total ribonucleic acid (RNA) was isolated from muscle biopsy samples, and ribonuclease protection assays were performed using human complementary DNA clones for IGF-I, IGF-binding protein-4, myosin, and actin. Ten weeks after Lupron treatment, messenger RNA (mRNA) concentrations of IGF-I decreased significantly, whereas there was a trend toward higher IGF-binding protein-4 concentrations, with no change in myosin or actin mRNA concentrations. In conclusion, testosterone deficiency in young men is associated with a marked decrease in measures of whole body protein anabolism, decreased strength, decreased fat oxidation, and increased adiposity. These effects of testosterone deficiency are independent of changes in peripheral GH production and IGF-I concentrations, even though im IGF-I mRNA concentrations decrease. These data suggest a direct effect of androgens on whole body lipid and protein metabolism.
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PMID:Testosterone deficiency in young men: marked alterations in whole body protein kinetics, strength, and adiposity. 962 14

The impact of estrogen deficiency on bone has been extensively studied in the female; however, the effects of androgen deficiency on calcium fluxes in males have been less well characterized. We investigated the effect of short-term, severe androgen deficiency on measures of calcium absorption and kinetics as well as on markers of bone turnover in males. To accomplish this, 11 healthy male volunteers were recruited (mean age 23.3 +/- 0.5 years [SEM], body mass index 25.3 +/- 0.8 kg/m2). They consumed a weight maintenance diet for at least 3 days prior to admission to our Research Unit, with a calcium intake of approximately 1200 mg/day. At baseline (D1), subjects received 42Ca intravenously as well as 44Ca PO mixed with milk or juice. A 29-h urine collection was begun and blood samples collected at frequent intervals for the measurement of the isotopic enrichment of 42Ca and 44Ca using thermal ionization mass spectrometry. Twice daily urine samples were collected for 5 days after the administration of the isotopes. A gonadotropin-releasing hormone agonist (Lupron) was given after D1, again 3 weeks later, and studies repeated identically 4 weeks (D2, n = 6) and 10 weeks from baseline (D3, n = 7) (two subjects completed three studies). Testosterone concentrations were markedly suppressed on both D2 and D3 (-95%, p < 0.006), whereas there were no detectable changes in growth hormone and insulin-like growth factor-1 concentrations. Urinary calcium excretion increased significantly after 4 weeks (43%, p = 0.0007) and 10 weeks (73%, p = 0.003) of sustained hypogonadism. Using a multicompartmental kinetic model, the contribution of oral calcium to the urinary losses was decreased by D3 (-41%, p = 0.01), yet the contribution of bone calcium to urine losses increased by 10 weeks (+11%, p = 0.01). There was a 21% decrease in bone calcium deposition (Vo+) by D3 (p < 0.05) with no significant change in bone resorption rates (Vo-). There was a significant correlation between the decrease in testosterone concentration and the increase in urinary calcium excretion, especially at 10 weeks (R2 = 0.84, p = 0.004). These kinetic changes were accompanied by a decrease in osteocalcin concentrations on D2, with improvements by D3. Urinary N telopeptide, a measure of bone resorption, also increased during the studies. In summary, profound hypogonadism in young males is associated with marked increases in urinary calcium losses, with a greater contribution of bone calcium to those losses and decreased kinetic markers of bone calcium deposition. We conclude that even short-term, severe deficiency in gonadal steroids can have profound negative effects on calcium and bone metabolism in males.
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PMID:Profound hypogonadism has significant negative effects on calcium balance in males: a calcium kinetic study. 1023 79