Background: Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations. Methods: We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography-mass spectrometry (ID/GC-MS).

To determine whether muscular contractions obtained by electrical stimulation in immobilized patients are able to reduce muscle catabolism, we studied 10 patients (65-79 yr old) hospitalized in the intensive care unit for postoperative ventilatory failure or cerebral infarction. Artificial nutrition was the same for each patient during the 9-day study period. Two periods of 4 days were defined and randomized for each patient, separated by one day. During the muscular stimulation (MS) period, intermittent electrical stimulation of the muscles of the legs (external electrodes), were performed daily during 2 X 30 mn. During the other period, muscular stimulations were not performed. Urinary excretion of nitrogen (micro-Kjeldhal digestion and Nessler procedure), creatinine (Jaffe reaction), and 3-methyl histidine (3-MH) (gas phase chromatography) was measured every day. (table; see text) We conclude that a significant decrease in 3-MH and creatinine excretion is observed during the MS period. In intensive care unit patients, muscle protein breakdown may be influenced by intermittent muscular electrical stimulation.

lower habitual physical activity is related to lower levels of circulating DHEAS and IGF-I independently of age and anthropometric measures. Lower maximal aerobic capacity is associated with lower DHEAS concentrations, in healthy elderly women.

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Activities of rat intestinal fucosyl-transferase (GDP-fucose: glycoprotein fucosyl-transferase; EC 2.4.1.68) and sialyl-transferase (N-acetylneuraminyl-transferase; EC 2.4.99.1) respectively exhibited a significant increase following weaning and a steady decrease between birth and weaning. The variations of the two glycosyl-transferase activities with age could not be explained by the presence of inhibitory factors in microsomes or cytosol, nor were they due to a natural modification of the milk composition at the end of lactation. The increase in fucosyl-transferase activity that followed weaning was prematurely induced by early weaning. Prolonged nursing prevented the normal increase in fucosyl-transferase activity, and late weaning delayed the increase. The sensitivity to the modification of the time of weaning indicated a major effect of dietary changes, related to the introduction of a solid carbohydrate-rich diet, on the developmental pattern of this enzyme. However, a stress response could not be excluded after early weaning since the corticosterone level of the early weaned rats was enhanced as compared to that of suckling rats. For sialyl-transferase, early weaning caused a slightly greater than normal decrease in the activity, whereas prolonged nursing only weakly diminished the normal decrease in the activity. Moreover, late weaning had no effect on the sialyl-transferase activity. The age-related variations of this enzyme likely are due to factors independent of diet. Thus, the developmental variations of the fucosyl- and sialyl-transferases appear to be differently regulated.