Responses of plasma adrenocorticotropin, cortisol, and dehydroepiandrosterone to ovine corticotropin-releasing hormone in healthy aging men.

To assess the effects of age on both the pituitary ACTH response to corticotropin-releasing hormone (CRH) and the secretory responses of cortisol (F) and dehydroepiandrosterone (DHEA) to endogenous rises in ACTH, we measured evening basal and ovine CRH (oCRH; 1 mu/kg)-stimulated plasma concentrations of ACTH,F, and DHEA in 49 healthy men, aged 21-86 yr. By analysis of variance, we found no change with age in either the basal concentration of ACTH or the magnitude of the peak ACTH response to oCRH. Older men had higher basal F levels (P less than 0.05), while basal plasma levels of CBG and ratios of F to CBG did not vary significantly with age (P greater than 0.1). We also found no significant increase with age in the magnitude of the peak F response to oCRH (P greater than 0.2), although peak F responses occurred significantly earlier (P less than 0.03) in the older men. Basal plasma levels of DHEA decreased significantly with age (P less than 0.001), as did the magnitude of peak DHEA responses to endogenous ACTH rises (P less than 0.01). There was no alteration in the timing of the peak DHEA response with age (P greater than 0.7). We conclude that while ACTH and F responses to evening injections of oCRH are well maintained in healthy aging men, that of DHEA is discordantly decreased. The present findings are compatible with the hypotheses that there is a diminished sensitivity of ACTH secretion to negative feedback regulation by glucocorticoids in older men, and there is an ACTH-independent age-related diminution in adrenal androgen secretion.

Responses of growth hormone (GH) and somatomedin-C to GH-releasing hormone in healthy aging men.

Although controversy exists regarding the effects of aging on GH secretory responses to indirect stimulation, in the only prior study of GH-releasing hormone (GHRH)-mediated GH secretion decreased GH responsivity occurred in healthy men after age 40 yr. We measured serum GH before and up to 180 min after and somatomedin-C (SM-C) levels before and 24 h after single morning bolus iv injections of GHRH-(1-44)-NH2 (1 microgram/kg) in 50 healthy fasted men, aged 21-86 yr, from the Baltimore Longitudinal Study of Aging. Only subjects with a body mass index (BMI; kilograms per m2) between 20.0 and 29.0 were studied. Basal serum GH levels were undetectable (less than 0.7 ng/ml) in all but 2 men. Neither the frequency of GH responses (P greater than 0.8), the magnitude of response (P greater than 0.2), nor the timing (P greater than 0.05) of the peak GH responses to GHRH were significantly altered with age. Although BMI values did not vary significantly with age in our study group, there was a significant negative correlation (r = -0.37; P less than 0.01) of peak GH with BMI. Regression analysis revealed a slight but significant increase in the level of fasting blood sugar with age, but no significant correlation between fasting blood sugar and peak GH levels. Serum levels of SM-C were significantly lower in older men both before (P less than 0.001) and 24 h after (P less than 0.02) GHRH injection. Repeated measures analysis of variance revealed significant (P less than 0.001) responses of SM-C to endogenous GH elevations produced by GHRH at all ages, but no age-dependent alterations in the magnitudes of these responses (P greater than 0.7). Our findings suggest that increasing age in adult men has little effect on the secretory responsiveness of pituitary somatotropes to GHRH. However, the finding of lower serum levels of SM-C with intact SM-C responsivity to endogenous GH is compatible with prior observations of an age-related decrease in the total daily spontaneous secretion of GH.

[Microbial decontamination of hospital linens using radiation]. / Mikrobnaia dekontaminatsiia bol'nichnogo bel'ia Radiatsionnym sposobom.

The irradiation of hospital linen contaminated with radioresistant microorganisms or hospital microflora with gamma radiation in a dose of 10 kGy ensures the reliable microbial decontamination of such linen. Cotton linen has been found capable of withstanding 15 irradiation cycles in a dose of 10 kGy.

[Effect of "pasteurizing" doses of ionizing radiations on the drug resistance of microorganisms isolated in pharmaceutical chemical manufacture]. / Vliianie "pasterizuiushchikh" doz ioniziruiushchikh izluchenii na lekarstvennuiu chuvstvitel'nost' mikroorganizmov, vydelennykh na khimiko-farmatsevticheskom proizvodstve.

Changes in the antibioticograms after a single irradiation of dry cultures of microorganisms isolated at a pharmaceutical factory were noted in 0.5 per cent of 686 microbial strains tested. Restoration of sensitivity to one or more often several antibiotics was found in the microbes with the changed antibioticograms. After a three-fold irradiation the value increased to 9 per cent. Development of the drug resistance in the microbes neither after the single nor after the three-fold irradiation was observed.