Temporal study of the staphylococci and micrococci of normal infant skin

Staphylococcus and Micrococcus populations were collected from the healthy skin of 10 infant subjects. Infants were sampled from 1 day to 32 weeks of age. Species were characterized by approximately 30 different morphological, physiological, and biochemical characters. Staphylococci were the predominant inhabitants of normal skin, whereas micrococci were found only occasionally in this environment. Staphylococcus epidermidid, S. haemolyticus, and S. hominis were the predominant and persistent staphylococci. These species constituted a high percentage of the total aerobic bacterial flora of infant skin. Micrococcus luteus and M. kristinae were the prevalent micrococci found on infant skin. Only limited correlation between Staphyloccus and Micrococcus populations and infant age or body area sampled was indicated by this study.     

Increase in testicular androgen receptor during sexual maturation in the rat

Androgen receptor concentration was measured by exchange with 3H-dimethylnortestosterone (DMNT) in cytosol and nuclear extracts from testes of rats 15-90 days of age. Dissociation kinetics verified the necessity of an extended incubation (86 h) for maximum exchange at 4 degrees C. Nuclear androgen receptor concentration per mg DNA decreased between 15 and 25 days of age, from 375 to 146 fmol per mg DNA, then increased to 584 fmol per mg DNA at 90 days. Testicular receptor content also increased between 25 and 90 days of age. Cytosol receptor concentration patterns were similar to nuclear androgen receptor patterns. The affinity of the receptor for the ligand did not change with age (mean Kd = 0.88 nM). No significant difference in androgen receptor concentration per cell was detected between cultured peritubular cells from animals 25 and 45 days of age. Androgen receptor concentrations in freshly isolated peritubular cells could not be determined. There also was no difference in receptor concentration per cell in a Leydig cell-enriched fraction from animals between 25 and 45 days of age. Although androgen receptor concentrations per Sertoli cell increased between 15 and 35 days of age, the increase in Leydig cell number over the same period probably accounted for approximately 75% of the increase in receptor per testis between 25 and 45 days of age.