Lateralization and effects of adult androgen in a sexually dimorphic neuromuscular system controlling song in zebra finches.

Unlike many other sexually dimorphic systems, gonadal secretions do not explain sex differences in the morphology of the telencephalic song control nuclei of zebra finches. It is important to understand whether a novel mechanism for controlling structure is restricted to the forebrain regions specialized for song, and whether other areas respond more typically to gonadal steroids. Therefore, the effects of sex and adult androgen manipulation on the neuromuscular end of the song control system (tracheosyringeal portion of the hypoglossal nucleus, nXIIts, and the syrinx, or vocal organ) were investigated. Because lesion and axotomy experiments indicate a right-side bias in the functional control of song, asymmetry in the motor nucleus and in the ventralis and dorsalis syrinx muscles was also tested. Male-biased dimorphisms existed in the volume of nXIIts, and in syrinx mass and size of muscle fibers, but not in motoneuron number or size. Asymmetries favoring the right side were detected in nXIIts volume and motoneuron number in males, as well as in ventralis and dorsalis fiber size in both sexes. Hormone manipulations had no effect on nXIIts size, neuron size, or number. Testosterone treatment of adult females increased all of the syringeal measures, but the only effect of flutamide in males was to decrease syrinx weight. Thus, male-biased sexual dimorphisms and right side dominance in both nXIIts and the syrinx may facilitate singing behavior. Adult androgen exposure can induce partial masculinization of the syrinx, but other factors must be important in mediating the sex differences in both that structure and the volume of nXIIts.

Sterile versus clean technique in postoperative wound care of patients with open surgical wounds: a pilot study.

PURPOSE: This study was completed to determine whether there were differences between sterile versus clean dressing change technique for open surgical wounds in the postoperative period with respect to (1) rate of wound healing and (2) cost of supplies. METHODS: A two-group design was used for this pilot study. Of a sample of 30 patients undergoing elective gastrointestinal operations with wounds healing by secondary intention, 15 were men and 15 were women. Mean age was 40.6 years (SD 13.0 years). Patients were randomly assigned to receive clean or sterile dressings, and the intervention was begun on the first postoperative day and repeated three times a day until discharge from the hospital. Analysis of rate of healing was performed with the Mann-Whitney U test: cost analysis was completed with a t test. FINDINGS: Subjects were studied for 3 to 9 days. Groups were homogeneous of the start of treatment with respect to age, length of operation, wound volume, nutritional status, and perfusion. There was no difference in rate of wound healing between the clean and sterile groups. Mean cost was significantly less for the clean group than for the sterile group. CONCLUSION: These pilot study data show no difference in rate of wound healing with clean versus sterile technique, and clean technique is less expensive. These findings need to be confirmed with a larger sample; type II error cannot be ruled out.