Structure of the thyroid gland, serum thyroid hormones, and the reproductive cycle of the Atlantic stingray, Dasyatis sabina.

This study examines the role of the thyroid gland in the control of reproduction in the viviparous Atlantic stingray, Dasyatis sabina. Thyroid activity in individuals in different reproductive stages was assessed both by microscopic examination of the gland, and by analysis of circulating levels of thyroid hormones from the same individuals. The thyroid gland is a cylindric organ, embedded in a connective tissue capsule, and composed of follicles, i.e., monolayer spheres of thyroid epithelial cells. Stingray follicular cells possess several characteristic features, namely apical cilia and a well-developed endoplasmic reticulum. Cells vary in size and shape, according to the activity of the gland. No structural differences were observed between the thyroid glands of the two sexes. Both thyroid hormones, triiodothyronine, [T(3)], and thyroxine, [T(4)], were detected in the serum of all animals examined. Levels ranged from 1.3-2.6 microg/100 ml for total T(4), and from 1.2-2.6 ng/ml for total T(3). The T(4) levels did not vary significantly in any group. Immature individuals and females undergoing oogenesis had the lowest levels of circulating T(3) and mature females from ovulation throughout gestation had high thyroid gland activity and high levels of circulating T(3). J. Exp. Zool. 284:505-516, 1999.

Incidence of postoperative infection or positive culture after facial laser resurfacing: a pilot study, a case report, and a proposal for a rational approach to antibiotic prophylaxis.

BACKGROUND: Laser skin resurfacing (LSR) has emerged as a popular procedure for facial rejuvenation; however, there are no clear guidelines regarding systemic antibiotic prophylaxis. OBJECTIVE: We attempt to provide practical guidelines for antibiotic prophylaxis in LSR based on our experiences, pharmacology, and a review of the literature. METHODS: In a pilot study, four consecutive full-face LSR patients were treated without oral or topical antibiotics. The next four patients received oral prophylaxis with a narrow spectrum antibiotic. We also report the case of a severe gram-negative infection after LSR. RESULTS: For full-face LSR, 2 of 4 consecutive patients without antibiotic prophylaxis experienced focal Staphylococcus aureus infection. The next 4 consecutive patients, who had received gram-positive oral prophylaxis, were all culture negative after 2 days. All test sites (5 of 5) were culture negative despite the absence of systemic or topical antibiotics. One patient not in the pilot study receiving gram-positive antibiotic prophylaxis experienced a gram-negative infection. CONCLUSION: We recommend narrow-spectrum gram-positive oral antibiotic coverage for full-face and regional LSR.