Testosterone Prevents Cutaneous Ischemia and Necrosis in Males Through Complementary Estrogenic and Androgenic Actions

OBJECTIVE

Chronic nonhealing wounds are a substantial medical concern and are associated with morbidity and mortality; thus, new treatment strategies are required. The first step toward personalized/precision medicine in this field is probably in taking sex differences into account. Impaired wound healing is augmented by ischemia, and we previously demonstrated that 17β-estradiol exerts a major preventive effect against ischemia-induced skin flap necrosis in female mice. However, the equivalent effects of testosterone in male mice have not yet been reported. We then investigated the role of steroid hormones in male mice using a skin flap ischemia model.

APPROACH AND RESULTS

Castrated male mice developed skin necrosis after ischemia, whereas intact or castrated males treated with testosterone were equally protected. Testosterone can (1) activate the estrogen receptor after its aromatization into 17β-estradiol or (2) be reduced into dihydrotestosterone, a nonaromatizable androgen that activates the androgen receptor. We found that dihydrotestosterone protected castrated wild-type mice by promoting skin revascularization, probably through a direct action on resistance arteries, as evidenced using a complementary model of flow-mediated outward remodeling. 17β-estradiol treatment of castrated male mice also strongly protected them from ischemic necrosis through the activation of estrogen receptor-α by increasing skin revascularization and skin survival. Remarkably, 17β-estradiol improved skin survival with a greater efficiency than dihydrotestosterone.

CONCLUSIONS

Testosterone provides males with a strong protection against cutaneous necrosis and acts through both its estrogenic and androgenic derivatives, which have complementary effects on skin survival and revascularization.

Multiple comparison procedure and modeling: a versatile tool for evaluating dose-response relationships in veterinary pharmacology - a case study with furosemide

Congestive heart failure (CHF) is a leading cause of mortality with an increasing prevalence in human and canine populations. While furosemide is a loop diuretic prescribed for the majority of CHF patients to reduce fluid retention, it also activates the renin-angiotensin aldosterone system (RAAS) which further contributes to the accelerated progression of heart failure. Our objective was to quantify the effect of furosemide on diuresis, renin activity (RA), and aldosterone (AL) in dogs, using a combined multiple comparisons and model-based approach (MCP-Mod). Twenty-four healthy beagle dogs were allocated to four treatment groups (saline vs. furosemide 1, 2, and 4 mg/kg i.m., q12 h for 5 days). Data from RA and AL values at furosemide trough concentrations, as well as 24-h Diuresis, were analyzed using the MCP-Mod procedure. A combination of E_max models adequately described the dose-response relationships of furosemide for the various endpoints. The dose-response curves of RA and AL were found to be well in agreement, with an apparent shallower slope compared with 24-h Diuresis. The research presented herein constitutes the first application of MCP-Mod in Veterinary Medicine. Our data show that furosemide produces a submaximal effect on diuresis at doses lower than those identified to activate the circulating RAAS.

Current research on ethnic hair

This study collected qualitative and quantitative data about the morphology, structure, geometry, water swelling, and mechanical properties of hair fibers from subjects of different ethnic origins. X-ray analysis, cross-sectional measurements, tensile testing, and water swelling were performed on samples of hair collected from Caucasian, Asian, and African subjects. No differences in the intimate structures of fibers were observed among these 3 types of hairs, whereas geometry, mechanical properties, and water swelling differed according to ethnic origin. In addition, the behavior of hair fiber under mechanical stress was visualized with environmental scanning electron microscopy.

Sleep and activity, age and fatness, and the energy expenditure of confined sheep

1. Changes in energy expenditure associated with sleep and activity, age and fatness were measured in sheep. States of vigilance were defined according to electrophysiological records as awake, drowsy, slow-wave sleep (SWS) and paradoxical sleep (PS; Ruckebusch, 1972). Energy expenditure was determined from respiratory exchange. Three groups, each of four sheep were used; yearlings, old (4-6 years of age) fat and old thin sheep. Body fat content was estimated from deuterium oxide space.

2. The amount of time spent by sheep from each group at each state of vigilance was similar, total ‘sleep’ time being 200-250 min/night.

3. The absolute decrease in energy expenditure during drowsiness and sleep was similar for all groups of sheep. The difference between SWS and lying awake was 20-27 J/kg body-weight (W)0.75 per min. Heat production was about the same for SWS and PS.

4. The energy cost of rumination was about 0.34 kJ/kg W per h.

5. The increase in heat production during standing consisted of the energy cost of standing, approximately 0.7 kJ/kg W per h, and the energy cost of changing position, approximately 47 J/kg W.

6. The old thin sheep had a slightly higher heat production on a per kg total W0.75 basis than the old fat sheep, but this difference largely disappeared when heat production was related to ‘lean’ W. On average energy expenditure was approximately 25% lower in the old sheep than in the yearling animals. This difference could not be related to difference in activity or in the energy costs of activity per unit of time.