Safe and effective method for chronic 17beta-estradiol administration to mice.

Supraphysiological 17beta-estradiol treatment administered via subcutaneous pellets is commonly used in mice. However, despite its efficacy in eliciting a uterotrophic response, we demonstrate that this regimen also was associated with urine retention, hydronephrosis, and ultimately premature death. To determine a safer yet still effective method to chronically treat mice with 17beta-estradiol, we initiated a placebo-controlled study to treat ovariectomized C57BL/6J mice for 6 weeks with various doses of 17beta-estradiol administered either in their drinking water (0.3 to 1000 nM) or via pellets (0.72 mg or 1.7 mg). Uterine weights demonstrated a dose-dependent effect of 17beta-estradiol administered either orally or via pellets; however, the pellet treatments resulted in urine retention. Treatment with either 200 or 1000 nM 17beta-estradiol in the drinking water yielded physiological and supraphysiological uterotrophic responses, respectively, without urine retention, providing safe, effective, and economical ways to treat mice chronically with 17beta-estradiol.

Evaluation of an antimicrobial-impregnated continuous ambulatory peritoneal dialysis catheter for infection control in rats.

Infection is the most serious complication arising in long-term continuous ambulatory peritoneal dialysis (CAPD), specifically peritonitis and exit-site infection. The initial weeks after implantation is the crucial period during which bacterial colonization of the catheter results in maximal morbidity, with Staphylococcus aureus being the most virulent organism. We developed an antimicrobial-impregnated CAPD catheter by impregnating the cuff and tubing with chlorhexidine, silver sulfadiazine, and triclosan in a polymer matrix. The antimicrobial spectrum and duration were shown by measuring zones of inhibition to various bacteria and fungi over the course of 5 to 10 days. Activity also was assessed subsequent to soaking in trypticase soy broth containing 20% bovine serum over the course of 1, 3, and 7 days. Significant antimicrobial activity was shown against all organisms tested for, with particular efficacy against gram-positive bacteria. Catheters were implanted in rats followed by inoculation of the exit site with S aureus. Seven days postimplantation, 0% of the impregnated catheters were colonized intraperitoneally compared with 100% of the control catheters. Similarly, 12.5% of the impregnated catheters were colonized at the exit site, whereas 100% of the controls were colonized. Histologic analysis showed that this combination and concentration of antimicrobials did not retard healing or cause increased inflammation compared with control catheters after 3, 10, and 24 days postimplantation in noninoculated rats.