Role of ovarian hormones in the pathogenesis of impaired detrusor contractility: evidence in ovariectomized rodents.

PURPOSE: Although detrusor hyperactivity with impaired contractility is a common urodynamic finding in elderly subjects, to our knowledge its pathogenesis remains unknown. Biopsy studies indicate that subjects with detrusor hyperactivity and impaired contractility have ultrastructural evidence of dysjunction and degeneration patterns in isolated detrusor hyperactivity and impaired contractility, respectively. Based on the known cellular effects of estrogen we postulated that declines in ovarian hormone production may contribute to the pathogenesis of detrusor hyperactivity with impaired contractility. MATERIALS AND METHODS: Mature 13 to 14-month-old female Fisher 344 rats were studied 4 months after bilateral ovariectomy or sham surgery. Detrusor structure was evaluated by electron microscopy and contractility was evaluated by muscle strip studies. RESULTS: After bilateral ovariectomy detrusor smooth muscle decreased by 25% with a 12% decrease in the number of nucleated muscle profiles and degenerative changes in many axons. Muscle strips from bilaterally ovariectomized animals generated 40% to 50% less tension per strip in response to carbachol than strips of equal size from sham operated animals with no apparent change in muscarinic receptor affinity. CONCLUSIONS: Bilateral ovariectomy resulted in many changes of the degeneration ultrastructural pattern but in none of the characteristic features of the dysjunction pattern. Our results indicate that the mature rodent detrusor and its innervation are sensitive to prolonged ovarian hormonal deficiency, contributing to impaired contractility in rodents. Future studies are required to establish whether estrogen has a role in the degeneration ultrastructural pattern or impaired contractility in humans.

A study on the radiopacity of different shades of resin-modified glass-ionomer restorative materials.

There are several resin-modified glass-ionomer restorative materials available to the dental profession today. The commercially available brands are presented in a range of shades. There is little information on their radiopacity and whether this varies with differences in shade. While the general radiopacity of various products may have been studied, only assumptions are available regarding their consistency between shades. The purpose of this study was to investigate if there were any significant differences in the radiopacity of the shades available within each commercial product. The products evaluated were Fuji II LC, Vitremer, and Photac-Fil. The optical densities of standardized radiographs of samples of these materials were determined and radiopacity values of materials expressed in millimeter equivalents of aluminum. Of the three resin-modified glass-ionomer restorative materials tested, Fuji II LC was the most radiopaque and Photac-Fil the least. Fuji II LC and Vitremer showed radiopacity values equivalent to > 2.5 mm and > 1.5 mm aluminum respectively; Photac-Fil demonstrated very low radiopacity values (equivalent to < 0.6 mm aluminum). Statistical analysis revealed that there was no significant difference in radiopacity among the shades within each of these brands.