Bone
-
The present study was carried out to investigate the ability of clodronate to inhibit ovariectomy-induced bone loss and increased bone turnover in rats. Estradiol was administered as a reference compound. Seventy Sprague-Dawley rats were ovariectomized (OVX) or sham-operated (Sham) at the age of 90 days and divided into seven groups. ⋯ These results suggest that ovariectomy of growing rats resulted in tibial and femoral osteopenia two months later. Clodronate as well as estradiol can suppress bone resorption and turnover in ovariectomized rats, inhibiting the development of osteopenia. Both clodronate doses (5 and 12.5 mg/kg) had beneficial effects in ovariectomized animals.
-
Twenty-eight young male adolescents (age from 13 years 6 months to 15 years 9 months) from a horseback-riding school were studied. They were studied at the end of summer (September of 1993) and, six months later, at the end of winter (March of 1994). At each timepoint their height and weight were measured and their pubertal status determined. ⋯ Modulation of PTH secretion by vitamin D appears to be a physiological mechanism occurring during adolescence. In spite of a marked depletion of vitamin D stores after winter, PTH values remained within normal range. Nevertheless, we cannot exclude that a more prolonged vitamin D deficiency could adversely affect bone metabolism during this critical period of life characterized by an increased need of vitamin D.