Interleukin‐6 (IL‐6) is a multifunctional cytokine whose circulating levels are under physiological conditions below detection, but whose production is rapidly and strongly induced by several pathological and inflammatory stimuli. IL‐6 has been implicated in a number of cell functions connected to immunity and hematopoiesis. Recently, it has been proposed to act as a stimulator of osteoclast formation and activity, in particular following estrogen depletion. The purpose of this study was to gain additional insights into the role of IL‐6 during development, as well as in physiological and pathological conditions. We report here that IL‐6 deficient mice generated by gene targeting are viable and do not present any evident phenotypic abnormality. However, analysis of bone metabolism revealed a specific bone phenotype. IL‐6 deficient female mice have a normal amount of trabecular bone, but higher rates of bone turnover than control littermates. Estrogen deficiency induced by ovariectomy causes in wild type animals a significant loss of bone mass together with an increase in bone turnover rates. Strikingly, ovariectomy does not induce any change in either bone mass or bone remodeling rates in the IL‐6 deficient mice. These findings indicate that IL‐6 plays an important role in the local regulation of bone turnover and, at least in mice, appears to be essential for the bone loss caused by estrogen deficiency.

This study examined the effect of 2 yr of treatment with the aminobisphosphonate alendronate (ALN) (0.05 or 0.25 mg/ kg i.v. ALN every 2 wk) on estrogen deficiency bone loss and bone strength changes in ovariectomized (OVX) baboons (n = 7 per group) and the ALN mode of action at the tissue level. Biochemical markers of bone turnover increased in OVX animals and were maintained by ALN treatment at non-OVX levels (low dose) or below (high dose). 2 yr of treatment produced no cumulative effects on bone turnover markers. Histomorphometry showed a marked increase in cancellous bone remodeling in OVX animals. Activation frequency increased from 0.48 to 0.86 per yr (L5 vertebra), and the osteoid surfaces from 9 to 13.5% (P < 0.05). No changes were observed in eroded and osteoclast surfaces. ALN treatment decreased activation frequency and indices of bone formation to control levels (low dose) or below (high dose), did not change indices of mineralization, and increased bone mineral density (BMD) in the lumbar vertebrae (L2-L4) by 15% at 0.25 mg/kg (P < 0.05), relative to vehicle-treated animals. The mean strength of cancellous bone (LA) increased by 44% (low ALN dose) and 100% (high dose), compared with vehicle. The strength of individual bones correlated with the square of the L2-L4 BMD (r = 0.91, P < 0.0034). In conclusion, ALN treatment reversed the effects of ovariectomy on cancellous bone turnover and increased bone mass and bone strength in baboons. (J. Clin. Invest. 1993. 92:2577-2586 Key words: osteoporosis * alendronate * histomorphometry-bone strength * bone mineral density

QOL was better in type 1 diabetics with ESRD following transplantation when compared with remaining on WL. SPK transplantation had significant positive effect on diabetes-related QOL which was sustained longitudinally but it was difficult to show an overall improvement in general QOL.

Prostaglandin E2 (PGE2) has been shown to stimulate both bone resorption and formation in experimental animals, leading to augmentation of trabecular and cortical bone. The amino bisphosphonate alendronate (ALN) is a potent inhibitor of bone resorption. The objectives of this study were to examine if PGE2 stimulation of bone formation was dependent on bone resorption and if the bone accrued as a result of PGE2 treatment contributed to bone strength. The 48 female Sprague-Dawley rats were assigned to six groups as follows: five groups (8/group) were ovariectomized at the age of 6 months. One group was sacrificed 2 months later to establish baseline conditions, and four groups were treated for 25 days with (1) vehicle, (2) PGE2 at 3 mg/kg/day, (3) ALN sc at 0.8 micrograms/kg/day, and (4) PGE2 + ALN at the respective doses. The sixth group served as nonovariectomized untreated controls. Histomorphometric analysis of 6-10 microns thick tibial sections after in vivo fluorochrome double labeling showed that treatment with PGE2 alone increased endocortical mineral apposition rate and bone formation rate, stimulated production of bone trabeculae in the marrow cavity, and increased cortical porosity. Combined ALN + PGE2 treatment prevented the resorption induced by PGE2 but not the stimulation of bone formation on endocortical and periosteal surfaces and resulted in a significant increase in cortical thickness. Consistent with these observations, the femoral midshaft tested to failure in three-point bending showed a significant increase in strength in the PGE2 + ALN group (181 +/- 15 N) compared to time 0 controls (145 +/- 23 N) or to the ovariectomized vehicle-treated group (141 +/- 28 N).(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperthyroidism, either endogenous or iatrogenic, leads to increased bone turnover and osteopenia. This study was conducted to examine (1) whether thyroid hormone excess in rats causes bone changes similar to those seen in patients with hyperthyroidism, and (2) the effects of the aminobisphosphonate alendronate on the thyroid hormone-induced bone changes. Sprague-Dawley male rats, divided into four groups, received L-thyroxine (T4) 250 micrograms/kg/day (+T4) or vehicle (-T4) subcutaneously six times per week and alendronate 1.75 mg/kg (+ALN) or vehicle (-ALN) orally twice a week. Rats were sacrificed after 3 weeks of treatment, blood samples were analyzed for serum T4, triiodo-L-thyronine (T3), and osteocalcin, and the proximal tibiae were processed for histomorphometric analysis. Serum T4 and T3 levels measured 20-24 hours after the last injection were 2 to 2.5-fold higher in +T4 groups than in -T4 groups. Serum osteocalcin was significantly (P < 0.05) higher in +T4/-ALN group than in the other groups, which were not statistically different from each other. T4 treatment (+T4/-ALN) significantly decreased the amount of cancellous bone volume (-45%) and increased osteoid surface (+254%), osteoblast surface (+111%), and osteoclast surface (+176%) relative to control values. Alendronate increased the bone volume above control values in both T4-treated (+T4/+ALN) and untreated (-T4/+ALN) rats, and prevented the T4-induced increase in bone turnover in +T4/+ALN rats. It is concluded that (1) excess thyroid hormone induces cancellous bone loss associated with high bone turnover in the rat, and (2) this bone loss can be prevented by alendronate through the inhibition of osteoclastic activity.

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