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  • 1
    Electronic Resource
    Electronic Resource
    Fluoride-induced bone changes in lambs during and after exposure to sodium fluoride (1991)
    Springer
    Osteoporosis international 2 (1991), S. 26-33 
    Details
    ISSN: 1433-2965
    Keywords: Bone fluoride content ; Bone remodeling ; Fluoride ; Histomorphometry ; Lambs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The evolution of bone changes induced by fluoride after the end of exposure was investigated in lambs. Sodium fluoride (NaF) was given orally at a dose of 3.5 mg/kg per day to 14 animals for 120 days. A group of 7 control and 7 treated lambs was slaughtered at the end of NaF administration (T120) and another group 120 days after the end of NaF exposure (T240). At T120, the bone fluoride content (BFC) was very significantly increased in treated animals. The histomorphometric analysis confirmed that fluoride induces an increase in bone formation (the osteoid perimeter and area were 3-fold and 4.5-fold higher respectively in treated than in control animals). The number of osteoblasts was significantly augmented. Serum osteocalcin level was twice as high in treated animals compared with controls. The bone formation rate at the tissue level (BFR) doubled after treatment, but the apposition rate (Aj.AR) was half that in the control group. The mineralization lag time (Mlt) was 120 days in treated animals compared with 42 days in controls. At T240, BFC had decreased by 50% compared with the level at T120, but it was still significantly higher than in controls. The osteoid and osteoblastic parameters were 2 and 1.3 times higher than in control animals. BFR remained significantly increased in treated animals, but Aj.AR and Mlt were similar in control and treated animals. In conclusion, after 4 months of NaF exposure fluoride induced an increase in osteoblast natality and bone formation at the tissue level, associated with a toxic effect at the individual cell level. Four months after the end of NaF exposure, positive effects on bone formation were still present but the evidence of cellular toxicity had disappeared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01627075
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  • 2
    Electronic Resource
    Electronic Resource
    Bone loss after cardiac transplantation: Effects of calcium, calcidiol and monofluorophosphate (1993)
    Springer
    Osteoporosis international 3 (1993), S. 322-329 
    Details
    ISSN: 1433-2965
    Keywords: Calcium ; Cardiac transplantation ; Fluoride ; Glucocorticoid-induced osteoporosis ; Parathyroid hormone ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Of 203 patients who underwent cardiac transplantation and were given long-term treatment with cyclosporine and 0.3 mg/kg per day prednisone, 123 were studied prospectively for at least 6 months and 46 for up to 2 years to evaluate the effects on lumbar bone mineral density (BMD) and calcium metabolism of a combined therapy with calcium, calcidiol and disodium monofluorophosphate (MFP). The population was arbitrarily assigned to one of two groups. Group I consisted of patients who had a lumbar spine BMDZ score above −1.5 SD as compared with an age-and sex-matched population and no vertebral fractures. They received daily 1 g elemental calcium and 25 µg (1000 IU) calcidiol. Group II consisted of patients who received daily the same doses of calcium and calcidiol combined with 200 mg MFP, and was divided into two subgroups: (a) osteopenic subjects who had a lumbar spine BMD Z score below −1.5 SD without vertebral fractures and (b) osteoporotic subjects with vertebral fractures. If serum creatinine was higher than 140 µmol/l the daily dose of MFP was tapered to 100 mg. Fifty-four and 27 patients from group I and 38 and 19 patients from group II were followed respectively for 12 and 24 months. In both groups serum parathyroid hormone levels were significantly reduced from the twelfth month in parallel with a significant increase in serum 25-OHD levels. No decline in lumbar BMD occurred in non-osteopenic and non-osteoporotic patients (group I) who received the calcium and calcidiol supplement. In group II, where MFP was added, a significant and linear increase in lumbar BMD was observed. The average increase reached 12.5% after 12 months and 29.5% after 24 months (p〈0.0001). The magnitude of the response was similar to the response previously reported in patients suffering from vertebral fractures due to postmenopausal osteoporosis and treated with the same daily dose of MFP. Because osteoporosis and fractures are not rare in patients after cardiac transplantation, these pilot results may be useful for further prevention and treatment trials of bone loss in this condition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01637318
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  • 3
    Electronic Resource
    Electronic Resource
    Trabecular and endocortical bone remodeling in postmenopausal osteoporosis: Comparison with normal postmenopausal women (1990)
    Springer
    Osteoporosis international 1 (1990), S. 41-49 
    Details
    ISSN: 1433-2965
    Keywords: Bone ; Histomorphometry ; Osteoporosis ; Osteoblasts ; Osteocalcin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To assess the bone turnover abnormalities which characterize postmenopausal osteoporosis with vertebral fractures (PMOp), a transiliac bone biopsy was performed after double labeling of the mineralizing front with tetracycline in 50 untreated PMOp patients who were compared with 13 healthy age-matched volunteer females. The analysis of bone remodeling and structure parameters demonstrated that PMOp is a disease affecting both the cancellous and the endocortical envelopes and characterized by increased resorption and by a marked decrease in the osteoblastic apposition rate due to a reduced duration of bone formation. This induces a decrease in the width of both individual osteons and trabeculae. In PMOp, the wide spectrum of bone turnover as compared with the controls, associated with the typical bimodal distribution of cancellous osteoid perimeter, allowed us to identify two subsets, one with normal turnover (NT) and one with high turnover (HT) representing 30% of the cases. When compared to NT, HT was characterized by increased osteoclast number, lower bone volume, thinner osteons, increased formation at the tissue-level and markedly decreased duration of formation. In HT the marked decrease in the duration of activity of osteoblasts and the markedly increased number of osteoclasts induced a greater decrease in bone volume, despite the increase of bone formation at the tissue level. These subsets could not be distinguished by any clinical or biochemical parameter except for serum bone gla protein (osteocalcin) which was significantly higher (as a group) in HT than in NT. The underlying cause for these two subsets is unknown. We conclude that PMOp affects the cancellous and the endocortical bone. Bone loss results from a wide spectrum of bone turnover abnormalities, with two distinct subsets, one with normal turnover and one with high turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01880415
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  • 4
    Electronic Resource
    Electronic Resource
    Glucocorticoid-induced inhibition of osteoblastic bone formation in ewes: A biochemical and histomorphometric study (1993)
    Springer
    Osteoporosis international 3 (1993), S. 97-102 
    Details
    ISSN: 1433-2965
    Keywords: Bone formation ; Ewes ; Glucocorticoids ; Histomorphometry ; Osteocalcin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanisms underlying glucocorticoid-induced osteoporosis in humans are a defect in bone formation associated with increased bone resorption. The latter may be due to elevated parathyroid hormone (PTH) levels induced by the impairment of intestinal calcium absorption caused by corticosteroids. In this study we analysed the effects of corticosteroids in old ewes, a potential model for the study of human bone turnover. Two groups of seven 9-year-old female sheep were selected. The first group was injected intramuscularly with a daily dose of 30 mg methylprednisone (MP) during the first 2 months and 15 mg during the last month. After 2 and 3 months of treatment, blood samples were taken. At the end of the experiment the animals were slaughtered and the iliac crest kept for bone histomorphometry. Serum osteocalcin (sOC) rapidly and markedly decreased in the MP-treated group compared with controls (−77%;p〈0.01). In contrast, at the end of the experiment serum calcium and PTH levels were similar in both groups. Histomorphometric analysis showed a significant reduction in the wall width of trabecular packets. Dynamic parameters reflecting bone formation at the tissue and cell levels were significantly lower in the MP-treated group than in controls, with a highly significant decrease in the mineralization rate (MAR: −63%,p〈0.05) and double-labeled perimeter (dLPm/B.Pm: −92%p〈0.05). The bone formation rate (BFR/B.Pm) also decreased by 84% and the adjusted apposition rate (Aj.AR) by 80%. The increase in the total formation period was mainly due to an increase in the inactive period. Significant correlations were found between sOC and MAR, dLPm/B.Pm and BFR/B.Pm (withr′ respectively 0.67, 0.76 and 0.51). In conclusion, the effects of corticosteroid on ewe bone remodeling are essentially characterized by a major bone formation defect without evidence of secondary hyperparathyroidism, although this cannot be totally excluded by our results. Ewes treated with glucocorticoids could represent a good model for evaluating the effects of drugs candidates for all bone conditions characterized by reduced bone formation resulting from osteoblastic depression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623380
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