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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Experimental Gerontology 25 (1990), S. 339-347 
    ISSN: 0531-5565
    Keywords: cAMP ; calcitonin ; osteoporisis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0531-5565
    Keywords: DNA synthesis ; bone resorption ; cAMP ; intracellular calcium ; parathyroid hormone ; protein kinase C ; signal transduction
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-2965
    Keywords: Bone density ; Calcitonin ; Calcium supplement ; Hormone replacement ; Quantitative computed tomography ; Vertebral height
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Estrogen and calcitonin increase bone density of osteoporotic women, particularly on the axial skeleton. To verify whether the effect of these drugs might in part be biased by spurious increases in bone density due to radiologically irrelevant microfractures, and consequent subtle decreases in vertebral height, we followed the changes in vertebral bone density (VBD), assessed by quantitative computed tomography, in relation to vertebral height (VH) in 60 osteoporotic women. VH was measured as the sum of anterior, central and posterior heights of L1–L3 vertebral bodies on lateral radiographs. Patients received either salmon calcitonin (sCT: 50 IU subcutaneously three times per week,n=18), hormonal replacement therapy (HRT: conjugated estrogen 0.625 mg/day, days 1–25, plus medroxyprogesterone acetate 10 mg/day, days 16–25 of each month;n=21) or calcium alone (Ca: 1000 mg/day,n=21). After 1 year, VBD increased in the HRT group (+5.0 ± 1.9%,p=0.010), did not change significantly in the sCT group (+3.3 ± 2.3%,p=0.167), and decreased by 6.1 ± 1.0% (p〈0.001) in the Ca group. By analysis of variance, the changes induced by HRT and sCT were significantly different from those observed in the Ca group (F=7.982,p〈0.001). VH decreased slightly in all three subsets of patients (−0.9 ± 0.5% in sCT, −1.5 ± 0.3% in HRT, −0.1 ± 0.5% in Ca), but these changes were not significantly different between groups (F=2.545,p=0.081). Correcting for this height decrease by analysis of covariance did not affect the significant effect of sCT and HRT on VBD, compared with that of Ca (F=6.801,p=0.001). Furthermore, no correlation was found between changes in bone VBD and VH in any of the groups. These data indicate that microfractures do not significantly account for the increases in bone density during active treatment of osteoporosis with either estrogen or calcitonin.
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  • 4
    ISSN: 1432-0827
    Keywords: Osteoblasts ; Matrix proteins ; Collagen ; Cell differentiation ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10-5 M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.
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  • 5
    ISSN: 1432-0827
    Keywords: Bone mineral density ; Dual energy X-ray absorptiometry ; Osteoporosis ; Menopause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Dual energy x-ray absorptiometry (DXA) was used to measure bone mineral density (BMD) of the lumbar spine and proximal femur (neck, Ward's triangle, and trochanter) in 417 normal women (aged 20–79) living in São Paulo, Brazil. Bone density decreased with age at all sites. At the spine, the greatest decrease occurred during the sixth decade, with an average 11.4% bone loss compared with the previous decade. Stratifying the subjects according to menopausal status revealed that the fastest bone occurred at the time around the menopause (ages 45–60) when the rate of bone loss (-0.66%/year) was almost twice as rapid as in postmenopausal women (-0.39%/year). Although significant linear rates of bone loss were detected in all proximal femur sites before the menopause, a menopause-dependent pattern was less evident that at the spine. Lifetime rates of bone loss at the appendicular skeleton were-0.43,-0.62, and-0.35%/year at the femoral neck, Ward's triangle, and trochanteric area, respectively. After the menopause, BMD declined with menopausal age at all sites, although the rate of bone loss was faster at the femoral neck (-0.62%/year) and Ward's triangle (-0.84%/year) than at the spine-0.49%/year). The results are consistent with the notion that in women, the fastest bone loss occurs at the time round the menopause, most likely consequent to ovarian failure; and that faster rates of bone loss are detected at the proximal femur than at the lumbar spine in late postmenopausal women.
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  • 6
    ISSN: 1432-0827
    Keywords: Bone crystals ; X-ray diffraction ; Bone quality ; Mineral analysis ; Ipriflavone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract We have previously found that a short-term treatment with high doses of ipriflavone increased bone density and improved the biomechanical properties of adult male rat bones, without altering their mineral composition. To determine whether this effect can be associated with alterations of bone crystal structure, we have performed X-ray diffraction analysis of bones obtained from rats treated with ipriflavone at doses that were effective in inducing favorable changes on bone density and biomechanics. Eighteen-week-old male Sprague Dawley rats were treated by oral route with either ipriflavone (200 or 400 mg/kg/day), or its vehicle for 12 weeks. The treatment was well tolerated and body weight increased to the same extent in all animals. As a measure of bone crystallinity, we examined the (310) and (002) reflections of the X-ray diffraction patterns, corresponding to the directions perpendicular and parallel to the c-axis of the crystals, respectively. No major differences were observed between ipriflavone-treated and control animals for the broadening parameter β1/2 for (310) and (002) peaks, as well as for lattice parameters. Therefore, a 12-week treatment with ipriflavone at high doses does not induce significant modifications of bone “crystallinity.” Thus. the positive effect of ipriflavone on bone mineral density appears to be associated with an increased apatite crystal formation rather than an increase of crystal size. These results provide further evidence for the safety and usefulness of ipriflavone in the treatment of osteoporotic syndromes.
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  • 7
    ISSN: 1432-0827
    Keywords: Key words: Bone mass — Intestinal calcium absorption — Aging in men.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Although about 25% of all hip fractures occur in men, little is known about the pattern of their age-related bone loss and its main determinants. The aim of this cross-sectional study was to evaluate the age-related changes of intestinal calcium absorption, bone mass, and bone turnover in normal men. In 70 normal males (age 17–91 years), we measured spinal and forearm bone density (FBD) (by DXA), fractional intestinal calcium absorption (by oral test), serum immunoreactive parathyroid hormone (PTH), dietary calcium intake (diet records), biochemical markers of bone turnover (serum alkaline phosphatase (ALP), osteocalcin, urine calcium, creatinine, and hydroxyproline), and 1,25(OH)2D3 serum levels. Vertebral bone density (VBD) showed a modest decline before age 50 and a greater decline after age 50, whereas FBD presented a significant decrease with advancing age starting at age 40, suggesting a predominant age-related cortical bone loss. Intestinal calcium absorption (47CaFA) and serum 1,25(OH)2D3 also presented an age-related decline similar to FBD. Simple correlation analysis revealed that age was significantly related to 47CaFA (r = 0.60), calcium intake (r = 0.32), VBD and FBD (r = 0.79 and 0.63, respectively), serum 1,25(OH)2D3 (r = 0.69), and serum iPTH (r = 0.72). No significant correlation was found between age and biochemical markers of bone remodeling. Partial correlation and stepwise variable selection analyses, using 47CaFA and bone mass as dependent variables, showed that in normal males, serum 1,25(OH)2D3 and dietary calcium intake were the main contributors (64%) to 47CaFA variability, whereas only age accounted for 63% of VBD and age and dietary calcium accounted for 45% of FBD variability. These results indicate that bone loss in men accelerates after age 50 years and that among other factors, intestinal calcium malabsorption and 1,25(OH)2D3 serum levels play a role.
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  • 8
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To determine whether postmenopausal bone loss and factors associated with osteoporosis affect tooth retention, we examined vertebral and proximal femoral (postcranial) bone mineral density in relation to tooth loss and attachment loss in a cross-sectional study of 135 postmenopausal women (age range 41–70 yr). Women had at least 10 teeth and no evidence of moderate or severe periodontal disease. Full-mouth attachment loss measurements were made using a pressure-sensitive probe, and bone density was determined by dual-energy X-ray absorptiometry. Attachment loss was correlated with tooth loss (number of remaining teeth, radiologically determined), but not with vertebral or proximal femur bone density. Multivariate analysis showed current smoking (p = 0.01), years since menopause (p = 0.02) and the interaction of age and current smoking (p 〈 0.01), to be statistically significant predictors of attachment loss in our study population.
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  • 9
    ISSN: 1432-0827
    Keywords: Bone mineral density ; Bone quality ; Vibration damping ; Impact strength ; Bone turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract To assess the potential impact of ipriflavone on the biomechanical properties and mineral composition of bone, we administered two doses (200 or 400 mg/kg bw) of the drug orally to adult male rats for 1 month. Bone biomechanics were evaluated by vibration damping, an index of strain energy loss, and impact strength (the amount of energy required to fracture after a single impact). At the higher dose, ipriflavone significantly decreased vibration damping of rat femurs by 23.0±9.8% compared with control, vehicle-treated animals, suggesting a higher capacity to withstand dynamic stress. This result was confirmed by the impact strength studies showing that a higher energy (49.6±21.3% above control) was required to fracture femurs of rat treated with 400 mg/kg bw ipriflavone. The high dose of ipriflavone increased bone mineral density, assessed by both volume displacement and ash analysis (4.2% and 2.5% above controls, respectively). The relative content of calcium, phosphorus, and magnesium in the ashes was not different among the treated and untreated groups, indicating that no gross abnormalities in mineral composition of bone occurred after ipriflavone administration. Similarly, there were no differences in serum calcium and magnesium levels between treated and control animals at the end of the study, whereas lower circulating phosphorus levels were detected in the latter. Ipriflavone treatment was not associated with significant changes in serum alkaline phosphatase nor type I collagen telopeptide levels, two markers of bone turnover. In summary, 1-month treatment with ipriflavone increased bone density and improved the biomechanical properties of adult rat male bones without altering mineral composition. These results lend support to the use of ipriflavone in osteoporotic syndromes.
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  • 10
    ISSN: 1432-0827
    Keywords: Key words: Bone crystals — X-ray diffraction — Bone quality — Mineral analysis — Ipriflavone.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. We have previously found that a short-term treatment with high doses of ipriflavone increased bone density and improved the biomechanical properties of adult male rat bones, without altering their mineral composition. To determine whether this effect can be associated with alterations of bone crystal structure, we have performed X-ray diffraction analysis of bones obtained from rats treated with ipriflavone at doses that were effective in inducing favorable changes on bone density and biomechanics. Eighteen-week-old male Sprague Dawley rats were treated by oral route with either ipriflavone (200 or 400 mg/kg/day), or its vehicle for 12 weeks. The treatment was well tolerated and body weight increased to the same extent in all animals. As a measure of bone crystallinity, we examined the (310) and (002) reflections of the X-ray diffraction patterns, corresponding to the directions perpendicular and parallel to the c-axis of the crystals, respectively. No major differences were observed between ipriflavone-treated and control animals for the broadening parameter β½ for (310) and (002) peaks, as well as for lattice parameters. Therefore, a 12-week treatment with ipriflavone at high doses does not induce significant modifications of bone ``crystallinity.'' Thus, the positive effect of ipriflavone on bone mineral density appears to be associated with an increased apatite crystal formation rather than an increase of crystal size. These results provide further evidence for the safety and usefulness of ipriflavone in the treatment of osteoporotic syndromes.
    Type of Medium: Electronic Resource
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