Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research
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J. Bone Miner. Res. · Feb 2001
Quantitative ultrasound and bone mineral density are equally strongly associated with risk factors for osteoporosis.
Because resources do not allow all women to be screened for osteoporosis, clinical risk factors are often used to identify those individuals at increased risk of fracture who are then assessed by bone densitometry. The aim of this study was to compare calcaneal quantitative ultrasound (QUS) and axial bone mineral density (BMD) T and Z scores in a large group of women, some with no clinical risk factors and others with one or more risk factors for osteoporosis. The study population consisted of 1115 pre- and postmenopausal women. ⋯ The proportion of women classified into each diagnostic category was similar for BMD and QUS. In conclusion, clinical risk factors for osteoporosis affected calcaneal BUA and SOS Z score measurements to the same extent as axial BMD Z score measurements. Provided revised diagnostic criteria are adopted for QUS, similar proportions of postmenopausal women are identified as osteopenic or osteoporotic as with BMD.
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J. Bone Miner. Res. · Sep 2000
Evaluation of changes in trabecular bone architecture and mechanical properties of minipig vertebrae by three-dimensional magnetic resonance microimaging and finite element modeling.
The study objective was to analyze the three-dimensional (3D) trabecular architecture and mechanical properties in vertebral specimens of young and mature Sinclair minipigs to assess the relative contribution of architecture to bone strength. We used 3D magnetic resonance microimaging (MRmicroI) and direct image analysis to evaluate a set of standard structural measurements and new architectural descriptors of trabecular bone in biopsy specimens from L2, L3, and L4 vertebrae (n = 16 in each group) from young (mean age, 1.2 years) and mature (mean age, 4.8 years) minipigs. The measurements included bone volume/tissue volume (BV/TV), marrow star volume (Ma. ⋯ The experimental maximum stress in the vertebra of the mature animals was twice as high as that for the young animals (p = 0.006). Bone quantity (BV/TV or bone mineral content [BMC]) alone could explain approximately 74-85% of the total variability in stress and modulus. The inclusion of either ConnD or % boneLD with BV/TV in a multiple regression analysis significantly improved the predictability of maximum stress, indicating that architecture makes additional contributions to compressive strength in normal minipig vertebra.
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J. Bone Miner. Res. · Jun 2000
Androgen deficiency induces high turnover osteopenia in aged male rats: a sequential histomorphometric study.
Hypogonadism is considered to be one of the major risk factors for osteoporosis in men. However, the mechanisms of bone loss caused by androgen deficiency are still unclear. In the present study, we sequentially investigated the skeletal and hormonal effects of androgen deficiency in aged orchiectomized (ORX) rats over a time period of 9 months. ⋯ These data show that androgen deficiency induces substantial loss of cancellous bone in the axial and appendicular skeleton of aged male rats and that this osteopenia is associated with a sustained increase in bone turnover. Thus, the skeletal effects of androgen withdrawal in aged male rats appear to resemble those induced by estrogen withdrawal in female rats. Furthermore, our study suggests that estradiol may act as a physiological suppressor of bone remodeling in aged male rats.
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J. Bone Miner. Res. · Apr 2000
Skeletal effects of parathyroid hormone infusion in ovariectomized rats with or without estrogen repletion.
We employed skeletally matured rats to study changes in biochemical markers of bone turnover, bone mineral density (BMD), and bone biomechanics produced by continuous elevation of parathyroid hormone (PTH) in estrogen-deplete and -replete rodents. Ninety-six 7-month-old virgin female rats were divided randomly into 12 groups (n = 8) and treated as follows. One group was killed on the day of surgery. ⋯ Our results showed that (1) continuously elevated levels of PTH induced additional loss of BMD in estrogen-deficient animals beyond the rapid bone loss phase associated with ovariectomy, (2) estrogen repletion, given by implant, to PTH-infused Ovx animals, reversed these BMD changes increasing BMD to levels comparable with estrogen-sufficient rats, and (3) these changes were reflected in the mechanical strength determined at these sites. These results lend experimental support that hormone replacement therapy may benefit bone health in postmenopausal women with primary hyperparathyroidism (PHPT). In addition, it raises the possibility that a continuous elevation of PTH could exert anabolic effects on skeletal tissue if its catabolic component can be minimized.
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J. Bone Miner. Res. · Mar 2000
Osteoporotic fractures are associated with an 86-base pair repeat polymorphism in the interleukin-1--receptor antagonist gene but not with polymorphisms in the interleukin-1beta gene.
Interleukin-1beta (IL-1beta) is a potent stimulator of bone resorption, and has been implicated in the pathogenesis of high bone turnover and osteoporosis. IL-1 receptor antagonist (IL-1ra) is a competitive inhibitor of IL-1beta effects and the biological effects of IL-1beta are therefore proportional to the ratio IL-1beta/IL-1ra. The coding regions of IL-1beta were examined for sequence variations by SSCP and sequencing after polymerase chain reaction (PCR) of genomic DNA. ⋯ T1100-C genotypes were distributed similarly in osteoporotic patients and normal controls and the polymorphism was without effect on bone mass and biochemical markers of bone turnover. In conclusion, an 86-base pair repeat polymorphism in the IL-lra gene is associated with increased risk of osteoporotic fractures. Other polymorphisms in the IL-1ra and the IL-1beta genes are not associated with osteoporotic fractures or alterations in bone mass or bone turnover.