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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Osteoporosis international 1 (1990), S. 3-6 
    ISSN: 1433-2965
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Osteoporosis international 1 (1990), S. 7-13 
    ISSN: 1433-2965
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-2965
    Keywords: Parathyroid hormone (PTH) ; Osteoporosis ; Bone resorption ; Bone formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To define the role of parathyroid gland function in the pathophysiology of bone loss in type I (postmenopausal) osteoporosis, we measured serum intact parathyroid hormone (PTH) concentration by immunoradiometric assay (IRMA) and by multisite immunochemiluminometric assay (ICMA) in 63 postmenopausal osteoporotic women (PMOp) with vertebral compression fractures and in 75 age-comparable postmenopausal normal women (PMNl). Also, tetracycline-based histomorphometric indices in cancellous bone were assessed in iliac biopsy samples from 61 PMOp and 28 PMNl women. Serum PTH concentrations by IRMA were similar in PMOp and PMNl (medians, 3.92 and 3.77 pmol/l; NS) but were significantly lower in PMOp by the more sensitive ICMA (medians, 2.82 and 3.14 pmol/l;P〈0.01). By multiple linear regression analysis, serum PTH was directly related (P〈0.001) to activation frequency, bone resorption rate, bone formation rate, and the calculated rate of bone loss. For each unit (pmol/l) increase in serum PTH by ICMA, activation frequency increased by 1.3%/year more (P=0.01), bone resorption rate increased by 3.9%/year more (P=0.003), and the rate of cancellous bone loss was 2.8% greater (P= 0.0003) in the PMOp women compared with the PMNl women. Concentrations of serum estradiol, but not serum estrone, had a weak opposing effect to PTH, especially for bone formation rate. These data suggest that in PMOp the bone has increased sensitivity to the biologic effects of PTH. This may represent one of the fundamental pathophysiologic defects in PMOp and, in the setting of estrogen deficiency, may explain, in part, their greater rate of bone loss.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-2965
    Keywords: Bone loss ; Bone mass measurements ; Osteoporosis ; Peak bone mass ; Postmenopause ; Rate of bone loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have addressed the relative importance of peak bone mass and subsequent rate of loss in determining postmenopausal women's bone mass in old age, by examining longitudinal measurements of radial mid-shaft bone mass on various samples of healthy white postmenopausal women. Using both the variance estimate of age-specific rates of bone loss and the population variance in bone mass, we determined that rates of loss could contribute importantly to future bone mass. However, since we found a small negative correlation between initial bone mass and rate of loss, it was necessary to estimate the effect of bone loss as the complement of the contribution of initial bone mass. We found that the influence of bone loss (relative to initial bone mass) increases as the women age, such that by about age 70, the contribution of initial bone mass and rate of loss approached equality. However, estimated rates of bone loss were not very stable over time, so it was difficult to identify long-term ‘fast-losers’. We conclude that the rate of postmenopausal bone loss is an important contributor to osteoporosis at old age, but it is difficult to identify long-term fast-losers, thereby reducing the clinical value of assessments of rates of change in bone mass early in the postmenopause.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1433-2965
    Keywords: Osteoporosis ; Prediction ; Biochemical markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study includes 70 healthy, immediately postmenopausal women stratified according to future rate of bone loss. The stratification was performed by means of four parameters of bone turnover: serum alkaline phosphatase, fasting urinary calcium and hydroxyproline, and body weight, used in an equation developed in a previous study. After the stratification the women were followed without intervention for the next 24 months, with bone mass measurements every 3 months. The bone loss estimated at baseline by means of the equation correlated with the bone loss measured in the forearm (y=0.72x−1.52;r=0.61;P〈0.001). Plasma bone gla protein (BGP, osteocalcin), which is a new specific marker of bone formation, was now added to the model (replacing body weight). This increased the diagnostic validity (y=x;r=0.76;P〈0.001). From the present study we conclude that the postmenopausal bone loss can be predicted by means of four biochemical parameters determined in plasma and urine in women just after the menopause.
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  • 6
    ISSN: 1433-2965
    Keywords: Bone mineral density ; Dual-energy X-ray absorptiometry ; Lumbar vertebrae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The bone mineral density (BMD) of lumbar vertebrae in the anteroposterior (AP) view may be overestimated in osteoarthritis or with aortic calcification, which are common in elderly. Furthermore, the risk of spinal crush fracture should be more closely related inversely to the BMD of the vertebral body than to that of the posterior arch. Therefore, we measured BMD of lumbar vertebrae in lateral (LAT) view (L2–L3), using a standard dual-energy X-ray absorptiometer (DEXA), thus eliminating most of the posterior spinal elements. The precision of BMD LAT measurement was determined both in vitro and in healthy volunteers. Then, we compared the capability of BMD LAT and BMD AP scans for monitoring bone loss related to age and for discriminating the BMD of postmenopausal women with nontraumatic vertebral fractures from that of young subjects. In vitro, when a spine phantom was placed in lateral position in the middle of 26 cm of water in order to simulate both soft-tissue thickness and X-ray source remoteness, the coefficient of variation (CV) of six repeated determinations of BMD was 1.0%. In vivo, the CV of paired BMD LAT measurements obtained in 20 healthy volunteers after repositioning was 2.8%. The age-related difference between a peak bone mass group estimated in a group of 27 healthy women aged 20 to 35 years and a group of 50 women aged 60 to 75 years, in whom neither vertebral fracture nor osteoporosis risk factors could be detected, were 21.7% and 37.6% in AP and LAT view, respectively. An arbitrary BMD fracture threshold was defined in AP and LAT views as the 90th percentile of the BMD value of a group of 22 osteoporotic women with vertebral fractures. The distribution of BMD AP and LAT above and below this threshold in 169 consecutively screened women without vertebral fracture was then analysed. In both AP and LAT views, 39.1% and 31.3% had BMD values above and below this threshold, respectively. Of the remaining, 16.0% had a BMD below this threshold only in AP and 13.6% only in LAT view. Thus, if BMD LAT was a better reflection of vertebral body bone mass than BMD AP, and thereby a better predictor of the resistance to crush fracture, our results would suggest that only the use of the standard AP view could under- or overestimate spinal fracture risk in about 30% of women screened for osteoporosis. In conclusion, our results indicate that BMD measurement in lateral view is feasible with a standard DEXA instrument. This mode of scanning, besides overcoming artefacts due to osteoarthritis of the posterior arch and aortic calcifications, appears to provide a greater sensitivity for assessing bone mass loss of the vertebral body than the standard anteroposterior scan.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Osteoporosis international 1 (1990), S. 61-61 
    ISSN: 1433-2965
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1433-2965
    Keywords: Peak bone density ; Bone density genotype ; Dietary calcium intake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Risk of osteoporotic fracture in later life relates to both age and menopause-related bone loss but also to peak bone density achieved in early adulthood. Several studies have shown that genetic influences make a major contribution to variance in adult bone density, but environmental factors such as dietary calcium and physical activity also contribute a large proportion of observed variance in bone density. Previous hypotheses have suggested that the effect of certain environmental factors, such as hormonal and dietary influences, may be permissive to development of peak bone mass. Consideration of the evidence for the interaction between environmental influences, such as physical activity and nutrition, and genotype leads us to propose that environmental factors interact to allow or prevent full expression of bone density genotype. This expansion of the ‘threshold’ hypothesis can include the effects of sex, physical activity and dietary calcium in a model that allows more systematic study of the determinants of peak bone density and thereby more rational intervention to augment bone density in early adulthood.
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  • 9
    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.
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  • 10
    ISSN: 1433-2965
    Keywords: Distal radius ; Mid-radius ; Age ; Anthropometry ; Peak bone mass ; Bone density ; Lean body mass ; Body mass index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A sample of 181 healthy premenopausal Caucasian women, 20 to 50 years of age, was part of a cross-sectional study on the determinants of radial bone mineral content (BMC), bone width (BW) and areal bone mineral density (BMD) at two sites, the distal (Dis) or 5 mm-site (about 50% cancellous tissue) and the mid-radial (Mid) site (over 90% cortical tissue), as measured by single photon-absorptiometry. Women in their 20s (n=45) had significantly lower DisBMC and DisBW values than women in their 30s (n= 65) or 40s (n=71). No such trends were noted for any of the mid-radial measurements with increasing age. With age, height and weight included in the same regression equation, age remained the only significant positive predictor of all three distal variables, while height was the only significant positive predictor of the mid-radial variables. Body weight was not associated with any of the bone variables in this model. A low lean body mass (LBM) or low body mass index (BMI) was consistently correlated with significantly lower bone values at both radial sites. These data suggest that peak bone mass (PBM), for the distal and largely cancellous portion of the radius, was achieved later in adulthood (30s) than the mid-radial or mostly cortical portion of the radius in which PBM was achieved much earlier, probably in late adolescence.
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