ISSN:0884-0431    

DOI:10.1002/jbmr.5650050302

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractOsteoporosis‐associated fractures are a major public health problem in the United States. Although clinicians and policy groups have advocated estrogen replacement therapy and other clinical measures to prevent osteoporosis, few studies have assessed whether these measures are being adopted by physicians in practice. The purpose of this study is to evaluate physicians' use of osteoporosis prevention measures and to assess the impact of physician specialty and practice setting on osteoporosis prevention performance.A survey of nearly 300 physicians was carried out in a large metropolitan area. Gynecologists, general internists, and cardiopulmonary specialists were included from one of three practice settings: fee‐for‐service private practice, full‐time academic medicine, or a large health maintenance organization.Most physicians, regardless of clinical specialty or practice setting, report that they advocate exercise and calcium supplementation. Few physicians prescribe estrogen replacement therapy (ERT) for the majority of their postmenopausal patients. Although there are minimal differences among the three types of practice settings examined, ERT varies markedly by clinical specialty. Of the gynecologists surveyed, 37% report prescribing ERT for the majority of their postmenopausal patients to prevent osteoporosis compared to only 7 and 5% of general internists and cardiopulmonary specialists, respectively (χ2= 45.3,p<0.0001).Although the efficacy of exercise and calcium supplementation to prevent osteoporotic fractures has not been well established, these measures are commonly advocated by both generalists and subspecialists. Although gynecologists are significantly more likely to prescribe ERT to prevent osteoporosis than the other clinical specialists, in general very few physicians prescribe ERT for most postmenopausal patients. This is despite the documented benefit of ERT in preventing osteoporotic fractures. Reasons are explored for physician reluctance to presc

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050303

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractMalignant hypercalcemia is caused by both increased bone resorption and enhanced tubular reabsorption of calcium.First, the response to an infusion of APD was compared in two groups of patients: 23 with breast cancer versus 20 with squamous cell cancer. The decrease in plasma calcium was smaller in the latter group (p<0.05 at day 14), due to increased tubular reabsorption of calcium (TmCa/GFR 2.20 ± 0.05 versus 2.58 ± 0.06 mmol/liter;p<0.001), whereas the degree of bone resorption reflected by urinary hydroxyproline was identical. Therefore, at a given initial plasma calcium level, the type of tumor (on which TmCA/GFR depends) seems to be a determinant for the effectiveness of the treatment.Second, the response to the initial treatment was compared with that to a second treatment with the same dose in 12 patients whose malignant hypercalcemia relapsed. Within 9 days, plasma calcium decreased from 3.46 ± 0.10 to 2.50 ± 0.10 mmol/liter after the first course, but only from 3.37 ± 0.08 to 2.79 ± 0.09 mmol/liter after the second course (p<0.01). TmCa/GFR was similar before the first and the second treatment and did not vary during the days following the infusion of APD. Initial urinary hydroxyproline was slightly but not significantly higher before the second treatment. It dropped following both APD courses, but to a lesser extent after the second treatment, reflecting higher bone resorption or possible resistance to bisphosphonate.In conclusion, both the degree of tubular reabsorption of calcium (which depends on tumor type) and that of bone resorption modify the response of malignant hypercalcemia to APD, bone resorption playing the key role for the loss of efficacy in case of retrea

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050304

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study reports a method to describe and analyze the structure of the trabecular pattern seen on radiographs of the distal radius. The structure is measured and related to the bone mineral density (BMD) of the lumbar spine measured by dual‐photon absorptiometry.Radiographs of hand and wrist combined with additional information of the bone mineral density of the vertebrae serve as testing material. With a computer‐aided imaging system, a part of the depicted radius is scanned. The image is filtered and segmented into a bilevel picture consisting of a light network with dark meshes. Seven features of the bilevel picture are measured and analyzed.It is shown that six features correlate significantly with the bone mineral density measured at the lumbar spine, although the correlations between the trabecular pattern and the BMD are too weak to allow precise predictions of BMD values for individuals. Nevertheless, the correlations confirm the existence of a relationship between the radiographic trabecular pattern and the bone mineral density of the lumbar spine. The method is worth being further developed for use on individual patients. It provides a noninvasive tool to make an objective and quantitative assessment of the trabecular patt

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050305

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTo perform a fast and reproducible analysis in bone histomorphometry, we developed an automatic method for calculating static and dynamic parameters.A color automatic image analyzer (SAMBA 200) was used to obtain the usual parameters of bone histomorphometry: bone volume (Cn‐BV%TV), osteoid volume (Cn‐OV%BV), and osteoid surface (Cn‐OS%BS). A specialized algorithm was designed for calculation of the mineral apposition rate (MAR). Eroded surface (Cn‐ES%BS) was read in a semiautomatic mode using a cursor.To validate this program, we input 30 samples from patients with bone disease (20 osteoporosis, 6 renal osteodystrophy, 2 osteomalacia, and 2 hyperparathyroidism) using manual and automatic modes.The results obtained showed a highly significant correlation with the usual manual method for all parameters: OS/BS,r= 0.93; OV/BV,r= 0.98; MAR,r= 0.90. With the automatic method, larger values were found for osteoid parameters and MAR and lower values for BV/TV. There were no statistical differences for OV/BV and MAR when compared to the reference manual method.This study establishes that automatic measurements of osteoid parameters and MAR can be performed by a fast analyzer with as good reproducibility and accuracy as the manual

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050306

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTo assess the effects of physical activity patterns on trabecular bone density in college women, we studied three groups of nonsmoking eumenorrheic women with different (but chronic) exercise regimens. There were nine sedentary (SED) women exercising less than 1 h/week, nine women who performed aerobic (AER) exercise greater than 2.5 h/week, and nine women who supplemented aerobics with muscle‐building activities (MB) for more than 1 h/week. Resting energy expenditure, calorie, protein, and calcium intake, total body weight, and body mass index were not statistically different among the three groups. AER and SED women had similar lumbar bone mineral density (BMD). MB women had significantly greater spinal bone density (p<0.007 versus SED, AER). IGF‐1 (insulin‐like growth factor) concentrations were greatest in MB (p<0.01), and hours muscle building per week correlated with IGF‐1 (r= 0.86,p<0.03). For all 27 women (mean age 24.5 years), body mass index was the single best predictor of lumbar BMD (r= 0.42,p<0.03); hours in muscle‐building exercise per week conferred an additive effect on lumbar BMD.This cross‐sectional study of young women suggests chronic muscle‐building exercises may augment lumbar bone mass. The additive effect of anaerobic exercise on bone density may be mediated by both local weight‐bearing changes and possible s

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050307

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThe relation of zinc to the aging skeleton was investigated in 140 women aged 36–85 years, mostly postmenopausal, who attended the Jerusalem Osteoporosis Center.Osteoporosis was determined by lumbar spine radiograms (Smith index). Bone density (BD) of the distal radius was assessed by Compton spectroscopy and bone mineral content (BMC) at the same site by single‐photon absorptiometry. Urine samples (24 h) were analyzed for zinc (UZn), hydroxyproline (UHP), calcium (UCa), magnesium (UMg), and phosphorus (UP) and expressed per gram creatinine.Patients with definite osteoporosis (n= 94) compared to subjects with borderline or no osteoporosis (n= 34) had a significantly higher mean age (67.4 versus 58.6 years), postmenopausal age (PMA, 19.9 versus 11.0), UZn (811 versus 581), UHP (23.5 versus 18.2), and UMg (90.4 versus 74.3). Urinary calcium UCa and phosphorus UP were similar in both groups. The bone mass measurements BD, BMC, and CI were lower in the osteoporotic group. Hyperzincuria (UZn above 800 μg/g creatinine) was found in 41 osteoporotic patients (45%) compared to 6 subjects in the control group (17%). In view of the positive correlation between UZn and age (r= 0.35,p= 0.001) and to eliminate the effect of age, a separate analysis was performed for 66 subjects under the age of 65 in whom the mean age was similar for the osteoporosis patients (n= 38) and control group (n= 28). Nevertheless, the osteoporosis patients still had a significantly higher mean UZn and UHP.A woman who does not suffer from any acute or metabolic disease, with urinary zinc of 800 μg/g creatinine, had about a 90% chance of having definite osteoporosis. UZn correlated with UHP and thus the increased UZn may reflect an increased rate of bone resor

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050308

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractSerum levels of bone gla protein (BGP) have been reported to increase with aging and hence to reflect an age‐related increase in bone remodeling activity. To evaluate the relationship between aging and serum BGP levels in a study of longitudinal design, we measured BGP concentrations in 77 normal men at 6 month intervals over a 3 year period. Mean BGP levels at the onset (4.95 ± 1.5 ng/ml) increased significantly during the study (p= 0.004), and the mean of individual BGP slopes was positive (0.38 ± 0.6 ng/ml per year,p= 0.0001). The rate of change in BGP was not related to serum creatinine levels or dietary calcium int

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050309

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThe beagle dog model has been established by our laboratory as a useful animal model to study bone loss after cessation of ovarian function. Previously we demonstrated bone loss associated with an osteoblastic insufficiency at 4 months after ovariohysterectomy (OHX). This study was designed to evaluate by four sequential monthly bone biopsies the development and course of the histologic bone abnormalities after OHX. We found cancellous bone volume, trabecular density, and wall thickness to be decreased (p<0.05) and trabecular separation increased (p<0.05) as early as 1 month after OHX. After 2 months, there was a decrease in mineralizing surface and mineral apposition rate (p<0.05). Volume and surface of osteoid were increased after 3 months (p<0.05), and there was an increase in the number of osteoblasts (p<0.01). No histologic signs of increased resorption were observed during the experiment. However, the findings of low bone volume with decreased trabecular density and increased separation without a change in trabecular plate thickness 4 weeks after OHX suggest that a dramatic increase in resorption must have taken place soon after OHX. These results point to an early phase of initiation of bone loss related to hyperresorption followed by a maintenance phase of low bone mass ascribable to an osteoblastic insufficiency. The events that stimulate the early initiating phase after cessation of ovarian function, the factors contributing to it, and the direct demonstration of hyperresorption await further studies.

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050310

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractParathyroid hormone (PTH) is a major activator of renal proximal tubule 25‐hydroxyvitamin D3‐1‐hydroxylase (1‐OHase). Chronic metabolic acidosis (CMA) inhibits 1‐OHase and reduces circulating 1,25‐dihydroxyvitamin D3[1,25‐(OH)2D3] levels in rats fed a low‐Ca diet (LCD, 0.002% Ca). To examine the cellular mechanism whereby CMA inhibits 1‐OHase, PTH‐dependent renal 1‐OHase activity and cAMP were measured in proximal tubules isolated from rats fed LCD for 14 days and made acidotic by the addition of 1.5% ammonium chloride to the drinking water. Serum 1,25‐(OH)2D3and proximal tubule 1‐OHase activity and cAMP content were lower in acidotic rats. hPTH‐(1–34) (10−7M) in vitro increased cAMP content to equivalent concentrations in tubules from rats with CMA and from nonacidotic controls; however, PTH increased 1‐OHase activity only in tubules from nonacidotic animals. Although forskolin increased tubule cAMP content to equivalent levels in tubules from acidotic and nonacidotic rats, 1‐OHase activity declined in tubules from nonacidotic rats and remained suppressed in acidotic tubules.The results suggest that chronic metabolic acidosis inhibits the PTH activation of 1‐OHase through alteration of one or more steps in a cAMP‐independent messenger system. PTH and forskolin can increase cAMP production by acidotic and nonacidotic proximal tubules; however, 1‐OHase activity is not restored to normal in acidotic tubules and no

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050311

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY