ISSN:0884-0431    

DOI:10.1002/jbmr.5650091202

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

年代:1994

数据来源: WILEY

摘要:

AbstractTo assess the effect of age and disease on mineral distribution at the distal third of the tibia, bone mineral content (BMC) and bone mineral density (BMD) were measured at lumbar spine (spine), femoral neck (neck), and diaphysis (Dia) and distal epiphysis (Epi) of the tibia in 89 healthy control women of different age groups (20‐29,n= 12; 30‐39,n= 11; 40‐44,n= 12; 45‐49,n= 12; 50‐54,n= 12; 55‐59,n= 10; 60‐69,n= 11; 70‐79,n= 9), in 25 women with untreated vertebral osteoporosis (VOP), and in 19 women with primary hyperparathyroidism (PHPT) using dual‐energy x‐ray absorptiometry (DXA; Hologic QDR 1000 and standard spine software). A soft tissue simulator was used to compensate for heterogeneity of soft tissue thickness around the leg. Tibia was scanned over a length of 130 mm from the ankle joint, fibula being excluded from analysis. For BMC and BMD, 10 sections 13 mm each were analyzed separately and then pooled to define the epiphysis (Epi 13‐52 mm) and diaphysis area (Dia 91‐130 mm). Precision after repositioning was 1.9 and 2.1% for Epi and Dia, respectively. In the control group, at any site there was no significant difference between age groups 20‐29 and 30‐39, which thus were pooled to define the peak bone mass (PBM). Mean decrease in BMD from PBM (mean + SEM) was significant after age 49 at Epi (‐11.8 + 12.7%), after age 54 at spine (‐14.2 + 5.9%) and neck (‐11.2 + 8.6%), and after age 59 at Dia (‐10.9 + 6.9%). Epiphysis and diaphysis BMC but not BMD were correlated with body weight (r= 0.22,p<0.04 for both sites). In patients with PHPT mean tibial BMD expressed as Z scores was significantly lower than in controls, from 39 to 130 mm but was similar to that in controls from 0 to 39 mm as well as at spine and neck. In patients with untreated VOP, mean BMD (Z scores) was lower than in controls at spine and neck as well as tibia from 0 to 52 mm (p<0.01) but not between 52 and 130 mm. We conclude that DXA measurement at tibia is a suitable tool to assess bone loss and distribution of bone mass between Dia (cortical) and Epi (with a substantial amount of trabecular bone) in a single weight‐bea

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091203

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe evidence for a role of parathyroid hormone in the bone loss after the menopause remains controversial. This study examines the effect of parathyroidectomy on femoral trabecular bone volume, thickness, and spacing and biochemical markers of bone turnover in the oophorectomized rat. Female Sprague‐Dawley rats 3 months old were double sham operated (sham), oophorectomized (OPX), parathyroidectomized (PTX), or oophorectomized and parathyroidectomized (O/P) under halothane anesthesia. At 9 weeks postoperation, femoral trabecular bone volume (BV/TV) was lower in OPX and O/P rats compared with sham or PTX animals (BV/TV, %, mean + SEM): sham 25.9 + 0.5, OPX 15.1 + 0.9, PTX 24.1 + 0.9, O/P 17.3 + 0.5;p<0.001). Urinary hydroxyproline excretion, serum osteocalcin, and alkaline phosphatase activity were higher in OPX and O/P rats compared with control animals at 3 weeks postoperation (OHPE μM GF, mean + SEM: sham 1.37 + 0.16, OPX 2.16 + 0.26, PTX 0.95 + 0.21, O/P 1.92 + 0.22,p<0.005; osteocalcin, μg/liter, sham 31.8 + 1.8, OPX 33.7 + 2.7, PTX 24.5 + 2.1, O/P 34.3 + 2.1,p<0.025; alkaline phosphatase, U/liter, sham 90 + 3, OPX 125 + 9, PTX 87 + 9, O/P 116 + 11, p<0.005). These data indicate postoophorectomy bone loss is not prevented by parathyroidect

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091204

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper aims to examine the relative contributions made by alcohol and iron overload and hypovitaminosis C to the osteoporosis associated with African hemosiderosis. To characterize this bone disorder, we examined double‐tetracycline‐labeled iliac crest bone biopsies and serum biochemistry in 53 black male drinkers, 38 with (Fe+) and 15 without (Fe−) iron overload, and in controls. We reasoned that abnormalities found in both patient groups were likely to be caused by alcohol abuse and those found only in the Fe+group to be caused by iron overload and hypovitaminosis C (iron/C−). The patient groups differed only with respect to greater erosion depth (p<0.05) and abnormal markers of iron overload in the Fe+group. Ascorbic acid levels were lower in the Fe+group than in controls (p<0.001). Bone volume and trabecular thickness were significantly lower in both patient groups compared with controls and therefore likely caused by alcohol. There were no positive correlations between formation and erosion variables in either patient group, which suggests uncoupling of formation from erosion, possibly as a result of alcohol abuse. Prolonged mineralization lag time associated with thin osteoid seams was found in 32% of patients, affecting both groups. This rules out osteomalacia and suggests osteoblast dysfunction, probably caused by alcohol. The number of iron granules in the marrow correlated with erosion depth (r= 0.373,p<0.01), trabecular number (r= ‐0.295,p<0.05), and trabecular separation (r= 0.347,p<0.05). Abnormalities in these variables were therefore attributed mainly to iron/C−. Several formation variables were significantly directly correlated with indicators of iron overload, suggesting that iron/C−does not adversely affect bone formation. We conclude that alcohol abuse was predominantly associated with thinning of trabeculae and iron overload and hypovitaminosis C with increased erosion depth and disconnection of the trabecular network. Osteomalacia

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091205

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe investigated the structural requirements for the binding of bisphosphonates to bone mineral and the relation between their affinity for bone and their effects on bone resorption in vitro. For this we used fetal mouse long bones in culture and bisphosphonates with variable R1and R2structures. In addition, we studied the effect of structural differences in the incorporation of calcium into bone. We found that bisphosphonates containing a hydroxyl group in the R1position have the highest affinity for bone mineral. This was related to their capacity to inhibit the incorporation of calcium into long bones but not to their antiresorptive potency. The latter was primarily determined by R2. Furthermore, the effect of bisphosphonates on calcification, but not on resorption of bone explants, was mainly determined by the mode of addition. The continuous presence of bisphosphonate during culture inhibited calcification even at very low concentrations, but short incubation of the bones with relatively high concentrations had no effect. This is probably a result of differences in the availability of the compound to the process of calcification. Because, in vivo, the more potent bisphosphonates inhibit resorption without adversely affecting mineralization of the skeleton and they disappear rapidly from the circulation after administration, we suggest that cultures of bone explants incubated with bisphosphonates for short times rather than cultures in which the drugs are continuously present provide more accurate information about the in vivo effect of these compounds on both resorption and calcification.

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091206

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis study was performed to investigate whether the circadian variation in urinary pyridinium crosslinks is related to physical activity, age, the menopause, and asymptomatic osteopenia. We measured urinary pyridinoline/creatinine (Pyr/Cr) and deoxypyridinoline/creatinine (D‐Pyr/Cr) in 9 healthy premenopausal women in two 27 h studies, before and at the end of 5 days of total bed rest. Both Pyr/Cr and D‐Pyr/Cr showed highly significant circadian variations, with the peak at night and the nadir during the day (p<0.001). The 5 days of complete bed rest produced no changes in the circadian pattern, but a general increase of 28% was observed in pyridinium crosslinks. A group of 12 healthy, early postmenopausal women (aged 55 + 2 years), 12 healthy, elderly postmenopausal women (aged 73 + 1 years), and 12 elderly osteopenic but otherwise healthy women (aged 73 + 1 years) were also studied for 27 h. All three groups showed highly significant (p≤ 0.001) circadian variations in the urinary excretion of pyridinium crosslinks. As expected, both Pyr/Cr (p<0.05) and D‐Pyr/Cr (p<0.001) increased at the time of menopause, but the circadian variations in Pyr/Cr and D‐Pyr/Cr were similar in all groups studied. We conclude that the circadian variation in the urinary excretion of pyridinium crosslinks is independent of physical factors. Furthermore, the circadian variation in pyridinium crosslinks was not related to age, menopausal status, or asymptomatic o

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091207

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

年代:1994

数据来源: WILEY

摘要:

AbstractHip fractures can be separated into femoral neck (cervical or intracapsular) or trochanteric (extracapsular). Trochanteric fractures have been associated with up to twice the short‐term mortality of cervical fractures in the elderly. Fracture type may be influenced by the fall direction and local differences in proximal femur strength properties. We previously demonstrated that fall characteristics and body habitus, in addition to femoral bone mineral density, play a dominant role in the prediction of hip fracture in elderly fallers. To examine the association of these determinants with hip fracture type, we assessed fall characteristics, body habitus, and site‐specific bone mineral density measurements in 112 elderly hip fracture patients (85 women and 27 men, mean age 85 years) 1 week after an acute hip fracture. Trochanteric BMD was 13% lower in women and 11% lower in men for patients with trochanteric fracture than in those with femoral neck fracture (p<0.01). A stepwise multiple logistic regression indicated that trochanteric BMD (decrease of 1.0 SD, adjusted OR 4.6, 95% CI 2.0‐9.5,p<0.0001) and femoral neck BMD (increase of 1.0 SD, adjusted OR 3.0, 95% CI 1.6‐5.9,p= 0.0003) were independently associated with trochanteric fracture. Fall characteristics, body habitus, gender, and age were not associated with hip fracture type. We conclude that a relatively low trochanteric BMD or a high femoral neck BMD was associated with a trochanteric hip fracture and that site‐specific trochanteric BMD determinations should be measured when assessing risk of trochanteric hip fractures in th

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091208

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

年代:1994

数据来源: WILEY

摘要:

AbstractVertebral height ratios are used to define vertebral deformity in clinical and epidemiologic studies of vertebral osteoporosis. However, few data have been obtained on the variation in these ratios in different populations using standard methods. We examined vertebral morphometric measurements obtained in a population survey from three centers: Malmö (Sweden), Montceau‐les‐Mines (France), and Graz (Austria), to study the influence of sex and the population center on vertebral height ratios. Radiographs were obtained according to a standardized protocol, and morphometric measurements, anterior heightHa, central heightHc, and posterior heightHp, made in Berlin. The height ratios anterior,Ha/Hp, central,Hc/Hp, posterior I,Hp/Hp', and posterior II,Hp/Hp″ (Hp' = posterior height of vertebrae above,Hp″ = posterior height of vertebrae below) were calculated for each vertebra from T4 to L4. The mean and standard deviation of these ratios for each sex and each center were derived using a statistical trimming procedure to normalize the distribution. Threshold values for defining grade 1 and grade 2 deformities, wedge, biconcavity, and compression, were calculated using these parameters. Anterior and central vertebral height ratios were smaller in males than females (p<0.01). There were significant differences between the three centers (p<0.01) both in the trimmed mean values for anterior and central vertebral height ratios and in the thresholds derived using standard criteria for defining wedge and biconcavity deformity. The data confirm the impression from single‐center studies that vertebral height ratios vary between populations and suggest that reference values for vertebral height ratios should be derived separately for males and females within individual populations wheneve

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091209

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

年代:1994

数据来源: WILEY

摘要:

AbstractBone density is not the unique factor conditioning bone strength. Trabecular bone microarchitecture also plays an important role. We have developed a fractal evaluation of trabecular bone microarchitecture on calcaneus radiographs. Fractal models may provide a single numeric evaluation (the fractal dimension) of such complex structures. Our evaluation results from an analysis of images with a varying range of gray levels, without binarization of the image. It is based on the fractional brownian motion model, or more precisely on the analysis of its increment, the fractional gaussian noise (FGN). The use of this model may be considered validated if two conditions are fulfilled: the gaussian repartition and the self‐similarity of our data. The gaussian repartition of intermediate lines of these images was tested on a sample of 32,800 lines from 82 images. Following a chi‐square goodness‐of‐fit test, it was checked in 86% of these lines for α = 0.01. The self‐similarity was tested on 20 images by two estimators, the variance method of Pentland and the spectrum method of Fourier. Self‐similarity is defined by lined‐up points in a log‐log plot of the FGN spectrum or of the variance as a function of the lag. We found two self‐similarity areas between scales of analysis ranging from 105 to 420 μm, then above 900 μm, where linear regression produced high mean correlation coefficients (r≥ 0.97). Following this validation, we studied the reproducibility of this new technique. Intra‐ and interobserver reproducibility, influence of transferring the region of interest, and long‐term reproducibility were assessed and given CV of 0.61 ± 0.15, 0.68 ± 0.47, 0.53 ± 0.16, and 2.07 ± 0.84%, respectively. These data have allowed us to validate the use of this fractal model by checking the fractal organization of our radiographic images analyzed by the model. The good reproducibility of successive x‐rays in the same subject allows us to undertake population studies and

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091210

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlthough hormone replacement therapy is effective in preventing postmenopausal bone loss, it fails to cause a return of bone mass to normal in patients with established osteoporosis. Similarly, in the ovariectomized rat, estrogen administration protects the skeleton from bone loss but fails to reverse this once it has occurred. However, physiologically produced sex steroids may, in contrast to conventional methods of sex steroid administration, be capable of restoring bone mass in osteopenic states. To investigate this question, we analyzed the effect of treatment with the LHRH agonist buserelin for varying durations, and subsequent cessation thereof, on histomorphometric indices of rat cancellous bone. Female rats 13 weeks old were given daily SC injections of vehicle or buserelin as follows: vehicle days 1‐90; vehicle days 1‐150; vehicle days 1‐60, buserelin days 61‐90; vehicle days 1‐60, buserelin days 61‐90, vehicle days 91‐150; vehicle days 1‐30, buserelin days 31‐90; vehicle days 1‐30, buserelin days 31‐90, vehicle days 91‐150; buserelin days 1‐90; buserelin days 1‐90, vehicle days 91‐150. At the end of the treatment period, animals were killed, tibiae removed, and histomorphometric indices assessed at the secondary spongiosa of the proximal metaphysis. Analysis of vaginal smears confirmed that buserelin rapidly suppressed ovulation, which quickly returned once treatment was stopped. We found that administration of buserelin for 30, 60, or 90 days reduced cancellous bone volume because of a reduction in both the number and thickness of trabeculae. The bone loss was at least partly a result of increased bone resorption, because buserelin significantly increased osteoclast surface and number. After cessation of buserelin administration, trabecular number remained unchanged but trabecular thickness increased in all groups, returning to that of vehicle‐treated animals. We conclude that buserelin reduces cancellous bone volume in female rats by decreasing trabecular number and thickness and that the latter, but not the former, is restored to normal by the return of

ISSN:0884-0431    

DOI:10.1002/jbmr.5650091211

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

年代:1994

数据来源: WILEY