摘要:

AbstractFew studies have examined the multifactorial risk factors of bone mass in Asian populations. This cross‐sectional study was designed to explore relationships between bone mass and environmental variables, including dietary and life‐style factors, in Japanese women living in Japan. A total of 178 Japanese women completed the study: 89 premenopausal, ages 35–40, and 89 postmenopausal, ages 55–60. Midradial bone mineral content (MBMC) and bone mineral content per unit area, referred to as bone density (MBMD), were measured using single‐photon absorptiometry. The major results of this investigation were the following: (1) The postmenopausal women differed significantly from the premenopausal women in having lower radial bone parameters, lower mean height, later age of menarche, and higher dietary intakes of carbohydrates, vegetables, and milk with a lower intake of caffeine. (2) Current protein intake was a positive correlate of MBMC in both groups. (3) Intake of vegetables (leafy green, yellow, orange, and white) and current milk intake were positively associated with MBMC in the postmenopausal women. (4) For the premenopausal women, irregular menstrual cycles was a negative correlate of MBMC, and for the postmenopausal women, years of menopause was negatively associated with MBMC and MBMD. Longitudinal studies are needed to establish more conclusively associations among diet, life‐style, and reproductive history and bone mass of Jap

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060702

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

年代:1991

数据来源: WILEY

摘要:

AbstractA simple technique has been developed to identify the resorption lacunae excavated by avian osteoclasts in vitro. Briefly, devitalized bovine bone wafers, with cells in situ, are fixed, stained with toluidine blue, and then examined by reflected light microscopy. Resorption pits are clearly visible using a x 10 objective, even when the resorbed areas are covered by a confluent layer of cells. The technique can be used to quantify the plan area, depth, and volume of the excavations. Depth and volume are assessed using the x 50 objective lens. This technique has been used to investigate the effects of retinyl acetate and EHDP on bone resorption.

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060703

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

年代:1991

数据来源: WILEY

摘要:

AbstractAcute osteoporosis after spinal cord injury is related to an early increase in osteoclastic resorption. Healthy subjects subjected to bed rest similarly increase their osteoclast number in trabecular bone. Bisphosphonates possess a highly antiosteoclastic activity. The effects of a 120 day bed rest period, with or without etidronate therapy on cortical bone were measured in 15 subjects. Cortical thickness and cortical porosity were measured on transiliac bone biopsies taken before and after the bed rest period. Osteoclasts were detected histo‐chemically and were counted with a semiautomatic image analyzer. Cortical thickness, cortical porosity, and cortical osteoclast number were not significantly modified in subjects submitted to bed rest alone. In the etidronate‐treated patients, cortical bone mass parameters were also found to be unaffected, but the most striking feature was that the osteoclast number was unchanged. Trabecular osteoclasts, on the contrary, were increased in the untreated subjects (+95.2%) but decreased in the treated subjects (‐78%). Bone cells may have heterogeneous responses according to their trabecular or cortical location. Cortical osteoclasts seem to be unaffected by etidronate th

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060704

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

年代:1991

数据来源: WILEY

摘要:

AbstractBoth dual‐photon absorptiometry (DPA) using153Gd and dual‐energy x‐ray absorptiometry (DEXA) can be used for measurement of bone mineral content (BMC) and bone mineral density (BMD) of the total skeleton and its seven major regions. The short‐term precision (coefficient of variation, CV) of DEXA for total‐body BMD using the medium (20 minute) and fast (10 minute) speeds was 0.34 and 0.68% in 5 normal subjects; the corresponding CV in 5 osteoporotic females were 0.70 and 1.04%. The CV for BMD using DPA was 0.82% in 8 normal subjects and 0.70% in 12 osteoporotic patients. The CV for regional BMD using DPA was similar to fast‐speed DEXA, without significant differences (pNS); precision with medium‐speed DEXA was superior to DPA, and the differences were statistically significant (p<0.05) for head, spine, trunk, ribs, and pelvis. Total‐body measurements using both DPA and DEXA were done on 99 subjects (84 females and 15 males). Significant correlations (r= 0.98;p<0.001) were found between DEXA and DPA measurements of both BMC and BMD. There were also significant correlations (r= 0.94–0.98;p<0.001) between DEXA and DPA measurements of anatomic regions (head, trunk, spine, pelvis, ribs, arms, and legs). DPA and DEXA results for BMD of total skeleton, ribs, pelvis, and legs were similar (pNS), and statistically significant differences were found in head, spine, and arm measurements (p<0.01,p<0.01, andp<0.05, respectively); regression equations allowed adjustment of DEXA values in patients already measured with the e

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060705

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe have developed a simple method for the direct analysis of two‐dimensional trabecular structure. Using this method, we have compared the structure of the left and right iliac crest and the second lumbar vertebra and studied the relationship between two‐dimensional trabecular structure and the ultimate compressive stress of bone samples from the second lumbar vertebra. Transverse cores were taken from the left and right iliac crests and second lumbar vertebrae of 35 subjects (12 females) who died suddenly. The trabecular structure was subdivided into nodes (node count) and free ends (free end count), which were expressed per square millimeter of cancellous space. A node was defined as the point of junction between two or more trabeculae; a free end was defined as the end of a trabecula that was unconnected in the plane of the section to any other trabecular element. The following struts were defined by drawing a line between the nodes and the free ends: node to node, node to free end, free end to free end, and cortex‐derived struts. Strut lengths were measured and expressed as a percentage of the total strut length and per square millimeter of cancellous space. Intra‐observer variation was generally low, with coefficients of variation for repeat measurements in the range 3.9–17.8%. There was no statistically significant difference between left and right iliac crests for any of the variables measured. With the exception of cortex‐derived struts, there was no statistically significant correlation between crests for any variable. When compared to the second lumbar vertebra, the iliac crest had a greater node count and node‐to‐node strut length, indicating a higher degree of connectedness. There was a significant correlation between the lumbar vertebra and iliac crest for node count and node‐to‐node strut length. Variables measured in the second lumbar vertebra correlated well with ultimate compressive stress, the strongest correlations being with free end‐to‐free end strut length (r= ‐0.75,p<0.0005) and node‐to‐free end strut length (r= 0.76,p<0.0002). In both the second lumbar vertebra and iliac crest, node count, node‐to‐node strut length, and free end‐to‐free end strut length correlated significantly with age. The method reported here requires inexpensive equipment and is reproducible. Two‐dimensional trabecular structure in the iliac crest has greater connectedness compared to that in the second lumbar vertebra, although there is a relationship between the two sites. The structural variables measured in the lumbar vertebra are indicative of ultimate compressive stress at that site. Similar relationships between the structural variables and age are seen in the iliac crest and second lumbar vertebra. This type of analysis should provide important quantitative information concerning the changes in trabecular structure with age and in disease, as well as the ability of different drug tre

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060706

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe have shown that ATP increases cytosolic Ca2+in UMR‐106 cells through P2‐purinergic receptor stimulation (Calcif Tissue Int 45:251‐254). This response was further characterized using cells loaded with indo‐1/AM or prelabeled with [3H]inositol. ATP elicited a rapid transient increase in Ca2+from 148 to 540 nM, followed by a biphasic decline (first rapid and then slower) to basal within 1 minute and then a late slow rise to 200 nM by 4 minutes. ADP also elicited a rapid transient increase, but this was followed by a second smaller transient and a later, slow increase above basal Ca2+. These transient increases in Ca2+induced by ATP and ADP were dose dependent, detected at 10−6M ATP and 10−7M ADP, and saturated at 10−4M with both nucleotides. The maximum increase in Ca2+was 20% greater with ATP than ADP. EGTA chelation of extracellular Ca2+abolished the biphasicity of the ATP‐induced Ca2+transient, the second ADP‐induced transient, and all late slower increases in Ca2+. Desmethoxyverapamil pretreatment attenuated the biphasicity of the ATP‐induced transient and the second peak elicited by ADP. Elevated extracellular Ca2+(5 mM) prevented the return to the basal level that normally follows the ATP‐induced Ca2+transient and amplified the sustained increase in Ca2+but had little effect on the response to ADP. IP3and IP4increased rapidly after addition of ATP, with I(1,4,5)P3increasing before I(1,3,4)P3. These data indicate that P2‐purinergic stimulation of UMR‐106 cells causes three consecutive responses in cytosolic Ca2+: (1) a transient increase due to IP3‐mediated mobilization of intracellular Ca2+; (2) a transient increase due in part to influx, probably associated with a Ca2+channel; and (3) a later sustained increase that req

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060707

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis study used the ionophore, A23187, to examine the hypothesis that the regulation of alkaline phosphatase and phospholipase A2activity by vitamin D3metabolites in cartilage cells is mediated by changes in calcium influx. Confluent, fourth‐passage cultures of growth zone and resting zone chondrocytes from the costochondral cartilage of 125 g rats were incubated with 0.01‐10 μM A23187. Specific activities of alkaline phosphatase and phospholipase A2were measured in the cell layer and in isolated plasma membranes and matrix vesicles. There was an inhibition of alkaline phosphatase specific activity at 0.1 μM A23187 in resting zone cells and at 0.1 and 1 μM in growth zone chondrocytes. At these concentrations of ionophore, the45Ca content of the chondrocytes was shown to increase. Both the plasma membrane and matrix vesicle enzyme activities were inhibited. There was no effect of ionophore on matrix vesicle or plasma membrane phospholipase A2in either cell type. In contrast, alkaline phosphatase activity is stimulated when growth zone chondrocytes are incubated with 1,25‐(OH)2D3and in resting zone cells incubated with 24,25‐(OH)2D3. Phospholipase A2activity is differentially affected depending on the metabolite used and the cell examined. Addition of ionophore to cultures preincubated with 1,25‐(OH)2D3or 24,25‐(OH)2D3blocked the stimulation of alkaline phosphatase by the vitamin D3metabolites in a dose‐dependent manner. The effects of ionophore were not due to a direct effect on the membrane enzymes since enzyme activity in isolated membranes incubated with A23187 in vitro was unaffected. These results suggest a role for calcium in the action of vitamin D metabolites on chondrocyte membrane enzyme activity but indicate that mechanisms other than merely Ca2+influx per

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060708

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

年代:1991

数据来源: WILEY

摘要:

AbstractOsteoporosis and hip fractures are less common and bone mass is greater in black than in white women. To determine if bone mass is greater in black than in white children, bone mineral density (BMD) of the midradius by single‐photon absorptiometry and BMD of the lumbar spine (L1‐L4), trochanter, and femoral neck by dual‐photon absorptiometry were measured in 20 black boys, 18 black girls, 33 white boys, and 35 white girls between the ages of 7 and 12 years. Mean age (10.4 ± 0.3 versus 10.2 ± 0.2 years) and body weight (39 ± 2 versus 38 ± 2 kg) in the blacks and whites, respectively, were not different in the two groups, and the ages and weights of the boys and girls were not different from each other. BMD were significantly greater in black than in white children at each site, in the black than in white boys at the trochanter and femoral neck, and in the black than in white girls at each site. In both races, BMD varied directly with age and body weight. Multivariate analysis showed that BMD were greater at the midradius, lumbar spine, trochanter, and femoral neck in the black than in the white children, that BMD of the lumbar spine was greater in the girls than in the boys, and that BMD of the trochanter and femoral neck were greater in the boys than in the girls. There were significant partial correlations between race and BMD and between BMD and body weight at each site, between sex and BMD at the lumbar spine, trochanter, and femoral neck, and between age and BMD at the midradius, trochanter, and femoral neck. Race, sex, age, and body weight together accounted for 49‐66% of the variation in bone mass. Thus, BMD of the midradius, spine, and hip are greater in black than in white children, body weight and age are important determinants of bone mass, and some sex differences in bone mass are present

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060709

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

年代:1991

数据来源: WILEY

摘要:

AbstractRecently we characterized the immobilization‐related osteopenia in adult rats and showed that it is caused by increased bone resorption and decreased bone formation (Weinreb et al. 1989Bone10:187). To assess the effect of age on disuse osteopenia, this study investigated the effects of immobilization on bone turnover in very young, suckling rats. The 15‐day‐old rats underwent unilateral hind limb immobilization by sciatic neurectomy; the contralateral limb was left intact and served as control. Experimental or sham‐operated animals were killed after 0, 2, 4, or 12 days postsurgery. Dry, fat‐free weight and ash weight were determined in both femora, and both tibiae were subjected to static and dynamic histomorphometry. Immobilization caused a progressive deficit in bone mass in the immobilized limb compared to the contralateral intact limb but did not affect femoral longitudinal growth. The total mineral content in the immobilized femora was 13.6% less than that in the intact limb by day 12. Concomitantly, tibial cancellous bone area and perimeter declined in the immobilized limb by 37.3 and 32.2%, respectively. This reduction in bone mass in the tibiae of immobilized limbs was associated with increased bone resorption, expressed as osteoclast perimeter, number of osteoclasts per mm surface, and number of osteoclasts per mm2tissue area. Bone formation was reduced as a result of impaired osteoblast activity as evidenced by (1) decreased endocortical and trabecular mineral apposition rate; (2) reduced trabecular mineral formation rate; (3) decreased percentage of ash of the femoral dry weight; and (4) increased volume of unmineralized osteoid in the tibial metaphysis. These data indicate that osteoblasts in very young rats are sensitive to mechanical disuse and exhibit impaired function within a short period after the onset of immobilization. They also suggest that mechanical unloading inhibits mineralization to a greater extent than matrix deposition, leading to the production of hypomineral

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060710

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe extrarenal synthesis of 1,25‐dihydroxyvitamin D [1,25‐(OH)2D] is a characteristic of activated macrophages and has been demonstrated to occur in vitro in synovial fluid macrophages from patients with inflammatory arthritis. To examine whether such synthesis occurs in vivo, 19 patients with rheumatoid arthritis, 5 patient controls, and 5 healthy controls received a challenge oral dose of 250 μg 25‐hydroxyvitamin D3(25‐OHD3) and the serum 1,25‐(OH)2D3response was measured. The median rise in serum 1,25‐(OH)2D3was significantly greater (22 pg/ml) in the rheumatoid patients compared to either of the control groups (8 pg/ ml), although the increase in precursor 25‐OHD3was similar in all groups. The serum 1,25‐(OH)2D concentration did not rise above the normal upper limit in any of the control subjects but exceeded the normal range in 8 of the rheumatoid patients. Extrarenal 1,25‐(OH)2D synthesis is substrate dependent, unlike renal 1α‐hydroxylation, which is homeostatically controlled. Excessive 1,25‐(OH)2D3synthesis in the rheumatoid group on raising the 25‐OHD3concentration is indicative of nonrenal production of the hormonal metabolite. Further evidence for substrate‐dependent extrarenal synthesis came from measurements of 25‐OHD and 1,25‐(OH)2D in paired serum and synovial fluid samples from 19 patients with inflammatory arthritis, including 15 with rheumatoid arthritis. Synovial fluid 1,25‐(OH)2D was usually present at a lower concentration than serum 1,25‐(OH)2D, with which it was strongly correlated (Kendall'sR= 0.46,P<0.001). Synovial fluid 1,25‐(OH)2D was also correlated with synovial fluid 25‐OHD (R= 0.55,P<0.001), but serum 1,25‐(OH)2D and 25‐OHD were not related. At high synovial fluid 25‐OHD concentrations the 1,25‐(OH)2D level in synovial fluid exceeded that in serum, suggesting local synthesis of 1,25‐(OH)2D within the synovium. Distribution of vitamin D metabolites between serum and synovial fluid could not be explained by the relevant concentrations of vitamin D binding protein. Together these results provide strong evidence for nonrenal synthesis of 1,25‐(OH)2D in patients with inflammatory arthritis. The extent of synovial synthesis of 1,25‐(OH)2D may be governed both by the severity of the inflammatory disease and by drug treatment. Such synthesis may be significant in the immunoregulatory system in the affected joint and may prove to have relevance to the development

ISSN:0884-0431    

DOI:10.1002/jbmr.5650060711

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

年代:1991

数据来源: WILEY