ISSN:0884-0431    

DOI:10.1002/jbmr.5650100202

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe report the establishment of a human fetal osteoblast cell line derived from biopsies obtained from a spontaneous miscarriage. Primary cultures isolated from fetal tissue were transfected with a gene coding for a temperature‐sensitive mutant (tsA58) of SV40 large T antigen along with a gene coding for neomycin (G418) resistance. Individual neomycin resistant colonies were screened for alkaline phosphatase (AP)‐specific staining. The clone with the highest AP level, hFOB 1.19, was examined further for other osteoblast phenotypic markers. Incubation of hFOB cells at the permissive temperature (33.5°C) resulted in rapid cell division, whereas little or no cell division occurred at the restrictive temperature (39.5°C). Both AP activity and osteocalcin (OC) secretion increased in a dose‐dependent manner following dihydroxyvitamin D3(1,25‐D3) treatment when cultured at either temperature. However, AP and 1,25‐D3‐induced OC levels were elevated in confluent hFOB cells cultured at 39.5°C compared with 33.5°C. Treatment of hFOB cells with 1–34 parathyroid hormone (PTH) resulted in an increase in cAMP levels. Upon reaching confluence, hFOB cultures went through programmed differentiation and formed mineralized nodules as observed by von Kossa staining. Further, immunostaining of postconfluent, differentiated hFOB cells showed that high levels of osteopontin, osteonectin, bone sialoprotein, and type I collagen were expressed. Therefore, the clonal cell line hFOB 1.19 provides a homogeneous, rapidly proliferating model system to study certain stages of human osteoblas

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100203

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

年代:1995

数据来源: WILEY

摘要:

AbstractBiosynthesis of bone sialoprotein (BSP) by a human osteoclastic cell line (FLG 29.1) during its differentiation induced by phorbol 12‐myristate 13‐acetate (TPA) was studied using metabolic radiolabeling experiments. The FLG 29.1 cells were metabolically radiolabeled with [3H] glucosamine and [35S] sulfate, and the labeled glycoproteins were analyzed by anion exchange chromatography, sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS‐PAGE) and immunoprecipitation experiments. One of the major glycoproteins synthesized by the TPA‐treated FLG 29.1 cells was sulfated, had an identical electrophoretic mobility to purified BSP, and could be immunoprecipitated with a specific antibody against human BSP (LF 6). Thus, this glycoprotein was tentatively identified as the BSP. Furthermore, mRNA for BSP was also detected in TPA‐treated FLG 29.1 cells by RNA‐polymerase chain reaction. Most BSP synthesized by FLG 29.1 cells remained cell‐associated, and this is in contrast with those synthesized by osteoblasts, where the protein is rapidly released into the extracellular matrix. Immunocytochemistry using an anti‐BSP antibody showed a prominent paranuclear (suggestive of Golgi apparatus) localization of BSP in the TPA‐treated FLG 29.1 cells after permeabilization, while untreated cells were not significantly immunostained. Localization of BSP at the plasma membrane was also demonstrated in the TPA‐treated FLG 29.1 cells by the fluorescence‐activated cell sorting analysis. Since TPA has been demonstrated to induce expression of various osteoclastic characteristics in FLG 29.1 cells, induction of BSP expression by TPA suggests that the protein may play a role during the differentiation process of osteoclasts or in functions of dif

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100204

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of combined administration of 24R,25‐dihydroxyvitamin D3(24,25‐(OH)2D3) and 1α‐hydroxyvitamin D3(1α‐(OH)D3) was studied in 24 non‐dialyzed patients with chronic renal insufficiency (CRI), matched pair‐wise as to age, sex, and creatinine clearance (Cr.cl). Low Ca intake had been supplemented beforehand. Then, 1α‐(OH)D3(mean dose 0.55 μg daily) was given orally to all patients for 3 months (T0toT3). Subsequently, patients were assigned randomly to 6 months further treatment either with 1α‐(OH)D3alone (Group A) or with 1α‐(OH)D3plus a high dosage of 24,25‐(OH)2D3(50 μg orally, twice weekly) (Group B). Histomorphometry was performed atT0T3, andT9. In both groups iPTH was equally suppressed, into the lower normal range. Whereas in Group A, serum Ca rose steadily and Cr.cl declined, in Group B both parameters levelled off betweenT6andT9. AtT9, in Group A the elevated resorption and osteoid indices had normalized markedly, but osteoblasts (Ob.Pm) and mineralizing boundaries (M.Bd) were depressed considerably betweenT3andT9. In contrast, in Group B, preservation of Ob.Pm and improved mineralizing activity were observed (M.Bd atT9>T3>T0). Resorption indices hardly changed. In the patients with high Ob.Pm atT0, cancellous bone area increased significantly. This was not observed in Group A. Thus, in Group B, osteoblast recruitment appeared maintained and M.Bd appeared normalized. Decline of remodeling toward an adynamic state with an increased risk of hyperc

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100205

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe examined the spontaneous bone loss in two populations of healthy postmenopausal women, who were followed for 9.5 and 14.5 years without any treatment influencing the calcium metabolism. The bone mass was measured in different skeletal areas: the distal forearm, the lumbar spine, the proximal femur, and the total skeleton. The spontaneous bone loss in the distal forearm, the lumbar spine, and the total skeleton was fitted to an exponential model as a function of years since menopause. The overall bone loss averaged 20–25% of premenopausal bone mass 16 years after menopause. The patterns of bone loss were, however, different for the axial and the peripheral skeleton. Thus, the bone loss in the distal forearm approached a more linear model with a more consistent bone loss throughout the observation period. In contrast, the lumbar spine showed no significant loss 8 years after menopause. This arrest in bone loss could not be explained by the presence of degenerative changes in the lumbar spine and/or aortic calcifications, although these changes significantly contributed to 14% increased bone mineral density (p<0.001). We conclude that bone loss averages 20–25% over the initial 16 years of menopause regardless of skeletal site and that patterns of bone loss are different in the axial and peripheral skele

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100206

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

年代:1995

数据来源: WILEY

摘要:

AbstractTo investigate the dose‐dependent effects of risedronate on cancellous bone remodeling, adult female beagle dogs were treated with either placebo, 0.1, 0.5, or 2.5 mg/kg/day of risedronate orally in an intermittent cyclic regimen (7 days on 21 days off), repeated three times. Iliac cancellous bone samples were subjected to histomorphometric analysis and three‐dimensional (3‐D) kinetic reconstruction of the remodeling site was performed. In the 0.1 mg/kg dose group, resorption and activation indices were no different from the placebo group. However, wall thickness was increased resulting in a positive bone balance at the level of the remodeling unit. In the 0.5 and 2.5 mg/kg dose groups, a dose‐dependent reduction in activation frequency and tissue level bone formation was observed. Resorption rates were also significantly decreased, 60% and 80% for the 0.5‐ and 2.5‐mg/kg groups, respectively. An approximate 25% reduction in final erosion depth was noted in both these groups. Analyses of the growth curves of the bone packet confirmed that the kinetics of the growth of a completed packet were different in the 0.5‐ and 2.5‐mg/kg dose groups compared with placebo. These changes were associated with a significant increase in the final wall thickness in both groups indicating no net impairment of osteoblast function. These increases in wall thickness in combination with the reductions in final erosion depth in the 0.5 and 2.5 mg/kg groups resulted in a significant dose‐dependent positive bone balance. This pharmacological profile suggests that risedronate may be of therapeutic utility in the treatment of metabolic bone diseases where reductions in activation frequency and resorptive cell activity at the level of the remodeling unit are a

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100207

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn previous studies, we reported that basic fibroblast growth factor (bFGF) regulates insulin‐like growth factor messenger RNAs and protein levels in the osteoblastic MC3T3‐E1 cells. In the present study, we examined the expression of insulin‐like growth factor binding proteins (IGFBPs) in MC3T3‐E1 cells and determined whether bFGF altered IGFBP mRNAs and protein levels. Since previous studies suggested that IGFBPs can inhibit DNA synthesis stimulated by IGF‐I, we wondered whether the mitogenic effect of bFGF was altered by exogenous IGFBP‐3. Confluent MC3T3‐E1 cells were serum‐deprived for 24 h and then treated with bFGF for 6–24 h. In control cultures, MC3T3‐E1 cells expressed the mRNAs for IGF‐I, IGF‐II, and IGFBP‐2, 4, 5, and 6 but not IGFBP‐1 or 3. A 24 h treatment with bFGF at 10−8M decreased IGF‐I mRNA by 97%, IGF‐II mRNA by 73%, IGFBP‐2 by 64%, IGFBP‐4 by 73%, IGFBP‐5 by 95%, and IGFBP‐6 by 65%. The inhibitory effect of bFGF on IGF‐I and IGFBP mRNA levels was not altered by aphidicolin, an inhibitor of cell replication. bFGF 10 nM decreased IGF‐I levels determined by radioimmunoassay after acidification by 45% and 72% at 24 and 48 h, respectively. Western ligand blot for IGF binding proteins revealed that MC3T3‐E1 cells expressed IGFBPs of 24, 30, and 34 kD. Treatment with bFGF 10−8M decreased the levels of the 24 and 30 kD band at 24 h but increased the 34 kD band. Western immunoblot revealed that the 24 kD protein was IGFBP‐4 and the 34 kD band was IGFBP‐2. bFGF at 10−9‐10−8M increased thymidine incorporation into DNA (TdR) in a dose‐dependent manner. When exogenous IGFBP‐3 was added to the cultures there was a significant reduction in DNA synthesis while the mitogenic effect of bFGF was not blocked. In summary, bFGF not only regulates IGF‐I mRNA and protein levels but it also regulates the IGF‐II mRNA and mRNA and protein levels of the IGFBPs expressed in MC3T3‐E1 cells. However, the mitogenic effect of bFGF may be independent of endogenous IGF‐I. These results m

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100208

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

年代:1995

数据来源: WILEY

摘要:

AbstractOsteocyte‐like cells were prepared by sequentially treating calvaria from newborn rats with collagenase and chelating agents. On a reconstituted gel of basement membrane components, cells from the third collagenase digest displayed a round shape and expressed the highest level of alkaline phosphatase with minimal osteocalcin deposition into the matrix. On the other hand, cells derived from the interior after EDTA treatment exhibited well‐developed dendritic cell processes and expressed essentially no alkaline phosphatase. The latter population also showed quite distinct characteristics such as higher extracellular activities of casein kinase II and ecto‐5′‐nucleotidase and the extracellular accumulation of a large amount of osteocalcin associated with mineral. These diverse phenotypic and protein expressions as well as the sites from which each population of cells were recovered strongly suggest that we have isolated osteoblastic and osteocytic cells. Bone sialoprotein II was extracellularly phosphorylated by casein kinase II in osteocytic cells but not in osteoblastic cells. We discuss the possibility that differentiation of young osteocytes from osteoblasts may facilitate the biochemical sequence of mineral deposition in the bo

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100209

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe measured the heels of 43 women who had recently sustained a hip fracture and 86 age matched controls, using an Achilles® ultrasound device. Average BUA, SOS, and Stiffness were significantly lower in fractured patients (p<0.0001). We also estimated ultrasound parameters for patients as a function of controls and found the mean BUA to be −1.09 SD compared with controls, the mean SOS −0.89 SD, and the mean Stiffness −0.98 SD. Femoral BMD measured at the neck, Ward's triangle, and the trochanter with a DPX Plus® was also significantly lower in fractured patients (p<0.0001). The increased risk of hip fracture associated with low ultrasound values was estimated with logistic regression analysis for each bone parameter, adjusted for height and weight. The adjusted regression coefficients associated with BUA, SOS, Stiffness, and BMD were all significant (p<0.0001) demonstrating the influence of all ultrasound and DXA parameters on the risk of hip fracture. After adjusting the logistic regressions for BMD neck, BUA, SOS, and Stiffness were still significant independent predictors of hip fracture. Sensitivity and specificity of all measures were analyzed with the area under the ROC curve which were for BUA, 0.77 ± 0.04; for SOS, 0.75 ± 0.04; for Stiffness, 0.78 ± 0.04; and for BMD, 0.74 ± 0.04. We determined the range for the best compromise between sensitivity and specificity of BUA, 97–98 dB/MHz; SOS, 1482–1487 m/s; Stiffness 59–62% Young Adult; and of BMD, 0.64–0.69 g/cm. The area under the ROC curves of BUA, SOS, Stiffness, and DXA were compared and no statistically significant difference was found. Patients with trochanteric fractures had significantly lower ultrasound parameters than those with cervical fractures (SOS and Stiffnessp= 0.001, BUAp= 0.009), whereas no significant difference was found for DXA parameters (BMD neck, BMD Ward, and BMD trochanterp≥ 0.5). Some previous studies showed a lower bone density in patients with trochanteric fractures and suggested that the two types of fractures might correspond to a different process. Our results suggest that ultrasound is better correlated to the type of fracture than DXA, discriminates subjects with hip fracture equally well as DXA, and does indeed provide an indication of fracture ri

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100210

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

年代:1995

数据来源: WILEY

摘要:

AbstractAlthough corticosteroid therapy is associated with the development of osteopenia, it is unclear whether the cause of osteopenia in inflammatory bowel disease (Crohn's disease and ulcerative colitis) is related to corticosteroid therapy or other disease‐related variables. Patients with Crohn's disease (a diffuse gastrointestinal disease) could have greater osteopenia than patients with ulcerative colitis because of small bowel disease and secondary malabsorption of calcium and vitamin D. A cross‐sectional analysis of consecutive patients with Crohn's disease and ulcerative colitis was undertaken. Bone density was determined by measurements of the L2–L4 spine, the total hip, and Ward's triangle using dual energy X‐ray absorptiometry (DXA). A number of clinical parameters were recorded prior to bone density evaluation and analyzed by univariate and subsequently multivariate analysis to determine possible predictors of osteopenia. Of the 26 patients with Crohn's disease, diminished bone density (a Z score of at least −1) was found at the hip in 64% and at the spine in 44%; and of the 23 patients with ulcerative colitis diminished bone density was found at the hip in 43% and at the spine in 48%. Among all the variables tested, only corticosteroid use was a statistically significant predictor of diminished bone density (p= 0.025 for the spine and hip andp= 0.005 for Ward's triangle). Disease diagnosis (Crohn's disease compared with ulcerative colitis) did not predict or correlate with diminished bone density. No obvious associations were seen between the measurements of any serum hormones or biochemistries and bone density, although the patients using corticosteroids had lower serum calcium levels than the nonusers. Separate multivariate analyses were performed for males and females. Corticosteroid use was statistically significantly associated with diminished bone density in females but not in males. All patients with inflammatory bowel disease (both Crohn's disease and ulcerative colitis), independent of whether or not they have small bowel disease, who have been using corticosteroids for long periods should have their bone density status investigated, since they have a high prevalence of diminished bone density and, therefore, are at risk for bone fractures. Further studies are required to sort out factors that may make bone density in females more sensitive to the effects of corticosteroids than that

ISSN:0884-0431    

DOI:10.1002/jbmr.5650100211

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

年代:1995

数据来源: WILEY