摘要:

AbstractTo determine whether a family history of osteoporosis identifies individuals with low bone mineral density (BMD), we studied 1477 white elderly (aged 60–89 years), noninstitutionalized ambulatory men (n= 600) and women (n= 877) from the Rancho Bernardo, California cohort. Family history data on biologic parents and full sisters were obtained by questionnaire. BMD of the lumbar spine and hip was measured using dual‐energy x‐ray absorptiometry. After adjustment for age, body mass index, history of cigarette smoking, thiazide use, and estrogen use, men and women with a family history of osteoporosis had lower BMD than those with a negative family history. In men, a positive family history was associated with lower BMD at the hip (p= 0.01), whereas in women a significant association was observed for the spine (p= 0.02). BMD decreased in a stepwise fashion with an increasing number of family members with a history of osteoporosis. Analysis of the effect of parental history of osteoporosis on BMD showed a significant relation between paternal (but not maternal) history and lumbar spine BMD in both sexes and a significant relation between maternal (but not paternal) history and hip BMD only in men. The relative risk of having categoric osteopenia was highest in those whose fathers had a history of osteoporosis (RR 2.16, 95% CI = 1.38–3.37). A similar association was found for subjects with fractures. These results were not explained by differential awareness of family history in individuals with known osteoporosis, because the prevalence of family history was unrelated to personal history of osteoporosis in men and only weakly related in women. The positive predictive value of family history as an indicator of categorically defined low bone density was 22% in men and 24% in women, although in women this value increased to 33% when father's history alone was considered. The negative predictive value of overall family history was 65% in men and 81% in women. Overall, these data suggest that clinicians who ask patients about family history of osteoporosis should ask about both

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090602

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:

AbstractOsteogenic protein‐1 (OP‐1, also called BMP‐7) is a bone morphogenetic member of the TGF‐β superfamily. In the present study, we examined the effect of recombinant human OP‐1 on cartilage and bone formation in organ cultures of metatarsal long bones of mouse embryos and compared the OP‐1 effects with those of human TGF‐β1and porcine TGF‐β1and β2. Cartilage formation was determined by measurement of longitudinal growth of whole bone rudiments during culture and by the incorporation of35SO4into glycosaminoglycans. Mineralization was monitored by45Ca incorporation in the acid‐soluble fraction and by measuring the length of the calcifying center of the rudiment. Toluidine blue‐stained histologic sections were used for quantitative histomorphometric analysis. We found that OP‐1 stimulated cartilage growth as determined by sulfate incorporation and that it increased remarkably the width of the long bones ends compared with controls. This effect was partly caused by differentiation of perichondrial cells into chondrocytes, resulting in increased appositional growth. In contrast to OP‐1, TGF‐β1and β2inhibited cartilage growth and reduced the length of whole bone rudiments compared with controls. In the ossifying center of the bone rudiments, both OP‐1 and TGF‐β inhibited cartilage hypertrophy, growth of the bone collar, and matrix mineralization. These data demonstrate that OP‐1 and TGF‐β exhibit opposite effects on cartilage growth but similar effects on osteogenesis in embryonic mouse long bone cultures. Since both OP‐1 and TGF‐β have been demonstrated in embryonic cartilage and bone, these results suggest that they act as autocrine or para

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090603

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 involvement of protein kinase C (PKC), cAMP‐dependent protein kinase (PKA), and other phosphorylation mechanisms in the rapid desensitization of the [Ca2+]iresponse to parathyroid hormone (PTH) stimulation was investigated in osteoblast‐like UMR‐106 cells. A 5 minute preincubation of the cell suspension with phorbol 12,13‐dibutyrate (PDB) decreased the response to PTH in a concentration‐dependent manner. 1‐Oleoyl‐2‐acetyl‐r‐glycerol (OAG) pretreatment likewise decreased the PTH response. Staurosporine, a potent protein kinase inhibitor, completely prevented the desensitization caused by PDB. These PDB and staurosporine effects were also observed in 3 mM EGTA‐containing medium ([Ca2+]free<10−8M). A 5 minute pretreatment of cells with 1 μM forskolin had no effect on the calcium response to PTH. Homologous and PDB‐induced desensitizations differed in several respects. Staurosporine pretreatment resulted in only a slight restoration of the PTH response under conditions of homologous desensitization. Chronic treatment with phorbol ester prevented the desensitization of the PTH response by acute phorbol treatment but not the homologous desensitization. Both homologous and PDB‐induced desensitization were relieved by alkaline phosphatase treatment, consistent with the involvement of phosphorylation in the desensitization. This alkaline phosphatase effect on desensitization was inhibited by L‐phenylalanine. These results suggest that PTH receptor homologous desensitization involves phosphorylation process(es) other than

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090604

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:

AbstractGap junctions are channels connecting cells that function in cell‐to‐cell communication. Gap junctions are abundant in osteoblastic cells. Membranes enriched for gap junction plaques were obtained by differential centrifugation, followed by treatment of the membranes with potassium iodide and sarkosyl before sucrose density gradient centrifugation. Electron microscopy showed that the preparation was enriched for electrondense membranes consistent with gap junctions. Coomassie Blue staining of SDS‐PAGE preparations revealed a prominent band at approximately 41 kD. Western analysis with a site‐directed antibody, CT‐360 (D. Laird, California Institute of Technology, Pasadena, CA), to the C‐terminal portion of the rat heart connexin 43 molecule was positive in the MC3T3‐E1 cell line, a phenotypic osteoblastic cell line derived from normal neonatal mouse calvariae. Western analysis using a monoclonal antibody, R5.21C, to rat liver connexin 32 was negative. Additionally, a prominent band at 59 kD was detected by CT‐360 in both gap junction‐enriched preparations and cell lysates. Treatment of diluted samples of gap junction‐enriched preparations with sulfhydryl reducing agents in combination with detergents resulted in the enhancement and diminution of the 41 and 59 kD bands, respectively. Immunoprecipitation following [35S]methionine/[35S]cysteine labeling revealed a significant band detected at 122 kD in addition to the 41 kD band. To demonstrate functional gap junctions, transfer of lucifer yellow dye to surrounding cells was monitored after microinjection of a target cell. Between passages 10 and 25 in culture, functional cell coupling was found in approximately 70% of injected cells. Coupling was detected within 1–2 minutes after injection. Simultaneous microinjection of the CT‐360 antibody with lucifer yellow resulted in the decoupling of cells. In conclusion, (1) MC3T3‐E1 cells possess a 41 kD protein that is recognized by connexin 43 antibody to rat heart gap junction; (2) multimers of the MC3T3‐E1 gap junctions occur in the preparation; and (3) functional coupling demonstrated by dye transfer may be regulated by region(s) in the C termin

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090605

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 shafts of ulnae from 110 g male rats were cultured, and after a period of 5 h preincubation one of each pair of bones was either loaded cyclically (500 g, 1 Hz, 8 minutes) to produce physiologic strains (‐1300 με) or treated with exogenous prostacyclin (PGI2) or prostaglandin E2(10−6M, 8 minutes) in the presence or absence of 17β‐estradiol (10−8M). PGI2, PGE2, and loading stimulated almost immediate increases in glucose 6‐phosphate dehydrogenase (G6PD) activity in osteocytes and osteoblasts. This increase was uniform throughout the section with exogenous PGs in the medium but was related to local strain magnitude in loading. Elevated G6PD levels in response to loading and PGI2persisted for 18 h, by which time, ALP activity in surface osteoblasts was elevated and [H]proline incorporation into collagen increased. PGE2produced similar immediate and sustained increases in G6PD activity and [H]proline incorporation after 18 h but no change in ALP activity. Bones cultured for 18 h with 17β‐estradiol increased their [H]proline incorporation, as did those loaded, and treated with PGI2and PGE2. Loading and PGI2but not PGE2produced similar proportional increases in [H]proline incorporation above the increased baseline of estradiol alone. These results suggest that estrogen and loading together produce a greater osteogenic response than either separately. If so, estrogen withdrawal would result in a rapid fall in bone mass to establish a new equilibrium appropriate to the reduced effectiveness of the loading‐related stimulus. Such a fall in bone mass is a characteristic feature of estrogen withdrawal

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090606

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 mechanism by which interleukin‐1 (IL‐1) and transforming growth factor α (TGF‐α) regulate prostaglandin synthesis has been examined in the clonal mouse osteoblastic cell line MC3T3‐E1. Cells were grown in DMEM containing 10% fetal calf serum. Prostaglandin E2(PGE2) production was determined by radioimmunoassay or by prelabeling cells with [H]arachidonic acid, followed by high‐performance liquid chromatography (HPLC) analysis of the labeled products released into the medium. Prostaglandin G/H synthase (PGHS) mRNAs were quantified by northern blot analysis using [32P]labeled cDNA probes. By HPLC, PGE2was the major prostanoid produced under basal or stimulated conditions. No release of thromboxane or 6‐keto‐PGF1αinto the medium was detected. PGE2production was stimulated approximately 7‐ to 14‐fold by IL‐1 (1 ng/ml) and 3‐ to 8‐fold by TGF‐α (30 ng/ml) after 24 h. In combination, however, IL‐1 and TGF‐α caused a synergistic 37‐ to 71‐fold increase in PGE2accumulation. PGHS‐1 mRNA levels were maximally increased approximately 2‐ to 3‐fold by IL‐1 and 1.5 to 2.5‐fold by TGF‐α after 24 h; the combination of IL‐1 and TGF‐α produced only an additive 3‐ to 6‐fold increase. Western blotting revealed a corresponding 3‐fold increase in immunoreactive PGHS‐1 protein in response to combined IL‐1 and TGF‐α. PGHS‐2 mRNA was increased 1.4‐fold by TGF‐α at 1 h, and the combination of IL‐1 and TGF‐α caused a 1.7‐fold increase. After 3.5 h, IL‐1 caused a dramatic induction of PGHS‐2 mRNA levels but TGF‐α alone no longer had an effect. However, the combination of IL‐1 and TGF‐α produced an increase in PGHS‐2 mRNA levels that was twice that of IL‐1 alone. The effects of IL‐1 and TGF‐α on the release of preincorporated [H]arachidonic acid from membrane phospholipid stores were examined at early time points in the presence of indomethacin. After 1 h, arachidonic acid release was enhanced 3‐fold by IL‐1, 1.5‐fold by TGF‐α, and 12‐fold by IL‐1 and TGF‐α in combination. In conclusion, the synergistic actions of IL‐1 and TGF‐α on PGE2synthesis in MC3T3‐E1 cells involve multiple regulatory sites, incl

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090607

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 define and identify metabolic bone disease and mineral alterations induced by chronic heavy alcoholism in patients without severe liver damage, we studied a prospective series of unselected patients admitted to a 300‐bed general hospital in Barcelona (Spain). A total of 26 chronic heavy drinkers of more than 150 g/day for at least 3 years were included. A general analytic and hormonal study, including liver biopsy in cases with any abnormality in liver function tests, and plasma and urine biochemistry with calcium regulating hormones and osteocalcin levels were determined. A transiliac bone biopsy after double‐tetracycline labeling, with histomorphometric study of undecalcified bone, was performed. Statistical analysis was adjusted by age and sex by means of logistic regression. A total of 26 (20 men and 6 women) chronic alcohol abusers were studied. After adjustment for age and sex, alcoholic patients showed slight but significantly increased concentrations of plasma calcium (9.56 ± 0.56; OR = 17.93; 95% CI 3.17–101.48) and decreased cPTH (0.36 ± 0.11; OR = 0.097;95% CI 0.018–0.528) compared with controls. Osteocalcin values were low (1.49 ± 0.89, normal range 1.8–6.6). There was a significant decrease in bone volume, BV/TV (12.56 ± 5.29; OR = 0.06; 95% CI 0.01–0.34), with increased resorption surfaces, ES/BS (4.28 ± 2.43; OR = 9.86; 95% CI 2.16–45.07), and increased osteoclast number, N.Oc/TA (0.21 ± 0.37; OR = 6.41; 95% CI 1.27–32.25). Dynamic parameters were abnormal (Fisher's exact test), as follows: decreased BFR/BS (0.023 ± 0.028 versus 0.049 ± 0.020;p= 0.013), MAR (0.309 ± 0.269 versus 0.771 ± 0.529;p= 0.029), MS/BS (3.743 ± 4.433 versus 5.890 ± 2.882;p= 0.008, and OMR (2.402 ± 2.833 versus 3.057 ± 0.083;p= 0.011) and increased MLT (175.80 ± 405.49 versus 34.53 ± 8.117;p= 0.008). We conclude that chronic alcohol consumption induces osteopenia with low turnover and increased osteoclast number and resorption surfaces. The increase in plasma calcium levels and decreased PTH suggests a primary effect of alcohol on bone, resulting in bone loss and calcium infusion from bone into plasma. These effects were observed in the abse

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090608

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:

AbstractUsing immunohistochemical methods we studied the tissue localization of the extracellular matrix proteins osteopontin (OPN), osteocalcin (OC), and dentin sialoprotein (DSP) during the formation of acellular and cellular cementum in newly born rats. In the layer of acellular cementum of developing incisor and molar teeth we found a very strong staining for OPN but not for DSP or OC. Many cells immediately adjacent to acellular cementum and PDL cells were also positive for OPN but not for DSP or for OC. In contrast, cellular cementum in molar teeth stained strongly for OPN and OC but not for DSP. Consistent with these observations, the cells engaged in the formation of cellular cementum (cementoblasts and cementocytes) reacted strongly for OPN and OC but not for DSP. In advanced stages of dentinogenesis, both crown and root odontoblasts and dentin stained for OPN, OC, and DSP. Cells and matrices of surrounding alveolar bone stained for OPN and OC but not for DSP. We conclude that cementoblasts and cementocytes of cellular cementum produce OPN and OC but not DSP and thus express an osteoblast‐like, not an odontoblast‐like, phenotype. The cells responsible for the production of acellular cementum are likely cells of the PDL in close contact with the dental root surface. These fibroblast‐like cells express OPN but not OC or DSP and accordingly express only a partial osteoblastic phen

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090609

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:

AbstractTreatment of mouse MC3T3‐E1 cells with ascorbic acid initiates the formation of a collagenous extracellular matrix and synthesis of several osteoblast‐related proteins. We recently showed that ascorbic acid dramatically increases alkaline phosphatase and osteocalcin mRNAs and that this induction is blocked by inhibitors of collagen triple‐helix formation (Franceschi and Iyer, J Bone Miner Res 7:235). In the present study, the relationship between collagen matrix formation and osteoblast‐specific gene expression is explored in greater detail. Kinetic studies revealed that ascorbic acid increased proline hydroxylation in the intracellular procollagen pool within I h and stimulated the cleavage of type 1 collagen propeptides beginning at 2.5 h. Mature α1(I) and α2(I) collagen components were first detected at 10 h and continued to increase in both cell layer and culture medium for up to 72 h. Ascorbic acid also increased the rate of procollagen secretion from cell layers to culture medium. The secretion of another matrix protein, fibronectin, was only slightly affected. Alkaline phosphatase or its mRNA was first detected 2–3 days after ascorbic acid addition, but osteocalcin mRNA was not seen until day 6. Two inhibitors of collagen triple‐helix formation, ethyl‐3,4‐dihydroxybenzoate and 3,4‐dehydroproline, inhibited procollagen hydroxylation and alkaline phosphatase induction. 3,4‐Dehydroproline also inhibited the induction of alkaline phosphatase and osteocalcin mRNAs. Surprisingly, induction was not blocked if cells were exposed to ascorbic acidbeforeinhibitor addition. Alkaline phosphatase was also partially inhibited if cells were grown in the presence of purified bacterial collagenase. These results indicate that the induction of osteoblast markers by ascorbic acid does not require the continuous hydroxylation and processing of procollagens and suggest that a stable, possibly matrix‐associated signal is generated at early times after ascorbic acid addition that allows subsequent induction of o

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090610

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:

AbstractTransforming growth factor β (TGF‐β) is one of the most abundant of the known growth regulatory factors stored within the bone matrix. When bone is resorbed, TGF‐β is released in an active form and is a powerful bone growth stimulant. When injected into the subcutaneous tissue over the calvarial surface of rodents, it rapidly causes proliferation of the periosteal layer and accumulation of new woven bone. In this report, we describe the effects of TGF‐β1on first subcultures of fetal rat osteoblasts obtained from calvarial bones and cultured from confluence with ascorbic acid and β‐glycerophosphate. Under these conditions, nodules with characteristics of normal bone appear by day 8. Similar to experiments described by Antosz et al., TGF‐β added to confluent cultures inhibited the formation of bone nodules. Both the number and total area of the nodules were quantitated and shown to be completely inhibited by 2 ng/ml of TGF‐β1. TGF‐β also impaired the expression of genes associated with bone formation, including type I collagen, alkaline phosphatase, osteopontin, and osteocalcin. TGF‐β also inhibited the expression of mRNA for the bone morphogenetic protein 2 (BMP‐2). These results, showing suppression of markers representative of osteoblast differentiation, suggest that the effects of TGF‐β to stimulate bone formation in vivo are not likely a result of effects on differentiated mineralizing osteoblasts but, as suggested by previous studies, more likely are caused by effects on osteoblast precursors. These results also suggest that endogenous BMP‐2 expression in fetal rat calvaria cells is importan

ISSN:0884-0431    

DOI:10.1002/jbmr.5650090611

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