bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential distribution of insulin-like growth factors and their binding proteins within bone: Relationship to bone mineral density
Authors: Dr. Benedict Mark R. , Ayers David C. , Calore James D. , Richman Robert A.
Published: February 2010

To evaluate the possibility that insulin-like growth factors (IGFs) and their binding proteins (BPs) in bone play a role in regulating cortical bone formation in growing animals, we compared changes in IGF and IGF BP levels with changes in bone mineral density (BMD) at three different regions (proximal, middle, and distal) along the rabbit femoral shaft. BMD measured by dual-energy x-ray absorptiometry decreased progressively from proximal to distal regions of the shaft, from 0.449 ± 0.005 to 0.354 ± 0.002 g/cm2 (mean ± SEM; n = 9), respectively; total protein concentrations also decreased toward the distal region. We extracted the IGFs and their BPs from bone by demineralization in 10% EDTA and 4 M guanidine-HCl (pH 4.5). The IGFs were then separated from their BPs by size exclusion HPLC. The pH of the extraction buffer profoundly influenced the recoveries of the IGFs and, to a lesser extent, the total protein; at least 100% more IGFs were recovered at acid (4.5) pH than at neutral (7.5) or basic (10.5) pH. The levels of IGF-I decreased markedly from proximal to distal regions, from 273 ± 27 to 100 ± 38 ng human IGF-I equivalent/g bone (or 103 ± 10 to 52 ± 11 ng human IGF-I equivalent/mg protein), respectively. IGF-II was uniformly distributed (385 ± 17 ng human IGF-II equivalent/g bone; mean of all three regions). Levels of the predominant 28–32 kD IGF BP doublet increased by about 100% from proximal to distal segments, regardless of whether the data were expressed per unit mass or protein. Thus, the differential distribution of bone-associated IGF-I paralleled that of BMD and total protein, whereas levels of the 28–32 kD bone IGF BP(s) were inversely related to cortical bone density.
Lack of evidence for rickets in the osteopetrotic rat mutation, toothless
Authors: Seifert Mark F.
Published: February 2010

A common, but paradoxic, feature among osteopetrotic human infants is the presence of rickets. This disorder of mineralization is manifested radiographically and histologically by increased growth plate cartilage and hypertrophic cell zone thickness and excess metaphyseal osteoid and biochemically by decreased serum calcium and phosphorus concentrations. Rickets has also been reported in two osteopetrotic animal mutations, the osteosclerotic (oc) mouse and the toothless (tl) rat. Although the phenotypic expression of the rachitic lesion in the oc mouse closely resembles that in affected humans, the results of the present study show that the lesion in the tl rat does not. Compared with normal littermates, histologic and morphometric analyses of tibial growth plate cartilage in tl rats up to 5 weeks of age showed age-related increases in thickness of the proliferative cell zone and decreases in thickness of the hypertrophic cell zone that were most apparent within the central, but not lateral, regions of the growth plate and areas of acellularity and failure of chondrocytes to transform synchronously from proliferative cell to hypertrophic cell phenotypes. Femoral ash content, composition, and accretion rates did not differ from those in normal rats during the first 5 weeks of life. These findings do not support the rachitic nature of the cartilage lesion in the tl rat. Rather, a chondrodysplastic disorder is suggested, which more closely resembles the cartilage defect present in this mutation.
Long-term effects of a treatment course with oral alendronate of postmenopausal osteoporosis
Authors: Rossini M. , Gatti D. , Zamberlan N. , Braga V. , Dorizzi R. , Adami S.
Published: February 2010

Several bisphosphonates are under investigation for the treatment and prevention of postmenopausal osteoporosis. Alendronate, one of these compounds, has been shown to inhibit bone turnover and induce substantial increases in bone mass, but little is known about the duration of its effects. This is considered important, keeping in mind the long half-life of bisphosphonate in bone. In this double-blind controlled study, two groups of 15 postmenopausal women with spinal bone mineral density (BMD) > 2 SD below adult mean peak without vertebral fractures were randomized to receive either alendronate, 20 mg/day, or placebo for 6 months. The treatment course with alendronate significantly suppressed all indices of bone turnover (hydrox-yproline, collagen crosslinks, and alkaline phosphatase activity) within 3 months, and a further slight decrease was observed in the subsequent 3 months. After treatment withdrawal, all indices of bone turnover slowly increased, and they attained the pretreatment values within 6–9 months. Lumbar spine BMD rose by 3.7% (± 1.7 SD) after 6 months of alendronate therapy but did not change 6 and 12 months after treatment withdrawal (4.6 ± 2.8 and 4.7 ± 2.6% versus baseline, respectively). In control patients a slow decrease in lumbar spine BMD was observed, but this was significant only at month 18 of the study. Femoral BMD did not significantly change in the alendronate group, but it slowly decreased in the control group at all sites of evaluation. The fractional loss became statistically significant versus both baseline and the active group by the end of the study only at the level of the femoral neck. These results may imply that the positive bone balance induced by alendronate is sustained long after stopping therapy, despite the reestablishment of pretreatment bone turnover.
Effect of administration and subsequent cessation of buserelin on cancellous bone of female rats
Authors: Dr. Tobias J.H. , Chambers T.J. , Gallagher A.
Published: February 2010

Although 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 ovulation on stopping treatment.
Pharmacokinetics of clodronate in renal failure
Authors: Saha H. , Castren-Kortekangas P. , Ojanen S. , Juhakoski A. , Tuominen J. , Tokola O. , Pasternack A.
Published: February 2010

The pharmacokinetic parameters describing the fate of one intravenous clodronate (disodium dichloromethane diphosphonate) dose was studied in 24 normal subjects and in 24 patients with different degrees of renal insufficiency. The aim of the study was to derive data for adjustment of dosage in relation to renal function. Disodium clodronate in serum and urine samples was analyzed by capillary gas chromatography with mass-selective detection. The renal clearance (CLR) of clodronate was highly dependent on renal function and declined successively with declining glomerular filtration rate (GFR). Plasma clearance (CLP) declined, too, but to a lesser degree than CLR. The impairment of renal function resulted in decreased cumulative urinary elimination of clodronate and increased total areas under the serum concentration-time curve (AUC0-∞). Hence, as the renal elimination of clodronate diminishes with decreasing GFR, there is a related retention of the substance. As a result of the present study, the following dosages are recommended: creatinine clearance (CLCr) from 50 to 80 ml/minute, 75-100% of normal dose; CLCr 12-50 ml/minute, 50-75% of normal dose; and ClCr < 12 ml/minute, 50% of normal dose. The results must be interpreted with caution in patients with malignancy and severe skeletal disease, in whom the nonrenal clearance may vary markedly.
Preliminary in situ identification of estrogen target cells in bone
Authors: Dr. Braidman Isobel P. , Davenport Lisa K. , Carter Howard D. , Selby Peter L. , Mawer Barbara E. , Freemont Anthony J.
Published: February 2010

Although estrogens profoundly influence skeletal growth and maturation, their mechanism of action is still unclear. To identify their target cells in bone, estrogen receptors were located by immunofluorescence using the H222 monoclonal antibody in cryosections (both undecalcified and briefly decalcified) of hyperplastic mandibular condyle (persistent asymmetric mandibular growth) from a 14-year-old girl and radius and ulna from an 18-month-old female pig (epiphyseal fusion) and from a 3-month-old guinea pig (epiphyses open). Bone was removed from the animals at the peak of estrus. The most striking feature in all three species was the high proportion (approximately 50%) of receptor positive osteocytes. Although all sections contained active bone-forming surfaces, we were unable to identify clearly osteoblasts or lining cells that were estrogen receptor positive. In pig bone only, distinctive groups of receptor positive chondrocytes, with a pericellular localization of collagen type 1, were detected above the growth plate but below secondary centers of ossification. This observation suggests that osteocytes are major skeletal estrogen target cells and may be involved in coordinating the response of surface bone cells to the hormone, and further that chondrocytes may be involved in estrogen-induced epiphyseal growth plate fusion.
Effects of tiludronate on bone loss in paraplegic patients
Authors: Dr. Chappard D. , Minaire P. , Privat C. , Berard E. , Mendoza-Sarmiento J. , Tournebise H. , Basle Mf , Audran M. , Rebel A. , Picot C. , Gaud C.
Published: February 2010

Immobilization secondary to spinal cord injury is associated with a marked and rapid atrophy of trabecular bone (disuse osteoporosis). This is due to an early increase of osteoclastic bone resorption associated with a pronounced decreased osteoblastic bone formation. Bisphosphonates are antiosteoclastic compounds and they have been effective in preventing disuse osteoporosis. However, some of them also depress osteoblastic activity and may impair the mineralization process. Tiludronate was shown effective in reducing bone resorption in several metabolic bone diseases without inducing mineralization defects. Twenty paraplegic patients (6 females and 14 males) were randomly assigned to three groups: 6 patients entered the placebo group; 7 patients received tiludronate 200 mg/day; and 7 received 400 mg/day. Histomorphometric analysis was performed on transiliac bone biopsies before and after 3 months treatment An insignificant decrease of bone volume was observed in the placebo group and the 200 mg group. In patients receiving 400 mg/day, a slight increase was noted. Osteoid parameters changed nonsignificantly in three groups although the 400 mg group exhibited a slight tendency to decrease osteoid volume and thickness. Eroded surfaces increased in all groups. The number of osteoclasts (identified histochemically by TRAP staining) increased in the placebo group but decreased in groups receiving tiludronate. Tiludronate appears effective in reducing bone resorption without impairing bone formation in a manner that preserved bone mass and bone cell coupling.
Biosynthesis of bone sialoprotein by a human osteoclast-like cell line (FLG 29.1)
Authors: Masi Laura , Brandi Maria Luisa , Robey Pamela Gehron , Crescioli Clara , Calvo Juan Carlos , Bernabei Pietro , Kerr Janet M. , DR. Yanagishita Masaki
Published: February 2010

Biosynthesis 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 differentiated osteoclasts.
Basic fibroblast growth factor regulates IGF-I binding proteins in the clonal osteoblastic cell line MC3T3-E1
Authors: Dr. Hurley Marja M. , Abreu Christine , Hakeda Yoshiyuki
Published: February 2010

In 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 10−8 M 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 10−8 M 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 10−9-10−8 M 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 may be important in understanding the role of bFGF in bone cell function.
Ultrasound discriminates patients with hip fracture equally well as dual energy X-ray absorptiometry and independently of bone mineral density
Authors: Schott A.M. , Weill-Engerer S. , Hans D. , Duboeuf F. , Delmas P.D. , Meunier P.J.
Published: February 2010

We 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 Stiffness p = 0.001, BUA p = 0.009), whereas no significant difference was found for DXA parameters (BMD neck, BMD Ward, and BMD trochanter p ≥ 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 risk independent of BMD.
Rheumatoid arthritis and bone mineral density in elderly women
Authors: Dr. Lane Nancy E. , Pressman Alice R. , Star Vicki L. , Cummings Steven R. , Nevitt Michael C.
Published: February 2010

Previous studies have suggested that women with rheumatoid arthritis (RA) have decreased bone mineral density (BMD) in both the appendicular and axial skeleton. The purpose of this investigation was to determine the association of RA and BMD from a community-based sample of ambulatory Caucasian women age 65 and over. BMD was measured by dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine and by single photon absorptiometry (SPA) at the distal radius and calcaneus. Study subjects included 120 postmenopausal women with RA who were further classified according to corticosteroid use, i.e., never users, current users, and ex-users, and 7966 age-similar controls. Elderly women with RA had a lower age-adjusted bone density of the distal radius, calcaneus, hip, and lumbar spine. Women with RA who were current users of steroids had the lowest BMD at both appendicular sites and at the hip, but those who never used steroids also had a significantly decreased BMD at all sites. The BMD of women with RA who had never used steroids remained significantly decreased at the distal radius, calcaneus, and hip after adjustment for age, BMD determinants, and functional outcomes of RA Functional outcomes of RA largely accounted for the lower BMD of women who were currently using steroids. Women with RA have lower appendicular and axial bone mass that is not attributable to the use of steroids. Those currently taking steroids have even lower appendicular and axial bone mass that may reflect their poorer functional outcome and is likely to increase the risk of fractures. Prevention of disability and avoidance of long-term steroid use may decrease the risk of fractures in elderly women with RA.
Tissue specificity and mechanism of vitamin D receptor up-regulation during dietary phosphorus restriction in the rat
Authors: Sriussadaporn Sutin , Wong Man-Sau , Pike Wesley J. , Favus Murray J.
Published: February 2010

Dietary phosphorus restriction up-regulates intestinal vitamin D receptor (VDR), but the tissue specificity of the up-regulation and the mechanism of receptor accumulation remain unknown. Therefore, the effects of low phosphorus diet (LPD) on VDR content in intestine, kidney, and splenic monocytes/macrophages were examined. Male Sprague-Dawley rats weighing 50–100 g were fed a normal diet (NPD; 0.6% Ca, 0.65% P) as controls followed by an LPD (0.6% Ca, 0.1% P) for 1–10 days (D1-D10). LPD rapidly decreased serum P levels by D1 from 11.11 ± 0.19 mg/dl (mean ± SE) to 4.98 ± 0.37 mg/dl (n = 9). LPD increased total serum Ca from 10.54 ± 0.09 mg/dl to 11.63 ± 0.15, 12.17 ± 0.15, and 12.39 ± 0.18 mg/dl by D1, D2, and D3, respectively, and then remained stable. Serum 1,25-(OH)2D3 rapidly increased from 123 ± 5.4 pg/ml to 304 ± 35 pg/ml by D1, reached a plateau through D5, and then gradually increased to 464.9 ± 27.7 pg/ml by D10. Intestinal VDR quantitated by ligand binding assay increased 3.5-fold from 169.6 ± 13.7 fmol/mg of cytosol protein in rats fed NPD (n = 12) to a peak of 588.3 ± 141.88 fmol/mg of protein by D3 (n = 6; p < 0.001) and then decreased to a plateau level of 2.5-fold greater than NPD (p < 0.05) during D5 to D10. In contrast, LPD did not up-regulate kidney or splenic monocyte/macrophage VDR. Northern blot analysis showed that intestinal VDR mRNA increased 2-fold by D2 (n = 3) of LPD and then gradually decreased to control levels after D5. In contrast, kidney VDR mRNA levels did not change during the first 5 days of P restriction and then subsequently decreased to 50% of NPD controls. The results of these studies indicate that VDR up-regulation during dietary phosphorus restriction is tissue-specific and that the mechanism of the up-regulation is time-dependent. Acutely (D1-D5), phosphorus restriction up-regulates intestinal VDR through increased VDR gene expression, whereas chronic (D5-D10) phosphorus restriction appears to alter VDR metabolism through nongenomic mechanisms that are consistent with prolongation of the half-life of the receptor. The nature of the tissue-specific regulation of VDR during phosphorus restriction remains to be determined.
Quantitative ultrasound and vertebral fracture in postmenopausal women
Authors: Bauer D.C. , Glüer C.C. , Genant H.K. , Stone K.
Published: February 2010

Quantitative ultrasound is a promising technique to evaluate fracture risk. To test the hypothesis that reduction of one ultrasound measurement, broadband ultrasound attenuation (BUA), is associated with an increased risk of vertebral fracture in postmenopausal women, we performed a cross-sectional analysis of 442 women aged 55–80 years enrolling in a clinical trial of alendronate. Prior to randomization, we obtained bone mineral density (BMD) measurements of the hip, spine, and whole body, radiographs of lateral lumbar and thoracic spine, and duplicate measurements of calcaneal BUA with a Walker Sonix UBA575. Vertebral fractures were defined by morphometry and semiquantitative reading by a radiologist. After adjustment for potential confounders, the relative risk of vertebral fracture was 1.8 (95% CI 1.4–2.3) for each standard deviation reduction in BUA; for each standard deviation reduction in BMD, the relative risk was 1.7 (95% CI 1.3–2.1) at the femoral neck, and 2.2 (95% CI 1.7–2.9) at the spine. Adjustment for hip, spine, or whole body BMD did not significantly alter the relation between BUA and vertebral fracture. For example, after adjusting for spine BMD, the relative risk of vertebral fracture was 1.5 (95% CI 1.1–2.0) for each standard deviation reduction in BUA. We conclude that low BUA is associated with the presence of vertebral fractures in postmenopausal women. The relation between BUA and vertebral fracture is similar to that observed for BMD and vertebral fractures. Furthermore, the relation between BUA and vertebral fracture persists after adjustment for BMD. Our findings suggest BUA measures qualities of bone that are in part independent of BMD, and thus may be useful alone or in combination with bone mass measurements in the prediction of vertebral fractures.
The relations between physical ability and bone mass in women aged over 65 years
Authors: Vico Laurence , Pouget Jean Francois , Calmels Paul , Chatard Jean Claude , Rehailia Mohamed , Minaire Pierre , Geyssant André , Alexandre Christian
Published: February 2010

In this cross-sectional study of 55 women (mean age 73.54 ± 5.87), the magnitude of the relation between different indices of physical ability and confounding factors to bone density were determined. Physical fitness was assessed by direct measurement of maximal oxygen consumption (V̇O2 max), isokinetic muscle strength, and quadriceps and psoas muscle surfaces and densities using computed tomography. Anthropometry, chronological and gynecological ages, and dietary calcium intake were also recorded. The bone mineral density (BMD) was evaluated at the axial level (lumbar spine and proximal femur) and at the peripheral level (radius and tibia, cancellous and cortical compartments). Parameters related to physical ability proved to be the best predictors of BMD in radial and tibial cancellous compartments, spine, femoral neck, and trochanter, accounting for 15–27.5% of the total variance. The V̇O2 max was a major determinant of the femoral mineral density and one of the predictors of radial and tibial cancellous compartments. Psoas parameters were strongly related to spine mineral density and also constituted a predictor of radius (cancellous) and tibia mineral densities. The arm muscle strength could predict, though weakly, the BMD of axial skeleton, whereas thigh muscle strength only predicted the BMD of inferior limbs. No correlation was observed between current dietary calcium intake and BMD. Age-postmenopause and fertile life remained predictive of BMD at mostly cancellous sites, whereas anthropometry exerted important effects on radial and tibial cortices. The study suggests distinct sets of relations between physical ability and the BMD variables. Subjects with greater and denser psoas muscles had greater spine BMD, and those with higher V̇O2 max had greater proximal femur BMD.
Bone density in young women is associated with body weight and muscle strength but not dietary intakes
Authors: Henderson N. Kathryn , Price Roger I. , Cole Joan H. , Gutteridge Donald H. , Bhagat Chotoo I.
Published: February 2010

Potential determinants of bone mineral density (BMD) were studied cross-sectionally in 115 healthy, sexually mature Caucasian women aged 18 years. Bone mineral density (Hologic QDR1000W) of the lumbar spine, proximal femur (five sites), and distal tibia and fibula; fasting blood and urine calcium biochemistry; serum sex hormone levels (follicular phase); nutrient intakes; aerobic fitness; trunk muscle strength; and habitual activity levels were measured. The effects of heredity were considered by measuring the BMD of 107 of the subjects' mothers. Simple and stepwise regression analysis were used to identify significant determinants of BMD at each of the regions studied. The analysis indicated that significant bivariate correlations exist between BMD at all sites and body weight (r = 0.23–0.47, p ≤ 0.01), lean body weight (r = 034–0.46), trunk strength (r = 0.27–0.47), physical activity score (r = 0.20–0.25), and aerobic fitness (r = 0.29–0.45). Dietary calcium intake correlated significantly with BMD at the trochanter site only (r = 0.19), and none of the biochemical or hormonal indices measured correlated consistently with BMD at any site. Significant correlations between the BMD of mothers and daughters ranged from r = 0.43 at lumbar spine to r = 0.34 at the intertrochanteric site. Paired t-tests showed the daughters had significantly (p < 0.03) lower BMD than their mothers at the lumbar spine (98 ± 12% [mean ± SD]) and significantly higher (p < 0.002) BMD at the femoral neck, trochanter, and total hip sites (110 ± 16%, 108 ± 17%, 103 ± 14%, respectively). When stepwise regression analysis included weight-corrected strength of the trunk flexor muscles (Corr Flex), weight-corrected aerobic fitness (Corr VO2max), physical activity score, and body weight, body weight was the only significant determinant of BMD at all sites. Corr Flex made significant contributions at all sites except the femoral neck, while Corr VO2max made additional contribution at the femoral neck, trochanter, total hip, and shaft of femur sites. These variables accounted for 13–27% of the variance in BMD. The addition of mother's BMD to these independent variables, in stepwise regression analysis, improved the prediction to 18–31% of the variance.
Expression of bone morphogenetic protein-6 messenger RNA in bovine growth plate chondrocytes of different size
Authors: Carey Dennis E. , Liu Xia
Published: February 2010

Bone morphogenetic protein-6 (BMP-6) is an osteoinductive factor that may have a regulatory role in the terminal differentiation of chondrocytes. We investigated the expression of BMP-6 messenger RNA in freshly isolated newborn calf rib chondrocytes separated by density gradient centrifugation into five highly enriched subpopulations at different stages of maturation as assessed by cell size and alkaline phosphatase activity. Expression of BMP-6 mRNA was compared with expression of type II collagen mRNA and type X collagen mRNA using Northern analysis. Type X collagen mRNA expression increased with increasing cell size whereas type II collagen mRNA varied little with cell size. BMP-6 mRNA expression was highest in small cells and lowest in the largest cells, which were maximally expressing type X collagen mRNA. This suggests that up-regulation of the BMP-6 gene may precede chondrocyte hypertrophy.
Upper extremity bone mass and osteoarthritis of the knees: Data from the baltimore longitudinal study of aging
Authors: Dr. Hochberg Marc C. , Lethbridge-Cejku Margaret , Scott William W. , Reichle Ralph , Plato Chris C. , Tobin Jordan D.
Published: February 2010

To examine the association of upper extremity bone mass with osteoarthritis (OA) of the knee, bilateral standing knee radiographs, taken between 1985 and 1991, in 430 Caucasian male and 266 Caucasian female subjects aged 40 years and above in the Baltimore Longitudinal Study of Aging, were read by one investigator for grade of OA using Kellgren-Lawrence scales. Several measures of upper extremity bone mass, size, and density, including combined cortical thickness (CCT), total width and percentage of cortical area of the second metacarpal, and bone mineral content (BMC), width, and density of the distal third of the left radius measured with single photon absorptiometry, were assessed at the same visit. In univariate analyses, men and women with definite knee OA were significantly older, men had significantly greater radial width, and women had significantly lower bone mass as measured by both CCT and BMC. After adjustment for age and body weight, however, men with knee OA had significantly higher BMC and radial width while neither of these measures of upper extremity bone mass and size was significantly associated with the presence of definite knee OA in women. Neither measure of upper extremity bone density was significantly associated with definite knee OA in either sex. These data suggest that, although men (but not women) with definite knee OA have significantly higher levels of adjusted radial bone mass and size, subjects with knee OA do not have significantly higher levels of adjusted bone mineral density at either upper extremity site.
Regulation of parathyroid hormone messenger RNA levels by protein kinase A and C in bovine parathyroid cells
Authors: Moallem Eli , Silver Justin , Naveh-Many Tally
Published: February 2010

Secretion of parathyroid hormone (PTH) is regulated by Ca2+ as well as by protein kinases A and C. In this study we report that protein kinases A and C regulate PTH messenger RNA levels in vitro in dispersed bovine parathyroid cells. Incubation of bovine parathyroid cells with cholera toxin (10−9 M), which activates adenylate cyclase and indirectly stimulates protein kinase A, increased PTH mRNA levels about 2-fold after 3 and 7 h incubation, but not at 24 h. Incubation with pertussis toxin (5 × 10−9 M), which blocks the high-calcium-mediated inhibition of cyclic adenosine monophosphate accumulation in these cells, also reversed the inhibition of PTH mRNA levels at high Ca2+ (2.0 mM) with a marked increase in PTH mRNA levels. Pertussis toxin also increased PTH mRNA at a low extracellular Ca2+ concentration (0.7 mM) (4-fold increase) and a normal concentration (1.25 mM) (2-fold increase). Inhibition of protein kinase C both by staurosporine (1 × 10−8 M) and by prolonged incubation with the phorbol ester phorbol 12-myristate 13-acetate (PMA) (1 × 10−7 M), decreased PTH mRNA levels at 24 h, reaching approximately 40% and 5% of control, respectively. Staurosporine and PMA had no effect on PTH mRNA levels at 3 h. The inactive phorbol ester, phorbol 12–13-diburyrate (PDBu), had no effect on PTH mRNA levels at 1 and 24 h. There were no changes in a control gene 18S RNA in these studies. PMA at 24 h, which may down-regulate protein kinase C activity, decreased PTH mRNA levels, suggesting that protein kinase C is necessary for normal PTH gene expression. These results suggest that both protein kinase A and C are involved in the regulation of PTH gene expression.
Human parathyroid hormone-(1–38) restores cancellous bone to the immobilized, osteopenic proximal tibial metaphysis in rats
Authors: Ma Y.F. , Jee W.S.S. , Ke H.Z. , Lin B.Y. , Liang X.G. , Li M. , Yamamoto N.
Published: February 2010

The purpose of this study was to determine if human parathyroid hormone-(1–38) (hPTH(1–38)) can restore cancellous bone mass to the established osteopenic, immobilized proximal tibial metaphyses of female rats. The right hindlimbs of 6-month-old female Sprague-Dawley rats were immobilized by bandaging the right hindlimbs to the abdomen. After 30 days of right hindlimb immobilization, the rats were subcutaneously injected with 200 μg hPTH(1–38)/kg/day for 15 days (short-term treatment) or 75 days (longer-term treatment). Static bone histomorphometry was performed on the primary spongiosa, and both static and dynamic histomorphometry were performed on the secondary spongiosa of the right proximal tibial metaphyses. Immobilization for 30 days without treatment decreased trabecular bone area, number, and thickness in both primary and secondary spongiosa, and induced an increase in eroded perimeter and a decrease in tissue referent-bone formation rate in the secondary spongiosa. These changes reached a new steady state thereafter. Treatment with 200 μg hPTH(1–38)/kg/day for 15 days, beginning 30 days after immobilization, significantly increased trabecular bone area, thickness, and number in both primary and secondary spongiosa despite continuous immobilization when compared with controls. The short-term PTH treatment (15 days) significantly increased labeling perimeter, mineral apposition rate, and tissue referent-bone formation rate in the secondary spongiosa and stimulated longitudinal bone growth as compared with the controls. Longer PTH treatment (75 days) further increased trabecular bone area, thickness, and number as compared with controls and groups given short-term PTH treatment (15 days). The bone formation indices in the secondary spongiosa of the longer-term treated rats were lower than those of the short-term treated group, but they were still higher than those of controls. Our findings indicate that PTH treatment stimulates cancellous bone formation, and restores and adds extra cancellous bone to the established, disuse-osteopenic proximal tibial metaphysis of female rats with continuously immobilized right hindlimbs. These results suggest that PTH may be useful in treating disuse-induced osteoporosis in humans.
Determinants of bone mass in 10- to 26-year-old females: A twin study
Authors: Young Doris , Hopper John L. , Nowson Caryl A. , Green Robyn M. , Sherwin Jane A. , Kaymakci Bahtiyar , Smid Monique , Guest Charles S. , Larkins Richard G. , Wark John D.
Published: February 2010

This cross-sectional twin study aimed to quantify the roles of constitutional and lifestyle factors on bone mass in adolescent and young adult women. Areal bone density (BMD) at the lumbar spine, femoral neck, Ward's triangle, and total hip, total body bone mineral content (BMC), and lean mass and fat mass were measured using dual energy X-ray absorptiometry (DXA) in 215 female volunteer twin pairs (122 monozygotic [MZ], 93 dizygotic [DZ]) aged 10 to 26 years. Height, weight, menarchial history, dietary calcium intake, physical activity, current tobacco use, and alcohol consumption were determined by questionnaire. Mean BMD increased with age to around 16 years, when it reached a plateau. Within-pair differences in BMD at the lumbar spine (expressed as a percentage of the pair mean BMD) were univariately associated with pair differences in menarchial status (14 ± 3%), height (0.7 ± 0.1% per cm), weight (0.4 ± 0.1% per kg), lean mass (1.0 ± 0.1% per kg), and fat mass (0.5 ± 0.1% per kg). Only menarchial status, height, and lean mass, however, were independent predictors. At the proximal femoral sites, within-pair BMD differences were associated with within-pair lean mass differences (1.0 to 1.1 ± 0.2%/kg), and no other factor was significant. The same conclusions applied to within-pair differences in BMD/height. Total body BMC was independently associated with menarchial status, height, lean mass, and fat mass; the effects of the latter two variables were stronger in pairs both premenarchial. After adjusting for constitutional factors, no lifestyle factor was independently predictive. By reducing collinearity, the cotwin method clearly identified that lean mass, not fat mass, was the major independent determinant of bone mass at the hip, both pre- and postmenarche.
Casein kinase localization in the endoplasmic reticulum of the ros 17/2.8 cell line
Authors: Sfeir Charles , Veis Arthur
Published: February 2010

Phosphophoryns (PPs) are phosphoproteins specific to the dentin matrix and are the major noncollagenous matrix proteins in rat incisor dentin. It has been hypothesized that their phosphate groups are important in dentin mineralization. PPs have many sequences which are substrates for membrane-associated endogenous messenger-independent kinases.(12) The objective of this study was to localize the protein kinases involved in phosphorylating the PPs. Osteoblast-like ROS 17/2.8 cells, which secrete extracellular matrix phosphoproteins, were lysed. After removal of the nuclei and mitochondria by low-speed centrifugation, the membrane associated organelles were isolated at higher speed from the cytosol. The Golgi vesicle and rough microsome fractions were collected from 29–43.7% sucrose density gradients. Each fraction was tested for casein kinase II (CKII) activity using an in vitro phosphorylation assay with PPs as substrate. To characterize and confirm the nature of the components of the sucrose gradient fractions, the activities of specific enzymes such as N-acetylglucosamine galactosyltransferase and cytochrome c reductase, which are exclusively associated with the Golgi and rough microsomes, respectively, were determined. Electron microscopy of the isolated fractions confirmed the enzyme assay characterizations. CKII activity capable of phosphorylating the PP was found in the rough microsome fraction but not in the Golgi. Thus, phosphorylation of the secreted phosphoproteins would appear to take place in the endoplasmic reticulum as a cotranslational event.
Frequency and characteristics of familial aggregation of paget's disease of bone
Authors: Morales-Piga A.A. , Rey-Rey J.S. , Corres-González J. , Garc ÍA-Sagredo J.M. , LÓPez-Abente G.
Published: February 2010

The cause of Paget's disease of bone (PDB) is unknown. In an attempt to ascertain the proportion of familial cases and evaluate the influence of genetic factors on the occurrence of the disease, a study was undertaken based on 35 PDB patients from our Unit. Their families were investigated, with the participation of a total of 128 first-degree relatives. Fourteen (40%) of these 35 index cases had at least one other first-degree relative affected with PDB and were defined as “familial.” The remaining 21 (60%) were considered “sporadic.” The frequency of males in the familial cases (79%) was significantly higher than among the sporadics (29%; p ≤ 0.01). Mean age at diagnosis (63.1  12.6 vs. 713 ± 8.7; p ≤ 0.02), proportion of polyostotic cases (85.7% vs. 52.4%, p ≤ 0.05), and mean number of involved bones per patient (436 ± 2.50 vs. 233 ± 1.93, p ≤ 0.01) differ significantly in the familial and sporadic groups. The disease appears to be transmitted via both paternal and maternal sides, and pedigree analysis suggested an autosomal dominant inheritance or multifactorial mechanism. Apart from green-and-blue eye color, which was clearly associated with familial grouping (OR 6.25, 95% CI 1.15–37.16, p ≤ 0.01), crude analysis on several genetically based traits and environmental variables revealed no other significant differences between the groups. The adjusted odds ratio estimated for green-and-blue eye color was 2.92 (95% CI 038–22.74). Although additional studies will be required to determine whether the high proportion of familial cases and the differences between these and the sporadic cases also exist in different geographic areas, our data support the existence of two distinct subtypes of PDB.
Inhibition of bone resorption and stimulation of formation by mechanical loading of the modeling rat ulna in vivo
Authors: Hillam Richard A. , Dr. Skerry Timothy M.
Published: February 2010

During normal growth of the rat ulna, bone is resorbed from the medial periosteal surface. This occurs as part of the modeling process by which the bone achieves its adult shape. By attaching strain gauges to the ulnae of rats in vivo, we measured the strains imposed on that surface of the bone during normal locomotion. We then applied mechanical loads to the ulnae of other rats in vivo for 6 consecutive days, inducing strains approximately double those we had measured. Fluorochromes were given on the 1st and 5th days. The histology of the medial ulnar periosteal surface was correlated with the amount of fluorochrome incorporation and tartrate resistant acid phosphatase (TRAP) activity in serial sections. In the nonloaded ulnae, the surfaces were lined with bone resorbing cells. Corresponding areas of the loaded bones were lined with osteoid and osteoblasts. There was insignificant label incorporation in the nonloaded bones but almost continuous label incorporation in the corresponding regions of the loaded bones, which was significantly different from the nonloaded bones. TRAP activity of the periosteal cells in the loaded bones was significantly less than in the nonloaded limbs. It is widely acknowledged that loading induces bone formation, and this implies that it also has the ability to inhibit resorption. However, to date there has been little direct evidence for the inhibition of resorption in vivo by mechanical loading. The changes we have observed are similar to the sequence of cellular events that occur during the reversal phase of bone remodeling, in which osteoclastic resorption ceases and osteoblasts are recruited and begin formation. This model may help increase understanding of that process.
Osteogenic growth peptide regulates proliferation and osteogenic maturation of human and rabbit bone marrow stromal cells
Authors: Robinson D. , Bab I. , Prof. Nevo Z.
Published: February 2010

The recently discovered osteogenic growth peptide (OGP) has been shown to regulate proliferation in fibroblastic and osteoblastic cell lines derived from rats and mice and also alkaline phosphatase activity in the latter was found to be affected. In vivo the OGP enhances bone formation and trabecular bone density. The results of the current study indicate that the OGP is also a potent regulator of marrow stromal cells from man and rabbit, as well as rabbit muscle fibroblasts. The main OGP activity in both marrow systems is a marked stimulation of alkaline phosphatase activity and matrix mineralization. In the rabbit-derived cell culture this enhancement is accompanied by a reciprocal inhibition of proliferation. On the other hand, the human cells show a concomitant increase of both parameters. The proliferative effect of the OGP is similar to that of growth hormone (GH) and basic fibroblast growth factor (bFGF). The combined activity of the OGP with GH is smaller than that of each of the polypeptides alone. The OGP and bFGF potentiate each other. Of the three polypeptides tested, OGP is the most potent enhancer of alkaline phosphatase activity and mineralization. bFGF has no influence on these characteristics of osteogenic maturation. The OGP maturational activity is unaffected by either GH or bFGF. These data suggest that the marrow stromal cells serve as targets for the OGP that mediate the OGP-induced increase in osteogenesis. The effect on the human cells implies a role for the OGP in clinical situations where the osteogenic potential of bone marrow is involved.