bluuebunny/crossref_metadata_2025 huggingface dataset:
Do variations in hip geometry explain differences in hip fracture risk between japanese and white americans?
Authors: Nakamura T. , Turner C.H. , Yoshikawa T. , Slemenda C.W. , Peacock M. , Burr D.B. , Mizuno Y. , Orimo H. , Ouchi Y. , Johnston C.C.
Published: February 2010

Despite lower femoral neck bone mass, Japanese women have a substantially lower incidence of hip fracture than North American whites. Reasons for this discrepancy were sought in a study of 57 Japanese and 119 white American women aged 50–79. All women were in good health. Bone mineral content (BMC) in the femoral neck, femoral neck length (NL), femoral neck angle (Ø), cross-sectional moment of inertia (CSMI), safety factor (SF), and fall index (FI) were calculated using dual x-ray absorptiometry. Height and weight were greater in Americans than in Japanese (1.62 versus 1.52 m; p < 0.0001 and 66.0 versus 49.4 kg; p < 0.0001, respectively). Mean BMC in the femoral neck and CSMI were greater in Americans than in Japanese (3.91 versus 3.02 g; p < 0.0001 and 0.99 versus 0.57 cm4; p < 0.0001, respectively). NL was longer in Americans (5.6 versus 4.4 cm; p < 0.0001) and θ was larger in Americans (130 versus 128° p < 0.01), whereas SF and FI were less in Americans than in Japanese (3.41 versus 5.12; p < 0.0001 and 1.00 versus 1.40; p < 0.0001, respectively). These results indicate that despite lower bone mass, Japanese women have lower risks of structural failure in the femoral neck, attributable primarily to shorter femoral necks and, to a lesser degree, a smaller femoral neck angle. Geometric characteristics of the femoral neck in Japanese women are associated with their lower hip fracture risk, and the measurement of proximal femoral geometry, combined with bone mass, may provide further clinical information about the risk of hip fracture.
Bone formation by marrow osteogenic cells (MBA-15) is not accompanied by osteoclastogenesis and generation of hematopoietic supportive microenvironment
Authors: DR. Benayahu D. , Gurevitch O. , Zipori D. , Wientroub S.
Published: February 2010

This study was aimed at elucidating the relationship between osteogenic activity of marrow stromal cells and their ability to support hematopoiesis followed by the bone-remodeling process. We used the MBA-15 cell line, which expresses osteoblastic phenotype in vitro and forms bone in diffusion chamber. We have compared bone formation and hematopoietic responses elicited in vivo by these cells with the implantation of freshly isolated bone marrow cells (BMC) or demineralized tooth matrix (DTM). Both MBA-15 cells and BMC, implanted under the kidney capsule, yielded intramembraneous bone, but DTM, implanted subcutaneously, elicited endochondral bone. MBA-15 formed primary bone, mimicking only the initial sequential stages of the ossification process. Neither histologic signs of bone resorption and remodeling nor tartrate-resistant acid phosphatase (TRAP)-positive cells and marrow formation were observed. Bone formation was monitored biochemically. Functions for hematopoietic stem and committed cell content were measured by GM-CFU and BFU-E assays that confirmed the morphologic observations. In both BMC and DTM implantation, bone formation was followed by hematopoietic activity, osteoclastogenesis, and remodeling. We conclude that MBA-15 osteoprogenitor cells, despite their extensive bone formation ability, are unable to form a microenvironment supportive for hematopoiesis and osteoclastogenesis or to initiate bone remodeling.
Expression of monocyte chemoattractant protein 1 in human osteoblastic cells stimulated by proinflammatory mediators
Authors: Zhu Jian-Fu , Valente Anthony J. , Lorenzo Joseph A. , Carnes David , Dr. Graves Dana T.
Published: February 2010

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine superfamily of genes that induces chemotaxis of monocytes in inflammatory processes. The effects of interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), transforming growth factor β (TGF-β), platelet-derived growth factor (PDGF-BB), parathyroid hormone (PTH), and 1,25(OH)2D3 on MCP-1 expression in human osteoblastic cells were compared. Inflammatory or proinflammatory cytokines stimulated the production of MCP-1 in normal human osteoblastic cells as determined by RIA. The osteotrophic mediators PTH and 1,25(OH)2D3 and PDGF-BB had no effect on MCP-1 expression. In further studies, the steady-state mRNA and MCP-1 protein levels in two human osteoblastic cell lines, MG-63 and SaOS-2, were examined. MCP-1 expression at both the protein and mRNA levels was greatly increased by IL-1β and TNF-α. At the mRNA level, IL-1β and TNF-α strongly induced MCP-1 expression; TGF-β and IL-6 induced MCP-1 but to a lesser extent. No significant changes in MCP-1 mRNA or MCP-1 protein secretion were observed when cells were treated with PDGF-BB, PTH, and 1,25(OH)2D3. When tested on preosteoclasts, MCP-1 was shown to have no effect on the formation of multinucleated, tartrate-resistant acid phosphatase (TRAP)-positive osteoclastic cells.
Upregulation of c-Fos protooncogene expression in pagetic osteoclasts
Authors: Hoyland Judith , Sharpe Paul T.
Published: February 2010

Using in situ hybridization we show that expression of the c-fos oncogene, a gene normally associated with osteosarcomas, is greatly elevated in osteoclasts of patients with Paget's disease. Immunohistochemical staining with c-fos antibodies also shows increased protein in pagetic osteoclasts. In light of transgenic mouse experiments showing a key role for c-fos in bone resorption, we propose that elevated c-fos gene expression in pagetic osteoclasts is an important component in producing the pagetic phenotype. Levels of c-fos gene and protein expression in pagetic osteoblasts are lower than those detected in osteoclasts but still higher than in nonpagetic osteoblasts. This may provide an explanation for the increased incidence of osteosarcomas in patients with Paget's disease because overexpression of c-fos in osteoblasts of transgenic mice induces osteosarcoma formation.
Bound phosphoproteins enhance mineralization of alkaline phosphatase-collagen complexes in vivo
Authors: DR. van den Bos Theo , Beertsen Wouter
Published: February 2010

Phosphoproteins (PP) covalently bound to a collagenous matrix have been reported to promote its mineralization in vitro. It was the aim of the present study to determine whether PP also enhance the mineralization of collagen in vivo. To this end, collagen slices were prepared from demineralized bovine cortical bone. Following immobilization of rat dentin phosphoprotein (PP) to the slices, bovine intestinal alkaline phosphatase (ALP) was bound according to the SATA-MHS coupling method. Controls were without enzyme. The slices were implanted into skin pockets prepared over the skull of female Wistar rats (6–10 weeks old). After 3–31 days the implants were removed and analyzed for calcium and phosphate content. It was shown that slices of PP-treated bone collagen mineralized more rapidly and to a greater extent than bone collagen slices without PP. Controls remained free of mineral. It is concluded that mineralization of collagenous matrices, induced by alkaline phosphatase, is enhanced by bound phosphoproteins following implantation in subcutaneous connective tissue.
Evaluation of urinary pyridinium crosslink excretion as a marker of bone resorption in the rat
Authors: Egger Chantal D. , Mühlbauer Roman C. , Felix Rolf , Delmas Pierre D. , Marks Sandy C. , Fleisch Herbert
Published: February 2010

The aim of this study was to evaluate the value of the urinary excretion of the pyridinium crosslinks, pyridinoline (Pyr) and deoxypyridinoline (D-Pyr), as markers of bone resorption in the rat. The excretion of the crosslinks was compared with that of urinary [3H]tetracycline ([3H]TC) excretion from chronically [3H]TC-prelabeled animals, a technique established to monitor bone resorption in the rat. Bone resorption was modulated by Ca restriction, infusion of PTH, thyroparathyroidectomy, and administration of different bisphosphonates. Furthermore, the urinary crosslinks were assessed in three different osteopetrotic mutations in the rat. We found a delayed response of Pyr and D-Pyr excretion to acute changes in bone resorption compared with [3H]TC excretion. This delay was 1 day after Ca restriction and longer after other treatments, such as PTH administration or bisphosphonate treatment, with which it was more than 3 weeks. In contrast, chronic states with stimulation or inhibition of bone resorption showed similar changes in excretion of the urinary crosslinks and [3H]TC, except after PTH administration. The excretion of the crosslinks was greatly reduced in osteopetrotic rats (op/op, tl/tl, and ia/ia) and increased to normal levels in tl/tl rats after stimulation of bone resorption by M-CSF administration. These results suggest that, in rats, urinary excretion of the pyridinium crosslinks reflects bone resorption in chronic but not always in acute conditions. The cause of this discrepancy is still unclear.
Retinoic acid induces a shift in the energetic state of hypertrophic chondrocytes
Authors: Dr. Shapiro Irving M. , Debolt Kristine , Hatori Masashi , Iwamoto Masahiro , Pacifici Maurizio
Published: February 2010

In the epiphyseal growth plate, chondrocyte maturation is accompanied by dramatic alterations in energy metabolism. To explore the relationship between these two events, we used retinoic acid (RA) to promote chondrocyte maturation in culture. The specific question that was addressed was, does RA treatment of cultured chondrocytes in vitro induce a change in energy status similar to that seen in hypertrophic chondrocytes in vivo. Maturing chondrocytes isolated from the cephalic region of day 18 chick embryo sterna were allowed to grow for 7–14 days in monolayer until confluent and then treated with 10–300 nM RA. Immature chondrocytes from the caudal region of sternum were grown in parallel and served as control cells for the study. We found that in maturing cephalic cell cultures, RA had a rapid and profound effect on oxidative metabolism. The retinoid caused a reduction in the energy charge ratio (ECR) and the ATP/ADP ratio and a sharp decrease in cell ATP levels. Maximum inhibition was observed when the RA concentration was 10–35 nM. Compared with the adenine nucleotides, creatine phosphate levels were decreased to a lesser extent by RA, although there was substantial inhibition of creatine kinase activity. We expected to find a compensatory elevation in glycolytic activities; however, the lactate levels in the medium of the treated cells indicated that anaerobic glycolysis was depressed. In contrast to the cephalic chondrocytes, when caudal cell cultures were treated with RA, lactate formation was stimulated and there were minimal effects on oxidative metabolism. To determine the mechanism of inhibition of glycolysis, we measured the activity of pyruvate kinase in RA-treated cephalic cells. We found that the activity of this key glycolytic enzyme was profoundly and rapidly inhibited by the retinoid. The unique energy state of the RA-treated chondrocytes was termed the minimal energy state. This condition may be expected to influence activities associated with plasma membrane ion pumps and gene transcription. Both these factors would promote chondrocyte hypertrophy and lead to terminal differentiation.
Overexpression of estrogen receptor in HTB 96 human osteosarcoma cells results in estrogen-induced growth inhibition and receptor cross talk
Authors: Dr. Watts C. K. W. , King R.J.B.
Published: February 2010

Estrogenic effects on the proliferation and differentiated cellular functions of bone cells have been described in vivo and in vitro. In particular, stimulatory effects on the growth rate of osteoblasts have been observed, although these are generally small. In an attempt to produce a more sensitive model for the study of estrogen action in bone, HTB 96 human osteoblast-like osteosarcoma cells, which lack endogenous estrogen receptor (ER), were stably transfected with an expression vector coding for the human ER gene. Several HTB 96 sublines expressing ER protein, detected by ligand binding and immunoassay, were isolated. The ability of 17β-estradiol (E2) to induce chloramphenicol acetyltransferase (CAT) activity from a cotransfected reporter vector containing the CAT gene linked to the Xenopus vitellogenin A2 gene estrogen response element demonstrated that the expressed ER was functional. ER continued to be expressed over a 30 week culture period. E2 but not other steroids significantly reduced growth rates and produced an altered morphology in HTB 96 sublines expressing higher levels of ER. The antiestrogen 4-hydroxytamoxifen partially reversed the E2 effect on growth rate. Transient transfection of cells expressing ER with a vector containing the CAT gene linked to the mouse mammary tumor virus long terminal repeat sequence, which contains response elements for the glucocorticoid receptor but not the ER, showed that E2 was able to inhibit CAT induction by dexamethasone. This result suggests that in ER-transfected HTB 9 cells the effects of E2 may result not from direct activation of endogenous genes but instead by transcriptional interference. Thus the mechanisms responsible for the effects of over-expression of ER in ER-negative HTB 96 osteoblast-like bone cells in vitro may differ from those that mediate the effects of estrogens on bone observed in vivo.
Modulation of ecto-nucleoside triphosphate pyrophosphatase activity of human osteoblast-like bone cells by 1α,25-dihydroxyvitamin D3, 24R, 25-dihydroxyvitamin D3, parathyroid hormone, and dexamethasone
Authors: Oyajobi Babatunde O. , Russell R. Graham G. , Caswell Alison M.
Published: February 2010

Extracellular inorganic pyrophosphate (PPi) is involved in the regulation of mineralization, and there is evidence that the cell surface enzyme, NTP pyrophosphatase, is a major source of this metabolite in bone. Osteotrophic agents that influence bone turnover may exert their effects, in part, by modulating the activity of ecto-NTP pyrophosphatase in bone cells. We investigated the effect of 1,25(OH)2D3,24,25(OH)2D3, dexamethasone, and parathyroid hormone (PTH) on the activity of this enzyme in cultured human trabecular bone-derived osteoblast-like cells. 1,25(OH)2D3 at 10−11-10−9 M induced a dose- and time-dependent increase in activity (at 96 h; maximum 10−9 M, p > 0.001), whereas higher concentrations (10−8 and 10−7 M) had no effect. In contrast, 24,25(OH)2D3 was effective only at 10−8 and 10−6 M (at 96 h; p > 0.01). Dexamethasone (10−9-10−7 M) caused a dose-dependent decrease in ecto-NTP pyrophosphatase activity (10−7 M, p > 0.001); concentrations higher than 10−7 M did not evoke greater inhibition. This effect became apparent by 48 h and was significantly enhanced after 72 h. The response to dexamethasone was attenuated by cycloheximide, indicating a requirement for de novo protein synthesis. Interestingly, the stimulatory effect of 10−9 M 1,25(OH)2D3 on ecto-NTP pyrophosphatase activity was significantly enhanced in the presence of dexamethasone (10−9-10−7 M). Human PTH(1-34) and bovine PTH(1-34) in the range 10−10-10−7 M had no effect on enzyme activity over a 72 h period. The effects of vitamin D3 on the expression of bone ecto-NTP pyrophosphatase may be tissue or cell type specific because the ecto-NTP pyrophosphatase activity of subject-matched skin-derived fibroblasts showed no sensitivity to 1,25(OH)2D3. These data suggest a possible role for both vitamin D3 metabolites and glucocorticoids in the regulation of the mineralization process in vivo via modulation of PPi production.
Immunohistochemical localization of heparan sulfate proteoglycan in rat tibiae
Authors: Nakamura Hiroaki , Ozawa Hidehiro
Published: February 2010

Ultrastructural and immunohistochemical studies were performed to clarify the localization of heparan sulfate proteoglycans (HSPG) and their role in cell-cell and/or cell-matrix interaction of bone cells. Ultrastructural observations using the freeze-substitution method revealed electron-dense undercoat structures on the cytoplasmic side of plasma membranes and extracellular matrices in the intercellular spaces where stromal cells came in contact with hematopoietic cells and/or osteoclasts. Immunohistochemical localization of HSPG in rat tibiae was examined using monoclonal antibody directed to glycosaminoglycan of HSPG by confocal laser scanning microscopy and transmission electron microscopy. Intense immunoreactivity was detected on the basement membranes of blood vessels, as well as the plasma membranes of fibroblast-like cells surrounding them. Immunoreactivity was also seen on extracellular matrices between fibroblast-like cells and osteoclast lineage cells. In addition, osteoblasts showed moderate immunoreactivity on those plasma membranes attached to bone matrix. A postembedding method revealed gold particles in Golgi vacuoles of osteoblasts, indicating the localization of HSPG. In osteoclasts, HSPG was localized in Golgi apparatus and lysosomal structures. These findings suggest that (1) osteoblasts and osteoclast lineage cells synthesize HSPG; (2) both membrane and matrix HSPG are localized in bone tissue; and (3) HSPG may play an important role in cell-cell interaction between fibroblast-like cells and osteoclast lineage cells by reserving heparin binding growth factors and/or heparin binding adhesion molecules, such as fibronectin.
Circulating levels of cytokines that modulate bone resorption: Effects of age and menopause in women
Authors: Mckane W. Roland , Khosla Sundeep , Peterson James M. , Egan Kathleen , Riggs B. Lawrence
Published: February 2010

Interleukin 1αa (IL-1α), interleukin 1β (IL-1β), and interleukin 6 (IL-6) are cytokines with potent bone-resorbing effects; some of these biologic effects are opposed by interleukin-1 receptor antagonist (IL-1ra). In vitro and animal model studies suggest that these cytokines are paracrine mediators of the increased bone resorption associated with estrogen deficiency, and increases in their production also could contribute to age-related bone loss. Therefore, we measured serum concentrations of these cytokines in 80 normal women who were 24-87 years old. IL-6 concentration correlated highly with age (p > 0.001) and increased three-fold during life. However, multiple-regression analysis showed no significant correlation between serum IL-6 levels and menopausal status, serum estradiol concentration, or markers for bone turnover (serum bone alkaline phosphatase, osteocalcin, carboxyl-terminal telopeptide of type I collagen, or 24 h urinary free pyridinoline excretion). Serum IL-1α, IL-1β, or IL-1ra level did not change with age and, by multiple-regression analysis, did not correlate with markers of bone turnover, except IL-1ra weakly with ICTP. We found no relationship between bone-resorbing cytokines and ovarian function. Although the large age-related increase in serum IL-6 concentration could contribute to age-related bone loss, the lack of correlation with markers for bone turnover argues against this. However, based on the strong evidence in experimental animals that these cytokines are involved in estrogen action on bone, further studies in humans are warranted.
Sex differences in bone mineral density in 1653 men and women in the sixth through tenth decades of life: The rancho bernardo study
Authors: Blunt Barbara A. , Klauber Melville R. , Barrett-Connor Elizabeth L. , Edelstein Sharon L.
Published: February 2010

This cross-sectional population-based study examined the effect of age and sex on bone mineral density (BMD) in the elderly. BMD was measured at the spine and hip using dual-energy x-ray absorptiometry and at midshaft and ultradistal radius using single-photon absorptiometry in 672 men and 981 women aged 50–98 years. In both sexes, mean BMD levels decreased significantly with age at all sites except the male spine. In linear regression models, the slope of loss was significantly greater in women than in men at all sites except the ultradistal radius. The slope was steeper at most sites in women aged 50-59 years than in older women, 60-98 years. In both age groups, mean age-adjusted BMD levels were lower at all sites in women who were past or never users of replacement estrogen than in women who were current estrogen users. Current estrogen users generally had lower slopes of loss with age than never or past estrogen users; however, few of these differences were statistically significant. We conclude that BMD levels decrease in old age in both sexes. Continued bone loss in old age raises the possibility that intervention to retard further loss may still be warranted in the elderly.
Lifestyle factors and bone density in the elderly: Implications for osteoporosis prevention
Authors: Nguyen T.V. , Kelly P.J. , Sambrook P.N. , Gilbert C. , Pocock N.A. , Eisman J.A.
Published: February 2010

Epidemiologic evidence suggests that lifestyle factors, such as exercise, calcium intake, and tobacco consumption, have effects on bone density. However, the influence of these factors in the elderly has not been well documented. To examine the effects of lifestyle factors in the elderly, we measured bone density (BMD) at the lumbar spine and proximal femur in 709 elderly men and 1080 women participating in the Dubbo Osteoporosis Epidemiology study (DOES), a community-based, longitudinal, epidemiologic study of osteoporosis in men and women over the age of 60. BMD was significantly higher in men than in women (20% at all sites). There was an age-related decline in BMD at the femoral neck in both sexes and at the lumbar spine in women. Between the ages of 60 and 80, the decrease in BMD at the femoral neck among women was 18.9%, which is almost twice the decrease in BMD among men (10.1%). Tobacco consumption was associated with a reduction in BMD at both sites in both sexes (5-8%), and this effect was independent of calcium intake or body weight. Exsmokers had BMD intermediate between that of current smokers and never smokers, suggesting the influence of tobacco was partially reversible. Quadriceps strength predicted bone density at the proximal femur in elderly men but not in women. Analyzing BMD (adjusted for age and weight) in tertiles of muscle strength and calcium intake revealed an interaction between calcium intake and muscle strength on bone density; BMD at the femoral neck among those with higher quadriceps strength and calcium intake was approximately 5% higher (P < 0.05) than in those with low quadriceps strength and calcium intake in both men and women. These data indicate that lifestyle factors, such as tobacco consumption, calcium intake, and physical activity, may influence bone density in the elderly. Modification of these lifestyle factors may influence osteoporotic fracture risk in elderly men and women.
Serum parathormone profile during surgical treatment of hyperfunctioning parathyroid adenoma: A multicompartmental model
Authors: Duquenne Marc , Weryha Georges , Kaminsky Pierre , De Talance Nicole , Mathieu Pierre , Leclere Jacques
Published: February 2010

Patterns of intact parathyroid hormone (iPTH) elimination and subsequent recovery of parathyroid function were studied in seven patients undergoing surgical removal of solitary hyperfunctioning parathyroid adenoma. Using a sensitive two-site immunoradiometric assay, iPTH levels were measured pre, peri-, and postoperatively. Blood samples were taken at very early and at late stages, including 3, 6, 9, and 15 minutes and 48, 72, and 96 h after adenomectomy. A biexponential formula was calculated to fit the decreasing values of iPTH in all patients. The PTH half-life in the early phase was 1.4 + 1.1 minutes (95% confidence limits). The PTH half-life in the second phase was 64.45 + 32.19 minutes (95% confidence limits). A third phase is represented by a slow, linear increase in plasma iPTH values as a result of the recovery of healthy suppressed parathyroid glands. The extrapolation to baseline of the later phase shows that the recovery of normal parathyroid function begins as soon as 240 minutes after adenomectomy and is independent of the decrease in PTH of adenomatous origin. All individual results were consistent with this model. Five patients had iPTH values below 5 pg/ml, one had 15 pg/ml, and the last had 27 pg/ml 5 h after parathyroid adenomectomy. The recovery of the hormonal activity of the remaining glands occurred rapidly. By the postoperative hour 24 the mean serum iPTH concentration was 12.28 + 8.07 pg/ml. The intraoperative serum iPTH concentration offers a model to assess both recovery of hormonal secretion from functionally suppressed parathyroid glands and disappearance of parathyroid hormone.
Force attenuation properties of various trochanteric padding materials under typical falling conditions of the elderly
Authors: Parkkari Jari , Kannus Pekka , Poutala Jarmo , Vuori Ilkka
Published: February 2010

The purpose of this study was to determine and compare the force attenuation properties of various external trochanteric padding materials under in vitro conditions simulating characteristic falling of the elderly. The selected materials had to be practically suitable for external hip padding so that the main criteria for the materials were good energy absorbing capacity, good durability, low weight, good recovery after compression, easy availability, and reasonable price. Eight materials met these requirements. The first six were flexible cross-linked polyethylene foams with densities from 30 to 200 kg/m3. The seventh material was Plastazote polyethylene foam, and the eighth foam was made of ethylene-vinyl acetate (EVA) copolymer. With a pendulum effective mass of 39 kg, impact velocity of 3.0 m/s, and impact force of 8.2 kN, the force attenuation provided by the 20 mm thick hip-padding materials was quite small, ranging from 22 to 38%. With all these materials the peak femoral force remained above 5 kN, more than two times above the femoral fracture threshold (2 kN). In the second set of experiments, the impact force was gradually reduced until the tested materials lowered the impact force below the fracture threshold. With the most efficient material this critical falling velocity was found to be 1.6 m/s. To go below the fracture threshold with the realistic impact velocity of 3.0 m/s, the padding materials had to be 100-140 mm thick. In conclusion, our test results strongly suggest that using reasonable thicknesses of the currently available hip padding materials, the impact forces clearly remain above the fracture threshold, and therefore, prevention of hip fractures by external protectors should be based on other ideas (increase in the impact surface and/or shunting of impact energy away from the greater trochanter) than hip padding alone.
Displacement and translocation of osteoblast-like cells by osteoclasts
Authors: Ferrier Jack , Xia Shen-Ling , Lagan Eva , Aubin Jane E. , Heersche Johan N. M.
Published: February 2010

Rabbit osteoclasts and rabbit osteoblast-like stroma cells (OB cells) were plated onto plastic surfaces and the migration patterns of individual osteoclasts and osteoclast-OB interactions were analyzed with time-lapse recording. To induce directed migration, the cultures were exposed to an electrical field of 0.01 or 0.1 V/mm. At 0.1 V/mm, osteoclasts moved directly toward the anode in some cases, clearing OB cells from their path of migration. In other cases, osteoclasts migrated toward the anode for part of the time but then changed direction and moved toward groups of OB cells. Observations were made on osteoclasts interacting with single OB cells or small colonies and on osteoclasts interacting with OB monolayers, at both field strengths; the results were independent of field strength. There were several characteristic behaviors. With single OB cells and small OB colonies, retraction of OB cells upon contact with the osteoclast was the predominant mechanism whereby these cells begin to move out of the path of the osteoclast. A pronounced ruffling or blebbing of the OB cell membrane often followed retraction. When osteoclasts displaced OB cells that were part of a monolayer, extension of an osteoclast lamellipodium underneath the edge of the OB cell layer generally preceded partial retraction of the OB cells involved. It sometimes appeared as if the detached or partially detached OB cells were “pushed” by the osteoclast, which in some cases resulted in OB cells being moved hundreds of μm in a period of a few hours, at rates comparable to the normal speed for osteoclast migration (⋍100 μm/h), much faster than the normal speed for OB cells (⋍10 μm/h). These results imply that osteoclasts have mechanisms to move OB cells out of their path of migration. Further, when these cells were plated onto devitalized bone slices, resorbing osteoclasts apparently were able to clear a path through the OB cells. Laser scanning fluorescent measurements showed that there was no general intracellular [Ca2+] increase in OB cells following contact with osteoclasts, suggesting that an intracellular [Ca2+] signaling cascade does not play a role in the OB displacement. These data support the hypothesis that osteoclasts obtain access to the bone surface by actively displacing osteoblasts or lining cells at sites earmarked for resorption.
Dual X-ray absorptiometry forearm software: Accuracy and intermachine relationship
Authors: Hagiwara Satoshi , Engelke Klaus , Yang Seoung-Oh , Dhillon Manjit S. , Guglielmi Giuseppe , Nelson David L. , Genant Harry K.
Published: February 2010

An ash study was performed to analyze the accuracy of forearm measurements at the one-third site of three dual x-ray absorptiometry (DXA) systems using 20 cadavers. A Hologic QDR-2000, a Hologic QDR-1000/W, and a Lunar DPX-L system were used. The correlations between ash weight and DXA BMC were excellent for the three instruments (r > 0.97, p < 0.001), with accuracy errors < 5.2%. To perform a forearm cross-calibration of bone mineral content (BMC) and density (BMD) between the scanners, 10 healthy volunteers were additionally scanned at the distal one-third radius. The correlations among the DXA machines were excellent (r > 0.95); the absolute BMC and BMD values were significantly different between the two Hologics and the Lunar machine. The slope and intercept of both the BMC and BMD between the two Hologic systems were close to unity. In conclusion, the DXA forearm software packages provide accurate methods for assessing bone mineral content and density. The conversion of data among different manufacturers should be performed by careful cross-calibration measurements.
Calcitonin inhibits testosterone and luteinizing hormone secretion through a mechanism involving an increase in camp production in rats
Authors: Dr. Wang Paulus S. , Tsai Shiow-Chwen , Hwang Guey-Shyang , Wang Shyi-Wu , Lu Chien-Chen , Chen Jiann-Jong , Liu Shy-Rong , Lee Kun-Yih , Chien Eileen Jea , Chien Chau-Heng , Lee Hsien-Yang , Lau Chin-Pang , Tsai Ching-Lin
Published: February 2010

Effects of calcitonin peptides, including human calcitonin (hCT), salmon calcitonin (sCT), and calcitonin gene-related peptide (CGRP), on the secretion of testosterone and luteinizing hormone (LH) in male rats were studied. Male rats were injected intravenously with human chorionic gonadotropin (hCG), calcitonin peptides, or hCG plus calcitonin peptides. Blood samples were collected at several intervals following hormone challenge. In an in vitro experiment, testis blocks were incubated with hCG (0, 0.05, 0.5, or 5 IU/ml) or hCG (0.5 IU/ml) plus calcitonin peptides (0–10−9 or 10−6 M) at 34°C for 30 minutes. Both medium and plasma samples were extracted by ether and analyzed for testosterone by radioimmunoassay (RIA). The concentration of calcium in each plasma sample was measured by an automatic calcium analyzer. The anterior pituitary gland (AP) was incubated with or without calcitonin peptides (0–10 nM) at 37°C for 30 minutes. They were then incubated with gonadotropin releasing hormone (GnRH, 10 nM) for a further 30 minutes. The concentration of LH in AP medium was measured by RIA. The accumulation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in both testicular tissues and APs were measured by RIA. A single intravenous injection of calcitonin peptides decreased the basal and hCG-stimulated levels of plasma testosterone gradually from 60 to 180 or 360 minutes after challenge. The plasma calcium was not altered by the injection of calcitonin peptides and/or hCG. Administration of calcitonin peptides in vitro resulted in a dose-dependent inhibition of both basal and hCG-stimulated release of testosterone. Meanwhile, calcitonin peptides caused a dose-dependent inhibition of the basal release of LH in vitro from rat APs. The content of cAMP in both testes and APs was increased by all calcitonin peptides. Neither hCT nor sCT altered the content of cGMP in testes and APs. These results suggest that calcitonin peptides, including hCT, sCT, and CGRP, inhibit the spontaneous and gonadotropin-stimulated secretion of testosterone by acting directly at testes and reducing the release of pituitary LH through a mechanism involving an increase in cAMP production.
Serum undercarboxylated osteocalcin correlates with hip bone mineral density in elderly women
Authors: Szulc Pawel , Arlot Monique , Chapuy Marie-Claire , Duboeuf Francois , Meunier Pierre J. , Dr. Delmas Pierre D.
Published: February 2010

We previously showed that circulating undercarboxylated osteocalcin (ucOC) is elevated in elderly women and is a powerful marker of the subsequent risk of hip fracture in elderly institutionalized women (J Clin Invest 1993; 91:1769). To investigate the relationship between bone mass and ucOC, we measured bone mineral density (BMD) of the hip with dual-energy x-ray absorptiometry in 98 elderly institutionalized women, 81.4 + 6.0 years old. ucOC was negatively correlated with BMD at all sites (r = –0.26 to –0.38, p < 0.001 to p < 0.0001), even after exclusion of the effect of age by partial correlation (for the femoral neck, r = –0.26, p < 0.01) and after controlling for serum parathyroid hormone. BMD was significantly lower at all sites of measurement in women with elevated ucOC (> 1.65 ng/ml, upper limit of the normal range in young women) than in those with normal ucOC (for the neck, 0.58 + 0.13 versus 0.43 + 0.13 g/cm2, p < 0.001). Similar results were obtained for ucOC expressed as the fraction of total OC (ucOC %). Multiple regression showed that ucOC has the highest predictive value for BMD when including age and body weight in the equation. In summary, our data indicate that serum ucOC is an independent determinant of BMD of the hip in elderly women. The mechanism by which serum ucOC is related to bone mass is unclear and should be addressed in further studies. However, our data suggest that ucOC level may be an interesting marker in the investigation of bone status in the elderly.
Bone mass improves in alcoholics after 2 years of abstinence
Authors: Peris Pilar , Parés Albert , Guan̄abens Núria , Del Río Luis , Pons Francesca , De Osaba Maria Jesús Martínez , Monegal Ana , Caballería Joan , Rodés Joan , Muñoz-Gómez José
Published: February 2010

To evaluate the effect of abstinence on bone mass and bone mineral metabolism in chronic alcoholics, a 2 year longitudinal follow-up study was carried out in a group of 30 chronic alcoholic males who started a rehabilitation program. Lumbar and femoral bone mineral density (BMD) and serum levels of osteocalcin and 25-hydroxyvitamin D were measured at entry and after 1 and 2 years in all patients. Circulating cortisol and parathyroid hormone were measured in 14 and 6 patients, respectively, at entry and every year. Testosterone was measured in 18 patients at entry and after 1 year. At entry, lumbar BMD was significantly lower in alcoholics (1.06 + 0.03 g/cm2) than in age-matched healthy men (1.22 + 0.03 g/cm2; p < 0.001). Circulating osteocalcin and vitamin D levels were also significantly lower in alcoholics than in controls. Lumbar and femoral neck BMD increased in alcoholics after 2 years of abstinence (lumbar BMD, mean + SEM, 1.06 + 0.03 to 1.10 + 0.04 g/cm2, p < 0.05; femoral BMD, 0.82 + 0.02 to 0.84 + 0.02 g/cm2; p < 0.02). Moreover, lumbar BMD increased in alcoholics (2.9 + 1.4%) and decreased in controls (–1.1 + 0.2%; p < 0.02). Femoral BMD also increased in alcoholics (2.8 + 1.0%) but the expected mean decrease of –0.92% was found in healthy age-matched males. Baseline low osteocalcin levels (5.1 + 0.6 ng/ml) increased after 1 year (8.6 + 0.5 ng/ml, p < 0.001) and 2 years of abstinence (9.5 + 0.7 ng/ml, p < 0.001). No significant changes in 25-hydroxyvitamin D, parathyroid hormone, testosterone, or cortisol levels were observed throughout the study. Presence and severity of liver disease did not correlate with bone mass changes. We conclude that in chronic alcoholics lumbar and femoral neck bone mass improves after abstinence. The increase in circulating osteocalcin without associated changes in other circulating hormones further supports the hypothesis that alcohol has deleterious effects on bone formation.
Direct, enzyme-linked immunoassay for urinary deoxypyridinoline as a specific marker for measuring bone resorption
Authors: Dr. Robins Simon P. , Woitge Henning , Hesley Robert , Ju Julia , Seyedin Saeid , Seibel Markus J.
Published: February 2010

Several studies in recent years have shown that the pyridinium crosslinks of collagen provide good urinary markers of collagen degradation, primarily reflecting bone resorption. Most studies, however, were based on time-consuming HPLC assays of the crosslinks. We now describe the development of an immunoassay (ELISA) based on a monoclonal antibody for free deoxypyridinoline (Dpd) and its use in healthy individuals and patients with bone-related disorders to measure the urinary excretion of Dpd as an improved assessment of bone resorption rate. The Dpd antibody exhibited less than 1% cross-reaction with free pyridinoline and was shown to react only with free Dpd in urine, having no significant interaction with peptide forms of the crosslinks. The intra- and interassay variations were less than 10 and 15%, respectively. A total of 402 urine samples from patients and healthy volunteers were analyzed by both the immunoassay and HPLC. The ELISA results were highly correlated with those for total Dpd measured by HPLC over the full range of sample groups (r = 0.95). In normal adults, the excretion of Dpd (mean + SD) was 4.7 + 1.6 nmol/mmol creatinine, with about fivefold higher excretion rates in children. For 31 osteoporotic patients, the ELISA Dpd values (median 6.7; range 3.0–13.5 nmol/mmol Cr) were significantly higher (p < 0.0001) than the corresponding values for age- and sex-matched controls (median 4.0; range 1.8–7.4). The difference between the groups was similar for total Dpd by HPLC (osteoporotic: mean 12.8, range 4.8–30.7; controls: 6.6, range 3.0–18.1; p < 0.0001). For other patient groups, comparisons of the Dpd excretion with healthy controls revealed similar differences for both the immunoassay and total Dpd analyses in primary HPT (n = 23: p < 0.0001), Paget's disease (n = 28, p < 0.0001), renal dysfunction (n = 26, no significant difference), and breast cancer (n = 17, p < 0.0001). We conclude that the immunoassay constitutes a simpler, more direct way of assessing bone resorption rates that provides similar information to the more cumbersome HPLC methods.
Brittle bones in spontaneously diabetic female rats cannot be predicted by bone mineral measurements: Studies in diabetic and ovariectomized rats
Authors: Verhaeghe J. , Suiker A.M.H. , Einhorn T.A. , Geusens P. , Visser W.J. , van Herck E. , van Bree R. , Magitsky S. , Bouillon R.
Published: February 2010

Spontaneously diabetic BB rats were sham operated (SO) or ovariectomized (OVX) within days after onset and studied after 4, 8, and 12 weeks. Analyses included histomorphometry of proximal tibial metaphyses, biochemical analyses of humeri, DXA analyses, and biomechanical testing of femora. In SO diabetic rats, no osteoblasts, osteoid tissue, or osteoclasts were present on the trabecular bone surface, but trabecular bone volume (TBV) remained normal compared with control BB rats. The concentration of IGF-I per dry weight of humerus was decreased after 12 weeks of diabetes, whereas the concentrations of calcium and osteocalcin did not change. DXA analysis showed normal bone mineral density (BMD) at both diaphyseal and metaphyseal femoral areas. On biomechanical testing, angular deformation, energy absorption, and torsional strength of the femora were decreased after 8–12 weeks of diabetes, but stiffness was normal. Ovariectomy in diabetic rats caused a decrease in femoral BMD especially at the metaphysis, and there was a trend toward decreased TBV in the tibial metaphysis; TBV loss was less marked than in control OVX rats, however. The increase in BMD at the femoral diaphysis, measured after 12 weeks of OVX in control rats, was absent in diabetic rats. Multiple-regression analysis indicated that the presence of diabetes but not ovariectomy, weight, and mineral content correlated with decreased energy absorption, angular deformation, and strength of the femora. The data infer that the (near) absence of unmineralized bone matrix in severely diabetic rats alters bone microarchitecture and ultimately results in brittle bones, which is not predicted by BMC or BMD measurements.
Fluctuation of mineral apposition rate at individual bone-remodeling sites in human iliac cancellous bone: Independent correlations with osteoid width and osteoblastic alkaline phosphatase activity
Authors: Bradbeer Jeremy N. , Lindsay Peter C. , Reeve Jonathan
Published: February 2010

We investigated the determinants of bone formation at individual remodeling sites (BMUs) in cancellous bone from 8 osteologically normal, sex hormone-replete women with endometriosis. All were tetracycline double- labeled (2, 12, 2, and 4 day regime) before iliac bone biopsy. At each BMU the mineral apposition rate (MAR) was determined conventionally from the distance between label midpoints (MAR 1) and also from the distance between the mineralization front and the trailing edge of the second label (MAR 2). MAR 1 and 2 were compared with within-BMU measurements of osteoid width (O.Wi) and the activities of osteoblastic alkaline phosphatase (AP) and succinic dehydrogenase (SDH, an enzyme in the Krebs cycle), both quantitated by microdensitometry. A total of 143 BMUs were evaluated, of which 88 were satisfactory for all measurements and 132 were satisfactory for all but SDH. There was a weak correlation (r = 0.34) between MAR 1 and 2 at individual sites, with a mean difference of 0.49 μm/day (mean MAR 0.82 μm/day). The mean MAR of individual subjects tended to be either increasing or decreasing (F = 16.1, p < 0.01). In linear regressions, MAR 2 was statistically dependent on O.Wi, AP, and SDH (73% of the variance accounted for). In contrast, MAR 1 was weakly correlated with O.Wi and only 30% of its variance was accounted for by AP, SDH, and O.Wi. The variance in the MAR 2 data was inversely increased (p < 0.01) compared with MAR 1 as the number of days of bone formation represented. The data are best explained by large within-BMU variations in MAR over periods of up to a few days and longer term trends affecting all BMUs. Correlations between fluctuation in MAR and osteoblastic AP and SDH activity suggest that bone formation depends partly on AP activity and osteoblast energy balance. Random obliquity of sectioning has considerable theoretical effects on some correlations (e.g., between O.Wi and MAR), but further investigation emphasized the likely biologic importance of the correlations involving enzyme activities.
Characteristics and properties of osteocytes in culture
Authors: van der Plas A. , Aarden E.M. , Feijen J.H.M. , de Boer A.H. , Wiltink A. , Alblas M.J. , de Leij L. , Nijweide P.J.
Published: February 2010

Although the osteocyte is the most abundant among the highly differentiated cells of mature bone (osteocytes, lining cells, osteoblasts, and osteoclasts), its properties and functions are the least known and understood. Here we isolated osteocytes from mixed populations of bone cells liberated from fetal chick calvariae by alternate treatments with collagenase and EDTA. The osteocytes were removed from the bone cell populations by binding them via an osteocyte-specific antibody (MAb OB 7.3) to magnetic beads and removing the beads together with the coupled osteocytes from the population using a magnet. Isolated osteocytes were found to be highly differentiated, postmitotic cells that required their typical stellate morphology in culture. Osteocyte populations had alkaline phosphatase (ALP) activity somewhat lower than that of the osteoblast-like cell populations from which they were separated by the immunodissection procedure. On the single-cell level, the ALP activity was highly variable. Parathyroid hormone (PTH) receptors were found to be present on osteocytes as well as on osteoblast-like cells, but not on fibroblast-like cells of the outer periosteum. In response to PTH, osteocytes increased their intracellular levels of cAMP, as did the osteoblast-like cells. Osteocytes appeared to be somewhat more sensitive to PTH than osteoblasts. When seeded onto dentin slices, osteocytes did not corrode the dentin surface to any appraisable degree. We therefore found no evidence to support the notion that osteocytes play a role in the calcium homeostasis through osteocytic osteolysis. Whether osteocytes play an important role in perceiving and transducing hormonal and/or mechanical stimuli remains open for future research.
Comparison of radiographic absorptiometry with dual-energy X-ray absorptiometry and quantitative computed tomography in normal older white and black women
Authors: Kleerekoper Michael , Nelson Dorothy A. , Flynn Michael J. , Pawluszka Annie S. , Jacobsen Gordon , Peterson Edward L.
Published: February 2010

Bone mineral density (BMD) of the phalanges of the hand was measured by the technique of radiographic absorptiometry (RA) in 199 older postmenopausal women previously determined to have normal BMD by dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). The average age of the women was 66.8 ± 4.9 years, and they were 19.9 ± 6.7 years postmenopause. In the 54 black women, phalangeal BMD was 11.7% greater than in the 145 white women, a difference comparable to that found using DXA at the radial midshaft, the lumbar spine, and femoral neck. A correlation matrix comparing BMD measured by RA to BMD measured by DXA and QCT indicates that, in general, RA was related to the various DXA and QCT measurement sites as well as these sites were related to each other. When results for RA, DXA, and QCT obtained in our cohort of older women were compared to available reference data for peak adult bone mass, the average difference (SD units) from peak value was greatest for RA (-1.77 radius, −1.24 spine, −2.13 femoral neck, −2.34 QCT spine, and −2.71 phalanges). We conclude that RA is an acceptable measure of phalangeal BMD and that the data in our cohort can serve as reference data for older white and black women aged 55–75 years. Once the ability of RA to predict future fracture occurrence has been demonstrated, it could be rapidly deployed as a low-cost, widely available bone mass measurement technique.