bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphate transport in immortalized cell cultures from the renal proximal tubule of normal and Hyp Mice: Evidence That the HYP gene locus product is an extrarenal factor
Authors: Dr. Nesbitt Teresa , Econs Michael J. , Byun Jong K. , Martel Josée , Tenenhouse Harriet S. , Drezner Marc K.
Published: February 2010

Whether renal phosphate wasting in X-linked hypophosphatemia (XLH) results from an intrinsic renal or humoral defect remains controversial. In studies of the murine homolog of XLH, harboring the Simian Virus 40 (SV40) large T antigen, we obviated the influence of renal cell heterogeneity and impressed memory by comparing Na+-phosphate cotransport in immortalized cells from the S1 segment of the proximal tubule. Cells from SV40 transgenic normal and Hyp mice exhibit characteristics of differentiated proximal tubule cells including gluconeogenesis and alkaline phosphatase activity. Surprisingly, however, we found two distinct populations of cells from the S1 proximal tubule of both normal and Hyp mice. In one, PTH treatment increases cAMP accumulation, while in the other both PTH and thyrocalcitonin enhance cAMP production. Kinetic parameters for Na+-phosphate cotransport were similar in both subpopulations of cells from normal (Km, 0.29 ± 0.03 vs. 0.39 ± 0.04 mM; Vmax, 4.6 ± 0.6 vs. 5.2 ± 0.4 nmol/mg/5 minutes) and Hyp mice (0.33 ± 0.02 vs. 0.26 ± 0.04; 6.0 ± 0.7, 4.8 ± 0.6). More importantly, phosphate transport in S1 cells of either subpopulation from Hyp mice is no different than that of normals. These data indicate that renal proximal tubule cells from Hyp mice have intrinsically normal phosphate transport and support the hypothesis that a humoral abnormality underlies renal phosphate wasting in XLH.
Effect of ovariectomy on cancellous bone in the hypophysectomized rat
Authors: Chen Meng-Meng , Dr. Yeh James K. , Aloia John F.
Published: February 2010

This experiment studied the effects of hypophysectomy (HX) and ovariectomy (OV) on cancellous bone in the proximal tibia and distal 5th lumbar vertebra by dynamic histomorphometry. Forty-eight female Sprague-Dawley rats, 3 months of age, were divided into age-matched control, HX, OV, and HX + OV (HO) groups. Ten rats were sacrificed at 3 months of age as baseline controls, and the rest of the animals were sacrificed 5 weeks after the surgery. While the age-matched controls and OV rats significantly increased in body weight compared with the baseline control rats, cancellous bone volumes in the proximal tibia and distal 5th lumbar vertebra increased in the age-matched controls and decreased in the OV rats. In the HX and HO rats, body weight equaled baseline control values, and their cancellous bone volumes were decreased with a poorer trabecular architecture in both bone sites. In all HX, OV, and HO rats, uterine weight and serum estradiol were significantly decreased. OV significantly increased longitudinal bone growth and the tissue- and surface-based bone formation and bone resorption parameters in both the proximal tibia and 5th lumbar vertebra (p < 0.05). HX alone or HO significantly decreased longitudinal bone growth and the tissue-based bone formation rate without significantly affecting surface-based bone formation and bone resorption parameters when compared with the age-matched controls. No significant differences were detected in any variable between the HX alone and HO rats. In this study, HX on OV rats decreased the longitudinal bone growth, cancellous bone turnover (tissuebased), and cancellous bone volume in the proximal tibia and distal 5th lumbar vertebra in young rats at 5 weeks after surgery. We suggest that the bone loss in the HO rats was due primarily to pituitary hormone deficiency and that the effect of ovarian hormone deficiency on cancellous bone is pituitary hormone dependent.
Bone structure in postmenopausal hyperparathyroid, osteoporotic, and normal women
Authors: Dr. Parisien May , Cosman Felicia , Mellish Robert W. E. , Schnitzer Michele , Nieves Jeri , Silverberg Shonni J. , Shane Elizabeth , Kimmel Donald , Recker Robert R. , Bilezikian John P. , Lindsay Robert , Dempster David W.
Published: February 2010

The purpose of this study was to test the hypothesis that patients with mild primary hyperparathyroidism are protected against postmenopausal (PM) loss of cancellous bone architecture. To achieve this, we compared bone structure and turnover in iliac bone biopsies from three groups: 16 women with mild primary hyperparathyroidism (PHPT; 58.2 ± 2.2 years, 11.5 ± 1.7 years PM), 17 women with untreated primary osteoporosis (OP; 65.1 ± 2.0 years, 17.2 ± 2.3 years PM), and 31 healthy women (N; 59.8 ± 1.4 years, 13.4 ± 1.5 years PM). The bone formation rate was significantly higher in PHPT than in either OP or N, and not different between OP and N. Cancellous bone volume, total strut length, and indices of connectivity (node number, node to node strut length, and node to terminus ratio) were significantly lower in OP than either PHPT or N but were the same or higher in PHPT than in N. Indices of disconnectivity were significantly lower in PHPT than in N, whereas they were the same or higher in OP than N. The data were also analyzed in subgroups matched by years PM with no changes in the results. These findings indicate that osteoporotic patients with normal bone turnover have low bone volume and micro-architectural deterioration, while patients with mild PHPT have normal bone volume and normal or greater trabecular connectivity despite higher bone turnover. These findings suggest that mild PHPT protects against the loss of cancellous bone structure that normally follows menopause.
Age and temperature related changes to the ultrastructure and composition of human bone mineral
Authors: Holden J.L. , Clement J.G. , Phakey P.P.
Published: February 2010

This X-ray diffraction (XRD) investigation of heat-treated human femoral bone showed that the main mineral phase of both unheated bone and bone heated to 600°C resembled that of a poorly crystalline form of hydroxy-apatite. The rod-shaped apatite crystals in unheated bone persisted in bone heated up to 400°C. Recrystallization at approximately 600°C, produced larger crystals, which either retained their original morphology or changed to tabular or equidimensional shapes. The size of the apatite crystals in unheated and heated bone specimens was dependent on both temperature and age. When heated above 600°C the crystallinity of the bone mineral increased, and the XRD pattern more closely resembled that of hydroxyapatite. Partial decomposition of the hydroxyapatite phase to calcium oxide above 1000°C, and β-tricalcium phosphate, α-tricalcium phosphate, and calcium oxide phosphate between 1200°C and 1400°C, indicated that the original apatite phase was both calcium deficient and contained carbonate. The relative peak intensities of the thermal decomposition products were related to some extent to the age of the deceased person and reflected the compositional changes that occur during bone aging. Because the thermally induced changes to the composition and ultrastructure of bone mineral were influenced by the age of the individual, this investigation proposed that the heat treatment of bone tissue may offer an alternative way of studying bone aging.
Three-dimensional nuclear magnetic resonance microimaging of trabecular bone
Authors: Chung Hsiao-Wen , Wehrli Felix W. , Williams John L. , Wehrli Suzanne L.
Published: February 2010

The conventional approach to measuring structural parameters in trabecular bone rests on stereology from optical images, derived from sections of embedded bone. In order to provide data that are statistically representative of a sufficiently large volume, multiple sections need to be analyzed in each of the three orthogonal planes. In this work, an alternative technique is presented which is based on three-dimensional (3D) volumetric proton nuclear magnetic resonance (NMR) microimaging. The method presented provides images from 9 × 9 × 4 mm3 volumes of defatted bone specimens in 15–20 minutes scan time at isotropic resolution corresponding to (78 μm)3 voxel size. Surface-rendered images of bovine and human trabecular bone are shown and an algorithm was developed and implemented for determining the orientation and magnitude of the principal axes of the mean intercept length tensor.
Osteoblasts are regulated by the cellular adhesion through ICAM-1 and VCAM-1
Authors: Dr. Tanaka Yoshiya , Morimoto Isao , Nakano Yoichiro , Okada Yosuke , Hirota Seiichi , Nomura Shintaro , Nakamura Toshitaka , Eto Sumiya
Published: February 2010

The two major processes of bone metabolism—bone formation and resorption—are regulated by cellular interactions. Osteoblasts and osteoclasts play a significant role in bone metabolism, which is known to be regulated by local soluble factors and systemic hormones. Although bone is a heterogeneous tissue comprised of osteogenic and hematopoietic cells, cellular adhesion of osteoblasts and its regulation remains to be understood. We first demonstrate that cellular adhesion by which osteoblasts communicate with opposing cells in bone milieu is involved in the osteoblast activation: (a) purified human osteoblasts obtained from osteoarthritis patients expressed particular adhesion molecules, ICAM-1, VCAM-1, and LFA-3; (b) the osteoblasts adhered to T cells which were used as representative adhesive partners, since T cells possess all the receptors to these adhesion molecules; (c) mRNA transcription and secretion of IL-1β and IL-6 were induced in the osteoblasts by the cellular adhesion to T cells and they were reduced by interrupting the adhesion; (d) cross-linking of ICAM-1 and VCAM-1 on the osteoblasts induced IL-6 secretion from the osteoblasts. These results indicate that osteoblasts adhere to opposing cells through particular adhesion molecules on their surface and that the adhesion molecules on the osteoblasts not only function as glue with opposing partners but transduce activation signals that facilitate the production of bone-resorbing cytokines. We propose that cellular adhesion of osteoblasts as well as soluble factors is significant for the regulation of bone metabolism.
Short-term effect of testosterone treatment on reduced bone density in boys with constitutional delay of puberty
Authors: Bertelloni Silvano , Baroncelli Giampiero I. , Battini Roberta , Perri Giuseppe , Saggese Giuseppe
Published: February 2010

We studied bone mineral content (BMC), bone mineral density (BMD), cortical thickness/total width (CT/TW) ratio and cortical area/total area (CA/TA) ratio in boys with constitutional delay of puberty and the effect of short-term testosterone treatment on bone mass. Seventeen boys (age 13.1-15.8 years) who met the family history and the clinical criteria of constitutional delay of puberty were selected and enrolled in the study. All subjects were eating a diet assuring an adequate intake of calories and calcium. A subset of 8 boys (group A) was treated with testosterone depot (100 mg/month x 6 months) while 9 boys (group B) were not. At inclusion, BMC and BMD were reduced in the patients according to their chronological age (BMC -4.04 ± 1.34 standard deviation scores [SDS]; BMD -2.95 ± 0.56 SDS), statural age (BMC -1.75 ± 0.79 SDS; BMD -1.69 ± 0.78 SDS), and bone age (BMC -1.80 ± 0.65 SDS; BMD -1.86 ± 0.68 SDS). No significant differences between the groups were found (group A: BMC 0.480 ± 0.57 g/cm, BMD 0.488 ± 0.037 g/cm2, CT/TW ratio 0.43 ± 0.4, CA/TA ratio 0.68 ± 0.04; group B: BMC 0.476 ± 0.060, p = NS vs. group A; BMD 0.491 ± 0.036 g/cm2, p = NS vs. group A, CT/TW ratio 0.42 ± 0.05, p = NS vs. group A; CA/TA ratio 0.67 ± 0.06, p = NS vs. group A). At 12 months of follow-up, BMC, BMD, CT/TW ratio, and CA/TA ratio significantly increased in group A (BMC 0.70 ± 0.13 g/cm, δ +41.1 ± 28.8%, p < 0.003 vs. 0 month; BMD 0.617 ± 0.082 g/cm2, δ + 26.2 ± 13.6%, p < 0.005 vs. 0 month; CT/TW ratio 0.52 ± 0.05, δ +20.59 ± 10.65%, p < 0.001 vs. 0 month; CA/TA ratio 0.77 ± 0.05, δ +13.60 ± 6.65%, p < 0.004 vs 0 month), but not in group B (BMC: 0.48 ± 0.05 g/cm; δ +5.1 ± 7.8%, p = NS vs. 0 month; BMD: 0.492 ± 0.037 g/cm2; δ + 0.54 ± 8.7%, p = NS vs. 0 month; CT/TW ratio 0.44 ± 0.04, δ +4.04 ± 6.75%, p = NS vs. 0 month; CA/TA ratio 0.68 ± 0.05, δ +2.39 ± 5.90%, p = NS vs. 0 month). We conclude that boys with constitutional delay of puberty have reduced BMC and BMD. The delay in statural and bone ages did not totally account for the decreased bone mass. Testosterone treatment for 6 months significantly increased BMC, BMD, CT/TW ratio, and CA/TA ratio in these patients, but definitive conclusions on the efficacy of the treatment in improving adult bone mass can be drawn only when our patients reach early adulthood.
Effect of menopause on femoral and vertebral bone loss
Authors: Pouilles J.M. , Tremollieres F. , Dr. Ribot Claude
Published: February 2010

The aim of this study was to investigate the effect of menopause on bone loss in the proximal femur and the lumbar spine. The rates of change in bone mineral density (BMD) were measured longitudinally by dual X-ray absorptiometry (DXA) at the femoral neck (FN), Ward's triangle (WT), and trochanter (TR) together with the lumbar spine in 81 healthy postmenopausal women (45-65 years of age) who had passed a natural menopause, 6 months to 12 years before. A significant correlation between the rate of change and interval since menopause was evidenced. The best fit of the data was a binomial function of interval since menopause at the spine, FN, and WT and a simple linear regression at TR level. At each skeletal site, the rate of bone loss (mean ± SD) was significantly different (p < 0.05) and twice as high in women who were between 6 months and 2 years postmenopausal at enrollment (FN, -1.82 ± 1.1.%; WT, -2.43 ± 1.7%; TR, -1.12 ± 1.7%) than in those who were beyond 5 years of menopause (FN, -0.48 ± 0.8%; WT, -0.68 ± 2.1%; TR, 0.41 ± 1.2%). A poor correlation (r = 0.39 - 0.42, p < 0.001) was found between the rate of vertebral and that of femoral postmenopausal bone loss. This study demonstrates that menopause is associated with a rapid and transient bone loss in BMD of the proximal femur, which declines with time after 3 years. These data suggest that therapy should be initiated as early as possible after menopause to prevent bone loss.
Defect in formation of functional matrix vesicles by growth plate chondrocytes in avian tibial dyschondroplasia: Evidence of defective tissue vascularization
Authors: Nie Daotai , Genge Brian R. , Wu Licia N.Y. , Prof. Wuthier Roy E.
Published: February 2010

Avian tibial dyschondroplasia (ATD), a disease characterized by an almost total lack of mineralization in affected areas of growth plate cartilage, may involve defective matrix vesicle (MV) mineralization. To explore the biochemical defect in ATD, both normal and diseased tissue were analyzed for the amount of isolatable MVs, their chemical composition, and their ability to induce mineral formation. We found significantly fewer MVs in ATD tissue, and in contrast to normal MVs, which rapidly mineralized when incubated in synthetic cartilage lymph, those isolated from ATD lesions induced only limited mineralization even after prolonged incubation. Analysis by detergent extraction revealed a nearly dysfunctional nucleational core in ATD MVs. Thus, in ATD tissue, there is a defect in the formation of MVs, and those that form are nearly inactive. There were also alterations in the lipid-dependent Ca2+-binding proteins (annexins) in ATD MVs. There were lower levels of annexins II and VI in endogenously produced collagenase-released matrix vesicles (CRMVs), but not in matrix vesicle–enriched microsomes (MVEMs) produced by tissue homogenization. These findings indicate that there is insufficient Ca2+ in ATD cells to enable incorporation of the annexins into MVs. Finally, there was evidence of phospholipid breakdown in ATD MVs, as well as in ATD tissue generally. This indicated that the ATD lesions were becoming necrotic. Taken together, these findings indicate that there is a defect in tissue vascularization such that the supply of mineral ions and nutrients to ATD cartilage is inadequate to support normal MV formation and subsequent mineralization.
Effects of extracellular calcium on insulin-like growth factor II in human bone cells
Authors: Honda Yoko , Fitzsimmons Robert J. , Baylink David J. , Mohan Subburaman
Published: February 2010

Extracellular calcium concentration is critically important for normal function of the body. Recently, reports have shown that cells derived from parathyroid glands contain an extracellular calcium receptor that is responsive to changes in extracellular calcium. Bone is also intimately involved in calcium homeostasis; therefore, we sought to test the hypothesis that extracellular calcium has direct effects on bone cells. Extracellular calcium was increased by the addition of varying concentrations of CaCl2 (0.4–2.0 mM) to the control medium. An increase in extracellular calcium increased cell proliferation, as assessed by 3H-thymidine incorporation, in a number of cell types including normal human bone cells derived from vertebrae (HBV155) and a number of human osteosarcoma cell lines. The increase in cell proliferation by elevated CaCl2 was dose dependent, whereas MgCl2 was not effective at the doses tested (up to 2 mM added MgCl2). To test the hypothesis that the mitogenic activity of elevated extracellular calcium involved a growth factor, levels of insulin-like growth factor II (IGF-II) were measured in the conditioned medium of HBV155 cells by radioimmunoassay after removal of binding proteins by size exclusion chromatography. The effects of an increase in extracellular calcium by 1 mM were: 1) increased culture media levels of IGF-II within 1 h of treatment, 2) the increase in IGF-II levels reached a maximum after 8 h of treatment, and 3) IGF-II levels were still elevated after 24 h of treatment. Furthermore, a blocking monoclonal antibody against IGF-II abolished the increased cell proliferation in HBV155 cells following elevation of extracellular calcium. Taken together, these findings suggest that an increase in extracellular calcium results in an increase in IGF-II which is required for the subsequent increase in cell proliferation.
Stimulatory effect of bone morphogenetic protein-2 on osteoclast-like cell formation and bone-resorbing activity
Authors: Kanatani Masanori , Sugimoto Toshitsugu , Kaji Hiroshi , Kobayashi Tatsuya , Nishiyama Katsuhito , Fukase Masaaki , Kumegawa Masayoshi , Chihara Kazuo
Published: February 2010

Although the action of bone morphogenetic protein (BMP) on osteoblast differentiation has been extensively investigated, its effect on osteoclast differentiation remains unknown. In the present study, in vitro effects of BMP-2 on osteoclast-like cell formation and bone resorption were examined. BMP-2 (1–100 ng/ml) significantly stimulated bone resorption by preexistent osteoclast-like cells in mouse bone cell cultures containing stromal cells, whereas it did not affect the bone-resorbing activity of isolated rabbit osteoclast-like cells. When BMP-2 was added to unfractionated bone cells after degeneration of preexistent osteoclast-like cells, BMP-2 dose-dependently stimulated osteoclast-like cell formation at a minimal effective concentration of 10 pg/ml. BMP-2 also enhanced the osteoclast-like cell formation induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Moreover, osteoclast-like cells newly formed by BMP-2 from unfractionated bone cells possessed the ability to form pits on dentine slices. Because these results indicated that BMP-2 directly or indirectly stimulated osteoclast differentiation and activity, we next examined the direct effect of BMP-2 on osteoclast precursors in the absence of stromal cells using hemopoietic blast cells derived from spleen cells. The mRNA for BMP-2/4 receptor was detected in hemopoietic blast cells supported by granulocyte-macrophage colony-stimulating factor (GM-CSF) as well as osteoblastic MC3T3-E1 cells and MC3T3-G2/PA6 stromal cells by RNase protection assay. BMP-2 dose-dependently stimulated osteoclast-like cell formation from hemopoietic blast cells supported by GM-CSF at a minimal effective concentration of 10 pg/ml. BMP-2 also enhanced 1,25(OH)2D3-induced osteoclast-like cell formation from hemopoietic blast cells. The present data are the first to indicate that BMP-2 stimulates bone resorption through both direct stimulation of osteoclast formation and activation of mature osteoclasts, possibly via stromal cells, in vitro.
Changes in phenotypic gene expression in rat mandibular condylar cartilage cells during long-term culture
Authors: Inoue Hiroyuki , Nebgen Denise , Dr. Veis Arthur
Published: February 2010

Gene expression patterns have been investigated in prolonged cultures of rat mandibular condylar cartilage (MCC) cells to examine the possibility of culture-induced phenotypic changes. MCC cells were isolated from newborn rats and grown in the presence of 10% fetal bovine serum (FBS) and basic fibroblast growth factor (bFGF). MCC cells were passaged and cultured in the presence of 10% FBS and bFGF until confluent. After confluence, the medium was changed to that supplemented with 10% FBS, ascorbate, and β-glycerophosphate (day 1). Mineralization and gene expression of MCC cells have been investigated. Mineralization, visualized by staining with Alizarin red, was observed to begin at day 13 in culture, and increased up to day 22 in culture, which was the length of this study. Type II collagen and aggrecan mRNAs were highly expressed at the start of culture (day 1–4) and decreased in a time-dependent manner. Type I collagen, alkaline phosphatase, and osteopontin mRNAs expressed biphasic patterns that peaked at the start of culture and the beginning of mineralization (day 13–16). Osteonectin mRNA was expressed throughout the culture period. Osteocalcin mRNA was expressed before the beginning of mineralization peaking at day 7. These observations suggest that the gene expression patterns of MCC cells can be categorized into two different periods in prolonged culture: maturation (day 1–10) and mineralization (day 13–22). The cell culture system of MCC represents a new model system in which the differentiation of embryonic MCC cells can be examined.
Early induction of alterations in cancellous and cortical bone histology after orchiectomy in mature rats
Authors: Gunness M. , Orwoll E.
Published: February 2010

Androgen deficiency is associated with low bone mass in humans and animals, but the remodeling alterations that lead to bone loss are unclear. Our objective was to define early responses in both cancellous and cortical bone to orchiectomy (ORX) using histomorphometry in sexually mature (4-month-old) rats. A total of 62 male rats, 4 months of age, were divided into six groups, sham operated (SH) or orchiectomized (ORX), and sacrificed 1, 2, or 4 weeks after ORX. Calcein was given 5 and 2 days before sacrifice to label mineralizing surfaces. Bone mineral density (BMD) was measured in excised femurs by dual energy X-ray absorptiometry (DEXA). Static and dynamic histomorphometry was evaluated in the cancellous bone of the proximal tibial metaphysis and lumbar vertebral bodies, and in the cortical bone of the tibial diaphysis. Osteopenia began to develop by 2 weeks after ORX, though weight gain and femur length did not change. Femoral BMD was significantly reduced and BMC decreased (NS) by 4 weeks after ORX (p < 0.05). Tibial and vertebral cancellous bone volume decreased 19% and 13%, respectively, while osteoblast and osteoclast surfaces, and numbers of osteoclasts, increased after ORX. At 2 weeks post-ORX, an increase in cancellous bone formation rate was attributable primarily to an increase in mineralizing surfaces and a smaller rise in mineral apposition rate. In contrast, cortical bone periosteal, but not endosteal, bone formation rate and mineralizing surfaces decreased. We conclude that ORX stimulates cancellous and diminishes periosteal bone turnover rapidly after ORX, with subsequent decreases in bone volume and mineral density. The clear divergence in cortical and cancellous bone responses to hypogonadism raises important questions regarding the control of bone formation and its role in defining the skeletal phenotype.
Body composition and bone mineral density in premenopausal and early perimenopausal women
Authors: Salamone Loran M. , Glynn Nancy , Black Dennis , Epstein Robert S. , Palermo Lisa , Meilahn Elaine , Kuller Lewis H. , Cauley Jane A.
Published: February 2010

Body composition appears to be an important determinant of bone mineral density (BMD). BMD at the femoral neck, lumbar spine, and whole-body and the whole-body soft-tissue composition were measured cross-sectionally in 334 healthy premenopausal and early perimenopausal women, aged 44–50 years, using a Hologic QDR densitometer. Correlations between lean mass and BMD at the hip, spine, and whole-body were greater (r = 0.40, r = 0.44, and r = 0.45, respectively, p < 0.0001) than those for fat mass (r = 0.19, r = 0.16, and r = 0.16, respectively, p < 0.01). There was a significant linear trend in femoral BMD from the lowest to highest category of lean mass (0.75 ± 0.10 g/cm2, 0.80 ± 0.10 g/cm2, and 0.86 ± 0.09 g/cm2, p < 0.0001). Similar trends were demonstrated for spinal and whole-body density. For categories of fat mass, there was a significant linear trend at the hip (0.78 ± 0.10 g/cm2, 0.79 ± 0.10 g/cm2, and 0.83 ± 0.10 g/cm2, p = 0.0106), but not at the spine or whole-body. There was a 5.00% (3.62, 6.38; 95% confidence limits) difference in hip BMD per unit (standard deviation) of lean mass, while only a 0.73% (-0.66, 2.11) difference in hip BMD per unit (SD) of fat mass. Differences in BMD were examined by categories of lean and fat mass (low, medium, high) for a total of nine possible combinations of lean and fat measures. BMD at the hip, spine, and whole-body were significantly higher in those with high lean mass than in those with low lean mass, irrespective of fat mass. Women with high lean/low fat had similar hip, spinal, and whole-body BMD as those with high lean/high fat, despite their significantly lower body weight (62.5 ± 3.3 kg vs 85.7 ± 5.4 kg, respectively, p < 0.0001). In premenopausal and early perimenopausal women, body weight alone may not be associated with increased bone mass unless a significant proportion of that weight is comprised of lean mass. The stronger association between lean mass and BMD than that for fat mass may be attributed to differences in determinants of lean mass, such as exercise, lifestyle factors, estrogen levels, or a combination of these factors.
Hip and calcaneal bone loss increase with advancing age: Longitudinal results from the study of osteoporotic fractures
Authors: Ensrud Kristine E. , Palermo Lisa , Black Dennis M. , Cauley Jane , Jergas Michael , Orwoll Eric S. , Nevitt Michael C. , Fox Kathleen M. , Cummings Steven R.
Published: February 2010

It is uncertain whether or how rapidly elderly women continue to lose bone with advancing age. To determine rates of change in bone mass at the hip and at the calcaneus in elderly women and to compare these rates of change among estrogen users and nonusers, we prospectively measured rates of change in bone mineral density (BMD) at the total hip and its four subregions (mean ± SD, 3.55 ± 0.29 years between examinations) and at the calcaneus (mean ± SD, 5.69 ± 0.33 years between examinations) in 5698 community-dwelling white women aged 65 years or older at the baseline examination. The rate of decline in total hip BMD steadily increased from 2.5 mg/cm2/year (95% confidence interval 2.0 to 2.9) in women 67–69 years old to 10.4 mg/cm2/year in those aged 85 or older (95% confidence interval 8.4 to 12.4). The rate of bone loss also increased with aging at all subregions of the hip and at the calcaneus. The average loss of bone from the total hip is sufficient to increase the risk of hip fracture by 21% per 5 years in women aged 80 years or older. Compared with nonusers, current estrogen users had a 33% lower age-adjusted mean rate of loss at the total hip (2.9 vs 4.3 mg/cm2/year, p ≤ 0.0001) and a 35% lower age-adjusted mean rate of loss at the calcaneus (3.9 vs 6.0 mg/cm2/year, p ≤ 0.0001). The rate of bone loss in the hip and calcaneus steadily increases with advancing age in older women. Estrogen therapy may significantly decrease this loss. Efforts to understand and prevent bone loss should include elderly women.
Comparison of rates of bone loss from the spine measured using two manufacturers' densitometers
Authors: Peel N.F.A. , Dr. Eastell R.
Published: February 2010

Measurements of bone mineral density of the lumbar spine (LS-BMD) by dual-energy X-ray absorptiometry (DXA), made using different manufacturers' densitometers, differ by approximately 15%. The aim of this study was to compare the rate of bone loss from the lumbar spine measured using two manufacturers' densitometers. LS-BMD (vertebrae L2-L4) was measured using both a Lunar DPX and a Hologic QDR 1000/W in 17 postmenopausal women at baseline and 2 years. The mean rate of change of LS-BMD made using the two densitometers did not differ (DPX -0.54% per year; QDR -0.17% per year). Although rates of change of LS-BMD measured using the two densitometers correlated (r = 0.47, p = 0.05), the variance of the rates of loss differed such that, in individual subjects, the difference between the rates of loss of LS-BMD, measured using the two densitometers, was related to the average rate of loss (r = 0.61, p = 0.009). For both densitometers, as bone mineral content (BMC) increased, the measured area also increased, leading to an underestimate of change in bone mineral density (BMD). This relation differed between the two densitometers such that the change in BMD was underestimated to a greater extent by QDR. We conclude that in the context of multicenter studies it may not be possible to directly combine data on the rate of bone loss acquired using different manufacturers' densitometers.
Assessment of biochemical markers of bone metabolism in relation to the occurrence of fracture: A retrospective and prospective population-based study of women
Authors: Åkesson K. , Ljunghall S. , Jonsson B. , Sernbo I. , Johnell O. , Gärdsell P. , Obrant K.J.
Published: February 2010

We have in a population-based setting evaluated biochemical markers of bone metabolism in 328 women, aged 40–80 years, and related it to contents of bone mineral measurements and the retrospective and prospective presence of fracture. The participants were recruited from the city population files. Serum samples for analysis of osteocalcin (Oc), procollagen I carboxy-terminal extension peptide (PICP), and carboxy-terminal telopeptide of type I collagen (ICTP) were taken, and forearm bone mineral content (BMC) was measured by single photon absorptiometry (SPA). Fracture history was recorded, and the information was verified and supplemented from both radiologic and orthopedic files. Five years later the registration of fractures was repeated. At the initial investigation, Oc was 23% lower in women who had sustained a fracture (n = 37) within 6 years before measurement (6.3 ± 3.6 μg/1 vs 8.2 ± 4.2 μg/1 (p = 0.006)), after adjusting for age and BMC differences. PICP and ICTP were not different from values in the women without fracture. However, in women aged 70–80 years with a fracture sustained during the previous 6 years, PICP was lower (128 ± 32 μg/1 vs 144 ± 34 μg/1, p = 0.046). Oc and ICTP were significantly correlated to age and BMC (Oc-age r = 0.36, Oc-BMC r = –0.31, ICTP-age r = 0.44, ICTP-BMC r = –0.24). The correlations of PICP were weaker. Prospectively, logistic regression gave an odds ratio (OR) of 1.8 (p = 0.015) for a low PICP and fracture susceptibility, at a change of 1 SD, independent of age and BMC. In the age bracket 70–80, the odds ratio was 2.4 (p = 0.036). The odds ratio for ICTP, independent of age and BMC, was 1.9 (p = 0.043) for 1 SD decrease and subsequent fracture risk. We concluded that women who had sustained at least one recent fracture had an altered bone turnover with decreased bone formation but an unaltered resorption. Women with retrospectively registered fractures also sustained subsequent fractures. A decrease from the mean of the collagen markers PICP and ICTP was associated with an increased risk for future fracture. Utilizing these biochemical markers of bone metabolism in a female population, PICP and ICTP had a similar influence on the risk of future fracture as forearm BMC (OR = 1.6, p = 0.03).
Short-term treatment with growth hormone stimulates osteoblastic and osteoclastic activity in osteopenic postmenopausal women: A dose response study
Authors: Brixen Kim , Kassem Moustapha , Nielsen Henning K. , Loft Anne Gitte , Flyvbjerg Allan , Mosekilde Leif
Published: February 2010

To investigate the potential use of growth hormone (GH) in Activate-Depress-Free-Repeat treatment of postmenopausal osteoporosis, we measured changes in serum levels of biochemical markers of bone turnover, insulin-like growth factor-I (IGF-I), calciotropic hormones, and bone mineral density in 40 postmenopausal women with osteopenia (ages 52–73 years) in response to 7 days of treatment with either placebo or GH (0.05, 0.10, or 0.20 IU/kg/day) administered subcutaneously in the evening. GH treatment increased serum osteocalcin (p < 0.01) and C-terminal type-I procollagen propeptide (p < 0.01) and also serum levels of type-I collagen telopeptide (p < 0.001), fasting urinary hydroxyproline/creatinine (p < 0.05), pyridinoline/creatinine (p < 0.05), and deoxypyridinoline/creatinine (p < 0.01) in a dose-dependent fashion. Even the lowest dose of GH tested induced a significant increase in these parameters; however, the effects were transient lasting only 1–2 weeks. In the highest dose group, however, a somewhat prolonged effect (30 days) on serum osteocalcin was observed. Furthermore, GH increased serum levels of IGF-I, insulin, and tri-iodothyronin. No effect on serum 1,25-dihydroxyvitamin D3 or parathyroid hormone could be demonstrated. Adverse effects were mainly related to fluid retention. They were clearly dose-dependent and rapidly reversible. In conclusion, short-term GH treatment stimulates bone formation and bone resorption in postmenopausal women with osteopenia.
Radial and ulnar cortical thickness of the second metacarpal
Authors: Fox Kathleen M. , Kimura Sumiko , Powell-Threets Kia , Plato Chris C.
Published: February 2010

Differential bone mass at various skeletal sites, which may be due to mechanical stress exerted by the muscles attached to the bone, has been demonstrated for athletes who exert one limb more than the other. The question arises as to whether this bilateral asymmetry extends to the two sides of the same bone with different muscular attachments. The objectives of this study were to ascertain whether the radial and ulnar sides of the second metacarpal have similar cortical thicknesses and determine if bone mass decreases equally with age on the radial and ulnar sides. Hand-wrist radiographs were obtained from 201 male and 191 female Caucasian participants of the Baltimore Longitudinal Study of Aging. Differences between radial and ulnar cortical thickness within age groups were tested with Student's t-test and between age groups using analysis of variance. Radial cortical thickness of the second metacarpal was found to be 11–12% greater in men and 10–12% greater in women than ulnar cortical thickness in both the left and right hands. Age-related changes in radial cortical thickness were evident in both sexes. In men, radial cortex decreased linearly from age 40 to 89. For women, there was a sharp decline in radial thickness from age 50 to age 60. Ulnar cortical thickness declined from age 50 to 60 for women only. Muscle attachment along the radial length of the second metacarpal may influence the accumulation of bone mass on the radial side at younger ages while muscle disuse may precipitate the loss of bone preferentially from the radial side.
Soft Tissue Body Composition: Familial Resemblance and Independent Influences on Bone Mineral Density,
Authors: Krall Elizabeth A. , Dawson-Hughes Bess
Published: February 2010

Familial resemblance in fat and lean soft tissue and the influence of these body composition measures on bone mineral density (BMD) were determined in 162 adult members of 42 families. Whole body fat and lean mass and BMD of the spine and femoral neck were measured by dual-energy X-ray absorptiometry and BMD of the heel and radius by single-photon absorptiometry. Significant correlations of lean tissue were observed between mothers and daughters (r = 0.35, p < 0.05), fathers and sons (r = 0.36, p < 0.05), and daughters and sons (r = 0.42, p < 0.01) after adjustment for age, height, fat mass, physical activity, and parity (among women). Fat tissue was not significantly correlated among any family member pairs. Lean tissue, but not fat, was positively associated with BMD in one or more family member subgroups at all skeletal sites. These findings suggest a hereditary component to muscle mass. Previously documented familial similarities in bone density may be related in part to the influence of lean mass on bone density.
Comparative effects of 1,25-dihydroxyvitamin D3 and EB 1089 on mouse renal and intestinal 25-hydroxyvitamin D3-24-hydroxylase
Authors: Roy Stéphane , Martel Josée , Dr. Tenenhouse Harriet S.
Published: February 2010

EB 1089 is a vitamin D analog that is less potent than 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in its calcemic action but more potent in its antiproliferative action. We characterized the interaction of 1,25(OH)2D3 and EB 1089 with renal 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase), the first enzyme in the C-24 oxidation pathway, and compared the effects of 1,25(OH)2D3 and EB 1089 on induction of 24-hydroxylase mRNA in mouse kidney and intestine. 1,25(OH)2D3 and EB 1089 were competitive inhibitors of 24-hydroxylase activity. However, the K1 for 1,25(OH)2D3 (5.2 ± 2.5 nM) was significantly lower than that for EB 1089 (286 ± 59 nM). In the kidney, the time course and extent of 24-hydroxylase mRNA induction, relative to 18S rRNA, was similar for 1,25(OH)2D3 and EB 1089 with a peak response at ≈ 6 h that was sustained for at least 16 h. In the intestine, however, induction of 24-hydroxylase mRNA, relative to 18S rRNA, was ∼50% lower for EB 1089 than for 1,25(OH)2D3 at 3 h (p < 0.05) and 6 h (p < 0.05) while at 16 h 24-hydroxylase mRNA was no longer detectable. Moreover, while both 1,25(OH)2D3 and EB 1089 elicited a similar dose-dependent induction of 24-hydroxylase mRNA in the kidney (EC50 = 0.4 ± 0.13 and 0.3 ± 0.08 ng/g for EB 1089 and 1,25(OH)2D3, respectively), the EC50 for EB 1089 (6.6 ± 1.7 ng/g) was significantly higher than that for 1,25(OH)2D3 (0.9 ± 0.32 ng/g) in the intestine (p < 0.01). EB 1089 was also less effective than 1,25(OH)2D3 in the induction of intestinal but not renal calbindin-D9k mRNA. To determine the mechanism for tissue-specific differences in potency, we determined the binding affinity of 1,25(OH)2D3 and EB 1089 for the vitamin D receptor. In the kidney, Kd values for 1,25(OH)2D3 (0.40 ± 0.05 nM) and EB 1089 (0.48 ± 0.04 nM) were not different. However, in the intestine, the Kd for EB 1089 (1.43 ± 0.19 nM) was significantly higher than that for 1,25(OH)2D3 (0.85 ± 0.06 nM; p < 0.05). Our results demonstrate that: (i) EB 1089 has a 50-fold lower affinity than 1,25(OH)2D3 for renal 24-hydroxylase, suggesting that it is more resistant to catabolism by the C-24 oxidation pathway; and (ii) EB 1089 and 1,25(OH)2D3 exhibit tissue-specific differences in vitamin D receptor-mediated responses in vivo that may be ascribed, at least in part, to differences in binding affinities for the vitamin D receptor.
Fibronectin gene expression, synthesis, and accumulation during in vitro differentiation of chicken osteoblasts
Authors: Winnard Robert G. , Gerstenfeld Louis C. , Toma Cyril D. , Dr. Franceschi Renny T.
Published: February 2010

A well-defined chicken osteoblast culture system(18) has been used to examine fibronectin (FN) mRNA levels, synthesis, and accumulation during in vitro differentiation and matrix mineralization. Immunofluorescent staining of cells after 6 or 18 days in culture revealed that FN was initially associated with the cell surface and in partial coalignment with cytoskeletal elements while at the latter time most FN was associated with the extracellular matrix as a ubiquitous fibrillar network. Western blot analysis of total cell-associated proteins also detected FN at all culture times. However, when results were normalized to cellular DNA, FN levels increased until days 12–16 and remained relatively constant thereafter. Similarly, FN synthesis as measured by [35S]-methionine labeling, and immunoprecipitation was greatest in early cultures (culture day 3) and then declined such that synthesis decreased 60% at day 18 and 94% after 24–31 days. FN mRNA levels as measured by Northern blot analysis were well correlated with FN synthesis. These results clearly show that FN is made by primary osteoblasts during their in vitro maturation. In contrast to other osteoblast markers such as alkaline phosphatase, osteocalcin, and osteopontin, whose expression increases as cells differentiate, FN accumulates in the matrix during periods of early cell growth and attachment and then remains proportional to cell number. Results with FN differ from those obtained with collagen which continues to accumulate in the extracellular matrix during osteoblast maturation. These results are consistent with FN being important for the initial attachment of early osteoblasts or osteoblast precursors to the pericellular matrix.
Technical considerations of dual-energy X-ray absorptiometry-based bone mineral measurements for pediatric studies
Authors: Dr. Koo Winston W. K. , Walters Jocelyn , Bush Andrew J.
Published: February 2010

Dual-energy X-ray absorptiometry (DXA) measurements have been shown to provide useful information on bone mineral status in young pediatric subjects. The purpose of this study was to challenge this system under various conditions to determine the clinical and experimental parameters that may be encountered which could interfere with DXA-based bone mineral content (BMC) and bone mineral density (BMD) measurements. Variations in data acquisition, including the covering of step phantom (external calibration standard) with a cotton blanket or partial exclusion of step phantom in the scan field, tissue freezing, or the presence of small nonmetallic objects, did not significantly alter DXA BMC or BMD measurements. By contrast, the presence of movement artifact, radiographic contrast media, and nonmetallic orthopedic casts significantly interfered with DXA BMC and BMD measurements. Variability in operator-dependent analysis of DXA scans occurred with regional analysis of whole body scans for DXA BMC and BMD measurements (average coefficient of variation was 2.9% and 1%, respectively, depending on the region analyzed) but did not affect the total (whole body) result. A minor adjustment in the manual delineation of the step phantom during data analysis may result in almost a 30% difference in DXA BMC and BMD. We conclude that movement artifact, radiographic contrast media, nonmetallic orthopedic cast, and variations in operator-dependent data analysis may interfere with DXA BMC and BMD measurement in young pediatric subjects. Therefore, appropriate care should be taken to reduce or eliminate such interference.
1α,25-dihydroxyvitamin D3 inhibits cell growth and chondrogenesis of a clonal mouse EC cell line, ATDC5
Authors: Akiyama Haruhiko , Hiraki Yuji , Shigeno Chohei , Kohno Hiroaki , Shukunami Chisa , Tsuboyama Tadao , Kasai Ryuichi , Suzuki Fujio , Konishi Junji , Nakamura Takashi
Published: February 2010

Here we report the effects of lα,25-dihydroxyvitamin D3 [1,25(OH)2D3] in vitro on the growth and chondrogenesis of a chondroprogenitor-like clonal mouse EC cell line, 10−10 to 10−7 M ATDC5, 1,25(OH)2D3 inhibited [3H]thymidine incorporation in undifferentiated chondroprogenitor-like ATDC5 cells in time- and dose-dependent manners. 1,25(OH)2D3 suppressed cartilage-nodule formation and the accumulation of cartilage-specific proteoglycan in ATDC5 cells in a dose-dependent manner. The 1,25(OH)2D3-induced inhibition of cartilage-nodule formation was reversible and direct, unrelated to the antiproliferative action of the hormone on the undifferentiated ATDC5 cells. ATDC5 cells even in the precartilaginous stage expressed 4.4 kb vitamin D receptor (VDR) mRNA as assessed by northern blot analysis. The equilibrium saturation binding experiment revealed the presence of a single class of saturable and high-affinity binding sites for 1,25(OH)2D3 in the cytosols. These results provide evidence for the hypothesis that both recruitment and chondrogenesis of chondroprogenitors are negatively regulated by 1,25(OH)2D3 via a VDR-mediated process in vivo.
Aspirin and NSAID use in older women: Effect on bone mineral density and fracture risk
Authors: Bauer Douglas C. , Orwoll Eric S. , Fox Kathleen M. , Vogt Thomas M. , Lane Nancy E. , Hochberg Marc C. , Stone Katie , Nevitt Michael C.
Published: February 2010

Prostaglandin inhibition by aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) may inhibit bone loss and preserve bone mineral density (BMD) in vitro and in animal models. The effect of these agents on BMI) and fracture risk in postmenopausal women is unknown. We assessed the risk factors for osteoporosis and the use of aspirin and NSAIDs in 7786 white women over age 65. Axial BMD was measured at the same time, and fractures were prospectively documented over the subsequent 4 years of follow-up. In age-adjusted analyses, daily use of aspirin or NSAIDs was associated with a 2.3–5.8% increase in BMD of the hip and spine. The relationship persisted even after adjustment for weight, a variety of medications, self-reported arthritis, and for radiographic findings of osteoarthritis, but the multiply adjusted increase in BMD was only 1.0–3.1%. Fracture risk was similar among daily users of aspirin and NSAIDs and nonusers. After adjustment for potential confounders, among daily aspirin users the relative risk of hip fracture was 1.1 (95% confidence interval [CI]: 0.7, 1.6), and among daily NSAID users the risk was 0.9 (CI: 0.6, 1.4). Considering all nonspine fractures together, the risk among aspirin users was 1.0 (CI: 0.8. 1.2), and among NSAID users the risk was also 1.0 (CI; 0.8, 1.2). Regular use of aspirin or NSAIDs may have a modest beneficial effect on BMD in postmenopausal women. This effect persists after adjustment for obesity and the presence of osteoarthritis. However, among women who take aspirin or NSAIDs regularly, there is no clinically significant protective effect on the subsequent risk of fractures.