bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Tower Climbing Exercise on Bone Mass, Strength, and Turnover in Growing Rats
Authors: Notomi Takuya , Okimoto Nobukazu , Okazaki Yuichi , Tanaka Yuri , Nakamura Toshitaka , Suzuki Masashige 
Published: April 2006

Abstract
To determine the effects of tower climbing exercise on mass, strength, and local turnover of bone, 50 Sprague-Dawley rats, 10 weeks of age, were assigned to five groups: a baseline control and two groups of sedentary and exercise rats. Rats voluntarily climbed the 200-cm tower to drink water from the bottle set at the top of it. In 4 weeks, the trabecular bone formation rate (BFR/bone surface [BS]), bone volume (BV/TV), and trabecular thickness (Tb.Th) of both the lumbar vertebra and tibia and the bone mineral density (BMD) of the tibia increased, while the osteoclast surface (Oc.S) decreased. The parameter values in the midfemur, such as the total cross-sectional area, the moment of inertia, the periosteal mineralizing surface (MS/BS), mineral apposition rate (MAR), BFR/BS, and bending load increased, while the endosteal MAR decreased. In 8 weeks, the increases in the bone mineral content (BMC), BMD of the femur and tibia, and the bending load values of the femur were significant, but the climbing exercise did not increase BMC, BMD, or the compression load of the lumbar vertebra. Although the periosteal MS/BS, MAR, and BFR/BS increased, the endosteal MS/BS, MAR, and BFR/BS decreased. These results show that climbing exercise has a beneficial effect on the femoral cortex and tibia trabecular, rather than the vertebral trabecular. In the midfemur, effects on bone formation are site specific, supporting accelerated cortical drift by mechanical stimulation.
Atherogenic High-Fat Diet Reduces Bone Mineralization in Mice
Authors: Parhami Farhad , Tintut Yin , Beamer Wesley G. , Gharavi Nima , Goodman William , Demer Linda L. 
Published: April 2006

Abstract
The epidemiological correlation between osteoporosis and cardiovascular disease is independent of age, but the basis for this correlation is unknown. We previously found that atherogenic oxidized lipids inhibit osteoblastic differentiation in vitro and ex vivo, suggesting that an atherogenic diet may contribute to both diseases. In this study, effects of an atherogenic high-fat diet versus control chow diet on bone were tested in two strains of mice with genetically different susceptibility to atherosclerosis and lipid oxidation. After 4 months and 7 months on the diets, mineral content and density were measured in excised femurs and lumbar vertebrae using peripheral quantitative computed tomographic (pQCT) scanning. In addition, expression of osteocalcin in marrow isolated from the mice after 4 months on the diets was examined. After 7 months, femoral mineral content in C57BL/6 atherosclerosis-susceptible mice on the high-fat diet was 43% lower (0.73 ± 0.09 mg vs. 1.28 ± 0.42 mg; p = 0.008), and mineral density was 15% lower compared with mice on the chow diet. Smaller deficits were observed after 4 months. Vertebral mineral content also was lower in the fat-fed C57BL/6 mice. These changes in the atherosclerosis-resistant, C3H/HeJ mice were smaller and mostly not significant. Osteocalcin expression was reduced in the marrow of high fat-fed C57BL/6 mice. These findings suggest that an atherogenic diet inhibits bone formation by blocking differentiation of osteoblast progenitor cells.
Familial Paget's Disease of Bone: Nonlinkage to the PDB1 and PDB2 Loci on Chromosomes 6p and 18q in a Large Pedigree
Authors: Good David , Busfield Frances , Duffy David , Lovelock Paul K. , Kesting Janine B. , Cameron Donald P. , Shaw Joanne T. E. 
Published: April 2006

Abstract
Paget's disease of bone is a common condition characterized by bone pain, deformity, pathological fracture, and an increased incidence of osteosarcoma. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis remains largely unknown. Susceptibility loci for Paget's disease of bone have been mapped to chromosome 6p21.3 (PDB1) and 18q21.1-q22 (PDB2) in different pedigrees. We have identified a large pedigree of over 250 individuals with 49 informative individuals affected with Paget's disease of bone; 31 of whom are available for genotypic analysis. The disease is inherited as an autosomal dominant trait in the pedigree with high penetrance by the sixth decade. Linkage analysis has been performed with markers at PDB1; these data show significant exclusion of linkage with log10 of the odds ratio (LOD) scores &lt; −2 in this region. Linkage analysis of microsatellite markers from the PDB2 region has excluded linkage with this region, with a 30 cM exclusion region (LOD score &lt; −2.0) centered on D18S42. These data confirm the genetic heterogeneity of Paget's disease of bone. Our hypothesis is that a novel susceptibility gene relevant to the pathogenesis of Paget's disease of bone lies elsewhere in the genome in the affected members of this pedigree and will be identified using a microsatellite genomewide scan followed by positional cloning.
Newly Established Assay Method for 25-Hydroxyvitamin D3 24-Hydroxylase Revealed Much Lower Km for 25-Hydroxyvitamin D3 than for 1α,25-Dihydroxyvitamin D3
Authors: Taniguchi Tomotaka , Eto Tada-Aki , Shiotsuki Hironori , Sueta Hideto , Higashi Shushi , Iwamura Takeshi , Okuda Kyu-Ichiro , Setoguchi Toshiaki 
Published: April 2006

Abstract
An accurate assay method of 25-hydroxyvitamin D3 24-hydroxylase (24-hydroxylase) was established. Kidney mitochondria prepared from vitamin D-replete rats were treated with polyoxyethylenesorbitan monolaurate. The solubilized suspension was ultracentrifuged at 100,000g for 60 minutes and an aliquot of the supernatant was incubated under the saturating concentrations of substrate NADPH and the mitochondrial-type electron transferring proteins, adrenodoxin and NADPH-adrenodoxin reductase. Products were analyzed by high-performance liquid chromatography (HPLC) monitoring effluents at a wavelength of 265 nm. The maximal velocity of the enzyme in vitamin D-replete rats was 400 pmol/minute per mg of protein, which was considerably higher than those reported by previous authors who used intact kidney mitochondria as the enzyme source. In applying the new assay method, an interesting property was found; Michaelis constant of 24-hydroxylase for 25-hydroxyvitamin D3 [25(OH)D3] was 0.6 μM, which was 35-fold lower than that for 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] which was 20.9 μM. This fact indicates that affinity of the enzyme to 25(OH)D3 is 35-fold higher than that to 1α,25(OH)2D3. These data suggest that 25(OH)D3 is the preferred substrate to 1α,25(OH)2D3.
Phenotypic Characterization of Mice Bred for High and Low Peak Bone Mass
Authors: Klein Robert F. , Shea Marie , Gunness Michele E. , Pelz Geoffrey B. , Belknap John K. , Orwoll Eric S. 
Published: April 2006

Abstract
In humans, peak bone mineral density (BMD) is a highly heritable trait and a strong determinant of subsequent osteoporotic fracture risk. To identify the genetic factors responsible for variation in peak BMD, investigators have turned to animal models. In this study we examined the heritability of BMD acquisition and characterized differences in skeletal geometry, histomorphometry, and biomechanical competence between two lines of mice artificially selected for extremes of peak whole body BMD. F2 progeny from a cross between C57BL/6 and DBA/2 inbred strains was used as the foundation population to develop lines selected for either high or low BMD. Whole body BMD was measured by dual-energy X-ray absorptiometry (DXA). By the third generation of selection, highest-scoring BMD (HiBMD) mice exhibited 14% greater peak BMD than lowest-scoring BMD (LoBMD) mice. The mean realized heritability of peak BMD was 36%. Femoral shaft cortical area and thickness and vertebral cancellous bone volume (BV) were significantly greater (16–30%) in the HiBMD line compared with the LoBMD line. Mean cancellous bone formation rates (BFRs) were 35% lower in HiBMD mice compared with LoBMD mice. Failure load and stiffness in the femoral shaft, femoral neck, and L6 vertebrae were all substantially greater (by 25–190%) in HiBMD mice. Thus, these divergently selected murine lines serve to illustrate some of the means by which genetic mechanisms can affect skeletal structure and remodeling. Identification of the individual genes influencing peak BMD in this experimental system will likely reveal some of the genetic determinants of overall bone strength.
Effects of a New Selective Estrogen Receptor Modulator (MDL 103,323) on Cancellous and Cortical Bone in Ovariectomized Ewes: A Biochemical, Histomorphometric, and Densitometric Study
Authors: Chavassieux Pascale , Garnero Patrick , Duboeuf Francois , Vergnaud Philippe , Brunner-Ferber Francoise , Delmas Pierre D. , Meunier Pierre J. 
Published: April 2006

Abstract
The aims of this study performed in ewes were: (1) to confirm in this animal model the effects on bone of ovariectomy (OVX) alone or associated with Lentaron (L), a potent peripheral aromatase inhibitor, used to amplify the effects of OVX and (2) to evaluate the effects of a new selective estrogen receptor modulator (SERM; MDL 103,323) on bone remodeling. Thirty-nine old ewes were divided into five groups: sham (n = 7); OVX (n = 8); OVX + L (n = 8); OVX + L + MDL; 0.1 mg/kg per day (n = 8); and OVX + L + MDL 1 mg/kg per day (n = 8). The animals were treated for 6 months. Biochemical markers of bone turnover (urinary excretion of type 1 collagen C-telopeptide [CTX], serum osteocalcin [OC], and bone alkaline phosphatase [BAP]) were measured each month. Bone biopsy specimens were taken at the beginning and after death at the end of the experiment. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) on the lumbar spine and femur. OVX induced a significant increase in biochemical markers. This effect was the highest after 3 months for CTX (+156% vs. sham) and after 4 months for OC and BAP (+74% and +53% vs. sham, respectively). L tended to amplify the effect of OVX on OC and BAP. OVX induced significant increases in the porosity, eroded, and osteoid surfaces in cortical bone but no effect was observed in cancellous bone. MDL treatment reduced the bone turnover as assessed by bone markers, which returned to sham levels as well as histomorphometry both in cortical and in cancellous bone. Cancellous osteoid thickness decreased by 27% (p &lt; 0.05), mineralizing perimeter by 81% (p &lt; 0.05), and activation frequency by 84% (p &lt; 0.02) versus OVX + L. Femoral and spinal BMD were increased by MDL and tended to return to the sham values. The effects of OVX on bone turnover were different on cortical and cancellous bone. These effects on cortical bone were reflected by changes in biochemical markers. MDL markedly reduces bone turnover and increases BMD suggesting that this new agent may prevent postmenopausal bone loss.
Comparison of Trabecular Bone Microarchitecture and Remodeling in Glucocorticoid-Induced and Postmenopausal Osteoporosis
Authors: Carbonare L. Dalle , Arlot M. E. , Chavassieux P. M. , Roux J. P. , Portero N. R. , Meunier P. J. 
Published: April 2006

Abstract
Long-term treatment with glucocorticoids (GCs) leads to a rapid bone loss and to a greater risk of fractures. To evaluate the specific effects of this treatment on cancellous bone remodeling, structure, and microarchitecture, we compared 22 transiliac biopsy specimens taken in postmenopausal women (65 ± 6 years) receiving GCs (≥7.5 mg/day, for at least 6 months) and 22 biopsy specimens taken in age-matched women with postmenopausal osteoporosis (PMOP), all untreated and having either at least one vertebral fracture or a T score &lt; −2.5 SD. On these biopsy specimens, we measured static and dynamic parameters reflecting trabecular bone formation and resorption. Also, we performed the strut analysis and evaluated the trabecular bone pattern factor (TBPf), Euler number/tissue volume (E/TV), interconnectivity index (ICI), and marrow star volume (MaSV). Glucocorticoid-induced osteoporosis (GIOP), when compared with PMOP, was characterized by lower bone volume (BV/TV), trabecular thickness (Tb.Th), wall thickness (W.Th), osteoid thickness (O.Th), bone formation rate/bone surface (BFR/BS), adjusted mineral apposition rate/bone surface (Aj.AR/BS), and higher ICI and resorption parameters. After adjustment for BV/TV, the W.Th remained significantly lower in GIOP (p &lt; 0.0001). The active formation period [FP(a+)] was not different. Patients with GIOP were divided into two groups: high cumulative dose GCs (HGCs; 23.7 ± 9.7 g) and low cumulative dose GCs (LGCs; 2.7 ± 1.2 g). HGC when compared with LGC was characterized by lower W.Th (p &lt; 0.05), BV/TV (p &lt; 0.001), Tb.Th (p &lt; 0.05), trabecular number (Tb.N; p &lt; 0.05), FP(a+) (p &lt; 0.05), and nodes (p &lt; 0.05), and higher E/TV (p &lt; 0.05), ICI (p &lt; 0.005), and TBPf (p &lt; 0.05). When HGC was compared with PMOP, the results were similar except for the MaSV, which was significantly higher (p &lt; 0.005). In summary, GIOP was characterized by lower formation and higher resorption than in PMOP, already present after LGC. With HGCs, these changes were associated with a more dramatic bone loss caused by a major loss of trabecular connectivity.
The Loss of Smad3 Results in a Lower Rate of Bone Formation and Osteopenia Through Dysregulation of Osteoblast Differentiation and Apoptosis
Authors: Borton Anita J. , Frederick Joshua P. , Datto Michael B. , Wang Xiao-Fan , Weinstein Robert S. 
Published: April 2006

Abstract
Smad3 is a well-characterized intracellular effector of the transforming growth factor β (TGF-β) signaling pathway and was implicated recently in the potentiation of vitamin D receptor (VDR)-mediated signaling. Given that both TGF-β and vitamin D are important regulators of bone remodeling, it is expected that Smad3 plays an integral role in normal maintenance of bone. However, the exact mechanisms by which Smad3 functions in bone remodeling are unknown. Here, we show that mice with targeted deletion of Smad3 are osteopenic with less cortical and cancellous bone compared with wild-type littermates. Decreases in bone mineral density (BMD) in Smad3 null mice reflect the inability of osteoblasts to balance osteoclast activity, although osteoclast numbers are normal and vitamin D mediated serum calcium homeostasis is maintained. The osteopenia of Smad3 null mice is attributed to a decreased rate of bone formation associated with increased osteocyte number and apoptosis. These findings are supported by studies with isolated primary osteoblasts that show TGF-β can no longer inhibit the differentiation of osteoblasts in the absence of Smad3; yet, TGF-β-stimulated proliferation remains intact. Together these data support a model that a loss of Smad3 increases the osteocyte fate of the osteoblast and decreases the duration of osteoblast function by shortening lifespan, ultimately resulting in osteopenia.
Focal Adhesion Kinase Activity Is Required for Bone Morphogenetic Protein—Smad1 Signaling and Osteoblastic Differentiation in Murine MC3T3-E1 Cells
Authors: Tamura Yasuhiro , Takeuchi Yasuhiro , Suzawa Miyuki , Fukumoto Seiji , Kato Mitsuyasu , Miyazono Kohei , Fujita Toshiro 
Published: April 2006

Abstract
Cell-matrix interactions via integrins are essential for osteoblastic differentiation. We have shown that signals activated by aggregation of α2β1-integrin with type I collagen are involved in the differentiation of osteoblastic MC3T3-E1 cells. Focal adhesion kinase (FAK) is an immediate downstream signal of the β1-integrin, and inactivation of FAK has been shown to disrupt osteoblastic differentiation. To elucidate roles of FAK in osteoblastic cells, we examined MC3T3-E1 cells stably expressing antisense FAK (asFAK) messenger RNA (mRNA). Alkaline phosphatase (ALP) activity, an osteoblastic marker, did not increase in asFAK cells with a long-term culture until 21 days or in response to bone morphogenetic protein 2 (BMP-2). Treatment with BMP-2 also failed to stimulate the expression of osteocalcin in asFAK cells. In control MC3T3-E1 cells, BMP-2 induced translocation of Smad1 into nuclei to stimulate transcriptional activity of the Smad6 promoter gene that contains a Smad1 response element. In contrast, BMP-2 failed to increase transcriptional activity of Smad6 promoter gene in asFAK cells, although it induced nuclear translocation of Smad1. These results indicate that FAK was involved in Smad1-dependent transcriptional activity but not in nuclear translocation of Smad1 in osteoblastic cells. Hence, FAK activation by integrins might converge transcriptional activation by BMP of its target genes in osteoblastic cells. These observations suggest that FAK activity is essential for BMP-Smad signaling to stimulate osteoblastic differentiation.
Transforming Growth Factor β Affects Osteoclast Differentiation via Direct and Indirect Actions
Authors: Quinn Julian M. W. , Itoh Kanami , Udagawa Nobuyuki , Häusler Karl , Yasuda Hisataka , Shima Nobuyuki , Mizuno Atsuko , Higashio Kanji , Takahashi Naoyuki , Suda Tatsuo , Martin T. John , Gillespie Matthew T. 
Published: April 2006

Abstract
Transforming growth factor β (TGF-β) is abundant in bone and has complex effects on osteolysis, with both positive and negative effects on osteoclast differentiation, suggesting that it acts via more than one mechanism. Osteoclastogenesis is determined primarily by osteoblast (OB) expression of the tumor necrosis factor (TNF)-related molecule receptor activator of NF-κB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG), which are increased and decreased, respectively, by osteolytic factors. A RANKL-independent osteoclastogenic mechanism mediated by TNF-α has also been shown. Therefore, we investigated TGF-β effects on osteoclast formation in culture systems in which osteoclastogenic stimulus is dependent on OBs and culture systems where it was provided by exogenously added RANKL or TNF-α. Both OPG and TGF-β inhibited osteoclast formation in hemopoietic cell/OB cocultures, but the kinetics of their action differed. TGF-β also inhibited osteoclastogenesis in cocultures of cells derived from OPG null (opg−/−) mice. TGF-β strongly decreased RANKL messenger RNA (mRNA) expression in cultured osteoblasts, and addition of exogenous RANKL to TGFβ-inhibited cocultures of opg−/− cells partially restored osteoclastogenesis. Combined, these data indicate that the inhibitory actions of TGF-β were mediated mainly by decreased OB production of RANKL. In contrast, in the absence of OBs, TGF-β greatly increased osteoclast formation in recombinant RANKL- or TNF-α-stimulated cultures of hemopoietic cells or RAW 264.7 macrophage-like cells to levels several-fold greater than attainable by maximal stimulation by RANKL or TNF-α. These data suggest that TGF-β may increase osteoclast formation via action on osteoclast precursors. Therefore, although RANKL (or TNF-α) is essential for osteoclast formation, factors such as TGF-β may powerfully modify these osteoclastogenic stimuli. Such actions may be critical to the control of physiological and pathophysiological osteolysis.
Antisense Oligodeoxynucleotide Evidence That a Unique Osteoclastic Protein-Tyrosine Phosphatase Is Essential for Osteoclastic Resorption
Authors: Suhr Sung Min , Pamula Sujatha , Baylink David J. , Lau K.-H. William 
Published: April 2006

Abstract
This study tested the hypothesis that a unique osteoclastic transmembrane protein tyrosine phosphatase (PTP-oc) is involved in osteoclastic resorption by determining whether suppression of PTP-oc expression with a specific phosphorothioated 20-mer PTP-oc antisense oligodeoxynucleotide (oligo) would inhibit basal, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-stimulated, and PTH-stimulated osteoclastic resorption. Treatment of rabbit osteoclasts with 1 μM of the antisense oligo for up to 4 days showed a time-dependent reduction in PTP-oc protein level, indicating that this PTP-oc antisense oligo was effective. To assess the effect of PTP-oc antisense oligo on osteoclastic resorption, rabbit osteoclasts were pretreated for 3 days with 1 μM of the antisense, a scramble oligo, or vehicle, respectively, followed by a 3-day treatment with vehicle, 10 nM of 1,25(OH)2D3, or 10 nM of parathyroid hormone (PTH). 1,25(OH)2D3 and PTH each alone increased PTP-oc cellular level and stimulated resorptive activity of rabbit osteoclasts. The antisense oligo treatment, but not the scramble oligo, decreased the basal and the stimulated resorption activity and reduced the PTP-oc protein level. Treatment with the PTP-oc antisense oligo, but not the scramble oligo, also markedly increased the Y527 phosphorylation level of c-src in rabbit osteoclasts. In conclusion, these results provide the first antisense oligo evidence that PTP-oc plays an essential role in osteoclastic resorption.
Spectroscopic Characterization of Collagen Cross-Links in Bone
Authors: Paschalis E. P. , Verdelis K. , Doty S. B. , Boskey A. L. , Mendelsohn R. , Yamauchi M. 
Published: April 2006

Abstract
Collagen is the most abundant protein of the organic matrix in mineralizing tissues. One of its most critical properties is its cross-linking pattern. The intermolecular cross-linking provides the fibrillar matrices with mechanical properties such as tensile strength and viscoelasticity. In this study, Fourier transform infrared (FTIR) spectroscopy and FTIR imaging (FTIRI) analyses were performed in a series of biochemically characterized samples including purified collagen cross-linked peptides, demineralized bovine bone collagen from animals of different ages, collagen from vitamin B6-deficient chick homogenized bone and their age- and sex-matched controls, and histologically stained thin sections from normal human iliac crest biopsy specimens. One region of the FTIR spectrum of particular interest (the amide I spectral region) was resolved into its underlying components. Of these components, the relative percent area ratio of two subbands at ∼1660 cm−1 and ∼1690 cm−1 was related to collagen cross-links that are abundant in mineralized tissues (i.e., pyridinoline [Pyr] and dehydrodihydroxylysinonorleucine [deH-DHLNL]). This study shows that it is feasible to monitor Pyr and DHLNL collagen cross-links spatial distribution in mineralized tissues. The spectroscopic parameter established in this study may be used in FTIRI analyses, thus enabling the calculation of relative Pyr/DHLNL amounts in thin (∼5 μm) calcified tissue sections with a spatial resolution of ∼7 μm.