bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Cyclosporine on Osteoclast Activity: Inhibition of Calcineurin Activity With Minimal Effects on Bone Resorption and Acid Transport Activity
Authors: Williams John P , Mckenna Margaret A , Thames Allyn M , McDONALD Jay M 
Published: April 2006

Abstract
Cyclosporine results in rapid and profound bone loss in transplant patients, an effect ascribed to osteoclasts. Cyclosporine, complexed with the appropriate immunophilin, inhibits calcineurin (the calcium/calmodulin dependent serine/threonine phosphatase) activity. We tested the hypothesis that cyclosporine inhibits calcineurin activity in osteoclasts, resulting in stimulation of osteoclast activity. We compared the effects of cyclosporine A and the calmodulin antagonist, tamoxifen, on bone resorption by avian osteoclasts. Tamoxifen inhibits bone resorption ∼60%, whereas cyclosporine A only inhibited bone resorption 12%. One-hour treatment with 100 nM cyclosporine inhibited osteoclast calcineurin activity 70% in whole cell lysates, whereas 10 μM tamoxifen only inhibited calcineurin activity 25%. We compared the effects of cyclosporine A and tamoxifen on acid transport activity in isolated membrane vesicles and in isolated membrane vesicles obtained from osteoclasts treated with cyclosporine A or tamoxifen under conditions that inhibit calcineurin activity. Direct addition of cyclosporine A in the acid transport assay, or pretreatment of cells with cyclosporine A followed by membrane isolation, had no effect on acid transport activity in membrane vesicles. In contrast, direct addition of tamoxifen to membranes inhibits acid transport activity, an effect that can be prevented by addition of exogenous calmodulin. Furthermore, acid transport activity was also inhibited in membrane vesicles isolated from cells treated with tamoxifen. In conclusion, cyclosporine A inhibits osteoclast calcineurin activity; however, calcineurin inhibition does not correspond to a significant effect on acid transport activity in isolated membrane vesicles or bone resorption by osteoclasts.
Zoledronic Acid Treatment of 5T2MM-Bearing Mice Inhibits the Development of Myeloma Bone Disease: Evidence for Decreased Osteolysis, Tumor Burden and Angiogenesis, and Increased Survival
Authors: Croucher Peter I , De Raeve Hendrik , Perry Mark J , Hijzen Anja , Shipman Claire M , Lippitt Jennifer , Green Jonathan , Van Marck Eric , Van Camp Ben , Vanderkerken Karin 
Published: April 2006

Abstract
Multiple myeloma is characterized by the growth of plasma cells in the bone marrow and the development of osteolytic bone disease. Myeloma cells are found closely associated with bone, and targeting this environment may therefore affect both the bone disease and the growth of myeloma cells. We have investigated the effect of the potent bisphosphonate, zoledronic acid, on the development of bone disease, tumor burden, and disease-free survival in the 5T2MM model of myeloma. 5T2MM murine myeloma cells were injected intravenously into C57BL/KaLwRij mice. After 8 weeks, all animals had a paraprotein. Animals were treated with zoledronic acid (120 μg/kg, subcutaneously, twice weekly) or vehicle, from the time of tumor cell injection or from paraprotein detection for 12 or 4 weeks, respectively. All animals injected with tumor cells developed osteolytic lesions, a decrease in cancellous bone volume, an increase in osteoclast perimeter, and a decrease in bone mineral density. Zoledronic acid prevented the formation of lesions, prevented cancellous bone loss and loss of bone mineral density, and reduced osteoclast perimeter. Zoledronic acid also decreased paraprotein concentration, decreased tumor burden, and reduced angiogenesis. In separate experiments, Kaplan-Meier analysis demonstrated a significant increase in survival after treatment with zoledronic acid when compared with control (47 vs. 35 days). A single dose of zoledronic acid was also shown to be effective in preventing the development of osteolytic bone disease. These data show that zoledronic acid is able to prevent the development of osteolytic bone disease, decrease tumor burden in bone, and increase survival in a model of established myeloma.
S100A4: A Novel Negative Regulator of Mineralization and Osteoblast Differentiation
Authors: Duarte Wagner R , Shibata Tatsuya , Takenaga Keizo , Takahashi Etsuko , Kubota Kaori , Ohya Keiichi , Ishikawa Isao , Yamauchi Mitsuo , Kasugai Shohei 
Published: April 2006

Abstract
S100A4 is an intracellular calcium-binding protein expressed by osteoblastic cells. However, its roles in bone physiology are unknown. Because before matrix mineralization, its expression is markedly diminished, we hypothesized that S100A4 negatively regulates the mineralization process. In this study, we investigated the effects of the inhibition of S100A4 synthesis on osteoblast differentiation and in vitro mineralized nodule formation. Inhibition of S100A4 synthesis was achieved by an antisense approach in the mouse osteoblastic cell line MC3T3-E1. Cell clones that synthesized low levels of S100A4 (AS clones) produced markedly increased number of mineralized nodules at much earlier stages in comparison with controls as demonstrated by Alizarin red S and von Kossa staining. The expression of type I collagen (COLI) and osteopontin (OPN) increased in AS clones compared with controls. Bone sialoprotein (BSP) and osteocalcin (OCN), molecules associated with mineralization and markers for mature osteoblastic phenotype, were expressed in AS clones before their detection in controls. Because S100A4 was not localized in the nucleus of MC3T3-E1 cells and AS clones, it is unlikely that S100A4 directly regulates the expression of these genes. Moreover, the expression of Cbfa1/Osf-2 and Osx, transcription factors necessary for the expression of osteoblast-associated genes, remained unchanged in AS clones, indicating that S100A4 may be downstream to these transcription factors. These findings indicate that S100A4 is a novel negative regulator of matrix mineralization likely by modulating the process of osteoblast differentiation.
Enhancement of Fibronectin Synthesis and Fibrillogenesis by BMP-4 in Cultured Rat Osteoblast
Authors: Tang Chih-Hsin , Yang Rong-Sen , Liou Houng-Chi , Fu Wen-Mei 
Published: April 2006

Abstract
The skeletal extracellular matrix produced by osteoblasts contains the glycoprotein fibronectin (Fn), which regulates the adhesion, differentiation, and function of osteoblasts. Fn fibrillogenesis is involved in the process of bone mineralization. Bone morphogenetic proteins (BMPs) can be isolated from organic bone matrix and are able to initiate de novo cartilage and bone formation. In this study, the effect of BMP-4 on Fn fibrillogenesis in cultured rat osteoblasts was examined. BMP-4 enhanced Fn synthesis and extracellular Fn assembly in primary cultured osteoblasts. In addition, the extracellular assembly of Fn from exogenously applied soluble human Fn was also increased by BMP-4. It has been reported that α5β1 integrin is related to Fn fibrillogenesis. The synthesis of both α5 and β1 integrins was upregulated by BMP-4. Immunocytochemistry showed that the clustering of α5 and β1 integrins was also increased by BMP-4. BMP-4 increased fibril formation of Fn and the adhesion of osteoblasts onto Fn matrix, which was inhibited by disintegrin triflavin and Gly-Arg-Gly-Asp-Ser (GRGDS) peptide. Phosphorylation of extracellular signal-regulated kinase (ERK) and focal adhesion kinase (FAK) was increased by BMP-4. Enhancement of extracellular Fn fibrillogenesis and the mRNA expression of β1 integrin by BMP-4 were inhibited by ERK kinase (MEK) inhibitor PD98059. These results suggest that the enhancement of extracellular Fn fibrillogenesis by BMP-4 in cultured osteoblasts is related to the increase of the synthesis of Fn and clustering of α5 and β1 integrins. ERK is involved in the signaling pathway of BMP-4 in regulating Fn fibrillogenesis in osteoblasts.
Long-Term Treatment of Incadronate Disodium Accumulates Microdamage but Improves the Trabecular Bone Microarchitecture in Dog Vertebra
Authors: Komatsubara Satoshi , Mori Satoshi , Mashiba Tasuku , Ito Masako , Li Jiliang , Kaji Yoshio , Akiyama Tomoyuki , Miyamoto Kensaku , Cao Yongping , Kawanishi Jun , Norimatsu Hiromichi 
Published: April 2006

Abstract
This study aimed to investigate the effect of long-term suppression of bone resorption by bisphosphonate on the microstructure, accumulation of microdamage, and mechanical properties of trabecular bone. Twenty-nine 1-year-old beagles (15 males, 14 females) were divided into three groups. The control group (CNT) was treated daily with vehicle, and the other two groups were treated with incadronate at a dose of 0.3 mg/kg/day (LOW) or 0.6 mg/kg/day (HIGH) orally for 3 years. After death, the second thoracic vertebra was scanned with microcomputed tomography (micro-CT) and assigned to histomorphometric and microdamage measurements. The fourth lumbar vertebra was mechanically tested by compression. Incadronate concentration in bone was measured in the 11th thoracic vertebra. Micro-CT analysis demonstrated a platelike trabecular structure and increased concave surface of trabeculae in the thoracic vertebra of incadronate-treated groups. Three-year incadronate treatment significantly suppressed trabecular activation rates by 56% in LOW and 67% in HIGH without impairment of mineralization, and increased microdamage accumulation in both incadronate-treated groups. Trabecular bone volume was significantly increased in both LOW and HIGH groups, and vertebral strength was significantly increased in the HIGH group compared with the CNT group. However, intrinsic material properties such as normalized ultimate stress and normalized toughness were reduced in incadronate-treated groups. Incadronate concentration in bone was dose-dependent. This study suggests that long-term suppression of bone remodeling increases microdamage accumulation, but this is not necessarily associated with vertebral fragility because of compensated increase of bone mass and improved microarchitecture.
Suture Growth Modulated by the Oscillatory Component of Micromechanical Strain
Authors: Kopher Ross A , Mao Jeremy J 
Published: April 2006

Abstract
Sutures are fibrous connective tissue articulations between intramembranous craniofacial bones. Sutures are composed of fibroblastic cells with their matrices in the center and osteogenic cells in the periphery producing a matrix that is mineralized during skeletal growth. Whether oscillatory forces stimulate sutural growth is unknown. In the present work, we applied static and cyclic forces with the same peak magnitude of 5N to the maxilla in growing rabbits and quantified (1) acute in vivo sutural bone strain responses and (2) chronic growth responses in the premaxillomaxillary suture (PMS) and nasofrontal suture (NFS). Bone strain recordings showed that the waveforms of static force and 1-Hz cyclic force were expressed as corresponding static and cyclic sutural strain patterns in both the PMS and NFS, with the mean peak PMS strain (−1451 ± 137 με for the cyclic and −1572 ± 138 με for the static) approximately 10-fold higher than the mean peak NFS strain (124 ± 9 με for the cyclic and 134 ± 9 με for the static). Strain polarity was the opposite: compressive for the PMS but tensile for the NFS. However, on application of repetitive 5N cyclic and static forces in vivo for 10 minutes/day over 12 days, cyclic loading induced significantly greater sutural widths for the compressed PMS (95.1 ± 8.3 μm) than sham control (69.8 ± 8.2 μm) and static loading (58.9 ± 2.8 μm; p &lt; 0.01). Interestingly, the same trend was true for the NFS under tensile strain: significantly greater sutural width for cyclic loading (267.4 ± 64.2 μm) than sham control (196.0 ± 10.1 μm) and static loading (169.9 ± 11.4 μm). Cell counting in 110 × 110 μm grids laid over sutures disclosed significantly more sutural cells on repetitive cyclic loading than sham control and static loading (p &lt; 0.05) for both the PMS and NFS. Fluorescent labeling of newly formed sutural bone demonstrated more osteogenesis on cyclic loading in comparison with sham control and static loading. Thus, the oscillatory component of cyclic force or more precisely the resulting cyclic strain experienced in sutures is a potent stimulus for sutural growth. The increased sutural growth by cyclic mechanical strain in the tensed NFS and compressed PMS suggests that both microscale tension and compression induce anabolic sutural growth response.
Cytokines, Osteoprotegerin, and RANKL In Vitro and Histomorphometric Indices of Bone Turnover in Patients With Different Bone Diseases
Authors: Siggelkow Heide , Eidner Thorsten , Lehmann Gabriele , Viereck Volker , Raddatz Dirk , Munzel Ullrich , Hein Gert , Hüfner Michael 
Published: April 2006

Abstract
Cytokines are supposed to play an essential role in the regulation of the bone metabolic unit. However, information on cytokine production of primary human osteoblasts from patients with metabolic bone disease is scarce, and few attempts have been made to correlate such data to histomorphometric parameters of individual patients. We investigated 11 patients with metabolic bone disease referred to our outpatient department for bone biopsy and analyzed interleukin (IL)-1, IL-6, and TNF-α protein release and gene expression in primary osteoblast cultures. Compared with four controls, five patients showed normal cytokine protein release, whereas six patients showed much higher levels of interleukin-6 (26-fold) and TNF-α (84-fold). All three cytokines were strongly correlated concerning gene expression and/or protein levels (r = 0.72–0.96). Histomorphometric analysis of the bone samples showed that eroded surface (ES/BS) as a parameter of bone resorption was significantly associated with TNF-α. In addition, RANKL gene expression was positively associated with ES/BS and osteoclast surface (Oc.S/BS). Finally, the formation parameters osteoid volume and osteoid surface were negatively associated with TNF-α. In conclusion, in an in vitro-ex vivo model of bone cells obtained from a group of 11 patients with different forms of metabolic bone disease, cytokine release in conditioned medium was significantly associated with bone resorption and bone formation, as quantified by histomorphometry. TNF-α seemed to be the more important cytokine; its effect on bone resorption could be mediated by RANKL.
The Bone Gain Induced by Exercise in Puberty Is Not Preserved Through a Virtually Life-Long Deconditioning: A Randomized Controlled Experimental Study in Male Rats
Authors: Pajamäki Ilari , Kannus Pekka , Vuohelainen Tuomo , Sievänen Harri , Tuukkanen Juha , Järvinen Markku , Järvinen Teppo LN 
Published: April 2006

Abstract
To investigate the controversial issue whether exercise-induced positive effects on bone can be maintained after cessation of exercise, 100 5-week-old male Sprague-Dawley rats were used to assess the effects of long-term exercise (EX, treadmill running) and subsequent deconditioning (DC, free cage activity) on the femoral neck and femoral midshaft. At entry, the rats were randomly assigned into eight groups: four control groups (C14, C28, C42, and C56), and four exercise groups (EX, EX + DC14, EX + DC28, and EX + DC42). Rats in the exercise groups were first subjected to a 14-week period of progressively intensifying running, after which the rats of group EX were killed and the remaining exercise groups (EX + DC14, EX + DC28, and EX + DC42) were allowed to move freely in their cages for a subsequent deconditioning period of 14, 28, or 42 weeks, whereas control rats were kept free in their cages for the entire study period (0–56 weeks) and killed with their respective exercise group. At each time point, a comprehensive analysis of the femoral neck and midshaft characteristics (peripheral quantitative computed tomography analysis and fracture load [Fmax]) was performed. In comparison with their age-matched controls, 14 weeks of treadmill training resulted in significant (p &lt; 0.05) increases in all measured femoral neck parameters of the growing male rats (i.e., +25% in total cross-sectional area [tCSA], +28% in total bone mineral content [tBMC], +11% in total bone mineral density [tBMD], and +30% in Fmax). On the contrary, no exercise-induced positive effects were seen in femoral midshaft. The exercise-induced benefits in the femoral neck were partially maintained during the deconditioning period of 14 weeks, the tCSA being +17%, tBMC +18% (both p &lt; 0.05), and the Fmax +11% (p = 0.066) higher in the exercised group than control group. However, after 42 weeks of deconditioning, these benefits were eventually lost. In conclusion, exercise through the period of the fastest skeletal growth results in significant improvements in size, mineral mass, and strength of the femoral neck of male rats. However, these exercise-induced bone benefits are eventually lost if exercise is completely ceased, and thus, continued training is probably needed to maintain the positive effects of youth exercise into adulthood. Further studies should focus on assessing the minimal level of activity needed to maintain the exercise-induced bone gains.
Influence of Environmental Cadmium Exposure on Forearm Bone Density
Authors: Wang Hongfu , Zhu Guoying , Shi Yongxin , Weng Shifang , Jin Taiyi , Kong Qinghu , Nordberg Gunnar F 
Published: April 2006

Abstract
Cadmium may have both direct and indirect effects on bone turnover. It is nephrotoxic and can interfere with vitamin D metabolism. Such perturbation may result in osteoporosis and osteomalacia. In this study, a total of 790 persons (302 males and 488 females) participated; they were all over 35 years old and resided in an area near a cadmium smelter in southeast China. All participants completed a questionnaire, and bone mineral density was measured by SPA-4 single-photon absorptiometry at the radius and ulna. Cadmium content of urine was determined by graphite-furnace atomic absorption spectrophotometry as a measure of dose. The decline in bone mineral density with age in a heavily polluted area was greater than that in a control area for subjects over 60 years of age of both sexes (p &lt; 0.05). In single regression, forearm bone densities were negatively correlated with urinary cadmium excretion in both males and females (p &lt; 0.001), whereas stepwise regression showed that forearm bone density decreased linearly with age (p &lt; 0.001) and urinary cadmium (p &lt; 0.01) in both sexes, suggesting a dose-effect relationship between cadmium dose and bone mineral density. Based on the World Health Organization criteria, (bone mineral density &lt; −2.5 SDs below the normal young adult), the prevalence of osteoporosis in women increased from 34.0% in the control area to 51.9% in the heavily polluted area (p &lt; 0.01) among subjects over 50 years old, and the odds ratio value was 2.09 (95% CI: 1.08–4.03) for the highly polluted area compared with the control area. A striking observation in the study was the marked increase of the prevalence of fracture in the cadmium-polluted area in both sexes. It was concluded that environmental exposure to cadmium is associated with an increased loss of bone mineral density in both males and females, leading to osteoporosis and increased risk of fractures, especially in the elderly and in females.
Tail Suspension Induces Bone Loss in Skeletally Mature Mice in the C57BL/6J Strain but Not in the C3H/HeJ Strain
Authors: Amblard Daniel , Lafage-Proust Marie-Hélène , Laib Andres , Thomas Thierry , Rüegsegger Peter , Alexandre Christian , Vico Laurence 
Published: April 2006

Abstract
We assessed the effects of tail-suspension in two skeletal genetic backgrounds, the high C3H/HeJ (C3H) and low C57BL/6J (B6) bone masses inbred mice (male, 4-months old). Cancellous bone mass and structural parameters were evaluated in distal femoral metaphysis by three dimensional microcomputed tomography. Bone cellular activities were evaluated by histomorphometry and measurements of alkaline phosphatase activity (ALP) and osteocalcin in blood and deoxypyridinoline (D-pyr) in urine. In C3H mice, 2- and 3-week unloading experiments were performed. After an early and transient decrease in body weight, a 2-week suspension period resulted in stimulation of both bone formation rate by 45% and active osteoclastic surfaces by 19%. D-pyr did not change, but ALP and osteocalcin levels increased by 18% and 72%, respectively, in 2-week suspended mice, and osteocalcin remained elevated by 30% in the 3-week suspended mice. Such cellular modifications allowed the C3H mice to maintain their initial bone mass and trabecular structural parameters even after a 3-week suspension period. In B6 mice, 1- and 2-week unloading experiments were performed. Tail suspension resulted in decreased body weight during the first days followed by an incomplete recovery during the second week of unloading. The resorption activity was unaffected by any suspension time period, whereas a decrease of 42.5% in bone formation rate and of 21.5% in ALP were seen by the end of the first week of suspension, both values being restored after a 2-week suspension period. At this latter time, trabeculae were thinner, leading to a 24.5% cancellous bone loss. Trabecular number and connectivity, rod-plate index, and degree of anisotropy were not modified. We concluded that C3H mice constituted a unique model in which genetic background overwhelmed the usual effects of reduced biomechanical usage in bone, whereas B6 mice, compared with the standardized rat model, offered an alternative model of bone loss in a mature skeleton.
Molecular Imaging of the Skeleton: Quantitative Real-Time Bioluminescence Monitoring Gene Expression in Bone Repair and Development
Authors: Bar Iris , Zilberman Yoram , Zeira Eveline , Galun Eithan , Honigman Alik , Turgeman Gadi , Clemens Thomas , Gazit Zulma , Gazit Dan 
Published: April 2006

Abstract
Monitoring gene expression in vivo, noninvasively, is a critical issue in effective gene therapy systems. To date, there are no adequate molecular imaging techniques, which quantitatively monitor gene expression in vivo in skeletal development and repair. The aim of this study was to monitor gene expression in skeletal development and repair, using a real-time molecular imaging system, which quantitatively and noninvasively detects bioluminescence in vivo. Our experimental model consisted of transgenic mice harboring the luciferase marker gene under the regulation of the human osteocalcin (hOC) promoter. A new light detection cooled charge coupled device (CCCD) camera was applied to monitor luciferase expression. In vitro, mesenchymal stem cells (MSCs) isolated from bone marrow of transgenic mice exhibited hOC promoter regulation, detected by luciferase expression that correlated with their osteogenic differentiation. During development from 1 week to 1.5 years, transgenic mice exhibited transgene expression in a wide spectrum of skeletal organs, including calvaria, vertebra, tail, and limbs, reaching a peak at 1 week in most of the skeletal organs. In two skeletal repair models, bone fracture and marrow ablation, the noninvasive CCCD system revealed a peak of luciferase expression at 6 days postsurgery. All quantitative, noninvasive, real-time CCCD measurements correlated with a luciferase biochemical assay and luciferase immunohistochemistry, which demonstrated luciferase expression in hypertrophic chondrocytes and trabecular osteoblasts. Our studies show for the first time (1) the CCCD detection system is a reliable quantitative gene detection tool for the skeleton in vivo, (2) expression of luciferase regulated by the hOC promoter is significantly decreased with age in most skeletal sites, and (3) the dynamics of hOC regulation during mice skeletal development and repair in real time, quantitatively and noninvasively.