bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal expression of the anabolic action of PTH in cancellous bone of ovariectomized rats
Authors: Meng X.W. , Liang X.G. , Birchman R. , Wu D.D. , Dempster D.W. , Lindsay R. , Shen V. 
Published: February 2010

Abstract
When administered intermittently, parathyroid hormone (PTH) is a potent anabolic agent in both human and animal bone. To improve our understanding of this anabolic effect, we have examined the time course of PTH action in an established animal model of estrogen deficiency-induced bone loss: the ovariectomized rat. Animals were ovariectomized (Ovx) and allowed to lose bone for 6 weeks. A dose of 20 μg/kg/d of rat PTH (1–34) was administered s.c., 6 days each week for periods of 1, 2, 3, 4, 6 and 8 weeks. Animals were sacrificed for evaluation of skeletal histomorphometry of the proximal tibia and mechanical strength of the cancellous bone in the marrow cavity of the distal femur. Cancellous bone volume (Cn-BV/TV) increased gradually over 8 weeks of treatment (16.8 ± 1.6 to 24.1 ± 2.7%) as did the bone formation rate (0.308 ± 0.054 to 1.659 ± 0.293 μm3/μm2/d), as determined by an increase in both total mineralization surface (15.5 ± 2.1 to 42.7 ± 5.0%) and mineral apposition rate (1.88 ± 0.20 to 3.55 ± 0.39 μm/d). The largest increments in these variables reflecting bone formation occurred over the first week of treatment. This bone formation was accompanied by an increase in trabecular thickness (Tb.Th) (55.3 ± 3.4 to 80.5 ± 5.0 μm) without a corresponding increment in trabecular number (Tb.N) (3.65 ± 0.17 to 3.55 ± 0.26). Extensive tetracycline labels were visualized on the surface of trabecular rod-like and plate-like structures. A small transient, though not statistically significant, increase occurred in both eroded surface and urinary pyridinoline concentration immediately after the onset of PTH administration. Osteocalcin showed a small decrement in the first two weeks after PTH administration, but the levels were elevated when compared with the Ovx control in later weeks. Mechanical strength of the cancellous bone also increased significantly with PTH treatment (20.5 ± 2.4 to 46.1 ± 10.0 Newtons). Our results showed that: 1) intermittent PTH treatment of Ovx rats elicited an immediate increase of bone formation activity by the existing osteoblasts, 2) the increase of Cn-BV/TV after PTH administration resulted primarily from an increase in Tb.Th, and 3) improved mechanical strength after PTH treatment can be achieved by increases in Tb.Th without an increase in Tb.N.
Effects of synthetic peptido-leukotrienes on bone resorption in vitro
Authors: Garcia C. , Qiao M. , Chen D. , Kirchen M. , Gallwitz W. , Mundy G.R. , Bonewald L.F. 
Published: February 2010

AbstractPeptido-leukotrienes are short-lived organic molecules known to have potent biological effects as mediators of inflammation, hypersensitivity and respiratory disorders. However, little is known concerning their effects on bone cells. We have shown previously that stromal cells isolated from a human giant cell tumor secrete 5-HETE (5-hydroxyeicosatetraenoic acid) and the peptido-leukotrienes, also known as the cysteinyl leukotrienes LTC4, LTD4, and LTE4. These eicosanoids were shown to stimulate the multinucleated giant cells obtained from these tumors to form resorption lacunae on sperm whale dentine. Here, we show that the peptido-leukotrienes also stimulate isolated avian osteoclast-like cells to form resorption lacunae and to increase their content of tartrateresistant acid phosphatase. LTD4 increased 45Ca release from murine calvarial bone organ cultures, but not from fetal rat long bone cultures. Isolated avian osteoclast-like cells were chosen to perform receptor binding studies, as this population is the most homogenous source of osteoclasts available. After the precursors had fused to form multinucleated cells, receptor binding assays were performed. Scatchard analysis of saturation binding data showed a single class of binding sites, with a dissociation constant (Kd) of 0.53 nM and a receptor density of 5,200 receptors per cell. Competition binding studies showed receptor specificity using a specific LTD4 receptor antagonist ZM 198,615. These data show that the peptido-leukotrienes activate highly enriched populations of isolated avian osteoclast-like cells, and also that specific LTD4 receptors are present in this cell population.
Bone-selective analogs of human PTH(1–34) increase bone formation in an ovariectomized rat model
Authors: Lane Nancy E. , Kimmel Donald B. , Nilsson Magnus H.L. , Cohen Fred E. , Newton Suellen , Nissenson Robert A. , Strewler Gordon J. 
Published: February 2010

Abstract
Intermittent parathyroid hormone (PTH) therapy increases bone mass. The purpose of this study was to determine if analogs of human PTH(1–34) (hPTH[1–34]), which differ from the native sequence in their receptor-activating properties, could promote bone formation in an ovariectomized (OVX) osteopenic rat model. We synthesized two hPTH(1–34) analogs with single substitutions for serine in the 3-position that in vitro are partial agonists in kidney. In the renal cell line OK, maximal cyclic adenosine monophosphate (cAMP) activation by [His3]hPTH(1–34) was 50%, and maximal cAMP activation by [Leu3]hPTH(1–34) was 20% of that produced by hPTH(1–34). Both analogs were full agonists in UMR-106 rat osteosarcoma cells and other bone-derived systems, but both had reduced potency compared with hPTH(1–34). Six-month-old retired breeder Sprague-Dawley rats were ovariectomized, and five animals underwent sham operation. On day 56 post-OVX, five sham-operated and five pre-PTH treatment OVX animals were sacrificed, and the remaining animals were randomized into 10 groups of six animals each. All other animals were injected with one of the hPTH analogs or hPTH(1–34) at 0,4,40, or 400 μg/kg of body weight (BW)/day and were killed on day 84. Histomorphometry of the proximal tibia metaphysis and biochemical markers of bone turnover (osteocalcin and pyridinoline cross-links) were the primary endpoints. The cancellous bone volume was significantly lower at day 56 post-OVX (pretreatment) and at day 84 post-OVX (post-vehicle treatment) than at baseline. None of the compounds significantly increased the cancellous bone volume. Trabecular number declined after OVX and did not change with hPTH treatment. In contrast, the trabecular thickness declined after OVX but was higher after treatment with 40 μg/kg of BW/day or 400 μg/kg of BW/day of hPTH(1–34). In OVX rats, the mineralizing surface was higher than baseline at day 56 and fell toward control levels by day 84. All three peptides produced marked dose-related increases in the mineralizing surface and bone formation rates, but the two analogs were less potent than hPTH(1–34). Likewise, all peptides produced significant dose-related increases in the serum osteocalcin level. The osteoclast surface was not affected by OVX but was decreased with medium and high doses of hPTH(1–34). Pyridinoline cross-link excretion was not significantly affected by treatment with hPTH(1–34) but responded with a dose-dependent decrease to treatment with [His3]hPTH(1–34). These data suggest that bone selective analogs of hPTH(1–34) maintain the ability to induce bone formation but are less potent than hPTH(1–34).
In vivo demonstration that parathyroid hormone and parathyroid hormone–related protein stimulate expression by osteoblasts of interleukin-6 and leukemia inhibitory factor
Authors: Pollock Jennifer H. , Blaha Michelle J. , Lavish Sandra A. , Stevenson Sharon , Greenfield Edward M. 
Published: February 2010

Abstract
We have previously reported that parathyroid hormone (PTH) and PTH related protein (PTHrP) stimulate expression of interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) in osteoblasts in vitro. In the current study, we have developed a model of hormone injection into the subcutaneous space overlying mouse parietal bones to demonstrate that similar processes occur in osteoblasts in vivo. Specifically, PTH and PTHrP rapidly and transiently induce expression of the mRNAs encoding IL-6 and LIF. The effects are dose-dependent, with a maximal stimulation of approximately 50-fold for each cytokine. Although PTH and PTHrP activate both adenyl cyclase and phospholipase C-dependent signal transduction pathways, stimulation of IL-6 and LIF depends on adenyl cyclase since it is not reproduced by PTH(3–34), a partial agonist that only activates phospholipase C. These results confirm our previous in vitro studies and support the hypothesis that IL-6 and/or LIF are physiologically important mediators of at least some of the actions of PTH and PTHrP.
Long-term extracellular matrix metabolism by cultured human osteogenesis imperfecta osteoblasts
Authors: Fedarko Neal S. , Sponseller Paul D. , Shapiro Jay R. 
Published: February 2010

Abstract
Osteopenia due to deficient extracellular matrix synthesis is a hallmark of osteogenesis imperfecta (OI). Previous studies carried out within 72 h of osteoblast subculture, at an early stage of matrix synthesis, indicated that for osteoblasts derived from human OI patients the total amounts of collagen, osteonectin, and three proteoglycans were significantly reduced, while total amounts of thrombospondin, fibronectin, and matrix hyaluronan were elevated compared with age-matched controls. The current study was undertaken to follow OI osteoblast matrix metabolism as that matrix is synthesized, deposited, and matured. Steady-state metabolic radiolabeling was used to follow the metabolism of collagen, hyaluronan, and total proteoglycan by OI and normal osteoblasts for up to 5 weeks. Trabecular osteoblasts from non-OI controls showed an increase in total and matrix-associated collagen synthesis during the first and second week, reaching steady-state levels by week 4. In contrast, cultured OI osteoblasts did not increase either the total (medium + matrix-associated) or matrix-associated collagen during the entire 5-week period. Proteoglycan synthesis exhibited a pattern similar to that for collagen. OI-derived proteoglycans differed from controls in that levels in OI cultures did not reflect the normal time-dependent increase in total proteoglycan and proteoglycan matrix deposition. OI osteoblast hyaluronan synthesis was increased when compared with age-matched controls during 4 weeks of culture. In contrast, the ratios of calcium to phosphorus solublized from control and the OI extracellular matrix were not statistically different. Thus, with respect to the synthesis of collagen, proteoglycans, and hyaluronan, OI osteoblasts fail to parallel controls in depositing and elaborating extracellular matrix during 35 days in culture.
Total body calcium and bone mineral content: Comparison of dual-energy X-ray absorptiometry with neutron activation analysis
Authors: Ellis K.J. , Shypailo R.J. , Hergenroeder A. , Perez M. , Abrams S. 
Published: February 2010

Abstract
The aim of this study was to compare the dual-energy X-ray absorptiometry (DXA) measurement of bone mass with an independent measure of body calcium obtained by neutron activation analysis (NAA). Total body bone mineral content (BMC) was measured using DXA in 46 subjects in the age range 5–47 years (17 children, 28 young women, and 1 adult male). Total body calcium (TBCa) was measured in the same subjects by in vivo NAA. The correlation between the two measures of bone mass was highly significant (BMC[g] = 3.22 × TBCa[g] – 51.4, r &gt; 0.98, p &lt; 0.0001, SEEBMC = 122.7 g). When BMC was the independent parameter, the SEETBCa was 37.5 g. Bland-Altman analysis indicated a mean difference of 2.8 g with a standard error + 4.7 g for TBCaNAA versus TBCaDXA when the BMC values were converted to TBCa. The relative change in bone mass (ΔTBCa/ABMC) for DXA was higher than that reported for dual-photon absorptiometry versus NAA. The findings presented in this study provide translational equations among the DXA and NAA measurements and for the conversion of total body BMC to TBCa in children and young adults.
Regional bone mineral density interrelationships in normal and osteoporotic postmenopausal women
Authors: Prof. Nordin B.E. Christopher , Chatterton Barry E. , Schultz Christopher G. , Need Allan G. , Horowitz Michael 
Published: February 2010

Abstract
We describe a prospective study in which bone mineral density (BMD) was measured in total body and regions, proximal femur, lumbar spine, and forearm in 84 apparently normal postmenopausal women with normal spinal radiographs and in 47 women with 1–10 wedged or compressed vertebrae. There was a history of peripheral fracture in 35 of the 84 controls and 30 of the 47 osteoporotics (p &lt; 0.02) but there was no association between vertebral fracture and wrist fracture. At all sites and regions, the differences in BMD between the “normal” and “osteoporotic” women was highly significant and all but “ribs” and “arms” remained significant after correction for menopausal age. In the whole set, and in both subgroups, the coefficients of correlation between sites and regions were all highly significant (p &lt; 0.001). Nonetheless, some sites discriminated better between the two groups than others. Standardized odds ratios (OR) for vertebral fracture versus no-fracture were calculated by logistic regression and expressed as the rise in OR for each standard deviation (SD) fall in bone density. This ratio was greatest (3.4) in “pelvis” and weakest (1.7) in “ribs” but all were statistically significant. Geometric mean regression equations were calculated for all the 78 possible pairs of sites and regions in the 84 normal subjects and the deviations of the osteoporotic women from these normal slopes calculated. In most pairs of sites and regions, the vertebral fracture cases were scattered around the normal group's slope but fell lower down on both axes. The bone deficits in the osteoporotics compared with young normal women ranged from –14% in “head” to –40% in Ward's triangle and the T-scores ranged from –1.9 in “ribs” to –3.9 in the forearm. Sensitivity ranged from 17% in “ribs” to 36.2% in Ward's triangle. Specificity varied between 88 and 94% and the percent correctly classified ranged from 62.6% in “ribs” to 72.5% in Ward's triangle. We conclude that primary postmenopausal osteoporosis affects the entire skeleton but that some sites discriminate better between vertebral fracture and nonfracture cases regardless of whether they represent cortical or trabecular bone.
The prevalence of vertebral deformity in European men and women: The european vertebral osteoporosis study
Authors: O'Neill T. W. , Felsenberg D. , Varlow J. , Cooper C. , Kanis J. A. , Silman A. J. ,   The European Vertebral Osteoporosis Study Group
Published: February 2010

Abstract
Our aim was to determine the prevalence of radiographically defined vertebral deformity, as a marker of vertebral osteoporosis, in different regions and populations within Europe. We used a cross-sectional population-based survey. Population-based sampling frames were obtained from 36 centers in 19 European countries. Stratified random sampling was used to recruit 15,570 males and females aged 50–79 years. Lateral spinal radiographs were taken according to a standardized protocol, and all X-rays were evaluated centrally. Vertebral deformity was morphometrically defined according to the published methods of McCloskey and Eastell. Based on the McCloskey method, the mean center prevalence of all deformities was 12% in females (range 6–21%) and 12% in males (range 8–20%). The prevalence increased with age in both sexes though the gradient was steeper in females. There was substantial geographical variation, with the highest rates in Scandinavian countries. Radiographically defined vertebral deformity is a common disorder and equally frequent in males and females. Using standardized methodology, there is important variation in occurrence across Europe, which might suggest clues to pathogenesis. (J Bone Miner Res 1996;11:1010–1018)
Analysis of signaling pathways used by parathyroid hormone to activate the c-fos gene in human SaOS2 osteoblast-like cells
Authors: Evans Dean B. , Hipskind Robert A. , Bilbe Graeme 
Published: February 2010

Abstract
We have evaluated the signaling pathways activated by parathyroid hormone (PTH) in SaOS2 human osteoblast-like cells correlating with induction of the c-fos proto-oncogene. Human PTH (1–34) (hPTH[1–34]) and hPTH(1–34) Nle8,18 Tyr34 induced the expression of c-fos mRNA in quiescent SaOS2 cells in a concentration-dependent manner. N-terminal truncations of hPTH(1–34) that fail to activate protein kinase A (PKA) also abolished c-fos mRNA induction. In gel retardation assays hPTH(1–34) led to a change in the mobility of specific, cyclic adenosine monophosphate (cAMP) response element binding protein (CREB)-containing protein-DNA complexes identical to that caused by other activators of PKA. The appearance of this altered mobility complex correlated temporally with the induction of c-fos mRNA. Using a c-fos serum response element probe, a slowed protein DNA complex appeared upon serum, epidermal growth factor, and basic fibroblast growth factor treatment. This slowed complex reflects phosphorylation of the transcription factor ternary complex factor (TCF) mediated via activation of the mitogen-activated protein (MAP) kinase pathway. The MAP kinase cascade is also activated by protein kinase C (PKC), and treatment with phorbol ester led to the induced TCF shift. In contrast, PTH did not produce this shift, ruling out PTH activation of c-fos via PKC and the MAP kinase signaling cascade. Further evidence for this was the lack of effect of the highly selective PKC inhibitor CGP 41251 on c-fos induction by hPTH(1–34). The janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling cascade targets the v-sis-inducible element in the c-fos promoter via the induced binding of STATs. Interferon γ rapidly induced STAT binding in SaOS2 cells, unlike PTH. Thus, PTH induction of c-fos transcription appears to occur principally through activation of PKA that then targets CREB and the c-fos calcium/cAMP response element.
Osteoarthritis in cynomolgus macaques III: Effects of age, gender, and subchondral bone thickness on the severity of disease
Authors: Carlson Cathy S. , Loeser Richard F. , Purser Connie B. , Gardin Jean F. , Jerome Christopher P. 
Published: February 2010

Abstract
Knee joints from cynomolgus monkeys of both genders and a wide range of ages were examined to characterize further the natural history of osteoarthritis (OA) in these animals. The objectives of this study were to characterize better the subchondral bone changes previously noted in this disease, to determine whether the severity of OA in these animals is affected by age or weight, and to determine whether males and females are affected similarly. As had been seen in previous studies, the medial tibial plateau was the most severely affected site. The thickness of the subchondral plate in the medial tibial plateau increased with increasing severity of articular cartilage lesions in both males and females; however, in monkeys with subchondral plate thicknesses less than 400 μm, articular cartilage lesions were essentially absent. Subchondral plate thickness increased with increasing weight in both genders, but females had a higher subchondral plate thickness than males for a given body weight. There was no correlation between bone volume in the proximal tibial epiphysis and articular cartilage lesions of OA. The prevalence and severity of OA in the medial tibial plateau increased with increasing age, but were not affected by gender or weight. Although there was no correlation between articular cartilage lesions and body mass index or weight, the waist/hip circumference ratio and severity of articular cartilage lesions were correlated in the female monkeys. This work provides evidence that thickening of the subchondral bone plate may be more important than the volume of epiphyseal/metaphyseal cancellous bone in determining the biomechanical stresses in the joint and in influencing the development of articular cartilage lesions.
DNA fragmentation during bone formation in neonatal rodents assessed by transferase-mediated end labeling
Authors: Bronckers A. L. J. J. , Goei W. , Luo G. , Karsenty G. , D'Souza R. N. , Lyaruu D. M. , Burger E. H. 
Published: February 2010

Abstract
To study the fate of bone cells, we used the transferase-mediated, biotin-dUTP nick end-labeling (TUNEL) assay to detect DNA fragmentation during the formation of intramembranous and endochondral bone in newly born hamsters, mice, and rats. In alveolar bone forming around the developing tooth crowns, DNA fragmentation was found in three cell types: TRAP-negative mononuclear cells at the bone surface, osteocytes, and some but not all nuclei of TRAP-positive osteoclasts. Osteoblasts did not undergo DNA fragmentation. A strong positive correlation was found between contacts of TUNEL-positive osteocytes and osteoclasts. Extracellular bone matrix also stained occasionally for the presence of DNA fragments. During endochondral bone formation, TUNEL staining was detected in late hypertrophic chondrocytes of the epiphyseal growth plate. During rapid longitudinal growth of long bones, TUNEL-positive hypertrophic chondrocytes were found coincident with or slightly after invasion of blood vessels from the diaphysis. However, during slow longitudinal growth and in secondary ossification centers, DNA fragmentation was seen in hypertrophic chondrocytes still located within their lacunae. We conclude that some of the osteocytes in deeper layers of bone die within their lacuna and disperse nuclear fragments over the extracellular matrix, that a majority of the osteocytes are phagocytosed and degraded by osteoclasts at sites of intense bone resorption, and that during endochondral ossification, substantial numbers of late hypertrophic chondrocyte cells undergo cell death.
Insulin receptor expression in bone
Authors: Thomas D. M. , Hards D. K. , Rogers S. D. , Ng K. W. , Best J. D. 
Published: February 2010

Abstract
Insulin is known to be an important osteotropic hormone. To date, no study has specifically addressed the possibility that insulin receptor expression may be regulated by differentiation in bone. We report a heterogeneous distribution of insulin receptor (IR) within neonatal rat calvaria using a specific monoclonal antibody to the β-subunit of the rat insulin receptor (CT-1). Specific binding of CT-1 to mature osteoblasts was demonstrated, with little binding over periosteal tissues or osteocytes. Using enzymatically derived subpopulations of calvarial cells, we showed a correlation between alkaline phosphatase activity and insulin-stimulated 2-deoxyglucose (2-DOG) uptake and increased 125I-insulin binding. Since primary calvarial cultures contain many cell types, we compared 125I-insulin binding, insulin-stimulated 2-DOG uptake, and Northern blot analysis of IR mRNA in the clonal preosteoblast-like cell line UMR 201-10B and the mature osteoblast cell line UMR 106-01. It is shown that UMR 106-01 cells possess higher levels of IR mRNA, insulin binding, and insulin-stimulated glucose uptake, and that insulin up-regulated expression of mRNA of the glucose transporter GLUT1 by 3-fold. In contrast, insulin binding was negligible in UMR 201-10B cells, which expressed much lower levels of IR mRNA. UMR 201-10B cells did not possess an insulin-sensitive glucose uptake system, although they express GLUT1 mRNA. These data are consistent with the hypothesis that, as in muscle and fat, insulin receptor expression correlates with the stage of osteoblast differentiation in vivo and in vitro.