bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human Microvascular Endothelial Cell Activation by IL-1 and TNF-α Stimulates the Adhesion and Transendothelial Migration of Circulating Human CD14+ Monocytes That Develop With RANKL Into Functional Osteoclasts
Authors: Kindle Libby , Rothe Linda , Kriss Michael , Osdoby Philip , Collin-Osdoby Patricia 
Published: April 2006

Abstract
Circulating pre-OCs may be recruited to locally inflamed sites through specific interactions with activated microvasculature. We found that HMVECs stimulated the adhesion and TEM of circulating pre-OCs, in an ICAM-1- and CD44-dependent manner, leading to greater RANKL-induced OC formation and bone pit resorption.
Introduction: Inflammation is critical for healing processes but causes severe tissue destruction when chronic. Local osteoclast (OC) formation and bone resorption may increase at inflammatory sites through multiple mechanisms, including direct stimulation by inflamed microvasculature of circulating OC precursor (pre-OC) migration through a blood vessel barrier into bone or joint tissue. How this might occur is not yet well understood.
Materials and Methods: Cytokine-activated human microvascular endothelial cell (HMVEC) monolayers, with or without IL-1 and TNF-α preactivation (24 h), were incubated in adhesion (1-3 h) or porous transwell transendothelial migration (TEM; 3 h) assays with human peripheral blood mononuclear cells (hPBMCs) or CD14+ monocyte or CD14− lymphocyte subsets. The number of cells that adhered or transmigrated, and their ability to thereafter develop with macrophage-colony stimulating factor (M-CSF) + RANKL into bone pit-resorbing OCs, were analyzed. Immunostaining and neutralizing antibodies to key cell adhesion molecules were used to determine their potential involvement in stimulated CD14+ monocyte TEM.
Results: M-CSF + RANKL caused OC and bone pit formation only from hPBMCs and CD14+ cells but not CD14− cells. Adhesion of hPBMCs or CD14+ cells but not CD14− cells was stimulated by cytokine preactivation of HMVECs and led to the full capture of all circulating pre-OCs capable of developing into OCs. Cytokine-preactivated HMVECs also promoted the postadhesion TEM of hPBMCs and CD14+ populations, resulting in markedly greater OC formation and bone pit resorption by transmigrated cells. Immunodetectable vascular cell adhesion molecule (VCAM-1), intercellular adhesion molecule (ICAM-1), and CD44 levels increased on cytokine-treated HMVEC surfaces, and neutralizing antibodies to ICAM-1 or CD44, but not VCAM-1 or platelet endothelial cell adhesion molecule (PECAM-1), inhibited stimulated CD14+ cell TEM through activated HMVECs.
Conclusions: This is the first demonstration that cytokine-activated HMVECs efficiently capture and promote the TEM of circulating pre-OCs capable of differentiating into bone-resorbing OCs. Thus, direct pre-OC recruitment by activated microvasculature at inflammatory sites may significantly contribute to normal OC bone remodeling during fracture healing or exacerbate pathological bone loss in various chronic inflammatory disorders.
Expression of Measles Virus Nucleocapsid Protein in Osteoclasts Induces Paget's Disease-Like Bone Lesions in Mice
Authors: Kurihara Noriyoshi , Zhou Hua , Reddy Sakamuri V , Palacios Veronica Garcia , Subler Mark A , Dempster David W , Windle Jolene J , Roodman G David 
Published: April 2006

Abstract
We targeted the MVNP gene to the OCL lineage in transgenic mice. These mice developed abnormal OCLs and bone lesions similar to those found in Paget's patients. These results show that persistent expression of MVNP in OCLs can induce pagetic-like bone lesions in vivo.
Introduction: Paget's disease (PD) of bone is the second most common bone disease. Both genetic and viral factors have been implicated in its pathogenesis, but their exact roles in vivo are unclear. We previously reported that transfection of normal human osteoclast (OCL) precursors with the measles virus nucleocapsid (MVNP) or measles virus (MV) infection of bone marrow cells from transgenic mice expressing a MV receptor results in formation of pagetic-like OCLs.
Materials and Methods: Based on these in vitro studies, we determined if the MVNP gene from either an Edmonston-related strain of MV or a MVNP gene sequence derived from a patient with PD (P-MVNP), when targeted to cells in the OCL lineage of transgenic mice with the TRACP promoter (TRACP/MVNP mice), induced changes in bone similar to those found in PD.
Results: Bone marrow culture studies and histomorphometric analysis of bones from these mice showed that their OCLs displayed many of the features of pagetic OCLs and that they developed bone lesions that were similar to those in patients with PD. Furthermore, IL-6 seemed to be required for the development of the pagetic phenotype in OCLs from TRACP/MVNP mice.
Conclusions: These results show that persistent expression of the MVNP gene in cells of the OCL lineage can induce pagetic-like bone lesions in vivo.
Long-Term Fracture Prediction by DXA and QUS: A 10-Year Prospective Study
Authors: Stewart Alison , Kumar Vinod , Reid David M 
Published: April 2006

Abstract
This study investigated the ability of DXA and QUS to predict fractures long term when measured around the time of the menopause. We found both DXA and QUS are able to predict both any fracture and “osteoporotic” fractures and that QUS can predict independently of BMD.
Introduction: There are now many treatments available for prevention of osteoporotic fracture. To be cost-effective, we need to target those most at risk. This study examines the ability of DXA and QUS to predict fractures in an early postmenopausal population of women.
Materials and Methods: We prospectively measured 3883 women who had been randomly selected from a community-based register. At baseline, they were measured using DXA of spine and hip (Norland XR-26) and QUS of the heel (Walker Sonix UBA 575). Follow-up had a mean of 9.7 ± 1.1 (SD) years. All incident fractures were identified and validated by examination of X-ray reports, and these were compared with those without fracture in a Cox-regression model to calculate hazard ratios (HRs).
Results: We found adjusted HRs for any fracture per 1 SD reduction in spine BMD to be 1.61 (1.42-1.83), whereas neck of femur BMD was 1.54 (1.34-1.75). Areas under the curve (AUC) for a receiver operator characteristic (ROC) analysis were 0.62 for spine BMD and 0.59 for neck BMD. In a subgroup where QUS was also measured, the HR for a 1 SD reduction in BMD was 1.69 (1.29-2.22) for spine BMD and 1.55 (1.17-2.06) for neck BMD. The HR for a 1 SD reduction in broadband ultrasound attenuation (BUA) was 1.53 (1.19-1.96), and 1.44 (1.12-1.86) when further adjusted for neck BMD. The AUCs were 0.63 for spine BMD, 0.59 for neck BMD, and 0.62 for BUA. When only osteoporotic fractures were examined, the HRs increased in all situations. BUA showed the highest HR of 2.25 (1.51-3.34), and when further adjusted for neck BMD was 2.12 (1.38-3.28).
Conclusions: In conclusion, it may be possible to scan women around the time of the menopause to predict future fractures. It seems that, for “osteoporotic” fractures, BUA may be an improved predictor of fractures in comparison with DXA, because the relative risk is highest for BUA, and independent of BMD.
The Mitogenic Effect of Parathyroid Hormone Is Associated with E2F-Dependent Activation of Cyclin-Dependent Kinase 1 (cdc2) in Osteoblast Precursors
Authors: Onishi Takehisa , Zhang Wenyu , Cao Xu , Hruska Keith 
Published: April 2006

Abstract
Injections of parathyroid hormone (PTH) have been reported to stimulate skeletal accretion through increased bone formation in several species, and osteoblast proliferation is a critical component of bone formation. However, the biological mechanisms of PTH-stimulated bone cell proliferation are largely unknown. In this study, we demonstrated that PTH stimulates proliferation of the osteoblast precursor cell line, TE-85, in association with increasing cdc2 protein levels and its kinase activity. cdc2 antisense oligonucleotides blocked PTH-induced DNA synthesis and cell cycle progression. Analysis of the time course of PTH-stimulated cdc2 message levels demonstrated that cdc2 mRNA levels were increased 1.5- to 4-fold between 3–18 h following release from cell synchronization. Transfections of TE-85 cells with a series of cdc2 promoter-luciferase deletion constructs revealed PTH stimulation of the cdc2 promoter. Promoter constructs containing a mutation in the E2F binding site were not stimulated by PTH. Gel mobility shift assays demonstrated increased free E2F levels in TE-85 nuclear extracts in response to PTH. Furthermore, the ratios of hyperphosphorylated to hypophosphorylated forms of Rb protein were increased by PTH treatment. These results demonstrate that PTH-stimulated cdc2 expression was associated with TE-85 cell proliferation and that the mechanism of stimulating cdc2 gene expression involved increasing the levels of free E2F.
Further Observations on Programmed Cell Death in the Epiphyseal Growth Plate: Comparison of Normal and Dyschondroplastic Epiphyses
Authors: Ohyama Kazuhiko , Farquharson Colin , Whitehead Colin C. , Shapiro Irving M. 
Published: April 2006

Abstract
The objective of the investigation was to provide information on apoptosis in the normal epiphysis and to assess apoptosis in the plate of the dyschondroplastic chick. Apoptosis was evaluated using two terminal deoxynucleotide transferase end-labeling procedures, DNA fragmentation and nuclear morphology. We found that there was a minimal level of apoptosis in the dyschondroplastic cartilage. In the tibial dyschondroplastic (TD) lesion itself, only about 3% of cells are positive in the articular and proliferative regions; 11% of prehypertrophic chondrocytes are stained by the end-labeling procedure, and most of the cells are localized around vascular channels at the calcifying front. This finding suggests that dyschondroplasia is linked to impairment of apoptosis, and as a result the tissue contains immature cells that have outlived their normal life span. In contrast, in the normal plate, we noted that when the proliferative period was complete, the cells became terminal transferase positive; in addition, chondrocytes in the normal plate exhibited DNA fragmentation. Semiquantitative analysis of stained chondrocytes in the growth plate indicate that in the proliferative zone 15.5% of cells are terminal deoxynucleotidyl transferase (TUNEL) positive; in contrast, 44% of postmitotic chondrocytes are stained by the TUNEL procedure. The presence of a sharp border between the pre- and postmitotic zones suggests that the stimulus for apoptosis is maturation dependent and reflects local metabolic control. We also examined apoptosis in metaphyseal osteoblasts. We found that adjacent to the epiphysis, many osteoblasts were undergoing apoptosis. In more mature sites in the metaphysis, there was less cell death, indicating that osteoblast apoptosis was delayed and cells were completing their normal life cycle. Although terminal transferase end-labeled cells were not seen in articular cartilage, we noted that fibroblasts, in the perichondrial ligament surrounding the articular as well as the epiphyseal regions of the plate, were undergoing apoptosis. Apoptosis at this site may be related to lateral expansion of the cartilages, reflect a high cell turnover rate at the junction between the tissues, and result from paracrine signals received from the underlying cartilage.
Interaction Between Nitric Oxide Synthase and Cyclooxygenase Pathways in Osteoblastic MC3T3-E1 Cells
Authors: Kanematsu Masahiro , Ikeda Kyoji , Yamada Yoshiji 
Published: April 2006

Abstract
Interleukin 1 (IL-1) and tumor necrosis factor α (TNF-α) have been implicated in the pathogenesis of osteoporosis. These proinflammatory cytokines induce both cyclooxygenase (COX) and nitric oxide synthase (NOS) with the release of prostaglandin (PG) and NO, respectively. The present study was undertaken to examine the interaction between COX and NOS pathways and their role in the regulation of osteoblastic function in MC3T3-E1 cells. Addition of IL-1α and TNF-α induced a marked increase in the production of both NO and PGE2. Reverse transcription–polymerase chain reaction analysis showed that the increase in NO production was preceded by the expression of inducible NOS mRNA. The temporal profile of PGE2 production revealed a biphasic pattern: the first small peak at 3 h was caused by de novo synthesis of PGE2 through inducible COX (COX-2) mRNA, while the subsequent progressive accumulation of PGE2 was mediated through the activation of COX pathway by NO since (1) aminoguanidine (AG), a selective inhibitor of inducible NOS, significantly suppressed the PGE2 production by IL-1α and TNF-α, (2) NOC-18, an NO donor, reversed this suppression, and (3) NOC-18 increased PGE2 production by itself. The increase in NO production in response to IL-1α and TNF-α was further stimulated by aspirin and inhibited by exogenous addition of PGE2, suggesting that PGE2 produced by the cytokines, in turn, negatively modulates NO production. IL-1α and TNF-α inhibited alkaline phosphatase (ALP) activity, which was significantly reversed by AG. NOC-18 not only suppressed ALP activity by itself but also blocked the effect of AG, suggesting the role of NO in the inhibition of ALP activity. PGE2 decreased ALP activity, and the inhibitory effect of NOC-18 was attenuated in the presence of aspirin, suggesting the involvement of PGE2 in the negative modulation of ALP activity by NO. These results suggest that NO produced in response to proinflammatory cytokines participates in the modulation of ALP activity via the activation of COX pathway. The interaction between NO and the COX pathways may play an important role in the regulation of osteoblastic functions under physiologic as well as pathologic conditions.
Cytokine-Induced Nitric Oxide Inhibits Bone Resorption by Inducing Apoptosis of Osteoclast Progenitors and Suppressing Osteoclast Activity
Authors: Van 't Hof Robert J. , Ralston Stuart H. 
Published: April 2006

Abstract
Interferon-γ (IFN-γ) has been shown to inhibit interleukin-1 (IL-1) and tumor necrosis factor α (TNF-α) stimulated bone resorption by strongly stimulating nitric oxide (NO) synthesis. Here we studied the mechanisms underlying this inhibition. Osteoclasts were generated in 10-day cocultures of mouse osteoblasts and bone marrow cells and the effect of cytokine-induced NO on osteoclast formation and activity was determined. Stimulation of the cocultures with IL-1β, TNF-α and IFN-γ markedly enhanced NO production by 50- to 70-fold, and this was found to be derived predominantly from the osteoblast cell layer. When high levels of NO were induced by cytokines during early stages of the coculture, osteoclast formation was virtually abolished and bone resorption markedly inhibited. Cytokine stimulation during the latter stages of coculture also resulted in inhibition of bone resorption, but here the effects were mainly due to an inhibitory effect on osteoclast activity. At all stages, however, the inhibitory effects of cytokines on osteoclast formation and activity were blocked by the NO-synthase inhibitor L-NMMA. Further investigations suggested that the NO-mediated inhibition of osteoclast formation was due in part to apoptosis of osteoclast progenitors. Cytokine stimulation during the early stage of the culture caused a large increase in apoptosis of bone marrow cells, and these effects were blocked by L-NMMA and enhanced by NO donors. We found no evidence of apoptosis in osteoblasts exposed to high levels of cytokine-induced NO at any stage in the culture, however, or of apoptosis affecting mature osteoclasts exposed to high levels of NO, suggesting that immature cells in the bone marrow compartment are most sensitive to NO-induced apoptosis. In summary, these studies identify NO as a potentially important osteoblast-osteoclast coupling factor which has potent inhibitory effects on bone resorption. These actions, in turn, are mediated by inhibition of osteoclast formation probably due to NO-induced apoptosis of osteoclast progenitors and by inhibition of the resorptive activity of mature osteoclasts.
Endogenous Sex Steroids and Bone Mineral Density in Older Women and Men: The Rancho Bernardo Study
Authors: Greendale Gail A. , Edelstein Sharon , Barrett-Connor Elizabeth 
Published: April 2006

Abstract
This study examines the associations between endogenous sex steroids and bone mineral density (BMD), using data from a geographically defined cohort in Rancho Bernardo, California. Participants were community-dwelling women and men aged 50–89 years who took part in a study of endogenous sex steroid measurement between 1984–1987 and who had BMD measured in 1988–1991. Those taking corticosteroids or estrogen at the time of sex steroid determination were excluded. The main study outcomes were BMD of the ultradistal radius, midshaft radius, lumbar spine, and total hip by sex steroid level, adjusted for age, body mass index, cigarette smoking, alcohol consumption, leisure exercise, use of thiazides, thyroid hormones, and former estrogen use (women only). At the time of the hormone measurements, the mean age of the 457 women was 72.1 years and that of the 534 men was 68.6 years. A statistically significant positive relation was seen between bioavailable estradiol and BMD at all sites in women and men. Total estradiol was significantly associated with BMD at all sites in women and at all but the ultradistal radius in men. Estrone had a global effect on BMD in women and was not measured in men. Higher bioavailable (but not total) testosterone levels were associated with higher BMD of the ultradistal radius, spine, and hip in men and the ultradistal radius in women. Dehydroepiandrosterone was positively associated with BMD of the midradius, spine, and hip in women and was not associated with BMD at any site in men. Of the sex steroids tested, bioavailable estrogen was most strongly associated with BMD in both women and men. We conclude that endogenous sex steroid levels are significantly related to bone density in older women and men. Individual variation in age-related bone loss may be partially accounted for by alterations in sex steroid levels with aging. Further study to elucidate safe environmental and medical methods to maintain optimal sex steroid levels in old age is needed.
Bone Density Variation and Its Effects on Risk of Vertebral Deformity in Men and Women Studied in Thirteen European Centers: The EVOS Study
Authors: Lunt M. , Felsenberg D. , Reeve J. , Benevolenskaya L. , Cannata J. , Dequeker J. , Dodenhof C. , Falch J. A. , Masaryk P. , Pols H. A. P. , Poor G. , Reid D. M. , Scheidt-Nave C. , Weber K. , Varlow J. , Kanis J. A. , O'NEILL T. W. , Silman A. J. 
Published: April 2006

Abstract
In Europe there is a 3-fold variation, according to geographical center, in risk of vertebral deformity in men and women over the age of 50. We investigated the relationship between bone density, as assessed by dual-energy X-ray absorptiometry (DEXA) of the spine and hip and prevalent vertebral deformities in 13 of the 36 centers participating in the European Vertebral Osteoporosis Study (EVOS). Each center recruited an age-stratified sample of men and women aged 50 years and over, and of those who agreed to densitometry, 288/2088 women and 233/1908 men were found to have one or more deformities of the vertebrae between T4 and L4 as assessed by the McCloskey algorithm. DEXA was in each case performed on L2–L4, the proximal femur, or both. Bone densitometry results were cross-calibrated between centers using the European Spine Phantom prototype and results expressed as bone mineral density (BMD, g/cm2). In both genders, subjects with deformities involving loss of anterior vertebral body height alone comprised over 20% of the total with deformities and these related poorly to BMD. Other classes of deformity were found by logistic regression to relate significantly to BMD in one or both genders, with odds ratios for the risk of any of these ranging from 1.67 to 2.11 for a 1 SD reduction in bone density at spine, femoral neck, or trochanter (p &lt; 0.001). Adjusting for anthropometric variables and BMD did not remove the effect of age on risk which rose 1.67- to 1.78-fold per decade according to gender. The greater unadjusted rate of increase in deformity risk with age in women was attributable to their faster rate of bone loss with age; after adjusting for age, body mass index (BMI), and BMD at the trochanter in grams per square centimeter, men had a 2-fold higher risk of deformity than women. Analysis of the relationship between mean bone density and the prevalence of deformity in each center demonstrated no significant differences between centers in either gender, after adjusting for BMD, age, and BMI together with an a posteriori statistical adjustment for imperfect cross-calibration of densitometers. It is concluded that BMD is an important determinant of deformity risk in both genders. Together with age, BMD explains much of the differences in risk both between the sexes and between individual geographical centers in Europe.
Functional Characterization of the Human Biglycan 5′-Flanking DNA and Binding of the Transcription Factor c-Krox
Authors: Heegaard Anne-Marie , Robey Pamela Gehron , Vogel Walther , Just Walter , Widom Russell L. , Schøller Jørgen , Fisher Larry W. , Young Marian F. 
Published: April 2006

Abstract
The transcriptional regulation of human biglycan expression under normal and pathological conditions was studied. The 5′-flanking regions of the human and mouse genes were isolated and analyzed; the two promoter regions share 81% identity. Both promoters are without a TATA and CAT box and contain multiple Sp1 sites. Human dermal fibroblasts were transiently transfected with progressive deletional human biglycan 5′-flanking DNA-CAT constructs, and a significant variation in activity among the individual constructs was found. A small deletion in several cases caused a more than 2-fold increase or decrease in promoter activity, thereby mapping the target sites for repressors or activators. Human biglycan expression is reduced in females with Ullrich-Turner syndrome (45,X) and increased in individuals with supernumerary sex chromosomes, and it has been speculated that biglycan plays a role in the short stature phenotype of Turner syndrome. Analysis of the transcriptional regulation of biglycan in individuals with sex chromosome anomalies showed that a −262 to −218 region of the biglycan promoter was differentially regulated. This region was extensively analyzed by DNAse footprinting and electrophoretic mobility shift assays, and a putative binding site for the transcription factor c-Krox was discovered. The binding of c-Krox to a site located at approximately −248 to −230 in the human biglycan promoter was confirmed by using extracts from COS cells expressing recombinant human c-Krox. The expression of c-Krox in bone was then examined by reverse-transcribed polymerase chain reaction and Northern blotting analysis; an ∼3.4 kb transcript was detected in primary osteoblastic cells, in MG–63 cells, and in human bone marrow stromal cells. This is the first detection of c-Krox in bone cells, and it suggests that c-Krox, like another member of the Krox family, Krox–20, might play a regulatory role in bone.