bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Negative Search for a Paramyxoviral Etiology of Paget's Disease of Bone: Molecular, Immunological, and Ultrastructural Studies in U.K. Patients
Authors: Helfrich M. H. , Hobson R. P. , Grabowski P. S. , Zurbriggen A. , Cosby S. L. , Dickson G. R. , Fraser W. D. , Ooi C. G. , Selby P. L. , Crisp A. J. , Wallace R. G. H. , Kahn S. , Ralston S. H. 
Published: April 2006

Abstract
Paget's disease of bone is a common bone disease characterized by increased and disorganized bone remodeling at focal sites throughout the skeleton. The etiology of the disease is unresolved. A persistent viral infection has long been suggested to cause the disease. Antigen and/or nucleic acid sequences of paramyxoviruses (in particular measles virus [MV], canine distemper virus [CDV], and respiratory syncytial virus [RSV]) have been reported in pagetic bone by a number of groups; however, others have been unable to confirm this and so far no virus has been isolated from patients. Here, we reexamined the question of viral involvement in Paget's disease in a study involving 53 patients with established disease recruited from seven centers throughout the United Kingdom. Thirty-seven patients showed clear signs of active disease by bone scan and/or histological assessment of the bone biopsy specimens and 12 of these had not received any therapy before samples were taken. Presence of paramyxovirus nucleic acid sequences was sought in bone biopsy specimens, bone marrow, or peripheral blood mononuclear cells using reverse-transcription polymerase chain reaction (RT-PCR) with a total of 18 primer sets (7 of which were nested), including 10 primer sets (including 3 nested sets) specifically for MV or CDV. For each patient at least one sample was tested with all primer sets by RT-PCR and no evidence for the presence of paramyxovirus RNA was found in any patient. In 6 patients, bone biopsy specimens with clear histological evidence of active disease tested negative for presence of measles and CDV using immunocytochemistry (ICC) and in situ hybridization (ISH). Intranuclear inclusion bodies, similar to those described by others previously, were seen in pagetic osteoclasts. The pagetic inclusions were straight, smooth tubular structures packed tightly in parallel bundles and differed from nuclear inclusions, known to represent MV nucleocapsids, in a patient with subacute sclerosing panencephalitis (SSPE) in which undulating, diffuse structures were found, arranged loosely in a nonparallel fashion. In the absence of amplification of viral sequences from tissues that contain frequent nuclear inclusions and given that identical inclusions are found in other bone diseases with a proven genetic, rather than environmental, etiology, it is doubtful whether the inclusions in pagetic osteoclasts indeed represent viral nucleocapsids. Our findings in this large group of patients recruited from throughout the United Kingdom do not support a role for paramyxovirus in the etiology of Paget's disease.
Alendronate Stimulates Collagenase 3 Expression in Osteoblasts by Posttranscriptional Mechanisms
Authors: Varghese Samuel , Canalis Ernesto 
Published: April 2006

Abstract
Bisphosphonates inhibit bone resorption by reducing osteoclastic cell number and activity. Alendronate is a nitrogen-containing bisphosphonate analog used in the treatment of postmenopausal osteoporosis. The effects of alendronate in osteoclasts are well documented; however, there is limited information on the actions of alendronate in osteoblasts (Ob's). In this study, we investigated the effects of alendronate at concentrations of 1-100 μM on the synthesis of collagenase 3 or matrix metalloproteinase 13 (MMP-13) and tissue inhibitors of MMPs (TIMPs) 1, 2, and 3 in primary Ob-enriched cells from 22-day-old fetal rat calvariae. Alendronate at concentrations higher than 10 μM markedly stimulated the synthesis of collagenase messenger RNA (mRNA) and immunoreactive protein in Ob's. Alendronate did not stimulate the transcriptional rate of the collagenase 3 gene. However, in transcriptionally arrested cells, alendronate prolonged the half-life of collagenase transcripts. Alendronate did not alter the expression of TIMP 1 and 2, but modestly stimulated the expression of TIMP 3. The actions of alendronate in Ob's suggest potential additional effects in bone remodeling.
A Dominant Negative Cadherin Inhibits Osteoblast Differentiation
Authors: Cheng Su-Li , Shin Chan Soo , Towler Dwight A. , Civitelli Roberto 
Published: April 2006

Abstract
We have previously indicated that human osteoblasts express a repertoire of cadherins and that perturbation of cadherin-mediated cell-cell interaction reduces bone morphogenetic protein 2 (BMP-2) stimulation of alkaline phosphatase activity. To test whether inhibition of cadherin function interferes with osteoblast function, we expressed a truncated N-cadherin mutant (NCadδC) with dominant negative action in MC3T3-E1 osteoblastic cells. In stably transfected clones, calcium-dependent cell-cell adhesion was decreased by 50%. Analysis of matrix protein expression during a 4-week culture period revealed that bone sialoprotein, osteocalcin, and type I collagen were substantially inhibited with time in culture, whereas osteopontin transiently increased. Basal alkaline phosphatase activity declined in cells expressing NCadΔC, relative to control cells, after 3 weeks in culture, and their cell proliferation rate was reduced moderately (17%). Finally,45Ca uptake, an index of matrix mineralization, was decreased by 35% in NCadΔC-expressing cells compared with control cultures after 4 weeks in medium containing ascorbic acid and β-glycerophosphate. Similarly, BMP-2 stimulation of alkaline phosphatase activity and bone sialoprotein and osteopontin expression also were curtailed in NCadΔC cells. Therefore, expression of dominant negative cadherin results in decreased cell-cell adhesion associated with altered bone matrix protein expression and decreased matrix mineralization. Cadherin-mediated cell-cell adhesion is involved in regulating the function of bone-forming cells.
Caveolae in Human and Murine Osteoblasts
Authors: Solomon Keith R. , Adolphson Layla D. , Wank David A. , Mchugh Kevin P. , Hauschka Peter V. 
Published: April 2006

Abstract
Caveolae are 50- to 100-nm plasmalemmal vesicles formed by oligomerized caveolin, a 22-kDa phosphoprotein. These organelles have been implicated in critical signal transduction and molecular transport processes. Here, we show for the first time that osteoblasts express caveolin and have abundant caveolae. Membrane fractionation techniques indicate that osteoblast caveolin is found in detergent-resistant membranes that have the buoyant density characteristic of caveolae, whereas immunoblotting and reverse-transcription polymerase chain reaction (RT-PCR) show that osteoblasts express both caveolin-1 and −2 isoforms. Electron microscopy (EM) and immunofluorescence reveal the hallmarks of caveolae in osteoblasts: abundant 50- to 100-nm noncoated cell surface invaginations (caveolae) and abundant punctate clusters of immunostained caveolin.
Thyroid Hormones Regulate Hypertrophic Chondrocyte Differentiation and Expression of Parathyroid Hormone-Related Peptide and Its Receptor During Endochondral Bone Formation
Authors: Stevens David A. , Hasserjian Robert P. , Robson Helen , Siebler Thomas , Shalet Stephen M. , Williams Graham R. 
Published: April 2006

Abstract
Hypothyroidism in children causes developmental abnormalities in bone and growth arrest, while thyrotoxicosis accelerates growth rate and advances bone age. To determine the effects of thyroid hormones on endochondral bone formation, we examined epiphyseal growth plates in control, hypothyroid, thyrotoxic, and hypothyroid-thyroxine (hypo-T4)-treated rats. Hypothyroid growth plates were grossly disorganized, contained an abnormal matrix rich in heparan sulfate, and hypertrophic chondrocyte differentiation failed to progress. These effects correlated with the absence of collagen X expression and increased parathyroid hormone-related protein (PTHrP) messenger RNA (mRNA) expression. In thyrotoxic growth plates, histology essentially was normal but PTHrP receptor (PTHrP-R) mRNA was undetectable. PTHrP is a potent inhibitor of hypertrophic chondrocyte differentiation that acts in a negative feedback loop with the secreted factor Indian hedgehog (Ihh) to regulate endochondral bone formation. Thyroid hormone receptor α1(TRα1), TRα2, and TRβ1 proteins were localized to reserve zone progenitor cells and proliferating chondrocytes in euthyroid rat cartilage; regions in which PTHrP and PTHrP-R expression were affected by thyroid status. Thus, dysregulated Ihh/PTHrP feedback loop activity may be a key mechanism that underlies growth disorders in childhood thyroid disease.
Circannual Rhythms and Interactions of Vitamin D Metabolites, Parathyroid Hormone, and Biochemical Markers of Skeletal Homeostasis: A Prospective Study
Authors: Woitge Henning W. , Knothe Antje , Witte Klaus , Schmidt-Gayk Heinrich , Ziegler Reinhard , Lemmer Björn , Seibel Markus J. 
Published: April 2006

Abstract
Recent studies suggest a circannual pattern of bone turnover. To further investigate the underlying mechanisms, 41 healthy subjects (25-80 years old) living in a southwestern German city were studied prospectively over a period of 18 months. Participants were examined every 4 weeks, and blood and urine samples were obtained on each visit. The following parameters were measured: serum 25-hydroxyvitamin D3 [25(OH)D3], 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and parathyroid hormone (PTH), as regulators, and serum total alkaline phosphatase (TAP), bone-specific alkaline phosphatase (BAP), urinary total pyridinoline (PYD), deoxypyridinoline (DPD), and the aminoterminal telopeptide of collagen type I (NTX), as biochemical markers of bone turnover. The presence of significant circannual rhythms for the various markers was tested using the Pharmfit method. In the total group, 25(OH)D3, 1,25(OH)2D3, and PTH as well as BAP, PYD, DPD, and NTX showed a significant seasonal variation. 25(OH)D3 revealed the highest amplitude (38.0%) with an acrophase in August. Levels of the biochemical markers and of PTH were highest in winter with amplitudes of up to 17.7% (DPD). Results were most pronounced in premenopausal women, in subjects &lt;50 years of age, and in subjects who did show a significant individual rhythm in 25(OH)D3 levels. No differences were found regarding other anthropometric or life style factors. Correlation analyses revealed strongest associations between the amplitudes of a vitamin D metabolite and a biochemical marker in premenopausal women. We conclude that specific markers of bone turnover show significant circannual rhythms. These changes are related directly to variations in the hormonal regulation of skeletal homeostasis. In postmenopausal women and in men, other effects may superimpose the circannual variation of biomarkers of bone turnover.
Rapid Small-Animal Dual-Energy X-Ray Absorptiometry Using Digital Radiography
Authors: Holdsworth D. W. , Thornton M. M. , Drost D. , Watson P. H. , Fraher L. J. , Hodsman A. B. 
Published: April 2006

Abstract
Although dual-energy X-ray absorptiometry (DEXA) is an established technique for clinical assessment of areal bone mineral density (BMD), the spatial resolution, signal-to-noise ratio, scan time, and availability of clinical DEXA systems may be limiting factors for small-animal investigations using a large number of specimens. To avoid these limitations, we have implemented a clinical digital radiography system to perform rapid area DEXA analysis on in vitro rat bone specimens. A crossed step-wedge (comprised of epoxy-based materials that mimic the radiographic properties of tissue and bone) was used to calibrate the system. Digital radiographs of bone specimens (pelvis, spine, femur, and tibia from sham-ovariectomized [SHAM] and ovariectomized [OVX] rats) were obtained at 40 kilovolt peak (kVp) and 125 kVp, and the resulting areal BMD values were compared with those obtained with a clinical fan-beam DEXA system (Hologics QDR 4500). Our investigation indicates that the cross-wedge calibrated (CWC) DEXA technique provides high-precision measurements of bone mineral content (BMC; CV = 0.6%) and BMD (CV = 0.8%) within a short acquisition time (&lt;30 s). Areal BMD measurements reported by the CWC-DEXA system are within 8.5% of those reported by a clinical fan-beam scanner, and BMC values are within 5% of the known value of test specimens. In an in vivo application, the CWC-DEXA system is capable of reporting significant differences between study groups (SHAM and OVX) that are not reported by a clinical fan-beam DEXA system, because of the reduced variance and improved object segmentation provided by the CWC-DEXA system.
Beneficial Effect of Intermittent Cyclical Etidronate Therapy in Hemiplegic Patients Following an Acute Stroke
Authors: Sato Yoshihiro , Asoh Takeshi , Kaji Masahide , Oizumi Kotaro 
Published: April 2006

Abstract
Significant decreases in bone mineral density (BMD) occur on the hemiplegic side in chronic stroke patients, which correlate with the degree of paralysis and hypovitaminosis D. In this double-blind, randomized, and prospective study of 98 patients with hemiplegia involving both an upper and lower extremity (55 males and 53 females; mean age, 71.4 ± 0.6 years) after an acute stroke, 49 were given etidronate for 56 weeks and 49 received a placebo. The BMD was measured by computed X-ray densitometry (CXD) of the second metacarpal bone bilaterally. Forty age-matched control subjects were followed for 56 weeks. At baseline, both groups had 25-hydroxyvitamin D [25(OH)D] insufficiency, increased serum ionized calcium and pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP), and low serum concentrations of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25(OH)2D], suggesting immobilization-induced hypercalcemia and inhibition of renal synthesis of 1,25(OH)2D. The BMD on the hemiplegic side decreased by 2.3% and 4.8% in the etidronate and placebo groups, respectively (p = 0.0003). After treatment, the serum 1,25(OH)2D concentration increased by 62.2% in the etidronate group and decreased by 12.4% in the placebo group. The etidronate group had significant decreases in the serum ionized calcium and ICTP and increases in PTH and bone Gla protein (BGP), whereas the placebo group had higher serum calcium and ICTP concentrations but stable PTH. These results suggest that etidronate can prevent decreases in the BMD in hemiplegic stroke patients because it decreases the serum calcium through inhibition of bone resorption and causes a subsequent increase in the serum 1,25(OH)2D concentration.
The Oxidative Metabolism of Estradiol Conditions Postmenopausal Bone Density and Bone Loss
Authors: Leelawattana Rattana , Ziambaras Konstantinos , Roodman-Weiss Jane , Lyss Christine , Wagner Danielle , Klug Thomas , Armamento-Villareal Reina , Civitelli Roberto 
Published: April 2006

Abstract
Because lifelong exposure to estrogen is a strong determinant of bone mass, we asked whether metabolic conversion of estrogen to either inactive or active metabolites would reflect postmenopausal bone mineral density (BMD) and rate of bone loss. Biochemical markers of inactive estrogen metabolites, urinary 2-hydroxyestrogen (2OHE1) and 2-methoxyestrogen (2MeOE1), and active metabolites, urinary 16α-hydroxyestrone (16αOHE1), estradiol (E2), and estriol (E3), were determined in 71 untreated, healthy postmenopausal women (age, 47-59 years) followed prospectively for 1 year. Urinary 2MeOE1 was correlated negatively with baseline vertebral (anteroposterior [AP] projection, r = −0.23 and p &lt; 0.05; lateral view, r = −0.27 and p &lt; 0.05) and proximal femur bone density measured by dual-energy X-ray absorptiometry (DXA; total, r = −0.38 and p &lt; 0.01; neck, r = −0.28 and p = 0.02; trochanter, r = −0.44 and p &lt; 0.01). BMDs of women in the lowest quartile of urinary 2MeOE1 (&lt;15 ng/g) were significantly higher than those in the highest quartile at all skeletal sites (p &lt; 0.05). Likewise, women in the lowest quartile of urinary 2OHE1/16αOHE1 ratio (&lt;1.6) did not experience bone loss after 1 year, in contrast to women in the higher quartiles. We propose that the rate of inactivation of estrogens through 2-hydroxylation may contribute to postmenopausal osteoporosis.
Insulin-Like Growth Factor I Production Is Essential for Anabolic Effects of Thyroid Hormone in Osteoblasts
Authors: Huang Bill K. , Golden Laurence A. , Tarjan Gabor , Madison Laird D. , Stern Paula H. 
Published: April 2006

Abstract
Thyroid hormone (T3) and insulin-like growth factor I (IGF-I) are critical regulators of skeletal function. T3 increases IGF-I production in bone. To assess the potential role of IGF-I as a mediator of T3 actions, we characterized phenotypic markers of osteoblast activity in two osteoblast models, normal mouse osteoblasts and MC3T3-E1 cells, exposed to T3 alone or under conditions that interfere with IGF-I actions. T3 significantly increased osteoblast 3H-proline incorporation, alkaline phosphatase (ALP), and osteocalcin. Both αIR3, a neutralizing monoclonal antibody to the IGF-I receptor, and JB1, an IGF-I analogue antagonist, attenuated the stimulatory effects of T3. T3 effects also were decreased in cells transfected with antisense oligonucleotide (AS-ODN) to the IGF-I receptor gene. Both IGF-I and T3 had mitogenic effects that were inhibited by the antagonists. IGF-I by itself did not stimulate 3H-proline incorporation, ALP, and osteocalcin in the models used, revealing that although IGF-I is essential for the anabolic effects of T3, it acts in concert with other factors to elicit these phenotypic responses. (J Bone Miner Res 2000;15:188–197)
Crucial Involvement of the EP4 Subtype of Prostaglandin E Receptor in Osteoclast Formation by Proinflammatory Cytokines and Lipopolysaccharide
Authors: Sakuma Yoko , Tanaka Kiyoshi , Suda Michio , Yasoda Akihiro , Natsui Koshi , Tanaka Issei , Ushikubi Fumitaka , Narumiya Shuh , Segi Eri , Sugimoto Yukihiko , Ichikawa Atsushi , Nakao Kazuwa 
Published: April 2006

Abstract
Prostaglandin E2 (PGE2) exerts its effects through the PGE receptor that consists of four subtypes (EP1, EP2, EP3, and EP4). Osteoclast formation in the coculture of primary osteoblastic cells (POB) and bone marrow cells was enhanced more by 11-deoxy-PGE1 (an EP4 and EP2 agonist) than by butaprost (an EP2 agonist) and other agonists, which suggests that EP4 is the main factor in PGE2-induced osteoclast formation. PGE2-induced osteoclast formation was not observed in the coculture of POB from EP4-deficient (EP4 k/o) mice and spleen cells from wild-type (w/t) mice, whereas osteoclasts were formed in the coculture of POB from w/t mice and spleen cells from EP4-k/o mice. In situ hybridization (ISH) showed that EP4 messenger RNA (mRNA) was expressed on osteoblastic cells but not on multinucleated cells (MNCs) in w/t mice. These results indicate that PGE2 enhances osteoclast formation through its EP4 subtype on osteoblasts. Osteoclast formation by interleukin 1α (IL-1α), tumor necrosis factor α (TNF-α), basic fibroblast growth factor (bFGF), and lipopolysaccharide (LPS) was hardly observed in the coculture of POB and bone marrow cells, both from EP4-k/o mice, which shows the crucial involvement of PG and the EP4 subtype in osteoclast formation by these molecules. In contrast, osteoclast formation by 1,25-hydroxyvitamin D3 (1,25(OH)2D3) was not impaired and that by parathyroid hormone (PTH) was only partially impaired in EP4-k/o mice, which may be related to the fact that EP4-k/o mice revealed no gross skeletal abnormalities. Because it has been suggested that IL-1α, TNF-α, bFGF, and LPS are involved in inflammatory bone loss, our work can be expected to contribute to an understanding of the pathophysiology of these conditions.(J Bone Miner Res 2000;15:218–227)
Early Postmenopausal Bone Loss Is Associated with PvuII Estrogen Receptor Gene Polymorphism in Finnish Women: Effect of Hormone Replacement Therapy
Authors: Salmén Timo , Heikkinen Anna-Mari , Mahonen Anitta , Kröger Heikki , Komulainen Marja , Saarikoski Seppo , Honkanen Risto , Mäenpää Pekka H. 
Published: April 2006

Abstract
Genetic factors regulate bone mineral density (BMD) and possibly the development of osteoporosis. An association between estrogen receptor (ER) polymorphism, BMD, and postmenopausal hormone replacement therapy (HRT) has not been established. Therefore, we studied the influence of the ER genotype on BMD before and after a 5-year HRT in a placebo-controlled, population-based, randomized group of 322 early postmenopausal women. The participants were randomized into two treatment groups: the HRT group (n = 145) received a sequential combination of 2 mg estradiol valerate and 1 mg CPA with or without vitamin D3, 100–300 IU + 500 mg calcium lactate/day (equal to 93 mg Ca2+), and the non-HRT group (n = 177) received calcium lactate, 500 mg alone or in combination with vitamin D3, 100–300 IU/day. PvuII restriction fragment length polymorphism (RFLP) of the ERα was determined using polymerase chain reaction (PCR). BMDs of the lumbar spine (L2–4) and proximal femur were measured by using dual-energy X-ray absorptiometry (DXA). At the baseline, there were no significant differences in the lumbar or femoral neck BMDs between the three ER PvuII genotype groups (PP,Pp,pp). After 5 years, the BMD of the femoral neck remained unaltered and that of the lumbar spine increased by 1.7% in the HRT group, whereas both BMDs were decreased by 4–5% in the non-HRT group. The ER genotype did not modulate the femoral neck BMD change during the follow-up. In contrast, in the non-HRT-group the lumbar spine BMD decreased more in subjects with the ER genotypes PP (6.4%) and Pp (5.2%) than in subjects with the pp genotype (2.9%) (p = 0.002). In the HRT group, the relative changes of the lumbar spine BMD were similar in all three ER genotype groups. Thus without HRT, the pp genotype was associated with a smaller decrease in the lumbar spine BMD than the Pp and PP genotypes. Long-term HRT seemed to eliminate the ER genotype-related differences in the BMD. We conclude that subjects with the ER PvuII genotypes PP and Pp may have a greater risk of relatively fast bone loss after menopause than those with the pp genotype and that they may preferentially derive benefit from HRT. (J Bone Miner Res 2000;15:315–321)