bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dexamethasone alters the subpopulation make-up of rat bone marrow stromal cell cultures
Authors: Herbertson Alexandra , Dr. Aubin Jane E. 
Published: February 2010

Abstract
Bone marrow stromal cells comprise a heterogeneous population including fibroblastic, adipocytic, hemopoietic, and osteogenic cells. Although the conditions under which different lineages are regulated have not been fully elucidated, dexamethasone clearly stimulates osteogenic expression in stromal cultures. The purpose of this study was to begin to elucidate and quantify some of the subpopulations present when rat bone marrow stromal cells are grown with or without dexamethasone under conditions favoring bone formation. Bone marrow stromal cells from young adult rats were cultured with ascorbic acid, β-glycerophosphate, and with or without dexamethasone for various periods of time. Culture dishes were then analyzed for cell counts, or stained with either histochemical or immunohistochemical stains, and colony types were quantitated, or cells were processed for flow cytometry. Dexamethasone significantly increased the number of alkaline phosphatase (AP) positive colonies, von Kossa positive bone nodules, α-naphthylbutyrate esterase positive colonies, and ED2 positive (macrophage) colonies. The number of adipocytic foci was largely unaffected in these experiments. Flow cytometry confirmed colony counts and showed stimulation by dexamethasone of AP positive cells and macrophages, and in addition, the reduction of hemopoietic cells expressing leukocyte common antigen. These data show conclusively that when rat bone marrow stromal populations are grown under conditions stimulating osteoprogenitor differentiation and bone formation, the stromal subpopulation make-up, including expression of hemopoietic lineages, is markedly altered.
Use of an in vivo model to determine the effects of interleukin-1 on cells at different stages in the osteoclast lineage
Authors: Uy Harry L. , Dallas Mark , Calland John W. , Boyce Brendan F. , Mundy Gregory R. , DR. Roodman David G. 
Published: February 2010

Abstract
In vitro model systems have been used extensively to study factors that affect osteoclast formation and to identify osteoclast precursors. However, in vitro systems do not examine the entire process of osteoclast differentiation simultaneously and lack accessory cells normally present in vivo. Additionally, the role that metabolism of the factor may play on its osteotropic activity in vivo is not addressed by these culture systems. Therefore, we have developed an in vivo model that permits us to examine simultaneously the effects of osteotropic factors on three distinct stages of osteoclast differentiation: (1) multipotent osteoclast precursors, the granulocyte-macrophage colony-forming unit (CFU-GM); (2) more differentiated marrow mononuclear osteoclast precursors; and (3) mature osteoclasts already present on bone surfaces. In the current study, we used interleukin-1 (IL-1) as a prototypic osteotropic factor to test the utility of this system to delineate the cellular mechanisms responsible for enhanced osteoclast activity stimulated by this cytokine. IL-1 induced hypercalcemia and enhanced the growth and differentiation of CFU-GM, increased the number of more committed mononuclear osteoclast precursors, and stimulated mature osteoclasts to resorb bone. These data demonstrate that this simple in vivo model permits the easy delineation of the stages of osteoclast development, in which osteotropic factors act to enhance bone turnover, and may be useful in understanding the mechanism of action of antiresorptive agents.
Bone resorption at the femoral neck is dependent on local factors in nonosteoporotic late postmenopausal women: An in vitro-in vivo study
Authors: Cohen-Solal M.E. , Graulet A.M. , Gueris J. , Denne M.A. , Bergot C. , Morieux C. , Sedel L. , Kuntz D. , Dr. de Vernejoul M.C. 
Published: February 2010

Abstract
Local mediators of bone resorption may be involved in bone loss in recently postmenopausal women and in osteoporosis. In the present study, we investigated the production of cytokines and the formation of osteoclast-like cells in marrow cultures from 16 late postmenopausal nonosteoporotic women (mean age: 66 ± 8 years; time after menopause: 15 ± 8 years) undergoing hip replacement for arthrosis. Marrow adherent mononuclear cells (MMNC) isolated from femoral diaphysis marrow were cultured for 10 days in the absence or in the presence of 1,25(OH)2D3. In vivo bone resorption was concomitantly assessed by histomorphometry on femoral neck bone sections. The number of TRAP+ multinucleated cells obtained after 10 days in MMNC cultured in the presence of 1,25(OH)2D3 correlated with the number of osteoclasts measured on the bone femoral neck biopsies (r = 0.65, p &lt; 0.01), suggesting that the formation of multinucleated cells in vitro could reflect the osteoclast differentiation in vivo. Furthermore, the number of osteoclasts was related to the eroded volume and the trabecular separation of the femoral neck bone biopsies. Finally, the release of interleukin-1 (IL-1), IL-6, and TNF-α by cultures of peripheral blood mononuclear cells (PBMC) and MMNC was measured by radioimmunoassay. The cytokine levels of basal and 1,25(OH)2D3-treated MMNC decreased from days 2 to 5 and then reached a plateau to day 10. The number of TRAP+ multinucleated cells obtained after 10 days in MMNC cultures correlated with the basal IL-6 release in the same cultures determined at day 2 (r = 0.55, p &lt; 0.01). IL-1 and IL-6 basal levels in PBMC and MMNC at day 2 were correlated (r = 0.53, r = 0.64, respectively; p &lt; 0.05), showing that cytokine production in peripheral blood reflects the local production in the marrow. Our data indicate that, in late postmenopausal women, local factors, and in particular IL-6, might be implicated in the bone-resorbing process, and that osteoclast activity might be responsible for micro-structural changes in the femoral neck.
Comparison of speed of sound ultrasound with single photon absorptiometry for determining fracture odds ratios
Authors: Stegman Mary Ruth , Heaney Robert P. , Recker Robert R. 
Published: February 2010

Abstract
The purpose of this study was to compare the ability of ultrasound velocity measurement with that of single photon absorptiometry to determine the odds of history of fracture since age 40, for a population-based study. To do this we computed odds ratios and 95% confidence intervals for 809 women and 502 men, aged 50 years and older, who are participants in the prospective phase of the Saunders County Bone Quality Study. These participants received both the ultrasound and single photon absorptiometry bone measurements at the initiation of the study. In addition, a history of all fractures that had occurred to participants since age 40 was obtained. The two bone assessment methods were compared by examining the magnitude of the odds ratios, to determine which produces the highest estimate of the probability of odds of fracture, and by examining widths of the respective confidence intervals to show which estimate of odds ratio is the most precise. Ultrasound velocity estimates a higher probability of odds of both low-trauma fractures and all fractures than distal radius and ulna bone mineral content, but lower than bone mineral density at the same sites for both women and men. However, the ultrasound measure is more precise than bone mineral density, but less precise than bone mineral content. We conclude that ultrasound velocity is as good as single photon absorptiometry in estimating odds of fracture.
Effect of 1,25-dihydroxyvitamin D3 treatment on bone formation by transplanted cells from normal and X-linked hypophosphatemic mice
Authors: Ecarot B. , Glorieux F.H. , Desbarats M. , Travers R. , Labelle L. 
Published: February 2010

Abstract
Bone cells isolated from the Hyp mouse, the murine homologue for hypophosphatemic vitamin D-resistant rickets, produce abnormal bone when transplanted to either normal or phosphate-supplemented Hyp mice. To assess whether correction of the bone formation by mutant cells transplanted into either normal or Hyp mice could be achieved in the presence of supraphysiologic serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), recipient mice of both genotypes were infused continuously with 1,25-(OH)2D3 (0.2 μg/kg/day). Bone nodules present in transplants recovered after 14 days were characterized by measuring the osteoid thickness and volume. Administration of 1,25-(OH)2D3 to Hyp mice corrected the defective bone formation by normal cells but not by pair-transplanted Hyp cells, despite normalization of serum phosphate levels and 3-fold increases in serum 1,25-(OH)2D3. The osteoid thickness and volume in Hyp transplants into 1,25-(OH)2D3-treated Hyp mice were, however, markedly reduced down to values observed for Hyp transplants into recipient normal mice. Administration of 1,25-(OH)2D3 to normal mice improved further bone formation by mutant cells without affecting that by pair-transplanted normal cells. Administration of 24,25-(OH)2D3 (1 μg/kg/day) combined with 1,25-(OH)2D3 to recipient mice of both genotypes prevented the sharp fall in serum 24,25-(OH)2D3 but was not more beneficial than 1,25-(OH)2D3 alone for improving bone formation by transplanted Hyp cells. These observations demonstrate an abnormal response of the mutant cells to the extracellular environment and support the concept of an intrinsic osteoblast defect in the Hyp mouse.
Expression and functional role of nitric oxide synthase in osteoblast-like cells
Authors: Riancho José A. , Salas Eduardo , Zarrabeitia María T. , Olmos José M. , Amado José A. , Fernández-Luna José L. , González-Macías Jesús 
Published: February 2010

AbstractNitric oxide synthases (NOS) are enzymes that produce nitric oxide (NO) from L-arginine in a reaction yielding citrulline as a coproduct. Nitric oxide modulates the activity of a wide variety of cells, but little is known about its effects on bone cells. In the present study we report that the NOS inhibitor NG-monomethyl-L-arginine (NMMA) induced a dose-dependent inhibitory effect on the proliferation of the osteoblast-like cell lines MG63 and ROS 17/2.8. The inhibitory effect was prevented by increasing L-arginine concentrations in the medium and by the NO donor sodium nitroprusside. Likewise, NMMA inhibited interleukin-6 secretion, independently of its effect on cell number. NOS expression by MG63 cells was confirmed by measuring their ability to metabolize radiolabeled L-arginine to citrulline. NOS bioactivity was detected in unstimulated cells, but was markedly increased by stimulating the cells with cytokines, lipopolysaccharide, or 1,25-dihydroxyvitamin D3. NOS activity was partially dependent upon the presence of calcium in the medium. Furthermore, constitutive-type NOS (c-NOS) and inducible-type NOS (i-NOS) mRNA expression was detected in ROS 17/2.8 cells after reverse transcription and polymerase chain reaction amplification. In conclusion, osteoblast-like cells express c-NOS and i-NOS, and NOS activity seems to play an important role in the regulation of cell proliferation and function.
Discriminative value of biochemical markers of bone turnover in assessing the activity of Paget's disease
Authors: Alvarez Luisa , Guañabens Nuria , Peris Pilar , Monegal Ana , Bedim Jose L. , Deulofeu Ramon , de Osaba M. Jesus Martinez , Muñoz-Gomez Jose , Rivera-Fillat Francisca , Ballesta Antonio M. 
Published: February 2010

Abstract
Clinical biochemical markers of bone turnover are usually increased in Paget's disease. However, the analysis of “new” markers, such as serum bone alkaline phosphatase (BAP), carboxy-terminal propeptide of type I procollagen (PICP), tartrate-resistant acid phosphatase (TRAP), telopeptide carboxy-terminal propeptide of type I collagen (ICTP), and urinary pyridinoline (PYR) and deoxipyridinoline (D-PYR), may improve the diagnostic efficacy and the evaluation of Paget's disease compared with conventional markers, such as serum total alkaline phosphatase (TAP) and urinary hydroxyproline (HYP). To evaluate the diagnostic accuracy and the changes of biochemical markers of bone turnover according to Paget's disease activity, we measured the levels of all these markers in three groups of pagetic patients classified according to their serum TAP activity: G-I, patients with serum TAP lower than 250 U/l (upper limit) (n = 15); G-II, patients with serum TAP between 251 and 500 U/l (n = 18); and G-HI, patients with serum TAP greater than 501 U/l (n = 26). Serum TAP and BAP showed the highest diagnostic accuracy among the markers of bone formation with a sensitivity of 78% and 84%, respectively, when the specificity was 100%. Urinary PYR was the most sensitive marker of bone resorption. Also, urinary PYR showed the highest proportion of increased values in pagetic patients (73%) compared with urinary HYP (64%), urinary D-PYR (60%), serum ICTP (41%), or serum TRAP (39%). In pagetic patients with normal serum TAP activity (G-I), serum BAP concentration was increased in 60% of patients, and urinary PYR was increased in 40% of patients. However, when serum TAP was greater than 500 U/l (G-III), almost all markers of bone formation and resorption were increased. These results suggest that when Paget's disease activity is high, most biochemical markers of bone turnover are increased. However, when the disease activity is low, serum BAP and urinary PYR improve the detection of such disease. Moreover, the determination of serum TAP activity and, to a similar extent, serum BAP concentration associated with the measurement of urinary PYR excretion provides the best biochemical approach for assessing Paget's disease activity.
Relations between histologic indices of bone formation: Implications for the pathogenesis of spinal osteoporosis
Authors: Parfitt A.M. , Villanueva A.R. , Foldes J. , Rao D. Sudhaker 
Published: February 2010

Abstract
Wall thickness, a major determinant of trabecular thickness, falls with age and falls further in osteoporosis. To estimate the importance of defective osteoblast recruitment in the pathogenesis of this defect, we compared various histologic indices of bone formation in iliac bone biopsies in three groups of subjects—healthy premenopausal women, healthy postmenopausal women, and patients with postmenopausal osteoporosis and at least one nontraumatic vertebral compression fracture. Indices that reflect the frequency of activation of bone remodeling and consequent birth rate of new teams of osteoblasts (osteoid surface, mineralizing surface, osteoblast surface, and bone formation rate, all expressed per unit of bone surface) were each higher in healthy subjects who were postmenopausal than in those who were premenopausal, but lower in osteoporotic than in normal postmenopausal women. In each group, the primary surface measurements were significantly correlated with each other, but the correlation was less close in those with osteoporosis. Indices that reflect the average collective performance of individual teams of osteoblasts (mineralizing surface and osteoblast surface per unit of osteoid surface, mineral apposition rate, adjusted apposition rate, and wall thickness) were all lower in postmenopausal than in premenopausal normal subjects, and even lower in those with postmenopausal osteoporosis. The parameters of the regression lines relating bone formation rate to osteoblast surface were essentially the same in each group, indicating that bone formation rate per unit of osteoblast surface was unaffected by age or menopause, and was the same in osteoporosis as in healthy subjects of similar age. We conclude that postmenopausal osteoporosis is characterized by a partial reversal of the menopause-related increases in histologic indices of bone formation that reflect activation frequency, and by an exaggeration of the age-related declines in the indices that reflect osteoblast team performance. Defective osteoblast recruitment makes a major contribution to the fall in wall thickness; this single defect can account for much of the age- and disease-related decline in osteoblast team performance.
Bone marrow cells are targets for the anabolic actions of prostaglandin E2 on bone: Induction of a transition from nonadherent to adherent osteoblast precursors
Authors: Dr. Scutt Andrew , Bertram Petrina 
Published: February 2010

Abstract
Although prostaglandin E2 (PGE2) is known to stimulate bone formation in vivo, its mechanism of action is not well understood. Circumstantial evidence suggests that bone marrow cells (BMC) may well be involved in this, and in order to investigate this further we have studied the effect of PGE2 on proliferation and matrix synthesis in high-density BMC cultures and on colony-forming unit (CFU-f) formation efficiency by BMC in vitro. High-density cultures of BMC formed a collagenous, calcified matrix, synthesized osteocalcin and expressed alkaline phosphatase activity. The addition of PGE2 caused a concentration-dependent increase in total (but not specific) APase activity, cell number, and collagen accumulation. It was found that PGE2 need only be present during the first 48 hours of the culture period and that longer exposure had no additional effect PGE2 also caused a concentration-dependent increase in CFU-f formation, and it was found that this was due to the recruitment of new mesenchymal precursor cells from the nonadherent fraction of the BMC. Once again, the presence of PGE2 for only the first 48 hours of the culture period was enough to precipitate a maximal response. We conclude that one mechanism for the anabolic actions of PGE2 may be the recruitment of OB precursors from a population of nonadherent mesenchymal precursor cells present in the bone marrow.
Shared phenotypic expression of osteoblasts and chondrocytes in fracture callus
Authors: Hughes Steven S. , Hicks David G. , O'Keefe Regis J. , Hurwitz Shepard R. , Crabb Ian D. , Krasinskas Alyssa M. , Loveys Luke , Puzas Edward J. , Rosier Randy N. 
Published: February 2010

Abstract
Endochondral ossification in fracture healing of rats at 4, 8, 11, 14, and 21 days was analyzed using immunological and molecular probes for markers of the chondrocyte and osteoblast phenotype. These markers were osteocalcin, type I and type II collagen, including the probes homologous to the alternatively spliced forms of α1 type II collagen, type IIA and type IIB. Histologic examination was performed on serial sections of the same tissue blocks to correlate cellular morphology with the immunohistochemical and in situ hybridization findings. At the junction of the cartilaginous and osseous tissue, an overlap of phenotype and morphology was noted. At the 8-day time point, the cells with chondrocyte morphology expressed intracellular message for osteocalcin and type I collagen. Immunohistochemical analysis of these cells also demonstrated intracellular osteocalcin. However, high levels of the type IIA collagen mRNA, which has previously been associated with less differentiated mesenchymal precursor cells, were expressed in both chondrocytes and osteoblasts. At the later time point (21 days) there was a substantial decrease in the number of cells displaying shared phenotypic characteristics. In situ hybridization and immuno-histochemistry have permitted identification of an overlapping or shared phenotype in osteoblasts and chondroblasts in fracture callus. The findings raise important questions regarding the possible plasticity of mesenchymal cell phenotypes within the dynamic environment of fracture healing. Additional examination of these issues will further define factors involved in origin, differentiation, and maturation of bone and cartilage cells.
Decreased mineralization and increased calcium release in isolated fetal mouse long bones under near weightlessness
Authors: Dr. Van Loon Jack J.W.A. , Bervoets Dirk-Jan , Burger Elisabeth H. , Dieudonn É Suzanne C. , Hagen Jan-Willem , Semeins Cor M. , Doulabi Behrouz Zandieh , Veldhuijzen Paul J. 
Published: February 2010

Abstract
Mechanical loading plays an important role in the development and maintenance of skeletal tissues. Subnormal mechanical stress as a result of bed rest, immobilization, but also in spaceflight, results in a decreased bone mass and disuse osteoporosis, whereas supranormal loads upon extremities result in an increased bone mass. In this first in vitro experiment with complete fetal mouse cartilaginous long bones, cultured under microgravity conditions, we studied growth, glucose utilization, collagen synthesis, and mineral metabolism, during a 4-day culture period in space. There was no change in percent length increase and collagen synthesis under microgravity compared with in-flight 1× gravity. Glucose utilization and mineralization were decreased under microgravity. In addition, mineral resorption, as measured by 45Ca release, was increased. These data suggest that weightlessness has modulating effects on skeletal tissue cells. Loss of bone during spaceflight could be the result of both impaired mineralization as well as increased resorption.
Characterization of the mouse tartrate-resistant acid phosphatase (trap) gene promoter
Authors: Reddy S.V. , Hundley J.E. , Windle J.J. , Alcantara O. , Linn R. , Leach R.J. , Boldt D.H. , Roodman G.D. 
Published: February 2010

Abstract
Tartrate-resistant acid phosphatase (TRAP) is an iron-binding protein that is highly expressed in osteoclasts. To characterize the regulation of TRAP gene expression, progressive 5′ and 3′ deletions of a 1.8 kb fragment containing the 5′-flanking sequence were fused to a luciferase reporter gene. Two nonoverlapping regions of this 1.8 kb fragment had promoter activity. The upstream promoter (P1) was located within the region from –881 bp to –463 bp relative to the ATG, while the downstream promoter (P2) was located between –363 bp to –1 bp in a region we have previously shown to be an intron in transcripts originating from the upstream promoter. A putative repressor region for the P2promoter at –1846 bp to –1240 bp and a putative enhancer region at –962 bp to –881 bp relative to the ATG were identified. PCR analysis of promoter-specific transcription of the TRAP gene in various murine tissues showed that both promoters were active in several tissues. Transferrin-bound iron increased P1promoter activity 2.5-fold and hemin decreased P1promoter activity, but neither had any effect on P2 activity. These data show that the transcriptional regulation of the TRAP gene is complex and that iron may play a key role in TRAP gene regulation.