bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prostaglandin E2 administered by subcutaneous pellets causes local inflammation and systemic bone loss: A model for inflammation-induced bone disease
Authors: Desimone Daniel P. , Greene Virginia S. , Hannon Kathleen S. , Turner Russell T. , Bell Norman H. 
Published: February 2010

AbstractThe effects of prostaglandin E2 (PGE2) given in controlled-release pellets or by daily sc injection for 21 days on mineral homeostasis and bone histomorphometry were compared in 7-week-old female rats. Sham operation and ovariectomy were performed at the beginning of the studies. In experiment 1, 7.5 mg PGE2 or drug-free, controlled-release pellets were implanted sc at the back of the neck on day 7. In experiment 2, 3 mg/kg body weight of PGE2 or vehicle was injected sc daily beginning on day 7. The animals were sacrificed on day 28 of the two experiments, and the tibiae were removed for histomorphometric analysis of the diaphysis and metaphysis. When administered by pellets in experiment 1, PGE2 lowered serum 1,25-dihydroxyvitamin D and did not influence weight gain, serum calcium, phosphorus, or magnesium, cross-sectional or medullary areas, periosteal bone formation and apposition rates, endosteal bone formation and apposition rates, or endosteal tetracycline-labeled perimeter. PGE2 lowered cancellous bone area and cancellous bone perimeter in both the sham-operated and ovariectomized rats. In contrast, when administered by sc injection in experiment 2, PGE2 reduced weight gain, increased serum magnesium, increased cortical area, and reduced medullary area without changing cross-sectional area, increased periosteal bone formation and apposition rates and endosteal bone and apposition rates, did not alter endosteal tetracycline-labeled perimeter, and increased cancellous bone area and cancellous bone perimeter in both sham-operated and ovariectomized animals. PGE2 produced local inflammation when given by pellets, and the serum concentration of 13,14-dihydro-15-ketoprostaglandin E2, the major metabolite of PGE2, increased when PGE2 was given by sc injection but not when administered by pellets. Thus, PGE2 given sc by controlled-release pellets (1) produces local inflammation and systemic bone loss without increasing PGE2 systemically and (2) provides a model for inflammation-induced loss of cancellous bone. The results also indicate that the pellet is not a valid means for the delivery of PGE2 to the general circulation.
Bone morphometric changes in adjuvant-induced polyarthritic osteopenia in rats: Evidence for an early bone formation defect
Authors: Bonnet Jacqueline , Zerath E. , Picaud N. , Lesur C. , Mattio A. , Tordjman C. , Hott M. , Marie P.J. 
Published: February 2010

Abstract
Adjuvant polyarthritis (AP) in rats is known to result in extensive bone loss. This study investigates the mechanisms responsible for the early trabecular osteopenia evaluated at a single point in time — 2 weeks after adjuvant injection—in the hindpaw of female Lewis rats using biochemical and histomorphometric methods. At this early point in time, the inflammation was generalized (inflammatory score, 20; albumin/globulin, —80% versus control). Histomorphometric analysis of the noninjected femur showed that the trabecular bone volume was significantly decreased (-28% versus control) in both proximal and distal parts, and the femur growth rate was unaffected. The trabecular osteopenia was associated with a 90% decrease in osteoid surface and a concomitant thinning (-19%) of the trabeculae. Both the double-fluorescence-labeled surface and the osteoblast surface were also markedly decreased (-75%). In addition, the mineral apposition rate was reduced (-50%) and the bone formation rate was decreased by as much as 90%. The trabecular bone volume was decreased in relation with the extent of double-fluorescence labeling (r = 0.38, p = 0.03) and bone formation rate (r = 0.42, p = 0.01), suggesting that the generalized osteopenia resulted from the reduced bone formation. This was associated with a 26% reduction in plasma osteocalcin. Neither the osteoclast surface nor the number of osteoclasts was consistently affected. However, urinary hydroxyproline was increased by 100–200%, which likely reflected the cartilage and bone destruction at the site of injection. The present data show that the early extensive osteopenia observed 2 weeks after AP induction in rats results from defective bone formation with unchanged bone resorption. The role of cytokines in such an inhibitory effect on bone formation remains to be determined.
Cross-sectional and longitudinal study of age-related phalangeal bone loss in adult females
Authors: Trouerbach W.T. , Vecht-Hart C.M. , Collette H.J.A. , Slooter G.D. , Zwamborn A.W. , Schmitz P.I.M. 
Published: February 2010

Abstract
To establish a comprehensive model for peripheral phalangeal bone loss, bone mass was studied in 1984 and 1989 using quantitative microdensitometry (QMD) in a total of 330 healthy women (age range 43–78.7 years). Bone mass and changes in bone mass were analyzed in relation to age and menopausal status. Ideal and nonideal populations were distinguished to assess the effect of diseases and medication. Both groups showed a decrease in bone mass, which proved to be more dependent on menopausal status than on age. A substantial loss started in the ideal group in the early postmenopausal period and in the nonideal group in the premenopausal period. Because the nonideal group started to lose bone at an earlier stage, the lifetime risk for osteoporosis is higher than in the ideal group.
Circulating PTHrP concentrations in tumor-induced hypercalcemia: Influence on the response to bisphosphonate and changes after therapy
Authors: Body J.J. , Dumon J.C. , Thirion M. , Cleeren A. 
Published: February 2010

Abstract
We studied the influence of circulating parathyroid hormone-related protein (PTHrP) concentrations on the response of hypercalcemic cancer patients to bisphosphonate therapy. We also examined the changes in circulating PTHrP levels during the normalization of serum Ca to determine if part of the increase in PTHrP concentrations is not secondary to hypercalcemia itself, as suggested by some in vitro data. We sequentially measured in 45 hypercalcemic cancer patients treated by pamidronate the circulating concentrations of PTHrP (by an amino-terminal RIA; normal values &lt;9 pmol/liter), Ca, Ca2+, Pi, intact PTH, and the fasting urinary excretion of Ca (Ca/Cr) and cyclic AMP (cAMP). Mean ± SEM baseline PTHrP levels were 9.5 ± 1.3, with a median (range) value of 6.0 (&lt; 3.4–43) pmol/liter. PTHrP levels were elevated in 18 of 45 patients, more often in epidermoid than in glandular carcinomas (P &lt; 0.05), and they were significantly (P &lt; 0.05) correlated with the concentrations of Pi (r = -0.46), Ca/Cr (r = -0.31), and urinary cAMP (r = 0.47). Mean pretreatment Ca levels were not significantly different between patients with elevated and patients with normal PTHrP levels, 13.3 ± 0.4 versus 12.9 ± 0.4 mg/dl, but the concentrations became significantly different (P &lt; 0.005) 4 days after therapy, 10.2 ± 0.3 versus 9.2 ± 0.1 mg/dl, respectively. The fall in fasting urinary Ca excretion was significantly (P &lt; 0.05 from day 4 to day 14) lower in patients with elevated baseline PTHrP levels: for example, Δ (day 4 - day 0), 0.31 ± 0.11 in patients with elevated PTHrP levels versus 0.64 ± 0.08 mg Ca per mg Cr in patients with normal PTHrP levels. In agreement with a lesser effect on serum Ca, intact PTH levels did not increase significantly in patients with elevated PTHrP levels, in contrast with a clear-cut recovery of PTH secretion in the other group. Last, PTHrP levels did not change significantly after bisphosphonate therapy: for example, at the day of the nadir of Ca, the levels were 8.2 ± 1.2 (6.4, &lt; 3.4–28) pmol/liter. In summary, our data suggest that circulating PTHrP concentrations do not change during correction of tumor-induced hypercalcemia but significantly influence the response to bisphosphonate therapy. Elevated PTHrP concentrations in hypercalcemic cancer patients thus constitute a primary phenomenon of pathogenic importance.
Development and characterization of a polyclonal antiserum-based radioimmunoassay for dog osteocalcin
Authors: Fanti Paolo , Colombo Giovanna , Yao Chinghua , Brown Stephen A. , Vernon Michael W. , Malluche Hartmut H. 
Published: February 2010

Abstract
Determination of the serum concentration of the protein osteocalcin (OC) is useful for the noninvasive evaluation of bone metabolism. Because the dog is an excellent experimental model for the study of bone, we produced and characterized a polyclonal antiserum specific for dog OC and used it to develop a radioimmunoassay (RIA) for the measurement of the concentration of this protein in dog serum. The antiserum expresses higher affinity for Ca2+-bound than for Ca2+-free OC (B50 at 10−5 versus 2 × 10−4 dilution). Also, in the presence of Ca2+ affinity is higher for the carboxylated than for the decarboxylated form of the protein, and under Ca2+-free conditions the affinity is equal for the two forms. The study of peptide fragments of OC demonstrates competitive binding of the peptide comprising amino acids 20–44 but not of other fragments; this suggests that the antigenic epitope of dog OC is located in the midmolecular region of the protein. The RIA displays excellent sensitivity for the measurement of OC in blood (detection limit 0.31 ng/ml), with intraassay and interassay variations of 4.6 and 6.8%, respectively. Analysis of gel chromatography fractions of normal dog serum shows that greater than 90% of the antigenic material coelutes with purified radiolabeled dog OC. Test of parallelism reveals lack of interference of serum constituents with the binding assay. The antiserum displays limited species specificity since it cross-reacts with human OC, but not with the protein from rodents. Consistent with previous observations in other in vivo models, the serum concentration of OC in experimental dogs is decreased significantly 7–10 days after thyroparathyroidectomy and it is unchanged 1 month following ovariohysterectomy.
Calcium retention and hormone levels in black and white women on high- and low-calcium diets
Authors: Dawson-Hughes Bess , Harris Susan , Kramich Carolyn , Dallal Gerard , Rasmussen Helen M. 
Published: February 2010

Abstract
Black-white differences in calcium metabolism are sought because they may reveal why blacks have higher bone mass than whites. Comparative studies of calcium absorption in blacks and whites are not available. In this study, we compare fractional calcium retention, an index of calcium absorption, and calcium regulating hormone levels in black and white women on a high-calcium diet and after adaptation to a low-calcium diet. A total of 30 healthy women (15 black and 15 white) had measurements of fractional 47Ca retention and calcium regulating hormone levels after 8 weeks on a 2000 mg calcium diet and, subsequently, after 1, 2, 4, and 8 weeks on a 300 mg calcium diet. By 2 weeks after the diet change, fractional 47Ca retention, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D [1,25-(OH)2D] had reached a plateau at higher levels, urine calcium at a low level, and serum calcium at the same level (repeated-measures ANOVA). Fractional 47Ca retention, serum calcium, and PTH were similar on both diets in blacks and whites. Blacks had higher levels of 1,25-(OH)2D on both diets (e.g., 125.1 ± 53.5 SD versus 73.4 ± 19.0 pmol/liter, P = 0.003 on low-calcium diet) and a greater increase in 1,25-(OH)2D after the diet change (33.9 ± 30.1 SD versus 11.8 ± 17.9 pmol/liter, P = 0.021). Serum phosphorus was lower in blacks throughout. For hormone levels and fractional calcium retention to stabilize after a diet change, 2 weeks was needed. Similar levels of fractional retention in black and white women despite higher levels of 1,25-(OH)2D in blacks suggest that blacks may have a gut resistance to the action of 1,25-(OH)2D.
Effects of transforming growth factor β1 and l-ascorbate on synthesis and distribution of proteoglycans in murine osteoblast-like cells
Authors: Takeuchi Yasuhiro , Matsumoto Toshio , Ogata Etsuro , Shishiba Yoshimasa 
Published: February 2010

Abstract
Proteoglycans synthesized by osteoblasts are incorporated into bone matrix and thought to play a role in bone metabolism. Transforming growth factor (TGF) β affects the synthesis of matrix proteins, including proteoglycans, in various stromal cells, and proteoglycans, especially decorin, are associated with matrix collagen. In the present study, the effects of TGF-β1 and L-ascorbate, a factor essential for collagen synthesis, on the synthesis and distribution of proteoglycans were examined using murine osteoblast-like MC3T3-E1 cells. TGF-β1 stimulated the synthesis of proteoglycans in MC3T3-E1 cells. Among various proteoglycans, the synthesis of decorin was preferentially enhanced by TGF-β1 and the effect was more pronounced on secreted decorin compared to that associated with the cell/matrix layer. TGF-β1 also stimulated the initiation and elongation of the dermatan sulfate glycosaminoglycan chain, resulting in a larger molecular size of decorin. TGF-β1 influenced the synthesis of a heparan sulfate proteoglycan only slightly. L-ascorbate had no effect on the synthesis of proteoglycans, but increased those associated with the cell/matrix layer. Furthermore, when L-ascorbate was added to the culture along with TGF-β1, the percentage of proteoglycans associated with the cell/matrix layer increased from 25.8 ± 1.0 to 41.0 ± 0.5%. These data demonstrate that TGF-β1 markedly stimulates the synthesis of proteoglycans, especially decorin, mainly as a secreting form, that the accumulation of decorin into matrix is enhanced by L-ascorbate, and that the effects of TGF-β1 and L-ascorbate are additive. Because L-ascorbate is required for the synthesis of collagen, the effect of L-ascorbate on the distribution of decorin appears to be due to its effect on collagen synthesis.
Effects of high extracellular calcium and strontium on inositol polyphosphates in bovine parathyroid cells
Authors: Shoback Dolores M. , Chen Tsui-Hua , Lattyak Bruce , King Kathleen , Johnson Randolph M. 
Published: February 2010

Abstract
The addition of Ca2+ or a variety of divalent cations increases intracellular Ca2+ in parathyroid cells and suppresses secretion. Since 1,4,5-inositol trisphosphate (IP3) and 1,3,4,5-inositol tetrakisphosphate (IP4) mediate Ca2+ mobilization in other systems, we examined high Ca2+- and Sr2+-induced accumulation of IP3 and IP4 isomers by anion-exchange HPLC and measured 1,4,5-IP3 mass in parathyroid cells. Raising extracellular [Ca2+] from 0.5 to 3.0 mM increased 3H-1,4,5-IP3 within 5 s, which was confirmed by mass measurements. 3H-1,3,4-IP3 rose gradually by 10 s and increased for 60 s after the addition of Ca2+. Although we detected no change in 3H-1,3,4,5-IP4, the increase in 3H-1,3,4-IP3 suggests that 3H-1,3,4,5-IP4 was being formed. The addition of 4 mM SrCl2 produced similar changes in 1,4,5-IP3, which were confirmed by mass assay. 3H-1,3,4,5-IP4 did not change. However, Sr2+ induced a gradual increase in 3H-1,3,4-IP3, which remained above control levels for 5 minutes. Isotopic labeling studies in this system may underestimate changes in 1,4,5-IP3 mass, but both mass and radioisotopic analyses indicate that high extracellular Ca2+ and Sr2+ stimulate substantial increases in 1,4,5-IP3 without significant accumulation of 1,3,4,5-IP4. These studies suggest a role for 1,4,5-IP3 in intracellular Ca2+ mobilization by divalent cations in parathyroid cells.
Linkage of extracellular and intracellular control of cytosolic Ca2+ in rat osteoclasts in the presence of thapsigargin
Authors: Zaidi Mone , Shankar Vijai S. , Bax Christopher M.R. , Bax Bridget E. , Bevis Peter J.R. , Pazianas Michael , Alam A.S.M. Towhidul , Moonga Baljit S. , Huang Christopher L.-H. 
Published: February 2010

Abstract
Cytosolic [Ca2+] was measured in single osteoclasts using fura-2 in experiments investigating the effects of Ca2+ “receptor” activation using thapsigargin as a means of depleting intracellular Ca2+ stores. Application of 4 μM thapsigargin to osteoclasts in Ca2+-free solutions resulted in an elevation of cytosolic [Ca2+]. Under similar conditions, activation of the osteoclast Ca2+ receptor by the substitute divalent cation agonist, Ni2+, resulted in a transient elevation of cytosolic [Ca2+]. In both instances, restoration of extracellular [Ca2+] to 1.25 mM resulted in an “overshoot” of cytosolic [Ca2+]. Prior depletion of intracellular Ca2+ stores by thapsigargin markedly reduced the magnitude of the cytosolic [Ca2+] response to a subsequent application of 5 mM Ni2+. The application of 2 μM thapsigargin to intercept the falling phase of the Ni2+-induced cytosolic Ca2+ signal resulted in a sustained elevation of cytosolic [Ca2+], which was terminated by a second application of the same Ni2+. Furthermore, the sustained elevation of cytosolic [Ca2+] induced by thapsigargin application alone was abolished by late application of Ni2+. We conclude that activation of the surface membrane Ca2+ receptor on the osteoclast results in the cytosolic release of Ca2+ from intracellular storage organelles; the refilling of such stores depends upon a thapsigargin-sensitive Ca2+-ATPase; store depletion induces capacitative Ca2+ influx; and the Ca2+ influx pathway is sensitive to blockade by Ni2+.
Electric fields modulate bone cell function in a density-dependent manner
Authors: Mcleod Kenneth J. , Donahue Henry J. , Levin Paul E. , Fontaine Marie-Anne , Rubin Clinton T. 
Published: February 2010

Abstract
The influence of an extremely low frequency (ELF) electric field stimulus (30 Hz at 6 μV/cm rms), known to promote bone formation in vivo, was evaluated for its ability to affect bone cell function in vitro. To accomplish this, we developed an apparatus for the exposure of monolayer cell systems to electric fields in a manner that provides relatively uniform electric field exposure of multiple cell samples as well as a rigorous sham exposure. We show that field exposure significantly limits the normal increase in osteoblastic cell number and enhances alkaline phosphatase activity compared to sham-exposed samples. Moreover, these alterations are shown to occur in a cell density-dependent manner. Samples plated at 6 × 103 cells/cm2 show no effect of field exposure. In samples plated at 30 × 103 cells/cm2, 72 h of field exposure resulted in 25% fewer cells in the exposed samples, and a doubling of alkaline phosphatase activity in those cells compared to sham exposure. Experiments using a 12 h exposure to preclude significant changes in cell number during the exposure show this density-dependent response to be biphasic. Sparse cultures (&gt;50 × 103 cells/cm2) were not found to be affected by the field exposure, but increases in alkaline phosphatase activity occurred in cultures at densities of 50–200 × 103 and 200–350 × 103 cells/cm2 and no effect on alkaline phosphatase activity was seen in confluent cell cultures of greater than 350 × 103 cells/cm2. This work suggests that the demonstrated osteogenic effect of this specific electric field stimulus on bone tissue may be initiated by an alteration of the differentiated status of the osteoblasts in the tissue rather than by stimulating cell proliferation, as has been previously suggested. As importantly, a more thorough characterization of this density-dependent interaction with electric fields may help to identify the mechanism of transduction by which ELF electric fields interact with cells.
Tumor necrosis factor α decreases 1,25-dihydroxyvitamin D3 receptors in osteoblastic ROS 17/2.8 cells
Authors: Mayur Nitin , Lewis Sharma , Catherwood Bayard D. , Nanes Mark S. 
Published: February 2010

Abstract
Bone remodeling is a complex process regulated by systemic hormones, local cytokines, and growth factors. One cytokine, tumor necrosis factor α (TNF-α), is known to have potent inhibitory effects on osteoblast matrix protein production and to stimulate osteoclast recruitment. We have previously shown that TNF-α inhibits 1,25-(OH)2D3-stimulated synthesis of bone gla protein (BGP), an abundant and osteoblast-specific matrix constituent. We hypothesized that the mechanism of TNF-α action included inhibition of intracellular 1,25-(OH)2D3 receptor (VDR) number or function. To test this, the osteoblastic cell line ROS 17/2.8 was cultured in the presence or absence of TNF-α (100 ng/ml), and binding of [3H]1,25-(OH)2D3 to 0.3 M KCl extracts of cytosol was measured by equilibrium assay. Specific [3H]1,25-(OH)2D3 binding decreased 70%, 25 h after addition of TNF-α. The decrease in [3H]1,25-(OH)2D3 binding was seen by 18 h, was sustained throughout the 72 h culture period, and was greater in low-density cultures. Scatchard analysis confirmed that TNF-α (100 ng/ml for 24 h) caused a decrease in the number of binding sites without change in VDR affinity. Northern analysis with a VDR riboprobe revealed that the decrease in VDR occurred without a change in the 4.4 kb steady-state VDR mRNA [VDR/cyclophilin mRNA signal ratio: control, 2.25; TNF-α, 2.24 (24 h),2.17 (40 h), n = 2 flasks/time point]. These results suggest that TNF-α action on osteoblastic cells includes an inhibitory effect on VDR number at a point distal to the synthesis of VDR mRNA.
Distribution of noncollagenous proteins in the matrix of adult human bone: Evidence of anatomic and functional heterogeneity
Authors: Ingram Ronald T. , Clarke Bart L. , Fisher Larry W. , Fitzpatrick Lorraine A. 
Published: February 2010

Abstract
The microanatomic distribution of several noncollagenous proteins (NCPs) in bone matrix was examined by immunohistochemical analysis of glycol-methyl methacrylate-embedded normal adult human bone biopsies. Osteopontin and bone sialoprotein stained throughout the lamellae of both trabecular and cortical bone. Cement lines (cortical and trabecular) and the mineralized matrix immediately adjacent to each Haversian canal were intensely stained. Osteocalcin was detected in cement lines; however, lamellar staining varied depending on the location within the individual unit of bone. In cortical bone, the inner concentric lamellae of osteons were often unstained but the outer lamellae were heavily stained for osteocalcin. Osteonectin was not detected in cement lines and in most specimens revealed a pattern similar to that of osteocalcin with respect to the absence of immunostaining within the inner concentric lamellae. Decorin was prominent in the perilacunar matrix, the canaliculi of osteocytes, and the matrix immediately adjacent to quiescent Haversian canals. Biglycan appeared evenly distributed throughout cortical and trabecular bone matrix. These results suggest that the incorporation of NCPs into matrix may vary depending on the stage of formation of individual bone units. The specific distribution and spatial relationship of these NCPs may be related to the function of each protein during bone resorption and formation. The distinct patterns of NCP localization in bone support the hypothesis that in addition to their structural and mineral-inducing properties, these proteins may influence the events associated with bone remodeling, such as recruitment, attachment, differentiation, and activity of bone cells.