bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of age on cyclosporin A-induced alterations in bone mineral metabolism in the rat in vivo
Authors: Katz Ian , Li Mei , Joffe Ian , Stein Barry , Jacobs Timothy , Liang Xiao Guang , Ke Hua Zhu , Jee Webster , Dr. Epstein Sol 
Published: February 2010

Abstract
Cyclosporin A (CsA) administered to actively growing young rats produces a high-turnover osteopenia. We investigated and compared the effect of CsA on the bone mineral metabolism in young rats with that of older rats, which have a lower rate of bone turnover. A group of 24 young (9 weeks) and 24 older (9 months) male Sprague-Dawley rats were orally administered 15 mg/kg of CsA or placebo daily for 24 days. Rats were weighed and serum assayed serially for bone gla protein (BGP), parathyroid hormone, ionized calcium, blood urea nitrogen, creatinine, and 1,25-dihydroxyvitamin D [1,25-(OH)2D]. After sacrifice, histomorphometric analysis was performed on undecalcified proximal tibial metaphysis with double-fluorescent labeling. Serum BGP levels were significantly elevated in both young and older rats administered CsA, and 1,25-(OH)2D levels were significantly elevated in CsA-treated young rats more than in older rats. Body weight was significantly reduced in CsA-treated older rats. There were mild but significant alterations in renal function in both groups receiving CsA. In the most comprehensive examination to date of the effects of CsA on bone histomorphometry, both young (-44%) and older rats (-20%) lost significant amounts of trabecular bone compared to their respective controls. Bone loss in young rats was mainly due to a reduced number of trabeculae; older rats lost mainly trabecular thickness. Microanatomic nodal studies were consistent with these results. These data demonstrate that although cancellous bone loss induced by CsA is more marked in young rats, older rats with slower bone turnover are also at risk.
Interleukin-6, IL-6 receptor, and IL-6 nuclear factor gene expression in paget's disease
Authors: Dr. Hoyland Judith A. , Freemont A.J. , Sharpe P.T. 
Published: February 2010

Abstract
The cytokine interleukin-6 (IL-6) is considered an important regulator of bone cell function and may play a central role in bone disease states characterized by increased bone remodeling, such as Paget's disease. Indeed, recent in vitro data suggest that IL-6 may be an autocrine/paracrine factor for pagetic osteoclasts. However, its expression and role in vivo are not known. Using in situ hybridization we investigated the spatial localization of expression of IL-6, IL-6 receptor (IL-6R), and the transcription factor (NF-IL-6) in pagetic bone. Our results show that osteoblasts in the normal remodeling bone of osteoarthritis (controls) and in Paget's disease express IL-6, IL-6R, and NF-IL-6 genes with higher levels of IL-6 and IL-6R mRNA in pagetic bone. Osteoclasts in both osteoarthritic and pagetic bone express IL-6R mRNA and NF-IL-6, but only pagetic osteoclasts expressed IL-6, suggesting that in Paget's disease IL-6 can act as an autocrine factor on osteoclasts. These results provide evidence for a major role of the IL-6 regulatory pathway in the phenotype of the pagetic osteoclasts and lead us to suggest a model linking possible paramyxovirus infection and IL-6 regulation in the pagetic osteoclast.
Long-term elevation of 1,25-dihydroxyvitamin D after short-term intravenous administration of pamidronate (aminohydroxypropylidene bisphosphonate, APD) in paget's disease of bone
Authors: Devlin Rowena D. , Retallack Robert W. , Fenton Anna J. , Grill Vivian , Gutteridge Donald H. , Kent Neil G. , Prince Richard L. , Worth Graeme K. 
Published: February 2010

Abstract
We report the prolonged biochemical changes that occurred in patients with Paget's disease when treated for 2–10 days with pamidronate disodium (3-amino-1-hydroxypropylidine-1,1-bisphosphonate, APD), by IV administration and observed for 6 months following therapy. In all 24 patients studied, bone resorption (measured by urinary hydroxyproline/creatinine ratio, OHP/Cr) fell sharply on treatment, from 0.12 ± 0.02 (mean ± SEM; above reference limits) to 0.04 ± 0.008 (reference range 0.006–0.027 for females, 0.005–0.020 for males), remaining at this level for 6 months after therapy. A fall in serum ionized calcium (Ca2+) to just below the reference limits with treatment (1.11 ± 0.02 mM; reference range 1.14–1.18 mM), followed by a rapid return to normal levels (1.14 ± 0.02 mM, mean ± SEM) within 8 days of treatment, was presumably due to the cessation of release of calcium from bone. This was followed by secondary hyperparathyroidism and a rise in serum 1,25-dihydroxyvitamin D [1,25-(OH)2D]. The hormonal responses, however, were profound. Serum immunoreactive PTH (iPTH) rose to twice pretreatment values (86 ± 11 pM, mean ± SEM; reference range for iPTH, &gt;50 years, &lt;50 pM; &lt;50 years, &lt;40 pM), returning to normal 4–8 weeks after therapy. Serum 1,25-(OH)2D levels rose to three times pretreatment values (300 ± 20 pM, mean ± SEM; reference range 50–150 pM), remaining above reference limits 4–8 weeks after therapy (188 ± 15 pM, mean ± SEM) and returning to normal values only after 12 weeks. The magnitude of the hormonal responses leads to speculation that factors other than serum calcium are involved in affecting these levels. Serum 24,25-dihydroxyvitamin D [24,25-(OH)2D] levels were below the mean of the reference range before treatment (3.93 ± 0.5 nM, mean ± SEM) and fell significantly with APD therapy (2.44 ± 0.25 nM, mean ± SEM), returning to pretreatment values only 12 weeks later (4.14 ± 0.35 nM). Serum 25-hydroxyvitamin D (25-OHD) did not change with treatment. We previously reported an increase in serum 1,25-(OH)2D levels in patients with Paget's disease treated with calcitonin (CT) or etidronate (EHDP). We now find a more pronounced and prolonged change in serum 1,25-(OH)2D with short-term IV APD treatment, which could indicate that with this bisphosphonate there is a long-term increase in gut calcium absorption. Also, 1,25-(OH)2D may play a role in the healing of pagetic lesions whether the treatment is CT, EHDP, or APD.
Transforming growth factor β increases ecto-nucleoside triphosphate pyrophosphatase activity of human bone-derived cells
Authors: Oyajobi Babatunde O. , Caswell Alison M. , Russell R. Graham G. 
Published: February 2010

Abstract
Inorganic pyrophosphate (PPi) may be involved in the regulation of mineralization. The cell surface enzyme, ecto-NTP pyrophosphatase, could be a major source of extracellular PPi in bone, and agents that influence its activity in osteoblasts may modulate bone mineralization. We studied the effects of serum on the ecto-NTP pyrophosphatase activity of cultured human osteoblast-like cells. Enzyme activity was lowered when the concentration of fetal calf serum (FCS) was reduced from 10 to 2.5% (vol/vol) for 48 h, and a further decrease in activity was observed after 96 h. Relative to enzyme activity in cells cultured in serum-free medium for 96 h, adult human platelet-poor plasma (HPPP; 2.5–10% vol/vol) induced a small increase, similar concentrations of adult human serum (HS) induced much larger increases, and charcoal-depleted FCS was ineffective. In an attempt to identify the factor(s) present in serum that influence ecto-NTP pyrophosphatase activity, we examined transforming growth factor-β (TGF-β) and platelet-derived growth factor (PDGF). PDGFs AA, AB, and BB (0.1–10 ng/ml) were ineffective, but both TGF-β1 and TGF-β2 increased enzyme activity. The increase was dose dependent between 0.001 and 10 ng/ml, was enhanced in the presence of 2% vol/vol FCS, and was not potentiated by PDGF or by 1,25-(OH)2D3. Furthermore, the increase was independent of cell density and was blocked by inhibitors of protein and RNA synthesis. Ecto-NTP pyrophosphatase of subject-matched human dermal fibroblasts was unaffected by TGF-β (10 ng/ml), suggesting that modulation of activity by the growth factor may be tissue specific. Alkaline phosphatase (ALP) probably serves to hydrolyze extracellular PPi in bone. In contrast to effects on NTP pyrophosphatase activity in osteoblast-like cells, TGF-β1 and TGF-β2 (0.001–10 ng/ml) decreased ALP activity dose dependently after 72 h. By inducing opposing changes in ecto-NTP pyrophosphatase and ALP activities, TGF-β may increase extracellular PPi concentrations in osseous tissues and consequently modulate bone mineral properties in vivo.
Effect of the bisphosphonate risedronate on bone metastases in a rat mammary adenocarcinoma model system
Authors: Hall D. Greg , Stoica George 
Published: February 2010

Abstract
Risedronate (NE-58095) is a third-generation bisphosphonate with very potent antiresorptive activity but few toxic effects. The purpose of this work was to evaluate the effect of risedronate treatment on bone metastases produced in a rat breast cancer model. Berlin Druckrey IV rats inoculated with ENU1564 mammary adenocarcinoma cells were treated daily with risedronate or a saline placebo. Survival times, dictated by extraskeletal metastases (lung, heart, and brain), were not affected by risedronate treatment. Risedronatetreated animals had skeletal changes associated with decreased remodeling of bones undergoing endochondral ossification, most prominently affecting the appendicular skeleton. Despite the skeletal alterations induced by the treatment, the distribution of bone metastases throughout the surveyed skeletal sites was similar for treated and untreated animals. Bone metastases were enumerated in histologic sections of distal femur, spine, and skull. Tumor size was estimated from area measurements obtained from histologic lesions in distal femoral metaphyses and vertebral bodies. A greater number of treated rats had no bone metastases in any of the examined sections (30 versus 16.1% of untreated rats). Multiple bone metastases were observed less frequently in treated rats (33.3 versus 71% of untreated rats). Treated rats had fewer observed bone metastases in each examined site than untreated rats (p ≤ 0.025). Mean tumor areas in femora and vertebrae were smaller in treated rats (p ≤ 0.05), due to the less frequent presence of very large lesions. In untreated animals, osteoclasts appeared to be active at the tumor/bone interface and osseous structures were often completely replaced by expanding tumors. In contrast, metastases in treated animals caused less disruption of skeletal histoarchitecture. The apparent lack of osteoclastic activity and retention of bone within lesions suggested a decreased contribution of osteoclasts to the bone resorptive process. An in vivo immunohistochemical cell proliferation assay failed to reveal differences in the percentage of dividing tumor cells in bone metastatic sites in treated versus untreated animals. The results demonstrate significant effects of risedronate treatment on the incidence and size of observed skeletal metastases in this model.
Comparison of the effects of 3,5,3′-triiodothyroacetic acid and triiodothyronine on bone resorption in cultured fetal rat long bones and neonatal mouse calvariae
Authors: Kawaguchi Hiroshi , Pilbeam Carol C. , Woodiel Florence N. , Raisz Lawrence G. 
Published: February 2010

Abstract
Thyroid hormones can stimulate bone resorption both directly and indirectly by increasing endogenous prostaglandin (PG) synthesis. Because 3,5,3′-triiodothyroacetic acid (Triac, Tiratricol) can bind to nuclear thyroid hormone receptors with high affinity, we compared the effects of Triac and 3,5,3′-triiodothyronine (T3) on bone resorption. 45Ca release was measured at 2, 5, and 8 days from 19-day-old-fetal rat long bones in the presence or absence of calcitonin, indomethacin, aphidicolin (APC), cortisol, or interleukin-1 receptor antagonist (IL-1ra). Both Triac and T3 stimulated 45Ca release in a dose-dependent manner. The maximal treated/control ratio (T/C) for Triac (10−7 M) was 1.6 ± 0.1 at 2 days and 2.5 ± 0.1 at 5 days and, for T3 (10−7 M), 1.5 ± 0.1 at 2 days and 2.6 ± 0.1 at 5 days. These responses were smaller and slower than that to PTH. Significant stimulation of resorption was observed at 10−8, 10−9, and 10−10 M for Triac but only at 10−8 and 10−9 M for T3. Indomethacin (10−6 M) and IL-1ra (1 μg/ml) did not decrease the effects of Triac or T3. In contrast, calcitonin (10−9 M), APC (30 μM), and cortisol could all block the response to these hormones. These results indicated that the resorptive responses were not mediated by endogenous PG or IL-1 but were osteoclast mediated and dependent on DNA synthesis, suggesting that these hormones acted by stimulating replication of osteoclast precursors or other supporting cells. Thyroid hormones were less effective in 7-day-old neonatal mouse calvariae. A small but significant stimulatory effect on 45Ca release was observed with Triac at 10−7 M at 2 and 4 days, but not with T3, and this effect was abrogated by indomethacin. We conclude that Triac stimulates bone resorption with a potency equal to or greater than that of T3. The effects of thyroid hormones were PG-independent in fetal rat long bones and PG-dependent in neonatal mouse calvariae. Since T3 may be converted to Triac in fasting and nonthyroidal illness, we speculate that Triac could mediate bone loss in these catabolic low-T3 states.
Injection of bovine parathyroid poly(A)+ RNA into xenopus oocytes confers sensitivity to high extracellular calcium
Authors: Chen Tsui-Hua , Pratt Stacy A. , Shoback Dolores M. 
Published: February 2010

Abstract
Parathyroid cells detect increments in the extracellular [Ca2+], which lead to substantial increases in intracellular free Ca2+ ([Ca2+]i) and, ultimately, to suppression of parathyroid hormone (PTH) secretion. To determine whether mRNA from parathyroid tissue could confer sensitivity to high extracellular Ca2+, we isolated and injected total bovine parathyroid poly(A)+ RNA into Xenopus laevis oocytes. To assess translational activity of the RNA, PTH released into the media was measured. Intact PTH was detected in the medium for ≤48 h, and injection of increasing amounts of RNA (∼0.5–50 ng/oocyte) led to the release of greater quantities of PTH. We screened for the expression of a putative Ca2+ sensor molecule by measuring 45Ca efflux from preloaded oocytes, in response to raising extracellular [Ca2+] from 0.7 to 5.7 mM. This increment in [Ca2+] stimulated 45Ca efflux by 249 ± 52 cpm over 20 min from eggs injected with parathyroid poly(A)+ RNA (n = 22). This response was significantly greater than 45Ca efflux from any group of controls exposed to the same change in extracellular Ca2+ (p &lt; 0.02), including oocytes injected with either water, cRNA for the platelet-derived growth factor (PDGF) BB receptor, or T cell poly(A)+ RNA. Size-fractionation of poly(A)+ RNA over sucrose gradients demonstrated that mRNA, which induced responsiveness to high extracellular Ca2+, was present in fractions with transcripts of ˜5–9 kB. Injection of these fractions also conferred sensitivity to the presence of Ba2+ or Sr2+ (both at 5 mM) in the media. These findings establish that parathyroid cells express mRNA for a molecule capable of detecting changes in the extracellular divalent cation concentration. This molecule may play a role in secretory responses mediated by Ca2+ in the parathyroid.
Evidence for both generalized and regional low bone mass among elderly women
Authors: Dr. Davis James W. , Ross Philip D. , Wasnich Richard D. 
Published: February 2010

Abstract
The consistency of bone mass measurements across bone sites was examined in a cohort of elderly Japanese-American women. The study included 744 women of mean age 66.6 years (age range 47–82 years) who had bone densitometry measurements at the spine, calcaneus, and distal and proximal radius. The women were classified at the four bone sites as in the lower, middle, or upper bone mass tertile for their age. Slightly more than half (56%) of the women were in the lower tertile at one or more of the bone sites, and such women were usually in the lower category at more than one site. Of the women, 24% were classified in the lower tertile at all four sites. Furthermore, as a group, women classified as in the low bone mass category at any one site had a low average bone mass at all four sites. Prospectively, the number of low bone mass sites predicted the risk of new spine fractures after adjusting for age and the number of spine and nonspine prevalent fractures. The risk increased approximately 1.3-fold for each additional low bone mass site. A subgroup (15%) of the population had marked heterogeneity in bone mass between sites. These women had one or more lower tertile bone mass site(s) and one or more upper tertile bone mass site(s). The results suggest that osteoporosis may occur as either a generalized or as a regional disorder.
Effects of medium acidification by alteration of carbon dioxide or bicarbonate concentrations on the resorptive activity of rat osteoclasts
Authors: Arnett Timothy R. , Boyde Alan , Jones Sheila J. , Taylor M. Louise 
Published: February 2010

Abstract
Little is known about the extracellular conditions or factors that stimulate mature osteoclasts to resorb mineralized tissues. Isolated mammalian osteoclasts are strongly stimulated by protons in HEPES-buffered culture media in the absence of CO2 and HCO3−, but it has been reported that cell-mediated Ca2+ release from bone organ cultures is increased only when media are acidified by reduction of HCO3− concentrations, and not by increasing Pco2 (considered models of metabolic and respiratory acidosis, respectively). We investigated this question using disaggregated rat osteoclasts cultured on dentin slices for 24 h. The number of pits resorbed per osteoclast was stimulated in media acidified by manipulation of either HCO3− or CO2 concentrations. In experiments in which incubator CO2 was varied, resorption was almost abolished in the presence of 2.5% CO2 at pH 7.61 but increased in a stepwise manner up to 1.3 pits per osteoclast when dentin slices were cultured with 10% CO2 at pH 6.97. The depths and widths of pits, measured using a confocal laser reflection microscope, also tended to increase with increasing CO2 and decreasing pH. However, in experiments where pH was lowered by reducing medium HCO3−, pit size decreased, partially offsetting the increased number of pits resorbed per osteoclast. These findings suggest that rat osteoclasts may be more sensitive to stimulation by CO2 acidosis than by HCO3− acidosis, at least in the short term, and may possibly reflect local regulatory processes in bone.
Effects of kistrin on bone resorption in vitro and serum calcium in vivo
Authors: King Kathleen L. , D'Anza James J. , Bodary Sarah , Pitti Robert , Siegel Mark , Lazarus Robert A. , Dennis Mark S. , Hammonds R. Glenn , Kukreja Subhash C. 
Published: February 2010

Abstract
In many cell systems, cell-cell and cell-matrix interactions are mediated by integrins, a family of cell surface heterodimeric glycoprotein receptors. Osteoclast integrins may play a role in the process of bone resorption. Osteoclasts express the αv and β3 subunits of the vitronectin receptor and adhere to a wide range of proteins in vitro, all of which contain the amino acid sequence Arg-Gly-Asp (RGD), an adhesion site recognition sequence common to many protein ligands that bind to integrins. The effect of kistrin, an RGD-containing snake venom protein, on osteoclast-mediated bone resorption was investigated in vivo and in vitro. When kistrin was infused into normocalcemic and hypercalcemic mice, serum calcium was significantly lowered at 3 and 6 h after the start of infusion, indicating an inhibitory effect on osteoclast activity in vivo. In vitro, kistrin potently inhibited bone resorption by isolated rat osteoclasts cultured on slices of bovine bone, and kistrin also inhibited the attachment of 293 cells expressing recombinant human αvβ3 to fibrinogen (IC50 = 1 nM). These results indicate the potential therapeutic use of RGD-containing molecules for hypercalcemia of malignancy or for other disorders associated with bone loss.
Effect of ipriflavone on expression of markers characteristic of the osteoblast phenotype in rat bone marrow stromal cell culture
Authors: Notoya Kohei , Yoshida Keiji , Tsukuda Ryoichi , Taketomi Shigehisa 
Published: February 2010

Abstract
The effects of ipriflavone on cellular proliferation and differentiation of osteoblasts were investigated using stromal cells isolated from the femoral bone marrow of young rats. To induce the formation of mineralized bone-like tissue in vitro, the cells were cultured in the presence of β-glycerophosphate and dexamethasone. Ipriflavone was added when subculturing was started. After 14 days of culturing with ipriflavone (10−7-10−5 M), increases in both the alkaline phosphatase activity and the hydroxyproline content per culture dish and a slight decrease in the saturated cell density were observed. Furthermore, continuous treatment with ipriflavone for 14–33 days resulted in an increase in the area of bone-like mineralized tissue accompanied by an increase in the secretion of osteocalcin. When culture medium lacking dexamethasone was used, rat bone marrow stromal cells neither differentiated into osteoblasts nor formed bone-like tissue, and under these conditions, ipriflavone had no effect on the proliferation or the phenotypic expression of the cells. These results suggest that ipriflavone directly stimulates markers of the osteoblast phenotype at a certain stage in bone formation without affecting undifferentiated cells that have not been committed to the osteogenic lineage.
Macrophage colony-stimulating factor restores bone resorption in op/op bone in vitro in conjunction with parathyroid hormone or 1,25-dihydroxyvitamin D3
Authors: Morohashi Tomio , Corboz Véronique Antonioli , Fleisch Herbert , Cecchini Marco G. , Felix Rolf 
Published: February 2010

Abstract
The in vivo administration of macrophage colony-stimulating factor (M-CSF) restores osteoclastogenesis and bone resorption in the op/op murine osteopetrosis. In vitro, exogenous M-CSF has been shown to be necessary for the generation of osteoclast-like cells in cocultures of hematopoietic and mesenchymal cells obtained from this mutant. In this study we investigated the capacity of M-CSF and other cytokines and hormones, alone or in combination, to induce bone resorption in explants of op/op metatarsals and metacarpals prelabeled with 45Ca. The effect on bone resorption was verified by counting the number of osteoclasts generated in the mineralized matrix. No osteoclast formation and no bone resorption were observed in the absence of M-CSF. M-CSF alone had only a slight effect at the high concentration of 104 units/ml. Addition of PTH or 1,25-(OH)2D3 together with M-CSF induced both osteoclastogenesis and bone resorption. The release of 45Ca was linear with time up to 15 days. PTH or 1,25-(OH)2D3 could not be substituted by TNF-α or IL-1, whereas IL-6 had a weak effect. M-CSF could not be replaced by GM-CSF. This study further emphasizes the role of M-CSF, PTH, and 1,25-(OH)2D3 in osteoclastogenesis.