bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum insulin-like growth factor binding protein-3 in the hypophosphatemic mouse: Decreased activity and abnormal modulation by dietary phosphate
Authors: Moriwake T. , Abribat T. , Brazeau P. , Ecarot B. 
Published: February 2010

Abstract
The hypophosphatemic mouse, the murine homologue of X-linked hypophosphatemia, is characterized by renal defects in phosphate reabsorption and 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) production and by an osteoblast dysfunction. In view of the potential importance of insulin-like growth factors (IGFs) in the regulation of these processes and the role of IGF-binding proteins (IGFBPs) as modulators of IGF action, we asked whether Hyp mice have alterations in IGFs or IGFBPs. Using specific radioimmunoassays and Western ligand blot analysis, we evaluated serum levels of IGFs (IGF-I and IGF-II) and IGFBPs, respectively, in normal and Hyp mice. We also examined the effect of dietary phosphate on these parameters. Serum levels of IGF-I and IGF-II in Hyp mice were not significantly different from those in normal mice, but IGFBP-3 levels were significantly lower (70% of normal, p &lt; 0.05) in the mutant strain. The other IGFBP species appear unchanged. Phosphate supplementation normalized serum phosphate levels in Hyp mice and elicited a significant decrease in serum IGF-I levels (23%, p &lt; 0.05) and a further reduction in IGFBP-3 (22%, p &lt; 0.02). Phosphate deprivation induced hypophosphatemia in normal mice to a degree similar to that in Hyp mice and did not alter serum levels of IGFBP-3 and IGF-I and IGF-II. The present results indicate that the low serum IGFBP-3 activity in Hyp mice is not related to hypophosphatemia per se. Based on the documented effects of parathyroid hormone (PTH) on IGF-I and IGFBP-3, we propose that the secondary hyperparathyroidism displayed by Hyp mice and its exacerbation by phosphate supplementation may contribute to low IGFBP-3 levels in control Hyp mice and to the decreases in serum IGF-I and IGFBP-3 in phosphate-supplemented Hyp mice.
Ultrastructural immunodetection of osteopontin and osteocalcin as major matrix components of renal calculi
Authors: McKee M. D. , Nancl A. , Khan S. R. 
Published: February 2010

Abstract
The organic matrix of renal calculi has long been considered to influence the crystal growth that occurs in these pathological mineral deposits. Recent advances in characterizing individual organic moieties from mineralized tissues in general and the combined use of antibodies raised against these molecules with different immunocytochemical approaches have allowed their precise distribution to be visualized in a variety of normal and pathological mineralized tissues. The present ultrastructural study reports on the epithelial expression and extracellular localization of several noncollagenous proteins in rat and human kidney stones using high-resolution colloidalgold immunocytochemistry. To this end, we have examined in an ethylene glycol-induced calcium oxalate model of urolithiasis in the rat, and in human kidney stones, the distribution of certain noncollagenous and plasma proteins known to accumulate in bone and other mineralized tissues that include osteopontin, osteocalcin, bone sialoprotein, albumin, and α2HS-glycoprotein. Of these proteins, osteopontin (uropontin) and osteocalcin (or osteocalcin-related gene/protein) were prominent constituents of the calcium oxalate-associated crystal “ghosts” found in the nuclei, lamellae, and striations of the organic matrix of lumenal renal calculi in the rat and of small crystal ghosts found within epithelial cells. Immunocytochemical labeling for both proteins of the content of secretory granules in tubular epithelial cells from treated rats, together with labeling of a similarly textured organic material in the tubular lumen, provides evidence for cosecretion of osteopontin and osteocalcin by epithelial cells, their transit through the urinary filtrate, and ultimately their incorporation into growing renal calculi. In normal rat kidney, osteopontin was localized to the Golgi apparatus of thin loop of Henle cells. In human calcium oxalate monohydrate stones, osteopontin was similarly detected in the lamellae and striations of the organic matrix. Based on these data, it is proposed that during urolithiasis, secretion of osteopontin (uropontin) and osteocalcin (or osteocalcin-related gene/protein), and the subsequent incorporation of these proteins into kidney stone matrix, may influence the nucleation, growth processes, aggregation, and/or tubular adhesion of renal calculi in mammalian kidneys.
End labeling studies of fragmented DNA in the Avian growth plate: Evidence of apoptosis in terminally differentiated chondrocytes
Authors: Hatori Masashi , Klatte Kevin J. , Teixeira Cristina C. , Dr. Shapiro Irving M. 
Published: February 2010

Abstract
The chondro-osseous junction has been the subject of considerable scrutiny, especially in terms of the fate and role of the terminally differentiated chondrocyte. Although it has been proposed that these cells change their phenotype and survive in the epiphysis, possibly as osteoblasts, evidence from a number of other studies suggests that chondrocytes may undergo apoptosis or programmed cell death. A useful test for programmed cell death is to end label DNA in cryosections using the commercial reagent ApopTagTM and detect antibody binding to fragmented DNA by epifluorescence; more direct assessments include examination of the nucleus for condensation of chromatin, evaluating fragmentation through alkaline and pulsed field agarose gel electrophoresis of DNA, and measuring apoptosis by flow cytometry. We found that we could label cells in the proliferative and the hypertrophic region of the proximal tibial growth plate of the chick with ApopTag. Most of the chondrocytes in the hypertrophic region were labeled by the reagent; in contrast, few proliferative chondrocytes were stained by the end-labeling procedure. Both agarose and pulsed field electrophoresis were used to confirm that there was fragmentation of chondrocyte DNA. Alkaline gel electrophoresis indicated that there was more fragmentation of DNA from hypertrophic cells than from proliferative chondrocytes. Further evidence in support of apoptosis was provided by electron microscopic observation of cells in the hypertrophic region of the growth plate. We noted that many of the cells in this region of the growth plate appeared to be undergoing programmed cell death since their nuclei contained condensed chromatin. Finally, we used flow cytometry to analyze chondrocytes isolated from the proliferating and hypertrophic regions of the growth plate for apoptosis. Dual parameteric flow cytometric contour plots of Hoechst and 7-amino-actinomycin D fluorescence showed that about 8% of cells in the plate were apoptotic. Most of these cells were in hypertrophic cartilage. In summary, the results of this investigation indicate that chondrocytes terminate their life history by apoptosis. While it is possible that the terminal labeling studies may overestimate the number of cells undergoing this event, the data lend credence to the view that cells are removed from the epiphysis through apoptosis. If this is the case, then chondrocytes probably enter the terminal phase of their life as fully functioning cells and genomic, and/or local environmental conditions provide termination signals that initiate events that lead to programmed cell death.
Aluminum inhibits both initiation and progression of mineralization of osteoid nodules formed in differentiating rat calvaria cell cultures
Authors: Dr. Bellows C. G. , Aubin J. E. , Heersche J. N. M. 
Published: February 2010

Abstract
Osteoid nodules form in cultures of fetal rat calvaria (RC) cells grown in medium containing 10% fetal bovine serum (FBS) and 50 μg/ml of ascorbic acid. When 10 mM β-glycerophosphate (β-GP) is added, the nodules mineralize in two phases: an initiation phase that is dependent upon alkaline phosphatase activity for cleavage of β-GP to inorganic phosphate (P1) and a progression phase that proceeds independently of the activity of alkaline phosphatase and does not require exogenous phosphate. We have used this system to investigate the effects of aluminum (Al3+) on mineralization. When AlCl3 was added to culture medium at concentrations of 0, 3, 10, 30, 100, and 300 μM, the total concentrations of aluminum were 0.98, 6.07, 16.82, 40.19, 88.45, and 284.52 μM, respectively. The corresponding free Al3+ concentrations, assessed after ultrafiltration, were found to be 1.11, 1.75, 3.40, 6.22, 5.38, and 12.11 μM. In cultures in which osteoid was formed and mineralization initiated in the presence of added Al3+ (3–300 μM), a dose-dependent inhibition of mineralization occurred. Osteoid formed in the presence of added Al3+ mineralized normally when Al3+ was removed from cultures at the time of initiation of mineralization with β-GP. In osteoid nodules grown in the absence of Al3+, addition of Al3+ (3–300 μM) at the start of the initiation phase of mineralization resulted in a dose-dependent inhibition of mineralization. Addition of Al3+ to cultures after mineralization had been initiated in the absence of Al3+ inhibited progression of mineralization at added Al3+ concentrations of 10 μM and above. Al3+ did not decrease the conversion of β-GP to Pi and caused a small but significant increase in alkaline phosphatase activity at added concentrations of 100 μM or greater. The data show that Al3+ inhibits both the initiation and progression phases of mineralization starting at added concentrations of 3–10 μM (∼1.7–3.4 μM free Al3+) and that mineralization of osteoid formed in the presence of Al3+ is unaffected if Al3+ is removed prior to the initiation of mineralization.
Heterogeneity of the skeleton: Comparison of the trabecular microarchitecture of the spine, the iliac crest, the femur, and the calcaneus
Authors: Amling Michael , Herden Stephan , Pösl Martin , Hahn Michael , Ritzel Holger , Delling Günter 
Published: February 2010

Abstract
The objective of this study was to elucidate the structure of cancellous bone and its age-related changes at different skeletal sites. Therefore, the lumbar spine, iliac crest, femur, and calcaneus of 12 age- and sex-matched skeletal healthy autopsy cases (6 females, 6 males, aged 28–84 years, mean 54 years) were removed. The following analysis includes an evaluation of the trabecular bone volume (BV/TV, %) and the trabecular interconnection (TBPf, mm−1) as well as a qualitative investigation of the structure of trabecular bone. BV/TV shows the following mean values: lumbar spine, 8.3% (±0.8%); iliac crest, 11.5% (±1.6%); intertrochanteric, 10.2% (±1.2%); femoral neck, 15.8% (±1.6%); and calcaneus, 15.4% (±2.0%). There are significant differences between the BV/TV of the femoral neck and that of the lumbar spine as well as between that of the calcaneus and the lumbar spine (p &lt; 0.01). However, a positive correlation can be seen between the bone mass of the spine and that of all other investigated sites (r = 0.67 tor = 0.80; Pr &lt; 0.1). The trabecular interconnection of the lumbar spine (2.7 mm−1, SEM ± 0.2 mm−1) and the femoral neck (0.3 mm−1, SEM ± 0.3 mm−1) differs significantly. Only these two sites show a significant positive correlation of TBPf (r = 0.60; pr &lt; 0.1). Age-dependent alteration of the spine and the femoral neck in bone mass and bone structure is nearly the same. The trabecular microarchitecture of the iliac crest varies systematically. A region 4–10 cm behind and 1–3 cm below the anterior superior iliac spine turns out to be the most suitable biopsy site because of its closest relation to the lumbar bone mass. However, drawing information about the trabecular interconnection within the lumbar spine by measurement of the iliac crest at any site seems to be impossible. The horizontal specimens reveal a vertical running tubular spongiosa pattern that is arranged in concentric rings starting from the dorsal shell like a honeycomb. The comparison of TBPf in horizontal and vertical planes and its age-related changes indicates the age-related bone loss to be predominantly a loss of horizontal trabeculae. Thus, the presented data provide further information about the skeletal distribution and heterogeneity of the trabecular microarchitecture.
Prostaglandin E2 stimulates osteoclast-like cell formation and bone-resorbing activity via osteoblasts: Role of cAMP-dependent protein kinase
Authors: Kaji Hiroshi , Sugimoto Toshitsugu , Kanatani Masanori , Fukase Masaaki , Kumegawa Masayoshi , Chihara Kazuo 
Published: February 2010

Abstract
Prostaglandin E2 (PGE2) is an important local regulator in bone. The present study was performed to investigate the effect of PGE2 on osteoclast-like cell formation and bone-resorbing activity of mature osteoclasts in the presence or absence of osteoblasts. PGE2 (10−8 to 10−6 M) significantly stimulated osteoclast-like cell formation in osteoblast-containing mouse bone cell cultures, although it did not affect osteoclast-like cell formation from hemopoietic blast cells supported by granulocyte-macrophage colony-stimulating factor in osteoblast-free mouse spleen cell cultures. The conditioned medium from osteoblastic UMR-106 cells pretreated with PGE2 (10−8 to 10−6 M) significantly stimulated osteoclast-like cell formation from hemopoietic blast cells. PGE2 also significantly stimulated the bone-resorbing activity of mature osteoclasts in osteoblast-containing mouse bone cell cultures. In contrast, PGE2 significantly inhibited the bone-resorbing activity and osteopontin mRNA expression in isolated rabbit osteoclasts. Rp-cAMPS, a direct protein kinase (PKA) antagonist, significantly inhibited PGE2-stimulated osteoclast-like cell formation and the bone-resorbing activity of mature osteoclasts, although protein kinase C inhibitors, dantrolene (an inhibitor of calcium release from the intracellular calcium pool) and voltage-dependent calcium channel blockers did not affect PGE2-stimulated osteoclast-like cell formation. In conclusion, PGE2 stimulated osteoclast-like cell formation and bone-resorbing activity in mouse bone cell cultures presumably through osteoblasts. The activation of PKA is linked to PGE2-stimulated osteoclast-like cell formation and bone-resorbing activity.
Estrogen inhibits interleukin-6 production and gene expression in a human osteoblastic cell line with high levels of estrogen receptors
Authors: Kassem Moustapha , Harris Steven A. , Spelsberg Thomas C. , Riggs B. Lawrence 
Published: February 2010

Abstract
Some studies suggest that estrogen acts on bone by decreasing the production of interleukin-6 (IL-6), a cytokine that increases bone resorption, by osteoblasts or bone marrow cells. However, other studies have not confirmed this, possibly because of a low and variable number of estrogen receptors (ER) in the model systems used. Thus, we employed a recently developed human fetal osteoblast cell line with high levels of ER. Treatment (n = 4 experiments) with 0.01 to 10 nM of 17β-estradiol had no effect on the constitutive production of IL-6. However, stimulated production, induced by treatment with IL-1β plus tumor necrosis factor-α (TNF-α), was reduced in a dose-dependent manner to 74 + 3% (mean + SEM) of control (p &lt; 0.01). This response was blocked by cotreatment with the type II antiestrogen ICI 182,780. Treatment with hydrocortisone (1 μM), a known inhibitor of IL-6 production in many cell types, reduced IL-6 production to 17 + 1% of control (p &lt; 0.001). As assessed by Northern analysis, treatment (n = 3 experiments) with 0.01-10 nM of 17β-estradiol decreased steady-state levels of IL-6 mRNA in a dose-dependent manner. These data support the hypothesis that at least part of the antiresorptive action of estrogen in humans is mediated by decreased production of IL-6 by osteoblastic cells.
Post-transcriptional stimulation of transforming growth factor β1 mRNA by TGF-β1 treatment of transformed human osteoblasts
Authors: Liu Changbao , Wallace Kathleen , Shi Congzhu , Heyner Susan , Komm Barry , Dr. Haddad John G. 
Published: February 2010

AbstractFollowing exogenous administration of transforming growth factor-β1 (TGF-β1) polypeptide to the human osteosarcoma cell line TE-85, we observed a 2- to 6-fold stimulation of steady-state TGF-β1 mRNA. The stimulation was dose- and time-dependent, as judged from Northern blot hybridization analyses. A 2- to 6-fold increase of the TGF-β1 polypeptide was also found in the media of these cells after TGF-β1 treatments. The autostimulation of TGF-β1 mRNA was nullified by cycloheximide treatment of the cells. The in vitro transcription rates of the TGF-β1 gene by isolated nuclei were not altered by TGF-β1 treatment. Under conditions of transcriptional inhibition, the stability of TGF-β1 mRNA was enhanced nearly two-fold by TGF-β1 treatment. Our findings indicate that TGF-β1 can stimulate autologous gene expression and subsequent polypeptide translation by a post-transcriptional mechanism requiring protein synthesis in human osteoblast-like cells. The recognized versatility of TGF-β1 autostimulation mechanisms (transcriptional and post-transcriptional) in other mesenchymal cells may apply also to skeletal cells, further underscoring the broad and potent activities of this cytokine.
Effects of sodium fluoride and alendronate on the bone mineral in minipigs: A small-angle X-ray scattering and backscattered electron imaging study
Authors: Fratzl Peter , Schreiber Sabine , Roschger Paul , Lafage Marie-Helene , Rodan Gideon , Klaushofer Klaus 
Published: February 2010

Abstract
Sodium fluoride (NaF), which stimulates bone formation, and bisphosphonates, which reduce bone resorption, are both used in the treatment of osteoporosis, and are binding to bone mineral. In this study, using small-angle X-ray scattering and backscattered electron imaging, we analyzed the bone mineral in the vertebrae of minipigs treated with fluoride, with the bisphosphonate alendronate (ALN), or with vehicle. All specimens were investigated blindly. A slight increase in the average thickness of the mineral crystals as well as changes in the structure of the mineral/collagen composite were found in the case of fluoride-treated animals. No differences were found between ALN-treated animals and controls. The changes produced by fluoride are in the same direction as seen in bones from patients treated with NaF, albeit much smaller. They also correlate quantitatively with the reduction in biomechanical properties of bone in fluoride-treated minipigs found in an earlier study with the same animals. These findings suggest that small changes in the structure of the mineral/collagen composite in bone may considerably affect its biomechanical properties. It also emphasizes the delicate balance between the increase of bone mass and deterioration of bone material properties for the effect of fluoride on the biomechanical properties of bone.
Lack of an effect of sodium zeolite A on rat tibia histomorphometry
Authors: Firling Conrad E. , Evans Glenda L. , Wakley Glenn K. , Sibonga Jean , Turner Russell T. 
Published: February 2010

Abstract
Cell culture studies suggest that the aluminum silicate polymer sodium Zeolite A (SZA) increases bone cell proliferation and extracellular matrix production. This study in rats investigated the short-term (2 weeks) and long-term (18 weeks) in vivo effects of SZA on growth rate (weight gain) and tibia histomorphometry. In separate short-term experiments, female (experiment 1) or male (experiment 2) Sprague-Dawley rats grown and maintained on normal calcium diets were gavaged daily during a 2 week treatment period with 30 mg/kg, 100 mg/kg, or 500 mg of SZA/kg of rat body weight. In the long-term study (experiment 3) ovariectomized (OVX) rats were fed a low calcium diet containing 0, 1.80, and 9.00 g of SZA/kg of diet (0, 125, and 617 mg/kg of body weight, respectively). Short- and long-term treatment of growing rats with SZA resulted in a dose-dependent increase in bone aluminum. In the first experiment, growing intact female rats showed no significant SZA dose-dependent response in growth rate (weight gain) or histomorphometry of cortical bone in the tibial diaphysis or cancellous bone in the secondary spongiosa of the tibial metaphysis. In the second experiment, growing male rats, with right hind limbs immobilized by unilateral sciatic neurotomy, showed no SZA dose-dependent response in growth rate. The longitudinal growth of cancellous bone in the tibia of the denervated limb and the intact contralateral limb were not influenced by sciatic neurectomy and/or by treatment with SZA. Histomorphometry demonstrated that cortical bone mass and formation was reduced in the sciatic-sectioned limb when compared with the contralateral intact limb of vehicle-treated rats, as evidenced by significant reductions in static measurements of cortical bone area (-8.5%) and cross-sectional area (-4.8%) and in calculations of the periosteal formation rate (-33.8%) and mineral apposition rate (-31.6%), and the endocortical formation rate (-35.5%) and mineral apposition rate (-37.9%). The cancellous bone mass of denervated limbs of vehicle-treated rats was also deficient, as evidenced by decreased cancellous bone area (-39.1%) and perimeter (-31.9%). The bone mineral apposition rate was decreased (-26.7%) indicating reduced osteoblast activity. Treatment with SZA did not influence these indices in the tibiae of either sciatic-sectioned limbs or contralateral intact limbs. In the long-term experiment, OVX resulted in a dramatic 88% decrease in cancellous bone volume which was prevented by treatment with 17/β-estradiol and not influenced by treatment with Zeolite A. The increases in osteoblast and osteoclast number following OVX were not influenced by SZA. The results indicate that SZA treatment has no anabolic effect on cortical and cancellous bone formation and mass in normal growing female rats and that this compound does not protect against osteopenia due to reduced load bearing in the growing male rat or gonadal hormone deficiency in adult female rats.
Association of bone mineral density with polymorphism of the estrogen receptor gene
Authors: Kobayashi Shinji , Inoue Satoshi , Dr. Hosoi Takayuki , Ouchi Yasuyoshi , Shiraki Masataka , Orimo Hajime 
Published: February 2010

Abstract
PvuII and XbaI restriction fragment length polymorphisms (RFLPs) of the estrogen receptor (ER) gene and its relation to bone mineral density (BMD) were examined in 238 postmenopausal healthy women aged 45–91 years (66.3 ± 0.6 years, mean ± standard error of the mean [SEM]) in Japan. The RFLPs were represented as Pp (PvuII) and Xx (XbaI), with capital letters signifying the absence of and small letters the presence of restriction sites. In the PPxx genotype (n = 18), Z score values of BMD were significantly lower than those for other genotypes (n = 220) (lumbar spine, −0.746 vs. −0.065 [p = 0.022]; total body, −0.482 vs. 0.308 [p = 0.002]). We classified the subjects into three genotypes with allelic haplotype: homozygote of the Px haplotype was expressed as the 11 genotype, heterozygote of the Px haplotype as the 10 genotype, and the one lacking the Px haplotype as the 00 genotype. The PpXx genotype was not included in this analysis because the allelic haplotypes are uncertain. The Px haplotype was associated with a low BMD in postmenopausal women (Z score for the lumbar spine, −0.746 vs. −0.279 vs. 0.083, for the 11, 10, 00 genotypes, respectively [p = 0.029]; Z score for the total body, −0.482 vs. 0.164 vs. 0.427, respectively [p = 0.003]). We suggest that some variation of the ER gene linked to these RFLPs is associated with low BMD and that this at least partly explains the cause of postmenopausal osteoporosis in Japanese women.