bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Long-Term Effect of Menopause on Postmenopausal Bone Loss in Japanese Women: Results from a Prospective Study
Authors: Okano Hiroya , Mizunuma Hideki , Soda Masayuki , Kagami Issei , Miyamoto Sumitaka , Ohsawa Minoru , Ibuki Yoshito , Shiraki Masataka , Suzuki Takao , Shibata Hiroshi 
Published: April 2006

Abstract
The aim of this study was to elucidate perimenopausal bone loss in relation to menstrual conditions and to investigate the long-term effect of menopause on bone loss in aged women. The rate of change in bone mineral density (BMD) was measured twice at an exact interval of 12 months by dual-energy X-ray absorptiometry (DXA) at the lumbar spine in 176 pre- and postmenopausal healthy women 41–65 years of age. Serum follicle-stimulating hormone, intact and N-fragment osteocalcin (OC), three types of vitamin D3, parathyroid hormone (PTH), and calcitonin were also determined. Women who exercised regularly or had anatomical changes at the lumbar spine were excluded from this study. The subjects were divided into eight groups based on their menstrual status and years since menopause. Annual bone loss at the lumbar spine of premenopausal women with regular menstruation was −0.2 ± 1.9% (95% confidence interval, −0.9∼–0.4%) and was not statistically different from zero, while that of women with irregular menstruation or at menopausal transition was −2.1 ± 3.4% (−3.4∼−0.8%), and −3.3 ± 2.3% (−5.2∼−0.3%), respectively, and was significantly different from zero. Serum OC levels of women at menopausal transition were significantly higher than those of women with regular menstruation, suggesting that bone loss had commenced in these women. The rate of annual change in BMD of women who were menopausal for 1–3, 4–6, 10–12, and more than 13 years was −3.1 ± 4.0% (−4.7∼−1.5%), −1.2 ± 2.6% (−2.2∼−0.2%), −1.0 ± 3.0% (−2.3∼−0.3%), and −2.3 ± 2.1% (−3.7∼−1.0%), respectively, and was significantly less than zero. But the annual bone loss of women who were menopausal for 7–9 years was −1.5 ± 2.6% (−3.0∼−0.1%) and was not statistically significant from zero. These results indicate that postmenopausal women lose BMD in two phases. The early bone loss is rapid and commences during irregular menstruation, then is attenuated within 6 years after the onset of menopause. The second bone loss commences after the attenuation of the first bone loss. Among bone metabolic hormones, intact PTH alone showed an age-related increase and was suggested as being a causal factor of bone loss in women who were menopausal for 13 years or more.
Bone and the Hematopoietic and Immune Systems: A Report of the Proceedings of a Scientific Workshop
Authors: Sharrock William J. ,   for the ORGANIZERS,   SPEAKERS
Published: April 2006

Abstract
Recent observations underscore the linkage between endochondral bone formation and the establishment of hematopoietic marrow and suggest that interactions among bone, marrow, and the immune system persist in the mature skeleton. A workshop was held at the National Institutes of Health, Bethesda, Maryland, to discuss recent work on these interactions and to identify new areas of research. Marrow stromal cells include the precursors of the osteochondrogenic lineage, exert important influences on osteoclastogenesis and lymphopoiesis, and mediate the effects of some systemic factors on bone turnover. Recent evidence indicates that hematopoietic cells can influence the differentiation of osteogenic cells and suggests that mature lymphocytes can influence osteoclastic and osteoblastic functions. However, interpretation of experiments may be confounded by the potential for stage-specific responses within a cell lineage, the likelihood that divergent pathways compete for limited pools of precursor cells, and the possibility that important cells or factors are still unidentified. Further, in vitro models may be limited by species and anatomical site specificities, the absence of intermediary or accessory cells, and the absence of normal marrow spatial organization and cellular interactions with the extracellular matrix. Nevertheless, current approaches hold the potential for significant advances in our understanding of the relationships between bone and the hematopoietic and immune systems. Refinements of in vitro systems, the use of genetically manipulated mice, and the examination of clinical syndromes promise important insights. Collaborations among bone biologists, hematologists, and immunologists, and between basic scientists and clinical investigators, will be crucial for continued progress.
Coupling of Calcium Receptors to Inositol Phosphate and Cyclic AMP Generation in Mammalian Cells and Xenopus laevis Oocytes and Immunodetection of Receptor Protein by Region-Specific Antipeptide Antisera
Authors: Chang Wenhan , Pratt Stacy , Chen Tsui-Hua , Nemeth Edward , Huang Zhengmin , Dr. Shoback Dolores 
Published: April 2006

Abstract
Ca2+ and other divalent cations modulate parathyroid hormone secretion by interacting with cell-surface Ca2+-sensing receptors (CaRs). We assessed the ability of these receptors to couple to Ca2+ mobilization, inositol phosphate (InsP) accumulation, and cyclic AMP production in different expression systems. In Xenopus laevis oocytes injected with bovine parathyroid CaR cRNA, the addition of extracellular cations to 1.5 mM Ca2+, 5.5 mM Mg2+, or 10 μM Gd3+ significantly increased45Ca efflux (p &lt; 0.01). InsP accumulation also increased dramatically when adding these cations to human embryonic kidney (HEK) 293 cells stably transfected with wild-type bovine parathyroid CaR cDNA. Raising the extracellular [Ca2+] ([Ca2+]o) from 0.1 to &gt;1.4 mM in oocytes and to &gt;1.0 mM in HEK 293 cells stimulated significant increments in45Ca efflux and InsP accumulation, respectively (p &lt; 0.05). In contrast, Ca2+ and Mg2+ increased InsPs to a lesser extent in COS 7 cells transiently transfected with CaR cDNA. In HEK 293 cells stably expressing CaR cDNA, there were significant reductions in cAMP content when adding high Ca2+, Mg2+, Gd3+, or the CaR modulator NPS R-467. Three region-specific anti-CaR peptide antisera immunoblotted bands of ∼140 and 155 kDa in membranes from CaR-transfected HEK 293 cells and bovine parathyroid tissue. Immunocytochemistry demonstrated strong cell-surface staining in CaR-transfected HEK 293 cells and parathyroid tissue, which was absent when antisera were preabsorbed with CaR peptides. These results indicate that the activation of the recombinant CaR by extracellular Ca2+ can couple negatively to adenylate cyclase but positively to phospholipase C (PLC), the latter at physiological [Ca2+]o.
Nitrogen-Containing Bisphosphonates Inhibit the Mevalonate Pathway and Prevent Post-Translational Prenylation of GTP-Binding Proteins, Including Ras
Authors: Luckman Steven P. , Hughes David E. , Coxon Fraser P. , Russell R. Graham G. , Dr. Rogers Michael J. 
Published: April 2006

Abstract
Bisphosphonates are currently the most important class of antiresorptive drugs used for the treatment of metabolic bone diseases. Although the molecular targets of bisphosphonates have not been identified, these compounds inhibit bone resorption by mechanisms that can lead to osteoclast apoptosis. Bisphosphonates also induce apoptosis in mouse J774 macrophages in vitro, probably by the same mechanisms that lead to osteoclast apoptosis. We have found that, in J774 macrophages, nitrogen-containing bisphosphonates (such as alendronate, ibandronate, and risedronate) inhibit post-translational modification (prenylation) of proteins, including the GTP-binding protein Ras, with farnesyl or geranylgeranyl isoprenoid groups. Clodronate did not inhibit protein prenylation. Mevastatin, an inhibitor of 3-hydroxy-3-methylglutatyl (HMG)-CoA reductase and hence the biosynthetic pathway required for the production of farnesyl pyrophosphate and geranylgeranyl pyrophosphate, also caused apoptosis in J774 macrophages and murine osteoclasts in vitro. Furthermore, alendronate-induced apoptosis, like mevastatin-induced apoptosis, could be suppressed in J774 cells by the addition of farnesyl pyrophosphate or geranylgeranyl pyrophosphate, while the effect of alendronate on osteoclast number and bone resorption in murine calvariae in vitro could be overcome by the addition of mevalonic acid. These observations suggest that nitrogen-containing bisphosphonate drugs cause apoptosis following inhibition of post-translational prenylation of proteins such as Ras. It is likely that these potent antiresorptive bisphosphonates also inhibit bone resorption by preventing protein prenylation in osteoclasts and that enzymes of the mevalonate pathway or prenyl protein transferases are the molecular targets of the nitrogen-containing bisphosphonates. Furthermore, the data support the view that clodronate acts by a different mechanism.
Mesenchymal Stem Cell Surface Antigen SB-10 Corresponds to Activated Leukocyte Cell Adhesion Molecule and Is Involved in Osteogenic Differentiation
Authors: Bruder Scott P. , Ricalton Nancy S. , Boynton Raymond E. , Connolly Timothy J. , Jaiswal Neelam , Zaia Joseph , Barry Frank P. 
Published: April 2006

Abstract
Bone marrow contains a rare population of mesenchymal stem cells (MSCs) capable of giving rise to multiple mesodermal tissues including bone, cartilage, tendon, muscle, and fat. The cell surface antigen recognized by monoclonal antibody SB-10 is expressed on human MSCs but is lost during their developmental progression into differentiated phenotypes. Here we report on the immunopurification of the SB-10 antigen and its identification as activated leukocyte-cell adhesion molecule (ALCAM). Mass spectrometry establishes that the molecular mass of ALCAM is 80,303 ± 193 Da and that it possesses 17,763 ± 237 Da of N-linked oligosaccharide substituents. Molecular cloning of a full-length cDNA from a MSC expression library demonstrates nucleotide sequence identity with ALCAM. We also identified ALCAM homologs in rat, rabbit, and canine MSCs, each of which is over 90% identical to human ALCAM in their peptide sequence. The addition of antibody SB-10 Fab fragments to human MSCs undergoing osteogenic differentiation in vitro accelerated the process, thereby implicating a role for ALCAM during bone morphogenesis and adding ALCAM to the group of cell adhesion molecules involved in osteogenesis. Together, these results provide evidence that ALCAM plays a critical role in the differentiation of mesenchymal tissues in multiple species across the phylogenetic tree.
Role of Interleukin-6 in Uncoupling of Bone In Vivo in a Human Squamous Carcinoma Coproducing Parathyroid Hormone-Related Peptide and Interleukin-6
Authors: Nagai Yumiko , Yamato Hideyuki , Akaogi Keiko , Hirose Kunitaka , Ueyama Yoshito , Ikeda Kyoji , Matsumoto Toshio , Fujita Toshiro , Ogata Etsuro 
Published: April 2006

Abstract
OCC tumor has been established from a human squamous carcinoma associated with humoral hypercalcemia of malignancy (HHM) and shown to overproduce parathyroid hormone-related peptide (PTHrP) and cause aggressive hypercalcemia when implanted into nude rats. In the present study, we have demonstrated by reverse transcription-polymerase chain reaction and Northern blot analysis that OCC tumor also overexpressed interleukin 6 (IL-6) mRNA and that tumor-bearing animals exhibited a marked increase in plasma IL-6 as well as PTHrP concentrations. When a monoclonal antibody against human IL-6 was injected to block the activities of tumor-derived IL-6, bone loss in tumor-bearing animals was significantly prevented. Quantitative bone histomorphometric analysis revealed that treatment with anti–IL-6 antibody caused a substantial decrease in both osteoclast number and eroded surface (as parameters of bone resorption) and also a significant increase in the mineral apposition rate, but little effect on the osteoblastic surface. These results provide in vivo evidence suggesting that in tumors coproducing IL-6 and PTHrP, IL-6 is involved not only in the acceleration of osteoclastic bone resorption but also, at least in part, in the suppression of osteoblastic functions in HHM syndrome.
Characterization of Serum Tartrate-Resistant Acid Phosphatase and Development of a Direct Two-Site Immunoassay
Authors: Halleen Jussi M. , Hentunen Teuvo A. , Karp Matti , Käkönen Sanna-Maria , Pettersson Kim , Väänänen H. Kalervo 
Published: April 2006

Abstract
Osteoclasts secrete tartrate-resistant acid phosphatase (TRAP) to the circulation, where the amount of TRAP is expected to correlate with the bone resorption rate. We have developed two monoclonal antibodies, O1A and J1B, using purified human bone TRAP as antigen. The antibodies recognized different epitopes, allowing us to develop a two-site fluoroimmunoassay. The immunoreactivity in fresh serum specimens was less than 10% of the concentrations measured from the same specimens after 24 h of storage at 4°C, or after addition of 5 mM EDTA or EGTA to them. When fresh serum was gel filtrated using Sephacryl S-200 column, all of the enzyme eluted in the void volume as a complex with a molecular weight of more than 250 kDa. If the serum was treated with EDTA before the gel filtration, the complex was destroyed and the enzyme eluted in fractions corresponding to a molecular weight of 30 kDa, the size of monomeric purified human bone TRAP. The immunoassay was used to measure TRAP concentrations from serum samples that had been stored at 4°C for 24 h. According to the assay, premenopausal women had 13.1 ± 3.1, postmenopausal women 17.6 ± 4.2, and children 32.6 ± 12.2 μg TRAP/l of serum. We conclude that TRAP circulates in the serum as part of a complex, which also contains Ca2+, and that TRAP-immunoassay is a potentially useful method for determining bone resorption rates, as long as the complex is destroyed before the assay.
Osteoblast Programmed Cell Death (Apoptosis): Modulation by Growth Factors and Cytokines
Authors: Jilka Robert L. , Weinstein Robert S. , Bellido Teresita , Parfitt A. Michael , Manolagas Stavros C. 
Published: April 2006

Abstract
Once osteoblasts have completed their bone-forming function, they are either entrapped in bone matrix and become osteocytes or remain on the surface as lining cells. Nonetheless, 50–70% of the osteoblasts initially present at the remodeling site cannot be accounted for after enumeration of lining cells and osteocytes. We hypothesized that the missing osteoblasts die by apoptosis and that growth factors and cytokines produced in the bone microenvironment influence this process. We report that murine osteoblastic MC3T3-E1 cells underwent apoptosis following removal of serum, or addition of tumor necrosis factor (TNF), as indicated by terminal deoxynucleotidyl transferase–mediated dUTP-nick end labeling and DNA fragmentation studies. Transforming growth factor-β and interleukin-6 (IL-6)–type cytokines had antiapoptotic effects because they were able to counteract the effect of serum starvation or TNF. In addition, anti-Fas antibody stimulated apoptosis of human osteoblastic MG-63 cells and IL-6–type cytokines prevented these changes. The induction of apoptosis in MG-63 cells was associated with an increase in the ratio of the proapoptotic protein bax to the antiapoptotic protein bcl-2, and oncostatin M prevented this change. Examination of undecalcified sections of murine cancellous bone revealed the presence of apoptotic cells, identified as osteoblasts by their proximity to osteoid seams and their juxtaposition to cuboidal osteoblasts. Assuming an osteoblast life span of 300 h and a prevalence of apoptosis of 0.6%, we calculated that the fraction that undergo this process in vivo can indeed account for the missing osteoblasts. These findings establish that osteoblasts undergo apoptosis and strongly suggest that the process can be modulated by growth factors and cytokines produced in the bone microenvironment.
Inorganic Polyphosphate in Human Osteoblast-like Cells
Authors: Leyhausen Gabriele , Lorenz Bernd , Zhu Hua , Geurtsen Werner , Bohnensack Ralf , Müller Werner E. G. , Schröder Heinz C. 
Published: April 2006

Abstract
Significant amounts of inorganic polyphosphates and of polyphosphate-degrading exopolyphosphatase activity were detected in human mandibular-derived osteoblast-like cells. The amount of both soluble and insoluble long-chain polyphosphate in unstimulated osteoblast-like cells was higher than in human gingival cells, erythrocytes, peripheral blood mononuclear cells, and human blood plasma. The cellular content of polyphosphate in osteoblast-like cells strongly decreased after a combined treatment of the cells with the stimulators of osteoblast proliferation and differentation, dexamethasone, β-glycerophosphate, epidermal growth factor, and ascorbic acid. The amount of soluble long-chain polyphosphate, but not the amount of insoluble long-chain polyphosphate, further decreased after an additional treatment with 1α,25-dihydroxyvitamin D3(1,25(OH)2D3). The decrease in polyphosphate content during treatment with dexamethasone, β-glycerophosphate, epidermal growth factor, and ascorbic acid was accompanied by a decrease in exopolyphosphatase, pyrophosphatase, and alkaline phosphatase activity. However, additional treatment with 1,25(OH)2D3 resulted in an increase in these enzyme activities. Osteoblast-like cell exopolyphosphatase activity and exopolyphosphatase activity in yeast, rat tissues, and human leukemia cell line HL60 were inhibited by the bisphosphonates etidronate and, to a lesser extent, clodronate and pamidronate. From our results, we assume that inorganic polyphosphate may be involved in modulation of the mineralization process in bone tissue.
Expression of the Thrombin Receptor in Developing Bone and Associated Tissues
Authors: Abraham Linda A. , Jenkins Alison L. , Stone Stuart R. , Mackie Eleanor J. 
Published: April 2006

Abstract
Thrombin, a serine protease with a central role in thrombosis and hemostasis, is also a specific agonist for a variety of cellular responses in osteoblasts and stimulates bone resorption in organ culture. Cultured osteoblast-like cells express the proteolytically activated thrombin receptor, but the significance of this finding in vivo remains unknown. Immunohistochemistry was used to investigate the normal tissue distribution of the proteolytically activated thrombin receptor in developing rat bones and associated tissues. In hind limbs, the receptor was first observed on embryonic day 16 and became more abundant within the limb as gestation progressed. Thrombin receptor staining was detected on osteoblasts, macrophages, muscle cells, and endothelial cells, but not osteoclasts. Similarly, osteoblasts in developing calvariae stained positively for the thrombin receptor. The pattern of receptor expression by primary osteoblast cultures and freshly isolated macrophages and osteoclasts corresponded to that observed in vivo. The observed pattern of thrombin receptor expression in bone cells supports the hypothesis that cell-mediated thrombin-induced bone resorption is mediated by osteoblasts.
Estrogen via the Estrogen Receptor Blocks cAMP-Mediated Parathyroid Hormone (PTH)-Stimulated Osteoclast Formation
Authors: Kanatani Masanori , Sugimoto Toshitsugu , Takahashi Yasuyuki , Kaji Hiroshi , Kitazawa Riko , Chihara Kazuo 
Published: April 2006

Abstract
Several lines of evidence indicate that estrogen inhibits parathyroid hormone (PTH)-induced bone resorption in vivo and in vitro. However, its precise mechanism remains unknown. The present study was performed to investigate whether osteoclast precursor cells possess the receptors for PTH/PTH-related protein (PTHrP) and/or estrogen and to clarify the mechanism by which estrogen affects PTH-induced osteoclast-like cell (Ocl) formation. The polymerase chain reaction (PCR) product corresponding in size to the mouse PTH/PTHrP receptor cDNA was detected in mouse hemopoietic blast cells supported by granulocyte-macrophage colony-stimulating factor (GM-CSF) as well as in osteoblastic MC3T3-E1 cells. The nucleotide sequence of the PTH/PTHrP receptor PCR product of hemopoietic blast cells was found to be 95.4% identical to that of PTH/PTHrP receptor cDNA of rat osteoblastic ROS cells. The PCR product corresponding in size to the mouse estrogen receptor cDNA was detected in mouse hemopoietic blast cells supported by GM-CSF as well as in MC3T3-E1 cells. The nucleotide sequence of the estrogen receptor PCR product of hemopoietic blast cells was completely identical to that of mouse estrogen receptor cDNA. 17β-estradiol (17β-E2) but not 17α-E2 dose dependently antagonized Ocl formation stimulated by human (h) PTH(1–34) at a minimal effective concentration of 10−10 M in the hemopoietic blast cell culture. 17β-E2 also significantly inhibited Ocl formation stimulated by 10−8 M hPTHrP(1–34), while it did not affect 1,25-dihydroxyvitamin D3–induced Ocl formation. However, 10−8 M 17β-E2 significantly inhibited Ocl formation stimulated by dibutyryladenosine cAMP (10−4 M) and Sp-cAMPS (10−4 M), an activator of cAMP-dependent protein kinase (PKA) as well as forskolin (10−5 M). In contrast, 17β-E2 did not affect Ocl formation by either phorbol myristate acetate (10−7 M), an activator of protein kinase C (PKC), or A23187 (10−7 M), a calcium ionophore. The pretreatment with 17β-E2 significantly inhibited Ocl formation induced by the combined treatment with PTH and PKC inhibitors (H7 or staurosporine), while it did not affect Ocl formation stimulated by the combined treatment with PTH and Rp-cAMPS, a PKA inhibitor. The present data indicate that estrogen inhibits PTH-stimulated Ocl formation by directly acting on hemopoietic blast cells, possibly through blocking a PKA pathway but not a calcium/PKC pathway.