bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Thickness of Human Vertebral Cortical Bone and its Changes in Aging and Osteoporosis: A Histomorphometric Analysis of the Complete Spinal Column from Thirty-Seven Autopsy Specimens
Authors: Ritzel Holger , Amling Michael , Pösl Martin , Hahn Michael , Delling Günter 
Published: April 2006

Abstract
The object of this study was to analyze the cortical thickness (Ct.Th) of the ventral and dorsal shell of the vertebral bodies throughout the human spine in aging and in osteoporosis. Therefore, the complete front column of the spine of 26 autopsy cases (aged 17–90, mean 42 years) without diseases affecting the skeleton and of 11 cases (aged 58–92, mean 77 years) with proven osteoporosis were removed. A sagittal segment prepared through the center of all vertebral bodies was undecalcified, embedded in plastic, ground to a 1 mm thick block, and stained using a modification of the von Kossa method. The analysis included the measurement of the mean cortical thickness of both the ventral and dorsal shell, respectively (from the third cervical to the fifth lumbar vertebral body). The qualitative investigation of the structure of the cortical ring completed the analysis. The presented data revealed a biphasic curve for both the ventral and dorsal shell, skeletally intact with high values of the cortical thickness in the cervical spine (285 μm), and a decrease in the thoracic (244 μm) and an increase in the lumbar spine (290 μm). The mean thickness of the ventral shell is in general greater than the thickness of the dorsal shell in both skeletally normal and osteoporotic cases. The cortical thickness of the spine showed no gender-specific differences (p = NS). There was a slight decrease of the cortical thickness with aging; however, this decrease and the correlation of cortical thickness to age was only significant below vertebral body T8 (r = 0.225–0.574; pr &lt; 0.05–0.005). Most interestingly, however, osteoporosis presents itself with a highly significant loss of cortical thickness throughout the whole spine. This decrease of cortical thickness was more marked in the dorsal shell (p &lt; 0.05) than in the ventral shell (ventral from C3 to T6 [p &lt; 0.05] below T6 [p = NS]). We therefore conclude that in osteoporosis the loss of spinal bone mass is not only a loss of trabecular structure but also a loss of cortical thickness. Furthermore, these results may explain the development of regions of least resistance within the spine in aging and the clustering of osteoporotic fractures in the lower thoracic and lumbar spine.
Localization and Quantification of Proliferating Cells During Rat Fracture Repair: Detection of Proliferating Cell Nuclear Antigen by Immunohistochemistry
Authors: Iwaki Akira , Jingushi Seiya , Oda Yoshinao , Izumi Toshihiro , Shida Jun-Ichi , Tsuneyoshi Masazumi , Sugioka Yoichi 
Published: April 2006

Abstract
Bilateral femurs of 12-week-old female Sprague-Dawley rats were fractured, and the fractured femurs were harvested 36 h, 3, 7, 10, and 14 days after the fracture. Localization of cell proliferation in the fracture calluses was investigated using immunohistochemistry with antiproliferating cell nuclear antigen (PCNA) monoclonal antibodies. Thirty-six hours after the fracture, many PCNA-positive cells were observed in the whole callus. The change was not limited to mesenchymal cells at the fracture site where the inflammatory reaction had occurred, but extended in the periosteum along almost the entire femoral diaphysis where intramembranous ossification was initiated. On day 3, periosteal cells or premature osteoblasts in the newly formed trabecular bone during intramembranous ossification still displayed intense staining. On day 7, many premature chondrocytes and proliferating chondrocytes were PCNA positive. Endochondral ossification appeared on days 10 and 14, and the premature osteoblasts and endothelial cells in the endochondral ossification front were stained with anti-PCNA antibodies. Quantification of PCNA-positive cells was carried out using an image analysis computer system, obtaining a PCNA score for each cellular event. The highest score was observed in the periosteum early after the fracture near the fracture site. Immunohistochemistry using anti-PCNA antibodies showed that the distribution of proliferating cells and the degree of cell proliferation varied according to the time lag after the fracture, suggesting the existence of local regulatory factors such as growth factors, and that significant cell proliferation was observed at the beginning of each cellular event.
Effect of Metabolic Acidosis on the Potassium Content of Bone
Authors: Bushinsky David A. , Gavrilov Konstantin , Chabala Jan M. , Featherstone John D. B. , Levi-Setti Riccardo 
Published: April 2006

Abstract
Metabolic acidosis induces resorption of cultured bone, resulting in a net efflux of calcium (Ca) from the bone and an apparent loss of mineral potassium (K). However, in these organ cultures, there is diffusion of K between the medium and the crystal lattice, causing difficulty in interpretation of the acid-induced changes in mineral ion composition. To determine the effects of acidosis on bone mineral K, we injected 4-day-old neonatal mice with pure stable isotope41K, equal to ∼5% of their total body K. Calvariae were dissected 24 h later and then cultured for 24 h in medium without added41K, either at pH ∼7.4 (Ctl) or at pH ∼7.1 (Ac), with or without the osteoclastic inhibitor calcitonin (3 × 10−9 M, CT). The bone isotopic ion content was determined with a high-resolution scanning ion microprobe utilizing secondary ion mass spectrometry.41K is present in nature at 6.7% of total K. The injected41K raised the ratio of bone41K/(39K+41K) to 9.8 ± 0.5% on the surface (ratios of counts per second of detected secondary ions, mean ±95% confidence interval) but did not alter the ratio in the interior (6.9 ± 0.4%), indicating biological incorporation of the41K into the mineral surface. The ratios of41K/40Ca on the surface of Ctl calvariae was 14.4 ± 1.2, indicating that bone mineral surface is rich in K compared with Ca. Compared with Ctl, Ac caused a marked increase in the net Ca efflux from bone that was blocked by CT. Ac also induced a marked fall in the ratio of41K/40Ca on the surface of the calvariae (4.3 ± 0.5, p &lt; 0.01 vs. Ctl), which was partially blocked by CT (8.2 ± 0.9, p &lt; 0.01 vs. Ctl and vs. Ac), indicating that Ac causes a greater release of bone mineral K than Ca which is partially blocked by CT. Thus, bone mineral surface is rich in K relative to Ca, acidosis induces a greater release of surface mineral K than Ca, and osteoclastic function is necessary to support the enriched levels of surface mineral K in the presence of acidosis.
Elimination and Biochemical Responses to Intravenous Alendronate in Postmenopausal Osteoporosis
Authors: Khan Sohail A. , Kanis John A. , Vasikaran Samuel , Kline W. F. , Matuszewski B. K. , McCloskey Eugene V. , Beneton Monique N. C. , Gertz Barry J. , Sciberras David G. , Holland S. D. , Orgee Jane , Coombes Gillian M. , Rogers Suzanne R. , Porras A. G. 
Published: April 2006

Abstract
Postmenopausal women with established vertebral osteoporosis were studied for 2 years to determine the terminal elimination half-life and the duration of response to treatment with intravenous alendronate (30 mg) given over 4 days. The urinary excretion of alendronate followed a multiexponential decline. Approximately 50% of the total dose was excreted over the first 5 days, and a further 17% was excreted in the succeeding 6 months. Thereafter, there was a much slower elimination phase with an estimated mean terminal half-life of greater than 10 years (n = 11). Urinary excretion of hydroxyproline and calcium decreased significantly from pretreatment values by day 3, reaching a nadir by 1 week (40% and 67% decrease, respectively). Thereafter, hydroxyproline remained suppressed for the following 2 years. In contrast, urinary calcium excretion returned gradually toward pretreatment values over the first year and during the second year was comparable to pretreatment values. Serum activity of alkaline phosphatase activity decreased over 3 months (23% reduction), increased gradually thereafter, and returned to pretreatment values at month 24. Bone mineral density measured at the spine increased by approximately 5% during the first year and remained significantly higher than pretreatment values at 2 years. We conclude that a short course of high doses of intravenous alendronate is associated with a prolonged skeletal retention of the agent. This open study also suggests that this regimen has a sustained effect on bone turnover persisting for at least 1 year.
Skeletal Involvement in Female Acromegalic Subjects: The Effects of Growth Hormone Excess in Amenorrheal and Menstruating Patients
Authors: Scillitani Alfredo , Chiodini Iacopo , Carnevale Vincenzo , Giannatempo Giuseppe M. , Frusciante Vincenzo , Villella Massimo , Pileri Mauro , Guglielmi Giuseppe , Di Giorgio Anna , Modoni Sergio , Fusilli Saverio , Di Cerbo Alfredo , Liuzzi Antonio 
Published: April 2006

Abstract
Bone involvement is a common clinical feature in acromegalic patients, though previous studies gave divergent results possibly because of the different gonadal status of the patients studied. To study the influence of estrogen milieu in these patients, we evaluated 23 acromegalic patients with active disease, subdivided into two groups: menstruating and amenorrheal patients, comparable for duration and activity of disease. Forty-two matched women served as controls. Skeletal involvement was studied by measuring: (a) the main biomarkers of bone turnover: serum alkaline phosphatase total activity (AP), bone GLA protein (BGP), serum carboxy-terminal propeptide of type I collagen (PICP), serum type I cross-linked N-telopeptide (ICTP), and urinary pyridinoline and deoxypyridinoline corrected for creatinine (Pyr/Cr, D-Pyr/Cr) and urinary calcium/creatinine ratio (Ca/Cr); (b) bone mineral density (BMD), as measured by quantitative computed tomography both at lumbar spine and distal radius, and by dual X-ray absorptiometry both at lumbar spine and at three femoral sites (Ward's triangle, femoral neck, and great trochanter). AP, BGP, ICTP, Pyr/Cr, D-Pyr/Cr were significantly higher in patients than in controls, independent of the menstrual pattern. Higher PICP levels were found in the whole group and in menstruating acromegalics when compared with control women; no difference was found in amenorrheal patients, who in turn showed higher urinary Ca/Cr values. When patients were considered all together, BMD at spine, femoral neck, and trochanter was higher than in controls. In contrast, when the gonadal status was taking into account and, menstruating and amenorrheal subjects were considered separately, BMD at spine, but not in other sites, was significantly higher in menstruating patients than in controls. In contrast, no difference of BMD values at any site was observed between amenorrheal patients and controls. The mean BMD Z scores allowed us to detect an unequal involvement of different skeletal sites. Our results show that bone turnover is increased in acromegalic women and suggest that GH anabolic effect on bone is more evident in the presence of estrogens and that different skeletal sites may be affected differently by hormone excess.
Monoclonal Antibodies Against Synthetic Peptides Corresponding to the Extracellular Domain of the Human Ca2+ Receptor: Characterization and Use in Studying Concanavalin A Inhibition
Authors: Goldsmith Paul K. , Fan Gaofeng , Miller Jeffery L. , Rogers Kimberly V. , Spiegel Allen M. 
Published: April 2006

Abstract
We generated monoclonal antibodies against two synthetic peptides corresponding to residues 214–235 (ADD) and 374–391 (LRG) of the human Ca2+ receptor (hCaR) extracellular domain (ECD). Although both antibodies reacted well with their respective immunizing peptides on peptide-based enzyme linked immunosorbent assay, ADD was much more strongly reactive with the hCaR than LRG in assays such as immunoblots done under denaturing conditions. The opposite pattern was seen in flow cytometry analysis of the native receptor stably expressed in transfected 293 cells. We speculate that the ADD epitope is unexposed in the native receptor while the reverse is true for the LRG epitope. The ability to measure cell surface expression of the hCaR under native conditions using flow cytometry with the LRG monoclonal allowed us to study the basis for Concanavalin A (Con A) inhibition of CaR activation by Ca2+. Our studies show that Con A inhibition is partially accounted for by receptor internalization but, additionally, Con A may prevent Ca2+ stimulation directly by binding to carbohydrate residues in the receptor ECD.
OP-1 (BMP-7) Affects mRNA Expression of Type I, II, X Collagen, and Matrix Gla Protein in Ossifying Long Bones In Vitro
Authors: Haaijman A. , D'Souza R. N. , Bronckers A. L. J. J. , Goei S. W. , Burger E. H. 
Published: April 2006

Abstract
In long bone development, a regulating role of OP-1 is suggested by the local correlated expression of both OP-1 ligand and OP-1 binding receptors in developing mouse hind limbs. OP-1 is expressed in the interdigital mesenchyme, whereas OP-1 binding receptors are found in the bordering perichondrium, and both OP-1 ligand and receptors are present in the zone of (pre)hypertrophic chondrocytes. We investigated the role of OP-1 in long bone development experimentally by treating organ cultures of embryonic mouse metatarsals with rhOP-1. The mRNA expression patterns of type I, II, X collagen, and matrix Gla protein (MGP) were studied using in situ hybridization and cell proliferation using [3H]thymidine and BrdU labeling. In the epiphyseal perichondrium, treatment with 40 ng/ml OP-1 enhanced cell proliferation after day 2, while 6-day treatment caused a shift in expression from type I collagen to type II collagen mRNA. This supports previous histochemical findings that OP-1 induced the transition of perichondrium into cartilage. In the center of the rudiment, OP-1 inhibited the expression of type X collagen mRNA, indicating inhibition of chondrocyte hypertrophy. An arrest of differentiation at the prehypertrophic chondrocyte stage was also indicated by the large area of cells expressing MGP mRNA in the OP-1–treated rudiments. We conclude that OP-1 affected the expression of marker genes of chondrocyte differentiation by acting on two steps in endochondral ossification. First, cell proliferation was enhanced, particularly so in the perichondrium where cells started to express the chondrocyte phenotype. Second, the terminal differentiation of mature chondrocytes into hypertrophic chondrocytes was inhibited. These results, combined with the known pattern of OP-1 ligand and BMP receptor expression in the embryo, suggest that OP-1 plays a local role in the cascade of events during endochondral ossification.
Hypophosphatemia and the Development of Rickets in Osteopetrotic (op/op) Mice
Authors: Mccary Laura C. , Smith Connie M. , Deluca Hector F. 
Published: April 2006

Abstract
Our previous work has shown that op/op mice hyperabsorb dietary calcium in the vitamin D–deficient state and shunt that calcium into bone. Under these conditions, the op/op mice are hypocalcemic. The purpose of this study was to examine calcium metabolism and bone mineralization in vitamin D–deficient op/op mice. First, the op/op mice and their normal littermates were placed on a vitamin D–deficient, low phosphorus diet to limit bone mineralization. Under these circumstances, op/op mice survived, even when calcium was also removed from the diet. If the diet contained phosphate, op/op mice died from hypocalcemic tetany when calcium was also removed from the diet. Furthermore, serum calcium levels became similar to wild type in the op/op mice administered the vitamin D–deficient, low phosphorus diet, and op/op mice were able to increase serum calcium in response to 1,25-dihydroxyvitamin D3. The op/op mice developed rickets when their serum phosphorus level was too low to support bone mineralization. The op/op mice became hypophosphatemic on regimens in which normal mice were able to maintain normal serum phosphorus levels. It appears that the op/op mouse simply requires a higher dietary calcium and phosphorus level to prevent rickets and hypocalcemic tetany since the bone is not available as a source of these minerals. However, the ability of the op/op mouse to mineralize bone at low serum calcium and phosphorus levels remains unexplained.
Expression of an Extracellular Calcium-Sensing Receptor in Human and Mouse Bone Marrow Cells
Authors: House Michael G. , Kohlmeier Lynn , Chattopadhyay Naibedya , Kifor Olga , Yamaguchi Toru , Leboff Meryl S. , Glowacki Julie , Brown Edward M. 
Published: April 2006

Abstract
The cloning of a G protein–coupled, extracellular calcium (Ca2+e)-sensing receptor (CaR) from bovine parathyroid provided direct evidence that Ca2+e-sensing can occur through receptor-mediated activation of G proteins and their associated downstream regulators of cellular function. CaR transcripts and protein are present in various tissues of humans and other mammals that are involved in Ca2+e homeostasis, including parathyroid, kidney, and thyroidal C-cells. The present study was performed to determine whether bone marrow cells express the CaR, since cells within the marrow space could be exposed to substantial changes in Ca2+e related to bone turnover. Using DNA and RNA probes from the human parathyroid CaR cDNA, we identified CaR transcripts of 5.2 and ∼4.0 kilobases by Northern analysis of poly(A+) RNA from low-density mononuclear cells isolated from whole human bone marrow that are putatively enriched in marrow progenitor cells, including bone cell precursors. In situ hybridization also identified CaR transcripts in the same cell preparations. Reverse transcription-polymerase chain reaction demonstrated &gt;99% nucleotide identity between transcripts from human bone marrow cells and the corresponding regions of the human CaR cDNA. Antisera specific for several different regions within the extracellular domain of the CaR were reactive with low-density human marrow cells that were either adherent or nonadherent to plastic. About one-third of the adherent, CaR-immunoreactive cells were also positive for alkaline phosphatase, a nonspecific marker of preosteoblasts, osteoblasts, and assorted cells of the colony-forming unit-fibroblast lineage. In addition, a substantial fraction (∼60%) of low density murine marrow cells cultured for 1 week at 4.8 mM Ca2+e expressed both CaR immunoreactivity and nonspecific esterase, an enzyme expressed by monocyte/macrophages and fibroblasts. Finally, erythroid precursors and megakaryocytes from murine marrow as well as blood platelets expressed abundant CaR immunoreactivity, while peripheral blood erythrocytes and most polymorphonuclear leukocytes did not. These studies indicate that the CaR is present in low-density mononuclear bone marrow cells as well as in cells of several hematopoietic lineages and could potentially play a role in controlling the function of various cell types within the marrow space.
Gene Expression Patterns of Murine Dentin Matrix Protein 1 (Dmp1) and Dentin Sialophosphoprotein (DSPP) Suggest Distinct Developmental Functions In Vivo
Authors: D'souza R. N. , Cavender A. , Sunavala G. , Alvarez J. , Ohshima T. , Kulkarni A. B. , MacDougall M. 
Published: April 2006

Abstract
Although the precise mechanisms of the conversion of predentin to dentin are not well understood, several lines of evidence implicate the noncollagenous proteins (NCPs) as important regulators of dentin biomineralization. Here we compared the in vivo temporospatial expression patterns of two dentin NCP genes, dentin matrix protein 1 (Dmp1), and dentin sialophosphoprotein (DSPP) in developing molars. Reverse transcription-polymerase chain reaction was performed on embryonic day 13 to 1-day-old first molars using Dmp1- and DSPP-specific primer sets. Dmp1 transcripts appeared at the late bud stage, while DSPP mRNA was seen at the cap stage. Expression of both genes was sustained throughout odontogenesis. In situ hybridization analysis revealed interesting differences in the expression patterns of these genes. While Dmp1 and DSPP showed coexpression in young odontoblasts before the start of mineralization, the expression of these genes was notably distinct at later stages. Dmp1 expression decreased in secretory odontoblasts after the appearance of mineral, while high levels of DSPP were sustained in odontoblasts. In early secretory ameloblasts, DSPP expression was transient and down-regulated with the appearance of dentin matrix. Interestingly, Dmp1 expression became evident in ameloblasts during the maturative phase of amelogenesis. In contrast to Dspp expression that was tooth-specific, Dmp1 was expressed by osteoblasts throughout ossification in the skeleton. Probes directed to the “DSP” and “DPP” regions of the DSPP gene showed identical patterns of mRNA expression. These data show that the developmental expression patterns of Dmp1 and DSPP are distinct, implying that these molecules serve different biological functions in vivo.
Genetic Influences on Muscle Strength, Lean Body Mass, and Bone Mineral Density: A Twin Study
Authors: Arden N. K. , Spector T. D. 
Published: April 2006

Abstract
Lean body mass and muscle strength are both associated with bone mineral density (BMD), which is known to be under strong genetic control. In this classical twin study, we examine the size of the genetic component of both muscle strength and lean body mass and to what degree they account for the genetic component of BMD. In all, 706 postmenopausal women were examined; 227 pairs of monozygous (MZ) twins and 126 pairs of dizygous (DZ) twins. Grip strength was measured using a hand-help grip bulb and leg strength using a dynamic leg extensor power rig. Lean body mass and BMD at multiple sites were measured by dual-energy X-ray absorptiometry. BMD correlated with both leg extensor strength (r = 0.16–0.26) and grip strength (r = 0.12–0.21). Lean mass was significantly correlated with BMD at all sites (r = 0.20–0.39). All three muscle variables have a moderate genetic component with heritability estimates of 0.52 for lean body mass, 0.46 for leg extensor strength, and 0.30 for grip strength (all p &lt; 0.05). The genetic component of BMD was not significantly reduced after adjusting for lean mass and muscle strength, with less than 20% of the genetic variance of BMD explained by the muscle variables. In conclusion, these data suggest that the three muscle variables have a modest genetic component, suggesting the potential for clinical intervention and lifestyle modifications. The genetic component to muscle bulk and strength accounts for little of the genetic component to BMD, confirming the rationale for research into bone-specific genes.