bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical Markers of Bone Turnover and the Volume and the Density of Bone in Children at Different Stages of Sexual Development
Authors: Mora Stefano , Pitukcheewanont Pisit , Kaufman Francine R. , Nelson Jerald C. , Gilsanz Vicente 
Published: April 2006

Abstract
Bone mass and biochemical markers of bone turnover increase significantly during puberty. We studied the possible relationships between markers of bone formation and bone resorption and increases in skeletal size, bone volume, and bone density in healthy children at different stages of sexual development. Serum concentrations of bone specific alkaline phosphatase (BALP) and osteocalcin (bone Gla protein, BGP), urinary levels of pyridinoline (Pyr) and deoxypyridinoline (Dpyr) and computed tomography (CT) measurements of the cross-sectional areas of the vertebrae and the femurs, the apparent density of cancellous bone in the vertebrae, and the volume and the material density of cortical bone in the femurs were determined in 126 boys and 143 girls, ages 7–18 years. Serum levels of BALP and BGP and urinary concentrations of Pyr and Dpyr peaked in early puberty and were lowest in the later stages of puberty. CT measurements for the cross-sectional areas of the vertebrae and the femurs, the femoral cortical bone areas, and the apparent density of cancellous bone increased in all children during puberty, while values for material bone density did not change significantly with the stage of sexual development. BALP and BGP showed significant inverse correlations with the material density of bone (r = –0.23 and –0.24, respectively), but no association with bone volume in the appendicular or axial skeleton. In contrast, Pyr and Dpyr correlated with femoral cross-sectional area (r = –0.24 and –0.33, respectively) and cortical bone area (r = –0.29 and –0.33, respectively), and with the apparent density of vertebral cancellous bone (r = –0.26 and –0.19, respectively), but not with the material density of bone. We conclude that, during puberty, there is a differential association between the two components of bone mass and the markers of bone formation and bone resorption; while markers of bone formation are related to the material density of bone, markers of bone resorption are related to the volume of bone.
A Six-Year Longitudinal Study of the Relationship of Physical Activity to Bone Mineral Accrual in Growing Children: The University of Saskatchewan Bone Mineral Accrual Study
Authors: Bailey D. A. , Mckay H. A. , Mirwald R. L. , Crocker P. R. E. , Faulkner R. A. 
Published: April 2006

Abstract
To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual-energy X-ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age- and gender-specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two-way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post-PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p &lt; 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around PBMCV.
Femoral Neck Is a Sensitive Indicator of Bone Loss in Immobilized Hind Limb of Mouse
Authors: Jämsä Timo , Koivukangas Antti , Ryhänen Jorma , Jalovaara Pekka , Tuukkanen Juha 
Published: April 2006

Abstract
The present study was carried out to evaluate a unilateral hind limb immobilization model in the mouse. The right legs of male mice (age 10–12 weeks) were immobilized for 3 weeks against the abdomen by an elastic bandage. Body weight decreased significantly during the immobilization. Peripheral quantitative computed tomography (pQCT) analysis showed that the cross-sectional cortical area (CSA), the bone mineral content (BMC), and the bone mineral density (BMD) of the tibial diaphysis were lower in both legs of the immobilized animals than in age-matched controls, but the difference was mainly due to weight reduction. At the tibial metaphysis, CSA, BMC, and BMD were reduced in both legs of the immobilized animals, even after weight adjustment. At the femoral neck, CSA, BMC, and BMD were significantly lower in both legs of the immobilized animals, and the difference between the hind legs of the immobilized animals was also highly significant. The findings of the pQCT study were in good agreement with the changes in mechanical strength. The tibia was a more sensitive indicator of diaphyseal bone weakening than the femur when measuring the bending breaking force of the diaphysis. The femoral neck showed significantly decreased strength, and the difference between the immobilized leg and the contralateral leg was most clearly seen in lateral loading. We conclude that 3 weeks of hind limb immobilization weakened the tibia and femur significantly compared with their contralateral counterparts. The reduction was more significantly seen in the mechanical bending strength than in the pQCT evaluation, and the femoral neck was the most sensitive indicator of bone weakening.
TNF-α and IL-1β Suppress N-Cadherin Expression in MC3T3-E1 Cells
Authors: Tsutsumimoto Takahiro , Kawasaki Satoshi , Ebara Sohei , Takaoka Kunio 
Published: April 2006

Abstract
Excessive production of tumor necrosis factor (TNF) and interleukin-1 (IL-1) secondary to estrogen deficiency have been implicated as the cause of osteoporosis in postmenopausal woman. These cytokines appear to stimulate osteoclast precursor proliferation and activate mature osteoclast formation directly and possibly indirectly via osteoblasts. To investigate the other possible roles that these cytokines may play in stimulating the bone resorption process, we examined the effect of TNF-α and IL-1β on cell–cell adhesion molecules, cadherins, in osteoblastic MC3T3-E1 cells. In this study, we investigated cadherin expression and the effect of TNF-α, IL-1β, and parathyroid hormone (PTH) on the expression of cadherins in MC3T3-E1 cells. Confluent cultures of MC3T3-E1 cells were challenged with recombinant human TNF-α (1–100 U/ml), recombinant human IL-1β (1–100 ng/ml) and human PTH(1–34) (1–100 ng/ml), respectively. The results show that MC3T3-E1 cells express functional cadherin molecules, N-cadherin and OB-cadherin. TNF-α (10–100 U/ml) and IL-1β (10–100 ng/ml) suppressed N-cadherin without changing OB-cadherin expression, while PTH (1–100 ng/ml) had no effect on cadherin expression. These results raise the possibility that TNF-α and IL-1β may compromise the cell–cell adhesion of osteoblasts which cover the bone surface. The ensuing compromised cell–cell adhesion of osteoblasts may in turn facilitate the direct adhesion of osteoclasts on the calcified bone matrix surface. These results implicate an indirect role for osteoblasts in the promotion of bone resorption by TNF-α and IL-1β.
Comparison of Recombinant Human PTH(1–34) (LY333334) with a C-Terminally Substituted Analog of Human PTH-Related Protein(1–34) (RS-66271): In Vitro Activity and In Vivo Pharmacological Effects in Rats
Authors: Dr. Frolik Charles A. , Cain Ricky L. , Sato Masahiko , Harvey Anita K. , Chandrasekhar S. , Black Elwood C. , Tashjian Armen H. , Hock Janet M. 
Published: April 2006

Abstract
Parathyroid hormone (PTH) and PTH-related protein (PTHrP) are believed to exert their biological actions through binding and activation of a common cell surface receptor. Recently, an analog of PTHrP (RS-66271), was described that demonstrated reduced binding affinity for the PTH/PTHrP receptor compared with bovine PTH(1–34) but retained equal biological activity. The present study investigated the receptor binding affinities of synthetic RS-66271 and recombinant human PTH(1–34) (LY333334) and compared their in vitro and in vivo pharmacological effects. RS-66271 had one hundredth the activity of PTH(1–34) in competing for the binding of [125I] [Nle8,18, Tyr34]human PTH(1–34) to the human PTH/PTHrP receptor stably expressed in a human kidney cell line. Despite this reduced binding affinity, RS-66271 had equivalent activity in increasing both cAMP production in osteoblast-like cells and bone resorption in neonatal mouse calvariae. However, RS-66271 was 7.6-fold less active in stimulating inositol phosphate production. For in vivo studies, young, male Fisher rats received a daily subcutaneous dose of either 10 or 40 μg/kg of peptide for 1, 2, or 4 weeks. Volumetric bone mineral density and total bone mineral content of the proximal tibia were determined by peripheral quantitative computerized tomography. Trabecular and cortical bone of the distal femur were analyzed for calcium and dry weight. Lumbar vertebrae (L4–L6) were analyzed by histomorphometry. Trabecular and cortical bone mass showed a dose- and time-dependent increase in the treated animals compared with the controls. These increases were evident as early as 1 week after initiation of dosing. There were no consistent significant differences in the comparative effects of PTH(1–34) and RS-66271 on the measured bone parameters. In conclusion, despite the reduced binding affinity of RS-66271 for the PTH/PTHrP receptor compared with human PTH(1–34), both peptides displayed similar in vitro and in vivo pharmacological effects.
Altered Expression of Bone Sialoproteins in Vitamin D–Deficient rBSP2.7Luc Transgenic Mice
Authors: Dr. Chen Jake (Jinkun) , Jin Hangqing , Ranly Don M. , Sodek Jaro , Boyan Barbara D. 
Published: April 2006

Abstract
Bone sialoprotein (BSP) and osteopontin (OPN) are two major noncollagenous matrix proteins in mineralized connective tissue that have discrete roles in bone matrix formation, mineralization, and remodeling. The osteotropic secosteroid, 1,25-dihydroxyvitamin D3, a potent regulator of bone remodeling required for normal bone development, has been shown to exert differential effects on OPN and BSP expression by bone cells in vitro. To investigate these effects in vivo, we induced vitamin D3 deficiency in a transgenic mouse line (rBSP2.7Luc) that has a 2.7 kb rat BSP promoter linked to a luciferase reporter gene in its genome. Pregnant rBSP2.7Luc mice were fed vitamin D3–deficient food and demineralized water for 6 weeks. Their offspring were weaned at 3 weeks of age and then fed vitamin D–deficient food for an additional week. The control group were fed normal rodent pellets and water during the entire experimental procedure. Bone tissues from 40, 4-week-old offspring in each group were analyzed for BSP, OPN and luciferase expression. Vitamin D3–deficient mice displayed a rachitic phenotype that included reduced size and malformation of bones. Assays of the BSP promoter transgene in calvariae, mandibles, and tibiae of the rachitic mice showed increases in luciferase activity of 3.1-, 1.9-, and 4.6-fold, respectively, when compared with control littermates. Semiquantitative reverse transcriptase polymerase chain reaction assays of BSP mRNA revealed increases of 7-, 74-, and 66-fold, respectively, in the same rachitic bones, while OPN mRNA was reduced 12.5-fold in calvariae and 2-fold in tibiae and mandibles. In situ hybridization using mouse cRNA probes revealed that the increased BSP expression and decreased OPN expression in the vitamin D3–deficient mice was primarily in osteoblastic cells on the surface of calvariae and endosteal spaces of alveolar bone, on newly formed epiphyseal bone, and in cementoblasts and in hypertrophic chondrocytes. These studies are the first to show that BSP and OPN are differentially regulated by vitamin D3 in vivo, reflecting the diverse roles of these protein in bone remodeling. Moreover, the increased expression of the BSP transgene in the rachitic mice demonstrates that vitamin D3 regulation of BSP expression is mediated, in part, by element(s) within the 2.7 kb promoter region.
Mapping the Gene Causing Hereditary Primary Hyperparathyroidism in a Portuguese Kindred to Chromosome 1q22-q31
Authors: Williamson C. , Cavaco B. M. , Jauch A. , Dixon P. H. , Forbes S. , Harding B. , Holtgreve-Grez H. , Schoell B. , Pereira M. C. , Font A. P. , Loureiro M. M. , Sobrinho L. G. , Santos M. A. , Prof. Thakker R. V. 
Published: April 2006

Abstract
A Portuguese kindred with autosomal dominant isolated primary hyperparathyroidism (HPT) that was associated with parathyroid adenomas and carcinomas was investigated with the aim of determining the chromosomal location of this gene, designated HPTPort. Leukocyte DNA from 9 affected and 16 unaffected members and 7 parathyroid tumors from 4 patients was used in comparative genomic hybridization (CGH), tumor loss of heterozygosity (LOH), and family linkage studies. The CGH studies revealed abnormalities of chromosomes 1 and 13, and the results of LOH studies were consistent with the involvements of tumor suppressor genes from these regions. Family segregation studies mapped HPTPort to chromosome 1q22-q31 by establishing linkage with eight loci (D1S254, D1S222, D1S202, D1S238, D1S428, D1S2877, D1S422, and D1S412) (peak two-point LOD scores = 3. 46–5.14 at 0% recombination), and defined the location of HPT Port to a 21 cM region flanked centromerically by D1S215 and telomerically by D1S306. Thus, HPTPort has been mapped to chromosome 1q22-q31, and a characterization of this gene will help to elucidate further the mechanisms that are involved in the development of parathyroid tumors.
Magnesium Deficiency and Bone Loss After Cardiac Transplantation
Authors: Boncimino K. , Mcmahon D.J. , Addesso V. , Bilezikian J.P. , Shane Elizabeth 
Published: April 2006

Abstract
Magnesium depletion adversely affects many phases of skeletal metabolism and has been implicated as a risk factor in several forms of osteoporosis. Magnesium deficiency has also been reported after cardiac transplantation. To evaluate whether altered magnesium homeostasis could be related to the pathogenesis of early bone loss after cardiac transplantation, we prospectively measured serum and urinary magnesium and evaluated them with respect to biochemical indices of mineral metabolism and rates of bone loss. The study population included 60 patients (45 men, 15 women) aged 53 ± 11 years (SD) with measurements of biochemistries and bone mineral density by dual-energy X-ray absorptiometry before and 3 months after transplantation. All received prednisone, cyclosporine A, and azathioprine, plus calcium (1000 mg) and vitamin D (400 IU). After transplantation, serum magnesium decreased by 16 ± 15% (SD) from 2.0 ± 0.3 mg/dl to 1.6 ± 0.2 mg/dl (normal 1.8–2.2 mg/dl; p &lt; 0.0001), accompanied by an increase in the fractional excretion of magnesium (7.1 ± 3.9% to 13.3 ± 5.6%; p &lt; 0.0017). Forty-three patients with low 3-month serum magnesium levels (≤ 1.7 mg/dl) sustained 41% less bone loss at the lumbar spine (4.0 ± 4.6% vs. 6.8 ± 5.3%; p = 0.051) and 58% less bone loss at the femoral neck (3.1 ± 5.9% vs. 7.3 ± 5.6%; p &lt; 0.01), despite receiving similar doses of prednisone and cyclosporine A. Of the biochemical parameters measured (including renal function, serum calcium, phosphorus, vitamin D metabolites, osteocalcin, urinary calcium, and markers of bone resorption), only intact parathyroid hormone (PTH) levels, which were 40% lower in patients with low serum magnesium levels differed significantly (45 ± 23 pg/ml vs. 74 ± 60 pg/ml; p = 0.019). Patients with low serum magnesium levels also had evidence of lower bone turnover. In summary, a highly significant decline in serum magnesium concentrations, associated with continued urinary magnesium losses, occurs after cardiac transplantation. Patients with low serum magnesium levels had significantly lower rates of bone loss, lower serum PTH concentrations, and lower bone turnover. Although the precise mechanisms by which the reduction in serum magnesium tends to protect against bone loss in the early post-transplantation period remain to be elucidated, reduced serum PTH and lower rates of bone turnover are likely to be important factors.
Preparation of a cDNA Library and Preliminary Assessment of 1400 Genes from Mouse Growth Cartilage
Authors: Okihana H. , Yamada K. 
Published: April 2006

Abstract
Cartilage is an inconvenient tissue for the isolation of mRNA, and this has hampered studies of its component mRNAs conducted to date. Here, we describe the preparation of a good quality cDNA library from mouse growth cartilage (mGC). A total of 1.7 μg of poly(A)+ RNA was obtained from about 1200 pieces of the mGC zone of 60 young mice (BALB/c, 4 weeks old). Using this poly(A)+ RNA, we constructed a cDNA library using the pAP3neo vector by the linker-primer method. The complexity of the cDNA library was 2.6 × 106 colony-forming units (cfu), which signified that almost all of the mRNA components in the mGC were present in this cDNA library. From this library, 1401 clones were randomly selected and their insert sizes were examined. Of these clones, 166 (12%) had no inserts, 466 (33%) had inserts ranging in size from 0–0.9 kbp, 480 (34%) had inserts of 1.0–1.9 kbp, 162 (12%) had inserts of 2.0–2.9 kbp, and 127 (9%) had sizes greater than 3.0 kbp. The average insert size was 1.45 kbp. The number of cfu and the insert size data qualified this library as of reasonably good quality. Clones with an insert size greater than 1 kbp (769 clones) were sequenced from their 5′ ends. Among the 769 clones examined, 608 gave sequence data. Among these, 196 (32%) were unknown, 2 were only poly A, and 410 (67%) coded for known proteins. Of these, 55 clones coded for type II (pro)collagen, 54 for osteonectin, and 22 for other cartilage collagens (type IX, type X, and type XI). The rest included cartilage extracellular matrix genes, general cellular genes, and others. To judge further the quality of the library, 45 species coding for type II collagen chain were aligned based on their 5′ end sequences. Three species (7%) contained almost the full-length insert, and the shortest one was 1.5 kbp in length (full-length 5.6 kbp). These data show that this cDNA library is of reasonably good quality, making it likely that the large number of unknown inserts (32%) will provide a suitable pool for the identification and functional determination of new GC genes.
Tartrate-Resistant Acid Phosphatase Forms Complexes with α2-Macroglobulin in Serum
Authors: Brehme Cheryl Shaffer , Roman Steven , Shaffer Jennifer , Wolfert Robert 
Published: April 2006

Abstract
Tartrate-resistant acid phosphatase (TRAP) is a standard histochemical marker of differentiated osteoclasts and has been proposed as a serum/plasma marker for osteoclast activity. Enzyme assays have been described that show elevated TRAP enzyme activity in the serum or plasma of patient groups known to have increased bone metabolism. However, the poor stability of the enzyme and potential contribution from nonosteoclastic sources make it problematic to measure in patient samples. Immunoassays developed to measure TRAP in serum and plasma have yielded widely varying TRAP levels in both normal and disease states. It is not clear if this variability is caused by differences in assay calibration, antibody specificity, and/or TRAP instability. In this paper, we report that purified TRAP spiked into serum forms high molecular weight complexes. Complex formation results in greatly decreased TRAP enzyme activity and immunoreactivity. The complexing protein in serum has been identified as α2-macroglobulin (α2M). Similar complexes are observed in stored patient samples. In vitro studies with purified components show that TRAP binds to α2M primarily through noncovalent ionic interactions. Our results demonstrate that one mechanism of TRAP instability in serum is complex formation with α2M and suggest further that current TRAP enzyme and immunoassays may not accurately measure the circulating level of TRAP.
The Addition of a Raloxifene Analog (LY117018) Allows for Reduced PTH(1–34) Dosing During Reversal of Osteopenia in Ovariectomized Rats
Authors: Dr. Hodsman A. B. , Drost D. , Fraher L. J. , Holdsworth D. , Thornton M. , Hock J. , Bryant H. , Watson P. H. 
Published: April 2006

Abstract
To test the hypothesis that an antiresorptive agent might reduce the dosing requirement for an anabolic drug during reversal of osteopenia due to estrogen deficiency, the following experiment was conducted in 6-month-old female rats. Ovariectomy or sham surgery was performed and the following six experimental groups were studied. Untreated (SHAM) or ovariectomized (OVX) animals served as control groups. Four weeks post-OVX, osteopenic rats (now 7 months old), were treated in one of four experimental protocols: human parathyroid hormone (hPTH(1–34), 80 μg/kg/day, given by subcutaneous injection 5 days/week; a selective estrogen receptor modulator (SERM), raloxifene analog LY117018 (RA), 3 mg/kg/day, given by gavage 5 days/week; and two combinations of LY117018 at the same dose and frequency with hPTH(1–34) (same dose, 5 times/week) and a reduced dosing interval of hPTH(1–34) (same dose, 2 times/week). After 12 weeks of treatment, the four experimental groups were sacrificed at age 10 months. SHAM and OVX controls were also studied at 7 and 10 months of age. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at four skeletal sites: two mixed cortical/trabecular sites (femur and tibia) and two predominantly trabecular sites (lumbar spine and pelvis). The differences in BMD were consistent at all four sites. RA alone maintained BMD at all skeletal sites, but the results were not significantly improved over OVX controls, at age 10 months. hPTH(1–34) injections given 5 days/week resulted in BMD increments significantly higher than in either OVX or SHAM controls (p &lt; 0.001). While the RA did not enhance the anabolic effects of full doses of hPTH(1–34), the addition of RA treatment to twice-weekly hPTH(1–34) dosing resulted in BMD increments at all four skeletal sites that were similar to the more intensive anabolic regimen of hPTH(1–34) therapy given 5 times/week. Therefore, an antiresorptive agent such as SERMs may potentially reduce the pharmacologic doses of PTH needed to reverse estrogen deficiency-induced osteopenia.