bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multicenter comparison of dual-energy X-ray absorptiometers: In vivo and in vitro measurements of bone mineral content and density
Authors: Economos Christina D. , Nelson Miriam E. , Fiatarone Maria A. , Dallal Gerard E. , Heymsfield Steven B. , Wang Jack , Russell-Aulet Mary , Yasumura Seiichi , Ma Ruimei , Vaswani Ashok N. , Pierson Richard N. 
Published: February 2010

Abstract
As part of a multicenter research project, we compared dual-energy X-ray absorptiometry (I)XA) instruments at three research centers (sites 1, 2, and 3) to determine both intra- and intersite variability of bone mineral content (BMC), bone mineral density (BMD), and bone area (BA). Scans of the total body and lumbar spine were performed in duplicate on five humans (in vivo), and scans of the total body were performed on two whole body phantoms with artificial skeletons and thickness overlays (in vitro) at all sites over 15 days. The average intrasite variability in two consecutive total body BMD measurements, expressed as a percent difference, was significantly higher in vitro, 1.74 + 1.97%, than in vivo, 0.71 + 0.38% (p &lt; 0.05). Average intrasite variability of the in vivo lumbar spine BMD was 1.08 + 1.12%. The intersite coefficients of variation for all BMD, BMC, and BA measurements were &lt;2.0%. The total body BMD from site 2 was systematically lower than at sites 1 and 3 both in vivo and in vitro (p &lt; 0.05) with no differences in BMC and BA. Although significant, the total body BMD differences between sites were small (&lt; 1.2%) in vivo compared with in vitro (&lt;2.6%) and are encouraging for the comparison and pooling of human data from multicenter trials, provided that appropriate standardized cross-calibration and analysis procedures are applied.
Increased bone formation and osteoblastic cell phenotype in premature cranial suture ossification (craniosynostosis)
Authors: de Pollack Cinderella , Renier Dominique , Hott Monique , Dr. Marie Pierre J. 
Published: February 2010

Abstract
Craniosynostosis is a heterogeneous disorder characterized by premature fusion of the skull bone sutures. To evaluate the pathogenesis of premature cranial suture ossification in craniosynostosis, we have evaluated the histologic indices of bone formation and the characteristics of osteoblastic cells derived from normal and affected cranial sutures in 47 infants and children, aged 3–18 months, with nonsyndromic craniosynostosis. The histomorphometric analysis of normal and fused sutures showed an age-related decline in the extent of endosteal bone surface covered with osteoid and osteoblasts during postnatal suture ossification. Bone formation was 20–50% higher at 3–6 months of age in fused sutures compared with normal sutures in the same patients. Cells derived from normal and fused sutures displayed characteristics of the osteoblast phenotype in culture. Analysis of [3H]thymidine incorporation into DNA from 1–14 days of culture showed an age-related decrease in osteoblastic cell growth in both normal and affected sutures. The proliferation of osteoblastic cells isolated from fused sutures was similar at all ages to that of cells isolated from normal sutures in the same patients. In contrast, alkaline phosphatase activity and osteocalcin production by osteoblastic cells cultured in basal conditions and after stimulation with 1,25-dihydroxyvitamin D (1,25[OH]2D3), were 53–74% higher in fused sutures compared with cells isolated from normal sutures in the same patients. The results indicate that bone formation activity at the suture site is locally increased in craniosynostosis, and this disorder is associated with increased in vitro parameters of osteoblastic cell differentiation, suggesting that an increased maturation of osteoblastic cells at the site of the suture leads to the premature ossification in nonsyndromic craniosynostosis.
Sequential effects of chronic human PTH (1-84) treatment of estrogen-deficiency osteopenia in the rat
Authors: Mitlak Bruce H. , Burdette-Miller Pamela , Schoenfeld David , Neer Robert M. 
Published: February 2010

Abstract
Although daily injections of parathyroid hormone (PTH) can rapidly reverse estrogen-deficiency bone loss in rats, PTH treatment of osteoporotic humans has to date produced more modest increases in bone mass. To explore the reasons for this important difference, we evaluated the dose- and time-dependence of human PTH 1–84 treatment effects on bone mass and biochemical markers of bone metabolism in rats with estrogen-deficiency bone loss. The highest doses of PTH increased spinal, femoral, and total skeletal mass to supra-normal levels and stimulated cortical endosteal bone formation. Spine and whole skeleton mass and density increased rapidly at first, but then increased more slowly; the rate of change decreased significantly (p &lt; 0.01) during continued treatment with the highest doses of PTH. The effects of PTH treatment on biochemical markers also were both dose-dependent and time-dependent. Serum osteocalcin, a marker of osteoblast function, increased with the highest doses of PTH (p &lt; 0.001), but reached an early plateau and later returned toward baseline. Urinary excretion of pyridinolines, a marker of osteoclast function, increased in a time-dependent fashion throughout treatment (p &lt; 0.001). Serum 1,25(OH)2 vitamin D levels increased in a dose-related fashion, but then decreased toward control levels despite continued treatment. We demonstrate that both osteoblast and osteoclast function are increased during daily PTH therapy in the rat. The pattern of response depends on both the dose of PTH and the duration of therapy. These dose- and time-related effects should be taken into account when designing experimental PTH treatments for osteoporosis, and they deserve intensive study.
Increase of vascular endothelial growth factor mRNA expression by 1,25-dihydroxyvitamin D3 in human osteoblast-like cells
Authors: Wang Da Shen , Yamazaki Kazuko , Nohtomi Kyoko , Shizume Kazuo , Ohsumi Kazuoki , Shibuya Masabumi , Demura Hiroshi , Dr. Sato Kanji 
Published: February 2010

Abstract
Vascular endothelial growth factor (VEGF), a secreted endothelial cell-specific mitogen, is produced in endocrine organs and regulated by trophic hormones. Because angiogenesis and osteogenesis are closely regulated, we studied whether human osteoblast-like cells produce VEGF, and if so, what factors regulate VEGF mRNA expression. Human osteoblast-like cells (HObLC) derived from trabecular bone explants were cultured in α-MEM supplemented with 10% fetal calf serum. Northern blot analysis revealed that HObLC expressed VEGF mRNA, as did several human osteosarcoma cells. 1,25-(OH)2D3 increased the steady-state levels of VEGF mRNA in a time- and concentration-dependent manner in HObLC and one of the osteosarcoma cell lines, SaOS-2, accompanied by an increase in the concentration of immunoreactive VEGF in the conditioned medium. PTH and IGF-I also increased the level of VEGF mRNA in HObLC and SaOS-2 cells. Furthermore, 12-O-tetradecanoylphorbol ester stimulated VEGF mRNA in a time-and concentration-dependent manner. The VEGF mRNA expression induced by 1,25-(OH)2D3 was completely inhibited by H-7, but only partially by staurosporine. We have demonstrated that PTH, IGF-I, and most potently 1,25-(OH)2D3 stimulate the mRNA expression and secretion of VEGF in human osteoblast-like cells, suggesting that one of the anabolic effects of 1,25-(OH)2D3 on skeletal tissue may be mediated by VEGF produced by osteoblasts.
Mechanical loading and sex hormone interactions in organ cultures of rat ulna
Authors: Cheng Ming Zhao , Zaman Gul , Rawlinson Simon C. F. , Suswillo Rosemary F. L. , Lanyon Professor Lance E. 
Published: February 2010

Abstract
The separate and combined effects of loading and 17β-estradiol (E2) or 5α-dihydrotestosterone (DHT) on [3H]thymidine and [3H]proline incorporation were investigated in cultured ulna shafts from male and female rats. Ulnae were cultured and loaded to produce physiological strains in the presence or absence of 10−8 M E2 or DHT. Loading engendered similar increases in incorporation of [3H]thymidine and [3H]proline in male and female bones. E2 engendered greater increases in incorporation in females than in males, and DHT greater increases in males than in females. In males E2 with loading produced increases in both [3H]thymidine and [3H]proline incorporation, which approximated to the arithmetic addition of the increases due to E2 and loading separately. In females E2 with loading produced increases greater than those in males, and substantially greater than the addition of the effects of E2 and loading separately. Loading with DHT in males also showed additional [3H]thymidine and [3H]proline incorporation. In females there was additional incorporation of [3H]proline, but not [3H]thymidine. The location of incorporation of [3H]thymidine and [3H]proline was consistent with their level of incorporation reflecting periostea! osteogenesis, in which case the early osteogenic effects of sex hormones are gender-specific when acting alone and in combination with loading. In males the effects of estrogen and testosterone add to, but do not enhance, the osteogenic responses to loading. In females testosterone with loading produces an additional effect on [3H]proline incorporation but no greater effect than loading alone on that of [3H]thymidine. In contrast, estrogen and loading together produce a greater effect than the sum of the two influences separately. Because premenopausal bone mass will have been achieved under the influence of loading and estrogen acting together, these findings suggest that the bone loss which follows estrogen withdrawal may result, at least in part, from reduction in the effectiveness of the loading-related stimulus on bone cell activity. This stimulus is normally responsible for maintaining bone mass and architecture.
Constitutive expression of non-bone/liver/kidney alkaline phosphatase in human osteosarcoma cell lines
Authors: Dr. Ali Nadire N. , Rowe Janice , Teich Natalie M. 
Published: February 2010

Abstract
Alkaline phosphatase (ALP) plays an important role in bone mineralization; high levels in differentiated osteoblasts allows their identification easily in vitro. It is generally assumed that the activity of ALP in osteosarcomaderived cell lines commonly used in studies of bone cell biology is exclusively due to the bone/liver/kidney (BLK) isoenzyme. However, we noted that two human osteosarcoma cell lines, U-2 OS and U-393 OS, predominantly expressed a truncated 1.8 kb mRNA for BLK-ALP. This observation stimulated further investigation upon the ability of ALP to form functional protein. We found that, unlike the BLK-ALP of the Saos-2 osteosarcoma cell line, the activity of U-2 OS ALP was thermostable, unaffected by L-homoarginine and levamisole, but inhibited by L-phenylalanine; these properties are characteristic of the placental and/or placental-like (PL-/PL-like ALP) isoenzymes which are 98% homologous at the amino acid level. In the U-393 OS cell line, which expresses the normal-sized 2.5 kb mRNA in substantially higher levels than that produced by U-2 OS cells, the ALP activity had kinetic properties very similar to that produced by the Saos-2 line for all criteria tested. The HOS osteosarcoma cell line (also known as TE-85), which expresses the normal-sized 2.5 kb BLK-ALP mRNA only, exhibited ALP activity with kinetic properties of both the BLK and PL-/PL-like isoenzymes. The three test lines, U-2 OS, U-393 OS and HOS, produced PL-/PL-like ALP mRNA and protein constitutively, and levels of these increased in cells treated with 1 μM dexamethasone. However, dexamethasone treatment of cells did not alter the types of ALP isoenzyme expressed. Thus our results show that, like Saos-2 cells, U-393 OS cells produce active BLK-ALP exclusively, whereas U-2 OS cells produce PL-/PL-like ALP only, and the HOS cell line produces both. Our findings have important implications for phenotypic characterization of various human osteosarcoma cell lines, and suggest that the production of PL-/PL-like ALP may be a more common occurrence in osteosarcomas than was originally thought.
Establishment of bone morphogenetic protein 2 responsive chondrogenic cell line
Authors: Aikawa Tomonao , Shirasuna Kanemitsu , Iwamoto Masahiro , Watatani Kazuya , Nakamura Takashi , Okura Masaya , Yoshioka Hideo , Matsuya Tokuzo 
Published: February 2010

Abstract
A clonal cell line named RMD-1 was established from the skeletal muscle of a 20-day fetal rat. RMD-1 represents a morphologically homogeneous population of undifferentiated mesenchymal cells, expressing α-smooth muscle actin and type I collagen, but no cartilage-associated genes. When cultured in agarose gel containing 100 ng/ml of recombinant human bone morphogenetic protein 2 (rhBMP-2; BMP-2), RMD-1 cells formed colonies and showed chondrocyte-like features as assessed by their ultrastructure, metachromatic staining with toluidine blue, and the production of large hydrodynamic-size proteoglycans. RMD-1 cells also differentiated into chondrocytes when the cells were plated at high density (over 2.5 × 105 cells/cm2) on type I collagen and incubated in medium containing 0.5% fetal bovine serum and 100 ng/ml of BMP-2. This chondrogenic differentiation was evidenced by a distinct morphological change into spherical cells, an increase in the levels of sulfated glycosaminoglycans, a decrease in type I collagen mRNA and the expression of cartilage-associated genes, including type II collagen, type IX collagen, aggrecan and alkaline phosphatase. In the presence of ascorbic acid and 10% serum, RMD-1 cells increased in size and expressed type X collagen as well as high alkaline phosphatase activity, then induced matrix mineralization. Thus, RMD-1 is a unique cell line that can differentiate from undifferentiated mesenchymal cells into hypertrophic chondrocytes.
Doubling skeletal mass during adult life: The syndrome of diffuse osteosclerosis after intravenous drug abuse
Authors: Dr. Whyte Michael P. , Teitelbaum Steven L. , Reinus William R. 
Published: February 2010

Abstract
A former intravenous substance abuser, seropositive for hepatitis C virus infection, was referred for diffuse osteosclerosis. There was no history of fracture or skeletal deformity. Cortical and trabecular bone density was approximately twice the mean value for controls. Skeletal histology revealed dense lamellar bone. Recognized causes of acquired generalized osteosclerosis or hyperostosis were excluded. This patient verifies the syndrome of painful diffuse osteosclerosis after intravenous drug abuse and shows that skeletal mass can be markedly increased with histologically normal, structurally sound bone during adult life. Elucidation of the etiology and pathogenesis could offer an effective treatment for osteoporosis.
Phosphorylation of the cytoplasmic tail of the PTH/PTHrP receptor
Authors: Blind Eberhard , Bambino Tom , Huang Zhengmin , Bliziotes Michael , Nissenson Robert A. 
Published: February 2010

AbstractActivation of the G protein–coupled receptor for parathyroid hormone (PTH)/PTH-related protein (PTHrP) produces homologous desensitization of receptor signaling. We have shown recently that the opossum PTH/PTHrP receptor stably expressed in human embryonic kidney (HEK) 293 cells is phosphorylated upon agonist binding and upon activation of serine/threonine protein kinases (PKA and PKC), an event which for some G protein-coupled receptors has been linked to desensitization. To locate the sites of phosphorylation, mutated forms of the opossum PTH/PTHrP receptor were stably expressed in HEK 293 cells, and ligand-stimulated receptor phosphorylation was evaluated. The five serine and threonine residues of the third cytoplasmic loop of the receptor were not required for receptor phosphorylation. Basal and ligand-induced phosphorylation were, however, completely abolished upon deletion of all but the 16 juxtamembrane residues of the cytoplasmic C-terminal tail of the receptor, even though this truncated receptor resembled the wild-type receptor in its level of expression based on Western blotting and radioligand binding. To identify further the phosphorylation sites, the 129 amino acid C-terminal tail of the rat PTH/PTHrP receptor was expressed in E. coli as a recombinant glutathione S-transferase fusion protein. Elimination of a single PKA consensus site in the tail (serine 491) resulted in ≥90% loss of PKA-mediated phosphorylation, identifying this as the preferential site for PKA, with two other sites (serine 473 and/or 475) being minor sites. Phosphorylation by PKC occurred largely in the proximal portion of the tail, whereas β-adrenergic receptor kinase 1 (βARK1) phosphorylated more distally in the tail. The ability of these kinases to phosphorylate the PTH/PTHrP receptor at distinct sites on the cytoplasmic tail may allow differential regulation of receptor signaling and trafficking.
Administration of the bisphosphonate ibandronate (BM 21.0955) by intravenous bolus injection
Authors: Pecherstorfer Martin , Ludwig Heinz , Schlosser Karl , Buck Signe , Huss Hermann-Josef , Body Jean-Jacques 
Published: February 2010

Abstract
Bisphosphonates (BPs) are used for the treatment of both benign and malignant diseases characterized by increased bone resorption. Because of their potential nephrotoxicity, currently available BPs have to be administered by slow intravenous infusion, with conventional doses requiring an infusion time of at least 2 h. In the present investigation, we evaluated the safety and efficacy of the new BP ibandronate as administered by intravenous bolus injection. On day 0, 15 normocalcemic breast cancer patients with bone metastases were treated with 3 mg of ibandronate injected intravenously over 60–120 s. Ibandronate treatment led to significant decreases in serum levels of calcium (p &lt; 0.0001) and phosphate (p &lt; 0.0001) and to subsequent increases in serum concentrations of parathyroid hormone (p &lt; 0.0001) and calcitriol (p &lt; 0.0001). Moreover, there was a significant reduction in the urinary excretion of calcium (p &lt; 0.0001), pyridinoline (p &lt; 0.001), and deoxypyridinoline (p &lt; 0.0001). Three serious adverse events were observed: vomiting (WHO grade 3), pulmonary infection (WHO grade 2), and deterioration of a pre-existing impaired glucose tolerance (WHO grade 3). Only vomiting appeared to be related to administration of the drug. The most frequent nonserious adverse events were 10 cases of transient clinically asymptomatic hypocalcemia and 8 cases of asymptomatic hypophosphatemia. Serum levels of creatinine and urea nitrogen did not increase, nor did creatinine clearance deteriorate. When tested with the dipstick method, proteinuria was present in five (33%) patients prior to ibandronate treatment (median protein concentration, 30 mg/dl). Following the BP injection, seven (47%) patients showed slight (highest protein concentration, 30 mg/dl) transient proteinuria at at least one time point, of which six cases appeared in conjunction with leucocyturia and three with microhematuria. Side effects specific to aminosubstituted BPs (fever, reduction in white blood cell counts, and lymphocyte counts) were not seen in these 15 patients. In conclusion, a single intravenous injection of 3 mg of ibandronate significantly inhibited osteoclast activity as reflected by the decrease in serum calcium and in urinary parameters of bone resorption. Serum creatinine levels and estimates of creatinine clearance were not affected by therapy. However, before repeated bolus injections of ibandronate at this dosage can be recommended for further clinical trials, whether a relationship exists between the transient pathological urinary findings and injected ibandronate needs to be determined.
Dual X-ray absorptiometry quality control: Comparison of visual examination and process-control charts
Authors: Lu Ying , Mathur Ashwini K. , Blunt Barbara A. , Glüer Claus C. , Will A. Steve , Fuerst Thomas P. , Jergas Michael D. , Andriano Kim N. , Cummings Steven R. , Genant Harry K. 
Published: February 2010

Abstract
Dual X-ray absorptiometry (DXA) is widely used to monitor treatment efficacy in reducing the rate of bone mineral loss. In order to assure the validity of these measurements, instrument quality control of the DXA scanners becomes very important. This paper compares five quality control procedures (visual inspection, Shewhart chart with sensitizing rules, Shewhart chart with sensitizing rules and a filter for clinically insignificant mean changes, moving average chart and standard deviation, and cumulative sum chart [CUSUM]) in their ability to identify scanner malfunction by means of (1) an analysis of five longitudinal phantom data sets that had been collected during a clinical trial and (2) an analysis of simulated data sets. The visual inspection method is relatively subjective and depends on the operator's experience and attention. The regular Shewhart chart with sensitizing rules has a high false alarm rate. The Shewhart chart with sensitizing rules and an additional filter for clinically insignificant mean changes has the lowest false alarm rate but a relatively low sensitivity. The CUSUM method has good sensitivity and a low false alarm rate. In addition, this method provides an estimate of the date a change in the DXA scanner performance might have occurred. The method combining a moving average chart and a moving standard deviation chart came closest to the performance of the CUSUM method. Comparing the advantages and disadvantages of all methods, we propose the use of the CUSUM method as a quality control procedure for monitoring DXA scanner performance. For clinical trials use of the more intuitive Shewhart charts may be acceptable at the individual sites provided their scanner performance is followed up by CUSUM analysis at a central quality assurance center.
Dual-energy X-ray absorptiometry for histologic bone sections
Authors: Dr. Denissen Harry , De Blieck Jolanda , Verhey Hans , Klein Christel , Van Lingen Arthur 
Published: February 2010

Abstract
In fundamental osteoporosis research precise and accurate assessment of the mineral quantity in histological bone sections is of particular importance when studying the local effects of implants releasing bone modulating agents. A potentially useful technique to estimate the bone mineral density (BMD) is dual-energy X-ray absorptiometry (DXA). A highly collimated (0.13 mm) Hologic 2000 with a line spacing and point resolution of 0.13 mm was used. The mineral content was measured in regions of 3.1 mm2. A ceramic hydroxyapatite (CHA) phantom was developed as a reference standard. The phantom was made of a single-phase hydroxyapatite starting powder by compressing and sintering at 1000°C. The true density was 3.14 + 0.001 g/cm3. The calcium/phosphorus ratio was close to the theoretical one of 1.67. The mean precision error expressed as the coefficient of variation (CV) of the mineral density (MD) measurements of the phantoms with thicknesses of 1, 2, and 3 mm was 0.2%. Embedded undecalcified alveolar bone sections of dogs (0.0015-1 mm in thickness) were scanned simultaneously with a phantom 1 mm in thickness. The precision error (CV) of the BMD measurements calculated by DXA for sections ≥0.1 mm and with a BMD ≥0.14 g/cm2 was 0.81%. There was a linear relationship between the BMD calculated by DXA and the estimated BMD in the histological bone sections by means of the true density of the phantom. It is concluded that DXA using a standard CHA phantom is a precise and accurate method to measure MD changes as small as 1% in histological bone areas of 3.1 mm2 provided that the loss or gain in BMD is ≥0.14 g/cm2.