bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative immunocytochemical study on the subcellular distributions of 44 kDa bone phosphoprotein and bone γ-carboxyglutamic acid (Gla)-containing protein in osteoblasts
Authors: Mark Manuel P. , Prince Charles W. , Gay Steffen , Austin Ronald L. , Bhown Merra , Finkelman Richard D. , Dr. Butler William T. 
Published: February 2010

Abstract
Bone γ-carboxyglutamic acid (Gla)-containing protein (BGP or osteocalcin) and 44 kDa bone phosphoprotein (44K BPP, also called Sialoprotein I or osteopontin) have been localized at the ultrastructural level in osteoblasts from woven bones of newborn rats. Frozen, undecalcified sections of periodate-lysine-paraformal-dehyde fixed specimens were incubated with affinity purified, monospecific antibodies against BGP or 44K BPP. The sites of the antigen-antibody reaction were demonstrated by the avidin-biotin-peroxidase complex method using the Hanker-Yates reagent as a peroxidase substrate. In some cases immunostaining could only be achieved after detergent treatment. The immunostained sections were then flat-embedded in Epon 812 and processed for electron microscopy. Strong specific intracellular labeling was obtained with both antibodies, but the patterns of staining differed significantly: BGP antigenicity was mainly located in the endoplasmic reticulum (ER), whereas 44K BPP behaved as a Golgi-specific antigen. In both cases, however, we found no evidence for immunostained secretory vesicles. There was no correlation between the expression of BGP by osteoblasts and the morphological aspect of these cells, their apparent degree of polarization with respect to the bone matrix, or their relation with the mineralized phase.
Increase in serum parathyroid hormone concentration in the lactating rat: Effects of dietary calcium and lactational intensity
Authors: Garner Sanford C. , Peng Tai-Chan , Hirsch Philip F. , Boass Agna , Toverud Svein U. 
Published: February 2010

Abstract
The change in circulating levels of immunoreactive parathyroid hormone (iPTH), measured with an N-terminal specific radioimmunoassay, was examined during lactation in rats. In lactating rats consuming a diet containing 0.4% Ca (basic diet), serum iPTH was a) increased by an average of 53% between days 10 and 18 compared to the level of age-matched nonlactating rats (24.7 ± 2.1 pg/ml vs 16.1 ± 0.8 pg/ml, mean ± SE, p &lt; 0.01) and b) significantly higher in dams suckling large litters (10–15 pups) than in dams suckling small litters (3 pups) over the period 3–13 days of lactation. Lactating rats consuming a low calcium diet (0.04% Ca), had serum iPTH levels on days 16–18 of lactation approximately twice those of nonlactating rats fed the same diet and 73% higher than those of lactating rats fed the basic diet. Serum Ca concentrations were 22% and 10% lower in dams consuming the 0.04 and 0.4% Ca diets, respectively, than in the nonlactating controls fed the same diets. Regression analysis showed a significant (p &lt; 0.001) negative correlation between iPTH and total serum calcium. Compared with nonmated controls, net mineral loss from femurs of dams consuming the 0.4% Ca diet was a) insignificant at day 6, b) 27% at day 15, and c) 34% at day 21 of lactation. Our data demonstrate that lactation in the rat is characterized by hyperparathyroidism that appears to be related to lactational intensity and that is accentuated when dietary calcium intake is restricted. The decrease in bone mineral during the period of elevated serum iPTH also suggests that parathyroid hormone plays a role in the bone loss normally seen in lactating rats.
Signal sequence of human preproparathyroid hormone is inactive in yeast
Authors: Dr. Born W. , Freeman M. , Bornstein W. , Rapoport A. , Klein R.D. , Hendy G.N. , Khorana H.G. , Rich A. , Potts J.T. , Kronenberg H.M. 
Published: February 2010

Abstract
The biosynthesis of human preproparathyroid hormone (hpreproPTH) and the processing to mature parathyroid hormone (hPTH) was investigated in yeast. Cells were transformed with a plasmid that carried a fusion gene made of the yeast pyruvate kinase promoter, complementary DNA (cDNA) encoding a slightly modified form of hpreproPTH and the transcription termination signal from yeast triosephosphate-isomerase. In transformed yeast cells we identified a protein that was recognized by a PTH antiserum and, on gel electrophoresis, comigrated with hpreproPTH marker. The amino-terminal sequence of the protein was consistent with that of hpreproPTH, indicating that the hormone precursor is not processed. It was localized inside the cell, when analyzed in pulse-chase experiments by trypsin accessibility in intact and lysed spheroplasts. In contrast, when mRNA from these yeast cells and from human parathyroid tissue was translated into preproPTH in a reticulocyte lysate supplemented with canine pancreatic microsomes, the preproPTHs from both mRNAs were transported and cleaved with identical efficiencies. We conclude that hpreproPTH is synthesized in yeast but not recognized and processed like a precursor of a secreted protein by the yeast secretory apparatus.
Effect of age on circulating immunoreactive and bioactive parathyroid hormone levels in women
Authors: Forero Martha Susana , Klein Robert F. , Nissenson Robert A. , Nelson Karen , Iii Hunter Heath , Arnaud Claude D. , Riggs Lawrence B. 
Published: February 2010

Abstract
Although levels of serum immunoreactive parathyroid hormone (iPTH) increase with age in women, this could be caused by retention of non-biologically active PTH fragments by the aging kidney. In 102 normal women, aged 30 to 89 yr, serum iPTH increased with age by 58% (r = 0.33, p &lt; 0.001) with antiserum GP-1M (which has midmolecule specificity) and 43% (r = 0.32, p &lt; 0.001) with antiserum CH-12M (which may have whole molecule specificity); urinary cAMP/GFR excretion increased by 29% (r = 0.22, p &lt; 0.05). The results of these assays were validated by comparison with serum levels of biologically active PTH (BioPTH) in immunoextracts of serum followed by renal adenylate cyclase assay in a selected subgroup of 25 of the women. Serum BioPTH correlated with serum iPTH assessed by antiserum GP-1M (r = 0.48, p &lt; 0.05) and antiserum CH-12M (r = 0.48, p &lt; 0.05) but not with urinary cAMP. The data are consistent with an increase of parathyroid function with aging: clearly, we do not find decreased parathyroid function as would be expected if age-related bone loss was not mediated, in part, by PTH.
Radioimmunoassay for osteonectin. Concentrations in bone, nonmineralized tissues, and blood
Authors: Malaval Luc , Fournier Brigitte , Delmas Pierre D. 
Published: February 2010

Abstract
We describe a double antibody radioimmunoassay for the bone protein osteonectin using a polyclonal antibody raised against bovine fetal bone osteonectin. This assay, which cross-reacts with human osteonectin, was used to explore the tissue distribution of the protein. Osteonectin was detected in extracts of nonmineralized tissues from bovine fetuses, with concentrations ranging from 10 ng/100 μg of proteins in the lens to about 80 ng/100 μg in collagen-rich tissues (e.g., tendon), which represents respectively from 0.01% to 0.5% of the concentrations found in bone extracts. Osteonectin is thus a widespread component of extracellular matrix, although its concentration is minute in tissues other than bone and dentin. Adult human serum contains 200 ng/ml of osteonectin and values obtained in plasma prepared without platelet activation are about one-third of those in matched sera. This platelet-independent fraction might be used as a marker for bone metabolism.
The assessment of bone formation and bone resorption in osteoporosis: A comparison between tetracycline-based iliac histomorphometry and whole body 85Sr kinetics
Authors: Dr. Reeve J. , Arlot Monique E. , Chavassieux Pascale M. , Edouard Claude , Green J.R. , Hesp R. , Tellez Marisol , Meunier P.J. 
Published: February 2010

Abstract
Bone formation and resorption have been measured in patients with idiopathic osteoporosis by histomorphometry of 7.5-mm trephine biopsies and in the whole body by 85Sr radiotracer methodology and calcium balances. The studies were synchronized and most were preceded by double in vivo tetracycline labeling. Correlations between histological and kinetic bone formation indices were better when based on the extent of double tetracycline labels than on measurements of osteoid by visible light microscopy. Correction of the kinetic data for long-term exchange, using 5 months' serial whole body counting of retained 85Sr, improved the fit of the kinetic to the histological data. A statistical analysis of the measurement uncertainties showed that the residual scatter in the best correlations (between exchange-corrected bone formation rates and double-labeled osteoid surface indices) could be attributed to measurement imprecision alone.
The exchange-corrected resorption rate correlated fairly well with iliac trabecular resorption surfaces, and using a volume referent rather than a surface referent for the histological index improved the statistical fit when patients with therapeutically accelerated bone turnover were included. A much better correlation was obtained by including osteoid volume acting as an independent predictor of bone resorption in a bivariate regression with a resorption surface index. The residual errors could then be accounted for by known measurement uncertainties. Whereas osteoid taking a double label closely predicted the kinetic rate of bone formation, further analysis suggested that osteoid that took no label or a single label was more closely related to bone resorption, presumably as a secondary result of the coupling of bone formation to bone resorption. The idea that continued bone loss in some patients is associated with defective osteoblastic bone formation is supported by the low rates found in some patients by both techniques. Heuristically these studies validate both in vivo tetracycline labeling for dynamic histomorphometry and corrections for long-term exchange in kinetic studies of bone formation, providing a quantitative framework for the design and analysis of future studies of bone remodeling in the osteoporoses.
1,25(OH)2D levels in dihydrotachysterol-treated patients: Influence on 1,25(OH)2D assays
Authors: Taylor Arlene , Norman Michael E. 
Published: February 2010

Abstract
Many clinicians continue to prefer dihydrotachysterol (DHT) as the initial vitamin D agent of choice in hypoparathyroidism and renal osteodystrophy because of its long history of efficacy and safety. Assessment of the factors influencing the clinical response to DHT treatment should include measurement of vitamin D metabolite profiles, but investigators have heretofore been unable to measure 1,25(OH)2D because levels have been found to be falsely elevated when employing the chick intestinal cytosol receptor assay. After converting from the chick cytosol receptor assay to the calf thymus receptor assay for measuring 1,25(OH)2D, we did not note falsely elevated levels of 1,25(OH)2D in DHT-treated patients. The design of this study, therefore, was aimed at determining whether or not the calf thymus receptor measured authentic 1,25(OH)2D in such patients. We controlled for the possibility that freezing and thawing or prolonged storage might have either lowered 1,25(OH)2D levels or degraded a metabolite(s) of DHT that would have otherwise been recognized as “1,25(OH)2D” by the calf receptor. Similarly, technical differences between the two assays, source of thymus, and potential interference by other cytosolic proteins were eliminated as causes for the difference between the 1,25(OH)2D levels in the two assays. Our experiments do not provide an explanation for why the thymus receptor does not “see” the interfering metabolite(s) of DHT. This could reflect either a tissue difference or perhaps a species difference. Our results do provide the first opportunity to expand the investigation of the metabolic effects of DHT therapy to include changes in intrinsic 1,25(OH)2D metabolism.
Two forms of parathyroid hormone-like adenylate cyclase-stimulating protein derived from tumors associated with humoral hypercalcemia of malignancy
Authors: Stewart Andrew F. , Burtis William J. , Wu Terence , Goumas Douglas , Broadus Arthur E. 
Published: February 2010

Abstract
Tumors associated with humoral hypercalcemia of malignancy (HHM) contain parathyroid hormone-like adenylate cyclase-stimulating proteins (hACSPs). We previously purified a 17,000 MW hACSP from an HHM-associated breast carcinoma. This report describes the characterization of hACSPs from three additional HHM-associated tumors: two typical HHM-associated tumors (squamous carcinomas) and a third unusual tumor type (pheochromocytoma).
Each tumor was extracted in acid-urea/ethanol-sodium chloride, and adenylate cyclase-stimulating activity (ACSA) was examined following reverse-phase and size-exclusion HPLC and isoelectric focusing. Each tumor contained a high molecular weight form of ACSA which co-eluted with the 17,000 molecular weight breast carcinoma hACSP in each of the three separation procedures. Each also contained a lower molecular weight form(s) of ACSA (6,000–9,000 molecular weight). Both forms were inhibited by Nle8,18Tyr34bPTH(3–34) amide. The high molecular weight form was not changed to the lower molecular weight form by a reducing agent.
Some HHM-associated tumors contain two forms of hACSP, one with a molecular weight of 17,000 and another with a molecular weight of 6,000–9,000, which appears to be an amino-terminal cleavage product of the larger protein.
Bone density of the radius, spine, and proximal femur in osteoporosis
Authors: Mazess Richard B. , Barden Howard , Ettinger Mark , Schultz Eloy 
Published: February 2010

Abstract
Bone mineral density (BMD) was measured in 140 normal young women (aged 20 to 39 years) and in 423 consecutive women over age 40 referred for evaluation of osteoporosis. Lumbar spine and proximal femur BMD was measured using dual-photon absorptiometry (153Gd), whereas the radius shaft measurement used single-photon absorptiometry (125I). There were 324 older women with no fractures, of which 278 aged 60 to 80 years served as age-matched controls. There were 99 women with fractures including 32 with vertebral and 22 with hip fractures. Subsequently, another 25 women with hip fractures had BMD measured in another laboratory; their mean BMD was within 2% of that of the original series. The mean age in both the nonfracture and fracture groups was 70 ± 5 years. The BMD in the age-matched controls was 20% to 25% below that of normal young women for the radius, spine, and femur, but the Ward's triangle region of the femur showed even greater loss (35%). The mean BMD at all sites in the crush fracture cases was about 10% to 15% below that of age-matched controls. Spinal abnormality was best discriminated by spine and femoral measurements (Z score about 0.9). In women with hip fractures, the BMD was 10% below that of age-matched controls for the radius and the spine, and the BMD for the femoral sites was about 25% to 30% below that of age-matched control (Z score about 1.6). Femoral densities gave the best discrimination of hip fracture cases and even reflected spinal osteopenia. In contrast, neither the spine nor the radius reflected the full extent of femoral osteopenia in hip fracture.
Bone resorption by isolated chick osteoclasts in culture is stimulated by murine spleen cell supernatant fluids (Osteoclast-Activating Factor) and inhibited by calcitonin and prostaglandin E2
Authors: de Vernejoul Marie-Christine , Horowitz Mark , Demignon Josiane , Neff Lynn , Baron Roland 
Published: February 2010

Abstract
The question of whether any of the agents known to activate bone resorption in vivo or in organ cultures acts directly on the osteoclast or via intermediate target cells that secondarily secrete locally paracrine factors is important for our understanding of bone remodeling. In an attempt to clarify this issue for some of the agents, we have taken advantage of the recent progress in obtaining and culturing relatively pure populations of osteoclasts. We performed an in vitro bone-resorbing assay in which isolated and partially purified chick osteoclasts were cultured on devitalized, paired and standardized bone disks prepared from rat calvaria prelabeled with both 45Ca and 3H-proline. Some of the isolated osteoclasts attached to the devitalized bone matrix, formed a ruffled border, and acidified the bone-resorbing compartment that they established with the matrix, thereby indicating that they resorbed bone in a physiologic manner. Salmon calcitonin added to these cultures (0.3 U/ml = 60 ng/ml) and prostaglandin E2 (PGE2) (10−6M) inhibited both basal and stimulated 45Ca and 3H-proline release. Neither parathyroid hormone (PTH) 1–34 (1 U/ml), 1,25-(OH)2-D3 (10−8 and 10−9M), nor interleukin 1 (IL-1) (purified from P388D1 macrophage culture supernatant fluids or recombinant murine IL-1-alpha) (100 ng/ml) stimulated bone resorption in these cultures. In contrast, supernatant fluids from concanavalin A (Con-A)-activated murine spleen cell cultures (murine osteoclast-activating factor; OAF) consistently and significantly induced a 3- to 5-fold stimulation of bone resorption in this system.
Does Interleukin-1 affect intracellular calcium in osteoblast-like cells (UMR-106)?
Authors: Pacifici Roberto , Civitelli Roberto , Rifas Leonard , Halstead Linda , Avioli Louis V. 
Published: February 2010

Abstract
Interleukin-1 (IL-1) enhances bone resorption and formation in vitro, presumably through a primary action on osteoblasts, but the mechanism by which IL-1 activates bone cells is unknown. We investigated the possibility that the effect of IL-1 on osteoblasts is mediated through an increase in intracellular calcium [Ca++]i by studying the effects of purified human monocyte-derived IL-1 (hIL-1) and recombinant human IL-1α (rhILα) and β (rhIL-1β) on [Ca++]i in the rat osteogenic sarcoma cell line UMR 106 using indo-1, a new-generation fluorescent Ca++-sensitive probe. hIL-1 (1 U/ml) resulted in an 85.5% rise in [Ca++]i over baseline that reached a peak after 30 seconds and returned to basal levels within 60 seconds. A similar transient rise in calcium was obtained upon exposure of the UMR cells to both the hIL-1 suspension buffer and to the concentration of fetal bovine serum present in the hIL-1 buffer. This effect was not abolished either by heat inactivation of both hIL-1 and serum or by pretreatment of hIL-1 with specific rabbit antihuman-IL-1 antibody. Moreover, exposure of the UMR cells to either rhIL-1α or rhIL-1β or to a mixture of both at concentrations of 1 to 100 U/ml was not followed by any change in [Ca++]i. Our data do not support the idea that IL-1 can stimulate osteoblasts through a calcium-mediated pathway.
The effect of fluoride on bone histology in postmenopausal osteoporosis depends on adequate fluoride absorption and retention
Authors: Dr. Budden F.H. , Bayley T.A. , Harrison J.E. , Josse R.G. , Murray T.M. , Sturtridge W.C. , Kandel R. , Vieth R. , Strauss A.L. , Goodwin S. 
Published: February 2010

Abstract
Forty-one women with idiopathic postmenopausal osteoporosis have been followed for 2 years after initiation of sodium fluoride at 40–50 mg/day, given together with a daily calcium supplement of 1 gram and vitamin D2, at 50,000 IU weekly. Histological and histomorphometric analyses were done on bone biopsies taken prior to and after 1 year of treatment (mean 1.25 ± 0.35 years). Thirty patients (74%) developed the histological fluoride effect of hyperosteoidosis, while the remaining 11 patients (26%) had no change from pretreatment biopsies. Hyperosteoidosis was based on increased values for osteoid volume and/or thickened osteoid with &gt;3 lamellar bands. Based on previously reported findings, this histological evidence of hypersoteoidosis within 12–18 months of initiation of therapy provides a useful predictor of ultimate satisfactory fluoride response in terms of bone mineral accretion. No increases in bone mass (measured by neutron activation analysis) were observed at the time of the posttreatment biopsy but, according to this previous work, increases are anticipated over a further 2–3 years of treatment. Factors affecting the development of hyperosteoidosis were analyzed. Hyperosteoidosis was associated with a significantly higher dose of sodium fluoride and a significantly higher level of bone fluoride retention but without significant increase in fasting serum fluoride. Results suggest that fluoride retention depends not only on fluoride dose but also on body size, renal function, and intestinal absorptions of calcium and fluoride. There were no differences in the initial investigations between patients with and without hyperosteoidosis, with respect to age, years of postmenopause, estrogen use, initial biochemistry, or initial bone histology. In this study, fluoride dose and bone fluoride retention were the only identified factors that influenced the histological fluoride response of hyperosteoidosis.
Increased intestinal absorption of calcium in young and adult x-linked hypophosphatemic mice after the administration of 1,25-dihydroxyvitamin D3
Authors: Meyer Martha H. , Dr. Meyer Ralph A. 
Published: February 2010

Abstract
We have reported that X-linked hypophosphatemic (Hyp) and normal mice respond equally to the administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] with uptake of 45Ca from an oral test meal as judged by the isotope remaining in the fecal samples. To determine whether this was due to specific stimulation of calcium absorption, as opposed to changes in calcium secretion or transit time, 1,25(OH)2D3 was administered to 4-week-old (young) and 13-week-old (adult) normal and Hyp mice at a dose of 0.12 μg/kg per day by continual infusion from an Alzet minipump. After 3 days of infusion, absorption of 45Ca from the isolated duodenum was measured in situ. Malabsorption of calcium was shown in vehicle-treated 4-week-old Hyp mice by significantly more 45Ca remaining in the intestinal segment and by significantly reduced plasma levels and reduced skeletal levels of 45Ca. Treatment of the young mice, both normal and Hyp, with 1,25(OH)2D3 resulted in increased absorption of 45Ca, increased plasma 45Ca, and increased incorporation of 45Ca into the femur. The young Hyp mice treated with 1,25(OH)2D3 showed a significant increase in femoral ash weight. At 13 weeks of age both normal and Hyp vehicle-treated mice showed equivalent absorption of calcium, and both responded to 1,25(OH)2D3 administration with enhanced calcium absorption. At both ages plasma phosphate rose in only the Hyp mice treated with 1,25(OH)2D3, whereas plasma and urine calcium were increased in only the hormone-treated normal mice. In conclusion, 1,25(OH)2D3 stimulates the absorption of calcium in the isolated duodenum of the young Hyp mouse with equal potency to that of young normal mice.
Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice
Authors: Forster Simon , Triffitt James T. , Bauer Henrik C.F. , Brosjö Otte , Nilsson Olle S. , Smith Roger , Sykes Bryan 
Published: February 2010

Abstract
The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-α). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site.