bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alteration of Vitamin D metabolism in mexican-Americans
Authors: Reasner Charles A. , Dunn James F. , Fetchick Diane A. , Mundy Gregory R. , Liel Yair , Hollis Bruce W. , Shary Judith , Bell Norman H. , Epstein Sol 
Published: February 2010

Abstract
Studies were performed to investigate vitamin D metabolism in Mexican-Americans. Groups of 15 whites and 16 Mexican-Americans ranging in age from 18 to 41 years were evaluated. All of them were within 25% of their ideal body weight. Each of them was admitted to the Clinical Research Center of the University of Texas Health Science Center and placed on a daily diet estimated to contain 400 mg calcium and 900 mg phosphate. It was found that whereas serum vitamin D (1.8 ± 0.5 versus 7.6 ± 1.3 ng/ml, P &lt; 0.001) and serum 25-hydroxyvitamin D (9 ± 1 versus 17 ± 2 ng/ml, P &lt; 0.01) were significantly lower and serum 1,25-dihydroxyvitamin D (37 ± 2 versus 28 ± 2 pg/ml, P &lt; 0.001) was significantly higher in the Mexican-Americans than in the whites, serum calcium (9.1 ± 0.1 versus 9.2 ± 0.1 mg/dl), magnesium (1.84 ± 0.07 versus 1.80 ± 0.07 mEq/liter), and Gla protein (19 ± 3 versus 21 ± 2 ng/ml) were not different in the two groups. Urinary calcium (144 ± 14 versus 124 ± 16 mg/day), phosphate (672 ± 51 versus 683 ± 44 mg/ day), sodium (110 Ω 8 versus 99 ± 9 mEq/day), potassium (43 ± 4 versus 49 ± 3 mEq/day), and magnesium (7.3 ± 0.7 versus 7.7 ± 0.5 mEq/day) and creatinine clearance (173 ± 14 versus 154 ± 7 liters/day) were not different in the two groups. Serum immunoreactive PTH (390 ± 25 versus 299 ± 21 pg/ml, P &lt; 0.02) was significantly higher in the Mexican-Americans than in the whites and urinary cyclic AMP (2.64 Ω 0.27 versus 2.59 ± 0.39 nM/dl GF) was not different in the two groups. The results indicate that Mexican-Americans are depleted of vitamin D and, as a result, have low serum 25-hydroxyvitamin D and compensatory increases in serum immunoreactive PTH and 1, 25-dihydroxyvitamin D. The depletion of vitamin D in Mexican-Americans is attributed to increased skin pigment
Concentration of Bone elements in osteoporosis
Authors: Baslé M. F. , Rebel A. , Mauras Y. , Allain P. , Audran M. , Clochon P. 
Published: February 2010

Abstract
In aging and in osteoporosis, decreased bone density is associated with decreased bone mass. However, changes in the bone mineral phase remain a matter for investigation. In particular, it is unknown whether bone mineral loss is directly related to reduction in bone mass or associated with changes in the concentration of mineral elements in mineralized bone tissue. In this study, the cortical bone concentration of elements was determined in biopsies of the ilium from 33 subjects (12 controls and 21 individuals with untreated severe osteoporosis). Calcium and phosphorus concentrations were evaluated in cortical and trabecular bone using energy-dispersive x-ray (EDX) microanalysis and inductively coupled plasma optical emission spectrometry (ICPOES). Bone concentrations of Na, K, Mg, Cu, Zn, Fe, Sr, Al, B, and Si were also determined in cortical bone using ICPOES. Additionally, the concentration of F in cortical bone was measured with a specific ion electrode and the concentration of Pb was determined by atomic absorption spectrometry. In mineralized bone tissue there was no significant age-dependent variation in the concentration of Ca, P, or other elements either in controls or in osteoporotic subjects. Moreover, the concentration of elements in bone tissue did not differ in the two groups. These results suggest that the decrease in bone density in osteoporosis is directly related to evolution of the bone mass, without detectable changes in the concentration of elements in bone
Production of both interleukin-lα and ß by newborn mouse calvarial cultures
Authors: Lorenzo Joseph A. , Sousa Sandra L. , Van Brink-Webb Suzanne E. Den , Korn Joseph H. 
Published: February 2010

Abstract
The conditioned medium (CM) from 4–6 day newborn mouse calvarial cultures was found to contain thymocyte comitogen proliferation activity. This activity was blocked by an antiserum to murine interleukin-1α (IL-1α) but not by an antiserum to murine interleukin-1ß. The release of thymocyte comitogen proliferation activity from the cultures did not appear dependent on endotoxin and was not associated with detectable interleukin-2 activity in the CM. Activity in the CM eluted from a gel filtration column with a peak Mr of 16–18 kD (the Mr of mature murine IL-1α and ß is 17 kD). Western immunoblots of 100-fold concentrated CM demonstrated only a single 33 kD band with an antiserum to murine IL-1ß and no bands with an antiserum to murine IL-1α. However, this assay was relatively insensitive (limit of detection 1–10 ng compared with 1–10 pg for the thymocyte comitogen proliferation assay). Immunoprecipitation of [35S]methionine-labeled CM with three different anti-IL-1α antisera, a more sensitive assay, demonstrated 15–17 kD bands in all cases.
These results demonstrate that 4–6 day newborn mouse calvarial cultures spontaneously release 17 kD IL-1α and 33 kD IL-1ß into their conditioned medium. It appears that although 17 kD IL-1α is the major bioactive form in the CM, 33 kD IL-1ß is present in greater amounts. These results also suggest that local production of IL-1 can regulate bone cell function and may play a role in bone growth and remodeling
Long-term organ culture of embryonic chick femora: A system for investigating bone and cartilage formation at an intermediate level of organization
Authors: Roach Helmtrud I. 
Published: February 2010

Abstract
Bone organ culture is an experimental system in which skeletal cells remain within their extracellular matrix but are removed from systemic influences. Femurs from 14-day-old chick embryos, which contain bone and cartilage matrix in approximately equal proportions, were cultured for up to 9 days in a serum-free medium. Cell proliferation, differentiation into chondrocytes and osteoblasts, formation of bone and cartilage matrix, and in vitro mineralization as well as bone and cartilage resorption were assessed using histologic and analytic methods. Particular attention was paid to the differences between cartilage and bone growth and to interpreting analytic data in the light of histologic observations.
The first 2 days of culture represented an “adaptation” period, characterized by the release of intracellular enzymes into the culture medium, probably as a consequence of cell breakdown. Days 3–9 in culture represented a period of “steady growth” during which skeletal cells continued to multiply in the absence of fetal serum and to secrete large amounts of bone and cartilage matrix. De novo mineralization could be induced by Ca-ß-glycerophosphate, but calcium deposits in tissues other than bone and cartilage were also induced. Resorption of bone or cartilage matrix was virtually absent.
Bone organ culture facilitates the study of bone and cartilage formation at an intermediate level of organization and thereby provides the necessary link between in vivo studies and investigations at the cellular level
Effects of weight lifting on bone mineral density in premenopausal women
Authors: Gleeson Peggy Blake , Protas Elizabeth J. , Leblanc Adrian D. , Schneider Victor S. , Evans Harlan J. 
Published: February 2010

Abstract
A group of 68 premenopausal women participated in a controlled 12 month exercise program. Two groups were matched according to age, body size (body mass index), and typical activity level. Data collection included bone mineral density (BMD) of the lumbar spine with dual-photon absorptiometry and of the os calcis with single-photon absorptiometry, lean body mass, urinary calcium/creatinine, and urinary gammacarboxyglutamic acid (Gla). Subjects wer given a daily 500 mg supplement of elemental calcium.
There was no significant difference between groups in terms of diet, in urinary calcium/creatinine or Gla, or in lean body mass. The weight lifting group had a nonsignificant increase in mean lumbar BMD of 0.81% and the control group exhibited a nonsignificant decrease of 0.5%. However, a paired t-test revealed a significant difference between the matched pairs in percentage change in lumbar BMD. The os calcis showed no significant change in the means in either group or as matched pairs. The relatively small change seen as a result of this modified Nautilus exercise program may prevent moderate weight lifting from being a practical answer for osteoporosis, even in a highly motivated population
Transfection of calcitonin gene regulatory elements into a cell culture model of the C cell
Authors: Cote Gilbert J. , Abruzzese Ronald V. , Gagel Robert F. , Lips CEES J. M. 
Published: February 2010

Abstract
Calcitonin gene expression in the TT cell line can be regulated by phorbol esters, cAMP, glucocorticoids, and 1,25-dihydroxyvitamin D3. To further study the regulation of this gene we have sequenced 1460 bases 5′ to the start of calcitonin gene transcription. This DNA sequence contains cis consensus elements for both phorbol ester- and cAMP-responsive elements. To study the role of these elements, calcitonin 5′ flanking DNA was coupled to the human growth hormone gene as a reporter and transiently transfected into TT cells, a human thyroid C cell line. Treatment of transfected TT cells stimulated a two- to fivefold increase in reported gene product expression, confirming the existence of functional cAMP- and phorbol ester-dependent enhancers within the calcitonin 5′ flanking sequence
Plasma 24,25-dihydroxyvitamin D3 concentrations in x-linked hypophosphatemic mice: Studies using mass fragmentographic and radioreceptor assays
Authors: Cunningham John , Coldwell Ruth D. , Trafford David J. H. , Makin Hugh L. J. , Jones Glenville , Tenenhouse Harriet S. 
Published: February 2010

Abstract
Previous studies have suggested that both plasma 24,25-dihydroxyvitamin D [24,25-(OH)2D] concentrations and renal 25-hydroxyvitamin D-24-hydroxylase activity are increased in mice with X-linked hypophosphatemia (Hypmice). However, because the plasma levels of 24,25-(OH)2D seemed surprisingly high, we repeated these assays using two different techniques. Mass fragmentographic and radioreceptor assays were employed to compare the plasma concentrations of 25-hydroxyvitamin D (25-OHD) and 24,25-(OH)2D in normal mice with those inHypmice. These assays yielded 24,25-(OH)2D concentrations much lower than previously reported in mice (both normal andHyp). The concentrations of 25-OHD3, and 24,25-(OH)2D3, determined by mass fragmentography, were lower inHypmice than in controls [25-OHD3, 9.7 ± 0.4 versus 14.6 ± 0.6 ng/ml, p &lt; 0.01; 24,25-(OH)2D3, 7.1 ± 0.3 versus 10.4 ± 0.4 ng/ml, p &lt; 0.01]. Plasma 25-OHD concentration was the main determinant of plasma 24,25-(OH)2D, and the ratio of 25-OHD3 to 24,25-(OH)2D3 obtained from mass fragmentographic measurements did not differ between the two groups (1.40 ± 0.05 versus 1.36 ± 0.03 ng/ml, NS in normal andHypgroups, respectively). Separate measurement of plasma 25-OHD, 24,25-(OH)2D, and 25-OHD3-26,23-lactone by radioreceptor assay showed no difference between either plasma 24,25-(OH)2D, or the ratio of 25-OHD concentration to 24,25-(OH)2D concentration amongHypand control animals. In neither study was plasma phosphate concentration related to the 25-OHD3: 24,25-(OH)2D3 ratio. We conclude that previous estimations of plasma 24,25-(OH)2D3 concentrations in mice were erroneously high and, further, that in fact this metabolite is not present in increased concentration inHyp mice
Skeletal growth factor and other growth factors known to be present in bone matrix stimulate proliferation and protein synthesis in human bone cells
Authors: Wergedal Jon E. , Mohan Subburaman , Lundy Mark , Baylink David J. 
Published: February 2010

Abstract
The purpose of the study was to investigate the effect of skeletal growth factor/insulinlike growth factor II and other growth factors known to be present in bone matrix on the proliferation and differentiation of human bone cells. Cells were isolated by collagenase digestion from femoral heads obtained during hip replacement operations. Cells were cultured in DMEM medium with 10% calf serum. Third to fifth passage cells were plated in multiwell plates and the medium changed to low serum (0.1%) for 2 days. The medium was changed to serum-free medium prior to addition of growth factors. Cell proliferation was measured by the incorporation of [3H]thymidine into DNA and by the percentage of cells that incorporate bromodeoxyuridine. Protein synthesis was measured by the incorporation of [3H]proline into trichloroacetic acid-precipitable material. Skeletal growth factor/insulinlike growth factor II and insulinlike growth factor I stimulated cell proliferation and protein synthesis in a dose-dependent manner. Alkaline phosphatase-specific activity was not increased by these factors. Transforming growth factor ß1 did not affect cell proliferation but stimulated protein synthesis and increased the specific activity of alkaline phosphatase. Fibroblast growth factor did not affect any of the cell parameters. These studies suggest that skeletal growth factor/insulinlike growth factor II, insulinlike growth factor I, and transforming growth factor ß1 may play a role in the local control of the proliferation and differentiation of human osteoblasts
Regulation of calbindin-D28K gene expression by 1,25-dihydroxyvitamin D3 in chick kidney
Authors: Hall Alan K. , Professor Norman Anthony W. 
Published: February 2010

Abstract
We report here the use of a cloned cDNA for the avian calbindin-D28K (28 kD, vitamin D-dependent calcium binding protein, CaBP) to investigate the expression of the chick calbindin gene in the kidney. All three calbindin-D28K mRNA species (2000, 2600, and 3100 nucleotide transcripts) were present in the kidney tissue of chronically vitamin D-deficient (-D) chicks; this basal constitutive level of expression was, however, enhanced by administration of the vitamin D3 metabolite, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] in both a time- and dose-dependent manner. D-deficient chick renal calbindin-D28K protein levels (measured by ELISA) were maximally (twofold) stimulated by 6.5 nmole per animal of 1,25-(OH)2D3 when measured 48 h later; a concomitant level of augmentation of calbindin-D28K mRNA accumulation was also observed at this time. Time course experiments showed that enhanced renal calbindin-D28K mRNA accumulation (in −D chicks) was significantly stimulated as early as 8 h and were maximal 12 h after a single pharmacologic dose of 1,25-(OH)2D3; this elevated level of gene expression was maintained for at least 72 h.
Renal calbindin-D28K protein levels (constitutively expressed in the −D chick) were significantly stimulated (twofold) as early as 12 h following the single dose of steroid hormone; the level of calbindin-D28K also remained elevated for a minimum of 72 h. Collectively, these data indicate that 1,25-(OH)2D3 acts upon the renal calbindin-D28K gene in a manner similar to that operable in the intestine. However, significant differences exist in the responses of these two tissues, and other (tissue-specific) vitamin D-independent factors also seem to regulate the expression of the chick renal calbindin-D28K gene.
Influence of experimental conditions on osteoblast activity in human primary bone cell cultures
Authors: Chavassieux Pascale M. , Chenu Chantal , Valentin-Opran Alexandre , Merle Blandine , Delmas Pierre D. , Meunier Pierre J. , Hartmann Daniel J. , Saez Simone 
Published: February 2010

Abstract
Primary bone cell cultures were derived from human bone explants. Cellular activity was characterized by the alkaline phosphatase (AP) activity, osteocalcin, and type I and III collagen secretions in the supernatant. The determination of bone cell activity was performed in three different wells. No significant difference was noted between wells: the coefficient of variation was 8.0 + 2.9% for AP activity, 18.3 + 1.9% for osteocalcin secretion, and 22.5 + 14.3% for collagen. The AP activity and osteocalcin secretion significantly decreased with the number of passages: they were the highest after the first passage. Between each subject, the coefficient of variation was 85% for AP activity and osteocalcin secretion and 63 and 57% for type I and III collagen secretion, respectively. The AP activity did not differ with the age or sex of the donor. In contrast, osteocalcin secretion was significantly lower in females than in males. In males, osteocalcin significantly decreased with the age of the donor (r = −0.61; p &lt;0.05). Cellular activity did not depend on the site of the biopsy. When bone explants from one donor were cultured in two different petri dishes, the activity of cells was similar in both dishes, except in one case. Primary cell cultures derived from human bone explants are the only model providing untransformed osteoblastlike cells of human origin. Because of the experimental conditions, some factors may have influenced the cellular activity and they must be taken into account to validate further in vitro studies.
Effect of age on variables relating to calcium and phosphorus metabolism in women
Authors: Kotowicz Mark A. , Riggs B. Lawrence , Melton L. Joseph , Cedel Sandra L. , O'Fallon W. Michael 
Published: February 2010

Abstract
Lack of adequate data concerning the effect of age on biochemical variables relating to bone and mineral metabolism hampers research on age-related bone loss in women. Furthermore, to detect disease and to monitor therapy, clinical laboratories require reference values derived from an appropriate population sample. Therefore, we determined the age-specific distribution of values for serum concentrations of calcium, inorganic phosphorus, alkaline phosphatase, bone Gla protein, and parathyroid hormone; for creatinine clearance; for fasting urinary calcium:creatinine ratio; and for 24 h urinary excretion of calcium, hydroxyproline, and cyclic AMP in a population-based sample of 301 white women. From this sample, a healthy subgroup of 181 women was identified by medical record review. Age-related effects were seen in all variables except serum calcium and phosphorus. Moreover, substantial differences between the population sample and the healthy subgroup were noted in values for creatinine clearance, serum alkaline phosphatase, and 24 h urinary calcium excretion. These observations may prove useful for assessment of normality in other populations of aging white women.
Effect of season on physical activity score, back extensor muscle strength, and lumbar bone mineral density
Authors: Bergstralh Erik J. , Offord Kenneth P. , Sinaki Mehrsheed , Wahner Heinz W. , Melton L. Joseph 
Published: February 2010

Abstract
Seasonal variation in physical activity, back extensor muscle strength (BES), and bone mineral density (BMD) of the lumbar spine was studied in 65 healthy postmenopausal women. Physical activity score (PAS) was assessed with an ordinal scale (0-18); this score and the BES were obtained monthly for 2 years (25 readings). BMD values were obtained semiannually (5 readings). A periodic (cosine) regression model was fit to each subject's PAS and BES data to obtain individual estimates of the annual peak day d and the average annual range due to seasonality. There was a strong (P &lt; 0.001) seasonal pattern in physical activity; August 3 was the average peak day, and the seasonal range was 2.0 PAS units. There was modest (P = 0.047) seasonality in BES; June 6 was the estimated peak day, and the seasonal range was 8.22 pounds (about 7% of the mean). BMD averaged 0.015 g/cm2 higher in August through November than February through May (P = 0.002), and the highest monthly average BMD was in August. This seasonal range of 1.4% is larger than the average annual decline with age in BMD observed in longitudinal studies of postmenopausal women. The results of this study have important implications for the planning of longitudinal studies involving changes in physical activity or bone mass in geographic areas with diverse seasons.
Correlation of an osteoclast antigen and ruffled border on giant cells formed in response to resorbable substrates
Authors: Webber David , DR. OSDOBY Philip , Krukowski Marilyn , Hauschka Peter 
Published: February 2010

Abstract
The osteoclast is the specialized multinucleated cell primarily responsible for the degradation of the organic and inorganic components of bone matrix. The functional and developmental relationship between osteoclasts and foreign body giant cells is unclear. The osteoclast plasma membrane ruffled border juxtaposed to the bone surface is a unique morphologic characteristic of active osteoclasts. In the studies reported here giant cell formation was induced in response to a variety of materials implanted onto the richly vascularized chick chorioallantoic membrane. Light and electron microscopic techniques were used to examine the morphologic characteristics of the giant cells. In addition, immunohistochemical methods were used to demonstrate the appearance of a 150 kD cell surface antigen on chicken osteoclasts recognized by monoclonal antibody 121F. Giant cells that formed in response to mineralized bone particles exhibited ruffled borders and stained positively with the 121F antibody. Many giant cells that formed in response to hydroxyapatite possessed ruffled borders similar to but not as extensive as those observed on giant cells formed on bone. Immunohistochemical localization of the 121F antigen on these cells suggested that the antigen was present, but staining intensity was reduced compared to that of bone-associated giant cells. The formation of mineral matrix complexes by the adsorption to hydroxyapatite of bone extract or osteocalcin enhanced ruffled borders and the presence of the 121F antigen on elicited giant cells. In contrast, giant cells that formed on non-resorbable materials, such as Sepharose beads, mica, and methacrylate, lacked ruffled borders and were negative for the 121F antigen. It appears that expression of the 121F osteoclast antigen correlates with the appearance and extent of ruffled membranes on giant cells. Furthermore, it appears that giant cell ruffled membrane development and the presence of the 121F osteoclast antigen are related to giant cell formation in response to resorbable materials that are subject to extracellular dissolution. Expression of this antigen may be indicative of the developmental and/or functional state of giant cells (osteoclasts) that form on resorbable substrates. In addition, components of the bone matrix, including osteocalcin, in association with bone mineral, lead to elevated levels of this osteoclast antigen.