bluuebunny/crossref_metadata_2025_split huggingface dataset:
T lymphocyte surface antigen markers in osteoporosis
Authors: Rosen Clifford J. , Usiskin Keith , Owens Marilyn , Barlascini Cornelius O. , Belsky Martin , Adler Robert A. 
Published: February 2010

Abstract
Two distinct syndromes of osteoporosis have been postulated: type I, which is characterized by accelerated bone loss occurring in women during the early postmenopausal period; and type II, an age-related process of bone loss affecting both men and women in and after the seventh decade. Recently there has been indirect evidence linking local products of the immune system with bone remodeling. We therefore studied peripheral blood profiles of specific lymphocyte phenotypes in women with type I osteoporosis and in older women and men with type II osteoporosis. The ratio of CD4-bearing (T helper) cells to CD8-bearing (T cytotoxic-suppressor) cells (CD4/CD8 ratio) was elevated in women with symptomatic type I disease. In addition there was a significant negative correlation (r = -0.62, p &lt; 0.001) between the CD4/CD8 ratio and the spinal bone mineral density measured by dual-photon absorptiometry. In contrast, older men with a history of fracture (hip or spine) had CD4/CD8 ratios similar to control men. The number of T cells bearing IL-2R or VLA-1 was not different between osteoporotic subjects and controls in either men or women. This study supports the concept that local products of the immune system may be directly or indirectly involved in the pathogenesis of type I osteoporosis.
Effects of estrogen on daylong circulating calcium, phosphorus, 1,25-dihydroxyvitamin d, and parathyroid hormone in postmenopausal women
Authors: Packer Elizabeth , Holloway Leah , Newhall Katherine , Kanwar Gurinderjit , Butterfield Gail , Marcus Robert 
Published: February 2010

Abstract
We studied the effects of estrogen on daylong circulating levels of calcium, inorganic phosphorus, parathyroid hormone (PTH), and 1,25-(OH)2D3 (calcitriol) in a group of 10 postmenopausal women (68.5 ± 1.4 years, mean ± SEM). The study was conducted under strict dietary control, with mean calcium and phosphorus intakes of 845 and 970 mg. After treatment with conjugated equine estrogens, 1.25 mg/day, for 1 month, significant decreases in fasting (0800 h) serum levels were observed for calcium (9.09 ± 0.08 versus 9.46 ± 0.10 mg/dl, p &lt; 0.01) and phosphorus (3.38 ± 0.10 versus 3.73 ± 0.08 mg/dl, p &lt; 0.01). On the 0800 h fasting specimen, midmolecule PTH concentrations were higher (44.0 ± 7.9 versus 34 ± 8.2 pg/ml, p &lt; 0.05), but intact PTH was unchanged (28.6 ± 2.7 versus 29.1 ± 1.7 pg/ml) and a rise in circulating calcitriol (39.8 ± 4.3 versus 31.6 ± 2.1 pg/ml) was marginally significant (p = 0.07). When data represented multiple samples averaged over 7 and 15 h, significant estrogen-related reductions in serum calcium and phosphorus concentrations were observed. In addition, estrogen was associated with a significant rise in the daylong (15 h) level of calcitriol (39.4 ± 4 versus 30.5 ± 2.4 pg/ml, p &lt; 0.01). Daylong mid- and intact PTH concentrations were unchanged on estrogen compared to baseline values. No significant correlations were observed between changes in fasting calcitriol level and changes in fasting concentrations of calcium, phosphorus, or PTH. Further, the rise in daylong calcitriol concentration did not correlate significantly with changes in fasting or integrated values of calcium or PTH. However, the rise in calcitriol did correlate significantly with the decrements in 3 and 7 h serum phosphorus levels (Δcalcitriol versus Δ 7 h phosphorus, r = 0.65, p &lt; 0.05; calcitriol fold-increase versus Δ 7 h phosphorus, r = 0.78, p &lt; 0.01). We conclude that the rise in circulating calcitriol on estrogen appears to be related primarily to changes in blood levels of inorganic phosphorus, not to changes in calcium and PTH, the other primary regulators of calcitriol production.
Cellular responses to mechanical loading in vitro
Authors: Dr. Haj Alicia J. El , Minter Sarah L. , Rawlinson Simon C. F. , Suswillo Rosemary , Lanyon Lance E. 
Published: February 2010

Abstract
A technique has been established in which cancellous bone biopsies may be simultaneously perfused and subjected to mechanical load bearing. Assessments of cell viability over a period of 24 h were based on the cAMP response to parathyroid hormone, intracellular lactate dehydrogenase activity, and electron micrograph morphology. Two cellular responses to mechanical loading were demonstrated similar to those that follow “osteogenic” loading in vivo, as reported previously. These were (1) a rise in intracellular G6PD in lining cells immediately after loading, and (2) an increase in RNA synthesis measured in osteocytes 6 h after loading. In vivo the osteogenic response to loading was modulated by indomethacin. In these in vitro experiments, addition of indomethacin inhibited both the loading-related G6PD and the RNA responses.
Calcium metabolism in postmenopausal osteoporosis: The influence of dietary calcium and net absorbed calcium
Authors: Hasling C. , Charles P. , Jensen F. TaagehøJ , Mosekilde L. 
Published: February 2010

Abstract
A group of 85 females aged 48-77 years with postmenopausal crush fracture osteoporosis were investigated using a 7 day combined calcium balance and calcium47 tracer kinetic turnover study to assess the influence of dietary calcium and net absorbed calcium on bone metabolism. During the study, patients were on their habitual diet, as determined by a prestudy registration. Dietary calcium was measured after double serving of all the meals. All urine and feces were collected and analyzed for calcium content. Bone mineralization rate and bone resorption rate were determined by applying the continuously expanding calcium pool model to the tracer kinetic data.
Urine calcium excretion and net absorbed calcium were correlated (r = 0.64, p &lt; 0.0001) with the following equation: urinary excreted calcium (mmol/day) = 2.4 + 0.4 x net absorbed calcium (mmol/day). Dermal calcium loss was not correlated with net absorbed calcium or urinary calcium. The net amount of absorbed calcium necessary to balance urinary and dermal losses was calculated to be 4.2 mmol calcium per day. The daily calcium intake necessary for obtaining a net absorbed calcium in excess of the urinary and dermal calcium losses and thereby ensure skeletal integrity was estimated to be 34.2 mmol calcium per day compared to an average intake of 27.9 + 7.6 (mean + SD) mmol/day.
Net absorbed calcium correlated negatively to bone resorption rate (r = -0.31, p &lt; 0.005) and positively to bone mineralization rate (r = 0.29, p &lt; 0.01) and to calcium balance (r = 0.66, p &lt; 0.0001). Dietary calcium intake and calcium balance correlated positively (r = 0.38, p &lt; 0.001). The minimum dietary calcium intake to ensure calcium balance was 34.5 mmol calcium per day when using this correlation.
We conclude that excess net absorbed calcium in postmenopausal osteoporosis is not quantitatively excreted in the urine but seems to induce a more positive calcium balance by reducing bone resorption rate and increasing bone mineralization rate. The recommended calcium allowance in Western countries does not meet the minimum dietary calcium requirement to ensure calcium balance in patients with postmenopausal osteoporosis when dermal calcium loss is also taken into account
Effects of (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate on mouse osteoclasts
Authors: Dr. Marshall Michael John , Wilson Andrew Sean , Davie Michael William John 
Published: February 2010

Abstract
A group of 5-day-old mice were injected intraperitoneally with (3-amino-1-hydroxypropylidine)-1,1-bisphosphonate (APD). Morphologic changes were observed in vitally stained osteoclasts on parietal bones 3 days later, and these were judged to be degenerative. At this time significantly increased numbers of nuclei per osteoclast and total numbers of osteoclast nuclei were observed. However, at 4 days after the injection of APD, the total numbers of osteoclasts were significantly reduced relative to controls. When parietal bones were maintained in culture, APD reduced osteoclast numbers and inhibited cell-mediated 45Ca2+ release. Exposure of bones to parathyroid hormone increased the number of osteoclasts counted 1 day later. This effect was not blocked by APD. Calcitonin prevented the reduction in osteoclast numbers due to APD in vitro. We conclude that APD has a direct effect on resorbing mouse osteoclasts
Estrogen inhibits release of tumor necrosis factor from peripheral blood mononuclear cells in postmenopausal women
Authors: Ralston Stuart H. , Russell R. Graham G. , Gowen Maxine 
Published: February 2010

Abstract
Cytokines, such as interleukin-1 (IL-1) and tumor necrosis factors (TNF), produced by cells of the monocyte-macrophage lineage in the local bone microenvironment, are potentially important local regulators of bone turnover. To investigate whether the protective effects of estrogen against postmenopausal bone loss may be mediated by inhibition of cytokine release, we studied the effects of 17β-estradiol, dihydrotestosterone, and hydrocortisone on TNF release from human peripheral blood mononuclear cells (PBMC) in vitro. In unstimulated cells derived from eight postmenopausal women, seven of whom had osteoporotic vertebral fractures, 17β-estradiol inhibited TNF release in a dose-dependent manner between 10−6 and 10−12 M but had no consistent effect on cells derived from men or premenopausal women. Dihydrotestosterone in concentrations of up to 10−6 M had no effect on TNF release in any patient group, whereas hydrocortisone at 10−6 M was a potent inhibitor of TNF release in all groups.
Since TNF is a potent stimulator of bone resorption, the inhibitory effect of estrogen on TNF release may be part of the mechanism by which it exerts a protective effect on the skeleton in postmenopausal women. These observations may also be relevant in other inflammatory diseases of connective tissue, such as rheumatoid arthritis, in which disease activity may fluctuate as estrogen levels change — during the menstrual cycle, in pregnancy, and after the menopause.
Frequency distributions of tetracycline-based measurements: Implications for the interpretation of bone formation indices in the absence of double-labeled surfaces
Authors: Foldes Joseph , Shih Mei-Shu , Parfitt A. Michael 
Published: February 2010

Abstract
The frequency distributions of mineral apposition rate (MAR) and mineralizing surface (MS), measured separately on the intracortical, endocortical, and cancellous surfaces in 46 normal subjects and 79 patients with postmenopausal osteoporosis, indicated that MAR has a finite lower limit of 0.3 μ/day (uncorrected for section obliquity) but that MS has no finite lower limit. We conclude that in the absence of labels MAR, and indices derived from it, must be treated as missing values, but that MS and indices with MS in the numerator should be allowed to take values of zero. To avoid infinite values for indices with MS in the denominator, we propose that osteoid mineralization rate (the reciprocal of mineralization lag time) and osteoblast vigor (the reciprocal of formation period) be used instead. For surfaces with genuine single labels (SL) but no double labels, we propose that MS is calculated as SL/2 and that for MAR either the lower limit of 0.3 or the mean measured value from other surfaces be used for calculating derived indices.
Calcium absorptive consistency
Authors: Heaney Robert P. , Weaver Connie M. , Lee Fitzsimmons Mary , Recker Robert R. 
Published: February 2010

Abstract
Calcium absorption efficiency was measured two or three times each in 74 premenopausal and 142 postmenopausal women under conditions predicted to alter absorptive performance. A woman's absorptive consistency was evaluated across differing loads, differing intervals, and substances of differing intrinsic absorbability. In all these circumstances there was a statistically significant correlation between a woman's absorption under differing test situations accounting for up to 60% of the variance typically found in cross-sectional studies. For example, when the same substance but at differing load levels was tested three times over an 8 week period, various coefficients of correlation ranged from + 0.773 to + 0.849 (P &lt; 0.001). Even over intervals as long as 5 years correlation of absorption fraction within individuals remained significant (r = +0.487, P &lt; 0.001).
Effects of progesterone on postovariectomy bone loss in aged rats
Authors: Barengolts E.I. , Gajardo H.F. , Rosol T.J. , D'Anza J.J. , Pena M. , Botsis J. , Kukreja S.C. 
Published: February 2010

Abstract
The effects of progesterone on oophorectomy-induced bone loss in aged rats were evaluated. Female rats aged 12 months were divided into three groups: (1) sham-operated controls (SHAM); (2) oophorectomized (OVX); (3) OVX rats treated with progesterone (OVX + PROG). After 20 weeks the dry weight, bone ash, and calcium content of femur, tibia, and fourth lumbar vertebra were significantly lower in OVX than in sham rats. These reductions did not occur in OVX rats treated with PROG. There was no difference in the bone composition between the control and progesterone-treated rats. Vertebral bone histomorphometry showed increased bone resorption as well as increased bone formation parameters in OVX rats. Progesterone treatment inhibited the increased resorption indices, but the bone formation remained elevated. The results indicate that progesterone therapy prevents the postovariectomy bone loss in aged rats. The protective effect of progesterone is mediated by inhibition of bone resorption while maintaining the increased bone formation. These findings suggest that progesterone alone may be a valuable agent for management of postmenopausal osteoporosis.
Effects of androgens on parathyroid hormone and interleukin-1-stimulated prostaglandin production in cultured neonatal mouse calvariae
Authors: Dr. Pilbeam Carol C. , Raisz Lawrence G. 
Published: February 2010

Abstract
In this study we show direct inhibitory effects on prostaglandin E2 (PGE2) production by the androgens, testosterone (T) and dihydrotestosterone (DHT), in cultured neonatal mouse calvariae. After 24 h of preculture with or without androgens, bones were treated with bovine (1–34)-parathyroid hormone (PTH) or recombinant human interleukin-1α (IL-1). During preculture androgens decreased PGE2 release only in those experiments in which control PGE2 was high. PTH increased medium PGE2 9-fold at 24 h, and 10−11 M T inhibited this increase by 50%. Treatment with IL-1 for 24 h increased medium PGE2 19- to 22-fold, and 10−10 M T and DHT inhibited this increase by 60 and 70%, respectively. T did not significantly affect the PTH-stimulated release of previously incorporated 45Ca or alter the PTH inhibition of incorporation of [3H]proline into collagenase-digestible protein. IL-1 stimulated 45Ca release by 60–80%, and small but significant reductions of 20–30% were seen with T and DHT. This study shows that T and DHT have direct effects on bone at physiologic concentrations, similar to our previous study in which PTH-stimulated PGE2 production in the same culture system was inhibited by physiologic concentrations of 17β-estradiol, and suggests that prostaglandins may mediate some of the effects of androgens in vivo.
Lysozyme synthesis in osteoclasts
Authors: Hilliard Thomas J. , Meadows Gary , Dr. Kahn Arnold J. 
Published: February 2010

Abstract
Osteoclasts may or may not be directly related to monocytes and macrophages, but it is well established that these cell types share a number of features in common.(1) In the present study we sought to extend this comparison by assessing lysozyme synthesis in osteoclasts, an enzyme known to be produced and secreted in large amounts by monocytes and macrophages.(2,3) Our data show that freshly isolated chicken osteoclasts and osteoclasts in situ contain an abundant amount of lysozyme and correspondingly high steady-state levels of the enzyme's messenger RNA. Marrow macrophages, at various stages of in vitro maturation, also possess lysozyme mRNA but in amounts approximately two to four times lower than osteoclasts. These observations reaffirm the monocyte-macrophage nature of the osteoclast but raise questions about the function of the lysozyme in this cell. At present, the role of the lysozyme in osteoclast activity remains unexplained.
Improved vertebral fracture threshold in postmenopausal osteoporosis by radiogrametric measurements: Its usefulness in selection for preventive therapy
Authors: Dr. Meema H. Erik 
Published: February 2010

Abstract
Measurements of the combined cortical thickness at the midshafts of the second metacarpal and the proximal radius, as well as their sums, were made from fine-grained radiographs in 107 normal premenopausal and 227 postmenopausal women and in 57 women with at least two spontaneous vertebral compressions. The −2 SD level of the premenopausal women was found to be an excellent vertebral fracture threshold for the radius measuring site and for the sums of metacarpal and radial measurements. Only 2 of 57 (4%) and 3 of 57 (5%), respectively, of values in the vertebral compression group fell at or above this level. At −3 SD a “secondary fracture threshold” was found for the sums in that only 7 of 57 (12%) of values in women with vertebral compressions were above this limit, but −3 SD was less satisfactory for the radius.
We conclude that this method discriminates as well between nonfracture and fracture cases as other radiologic methods for measurement of bone mass or density. Because it is less costly it seems better suited for mass screening in selecting postmenopausal women for preventive therapy than the less widely available high-technology methods.
Calcitonin secretion in idiopathic renal stone formers
Authors: Dr. Fuss Michel , Pepersack Thierry , Corvilain Jacques , Bergmann Pierre , Simon Jacques , Body Jean-Jacques 
Published: February 2010

Abstract
Several studies demonstrated a reduction in bone mineral content (BMC) in idiopathic renal stone formers (RSF). We found this reduction in association with a chronic low-calcium diet. Low calcium intake could theoretically result in calcitonin deficiency, responsible for increased bone resorption. This hypothesis was tested in 22 male RSF eating a low-calcium diet (350 ± 72 SD mg/day) for 2 years or more, who showed a significant reduction in their BMC. When compared to 15 normal male subjects eating a free diet, RSF showed increases in serum alkaline phosphatase activity and fasting urinary excretion of hydroxyproline and calcium, suggesting increased bone turnover. Plasma calcitonin levels were measured by radioimmunoassay following an extraction-concentration technique (exCT). Basal plasma exCT levels were higher (P &lt; 0.005) in RSF (4.1 * 0.8 SEM pg/ml) than in normal subjects (2.8 ± 0.4). Following a 5 minute infusion of 2 mg elemental calcium per kg, levels of plasma exCT tended to increase more, although not significantly, in RSF (51.3 ± 9.4 pg/ml) than in normal subjects (36.6 ± 9.7). The CT secretory response, taking into account changes in serum calcium concentration (AexCT/ACa), was higher (P &lt; 0.05) in RSF (50.0 ± 10.0) than in normal subjects (25.6 ± 6.6). Our study thus demonstrates that RSF chronically fed a low-calcium diet have increased basal plasma CT levels and increased CT cells responsiveness. CT deficiency cannot therefore be considered a cause for the low BMC associated with a chronic low-calcium diet in RSF.
In vivo osteogenic activity of isolated human bone cells
Authors: Yamamoto Takehisa , Ecarot Brigitte , Glorieux Francis H. 
Published: February 2010

Abstract
Human bone cells were obtained as the outgrowth from cancellous bone fragments pretreated with collage-nase and DNase. The osteogenic potential of cells in primary culture was assessed upon intramuscular transplantation into young mice pretreated with cortisone. Transplants were recovered after 2 weeks and examined by light microscopy. Of 34 transplants, 6 showed evidence of osteogenesis and 12 the production of unmineralized matrix. Only cells were observed in the other transplants. In an attempt to find a biochemical marker for osteogenic cells we have assayed medium osteocalcin and alkaline phosphatase activity levels in cultures before transplantation. No correlation was found between the level of expression of the two osteoblast markers and the osteogenic potential of the cells.
Effects of interleukin-6 on cellular function in UMR-106–01 osteoblastlike cells
Authors: Fang Meika A. , Hahn Theodore J. 
Published: February 2010

Abstract
High levels of interleukin-6 (IL-6) have been detected in synovial fluid from patients with inflammatory arthropathies associated with local bone resorption, suggesting a role for IL-6 as a local regulator of bone resorption and remodeling. In the present study we examined the effects of IL-6 on [3H]thymidine ([3H]TdR) incorporation, collagen synthesis, and alkaline phosphatase activity in UMR-106–01 rat osteoblastic osteosarcoma cells. IL-6 stimulated a dose-dependent increase in [3H]TdR incorporation that was maximal at 1000 U/ml (+147% of basal, p &lt; 0.005) in osteoblastlike cells that were in a logarithmic phase of growth. The increase in [3H]TdR incorporation was maximal between 12 and 24 h and was neutralized by pretreatment with the polyclonal rabbit antibody to IL-6. IL-6 also increased cell number and the secretion of prostaglandin E2 in UMR-106–01 cells in logarithmic growth phase. The stimulation of [3H]TdR incorporation and release of PGE2 into the culture medium by IL-6 was inhibited by indomethacin. A 24 h exposure of the osteoblastlike cells to 1000 U/ml of IL-6 reduced [3H]proline incorporation into collagenase-digestible (CDP) protein to 73% of control values (p &lt; 0.01). Noncollagen protein (NCP) synthesis was inhibited to 80% of control values (p &lt; 0.01) by 1000 U/ml of IL-6. The inhibitory effect was relatively greater on CDP than on NCP and consequently resulted in a decrease in the percentage of collagen synthesis. Alkaline phosphatase activity was not altered in these cells after a 24 h exposure to 1–1000 U/ml of IL-6. These results indicate that IL-6 has a direct effect on osteoblastlike cells, stimulating DNA synthesis via a prostaglandin-dependent mechanism and suppressing collagen and noncollagen protein synthesis.
Effects of transforming growth factor β1 on the regulation of osteoclastic development and function
Authors: Hattersley Gary , Chambers Timothy J. 
Published: February 2010

Abstract
Transforming growth factor (TGF) β1 is a multifunctional cytokine with powerful effects on osteoblastic cells. Its role in the regulation of osteoclast generation and function, however, is unclear. It has been reported both to stimulate and to inhibit resorption in organ culture and to inhibit multinuclear cell formation in bone marrow cultures. We tested the effects of TGF-β1 on bone resorption by osteoclasts isolated from neonatal rat long bones. We found potent stimulation of osteoclastic bone resorption, mediated by osteoblastic cells, with an EC50 of 10 pg/ml, considerably lower than that of well-documented osteotropic hormones. Stimulation was not mediated by Swiss mouse 3T3 cells, a nonosteoblastic cell line. TGF-β1 strongly inhibited the generation of calcitonin receptor (CTR)-positive cells in mouse bone marrow cultures, but as for isolated osteoclasts, bone resorption per CTR-positive cell was increased. The inhibition of CTR-positive cell formation was associated with suppression of maturation of other bone marrow derivatives and may be related more to the known ability of TGF-β1 to suppress the proliferation of primitive hematopoietic cells than to a specific role of TGF-β1 in osteoclast generation.