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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of parathyroid hormone and calcium ionophore A23187 effects on bone resorption and nucleic acid synthesis in cultured fetal rat bone (1982)
    Springer
    Calcified tissue international 34 (1982), S. 495-500 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ionophore A23187 ; Parathyroid hormone ; 45Ca release ; DNA concentration ; Nucleic acid synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary It has recently been demonstrated that calcium ionophore A23187 mimics certain of the effects of parathyroid hormone (PTH) on bone in vitro, including stimulation of45Ca release and cAMP formation. To further examine the relative effects of these two agents on bone cell metabolism, we compared the effects of synthetic PTH 1–34 (50 ng/ml) and calcium ionophore A23187 (0.5µg/ml) on45Ca release, DNA concentration, and nucleic acid synthesis in fetal rat forelimb rudiments cultured for periods up to 120 h. Both agents stimulated45Ca release; however, the effects of PTH were apparent after a shorter period of exposure. Bone DNA concentration (expressed asµg DNA/mg bone) was not affected by PTH but was significantly increased relative to control values by exposure to A23187 for 8–120 h of incubation. PTH increased the incorporation of3H-thymidine into DNA at 30 and 48 h, and increased the incorporation of14C-uridine into RNA at 48 h, time points which corresponded to a period of accelerated PTH stimulation of45Ca release. In contrast,3H-thymidine and14C-uridine incorporation were both uniformly suppressed by A23187 at all time points examined. Thus the increased DNA concentration observed in A23187-treated rudiments appeared to be the result of a decreased rate of bone maturation and mineralization. The markedly different patterns of nucleic acid synthesis in response to PTH and A23187 suggest that these agents differ significantly in their mechanisms of action on bone cell metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411291
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of lithium on parathyroid hormone-induced calcium release from bone rudiments (1979)
    Springer
    Calcified tissue international 27 (1979), S. 127-128 
    Details
    ISSN: 1432-0827
    Keywords: Lithium ; Parathyroid hormone ; Bone rudiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Lithium treatment of humans and animals has been associated with adverse effects on bone and mineral metabolism. In order to determine whether lithium was altering the skeletal response to parathyroid hormone, we incubated bone rudiments for 5 days in the presence or absence of the drugs. Lithium had no effect on either parathyroid hormone-induced cyclic AMP generation or45Ca release from the bone rudiments. The data are consistent with the hypothesis that the skeletal effects of lithium are not mediated via inhibition of the parathyroid hormone-adenyl cyclase-cyclic AMP system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441174
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of subacute effects of oxazacort and prednisone on mineral metabolism in man (1980)
    Springer
    Calcified tissue international 31 (1980), S. 109-115 
    Details
    ISSN: 1432-0827
    Keywords: Corticosteroids (glucocorticoids) ; Bone loss (osteopenia) ; Calcium absorption ; Calcium and hydroxyproline excretion ; Prednisone ; Oxazacort (Azacortinol)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Prolonged therapeutic administration of prednisone or other corticosteroids frequently produces severe osteopenia with an increased incidence of bone fractures. Recent efforts to decrease the severity of corticosteroid-induced osteopenia have included the development of corticosteroid analogues designed to possess diminished bone-wasting effects relative to their anti-inflammatory activity. We compared the effects of an oxazoline derivative of prednisolone, oxazacort (azacortinol), with those of prednisone on mineral metabolism in man. After a 12-day equilibration period on a 600 mg/day calcium diet, normal volunteers were studied for 15 days during treatment with either prednisone (20 mg/day, 12 subjects) or oxazacort (25 mg/day, 10 subjects). There was no difference between the two groups with regard to the effects of each corticosteroid on serum ionized calcium, phosphate, alkaline phosphatase, immunoreactive parathyroid hormone (iPTH), and 25-hydroxyvitamin D (25OHD) concentrations. Both corticosteroids suppressed intestinal47Ca absorption to a similar degree after 15 days of treatment (prednisone: −28.5±7.5, oxazacort: −30.2±4.4% of initial values). Although both corticosteroids increased 24-h urinary calcium excretion significantly above pretreatment values, this effect was less marked in the oxazacort-treated subjects. The mean cumulative 15-day increase in urinary calcium excretion in the prednisone-treated group (+326 ± 54 mg/g creatinine/24 h) was more than twice as great as that in the oxazacort-treated group (+146 ± 48 mg/g creatinine/24 h), a difference significant atP〈0.001. It is concluded that the increase in urinary calcium excretion, and presumably the negative calcium balance, produced by a 2-week administration of oxazacort is significantly less pronounced than that produced by an equivalent dose of prednisone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407171
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of a weighted vest on perceived health status and bone density in older persons (1993)
    Springer
    Quality of life research 2 (1993), S. 141-152 
    Details
    ISSN: 1573-2649
    Keywords: Bone density ; controlled trial ; health perception ; pain ; quality of life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To assess the effect of an exercise intervention using a weighted vest on perceived health status and bone density in older persons, we enrolled 36 seniors in a randomized controlled trial. The vest-use group met weekly for 1 h for a low level exercise class. They wore a weighted vest during the class and as tolerated at home. The discussion controls met for 1 h weekly. At baseline and follow-up (20 weeks), subjects completed a questionnaire that incuded the 20 item MOS Short-Form Health Survey, Multidimensional Health Locus of Control Scale, and Philadelphia Geriatric Center Morale Scale, and bone density was measured by dual energy X-ray absorptiometry. Subjects also completed daily activity diaries. Subjects in the vest group reported a statistically significant dicrease in bodily pain, improved physical functioning, and increased internal health locus of control. Bone density increased by 1% in the vest group and decreased by 0.6% in the controls (p=0.12). We conclude that our exercise intervention had a positive effect on some measures of perceived health in older persons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00435733
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    Paper (German National Licenses)
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