In vitro and in vivo effects of parathyroid hormone and human cancer ascites fluid bone resorbing protein
Date
1984
DOI
Authors
Alamoudi, Najlaa Mohamed
Version
OA Version
Citation
Abstract
We have compared the effects of human 1-34 amino terminal fragment of parathyroid hormone (PTH) and a bone resorbing protein (BRP) isolated from human cancer ascites fluid on calcium mobilization, matrix resorption and collagen synthesis. PTH and BRP, as well as lymphocyte derived osteoclast activating factor (OAF), stimulated calcium mobilization from embryonic chick calvaria after 72 hours in culture. PTH and OAF also stimulated matrix resorption as measured by release of 3H-proline and hydroxyproline. BRP, in contrast, had no effect on matrix resorption. Both PTH and BRP stimulated synthesis of bone matrix (OAF was not tested). Indomethacin, an inhibitor of prostaglandin synthesis, had no effect on PTH or BRP stimulated calcium mobilization when added concomitantly with these proteins. However, preincubation of the bones with indomethacin completely inhibited PTH mediated and partially inhibited BRP mediated calcium mobilization. These results suggest that BRP acts to uncouple calcium and matrix resorption and probably acts through a prostaglandin dependent mechanism. PTH also appears to Stimulate calcium mobilization through a prostaglandin dependent mechanism.
We have also examined the effects of BRP and PTH in vivo. PTH, but not BRP, produced acute hypercalcemia in growing chicks. Chronic effects on bone resorption was monitored by labeling bones in growing chicks with tritiated tetracycline and measuring residual radioactivity after chronic administration of either PTH or BHP. Administration of BRP or PTH to chicks twice daily for one week caused significant hypercalcemia when compared to saline injected controls. BRP increased bone resorption while PTH decreased bone resorption. Bone calcium, and phosphorus content, expressed on a weight basis, were not different from controls. However, mice treated with both PTH and BRP were hypocalcemic and bone resorption was inhibited in those animals treated with BRP. Bone calcium and phosphorus content was also increased. Molar ca/p ratios were normal in both. The histological sections from in vitro and in vivo studies showed no difference between groups, although by visual examination of chick bone treated in vivo indicated increased marrow space and thinning of trabeculae.
Description
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.
Black and white photographs included.
Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1984 (Oral Biology)
Bibliography : leaves 172-198.
Black and white photographs included.
Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1984 (Oral Biology)
Bibliography : leaves 172-198.
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.