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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 258-264 
    ISSN: 0021-9304
    Keywords: growth hormone ; biological integrity ; drug delivery system ; dynamic compaction ; biphasic calcium phosphate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The association of therapeutic agents with biomaterials has been achieved through various techniques, such as coating of the ceramic block surface or drug incorporation into ceramics. The dynamic compaction method recently was developed to consolidate drug-loaded calcium phosphate powder without a sintering step. In the present work, human recombinant growth hormone was loaded on biphasic calcium phosphate powder and consolidated by a specific process of cold sintering (dynamic compaction). Analyses of the biocompatibility of compacted pellets (mouse L929 fibroblastic cell culture) and the bioactivity of the drugs released by them (growth hormone bioassay) were performed. This report demonstrates the biocompatibility of the compacts prepared by dynamic compaction. L929 cell proliferation was maintained and the capacity to secrete fibronectin was conserved in the presence of compacted materials. Comparison of released growth hormone integrity, revealed by radioimmunoassay and eluted stain bioassay, has shown that the biological activity of growth hormone was totally preserved after dynamic compaction. However, 35% of loaded growth hormone was not released in our experimental conditions, probably because of the inaccessibility of growth hormone within the granulated compacts. Dynamic compaction shows good potential for the production of biomaterials capable of releasing therapeutic agents in situ. © 1997 John Wiley & Sons, Inc. J. Biomed Mater Res, 36, 258-264, 1997.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 79-85 
    ISSN: 0021-9304
    Keywords: growth hormone ; biphasic calcium phosphate ; monocyte ; lipopolysaccharides ; cell degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study investigated the effects of human growth hormone (hGH) on the monocyte/macrophage lineage, the first cell population involved in degradation of calcium phosphate ceramic after in vivo implantation. Monocytes isolated from human blood were cultured on biphasic calcium pellets (200 mg) for 8 days in the presence of lipopolysaccharides (LPS, 0.5 μg/mL), hGH (10 and 50 ng/mL), or an association of LPS with hGH (10 and 50 ng/mL). Unlike LPS, hGH significantly decreased (about 25%) the total number of lacunae formed by monocytes. However, hGH induced the formation of lacunae with a greater surface area (about a 90% increase) as compared to the control. Finally, intense upmodulation (about a 250% increase) of lacuna surface area was observed in the presence of both soluble factors, suggesting that hGH and LPS act synergistically. In view of the development of a drug delivery system for hGH bone release, this study shows that hGH not only stimulates bone cells implicated in the synthesis of the extracellular matrix but also those involved in the early degradation of calcium phosphate biomaterial. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 79-85, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: growth hormone ; biphasic calcium phosphate ; drug delivery system ; bone ingrowth ; ceramic resorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Calcium phosphate ceramics recently have been used for administering therapeutic agents in bone. The present work investigated the efficacy of macroporous biphasic calcium phosphate (MBCP) implants as a matrix for local delivery of human growth hormone (hGH). An initial study showed that the release of 5 μg of hGH loaded onto MBCP cylinders was rapid during the first 48 h and sustained for a total of 11 days. The biological integrity of hGH (88.2%) was checked using a specific bioassay (cellular proliferation of hGH-sensitive Nb2 cells) in comparison with a radioimmunoassay to calculate the proportion of bioactive hGH released. MBCP cylinders then were loaded with 1, 10, and 100 μg of hGH and implanted into rabbit femurs (n = 16) to determine hGH effects on bone ingrowth and ceramic resorption, as evaluated by scanning electron microscopy and image analysis. Results indicated that hGH increased bone ingrowth and ceramic resorption significantly in comparison with contralateral and control implants. Biochemical parameters monitored in rabbit plasma showed that hGH did not produce detectable systemic effects. Thus the use of MBCP appears to be effective for local delivery of hGH and for increasing bone ingrowth. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 560-566, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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