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  • 1
    Electronic Resource
    Electronic Resource
    Enzyme-bound early product of purified poly(ADP-ribose) polymerase
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 78 (1977), S. 1281-1288 
    Details
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0006-291X(77)91431-0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Highly effective DNA in stimulating poly(ADP-ribose) polymerase reaction
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 88 (1979), S. 305-311 
    Details
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0006-291X(79)91730-3
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gene expression and protein activity in bone-bonding and non-bonding PEO/PBT copolymers (1994)
    Springer
    Journal of materials science 5 (1994), S. 582-586 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The formation of a reactive carbonate-apatite surface is generally considered a critical step for bone-bonding. However, the contribution of proteins in the establishment of bone-bonding is debatable. In the current study, osteocalcin, osteopontin and β-actin mRNA expression and alkaline phosphatase activity were therefore determined in different porous substrates loaded with marrow after subcutaneous implantation for 2 weeks. Two polyethylene oxide (PEO)/polybutylene terephthalate (PBT) copolymers were used for this purpose. First, an 80/20 PEO/PBT which generates a carbonate-apatite surface and bonds to bone rapidly. Second, a 30/70 PEO/PBT which previously did not show bone-bonding up to 1 year postoperative. Bone had formed within the pores and occasionally at the calcified surface of the 80/20 materials. In contrast, 30/70 materials did not calcify and bone was not found in the pores. Despite these morphological differences, gene expression and protein activity was similar in 80/20 and 30/70 PEO/PBT materials. These results suggested that bone-bonding of PEO/PBT copolymers is more likely to depend on the formation of a carbonate-apatite surface than on a specific influence of a bioactive material on osteogenic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120334
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    BMP-Induced osteogenesis on the surface of hydroxyapatite with geometrically feasible and nonfeasible structures: Topology of osteogenesis (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 190-199 
    Details
    ISSN: 0021-9304
    Keywords: BMP ; geometry ; carriers ; hydroxyapatite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bone morphogenetic protein (BMP) is known to require a suitable carrier to induce ectopic bone formation in vivo. Hydroxyapatite ceramics have been reported to be effective in some forms but ineffective in others as a carrier of BMP-induced bone formation. In this study we compare three geometrically different forms of hydroxyapatite to examine their functions as carriers of BMP-induced bone formation. A fraction containing all the active BMPs (BMP cocktail) was partially purified from a 4M guanidine extract from bovine bone by a three-step chromatographic procedure. The BMP cocktail was combined with each of three forms of hydroxyapatite - solid particles (SPHAP), porous particles (PPHAP), and coral-replicated porous tablets (coral-HAP) - and implanted subcutaneously into rats. Both the PPHAP and coral-HAP systems induced osteogenesis 2 weeks after implantation, as evidenced by morphological and biochemical observations. Details of the osteogenetic process were followed by double-fluorescence labeling in the coral-HAP system to confirm bone formation on the surface of hydroxyapatite. However, there was no evidence of osteogenesis or chondrogenesis in the SPHAP system. The results indicate that the geometry of the interconnected porous structure in PPHAP and coral-HAP create spaces for vasculature that lead to osteogenesis while the smooth structure and close contact of particles in SPHAP inhibit vascular formation and proliferation of mesenchymal cells, preventing bone and cartilage formation. It was concluded that the geometrical structure in hydroxyapatite ceramics that induces vasculature is crucial as a carrier for BMP-induced bone formation. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 190-199, 1998.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    In vitro bone formation by rat marrow cell culture (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 333-340 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fresh marrow cells were obtained from the femora Fischer rats and cultured in a medium containing 15% fetal calf serum (FCS) to leach confluent. After trypsinization, cells were subcultured at a cell density of 100 × 103/35 mm well in the presence of FCS, 10 mM β-glycerophosphate, 82 μg/mL ascorbic acid phosphate, and 10-8M dexamethasone (Dex). Osteoblastic cells and microscopic mineralized nodules began to appear at about 1 week after the subculture, and at 2 weeks many macroscopic nodules that showed high alkaline phosphatase activity (ALP) and appearance of bone Gla protein (BGP) mRNA were evident. As demonstrated by in situ hybridization, the mRNA was manifested by cuboid-shaped cells (osteoblastic cells). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) showed the mineralization of fine crystals of hydroxyapatite comparable to natural rat bone mineral. In contrast to these findings, subculture done under the same conditions except for the lack of Dex did not show mineralized nodules, nor did they show the osteoblastic phenotype expression. These analyses indicate that Dex-induced mineralization using rat bone marrow cell culture is an in vitro counterpart of bone formed in vivo. Such a culture is useful for investigating materials/osteogenic cells interactions. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Analysis of gene expression in osteogenic cultured marrow/hydroxyapatite construct implanted at ectopic sites: A comparison with the osteogenic ability of cancellous bone (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 568-573 
    Details
    ISSN: 0021-9304
    Keywords: hydroxyapatite ; marrow cell ; dexamethasone ; osteocalcin ; alkaline phosphatase ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We investigated the in vivo osteogenic ability of cultured marrow cells subcultured in porous hydroxyapatite. This osteogenic ability was compared with that of cancellous bone grafts. Fresh marrow cells were obtained from young adult rat femora and cultured in a standard medium for 10 days, then trypsinized and used to make constructs of porous hydroxyapatite (HA) and cultured marrow cells. An additional 2-week culture (subculture) was performed for the construct in standard medium with and without the addition of dexamethasone (Dex). The 2-week subcultured constructs then were implanted into subcutaneous sites of syngeneic rats. These implants and the rat cancellous bone were harvested and prepared for gene expression analysis of alkaline phosphatase (ALP) and osteocalcin (OC) as well as for histological analysis. ALP and OC mRNAs could be detected in Dex-treated subcultured constructs 1 week after implantation, with an increase at 2 weeks, comparable to the observation in cancellous bone. Histological analysis showed active bone formation even 1 week postimplantation. In contrast, the subcultured constructs without the addition of Dex did not show bone formation, and only small levels of ALP and OC mRNAs were found. These results indicate that the bone tissue formed by grafting the Dex-treated construct of cultured marrow cells and hydroxyapatite possesses a high osteoblastic activity comparable to that of viable cancellous bone. Thus the prefabricated osteogenic subcultured marrow/HA construct may be applicable in bone reconstructive surgery. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 568-573, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Osteogenic differentiation of cultured marrow stromal stem cells on the surface of bioactive glass ceramics (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 341-348 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To investigate the significance of apatite-wollastonite-containing glass ceramic (AW ceramic) surfaces and the biological apatite layer formed on these surfaces, rat marrow cell culture, which shows osteogenic differentiation, was carried out on four different culture substrata (control culture dish, two AW ceramics, each having a different surface roughness, and a ceramic on which an apatite layer was formed. A culture period of 2 weeks in the presence of β-glycerophosphate, ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain on all substrata. The stain on the apatite-formed AW ceramic was the most intense, the enzyme activity being about twice that of the control culture dish, which had the lowest stain and activity of the four substrata. Northern blot analysis of bone Gla protein (BGP) showed the same tendency, that is, the amount of BGP mRNA from cultured cells on the apatite-formed AW ceramics was the highest and the mRNA on the control dish was the lowest. These data indicate that the glass ceramic surface promotes osteoblastic differentiation and that the promotion can be further enhanced by the formation of a biological apatite layer on the ceramic surface. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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