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  • Chemistry  (7)
  • 1990-1994  (7)
  • 1
    Electronic Resource
    Electronic Resource
    An Alternative Synthesis of [Pd2Cl2(μ-dmpm)2] (1992)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 334 (1992), S. 34-36 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new, high yield synthesis of [Pd2Cl2(m̈-dmpm)2] (dmpm = bis(dimethylphosphino)methane), which avoids the use of the ill-defined, polymeric substance [PdCl(CO)]n as a starting material, is described. The procedure involves ligand metathesis of [Pd2Cl2(m̈-dppm)2] (dppm = bis(diphenylphosphino) methane) with dmpm using a solvent in which both [Pd2Cl2(m̈-dppm)2] and [Pd2Cl2(m̈-dmpm)2] are only sparingly soluble. Yields of 〉 98% are routinely obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19923340106
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  • 2
    Electronic Resource
    Electronic Resource
    Behavior of primary bone cells on characterized polystyrene surfaces (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 851-859 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Primary bone cells, isolated from the periosteally stripped calvariae of neonate rats, were cultured on 60Co γ-irradiation-sterilized bacteriologic-grade polystyrene that had been either surface treated with concentrated sulfuric acid or received further γ-irradiation treatments facilitated cell colonization of the polystyrene compared to those surfaces not treated in the laboratory. x-Ray photoelectron spectroscopy (XPS) showed that the two treatments introduced different chemical groups onto the polymer surface and that cell adhesion was related to γ-irradiation in a dose-dependent manner. These results show that simple biologic assays, such as cell colonization, are not able to distinguish between differences in surface chemistry demonstrated by such a routinely employed surface analysis technique. Thus, there is a need to develop more sensitive biologic assays that provide functional information of a precision that can be correlated with subtle changes in substratum surface chemistry. Further, we argue that because cells isolated by tissue digestion using proteolytic enzymes respond more readily to changes in the surface chemistry of the substratum they colonize, compared to explanted cells; biologic assays designed for biomaterials testing must take into account changes effected in cell adhesion behavior by isolation procedures. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270703
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  • 3
    Electronic Resource
    Electronic Resource
    Osteoclastic resorption of calcium phosphates is potentiated in postosteogenic culture conditions (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 105-112 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cell-mediated resorption of densely sintered hydroxyapatite (HA1250), tricalcium phosphate (TCP), and 600° or 900°C calcined hydroxyapatite (HA600 and HA900, respectively), was investigated by using two culture systems. The first was an osteoclastic cell culture, and the second was a two-stage culture that was composed of a bonelike tissue formation on the substrata in the first stage and its subsequent resorption by osteoclasts in the second stage. Neither of the materials showed resorption or surface alterations in the osteoclastic cell culture, except for some limited phagocytotic activity on HA600 and HA900. In the two-stage culture, production of mineralized extracellular matrix was only observed on HA1250 and TCP, and its subsequent resorption by osteoclastlike cells was evident. Small and occasionally larger tartrate-resistant acid phosphatase positive cells produced 20-150 μm diameter resorption pits in both the mineralized extracellular matrix on HA1250 and TCP and TCP and the surfaces of HA600 and HA900. Resorption of the mineralized extracellular matrix on TCP also resulted in degradation of the underlying ceramic surface, mainly initiating from intergrain boundaries, whereas the surface of HA1250 remained unaltered. The results of this study clearly demonstrate that osteoclastic resorption of calcium phosphates is potentiated in postosteogenic culture conditions. A possible role for bone matrix constituents in cell-mediated resorption is hypothesized, whereas the occurrence of resorption seems to be mainly governed by the combined effects of material characteristics such as grain size and crystal structure. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280114
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  • 4
    Electronic Resource
    Electronic Resource
    Interfacial behavior of PEO/PBT copolymers (polyactive®) in a calvarial system: An in vitro study (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 269-277 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyactive®, a polyethylene oxide/ polybutylene terephthalate (PEO/PBT) copolymer, has been reported to display bone-bonding behavior. Although a detailed description of the in vivo bone/ Polyactive® interface is available, the underlying bone-bonding mechanism is still largelyunknown. In this in vitro study, a calvarial envelope method has been adopted to reproduce the in vivo bone-bonding phenomenon and subsequently to obtain information on the biological effect of varying PEO/PBT segment ratios. The following PEO/PBT ratios were examined: 70/30, 60/40, 55/45, 40/60, and 30/70. Light microscopy (LM) and scanning (SEM), transmission (TEM), and backscatter electron microscopy (BSE), as well as X-ray microanalysis (XRMA), were employed. Within the period of analysis (3 weeks), an intimate contact between mineralized deposition and the 70/30, 60/40, and, to a lesser extent, the 55/45 surface was observed. Calcified areas developed within the surface of these PEO/BPT proportions during the culture period. Needle-shaped crystals from the mineralized tissue compartment and from calcified areas within the materials surface were intermingled at the interface, providing a morphologic continuity. A cellular layer was interposed with the mineralization front and the noncalcified 40/60 and 30/70 substrates. Apparently, the percentage of PEO is important for calcification within the near surface of the polymer. This relation is such that the highter the PEO content in PEO/PBT ratios, the more rapid the calcification is considered. The occurrence of material calcification is considered to be largely responsible for the subsequent interfacial interactions. The calvarial envelope culture method allows not only reproduction of the in vivo bone/Polyactive® interface, but also a relatively rapid differentiation within the range of PEO/PBT ratios. It was therefore concluded that this in vitrosystem is suitable for further studies toward a better understanding of the bone/Polyactive® interfacial composition and the underlying mechanisms. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280218
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  • 5
    Electronic Resource
    Electronic Resource
    The bone-titanium interface in vitro (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 1289-1306 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Commercially pure 5-mm-diameter titanium (cpTi) discs received droplet inoculations of cells derived from rat bone marrow and were maintained in supplemented culture medium for 2-3 weeks. The cells and extracellular matrix (ECM) were processed for observation by light (LM), scanning (SEM), and transmission electron (TEM) microscopy. The latter was achieved by freeze-fracturing the solid metal from the resin-embedded tissue using a method which preserved the interface. Surface staining of whole discs revealed cells separated from the metal substratum by areas of ECM which stained positively using von Kossa's method to identify mineralization. At SEM, the ECM comprised dense interwoven collagen fiber networks which were partially obscured by globular masses (GMs). Individual GMs were associated with collagen fibers, especially at fiber intersections. EDAX line scan analysis confirmed the presence of Ca and P in these areas which were assumed to be spheritic foci of calcification since the Ca and P peaks diminished in areas which demonstrated only collagen fibers or the underlying cpTi. TEM examination confirmed the presence of globular mineralization and also revealed the presence of an interfacial zone between the metal substratum and the mineralized ECM elaborated by osteoblasts during the culture period. The interfacial zone comprised two layers, a bonding zone containing few collagen fragments and a ruthenium red positive layer containing more densely packed collagen fibers. We believe that this is the first report of both the formation of bonelike tissue on solid titanium substrata in vitro and demonstration of an interface which bears close morphological similarities to that known to develop in vivo.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820241003
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  • 6
    Electronic Resource
    Electronic Resource
    Guided bone tissue elaboration by osteogenic cells in vitro (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 429-431 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Primary rat bone marrow cells were cultured for 2 weeks in polystyrene dishes whose surfaces had been roughened using 600- or 320-grit silicon carbide paper. Eight samples were prepared of each of the three groups of dishes, to include a nontreated control suface. Following the culture period, the dishes were stained by von Kossa's method. The distribution of bone formed during the culture period was examined by light microscopy and the area of bone formed quantified. Results demonstrated that both the amount and spatial distribution of bone were influenced by the roughness of the underlying substratum. Differences between the smooth and roughened surfaces were statistically different at P 〈 .05. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270403
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of interfaces in ceramic composites by SIMS, AES and EPMA (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 23-31 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fracture surfaces and polished cross-sections of aligned SiC fibre-cordierite matrix composites have been studies using SIMS, AES and electron probe x-ray microanalysis (EPMA). It has been shown that, during fabrication, interface reactions resulting in penetration of the fibres by matrix cations take place. Titanium diffusion out from the fibres together with segregation of matrix elements to the interface is also observed. A correlation is found between interface composition and mechanical properties of the composites. The relative merits of SIMS, AES and EPMA in the determination of the nature of the fibre-matrix interface are discussed. SIMS using a microfocused Ga ion beam is shown to be a powerful new tool in the investigation of interfaces.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180105
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