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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 139-144 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A rat model was used to investigate the effect of net surface charge on polymer biocompatibility and its potential to modify and stimulate the inflammatory response. Poly(ether)urethane was taken as the base material and the net charge altered by introducing sulphonate ionic groups to the polymer backbone. Three differently charged poly(ether)urethanes were made with 10, 20, and 30% sulphonate substitution, giving a range of negative charge, with unmodified poly(ether)urethane used as a control. The polymers were implanted intramuscularly into rats for 2 days, and for 1, 2, and 12 weeks. After explantation, the cellular infiltration in the tissue surrounding the implants was evaluated using immunohistochemistry to stain for specific cell types: macrophages, neutrophils, lymphocytes, and the cytokine TNFα. In situ hybridization was used to detect expression of mRNA encoding TNFα. Stained sections were analyzed and the cellular response quantified using image analysis. Initially macrophages and neutrophils were observed around all the materials, but neutrophils were absent in all samples at 12 weeks. The 2-day time point had significantly more macrophages than the later time points. By 2 weeks the 20%-charged polymer elicited significantly less neutrophil infiltration than the other three polymers. In all samples where macrophages were observed, cells staining positive for TNFα protein and message also were observed. No T or B lymphocytes were observed in the infiltrates around the materials at any time point. The results indicate that surface charge can influence the early phase acute inflammatory response to an implanted material. © 1996 John Wiley and Sons, Inc.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 819-828 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interaction between corrosion products of metallic implants and the surrounding tissue is important in determining the biocompatibility of the implant, in particular the interaction of corrosion products with inflammatory cclls such as neutrophils and macrophages. Such cells are capable of releasing enzymes and high-energy oxygen radicals which can damage the tissue. Clearly, any factors that influence cell movement to the implant site could influence the biocompatibility of the implant. The present study examined the influence that copper and nickel ions had on neutrophil locomotion. Both copper and nickel ions stimulated a proportion of the neutrophil population to take up a nonspherical morphology and to locomote. These metal ion stimulated cells have higher circularity values and move slower than neutrophils incubated with FM1.P. For both FMLP and nickel ion stimulated cells, there is a correlation between the speed of neutrophil locomotion and neutrophil circularity; as the neutrophil circularity value decreases, the speed of locomotion increases.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 542-549 
    ISSN: 0021-9304
    Keywords: hydrophilicity ; macrophages ; image analysis ; inflammation ; TNFα ; MCP-1 ; polyurethane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study investigates the effect of changing the hydrophilicity of polyurethane on the soft tissue inflammatory response after implantation into rats. A series of five polyurethanes were made from the macrodiols poly(ethylene oxide) (PEO), poly(tetramethylene oxide) (PTMO), poly(hexamethylene oxide) (PHMO), poly(octamethylene oxide) (POMO), and poly(decamethylene oxide) (PDMO). In the sequence the macrodiols become less polar and phase separation in the polymer increases, creating a range of hydrophilicity. These five polyurethanes were studied along with commercial Pellethane 2363-80A. The materials were implanted intramuscularly into rats for 7 days, 1 month, and 3 months. The inflammatory response was analyzed using a combination of immunohistochemistry, enzyme histochemistry, and image analysis to determine the specific cell types involved in the response and to quantify these cellular responses. The presence of three cytokines also was investigated. The cell types targeted were neutrophils, monocytes, macrophages, and T and B lymphocytes. The cytokines target were tumor necrosis factor α(TNFα), interleukin 6 (IL-6), and monocyte chemotactic protein 1 (MCP-1). All samples were positive for macrophages and activated macrophages, TNFα, and MCP-1, and negative for all other antibodies. The response was sustained throughout the implantation period with no significant difference among the samples except at the 7-day time point. The study demonstrated an absence of lymphocytes and neutrophils in a response that was sustained in terms of macrophages with the presence of TNFα and MCP-1 and the absence of IL-6. The position of subsets of macrophages with respect to increasing distance from the implants was demonstrated to be significant and consistent within this series of polyurethanes. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 542-549, 1997.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 37 (1997), S. 481-488 
    ISSN: 0021-9304
    Keywords: MCP-1 ; biomaterials ; flow cytometry ; macrophages ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macrophages were elicited by the subcutaneous implantation of ultra high molecular weight polyethylene (UHMWPE) for periods of 2, 7, and 14 days in rats. Exudates of varying volumes were produced that was comprised of granulocytes, monocytes, immature and mature macrophages, and T-lymphocytes. No B-lymphocytes were observed at any time periods. Cell types were identified by their granularity and positivity to the following antibodies: leucocyte common antigen (LCA, pan leucocyte); CD11b/c (macrophage/monocyte); CD5 (T-lymphocyte); CD45RA (B-lymphocyte); HIS48 (granulocyte); ED2 (mature macrophage); and MCP-1 (monocyte chemoattractant protein 1). Monocytes isolated from control rat blood demonstrated a size slightly larger than that of granulocytes but with less granularity. Their size and granularity were followed over increasing time periods. The macrophages elicited by UHMWPE showed a similar pattern, with the exception of an apparently highly granular subpopulation with volumes similar to that of granulocytes but significantly more granular. The granular macrophage subset had a very high degree of ED2 and MCP-1 positivity, and their proportion, compared with other macrophages, was greatest at 2 days. The high MCP-1 expression was accounted for by MCP-1 molecules bound to the surface of a small proportion of macrophages that were activated. It is postulated that this subpopulation was responsible for the synthesis of the MCP-1 and could indicate a mechanism by which monocytes are attracted to the site of an implanted material. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 37, 481-488, 1997.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 1545-1555 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was designed to evaluate the interfacial interactions between proteins and cells and a model surface which varied in its surface energy. The adsorption of proteins from single and binary solutions was studied using ellipsometry and the adhesion and spreading of L929 fibroblasts has been quantified using image analysis. The results demonstrated that after 24 h incubation, multilayer adsorbed fibrinogen appeared to produce a surface most conducive to cell adhesion and spreading on both the hydrophilic and hydrophobic regions of the material. Fibronectin on its own did not produce an optimal surface for cell spreading. Albumin produced a suitable surface for cell spreading on the hydrophilic part of the surface, but created a highly unsuitable surface on the hydrophobic region of the specimens. Competition between proteins for adsorption to the surface and changes in protein conformation was evident, particularly on the hydrophobic part of the material, and this was shown to influence cell adhesion and spreading. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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