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  • 1
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In the development of a polyurethane vascular catheter with anti-infective properties, it became desirable to develop a measure of tissue inflammation. This was investigated in a rabbit model by implanting uncoated catheters and catheters coated with heparin (HEP), chlorhexidine (CH), or CH/HEP in the subcutaneous space with or without 104 Staphylococcus aureus. At intervals of 2, 4 and 7 days after implantation, animals were sacrificed; tissue blocks containing catheters were removed and preserved with formaldehyde; and sections were stained with hematoxylin and eosin. Using a histologic index, 240 sections (10 for each experimental condition) were evaluated by two investigators blinded to experimental conditions. Uncoated catheters or catheters coated with CH alone had a lower histologic index (less inflammation) than catheters coated with HEP alone or CH/HEP (P 〈.05). When catheters were inoculated with S. aureus, those coated with CH, with or without HEP, had a lower histologic index than uncoated catheters (P 〈.05). Next, 30 volunteers had a control catheter inserted in a vein in one forearm and a catheter coated with either CH alone or CH/HEP in a vein in the other forearm. After 96 h of observation there was a greater risk of phlebitis associated with CH/HEP catheters than control catheters (P 〈.05), and no difference in the risk of phlebitis between CH catheters and control catheters (P = 0.43). Thus, the amount of inflammation around the catheter in the subcutaneous space of rabbit correlated with the risk of peripheral vein phlebitis. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We previously have shown that vascular catheters made of silicone elastomer carry a greater risk of subcutaneous infection with Staphylococcus aureus than do polyurethane (PU), polyvinylchloride (PVC), or Teflon® catheters. We further have shown that there is greater inflammation surrounding silicone catheters than there is surrounding catheters made of the other materials, suggesting that silicone produces a greater chemotactic gradient than do the other materials. This study used a functional complement opsonization assay and radioimmunoassays to compare the relative abilities of silicone, polyurethane, and polyvinylchloride to activate complement. Serum incubated in silicone catheters for 24 h had less than 30% of the opsonizing ability of fresh serum while ≥78% of the opsonizing ability remained with serum incubated in PU or PVC catheters. Measurement of C3a des Arg, C4a des Arg, C5a des Arg, and SC5b-9 demonstrated that the loss of opsonizing ability was due to 10-fold greater alternate pathway complement activation by silicone than by PU or PVC. This finding suggests that excessive complement activation by silicone may explain the greater inflammation seen around silicone catheters in vivo and also might play a role in silicone's creating a greater risk of infection. © 1996 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: There is currently very little information to suggest that polymer materials used to make vascular catheters differ in their risk of infection. A rabbit model of subcutaneous Staphylococcus aureus infection was used to determine the relative risk of infection associated with silicone, polyurethane, polyvinylchloride, and Teflon® catheters. Seven days after catheter implantation and inoculation with S. aureus, catheters were observed for gross purulence and quantitatively cultured. Silicone catheters were found to have a greater risk of grossly apparent infection (purulence) and a greater number of organisms removed from catheters by quantitative culture than the other three catheter materials (P 〈 .01). The risk of infection associated with silicone catheters decreased (P 〈 .05) if the S. aureus inoculation was delayed for 2 days or if the histology of the inflammatory response around the four catheter materials was evaluated at either 2 or 7 days after catheter insertion with or without S. aureus inoculation. Silicone catheters had greater associated inflammation (P 〈 .05) with or without S. aureus inoculation. These results suggest that silicone catheter materials may have unique properties that increase the risk of infection after implantation. Further studies should be done to understand the mechanism(s) of these observations. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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