Biomedical subjects

R G Flemming

Publications and source records attributed to R G Flemming.

3 recordsLinked to original sources

PubMed2000

Bacterial colonization of functionalized polyurethanes.

A protocol was developed for studying the growth of bacteria upon polyurethanes subsequent to the establishment of an adherent bacterial population. An inocula of approximately 10(5) cfu S. aureus were spread on functionalized polyurethanes which included Pellethane, sulfonated Pellethane, phosphonated Pellethane, quaternized amine polyurethanes, and a zwitterionic phosphonated polyurethane. After 24 h incubation, Pellethane, sulfonated Pellethane, and phosphonated Pellethane showed bacterial growth by at least a factor of 10. In contrast, the zwitterionic phosphonated polyurethane showed a factor of 10 decrease in bacteria after 24 h and the quaternized amine polyurethanes reduced the bacteria to only a few hundred after only 1 h. When treated with bovine serum albumin, Pellethane, sulfonated Pellethane, and phosphonated Pellethane again showed bacterial growth by as much as a factor of 10 over 24 h. The quaternized amine polyurethanes and the zwitterionic phosphonated polyurethane still exhibited bactericidal abilities even when coated with bovine serum albumin, with the zwitterionic material reducing bacteria by more than a factor of 10 over 24 h and the quaternized amine polyurethane reducing the bacteria to only a few hundred after only 1 h. A zone of inhibition study suggested that the bactericidal activity of the zwitterionic phosphonated polyurethane was due to the leaching of cadmium ions. A quaternized amine polyurethane which contained chloride instead of iodide as the counterion to the amine moiety was less bactericidal than the iodide-containing polymer when treated with albumin. Thus, bacteria were able to colonize Pellethane, phosphonated sulfonated Pellethane, and phosphonated Pellethane, but the iodide-containing quaternized amine polyurethane and the zwitterionic polyurethane prevented colonization.

Albumins↗

PubMed1999

Effects of synthetic micro- and nano-structured surfaces on cell behavior.

Topographical cues, independent of biochemistry, generated by the extracellular matrix may have significant effects upon cellular behavior. Studies have documented that substratum topography has direct effects on the ability of cells to orient themselves, migrate, and produce organized cytoskeletal arrangements. Basement membranes are composed of extracellular matrix proteins and found throughout the vertebrate body, serving as substrata for overlying cellular structures. The topography of basement membranes is a complex meshwork of pores, fibers, ridges, and other features of nanometer sized dimensions. Synthetic surfaces with topographical features have been shown to influence cell behavior. These facts lead to the hypothesis that the topography of the basement membrane plays an important role in regulating cellular behavior in a manner distinct from that of the chemistry of the basement membrane. This paper describes the topography of the basement membrane and reviews the fabrication of synthetic micro- and nano-structured surfaces and the effects of such textured surfaces on cell behavior.

Animals↗

PubMed1999

Bacterial adhesion to functionalized polyurethanes.

The effect of fibrinogen and high molecular weight kininogen on bacterial adhesion to functionalized polyurethanes was studied. Glass slides were coated with different polyurethanes, including Pellethane, sulfonated Pellethane, phosphonated Pellethane, a zwitterionic phosphonated polyurethane, and quaternized amine polyurethanes. The polymer-coated glass squares were exposed to radiolabelled S. aureus. When comparing adhesion to bare polyurethanes, it was found that adhesion was lowest on the phosphonated Pellethane and the zwitterionic phosphonated polyurethane while highest on the methyl quaternized polyurethanes. Fibrinogen-mediated adhesion was studied by first exposing the polymers to increasing concentrations of canine fibrinogen before incubating them with S. aureus. All the polymers except the quaternized amine polyurethanes exhibited at least ten-fold increases in bacterial adhesion as the fibrinogen treatment concentration was increased from 0.0 to 10.0 microg ml(-1). The quaternized amine polyurethanes maintained their relatively high amount of bacterial adhesion regardless of the fibrinogen concentration. The effect of two-chain high molecular weight kininogen (TCHMWK) on fibrinogen-mediated bacterial adhesion was assessed by exposing the polymers to 1.0 microg ml(-1) fibrinogen followed by two different concentrations of TCHMWK. Decreases in bacterial adhesion were observed on all the polymers except the quaternized amine polyurethanes, which again retained their relatively high amount of bacterial adhesion.

Animals↗