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Biomedical subjects

D F Williams

Publications and source records attributed to D F Williams.

At least 145 records · Page 8Linked to original sources
PubMed1984

Effects of physical configuration and chemical structure of suture materials on bacterial adhesion. A possible link to wound infection.

The purpose of this study was to examine the effects of physical configuration and the chemical nature of suture materials on the preferential adherence of bacteria. Ten suture materials of 2-0 (chromic catgut, Dexon, Vicryl, PDS, Mersilene, Tycron, Ethibond, Surgilon, Ethilon, and Prolene) were used. The bacterial strains tested were Staph. aureus and E. coli. The level of bacterial adherence was determined quantitatively by radiolabelled cells and qualitatively by scanning electron microscopy. It was found that the amount of adhered bacteria depended on the type of suture material, the type of bacteria, and the duration of contact. In the group of absorbable sutures, the new PDS sutures exhibited the smallest affinity toward the adherence of both E. coli and Staph. aureus. Dexon sutures had the highest affinity toward these two bacteria. With nonabsorbable sutures, the physical configuration of the sutures contributed more to their ability to attract bacteria than the surface finish. The bacterial adherence on suture materials was also time dependent. Scanning electron microscope morphologic observation also indicated that Staph. aureus adhered on the suture surface in clusters whereas E. coli tended to adhere individually.

Absorption↗
PubMed1984

The response of bone to carbon--carbon composites.

A cloth-sandwich construction of a carbon-carbon composite material has been implanted in the femora of a series of rats and the response of the bone to this material compared to the response to titanium. It is shown that the carbon provides for excellent hard tissue biocompatibility. When the composite has a surface texture associated with fibre run out there is a degree of bony attachment, the interfacial shear strength for the composite-bone system being significantly greater than that for the titanium-bone system during the period 4-40 weeks post implantation.

Animals↗
PubMed1983

The effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures.

The purpose of the study was to examine the effect of gamma irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures. The sutures of size 2-0 were irradiated at dosage levels of 0-20 mrad. The three enzymes chosen for this study were esterase, alpha-chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions; their corresponding buffer controls, and implanted in inbred black-and-white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH = 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the configuration and chemical structure of the PGA sutures.

Biodegradation, Environmental↗
PubMed1983

Quantitative microradiography of cortical bone in disuse osteoporosis following fracture fixation.

Stainless steel (elastic modulus 210 GN/m2) and carbon fibre reinforced epoxy resin (elastic modulus 65 GN/m2) plates have been attached to intact femora in cats and the development of disuse osteoporosis assessed by microdensitometric methods after 8 months. The bone adjacent to the stainless steel plate showed evidence of considerable demineralization, both uniformly throughout a section and especially at certain focal points. A noticeable, but much smaller amount of osteoporosis developed adjacent to the composite plate. Various methods of presenting quantitative micro-densitometric data are used.

Animals↗
PubMed1983

Laser techniques for the evaluation of wear in Class II restorations.

A technique for the quantitative determination of the changes in surface topography of restorations during wear has been developed. This involves the optical contouring of the surface using a laser, and the generation of contour maps. Several different methods for interpreting these maps are discussed. A computer-aided method is the most consistently accurate and measures wear volume to an accuracy of 2--5%.

Computers↗
PubMed1982

The effects of proteins on metallic corrosion.

The corrosion of the pure metals aluminium, cobalt, copper, chromium, molybdenum, nickel, and titanium and of a cobalt-chromium molybdenum casting alloy has been studied in buffered saline with and without the presence of the proteins serum albumin and fibrinogen. The corrosion of aluminium and titanium was unaffected by the protein. The corrosion rates of chromium and nickel showed a slight increase, while cobalt and copper dissolved to a very much greater extent in the presence of protein. However, with molybdenum the corrosion was inhibited by protein.

Alloys↗
PubMed1982

A study of sarcogenicity associated with Co-Cr-Mo particles implanted in animal muscle.

A study has been made of the sarcogenicity of particles of cobalt-chromium-molybdenum alloy. The particles were implanted as a dry powder into a surgical incision into the dorsal paraspinal muscle of adult female rats and guinea pigs. Two preparations were used. In one, the particles had a size range of 100-250 micrometers. This preparation was implanted into 51 Wistar rats. In the other, the particles had a size range of 0.5-50 micrometers, 85% being in the range 0.5-5 micrometers. This preparation was implanted into 61 Wistar rats, 53 hooded rats, and 46 Dunkin Hartley guinea pigs. Sham operations were carried out on a control group of 50 Wistar rats. No malignant neoplasms developed at the test or control operation sites during the time periods for which the animals survived. This negative finding contrasts with that from a previous study by Health, Freeman and Swanson, who observed sarcomas in rats at sites of intramuscular injection of cobalt-chromium-molybdenum particles suspended in horse serum. Possible explanations for this difference in results are discussed.

Animals↗
PubMed1982

Scanning electron microscopy of the metal-tissue interface. I. Fixation methods and interpretation of results.

Scanning electron microscopy has been used to study the interface between implants of pure metals and the muscular tissue of rats. Several problems arise in the interpretation of the observations made, due to the potential for disruption to the tissue and the exacerbation of any corrosion that may have occurred in vivo during the fixation periods. Details are given of the control experiments performed in order to ascertain the nature of potential artefacts and of the techniques eventually determined to be optimal for these purposes.

Animals↗
PubMed1982

Scanning electron microscopy of the metal-tissue interface. II. Observations with lead, copper, nickel, aluminium, and cobalt.

The nature of the metal-tissue interface following the implantation of five pure metals, lead, copper, nickel, aluminium and cobalt, in rats has been observed by scanning electron microscopy. The general conclusion, derived from light microscopy that the tissue response to pure metals is characteristic of and specific to individual pure metals has been confirmed in this study. However, far more detailed observations of factors such as the extent of metallic corrosion, the distribution of red blood cells, platelets and other cells in the capsule and adherent to the metal surface, have been possible with SEM.

Animals↗
PubMed1981

The response to the intramuscular implantation of pure metals.

Discs of five high-purity metals, cobalt, nickel, copper, aluminium and lead have been implanted intramuscularly in rats and the response observed histologically for period up to 52 weeks. A reproducible but different response was observed with each metal. Whenever corrosion occurred, as with copper, nickel and some cobalt specimens, the implants became loose. In the absence of corrosion, the implants were firmly held within a more confined capsule. A minimal response was seen with lead, implying normally toxic metals do elicit an immune response whilst some, especially copper and nickel appear to render the host more susceptible to disease. The implants appear to have a profound effect on the immediate vasculature, are able to cause a prolonged polymorphonuclear response in the same way as bacteria, are associated with varying amounts of haemosiderin laden macrophages but not with giant cells. The animals appear to be able to deal with bacteria introduced at surgery without hindrance from the metal.

Aluminum↗