Biomedical subjects

W J Seare

Publications and source records attributed to W J Seare.

3 recordsLinked to original sources

PubMed2000

Alloplasts and biointegration.

During the past 2000 years, medical science has embraced the use of alloplastic materials to improve and replace many bodily functions. During the past 50 years, there has been a virtual explosion of alloplastic implant and device technologies. Alloplasts have been borrowed from industry with few if any modifications. Experimental and clinical studies have shown that smooth, textured, and fabric-surfaced alloplasts excite a fibrous capsule around the implant and distance normal tissue and vascularity from the implant-tissue interface. In contrast, some porous alloplasts have been shown to bond with tissues, reducing the fibrous encapsulation and promoting vascularization. The physical and chemical stability of the implant in situ and its surface composition, texture, and pore size significantly influence the tissue response. Lessons learned during the past 50 years are now being translated into new medicine-specific alloplasts.

Animals↗

PubMedDate not supplied

Surface texturing and coating of biomaterial implants: effects on tissue integration and fibrosis.

To determine whether texturing and coating have additive effects in promoting tissue integration and inhibiting fibrosis, we evaluated smooth silicone rubber (SSR), textured silicone rubber (TSR), porous silicone rubber (PSR), expanded polytetrafluoroethylene (ePTFE), and porous polyurethane (PPU) subcutaneous implants in eight minipigs. Some of the implants were coated with type IV collagen (Col) and/or fibronectin (Fn). At 6 months, we removed the implants and examined them microscopically. Texturing was more important than Col and Fn in reducing fibrosis and inflammation. The PSR yielded the best response, including reduced fibrosis and inflammation, satisfactory adherence, and no dystrophic mineralization.

Animals↗

PubMedDate not supplied

Quantitative bacterial analysis of porous, fabric, and smooth non-blood contacting implant surfaces and their tissue interfaces in a 169 day pneumatic total artificial heart animal recipient.

All long-term total artificial heart (TAH) survivals are subject to sepsis. Survival can be prolonged, but the source of the infection cannot be eliminated with any known course of antibiotics or treatment regimen. Sambo, a U-100 pTAH calf, survived 169 days. At week 6, he became septic, growing a Pseudomonas species (Ps). Weekly blood cultures were intermittently positive until week 13 when they became continuously positive until his demise, from a ruptured left ventricular pumping diaphragm. Spatially specific porous silicone rubber (SSP) was used for surface modifications on the drive lines and as cuffs around the Dacron TAH graft to large vessel anastomoses. This gave an excellent opportunity to examine two types of porous implants surfaces (Dacron grafts and SSP) to the smooth Biomer ventricular surfaces with their respective adjoining tissue interfaces for bacterial colonization. Nine tissue samples and 13 implant surfaces were processed with Costerton's quantitative bacterial techniques. The largest numbers of bacteria (> 10(6)/cm2 Ps.) were grown from the smooth ventricular surface and in the cul-de-sac where the SSP delaminated from the driveline (two smooth implant surfaces in contact but without tissue apposition). The Dacron grafts were intermediate in bacterial concentrations and SSP surface modified drivelines and tissues were sterile. In this model, the more intimate biointegration found in the porous implants showed improved bacterial resistance in a chronically infected pTAH. The more completely biointegrated and neo-vascularized porosity SSP was the only implant surface and opposing implant tissue interface sampled to remain sterile.

Animals↗