PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Polyesters”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed1982

Enzymatic removal of formalin-fixed tissues from polyester arteries, and its effect on physical properties of fibers.

A method is presented that can be utilized for the removal of formalin-fixed tissues from arterial grafts without affecting fiber material properties. Such a method could prove highly useful for studying the changes in the structure and properties of graft fiber as functions of important clinical variables. Information on what actually happens to the arterial graft material in situ with passage of time is greatly lacking in the current graft literature. The method proposed involves treatment of the formalin-fixed fiber-tissue complex with an enzymatic preparation containing enzymes derived from the porcine pancreas (pancreatin) in solution with tris(hydroxymethyl) aminomethane buffer at pH 7.6. Studies with two different grafts--a Microknit Dacron Bifurcation from a clinical patient 10 1/4 years after implantation and stored in formalin for 11 months, and a Sauvage Filamentous Velour of Dacron from an animal 24 h after implantation and stored in formalin for nine months--showed that the treatment was highly effective in completely removing the tissues at concentrations of pancreatin as low as 2.5%. The same treatment given to the virgin yarns of grafts revealed no significant effects on tensile, dimensional, and morphological properties.

Animals↗
PubMed1984

A histopathological study of the percutaneous implantation of polyester fibers.

A histopathological study was made on scalp biopsies at 1 day, 1 week, 2 weeks, 1 month, 2 months, 5 months, and 20 months following implantation of synthetic fibers developed as artificial hair in Japan, in order to determine the histological conditions of its fixation over an extended period. In addition, the operative technique and materials for implantation were explored.

Biocompatible Materials↗
PubMed1988

Multiple gamma radiation sterilization of polyester fibres.

Gamma radiation with a dose of 2.5 Mrad has been found to be suitable to sterilize polyethylene terephthalate (PET) bulk materials intended for biomedical applications. The radiation stability of PET bulk materials and fibre may not however be taken as identical due to the changes in the polymer structure during the processing of bulk materials for fibre. The chemical changes occurring in PET fibres during single and multiple (prolonged) sterilization in air were investigated. It was found that single sterilization (2.5 Mrad) itself affected the PET yarn and fibre. This was exhibited by the increase of crystallinity from 30.5 to 37% in the case of yarn and from 40 to 44% in the case of fibre. The breaking load of the yarn also increased from 441 g to 451 g. These changes were attributed to the degradation of PET in the amorphous region and the recombination of degraded aliphatic segments. Sterilization at higher doses affected the crystalline region which decreased the crystallinity, breaking load and molecular weight. For samples irradiated at 2.5 Mrad, the breaking load increased, though the dispersity increased. This was attributed to cross-linking by recombination. The increase in crystallinity also enhanced the breaking load of the samples. Higher doses of sterilization led to drastic microstructural and macrostructural changes as seen from the molecular weight. It was inferred that the changes in crystallinity and microstructure that occurred during multiple sterilization might affect the biocompatibility of the material.

Biocompatible Materials↗
PubMed1992

Biocompatibility of the Vascugraft: evaluation of a novel polyester urethane vascular substitute by an organotypic culture technique.

To evaluate the biocompatibility of chemically and structurally modified polyurethane elastomers for use as blood vessel replacements, small squares of vascular prostheses were cultured in direct contact with endothelium from chick embryo aorta using an organotypic culture assay. The polyurethane materials tested were: Vascugraft (fibrous, open pore structure); commercial Hydrophilic Mitrathane prosthesis (high porosity, smooth surface, non-permeable, closed pore structure); experimental hydrophobic Mitrathane (less porosity but a fibrous, open pore structure, similar to Vascugraft). The commercial expanded polytetrafluoroethylene prostheses Impra and reinforced GORETEX were included as controls on account of their extensive clinical application in the femoropopliteal position. After 5 d incubation at 37 degrees C biocompatibility was assessed in terms of average area of migrating cells on the biomaterial, total number of cells surrounding the explant and level of adhesion between the cells and the biomaterial. The Vascugraft prosthesis promoted the growth of a continuous monolayer of cells on its surface. This behaviour was equivalent to Impra and reinforced GORETEX materials in terms of cell density and area of cell migration but appeared to be superior for cell adhesion. From a second series of cell culture tests, in which the extractables leached from the biomaterials were added to the nutrient medium, it was concluded that none of the biomaterials tested released cytotoxic contaminants.

Animals↗
PubMed1996

Biological molecule-impregnated polyester: an in vivo angiogenesis study.

Specific extracellular matrix molecules and growth factors (GFs) with angiogenic properties could be combined with biomaterials to enhance angiogenesis and subsequently tissue ingrowth through the wall of the porous structure. In this study, composite fibrin matrices containing hyaluronic acid (HA), fibronectin (FN) and/or fibroblast growth factor-1 (FGF-1), FGF-2 and an endothelial cell growth supplement (ECGS) were adsorbed onto Dacron meshes which were then implanted subcutaneously in mice. The release from the implants and the tissue distribution of implanted GFs were determined in vivo using radiolabelled FGF-2. Angiogenesis was quantified by counting the number of capillaries present in each Dacron histological serial section. Radiolabelled GF was rapidly released from matrices and was absent from them by day 28. A very low percentage of the implanted radiolabelled GFs was found in the kidneys and livers of the animals. The number of microvessels formed within fibrin-impregnated samples was increased in the presence of HA and ECGS at 14 d and of FN and ECGS or FGF-2 at 28 d. FGF-1 had no direct effect on angiogenesis in our model. These results indicate that enhancement of vascularization within prosthesis mesh may be achieved by using fibrin as a support for angiogenic molecules such as HA, FN and FGFs.

Animals↗