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At least 73 records · Page 4Linked to original sources

PubMed1987

Radiosterilization of albuminated polyester prostheses.

The study reported here is concerned with the radio-sterilization of Dacron vascular prostheses coated with crosslinked albumin. gamma-Radiations have no effect on the mechanical properties of the polyester fibres or on their crystallinity, whether irradiated in a dry state or immersed in saline. Special attention has been paid to the release of the albumin, or protein fragments from the reticulum using 125I-labelled albumin as a radiotracer. The albumin leakage depends upon the type of Dacron fabrics considered but the values derived from radioactivity measurements are always greater than those directly measured, which indicates a radio-induced break of the bond between iodine and albumin; this has nothing to do with the break of the association between albumin and Dacron. Moreover no cytotoxicity of the irradiated immersion medium has been observed using a test based on organotypic culture in liquid medium. Thus radio-sterilization of an albuminated polyester vascular prosthesis immersed in saline appears to be a suitable procedure.

Albumins↗

PubMed1988

Experimental colonization of a polyester vascular graft with Staphylococcus aureus: a quantitative and morphologic study.

Colonization of a polyester (Dacron) vascular graft by Staphylococcus aureus 209P-R was studied. Twenty-five dogs had thoracoabdominal aortic bypass. After intervals of 2 hours (three dogs), 8 days (five dogs), 1 month (six dogs), 2 months (six dogs), or 6 months (five dogs), a bacteremic challenge was produced by intravenous injection of 6 x 10(8) colony-forming units of S. aureus. Two hours later grafts were removed and cut into 10 fragments, each submitted to bacterial counts and scanning electron microscopic studies. Results of bacterial counts were expressed in colony-forming units (CFU) per square centimeter of graft segment (median [lower to upper quartiles]). Normal canine aortas (n = 2) used as controls trapped no bacteria. Colonization of Dacron grafts varied according to the duration of graft function (p less than 0.01): after 2 hours, 4416.5 CFU (1158 to 9073 CFU); after 8 days, 1515 CFU (963 to 2893 CFU); after 1 month, 199 CFU (86 to 538 CFU); after 2 months, 615 CFU (243 to 1407 CFU); and after 6 months, 1 CFU (1 to 5 CFU). Heavily colonized fragments were observed for duration of graft function of 2 months or less, whereas at 6 months all the fragments trapped fewer than 50 CFU/cm2 of graft segment. Scanning electron microscopy showed that colonization was closely associated with healing. Staphylococcal entrapment was related to the amount of fibrin deposits, which were especially abundant where the thrombotic matrix was unorganized and on bare polyester filaments. Graft colonization is especially to be feared in the first weeks after graft implantation, an observation which may help to define guidelines for preventing hematogenous vascular graft infection.

Animals↗

PubMed1975

A comparison in vivo dacron wool (Swank) and polyester mesh (Pall) micropore blood transfusion filters in the prevention of pulmonary microembolism associated with massive transfusion.

Experiments were performed to compare the effectiveness in vivo of the two most widely used micropore blood transfusion filters in preventing detrimental physiologic changes associated with transfusion of microaggregate-containing blood. Exchange transfusion with stored blood having an elevated screen filtration pressure (SFP) through polyester mesh (Pall) filters (Group PM) was followed by decreases in arterial blood pH and O2 consumption, increases in arterial blood pyruvate and lactate concentrations, and a decrease in pulmonary DO2. The lungs of 5 of 6 animals revealed emboli far out in the pulmonary microcirculation. These changes did not occur in animals transfused through dacron wool (Swank) filters (Group DW). Even though an increase after transfusion in pulmonary Qs/Qt in Group PM did not achieve statistical significance when compared to pretransfusion Qs/Qt, it was significantly higher than that in animals in Group DW. Both filters removed considerable quantities of microaggregates; however, the polyester mesh (Pall) filters permitted passage of small microaggregates and development of ditrimental physiologic changes. Dacron wool (Swank) filters completely removed measurable microaggregates and detrimental changes did not occur.

Animals↗

PubMed1984

Comparison of the structure of neotendons induced by implantation of carbon or polyester fibres.

Carbon-fibre and polyester-fibre implants of comparable dimensions were used to replace the calcaneal tendon in 30 sheep. The neotendon produced in proximity to the polyester fibres was denser, more collagenous and more closely adherent than that in the carbon-based neotendon. Fragmentation of the carbon caused continuing cellular reaction which was associated with a poor collagen response.

Animals↗

PubMed1984

Polyester wax embedding and sectioning technique for immunohistochemistry.

We have developed a method useful for immunohistochemical studies by combining tissue fixation with buffered neutral formalin and polyester wax embedding. Buffered neutral formalin fixation preserves cell and tissue fine structure, and also the antigenicity of unstable enzymes. Polyester wax embedding makes possible thin serial sections of various tissues and preserves antigenicities for at least 6 months. We have demonstrated using this technique the localization of alpha-amylase in mouse salivary gland, parietal-cell specific antigen in mouse glandular stomach, and DNA polymerase alpha and beta in chick tissue.

Animals↗

PubMed1986

Permanent preservation of whole alizarin red S skeletons by clearing and embedding in polyester resins.

A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method.

Anthraquinones↗

PubMed1975

[Polyester knitted nets in pediatric surgery].

The paper concerns the clinical evaluation of polyester knitted nets produced by Central Laboratory of Knitting Industry in Lódź used for reconstructive operations of abdominal and chest wall. The polyester knitted net was used in 29 children (newborns, infants and older children). Basing on the clinical observations and microscopic examinations there is discussed healing-in of the knitted fabric and complications observed during the postoperative course.

Age Factors↗

PubMed1989

[Dental resin for restoration with unsaturated polyester resin used as base material. Effect of catalyst, accelerator and subaccelerator on working time, setting time and peak temperature].

The fatal demerit of resin materials which causes a marginal sealing defect or marginal fracture is hard to eliminate. A series of studies seeking for dental resin for restoration having no polymerization shrinkage, applying polyester resin used as base resin. This study was conducted to promote the improvement of composite resin, in which the author examined the composition with catalyst, accelerator and subaccelerator having preferable working time, setting time and peak temperature which is not clear, so as to obtain the fundamental data. In accordance with the increase in the amount of catalyst, accelerator and subaccelerator added, peak temperature showed a tendency to increase. Contrarily, working time and setting time showed a tendency to decrease. The composition showing preferable working time, setting time and peak temperature, is as follows: to the base resin, polyester with 38 wt% of shrinkage inhibitor mixed, catalyst by 1.0 wt%, accelerator by 0.50 wt% and subaccelerator by 0.02 wt% were added. The trial product of composite resin a 70 wt% of surface-treated glass beads added showed a working time of 2.3 minutes, setting time of 9 minutes and peak temperature of 57.0 degrees C, approximately the same values as of commercial composite resin.

Dental Restoration, Permanent↗

PubMed1975

Bone induction effect of fine bone shavings in polyester fibre. An experimental study.

Autogenous marrow-free bone shavings of dense lamellar bone spread over polyester mesh were transplanted into muscle, the palate and the tibia. A thin sheet of silastic was used to eliminate the induction effect of the adjacent bone, and the results were evaluated histologically. It was found that finely divided autogenous bone shavings actively induce new bone formation, and that the rate of bone production depends on the proximity of bone-competent tissue, such as a muscle tendon or a muscle attachment. Osteogenesis is also stimulated by a direct blood supply from the adjacent bone. Polyester mesh (Mersilene) is a relatively inert material, which could be used to great advantage in the transplantation of bone. Preliminary results of this research indicate that it may be of great value in bone reconstruction. These experiments support the idea of a non-cellular and diffusible bone stimulatory substance which influences the inducible osteogenic precursor cells to produce bone.

Animals↗

PubMed1988

Application of Neuhoff's optimized Coomassie brilliant blue G-250/ammonium sulfate/phosphoric acid protein staining to ultrathin polyacrylamide gels on polyester films.

An optimized Coomassie staining procedure, utilizing Coomassie Brilliant Blue G-250 in phosphoric acid/ammonium sulfate, was applied to ultrathin-layer isoelectric focusing in 0.18 mm polyacrylamide gels, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in 0.38 mm polyacrylamide gels, both backed to Gel-Fix polyester supporting films. After isoelectric focusing staining of gelatin and acidic proteins was better with the phosphoric acid/ammonium sulfate procedure than with conventional organic solvent methods. When applied to gels after sodium dodecyl sulfate-polyacrylamide gel electrophoresis the sensitivity of the phosphoric acid/ammonium sulfate method was equal to that on conventional staining but lower than on silver staining.

Acrylic Resins↗

PubMed1983

Polyester prostheses as substitutes in the thoracic aorta of dogs. I. Evaluation of commercial prostheses.

Using canine models, a representative selection of polyester or Dacron vascular prostheses, including woven, knitted, and velour types, were evaluated for their relative healing characteristics and for their structural changes during implantation. Following residence periods ranging from 4 h to 6 months at the site of the thoracic aorta, the dogs were sacraficed, and the grafts were excized for measurement of the thrombogenicity of the flow surface and for pathological examination by light microscopy and SEM. The kidneys were also removed and examined for infarcts caused by any trapped circulating emboli. The extent of healing, the presence of embolizing nuclei, and the thrombogenicity and morphology of the lumen surface were also assessed. The healing characteristics of each type of device proved similar. Velour fabrics exhibited more extensive encapsulation, but frequently their internal capsules failed to incorporate all the fibers. In all cases, cellular development on the lumen was limited to areas contiguous to the anastomoses. The initial porosity of the devices as measured by water permeability did not appear to influence the healing sequence to a significant extent. The grafts did exhibit differences in structural stability depending on whether they were of a knitted or woven construction. We suggest that users consider these different mechanical and structural properties when making their choice of a graft. Despite these differences, we believe that the healing process is far more host dependent than graft dependent.

Angiography↗

PubMed1985

Nerve regeneration through biodegradable polyester tubes.

One approach to repair of transected nerves is to attempt extrinsic guidance of axons across the gaps. We inserted the proximal and distal stumps of severed mouse sciatic nerves into opposite ends of biodegradable polyester tubes. The nerves and ensheathing tubes were examined after postoperative survival times of as long as 2 years. Myelinated fiber number in each successfully regenerated nerve was measured and correlated with the tube's residual lumen size. In selected regenerated nerves axonal sizes and myelin sheath widths were sampled and compared with control values. Swelling and deformation of tube walls occurred in nearly all tubes. Successful regeneration was obtained through more than half of the implants, and was more probable in tubes with larger initial lumens. Myelinated fiber number in regenerated nerves ranged from 231 to 3561 (normally 3900 to 4200); larger values again were found in tubes with larger initial lumens. Mean axonal areas in regenerated nerves were roughly half of normal, though myelin sheaths became appropriately thick. We concluded that the more biodegradable a tube, the more likely it was to incur distortion and luminal narrowing. Tube composition per se seemed of importance mainly as it related to maintenance of adequate luminal size over the length of the degrading tubes; luminal adequacy, not tube composition, seemed paramount in determining the extent of nerve regeneration.

Animals↗

PubMed1990

Evidence for microbial polysaccharide preparations containing polyester substituents.

CPMAS 13C-n.m.r. spectroscopy was employed to characterize the composition and solid phase morphology of gellan, welan, rhamsan and NW11. Spectra indicated that commercial preparations of these polysaccharides, which share a similar molecular backbone, contain a non-carbohydrate component exhibiting four inequivalent carbon atoms. Isolation of this component, followed by 13C-n.m.r. in CHCl3 and MS analysis, revealed its structure to be poly(beta-hydroxybutyrate). Evidence is presented which suggests that this polyester may be a covalent adduct to the above polysaccharides, although this cannot be unambiguously determined at this time. Further experimentation is in progress.

Hydroxybutyrates↗

PubMed1986

Tissue reaction to polypropylene and polyester in obese patients.

Local tissue reaction was examined after subcutaneous implantation for 8 wk of small pieces of Marlex (polypropylene) and Dacron (polyester) in 11 extremely obese patients. Dacron gave a stronger chronic inflammatory reaction in 7 out of 11 patients, and a stronger foreign body giant cell reaction in all of them: Marlex is therefore perhaps more suitable than Dacron as a reinforcement band in gastric surgery for obesity. At reoperations due to complications after gastric banding the tissue reaction in the omentum which covered the band, was examined in 9 patients. No major difference in tissue reaction in the omentum compared to that in subcutaneous fat was found. None of the reoperations was caused by too strong a tissue reaction to the reinforcement band i.e. Marlex in 8 patients and Gore-tex (Teflon) in one patient.

Biocompatible Materials↗

PubMed1989

Cellular reactions to polyester arterial prostheses impregnated with cross-linked albumin: in vivo studies in mice.

This study was designed to assess the possible immunological responses in mice against polyester prostheses coated with albumin and previously stabilized either with cross-linked glutaraldehyde (GA), at different concentrations, or with carbodiimide (CDI). Prosthetic discs were first implanted in the peritoneal cavities of mice, and T cells and T cell subsets (helper, suppressor, la-bearing T lymphocytes) were then quantified before implantation and at 1, 2, 3 and 4 weeks post-implantation. The percentages of T cells, subsets, and the helper/suppressor cell ratio, as well as the percentage of T cells with la receptors, were similar to the control in all experimental groups. No significant difference and no correlation were observed between the groups wherever tested. Virgin and albumin-coated grafts did not induce any quantitative changes in T cell subpopulations in mice.

Albumins↗

PubMed1989

Experimental evaluation of a gelatin-coated polyester graft used as an arterial substitute.

Protein coating and endothelial cell preseeding have been proposed and studied as improvements to arterial prostheses. In this paper, an impervious polyester vascular graft which had been coated with cross-linked gelatin was compared to a porous one over a period of up to 8 months in dogs. This evaluation involved in vivo methods using radio tracers to study patency and thrombogenicity and in vitro controls of the healing processes. The main advantages offered by coated grafts over uncoated include the absence of preclotting and better biointegration.

Animals↗

PubMed1991

Partially biodegradable polyacrylic-polyester composites for internal bone fracture fixation.

New partially resorbable composite formulations based on components used in surgery were synthesized in rod form (length 15-20 mm, diameter 4 mm). The biostable components were poly(methyl methacrylate) in hydrophobic implants and poly(2-hydroxy ethyl methacrylate) in hydrophilic ones. The biodegradable components were commercially available suture yarn made from poly (alpha-hydroxy esters): polyglycolide, a polyester derived from glycolic acid; and a copolyester of glycolic and lactic acids, polyglactin 910. Biodegradation in phosphate-buffered solution at pH 7.0 and 37 +/- 0.5 degrees C was analysed gravimetrically. There was no measurable loss of mass after treatment for 20-25 d. Composite microstructure was examined by phase-contrast, cross-polarized light microscopy.

Biocompatible Materials↗

PubMed1992

Polyester film strips coated with photographic gelatin containing immobilized glucose oxidase hardened by chromium(III) sulphate.

Glucose oxidase was immobilized into photographic gelatin hardened by chromium(III) sulphate. The enzyme-gelatin mixture was coated on polyester film strips which allowed easy and simple handling during assays. The effect of gelatin and cross-linker concentrations on water content and enzymatic activity was studied. The effect of pH during immobilization and that of incubation temperature on maximum activity were examined. Enzyme leakage tests were carried out during reuse number studies. Consecutive use of strips followed by washing and resting between uses were found to affect the reuse number. A maximum immobilization of 68% was reached under optimal conditions. Mechanical stability and leakage were found to be functions of gelatin and cross-linker concentrations. Photographic gelatin was found to have many capabilities with extraordinary characteristics as a carrier on immobilization.

Biocompatible Materials↗