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At least 127 records · Page 7Linked to original sources

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↗

PubMed1993

Numerical and functional modifications in platelets induced by polyester coated by a hydrophilic polymer.

We evaluated the alterations in number, functionality and release reaction of the platelets contained in plasma, filtered through a polyester filter and coated with a hydrophilic polymer. The alterations in number were examined by counting before and after filtration. The morphological modifications were studied by determining the mean platelet volume. The functional alterations were analysed by a platelet aggregation test, induced by ADP and collagen. The presence of products from the release reaction in filtered plasma was studied using radioimmunoassays of beta-thromboglobulin, platelet factor 4 and thromboxane B2. The results obtained showed that the filtration of plasma through the material did not determine a significant platelet adhesion, did not alter the volume or the functionality of the platelets and induced no release reaction.

Biocompatible Materials↗

PubMed1996

An albumin-coated polyester arterial graft: in vivo assessment of biocompatibility and healing characteristics.

The albumin-coated vascular graft (ACG) and its uncoated polyester substrate, the Vascular II (V-II), were evaluated in terms of biocompatibility and biofunctionality using two in vivo animal studies. Biocompatibility and immunoreactivity were assessed by implanting intraperitoneally in the rat small segments of the ACG and the V-II graft and harvesting them with their surrounding tissue 3d, 1, 2 and 4 weeks later. Cytofluorometric determination of total T cells (CD3), the ratio of CD4/CD8 subsets and the percentage of IL-2 receptor-positive T cells in the peripheral blood has revealed that no significant difference in any of the T cell populations was found between the ACG and the V-II graft. The cellular reactivity of the ACG in terms of acid phosphatase activity at the implant side was significantly greater at 3 d but not at longer periods. Biofunctionality was evaluated by implanting both grafts as a thoracoabdominal vascular bypass in dogs for 11 different periods ranging from 4 h to 6 months. The rate of albumin resorption was such that traces were still present at 1 month, but no longer observable at 2 months. Tissue incorporation into the graft wall was earlier for the V-II (2 weeks) than for the ACG (4 weeks), which showed complete encapsulation, tissue incorporation and endothelialization after 2 months in vivo. Only small differences were observed between both grafts in terms of platelet and fibrin uptake on the luminal surface. The prostacyclin/thromboxane A2 ratio increased to a level higher that 1.0 aorta within 1 month for the V-II and 4 months for the ACG. In conclusion, the Bard ACG has demonstrated excellent biocompatibility in terms of blood T cell behaviour and acid phosphatase activity at the implant site. Finally, its healing response is equivalent to that of the uncoated Dacron prosthesis once the albumin coating has been resorbed.

Acid Phosphatase↗

PubMed1990

Use of polymyxin-coated polyester cloth in the enzyme immunoassay of Salmonella lipopolysaccharide antigens.

Polyester cloth coated with polymyxin B was used to capture Salmonella typhimurium lipopolysaccharide antigens which were then quantitatively or qualitatively assayed using a specific antibody-peroxidase conjugate. This simple, rapid method can be used to assay a large number of samples by employing a large sheet of the polymyxin-coated cloth onto which multiple samples can be blotted. The method is reproducible and economical, since polymyxin B is relatively inexpensive, stable and available in pure form.

Adsorption↗

PubMed1984

Albumin coating of a knitted polyester arterial prosthesis: an alternative to preclotting.

Coating a knitted polyester arterial prosthesis with cross-linked albumin fills the interstices of the graft and relieves the surgeon of the necessity to preclot . This is of particular value in patients whose blood clotting properties are hypercoagulable, or hypocoagulable . In addition, such prostheses require less handling, which can lower the risk of bacteremic colonization and shorten the operative time. The in vivo behavior of the implanted albuminated prosthesis in the thoracic aorta of dogs is similar to that of preclotted grafts, although the sequences of early healing are different. The preclotted graft develops a continuous, thick thrombotic matrix on its luminal surface during the first 4 hours of implantation. Following the initiation of the fibrinolytic mechanism 24 to 48 hours postoperatively, this thrombotic deposit quickly recedes , leaving blood cells and platelets adhering here and there to the prosthetic surface. In comparison, the albuminated coating is not associated with major early thrombotic deposits. The albumin remains visible between the filaments during the first 2 weeks of implantation. Both treated and control grafts contain numerous thrombi on their inner surface after 1 to 2 weeks. After 1, 3, and 6 months, both implants are well encapsulated and present a glistening and continuous luminal surface. This excellent healing, however, can be compromised should the graft adhere too closely to the animal's lungs.+2

Albumins↗

PubMed1987

[Complement activation in extracorporeal circulation. Comparison of nylon versus polyester bubble oxygenators].

Complement activation during cardiopulmonary bypass is well known and may influence postoperative morbidity. As nylon can particularly induce complement activation, its influence was assessed by measuring total haemolytic complement and B, C3 and C4 factors, during cardiopulmonary bypass with bubble oxygenators for coronary surgery, comparing "nylon" circuits (20 patients, Bentley BOS 10) versus "polyester" circuits (19 patients, Shiley S 100 A). Complement activation began with induction of anaesthesia and surgical procedures, B, C3 and C4 levels falling significantly (respectively 15, 17 and 20% from baseline values). The alternative pathway was activated before the classical pathway. Complement activation continued during cardiopulmonary bypass, with no more consumption of complement factors (slight variations of about 0 to 3% of the levels found after anaesthetic induction and surgical procedures). No statistically significant difference appeared between the two groups. This suggested that nylon did not significantly increase complement activation during cardiopulmonary bypass. The bubble oxygenator material cannot therefore be considered as a criterion for choosing the type of equipment.

Complement Activation↗

PubMed1986

Short-term in vivo stability of endothelial-lined polyester elastomer and polytetrafluoroethylene grafts.

A fibronectin substrate will significantly enhance the strength of endothelial cell attachment on grafts constructed of polyester elastomer (PE) and polytetrafluoroethylene (e-PTFE). This experiment was undertaken to determine the short-term in vivo stability of endothelium on these fibronectin coated surfaces. Eight mongrel dogs underwent bilateral carotid artery replacement with both graft materials. All grafts were inoculated with 2,000 cells/mm2 using cultured autogenous venous endothelium labelled with Indium-111-oxine. The Indium-111 label in the grafts was measured immediately prior to implantation, after 1 hour of in vivo perfusion, and at explantation after 24 hours. The percentage of inoculated cells attached to the grafts before perfusion was similar for both materials, 93.3 +/- 3.0% versus 92.2 +/- 7.2%, for PE and e-PTFE respectively. All grafts were patent at one hour after implantation. PE grafts were found to have 93.8 +/- 3.9% of the attached cells present at one hour while e-PTFE grafts had only 54.5 +/- 10.8% remaining, p less than .001. After 24 hours, 5/8 (62.5%) e-PTFE grafts and 2/8 (25.0%) PE grafts remained patent, p = .13. Of the patent grafts however, endothelial cell retention was still superior on the PE grafts with 78.0 +/- 0.6% of the attached cells remaining compared to only 24.5 +/- 6.1% on e-PTFE, p less than .001. Occluded PE grafts had fewer cells remaining at 24 hours than patent ones, 78.0 +/- 0.6% versus 31.1 +/- 32.8%, respectively, p = .13. Histologically, patent PE grafts demonstrated nearly confluent endothelial monolayers while e-PTFE had patches of endothelial cells surrounded by a platelet-fibrin carpet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Three-dimensional mammalian cell growth on nonwoven polyester fabric disks.

Small disks of nonwoven polyester fabric (NWPF), similar to Fibra-Cel carriers, were surface treated with strong acid and used as a high surface area support matrix for in vitro culture of anchorage dependent MRC-5 cells. The disks can be autoclaved, and require inocula concentrations of only 2-5% of the final cell densities, which have reached 10(8) cells/mL of disk bed volume. Scanning electron microscopy photographs shown herein reveal that cells grow in a multilayered fashion between the randomly arrayed fibers of the nonwoven fabric, emulating in vivo growth.

Cell Adhesion↗

PubMed1991

Histologic and immunohistochemical studies on the preparation of white cell-poor red cell concentrates: the filtration process using three different polyester filters.

Three third-generation white cell (WBC)-depletion filters based on polyester layers with decreasing pore size were investigated. In the coarse layers, unaggregated granulocytes, monocytes, and platelets and aggregates of these cells were captured in close contact with the fibers. This indicates that the depletion of granulocytes, monocytes, and platelets in the coarse layers of the filters is due in part to activation and adhesion with the formation of cell clusters on the fibers. In Filter I and Filter II platelets were not found in the fine layers, whereas in Filter III, 70 percent of the platelets were detected as unaggregated platelets on the fibers of the fine layers. More than 95 percent of the lymphocytes captured in the three filters occurred as single cells in the fine layers, and over 60 percent of these could be recovered. This suggests that the depletion of lymphocytes depended on trapping of the cells in the fiber network. All three filters captured HLA-DR-positive lymphocytes in the top layers, a finding that supports earlier reports that the transfusion of filtered red cell concentrates reduces HLA alloimmunization. More lymphocytes and granulocytes were found in the last layer of Filters II and III than of Filter I. Therefore, the risk of white cell leakage is probably lowest for Filter I. Red cells were found as red cell aggregates in the fine layers of Filters I and II, whereas almost no red cells were detected in Filter III. It was shown that the three filters studied were similar in their removal of WBCs, but differed in their mechanisms of removal.

Blood Platelets↗

PubMed1992

Prevention of growth of Yersinia enterocolitica in blood by polyester fiber filtration.

The ability of polyester white cell-reduction blood filters to prevent the growth of Yersinia enterocolitica in units of donated blood was studied. Sixteen units of freshly drawn blood were inoculated with 10, 50, 100, or 150 colony-forming units (CFU) per mL of a clinical isolate of Y. enterocolitica (serotype O:3). The units were subsequently fractionated into red cell concentrate and resuspended in AS-1 or AS-3 solution. One-half of the red cell concentrates in each solution were filtered within 15 hours of phlebotomy and stored for 42 days. The remaining units served as unfiltered controls. Bacterial growth was monitored by weekly cultures and, on the last storage day, by the presence of endotoxin and the formation of methemoglobin. One hundred twelve primary cultures (560 plates) were performed. Units collected in AS-1 and filtered remained sterile when initially inoculated with 50 CFU or less. Filtered units spiked with 100 CFU or less and collected in AS-3 remained sterile throughout their shelf life. All unfiltered units supported bacterial growth and the formation of endotoxin and methemoglobin. The filtration of freshly donated blood proves to limit the growth of Y. enterocolitica in red cell components.

Blood Gas Analysis↗

PubMed1983

Dibutyryl cAMP-inducible alkaline phosphatase in animal cell plasma membranes: fluorescence detection of mutant clones on polyester cloth.

We have developed a rapid screening assay that allows us to estimate the alkaline phosphatase content of mouse L-M cell colonies immobilized on polyester cloth. This permitted the identification and isolation of two mutant clones with increased constitutive alkaline phosphatase activity and six clones that fail to express this activity when treated with dibutyryl cyclic AMP. Both of the strains with increased constitutive activity have basal enzymatic activities that are 6- to 7-fold higher than the activity of the parental strain. The extents to which the cyclic nucleotide further induces alkaline phosphatase in these two strains are different, however, indicating that they represent two classes of mutants. Studies using amino acids and synthetic peptides as alkaline phosphatase inhibitors suggest that only one alkaline phosphatase isoenzyme predominates, in both the parental and the mutant cell lines, with or without induction by cyclic nucleotide. Comparison to mouse tissues indicates that our cell lines express an isozyme resembling that found in kidney and bone. The six clones that fail to express alkaline phosphatase activity when treated with dibutyryl cyclic AMP also have extremely low basal levels of the enzyme. All of these mutant strains continue to synthesize protein when treated with dibutyryl cyclic AMP and undergo growth cessation and morphological changes in the presence of this agent. Thus, the mutations all appear to affect factors specific to the expression of alkaline phosphatase activity rather than factors that affect general cellular responsiveness or permeability to dibutyryl cyclic AMP. The characterization of these strains may help elucidate mechanisms of eukaryotic membrane protein biogenesis, enzyme induction, and regulation of gene expression by cyclic nucleotides.

Alkaline Phosphatase↗

PubMed1992

Sulfated polyester interactions with the CD4 molecule and with the third variable loop domain (v3) of gp120 are chemically distinct.

Sulfated polyesters (SP) that inhibit HIV infection interact with both the gp120 binding region of CD4 molecules and with the v3 domain loop of gp120 molecules (gp120/v3) but the contributions of these interactions to the inhibition of HIV env-mediated fusion are presently unclear. In order to characterize the molecular mechanisms by which SP inhibit HIV env-mediated fusion, we studied the effect of SP treatment on env-mediated fusion of CD4+ cells driven by recombinant vaccinia virus (vPE-16) and on the binding of anti-HIV MAbs to cellular gp120 or purified, rgp120. SP were more effective than neutralizing anti-gp120/v3 MAbs in inhibiting env-mediated fusion. In addition, SP interacted with the v3 loop of gp120 to inhibit the binding of the neutralizing MAb 9284 but not the binding of 9305, a neutralizing anti-gp120/v3 MAb that binds to an adjacent epitope. Because SP are polyanions, we compared the chemical properties of the SP-gp120/v3 and SP-CD4 interactions. Whereas the ability of SP to inhibit the binding of MAb 9284 and rgp120 was relatively independent of NaCl concentrations, the ability of SP to interfere with rCD4-rgp120 binding depended on the NaCl concentration and was maximal at low NaCl concentrations. In addition, the SP-gp120 interaction was found to be reversible, in contrast to the SP-rCD4 interaction which was previously shown to be relatively irreversible at low salt. These data are consistent with the notions that the interaction of SP with CD4 is primarily electrostatic, but that the interaction of SP with gp120 has complex characteristics that implicate a role for protein conformation.

Animals↗

PubMed1979

The effect of a non-absorbable fat, sucrose polyester, on the metabolism of vitamin A by the rat.

Sucrose polyester (SPE) is a fat-like material that is not absorbed. The effect of this material on vitamin A metabolism was determined by measuring the amount of the vitamin that was stored in the liver of rats following the ingestion of a known amount of vitamin A. In one study, the vitamin A was administered as an oral dose in a vehicle consisting of various proportions of cottonseed oil and SPE. Each 1% replacement of cottonseed oil by SPE resulted in a 0.26% decrease in the amount of vitamin A found in the liver. In the second study, the vitamin A was incorporated into diets in which the fat component consisted of various proportions of cottonseed oil and SPE. When these diets were consumed for 1 week, each 1% replacement of cottonseed oil by SPE resulted in a 0.84% decrease in the storage of vitamin A by the liver. It is proposed that in the lumen of the intestine vitamin A distributes between the customary micellar phase and the unhydrolyzed oil phase of SPE. The vitamin A in this latter phase is eliminated in the feces.

Absorption↗

PubMedDate not supplied

The benefits of fluoropassivation of polyester arterial prostheses as observed in a canine model.

The effect of treating the surface of a polyester vascular prosthesis with a novel fluoropolymer before sealing the graft with gelatin has been evaluated in a canine thoracoabdominal bypass model. The healing behavior of the Fluoropassiv graft was compared with that of the Gelsoft ERS prosthesis used as control for prescheduled periods of implantation ranging from 4 hr to 6 months. Both series of explanted grafts were analyzed using macroscopic, histologic, and scanning electron microscopic observations, and by determining the prostacyclin/thromboxane A2 ratio (PGI2/TXA2) and the thrombogenicity of the luminal surface by means of labelled platelets and fibrin deposition. Chemical analysis of explanted and cleaned graft segments was performed using electron spectroscopy for chemical analysis, differential scanning calorimetry, and contact angle methods. No difference in platelet and fibrin deposition or PGI2/TXA2 secretion by the luminal surface was observed between the treated and the control grafts at any implantation period. On the other hand, pathologic investigation has revealed that, although there is no difference between the two grafts during the first month, the healing sequence of the Fluoropassiv graft appeared more complete and mature than the control graft after 3 and 6 months. Differences were observed in the extent of collagenous internal capsular development, endothelialization, and tissue penetration into the knitted structure. The presence of fluorine and a higher contact angle at the surface of all the explanted fluoropassivated grafts is believed to have been responsible for reducing the inflammatory response and enhancing the long-term healing behavior of this novel prototype device over the control gelatin sealed prosthesis.

Animals↗