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 91 records · Page 5Linked to original sources

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↗

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↗

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↗

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↗

PubMed1977

A modified technique (using polyester tape) of skin surface biopsy. Its interest for the investigation of athlete's foot.

A technical modification of skin surface biopsy has been introduced by using plastic tape instead of glass as holder, mainly to investigate mycological infections of skin folds. Among various brands of plastic sheets, a polyester film (Melinex O UCB-SIDAC) has been demonstrated as the most suitable. A direct microscopic comparison has been made between our modified technique and conventional scraping as procedures for collecting material from interdigital spaces in 30 patients with bilateral athlete's foot. It has been shown that the skin surface biopsy gives a slightly greater number of positive results (presence of dermatophytes or Candida species) than the conventional scraping technique, although the difference between both techniques is not statistically significant at the 0-05 level (0-05 less than P less than 0-10). Some advantages of the modified skin surface biopsy are emphasized.

Biopsy↗

PubMed1989

Mortality of a cohort in a polyamide-polyester factory in Lyon: a further follow up.

In 1981-2 a retrospective study was undertaken in a polyamide-polyester factory in Lyon, France, to evaluate the effect of exposure to phthalates, nickel catalysers, and other chemicals in the work environment. The present paper reports the results of the follow up of this cohort up to July 1986. A slightly increased risk of cancers, in particular of the lung (44 cases), marginally related to exposure category but not significantly related to duration of exposure was found. The excess of skin cancers noted previously has disappeared, whereas an excess of cases of bladder cancer (based on seven cases) may be noted, mainly among nylon workers. The cohort is still young, however, and a continued follow up is likely to yield important information about the potential hazards associated with the nylon and tergal polymer industry.

Chemical Industry↗

PubMed1984

Severe postural hypotension following home canoe construction from polyester resins.

On two occasions a 36-year-old man developed severe postural hypotension and neurological signs after working with a polyester resin canoe building kit in an unventilated shed. It is likely that his recurrent illness was caused by styrene intoxication. Postural hypotension secondary to styrene exposure has not previously been reported.

Hobbies↗

PubMed1988

Polyester arterial grafts impregnated with cross-linked albumin: the rate of degradation of the coating in vivo.

One of the techniques used to avoid preclotting a porous textile arterial prosthesis is to coat the graft with a layer of a bioerodible polymer. The efficacy of this treatment is dependent in part on the rate at which the polymer degrades after implantation. The focus of this study was therefore to investigate the rate of in vivo degradation of albumin-coated polyester (Dacron)-knitted vascular prostheses. Two types of cross-linked albumin were included: one using glutaraldehyde, the other using carbodiimide as the cross-linking agent. Radioactively labeled albumin-coated prostheses were implanted in the thoracic aorta and peritoneal cavity of dogs, and their rates of biodegradation in vivo were monitored over a 4-week period. The rate of biodegradation was found to depend upon the site of implantation. It occurred more rapidly in the peritoneal cavity where less than 20% of the albumin coating remained after 4 weeks in vivo in comparison to the approximately 30% in the thoracic aorta. The nature and intensity of the cellular response appeared to be related to the cytotoxic potential of the cross-linking agent. Glutaraldehyde induced an inflammatory response and a delay in healing, whereas carbodiimide caused only a mild tissue reaction.

Animals↗

PubMed1988

Characteristics of polyester arterial grafts coated with albumin: the role and importance of the cross-linking chemicals.

Preclotting is mandatory prior to implanting a knitted polyester arterial graft, unless the structure is made impermeable to blood by coating with a bioerodible material. Before achieving wide-spread clinical acceptance, the technique of impregnating with cross-linked albumin must be optimized in order to develop a graft that is immediately implantable, easy to handle and suture and has improved healing characteristics. The choice of the chemical to cross-link the albumin is of paramount importance. In this study two alternative candidates have been evaluated by using a series of tests to measure the physical properties, the morphology and the cytocompatibility of albumin-coated grafts. A carbodiimide cross-linking agent appears more promising than glutaraldehyde, since it is equally effective in producing a blood impermeable prosthesis, yet presents improved biocompatibility and provokes a less intense inflammatory response from the host.

Aldehydes↗

PubMed1988

Aliphatic polyesters and cellulose-based polymers for controlled release applications.

The general technologies for fabricating drug delivery systems are briefly discussed in the present review. Furthermore, two types of commonly used polymers, biodegradable aliphatic polyesters for parenteral administration and cellulose-based polymers for oral uses, are presented by means of selected examples of their properties and applications to control drug release.

Cellulose↗

PubMed1985

Strength of carbon and polyester fibre tendon replacements. Variation after operation in rabbits.

The calcaneal tendons of rabbits were excised and either replaced with a carbon or polyester fibre implant, or left as controls. The strength of the neotendons and their mode of failure under tension were examined at intervals up to six months after operation. Return to near normal strength took six months to develop, suggesting that patients having ligament or tendon reconstructions should not resume normal activity for several months. Carbon fibre-based neotendons showed progressive elongation which, unless avoided by a sufficient period of immobilisation, would affect the functional result.

Animals↗