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PubMedDate not supplied

Comparison of adhesive polyurethane membrane and polypropylene sutures for closure of skin incisions in cats.

Paired skin incisions were made on each side of four cats and closed with either interrupted polypropylene sutures or adhesive polyurethane membrane. The healing of these wounds was compared by gross appearance, break strength determination, and histologic examination. The adhesive polyurethane membranes were quicker and easier to apply, producing a more uniform closure than sutures both clinically and histologically. They adhered strongly to the skin, supporting more wound length than sutures for the first 7 days. There were no differences in break strength between closure techniques. Histologically, the wounds closed with adhesive polyurethane membrane were characterized by a milder inflammatory reaction and greater vascular infiltration than sutured wounds, especially early in the healing period.

Animals↗

PubMed1985

Bipolar tined polyurethane ventricular lead: a four-year experience.

With the advent of polyurethane as an insulating material for permanent pacemaker leads, concern has arisen over the integrity and long-term durability of polyurethane-insulated pacing leads. Specific concern has arisen over particular bipolar tined polyurethane ventricular leads. We have assessed our 4-year experience with this lead. This experience involves two groups of patients, those with leads manufactured before a certain date and those with leads manufactured at a later date. In the first group (judged to be at increased risk) the failure rate was 8.8%, and in the second group (judged not to be at increased risk) the rate was 3.9%. Lead failure occurred at an average of 17.5 months in the first group. Adequate follow-up on the second group is not available to determine whether or not the failure rate may eventually be as high as that in the early group. Actuarial analysis suggests that survivorship free of lead failure is probably not significantly different in the two groups. This experience points out the need for determining lead failure rates, identifying optimal lead design and configuration, and establishing a lead registry or mechanism by which the integrity of various pacing leads can be evaluated.

Electrocardiography↗

PubMed1991

Experimental study about removal of the implanted tined polyurethane ventricular lead by radiofrequency waves through the lead.

Polyurethane pacemaker leads are widely used nowadays. However, only a few studies have been done to investigate the fixation mechanism of polyurethane leads. To elucidate how pacemaker leads are fixed at the early phase after implantation, polyurethane-insulated tined ventricular leads were implanted in seven mongrel dogs. One to 4 months later, tips of the leads were anchored among the trabeculae and the distal part of the leads were encapsulated by whitish fibrous tissue. It was found that not organized thrombi, but cell reaction with various stages of inflammatory cells was responsible for forming the fibrous tissue. We attempted to remove the lead by delivering radiofrequency wave through the lead. However, no lead could be removed.

Animals↗

PubMed1992

Is polyurethane lead insulation still controversial?

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high-performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.) electrode, polyurethane electrodes have a 100% reliability at 84 months, which is similar to silastic electrodes.

Databases, Factual↗

PubMed1996

The combined effects of plasma and hydrogel coating on adhesion of Staphylococcus epidermidis and Staphylococcus aureus to polyurethane catheters.

The adhesion of three Staphylococcus epidermidis and three S aureus clinical isolates, to uncoated and hydrogel-coated polyurethane catheters was tested, following pretreatment of catheters with human plasma. Plasma significantly decreased the adhesion of S. epidermidis strains to uncoated polyurethane catheters, but had no significant effect on the adhesion to hydrogel-coated catheters. The influence of plasma on adhesion of S. aureus strains to catheters was strain dependent. Plasma significantly increased the adhesion of one strain (SA6) to uncoated catheters. For two other strains (SA3 and SA14) plasma produced no clear effect on their adhesion to uncoated catheters; adhesion values for each strain showed either a small but significant increase or a replicate-dependent increase or decrease. However, plasma significantly increased the adhesion of all S. aureus strains to hydrogel-coated polyurethane catheters. Overall, with the exception of one batch culture of S. epidermidis strain SE3 tested, attachment to plasma-treated hydrogel coated catheters was statistically significantly lower, by up to 85%, than attachment to plasma-treated uncoated catheters for both S. epidermidis and S. aureus.

Adsorption↗

PubMed1999

Evaluation of a polyurethane jugular catheter in cats placed using a modified Seldinger technique.

OBJECTIVE: To describe and evaluate the placement of a new design of polyurethane jugular catheter in cats using a modification of the technique of Seldinger. The maintenance and use of these catheters for repeated blood sampling over several days in healthy and diabetic cats is reported. PROCEDURE: Thirty polyurethane jugular catheters were placed in 10 clinically healthy cats and 10 cats with diabetes mellitus using the modified Seldinger technique. Catheters were placed while the cats were under general anaesthesia. RESULTS: The catheters remained in place for a range of 2 to 14 days (median 5 days) with no major complications. In all cats patency of the catheters was maintained until removal. All cats examined had patent jugular veins when assessed 4 or more weeks after the catheters were removed. CONCLUSIONS: These polyurethane jugular catheters, when placed by a modified Seldinger technique, are effective and safe in cats, and jugular patency returns after the catheters are removed.

Animals↗

PubMed1989

Degradation of pentachlorophenol by polyurethane-immobilized Flavobacterium cells.

Polyurethane-immobilized Flavobacterium cells (ATCC 39723) degraded pentachlorophenol (PCP) at initial concentrations as high as 300 mg liter-1. The reversible binding of PCP to the polyurethane was shown to be important in the protection of the cells from inhibition of PCP degradation. The degradation activity of the bacteria was monitored for 150 days in semicontinuous batch reactors. The degradation rate dropped by about 0.6% per day. PCP was degraded in a continuous-culture bioreactor at a rate of 3.5 to 4 mg g of foam-1 day-1 for 25 days. Electron micrographs of the polyurethane suggested that the cells were entrapped within 50- to 500-microns-diameter pockets in the foam.

Biodegradation, Environmental↗

PubMed1997

Benign and malignant esophageal strictures: treatment with a polyurethane-covered retrievable expandable metallic stent.

PURPOSE: To evaluate the clinical effectiveness of a polyurethane-covered, retrievable, self-expandable metallic stent and hook catheter in the treatment of esophageal strictures. MATERIALS AND METHODS: Stents were constructed of 0.4-mm stainless steel wire in a cylindric zig-zag configuration of six to nine bends. Four to eight stents were connected in tandem by dipping in a polyurethane solution. A nylon loop was hooked inside to each bend of the proximal portion of the stent and strung with a thread. Under fluoroscopic guidance, 22 stents were placed in 16 patients with a malignant stricture and five patients with a benign stricture. The stent was removed with a hook catheter 2 months after placement in patients with a benign stricture and when complications occurred in patients with a malignant stricture. All patients had dysphagia with ingestion of soft foods or liquids. RESULTS: Stent placement was technically successful and well tolerated in 20 patients. In one patient, the stent was misplaced but relocated successfully. After stent placement, all patients were able to ingest solid and/or soft foods without dysphagia. After stent removal, strictures showed improvement but recurred in two patients. CONCLUSION: Use of polyurethane-covered, retrievable expandable stents seems to be a feasible and effective method of treatment of benign and malignant esophageal strictures.

Adolescent↗

PubMed2000

Treatment and pain relief of ulcerative hemangiomas with a polyurethane film.

BACKGROUND: Hemangiomas are the most common tumors occurring in young children. The most common complication in the growing phase of hemangioma is ulceration. AIM AND METHOD: We report healing, pain relief and evolutive effects of a polyurethane film in 8 cases with ulcerative hemangiomas. RESULTS: In all 8 infants, prompt pain relief and healing within 1-2 months were observed. An increased regression was also noted within 2-4 months, when the hemangiomas were in the normal proliferative phase. CONCLUSION: As far as the authors know, there is no explanation for the effectiveness of polyurethane film. Explanations could be the occlusive effects of the film inhibiting proliferation or the decrease in blood flow. As primary initial therapeutic approach in ulcerative hemangiomas, we advocate the application of a polyurethane film. This therapy is painless and suitable for children.

Female↗

PubMed1987

Acute thrombogenicity of a compliant polyurethane urea graft compared with polytetrafluoroethylene: an experimental study in sheep.

The acute thrombogenicity of a new polyurethane urea graft has been compared with polytetrafluoroethylene (PTFE) grafts using labelled homologous platelets in the carotid arteries of sheep in a low-flow model. There was no difference in patency. Thrombus weight and thrombus free surface were the same in both types of graft after 4 h. The accumulation of homologous 32P platelets was measured at the 2 anastomoses and at a midgraft position. At no point was there any statistically significant difference between the 2 grafts, but the activity was always somewhat higher in the polyurethane grafts. Although more compliant, in this study polyurethane urea grafts behaved much like PTFE ones.

Animals↗

PubMed1976

Scanning electron microscopy of surface irregularities and thrombogenesis of polyurethane and polyethylene coronary catheters.

Following routine coronary arteriography, surface irregularities and thrombogenesis of the inner and outer wall of six Ducor polyurethane and six RPX polyethylene coronary catheters were studied by scanning electron microscopy. Polyurethane catheters had rough and highly irregular external and internal surfaces. All catheters showed adherent thrombi on their external surface. The internal surface of three catheters showed evidence of thrombosis. Polyethylene differed from polyurethane in several respects. Although the external surface had an irregular and wavelike appearance, the internal surface was smooth and regular. Two polyethylene catheters showed thrombi on their external surface. The internal surface of one catheter showed single platelets in one area. These results confirm recent reports showing that internal and external surface irregularities play a major role in the initiation of thrombosis in and on intravascular catheters. They stress the need for high quality catheter materials with smooth and regular surfaces in the prevention of thromboembolic complications from coronary arteriography.

Adult↗

PubMed2002

Novel dendrimer based polyurethanes for PEO incorporation.

A series of segmented polyurethanes based on methylene diisocyanate/poly (tetramethylene oxide) and chain extended with either ethylene diamine or butane diol in combination with a generation 2 polypropylenimine octaamine dendrimer were synthesized. For polymer synthesis, the dendrimers were protected with either t-boc or Fmoc groups and were incorporated into the polyurethane microstructure to permit further functionalization with biologically active groups. Following deprotection, the dendrimers were reacted with succinimidyl propionate polyethylene oxide (SPA-PEO) to improve the protein resistance of the polymers and to examine the potential of this technique for polymer functionalization. Different synthesis techniques were examined to optimize the incorporation of the PEO into the polymer microstructure. Incorporation of the dendrimers and the PEO were confirmed by NMR and FTIR. Gel permeation chromatography was used to examine the molecular weights of the various polyurethanes. The dendrimer incorporated polymers had significantly lower molecular weights than the ED or BDO chain extended controls, likely due to lower reactivity of the dendrimers as a result of steric factors. Following PEO reaction, the molecular weights of the resultant polymers were consistent with the levels of PEO incorporation noted by comparison of peak intensities in the NMR spectra. Due to the highly hydrophilic nature of the PEO, some migration to the polymer surface was expected. Water contact angles and XPS, used to characterize the surfaces, suggest that there was some PEO enrichment at the surface of the polymers. Adsorption of radiolabeled fibrinogen to the polymer surfaces was decreased by a factor of approximately 40% in some of the PEO incorporated polymers. There were also differences in the patterns of plasma protein adsorption on the various surfaces as evaluated by SDS PAGE and immunoblotting. Therefore, the use of dendrimers in biomaterials for incorporation of a large number of functional groups seems to be promising.

Biocompatible Materials↗

PubMed2003

Platelet adhesion onto segmented polyurethane surfaces modified by carboxybetaine.

Polyurethanes are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for more demanding applications. Surface modification is an effective way to improve the hemocompatibility for biomaterials. The purpose of present study was to synthesize a novel nonthrombogenic biomaterial by modifying the surface of polyurethane with Zwitterions of carboxybetaine monomer. The films of polyurethane were grafted with two kinds of carboxybetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-FT-IR spectra: a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of N,N-dimethylethylethanolamine (DMEA) or 4-dimethylamino-1-butanol (DMBA) was allowed to react in toluene with isocyanate groups bound on surface. In the third step, carboxybetaines were formed in the surface through the ring-opening reaction between tertiary amine of DMEA or DMBA and beta-propiolactone (PL). It was characterized by ATR-FT-IR and XPS that the grafted surfaces were composed of carboxybetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. Platelet adhesion tests showed that films grafted carboxybetaine have good blood compatibility, as featured by the low platelet adhesion.

Betaine↗

PubMed2004

Properties of phospholipid monolayer deposited on a fluorinated polyurethane.

A simple procedure for surface modification of polyurethane by the Langmuir-Blodgett (LB) method using the amphiphile 1,2-distearoyl-sn-glycero-3-phosphocholine dihydrate (DSPC) was developed. The polyurethane containing the fluorinated moiety was prepared via the perfluoro-containing chain extender 2,2,3,3-tetrafluoro-1,4-butanediol. The fluorinated polyurethane (FPU) films were prepared by spin coating and dipping methods. The spin-coated FPU films exhibited hydrophobic characteristic and, thus, enhanced the transferability of DSPC. Held at constant pressure of 45 mN/m, the DSPC monolayer was transferred successfully to FPU films with a near-unity transfer ratio. The in vitro platelet adhesion assay revealed that the FPU modified with DSPC monolayer was more platelet compatible than the unmodified FPU substrates with no pseudopods and flattening of adherent platelets as well as lower platelet adhesion density. Moreover, the DSPC monolayer remained intact after platelet adhesion testing. In addition, the platelet compatibility of the unmodified FPU was affected by the film preparation methods. This might be attributed to the distinctive surface micromorphology formed. This simple DSPC deposition scheme by a LB technique would be very useful to further enhance the platelet compatibility of hydrophobic substrate and can be utilized for biomedical application in which the flow shear rate is not too high.

Biocompatible Materials↗

PubMed1989

Synthesis and non-thrombogenicity of polyurethanes with poly(oxyethylene) side chains in soft segment regions.

Epoxidized polybutadiene-urethanes were synthesized and grafted with poly(oxyethylene)s. The non-thrombogenicity of the graft polyurethanes was investigated in relation to the content of poly(oxyethylene). The grafting of poly(oxyethylene) to polyurethane suppressed adsorption and denaturation of plasma proteins and platelet adhesion. It was also found that there exists an optimum content of poly(oxyethylene) for the graft polyurethane to attain the highest non-thrombogenicity.

Adsorption↗

PubMed1994

Protein adsorption, lymphocyte adhesion and platelet adhesion/activation on polyurethane ureas is related to hard segment content and composition.

Segmented polyurethane ureas with different hard segment content and composition were synthesized using 4,4'-diphenylmethane diisocyanate and polytetramethylene glycols. Using polyols with different molecular weights, it was possible to synthesize polyurethane ureas with either: (i) a constant ratio of urethane to urea bonds; (ii) a constant urethane content; or (iii) a constant urea content. Bulk properties were assessed by dynamic mechanical analysis. Surface properties were estimated by contact angle measurements and streaming potential measurements. Haemocompatibility was evaluated in vitro by measuring the adsorption of human serum albumin (HSA) and fibrinogen (Fg), the adhesion of human peripheral blood lymphocytes (PBL), and the presence of activated platelets on the biomaterial surfaces. Enzyme immuno assays (EIA) have been specially developed for this purpose for the detection of antibody-recognizable plasma proteins and platelet surface membrane proteins. No simple correlation between chemical structure of the polymers and surface properties was found. Parameters of haemocompatibility correlated more closely with hard segment content and chemical composition than with the surface characteristics of the polymers. Adsorption of plasma proteins, adhesion of lymphocytes and the adhesion/activation of platelets were found to increase with increasing hard segment content of the polyurethane ureas. However, the monoclonal-antibody recognisable fibrinogen and the platelet activation were nearly constant with increasing hard segment content, if the urea content was kept constant.

Adsorption↗

PubMed1999

Langmuir-Blodgett films of antibodies as mediators of endothelial cell adhesion on polyurethanes.

The effect of endothelial cell adhesion on polyurethanes coated with Langmuir-Blodgett antibody films has been examined. The films were cross-linked with glutaraldehyde with the aim of providing a densely packed and covalently linked two-dimensional antibody network on the polyurethane surfaces. Our results demonstrate that although neither of the two polyurethanes examined were entirely suited to cellular adhesion, Langmuir-Blodgett antibody films, cross-linked with small concentrations of glutaraldehyde, are more suitable for endothelial cell adhesion than surfaces free of antibody.

Antibodies, Monoclonal↗

PubMed1999

Commercial polyurethanes: the potential influence of auxiliary chemicals on the biodegradation process.

This investigation elucidates some aspects of auxiliary chemicals on the biodegradation of two commercial polyurethanes (Pellethane and Corethane). The materials were incubated for 28 days with cholesterol esterase and/or with phosphatidylcholine. Extraction studies were carried out on the two materials, using different solvents, chosen on the basis of solvent polarity. FT-IR spectra for the extracted materials indicated the presence of poly(methylene)n oxide moities, silicone oil, bis-ethylene-stearamide, aromatic moities, and alkyd-urea compounds in Pellethane. Corethane materials were shown to contain some fatty acids, hydrocarbon waxes, ester-based species, and chlorinated compounds. Analysis of incubation solutions by high performance liquid chromatography failed to isolate methylene dianiline (MDA) or any of its derivatives from the various polymer incubation solutions. However, a methanol extract of Corethane samples that were incubated for 28 days in cholesterol esterase did show the presence of MDA. The absence of MDA in the Pellethane methanol extracted samples may reflect the differences in surface additives found for this material versus the Corethane. FT-IR/ATR analysis of polymer surfaces exposed to cholesterol esterase/phospholipids mixture showed that there was an increase in the uptake of phospholipids over samples that were incubated in phospholipid dispersion alone. The results of this study show that some of the auxiliary chemicals found in commercial polyurethanes may hinder the specific release of hydrolytic degradation products and delay polymer degradation. However, it should be recognized that the surface layer containing these compounds is susceptible to change following the interaction between the polyurethane-based devices and elements of the host environment (i.e. lipids, enzymes, etc.). Hence, recognition and identification of these changes will ultimately be important in assessing a commercial polymer's blood compatibility characteristics.

Biodegradation, Environmental↗