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PubMed2003

Clinical breakage, slippage and acceptability of a new commercial polyurethane condom: a randomized, controlled study.

Although latex remains the primary material for male condoms, a number of condoms made from synthetic materials have appeared in commercial markets in recent years. Published data on the safety and efficacy of these condoms is still limited, but nevertheless synthetic condoms do offer the user a wider choice and may encourage greater use of condoms for contraception and sexual transmitted infection prophylaxis. This paper reports on a study carried out in the Paris region of France on a new, commercial polyurethane condom marketed in Japan as Sagami Original and in Europe as Protex Original. A standard latex condom complying with the European standard for condoms (EN 600:1996) from the same manufacturer was used as the control in the study. The clinical breakage rate for the polyurethane condom was 0.6% (95% confidence interval 0.2-1.4%) compared to 1.3% (95% confidence interval 0.6-2.2%) for the latex condom. The difference was not statistically significant (chi(2) = 1.9, p = 0.168). Clinically significant slippage (complete slippage of the condom off the penis) was 1.1% (95% confidence interval 0.5-1.9%) for the polyurethane condom, compared to 0.5% (95% confidence interval 0.2-1.2%) for the latex; a difference that again was not statistically significant (chi(2) = 1.783, p = 0.182). The polyurethane condom was therefore equivalent to the latex condom in terms of clinical failure rate.

Adult↗

PubMed1995

Comparison of transverse strength and dimensional variations between die stone, die epoxy resin, and die polyurethane resin.

This study compared transverse strength and dimensional variations of die stone, epoxy resin, and polyurethane resin. The polyurethane resin was tested unfilled, then filled with 20%, 40%, and 60% silica, by weight. Transverse strength was evaluated for five test strips for each material, and an original calibration plate technique closely simulating intraoral conditions was introduced to evaluate dimensional accuracy. Two series of five measurements for dimensional variations were recorded on each test strip. The first series was 15 minutes after removal from mold and the second series of 5 minutes a week later. The results were computed with a parametric ANOVA and Scheffe's test at 95% confidence level (p < or = 0.05). These results confirmed that die stone recorded the least dimensional change but was rigid and brittle, whereas epoxy resin and polyurethane resin had suitable mechanical properties including greater dimensional variations. Incorporating silica filler in polyurethane resins also reduced their transverse strength and sponsored minimal dimensional variations.

Analysis of Variance↗

PubMed2001

Studies on the effect of surface properties on the biocompatibility of polyurethane membranes.

To study the effect of surface properties on the biocompatibility of biomaterials based on the same material, polyurethane membranes with different surface properties were prepared. Myoblast culture and interleukin-1 (IL-1) generation in an air pouch model and in vitro monocyte culture were used to examine biocompatibility of different polyurethane membranes. Polyurethane membranes were found to exhibit significant differences depending on their surface properties prepared by different fabrication processes. When myoblasts were cultured on polyurethane surfaces, the smooth and hydrophobic membrane (F1), prepared by the solvent evaporation process, showed the greatest inhibition of myoblast adhesion compared with other porous and hydrophilic membranes (F2, F3 and F4), prepared by immersing the polymer solution into a precipitation bath. In contrast, IL-1 generation by monocytes/macrophages on the membrane F1 was more severe than those on the porous and hydrophilic membranes. Based on our results, the interaction of biomaterials with various cells is discussed.

Adult↗

PubMed2001

Synthesis and characterization of non-leaching biocidal polyurethanes.

The biocidal activities of a series of quaternized polyurethanes were examined against Staphylococcus aureus and Escherichia coli. The percentage of dead cells on a surface was found to depend on the alkyl halide used for quaternization, the concentration of quaternized moieties in the polyurethane, the gram-type of the microorganism, and the contact time of the organism with the surface. N,N-bis(2-hydroxyethyl)isonicotinamide (BIN) was incorporated as the chain extender in a series of poly(tetramethylene oxide)-based polyurethane block copolymers. Three families of materials were synthesized that contained increasing hard segment fractions and therefore increasing concentrations of BIN. The pyridine ring in BIN was quaternized with a variety of alkyl halides to form cationic polyurethanes that possessed biocidal activity. The effect of quaternization on material properties was examined with tensile testing, water absorption analysis, and contact angle measurements. The antibacterial action of the polymers was investigated with zone of inhibition experiments and fluorescence microscopy, which was established as a reliable technique to determine the viability of organisms attached to a polymer surface.

Adsorption↗

PubMed2003

Biological efficacy of electroless-deposited silver on plasma activated polyurethane.

Silver coating of catheters has been shown to have inhibitory effects on bacterial growth and adhesion to catheter surfaces. In this study, plasma-modification was used to enhance the adhesion of an electroless silver coating on polyurethane. Both the antibacterial and antiadhesive properties of these coatings were investigated. Bacterial growth was inhibited in cultures exposed to silver-treated polyurethane compared to unmodified polyurethane. Higher growth inhibition was observed for polyurethane surfaces with lower silver coverage. Bacterial adhesion was completely inhibited on all silver-coated surfaces.

Anti-Bacterial Agents↗

PubMed2003

A novel solvent system for blending of polyurethane and heparin.

To improve the blood-compatibility of polyurethane, the co-solvent of tetrahydrofuran and water, a new solvent system for blending polyurethane and heparin, was proposed. After solvent casting, heparin was blended in a polyurethane film. The ATR-FTIR was used to analyze the surface chemical element and the contact angle was measured to investigate the hydrophilicity of the surface of the PUs. As the amount of heparin increased, the surface hydrophilicity was increased and all the clot times exceeded the measurement limit of the clot detection instrument when the heparin loaded on the polyurethane films was 3%, 5% and 7%. After the films were immersed in the phosphate buffered saline for 30 days, the activated partial thromboplastin time and thrombin time still exceeded the measurement limit of the clot detection instrument.

Biocompatible Materials↗

PubMed1997

Physical property analysis and bacterial adhesion on a series of phosphonated polyurethanes.

Glycerophosphorylcholine (GPC) was incorporated as the chain extender in a series of poly(tetramethylene oxide)-based polyurethane block copolymers. In order to determine the feasibility of use of these polyurethanes in biomedical devices, the effects of GPC incorporation on physical properties were studied. The effect of soft-segment molecular weight was also investigated. Biocompatibility of these materials was studied with regard to bacterial adhesion and protein deposition. Tensile testing showed that as GPC content increased, elongation at break decreased, while Young's modulus increased. Differential scanning calorimetry (DSC) results showed slightly decreased glass transition temperatures (Tgs) with increasing GPC content, indicating increased phase separation. Dynamic mechanical analysis (DMA) confirmed the decrease in Tg and the increase in rubbery plateau modulus with increasing GPC content. Water absorption was also increased with GPC content. Decreased bacterial adhesion was found on the GPC-containing materials compared to other functionalized polyurethanes. These experiments were carried out in a radial flow chamber utilizing automated video microscopy. Bacterial attachment was found to be lower on the GPC-containing polyurethanes both in the absence of and after pre-adsorption with plasma proteins.

Bacterial Adhesion↗

PubMed1997

Controlled release of antibiotics from biomedical polyurethanes: morphological and structural features.

Polymer-associated infections are of increasing importance. Antistaphylococcal antimicrobial substances (ciprofloxacin, gentamycin, fosfomycin, flucloxacillin) were incorporated into polyurethanes by the solvent casting technique. Drug release rates, bacterial colonization and morphological features were evaluated to predict and understand the antimicrobial activity of these delivery systems. Drug release characteristics were investigated by standard bioassay and high-performance liquid chromatography (HPLC), and the physico-chemical mechanisms of the delivery were discussed. Ciprofloxacin hydrochloride showed a fast initial release rate, whereas gentamicin-base was characterized by a more continuous release type of behaviour. Bacterial colonization to the antibiotic-loaded polyurethanes was inhibited effectively by preparations showing a slower but more sustained antimicrobial delivery. Polyurethane-antibiotic combinations were most homogeneous for gentamicin-base and flucloxacillin as shown by scanning electron microscopy (SEM). In polymers loaded with fosfomycin and ciprofloxacin a granular structure of the crystallized drug embedded in the polyurethane matrix could be demonstrated. Physico-chemical similarity of the polymeric material and the antibiotics is important for the homogeneity of polymer-antibiotic combinations. High homogeneity is required for a sustained and prolonged release over time and effective inhibition of bacterial colonization.

Anti-Bacterial Agents↗

PubMedDate not supplied

Neutrophil adhesion on phosphorylcholine-containing polyurethanes.

Polyurethanes have been synthesized using glycerophosphorylcholine (GPC) as a chain extender. By altering the ratio of GPC to butanediol (BD), a series of polymers was obtained composed of different contents of phosphorylcholine. Bulk and surface characterization of the polymers was carried out. Differential scanning calorimetry and dynamic mechanical analysis showed that the polymer with the highest phosphorylcholine content (PU-GPC-20) had the lowest soft segment Tg and the highest tensile strength and Young's modulus among the polymers studied. This is due to the high degree of microphase separation in PU-GPC-20 as a result of by ionic aggregation and hydrogen bonding from the zwitterionic phosphorylcholine moiety. PU-GPC-20 contained approximately 20 wt%, of glycerophosphorylcholine. Dynamic contact angle analysis showed that these polymers, especially the ones with high phosphorylcholine content, rearranged themselves to minimize their interfacial tension upon contacting an aqueous environment. Under shear rates of from 20 to 120 s(-1), neutrophils did not adhere to PU-GPC-20. Under similar conditions neutrophil adhesion was observed only at 20 s(-1) on PU-GPC-10, PU-GPC-5 and on the control polyurethane (PU-base). Cell spreading was observed on the control polyurethane but not on any of the other surfaces. The incorporation of phosphorylcholine into the polyurethane backbone effectively reduced neutrophil adhesion and thus potentially could result in lower inflammatory and foreign body responses.

Absorption↗

PubMed2000

Improved cell adhesion by plasma-induced grafting of L-lactide onto polyurethane surface.

Lactide-grafted polyurethanes were prepared by exposing the polyurethane films to argon plasma discharge, followed by grafting L-lactide onto the plasma-treated surface. The modified surfaces were characterized by measuring the static contact angle and by electron spectroscopy for chemical analysis (ESCA). The water contact angle of polyurethanes was decreased by L-lactide grafting, indicating hydrophilicity of the modified surface. Grafting also increased the O/C atomic ratio and C(C=O)/Ctotal percentage on the surfaces as detected by ESCA. The grafted surfaces showed enhanced attachment and growth in both 3T3 fibroblast and human umbilical vein endothelial cell culture tests. Platelet adhesion to the modified surfaces was also reduced in vitro. L-Lactide monomers grafted onto polyurethane substrates could therefore be useful in facilitating endothelial cell seeding process in small vascular graft applications.

3T3 Cells↗

PubMed2000

Polyurethane: material for the next generation of heart valve prostheses?

OBJECTIVES: The prospects for a durable, athrombogenic, synthetic, flexible leaflet heart valve are enhanced by the recent availability of novel, biostable polyurethanes. As a forerunner to evaluation of such biostable valves, a prototype trileaflet polyurethane valve (utilising conventional material of known in vitro behaviour) was compared with mechanical and bioprosthetic valves for assessment of in vivo function, durability, thromboembolic potential and calcification. METHODS: Polyurethane (PU), ATS bileaflet mechanical, and Carpentier-Edwards porcine (CE) valves were implanted in the mitral position of growing sheep. Counting of high-intensity transient signals (HITS) in the carotid arteries, echocardiographic assessment of valve function, and examination of blood smears for platelet aggregates were undertaken during the 6-month anticoagulant-free survival period. Valve structure and hydrodynamic performance were assessed following elective sacrifice. RESULTS: Twenty-eight animals survived surgery (ten ATS; ten CE; eight PU). At 6 months the mechanical valve group (n=9) showed highest numbers of HITS (mean 40/h, P=0.01 cf. porcine valves), and platelet aggregates (mean 62.22/standard field), but no thromboembolism, and no structural or functional change. The bioprosthetic group (n=6) showed low HITS (1/h) and fewer aggregates (41.67, P=1.00, not significant), calcification and severe pannus overgrowth with progressive stenosis. The PU valves (n=8) showed a small degree of fibrin attachment to leaflet surfaces, no pannus overgrowth, little change in haemodynamic performance, low levels of HITS (5/h) and platelet aggregates (17.50, P<0.01 cf. mechanical valves, P=0.23 cf. porcine valves), and no evidence of thromboembolism. CONCLUSIONS: In the absence of valve-related death and morbidity, and retention of good haemodynamic function, the PU valve was superior to the bioprosthesis; lower HITS and aggregate counts in the PU valve imply lower thrombogenicity compared with the mechanical valve. A biostable polyurethane valve could offer clinical advantage with the promise of improved durability (cf. bioprostheses) and low thrombogenicity (cf. mechanical valves).

Analysis of Variance↗

PubMedDate not supplied

Structure and properties of triolein-based polyurethane networks.

Polyurethane networks based on vegetable oils have very heterogeneous composition, and it is difficult to find a close correlation between their structure and properties. To establish benchmark structure-properties relationships, we have prepared model polyurethane networks based on triolein and 4,4'-diphenylmethane diisocyanate (MDI). Cross-linking in the middle of fatty acid chains leaves significant parts of the triglyceride as dangling chains. To examine their effect on properties, we have synthesized another polyurethane network using triolein without dangling chains (removed by metathesis). The structure of polyols was studied in detail since it affects the structure of polyurethane networks. The network structure was analyzed from swelling and mechanical measurements and by applying network and rubber elasticity theories. The cross-linking density in both networks was found to be close to theoretical. The triolein-based model network displayed modulus (around 6 MPa), tensile strength (8.7 MPa), and elongation at break (136%), characteristic of hard rubbers. Glass transition temperatures of the networks from triolein and its metathesis analogue were 25 and 31.5 degrees C, respectively.

Molecular Structure↗

PubMedDate not supplied

Preparation of porous polyurethane particles and their use in enzyme immobilization.

Porous polyurethane particles were prepared as follows: (1) Two low molecular weight polymers, namely, poly[methylene(polyphenyl isocyanate)] and poly(propylene glycol) were mixed with stirring at room temperature and allowed to react. (2) The reacted mixture was dispersed with stirring in mineral oil containing small amounts of water, the catalyst dibutyltin dilaurate, and CaCO3 powder. In the presence of the catalyst, the reaction between the two polymers proceeded to completion. Small particles of polyurethane are thus formed which contain mineral oil and CaCO3 as porogens. The particles obtained, separated by filtration, were treated with a solution of HCl in order to generate additional pores, extracted with benzene to eliminate the mineral oil present in the pores, and finally subjected to drying and sieving. The particles were investigated by scanning electron microscopy (SEM), infrared (IR) spectroscopy, and specific surface area measurements. Lipase from Candida rugosa was immobilized by adsorption on the porous polyurethane particles and cross-linked with glutaraldehyde to enhance the stability of the immobilization. The biocatalytic particles were used for the hydrolysis of triacylglycerides. The high activity of the immobilized enzyme, which per enzyme molecule can be higher than that of the free enzyme, reveals that the porous polyurethane particles constitute excellent supports for lipase.

Emulsions↗

PubMed1999

Permeability of nitrile rubber, latex, polyurethane, and neoprene gloves to 18 antineoplastic drugs.

The permeability of four glove materials to various antineoplastic drugs was studied. Eighteen antineoplastic drugs posing potential health hazards to handlers were prepared at the highest concentrations normally encountered by hospital personnel. Four glove materials-nitrile rubber, latex, polyurethane, and neoprene-were exposed to the drugs for 30, 60, 90, and 120 minutes. Glove thickness was measured with an electronic digital caliper. Random samples of material were selected from the glove fingertips, and triplicate samples were tested for each drug at each interval. For a majority of the drugs, a bacterial mutagenicity assay was used to measure the amount of drug (if any) that permeated the material. High-performance liquid chromatography was used for drugs not tested with the bacterial assay. The nitrile gloves were the thinnest (0.12 mm), and the latex gloves were the thickest (0.18 mm). The four materials were generally impermeable to each drug. One sample of the nitrile gloves appeared to have a defect, allowing >5% of the drug solution to pass through at 30 minutes. One sample each of the latex, polyurethane, and neoprene gloves demonstrated minimal permeability (< or =1%): One latex glove sample was permeated by carmustine, and paclitaxel permeated one sample each of the polyurethane and neoprene materials. Nitrile rubber, latex, polyurethane, and neoprene gloves were impermeable to 18 antineoplastic drugs in most, but not all, cases.

Antineoplastic Agents↗

PubMed1994

Epicardial administration of ibutilide from polyurethane matrices: effects on defibrillation threshold and electrophysiologic parameters.

Polymer-drug composites known as controlled-release systems have been used effectively to prevent and treat ventricular arrhythmias in experimental studies. We wished to determine if such systems could be useful in reducing ventricular defibrillation energy requirements in an acute canine model without producing undesirable electrophysiologic effects. Ibutilide-polyurethane monolithic controlled-release matrices were formulated with ibutilide fumarate and a polyether polyurethane. In vitro drug-release characteristics of the drug matrices were determined. Two formulations were investigated: (a) 20% ibutilide by weight in polyether polyurethane, and (b) 4% ibutilide/16% dimethyl tartrate in polyurethane. Based on in vitro release studies, 20% ibutilide matrices (25 mg) would provide a 25-kg dog with a dose of 25 micrograms/kg ibutilide in a 2-h acute experimental period, and 4% ibutilide matrices were estimated to provide 3.5 micrograms/kg. We used each of these types of matrices in acute open-chest dog studies to assess electrophysiologic effects and the influence of epicardial controlled-release ibutilide, as compared with intravenous (i.v.) administration, on defibrillation energy thresholds (DFTs), using epicardial defibrillation electrodes. In monophasic defibrillation waveform studies, 20% matrices significantly decreased DFT as compared with a predrug control period [2.54 +/- 0.59 (mean +/- SEM) vs. 7.23 +/- 1.73 J, respectively, p = 0.038]. Administration of the same dose i.v. did not cause significant reduction in energy requirement. With a biphasic defibrillation waveform, 4% ibutilide matrices significantly decreased DFT as compared with control (2.53 +/- 0.34 vs. 3.42 +/- 0.46 J, respectively, p = 0.003). Administration of an equivalent i.v. dose did not cause a significant reduction in biphasic energy requirement. Both types of controlled-release systems significantly prolonged refractoriness and conduction times of ventricular extrastimuli as compared with vehicle. No proarrhythmia events were observed. Epicardial polymeric controlled-release ibutilide significantly prolonged ventricular refractoriness and conduction and thus may enhance antiarrhythmia activity. In addition, controlled-release ibutilide formulations significantly decreased DFT requirements. Thus, ibutilide-polymeric controlled-release matrix systems may be useful in conjunction with implantable defibrillators in preventing ventricular arrhythmias and reducing defibrillation energy requirements.

Animals↗

PubMed1990

Natural-Y Même polyurethane versus smooth silicone: analysis of the soft-tissue interaction from 3 days to 1 year in the rat animal model.

The polyurethane foam-covered breast prosthesis is experiencing increased clinical use. The polyurethane is felt to be responsible for altering capsule formation and reducing the contracture rate. This study characterizes the soft-tissue response to the Natural-Y Même polyurethane foam versus smooth silicone in a rat model. Implants were fashioned from an unbacked polyurethane foam specimen used to cover the Natural-Y prosthesis, a silicone shell covered with the Natural-Y foam, and a smooth silicone control. Materials were placed subcutaneously into the backs of male Lew/SsN rats (n = 81) for 3, 7, 14, and 28 days and 3, 6, and 12 months. Implants were then harvested with their soft-tissue response and evaluated histologically. Analysis demonstrates that microstructuring of a surface, as opposed to a smooth material, will dramatically alter the early, intermediate, and late wound-healing events. The soft-tissue response was observed to be dependent on implant site, material chemistry, and morphology as characterized by exudate formation, macrophage invasion, multinucleated giant cell formation, collagen deposition, foam degradation, and angiogenesis.

Animals↗

PubMed1991

Comparative experience with smooth and polyurethane breast implants using the Kaplan-Meier method of survival analysis.

Smooth-walled silicone implants have been widely used in breast surgery. Capsular contracture, causing undesirable firmness and spherical deformity, has been a common problem. Recent studies suggest that polyurethane-covered breast implants are associated with a lower incidence of capsular contracture. The statistical methodology employed in some of these studies, however, may be subject to criticism. Between July of 1984 and June of 1990 (72 months), 427 polyurethane breast implants were used in 279 patients and 439 smooth prostheses were used in 250 patients for a variety of aesthetic and reconstructive procedures. The occurrence of capsular contracture was carefully monitored and then analyzed using the Kaplan-Meier method of survival analysis. This method is particularly well suited to analysis of these types of clinical data because it allows for the fact that contractures occur at varying intervals after surgery and that follow-up of patients is incomplete. The probability of capsular contracture with smooth-walled prostheses was found to be significantly greater than with polyurethane-covered implants in each group of patients studied (p less than 0.05). Other complications occurred at a similar rate regardless of prosthesis type. This study supports the belief that polyurethane breast implants have a lower contracture rate; furthermore, it introduces the Kaplan-Meier method for analyzing the outcome of alternative plastic surgical therapies.

Breast↗

PubMed1992

The biomechanical and histopathologic effects of surface texturing with silicone and polyurethane in tissue implantation and expansion.

There has been considerable interest in determining the effect of morphologic alterations of prosthetic surfaces on capsule response in breast surgery. The purpose of this study was to provide a precise, three-dimensional evaluation of soft-tissue response to surface modifications in both implantation and expansion. Expandable 100-cc prostheses were designed with one of three surfaces: textured silicone (Biocell), standard smooth silicone, or polyurethane (Natural-Y, Meme). A new submuscular implantation site in the rabbit was developed. Each animal randomly received a smooth-surface device on one side and either a textured silicone or polyurethane device on the other. In one group of animals, the prostheses were expanded monthly. Capsular response was evaluated monthly in vivo using standardized techniques as well as biomechanical methods for up to 6 months in the expander group (n = 7 to 16) and 8 months in the implant group (n = 7 to 15). Analysis of biomechanical and histologic data revealed that prosthetic surface morphology can specifically alter capsular response. Polyurethane was the only effective surface in preventing capsular contracture in implantation. In expansion, both textured silicone and polyurethane surfaces resulted in significantly less capsular contracture and less resistance to expansion than comparable smooth-surfaced controls. Statistical comparisons reveal that the biomechanical methods utilized in this study provide the most precise and objective method of defining overall soft-tissue contracture around implanted biomaterials.

Animals↗