Evaluation of the efficacy of a polyurethane condom: results from a randomized, controlled clinical trial.
CONTEXT: Condoms made of latex are not comfortable or appropriate for all consumers. Polyurethane condoms may provide a needed alternative. METHODS: In a double-masked study, 805 monogamous couples were randomized to use either the polyurethane condom or the latex condom for six months. Couples recorded the frequency of intercourse, of condom use and of breakage and slippage throughout the trial in coital diaries and in detailed reports on the first five uses. Breakage and slippage rates were determined, and typical-use and consistent-use pregnancy rates were calculated using life-table analysis, adjusted for use of emergency contraception. RESULTS: The six-month pregnancy rate during typical use (adjusted for use of emergency contraception) was 4.8% for the polyurethane condom and 6.3% for the latex condom. Similarly adjusted pregnancy rates during consistent use over six completed menstrual cycles--2.4% for the polyurethane condom and 1.1% for the latex condom--did not differ significantly. Clinical failure rates (including breakage and slippage occurring during either intercourse or withdrawal) were 8.5% for the polyurethane condom and 1.6% for the latex condom. In general, male participants were more satisfied with the latex condom, and users of latex were significantly less likely to drop out of the study for condom-related reasons than were users of polyurethane. CONCLUSIONS: Although polyurethane and latex condoms provide equivalent levels of contraceptive protection, the polyurethane condom's higher frequency of breakage and slippage suggests that this condom may confer less protection from sexually transmitted infections than does the latex condom. (+info)
Toxicity of combustion products from burning polymers: development and evaluation of methods.
Laboratory and room-scale experiments were conducted with natural and synthetic polymers: cotton, paper, wood, wool, acetate, acrylic, nylon, and urethane. Smoke and off-gases from single materials were generated in a dual-compartment 110-liter exposure chamber. Multicomponent, composite fuel loads were burned within a 100 m(3) facility subdivided into rooms. In chamber experiments, mortality depended on the amount of material burned, i.e., fuel consumption (FC). Conventional dose (FC)/mortality curves were obtained, and the amount of fuel required to produce 50% mortality (FC(50)) was calculated. With simple flame ignition, cotton was the only material that produced smoke concentrations lethal to rats; FC(50) values for cotton ranged from 2 g to 9 g, depending on the configuration of the cotton sample burned. When supplemental conductive heat was added to flame ignition, the following FC(50) values were obtained; nylon, 7 g; acrylic, 8 g; newsprint, 9 g; cotton, 10 g; and wood, 11 g. Mortality resulting from any given material depended upon the specific conditions employed for its thermal decomposition. Toxicity of off-gasses from pyrolysis of phosphorus-containing trimethylol propane-polyurethane foams was markedly decreased by addition of a flame ignition source. Further studies are needed to determine the possible relevance of single-material laboratory scale smoke toxicity experiments. Room-scale burns were conducted to assess the relative contributions of single materials to toxicity of smoke produced by a multicomponent self-perpetuating fire. Preliminary results suggest that this approach permits a realistic evaluation of the contribution of single materials to the toxicity of smoke from residential fires. (+info)
Neutrophil chemotaxis on silicone and polyurethane surfaces.
Silicone vascular catheters have a greater risk of infection and produce greater inflammation in vivo and greater complement activation in vitro than other vascular catheter polymer materials. This study investigated whether polymorphonuclear leukocyte (PMNL) chemotaxis under agarose on silicone surfaces is different than on polyurethane (PU). Glass slides were coated with silicone and PU by use of a constant-speed dipping apparatus. Chemotaxis (3 h) in response to (10-7 mL) FMLP, zymosan-activated serum, and fresh serum (100%) was greater on silicone than on PU (P<.05). Polyclonal antibody to C5a blocked >50% of the movement toward serum (P<.05). Serum in the PMNL well significantly decreased chemotaxis toward FMLP on silicone (P<.05) but not on PU. These findings suggest that excessive complement activation by silicone may interfere with chemotaxis, but further work is necessary to determine whether this is relevant to an increased risk of catheter-related infection. (+info)
Neutrophil adhesion on polyurethanes preadsorbed with high molecular weight kininogen.
Interaction of biomaterials with blood components including neutrophils is responsible for some of the clinical complications that have occurred in cardiopulmonary bypass, hemodialysis, and ventricular assist procedures. The possibility of inhibiting the initial adhesion of neutrophils to biomaterials has been studied extensively, but the problem remains unsolved. In this study, we investigated the effect of HK adsorption on polyurethane, a widely used component of extracorporeal and intracorporeal devices. HK and HKa were allowed to adsorb on 4 different charged polyurethanes: noncharged (PU), cationic (NR(4)), anionic (SO(3)), and zwitterionic (GPC) polyurethanes. The effect of kininogen adsorption on neutrophil adhesion, the surface density of the adsorbed kininogen, and the exposure of HK domains 3 and 5 (D(3) and D(5H)), which are responsible for the binding of HK to the neutrophil integrin alpha(m)beta(2) or Mac-1, were examined. On PU, NR(4), and SO(3), kininogen adsorption reached 80% of monolayer coverage when 100 pmol/mL or higher concentration of protein solutions were used. The NR(4) surface adsorbed the most kininogen along with a high exposure of D(3) and D(5H). The availability of D(3) and D(5H) allowed neutrophils to bind to the surface via the Mac-1 receptor; thus, on the NR(4) surface, adsorbed kininogens lost their antiadhesive property, which resulted in a high degree of neutrophil adhesion. Increasing Mac-1 expression by exposure to fMLP increased the neutrophil adhesion on this surface. In contrast, exposure of D(3) and D(5H) on SO(3) was significantly less, because HK binds to anionic surfaces with similar protein sequences used for cell binding. This low binding site exposure preserved the antiadhesive property of HK. GPC was resistant to neutrophil adhesion even in the absence of adsorbed kininogens because of its phosphorylcholine moiety. Thus, both SO(3) coupled with kininogen (or kininogen peptides) and GPC have the potential to markedly reduce neutrophil adhesion to biomaterial devices. (+info)
Exposure to MDI during the process of insulating buildings with sprayed polyurethane foam.
Buildings are often insulated with sprayed-in-place polyurethane foam in spite of the fact that few studies have been carried out on exposure levels to isocyanates during the spraying process. This paper is meant to provide new data on personal exposure to methylene-bis (4-phenylisocyanate) (MDI) while dwellings and office buildings are being insulated with polyurethane foam. An impinger using a 1-(2-methoxyphenyl)piperazine toluene solution as absorbent was used to take personal samples for the sprayer and helper during indoor and outdoor applications. The analytical results show that the levels of exposure were significant, especially for the sprayer, with values of up to 0.077 mg m-3 and 0.400 mg m-3 during outdoor and indoor applications, respectively. The helper's exposure was always lower. (+info)
In vitro cytotoxicity of textile paint components linked to the "Ardystil syndrome".
The spraying of a paint formula (Acramin F system) had led to severe pulmonary disease in textile printing sprayers in Spain and Algeria (Ardystil syndrome). In order to elucidate the underlying mechanisms of the toxicity of this paint and its main polymeric components, Acramin FWR, Acramin FWN, Acrafix FHN, and Acramoll W, we have undertaken studies using a battery of different cell-types and assessing in vitro cytotoxicity by measuring LDH leakage. This study shows that, as in in vivo studies, the three polycationic paint components, Acramin FWR (a polyurea), Acramin FWN (a polyamide-amine), and Acrafix FHN (a polyamine) exhibited considerable cytotoxicity (LC50 generally below 100 microg/ml for an incubation of 20-24 h) in vitro, while Acramoll W, which is not a polycation, was almost non-toxic (in the concentration range tested). The cytotoxicity was comparable in primary cultures of rat and human type II pneumocytes and alveolar macrophages as well as in the pulmonary cell line A549 and the hepatic cell line HepG2. In human erythrocytes, the toxicity was less pronounced. We speculate that the multiple positive charges play an important role in the toxic mechanism. It is concluded that Acramin FWR and Acramin FWN have similar intrinsic toxicity and that these polymeric compounds, which have no irritant properties or systemic toxicity when given orally, exert a high, unexpected, degree of cytotoxicity. (+info)
In vivo analysis of dynamic tensile stresses at arterial end-to-end anastomoses. Influence of suture-line and graft on anastomotic biomechanics.
OBJECTIVE: to determine the influence of an anastomotic suture line and a graft on dynamic tensile stresses of vascular end-to-end anastomoses in vivo. MATERIAL AND METHODS: the abdominal aorta of twelve 35-kg pigs was used as an experimental model. Simultaneous recordings of internal arterial diameter and pressure were performed on each pig at 3 successive stages: (1) The genuine artery (REF), (2) artery-artery (A-A) and (3) graft-artery (G-A) anastomosis at 1-mm increments in the immediate perianastomotic area. Thereby, RD (relative distension), CC (compliance coefficient), E(p)(dynamic pressure-strain elastic modulus) and hysteresis loop areas could be calculated for every measuring point. RESULTS: the graft was significantly stiffer than REF. A-A and G-A anastomoses were significantly less compliant than REF. Maximum E(p), minimum CC and hysteresis loop areas were found at the anastomotic line due to minimum anastomotic RD. Downstream of the G-A anastomosis, the RD, CC, E(p)and loop areas were significantly different from REF, but significantly different from A-A. CONCLUSION: an animal model for acute studies of mechanical properties of vascular end-to-end anastomoses was developed. The main determinant for anastomotic biomechanics was the suture-line itself. (+info)
Prenatal toxicity of inhaled polymeric methylenediphenyl diisocyanate (MDI) aerosols in pregnant wistar rats.
Mated Wistar rats, 25/group, were exposed to polymeric methylenediphenyl diisocyanate (MDI) aerosol of respirable size for 6 h/day, on gestational days (gd) 6 through 15, at 0, 1, 4, and 12 mg/m3. Maternal clinical signs, body weights, and feed and water consumption were measured throughout gestation. At scheduled sacrifice on gd 20, maternal body, gravid uterine, liver, and paired lung weights were documented. Corpora lutea were counted, implantation sites were identified: resorptions, dead and live fetuses, and placentas were weighed. All live fetuses were counted, sexed, weighed, and examined for external alterations; approximately 50% of the live fetuses/litter were preserved in Bouin's fixative and examined for visceral alterations, and the remaining live fetuses/ litter were cleared and stained with alizarin red S and examined for ossified skeletal alterations. Maternal toxicity was observed at 12 mg/m3, including mortality (2 of 24 pregnant), damage to the respiratory tract, reduced body weights and weight gain, reduced liver and increased lung weights, and reduced gravid uterine weight (the last not statistically significantly different from the control value). Developmental toxicity was also observed at 12 mg/m3, including reduced placental and fetal body weights and an increased incidence of fetal skeletal variations and skeletal retardations. There was no evidence of maternal or developmental toxicity at 1 or 4 mg/m3. The no observed adverse effect concentration for maternal and developmental toxicity was therefore 4 mg/m3. There were no treatment-related teratogenic effects at any concentrations evaluated. (+info)