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PubMedDate not supplied

In vivo study of polyurethane-coated Gianturco-Rosch biliary Z-stents.

PURPOSE: Prototypes of Gianturco-Rosch Z-stents coated with polycarbonate urethane (PCU) were placed in the biliary tree of pigs, in order to test their biomechanical behavior, stability, and biocompatibility. METHODS: The stents were surgically implanted in the common bile duct of three pairs of pigs, which were killed after 1, 3, and 6 months respectively. Explanted livers from pigs of the same race, age, and size were used to provide comparative data. The bile ducts were radiologically and histopathologically examined; the stents were processed and examined by scanning electron microscopy. RESULTS: No complications occurred and the animals showed a normal weight gain. The main bile duct appeared radiologically and macroscopically dilated, but the stents proved to be in place. Histologically, the bile duct epithelium was destroyed, but neither hyperplastic nor inflammatory fibrotic reactions of the wall were evident. Both the metallic structure and the polymeric coating of the stents were intact. A layer of organic material with a maximum thickness of approximately 3 micron was evident on the inner surface of the stents. CONCLUSION: The present in vivo study demonstrates the biocompatibility, efficacy, and stability of PCU-coated Gianturco-Rosch stents in the biliary environment.

Animals↗
PubMed2000

Vertebral body replacement with a bioglass-polyurethane composite in spine metastases--clinical, radiological and biomechanical results.

Metastatic spine lesions frequently require corpectomy in order to achieve decompression of the spinal cord and restoration of spinal stability. A variety of systems have been developed for vertebral body replacement. In patients with prolonged life expectancy due to an improvement of both systemic and local therapy, treatment results can be impaired by a loosening at the implant-bone interface or mechanical failure. Furthermore, early detection of a metastatic recurrence using sensitive imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) is possible in these patients without artefact interference. The aim of our pilot study was to evaluate the clinical applicability and results of a new radiolucent system for vertebral body replacement in the lumbar spine. The system consists of bone-integrating biocompatible materials - a polyetherurethane/bioglass composite (PU-C) replacement body and an integrated plate of carbon-fibre reinforced polyetheretherketone (CF-PEEK) - and provides high primary stability with anterior instrumentation alone. In a current prospective study, five patients with metastatic lesions of the lumbar spine were treated by corpectomy and reconstruction using this new system. Good primary stability was achieved in all cases. Follow-up (median 15 months) using CT and MRI revealed progressive osseous integration of the PU-C spacer in four patients surviving more than 6 months. Results obtained from imaging methods were confirmed following autopsy by biomechanical investigation of an explanted device. From these data, it can be concluded that implantation of the new radiolucent system provides sufficient long-term stability for the requirements of selected tumour patients with improved prognosis.

Adult↗
PubMed1976

The many uses of polyurethane foam.

Self adherent foam padding has unlimited opportunities for plastic and general surgical use. Skin blisters do occur but less often than with tape. It may also be used over the shoulder and scapula where other types of more invasive immobilization were usually necessary and has also been effectively utilized as postmammoplasty support, as facial and postrhytidectomy dressings, and over leg grafts. Furthermore, it can be used for postpilonidal and axillary pad dressings.

Bandages↗
PubMed1981

Polyurethane contraceptive vaginal sponge: product modifications resulting from user experience.

A preliminary study of a new contraceptive vaginal sponge containing the spermicide nonoxynol -9 (N-9), was undertaken to assess acceptability of the method among a group of sexually active volunteers in Mexico City. Numerous modifications of the product and its packaging resulted from user experience and feedback to the physicians and bioengineers conducting the study. Although determining efficacy of the sponge was not an objective, it quickly became clear that spermicide is a crucial component of the intravaginal sponge contraceptive system; a high incidence of pregnancies led us to increase the spermicide level from 10% to 20%, then to the current 30% of dry sponge weight, or about 1.0 gram per sponge. (It should be noted that the high pregnancy rates were consistent with our experience using other vaginal contraceptive methods in the same clinic population). This initial evaluation of the contraceptive sponge has resulted in significant modification which should increase its acceptability to a small but important group of contracepting women. The sponge is currently being evaluated by the International Fertility Research Program (IFRP) in multicentered comparative clinical trials to determine use-effectiveness and acceptability in various cultures.

Clinical Trials as Topic↗
PubMed1980

Standardization of a polyurethane elastomer for facial prostheses.

This study has shown that the polyester urethane elastomers are soft and flexible, characteristics which are desirable for simulating soft facial tissue. In addition, this material was found to have a larger resistance-to-tear when compared with othe materials. The physical and mechanical properties are very sensitive to the composition and the amount of catalyst added. Less influence on the elastomer properties was noticed for the range of temperatures at which it was polymerized. The range of curing time used in this study shows no significant statistical difference on the elastomer properties. Future studies will be directed toward the polymerization of the material at a wider range of times and temperatures to determine the effects at the low and high ends of the range.

Chemical Phenomena↗