RESUMEN
The polymerization of gases present in a low temperature plasma is a technique particularly well suited for biomedical material processing. Therefore, the possibilities this technique offers to increase the biocompatibility and haemocompatibility of polysulphone and poly(hydroxybutyrate) membranes to be used in a new bioartificial pancreas device were studied. The deposition of thin fluorocarbon coatings from an argon plasma containing perfluorohexane gave very smooth and hydrophobic surfaces without affecting the filtering properties of the treated membranes. Adding hydrogen increased the reaction yield, but gave rougher and less hydrophobic coatings. We characterized the biological properties of the treated surfaces and discussed the influence of the modified surface properties on the biological behaviour of the treated polymers. The good biocompatibility of the deposited coatings was established by following in vitro the insulin secretion of Langerhans islets cultured on the treated membranes and by examining the fibrous capsule that developed on plasma-treated polymer disks after three months of in vivo incubation in the peritoneum of Wistar rats. Rough and haemocompatible films of poly(hydroxybutyrate) and smoother, but more thrombogenic, polysulphone films were treated by perfluorohexane and perfluorohexane + H2 plasmas to study the relative influence of surface roughness and surface energy on polymer thrombogenicity. In vitro protein adsorption and total blood clotting tests proved that the surface roughness influences the thrombogenicity more than the other surface properties. This study seems to show that the plasma deposition of smooth and hydrophobic fluorocarbon coatings can increase the biocompatibility and reduce the surface thrombogenicity of the treated membranes without affecting their filtering properties.
Asunto(s)
Materiales Biocompatibles , Sangre , Fluorocarburos , Membranas Artificiales , Prótesis e Implantes , Animales , Proteínas Sanguíneas , Células Cultivadas , Insulina/metabolismo , Secreción de Insulina , Islotes Pancreáticos/citología , Islotes Pancreáticos/metabolismo , Peritoneo , Poliésteres , Polímeros/química , Prótesis e Implantes/efectos adversos , Ratas , Ratas Wistar , Sulfonas/química , Propiedades de Superficie , TrombosisRESUMEN
Protein S is a physiological inhibitor of coagulation. It intervenes as co-factor of activated protein C and increases the inactivation of factors V and VIII induced by the latter. Patients with protein S deficiency are exposed to recurrent venous and arterial thrombosis. Most of these thromboses affect the lower limbs, but other regions, and notably the digestive tract, may be involved. Deficiencies in physiological inhibitors of coagulation, and in particular protein S, seem to be a new entity in the vascular pathology of the gastrointestinal system. All young patients with thromboembolic accidents affecting the digestive tract should be investigated for protein S deficiency. If such deficiency is found, then all members of the patients' family must also be investigated. Long-term treatment with antivitamin K drugs prevents recurrences of these thromboembolic accidents.
Asunto(s)
Glicoproteínas/deficiencia , Oclusión Vascular Mesentérica/etiología , Venas Mesentéricas , Trombosis/etiología , Adulto , Anticoagulantes/uso terapéutico , Coagulación Sanguínea , Pruebas de Coagulación Sanguínea , Femenino , Glicoproteínas/fisiología , Humanos , Oclusión Vascular Mesentérica/terapia , Proteína S , Trombosis/tratamiento farmacológico , Trombosis/genéticaRESUMEN
Based on findings for 30 patients, the authors assess the value of CT scans for the diagnosis of cavernous hemangiomas of the liver. Four images were retained, and were graded 0 (absence) or 1 (presence): hypodensity before injection of the contrast material, arteriolar halo after injection, progressive centripetal filling and late hyperdensity. A score of 3 or 4 after the CT scan allows diagnosis. Solitary lesions of at least 3 cm are correctly evaluated. When associated with other smaller lesions, or when smaller than 3 cm, CT scans are less helpful and arteriography is necessary. In all. CT scanning has four limiting parameters: lesion diameter, the number of images requiring exploration, the difficulty in obtaining exactly the same section in various sequences allowing effective scan analysis (thoraco-abdominal position of the liver) and problems specific to individual patients (poor circulation, iodine allergy or intolerance). These limiting factors explain the "wait-and-see" strategy suggested when confronted with solitary hyperechoic nodules smaller than 3 cm.
Asunto(s)
Hemangioma Cavernoso/diagnóstico por imagen , Neoplasias Hepáticas/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Femenino , Humanos , MasculinoRESUMEN
The authors present their experience with interventional radiological techniques employed for chemotherapy: 205 intra-arterial chemotherapy (IAC) cycles were administered to 67 patients (lesion sites were: liver 20, pelvis 35, unknown 12). Catheters were left in place for 5 days in 89% of cases. The positions of the end of the catheter was checked by CT scan, with concomitant arterial opacification in the case of pelvic pathologies; this allowed evaluation of the tumor volume treated. Serious radiological complications of IAC included: 2 surgical thrombectomies and 2 surgical removals of broken catheters (2% complication rate for IAC). 15 embolizations with microcapsules of mitomycin were performed for 11 patients, using the technique of Kato. Venous blood samples revealed the persistence of mitomycinemia for up to four hours. three instances of pain were noted in the 24 hours following embolization. These two techniques have a low rate of serious complications; the therapeutic efficacy observed in certain cases warrants the use of these methods for cancers impossible to treat by radical procedures.