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Biomedical subjects

Y Idezuki

Publications and source records attributed to Y Idezuki.

At least 145 records · Page 8Linked to original sources
PubMed1982

Permeability of heparinized hydrophilic polymer (H-RSD): application to semipermeable membrane for microencapsulation of activated charcoal.

A series of heparinized hydrophilic polymers (H-RSD) composed of a hydrophobic element, a nonionic hydrophilic element, a cationic element and ionically bound heparin was synthesized. The permeability of the H-RSD polymers with various chemical compositions and water contents was investigated. From the studies on the permeability, it has been found that in order to maintain good permeability after heparinization, the nonionic hydrophilic element is necessary. In addition, the microencapsulation of activated charcoal granules using a H-RSD polymer with a similar permeability to that of Cuprophan was examined. In vitro adsorption studies and in vivo direct hemoperfusion studies on the activated charcoal microencapsulated with the H-RSD polymer, show that the H-RSD coating prevents clot formation without loss of the absorption power of the activated charcoal.

Absorption↗
PubMed1977

Endoscopic balloon tamponade for emergency control of bleeding esophageal varices using a new transparent tamponade tube.

The endoscopic tamponade method, using a new transparent balloon tube, has been developed for the emergency control of bleeding esophageal varices. The introduction of the tube is performed while observing the esophagus utlizing a fiberoptic endoscope, which is inserted within the lumen of the tube so that the accidental injury to the mucosa can be avoided. The accurate diagnosis of the cause of bleeding is possible so that the most suitable form of treatment can be initiated without delay. Hemostasis is achieved with minimum balloon pressure, and the examination of the varices may be repeated, whenever desired, so that damage to the esophageal mucosa can be avoided. Deflation of the balloons and termination of the tamponade can be selected and planned so that the recurrence of bleeding immediately after the removal of the tube can be avoided. This method has so far been used successfully without any complications in 5 patients.

Emergencies↗
PubMed1975

Mechanism of antithrombogenicity of a new heparinized hydrophilic polymer: chronic in vivo studies and clinical application.

A new heparinized hydrophilic polymer, H-RSD (graftcopolymer composed of ethylene, vinyl acetate, vinyl chloride, polyethyleneglycolmethacrylate, quartenized dimethylaminoethylmethacrylate and ionically bound heparin), continuously releases heparin from its surface at the rate of approximately 0.004 units/cm2/min when placed in the plasma. It has excellent antithrombogenic and mechanical properties for a biomaterial. In vivo evaluation for thrombogenically using IVC indwelling catheter method in dogs revealed excellent antithrombogenicity over 2 wks. Use of H-RSD as a coating material on other synthetic polymers has also been studied, Catheters made of polyurethane were coated with H-RSD 20 mu, 50 mu, 100 mu, and 150 mu in thickness, and were tested for thrombogenicity in the dog. Catheters coated with 20 mu of H-RSD caused moderate to severe thrombus in the IVC after 2 wks, but catheters coated with H-RSD 50 mu or more were completely free of thrombus formation after 2 wks. Scanning electron micrograph showed neither fibrin clots nor platelet adhesion on the surface of H-RSD catheters. Heparin concentration in H-RSD catheters was analyzed by electron probe X-ray microanalyzer before and after in vivo tests. Heparin concentration became higher as the thickness of H-RSD coating increased. After a 2 wk test, heparin concentration in the catheters decreased to about 85% of the initial value. Good retention of heparin in the H-RSD catheters after in vivo tests was found to correlate with continuous release of heparin from its surface. H-RSD catheters can be sterilized with ethylene oxide gas. Pyrogen and acute toxicity tests on extracts of H-RSD were negative. H-RSD catheters were used in 9 patients for up to 3 wks. Thrombus formation observed by pullout venography or at autopsy in these patients was less than those seen in patients with silicone rubber or polyethylene catheters.

Acetates↗