Biomedical subjects

I K Kang

Publications and source records attributed to I K Kang.

22 records · Page 2Linked to original sources

PubMed1988

Serotonin and beta-thromboglobulin release reaction from platelet as triggered by interaction with polypeptide derivatives.

The effect of wettability of 14 polypeptide derivatives upon adhesion and activation of platelets was investigated with reference to release reactions from adhered platelets, using radioisotope labeling and radioimmunoassay method. The serotonin release was more significant from platelets adhered to polymer materials to which a large number of platelets are adhered. However, no clear relationship was found between adhesion of platelets and beta-thromboglobulin release from adhered platelets. Therefore, stimuli inducing serotonin release and beta-thromboglobulin release were considered to be from different origins. The trend in beta-thromboglobulin release was well correlated with the extent of morphological change of adhered platelets as observed by scanning electron microscope. It was suggested that the determination of released beta-thromboglobulin in association with the measurement of platelet adhesion could be useful for evaluation of blood compatibility of materials.

Blood Platelets↗

PubMed1988

Gas permeability of the film of block and graft copolymers of polydimethylsiloxane and poly(gamma-benzyl L-glutamate).

A-B-A type block copolymers of poly(gamma-benzyl L-glutamate) (PBLG, A segment) and polydimethylsiloxane (PDMS, B segment) and PDMS (trunk)-PBLG (branch) graft copolymers were synthesized, and the permeation of oxygen in water and the permeation of oxygen and carbon dioxide in the dry state were investigated. The gas permeation coefficient (P) increased with increasing content of PDMS. However, PCO2/PO2 values of copolymer films were in the range 6-9, i.e. larger than 5.4 for PDMS film. The oxygen permeation in water suffered from the interfacial resistance, which was reduced by the hydrolysis of film surface. The Arrhenius plot of the gas permeation coefficient in the dry state of the block copolymer B showed a turning point at about 40 degrees C. This temperature is close to beta-peak temperature (39 degrees C) and may be ascribed to the molecular motion of the PBLG segment. Transmission electron microscopy showed that one of the block copolymer films (PDMS 46 mol%) appears to have PDMS segments dispersed in the PBLG matrix (island-in-sea structure) and one of the graft copolymer films (PDMS 58 mol%) appears to take a lamellar structure. The gas permeation across the graft copolymer film appears to occur through the continuous PDMS phase, leading to a near-negligible activation energy in this process.

Biocompatible Materials↗

PubMed1988

Adsorption of plasma proteins and platelet adhesion on to polydimethylsiloxane/poly(gamma-benzyl L-glutamate) block copolymer films.

A-B-A-type block copolymers of four different compositions were synthesized, in which A and B represent poly(gamma-benzyl L-glutamate) and polydimethylsiloxane segments, respectively. Among the block copolymers and their surface-modified derivatives, those containing 40-70 mol% polydimethylsiloxane and having water contact angles ranging from 50 degrees to 85 degrees were found not to induce conformational change of plasma proteins upon adsorption. It was also observed that the number of adhered platelets and the rate of serotonin release from adhered platelets increased when plasma proteins underwent conformational change upon adsorption. These experimental observations indicate that hydrophobic-hydrophilic block copolymers having a certain composition do not induce conformational change of plasma proteins upon adsorption and do not adhere to and activate platelets, thus leading to a suppression of thrombus formation.

Adsorption↗

PubMedDate not supplied

Preparation of insulin-immobilized polyurethanes and their interaction with human fibroblasts.

Insulin-immobilized polyurethanes (PU) were prepared by the graft polymerization of acrylic acid on oxygen plasma-treated PU, followed by a coupling reaction with polyethylene oxide (PEO) and subsequently with insulin. Modified PUs were characterized by measuring the water contact angle, the electron spectroscopy for chemical analysis and the attenuated total reflection Fourier-transform infrared spectroscopy. The wettabilities of the PU surfaces were increased by the introduction of acrylic acid, PEO and insulin. The amount of insulin immobilized was controlled by changing the concentrations of grafted acrylic acid and PEO. The interactions of human fibroblasts with surface-modified PUs were investigated using [3H]-thymidine incorporation and optical microscopy. Compared to the PU control, the proliferation of cells on the insulin-immobilized PUs was accelerated irrespective of the presence of serum while it was not influenced by PEO grafting. It seemed to be certain, from the experiments with high performance liquid chromatography, that A chain of insulin mainly reacted with the amine-end group of PEO grafted during the immobilization reaction.

Acrylates↗