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Biomedical subjects

A Kishida

Publications and source records attributed to A Kishida.

At least 55 records · Page 3Linked to original sources
PubMed1997

The mechanism of anticoagulant activity of a novel heparinoid sulfated glucoside-bearing polymer.

In our previous study on glycoside polymer, it was discovered that sulfated poly(glucosyloxyethyl methacrylate) [poly(GEMA)-sulfate], which bears sulfated D-(+)-glucose, exhibited anticoagulant activity. The anticoagulant activity of poly(GEMA)-sulfate in solution was prolonged by increasing the dose or degree of sulfation of the polymer. In this study, to recognize the mechanism of anticoagulant activity of poly(GEMA)-sulfate, we estimated the binding capacity of antithrombin III to thrombin and some in vitro clotting tests in the presence of poly(GEMA)-sulfate. These results revealed that poly(GEMA)-sulfate had an anticoagulant mechanism which differed to that of heparin. We concluded that the anticoagulant activity of poly(GEMA)-sulfate is responsible for inhibiting fibrin network formation by the insoluble ion complex between fibrinogen and poly(GEMA)-sulfate.

Anticoagulants↗
PubMed1996

Novel functional polymers: poly(dimethylsiloxane)-polyamide multiblock copolymer. V. The interaction between biomolecules and the surface of aramid-silicone resins.

Multiblock copolymers consisting of aromatic polyamide(aramid) and poly(dimethylsiloxane) (PDMS) aramid-silicone resins (PASs) were synthesized by low temperature solution polycondensation, and PAS films were prepared by casting from an N,N'-dimethylacetamide solution. In this study, we investigated bovine serum albumin (BSA) adsorption, L929 cell adhesion, and tissue reaction on the surface of PAS in order to clarify the interaction between PAS and biomolecules. It was found that the amount of adsorbed biomolecules on PAS was extremely low in contrast with those on aramid and nylon films, and it was comparable to SILASTIC 500-1 film. This suppression of adsorption of biomolecules onto PAS seemed to be due to the low surface free energy of the outermost surface of PAS, where PDMS block was condensed.

Adsorption↗
PubMed1996

Evaluation of biological responses to polymeric biomaterials by RT-PCR analysis. I. Study of IL-1 beta mRNA expression.

In this study, we introduce a novel research methodology, the evaluation of mRNA expression of cells contacting with polymeric materials using reverse transcription-polymerase chain reaction (RT-PCR) analysis HL-60 was used as a model of the macrophages. The expression of interleukin-1 beta (IL-1 beta) mRNA, a cytokine secreted by macrophages, was selected to estimate the extent of inflammation. The expression of IL-1 beta mRNA in the HL60 cells cultured on various substrates and in various conditions was studied. Expression of IL-1 beta could be successfully determined by RT-PCR analysis. A 48 h incubation period was necessary to clarify the expression of IL-1 beta mRNA. It became clear that lipopolysaccharide stimulation was not necessary in this analysis because of the high sensitivity of RT-PCR analysis. It is concluded that RT-PCR analysis is a powerful tool for studying cell-polymer interaction, and is a complementary method for ELISA.

Base Sequence↗
PubMed1995

Successful management of infantile hepatic hilar hemangioendothelioma with obstructive jaundice and consumption coagulopathy.

A 4-month-old boy with benign hemangioma of the porta hepatis is described. Obstructive jaundice and consumption coagulopathy developed, which were treated by percutaneous transhepatic drainage (PTHD), without resection of the tumor or bypass surgery. Because of tumor regression, the patient has remained free of symptoms even after the PTHD tube was removed. Because juvenile hemangioma is a benign tumor and occasional spontaneous regression is known to occur (as in our case and other reports), it is suggested that complete resection or bypass surgery is not necessary for juvenile hemangioendothelioma, even with obstructive jaundice, if bile drainage is adequately maintained.

Cholestasis↗
PubMed1994

Immobilization of human thrombomodulin onto poly(ether urethane urea) for developing antithrombogenic blood-contacting materials.

Thrombomodulin (TM) is a newly described endothelial cell-associated protein that functions as a potent natural anticoagulant by converting thrombin from a procoagulant protease to an anticoagulant. In this study, focussing on the application of TM for biomedical materials, recombinant human TM (hTM) was immobilized onto the polymers for medical use, and the evaluation of their antithrombogenicity and the interaction with platelets were investigated. As the base polymer for immobilization reaction, poly(ether urethane urea) (PEUU), which was reported to have good blood compatibility, was used. hTM-immobilized PEUU showed superior antithrombogenic activity, such as the prolongation of plasma recalcification time and the inhibition of thrombin-induced platelet aggregation, though the amount of immobilized hTM was very small (i.e. less than 1 microgram/cm2). Platelet adhesions onto hTM-immobilized PEUU were not observed. These results show that the immobilization of hTM does not change the native good blood compatibility of PEUU, but provides excellent anticoagulant activity.

Antithrombins↗
PubMed1994

Immobilization of human thrombomodulin on biomaterials: evaluation of the activity of immobilized human thrombomodulin.

Thrombomodulin (TM) is a newly described endothelial cell associated protein that functions as a potent natural anticoagulant by converting thrombin from a procoagulant protease to an anticoagulant. In this study, the immobilization of hTM was investigated in detail using surface modified polymers. As the basis of immobilization, poly(acrylic acid) (PAAc) surface-grafted poly(ethylene) (PAAc-g-PE) film was used with the expectation of increasing the immobilization amount of hTM. The effect of the immobilization reaction on the hTM activities, and the comparison of the activities of the immobilized hTM with the free hTM, were studied.

Acrylic Resins↗
PubMed1993

A novel biomaterial: poly(dimethylsiloxane)-polyamide multiblock copolymer I. Synthesis and evaluation of blood compatibility.

Aramid-silicone resins (PASs) consisting of aromatic polyamide (aramid) and poly(dimethyl-siloxane) (PDMS) segments were synthesized by low temperature solution polycondensation. For the evaluation of blood compatibility in vitro, two kinds of experiments were carried out. One was the thromboxane B2(TXB2) release test from platelets attaching to PAS and Biomer. The other was the observation of the platelet adhesion on the surfaces of PAS by scanning electron microscopy (SEM). The results indicated that PAS was bio-inert in vitro. The surface chemical composition of PAS films was investigated by means of electron probe micro analysis (EPMA), X-ray photoelectron spectroscopy (XPS), and dynamic contact angle measurements. The relationship between blood compatibility and surface composition of PAS is discussed.

Biocompatible Materials↗
PubMed1993

Affinity gel electrophoresis of nucleic acids. The interaction between water soluble polymers having malachite green and double-stranded DNAs.

Copolymers prepared by the free radical copolymerization of acrylamide and vinyl malachite green were immobilized in an agarose gel matrix to produce a novel affinity gel for double-stranded DNAs. Relative electrophoretic mobilities of calf thymus DNA and poly(dA-dT)2 strongly depended on the amount of vinyl malachite green to show the strong interaction between DNAs and the copolymers. But any affinity interaction was not observed between poly(dG-dC)2 and the copolymers.

Acrylamide↗
PubMed1992

Interactions of poly(ethylene glycol)-grafted cellulose membranes with proteins and platelets.

The interactions of proteins and platelets with cellulose membranes grafted with poly(ethylene glycol) were studied. The poly(ethylene glycol) grafting was carried out using poly(ethylene glycol)-monoacid and poly(ethylene glycol)-diacid, which have one and two terminal carboxyl groups, respectively. The grafting operates through esterification between the carboxyl groups of poly(ethylene glycol) and the hydroxyl groups on the membrane surface. Both of the poly(ethylene glycol) grafted membranes reduced the complement activation. Adsorption of bovine serum albumin and gamma-globulin increased when the membrane was grafted with poly(ethylene glycol)-diacid, but did not change when it was grafted with poly(ethylene glycol)-monoacid. When platelets were incubated with serum proteins, the platelet adhesion to the membranes slightly decreased by grafting both the poly(ethylene glycol)-diacid and poly(ethylene glycol)-monoacid. The poly(ethylene glycol)-diacid grafted surface showed more clotting than the poly(ethylene glycol)-monoacid grafted and original surfaces.

Animals↗
PubMed1992

RGD-albumin conjugate: expression of tissue regeneration activity.

Albumin conjugated with Arg-Gly-Asp (RGD) has cellular adhesive activity comparable to that of fibronectin in vitro. This study examined whether RGD-albumin conjugate (RGD-ALB) can promote soft tissue ingrowth into a porous matrix in vivo. Polyurethane sponges with 150-500 microns pore size adsorbed with RGD-ALB, fibronectin and albumin were implanted in the subcutaneous tissue of rats. The RGD-ALB-adsorbed sponge exhibited tissue ingrowth comparable to that of the fibronectin-adsorbed sponge at the early period of implantation. On the other hand, the tissue ingrowth was markedly retarded for non-adsorbed and albumin-adsorbed sponges. The enhanced tissue ingrowth found for RGD-ALB and fibronectin was deduced to be mainly a result of its cell-adhesion activity. It is concluded that RGD-ALB exhibits tissue ingrowth-promoting activity at the initial stage of wound healing as effectively as fibronectin.

Albumins↗
PubMed1991

Cell behaviour on polymer surfaces grafted with non-ionic and ionic monomers.

Following exposure to corona discharge, a polyethylene film was graft polymerized with different water-soluble monomers such as acrylamide (non-ionic), acrylic acid (anionic), 2-acrylamide-2-methyl propane sulphonic acid (anionic), styrene sulphonic acid sodium salt (anionic) and N,N-dimethylaminopropyl acrylamide (cationic). Attachment and proliferation of HeLa S3 cells were studied for grafted surfaces with different zeta potentials and contact angles. The polyethylene surface graft polymerized with styrene sulphonic acid sodium salt exhibited high cell attachment and protein adsorption, whereas the cells did not adhere to the 2-acrylamide-2-methyl propane sulphonic acid graft-polymerized surface, although both surfaces had high negative zeta potentials. Graft polymerization of acrylamide reduced the zeta potential of surface close to zero and rejected the cell attachment. The polyethylene surface became highly cell-adhesive through graft polymerization of the cationic N,N-dimethylaminopropyl acrylamide monomer, but too much grafting killed the attaching cells. Once the cells attached to a surface without being killed, they could proliferate at the same growth rate, whatever their surface zeta potential.

Acrylic Resins↗