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Biomedical subjects

I Kaetsu

Publications and source records attributed to I Kaetsu.

At least 37 records · Page 2Linked to original sources
PubMed1983

Cell culture on polymers prepared by radiation-induced polymerization of various glass-forming monomers.

The growth of cells on polymers prepared by the radiation polymerization of monomethacrylate and dimethacrylate was investigated. Cell growth was affected greatly by such properties of the polymers as water content, wettability, and porosity. Growth was promoted remarkably by rinsing the polymers with warm water at 60-70 degrees C and by irradiation of polymers with an electron beam. Cell growth decreased with increasing oxyethylene length (n) in the polymerized dimethacrylate of same series, CH2C(CH3)CO(OCH2CH2)nOCOC(CH3)CH2. A decrease in the hydrophilicity of the polymer increased cell growth rate. Formation of pore structures in the polymer films also increased the cell growth.

Animals↗
PubMed1983

Cell culture on polymers prepared by radiation-induced grafting of various monomers.

The adhesion and growth of tissue cells on polymers prepared by radiation grafting was investigated. The apparent rates of initial attachment and growth of Chang liver and C6 cells were promoted on surfaces with increased wettability and with a heterogeneous structure for grafted polyvinyl fluoride film. The degree of cell attachment and growth on surfaces having a dense microblock structure, formed by grafting of methyl methacrylate in acetone solvent, was greater than that caused by other factors, such as wettability.

Animals↗
PubMed1983

In vivo release of testosterone from vinyl polymer composites prepared by radiation-induced polymerization.

Polymer-testosterone composites with long periods of controlled slow release were made by radiation-induced polymerization in a supercooled state at low temperature using glass-forming monomers. The in vitro release of testosterone from various vinyl polymer composites was found to follow a matrix-controlled process (Q-t1/2). The rate of drug delivery was accelerated with increasing water content of polymers. In experiments in vivo, the composites were implanted subcutaneously in the back of castrated rats during the 30 day test period. The in vivo release rate of testosterone was a little smaller than in vitro. This difference between two releases also increased with the increase of hydrophilicity of polymer. The physiological response in rats was investigated by measuring the weight of ventral prostate and serum testosterone concentration with testosterone-containing composites. The weight of ventral prostate increased linearly with increasing rate of drug release and the serum testosterone concentration could be correlated with the release and with the weight increase of ventral prostate. It was found from microscopic observation that the used polymer carriers had relatively good biocompatibility to cause little foreign body reaction.

Animals↗
PubMed1982

In vivo release of testosterone from protein--vinyl polymer composites.

Hydrophilic vinyl polymer-protein composites containing testosterone were made by means of thermal denaturation of albumin after radiation-induced polymerization of 2-hydroxyethylmethacrylate (HEMA) at--78 degrees C. The albumin-HEMA mixed polymer can be considerably digested with trypsin. The degree of digestion was smaller than that expected from calculation. It was deduced that the digestion of the albumin component was retarded in the presence of HEMA. The same tendency was observed in in vivo experiments. At the same time, in vivo release of testosterone was depressed in albumin-HEMA mixed polymer composite in accordance with the weight decrease of polymer composite resulting from digestion. The effect of testosterone on the weight of ventral prostate was investigated using composites in castrated Wistar rats. The effect was larger in the controlled slow release from implanted composites rather than that of dosage by injection. The microscopic observation showed that the inflammation and foreign body reaction in rat tissue were retarded in albumin-HEMA mixture polymer composite compared with 100% albumin composite.

Animals↗
PubMed1981

Stabilization of Photosystem II (O(2) Evolution) of Spinach Chloroplasts by Radiation-induced Immobilization.

Spinach chloroplasts were immobilized with vinyl monomers by radiation-induced polymerization at low temperature and stored in buffer containing bovine serum albumin. The lifetime of O(2) evolution activity in photosystem II was prolonged remarkably in immobilized chloroplasts. Thermostability of immobilized chloroplasts stored in buffer containing bovine serum albumin was far better than that of immobilized chloroplasts in pure buffer and that of intact chloroplasts. When immobilized chloroplasts were stored in buffer including polyethylene glycol, the lifetime of O(2) evolution activity was longer than for those stored in buffer containing bovine serum albumin.

Journal Article↗
PubMed1980

Controlled slow release of chemotherapeutic drugs for cancer from matrices prepared by radiation polymerization at low temperatures.

The vinyl polymer-chemotherapeutic agent composites of various shapes (rod, tablet, membrane, microsphere, and powder) were prepared by radiation polymerization at low temperatures for the purpose of durable controlled slow release of drugs from implanted matrices. Bleomycin hydrochloric acid, mitomycin C, and 5-fluorouracil were tested as chemotherapeutic drugs entrapped in poly(diethylene glycol dimethacrylate) including a small quantity of a polymer such as poly(styrene), poly(vinyl formal), poly(vinyl acetate), poly(methyl methacrylate) on polyethylene glycol No. 600. The release rates from the matrices depended much on the kind of polymer, drug, and monomer concentration in polymerization and also on the shape of the composite. The release of these drugs from polymer matrices obeyed the diffusion-controlled release mechanism based on Higuchi's equation and was durable for more than thirty days. It was found that the release rate can be controlled easily by design of the shapes and structures of the polymer matrices.

Antineoplastic Agents↗
PubMed1980

Immobilization of enzymes for medical uses on plastic surfaces by radiation-induced polymerization at low temperatures.

The immobilization of some medically useful enzymes were studied by means of radiation-induced polymerization at -78 degrees C. Glucose oxidase and glucose peroxidase were immobilized in the form of thin membranes inside polyvinyl chloride tubes and on polyethylene films; these membranes showed considerable activity yield, as well as good activity retention. Two effective methods were adopted to improve the surface properties of the base materials and to facilitate firm immobilization by coating: that is, an undercoating method followed by radiation curing of the undercoating and an irradiation grafting method with a monomer. Both were tested with good results. An immobilization of urokinase was also carried out successfully by similar methods. The thrombogenicity of the immobilized urokinase showed a remarkable effect on thombus formation.

Adhesiveness↗
PubMed1980

Controlled release of multi-component cytotoxic agents from radiation polymerized composites.

Multi-component cytotoxic (anticancer) agents such as mitomycin C (MMC), adryamycin (ADM) and 1-(2-tetrahydrofuryl-5-fluorouracil) (FT-207), were entrapped in a single common composite by radiation-induced polymerization of glass-forming monomers in the presence of polymers. The release profiles of each cytotoxic agent were controlled by the contents and compositions of three cytotoxic agents in the matrix. The release rates of each cytotoxic agent were retarded by addition of an adsorbent and accelerated by addition of a pore-making agent. The release fom the common matrix of a cytotoxic agent and its promoter which have markedly different molecular weights [e.g. MMC and urokinase (UK)] was also investigated. A double entrapping method was successfully used for controlled release in such cases. In conclusion it was found that the release profiles of multi-components in a single matrix could be controlled by using these techniques.

Delayed-Action Preparations↗
PubMed1979

Immobilization of Streptomyces phaerochromogenes by radiation-induced polymerization of glass-forming monomers.

Immobilization of Streptomyces phaerochromogenes was studied by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures. Radiation damage of the enzyme could be avoided by choosing irradiation at low temperatures. The enzymatic activity of immobilized cells increased remarkably with a decrease in the irradiation temperature of about -24 degrees C. In constrast to the case of cell-free enzyme immobilization, the most characteristic case was than in these immobilized cells, the enzymatic activity did not decrease with repeated use even in the composite obtained at much lower monomer concentrations. Another characteristic of immobilized cells was the increase in enzymatic activity in the initial stage of repeated use, which could be attributed to the swelling effect of the polymer matrix, thereby increasing the enzymatic activity of whole cells.

Adsorption↗
PubMed1979

Enzyme immobilization by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures.

Enzyme immobilization by radiation-induced polymerization of hydrophilic glass-forming monomers, such as 2-hydroxyethyl methacrylate, was studied. Enzyme radiation damage could be sufficiently retarded at low temperatures. The immobilized enzyme activity yield was markedly higher at low temperature than at higher temperature polymerization. At low temperatures the polymerized composite had a porous structure owing to ice crystallization which depends on the monomer concentration. It was deduced that the enzyme was partially trapped on the polymer surface, partially isolated in the pore, and partially occluded inside the polymer matrix. A decrease in activity caused by enzyme leakage was observed with repeated use in enzyme reactions where the composites had a large porosity. The activity yield showed a maximum at certain optimum porosities, i.e., at optimum monomer concentrations. Continuous enzyme reaction was preferably carried out using immobilized enzyme columns.

Acrylates↗
PubMed1979

Enzyme immobilization by radiation-induced polymerization of hydrophobic glass-forming monomers at low temperatures.

Enzyme immobilization was studied by means of radiation-induced polymerization of hydrophobic glass-forming monomers at low temperatures. The polymerized hydrophobic composite was generally obtained in microspheric form. Enzymatic activity showed little decrease with repeated use in these systems. The particle size of the microsphere increased with increasing monomer concentration, and activity yield had a maximum at an optimum monomer concentration. Immobilization by copolymerization of hydrophilic and hydrophobic comonomers was also investigated and a maximum activity yield was found at a certain monomer concentration. A model scheme for immobilization at low temperatures was proposed and discussed.

Carbohydrate Epimerases↗
PubMed1979

Drug entrapment for controlled release in radiation-polymerized beads.

The preparation of beads including polymer, vinyl monomer, and drug was carried out by low temperature, radiation-induced polymerization. Complete spherical particles were obtained when ethanol was the precipitation medium Polymers such as polymethyl methacrylate and polystyrene were dissolved in various glass-forming monomers, and the drug was dispersed in the mixture. The mixture was dropped into cold precipitation media. The formed monomeric particle was irradiated at low temperatures to produce polymerization. The drug release profiles from polymerized particles were changed by varying the glass-forming monomer and the precipitation medium.

Delayed-Action Preparations↗
PubMed1979

Controlled drug dissolution by radiation-induced polymerization in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methacrylic acid-methyl acrylate copolymer.

Polymer-containing tablet preparation was studied using radiation-induced polymerization of glass-forming monomers at low temperatures in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methyl acrylate-methacrylic acid copolymer. Drug dissolution from tablets was in the pH 3.0-8.0 range. A copolymer contained in the tablets dissolved in the dissolution medium at a specific pH. Drug dissolution from tablets took place rapidly at pH greater than 6.0 in the presence of methyl acrylate-methacrylic acid copolymer and at pH less than 5.0 in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer. The polymers had fibrous or capillary pore structures in contrast to the spherical pore structures formed in the presence of polyethylene glycol 600.

Acrylic Resins↗
PubMed1979

Immobilization of Glucose Isomerase-Containing Streptomyces phaeochromogenes Cells in Fine-Particle Form.

A new preparation method for immobilizing Streptomyces phaeochromogenes cells in fine-particle form was investigated using radiation-induced polymerization at low temperatures with previously salted out hydrophilic monomers. Using this method, it was found that the glucose isomerase activity of the immobilized cell particles was markedly higher than that of immobilized cells in block form obtained without salting out of the monomer. The diameter of the particles was varied by changing the irradiation temperature or the concentrations of monomer and salt. The magnitude of the enzymatic activity increased with decreasing particle diameter. K(m) values of the immobilized cell particles were close to that of the intact cell. These facts suggested that the cells were trapped on the surface of the particle.

Journal Article↗
PubMedDate not supplied

Effect of drug-vinyl copolymer delivery composites on the rat prostate.

A radiation polymerized drug-vinyl copolymer delivery composite (0.8 mm in diameter, 3 mm long) was inserted into the right-lobe ventral prostate (I), into the right testis (II), and subcutaneously (III) into the back of male Wistar rats. The implantation was carried out over a period of 12 weeks maximum. From the relationship between the site of surgical insertion of the implant and the physiologic response (as measured by the decrease in the weight of the prostatic organs, e.g., ventral prostates, dorsolateral prostates, and seminal vesicles), it was found that in an AA560-containing composite (36 micrograms daily), the physiologic response is increased in order of (III) greater than (II) greater than (I). The same tendency was observed in the Estracyt-containing composite system (15 micrograms daily). The difference in the physiologic response owing to the site of surgical insertion of the implant was not observed in an E2-17 beta-containing composite (6 micrograms daily), although this composite showed the strongest physiologic response. No physiologic response in rats with CMA-containing composite (28 micrograms daily) was noted.

Acrylates↗
PubMedDate not supplied

Immobilization of erythrocytes by radiation polymerization of glass-forming monomers at low temperatures.

The immobilization of erythrocyte as the whole cell without hemolysis was studied. It found that erythrocyte could be treated and immobilized stably by radiation polymerization of specific monomers having high viscous and long oxyethylene units chain such as methoxypolyethyleneglycol methacrylate (M-23G) and polyethyleneglycol dimethacrylate (14G). Irradiation dose without hemolysis was limited less than 1 X 10(5) r and a comonomer system consisting of M-23 G-14G, 1:1 and small quantity of glutaraldehyde (GA) was the optimum carrier composition. The functional properties of the immobilized erythrocyte was also investigated. It was found that the immobilized cell could be carried out carbon monoxide-oxygen gas exchange effectively and reversibly so as in the intact cell. The immobilized erythrocyte also showed the catalase activity just as in the intact cell. The stability of erythrocyte increased greatly by the immobilization for standing at low and room temperatures and hardly hemolyzed in non-isotonic medium such as pure water. It was observed in scanning electron microscope that the immobilized erythrocyte had a hollow disk shape same as in intact cell and covered with a thin polymer layer.

Carbon Monoxide↗
PubMedDate not supplied

Immobilization of yeast cells by radiation-induced polymerization.

Radiation-induced polymerization method was applied to the immobolization of yeast cells. The effects of irradiation, cooling and monomer, which are necessary for polymerization, were recovered completely bu subsequent aerobic incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobic incubation period. The growth of yeast cells in immobilized yeast cell was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system.

Dose-Response Relationship, Radiation↗