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Biomedical subjects

M Kumakura

Publications and source records attributed to M Kumakura.

At least 55 records · Page 3Linked to original sources
PubMed1984

Flexible porous discs by radiation polymerization method for enzyme immunoassay of alpha-fetoprotein.

New porous discs for enzyme immunoassay of alpha-fetoprotein (AFP) have been prepared by radiation polymerization of various monomers at low temperature. The activity (optical density) of immobilized anti-AFP disc varied with irradiation temperature, anti-AFP concentration, and the hydrophilicity of monomer, in which copolymerization of hydrophilic 2-hydroxyethyl methacrylate and hydrophobic monomers at low temperature below 0 degrees C gave a high activity. The immobilized anti-AFP disc was flexible and had a porous structure. The immobilized anti-AFP discs in dry state are convenient for storage. The minimum serum volume in the assay was 5 microliter. A good correlation (r = 0.98) was noted between AFP concentrations measured by ratio immunoassay and enzyme immunoassay with immobilized anti-AFP disc. The mean recovery of AFP (16-80 ng) added to serum was 95-110%.

Animals↗
PubMed1983

Polyacrolein microspheres as immunoreagents.

Polyacrolein microspheres were prepared by radiation polymerization of acrolein in the absence of emulsifying or stabilizing agent. The microspheres had functional surface aldehyde groups permitting covalent binding with antibody in 1 step. The particle size of the microspheres varied with polymerization conditions, especially irradiation temperature. The microsphere antibody conjugates obtained by binding immunoglobulins to polyacrolein microspheres were used to label cells. The reactivity of microsphere antibody conjugates was shown by specific aggregation by antigen.

Acrolein↗
PubMed1983

Immobilization of antibodies and enzyme-labeled antibodies by radiation polymerization.

Immobilization of antibodies and enzyme-labeled antibodies by radiation polymerization at low temperatures was studied. The antibody activity of antibody was not affected by irradiation at an irradiation dose of below 8 MR and low temperatures. Immobilization of peroxidase-labeled anti-rabbit IgG goat IgG, anti-peroxidase, peroxidase, and anti-alpha-fetoprotein was carried out with hydrophilic and hydrophobic monomers. The activity of the immobilized enzyme-labeled antibody membranes varied with the thickness of the membranes and increased with decreasing membrane thickness. The activity of the immobilized antibody particles was varied by particle size. Immobilized anti-alpha-fetoprotein particles and membranes can be used for the assay of alpha-fetoprotein by the antigen-antibody reaction, such as a solid-phase sandwich method with high sensitivity.

Acrylates↗
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↗
PubMed1978

Metabolic fate of 1-hexylcarbamoyl-5-fluorouracil in rats.

1. The metabolic fate of a new antitumour agent, 1-hexylcarbamoyl-5-fluoro [6-14C]uracil (14C-HCFU) in rats after oral administration was compared with that of 5-fluoro[6-14C]uracil (14C-FU). 2. Tissue radioactivity reached a max. 1 to 3 h after administration of 14C-HCFU and 0.5 h after 14C-FU. 3. Both drugs were excreted rapidly, mostly in urine. Expired 14CO2 from 14C-HCFU was significantly less than that from 14C-FU. 4. Unchanged FU was not detected in plasma 3 h after administration of 14C-FU, whereas FU was detected in plasma 5 h after 14C-HCFU. The pyrimidine ring of 14C-HCFU might be degradated more slowly than that of 14C-FU. 5. 1-(5-Carboxypentylcarbamoyl)-5-fluorouracil and 1-(3-carboxypropylcarbamoyl)-5-fluorouracil were identified as the major urinary metabolites of 14C-HCFU.

Animals↗