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Biomedical subjects

Y Ikariyama

Publications and source records attributed to Y Ikariyama.

11 recordsLinked to original sources
PubMed1991

Electrically controlled proliferation of human carcinoma cells cultured on the surface of an electrode.

Human carcinoma cells, MKN45, were cultured on the surface of a metal-coated plastic plate electrode the potential of which was controlled. The proliferation rate and cell morphology were altered depending on the applied potential. Cell proliferation was halted in the potential range above 0.4 V vs. Ag/AgCl, although cells started to proliferate again when the applied potential was shifted from 0.4 V to 0.1 V vs. Ag/AgCl. Fluorescence probe studies indicated that the fluidity of plasma membrane decreased in association with halting of cell proliferation. These results suggest that electrical stimulation causes cells to temporarily halt proliferation, and that cell proliferation was reversibly controlled by electrode potential. The mechanism is interpreted in relation to the change of plasma membrane structure represented by membrane fluidity.

Cell Division↗
PubMed1990

Application of a fusion protein, metapyrocatechase/protein A, to an enzyme immunoassay.

A fusion protein of metapyrocatechase and protein A was genetically produced for demonstration of effective conjugation of an enzyme with a binding protein employed in enzyme immunoassay. Plasmid pMPRA3, constructed by inserting the protein A gene into a plasmid pMK12 vector derived directly from the structural gene of metapyrocatechase, was expressed in Escherichia coli. The resulting fusion protein was shown to have promising properties for use in enzyme immunoassays due to the specific binding of the protein A moiety to the Fc portion of immunoglobulin G and to the high amplification of enzyme. Bovine serum albumin, a model antigen, was successfully determined in the concentration range from 1 x 10(-3) to 1 x 10(-7) g/ml.

Catechol 2,3-Dioxygenase↗
PubMed1990

Hyperproduction of a bifunctional hybrid protein, metapyrocatechase-protein A, by gene fusion.

A hybrid protein between metapyrocatechase and Staphylococcal protein A was produced by recombinant DNA techniques. A plasmid carrying the fusion gene that encodes the hybrid protein was constructed and expressed in E. coli. Over 70% of soluble proteins of the cell extracts was estimated to be the hybrid protein. This fusion protein is about 65,000. Both the IgG-binding activity of protein A and the metapyrocatechase activity were found in the hybrid protein. The optimum pH of metapyrocatechase in the fusion protein was at around 6.5 and Km was 1.3 X 10(-5) M. A simple immuno-enzymometric assay was developed for anti-BSA antibody using the fusion protein.

Amino Acid Sequence↗
PubMed1990

Enzymatic synthesis of polyaniline film using a copper-containing oxidoreductase: bilirubin oxidase.

Electroactive polyaniline films have been synthesized by using a copper-containing oxidoreductase, bilirubin oxidase (BOD). Enzymatic polymerization took place on the surface of BOD-adsorbed solid matrix which was in contact with a buffer solution containing aniline. Optimum conditions for enzymatic polymerization of aniline were investigated. Elemental analysis and IR spectroscopy indicated that the enzymatically synthesized film was polyaniline. The cyclic voltammetric studies demonstrated that the polyaniline film was electrochemically reversible in the redox properties in acidic aqueous solutions. Since the film retained enzymatic activity of BOD which was employed as a catalyst for polymerization, enzymatic polymerization seems promising in preparation of immobilized enzyme membranes.

Aniline Compounds↗
PubMed1990

Electrical effects on the proliferation of living HeLa cells cultured on optically transparent electrode surface.

Low d.c. potential application induced changes of cellular morphology and growth of living cells on a potential-controlled electrode. At a potential range higher than +0.7 V (vs. Ag/AgCl), serious electric effects on cell viability, membrane permeability, and cytoskeletal morphology of HeLa cells were observed. On the other hand, at lower than +0.5 V no effect was observed. At the boundary potential range between +0.5 V to +0.7 V, where HeLa cells were cultured on the potential-controlled optically transparent In2O3 electrode (OTE) surface, intriguing effects on HeLa cells appeared. At this potential range, where HeLa cells cultured on a potential-applied OTE, all the cells were alive accompanying morphological change. The morphology of HeLa cells returned to their normal spindle shape, when potential application to the electrode was cut off. At a potential of +0.65 V, cell proliferation ratio of cultured cell on an electrode was about one-fifth of that on a non-controlled electrode. These results suggest that low d.c. electrical effects induce significant change in cellular morphology and function.

Cell Division↗
PubMed1989

Luminescence biosensors.

A novel optical biosensor for homogeneous immunoassay has been developed on the basis of the finding that electrochemical luminescence of pyrene-labelled antigen is extremely inhibited by immunochemical complexation. Electrochemical luminescence homogeneous immunoassay for human serum albumin (HSA), as a model analyte, was performed with a platinum plate electrode which was located in the vicinity of an optical fibre tip. HSA was determined in the concentration range of 3-25 X 10(-6) mol/l. To improve electrochemical luminescence measurement an optical fibre electrode has been developed by fabricating a transparent platinum film on the top of an optical fibre. The minimum detectable limit of luminol was 10(-11) mol/l with the optical fibre electrode. Luminol was applied as a label for homogeneous immunoassay.

Biosensing Techniques↗
PubMed1989

Electrically regulated cellular morphological and cytoskeletal changes on an optically transparent electrode.

Electrically regulated morphological and cytoskeletal changes of HeLa cells were studied on an optically transparent electrode (OTE), on which potential-applied surface cellular behavior and morphogenesis were easily observed. Upon application of a potential, HeLa cells in an OTE exhibited remarkable morphological changes above +0.5 V (vs. Ag/AgCl) and below 0 V. At each potential in this potential range, change in F-actin distribution was observed using a fluorescent probe (rhodamine phalloidin). These results suggest that an electrical field induces a subcellular cytoskeletal change. Electrostimulation of cells with OTE can be a valuable strategy for the manipulation of cultured human cells.

Actins↗
PubMed1985

Electrochemical luminescence-based homogeneous immunoassay.

Aromatic hydrocarbon such as pyrene capable of generating electrochemical luminescence was employed as a label of immunoassay. Pyrene labeled antigen generated luminescence upon electrolytic reduction, while the luminescence decreased remarkably in the presence of antibody. The labeled antigen (constant) and free antigen were competitively reacted to the constant amount of antibody. The luminescence was correlated to the antigen concentration as little as 10(-6)M antigen. The proposed method is a very unique immunochemical technique which requires no BF separation.

Antibodies↗
PubMedDate not supplied

Ca(2+)-responsive extensible monolayer membrane of calmodulin-albumin conjugate.

A Ca(2+)-responsive monolayer protein membrane was prepared by developing calmodulin and bovine serum albumin at the air-water interface and by conjugating them with a bifunctional agent. In the case of the BSA monolayer, complex formation with Mg2+ generated a larger change in surface pressure than that with Ca2+. On the other hand, a drastic change in surface pressure was observed for the conjugated thin membrane associated with Ca2+ than that associated with Mg2+. Due to a drastic change in the conformation of calmodulin, the conjugated protein film changes its morphology (STM image), depending on Ca2+ concentration: the extended structure in the presence of Ca2+ transforms to a shrinked structure in the absence of Ca2+. The largest surface pressure change was detected when calmodulin was mixed with an equimolar amount of bovine serum albumin.

Calcium↗