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Biomedical subjects

M Aizawa

Publications and source records attributed to M Aizawa.

At least 73 records · Page 4Linked to original sources
PubMed1994

Electronically modulated biological functions of molecular interfaced enzymes and living cells.

Conducting polymer molecular interfaces have been implemented to modulate biological functions of fructose dehydrogenase, pyruvate oxidase and Saccharomyces cerevisiae at the electrode surface by adjustment of electrode potential. The enzyme activity of the polypyrrole-interfaced fructose dehydrogenase was electronically modulated by means of electron transfer between the enzyme and the electrode surface. The enzyme activity of polypyrrole-interfaced pyruvate oxidase was modulated by an electronically driven change of substrate concentration. The gene expression in polypyrrole-interfaced Saccharomyces cerevisiae was electronically induced by a change in the phosphate concentration.

Electrodes↗
PubMed1994

CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1.

We have identified a novel gene containing CAG repeats and mapped it to chromosome 14q32.1, the genetic locus for Machado-Joseph disease (MJD). In normal individuals the gene contains between 13 and 36 CAG repeats, whereas most of the clinically diagnosed patients and all of the affected members of a family with the clinical and pathological diagnosis of MJD show expansion of the repeat-number (from 68-79). Southern blot analyses and genomic cloning demonstrates the existence of related genes. These results raise the possibility that similar abnormalities in related genes may give rise to diseases similar to MJD.

Adult↗
PubMed1994

Conductive property of the zone of slow conduction of reentrant ventricular tachycardia and its relation to pacing induced terminability.

In order to assess the functional characteristics of the zone of slow conduction of reentrant VT, rapid pacing was performed to entrain VT. The orthodromic conduction time was measured as the interval between the stimulus and the orthodromically captured electrogram recorded distal to the zone of slow conduction, but not precisely at the exit point, and its response to rapid pacing was evaluated. In 32 of 33 consecutive patients, rapid pacing was performed to entrain VT. Of these, rapid pacing was repeated in 28 patients at 3-10 cycle lengths in steps of 10 msec before VT was terminated, or rapid pacing produced an acceleration of the rate. A pacing induced prolongation of the orthodromic conduction time (slowed conduction) was observed in 16 (57.1%) patients and in another 12 (42.9%) patients, the conduction time was constant. The pacing induced termination was observed in 93.8% of VT with slowed conduction and in 50% of VT with constant conduction, and the difference was significant (P < 0.05). There was no difference in the cycle length of VT or the shortest paced cycle length between VT with and without slowed conduction. The zone of slow conduction in human VT showed different conductive properties and VT with slowed conduction was associated with an easier and safer terminability with rapid pacing. The fact might be useful in selecting patients for antitachycardia pacing.

Adolescent↗
PubMed1994

[Three cases of neurogenic bladder due to neuro-Beçhet disease].

We reported three cases of neurogenic bladder due to neuro-Beçhet disease. Case 1 (24-year-old male) and case 3 (54-year-old male) had complaint of urinary frequency and urinary incontinence. Case 2 (35-year-old male) had a complaint of urinary retention. Uro-dynamic study were performed repeatedly in each case. Two cases showed overative detrusor activity in storage phase and normal or hypo detrusor activity in voiding phase. One case (case 2) showed normal detrusor activity in storage phase and acontractile in voiding phase. All cases showed detrusor-sphincter dyssynergia (DSD). All cases were managed with clean intermittent catheterization. Six months later case 2 complained of urge incontinence. Repeated uro-dynamic study revealed that bladder function changed from normal detrusor to overactive detrusor in storage phase. These findings suggest that neurogenic bladder due to neuro-Beçhet disease is characterized uro-dynamical by overactive detrusor in storage phase and DSD in voiding phase.

Adult↗
PubMed1993

Bioluminescent immunoassay with a protein A-luciferase fusion protein.

Protein A and firefly luciferase were genetically fused and the resulting fusion protein was applied to a bioluminescent immunoassay. The gene fusion plasmid, pMALU2, was constructed by inserting the structural gene of luciferase into a protein A expression vector, and was expressed in Escherichia coli. The resulting fusion protein of molecular weight 91 kDa retained not only the enzymatic activity of luciferase but also the binding capability of protein A to the Fc region of immunoglobulin G (IgG). The bioluminescent immunoassay was performed with the fusion protein and human IgG was determined in the concentration range from 10(-3) to 10(-7) g/ml.

Escherichia coli↗
PubMed1993

[Biosensors].

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Antibodies, Monoclonal↗
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↗
PubMed1991

Immunosensors.

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Animals↗
PubMed1990

[A combined chemo-endocrine therapy with tegafur, adriamycin, methotrexate and tamoxifen for advanced renal cell carcinoma].

Six patients with advanced renal cell carcinoma was treated with a new chemo-endocrine regimen consisting of Tegafur, Adriamycin, Methotrexate and Tamoxifen. Estrogen receptor was measured in four cases from renal or metastatic tumors by DCC method, presenting 14.7, 9.7, 1.0 and 0 f moles/mg protein respectively. The patients were medicated with 800-1,200 mg of Tegafur and 20 mg of Tamoxifen daily po, and 20 mg of Adriamycin and 10 mg of Methotrexate intermittently for two weeks interval iv. According to a criteria of Japan Society for Cancer Therapy, two were regarded as CR, one as PR, one as NC and two as PD. The one out of two cases with and without estrogen receptor responded favourably to this therapy. Side effects observed in the treatment were mild gastrointestinal disorders including nausea and vomiting, slight degree of leukopenia, stomatitis, pigmentation and liver dysfunction. The patients were found to be in good quality of life during the treatment because of less toxicity. This therapy can be regarded as a good modality for a treatment of advanced renal cell carcinoma. This is a first report of combined chemo-endocrine therapy with Tegafur, Adriamycin, Methotrexate and Tamoxifen for renal cell carcinoma in the world.

Aged↗
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↗
PubMed1990

[Biosensor].

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Biosensing Techniques↗
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↗