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Biomedical subjects

M Aizawa

Publications and source records attributed to M Aizawa.

At least 19 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↗
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↗
PubMed1989

Mucoepidermoid carcinoma arising in a lymphoepithelial cyst--report of a case and review of the literature on branchiogenic carcinoma.

A 59-year-old Japanese man who had recently noticed a gradual enlargement in a nodule located in the left anterior part of his neck was admitted for surgical treatment. The histopathological features of the resected tumor were consistent with a typical lymphoepithelial cyst, however, the inner surface epithelium of the cyst showed histological transition to mucoepidermoid carcinoma, which was partially invading the cyst wall. Despite clinical efforts in a systemic search, no primary lesions which could have metastasized were found. The patient hasn't shown any evidence of recurrence since his tumor resection over 2 years ago. Besides this rare case report, a review of the English literature reveals 22 cases of possible branchiogenic carcinoma over the last 10 years, including 21 cases whose histological features were of squamous cell carcinoma and 1 whose histological features revealed mucoepidermoid carcinoma. The present case is thus only the second proven case of low-grade mucoepidermoid carcinoma arising within a branchiogenic cyst.

Branchioma↗
PubMed1989

Electrophysiologic evaluation of asymptomatic patients with the Wolff-Parkinson-White pattern.

In the past 4 years, 34 asymptomatic patients with the Wolff-Parkinson-White (WPW) pattern underwent electrophysiologic study. The effective refractory period (ERP) of antegrade conduction over the accessory pathway was 288 +/- 29 msec. In three asymptomatic patients (9%), the antegrade ERP of the accessory pathway was shorter than 250 msec. The antegrade ERP of the accessory pathway became shorter than 250 msec in an additional 12 of 22 (55%) patients after isoproterenol administration. Nineteen (56%) of the asymptomatic patients showed the absence of retrograde conduction over the accessory pathway even after isoproterenol administration. The rate of induction of orthodromic reciprocating tachycardia in the asymptomatic WPW patients was 15% (5/34), which was significantly lower than that in the symptomatic patients. These data suggest that in the asymptomatic patients, the absence of retrograde conduction over the accessory pathway is the reason they remained asymptomatic, free of reciprocating tachycardia. However, even in the asymptomatic patients, some had the accessory pathway in which antegrade ERP was shorter than 250 msec. They may result in rapid ventricular conduction over the accessory pathway when atrial fibrillation develops.

Adult↗
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↗
PubMed1989

Attenuation of the vasoconstrictor action of neuropeptide-Y by calcium-channel blockers.

Neuropeptide-Y (NPY) was administered intracoronarily in dogs to see the modification of its vasoconstrictor action by the calcium (Ca)-channel blockers nisoldipine (0.1 microgram/kg) and nifedipine (1 microgram/kg). Dogs were anesthetized and the left circumflex artery was cannulated without opening the chest by using a specially designed cannula perfused at constant pressure. The change in coronary flow due to NPY was determined before and after the systemic administration of the two Ca-channel blockers. With administration of 1 to 2 nmol of NPY, coronary blood flow decreased maximally by 23.4 +/- 7.8% without changes in perfusion pressure or central venous pressure and it became significantly less after nisoldipine: 16.0 +/- 5.7% (p less than 0.02). A similar attenuation in the decrease in coronary flow was observed in the nifedipine study: 23.2 +/- 7.5% to 12.0 +/- 6.7% (p less than 0.02). A fall in systemic arterial blood pressure was observed after administration of both Ca-channel blockers, but it was significant only after nisoldipine (p less than 0.01). Nonsignificant increases in heart rate were observed after both drugs. Nisoldipine seemed to attenuate the NPY-induced vasoconstriction in dogs, and its equimolar potency is about ten times that of nifedipine.

Animals↗
PubMed1989

[Effects of EDTPO on hard tissues in rats. 1. Comparison of histological changes produced by same molar of EDTPO, HEBP and EDTA].

Ethylenediamine-N,N,N',N'-tetrakis (methylenephosphonic acid) (EDTPO) is a potent inhibitor of both formation and dissolution of hydroxyapatite crystals in vitro as well as 1-hydroxyethylidene-1, 1-bisphosphonic acid (HEBP). The purpose of this study was to compare with the biological effects of the same molar level of EDTPO, HEBP and ethylenediamintetraaceticacid (EDTA), prototype of EDTPO, on bone, incisor dentin and serum chemistry in young rats. HEBP at 8mg P/kg does chosen based on it's toxicity, and 16mg P/kg of EDTPO and 48mg/kg of EDTA which were identical molar level with 8mg P/kg of HEBP, were injected subcutaneously at once a day for 10 days. At the end of treatment period blood for chemical analysis, and tibia and mandibular for histological examination were taken. Results obtained were; 1) EDTPO and HEBP impaired the net weight gain during experimental period, by about 80% of final body weight in control group, but EDTA did not affect. 2) The biochemical findings of serum were as follows; calcium (Ca) level increased in EDTPO and HEBP group, and inorganic phosphorus (IP) level decreased in EDTPO and HEBP group when compared to control group, and changes of Ca and IP level in EDTPO group was more remarkable than those of HEBP group. Alkalie phosphatase level was decreased in EDTPO group, but increased in HEBP group compared to control group. There were no significant differences between EDTA group and control group, excepting for decrease of Ca level. 3) In histological aspects of the tibia, EDTPO and HEBP groups revealed enlargement of growth plates, being greater in EDTPO group than HEBP group, over the control group, and showed expanded hypertrophic zone of growth plates and wide osteoid seams in the metaphysis. EDTPO group also inhibited the calcification of dentin of mandibular incisor more strongly than HEBP group. From these data, it was indicated that EDTPO is more potent inhibitor of calcification than HEBP. Both of EDTPO and HEBP group, moreover, revealed enlargement of tibial metaphysis. These phenomena suggest that EDTPO also inhibits bone resorption as well as HEBP. EDTA group did not reveal any differences compared to control group.

Animals↗