Biomedical subjects

Masahiro Kudo

Publications and source records attributed to Masahiro Kudo.

5 recordsLinked to original sources

PubMed2005

Effective monitoring of protein reaction on glass plate surfaces by TOF-SIMS.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is capable of chemically visualizing proteins on insulated samples. Distribution of an immobilized probe protein, fluorescent-labeled protein A-immobilized on a glass plate, and that of a sample protein, immunogloblin G (IgG) in solution, reacting with protein A on the biosensor surface, were evaluated with TOF-SIMS (TFS-2100, Physical Electronics). TOF-SIMS spectra and images of the protein on the glass plates were obtained, and this "mutual information", as defined by information theory, was employed to analyze the TOF-SIMS spectra of proteins. Fragment ions from protein A and IgG were distinguished by the mutual, reinforcing information and specific fragment ions to each protein were selected to obtain the TOF-SIMS image of the protein. It is evident from the TOF-SIMS images of each protein that protein A was immobilized on the substrate homogeneously and that the reaction between the immobilized protein A and IgG is not localized in this condition. Chemical images of the proteins by TOF-SIMS will contribute to a better understanding of the reaction on the biosensor surface, and thus will help the development of more sophisticated biosensors. In addition, the requisite chemical conditions as well as the interaction between the biosensor surface and the immobilized proteins were investigated by TOF-SIMS by means of sets of reinforcing, mutually supportive information.

Adsorption↗

PubMed2005

Development of fluorescence change-based, reagent-less optic immunosensor.

A reagent-less, regenerable and portable optic immunosensor was developed. A model sample, immunoglobulin G (IgG), was detected with this system based on changes in fluorescent intensity of fluorescent labeled protein A with specific reactivity to IgG depending on a reaction between the proteins. A glass plate immobilized with Qdot-labeled protein A was placed on the top of optic fibers designed for both excitation and fluorescence emission. The optic fibers with the Qdot-labeled protein A-immobilized glass plate were inserted into a solution of pH 7.4 phosphate buffered saline. After stabilization of the fluorescence intensity, IgG was added and the time-course of the fluorescence intensity was measured on a fluorometer connected with the optic fibers. Furthermore, the fluorescence response of a transient state was evaluated with the same system. When the Qdot-labeled protein A bound to IgG, fluorescence intensity decreased because of the inhibition by IgG. The degree of fluorescence decrease depends on the IgG concentration at a steady state and also in a transient state.

Antigen-Antibody Complex↗

PubMed2005

Prognostic value of I-123 metaiodobenzylguanidine imaging in vasospastic angina without significant coronary stenosis.

BACKGROUND: Myocardial imaging is widely used to detect coronary artery disease and to assess its prognosis. In vasospastic angina (VA), cardiac imaging can provide information on disease activity, which is related to cardiac events. The aim of this study was to clarify whether exercise thallium-201 imaging (Tl-SPECT) and 123I-metaiodobenzylguanidine imaging (MIBG) have prognostic value for patients with VA, but without significant coronary artery stenosis. METHODS AND RESULTS: One hundred and 5 patients who showed acetylcholine-induced coronary spasm, normal left ventricular function and no significant stenosis (<50%) underwent both symptom-limited Tl-SPECT and MIBG within 1 month. All patients were prescribed calcium antagonist during the follow-up period (mean 4.7 years). Exercise-induced ischemia was detected by Tl-SPECT in 53 patients and multivessel coronary spasm by coronary angiography in 33 patients. During the follow-up period, 1 patient died suddenly and another died of acute myocardial infarction (MI). Two patients developed nonfatal acute MI and 7 patients underwent emergency coronary angiography because of unstable angina. According to the baseline characteristics, VA with cardiac events showed a significantly higher heart-to-mediastinum ratio (H/M ratio) and a significantly lower MIBG washout rate than those without cardiac events (p<0.03 and p<0.02, respectively). Among 8 clinical variables, including coronary risk factors, exercise parameters and exercise-induced ischemia on Tl-SPECT and the MIBG delayed H/M ratio and washout rate, univariate Cox proportional hazard regression analysis showed that the high H/M ratio and reduced washout rate of MIBG were significant predictors of future cardiac events (relative risk (RR) =4, confidence interval (CI) =1.21-13.29, p<0.02 for H/M ratio and RR 0.92, CI 0.85-0.99, p<0.02 for washout rate). However, exercise-induced ischemia did not show any statistical significance. By multivariate Cox proportional hazard regression analysis, a reduced MIBG washout rate was the only significant predictor of future cardiac events (odds ratio =0.90, CI =0.82-1.00, p<0.04). CONCLUSION: MIBG imaging can identify high-risk patients, even among those with VA who were previously regarded as low risk. This result strongly supports the idea that cardiac sympathetic dysfunction contributes to coronary artery spasm leading to cardiac events.

3-Iodobenzylguanidine↗

PubMed2004

Fucoxanthin induces apoptosis and enhances the antiproliferative effect of the PPARgamma ligand, troglitazone, on colon cancer cells.

The effect of fucoxanthin, from the edible seaweed Undaria pinnatifida on viability of colon cancer cells and induction of apoptosis was investigated. Fucoxanthin remarkably reduced the viability of human colon cancer cell lines, Caco-2, HT-29 and DLD-1. Furthermore, treatment with fucoxanthin induced DNA fragmentation, indicating apoptosis. The DNA fragmentation in Caco-2 cells treated with 22.6 microM fucoxanthin for 24 h was 10-fold higher than in the control. Fucoxanthin suppressed the level of Bcl-2 protein. Also, DNA fragmentation induced by fucoxanthin was partially inhibited by a caspase inhibitor Z-VAD-fmk. Moreover, combined treatment with 3.8 microM fucoxanthin and 10 microM troglitazone, which is a specific ligand for peroxisome proliferator-activated receptor (PPAR) gamma, effectively decreased the viability of Caco-2 cells. However, separate treatments with these same concentrations of fucoxanthin nor troglitazone did not affect cell viability. These findings indicate that fucoxanthin may act as a chemopreventive and/or chemotherapeutic carotenoid in colon cancer cells by modulating cell viability in combination with troglitazone.

Antineoplastic Agents↗

PubMed2003

Reagentless and regenerable immunosensor for monitoring of immunoglobulin G based on non-separation immunoassay.

Based on the enhancement of fluorescein isothiocyanate (FITC) fluorescence caused by reactions between proteins, we developed a reagentless, regenerable and rapid immunosensing system to determine immunoglobulin G (IgG). Fluorescence intensity of the immobilized FITC depends on IgG concentration, ranging from 10 to 50 microg/ml, specifically, even with co-existing proteins. The response time is 30 min during steady-state measurement and is less than a minute during transient measurement. When the FITC-labeled protein A binds to IgG, the surrounding atmosphere of FITC becomes hydrophobic. Since the fluorescence intensity of fluorescent substances generally increases at a hydrophobic environment, FITC fluorescence intensity increases with the concentration of protein A bonding to IgG. This system is regenerable because the fluorescence enhancement repeatedly occurs every time the immobilized fluorescent reagent is immersed in sample solutions.

Biosensing Techniques↗