Biomedical subjects

Young Min Bae

Publications and source records attributed to Young Min Bae.

10 recordsLinked to original sources

PubMed2006

Serotonin depolarizes the membrane potential in rat mesenteric artery myocytes by decreasing voltage-gated K+ currents.

We hypothesized that voltage-gated K+ (Kv) currents regulate the resting membrane potential (Em), and that serotonin (5-HT) causes Em depolarization by reducing Kv currents in rat mesenteric artery smooth muscle cells (MASMCs). The resting Em was about -40 mV in the nystatin-perforated patch configuration, and the inhibition of Kv currents by 4-aminopyridine caused marked Em depolarization. The inhibition of Ca2+-activated K+ (KCa) currents had no effect on Em. 5-HT (1 microM) depolarized Em by approximately 11 mV and reduced the Kv currents to approximately 63% of the control at -20 mV. Similar 5-HT effects were observed with the conventional whole-cell configuration with a weak Ca2+ buffer in the pipette solution, but not with a strong Ca2+ buffer. In the presence of tetraethylammonium (1mM), 5-HT caused Em depolarization similar to the control condition. These results indicate that the resting Em is largely under the regulation of Kv currents in rat MASMCs, and that 5-HT depolarizes Em by reducing Kv currents in a [Ca2+]i-dependent manner.

4-Aminopyridine↗

PubMed2005

Study on orientation of immunoglobulin G on protein G layer.

A comparative study of immunoglobulin G (IgG) immobilization was performed, both on a thiolated protein G layer, where this immobilization was due to affinity binding with an Fc fragment of IgG, and on 11-mercaptoundecanoic acid (11-MUA), where the immobilization was due to chemical bonding. The change of IgG layer formation on the two base layers as a function of the IgG concentration was investigated by surface plasmon resonance (SPR), atomic force microscopy (AFM) in a non-contact mode, and spectroscopic ellipsometry (SE). It was observed that the IgG layer was immobilized more evenly on the thiolated protein G layer than on the 11-MUA layer, based on the SPR measurements. The surface topology analysis by AFM indicated that the IgG layer was immobilized on the protein G layer according to the envelope profile of the base layer. Based on the SE analysis, it was determined that the IgG layer thickness on the thiolated protein G layer increased with increasing IgG concentration. Based on the above analyses, the scheme for orientation of IgG immobilized on the thiolated protein G layer was proposed.

Biosensing Techniques↗

PubMed2005

Application of a taste evaluation system to the monitoring of Kimchi fermentation.

As an objective method, taste evaluation with an instrument is able to supplement the subjective sensory evaluation and to be applied to the optimization of food processing. Kimchi, a Korean traditional pickle fermented with lactic acid bacteria, is expanding its consumption worldwide. The fermentation control of it has been routinely done by measuring titratable acidity and pH. In this study, an eight-channel taste evaluation system was prepared, followed by an application to the monitoring of Kimchi fermentation. Eight polymer membranes which individually responded to cationic or anionic substances were prepared by mixing electroactive materials such as tri-n-octylmethylammonium chloride, bis(2-ethylhexyl)sebacate as the plasticizer and polyvinyl chloride in the ratio of 1:66:33. Each membrane prepared was separately installed onto the sensitive area of an ion-selective electrode to produce the respective taste sensor. The eight-channel sensor array and a double junction reference electrode were connected to a 16-channel high input impedance amplifier. The amplified sensor signals were stored to a personal computer via a multi-channel A/D converter. Two sensor groups composed of the cation-selective and anion-selective polymer membrane electrodes showed characteristic concentration-dependency to various artificial taste substances. As a whole, the response potentials of the sensor array increased during the fermentation period at 4, 10 and 25 degrees C. Even the response potentials of the anion-selective taste sensors slightly increased possibly due to the protonation of anions by liberated H+ ions, thereby leading to a decrease in the anion concentration. When the signal data were interpreted by principal component analysis (PCA), the first PC at 4 degrees C explained most of the total data variance. A close correlation was found between the values of titratable acidity and the first PC, which indicated a possible applicability of the multi-channel taste sensor of this study to the process monitoring of various pickle.

Biomimetics↗

PubMed2005

The fabrication of protein chip based on surface plasmon resonance for detection of pathogens.

Protein chip based on surface plasmon resonance (SPR) was developed for detection of pathogens existing in contaminated environment, such as Escherichia coli O157:H7, Salmonella typhimurium, Legionella pneumophila, and Yersinia enterocolitica. Protein G was immobilized to endow the orientation of antibody molecules on the SPR surface. The pathogen binding of the protein chip was investigated by SPR spectroscopy. Consequently, it was found that the four kinds of pathogen could be selectively detected by using SPR-based protein chip.

Bacteria↗

PubMed2005

Staurosporine inhibits voltage-dependent K+ current through a PKC-independent mechanism in isolated coronary arterial smooth muscle cells.

We examined the effects of the protein kinase C (PKC) inhibitor staurosporine (ST) on voltage-dependent K (KV) channels in rabbit coronary arterial smooth muscle cells. ST inhibited the KV current in a dose-dependent manner with a Kd value of 1.3 microM. The inhibition of the KV current by ST was voltage-dependent between -30 and +10 mV. The additive inhibition of the KV current by ST was voltage-dependent throughout the activation voltage range. The rate constants of association and dissociation of ST were 0.63 microM s and 0.92 s, respectively. ST produced use-dependent inhibition of the KV current. ST shifted the activation curve to more positive potentials but did not have any significant effect on the voltage dependence of the inactivation curve. ST did not have any significant effects on other types of K channel. Another PKC inhibitor, chelerythrine, and PKA inhibitor peptide (PKA-IP) had little effect on the KV current. These results suggest that ST interacts with KV channels that are in the closed state and that ST inhibits KV channels in the open state in a manner that is phosphorylation-independent and voltage-, time-, and use-dependent.

Algorithms↗

PubMed2004

Detection of insulin-antibody binding on a solid surface using imaging ellipsometry.

Imaging ellipsometry (IE) was used to detect the binding of insulin to its antibody on a solid surface. The modification of a gold surface with 11-mecaptoundecanoic acid (11-MUA), the adsorption of protein G, and antibody immobilization onto the protein G layer were confirmed by surface plasmon resonance. Ellipsometric images and ellipsometric angles of the surface antibody were acquired using the IE system by off-null ellipsometry. Ellipsometric images of antigen binding to the antibody were acquired, and their mean optical intensities estimated. Changes in mean optical intensity indicated that the detection range for insulin was from 10 ng/ml to 100 microg/ml.

Antigen-Antibody Complex↗

PubMed2004

Immunosensor for detection of Yersinia enterocolitica based on imaging ellipsometry.

An immunosensor for the detection of pathogens was developed using imaging ellipsometry (IE) as a detection method. Yersinia enterocolitica was selected as the target pathogen in this study. A gold surface deposited with a self-assembled layer of 11-mercaptoundecanoic acid (11-MUA) was used as a substrate. For the fabrication of the immunosensor, protein G spots were made on the substrate using an inkjet-type microarrayer, and monoclonal antibody (Mab) was adsorbed onto the protein G spots. Deposition of each layer onto the substrate was confirmed by the measurement of surface plasmon resonance. The ellipsometric image of the protein G spot and the Mab-adsorbed protein G spot were acquired using an off-null ellipsometry type of imaging ellipsometry system. By measuring the ellipsometric angles of the protein layers, the surface concentration of each protein layer was calculated. The change in the mean optical intensity of the protein spot to the various concentrations of Y.enterocolitica was estimated. The immunosensor using imaging ellipsometry could successfully detect Y. enterocolitica in concentrations varying from 10(3) to 10(7) cfu/mL. The proposed immunosensor system has the advantage of allowing label-free detection, high sensitivity, and operational simplicity.

Antibody Affinity↗

PubMed2004

Direct block by bisindolylmaleimide of the voltage-dependent K+ currents of rat mesenteric arterial smooth muscle.

We investigated the effect of bisindolylmaleimide (I), a widely used protein kinase C (PKC) inhibitor, on the voltage-dependent K(+) (Kv) currents of rat mesenteric arterial smooth muscle cells using the whole-cell patch-clamp technique. Bisindolylmaleimide (I) reversibly and dose-dependently inhibited the Kv currents with an apparent K(d) value of 0.23+/-0.001 microM. The blockade was apparently through the acceleration of the decay rate of the Kv currents. The apparent rate constants of association and dissociation for bisindolylmaleimide (I) were 17.9+/-1.6 microM(-1) s(-1) and 4.1+/-1.5 s(-1), respectively. The inhibition of Kv current by bisindolylmaleimide (I) was steeply voltage-dependent between -30 and 0 mV (voltage range of channel activation). Bisindolylmaleimide (I) had no effect on the steady-state activation and inactivation of the Kv currents. Applications of trains of pulses at 1 or 2 Hz lead to a progressive increase in the bisindolylmaleimide (I)-blockade, and the recovery from bisindolylmaleimide (I)-block at -80 mV exhibited a time constant of 577.2+/-52.7 ms. Bisindolylmaleimide (V), an inactive analogue of bisindolylmaleimide (I), similarly inhibited the Kv currents with an apparent K(d) value of 1.48+/-0.004 microM, but other PKC inhibitor chelerythrine little affected the Kv currents. These results suggest that bisindolylmaleimide (I) directly inhibits the Kv currents of rat mesenteric arterial smooth muscle cells independently of PKC inhibition, in a state-, voltage-, time- and use-dependent manner.

Animals↗

PubMed2004

Ligusticum wallichi-induced vasorelaxation mediated by mitogen-activated protein kinase in rat aortic smooth muscle.

Traditional herbal medicines have been widely used for the treatment of cardiovascular disorders in oriental countries. To determine the effects of Ch1LW, a chloroform extract of Ligusticum wallichi, on the vascular system, we studied changes in rat aortic smooth muscle in terms of magnitude of contraction and the activity of mitogen-activated protein kinases (MAPKs). Ch1LW inhibited the muscle contraction induced by norepinephrine (NE) in aortic strips. Ch1LW also abolished Ca2+-independent contraction evoked by 12-deoxyphorbol 13-isobutyrate in Ca2+-free medium containing 1 mM EGTA. Furthermore, western blotting analysis using phosphorylated MAPK antibodies showed that NE increased the activity of both extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 MAPK, which were inhibited by PD98059 and SB203580, blockers of ERK1/2 and p38 MAPK, respectively. Furthermore, treatment with Ch1LW significantly abolished NE-mediated activation of ERK1/2, whereas the activity of p38 MAPK was not affected by the extract. These results suggest that Ch1LW induces vasorelaxation in rat aortic smooth muscle, which may be mediated by the inhibition of ERK1/2 pathway, but not p38 MAPK.

Animals↗

PubMed2003

Fabrication of self-assembled protein A monolayer and its application as an immunosensor.

The self-assembled layer of modified protein A was fabricated. In order to modify protein A, the surface group of protein A was substituted with thiol (-SH) functionality by using N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP) and dithiothreitol (DTT). The formation of a self-assembled protein A layer on a Au substrate and its increased binding capacity to antibody were confirmed by surface plasmon resonance (SPR) spectroscopy. The surface structure of self-assembled protein A layer, and the binding status of anti-bovine serum albumin (anti-BSA) and BSA were determined by atomic force microscopy (AFM). Treatment on the self-assembled protein A layer with a detergent, such as Tween 20, increased the binding capacity of anti-BSA, because protein A aggregation was reduced significantly by the detergent; this was confirmed by SPR spectroscopy. The self-assembled layer of chemically modified protein A with enhanced binding capacity can be used for immunosensor fabrication.

Antibodies↗