Biomedical subjects

Eunjung Ko

Publications and source records attributed to Eunjung Ko.

10 recordsLinked to original sources

PubMed2006

Highly convergent three component benzyne coupling: the total synthesis of ent-clavilactone B.

The first total synthesis of (+)-clavilactone B, a potent antifungal agent and novel tyrosine kinase inhibitor, is described. The absolute configuration of clavilactones has been unambiguously established by using Sharpless asymmetric epoxidation to generate the enantiomerically pure substrate. The strategy highlights the use of a powerful and convergent three-component benzyne coupling with a methylallyl Grignard and a chiral epoxy-aldehyde to generate two C-C bonds and install the carbon skeleton of clavilactone. Oxidative lactonization, ten-membered ring construction by ring closing metathesis, and oxidation gave clavilactone B.

Benzene Derivatives↗

PubMed2005

Ab Initio simulations of nonstoichiometric Cd(x)Te(1-x) liquids.

We present ab initio molecular-dynamics simulations for Cd(x)Te(1-x) liquids where the composition is nonstoichiometric. The simulations are performed following Born-Oppenheimer molecular dynamics. The required forces are obtained from a solution of the Kohn-Sham equation using ab initio pseudopotentials. We consider stoichiometries of the form: Cd(x)Te(1-x), where x=0.2, 0.4, 0.6, and 0.8. For each composition of the melt, we consider a range of temperatures near the experimentally determined liquid temperatures. We examine the microstructural properties of the melt, the viscosity, and self-diffusion properties of the liquid as a function of the stoichiometry and temperature. We also perform an analysis of the distribution of the electronic density of states in these liquids. We find that structural changes in the local order, experimentally predicted to occur when the concentration of Cd is increased, are closely related to changes in the electronic properties of the melt.

Journal Article↗

PubMed2005

Bee venom modulates murine Th1/Th2 lineage development.

Administration of bee venom (BV) elicits anti-inflammatory, anti-nociceptive and anti-allergic effects in various animal models. This study was designed to evaluate the direct effects of BV on helper T cell activities and on Th1/Th2 lineage development using both in vitro and in vivo conditions. In the Th1 skewed condition, BV increased the expression of IFN-gamma mRNA and enhanced the expression of T-bet on purified CD4(+) T cells from splenocytes of BALB/c mice. On the other hand, BV treatment did not alter the expression of IL-4 or GATA-3 in a Th2 driven environment. To elucidate the effects of BV on Th1/Th2 lineage development under in vivo conditions, BV was given by intraperitonial injection to BALB/c mice. It significantly increased the CD4(+) T cell population and enhanced IFN-gamma expression, while IL-4 transcripts were not altered upon in vivo activation using an anti-CD3 antibody injection. Taken together, these results imply that BV induces Th1 lineage development from CD4(+) T cells by increasing the expression of a Th1-specific cytokine, IFN-gamma. In addition, this result may be mediated by inducing a Th1-specific transcription factor, T-bet.

Animals↗

PubMed2004

Viscosities of liquid CdTe near melting point from ab initio molecular-dynamics calculations.

Recent experimental results for the viscosity of liquid CdTe exhibit disparate behavior as a function of temperature. While some measurements show the expected Arrhenius-type behavior, other measurements show an anomalous temperature dependence indicating an increase in viscosity with increasing temperature. We present ab initio molecular-dynamics simulations of liquid cadmium telluride near its melting point and use the Stokes-Einstein relation to extract values of the viscosity constant. We find no anomalous behavior; the viscosity decreases monotonically with temperature and is consistent with an Arrhenius like behavior. Although calculated values are slightly smaller than those measured, the predicted activation energy agrees well with experiment.

Journal Article↗

PubMed2004

Ginsenoside Rg1 enhances CD4(+) T-cell activities and modulates Th1/Th2 differentiation.

Panax ginseng is commonly used as a tonic medicine in Asian countries such as Korea, China, and Japan. It has been reported that ginsenoside Rg1 in P. ginseng increases the proportion of T helper (Th) cells among the total number of T cells and promotes IL-2 gene expression in murine splenocytes. This implies that ginsenoside Rg1 increases the immune activity of CD4(+) T cells, however, the exact mechanism remains unknown. The present study elucidated the direct effect of Rg1 on helper T-cell activities and on Th1/Th2 lineage development. The results demonstrated that ginsenoside Rg1 had no mitogenic effects on unstimulated CD4(+) T cells, but augmented CD4(+) T-cell proliferation upon activation with anti-CD3/anti-CD28 antibodies in a dose-dependent manner. Rg1 also enhanced the expression of cell surface protein CD69 on CD4(+) T cells. In Th0 condition, ginsenoside Rg1 increases the expression of IL-2 mRNA, and enhances the expression of IL-4 mRNA on CD4(+) T cells, suggesting that Rg1 prefers to induce Th2 lineage development. In addition, ginsenoside Rg1 increases IL-4 secretion in CD4(+) T cells under Th2 skewed condition, while decreasing IFN-gamma secretion of cells in Th1 polarizing condition. Thus, Rg1 enhances Th2 lineage development from the naïve CD4(+) T cell both by increasing Th2 specific cytokine secretion and by repressing Th1 specific cytokine production. Therefore, these results suggest that ginsenoside Rg1 is a desirable agent for enhancing CD4(+) T-cell activity, as well as the correction of Th1-dominant pathological disorders.

Animals↗

PubMed2004

Traditional Korean medicine (SCRT) modulate Th1/Th2 specific cytokine production in mice CD4+ T cell.

Traditional Korea medicine, So-Cheong-Ryong-Tang (SCRT) also called as Xiao-qing-long-tang or Sho-seiru-to, contains eight species of medicinal plants and has been used for treating allergic diseases, such as allergic rhinitis and asthma, for hundreds of years in Asian countries. CD4+ T cells were highly purified by using magnetic bead from splenocytes of BALB/c mice. SCRT treatment slightly decreased the expression of cell surface protein CD69 on CD4+ T cell in the flow cytometry analysis. In RT-PCR analysis, SCRT increases the expression of IL-2 and IL2R-alpha mRNA, and decreases the expression of IL-4 mRNA, which is an important cytokine of Th2 cell development. On the other hand, SCRT treatment increases IFN-gamma expression, which is one of the key cytokines for Th1 cell development. Present study implies that SCRT can correct Th2 dominant condition directly affecting to the CD4+ T cell without significantly depressing general T cell activities. These results also suggest that the effect on CD4+ T cell may be the one of key pharmacological effect point for treating IgE medicated allergic asthma by SCRT.

Adjuvants, Immunologic↗

PubMed2004

Suppression of IgE production and modulation of Th1/Th2 cell response by electroacupuncture in DNP-KLH immunized mice.

Effects of electroacupuncture (EA) on Th1/Th2 cell response were investigated in BALB/c mice immunized intraperitoneally with 2,4-dinitrophenylated keyhole limpet protein (DNP-KLH). Successive electroacupuncture stimulation on the ST36 acupoint was performed just after immunization. Serum levels of antigen-specific IgE and total IgE were significantly decreased compared with non-acupunctured controls. Production of the Th2-specific cytokines IL-4 and IL-13 in the anti-CD3 mAb-activated splenocytes was significantly suppressed in ST36 electroacupunctured mice compared with non-acupunctured mice. These results imply that successive electroacupuncture on ST36 can decrease the serum level of antigen-specific IgE and total IgE by suppression of the Th2 lineage development.

Animals↗

PubMed2004

So-Cheong-Ryong-Tang, tradititional Korean medicine, suppresses Th2 lineage development.

The present study was designed to evaluate the effect of So-Cheong-Ryong-Tang (SCRT, also called Sho-Seiryu-To or Xiao-Qing-Long-Tang) on helper T cell development by monitoring Th1/Th2-specific cytokine secretion patterns in artificially induced Th1 or Th2 polarized conditions. The results demonstrated that Th2 cells were dramatically underpopulated in the Th2-driven condition triggered by SCRT treatment, while the Th1 cells were not altered in the Th1-skewed condition. Furthermore, under Th2-skewed conditions the levels of interleukin-4 were considerably decreased with SCRT treatment. The expression of GATA-3, a transcription factor that plays a pivotal role in Th2 lineage programming, did not change with SCRT treatment, while the expression of another Th2 transcription factor, c-Maf, was dramatically suppressed. These data suggest that SCRT modulates Th2 development by suppressing c-Maf expression. This study implies that the SCRT effect on CD4(+) T cells is a key pharmacologic point of effect for treating IgE-mediated allergic asthma. These results also suggest that SCRT might be a useful agent for the correction of Th2-dominant pathologic disorders.

Animals↗

PubMed2004

Chung-Yeul-Gue-Soup-Sa-Gan-Tang, traditional Korean medicine, enhances CD4(+) T cell activities and modulates Th1/Th2 lineage development.

Chung-Yeul-Gue-Soup-Sa-Gan-Tang (CYT), a traditional Korea herbal medicine, has been widely used in Korea for the treatment of various immunological disorders, including allergic asthma. In this study, CYT was examined in vitro and tested for possible immunological effects. The results demonstrated that CYT had no mitogenic effects on unstimulated CD4(+) T cells, but rather increased CD4(+) T cell proliferation upon activation with anti-CD3/CD28 antibody. Under the Th0 condition, CYT also enhanced expression of interleukin (IL)-2 in purified murine CD4(+) T cells assayed by real-time PCR, suggesting that CYT moderately increases the activity of helper T cells upon T cell receptor ligation under the neutral condition. However, the Th1 cells were overpopulated following CYT treatment under the Th1 condition, while Th2 cells were under-populated in the Th2 driven condition. In addition, under Th1/Th2-skewed conditions, the levels of IL-4 were considerably decreased, while the expression of T-bet and interferon-gamma were increased with CYT treatment. Thus, CYT enhances Th1 lineage development from naive CD4(+) T cells both by increasing Th1 specific cytokine secretion and repressing Th2 specific cytokine production. These results suggest that CYT is a desirable agent for the correction of Th2 dominant pathological disorders.

Animals↗

PubMed2002

Highest electron affinity as a predictor of cluster anion structures.

Small clusters have a range of unique physical and chemical phenomena that are strongly size dependent. However, analysis of these phenomena often assumes that thermodynamic equilibrium conditions prevail. We compare experimentally measured and ab initio computed photoelectron spectra of bare and deuterated silicon cluster anions produced in a plasma environment. We find that the isomers detected experimentally are usually not the ground-state isomers, but metastable ones, which indicates that cluster relaxation is strongly limited kinetically by a dwell time that is much shorter than the relaxation time. We show that, under these conditions, the highest electron affinity replaces the traditional lowest total energy as the appropriate criterion for predicting isomer structures. These findings demonstrate that a stringent examination of non-equilibrium effects can be crucial for a correct analysis of cluster properties.

Journal Article↗