• Journal of the Korean Electrochemical Society
• /
• v.15 no.1
• /
• pp.54-66
• /
• 2012

The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

• BMB Reports
• /
• v.46 no.12
• /
• pp.611-616
• /
• 2013

Luteolin-7-O-glucoside (LUT7G), a flavone subclass of flavonoids, has been found to increase anti-oxidant and anti-inflammatory activity, as well as cytotoxic effects. However, the mechanism of how LUT7G induces apoptosis and regulates cell cycles remains poorly understood. In this study, we examined the effects of LUT7G on the growth inhibition of tumors, cell cycle arrest, induction of ROS generation, and the involved signaling pathway in human hepatocarcinoma HepG2 cells. The proliferation of HepG2 cells was decreased by LUT7G in a dose-dependent manner. The growth inhibition was due primarily to the G2/M phase arrest and ROS generation. Moreover, the phosphorylation of JNK was increased by LUT7G. These results suggest that the anti-proliferative effect of LUT7G on HepG2 is associated with G2/M phase cell cycle arrest by JNK activation.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.27 no.1
• /
• pp.43-48
• /
• 2013

Cisplatin is a anti-neoplastic agent which is commonly used for the treatment of solid tumor. Cisplatin activates multiple signal transduction pathways involved in the stress-induced apoptosis in a variety of cell types. Previous study reported that cisplatin induces apoptosis through activation of ERK, p38 and JNK in rat mesangial cells, but apoptotic pathway remain known. The present study investigated the apoptotic pathway for cisplatin-indcued apoptosis in rat mesangial cells. cisplatin-induced apoptosis was associated with activation of caspase-3, caspase-8, caspase-9. Caspase-8 inhibition prevented the activation of both caspase-3 and caspase-9. In addition, cisplatin-induced apoptosis increased the expression of Bax, but not the level of Bcl-2. These change of Bax/bcl-2 ratio caused the release of cytochrome c from mitochondria into cytosol. In previous study, the ethanol extract of Bojungbangam-tang (EBJT) inhibited cisplatin-induced apoptosis in rat mesangial cells through inhibition of ERK and JNK activation. However, EBJT did not increase cell proliferation, because it did not prevent cisplatin-induced G2/M phase arrest. These effect of EBJT may be related to p38 activation. Cisplatin-induced G2/M phase arrest are inhibited by treatment with p38 inhibitor and EBJT in rat mesangial cells. Also, p38 inhibition and EBJT treatment on cisplatin-induced G2/M phase arrest are markedly increased the G0/G1 phase and reduced the sub-G1. In conclusion, anti-apoptotic effet of EBJT did not increases cell proliferation, because EBJT did not reduce p38 activation related to cisplatin-induced G2/M phase arrest.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.6
• /
• pp.853-858
• /
• 2003

The reaction mechanism of the pyrolysis of sulphonyl oximes ($CH_3-C_6H_4-S(O)_2O-N=C(H)-C_6H_4Y$), in the gas phase is studied theoretically at HF/3-21G, ONIOM (B3LYP/6-31G**:HF/3-21G) and ONIOM (MP2/6- 31G**:HF/3-21G) levels. All the calculations show that the thermal decomposition of sulphonyl oximes is a concerted asynchronous process via a six-membered cyclic transition state. The activation energies (Ea) predicted by ONIOM (B3LYP/6-31G**: HF/3-21G) method are in good agreement with the experimental results for a series of tosyl arenecarboxaldoximes. Five para substituents, Y = $OCH_3$, $CH_3$, H, Cl, and $NO_2$, are employed to investigate the substituent effect on the elimination reaction. Linear Hammett correlations are obtained in all calculations in contrast to the experimental finding.

• Journal of the Korean Society of Tobacco Science
• /
• v.28 no.2
• /
• pp.152-157
• /
• 2006

A new procedure has been developed for the quantitation of aromatic amines in mainstream cigarette smoke. Two solid-phase extraction (SPE) clean up steps, using a different retention mechanisms, are required to process the samples. The first step used a cation-exchange cartridge, followed by a second step that used a cartridge with a hydrophobic retention character. The aromatic amines eluted from the second SPE cartridge are derivatized with pentafluoropropionic anhydride. This new method have advantages over other reported techniques, being sensitive, robust, and easily automated. The detection limits were ranged from 0.12 ng/mL for 1-aminonaphthalene to 0.16 ng/mL for 3-aminobiphenyl and the recoveries were from 97 to 106%. Compared with other reports for analysis of 2R4F reference cigarette, this method shows a close analytical data and good repeatability.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.2
• /
• pp.263-266
• /
• 2004

A sensitive, selective and rapid method has been developed for the determination ${\mu}$g/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with $C_{18}$ cartridge. The QADEAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH = 3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1 : 2 (V(V) to QADEAP). This chelate was enriched by solid phase extraction with $C_{18}$cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is $1.28 {\times}10^5L\;mol^{-1}cm^{-1}$ at 590 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.6 ${\mu}$g/mL. The detection limit is 0.04 ${\mu}$g/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.14 no.2
• /
• pp.59-67
• /
• 2000

In this paper, an ozonizer, which can supply individual and superposed silent discharge using three-phase voltage has been designed and manufactured. The ozonizer consists of 3 electrodes(Central Electrode, Internal Electrode and External Electrode and External electrode) and 2 gaps (gap between Central Electrode and Internal Electrode, gap between Internal Electrode and External Electrode). Ozone is generated according to voltage supplying method to each electrode by individual silent discharge and three-phase superposed discharge. The characteristics of ozone generation were investigated with variation of discharge power and the flow rate of supplied gas (O2). In case of individual silent discharge, the maximum values of ozone concentration, ozone generation and ozone yield were obtained between internal electrode and external electrode, and its values were 2300[ppm], 570[mg/h] and 745[g/kWh] respectively. Each maximum value was 5039[ppm], 1773[mg/h] and 851[g/kWh] respectively, when three-phase superposed silent discharge was employed. Therefore, characteristics of ozone generation with three-phase voltage are improved compared with single-phase voltage because silent discharge is generated continuously.

• Radiation Oncology Journal
• /
• v.17 no.3
• /
• pp.223-229
• /
• 1999

Purpose : The expression pattern of c-jun by ionizing radiation according to cell growth state (exponential growth vs. stationary phase) and its relationship with cell cycle redistribution were investigated. Materials and Methods : The exponential growth phase (day 4) and stationary phase (day 9) cells were determined from cell growth curve according to the elapse of days in CaSki. The cells were irradiated using 6 MV X-ray with a dose of 2 Gy at a fixed dose rate of 3 Gy/min. Northern blot analysis was peformed with total cellular RNA and cell cycle distribution was analyzed using flow cytometry according to time-course after irradiation. Results : The maximum expression of c-jun occurred 1 hour after irradiation in both exponential growth and stationary phase cells. After then c-jun expression was elevated upto 6 hours in exponential growth phase cells, but the level decreased in stationary phase cells. Movements of cells from G0-G1 to S, G2-M phase after irradiation were higher in exponential growth phase than stationary phase. Conclusion : c-jun may be involved in the regulation of cellular proliferation according to the growth states after irradiation.

• Archives of Pharmacal Research
• /
• v.23 no.4
• /
• pp.349-352
• /
• 2000

A reversed-phase high performance liquid chromatographic method was developed to determine salidroside and tyrosol simultaneously in the Rhodiola rosea. The optimum condition was Nova-pak $C_18$as stationary phase, 6.5% methanol in water as mobile phase and detection at UV 225 nm. The identification was carried out by comparing the retention time and LC/MS spectrum of the relevant peaks with those of isolated standards. The contents of salidroside and tyrosol in the samples gathered from various area in China were ranged over 1.3-11.1 ${m}g/g$ and 0.3-2.2 ${m}g/g$, respectively.

• Environmental Mutagens and Carcinogens
• /
• v.9 no.1
• /
• pp.13-22
• /
• 1989

The effect of novobiocin (NOV), and inhibitor of topoisomerase II, on ethyl methanesulfonate (EMS)-or bleomycin (BLM)-induced DNA repair synthesis was examined during the cell cycle of Chinese hamster ovary (CHO)-K1 cells. Three assays were employed in this study: cell survival, alkaline elution and unscheduled DNA synthesis. EMS was effective at killing CHO cells in G1 phase, wheras BLM preferentially killed cells in G2 and S phases. EMS induced the much more amount of DNA damage in G1 phase, while BLM induced in G2 phase than the other phases. The both of pre- and post-treatment with BOV inhibitied EMS- or BLM-induced DNA repair synthesis in G1 and G2 phases, and pretreatment with NOV inhibited more effectively than the post-treated group. These results suggested that CHO cells exhibited a differential sensitivity to cell lethality and DNA damage in relation to cell cycle according to used chemical agents, and that DNA topoisomerase II participated in an initial stage of DNA repair.