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세포 밖 2가 양이온이 과분극에 의해 활성화되는 전류(Ih)에 미치는 영향
곽지연(Jiyeon Kwak) 대한약학회 2012 약학회지 Vol.56 No.2
The hyperpolarization-activated current (Ih) is an inward cation current activated by hyperpolarization of the membrane potential and plays a role as an important modulator of action potential firing frequency in many excitable cells. In the present study we investigated the effects of extracellular divalent cations on Ih in dorsal root ganglion (DRG) neurons using whole-cell voltage clamp technique. Ih was slightly increased in Ca2+-free bath solution. BAPTA-AM did not change the amplitudes of Ih. Amplitudes of Ih were decreased by Ca2+, Mg2+ and Ba2+ dose-dependently and voltage-independently. Inhibition magnitudes of Ih by external divalent cations were partly reversed by the concomitant increase of extracellular K+ concentration. Reversal potential of Ih was significantly shifted by Ba2+ and V1/2 was significantly affected by the changes of extracellular Ca2+ concentrations. These results suggest that Ih is inhibited by extracellular divalent cations (Ca2+, Mg2+ and Ba2+) by interfering ion influxes in cultured rat DRG neurons.
Kwak Nakwon,Lee Kyoung-Hee,Woo Jisu,Kim Jiyeon,Lee Chang-Hoon,Yoo Chul-Gyu 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-
Inflammation, oxidative stress, and protease–antiprotease imbalance have been suggested to be a pathogenic triad in chronic obstructive pulmonary disease (COPD). However, it is not clear how proteases interact with components of inflammatory pathways. Therefore, this study aimed to evaluate the effect of neutrophil elastase (NE) on lipopolysaccharide (LPS)-induced interleukin 8 (IL-8) production and determine the molecular mechanism in human bronchial epithelial cells (HBECs). Immortalized bronchial epithelial cells and primary HBECs were used to investigate the impact of NE on LPS-induced IL-8 production. The molecular mechanism by which NE modulated LPS-induced IL-8 production was confirmed in elastase-treated C57BL/6 mice and primary HBECs obtained from COPD patients and healthy controls. The results showed that NE treatment synergistically augmented LPS-induced IL-8 production in both immortalized bronchial epithelial cells and primary HBECs. NE partially degraded peroxisome proliferator-activated receptor gamma (PPARγ), which is known to regulate IL-8 production in the nucleus. Treatment with a PPARγ agonist and overexpression of PPARγ reversed the NE-induced synergistic increase in LPS-induced IL-8 production. Moreover, PPARγ levels were lower in lung homogenates and lung epithelial cells from elastase-treated mice than in those from saline-treated mice. In accordance with the findings in mice, PPARγ levels were lower in primary HBECs from COPD patients than in those from healthy never-smokers or healthy smokers. In conclusion, a vicious cycle of mutual augmentation of protease activity and inflammation resulting from PPARγ degradation plays a role in the pathogenesis of COPD.
Kwak, Moo Jin,Oh, Myung Seok,Yoo, Youngmin,You, Jae Bem,Kim, Jiyeon,Yu, Seung Jung,Im, Sung Gap American Chemical Society 2015 Chemistry of materials Vol.27 No.9
<P>Exquisite surface wettability control of separation system surface is required to achieve separation of liquids with low surface tension difference. Here, we demonstrate a series of surface-energy-controlled homogeneous copolymer films to control the surface wettability of polyester fabric, utilizing a vapor-phase process, termed as initiated chemical vapor deposition (iCVD). The homogeneous copolymer films consist of a hydrophobic polymer, poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane), pV4D4, and a hydrophilic polymer, poly(4-vinylpyridine), p4VP. Because the mixing of two or more components is always favorable in vapor phase, the iCVD process allows the formation of homogeneous copolymers from two immiscible, hydrophilic/hydrophobic monomer pairs, which is highly challenging to achieve in liquid phase. Simply by tuning the flow rate ratio of monomer pairs, a series of homogeneous copolymers with systematically controlled surface energy were formed successfully. The fabricated separation system could separate water (surface energy = 72.8 mJ/m<SUP>2</SUP>), glycerol (64 mJ/m<SUP>2</SUP>), ethylene glycol (48 mJ/m<SUP>2</SUP>), and olive oil (35.1 mJ/m<SUP>2</SUP>) sequentially with excellent selectivity, just by choosing a copolymer-coated polyester fabric with proper surface energy. Considering the small differences in the surface tension of the liquids used in this work, the surface-energy-controlled separation system can be a powerful tool to separate various kinds of liquid mixtures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-9/acs.chemmater.5b00842/production/images/medium/cm-2015-00842c_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b00842'>ACS Electronic Supporting Info</A></P>
Jiyeon Kim,Byeong Sub Kwak,강미숙 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.2
The improved photocatalytic performance of a carbon/TiO2 composite was studied for the Bisphenol A (BPA) decomposition. Titanium tetraisopropoxide (TTIP) and a rice husk from Korea were heterogeneously mixed as the titanium and carbon sources, respectively, for 3 h at room temperature, and then thermally treated at 600 oC for 1 h in H2 gas. The transmission electron microscopy (TEM) images revealed that the bulk carbon partially covered the TiO2 particles, and the amount that was covered increased with the addition of the rice husk. The acquired carbon/TiO2 composite exhibited an anatase structure and a novel peak at 2θ = 32o, which was assigned to bulk carbon. The specific surface area was significantly enhanced to 123 ~ 164 m2/g in the carbon/TiO2 composite, compared to 32.43 m2/g for the pure TiO2. The X-ray photoelectron spectroscopy (XPS) results showed that the Ti-O bond was weaker in the carbon/TiO2 composite than in the pure TiO2, resulting in an easier electron transition from the Ti valence band to the conduction band. The carbon/TiO2 composite absorbed over the whole UV-visible range, whereas the absorption band in the pure TiO2 was only observed in the UV range. These results agreed well with an electrostatic force microscopy (EFM) study that showed that the electrons were rapidly transferred to the surface of the carbon/TiO2 composite compared to the pure TiO2. The photocatalytic performance of the BPA removal was optimized at a Ti:C ratio of 9.5:0.5, and this photocatalytic composite completely decomposed 10.0 ppm BPA after 210 min, whereas the pure TiO2 achieved no more than 50% decomposition under any conditions.
Enhanced Hydrogen Production from Methanol/Water Photo-Splitting in TiO2 Including Pd Component
Byeong Sub Kwak,Jinho Chae,Jiyeon Kim,강미숙 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.5
The future use of hydrogen as an energy source is expected to increase on account of its environmentally friendliness. In order to enhance the production of hydrogen, Pd ions (0.01, 0.05, 0.1, and 0.5 mol%) were incorporated TiO2 (Pd-TiO2) and used as a photocatalyst. The UV-visible absorbance decreased with increasing level of palladium incorporation without a wavelength shift. Although all the absorption plots showed excitation characteristics, there was an asymmetric tail observed towards a higher wavelength caused by scattering. However, the intensity of the photoluminescence (PL) curves of Pd-TiO2 was smaller, with the smallest case being observed at 0.1 and 0.5 mol% Pd-TiO2, which was attributedto recombination between the excited electrons and holes. Based on these optical characteristics, the evolution of H2 from methanol/water (1:1) photo-splitting over Pd-TiO2 in the liquid system was enhanced, compared with that over pure TiO2. In particular, 2.4 mL of H2 gas was produced after 8 h when 0.5 g of a 1.0 mol% Pd-TiO2 catalyst was used. H2 was stably evolved even after 28 h without catalytic deactivation, and the amount of H2 produced reached 14.5 mL after 28 h. This is in contrast to the case of the Pd 0.1 mol% impregnated TiO2 of H2 evolution of 17.5 mL due to the more decreasedelectron-hole recombination.