• Journal of The Korean Astronomical Society
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• v.16 no.1
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• pp.19-22
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• 1983

The reduced profiles of $C_2$ 5150.56, CN 3864.32, MgH 5150.20 and FeI 5150.84 lines, representing the penumbra, the penumbra-umbra boundary and the umbra of spa 6403 have been analyzed by comparing them with the synthetic profiles computed from a set of umbral and penumbral models. The results are presented and discussed. It is suggested that there may be a significant lateral flow of pbotospheric radiation into the umbral and penumbral regions of the sunspots.

• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.441-448
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• 2000

The production and cation flux-mediated activation of the P-type ATPase in Helicobacter pylori was investigated. Using the polymerase chain reaction (PCR), the proton pump genotype of H. pylori was found to be positive for both F-type and P-type ATPases. Yet, their production in terms of enzyme specific activity varied substantially depending on H. pylori strains, ranging over 3-fold. Its main constituent appeared to be the P-type ATPase pool, in contrast to other common bacterial compositions. Interestingly, the F-type ATPase was observed only when intact H. pyloricells were exposed to pH 4.5 or above (37$^{\circ}C$ for 1 h). In contrast, significant amounts of the P-type ATPase still remained after 1 h of cell treatment even at pH below 4.5. By enriching the acidic medium with RPMI(pH 3.0), the P-type ATPase was stabilized, accompained by inactivation of the F-type ATPase. Using H. pylori membrane vesicles, it was found that ammionia-mediated cation flux increased the rate of ATP hydrolysis by the P-type ATPase. Accordingly, these data strongly suggest that the P-type ATPase is involved or functions as an effective regulator for the cation flux across the H. pylori membrane, thereby reducing the risk of excess proton influx.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.2
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• pp.259-265
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• 2017

Excessive influx and the subsequent rapid cytosolic elevation of $Ca^{2+}$ in neurons is the major cause to induce hyperexcitability and irreversible cell damage although it is an essential ion for cellular signalings. Therefore, most neurons exhibit several cellular mechanisms to homeostatically regulate cytosolic $Ca^{2+}$ level in normal as well as pathological conditions. Delayed rectifier $K^+$ channels ($I_{DR}$ channels) play a role to suppress membrane excitability by inducing $K^+$ outflow in various conditions, indicating their potential role in preventing pathogenic conditions and cell damage under $Ca^{2+}$-mediated excitotoxic conditions. In the present study, we electrophysiologically evaluated the response of $I_{DR}$ channels to hyperexcitable conditions induced by high $Ca^{2+}$ pretreatment (3.6 mM, for 24 hours) in cultured hippocampal neurons. In results, high $Ca^{2+}$-treatment significantly increased the amplitude of $I_{DR}$ without changes of gating kinetics. Nimodipine but not APV blocked $Ca^{2+}$-induced $I_{DR}$ enhancement, confirming that the change of $I_{DR}$ might be targeted by $Ca^{2+}$ influx through voltage-dependent $Ca^{2+}$ channels (VDCCs) rather than NMDA receptors (NMDARs). The VDCC-mediated $I_{DR}$ enhancement was not affected by either $Ca^{2+}$-induced $Ca^{2+}$ release (CICR) or small conductance $Ca^{2+}$-activated $K^+$ channels (SK channels). Furthermore, PP2 but not H89 completely abolished $I_{DR}$ enhancement under high $Ca^{2+}$ condition, indicating that the activation of Src family tyrosine kinases (SFKs) is required for $Ca^{2+}$-mediated $I_{DR}$ enhancement. Thus, SFKs may be sensitive to excessive $Ca^{2+}$ influx through VDCCs and enhance $I_{DR}$ to activate a neuroprotective mechanism against $Ca^{2+}$-mediated hyperexcitability in neurons.

• Journal of Microbiology
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• v.41 no.3
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• pp.202-206
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• 2003

A protein, exhibiting a high similarity to the major serine transporter of Escherichia coli, SstT, was found in Haemophilus influenzae Rd. A Na$\^$＋/-stimulated serine transport activity was also detected in the cells. The gene (sstT) for the Na$\^$＋//serine symporter from the chromosome of H. influenzae was cloned, and the properties of the transporter investigated. The serine transport activity was stimulated by Na$\^$＋/. The uptake of Na$\^$＋/ was elicited by the addition of serine or threonine into the cells, supporting the idea that these amino acids are transported by a mechanism of Na$\^$＋//substrate symport. No uptake of H$\^$＋/ was elicited by the influx of serine. The serine transport via the SstT of H. influenzae was inhibited by excess threonine, which was used as another substrate. The $K_{m}$ and the $V_{max}$ values for the serine transport were 2.5 ${\mu}$M and 14 nmol/min/mg protein, respectively.

• Journal of Ginseng Research
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• v.24 no.3
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• pp.138-142
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• 2000

Effects of ginsenosides (Rb$_1$, Rb$_2$, Rc, Re, Rg$_1$, Rf) on L-glutamate (glutamate)-induced swelling of cultured astrocytes from rat brain cerebral cortex were studied. Following the exposure to 0.5mM glutamate for 1 hr, the intracellular water space (as measured by [$^3$H]O-methyl-D-glucose uptake) of astrocytes increased by about two-fold. Simultaneous addition of ginsenosides Rb$_2$ and Rc with glutamate reduced the astrocytic swelling in a dose-dependent manner. These ginsenosides at 0.5 mg/ml did not affect the viability of astrocytes for up to 24 hr which was determined by a colorimetric assay (MTT assay) for cellular growth and survival. These ginsenosides at 0.3 mg/ml inhibited the increase of intracellular Ca$\^$2+/ concentration ([Ca$\^$2+/]$\_$i/) induced by glutamate. These data suggest ginsenosides Rb$_2$ and Rc prevent the cell swelling of astrocytes induced by glutamate, maybe via inhibition of Ca$\^$2+/ influx.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1B
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• pp.79-84
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• 2012

Nitrate is a common contaminant in groundwater aquifer. The present study investigates the performance of the bipolar zero valent iron (ZVI, $Fe^0$) packed bed electrolytic cell in removing nitrate in different operating conditions. The packing mixture consists of ZVI as electronically conducting material and silica sand as non-conducting material between main cathode and anode electrodes. In the continuous experiments for the simulated wastewater (contaminated groundwater, initial nitrate about 30 mg/L as N and electrical conductivity about 300 ${\mu}S/cm$), over 99% removal of nitrate was achieved in the applied voltage 600 V and at the flow rate of 20 mL/min. The optimum packing ratio (v/v) and flow rate were determined to be 1:1~2:1 (silica sand to ZVI), 30 mL/ min respectively. Effluent pH was proportional to nitrate influx concentration, and ammonia which is the final product of nitrate reduction was about 60% of nitrate influx. Magnetite was observed on the surface of the used ZVI as major oxidation product.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.4
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• pp.411-419
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• 2003

Dredged material during Masan Bay cleaning in 1990-1994 was deposited in Gapo area. The site provides an ideal experimental condition to monitor environmental remediation and benthic ecosystem stabilization processes after the disturbance. Sea water samples were taken during one tidal cycle in one hour interval from Oct. 2001 to Apr. 2002 (4 times) to estimate the organic matter and nutrient fluxes in Gapo area. Hourly material fluxes were estimated from the water balance estimated from 3 dimensional topography of Gapo area and from material concentration. Net material fluxes were estimated from the difference between total influx and total outflux during one tidal cycle. Chemical oxygen demand showed net outflux in Nov. 2001, Dec. 2001 and Apr. 2002 (2.2∼3.9 g m$\^$-2/ h$\^$-1/) and showed net influx in Mar. 2002 (1.4 g m$\^$-2/ h$\^$-1/). Ammonium showed net outflux during the study (0.1∼118 mg m$\^$-2/ h$\^$-1/m-2h-I). According to this investigation, Gapo area was a source rather than a sink of organic matter. However, the variability of the material fluxes was high so that a long term study may be required.

• The Korean Journal of Physiology
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• v.23 no.1
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• pp.23-34
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• 1989

Gentamicin (GM) is a polybasic, aminoglycoside antibiotic used frequently for the treatment of serious gram-negative infections. The major limiting factors in the clinical use of GM as well as other aminoglycoside antibiotics are their nephrotoxicity and ototoxicity. The primary mechanism of cell injury in aminoglycoside toxicity appears to be the disruption of normal membrane function and the inhibition of $Na^{+}-K^{+}$ ATPase activity. There are both indirect and direct evidences which suggests that the effect of aminoglycoside antibiotics on $Na^{+}-K^{+}$ ATPase may explain, or contribute to, their toxicity. It has been shown that aminoglycoside reduce total ATPase activity (Kaku et al., 1973) and $Na^{+}-K^{+}$ ATPase activity (linuma et al., 1967) in the stria vascularis and spiral ligament of the guinea-pig cochlea. Lipsky and Lietman (1980) reported that aminoglycoside antibitoics inhibited the activity of $Na^{+}-K^{+}$ ATPase in microsomal fractions of the cortex and medulla of the guinea-pig kidney, isolated rat renal tubule and human erythrocyte ghosts. The present invstigation was undertaken to elucidate the mechanism of GM on human erythrocytes by examining its effect on $Na^{+}-K^{+}$ ATPase activity, actives sodium and potassium transport across red blood cell and $^{3}H-ouabain$ binding to red blood cell membranes. The results obtained are summarized as follows: 1) CM inhibited significantly both the activity of total ATPase and $Na^{+}-K^{+}$ ATPase at all concentrations tested. 2) GM inhibited active $^{22}Na$ efflux across red blood cell. When ouabain is present, the rate of $^{22}Na$ efflux was completely inhibited. When both GM and ouabain were added, the inhibitory effect of active $^{22}Na$ efflux was more pronounced. 3) Active $^{86}Rb$ influx was inhibited significantly by GM. In the presence of ouabain, the rate of $^{86}Rb$ influx is markedly inhibited. But $^{86}Rb$ influx is not appreciably altered by the presence of both GM and ouabain. 4) In the presence of GM, $^{3}H-ouabain$ binding to red blood cell membrane increased. From the above results, it may be concluded that the inhibition of active sodium and potassium transport across red blood cell by gentamicin appears to be due to the inhibition of $Na^{+}-K^{+}$ ATPase activity and an increase in ouabain binding to red blood cell membranes.

• Toxicological Research
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• v.14 no.3
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• pp.349-356
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• 1998

We identified S9940, a novel microbial metabolite from Streptomyces spp., to inhibit the release of neurotransmitter from PC12 cells. S9940 is an inhibitor of trifiated norepinephrine ([$^{3}H$]-NE) release in high $K^+$ buffer solution containing ionomycin, indicating that S9940 inhibits neurotransmitter release after the influx of $Ca^{2+}$ ions. We also examined the effect of S9940 on $\beta-glucuronidase$ release from guinea pig neurophils and the effect on the neurite extension of PC12 cells and rat hippocampal neurons. As a result, S9940 inhibited $\beta-glucuronidase$ release: when treated with $5{\mu}g/ml$ of S9940, which prevented [$^{3}H$]-NE release, the inhibition of neurite extension for both PC12 cells and rat hippocampal neurons was observed.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.324-330
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• 1990

The distribution of physicochemical environmental factors and microbiological factors was studied at 6 sampling sites in Kyeongge Bay of Yellow Sea from October 1989 to October 1990. The total bacterial number, saprophytic bacterial number, petroleum-degrading bacterial number, bacterial biomass, and bacterial secondary production were measured in the range of 0.09~1.24*10$^{7}$ cells/ml, 7~60000 CFUs/ml, 0~240 cells/ml, 14.16~301 .$\mu$g-C/l, and 0.13~11.82 mg-C/m$^{3}$/hr, respectively. The turnover times of $^{3}$H-glucose and $^{3}$H-acetate were in range of 6.5~6984 and 41~24897 hours, respectively. The spatial distribution of heterotrophic bacterial communities were hightly affected by influx of organic pollutants from the coastal area and the seawater exchange with offshore.