• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.129-135
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• 1994

Acyclic polyether dicarboxylic acid have been studied as metal cation carriers in a bulk liquid membrane system. The proton-ionizable ligands feature allows the coupling of a cation transport to reverse proton transport. This feature offers promise for the effective separation and concentration of metal cations with the metal cation transport being driven by a pH gradient. Metal cation transport increased regularly with increasing hydroxide($H^-$) concentration of source phase and with proton($H^+$) concentration of receiving phase. Competitive transport by the acyclic polyether dicarboxylic acids is selective for calcium ion over other alkaline-earth cations.

• Journal of Plant Biology
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• v.36 no.1
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• pp.67-74
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• 1993

Both polar and gravity-induced lateral transport of auxin was markedly reduced in corn coleoptile segments by octanol treatment. Octanol enhance net auxin uptake without affecting that of benzoic acid, suggesting that the effect did not result from a nonspecific action on general membrane permeability. Since naphthylphthalamic acid (NPA) action on both transport and net uptake of auxin was substantially decreased in the presence of octanol, a specific interaction of octanol with the NPA site (efflux carrier) can be postulated. Studies on in vitro binding of NPA to membrane vesicles indicated that octanol did not interfere with NPA binding. When basipetal transport of auxin was impared by plasmolysis, octanol still inhibited auxin transport in the plasmolyzed tissues. The results ruled out the possibility of octanol acting at the plasmodesmata. Kinetic analysis of growth indicated that IAA-sustained growth was rapidly blocked by octanol implicating a common system by which auxin transport is linked to auxin action. Possible mechanisms for octanol action will be discussed.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.4
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• pp.403-411
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• 1997

To elucidate the mechanism of gentamicin induced renal dysfunction, renal functions and activities of various proximal tubular transport systems were studied in gentamicin-treated rats (Fisher 344). Gentamicin nephrotoxicity was induced by injecting gentamicin sulfate subcutaneously at a dose of 100 $mg/kg{\cdot}day$ for 7 days. The gentamicin injection resulted in a marked polyuria, hyposthenuria, proteinuria, glycosuria, aminoaciduria, phosphaturia, natriuresis, and kaliuresis, characteristics of aminoglycoside nephropathy. Such renal functional changes occurred in the face of reduced GFR, thus tubular transport functions appeared to be impaired. The polyuria and hyposthenuria were partly associated with a mild osmotic diuresis, but mostly attributed to a reduction in free water reabsorption. In renal cortical brush-border membrane vesicles isolated from gentamicin-treated rats, the $Na^+$ gradient dependent transport of glucose, alanine, phosphate and succinate was significantly attenuated with no changes in $Na^+-independent$ transport and the membrane permeability to $Na^+$. These results indicate that gentamicin treatment induces a defect in free water reabsorption in the distal nephron and impairs various $Na^+-cotransport$ systems in the proximal tubular brush-border membranes, leading to polyuria, hyposthenuria, and increased urinary excretion of $Na^+$ and other solutes.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.88-96
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• 2000

The aim of the current study was to evaluate the transport system in EMT-6 cell for the uptake of the methylmercury(MeHg). Several inhibitors ere used to test used to test which potential transport system might be involoved in MeHg uptake. Probenecid was used to test the organic transport system, valinomycin for testing the effect of the membrane potential, cytochalasin B for testing the facilitated diffusive D-glucose transport system and colchicine for testing the microtubule system. Ouabain for evaluating active transport system, 4',4-diisothiocyano-2',2-stilbenedisulfonic acid(DIDS) the Cl- ion transport system and verapamil for the $Ca^{2+}$ transprot system. Significantly, MeHg decreased the synthesis of nitric oxcide(NO) and intracellular ATP in ENT-6 cells. In the condition of ouabain containing with MeHg decreased the production of NO and intracelluar ATP. In the treatment of inhibitors, ouabain showed protective effect against cytotoxicity of MeHg but ather inhibitors not showed protective effects. The protective effects of ouabain against the cytotoxicity of MeHg deoended on the concentration of added ouabain to the culture medium for MET-6 cells. These result showed that the uptake of MeHg might be involved in the active transport system. Active transports system seems to share similarities with the transport systems for the uptake of MeHg when using MeHg and MeHg-glutathione complex.x.

• The Korean Journal of Physiology
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• v.30 no.2
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• pp.279-288
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• 1996

Chronic exposure to cadmium impairs various renal tubular functions, including organic acid (anion) secretion. To investigate the mechanism of cadmium-induced alterations in the organic anion transport system, kinetics of p-aminohippurate (PAH) uptake was studied in renal cortical basolateral membrane vesicles (BLMV) isolated from cadmium-intoxicated rats (adult male Sprague-Dawley). Cadmium intoxication was induced by subcutaneous injections of $CdCl_{2}$ (2 mg Cd/kg per day) for 3 weeks. The renal plasma membrane vesicles were prepared by Percoll gradient centrifugation. The vesicular uptake of $^{14}C$-PAH was determined by rapid filtration technique using Millipore filter. Cadmium intoxication resulted in a marked attenuation of $Na^{+}$-dependent, ${\alpha}$-ketoglutarate (${\alpha}$KG)-driven PAH uptake with no changes in $Na^{+}$ and ${\alpha}$KG-independent transport component. Kinetic analysis indicated that Vmax, but not Km, of the $Na^{+}$-dependent, ${\alpha}$KG-driven component was reduced. A similar reduction of $Na^{+}$-dependent, ${\alpha}$KG-driven PAH uptake was observed in normal membrane vesicles directly exposed to inorganic cadmium in vitro, and this was accompanied by an inhibition of both $Na^{+}$-dependent ${\alpha}$KG uptake and ${\alpha}$KG-PAH exchange activity. These results indicate that during chronic exposure to cadmium, free cadmium ions liberated in the proximal tubular cytoplasm directly interact with the basolateral membrane and impair the active transport capacity for organic anions, most likely due to an inhibition of both $Na^{+}$-dicarboxylate cotransporter and dicarboxylate-organic anion antiporter activities.

• Journal of Acupuncture Research
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• v.18 no.3
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• pp.123-133
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• 2001

Objective : This study was undertaken to determine whether Cordyceps sinensis Sacc. (CSS) extract exerts the protective effect against oxidant-induced alterations in membrane transport function in renal tubules. Methods : Membrane transport fucntion was estimated by examining alterations in p-aminohippurate (PAH) uptake in rabbit renal cortical slices. For induction oxidative stress, slices were treated with an organic peroxide cumene hydroperoxide for 60 min at $37^{\circ}C$. Cumene hydroperoxide inhibited PAH uptake in a time dependent manner. Results : CSS at 0.5-5% concentrations prevented cumene hydroperoxide-induced inhibition of PAH uptake. CSS at 1% also attenuated LDH release and lipid peroxidation induced by cumene hydroperoxide. When slices were treated with 0.2 mM mercury chloride, PAH uptake was inhibited and lipid peroxidation was increased. These changes by mercury were significantly prevented by CSS. Conclusion : These results suggest that CSS prevents oxidant-induced alterations in membrane transport function in rabbit renal cortical slices. Such protective effect of CSS may be attributed to inhibition of peroxidation of membrane lipid.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.338-343
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• 2019

The water transport and water content of the electrolyte membrane greatly affect the performance of the membrane in PEMFC(Proton Exchange Membrane Fuel Cell). In this study, the parameters (electroosmotic coefficient, water diffusion coefficient) of polymer membranes for water transport were measured by a simple method, and water flux and ion conductivity were simulated by using a model equation. One dimensional steady state model equation was constructed by using only the electro-osmosis and diffusion as the driving force of water transport. The governing equations were simulated with MATLAB. The electro-osmotic coefficient of $144{\mu}m$ thick polymer membranes was measured in hydrogen pumping cell, the value was 1.11. The water diffusion coefficient was expressed as a function of relative humidity and the activation energy for water diffusion was $2,889kJ/mol{\cdot}K$. The water flux and ion conductivity results simulated by applying these coefficients showed good agreement with the experimental data.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.51-58
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• 2008

Many researches for effects of different flow configurations on performance of Proton Exchange Membrane Fuel Cell have extensively been done but the effects of flow direction at the same flow channel shape should be considered for optimal operation of fuel cell as well. In this paper a numerical computational methode for simulating entire reactive flow fields including anode and cathode flow has been developed and the effects of different flow direction at parallel flow was studied. Pressure drop along the flow channel and density distribution of reactant and products and water transport, ion conductivity across the membrane and I-V performance are compared in terms of flow directions(co-flow or counter-flow) using above numerical simulation method. The results show that the performance under counter-flow condition is superior to that under co-flow condition due to higher reactant and water transport resulting to higher ion conductivity of membrane.

• Journal of Acupuncture Research
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• v.19 no.4
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• pp.190-199
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• 2002

Objective : This study was performed to determine if Scutellaria balicalensis Georgi extract (SbGE) prevents oxidant-induced membrane transport dysfunction in renal tubular cells. Methods : Membrane transport function was estimated by measuring $Na^+$-dependent inorganic phosphate transport in opossum kidney (OK) cells. $H_2O_2$ inhibited phosphate transport in a dose-dependent manner. Results : The inhibitory effect of $H_2O_2$ was significantly prevented SbGE over concentration range of 0.005-0.05%. $H_2O_2$ caused ATP depletion, which was prevented by SbGE. $H_2O_2$ induced the loss of mitochondrial function as evidenced by decreased MTT reduction and its effect was prevented by SbGE. The $H_2O_2$-induced inhibition of phosphate transport was not affected by a potent antioxidant DPPD, but the inhibition was prevented by an iron chelator deferoxamine, suggesting that $H_2O_2$ inhibits $Na^+$-dependent phosphate transport via an iron-dependent nonperoxidative mechanism in renal tubular cells. Conclusion : These data suggest that SbGE may exert the protective effect against oxidant-induced membrane transport dysfunction by a mechanism similar to iron chelators in renal epithelial cells. However, furher studies should be carried out to find the active ingredient(s) of SbGE that exerts the protective effect.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.05a
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• pp.7-13
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• 2003