• Journal of Pharmaceutical Investigation
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• v.22 no.4
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• pp.289-300
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• 1992

The counter-transport phenomena in the hepatic transport of 1-anilino-8-naphthalene sulfonate (ANS) were kinetically investigated by analyzing the plasma disappearance-time profiles and the transport into the isolated hepatocytes. In vivo "counter transport phenomena" were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of counter-transport phenomenon. To examine the inhibitory effects on the initial uptake of a ligand by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. The initial plasma disappearance curves of ANS were then kinetically analyzed based on a two-compartment model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). No effects on the initial plasma disappearance rates of ANS were observed after preloading of bromophenol blue (BPB) or rose bengal (RB) in the liver. Inhibitory effect of BPB or RB on the initial uptake (or efflux) rates of ANS by the isolated hepatocytes were not observed, suggesting that the true counter transport mechanism is not working. In conclusion, checking the preloading effects of transstimulation on the initial uptake of a ligand by the liver could be a useful criterion for carrier cycling and common use of the same carrier between two ligands. However, one cannot exclude those possibilities even if the preloading effects cannot be observed.

• YAKHAK HOEJI
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• v.47 no.2
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• pp.110-119
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• 2003

The purpose of the present study was to kinetically investigate the carrier-mediated uptake in the hepatic transport of organic anions, and to simulate the ″in vivo counter-transport″ phenomena, using kinetic model which was developed in this study. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of ″counter-transport″ phenomenon. To examine the inhibitory effects on the initial uptake of a ligand by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. The initial plasma disappearance curves of a organic anion were then kinetically analyzed based on a flow model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). Moreover, ″in vive counter-transport″ phenomena were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The ″in vivo counter-transport″ phenomena in the hepatic transport of a organic anion were well demonstrated by incorporating the carrier-mediated process. However, the ″in vivo counter-transport″ phenomena may be also explained by the enhancement of back diffusion due to the displacement of intracellular binding. In conclusion, one should be more cautious in interpreting data obtained from so-called ″in vivo counter-transport″ experiments.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.2
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• pp.19-21
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• 1978

The electrical drift mobility of charge carrier of Cholesteryl Benzoate was measured by Polarity inversion method in the temperature range 140~ 185$^{\circ}C$. with a view to revealing the mechanism of charge carrier transport. The electrical drift mobility of charge carrier of that increased from 2.5$\times$10-7$\textrm{cm}^2$/V.sec to 2.0$\times$10-6$\textrm{cm}^2$/v.sec as the temperature increased. As a result of the experiment, the mechanism of current transport is believed to be ionic mechanism.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.21-26
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• 1996

In our previous studies, we reported that lead intoxicated nerve cell by inhibition of the Na$^{+}$-K$^{+}$ ATPase activity and reduction of myo-inositol in nerve cell. As the second series of experiments, in order to understand toxic mechanism of lead for nerve cell, the characteristics of myo-inositol transport system and the effect of lead on its system have been studied in the sciatic nerves of control and lead-treated rats. A lead intoxicated animal model was induced by feeding diet containing lead to Sprague-Dawley rat for two weeks. Four weeks aged Sprague-Dawley rats were divided into three group : normal control group, 10ppm-lead treated group, 100ppm-lead treated group. All rats were sacrified at the end of two weeks. The rate o myo-inositol transport by sciatic nerve isolated from lead-treated rat was significantly decreased compared with that of control rat. This deficit results from that myo-inositol transport system which is carrier mediated and sodium-potassium dependent was inhibited by the lead treatment (both 10ppm and 100ppm) due to increase of the Km value without affecting Vmax value for myo-inositol carrier. These observations suggest that the toxic mechanism of lead on nerve myo-inositol transport system might be a change of affinity without change of maximum transport velocity for carrier.

• Journal of Pharmaceutical Investigation
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• v.23 no.1
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• pp.1-9
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• 1993

The endothelial cell of brain capillary called the blood-brain barrier (BBB) has carrier-mediated transport systems for nutrients and drugs. The mechanism of the BBB transport of basic and acidic drugs has been reviewed and examined for endogenous transport systems in BBB in WKY and SHRSP. Acidic drugs such as salicylic acid and basic drugs such as eperisone are taken up in a carrier mediated manner through the BBB via the monocarboxylic acid and amine transport systems. The specific dysfunction for the choline transport at the BBB in SHRSP would affect the function of the brain endothelial cell and brain parenchymal cell. The utilization of the endogenous transport systems of monocarboxylic acid and amine could be promising strategy for the effective drug delivery to the brain.

• Archives of Pharmacal Research
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• v.6 no.2
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• pp.109-114
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• 1983

A mechanism of taurine transfer across the rat small intestine was elucidated by using the in situ recirculation perfusion or loop method. Taurine uptake was saturable, Km= 39.9 mM, and energy dependent, and required sodium. The close structural analogues, aminomethane sulfonic acid, .gamma.-amino-butyric acid, hypotaurine, and .betha.-alanine, reduced significantly taurine uptake when present in 10-fold excess. The .alpha.-amino acid, glycine, did not inhibit uptake. Hence, all of these findings lead to a conclusion that a carrier-mediated transport system for taurine exists in the small intestine.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.1
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• pp.27-34
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• 2000

In this paper, carrier transport mechanism and modulation response for SCH(Separate Confinement Heterostructure) SQW(Single Quantum Well) laser diodes were studied. In order to explain carrier transport mechanism, both carrier density and current density were calculated. The recombination current density in the quantum well as a function of the SCH length was also calculated. For the modulation response, linearizing the rate equation, we calculated the bandwidth, relaxation oscillation frequency, damping factor, and the K-factor.

• YAKHAK HOEJI
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• v.49 no.4
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• pp.275-283
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• 2005

The purpose of the present study was to kinetically investigate the carrier-mediated uptake in the hepatic transport of organic anions, and to simulate the 'in vivo counter-transport' phenomena, using kinetic model which was developed in this study. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of 'counter-transport' phenomenon. To examine the inhibitory effects on the initial uptake of organic anions by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. Effects of bromophenol blue (BPB) or bromosulfophthalein (BSP) on the plasma disappearance curves of a 1-anilino-8-naphthalene sulfonate (ANS) were then kinetically analyzed based on a flow model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). Moreover, 'in vivo counter-transport' phenomena were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The 'in vivo counter-transport' phenomena in the hepatic transport of a organic anions were well demonstrated by incorporating the carrier-mediated process. However, the 'in vivo counter-transport' phenomena may be also explained by the enhancement of back diffusion due to the displacement of intracellular binding. In conclusion, one should be more cautious in interpreting data obtained from so-called 'in vivo counter-transport' experiments.

• Macromolecular Research
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• v.12 no.2
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• pp.145-155
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• 2004

Facilitated transport membranes for the separation of olefin/paraffin mixtures have long been of interest in separation membrane science because olefins, such as propylene and ethylene, which are important chemicals in petrochemical industries, are currently separated by energy-intensive cryogenic distillation processes. Recently, solid polymer electrolyte membranes containing silver ions have demonstrated remarkable performance in the separation of olefin/paraffin mixtures in the solid state and, thus, they can be considered as alternatives to cryogenic distillation. Here, we review recent progress, and critical issues affecting in the use of facilitated olefin transport membranes; in particular, we provide a general overview with reference to carrier properties, transport mechanisms, and separation performance.

• YAKHAK HOEJI
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• v.38 no.2
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• pp.114-122
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• 1994

A study on the absorption mechanism of cefixime(CF), an oral ${\alpha}-amino$ group deficient cephalosporin antibiotic, has been undertaken through the rat jejunum and nasal cavity using an in situ simultaneous perfusion technique developed in our laboratory. CF was well absorbed in the jejunum and nasal cavity of rats at pH 5.0, but not at pH 7.0. CF absorption was studied over four orders of magnitude in concentration to determine saturability. Disappearance of CF in the perfusate followed first-order kinetics at all tested concentrations. The apparent first-order absorption rate constant was found to be dependent on the concentration over the range of $0.1\;mM{\sim}3\;mM$ in the jejunum and nasal cavity of rats. Inhibitors were added to determine the competitive inhibition of CF absorption. The presence of L-tyrosine, L-phenylalanine, alanine-alanine, glycine-glycine and cefadroxil produced the significant inhibition of CF absorption in the nasal cavity and jejunum. However, there was no evidence of the inhibition in the presence of cefazolin. In addition, The CF absorption in the nasal cavity and jejunum was inhibited significantly by ouabain and 2,4-dinitrophenol(DNP). This study suggested that CF is absorbed across the rat nasal cavity and jejunum by carrier-mediated transport mechanism and energy consuming system.