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정현정,용철순,최윤수,오두만 ( Hyun Jeong Jeong,Chul Soon Yong,Yoon Soo Choi,Doo Man Oh ) 한국약제학회 1997 Journal of Pharmaceutical Investigation Vol.27 No.1
N/A Amino-β-lactam antibiotics are absorbed by the dipeptide transporter in the small intestine. These uptakes are coupled to a proton influx. The inward proton gradient is partly induced by the Na^+/H^+ exchanger and calcium ion is involved in control of this antiport. Interaction between ampicillin which is one of the amino-β-lactam antibiotics and nifedipine which is one of calcium channel blocking agents was studied in rats in vivo and with rabbit jejunum mounted on the Sweetana/Grass diffusion cells in vitro. Bioavailability of ampicillin was increased significantly when nifedipine was co-administered orally in rats. There were no differences in the distribution phase and the elimination phase when ampicillin was given either alone or with nifedipine intravenously. Conditions for in vitro experiments were determined. The lift rate of O₂/CO₂ gas was controlled to 3 bubbles/sec and ampicillin was stable in the Kreb`s buffer at pH 6.0. Absorption of ampicillin was the greatest when the completely-stripped serosal membrane was used. Transport of ampicillin from mucosal to serosal side in the rabbit jejunum was enhanced by 32% in the presence of nifedipine (p=0.059). Above results suggest that nifedipine might increase the plasma level of ampicillin via the improved absorption in the intestine rather than the reduction in the elimination or/and alteration in the distribution.
Hepatic Targeting of Acyclovir Using Asialofetuin as a Drug Carrier
용철순,손성호,전철수,오두만,Yong, Chul-Soon,Son, Sung-Ho,Jun, Chul-Soo,Oh, Doo-Man 한국약제학회 1994 Journal of Pharmaceutical Investigation Vol.24 No.4
With the purpose of improving the therapeutic index of $[^3H]$ acyclovir (ACV) in the treatment of chronic hepatitis B infection, asialofetuin (AF) which after selective interaction with Ashwell's receptor specifically enters into hepatocytes, was chosen as a carrier system for hepatic targeting. This drug was first converted to its monophosphate (ACVMP), which was subsequently activated by water soluble carbodiimide to conjugate with ${\varepsilon}-NH_2$ groups of Iysine residues of AF. The molar ratio of ACVMP to AF in the conjugate was 3.9. In rats, elimination of ACVMP-AF conjugate after i.v. injection showed two phase elimination kinetics. Initial apparent elimination rate constant in rats was $0.191\;min^{-1}$ which was greater than that of ACV. The elimination rate constant from terminal phase was $0.021\;min^{-1}$. Area under the total radioactivities versus time curve was found to be several times larger in liver than in other organs (spleen, intestine, lung and kidney) after i.v. administration of the conjugate labelled in the drug moiety. The above results suggested that ACVMP-AF conjugate was rapidly taken up by hepatocytes and could be a useful hepatic targeting system.
아시클로버 - 아시알로페투인 접합체의 간 포획 및 안정성
손성호,허근,이영대,오두만,용철순 ( Sung Ho Son,Keun Huh,Young Dae Lee,Doo Man Oh,Chul Soon Yong ) 한국약제학회 1997 Journal of Pharmaceutical Investigation Vol.27 No.1
N/A For the purpose of improving the chemotherapeutic index of acyclovir(ACV), it was conjugated with asialofetuin(AF), which has been reported to enter into hepatocytes. When [H³] acyclovir in itself or its conjugate were administered to rats, the latter was taken up more selectively by the liver than any other tissues. The stability of ACVMP-AF conjugate in phosphate buffer (pH 5.0) and rat liver homogenate showed a pseudo-first order profile. ACVMP-AF, however, was relatively stable in pH7.4 phosphate buffer and rat plasma. The conjugate was added to the isolated rat hepatocyte and cellular uptake was monitored by scintillation counting for up to 6 hours at 37℃. Hepatocytes incubated with the conjugate exhibited radioactivities significantly enhanced over control levels dose-dependently, i.e., a 3-40 fold increase in radioactivities was observed over controls at the conjugate concentrations of 0.1-10 ㎍/㎖. The AUQ in the liver, kidney, spleen. intestine and lung was higher in treatment with ACVMP-AF than that in treatment with ACV. In treatment with ACVMP-AF, the weighted-average overall drug targeting efficiency(Te) for the liver was higher than in treatment with ACV(57.00 vs 13.31%), and the weighted-average tissue exposure(Re) was 5.03 for the liver. These results indicated that ACVMP-AF conjugate was rapidly taken up by hepatocytes and could be an efficient and selective hepatic targeting system.
일회통과 관류실험시 물의 수송: 관류액의 종류와 삼투압의 영향
이정화(Jeong Hwa Lee),이현주(Hyun Joo Lee),용철순(Chul Soon Yong),오두만(Doo Man Oh) 대한약학회 1995 약학회지 Vol.39 No.4
The single-pass perfusion experiments were performed in anesthetized rats to investigate the effects of perfusates and their osmolality on the water transport and to determine the correlation between the extent of water transport and the volume change of perfusate. Phenol red was used as a nonabsorbable marker. In normal rats, when perfused at a flow rate of 0.5ml/min, 2-(N-morpholino) ethanesulfonic acid (MES) and Sorensen''s phosphate buffers showed minimal net water transport as 0.125 and 0.173%/cm of intestinal length, respectively. Hypotonic perfusate of 200mOsm/kg of water and hypertonic perfusate of 400mOsm/kg of water generated significant water transport compared with isotonic perfusate of 300mOsm/kg of water. There was a linear correlation between the extent of water transport and the volume change of perfusate, suggesting that the volume change can be used as a measure of water transport.
장관세포인 HT-29 에 존재하는 디펩티드수송체의 Xenopus oocyte 에서의 발현
오두만,양재하 한국약제학회 1995 Journal of Pharmaceutical Investigation Vol.25 No.4
Cloning the gene encoding a dipeptide transporter is necessary for understanding the absorption mechanism of peptides and peptide-like drugs in the gastrointestinal tract. Functional expression of a dipeptide transporter after microinjection into Xenopus laevis oocytes was performed using the mRNA purified from human intestinal HT-29 cells. Fifty nanoliters of purified mRNA (1 ㎎/mL) were microinjected into healthy oocytes followed by incubation for 4 days in order to express a dipeptide transporter. Functional expression was determined by a uptake assay using 10Ci/mL [³H]-glycylsarcosine, a dipeptide substate of the transporter. Seasonal variability and batch-to-batch variability were greater in summer. The usage of beveled micropipettes improves viability of oocytes at 4 days after microinjection. Expression of a dipeptide transporter in oocytes after microinjection of mRNA obtained from HT-29 cells was significantly larger than those after microinjection of water or mRNA obtained from the rabbit intestine.