Duk Keun An

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Verrucous carcinoma (VC), a variant of squamous cell carcinoma (SCC), is distinct from SCC in morphology and behavior. The underlying genetic changes involved in the development of VC and its precursor verrucous hyperplasia (VH) are unknown. This study determined whether chromosomal regions frequently lost during the development of SCC are also lost in the(More)
An analytical method has been developed to determine simultaneously plasma concentration of the enantiomers of verapamil and its major metabolite, norverapamil, using capillary zone electrophoresis. Trimethyl-beta-cyclodextrin was selected as chiral selector. Good separation was achieved under the conditions as below: Running electrolyte was pH 2.5, 60(More)
Surface-enhance Raman (SER) spectra of pyrazinamide (PZA), isoniazid (INAZ), and isonicotiamide (INCT) in silver sols have been studied over a range of solution concentration and pH. A linear calibration curve has been obtained for each of the sample molecules, and the lower limits of detection are estimated to be 5 ng for PZA and INAZ, and 10 ng for INCA.(More)
AIM To explore the biotransformation of compound 7-(4-chlorbenzyl)-7,8,13, 13a-tetrahydroberberine in the rabbit. METHODS Analyze the rabbit bile sample with HPLC, LC/MS and LC/NMR. RESULTS A metabolite and unchanged 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine were found in the rabit bile, the metabolite was characterized and its structure was(More)
A normal phase liquid chromatographic method was developed for the determination of berberine-type alkaloids in rhizoma Coptidis and traditional Chinese medicine--Angong Niuhuang Wan. Experimental evidences indicate that a normal phase system of a silica column (3.9 x 250 mm) as stationary phase with an eluent of ethyl acetate-formic acid-ethanol (15:3:2)(More)
Eight Chinese healthy male volunteers aged 27 +/- s 4 a were injected i.v. midazolam (Mid) 15 mg. Blood samples were collected at 0, 2, 5, 7, 10, 20, 30, 45, 60, 90, 120, 180, and 240 min. A HPLC method was established for determining the Mid concentrations in serum. The concentration-time data was fitted with biexponential curve. Pharmacokinetic parameters(More)
Kovats retention indexes of more than 200 kinds of natural and synthetic compounds of alcohol, aldehyde, acetal, ketone, ether, alkene, nitrile, carboxylic acid, ester, etc. were determined on polar liquid phase (DB-WAX) and nonpolar liquid phase (DB-1) by linear temperature-program capillary column gas chromatography. Some rules of part of the homologous(More)
AIM To study the phase II metabolites of phenoprolamine hydrochloride (DDPH) in rat bile. METHODS DDPH was administered by i.p. to bile duct-cannulated rats. Bile samples were collected before drug administration and up to 12 h after drug administration. After being purified and enriched with C-18 SPE columns the rat bile samples were analyzed by(More)