• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.291-294
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• 2006

A highly sensitive high-performance liquid chromatographic-tandem mass spectrometric method (HPLC-MSMS) has been developed to quantify itraconazole in human plasma for the purpose of pharmacokinetic studies. Sample preparation was carried out by liquid-liquid extraction using loratadine as an internal standard. Chromatographic separation used a YMC $C_{18}$ column, giving an extremely fast total run time of 3 min. The method was validated and used for the bioequivalence study of itraconazole tablets in healthy male volunteers (n = 31). The lower limit of detection proved to be 0.2 ng /mL for itraconazole.

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.421-428
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• 2007

This study was conducted two kinds of aims: 1) to modify the analytical methods (conditions) by high performance liquid chromatography - fluorescence detector for the detection of residual ivermectin in raw milk, 2) to provide basic information for the evaluation of standard of the residual ivermectin in raw milk. It could be considerable that negative ion spectra can be better method in the LC/MS analysis for the detection of residues, Characteristic daughter ions were observed in negative ion spectra, however, linear line was not formed in positive ion one. Three Holstein cows ($500{\pm}10kg$) were applied to commercial ointment of ivermectin just one time at the first day of test, and residues in raw milk were examined for 20day after administration. The limit of detection (LOD) was 0.65ng (n=5) by HPLC/FLD, and recovery rates were $87.85%{\sim}99.47%$. The peak was observed at the 4th day, and residues lasted to the end. Thus ivermectin was prohibited when lactating.

• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.125-130
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• 2000

An antiviral protein (CAP30) with ribosome-inactivating activity was purified from the leaves of Chenopodium album L. through ammonium sulfate precipitation and column chromatography using S-Sepharose, Blue-Sepharose, FPLC Suprose12 HR, and FPLC Mono-S. The molecular wight of CAP30 was estimated to be 30kD. CAP30 was thermostable, maintaing its activity even after incubation at $70^{\circ}C$ for 30 min, and was stable in the pH range of 6 to 9. In a cell-free in vitro translation system using rabbit reticulocyte lysate, protein synthesis was inhibited by the addition of CAP30 with an $IC_{50}$ of 2.26pM. The comparison of N-terminal amino acid sequences of this protein with known ribosome-inactivating proteins (RIPs) revealed that it had some sequence homology with PAP-S and PAP-R from pokeweed (Phytolacca americana)and dodecandrin from P. dodecandra, but had no sequence homology with RIPs from other plants belonging to different orders. The mosaic symptoms on tobacco leaves caused by cucumber mosaic virus infection was completely inhibited by 100 ng/ml of the pure CAP30 protein.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.83-89
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• 1998

Ginseng total saponins (GTS) injected intracerebroventricularly (i.c.v.) at doses from 0.1-1 vs inhibited the i.c.v. injection stress-induced plasma corticosterone levels in mice. The inhibitory action of GTS was blocked by co-administered NG-nitro-L-arginine methyl ester (L-NAME; 1.5 us, i.c.v.), an. inhibitor of nitric oxide synthase (NOS). Of the ginsenosides Rbl, Rba, Rc, Rd, Re, Rf, Rgl,20(S)-Rg3, and 20(R)-Rg3 injected i.c.v. at doses from 0.01 to 0.3ug(or 1 uE),20(5)-Rg3 and Rc significantly inhibited the o.c.v. injection stress-induced Plasma corticosterone levels. The inhibitory actions of 20(S)-Rg3 and Rc were blocked by co-administered L-NAME (1.5 n, i.c.v.). These results suggest that G75, 20(S)-Rg3 and Rc may inhibit the i.c.v. injection stress-induced hypothalamo-pituitary-adrenal response by inducing NO production in the brain.

• Archives of Pharmacal Research
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• v.22 no.1
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• pp.86-88
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• 1999

An advance d and sensitive high-performance liquid chromatographic (HPLC) method for determination of omeparzole in human plasma has been developed. After omeprazole was extracted from plasma with diethylether, the organic phase was transferred to another tube and trapped back with 0.1 N NaOH solution. The alkaline aqueous layer was injected into a reversed-phase C8 column. Lansoprazole was used as an internal standard. The mobile phase consisted of 30% of acetonitrile and 70% of 0.2 M $ KH_{2}PO_{4}$, pH 7.0. Recoveries of the analytes and internal standard were >75.48%. The coefficients of variation of intra- and inter-day assay were <5.78 and 4.59% for plasma samples. The detection limit in plasma was 2 ng/ml. The clinical applicability of this assay method was evaluated by determining plasma concentration-time courses of the respective analytes in 24 healthy volunteers after oral administration 40 mg of omeprazole. The present assay is considered to be simple, accurate, economical and suitable for the study of the kinetic disposition of omeprazole in the body.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.49-52
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• 2009

Single-drop microextraction (SDME) is an extraction methodology where the drop plays an essential role as extracts. It was evaluated for the GC-MS determination of nerve agents, one class of the chemical warfare agents (CWAs). Since these nerve agents are highly toxic, it is important to detect the nerve agents in the environmental samples. Several affecting factors including extraction solvents, stirring rate, extraction time, and amounts of salt were optimized. The limit of detections (LODs) were 0.1 - 10 ng/mL and the relative standard deviations (RSDs%, n=5) were in the range of 6.3% to 9.0% for four nerve agents. Without pretreatment of the environmental samples, 5-103 fold enrichments and 48-100% recovery were accomplished. These results demonstrated the feasibility of this method for on-site and off-site analysis of water sample collected from suspicious CWAs site.

• YAKHAK HOEJI
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• v.47 no.6
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• pp.422-431
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• 2003

The use of recombinant human erythropoietin (rhEPO), a stimulator of erythropoiesis, banned in sports because of the medical risk associated with thrombosis. Due to analytical difficulties to differentiate between natural human EPO (hEPO) and rhEPO, blood parameters of erythropoiesis such as contents of hemoglobin (cut-off value <17.5 g/d l for man, and < 16.0 g/dl for women), hematocrit and reticulocytes (cut-off value <2.0%) were measured to focus the misuse of rhEPO. We conducted anti-doping test for 122 blood samples of the World Cup athletes. The mean values of key parameters are as follows; 14.5$\pm$1.0 g/dl for hemoglobin, 41.7$\pm$2.8% for hematocrit, and 1.3$\pm$0.4% for reticulocyte. Blood sample was found to be stable up to 8 hours for the reticulocyte measurement. In addition, the soluble transferrin receptor and ferritin levels were measured by immunoassay methods using plasma samples (n=28) in which the mean value was 0.8$\pm$0.5 $\mu\textrm{g}$/$m\ell$ and 54.6$\pm$33.7 ng/$m\ell$, respectively. The results indicate that all samples tested were negative for the blood parameters of indirect anti-doping test for hEPO misuse. The statistical evaluation suggest that several other parameters such as red blood cell, mean corpuscular hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin and white blood cell could be considered as factors influencing hEPO function in addition to five parameters mentioned.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.2.1-2.7
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• 2011

Objectives: N-Nitrosodimethylamine (NDMA) is classified as a probable human carcinogen by the United States Environmental Protection Agency (US EPA) and is formed during the chlorination of municipal drinking water. In this study, selected nitrosamines were measured in chlorinated drinking water collected from Chuncheon, Kangwon-do, Republic of Korea, and a risk assessment for NDMA was conducted. Methods: Twelve water samples were collected from 2 treatment plants and 10 household taps. Samples were analyzed for 6 nitrosamines via solid-phase extraction cleanup followed by conversion to dansyl derivatives and high-performance liquid chromatography-fluorescence detection (HPLC-FLD). Considering the dietary patterns of Korean people and the concentration change of NDMA by boiling, a carcinogenic risk assessment from ingestion exposure was conducted following the US EPA guidelines. Results: NDMA concentrations ranged between 26.1 and 112.0 ng/L. NDMA in water was found to be thermally stable, and thus its concentration at the end of boiling was greater than before thermal treatment owing to the decrease in water volume. The estimated excess lifetime carcinogenic risk exceeded the regulatory baseline risk of $10^{-5}$. Conclusions: This result suggests that more extensive studies need to be conducted on nitrosamine concentration distributions over the country and the source of relatively high nitrosamine concentrations.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.1
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• pp.93-98
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• 2001

The precise mechanism of set-point regulation in hypothalamus was not elucidated. Nitric oxide synthases(NOS) were detected in hypothalamus, however, the roles of NO in hypothalamus was not fully studied. So, we tested the effects of NO on body temperature because preoptic-anterior hypothalamus was known as the presumptive primary fever-producing site. NO donor sodium nitroprusside (SNP, 4 nmol, i.c.v.) elicited marked febrile response, and this febrile response was completely blocked by indomethacin (a cyclooxygenase inhibitor). But, ODQ (selective guanylate cyclase inhibitor, $50\;{\mu}g,$ i.c.v.) did not inhibit fever induced by SNP. The cyclic GMP analogue dibutyryl-cGMP $(100\;{\mu}g,\;i.c.v.)$ induced significant pyreses, which is blocked by indomethacin. $N^G-nitro-L-arginine$ methyl ester (L-NAME, non selective NOS inhibitor) inhibited fever induced by $interleukin-1{\beta}\;(IL-1{\bata},\;10\;ng,\;i.c.v.),$ one of endogenous pyrogens. These results indicate that NO may have an important role, not related to stimulation of soluble guanylate cyclase, in the signal pathway of thermoregulation in hypothalamus.

• Korean Journal of Veterinary Service
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• v.23 no.2
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• pp.137-142
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• 2000

In order to develop a good separation and simultaneous analysis of different sugar in an artificial mixed sugar solution, we analyzed 10 sugar components in an artificial mixed sugar solution composed of fructose, glucose, mannitol, sucrose, maltose, lactose, xylose, xylitol erythritol, and trehalose with using HPLC-ELSD or HPLC-RI. Separation and quantification by HPLC-ELSD was superior to those by HPLC-RI and detection sensitivity by HPLC-ELSD was higher then that by HPLC-RI as micorgram($\mu\textrm{g}$) level. 1. The units of minimal detectable limits were showed $\mu\textrm{g}$/$m\ell$ and ng/$m\ell$ by the HPLC-RI and HPLC-ELSD, respectively. 2. The condition of ELSD was drift tube temperature $82^{\circ}C$, $N_2$ gas flow rate 2.10 SLPM, and colum oven temperature $30^{\circ}C$, respectively. Isolation and recovery rates of single sugar from the multiple sugar solution was higher at the condition (time: flow rate: D.W.:ACN MeOH, min : $m\ell$/min:v:v:v) of linear gradient elution of mobile phase as 0 : 1.00 : 15 : 85 : 0.1 : 1.00 : 6 : 90 : 4, 17 : 1.00 : 10 : 70 : 20, 28 : 1.00 : 15 : 85 : 0 an 35 : 1.00 : 15 : 85 : 0, in order.