• Journal of Korean Society for Atmospheric Environment
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• v.11 no.E
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• pp.31-43
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• 1995

Natural emissions of NOx from soils were measured at an agricultural corn field during 3 weeks of growing season in summer (from May to June) 1995. This experiment was conducted in an effort to characterize the role of soil NOx on tropospheric ozone formation in rural atmosphere, and understand the natural NOx emission mechanism with respect to soil parameters. NO fluxes were ranged from 3.1 ng Nm$^{-2}s^{-1}$ to 259.0 ng Nm$^{-2}s^{-1}$, and average NO flux during experimental period was found to be 47.6 $\pm$ 50.6 ng Nm$^{-2}s^{-1}$ with 732 number of data. Diurnal variation of NO flux was shown clearly with daytime maximum and nighttime minimum. NO fluxes were correlated with soil temperature. Exponential soil temperature dependency of NO fluxes was found with 0.0160$^{circ}C^{-1} of k and r^2=0.508$, which agrees well to the value estimated at corn fields in eastern United States. The significant increases of NO fluxes from agricultural soil were detected after applying N fertilizers to soil. THe mechanisms attributed to this are enhanced biological nitrification and denitrification. In the view of rural ozone formation, the roles of natural NO emissions are very essential, especially in NOx - limited region such as southern United States.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1173-1178
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• 2008

A simple and sensitive high-performance liquid chromatographic method was developed for the simultaneous identification of enrofloxacin and its active metabolite ciprofloxacin in chicken muscle. Norflorxacin imprinted polymers synthesized in water-containing systems show high selectivity to enrofloxacin and ciprofloxacin in an aqueous environment. Using these water-compatible imprinted polymers as selective adsorbents in the solid-phase extraction of enrofloxacin and ciprofloxacin from chicken samples, the remaining biological matrix could be quickly washed out from the imprinted column while enrofloxacin and ciprofloxacin were selectively retained and enriched. Analytical separation was performed on a $C_{18}$ column using acetonitrile-water as a mobile phase and fluorescence detection. Good linearity was obtained from 0.8 to 500 ng/g (r > 0.998) with relative standard deviation of less than 3.9%. The mean recoveries of enrofloxacin and ciprofloxacin from chicken muscle were 80.6-94.5% and 77.8-91.8% at three different concentrations. The limits of determinations based on S/N=3 were 0.07 ng/g and 0.09 ng/g, which are below the maximum residue limits established in many countries.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E1
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• pp.1-11
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• 2005

The concentration levels of gaseous elemental mercury (GEM) in ambient air have been investigated from a monitoring station located in Yang Jae district of Seoul, Korea for a long-term period covering 1997 through 2002. The mean concentration of Hg, if computed based on its hourly measurement data for this six-year period, was $5.32\pm3.53 ng m^{-3} (N = 27,170)$. The inspection of the diurnal distribution patterns indicated the presence of notably high concentration levels during nighttime relative to daytime (e.g., the mean hourly value as high as $9 ng m^{-3}$ in winter nighttime). When divided seasonally, the highest mean of $6.12 ng m^{-3}$ was also observed during winter followed by spring, fall, and summer. The results of our analysis confirmed the relative dominance of winter (seasonally) or nighttime (diurnally), while exhibiting a complicated trend on a long-term basis. Examination of our data over a different temporal scale consistently indicated that dynamic changes in Hg concentrations occurred through time in line with changes in the strength and diversity of the source processes. It is thus acknowledged that the presence of unusually high Hg levels is the consequence of intense man-made activities, while such signatures can vary in a competitive manner.

• Mass Spectrometry Letters
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• v.11 no.3
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• pp.59-64
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• 2020

Mertansine, a thiol-containing maytansinoid, is a tubulin inhibitor used as the cytotoxic component of antibody-drug conjugates for the treatment of cancer. Liquid chromatography-tandem mass spectrometry was described for the determination of mertansine in rat plasma. 50-μL rat plasma sample was pretreated with 25 μL of 20 mM tris-(2-carboxyethyl)-phosphine, a reducing reagent, and further vortex-mixing with 50 μL of 50 mM N-ethylmaleimide for 3 min resulted in the alkylation of thiol group in mertansine. Alkylation reaction was stopped by addition of 100 μL of sildenafil in acetonitrile (200 ng/mL), and following centrifugation, aliquot of the supernatant was analyzed by the selected reaction monitoring mode. The standard curve was linear over the range of 1-1000 ng/mL in rat plasma with the lower limit of quantification level at 1 ng/mL. The intra- and inter-day accuracies and coefficient variations for mertansine at four quality control concentrations were 96.7-113.1% and 2.6-15.0%, respectively. Using this method, the pharmacokinetics of mertansine were evaluated after intravenous administration of mertansine at doses of 0.2, 0.5, and 1 mg/kg to female Sprague Dawley rats.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.70-76
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• 2011

PCR-based Weissella species-specific detection method was developed to apply for the discrimination of Korean and Chinese kimchi by detecting a Weissella species only found in Korean or Chinese kimchi. PCR primers were designed from the species-specific sequence in the recN gene of each species. The primers allowed the species-specific detection and identification of nine species in the genera Weissella, and were successfully applied to the detection of W. cibaria, W. confusa, W. koreensis, and W. soli in kimchi with 20 ng template DNA. W. cibaria, W. confusa, and W. koreensis were detected from the Korean kimchi samples tested but W. soli was not detected. However, the four species were detected from Chinese kimchi samples. PCR-based W. soli-specific detection could not be perfectly applied as the Chinese kimchi discriminating method but has significance as an approach to evaluate the potential of scientific verification method based on the difference of microbial community.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.165-170
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• 2009

Purpose: Nowadays, NM (in vitro lab) and LM (TLA lab) are overlaped in almost all tests. in this case, how can NM develop continually in a keen competition with LM. we studied to find out current situation and problems after comparing NM with LM. Then, to improve our technic. Methods and meterials: We studied from October 2008 to February 2009 at department of nuclear medicine Seoul National University Bundang Hospital visited 108 patients. We assayed TSH, $FT_4$ by Ria-mat{TSH (n=23), $FT_4$ (n=19)} and AFP, CEA, PSA by manual. {AFP (n=24), CEA (n=31), PSA (n=31)}. On the other hand, LM was measured by TLA system. Results: NM was similar to LM (value of AFP), NMLM (value of PSA,TSH), NM$\leqq$LM (value of $FT_4$ in range 0.01~1.00 ng/mL), NM$\geqq$LM (value of $FT_4$ in range 1.00~6.00 ng/mL) Conclusions: There was no test which result showed big difference remarkably, but several tests have some difference totally or partly. It means that there is possibility to judge wrongly (normal patient->abnormal, abnormal->normal). So, we need to consider always when we report the result.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.80-80
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• 2003

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor, cognitive, and psychiatric symptoms, accompanied by marked cell death in the striatum and cortex. Stereotaxic injection of quinolinic acid (QA) into striatum results in a degeneration of GABAergic neurons and exhibits abnormal motor behaviors typical of the illness. The objective of this study was carried out to obtain basic information about whether parthenogenetic mouse embryonic stem (PmES) cells are suitable for cell replacement therapy of HD. To establish PmES cell lines, hybrid F1 (C57BL/6xCBA/N) mouse oocytes were treated with 7% ethanol for 5 min and cytochalasin-B for 4 hr to initiate spontaneous cleavage. Thus established PmES cells were induced to differentiate using bFGF (20ng/ml) followed by selection of neuronal precursor cells for 8 days in N2 medium. After selection, cells were expanded at the presence of bFGF (20 ng/ml) for another 6 days, then a final differentiation step in N2 medium for 7 days. To establish recipient animal models of HD, young adult mice (7 weeks age ICR mice) were lesioned unilaterally with a stereotaxic injection of QA (60 nM) into the striatum and the rotational behavior of the animals was tested using apomorphine (0.1mg/kg, IP) 7 days after the induction of lesion. Animals rotating more than 120 turns per hour were selected and the differentiated PmES cells (1$\times$10$^4$cells/ul) were implanted into striatum. Four weeks after the graft, immunohistochemical studies revealed the presence of cells reactive to anti-NeuN antibody. However, only a slight improvement of motor behavior was observed. By Nissl staining, cell mass resembling tumor was found at the graft site and near cortex which may explain the slight behavioral improvement. Detailed experiment on cell viability, differentiation and migration explanted in vivo is currently being studied.

• BMB Reports
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• v.40 no.6
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• pp.1016-1020
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• 2007

In this study, dioscin was isolated from Dioscoreae Rhizoma (DR), which is the rhizome of Dioscorea batatas DECNE. that inhabits broad areas of Korea and Japan. To determine whether dioscin induced growth hormone (GH) release, we evaluated its induction effects on GH release both in vitro and in vivo. The 70% methanol extract of DR, and its n-hexane and n-BuOH fractions, induced rat GH (rGH) release in rat pituitary cells 10-fold, 8-fold, and 5-fold higher than the control ($0.36{\pm}0.02 nM$), respectively (p < 0.05 each). The dioscin-induced rGH release of the cells was concentration-dependent and its $ED_{50}$ was $1.14{\times}10^{-5} M$. Within 90 minutes after intravenous administration of $10{\mu}g$/kg (p < 0.05 at $t_{max}$), dioscin caused the greatest increase in rGH concentration ($C_{max}$) in the rat plasma ($34.16{\pm}14.10 ng/ml$) (n = 4), which was twice as high as the control group ($12.88{\pm}3.29 ng/ml$) (n = 27).

• Analytical Science and Technology
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• v.15 no.4
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• pp.346-359
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• 2002

The brominated flame retardants (BFRs) are one of the unregulated pollutants in Korea, which is recently highlighted the new pollutants of environmental contamination. In this study, the previous research papers related the BFRs were surveyed, and the analytical methods of BFRs were established. The results are followed; The 40 kinds of PBDEs standards were used to establish the analytical methods to perform the experiments of recoveries and detection limits in water and soil. The detection limits of PBDEs using GC/MS represented 5.0~10.0 pg/L for water and 0.5~2.0 ng/g for soil samples. The average recoveries of water samples were 89~98% with ethylacetate, n-hexane and dichloromethane, and 89~103% in combined solvent with n-hexane and acetone. In soxhlet extraction, the higher recoveries obtained the acetone:n-hexane(1:1) comparing with acetone:dichloromethane(1:1).

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.55-61
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• 2011

NDMA(N-Nitrosodimethylamine) has been considered as a carcinogenic pollutant even at extremely low-concentration (10ng/L). However, previous researches on NDMA have focused on mainly high concentration due to a difficulty of analysis. In this study, removal efficiencies were evaluated for individual or combined methods with PAC(Powder Activated Carbon), GS(Granular Sludge), MF(Microfiltration), UF(Ultrafiltration) and Silica gel(MCM-41, Diatomite, Spherical silica gel) at both aerobic and anaerobic conditions. Combined method of GS, PAC and UF membrane at anaerobic condition showed the highest removal efficiency of 65% while Silica gel showed the lowest removal efficiency of 6%. The outcomes of this study could be used further study of extremely low-concentration NDMA removal.