• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.48-53
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• 2006

The asymmetric biosynthesis of ethyl (S)-4-chloro-3-hydrobutanoate from ethyl 4-chloro-3-oxobutanoate was investigated by using whole cells of Candida magnoliae JX120-3 without the addition of glucose dehydrogenase or $NADP^+/NADPH$. In a one-phase system, the bioconversion yield was seriously affected on the addition of 12.1 g/L ethyl 4-chloro-3-oxobutanoate. In order to reduce this substrate inhibition, a water/ n-butyl acetate two-phase system was developed, and the bioreduction conditions optimized with regard to the yield and product enantiometric excess value. The optimal conditions were as following: water to n-butyl acetate volume ratio of 1:1, 4.0 g DCW/L active cells, 50 g/L glucose and $35^{\circ}C$. By adopting a dropwise substrate feeding strategy, high concentration of ethyl 4-chloro-3-oxobutanoate (60 g/L) could be asymmetrically reduced to ethyl (S)-4-chloro-3-hydrobutanoate with high yield (93.8%) and high enantiometric excess value (92.7%).

• 분석과학
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• 제19권6호
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• pp.519-528
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• 2006

본 연구에서는 뇨시료를 고체상 추출법으로 추출한 후 HPLC/DAD/ESI-MS(high-performance liquid chromatograph/diode array detector/electro-spray ionitation mass spectrometry)를 사용하여 분석하였다. 7종의 thyroid hormones의 HPLC 분리조건은 Hypersil ODS(octadecylsilica) 컬럼(4.6mm I.D., 100 mm length, particle size $5{\mu}m$)을 사용하고 ammonium formate buffer와 acetonitrile을 이동상으로 하여 기울기 용리한 결과 완전 분리가 가능하였으며, UV spectra 및 질량스펙트럼을 확인할 수 있었다. 고체상 추출법에 의한 전처리 최적 조건을 조사한 결과 시료를 pH 3으로 한 후 C18 고체상을 사용하여 4 mL의 methanol/ammonium hydroxide(9:1) 혼합용액으로 용리할 경우 회수율이 89.0-113.1%로 나타났다. HPLC/DAD를 이용하여 10-1000 ng/mL범위에서 검량선을 작성한 결과 $r^2$값은 0.992-0.998 으로 나타났으며 검출한계는 2-4 ng/mL(3.8-13.0 pmol/mL)로 계산되었다.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.781-785
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• 2005

A fast and reliable method for the selective separation and preconcentration of $Cu^{2+}$ ions using homogeneous liquid-liquid extraction was developed. A new $\alpha$-dioxime derivative (2H-1,4-benzothioazine-2,3(4H)dionedioxime, Dioxime I) was synthesized and investigated as a suitable selective complexing ligand for $Cu^{2+}$ ions. Zonyl FSA (FSA) was applied as a phase-separator agent under the slightly acidic pH conditions. Under the optimal experimental conditions ([FSA] = 3.2% w/v, [THF] = 19.5% v/v, [Dioxime I] = 1.9 ${\times}\;10^{-3}$ M, and pH = 4.7), 10 ${\mu}g\;of\;Cu^{2+}$ in 5.2 mL aqueous phase could be extracted quantitatively into 80 $\mu$L of the sedimented phase. The maximum concentration factor was 65-fold. The limit of detection of the proposed method was 0.005 ng $mL^{-1}$. The reproducibility of the proposed method, on the 10 replicate measurements, was 1.3%. The influence of the pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the complexing ligand and the effect of different diverse ions on the extraction and determination of $Cu^{2+}$ ions were investigated. The proposed method was applied to the extraction and determination of $Cu^{2+}$ ion in different synthetic and natural water samples.

• 대한기계학회논문집
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• 제12권4호
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• pp.825-832
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• 1988

본 연구에서는 1차원 열흐름하에서 상부가 가열된 다공물질내의 열파이프 현 상과 관련하여 2상영역의 존재와 그 길이에 영향을 미치는 인자들을 실험적으로 관찰, 조사하였다.

• Korean Journal of Acupuncture
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• 제18권1호
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• pp.11-20
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• 2001

댑싸리하고초 약침액을 이용하여 phase II detoxification 효소인 quinone reductase (QR 및 GST) 유도, GSH 생성량, phase I 효소 cytochrome P4501A1 활성억제, 발암물질 B[a]P-DNA adduct 형성의 저해효과 등을 측정하였다. QR 생성 유도를 Hepa1c1c7로 실험한 결과, 댑싸리하고초 약침액및 열수추출액 모두에서 유도 되었으며, 농도가 높아질수록 유도율이 더 높게 나타났으며, GSH와 GST의 유도율도 약침액에서 나타났다. 댑싸리하고초 약침액 $5{\times}$에서 45.2%의 cytochrome P4501A1 효소활성 저해효과를 측정할 수 있었다. 또한 B[a]P-DNA binding 저해효과를 실험한 결과, 약침액 $3{\times}$ 농도에서 45.0%의 저해효과가 있었다. 이상의 결과에 의하면 댑싸리하고초 약침액은 암억제 물질로서의 기능을 충분히 발휘할 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2813-2818
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• 2010

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

• 동의생리병리학회지
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• 제22권1호
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• pp.126-130
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• 2008

Water extract from Prunella vulgaris L. (PVW) was tested for colon cancer chemopreventive activity by measuring the activities of cytochrome P450 1A1, phase Ⅱ detoxification enzyme [quinone reductase (QR) and glutathione S-transferase (GST)] and ornithine decarboxylase (ODC) and glutathione (GSH) levels in cultured human colorectal adenocarcinoma HT-29 cells. PVW significantly inhibited 7,12-dimethylbenz[a]anthracene (DMBA)-induced cytochrome P450 1A1 activity at 10 and 50 ${\mu}g/ml$. PVW induced QR activity in a dose-dependent manner over a concentration range of $1{\sim}50\;{\mu}g/ml$. GST activity was also induced with the treatment of PVW in HT-29 cells. In addition GSH levels were increased with PVW. PVW inhibited ODC activity, a key enzyme of polyamine biosynthesis, which is enhanced in tumor promotion. These results suggest that Prunella vulgaris L. has colon cancer chemopreventive activity by inhibiting cytochrome P450 1A1 and ODC activities and by increasing phase Ⅱ enzyme activity and GSH levels.

• 분석과학
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• 제32권5호
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• pp.163-172
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• 2019

Methamphetamine (MA) is currently the most abused illicit drug in Korea and its major metabolite is amphetamine (AP). As MA exist as two enantiomers with the different pharmacological properties, it is necessary to determine their respective amounts in a sample. Thus a chiral stationary phase liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of d-MA, l-MA, d-AP, and l-AP in human urine. Urine sample ($200{\mu}L$) was diluted with pure water and purified using solid-phase extraction (SPE) cartridge. A $5-{\mu}L$ aliquot of SPE treated sample solution was injected into LC-MS/MS system. Chiral separation was carried out on the Astec Chirobiotic V2 column with an isocratic elution for each enantiomer. Identification and quantification of enantiomeric MA and AP was performed using multiple reaction monitoring (MRM) detection mode. Linear regression with a $1/x^2$ as the weighting factor was applied to generate a calibration curve. The linear ranges were 25-1000 ng/mL for all compounds. The intra- and inter-day precisions were within 3.6 %, while the intra- and inter-day accuracies ranged from -5.4 % to 11.8 %. The limits of detection were 2.5 ng/mL (d-MA), 3.5 ng/mL (l-MA), 7.5 ng/mL (d-AP), and 7.5 ng/mL (l-AP). Method validation parameters such as selectivity, matrix effect, and stability were evaluated and met acceptance criteria. The applicability of the method was tested by the analysis of genuine forensic urine samples from drug abusers. d-MA is the most common compound found in urine and mainly used by abusers.

• Clinical and Experimental Pediatrics
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• 제49권5호
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• pp.539-544
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• 2006

목 적 : 가와사끼병의 진단 지표로서 NT-proBNP의 유용성을 살펴보고자 하였다. 방 법 : 가와사끼병을 진단 받은 환아 58명에서 발병 10일 이내 급성기에 전기화학발광면역법(Electrochemiluminescence immunoassay)를 이용하여 NT-proBNP를 측정하였고, 그 중 51명에서 회복기(발병 60에서 81일 이내)에 NT-proBNP 값을 측정하여 비교하였다. 가와사끼병과 임상적으로 구별하기 어려운 급성 열성 질환이 있는 환아 34명을 대조군으로 하여 NT-proBNP를 측정하여 가와사끼병 환자군과 비교하였다. 또한 가와사끼병 급성기에 심장 초음파검사를 시행하여 심낭삼출과 관상동맥 병변의 여부를 확인하였고 좌심실 확장기말 내경(LVIDd)과 수축기말 내경(LVIDs), 좌심실 구출율(LVEF)과 좌심실 단축율(LVSF)을 측정하여 NT-proBNP 측정치와의 상관관계를 조사하였다. 가와사끼병과 다른 질환의 감별진단을 위해 receiveroperating characteristic curve를 이용하여 NT-proBNP의 cutoff value를 구하였다. 결 과 : 가와사끼병 급성기 NT-proBNP 측정치는 대조군에 비해 유의하게 높았다($1,501.6{\pm}2,132.6$ vs. $139.0{\pm}88.8pg/mL$, P<0.0001). 51명의 가와사끼병 환자군에서 NT-proBNP 값은 급성기에 증가하고 회복기에 크게 감소하였다($1,466.0{\pm}2,173.2$ vs. $117.5{\pm}95.5pg/mL$, P<0.0001). 가와사끼병의 감별진단을 위한 NT-proBNP의 cutoff value를 260 pg/mL으로 하였을 때 민감도 93%, 특이도 88%를 보였다. NT-proBNP는 심낭삼출이 있는 환아에서 심낭삼출이 없는 환아에 비해 높았다($1,784.2{\pm}1,903.1$ vs. $1,384.4{\pm}2,232.6pg/mL$). 관상동맥 병변이 있는 환아(n=3)가 적어 NT-proBNP와의 관계를 확인할 수 없었다. NT-proBNP 측정치와 LVEF index(r=0.104, P=0.46) 및 LVIDd index(r=0.171, P=0.22)은 상관관계가 없었다. 결 론 : NT-proBNP는 가와사끼병 급성기에 크게 증가하며 회복기에 감소한다. NT-proBNP >260 pg/mL일 때 가와사끼병을 강력히 의심할 수 있으며, NT-proBNP는 가와사끼병을 진단하는 지표로 사용될 수 있을 것으로 생각된다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.117.1-117.1
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• 2008