• Journal of Photoscience
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• 제10권3호
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• pp.219-223
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• 2003

Phloxine B (2,4,5,7-tetrabromo-4,5,6,7-tetrachlorofluorescein disodium salt), also referred as D&C red dye no. 28, is phototoxic to many insects such as Tephritidae fruit flies. Sunlight photolysis of phloxine B in aqueous solutions was a first order kinetic reaction at low concentrations. But it turned to be more complex reactions with the increase of phloxine B concentration. The half-lives of phloxine B (6-120 ${\mu}$M) were 18-41 and 52-289 hours in oxygenated and deaerated distilled water, respectively. The photolysis rate constants increased as the phloxine B concentrations increased. The singlet oxygen formation positively correlated with the concentrations of phloxine B and humic acid in oxygenated distilled water. The formation of singlet oxygen did not stop even after the complete degradation of phloxine B, which suggested an involvement of photoproduct-mediated reactions. The results showed that singlet oxygen mediated photooxidation was a dominant reaction for phloxine B dissipation in an aqueous solution, and the self-sensitized and photoproduct-mediated reactions were also involved at the higher concentrations. Iodide and bromide ions significantly decreased phloxine B photolysis rate constants, which were in relation to the decrease of singlet oxygen formation.

• Radiation Oncology Journal
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• 제29권2호
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• pp.127-133
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• 2011

5년 반 전 처음 위암 발견 당시 45세였던 여자 환자로 처음부터 원격전이가 있었던 상태였으며 위절제술과 전이부위 절제를 포함한 수술과 항암제치료를 받았다. 그 후 4년 2개월 전부터 여러 차례 새로운 원격전이가 나타날 때마다 간헐적인 경구용 TS-1 항암제 치료와 함께 방사선치료를 시행 받았다. 방사선치료는 4년여에 걸쳐서 8차 시행하였으며 총 시행부위 수는 17 부위였다. 환자의 방사선치료 부위들 중에 근치적 방사선량의 치료를 받은 부위들은 그 뒤 수년의 시간이 흘러도 해당 부위의 국소조절 상태가 유지되었다. 환자는 현재 51세로 일상생활에는 별 지장이 없는 상태이다.

• Journal of Pharmaceutical Investigation
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• 제24권1호
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• pp.1-9
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• 1994

In order to study systemic peptide delivery through the ocular route, the stabilities of methionine enkephalin (Met-Enk) and $[D-ala^2]-methionine$ enkephalinamide (YAGFM) in the corneal extracts of rabbits were investigated using reversed phase HPLC. Met-Enk was found to be hydrolyzed most rapidly in the corneal epithelium, but YAGFM was relatively stable. Aminopeptidases appeared to contribute over 60% to the degradation of Met-Enk and the degradation rate of Met-Enk followed the first order kinetics. The half-lives of Met-Enk in the extracts of the corneal epithelium and endothelium were 36 and 673 min, respectively. From the effects of enzyme inhibitors, it was found that the application of the mixture of amastatin, thimerosal and EDTA was very useful for the inhibition of peptide degradation.

• 한국환경농학회지
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• 제14권2호
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• pp.179-185
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• 1995

Carbofuran의 aminothio 유도체로서 국내에서 사용되고 있는 살충제들인 carbosulfan, furathiocarb 및 benfuracarb를 논 및 밭상태 수분조건별로 토양에 처리하고 토양중 분해양상 및 carbofuran 방출 특성을 조사하였다. 토양에 처리한 유도체들은 토양중에서 carbamoyl N-S간 결합의 붕괴에 따라 carbofuran을 빠른 속도로 방출하였다. 토앙중 분해반감기는 $23{\sim}68$시간 범위로서 유도체 측쇄구조 및 토양수분조건에 영향을 받는 것으로 나타났다. 토양 처리 5일후 유도체농약들의 carbofuran으로의 유효전환율은 $64{\sim}84%$ 범위였으며 유도체형태로의 처리는 carbofuran 직접처리에 비하여 토양중 carbofuran 전류수준의 급격한 상승을 완화, 직접살포에 따른 부작용을 경감시킬 수 있을 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
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• 제19권8호
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• pp.818-822
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• 2009

A ${\beta}-1$,3-1,4-glucanase from the fungus Laetiporus sulphureus var. miniatus was purified as a single 26 kDa band by ammonium sulfate precipitation, HiTrap Q HP, and UNO Q ion-exchange chromatography, with a specific activity of 29 U/mg. The molecular mass of the native enzyme was 52 kDa as a dimer by gel filtration. ${\beta}-1$,3-1,4-Glucanase showed optimum activity at pH 4.0 and $75^{\circ}C$. The half-lives of the enzyme at $70^{\circ}C$ and $75^{\circ}C$ were 152 h and 22 h, respectively. The enzyme showed the highest activity for barley ${\beta}$-glucan as ${\beta}-1$,3-1,4-glucan among the tested polysaccharides and p-nitrophenyl-${\beta}$-D-glycosides with a $K_m$, of 0.67 mg/ml, a $k_{cat}$ of 13.5 $S^{-1}$ and a $k_{cat}/K_m$ of 20 mg/ml/s.

• Environmental Analysis Health and Toxicology
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• 제16권3호
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• pp.139-142
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• 2001

Acetanilide is a High Production Volume Chemical, which is produced about 2,300 tons/year in Korea as of 1998 survey. Most is used as an intermediate for synthesis of pharmaceuticals and dyes, and the chemical is one of seven chemicals of which human and environmental risk are being assessed by National Institute of Environmental Research under the frame of OECD SIDS program. The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) is used to estimates the rate constant for the atmospheric, gas－phase reaction between photochemically produced hydroxyl radicals and organic chemicals. It is also used to estimates the rate constant for the gas－phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half－lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. AOPWIN requires only a chemical structure to make these predictions. Structures are entered into AOPWIN by SMILES (Simplified Molecular Input Line Entry System) notations. In this study, one of environmental fate/distribution of the chemical elements, photodegradation of acetanilide was estimated using AOPWIN model based on SMILES notation and chemical name data.

• Journal of Applied Biological Chemistry
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• 제48권4호
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• pp.187-192
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• 2005

Influence of herbicide oxadiazon on soil microbial activity and nitrogen dynamics was evaluated. Soil samples were treated with oxadiazon at field and tenfold field rates and incubated. Organic amendment was added as an additional substrate for soil microorganisms. Tenfold field rate oxadiazon stimulated substrate-induced respiration (SIR) and dehydrogenase activity (DHA) in amended soil as compared to unamended soil and control treatment. Soil urease activity was not affected by oxadiazon treatment. In both amended and unamended soils, treatment of the herbicide at higher rate had not significant influence on $NH_4$-N and $NO_3$-N concentrations. Higher dose of oxadiazon was degraded in both soils, but dissipation rate in amended soil was higher than unamended soil, with half-lives ($t_{1/2}$) of 23.1 and 138.6 days, respectively. Recommended field rate did not affect microbial activity and nitrogen dynamics in soil ecosystem. Results showed influence of oxadiazon on cycling processes of nitrogen in soil was not significant however its effect on microbial activity was a tendency depending on addition of organic amendment to soil.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.228-233
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• 2008

Effects of chaperones on mRNA stability and gene expression were studied in order to develop an efficient Escherichia coli expression system that can maximize gene expression. The stability of mRNA was modulated by introducing various secondary structures at the 5'-end of mRNA. Four vector systems providing different 5'-end structures were constructed, and genes encoding GFPuv and endoxylanase were cloned into the four vector systems. Primer extension assay revealed different mRNA half-lives depending on the 5'-end secondary structures of mRNA. In addition to the stem-loop structure at the 5'-end of mRNA, coexpression of dnaK-dnaJ-grpE or groEL-groES, representative heat-shock genes in E. coli, increased the mRNA stability and the level of gene expression further, even though the degree of stabilization was varied. Our work suggests that some of the heat-shock proteins can function as mRNA stabilizers as well s protein chaperones.

• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.332-339
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• 2010

The lipase from Mucor racemosus NRRL 3631 was partially purified by fractional precipitation using 60% ammonium sulfate, which resulted in a 8.33-fold purification. The partially purified lipase was then immobilized using different immobilization techniques: physical adsorption, ionic binding, and entrapment. Entrapment in a 4% agar proved to be the most suitable technique (82% yield), as the immobilized lipase was more stable at acidic and alkaline pHs than the free enzyme, plus 100% of the original activity was retained owing to the thermal stability of the immobilized enzyme after heat treatment for 60 min at $45^{\circ}C$. The calculated half-lives (472.5, 433.12, and 268.5 min at 50, 55, and $60^{\circ}C$, respectively) and the activation energy (9.85 kcal/mol) for the immobilized enzyme were higher than those for the free enzyme. Under the selected conditions, the immobilized enzyme had a higher $K_m$ (11.11 mM) and lower $V_{max}$ (105.26 U/mg protein) when compared with the free enzyme (8.33 mM and 125.0 U/mg protein, respectively). The operational stability of the biocatalyst was tested for both the hydrolysis of triglycerides and esterification of fatty acids with glycerol. After 4 cycles, the immobilized lipase retained approximately 50% and 80% of its original activity in the hydrolysis and esterification reactions, respectively.

• Archives of Pharmacal Research
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• 제27권8호
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• pp.878-883
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• 2004

Tacrolimus (FK506), which is isolated from Streptomyces tsukubaensis, is a new potent immu-nosuppressant. Because of poor solubility in water, the conventional intravenous dosage forms of tacrolimus contain surfactants such as cremophor EL (BASF Wyandotte Co.) or hydroge-nated polyoxy 60 castor oil (HCO-60) which may cause adverse effects. This study relates to a polymer-tacrolimus conjugate, which can be dissolved in water, formed by chemically binding the sparingly soluble drug, tacrolimus, with the water soluble polymer, methoxypoly(ethylene glycol) (mPEG). Water soluble tacrolimus-mPEG conjugates have been synthesized and shown to be function in vitro as prodrugs. These conjugates are in the form of an ester wherein the 24-, 32- or 24,32-positions are esterified. The desired 24-, 32- or 24,32-esterified com-pounds were obtained by initially acylating of tacrolimus with iodoacetic acid at the 24-,32-, or 24,32-positions and then reacting the resulting acylated tacrolimus with a mPEG in the pres-ence of a base such as sodium bicarbonate. These conjugates were converted again into tac-rolimus by the action of enzymes in human liver homogenate, and the half-lives of the conjugates are approximately 10 min in the homogenate, indicating that the esterified tacroli-mus derivatives may be practically applicable as a prod rug for the immunosuppressant.