• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.766-771
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• 2004

Julong 601, a Gram-positive anaerobic bacterium strain capable of cleaving the C-ring of isoflavones daidzein and genistein, was isolated from human feces. BLAST search revealed that its complete 16S rDNA gene sequence has 99% similarity to Eubacterium ramulus. Metabolites of daidzein and genistein were determined as O-desmethylangolensin (O-Dma) and 2-(4-hydroxyphenyl) propionic acid (2-HPPA), respectively, based on UV, EI-MS, and $^1H$ and ^{13}C$ NMR spectral analyses. Enantiomers of O-Dma and 2-HPPA were isolated by chiral stationary-phase HPLC (CSP HPLC). Cleavage of the C-ring of daidzein and genistein by strain Julong 601 was highly enantioselective. Specific rotation ([$\alpha]_D$) and circular dichroism (CD) spectra of the enantiomers are reported here for the first time. Biotransformation kinetics of daidzein and genistein indicated that the C-ring of genistein has a higher susceptibility to bacterial degradation than that of daidzein.

• 한국미생물·생명공학회지
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• 제32권4호
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• pp.362-365
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• 2004

The fucoidan from Laminaria relicollected at Wando in Korea was purified with the yield of 2.3% in mass. The monosaccharide composiof the purified fucoidan was nearly identical to that of the commercial standard: fucose 63.71 %, xylose 22.98%, galactose 6.62%, mannose 0.24%, and uronic acid 3.26%. Microorganisms capable of degrading the purified fucoidan were isolated from the colonies on the minimal medium containing 0.2% of purified fucoidan as a sole carbon source. Of these isolates, a strain showing a relatively higher capability to degrade fucoidan, up to 63%, was partially characterized as a Gram positive, aerobic, moderately halophilic marine bacterium.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.171-176
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• 2000

Bioremediation of hazardous hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), is a major environmental concern due to their toxic and carcinogenic properties. Due to their hydrophobicity, the hydrophobic organic compounds are mainly associated with the soil organic matter or nonaqueous-phase liquids. A major question concerns the relationships between biodegradation and sorption. This work develops and utilizes a non- steady state model for evaluating the interactions between sorption and biodegradation of phenanthrene, a 3-ring PAH compound, in soil-slurry systems. The model includes sorption/desorption of a target compound, its utilization by microorganisms as a primary substrate existing in the dissolved phase and/or the sorbed phase in biomass and soil, oxygen transfer, and oxygen utilization as an electron acceptor. Biodegradation tests with phenanthrene were conducted in liquid and soil-slurry systems. The soil-slurry tests were performed with very different mass transfer rate: fast mass transfer in a flask test at 150 rpm, and slow mass transfer in a roller-bottle test at 2 rpm. In the slurry tests, phenanthrene was degraded more rapidly than in liquid tests, but with a similar rate in both slurry systems. Modeling analyses with several hypotheses indicate that a model without biodegradation of compound sorbed to the soil was not able to account for the rapid degradation of phenanthrene, particularly in the roller bottle slurry test. Reduced mass-transfer resistance to bacteria attached to the soil is the most likely phenomenon accounting for rapid sorbed-phase biodegradation.

• Toxicological Research
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• 제22권4호
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• pp.349-356
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• 2006

Diallyl disulfide (DADS), an oil-soluble organosulfur compound in garlic has been reported to suppress tumor growth and to induce apoptosis in cancer. In the present study, we investigated the effects of DADS on pulmonary metastasis of B16-F10 murine melanoma cells. DADS (i.p. 40 mg/kg) significantly (p<0.05) reduced the number of pulmonary metastatic nodules (48%) in experimental pulmonary metastasis assay. We also found that DADS inhibited adhesion, invasion and migration of B16-F10 melanoma cells in a dose-dependent manner. To study the antimetastatic potential of DADS, we performed the effects of DADS on matrix metalloproteinase activity. DADS significantly inhibited the expression of matrix metalloproteinase-2 activity in B16-F10 cells by gelatin zymography. These results suggest that DADS prevent metastasis in part through suppression of migration of B16-F10 melanoma cells by Inhibiting matrix metalloproteirase-2 responsible for degradation of extracellar matrix.

• Toxicological Research
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• 제29권4호
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• pp.235-240
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• 2013

Extracellular accumulation of amyloid beta protein ($A{\beta}$) plays a central role in Alzheimer's disease (AD). Some metals, such as copper, lead, and aluminum can affect the $A{\beta}$ accumulation in the brain. However, the effect of mercury on $A{\beta}$ accumulation in the brain is not clear. Thus, this study was proposed to estimate whether mercury concentration affects $A{\beta}$ accumulation in PC12 cells. We treated 10, 100, and 1000 nM $HgCl_2$ (Hg) or $CH_3HgCl_2$ (MeHg) for 48 hr in PC12 cells. After treatment, $A{\beta}_{40}$ in culture medium increased in a dose- and time-dependent manner. Hg and MeHg increased amyloid precursor protein (APP), which is related to $A{\beta}$ production. Neprilysin (NEP) levels in PC12 cells were decreased by Hg and MeHg treatment. These results suggested that Hg induced $A{\beta}$ accumulation through APP overproduction and reduction of NEP.

• 생명과학회지
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• 제14권1호
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• pp.17-20
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• 2004

대장균 트립토판 합성효소의 $\beta$반응의 빠른 속도 반응에 일가 양이온의 영향을 D56N과 D56G 잔기치환체를 대상으로 조사하였다. 일가 양이온을 처리하였을 때 생성되는 중간반응 생성물의 생성과 분해 속도가 영향을 받았다. 56번 자리 잔기치환체도 야생형에 비해 반응의 중간산물의 생성과 분해에 있어 모두 느린 속도를 보여주고 있다. 이들 잔기 치환체에 미치는 일가 양이온의 영향 또한 달라졌다. 이 결과는 대장균의 효소에서도 56번잔기가 이소조절에 관여하고 있고, 이 과정에서 일가 양이온들이 이소조절 리간드역할을 수행하는 것을 보여준다.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2006년도 추계학술대회
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• pp.19-24
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• 2006

Mothers against decapentaplegic homolog 4 (SMAD4) is a tumor suppressor gene associated with gastrointestinal carcinogenesis. The aim of the present study was to characterize more precisely its role in the development and progression of human gastric carcinoma. In this study, using tissue microarray analysis of 283 gastric cancers and related lesions, we found loss of SMAD4 protein expression in the cytoplasm (36/114, 32%) and in the nucleus (46/114, 40%) of gastric cancer cells. The loss of nuclear SMAD4 expression in primary tumors correlated significantly with poor survival, and was an independent prognostic marker in multivariate analysis. We also found a substantial decrease in SMAD4 expression at both the RNA and protein level in several human gastric carcinoma cell lines. To identify the genetic and/or epigenetic mechanisms of altered SMAD4 expression in gastric carcinoma, loss of heterozygosity (LOH), promoter hypermethylation, and exon mutations were examined. We found that LOH (20/70, 29%) and promoter hypermethylation (4/73, 5%) were associated with the loss of SMAD4 expression. SMAD4 protein levels wore also affected in certain gastric carcinoma cell lines following incubation with Mc132, a proteasome inhibitor. Taken together, our results indicate that the loss of SMAD4, especially loss of nuclear SMAD4 expression, is involved in gastric cancer progression. The loss of SMAD4 in gastric carcinomas is due to several mechanisms, including LOH, hypermethylation, and proteasome degradation.

• 공업화학
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• 제21권3호
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• pp.243-251
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• 2010

연소배가스에 존재하는 질소산화물의 제거를 위해서는 촉매 환원, 흡수, 흡착 등 화학적 기술이 적용되고 있는데, 장기적으로는 환경친화적이고 에너지 소모가 적은 생물학적 공정의 개발 및 이용이 필요하다. 본 논문에서는 연소 배가스에 존재하는 질소산화물을 제거하기 위한 생물학적 공정의 기술동향을 살펴보고 각각의 장단점을 고찰하였다. 질산화와 탈질 기작을 이용하는 박테리아 시스템과 광합성 미세조류를 이용하는 시스템으로 구분하여 기술의 원리와 현재의 기술 수준을 논하였다. 두 경우 모두 처리속도를 높이기 위해서는 불용성의 일산화질소를 일단 적절한 흡수제에 고농도로 포집시킨 후 미생물에 의하여 분해 또는 고정하는 방향이 바람직하며, 배가스 중 $CO_2$와 NOx를 동시에 고정이 가능하고 별도의 탄소원이 요구되지 않는 미세조류의 활용이 기대된다.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.27-37
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• 1997

Internal combustion engine is the main source of environmental pollutants and therefore better technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, harmful elements from the exhaust gases are caused by incomplete combustion of mixture inside the engine cylinder and this abnormal combustion like misfire or partial burning is the direct cause of the air pollution and engine performance degradation. the object of this research is to detect abnormal combustion like misfire and to keep the engine performance in the optimal operating state. Development of a new system therefore could be applied to a real car. To realize this, the spark-plug in a conventional ignition system is used as a misfire detection sensor and breakdown voltage is analyzed. In this research, bias voltage(about 3kV) was applied to the electrodes of spark-plug and breakdown voltage signal is obtained. This breakdown voltage signal is analyzed and found that a combustion phenomena in engine cylinder has close relationship with harmonic coefficient K which was introduced in this research. Newly developed combustion diagnostic method( breakdown voltage signal analysis) from this research can be used for the combustion diagnostic and combustion control system in an real car.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.40-45
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• 2007

Methylene blue(MB) was photocatalytically degraded with one-body photoanode and solar simulator to investigate the possible application to both environmental purification and photoelectrochemical cell for hydrogen production. Photoactive titanium dioxide was formed on both sides of Ti plate following steps such as rinsing-annealing-calcination or anodizing(20 V, 30 V)-annealing($350^{\circ}C$, $450^{\circ}C)$ after etching. The prepared titania plate($2cm{\times}2\;cm$, ca 1.6 mg $TiO_2$ on the basis of $1\;{\mu}m$ thickness) was used to degrade MB(10 ppm in 200 mL solution). The reaction tended to follow the Langmuir-Hinshelwood kinetics with zero order. Comparative experiments with Degussa P25 showed the same zero order kinetics when 2 mg of P25 had been used, while the first order kinetics when 200 mg used. This concludes the feasibility of the prepared titania plate as a material for the purification of low-level harmful organics and an electrode or a membrane for photoelectrochemical system for hydrogen production.