• Biomedical Science Letters
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• v.23 no.1
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• pp.30-33
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• 2017

N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) is a carcinogen made of modified guanine on which alkyl group is added on 6th oxygen. It has been used for inducing different types of cancers experimentally in vivo and in vitro. Stomach cancer might be the best well established particular cancer induced with MNNG. Comparative analysis of gene expression between normal stomach cell and MNNG-treated stomach cell could give much information to understand cancer formation in stomach. To this end, normal human stomach cells HS738 were treated with DMSO or MNNG. Genetic comparison was conducted with purified RNA from the treated cells for 6 hours or 24 hours. Total 13 genes were selected based on their high induction folds and comprehensible function to cancer formation. Some of the genes were cancer-promoting whereas the others were anti-cancer genes. These results could give important information of genetic changes in stomach cells during MNNG-induced stomach cancer formation.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.68.1-68
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• 2003

When plants are infected by plant pathogens, typical disease symptom termed lesion, appears in compatible interaction. Whereas, in incompatible interactions, only small speck of lesions are visible on the leaf surfaces. Hypersensitive response (HR) of plant which is the result of infection by incompatible pathogens, is a well known defense response inducing rapid cell death resulting in complete resistance. However, some rice mutants show spontaneous disease symptoms during the growth stages without interaction with pathogens. We investigated the spontaneous cell death mutant called Blast Lesion Mimic(BLM) generated by EMS mutation, on the relationship with the hypersensitive response as well as resistant characteristics. Accumulation of phenolic compounds were detected around the lesions as lesions develop on leaf surface. Activation of PR gene was detected before the lesion appeared, and that result indicates the defense-related response are started earlier than lesion formation. The BLM mutant showed resistant response to inoculation of Magnaporthe grisea KJ201 with which the wild type Hwacheong is totally susceptible. Informations on the formation of spontaneous lesions and detail analysis of lesion mimic mutants and related genes are very limited to date. It is really important to understand the phenomenon of the defense-related lesion formation for developing resistant cultivar for rice blast pathogens

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.162-168
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• 1990

The aims of the present study were to evaluate the effects of culture conditions on the biosynthesis of extra-cellular alkaline protease in Streptomyces sp. The formation of aerial mycelia and spores were compared with the protease production in order to know the relations between the alkaline protease and the cell differentiation. As results, it was found that substrate concentration was very critical to regulate the formation of the protease, aerial mycelia, and spores, which were resulted from the changes of culture pH to acid. When the culture pH was adjusted with phosphate buffer from pH 6 to pH 9, the alkaline protease production was increased as the culture pH increased whereas aerial mycelia and spore formation were reversely related to the culture pH. Therefore, it was thought that the culture pH was an important factor to regulate the alkaline protease synthesis.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1026-1035
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• 2015

Condensin is not only responsible for chromosome condensation, but is also involved in double-strand break (DSB) processing in the cell cycle. During meiosis, the condensin complex serves as a component of the meiotic chromosome axis, and mediates both proper assembly of the synaptonemal complex and DSB repair, in order to ensure proper homologous chromosome segregation. Here, we used the budding yeast Saccharomyces cerevisiae to show that condensin participates in a variety of chromosome organization processes and exhibits crucial molecular functions that contribute to meiotic recombination during meiotic prophase I. We demonstrate that Ycs4 is required for efficient DSB formation and establishing homolog bias at the early stage of meiotic prophase I, which allows efficient formation of interhomolog recombination products. In the Ycs4 meiosis-specific allele (ycs4S), interhomolog products were formed at substantial levels, but with the same reduction in crossovers and noncrossovers. We further show that, in prophase chromosomal events, ycs4S relieved the defects in the progression of recombination interactions induced as a result of the absence of Rec8. These results suggest that condensin is a crucial coordinator of the recombination process and chromosome organization during meiosis.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2827-2832
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• 2015

Oxidative stress is associated with colon carcinogenesis including aberrant crypt foci (ACF) formation and it plays an important role in pathophysiological changes in cancer cells. The aims of this study were to investigate the effects of dietary unpolished Thai rice (UTR) on ACF formation and dysplastic progression in azoxymethane (AOM)-treated rats. Anti-cancer efficacy of UTR regarding apoptotic induction and oxidative redox status in human colon cancer (CaCo-2) cells was also investigated. Rats given 20% and 70% of UTR in the diet showed significantly and dose-dependently decreased total number of ACF. UTR treatment also was strongly associated with the low percentage of dysplastic progression and mucin depletion. In addition, we found that UTR significantly induced cancer cell apoptosis, increased cellular oxidants, and decreased the level of GSH/GSSG ratio in CaCo-2 cells. Our study suggests that UTR supplementation may be a useful strategy for CRC prevention with the inhibition of precancerous progression, with induction of cancer cell apoptosis through redox alteration.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.163-175
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• 2004

This study was performed to evaluate bone formation in the calvaria of rabbit by the concept of guided bone regeneration with titanium mesh membrane and demineralized freeze-dried bone. The animal was sacrificed at 2 weeks, 4 weeks, 8 weeks, and 12 weeks after the surgery. Non-decalcified specimens were processed for histologic analysis. 1. The titanium mesh but the biocompatibility was excellent the cell-occlusiveness was feeble. 2. The cell-occlusiveness was feeble and also the soft tissue growth of the upper part of the newly-formed bone after operating was excellent in early stage. 3. The maintenance ability of the space for the GBR very was excellent. 4. The titanium mesh the tissue-integration was superior the wound fixation ability excellent. 5. The demineralized freeze-dried bone did not promote the bone regeneration. 6. With the lapse of time, formation quantity of the bone some it increased, it increased quantity very it was feeble. Within the above results, the titanium mesh for the guided bone regeneration was excellent, the dεmineralized freeze-dried bone confirmed does not promote bone regeneration.

• BMB Reports
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• v.49 no.8
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• pp.449-454
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• 2016

Stress Granules (SGs) are microscopically visible, phase dense aggregates of translationally stalled messenger ribonucleoprotein (mRNP) complexes formed in response to distinct stress conditions. It is generally considered that SG formation is induced to protect cells from conditions of stress. The precise constituents of SGs and the mechanism through which SGs are dynamically regulated in response to stress are not completely understood. Hence, it is important to identify proteins which regulate SG assembly and disassembly. In the present study, we report Neuregulin-2 (NRG2) as a novel component of SGs; furthermore, depletion of NRG2 potently inhibits SG formation. We also demonstrate that NRG2 specifically localizes to SGs under various stress conditions. Knockdown of NRG2 has no effect on stress-induced polysome disassembly, suggesting that the component does not influence early step of SG formation. It was also observed that reduced expression of NRG2 led to marginal increase in cell survival under arsenite-induced stress.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.423-428
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• 2010

The aim of this study was to evaluate the in vivo effect of galangin and the 70% ethanolic extract of Alpinia officinarum (AO) toward $KBrO_3$-induced DNA and chromosomal damage in mice. Galangin and AO inhibited the formation of 8-hydroxy-2'-deoxyguanosine (8-OH2'dG) as an indicator of DNA oxidative damage in the liver cell. Galangin and AO showed the inhibitory effect on the formation of DNA single strand break in the splenocyte by single cell gel electrophoresis (SCGE) assay and also inhibited micronucleated reticulocyte (MNRET) formation of peripheral blood in tail blood of mice. Vit-E revealed antigenotoxic effects in DNA and chromosome levels, but galangin was more potent active compound compare to vit-E under our experimental conditions. The results suggest that the extract of Alpinia officinarum containing galangin can modify the oxidative DNA and chromosomal damage and may act as chemopreventive agent against oxidative stress in vivo.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2006.04a
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• pp.123-135
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• 2006

Alzheimer's disease (AD) is the most common form of dementia in the aging population and is clinically characterized by a progressive loss of cognitive abilities. Pathologically, it is defined by the appearance of senile plaques - extracellular insoluble, congophilic protein aggregates composed of amyloid $\beta$ (A$\beta$) and neurofibrillary tangles (NFTs) - inyracellular lesions consisting of paired helical filaments from hyperphosphorylated cytoskeletal tau protein as described by Alois Alzheimer a century ago. These hallmarks still serve as the major criteria for a definite diagnosis of the disease. Consequently, one of the key strategy for drug development in this disease area focuses on reducing the concentration of cerebral A$\beta$ plaque by using substances that inhibit A$\beta$ fibril formation. We focused on developing inhibitors by synthesizing several kinds of aromatic molecules. The synthetic compounds were initially screened to evaluate the effective compound by tioflavin T fluorescence assay. The selected effective compounds were tested cytotoxicity and protective effect from A$\beta$-induced neuronal toxicity by cell based MTT assay with HT22 hippocampal neurons. The BBB permeability on effectors was also tested in in vitro co-culture model(HUVEC/C6 cell line). The behavior test wea carried out in mutant APP/PS1 transgenic mouse model of Alzheimer's disease. And inhibition of A$\beta$ fibril formation by the effective compound was monitored with transmitted electron microscopic images.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.595-600
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• 2020

The photovoltaic properties of perovskite solar cells (PSCs) with a carbon electrode fabricated using different annealing processes are investigated. Perovskite formation (50 ℃, 60 min) using a hot-plate and an oven is carried out on cells with a glass/fluorine doped TiO₂/TiO₂/ZrO₂/carbon structure, and the photovoltaic properties of the PSCs are analyzed using a solar simulator. The microstructures of the PSCs are characterized using an optical microscope, a field emission scanning electron microscope, and an electron probe micro-analyzer (EPMA). Photovoltaic analysis shows that the energy conversion efficiency of the samples fabricated using the hot-plate and the oven processes are 2.08% and 6.90%, respectively. Based on the microstructure of the samples and the results of the EPMA, perovskite is formed locally on the carbon electrode surface as the γ-butyrolactone (GBL) solvent evaporates and moves to the top of the carbon electrode due to heat from the bottom of the sample during the hot plate process. When the oven process is used, perovskite forms evenly inside the carbon electrode, as the GBL solvent evaporates extremely slowly because heat is supplied from all directions. The importance of the even formation of perovskite inside the carbon electrode is emphasized, and the feasibility of oven annealing is confirmed for PSCs with carbon electrodes.