• Journal of Environmental Science International
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• v.19 no.12
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• pp.1323-1334
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• 2010

The effect of nitric oxide (NO) on antioxidant system and protective mechanism against oxidative stress under UV-B radiation was investigated in leaves of maize (Zea mays L.) seedlings during 3 days growth period. UV-B irradiation caused a decrease of leaf biomass including leaf length, width and weight during growth. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated UV-B stress induced growth suppression. NO donor permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under UV-B stress, suggesting that NO has protective effect on chloroplast membrane in maize leaves. Flavonoids and anthocyanin, UV-B absorbing compounds, were significantly accumulated in the maize leaves upon UV-B exposure. Moreover, the increase of these compounds was intensified in the NO treated seedlings. UV-B treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in maize leaves, while NO donor prevented UV-B induced increase in the contents of malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that NO serves as antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, catalase (CAT) and ascorbate peroxidase (APX) in maize leaves in the presence of NO donor under UV-B stress were higher than those under UV-B stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3- oxide (PTIO), a specific NO scavenger, to the maize leaves arrested NO donor mediated protective effect on leaf growth, photosynthetic pigment and free radical scavenging activity. However, PTIO had little effect on maize leaves under UV-B stress compared with that of UV-B stress alone. $N^{\omega}$-nitro-L-arginine (LNNA), an inhibitor of nitric oxide synthase (NOS), significantly increased $H_2O_2$ and MDA accumulation and decreased antioxidant enzyme activities in maize leaves under UV-B stress. This demonstrates that NOS inhibitor LNNA has opposite effects on oxidative resistance. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative stress induced by UV-B radiation and thus confer UV-B tolerance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1708-1716
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• 2016

The Akt/mammalian target of the rapamycin (mTOR) pathway is activated in the majority of human cancers. Activation of the Akt/mTOR pathway confers resistance to many types of cancer therapy. In this study, we evaluated the apoptotic effect of ethanol extract of Artemisia annua L. through down-regulation of Akt signal pathways and the mitochondrial pathway in hepato-carcinoma cells (HepG2). A. annua extract is known as a medicinal herb that is effective against cancer. We evaluated anti-proliferative activity by MTT-based viability assay and apoptotic effect by Annexin-V/PI staining, mitochondrial membrane potential (MMP), and caspase-3/7 activity as determined by flow cytometry. A. annua treatment led to loss of MMP, resulting in cytochrome c-inducible activation of caspase-3/7. Treatment with A. annua extract reduced activities of Akt/mTOR/anti-apoptotic proteins (such as Bcl-2 and $Bcl-X_L$), leading to increased activation of tumor suppressor p53 and pro-apoptotic proteins (such as Bax and Bak). We applied LY294002 (inhibitor of Akt) and rapamycin (inhibitor of mTOR) to determine the relationship between signal transduction of proteins associated with apoptosis. LY294002 and rapamycin significantly reduced cell viability and increased apoptosis. These results indicate that Bcl-2 and caspase-3 are key regulators in A. annua extract-induced apoptosis in HepG2 cells and are controlled through the Akt/mTOR signaling pathway.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.564-577
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• 2016

Salinity stress limits plant cultivation in many areas worldwide; however, persimmon (Diospyros spp.) has high tolerance to salt. Five accessions of Diospyros [three of Diospyros lotus (accession numbers 824, 846, and 847); one of Diospyros kaki var. sylvestris (869); and one of Diospyros virginiana (844)] were chosen for analysis of salinity stress. We compared the effects of salt stress on plant growth, relative water content (RWC), malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide content ($H_2O_2$), and antioxidative enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD; and ascorbate peroxidase, APX) in leaves of healthy potted seedlings from each of the five accessions after salt treatment for 25 days. Salt stress affected the growth of plants in all five accessions, with all three D. lotus accessions showing the most severe effect. Salt stress increased membrane lipid peroxidation in all accessions, but a stronger increase was observed in the three D. lotus accessions. Moreover, accumulation of $H_2O_2$ was faster in salt-sensitive D. lotus compared to salt-tolerant D. virginiana 844. The activities of all antioxidant enzymes increased in D. virginiana 844 and in D. kaki var. sylvestris 869; the activities of SOD, CAT, and APX were at similar levels in D. virginiana 844 and D. kaki var. sylvestris 869, but POD activity was stimulated to a greater extent in D. virginiana 844. The activities of all antioxidant enzymes (except POD) decreased in D. lotus 824 and increased (except for SOD) in D.lotus 846. The activities of SOD and APX decreased in D. lotus 847, whereas POD and CAT activities both increased. Relative water content decreased significantly in D. lotus. No significant changes in lipid peroxidation or relevant antioxidant parameters were detected in any of the accessions in controls treated with 0.0% NaCl. D. virginiana 844 had higher antioxidant capacity in response to salinity compared to other persimmon rootstocks. These results indicate that changes of these key physiological variables are related to salinity resistance in different accessions of persimmon.

• Journal of Life Science
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• v.24 no.5
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• pp.588-593
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• 2014

Tumor angiogenesis is important in tumorigenesis and therapeutic interventions in cancer. To know inhibitor and effector of tumor angiogenesis in cancer, the specific gene of tumor and angiogenesis may develop the mechanisms of cancer suppression and therapy. Recently, we described the role of RalA-binding protein 1 (RLIP76) in tumor angiogenesis. Tumor vascular volumes were diminished, and vessels were fewer in number, shorter, and narrower in RLIP76 knockout mice than in wild-type mice. Moreover, angiogenesis in basement membrane matrix plugs was blunted in the knockout mice in the absence of tumor cells, with endothelial cells isolated from the lungs of these animals exhibiting defects in migration, proliferation, and cord formation in vitro. RLIP76 is expressed in most human tissues and is overexpressed in many tumor types. In addition, the protein regulates tumorigenesis and angiogenesis in vivo and in vitro. As the export of chemotherapy agents is a prominent cellular function of RLIP76, it is a major factor in mechanisms of drug resistance. Moreover, RLIP76 acts as a selective effector of the small GTPase, R-Ras, and regulates R-Ras signaling, leading to cell spreading and migration. Furthermore, in skin carcinogenesis, RLIP76 knockout mice are resistant, with tumors that form showing diminished angiogenesis. Thus, RLIP76 is required for efficient endothelial cell function and angiogenesis in solid tumors.

• Journal of Life Science
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• v.28 no.6
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• pp.733-737
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• 2018

Cucurbitacin-I, a natural triterpenoid derived from Cucurbitaceae family plants, exhibits a number of potentially useful pharmacological and biological activities. Indeed, the previous study demonstrated that cucurbitacin-I reduced the proliferation of colon cancer cells by enhancing apoptosis and causing cell cycle arrest at the G2/M phase. CD44, a type I transmembrane protein with the function of adhering to cells, mediates between the extracellular matrix and other cells through hyaluronic acid. Recent studies have demonstrated that an overexpression of the CD44 membrane receptor results in tumor initiation and growth, specific behaviors of cancer stem cells, the development of drug resistance, and metastasis. The aim was to examine the effect of cucurbitacin-I on CD44 expression human ovarian cancer cells because the effect of cucurbitacin-I on CD44 expression has not been reported. The expressions of CD44 mRNA and protein were detected using a quantitative real-time reverse-transcription polymerase chain reaction and a Western blot analysis, respectively. Treatment with cucurbitacin-I inhibited the expression of CD44 mRNA and protein. A subsequent analysis revealed that cucurbitacin-I blocked the phosphorylation of activator protein-1 (AP-1) and nuclear factor kappa-B ($NF-{\kappa}B$), which are key regulators of CD44 expression. Taken together, the data demonstrate that cucurbitacin-I regulates the AP-1 and $NF-{\kappa}B$ signaling pathways, leading to decreased CD44 expression.

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.323-331
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• 1995

Monocyte/macrophage infiltration is the well known initial features associated with the development of glomerular disease including non-immune mediated nephropathy. Tumor necrosis factor ${\alpha}(TNF{\alpha})$, a cytokine produced primarily by monocyte/macrophage, exhibits similar effects as observed at the initial stages and during the progression of glomerular injury. Because the mesangial cells are target cells for glomerular injury, the present study examined the effect of $TNF{\alpha}$ on glomerular mesangial cell membrane lipid peroxidation as an index of cytotoxicity attributing to $TNF{\alpha}$. Primary culture of rat mesangial cell was established by incubation of glomeruli isolated from male Sprague-Dawley rat kidneys utilizing a standard sieving method. The levels of lipid peroxides in the mesangial cells were quantitated by malondialdehyde- thiobarbituric acid adduct formation. During an 8 hour incubation at $37^{\circ}C$, $TNF{\alpha}$ at 10 to 10,000 units/ml increased the levels of lipid peroxides dose dependently. Western blot analysis demonstrated that a short thermal stress induced heat shock response and the synthesis of heat shock protein 70(hsp70) in this mesangial cells. Further, this induction of hsp 70 prevented increase of lipid peroxides in the mesangial cells exposed to $TNF{\alpha}$. These data suggest that $TNF{\alpha}-induced$ lipid peroxidation in the mesangial cells may have pathophysiological relevance to glomerular injury and prior induction of heat shock response may play a role in the cellular resistance against $TNF{\alpha}-induced$ glomerular injury.

• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.399-406
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• 1986

This study was performed to establish human plasmacytoma cell line as the partner cells for producing human hybridoma. Bone marrow cells from a multiple myeloma patient from Seoul National University Hospital, Korea were cultured and established as the cell line, named as HMC-BM4. HMC-BM4 cells were cultivated in RPMI 1640 media containing 8-azaguanine(8-AG; gradually increasing concentration from $1\;{\mu}g/ml$ to $20\;{\mu}g/ml$). 8-AG resistant cells were collected and cloned by limiting dilution. Each clone was divided and tested to die in hypoxanthine, aminopterine and thymidine (HAT) selection media. Finally one clone was selected and named as HMC-AR, which was sensitive to HAT selection media. HMC-AR cells showed typical morphology of plamacytoma in Wright staining. No cell formed the rosette with sheep erythrocytes. Surface membrane $\mu$ heavy chain was detected in 20% of HMC-AR cells and cytoplasmic $\mu$ heavy chain in 90% of them by direct immunofluorescent staining. Ia-like antigen was found in 90% of HMC-AR cells by indirect immunofluorescent staining using anti-Ia-like antigen monoclonal antibody, 1BD9-2. And about $1.0\;{\mu}g/ml$ of human $\mu$ heavy chain was detected in the 3-day culture supernatant of HMC-AR cells. 88% of cells contained 46 chromosomes. Mycoplasma was not detected in HMC-AR cells by Hoechst 33258 staining. This cell line would be used for making hybridomas secreting human monoclonal antibody.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.633-643
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• 2017

To examine the pro-apoptotic role of the human ortholog (YPEL5) of the Drosophila Yippee protein, the cell viability of Saccharomyces cerevisiae mutant strain with deleted MOH1, the yeast ortholog, was compared with that of the wild-type (WT)-MOH1 strain after exposure to different apoptogenic stimulants, including UV irradiation, methyl methanesulfonate (MMS), camptothecin (CPT), heat shock, and hyperosmotic shock. The $moh1{\Delta}$ mutant exhibited enhanced cell viability compared with the WT-MOH1 strain when treated with lethal UV irradiation, 1.8 mM MMS, $100{\mu}M$ CPT, heat shock at $50^{\circ}C$, or 1.2 M KCl. At the same time, the level of Moh1 protein was commonly up-regulated in the WT-MOH1 strain as was that of Ynk1 protein, which is known as a marker for DNA damage. Although the enhanced UV resistance of the $moh1{\Delta}$ mutant largely disappeared following transformation with the yeast MOH1 gene or one of the human YPEL1-YPEL5 genes, the transformant bearing pYES2-YPEL5 was more sensitive to lethal UV irradiation and its UV sensitivity was similar to that of the WT-MOH1 strain. Under these conditions, the UV irradiation-induced apoptotic events, such as FITC-Annexin V stainability, mitochondrial membrane potential (${\Delta}{\psi}m$) loss, and metacaspase activation, occurred to a much lesser extent in the $moh1{\Delta}$ mutant compared with the WT-MOH1 strain and the mutant strain bearing pYES2-MOH1 or pYES2-YPEL5. These results demonstrate the functional conservation between yeast Moh1 and human YPEL5, and their involvement in mitochondria-dependent apoptosis induced by DNA damage.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.120-126
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• 2018

As a basic study for environment-friendly production of bacterial cellulose (BC) dressing with antimicrobial activity, we isolated and identified acetic acid bacteria which are resistant to silver ions and can biosynthesize silver nanoparticles. Furthermore, conditions of BC production by selected strain were also investigated. Strain G7 isolated from decayed grape skin was able to grow in the presence of 0.1 mM $AgNO_3$ which was identified as Acetobacter intermedius based on 16S rRNA gene analysis. BC production was the highest in a medium containing 2% glucose as a carbon source, 2% yeast extract as a nitrogen source, and 0.115% acetic acid as a cosubstrate. Structural properties of BC produced in optimal medium were studied using Fourier-transform infrared spectroscopy and X-ray diffractometer, and it was found that BC produced was cellulose type I that was the same as a typical native cellulose. When strain G7 was cultured in an optimal medium containing 0.1 mM $AgNO_3$, the color of the culture broth turned into reddish brown, indicating that silver nanoparticles were formed. As a result of UV-Vis spectral analysis of the culture, it was found that a unique absorption spectrum of silver nanoparticles at 425 nm was also observed. Scanning electron microscopic observations showed that silver nanoparticles were formed on the surface and pores of BC membrane.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.2
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• pp.123-127
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• 2003

Chemical burns onto oral mucosa which are infrequent, may result from contact with a wide variety of chemical agents. The degree of injury depends on the chemical, its concentration, duration of contact, and the natural penetrability and resistance of the tissues involved. Chemicals do not usually "burn" in that they do not cause destruction by hyperthermic activity. Rather, they damage tissue by causing coagulation of protein by one of several processes, reduction, oxidation, desiccation, corrosion, or vesication. Paraquat(Gramoxon) is the most frequently agricultural chemicals that induce the severe toxic reactions onto the organs of human body in Korea. The toxic reaction are composed of pulmonary edema and fibrosis, formation of hyaline membrane, inflammatory reaction and bleeding tendency, owing to the cell damage by the production of superoxide radicals. The contents of essential treatment in paraquat intoxication are commonly airway and breathing maintenance, gastric lavage, much hydration and diuresis, hemoperfusion and medications for the removal of the chemicals and the prevention of various complications. The sedative oral dressings, such as, orabase ointment application, warm saline gargling, lidocaine viscous gargling and oral gargling by the mixed solutions(tetracycline, prednisolone and 10% dextrose water) are important for the improvement of chemical oral mucositis and the comfortable feeding of diet. The authors managed properly two cases of oral chemical mucositis that were occurred by the incorrect use of agricultural chemicals(paraquat) and report the cases with the review of literatures about care of the chemical intoxication and oral mucositis.