• Journal of Astronomy and Space Sciences
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• v.6 no.1
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• pp.57-72
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• 1989

A total of 80 photographs on 29 nights and another total of 44(22 each in B and V) photoelectric observations on 6 nights are secured for P/Halley(1982 ⅰ) for seven months before and after the perihelion passage. The photographic observations have been mode at different places depending on the position of the comet and the development of the tail, while the photoelectric observations were made only with 61-cm reflector at Yonsei University Observatory(YUO). Four most representative photographs are presented only to illustrate the remarkable features of the comet. The second one of these shows a coma with a possible flash activity on 1985 SEPT. 18.56 UT. The third one shows the largest tail recorded among our plates, and the last one prepresents unusual record made on northern hemisphere at a latitude as high as about $33^{circ}$12' N on the occasion of the comet's second perigee on 1976 APR. 11.6 UT. Photoelectric observations, on the other hand, determine the V and B-V of the total and the coma of the comet before its perihelion passage, and exhibit the light variations of 0m.6 in V in an hour and a half. Two new sets of m and n, one before and the other after the perihelion passage, determined based on the collected data, but the values are dissimilar one another significantly.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1076-1081
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• 2001

Gamma-irradiated peanuts, Korean and Chinese origins, were investigated on detection properties by thermoluminescence (TL), electron spin resonance (ESR), and DNA comet assay (single cell gel electrophoresis). TL measurement showed that the non-irradiated sample revealed a glow curve with low intensity at about 25$0^{\circ}C$, while the irradiated samples showed higher intensity around at 18$0^{\circ}C$. TL ratio (TL$_1$/TL$_2$) of area for TL$_1$ glow curve to TL$_2$ was below 0.05 for the non-irradiated sample and 0.2 or more for the irradiated ones, thus identifying each other. ESR spectroscopy for the irradiated peanuts using outer skin showed negligible signals induced by irradiation, indicating ESR is little applicable to the detection of irradiated peanuts. In DNA comet assay, the non-sample had no or very short tails, whereas the irradiated samples revealed the cells with long tails. Significance in the increase of their lengths depending on irradiation dose (r=0.761/Korean, r=0.768/Chinese) was also found. There was no remarkable difference in detection properties by origins of samples in all determinations, It is concluded that TL analysis or DNA comet assay is suitable for detection of irradiated peanuts and a combined method is recommendable for enhancing the reliability of detection results.

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.128-134
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• 2001

Single cell gel electrophoresis (SCGE) assay, also called comet assay, is a rapid and sensitive method to detect DNA damage in single cell level. To evaluate the DNA damage of lymphocytes of pesticides sprayers, SCGE assay was carried out for 50 pesticides sprayer and 58 control subjects. They were interviewed with structured questionnaire to get the information about the kinds and amount of pesticide. Insecticides and fungicides were predominant among pesticides. Major components of pesticides were organophosphorus, organosulfate, cartap, carbamates, and triazole. Sprayed pesticides were classified into two groups. Group I included organophosphorus, organoarsenic, organotin, tetrazine, triazole and gramoxone, which were known to cause DNA damages. Group II pesticide were carbamates, surfactants, organosulfates, etc., which were not found as DNA damaging agents in scientific documents. Olive tail moments of 100 lymphocytes were measured by KOMET 3.1 program for each person. The means of tail moments were compared between farmers exposed to pesticides and control subjects. Farmers showed higher tail moments than control subjects (2.07$\pm$1.40 vs 1.53$\pm$0.77, p<0.05). The means of tail moments also were compared among group I sprayers (n=36), group II sprayers (n=24) and, control subject, and the means or tail moments were 3.4s$\pm$3.2o, 2.66$\pm$2.20 and 1.53$\pm$0.77 respectively. The difference between means of group I sprayers and controls was statistically significant (p<0.05). In conclusion, this study showed higher DNA damage in farmers exposed to pesticides than control subjects, and comet assay could be useful as a biological monitoring method of genotoxic pesticides for farmers.

• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.183-187
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• 2007

The detection and measurement of faint features in cometary image is generally troublesome due to the high value of the ratio of the brightness of the nucleus to the tail, the large size and low surface brightness of the coma and tail and the disturbing presence of field stars trails. The image processing is based on background removal by median filtering. Sample results are shown for the case study of comet 73P/Schwassmann-Wachmann 3.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.123-128
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• 2015

Previously, we investigated extremely low-frequency magnetic fields (ELF-MFs) on diverse DNA damage responses, such as phosphorylated H2AX (${\gamma}H2AX$), comet tail moments, and aneuploidy production in several non-tumorigenic epithelial or fibroblast cell lines. However, the effect of ELF-MF on DNA damage responses in neuronal cells may not be well evaluated. Here, we investigated the effects of ELF-MF on the DNA damage responses in HT22 non-tumorigenic mouse neuronal cells. Exposure to a 60-Hz, 2 mT ELF-MF did not produce any increased ${\gamma}H2AX$ expression, comet tail moments, or aneuploidy formation. However, 2 mT ELF-MF transiently increased the cell number. From the results, ELF-MF could affect the DNA damage responses differently, depending on the cell lines.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.575-578
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• 2004

High resolution observations of cluster of galaxies by Chandra have revealed the existence of an X-ray emitting comet-like galaxy C153 in the core of cluster of galaxies A2125. The galaxy C153 moving fast in the cluster core has a distinct X-ray tail on one side, obviously due to ram pressure stripping, since the galaxy C153 crossed the central region of A2125. The X-ray emitting plasma in the tail is substantially cooler than the ambient plasma. We present results of two-dimensional magnetohydrodynamic simulations of the time evolution of a sub clump like C153 moving in magnetized intergalactic matter. Anisotropic heat conduction is included. We found that the magnetic fields are essential for the existence of the cool X-ray tail, because in non-magnetized plasma the cooler sub clump tail is heated up by isotropic heat conduction from the hot ambient plasma and does not form such a comet-like tail.

• Journal of Nutrition and Health
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• v.36 no.1
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• pp.24-31
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• 2003

The present study was attempted to investigate the antioxidant capacity of popular yellow-green vegetable juices (kale, Angelica keishei, carrot, small water dropwort) and to investigate the effect of vegetable juices on protecting oxidative damage to DNA in cultured Chinese hamster lung (CHL) cells. Antioxidant capacity was analyzed by TRAP assay (Total radical-trapping antioxidant potential). Cellular DNA dmamage was measured by SCGE (single-cell gel electrophoresis, also known as comet assay. Cells incubated in medium with PBS (negative control) or with various concentration of the freeze dried green juices (25, 50, 100, 250 $\mu\textrm{g}$/$m\ell$) resuspended in PBS were treated with $H_2O_2$ (200 ${\mu}{\textrm}{m}$) as an oxidative stimulus for 5 min at 4$^{\circ}C$. The physiological function of each vegetable juice on oxidative DNA damage was analyzed and expressed as tail moment (tail length X percentage migrated DNA in tail) . Kale juice had the highest TRAP value suggesting that kale has the highest antioxidant capacity followed by Angelica keishei, small water dropwort and carrot. Cells treated with $H_2O_2$ had extensive DNA damage compared with cells treated with PBS or pre-treated with vegetable juice extracts. All green juices inhibited $H_2O_2$-induced DNA damage with kale being the most effective juice among the tested juices. These results indicate that green juice supplementation to CHL cells followed by oxidative stimulus inhibited damage to cellular DNA, supporting a protective effect against oxidative damage induced by reactive oxygen species. (Korean J Nutrition 36(1) : 24-31, 2003)

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.373-380
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• 2004

Objectives : There has been gradually increasing concern about the adverse health effects of electromagnetic radiation originating from cell phones which are widely used in modern life. Cell phone radiation may affect human health by increasing free radicals of human blood cells. This study has been designed to identify DNA damage of blood cells by electromagnetic radiation caused by cell phone use. Methods : This study investigated the health effect of acute exposure to commercially available cell phones on certain parameters such as an indicator of DNA damage for 14 healthy adult volunteers. Each volunteer during the experiment talked over the cell phone with the keypad facing the right side of the face for 4 hours. The single cell gel electrophoresis assay (Comet assay), which is very sensitive in detecting the presence of DNA strand-breaks and alkali-labile damage in individual cells, was used to assess peripheral blood cells (T-cells, B-cells, granulocytes) from volunteers before and after exposure to cell phone radiation. The parameters of Comet assay measured were Olive Tail Moment and Tail DNA %. Results : The Olive Tail Moment of B-cells and granulocytes and Tail DNA % of B-cells and granulocytes were increased by a statistically significant extent after 4-hour use of a cell phone compared with controls. Conclusion : It is concluded that cell phone radiation caused the DNA damage during the 4 hours of experimental condition. Nonetheless, this study suggested that cell phone use may increase DNA damage by electromagnetic radiation and other contributing factors.

• Korean Journal of Medicinal Crop Science
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• v.11 no.2
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• pp.89-96
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• 2003

Korean mistletoes extracts were investigated for in vitro antioxidation activity, with 1,1-diphenyl-2-picrylhydrazine(DPPH), and an inhibitory effect on oxidative DNA damage by using comet assay. The Korean mistletoes were 4 different kinds classified by their host plants (Korean Viscum sp. in Quercus acutissima Carr., Korean Viscum sp. in Castanea crenata, Korean Viscum sp. in Betula platyphylla, and Korean Viscum sp. in Salix koreensis). The samples were extracted with ethanol, and fractonationed with n-butanol, ethyl acetate, chloroform, n-hexane, and second distilled water. Among them, ethyl acetate fraction from Korean Viscum sp. in Betula platyphylla showed the strongest activities to electron donating ability on 1,1-diphenyl-2-picrylhydrazyl(DPPH) and the protective effect on oxidative DNA damage.

• Toxicological Research
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• v.23 no.1
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• pp.25-31
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• 2007

To evaluate the protective effect of Houttuynia cordata on hydrogen peroxide-induced oxidative DNA damage in HepG2 cell line, we used an alkaline single-cell gel electrophoresis (SCGE; comet assay). The DNA damage was analyzed by tail moment (TM) and tail length (TL), which used markers of DNA strand breaks in SCGE. The $100{\mu}g/ml$ of methanolic extract of Houttuynia cordata root showed significant protective effects (p < 0.01) against hydrogen peroxide-induced DNA damage in HepG2 cells and increased cell viability against hydrogen peroxide. The results of this study indicate that Houttuynia cordata root methanol extract acts as a potential antioxidant, and exhibits potential anticancer properties, which may provide a clue to find applications in new pharmaceuticals for oxidative stability.