• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.594-598
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• 2002

The changes in DNA damage were investigated during storage after irradiation. Kiwi, orange and pear were irradiated at 0.1, 0.3, 0.5, 0.7 and 1.0 kGy and stored for 3 months at 4$^{\circ}C$. The comet assay was applied to the sample seeds alt the beginning of irradiation and at the end of storage. Seeds were isolated and crushed, and the suspended cells were embedded in an agarose layer. After lysis of the cells, they were electrophoresed for 2 min and then stained. DNA fragmentation in seeds caused by irradiation was quantified as tail length and tail moment (tail length $\times$ % DNA in tail) by comet image analyzing system. Immediately after irradiation, the differences in tail length between unirradiated and irradiated fruit seeds were significant (p<0.05) in kiwi, orange and pear seeds. With in-creasing the irradiation doses, statistically significant longer extension of the DNA from the nucleus toward anode was observed. The results represented as tail moment showed similar tendency to those of tail length, but tile latter parameter was more sensitive than the former. Similarly even 3 months after irradiation, all the irradiated fruit seeds significantly showed longer tail length than the unirradiated controls. These results indicate that the comet assay could be one of the simple methods of detecting irradiated fruit seeds. Moreover, the method could detect DNA damage even after 3 months after irradiation.

• Toxicological Research
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• v.20 no.2
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• pp.89-100
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• 2004

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of $\gamma$-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values. We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, Le., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.10a
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• pp.133-133
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• 2003

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.116-116
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• 2001

The alkaline Comet assay has been used with increasing popularity to investigate the level of DNA damage in terms of strand breaks and alkaline labile sites in biomonitoring studies within the last decade in western countries.(omitted)

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.95-95
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• 2003

The comet assay has been recently validated as a sensitive and specific test system for the quantification of DNA damage. with 11 substances that demonstrated positive results in at least one test among 4 standard short-term genotoxicity tests, and to evaluate its ability to predict rodent carcinogenicity.(omitted)

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.199-210
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• 2000

We present the results from narrow-band spectrophotometry of Comet Hale-Bopp (C/1995 O1) near perihelion obtained at Sobaeksan Optical Astronomy Observatory 61cm telescope equipped with PM 512 CCD camera(512$\times$512, 0.5"/pixel) and narrow-band filter set for the comet on 19 nights from February 21 to May 1, 1997. We discuss molecular emission band morphology and photometric behavior of Comet Hale-Bopp. The morphology of CN band shows more symmetric light distributions than $C_2$ or $C_3$ bands. On other hand, $C_2$ and $C_3$ band have more compact light distributions than CN band. Similar to wide-band image, molecular band morphology shows spiral structures at the core of the comet. The CN surface brightness variation with changing heliocentric distance shows difference from those of $C_2$ and $C_3$. The brightness, however, of these molecular bands near perihelion shows previously known 7day period light variations.

• Environmental Mutagens and Carcinogens
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• v.21 no.1
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• pp.34-43
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• 2001

Di-2-ethylhexyl phthalate (DEHP) is the most commonly used phthalate ester in polyvinyl chloride formulations including food packing and storage of human blood. DEHP is a well known as non-genotoxic carcinogen and endocrine disrupting chemical (EDC). DEHP have shown all negative results in ICH-guildeline recommended standard genotoxicity test battery. In this study, to assess the clastogenic and DNA damaging effect in human-derived tissue specific cells, DEHP was treated in human derived MCE-7 cells, HepG2 cells, LNCap cells, BeWo cells, MCE-10A cells, and female peripheral blood cells using micronucleus assay and in human breast carcinoma MCF-7 cells up to $1.28$\times$10^{-2}$ M using Comet assay. The in vitro micronucleus assay is a mutagenicity test system for the detection of chemicals which induce the formation of small membrane bound DNA fragment i.e. micronuclei in the cytoplasm of interphase cells, originated from clastogenic and/or aneugenic mechanism. The single cell gel electrophoresis assay (Comet assay) is used to detect DNA strand-breaks and alkaline labile site. In our results, DEHP increased significantly and/or dose-depentently and time-dependently micronucleus frequency at the 6 and 24 hr without metabolic activation system only in MCE-7 cells. DEHP treated with 2 hrs in MCF-7 cells using Comet assay induced DNA damage dose-depentantly.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.50.3-51
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• 2016

Recent analysis on the thermophysical property of asteroids revealed that their thermal inertia decrease with their sizes at least for main belt asteroids. However, little is known about that of comet-like bodies. In this work we utilized a simple thermophysical model (TPM) to calculate the thermal inertia of a bare nucleus of the comet P/2006 HR30 (Siding Spring) and an asteroid in comet-like orbit 107P/(4015) Wilson-Harrington from AKARI observation data. From five spectroscopic observations of the targets, we find out that the former has thermal inertia of around $2,000J\;m^{-2}K^{-1}s^{-1/2}$ (using pV = 0.055) and the latter has about $1,000-2000J\;m^{-2}K^{-1}s^{-1/2}$ (using pV = 0.055 and 0.043, respectively). These are high enough for both of them to deposit water ice at few centimeters depth, and hence it is difficult to say they are cometary based on the results of this study. These values, however, dependent significantly on the errors of observation and the uncertainties of the input parameters, as well as other conditions which are ignored in simple TPM approach, such as shape model and surface roughness. Further detailed analyses on these cometary bodies will shed light on our understanding of the detailed surfacial characteristics of them.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.49.3-50
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• 2017

There have been recent studies which revealed a tendency that thermal inertia decreases with the size of asteroidal bodies, and suggestions that thermal inertias of cometary bodies should be much smaller than those asteroidal counterparts, regardless of comets' nuclear sizes, which hints a way to differentiate cometary candidates from asteroids using thermal inertia information. We thus selected two comet-like objects from AKARI satellite of JAXA, namely, 107P/ (4015) Wilson-Harrington and P/2006 HR30 (Siding Spring), and applied simple thermophysical model to test the idea. Both targets did not show any comet-like activity during the observations. From the model, we found Wilson-Harrington to have size of 3.7-4.4 km, geometric albedo 0.040-0.055 and thermal inertia of 100-250 J m-2 K-1 s-0.5, which coincide with previous works, and HR30 to have size of 24-27 km, geomoetric albedo of 0.035-0.045 with thermal inertia of 250-1000 J m-2 K-1 s-0.5. HR30 is found to have the rotation pole near the ecliptic plane (the latitude between -20 and +60 deg). Based on the results, we conjecture that comet-like objects are not clearly distinguishable from asteroidal counterpart using thermal inertia.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.350-354
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• 2015

BACKGROUND: Botanical insecticides, especially Azadirachta Indica extract (AIE) and Sophorae radix extract (SRE) are widely used in Agriculture field. In our previous studies on genotoxicity test of AIE and SRE samples, a suspicious clastogenic properties was shown. Herein, we investigated the DNA damage effect of these botanical insecticide samples through the in vitro comet assay. METHODS AND RESULTS: Chinese hamster lung (CHL) fibroblast cell line was used, and methyl methanesulphonate was as positive control. Respective two samples of AIE and SRE were evaluated using Single Cell Gel Electrophoresis (Comet) assay and measured as the Olive tail moment (OTM). Results from this study indicated that all tested AIE and SRE samples did not show DNA damage in comet assay using CHL cells, compared with control. CONCLUSION: AIE and SRE samples used in this study were not cause genetic toxicity and are suitable for use as organic materials.