• Journal of the Korean Data and Information Science Society
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• 제20권4호
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• pp.733-740
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• 2009

We obtain a skewed uniform distribution by a uniform distribution, and evaluate its coeffcient of skewness. And we obtain the approximate maximum likelihood estimator (AML) and moment estimator of skew parameter in the skewed uniform distribution. And we compare simulated mean squared errors (MSE) of those estimators, and also compare MSE of two proposed reliability estimators in two independent skewed uniform distributions each with different skew parameters.

• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.573-584
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• 2007

We define a skew-symmetric Laplace distribution by a symmetric Laplace distribution and evaluate its coefficient of skewness. And we derive an approximate maximum likelihood estimator(AME) and a moment estimator(MME) of a skewed parameter in a skew-symmetric Laplace distribution, and hence compare simulated mean squared errors of those estimators. We compare asymptotic mean squared errors of two defined estimators of reliability in two independent skew-symmetric distributions.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1205-1214
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• 2007

We define a skew-symmetric double Rayleigh distribution by a symmetric double Rayleigh distribution, and derive an approximate maximum likelihood estimator(AML) and a moment estimator(MME) of a skewed parameter in a skew-symmetric double Rayleigh distribution, and hence compare simulated mean squared errors of those two estimators. We also compare simulated mean squared errors of two proposed estimators of reliability in two independent skew-symmetric double Rayleigh distributions.

• 환경생물
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• 제22권4호
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• pp.507-512
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• 2004

This study was focused on the risk assessment of whether radiofrequency electromagnetic fields generated by mobile phone is cytogenetically toxic or not. We conducted the effects of 835-MHz electromagnetic field (EMF) on DNA strand breaks in mouse thymic lymphoma L5178Y $Tk^{+/1-}$ cells using alkaline comet assay. EMF frequency 835-MHz we chosen is one of the most popular communication frequency bands in Korean code-division multiple-access (CDMA) mobile phone system. The cells were exposed to 835-MHz EMF alone or 835-MHz EMF combined with cyclophosamide(CPA) or 4-nitroquinoline-1-oxide (4NQO) at specific absorption rate (SAR) of 4.0 W $kg^{-l}$ for 24 and 48hrs. DNA damage expressed as tail moment was increased more than two-fold after exposure to 835-MHz EMF for 24 and 48hr. In particular, CPA for 48hr and 4NQO for 24 hr enhanced notably the tail moment to 9-fold and 16-fold in the presence of 835-MHz EMF, respectively, compared to each single treatment. From these results, it appears that exposure to CDMA-mobile phone radiation at 835-MHz frequency may potentiate DNA strand breaks of mouse thymic lymphoma L5178Y $Tk^{+/1-}$;cells under the defined conditions of this study.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3409-3416
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• 2012

Aim: It is well known that polycyclic aromatic hydrocarbons (PAHs) such as benzo (a) pyrene have carcinogenic properties and may cause many types of cancers in human populations. Genetic susceptibility might be due to variation in genes encoding for carcinogen metabolizing enzymes, such as cytochrome P-450 (CYP450). Our study aimed to investigate the effect of genetic polymorphisms of CYP1A1 (m1 and m2) on genetic damage in 115 coal-tar workers exposed to PAHs at their work place. Methods: Genetic polymorphisms of CYP1A1 were determined by the PCR-RFLP method. Comet and buccal micronucleus assays were used to evaluate genetic damage among 115 coal tar workers and 105 control subjects. Results: Both CYP1A1 m1 and CYP1A1 m2 heterozygous and homozygous (wt/mt+mt/mt) variants individually as well as synergistically showed significant association (P<0.05) with genetic damage as measured by tail moment (TM) and buccal micronuclei (BMN) frequencies in control and exposed subjects. Conclusion: In our study we found significant association of CYP1A1 m1 and m2 heterozygous (wt/mt)+homozygous (mt/mt) variants with genetic damage suggesting that these polymorphisms may modulate the effects of PAH exposure in occupational settings.

• 환경생물
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• 제19권1호
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• pp.19-24
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• 2001

병해충을 막기 위해 농업용 살충제가 광범위하게 사용되고 있다. 농약사용에 따른 생물학적 위해가 우려되며 농약이 또 다른 환경유해요인과 인체에 상승적으로 작용할 경우 농업재해로 이어질 가능성이 있다. 다양한 인자에 의한 DNA손상을 감지하는데 유용한 단세포 겔 전기영동법을 이용하여 살충제와 방사선에 의한 사람 림프구 DNA손상을 평가하였다. 각기 다른 농도로 살충제를 10분간 전처리한 림프구와 정상 림프구에 0-2.0 Gy의 방사선으로 조사한 다음 DNA 손상도를 평가하였다. DNA가닥 절단에 대한 표식인 tail moment의 증가는 감마선에 대해서 뚜렷한 선량-반응 관계를 나타내었다. 단세포 겔 전기영동법을 통한 평가결과 권장 사용농도 이상의 살충제는 림프구에 대한 유전독성을 나타내었을 뿐 아니라 방사선과 함께 상승작용을 일으켜 림프구 DNA손상을 더욱 증가시키는 것이 확인되었다. 이와 같은 결과는 환경재해의 방재 및 예방 조치에 필요한 생물정보를 사전에 제공하는 의미를 가진다.

• Journal of Nutrition and Health
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• 제39권7호
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• pp.599-609
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• 2006

In this study, we investigated the in vivo effect by intake of the irradiated foods such as mackerel and sesame seed which are high in unsaturated fatty acid through TBARS (thiobarbituric acid reactive subtance) and the tissue pathological and genotoxicological test. Thirty two ICR mice are divided into four groups, one non-irradiated (control) group and three irradiated (5, 10, 20 kGy, respectively) groups. Sesame seed and pulverized mackerel in modified AIN93M diet were mixed together then divided into four identical parts. Three parts of them were irradiated by doses of 5, 10, and 20 kGy. These experimental diet were fed to each group for 4, 8 and] 6 weeks. The results of the study were as follows: No significant differences in weight gain were found in each group. Peroxide value of the irradiated diet was higher than that of the non-radiated one and also increased according to the storage period. TBA values in plasma, liver, kidney and Peyer's patch were not significantly different among 4 groups. DNA% in tail, tail length (TL) and tail moment (TM) values of the blood lymphocyte in 4, 8 and 16 week groups and the liver in 16 week group were much measured over the control DNA % in tail of kidney of 8 week group was significantly than the control and TL and TM of 8 week and TM of 16 week groups showed a tendency of higher values. By Peyer's DNA % in tail of 8 week group, DNA % in tail and TM of 16 week groups increased significantly over the control, Ultrastructural examination shows myeline figures and swollen mitochondria in parietal cells and intestinal epithelial cells of 8 and 16 weeks groups. After this study, we need further investigations on the safety of highly consumed foods which contain high contents of unsaturated fatty acid, largely imported and which are possible to be irradiated.

• Toxicological Research
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• 제23권1호
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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.

• 환경생물
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• 제31권3호
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• pp.189-191
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• 2013

Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) are widespread contaminants of food and feedstuffs. It is very likely, that humans and animals are always exposed to mixtures of mycotoxins rather than to individual compounds. Therefore, risk assessments should consider mixture toxicity data. In the present study the combination of AFB1, OTA and ZEA was tested for genotoxicity in rat bone marrow and blood leukocytes after 15, 30 and 60 days treatment. The level of DNA damage was determined by the comet assay. The tail intensity and Olive tail moment in leukocytes and bone marrow cells were significantly higher than in controls. At the same time, the level of DNA damage in bone marrow cells was higher than in leukocytes. The data suggests that prolonged exposure to mycotoxins combination through food consumption can induce DNA damage contributing to the harmful effects in vivo.

• Environmental Analysis Health and Toxicology
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• 제19권1호
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• pp.101-107
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• 2004

To ascertain the effects of hair dyeing application on the DNA damage in human lymphocytes, a mixture of permanent black colored hair dye with the same amount of oxidant containing 6% hydrogen peroxide was used. A hair dyeing with contacting the scalp (conventional dyeing) and a hair dyeing with 3 to 4mm away from the scalp (alternative dyeing) were applied to each If young healthy women. Blood was taken from the brachial vein at two sampling times, just before and 6 hours after the hair dyeing, and tail extent moment(TEM) and tail length (TL) were measured by using a comet assay. After dyeing, TL was significantly increased in both conventional dyeing group and alternative dyeing group compared with before dyeing as an average of 47% and 28%, respectively, and TL for conventional dyeing group was higher than alternative dyeing group as an average of 1.2 fold. After dyeing, TEM was significantly increased in both conventional dyeing group and alternative dyeing group compared with before dyeing as an average of 192% and 76%, respectively, and TEM for conventional dyeing group was significantly higher than alternative dyeing group as an average of 1.7 fold. Therefore, alternative dyeing application was induced to lower lymphocyte DNA damage than conventional dyeing application, and TEM was appeared to be a more sensitive tool for the measurement of lymphocyte DNA damage than TL in this study.