• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.276-276
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• 2013

Here we report an integrated microdevice consisting of an efficient passive mixer, a magnetic separation chamber, and a capillary electrophoretic microchannel in which DNA barcode assay, target pathogen separation, and barcode DNA capillary electrophoretic analysis were performed sequentially within 30 min for multiplex pathogen detection at the single-cell level. The intestine-shaped serpentine 3D micromixer provides a high mixing rate to generate magnetic particle-pathogenic bacteria-DNA barcode labelled AuNP complexes quantitatively. After magnetic separation and purification of those complexes, the barcode DNA strands were released and analyzed by the microfluidic capillary electrophoresis within 5 min. The size of the barcode DNA strand was controlled depending on the target bacteria (Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella typhimurium), and the different elution time of the barcode DNA peak in the electropherogram allows us to recognize the target pathogen with ease in the monoplex as well as in the multiplex analysis. In addition, the quantity of the DNA barcode strand (~104) per AuNP is enough to be observed in the laser-induced confocal fluorescence detector, thereby making single-cell analysis possible. This novel integrated microdevice enables us to perform rapid, sensitive, and multiplex pathogen detection with sample-in-answer-out capability to be applied for biosafety testing, environmental screening, and clinical trials.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05b
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• pp.1-19
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• 2002

It is well established that the initiating event in chemical carcinogenesis is the binding of reactive carcinogens to DNA. Thus, a number of analytic methods have been developed for determining levels of carcinogen-DNA adducts in humans as a marker of individual exposure and, potentially, of risk for cancer development. In addition, reactive carcinogens also bind to protein suggesting protein adducts can be used as a surrogate for DNA adducts in some situations. We have developed monoclonal and polyclonal antibodies to carcinogen-DNA and protein adductis and highly sensitive ELISA and immunohistochemical assays for determining levels of adducts in human tissues. These studies have demonstrated higher levels of adducts in those with higher exposure as a result of workplace, dietary, chemotherapy, environmental of lifestyle (smoking) exposures. Elevated levels of adducts have been found in lung and liver cancer cases compared to controls. We have also used DNA adducts to determine efficacy of an antiosidant vitamin intervention. DNA adduct studies have demonstrated very different levels of damage in those with similar exposure levels. These interindividual differences are likely the result genetic differences in capacity to activate carcinogens, detoxify reactive intermediates and repair DNA adducts once formed. We are currently investigating the relationship between polymorphisms in a number of these genes to determine their relationship to adduct levels as well as their ability to confer increased risk for cancer development. The ability to identify high risk individuals will allow the targeting of screening and preventive strategies to those most likely to benfit.

• Korean Journal of Animal Reproduction
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• v.17 no.1
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• pp.43-48
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• 1993

These experiments were carried out to construct mouse testis cDNA library and to to seen H-Y Ag gene. Mouse testis was obtained from BALB/c inbreed mouse that was after-born 1 week. Isolation of mouse testis total RNA was carried out by guanidum/cesium choloride, poly(A+) mRNAs were purified by oligo d(T)-cellulose chromatography method. To investigate protein synthesis activity, in-vitro translation carried out by total RNA and poly(A+) mRNA. The products of in-vitro translation were identified in 12.5% PAGE. Single strand DNA and double strand DNA were synthesized from poly(A+) mRNA and purified using phenol/chloroform/isoamylalcohol. Synthesized cDNA was combined with cohesive Eco RI polylinker, its recombination efficiencies were identified by X-gal and IPTG. In the cDNA library, 1$\times$107 phagemids were screened with 32P labelled probe. Hybridization were carried on $65^{\circ}C$ for 16~20hours. And 1$\times$106 phagemids were screened with rabbit-anti-H-Y. In former, select 5 positive clones, and later, 1 positive clone. Its southern blot analysis showed various size of insert cDNA from 0.7kb to 3kb.

• Journal of Aquaculture
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• v.16 no.3
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• pp.196-201
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• 2003

Sessile organisms such as the oyster Crassostrea gigas have been given much attention as a potential biomonitoring indicator to assess the impact of toxicants on aquatic organism. In this study, we exposed cells isolated from gill of oyster (Crassostrea gigas) to hydrogen peroxide in vitro. In addition oysters were in vivo exposed to pyrene and benzo(a)pyrene at various concentrations for 2 weeks. Comet assay was used to detect DNA single strand breaks and to investigate the application of this technique as a tool for aquatic biomonitoring. Hydrogen peroxide increased DNA single strand break with increasing concentration after 30 minutes exposure in vitro. Pyrene and benzo(a)pyrene caused DNA damage only at very high concentration (100 $\mu\textrm{g}$/L or 1000 $\mu\textrm{g}$/L) at two week exposure in vivo. DNA damage was relatively higher at hemocyte than at gill. It suggested that metabolized PAHs are transferred to hemolymph from digestive gland which have a relatively high enzyme activity, and attacked the DNA of hemocyte, while gill accumulated PAHs without degrading them to their metabolites due to low enzyme activity at gill. Both in vitro and in vivo exposure experiments showed that the comet assay is an effective tool on screening whether the organism are exposed to genotoxic contaminants.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.1
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• pp.26-31
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• 2011

The genotypes of Human Papilloma Virus (HPV) are important in the carcinogenesis of uterine cervical cancer. Diagnosis of uterine cervical cancer screening has been executed using Papanicolau method (Pap) and HPV DNA Chip method. We researched the interrelation of HPV DNA genotypes in single and multiple infections and analyzed the results of Pap and HPV DNA Chip tests at Gunsan Medical Center (GMC). The correlation analysis was surveyed on collected results from 599 patients who have been tested with both Pap and HPV DNA chip tests from November 2004 to May 2010 at GMC. The inconsistency between Pap and HPV DNA Chip tests was 41.1%. The HPV DNA Chip genotype related with high risk cases were type 16 (13.5%), type 52 (10.5%), type 58 (10.1%), and type 18 (3.4%). Those related with low risk cases were type 70 (8.9%), type 6 (1.7%), type 40 (1.2%), type 11 (1.3%), and other types (14.3%). Among the 195 cases of HPV positive status, 161 cases were associated with single infection; 108 (67.1%) cases were related with high risk genotype; 19 (11.8%) cases were low risk genotype; 31 (21.1%) cases were related with other types. 29 cases were associated with double infections; 23 (79.3%) cases were high risks; 5 (17.2%) cases were mixed high and low risks; 1 (3.5%) case was low risk.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.118-123
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• 2015

Metagenomics is a powerful tool to isolate novel biocatalyst and biomolecules directly from the environmental DNA libraries. Since the metagenomics approach bypasses cultivation of microorganisms, un-cultured microorganisms that are majority of exists can be the richest reservoir for natural products discovery. To discover novel herbicidal substances from soil metagenome, we established three easy, simple and effective high throughput screening methods such as cucumber cotyledon leaf disc assay, microalgae assay and seed germination assay. Employing the methods, we isolated two active single clones (9-G1 and 9-G12) expressing herbicidal activity which whitened leaf discs, inhibited growth of microalgae and inhibited root growth of germinated Arabidopsis seeds. Spraying butanol fraction of the isolated active clones' culture broth led to growth retardation or desiccation of Digitalia sanguinalis (L) Scop. in vivo. These results represent that the screening methods established in this study are useful to screen herbicidal substances from metagenome libraries. Further identifying molecular structure of the herbicidal active substances and analyzing gene clusters encoding synthesis systems for the active substances are in progress.

• Toxicological Research
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• v.33 no.2
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• pp.107-118
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• 2017

Although alternative test methods based on the 3Rs (Replacement, Reduction, Refinement) are being developed to replace animal testing in reproductive and developmental toxicology, they are still in an early stage. Consequently, we aimed to develop alternative test methods in male animals using mouse spermatogonial stem cells (mSSCs). Here, we modified the OECD TG 489 and optimized the in vitro comet assay in our previous study. This study aimed to verify the validity of in vitro tests involving mSSCs by comparing their results with those of in vivo tests using C57BL/6 mice by gavage. We selected hydroxyurea (HU), which is known to chemically induce male reproductive toxicity. The 50% inhibitory concentration ($IC_{50}$) value of HU was 0.9 mM, as determined by the MTT assay. In the in vitro comet assay, % tail DNA and Olive tail moment (OTM) after HU administration increased significantly, compared to the control. Annexin V, PI staining and TUNEL assays showed that HU caused apoptosis in mSSCs. In order to compare in vitro tests with in vivo tests, the same substances were administered to male C57BL/6 mice. Reproductive toxicity was observed at 25, 50, 100, and 200 mg/kg/day as measured by clinical measures of reduction in sperm motility and testicular weight. The comet assay, DCFH-DA assay, H&E staining, and TUNEL assay were also performed. The results of the test with C57BL/6 mice were similar to those with mSSCs for HU treatment. Finally, linear regression analysis showed a strong positive correlation between results of in vitro tests and those of in vivo. In conclusion, the present study is the first to demonstrate the effect of HU-induced DNA damage, ROS formation, and apoptosis in mSSCs. Further, the results of the current study suggest that mSSCs could be a useful model to predict male reproductive toxicity.

• The Korean Journal of Cytopathology
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• v.19 no.2
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• pp.107-110
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• 2008

We evaluated the usefulness of cervicovaginal cytology as a primary screening test by analyzing the cytologic and histological diagnoses of 2,254 women. Cervicovaginal cytology had 93.0% sensitivity, 86.1% specificity, 88.2% positive predictive value, and 91.7% of negative predictive value. Cervicovaginal cytology as a primary screening test showed much higher specificity but slightly lower sensitivity than HPV DNA testing. However, the sensitivity of cervicovaginal cytology will be improved continuously due to the development of liquid-based cytology. We regard cervicovaginal cytology as a good primary screening test for cervical intraepithelial neoplasia or carcinoma.

• Journal of Digestive Cancer Research
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• v.4 no.1
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• pp.17-20
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• 2016

Colorectal cancer is the 2^nd most common cancer in men, and the 3^rd most common cancer in women in Korea. This incidence has been increasing steadily since the data analysis began in 1999. Guidelines from many countries including Korea recommend annual or biennial fecal occult blood test as a national colorectal cancer screening program, however, colonoscopy, stool DNA test, double contrast barium enema, and sigmoidoscopy are recommended in some countries. I will summarize the Korean National Screening Guideline for colorectal cancer revised by multi-society expert committee in Korea last year. They recommend annual or biennial fecal immunochemical test between 45 and 80 year-old asymptomatic average risk people. Selective use of colonoscopy is recommended, taking into consideration of individual preference and the risk of colorectal cancer. There is no evidence for the risks or benefits of double contrast barium enema or computed tomographic colonography for colorectal cancer screening.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8455-8460
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• 2016

Background: Poor participation rates are often observed in colorectal cancer (CRC) screening programs utilising faecal occult blood tests. This may be from dislike of faecal sampling, or having benign bleeding conditions that can interfere with test results. These barriers may be circumvented by offering a blood-based DNA test for screening. The aim was to determine if program participation could be increased by offering a blood test following faecal immunochemical test (FIT) non-participation. Materials and Methods: People were invited into a CRC screening study through their General Practice and randomised into control or intervention (n=600/group). Both groups were mailed a FIT (matching conventional screening programs). Participation was defined as FIT completion within 12wk. Intervention group non-participants were offered a screening blood test (methylated BCAT1/IKZF1). Overall participation was compared between the groups. Results: After 12wk, FIT participation was 82% and 81% in the control and intervention groups. In the intervention 96 FIT nonparticipants were offered the blood test - 22 completed this test and 19 completed the FIT instead. Total screening in the intervention group was greater than the control (88% vs 82%, p<0.01). Of 12 invitees who indicated that FIT was inappropriate for them (mainly due to bleeding conditions), 10 completed the blood test (83%). Conclusions: Offering a blood test to FIT non-participants increased overall screening participation compared to a conventional FIT program. Blood test participation was particularly high in invitees who considered FIT to be inappropriate for them. A blood test may be a useful adjunct test within a FIT program.