• YAKHAK HOEJI
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• v.36 no.5
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• pp.449-454
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• 1992

The effect of radioprotective ginseng protein fraction on DNA repair capacity was determined by measuring the amount of $^{3}H-thymidine$ incorporated into DNA in the process of repair synthesis for UV damaged DNA. CHO-Kl cells were prepared whose semiconservative replication was inhibited by trimethylpsoralen plus near-UV(PUVA) treatment. When the cells were exposed to UV light alone, the DNA repair capacity was increased at first and then decreased as UV dose increased. However, when the ginseng fraction was treated to the cells, the DNA repair capacity was kept increasing regardless of UV dose increment. When the concentration of protein contained in the added fraction was increased gradually, the repair capacity was also increased almost linearly showing dose-response relationship of the effect. These results suggest that the enhancement of DNA repair capacity of the cell can be one of the mechanisms of radioprotection by the ginseng fraction.

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.259-264
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• 1993

Three cell lines, CHO, L929 and B16 which are non-tumorigenic and cancer cells, respectively, were first tested for their survival in the presence of radioprotective ginseng protein fraction(GPF0. The influence of three radioprotectors-CPF, cysteamine, and 1-Methyl-2-bis[(2-methylthio)vinyl] quinolinium iodide (MVQI) on DNA repair capacity of UV damaged cells survival test, the GPF showed higher cytotoxicity in L929 and B16 than in CHO cells. However, the degree of cell killing was also investigated by measuring $^3H$-thymidine incorporation of PUVA treated cells. In cell survival test, the GPF showed higher cytotoxicity in L929 and B16 than in CHO cells. However, the degree of cell killing was not high enough to consider it as an antitumorigenic agent. Variable results were obtained in the effects on DNA repair capacity depending on the protectors and cell lines used. In pretreatment, the presence of GPF and MVOI brought about a sinificant increase in the capacity in both CHO and B16 cells. However, in L929, the enhancing effect was not shown. In all three cell lines, cysteamine showed lower repair capacity than control, suggesting the primary damage reduction in stronger enhancing effects in L929 and B16 cells, while it was weaker in CHO cells. Here also cystemine hsowed a very little or no increase in the capacity in all three cell lines. These results demonstrate that GPF has mild cytotoxicity in tumorignic cells and that GPF and MVQI enhance DNA repair capacity of UV damaged cells, whether they are tumorigenic or not. On the other hand, cysteamine shows only damage reduction effect. Celles of different genetic origin seem to give different responses to the modifier and different modifiers may possibly work by different mechanisms.

• Journal of Animal Science and Technology
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• v.63 no.5
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• pp.984-997
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• 2021

This study sought to evaluate DNA damage and repair in porcine postovulatory aged oocytes. The DNA damage response, which was assessed by H2A.X expression, increased in porcine aged oocytes over time. However, the aged oocytes exhibited a significant decrease in the expression of RAD51, which reflects the DNA damage repair capacity. Further experiments suggested that the DNA repair ability was suppressed by the downregulation of genes involved in the homologous recombination (HR) and nonhomologous end-joining (NHEJ) pathways. The expression levels of the cell cycle checkpoint genes, CHEK1 and CHEK2, were upregulated in porcine aged oocytes in response to induced DNA damage. Immunofluorescence results revealed that the expression level of H3K79me2 was significantly lower in porcine aged oocytes than in control oocytes. In addition, embryo quality was significantly reduced in aged oocytes, as assessed by measuring the cell proliferation capacity. Our results provide evidence that DNA damage is increased and the DNA repair ability is suppressed in porcine aged oocytes. These findings increase our understanding of the events that occur during postovulatory oocyte aging.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7091-7094
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• 2013

DNA repair capacity is crucial in maintaining cellular functions and homeostasis. However, it can be altered based on DNA sequence variations in DNA repair genes and this may lead to the development of many diseases including malignancies. Identification of genetic polymorphisms responsible for reduced DNA repair capacity is necessary for better prevention. Homologous recombination (HR), a major double strand break repair pathway, plays a critical role in maintaining the genome stability. The present study was performed to determine the frequency of the HR gene XRCC3 Exon 7 (C18067T, rs861539) polymorphisms in Saudi Arabian population in comparison with epidemiological studies by "MEDLINE" search to equate with global populations. The variant allelic (T) frequency of XRCC3 (C>T) was found to be 39%. Our results suggest that frequency of XRCC3 (C>T) DNA repair gene exhibits distinctive patterns compared with the Saudi Arabian population and this might be attributed to ethnic variation. The present findings may help in high-risk screening of humans exposed to environmental carcinogens and cancer predisposition in different ethnic groups.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6469-6474
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• 2012

Background: DNA repair is one of the crucial defense mechanism against mutagenic exposure. Inherited SNPs of DNA repair genes may contribute to variation in DNA repair capacity and susceptibility to cancer. Due to the presence of these variants, inter-individual and ethnic differences in DNA repair capacity have been established in various populations. India harbors enormous genetic and cultural diversity. Materials and Methods: In the present study we aimed to determine the genotypes and allele frequencies of XRCC1 Arg399Gln (rs25487), XRCC3 Thr241Met (rs861539), XPD Lys751Gln (rs13181), and OGG1 Ser326Cys (rs1052133) gene polymorphisms in 186 healthy individuals residing in the Hyderabad region of India and to compare them with HapMap and other populations. Results and Conclusions: The genotype and allele frequency distribution at the four DNA repair gene loci among Hyderabad population of India revealed a characteristic pattern. Comparison of these gene polymorphisms with other populations revealed a distinctiveness of Hyderabad population from the Deccan region of India. To the best of our knowledge, this is the first report of such DNA repair gene polymorphisms in the Deccan Indian population.

• Korean Journal of Microbiology
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• v.26 no.2
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• pp.113-121
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• 1988

Ozone, an atmospheric pollutant, can damage similar UV and X-rays DNA and its components. It is possible then that the KNA damage produced by this gas are similar, to some extent, to those of radiations and that they could be repaired by the same DNA repair mechanisms. It has been observed in Escherichia coli that radiosensitive strains such as lex A, rec A and pol A, all deficient to some extent for DNA repair, are more sensitive to ozone than a wild type strain. We have thendetermined the ozone resistance and host-cell reactivation of ozone-damaged T3 phages for the E. coli double mutants pol A, lex A, uvr B, lex A, uvr A, rec A and rec A lox A. According to the results, the DNA polymerase 1 plays a key role in ozone resistance and Type 11 mechanism and/or shory patch excision repair are the most important for it. The interactions between the different DNA repair mechanisms are secondary. There is a strong correlation between ozone resistance and the capacity to reactivate T3 phages damaged by ozone.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.4879-4881
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• 2012

Epidermal growth factor receptor (EGFR) overexpression is associated with resistance to chemotherapy and radiotherapy. The EGFR modulates DNA repair after radiation-induced damage through an association with the catalytic subunit of DNA protein kinase. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage induced by ionizing radiation, and non-homologous end joining is the predominant pathway for repair of radiation-induced DSBs. Some cell signaling pathways that respond to normal growth factors are abnormally activated in human cancer. These pathways also invoke the cell survival mechanisms that lead to resistance to radiation. The molecular connection between the EGFR and its control over DNA repair capacity appears to be mediated by one or more signaling pathways downstream of this receptor. The purpose of this mini-review was not only to highlight the relation of the EGFR signal as a regulatory mechanism to DNA repair and radiation resistance, but also to provide clues to improving existing radiation resistance through novel therapies based on the above-mentioned mechanism.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.5
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• pp.509-517
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• 2008

DNA damage accumulates in cells as a result of exposure to exogenous agents such as benzopyrene, cigarette smoke, ultraviolet light, X-ray, and endogenous chemicals including reactive oxygen species produced from normal metabolic byproducts. DNA damage can also occur during aberrant DNA processing reactions such as DNA replication, recombination, and repair. The major of DNA damage affects the primary structure of the double helix; that is, the bases are chemically modified. These modification can disrupt the molecules'regular helical structure by introducing non-native chemical bonds or bulky adducts that do not fit in the standard double helix. DNA repair genes and proteins scan the global genome to detect and remove DNA damage and damage to single nucleotides. Direct reversal of DNA damage, base excision repair, double strand break. DNA repair are known relevant DNA repair mechanisms. Four different mechanisms are distinguished within excision repair: direct reversal, base excision repair, nucleotide excision repair, and mismatch repair. Genetic variation in DNA repair genes can modulate DNA repair capacity and alter cancer risk. The instability of a cell to properly regulate its proliferation in the presence of DNA damage increase risk of gene mutation and carcinogenesis. This article aimed to review mechanism of excision repair and to understand the relationship between genetic variation of excision repair genes and head and neck cancer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2500-2504
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• 2011

Living organisms are composed of cells that can replicate themselves through growth, division packed with tons capacity. On DNA mutations, ie mutations in the offspring's survival and reproduction can be held against you, and packed with tons ambivalence that could benefit. In this study, the DNA double helix is used as a template for replication, we first separated into single strands of the double helix must be opened Combining the double helix portion of the location of errors in the bond provides a way to find and repair.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.55-64
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• 2006

The fetal central nervous system (CNS) is sensitive to diverse environmental factors, such as alcohol, heavy metals, irradiation, mycotoxins, neurotransmitters, and DNA damage, because a large number of processes occur during an extended period of development. Fetal neural damage is an important issue affecting the completion of normal CNS development. As many concepts about the brain development have been recently revealed, it is necessary to compare the mechanism of developmental abnormalities induced by extrinsic factors with the normal brain development. To clarify the mechanism of fetal CNS damage, we used one experimental model in which 5-azacytidine (5AZC), a DNA damaging and demethylating agent, was injected to the dams of rodents to damage the fetal brain. 5AzC induced cell death (apoptosis)and cell cycle arrest in the fetal brain, and it lead to microencephaly in the neonatal brain. We investigated the mechanism of apoptosis and cell cycle arrest in the neural progenitor cells in detail, and demonstrated that various cell cycle regulators were changed in response to DNA damage. p53, the guardian of genome, played a main role in these processes. Further, using DNA microarray analysis, tile signal cascades of cell cycle regulation were clearly shown. Our results indicate that neural progenitor cells have the potential to repair the DNA damages via cell cyclearrest and to exclude highly affected cells through the apoptotic process. If the stimulus and subsequent DNA damage are high, brain development proceeds abnormally and results in malformation in the neonatal brain. Although the mechanisms of fetal brain injury and features of brain malformation afterbirth have been well studied, the process between those stages is largely unknown. We hypothesized that the fetal CNS has the ability to repair itself post-injuring, and investigated the repair process after 5AZC-induced damage. Wefound that the damages were repaired by 60 h after the treatment and developmental processes continued. During the repair process, amoeboid microglial cells infiltrated in the brain tissue, some of which ingested apoptotic cells. The expressions of genes categorized to glial cells, inflammation, extracellular matrix, glycolysis, and neurogenesis were upregulated in the DNA microarray analysis. We show here that the developing brain has a capacity to repair the damage induced by the extrinsic stresses, including changing the expression of numerous genes and the induction of microglia to aid the repair process.