• Tuberculosis and Respiratory Diseases
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• 제71권4호
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• pp.259-265
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• 2011

Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, gefitinib and erlotinib, are effective therapies for non-small cell lung cancer (NSCLC) patients whose tumors harbor somatic mutations in EGFR. The mutations are, however, only found in about 30% of Asian NSCLC patients and all patients ultimately develop resistance to these agents. Ionizing radiation has been shown to induce autophosphorylation of EGFR and activate its downstream signaling pathways. In the present study, we have tested whether the effect of gefitinib treatment can be enhanced after ionizing radiation. Methods: We compared the PC-9 and A549 cell line with its radiation-resistant derivatives after gefitinib treatment with cell proliferation and apoptosis assay. We also analyzed the effect of gefitinib after ionizing radiation in PC-9, A549, and NCI-H460 cells. Cell proliferation was determined by MTT assay and induction of apoptosis was evaluated by flow cytometry. Caspase 3 activation and PARP cleavage were evaluated by western blot analysis. Results: PC-9 cells having mutated EGFR and their radiation-resistant cells showed no significant difference in cell viability. However, radiation-resistant A549 cells were more sensitive to gefitinib than were their parental cells. This was attributable to an increased induction of apoptosis. Gefitinib-induced apoptosis increased significantly after radiation in cells with wild type EGFR including A549 and NCI-H460, but not in PC-9 cells with mutated EGFR. Caspase 3 activation and PARP cleavage accompanied these findings. Conclusion: The data suggest that gefitinib-induced apoptosis could increase after radiation in cells with wild type EGFR, but not in cells with mutated EGFR.

• Radiation Oncology Journal
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• 제30권1호
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• pp.27-35
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• 2012

Purpose: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose. Results: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The $V_{20Gy}$ of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%. Conclusion: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

• 환경생물
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• 제27권2호
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• pp.140-145
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• 2009

All organisms are being exposed to harmful factors present in the environmental. The combined action of various factors is a distinguishing feature of modern life. An interaction between two chemicals is considered as synergistic when the effect produced is greater than the sum of the two single responses. The biological effects due to the combined action of ionizing radiation with the other factor are hard to estimate and predict in advance. In the current study, we investigated the synergistic effects between ionizing and $HgCl_2$ using fish hepatoma cells (PLHC-1 cells). The results showed a dramatic decrease of cell viability after simultaneous treatment of PLHC-1 cells with ionizing radiation and $HgCl_2$. Neiither of the two had any cytotoxic effect when treated alone. The cytotoxicity of ionizing radiation was enhanced in the presence of $HgCl_2$. The synergistic effects were observed after exposure of the PLHC-1 cells to ionizing radiation combined with $HgCl_2$. The synergistic interaction was due to an increase of irreversibly damaged cells after the combined exposure. Analysis of the extent of synergistic interaction enables to make quantitative estimation of irreversibly damaged cells after the combined exposure. The present study suggests that PLHC-1 cells can serve as rapid screening tools for detecting the toxicity of harmful factors.

• Food Science and Biotechnology
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• 제18권1호
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• pp.162-166
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• 2009

This study evaluated glucose effect on Listeria monocytogenes survival under gamma irradiation and NaCl stress. L. monocytogenes in phosphate buffered saline (PBS) plus glucose (0-4%) was treated with gamma irradiation (0-0.5 kGy), and the samples were then exposed to NaCl (0-9%) in tryptic soy agar plus 0.6% yeast extract. $D_{10}$ and $t_{3D}$ values were determined, and a model for prediction of $D_{10}$ values was developed. Cell counts of L. monocytogenes reduced as irradiation dose increased, and L. monocytogenes in PBS (no glucose) was more sensitive to irradiation and NaCl compared to those in PBS (2 or 4% glucose). $D_{10}$ values were 0.07-0.1, 0.12-0.16, and 0.13-0.15 kGy for 0, 2, and 4% glucose, respectively. The $t_{3D}$ values were 0.22-0.3 (0% glucose), 0.35-0.48 (2% glucose), and 0.40-0.44 (4% glucose). A model performance was acceptable. These results indicate that glucose in foods would increase the resistance of L. monocytogenes to gamma irradiation and NaCl stress.

• Journal of Radiation Protection and Research
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• 제38권4호
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• pp.237-241
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• 2013

국내 가압경수로형 원전 계획예방정비기간에 수행되는 주요 방사선작업에 대한 감마선 에너지 분포를 측정하였다. 고방사선구역 작업시 종사자가 착용하는 대표적인 납 차폐복에 대하여 감마선 에너지 분포에 따른 차폐효과를 평가하기 위해 전산모사 방법을 이용하였다. 전산모사는 MIRD형 인체모형에 추가적으로 납 차폐복을 모델링하고 측정된 감마선 에너지 정보를 이용하여 수행하였다. 주요 방사선작업의 평균 감마선 에너지는 일반적으로 방사선방호 과정에서 적용되는 기준 방사선에너지 보다 낮은 것으로 평가되었다. 방사선 방호 목적을 달성하기 위한 효율적인 납 차폐복 착용을 위해 방사선작업 지역의 방사선에너지 분포평가의 필요성을 확인하였다.

• 방사선산업학회지
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• 제6권2호
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• pp.111-117
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• 2012

This study was conducted to improve organoleptic quality of gamma-irradiated Tarakjuk at 10 kGy with cheeses (Camembert, Cheddar, Gouda, and Edam) and flavors (Nurungji, cream, and vanilla-cream). Overall acceptability of gamma-irradiated Tarakjuk added each camembert cheese and vanilla-cream flavor was the highest among the all samples. In the effect of sterilization method on the quality of Tarakjuk, the autoclaved samples added with Edam cheese, Gouda cheese, and vanilla-cream flavor, respectively, were showed higher score on the overall acceptability than the irradiated samples, meanwhile the irradiated samples were superior in the other samples. In case of added mixture of Edam cheese and vanilla-cream flavor, irradiated Tarakjuk with mixture was showed the most of high score on overall acceptability. In conclusion, addition of mixture of cheese and flavor to Tarakjuk may help to improve organoleptic quality of sterilized Tarakjuk by gammairradiation.

• 방사선산업학회지
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• 제7권1호
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• pp.81-85
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• 2013

This study was conducted to investigate the effect of fermented blackberry drinks (BD) on carbon tetrachloride ($CCl_4$)-induced liver injury in rats. Male Sprague-Dawley rats were randomly divided into four groups with 6 rats per group: control, $CCl_4$, $CCl_4$ plus BD $3ml\;kg^{-1}$, and $CCl_4$ plus BD $6ml\;kg^{-1}$. We found that the levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly increased and the activity of antioxidant enzyme glutathione peroxidase (GPx) in the liver was decreased in rats treated with $CCl_4$ alone when compared with the control group. However, the administration of BD attenuated the levels of serum AST and ALT in $CCl_4$-treated rats. Moreover, the administration of BD significantly increased the activity of GPx in $CCl_4$-treated rat livers. Taken together, these results suggest that BD could protect the liver from $CCl_4$-induced hepatic damage.

• 방사선산업학회지
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• 제5권2호
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• pp.169-173
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• 2011

This study investigated the effect of gamma irradiation on immune enhancing activity of Chaga mushroom extract (CME). CME was prepared by hot water extraction at $70^{\circ}C$ for 4 hours and lyophilized. Lyophilized CME powder was dissolved with deionized water at $10mg\;ml^{-1}$ and then irradiated at the doses of 10, 30 and 50 kGy by cobalt 60 gamma irradiator. The gamma-irradiated and non-irradiated CME were treated into the splenocyte separated from mouse. Cell proliferation and cytokine production of the immune cells were increased by gamma-irradiated CME and these increases were more prominent when CME was irradiated at higher doses. Therefore, it is considered that gamma irradiation can be an effective method for improvement of the immunomodulating activity Chaga mushroom extract.

• 한국환경복원기술학회지
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• 제21권6호
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• pp.1-13
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• 2018

Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

• Asian Pacific Journal of Cancer Prevention
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• 제17권6호
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• pp.2979-2982
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• 2016

Background: High dose ionizing radiation can induce ovarian cancer, but the effect of low dose radiation on the development of ovarian cancer has not been extensively studied. We evaluated the effect of low dose radiation and total background radiation, and the radiation delivered to the ovaries during the treatment of rectosigmoid cancer and breast cancer on ovarian cancer incidence. Materials and Methods: Background radiation measurements are from Assessment of Variations in Radiation Exposure in the United States, 2011. Ovarian cancer incidence data are from the Centers for Disease Control and Prevention. Standardized incidence ratios (SIR) of ovarian cancer following breast cancer and rectosigmoid cancer are from Surveillance, Epidemiology, and End Results (SEER) data. Obesity data by US state are from the Centers for Disease Control and Prevention. Mean ages of US state populations are from the United States Census Bureau. Results: We calculated standardized incidence ratios (SIR) from Surveillance, Epidemiology, and End Results (SEER) data, which reveal that in 194,042 cases of breast cancer treated with beam radiation, there were 796 cases of ovarian cancer by 120+ months of treatment (0.41%); in 283, 875 cases of breast cancer not treated with radiation, there were 1,531 cases of ovarian cancer by 120+ months (0.54%). The difference in ovarian cancer incidence in the two groups was significant (p < 0.001, two tailed Fisher exact test). The small dose of scattered ovarian radiation (about 3.09 cGy) from beam radiation to the breast appears to have reduced the risk of ovarian cancer by 24%. In 13,099 cases of rectal or rectosigmoid junction cancer treated with beam radiation in the SEER data, there were 20 cases of ovarian cancer by 120+ months of treatment (0.15%). In 33,305 cases of rectal or rectosigmoid junction cancer not treated with radiation, there were 91 cases of ovarian cancer by 120+ months (0.27%). The difference in ovarian cancer incidence in the two groups was significant (p = 0.017, two tailed Fisher exact test). In other words, the beam radiation to rectum and rectosigmoid that also reached the ovaries reduced the risk of ovarian cancer by 44%. In addition, there was a significant inverse relationship between ovarian cancer in white women and radon background radiation (r = - 0.465. p = 0.002) and total background radiation (r = -0.456, p = 0.002). Because increasing age and obesity are risk factors for ovarian cancer, multivariate linear regression was performed. The inverse relationship between ovarian cancer incidence and radon background was significant (${\beta}=-0.463$, p = 0.002) but unrelated to age (${\beta}=-0.080$, p = 0.570) or obesity (${\beta}=-0.180$, p = 0.208). Conclusions: The reduction of ovarian cancer risk following low dose radiation may be the result of radiation hormesis. Hormesis is a favorable biological response to low toxin exposure. A pollutant or toxin demonstrating hormesis has the opposite effect in small doses as in large doses. In the case of radiation, large doses are carcinogenic. However, lower overall cancer rates are found in U.S. states with high impact radiation. Moreover, there is reduced lung cancer incidence in high radiation background US states where nuclear weapons testing was done. Women at increased risk of ovarian cancer have two choices. They may be closely followed (surveillance) or undergo immediate prophylactic bilateral salpingo-oophorectomy. However, the efficacy of surveillance is questionable. Bilateral salpingo-oophorectomy is considered preferable, although it carries the risk of surgical complications. The data analysis above suggests that low-dose pelvic irradiation might be a good third choice to reduce ovarian cancer risk. Further studies would be worthwhile to establish the lowest optimum radiation dose.