• Radiation Oncology Journal
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• v.22 no.3
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• pp.217-224
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• 2004

Purpose: It is well known that the radiosensitivity of tumor cells can be significantly reduced under hypoxic conditions. Hypoxia-inducible factor-1 $\alpha$ (HIF-1 $\alpha$) plays a pivotal role in the essential adaptive responses to hypoxia. Therefore this study investigated the relationship between HIF-1 $\alpha$ expression and radiosensitivity. M Mouse hepatoma cell line hepafcic7 and HIF-1 $\beta$-deficient mutant cell line hepa1C4 were used to analyze the role of HIF-1 a. on radiosensitivity. These cells were exposed for 6 h to desferrioxamine (DFX) before radiation. HIF-1$\alpha$. expression was examined by Western blot. Apoptosis was assessed by DNA fragmentation, propidium iodide staining, and apoptotic cell death detection ELISA kit. Radiation sensitivity was determined using MTT assay. The radiobioiogical parameters, surviving fractions at 2 Gy and 8 Gy, and mean inactivation dose (MID) from the linear-quadratic model were used to assess radiation sensitivity in the statistical analyses. Results: The expression of HIF-1 $\alpha$. was Increased, whereas apoptosis was decreased, by radiation In the presence of DFX In hepal cl c7, but not In hepal C4. The radlosensitivity of hepal C4 cells was not significantly affected by DFX treatment. The radiosensitivlty of hepal cl c7 cells was significantly decreased in the presence of DFX Conclusion: The expression of HIF-1 w by hypoxia-mimic agent DFX reduced apoptosls and radiosensitlvity in mouse hepatoma cell line hepafclc7. These results suggested that HIF-1 u could be Induced by irradiation in hypoxic ceils of tumor masses, and that this mlght Increase radioresistance in hypoxic cells.

• Radiation Oncology Journal
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• v.24 no.2
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• pp.128-137
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• 2006

Purpose: We investigated whether a relationship exists between tumor control dose 50 ($TCD_{50}$) or tumor growth delay (TGD) and radiation induced apoptosis (RIA) in syngeneic murine tumors. Also we investigated the biological markers that can predict radiosensitivity in murine tumor system through analysis of relationship between $TCD_{50}$, TGD, RIA and constitutive expression levels of the genetic products regulating RIA. Materials and Methods: Syngeneic murine tumors such as ovarian adenocarcinoma, mammary carcinoma, squamous cell carcinoma, fibrosarcoma, hepatocarcinoma were used In this study. C3H/HeJ mice were bred and maintained in our specific pathogen free mouse colony and were $8{\sim}12$ weeks old when used for the experiments. The tumors, growing in the right hind legs of mice, were analyzed for $TCD_{50}$, TGD, and RIA at 8 mm in diameter. The tumors were also analyzed for the constitutive expression levels of $p53,\;p21^{WAF1/CIP1},\;BAX,\;Bcl-2,\;Bcl-X_L,\;Bcl-X_S$, and p34. Correlation analysis was peformed whether the level of RIA were correlated with $TCD_{50}$ or TGD, and the constitutive expression levels of genetic products regulating RIA were correlated with $TCD_{50}$, TGD, RIA. Results: The level of RIA showed a significant positive correlation (R=0.922, p=0.026) with TGD, and showed a trend to correlation (R=-0.848), marginally significant correlation with $TCD_{50}$ (p=0.070). It indicates that tumors that respond to radiation with high percentage of apoptosis were more radiosensitive. The constitutive expression levels of $p21^{WAF1/CIP1}$ and 34 showed a significant correlation either with $TCD_{50}$ (R=0.893, p=0.041 and R=0.904, p=0.035) or with TGD (R=-0.922, p=0.026 and R=-0.890 p=0.043). The tumors with high constitutive expression levels of $p21^{WAF1/CIP1}$ or p34 were less radiosensitive than those with low expression. Conclusion: Radiosensitivity may be predicted with the level of RIA in murine tumors. The constitutive expression levels of $p21^{WAF1/CIP1}$ or p34 can be used as biological markers which predict the radiosensitivity.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.216-219
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• 1997

Thirty day old rice seedlings, Ilpoom and Taeback variety, grown under deficient condition of several elements in nutrition solution of sand culture were exposed to 20Gy, 40Gy, 80Gy of gamma ray $(^{60}Co)$ to study the effect of their radiosensitivity. The results obtained are summarized as follows : Plant height and fresh weight of nutrient deficient rice plants were far less than those of control. The effect was different with nutrient element and rice variety, as show increasing effect of radiosensitivity in the Ilpoom variety was high in the Fe deficient whereas that of Taeback was high in the P deficient. Growth inhibition of rice plant irradiated with 20Gy was highly occurred in the Fe and Zn deficient plot in Ilpoom variety and P and Zn deficient plot in Taeback variety. In 80Gy irradiated group, radiosensitivity of rice plant was high in the P and Ca deficient plot of both Ilpoom and Taeback variety.

• Applied Biological Chemistry
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• v.29 no.4
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• pp.416-421
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• 1986

방사선을 이용한 화분의 저장방법을 개선하기 위하여 저장중인 메밀 화분으로 부터 곰팡이를 분리, 동정하고 이들의 방사선 감수성을 조사하였다. 분리, 동정된 곰팡이는 Penicillium jenseni, Aspergillus oryzae, Asp. niger, Alternaria SP. 으로 이들 포자의 $D_{10}$ 값은 각각 0.43, 0.54, 0.58, 0.97kGy 이었고, 유도선량은 각각 0.23, 0.18, 0.23, 0kGy이었다. Pen. jenseni 포자의 방사선 감수성은 용존산소하에서 증가하였으며 이에 열처리를 병용하였을 때는 유도선량이 현저하게 감소하였다. 화분 중의 총세균과 곰팡이의 $D_{10}$ 값은 각각 1.25kGy와 $1.50{\sim}4.30kGy$이었다.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.298-306
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• 2004

Purpose: The purpose of this study was to identify Radiosensitivity of proteins in tissues with different radiosensitivity. Materials and Methods: C3H/HeJ mice were exposed to 10 Gy. The mice were sacrifiud 8 hrs after radiation. Their spleen and liver tissues were collected and analyzed histologicaly for apoptosis. The expressions of radiosusceptibillty protein were analyzed by 2-dimensional electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Resilts: The Peak of apoptosis levels were $35.3{\pm}1.7{\%}$ in spleen and $0.6{\pm}0.2{\%}$ in liver at 8 hrs after radiation. Liver, radioresistant tissues, showed that the levels of ROS metabolism related to proteins such as cytochromm c, glutathione S transferase, NADH dehydrogenase, riken cDNA and peroxiredoxin Vl increased after radiation. The expression of cytochrome c increased significantly in spleen and liver tissues after radiation. In spleen, radiosensitivity tissue, the identified proteins showed a significantly quantitative alteration following radiation. It was categorized as signal transduction, apoptosis, cytokine, Ca signal related protein, stress-related protein, cytoskeletal regulation, ROS metabolism, and others. Conclusion: Differences of radiation-induced apoptosis by tissues specifted were coupled with the induction of related radiosensitivity and radioresistant proteins. The result suggests that apoptosis relate protein and redox proteins play important roles in this radiosusceptibility.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.7-15
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• 1991

Pentoxifylline (PENTO) has been known to improve RBC fluidity, and thus improve the flux of RBC through narrow capillaries. Additionally, PENTO also decreases the $O_2$ affinity of hemoglobin by increasing 2,3-DPG levels, thereby increasing the $O_2$ release from RBC. Nicotinamide (NA) has been reported to decrease the number of acutely hypoxic cells in tumors by temporarily increasing tumor blood flow. Therefore, the purpose of this study was to examine whether the combination of PENTO and NA (PENTO+NA) would reduce the radioresistance of the Fsall murine fibrosarcoma by oxygenating the hypoxic cells. We obsewed a significantly enhanced radiation-induced growth delay of the FSaII tumors by PENTO+NA. Thus the enhancement ratio was between 2.5 and 2.8 in growth delay assay. The $TCD_{50}$ of control tumors was about 57 Gy, but that of PENTO+NA treated tumors was about 32Gy. Thus $TCD_{50}$ was modified by a factor of 1.8. We also observed that PENTO+NA exerted no effect on the radiation-induced skin damage after the legs without bearing tumors were exposed to X-irradiation. In order to clarify radiosensitizing effects of PENTO+ NA, changes in tumor blood flow and intratumor pOf were measured using laser Doppler flowmetry and $O_2$ microelectrode methods. The tumor blood flow significantly increased at 10 min. after injection of PENTO+ NA. Furthermore, we also found that PENTO+ NA significantly increased intratumor $pO_2$ from 8 to 19 mmHg. We concluded that PENTO+MA was far more effective than NA alone or PENTO alone. The increase in the response of tumors in vivo to X-irradiation appeared to be due mainly to an increase in the tumor oxygenation. Further studies using various concentrations of PENTO alone and in combination with NA to obtain better sequencing and maximal radiosensitization are warranted.

• Radiation Oncology Journal
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• v.21 no.3
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• pp.216-221
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• 2003

Purpose: To investigate the modulation of radiosensitivity by celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, on cancer cells over- and under-expressing COX-2. Materials and Methods: A clonogenic radiation survival analysis was performed on A549 human lung and MCF-7 human breast cancer cell lines incubated in both 1 and $10\%$ fetal bovine serum (FBS) containing media. The apoptosis in both cell lines was measured after treatment with radiation and/or celecoxib. Results: Celecoxib enhanced the radiation sensitivity of the A549 cells in the medium containing the $10\%$ FBS, with radiation enhancement ratios of 1.58 and 1.81 respectively, at surviving fractions of 0.1, with $30\muM\;and\;50\muM$ celecoxib. This enhanced radiosensitivity disappeared in the medium containing the $1\%$ FBS. Celecoxib did not change the radiation sensitivity of the MCF-7 cells in either media. The induction of apoptosis by celecoxib and radiation was not synergistic in either cell line. Conclwsion: Celecoxib, a selective COX-2 inhibitor, preferentially enhanced the effect of radiation on COX-2 over-expressing cancer cells compared to the cells with a low expression, and this effect disappeared on incubation of the cells during drug treatment in the medium with suboptimal serum concentration. Apoptosis did not appear to be the underlying mechanism of this radiation enhancement effect due to celecoxib on the A549 cells. These findings suggest radiosensitization by a selective COX-2 inhibitor is COX-2 dependent.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.483-487
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• 2016

The purpose of this study is to investigate whether gold nanoparticles had radiosensitization when combined with gamma and x ray beam. Cytotoxicity was mearsured with comparing survival fraction after incubated time 6,12,18 and 24 hours. Clonogenic assay was employed to assess survival fraction of cells with and without gold nanoparticles treatment following gamma ray irradiation. The most of gold nanoparticles were distributed in the cytoplasm. And the toxicity of gold nanoparticles used this study were found to be non-cytotoxic. And we also observed enhancement by about 40% in RBE value for gamma ray irradiation of cells treated with gold nanoparticles. Dose reduction of about half for gamma ray irradiation is demonstrated for gold nanoparticles treated cells as compared to untreated cells. In cells with exposed to gamma ray, DNA damage was increased when compared to only radiation exposed cells. The study revealed a significant reduction in radiation dose for killing the cells with internalized gold nanoparticles as compared to the cells without gold nanoparticles. The gold nanoparticles treatment resulted in enhancement of radiation effect as evident from increase in relative biological effectiveness values for photon irradiated cells.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.18-19
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• 2011

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.179-182
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• 2017

Cerebral nervous system intervention procedures have been reported frequently due to radiation exposure such as skin baldness, hair loss, and redness due to prolonged procedures. Therefore, the bismuth shield designed to reduce the radiation exposure of the target organ located in the anterior part of the human body sensitive to skin and radiation sensitivity during CT (computed tomography) scan is applied to the cerebral vascular system intervention by ergonomic design, To reduce the radiation dose of sensitive scalp, we propose a study.