• Nuclear Engineering and Technology
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• 제45권3호
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• pp.385-392
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• 2013

Zirconium and zirconium alloys are widely used as nuclear reactor core materials such as fuel cladding and guide tubes because they have excellent corrosion- and radiation-resistant properties. In the reactor core, zirconium alloys are subjected to high-energy neutron fluence, causing radiation-induced dislocation and growth. To discern a possible correlation between radiation-induced dislocation and growth, characteristics of dislocation and growth in zirconium and its alloys are examined. The radiation-induced dislocation including and dislocation loops is reviewed in various temperature and fluence ranges, and their growth behavior is examined in the same way. To further a fundamental understanding, radiation-induced growth prediction models are briefly reviewed. This research will assist in the design of zirconium based components as well as the safety analysis of various reactor conditions, in both research and commercial reactors.

• Asian Pacific Journal of Cancer Prevention
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• 제13권10호
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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.

• 대한방사선치료학회지
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• 제14권1호
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• pp.165-174
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• 2002

혈관내피세포 성장 인자(Vascular endothelial growth factor, VEGF)는 혈관내피세포 특이하게 성장요인으로 작용하는 물질로 알려져 있다. 전리방사선에 대한 혈관내피세포의 효과는 정상조직에 대한 반응에 있어 아주 중요한 요소일 것으로 생각된다. 본 연구는 방사선 조사에 의해 배양시킨 혈관내피세포에서 apoptosis가 유도되는지, 유도가 된다면 VEGF에 의해 apoptosis가 억제되는지 그리고 apoptosis의 억제가 어떤 경로를 경유하는지를 실험하였다. 혈관내피세포에 방사선를 조사한 결과, 대조군에 비하여 선량이 증가함에 따라 apoptosis가 증가하였다. 같은 조건하에서 VEGF는 농도 의존적으로 apoptosis를 억제하였다. Antiapoptotic factor로서 VEGF가 어떤 신호 과정을 경유하는지를 밝히고자, 혈관내피세포에 방사선을 조사하여 apoptosis를 유도하면서 Flt-1과 Flk-1/KDR receptor를 처리하였다. 그결과 VEGF에 유도된 apoptosis 억제효과가 차단되었다. Phosphatidylinositol 3'-kinase(PI3-kinase) 특정 억제 물질인 Wortmanin과 LY294002를 방사선 조사한 혈관내피에 VEGF와 함께 처리했을 때 VEGF에 의해 유도된 apoptosis를 억제하였다. 이같은 결과는 VEGF가 방사선 조사로 일어나는 세포 치사를 억제하는 중요한 역할을 담당하며, In Vivo의 실험이 더 이루어져야 할 것으로 생각된다.

• The Korean Journal of Physiology and Pharmacology
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• 제17권4호
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• pp.267-274
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• 2013

A beneficial radioprotective agent has been used to treat the radiation-induced lung injury. This study was performed to investigate whether curcumin, which is known to have anti-inflammatory and antioxidant properties, could ameliorate radiation-induced pulmonary inflammation and fibrosis in irradiated lungs. Rats were given daily doses of intragastric curcumin (200 mg/kg) prior to a single irradiation and for 8 weeks after radiation. Histopathologic findings demonstrated that macrophage accumulation, interstitial edema, alveolar septal thickness, perivascular fibrosis, and collapse in radiation-treated lungs were inhibited by curcumin administration. Radiation-induced transforming growth factor-${\beta}1$ (TGF-${\beta}1$), connective tissue growth factor (CTGF) expression, and collagen accumulation were also inhibited by curcumin. Moreover, western blot analysis revealed that curcumin lowered radiation-induced increases of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), TNF receptor 1 (TNFR1), and cyclooxygenase-2 (COX-2). Curcumin also inhibited the nuclear translocation of nuclear factor-${\kappa}B$ (NF-${\kappa}B$) p65 in radiation-treated lungs. These results indicate that long-term curcumin administration may reduce lung inflammation and fibrosis caused by radiation treatment.

• Toxicological Research
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• 제20권2호
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• pp.117-122
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• 2004

The present study was carried out to establish a short-term teratogenicity study for detecting developmental toxic potential induced by gamma radiation in ICR mice. Pregnant mice were exposed at dose levels of 0, 0.5, 1, 2, or 4 Gy on gestational day 8.5. All dams were subjected to caesarean section on gestational day 10.5 and their embryos were examined for growth, differentiation, and morphological abnormalities. An increase in the number of resorption was found at 4 Gy in a dose-dependent manner. Dose-dependent decreases in the developmental score of yolk sac circulation and olfactory system at above 1 Gy, in the number of somite pairs and developmental score of allantois, optic system, and maxillary process at above 2 Gy, and in the all growth and developmental parameters examined at 4 Gy were found. Various types of morphological abnormalities were seen at dose levels of 0.5 Gy or greater. Characteristic malformations induced by gamma radiation were abnormal axial rotation, hematoma, craniofacial hypoplasia, open neuropore, shortened prosencephalon, kinked somites, irregular somites, swelling, hydropericardium, absent branchial bar, and absent limb bud. Morphological alterations such as hematoma, craniofacial hypoplasia, open neuropore, and kinked somites were noted even in the lowest dose (0.5 Gy). These results indicated that the short-term teratogenicity study established in this study can be a useful tool for not only detecting the developmental toxic potential induced by gamma radiation, but also screening radio-protective agents in ICR mice.

• Radiation Oncology Journal
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• 제32권3호
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• pp.156-162
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• 2014

Purpose: This study was designed to evaluate the efficacy and safety of topically applied recombinant human epidermal growth factor (rhEGF) for the prevention of radiation-induced dermatitis in cancer patients. Materials and Methods: From December 2010 to April 2012, a total of 1,172 cancer patients who received radiotherapy (RT) of more than 50 Gy were prospectively enrolled and treated with EGF-based cream. An acute skin reaction classified according to the Radiation Therapy Oncology Group 6-point rating scale was the primary end point and we also assessed the occurrence of edema, dry skin, or pruritus. Results: The percentage of radiation dermatitis with maximum grade 0 and grade 1 was 19% and 58% at the time of 50 Gy, and it became 29% and 47% after completion of planned RT. This increment was observed only in breast cancer patients (from 18%/62% to 32%/49%). Adverse events related to the EGF-based cream developed in 49 patients (4%) with mild erythema the most common. Skin toxicity grade >2 was observed in 5% of the patients. Edema, dry skin, and pruritus grade ${\geq}3$ developed in 9%, 9%, and 1% of the patients, respectively. Conclusion: Prophylactic use of an EGF-based cream is effective in preventing radiation dermatitis with tolerable toxicity. Further studies comparing EGF cream with other topical agents may be necessary.

• 식물조직배양학회지
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• 제26권4호
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• pp.265-269
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• 1999

고구마 산성 peroxidase (POD) (swpal) 또는 중성 POD(swpnl)을 도입한 형질전환 담배에 다양한 선량의 감마선을 조사한 후 30일에 항산화효소 활성과 식물생장에 미치는 영향을 조사하였다. 감마선은 조사선량에 비례하여 형질전환 식물체와 정상식물에 관계없이 모든 식물체의 생장을 크게 억제시켰다. 50-70 Gy 처리에서 식물체의 신장이 크게 억제되었고 새로운 잎이 발생되지 못하였다. 10-50 Gy의 조사선량에서는 POD, superoxide dismutase, catalase 활성에 큰 변화를 주지 않았다. 이러한 결과는 고구마 POD는 감마선 조사에 의해 유도되는 산화적인 스트레스에 대한 보호효과에 관여하지 않음이 시사된다.

• Radiation Oncology Journal
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• 제32권3호
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• pp.208-212
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• 2014

Marfan syndrome is one of the collagen vascular diseases that theoretically predisposes patients to excessive radiation-induced fibrosis yet there is minimal published literature regarding this clinical scenario. We present a patient with a history of Marfan syndrome requiring radiation for a diagnosis of a right brachial plexus malignant nerve sheath tumor. It has been suggested that plasma transforming growth factor beta 1 (TGF-${\beta}1$) can be monitored as a predictor of subsequent fibrosis in this population of high risk patients. We therefore monitored the patient's TGF-${\beta}1$ level during and after treatment. Despite maintaining stable levels of plasma TGF-${\beta}1$, our patient still developed extensive fibrosis resulting in impaired range of motion. Our case reports presents a review of the literature of patients with Marfan syndrome requiring radiation therapy and the limitations of serum markers on predicting long-term toxicity.

• Journal of Photoscience
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• 제9권2호
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• pp.162-165
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• 2002

Rice is widely cultivated in various regions throughout Asia. Over a five-year period, we investigated the effects of supplemental UVB radiation on the growth and yield of Japanese rice cultivars in the field. The findings of that study indicated that supplemental UVB radiation has inhibitory effects on the growth and grain development. Furthermore, we investigated the sensitivity to UVB radiation of rice cultivars of 5 Asian rice ecotypes, and found that rice cultivars vary widely in UVB sensitivity. The aim of our study is improving UVB resistance in plants by bioengineering or breeding programs. In order to make it, there is need to find the molecular origin of the sensitivity to UVB. Cyclobutane pyrimidine dimer (CPD) is major UV-induced DNA lesions. Plants possess two mechanisms to cope with such DNA damage. The first is the accumulation of UV-absorbing compounds. Our previous data showed that the steady-state CPD levels in leaves of rice grown under chronic radiation in any culture were not so greatly influenced by the increased UV-absorbing compounds content, although there was a significant positive correlation between the CPD levels induced by challenge UVB exposure and the UV-absorbing compounds content. The other is the repair of DNA damage. Photorepair is the major pathway in plants for repairing CPD. We found that the sensitivity to UVB could seriously correlate with the low ability in CPD photorepair in rice plants. These results suggest that photo lyase might be an excellent candidate for restoration by way of selective breeding or engineering in rice.

• 대한방사선협회지
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• 제25권1호
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• pp.317-323
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• 1999

The response of endothelial cells to ionizing radiation is thought to be an important factor in the overall response of normal tissue. It has been reported that basic fibroblast growth factor (bFGF), a potent mitogen for endothelial cells, protects endoth