• Journal of Radiation Protection and Research
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• 제46권1호
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• pp.8-13
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• 2021

Background: Salmonella enteritidis (SE) was the main cause of the pandemic of foodborne salmonellosis. The surface of eggs' shells can be contaminated with this bacterium; however, washing them with sodium hypochlorite solution not only reduces their flavor but also heavily impacts the environment. An alternative to this is surface sterilization using low-energy electron beam. It is known that irradiation with 1 kGy resulted in a significant 3.9 log reduction (reduction factor of 10,000) in detectable SE on the shell. FAO/IAEA/WHO indicates irradiation of any food commodity up to an overall average dose of 10 kGy presents no toxicological hazard. On the other hand, the Food and Drug Administration has deemed a dose of up to 3 kGy is allowable for eggs. However, the maximum dose permitted to be absorbed by an edible part (i.e., internal dose) is 0.1 Gy in Japan and 0.5 Gy in European Union. Materials and Methods: The electron beam (EB) depth dose distribution in the eggshell was calculated by the Monte Carlo method. The internal dose was also estimated by Monte Carlo simulation and experimentation. Results and Discussion: The EB depth dose distribution for the eggshells indicated that acceleration voltages between 80 and 200 kV were optimal for eggshell sterilization. It was also found that acceleration voltages between 80 and 150 kV were suitable for reducing the internal dose to ≤ 0.10 Gy. Conclusion: The optimum irradiative conditions for sterilizing only eggshells with an EB were between 80 and 150 kV.

• Journal of Radiation Protection and Research
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• 제40권3호
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• pp.187-193
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• 2015

Deleterious effects of high dose radiation exposure with high-dose-rate are unarguable, but they are still controversial in low-dose-rate. The regulator of G-protein signaling (RGS) is a negative regulator of G protein-coupled receptor (GPCR) signaling. In addition, it is reported that irradiation stress led to GPCR-mediated mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3-k) signaling. The RGS mRNA expression profiles by whole body radiation with low-dose-rate has not yet been explored. In the present study, we, therefore, examined which RGS was modulated by the whole body radiation with low-dose-rate ($3.49mGy{\cdot}h^{-1}$). Among 16 RGS expression tested, RGS6, RGS13 and RGS16 mRNA were down-regulated by low-dose-rate irradiation. This is the first report that whole body radiation with low-dose-rate can modulate the different RGS expression levels. These results are expected to reveal the potential target and/or the biomarker proteins associated with male testis toxicity induced by low-dose-rate irradiation, which might contribute to understanding the mechanism beyond the testis toxicity.

• KSBB Journal
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• 제28권6호
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• pp.415-422
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• 2013

Gamma irradiation (${\gamma}IR$) is widely used for radiotherapy as a treatment of cancer cells although it has a risk to damage normal cells. Inflammation is regarded as one of side effects of ${\gamma}IR$ while the effect of low dose of ${\gamma}IR$ on inflammation has not been researched well. Here, we investigated the inflammatory responses of low dose of ${\gamma}IR$ on murine spleen cells. It was evaluated if ${\gamma}IR$ affected the mitogen-induced lymphocyte proliferation, the regulation of various inflammatory cytokines (IFN-${\gamma}$, IL-2, IL-17, IL-4, IL-10), and the involvement of Ikaros and MAPK/NF-${\kappa}B$ medicated mechanism. Exposure of $^{137}Cs-{\gamma}IR$ below 2 Gy decreased the lymphocytes proliferative response to mitogens (LPS, ConA) except at the lowest dose, 0.05 Gy. IL-17, IL-2 and IL-4 mRNA increased at 0.5 and 2 Gy, but not altered at 0.05 Gy. IL-10, anti-inflammatory cytokine, increased only at 0.05 Gy. In regard to intracellular signaling, p-JNK, p-p38 and p-$I{\kappa}B{\alpha}$ were not changed, whereas the activation of ERK and Ikaros increased at the lowest dose. These results suggest that exposure of ${\gamma}IR$ less than 0.5 Gy (or below 0.05 Gy) has beneficial effects as a radiation hormesis on immune function.

• 한국환경농학회지
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• 제19권4호
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• pp.324-327
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• 2000

저선량 조사한 대두종자의 초기생육과 대두 유식물체의 후속고선량에 대한 방사선 감수성 변화를 알아보고자 저선량 0, 4, 8, 12, 20 Gy를 조사하여 재배한 대두 유식물체에 ${\gamma}$선 50, 100, 200 Gy를 조사한 후 생육상황을 관찰하였다. 저선량 조사에 의해 대두 신규종자의 발아율 증가효과는 없었으나 작물 생장 증대효과는 있었으며 저선량 8 Gy 조사구가 가장 효과적이었다. 대두유식물체의 고선량 방사선에 의한 생육장해는 사전 저선량조사에 의해 크게 감소되었으며 저선량 조사에 의한 고선량 방사선 저항성 증가는 8 Gy와 20 Gy조사에서 가장 효과적이었다.

• Journal of Radiation Protection and Research
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• 제38권4호
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• pp.166-171
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• 2013

While high-dose ionizing radiation results in long term cellular cytotoxicity, chronic low-dose (<0.2 Gy) of X- or ${\gamma}$-ray irradiation can be beneficial to living organisms by inducing radiation hormesis, stimulating immune function, and adaptive responses. During chronic low-dose-rate radiation (LDR) exposure, whole body of mice is exposed to radiation, however, it remains unclear if LDR causes changes in gene expression of the whole brain. Therefore, we aim to investigate expressed genes (EGs) and signaling pathways specifically regulated by LDR-irradiation ($^{137}Cs$, a cumulative dose of 1.7 Gy for total 100 days) in the whole brain. Using microarray analysis of whole brain RNA extracts harvested from ICR and AKR/J mice after LDR-irradiation, we discovered that two mice strains displayed distinct gene regulation patterns upon LDR-irradiation. In ICR mice, genes involved in ion transport, transition metal ion transport, and developmental cell growth were turned on while, in AKR/J mice, genes involved in sensory perception, cognition, olfactory transduction, G-protein coupled receptor pathways, inflammatory response, proteolysis, and base excision repair were found to be affected by LDR. We validated LDR-sensitive EGs by qPCR and confirmed specific upregulation of S100a7a, Olfr624, and Gm4868 genes in AKR/J mice whole brain. Therefore, our data provide the first report of genetic changes regulated by LDR in the mouse whole brain, which may affect several aspects of brain function.

• Archives of Pharmacal Research
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• 제20권3호
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• pp.212-217
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• 1997

Induction of an adaptive response to ionizing radiation in mouse lymphoma (EL4) cells was studied by using cell survival fraction and apoptotic nucleosomal DNA fragmentation as biological end points. Cells in early log phase were pre-exposed to low dose of ${\gamma}$-rays (0.01 Gy) 4 or 20 hrs prior to high dose ${\gamma}$-ray (4, 8 and 12 Gy for cell survival fraction analysis; 8 Gy for DNA fragmentation analysis) irradiation. Then cell survival fractions and the extent of DNA fragmentation were measured. Significant adaptive response, increase in cell survival fraction and decrease in the extent of DNA fragmentation were induced when low and high dose .gamma.-ray irradiation time interval was 4 hr. Addition of protein or RNA synthesis inhibitor, cycloheximide or 5,6-dichloro-1-.betha.-d-ribofuranosylbenzimidazole (DRFB), respectively during adaptation period, the period from low dose ${\gamma}$-ray irradiation to high dose ${\gamma}$-ray irradiation, was able to inhibit the induction of adaptive response, which is the reduction of the extent DNA fragmentation in irradiated EL4 cells. These data suggest that the induction of adaptive response to ionizing radiation in EL4 cells required both protein and RNA synthesis.

• Journal of Radiation Protection and Research
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• 제37권3호
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• pp.159-166
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• 2012

본 연구는 저선량율 방사선에 의한 급성독성을 조사하기 위해 BALB/c 마우스에게 낮은 선량율에 방사선을 만성 노출 후 일반증상과 체중, 장기중량, 부검소견, 혈액 및 뇨 검사를 통해 독성유무를 관찰하였다. 각각 암 수 20마리 마우스는 각 5마리씩 4군으로 분류하고, 3.49 $mGy{\cdot}h^{-1}$의 저선량율 방사선을 정상대조군, 0.02, 0.2, 2 Gy를 각각 5.7시간, 2.4일, 24일 간 지속적으로 노출시키고 조사 후 1일에 마우스를 희생하여 독성을 평가하였다. 저선량율 방사선은 최고선량의 (2 Gy) 노출에도 사망률, 임상증상, 체중, 사료와 음수 섭취량, 뇨검사, 혈청 생화학에서 독성이 관찰되지 않았다. 하지만 고환, 난소, 자궁을 포함한 생식 장기는 방사선량 의존적으로 장기의 무게가 감소되었으나, 다른 장기의 무게 변화는 관찰되지 않았다. 모든 방사선 조사군에서 혈액학적인 부작용은 관찰되지 않았고, 단지 호중구수가 노출선량에 의존적으로 증가하였다. 이번 실험결과 마우스에서 저선량율 방사선 노출은 최고 선량인 2 Gy의 노출에 다른 부작용은 관찰되지 않았으나, 암컷 수컷의 생식장기에 무게 감소가 관찰되었다.

• Journal of Radiation Protection and Research
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• 제39권3호
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• pp.134-141
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• 2014

방사선요법은 항암 치료에서 널리 이용되는 요법으로, 항암치료에 저선량 방사선을 이용하는 것에 대한 관심이 증가되고 있고, 저선량 방사선의 다양한 생물학적 효과가 있음이 보고되고 있다. 그러므로 본 연구에서는 마우스 모델에서 저선량 방사선이 면역반응에 어떠한 영향을 미치는지, 또한 이를 감지할 수 있는지를 조사하였다. C57BL/6 마우스에 $^{137}Cs$ 선원을 이용하여 연속 3일간 총 90 mGy의 저선량 방사선을 전신 조사한 후 마지막 방사선 조사 2, 14, 28일 후에 마우스를 희생시켜 말초 혈액 세포수, 비장 세포수, 비장 내 면역세포의 비율과 활성화 정도를 분석하였다. 말초 혈액 검사를 통해, 저선량 방사선 조사군에서 적혈구와 혈소판 수의 유의적 변화는 관찰할 수 없었으며, 백혈구 수는 마지막 방사선 조사 후 2일째에 선량-의존적인 감소를 보였으나, 점차 회복되는 경향을 나타냈다. 비장세포 수도 2일째 감소를 보였지만 서서히 그 수가 증가됨을 확인하였다. 2일과 14일째에 비장세포의 Foxp3 mRNA가 감소된 반면, CD4 T 세포와 CD69 양성세포가 증가되었다. 마우스에서 분할 저선량 방사선을 전신조사한 결과, 방사선조사군에서 특이적인 임상 증상이나 유의적인 체중감소를 보이지 않았다. 본 연구에서는 마우스를 대상으로 저선량을 분할 조사하였을 경우에도 면역학적 변화를 확인할 수 있으며 이를 통해 향후 저선량 방사선의 생물학적 효과를 뒷받침하는 자료로 활용할 수 있으리라 기대한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 추계학술대회 논문집
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• pp.80-84
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• 1993

In this research, we studied the variation of the dielectric loss absorption of the dielectric loss absorption of the sample according with the change to $\^$60/Co-${\gamma}$-ray irradiation dose of the influence of temperature and applied voltage. In order to investigate the effect of irradiation oriented polypropylene film, we have observed dissipation factor within the temperature range of 30∼130 [$^{\circ}C$] and voltage range of 100∼250$^{\circ}C$ [V]. As for the dependency of temperature by dissipation factor, the ${\alpha}$-peak which appears at high temperature increases accordingly to the increasement of irradiation dose which is contributed by the crystal region and moves towards the high temperature. The ${\beta}$-peak which appears at low temperature is origined from dipoles and molecular motions in the amorphous region. As for the dependency of voltage by tan$\delta$, at low temperature the peak of the tan$\delta$, at low temperature the peak of the tan$\delta$ shifts accordingly to the increasement of irradiation dose towards the high temperature region.

• 환경생물
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• 제20권3호
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• pp.197-204
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• 2002

저선량 $\gamma선 조사가 참박의 초기생육과 생리활성에 미치는 효과를 알아보기 위하여 참박 종자에 $\gamma선을 0-2O Gy 수준으로 조사하여 생육을 관찰하였다. 저선량 $\gamma선에 의한 참박의 초기생육은 대조구에 비해 4-16Gy에서 다소 증가하였고, 생육 조사시 측정한 자엽의 경우 catalase와 Peroxidase 활성이 대조구에 비해 8 Gy 조사구에서 가장 높았으며 본엽은 peroxidase활성이 4 Gy 조사구에서 확연히 증가하였다. 저선량 $\gamma선을 조사한 박 식물체의 광 스트레스에 대한 반응효과는 광계II의 광화학적 효율이 대조구와 8 Gy의 경우 50% 정도 감소되었으나 4 Gy에서는 40% 정도의 감소를 보였다. 반면 Fo는 광저해가 진행됨에 따라 약간의 증가를 보였으나 대조구나 저선량 조사구사이의 차이는 거의 없는 것으로 나타났다. 광계II의 광양자 수율, $\varphi_{PSII}$과 광계II 반응중심의 흥분 포획능, 1/Fo-l/Fm 또한 광저해가 진행되는 동안 감소하여 $\varphi_{PSII}$는 대조구와 8 Gy의 경우 20% 정도 감소를 보인 반면 4 Gy 조사구는 15%의 감소를 보였고, 1/Fo-lF/m은 대조구와 8 Gy는 55%, 4 Gy는 45%의 감소를 나타냈다. 비광화학적 소멸인 NPQ는 대조구와 저선량 조사구 모두 70% 정도 감소되는 경향을 보였다. 이러한 결과를 볼 때 종자의 종피를 투과한 저선량의 $\gamma선이 참박의 생육을 촉진시키고 4 Gy에서 광 스트레스에 대한 저해가 감소되었다.