• Journal of Radiation Protection and Research
• /
• 제40권1호
• /
• pp.25-35
• /
• 2015

We analyzed the differential effects of histopathology, apoptosis and expression of radiation response genes after chronic low dose rate (LDR) and acute high dose rate (HDR) radiation exposure in spleen, lung and liver of rats. Female 6-week-old Sprague-Dawley rats were used. For chronic low-dose whole body irradiation, rats were maintained for 14 days in a $^{60}Co$ gamma ray irradiated room and received a cumulative dose of 2 Gy or 5 Gy. Rats in the acute whole body exposure group were exposed to an equal dose of radiation delivered as a single pulse ($^{137}Cs$-gamma). At 24 hours after exposure, spleen, lung and liver tissues were extracted for histopathologic examination, western blotting and RT-PCR analysis. 1. The spleen showed the most dramatic differential response to acute and chronic exposure, with the induction of substantial tissue damage by HDR but not by LDR radiation. Effects of LDR radiation on the lung were only apparent at the higher dose (5 Gy), but not at lower dose (2 Gy). In the liver, HDR and LDR exposure induced a similar damage response at both doses. RT-PCR analysis identified cyclin G1 as a LDR-responsive gene in the spleen of rats exposed to 2 Gy and 5 Gy gamma radiation and in the lung of animals irradiated with 5 Gy. 2. The effects of LDR radiation differed among lung, liver, and spleen tissues. The spleen showed the greatest differential effect between HDR and LDR. The response to LDR radiation may involve expression of cyclin G1.

• 한국환경농학회지
• /
• 제22권3호
• /
• pp.215-219
• /
• 2003

채소종자의 발아와 초기생장에 대한 저선량 방사선과 종자수분 함량의 영향을 알아보고자 배추, 무, 고추, 호박 참박 각각의 건조종자와 습윤종자에 저선량 감마선을 $0{\sim}20\;Gy$ 수준으로 조사하였다. 수분함량을 상이하게 하여 관찰한 발아와 초기생장에 미치는 저선량 방사선 효과는 작물종에 따라 다르게 나타났다. 발아율의 경우는 건조종자보다 습윤종자에서 대체로 높았으며 저선량 효과는 배추와 호박의 습윤종자4 Gy와 2 Gy에서 각각 33%와 13% 증가하여 뚜렷한 효과를 보였고, 참박은 건조종자 $4{\sim}8\;Gy$에서 높았다. 초기생장은 습윤종자에서 뚜렷한 효과를 보여 배추와 무는 10 Gy, 호박은 2 Gy, 참박은 8 Gy에서 $6{\sim}26%$ 정도 증가하였다. 이러한 초기생장 촉진효과는 저선량 방사선과 수분함량 상호간에 유의적인 차이를 보였으며 특히 배추와 참박에서 가장 높았다. 즉, 채소 종자의 수분함량을 상이하게 하여 저선량 방사선의 효과를 조사한 결과 적정 수분함량에서 발아와 유묘생장이 촉진됨을 확인할 수 있었다.

• 한국환경농학회지
• /
• 제19권5호
• /
• pp.394-400
• /
• 2000

${\gamma}-Radiation$ at very low doses frequently has a stimulating or hormetic effect on the growth of organism. Effects of low dose ${\gamma}-ray$ irradiation on the root growth of soybean cultivars were investigated and hormetic effects by environmental conditions were compared with the occurrence of increased economic yield, seeds of cultivars were irradiated with the dose of $0.5{\sim}20Gy$ and cultivated in growth chamber controling temperature, humidity, light, greenhouse and field respectively. To understand hormetic effect on root growth of cultivars and the difference of hormetic effect by cultivation environment, harvested root of soybean cultivars were scanned with image file, and root surface area, root length, root average diameter etc. were examined by WinRhizo program. Also, dry weight of cultivars was examined. Root growth and dry weight of soybean cultivars showed apparently hormetic effect at cultivation of growth chamber condition. In field experiment executed for whole life cycle, yields of pea were not different significantly in each ${\gamma}-ray$ irradiated cultivars but weight of one hundred peas increased in whole ${\gamma}-ray$ irradiated cultivars. Increment of yield was assumed to be induced through shortening of maturing stage caused by ${\gamma}-ray$ hormesis in early growth stage.

• 전기전자학회논문지
• /
• 제15권2호
• /
• pp.143-148
• /
• 2011

MOS (Metal-Oxide Semconductor) devices among the most sensistive of all semiconductors to radiation, in particular ionizing radiation, showing much change even after a relatively low dose. The necessity of a radiation dosimeter robust enough for the working environment has increased in the fields of aerospace, radio-therapy, atomic power plant facilities, and other places where radiation exists. The power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) has been tested for use as a gamma radiation dosimeter by measuring the variation of threshold voltage based on the quantity of dose, and a maximum total dose of 30 krad exposed to a $^{60}Co$ ${\gamma}$-radiation source, which is sensitive to environment parameters such as temperature. The gate oxide structures give the main influence on the changes in the electrical characteristics affected by irradiation. The variation of threshold voltage on the operating temperature has caused errors, and needs calibration. These effects can be overcome by adjusting gate oxide thickness and implanting impurity at the surface of well region in MOSFET.

• Journal of Photoscience
• /
• 제9권2호
• /
• pp.397-399
• /
• 2002

The seedling height, leaf width and leaf length of pepper increased in plants grown from seeds irradiated with the low dose of 4 Gy. The $O_2$ evolution in the 4 Gy irradiation group was 1.5 times greater than the control. Pmax was decreased with increasing illumination time by 20% in the control, while hardly decreased in the 4 Gy irradiation group. Fv/Fm was decreased with increasing illumination time by 50% after 4 hours, while Fv/Fm in the 4 Gy irradiation group was decreased by 37% of inhibition, indicating that the low dose $\gamma$ radiation increased resistance of plants to photoinhibition.

• Fibers and Polymers
• /
• 제5권2호
• /
• pp.156-159
• /
• 2004

Novoloid fibers have high chemical, flame and thermal resistance; however they have low tensile properties. Effects of gamma irradiation on the tensile properties of novoloid fibers have been investigated. Loop and knot resistance have also been examined. Maximum tenacity of the single fiber increased with an increase of the radiation dose applied. According to the loop and knot tenacity results it is found that brittleness has been also affected by the amount of radiation dose.

• 대한방사선방어학회:학술대회논문집
• /
• 대한방사선방어학회 2011년도 추계 학술발표회 및 심포지엄
• /
• pp.212-213
• /
• 2011

The biological effects of low dose ionizing radiation (LDIR) remain insufficiently understood. We examined for the scientific evidence to show the biological effects of LDIR using radiation-sensitive immune cells. We found that Ikaros protein was responsed to low dose-dependent effects of gamma radiation in IM-9 B lymphocytes. Ikaros encodes zinc finger transcription factors that is important regulators of a hematopoietic stem cells (HSCs) progression to the B lymphoid lineage development, differentiation and proliferation. In this study, we observed that cell proliferation was enhanced from 10% to 20% by LDIR (0.05 Gy) in IM-9 B lymphocytes. The Ikaros protein was phosphorylated in its serine/threonine (S/T) region and decreased its DNA binding activity in the cells exposed to LDIR. We found that Ikaros phosphorylation was up-regulated by CK2/AKT pathway and the residues of ser-304 and ser-306 in Ikaros was phosphorylated by LDIR. We also observed that Ikaros protein was localized from the nucleus to the cytoplasm after LDIR and bound with Autotaxin (ENPP2, ATX) protein, stimulating proliferation, migration and survival of immune cells. In addition, we found that the lysoPLD activity of ATX was dependent on Ikaros-ATX binding activity. These results indicate that the Ikaros is an important regulator of immune activation. Therefore, we suggest that low dose ionizing radiation can be considered as a beneficial effects, stimulating the activation of immune cells.

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

• Journal of Radiation Protection and Research
• /
• 제26권4호
• /
• pp.409-415
• /
• 2001

저선량 방사선 조사가 묵은 고추종자의 발아율과 발아종자의 생리활성에 미치는 효과 등을 알아보고자 4년 저장한 조광고추와 3년 저장한 홍광고추 종자에 저선량 ${\gamma}$선을 $2{\sim}50Gy$ 까지 조사하여 관찰한 결과는 다음과 같다. 저선량 조사한 고추종자의 발아율은 대조구보다 증가하는 경향을 보였다. 특히 발아초기에 그 효과가 뚜렷하게 나타나 파종 7일 후에 조광고추 품종은 4Gy 조사구에서 74%, 홍광고추 품종은 8 Gy 조사구에서 11% 증가하였다. 고추의 유묘초장에서도 거의 모든 저선량 조사구에서 증가하였는데 특히 조광고추 품종은 4 Gy 조사구에서, 홍광고추 품종은 8 Gy 조사구에서 유의성있는 증가효과를 보였다. 저선량 조사한 종자의 단백질 함량은 조광고추 풀종은 발아후기에, 홍광고추 품종은 발아초기에 증가하였고, catalase와 peroxidase 활성은 조광고추 품종은 4 Gy 조사구에서, 홍광고추 품종은 8 Gy 조사구에서 높은 값을 보였다. 이에 저선량 ${\gamma}$선 조사에 의해 묵은 종자의 발아와 생리활성이 촉진됨을 확인할 수 있었다.

• Journal of Radiation Protection and Research
• /
• 제20권2호
• /
• pp.97-102
• /
• 1995

인체 말초 혈액 림프구에서 저선량의 감마선에 의해 유도되는 적응 반응을 관찰하였다. 인체 림프구를 저선량의 감마선(priming dose 0.01Gy) 을 조사한 후 여러 시간 간격 후 고선량 (challenging dose, 1.5Gy) 을 조사하였다. 저선량을 미리 조사한 림프구와 조사하지 않은 림프구에서 발생된 미세핵의 빈도를 계수하였다. 비세핵 발생 빈도는 저선량 조사 4시간 후 고선량을 조사하였을 때 최대 감소치를 보였다. 저선량과 고선량 조사 시간차가 7시간 또는 20시간이었을 때 미세핵 발생 빈도는 약간 감소하였으나 유의성은 없었다. 본 연구에서는 $G_0$상태의 세포주기에서 저선량을 조사하였을 경우 적응 반응이 나타나는 것이 관찰 되었다. 미세핵 분석법은 실험 방법이 비교적 간단하고, 기타 염색체 분석법에 비하여 빠른 시간내 결과를 도출 할 수 있어 추후 방사선에 대한 적응 반응의 연구에 유용한 지표가 될 수 있을 것이다.