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권재,안희영,사문선,원종하,신정임,이창준 한국뇌신경과학회 2017 Experimental Neurobiology Vol.26 No.1
Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca2+) level. Therefore, maintaining the intracellular Ca2+ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca2+ homeostasis in astrocytes is the store-operated Ca2+ entry (SOCE). This process is mediated by a combination of the Ca2+-store-depletion-sensor, Stim, and the store-operated Ca2+-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca2+-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca2+-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.
Development of a Low-cost, Comprehensive Recording System for Circadian Rhythm Behavior
권재,박민구,이승은,이창준 한국뇌신경과학회 2018 Experimental Neurobiology Vol.27 No.1
Circadian rhythm is defined as a 24-hour biological oscillation, which persists even without any external cues but also can be reentrained by various environmental cues. One of the widely accepted circadian rhythm behavioral experiment is measuring the wheel-running activity (WRA) of rodents. However, the price for commercially available WRA recording system is not easily affordable for researchers due to high-cost implementation of sensors for wheel rotation. Here, we developed a cost-effective and comprehensive system for circadian rhythm recording by measuring the house-keeping activities (HKA). We have monitored animal’s HKA as electrical signal by simply connecting animal housing cage with a standard analog/digital converter: input to the metal lid and ground to the metal grid floor. We show that acquired electrical signals are combined activities of eating, drinking and natural locomotor behaviors which are well-known indicators of circadian rhythm. Post-processing of measured electrical signals enabled us to draw actogram, which verifies HKA to be reliable circadian rhythm indicator. To provide easy access of HKA recording system for researchers, we have developed user-friendly MATLAB-based software, Circa Analysis. This software provides functions for easy extraction of scalable “touch activity” from raw data files by automating seven steps of post-processing and drawing actograms with highly intuitive user-interface and various options. With our cost-effective HKA circadian rhythm recording system, we have estimated the cost of our system to be less than $150 per channel. We anticipate our system will benefit many researchers who would like to study circadian rhythm.
원전 중대사고 시 WinMACCS와 RASCAL 전산코드를 이용한 소외 사고결말평가
권재,이진오,류강우,김광표 (사)한국방사선산업학회 2021 방사선산업학회지 Vol.15 No.1
After the Fukushima nuclear power plant accident in March 2011, the importance ofevaluating the consequence of the accident is increasing. Accordingly, in South Korea, the law onsubmission of accident management plans including severe accidents was revised in June 2016 toassess accident management capability through probabilistic safety assessment. In this study, werecognized the necessity of verifying the results of the level 3 probabilistic safety assessment andcompared the accident consequence through probabilistic and deterministic methods to confirmthe similarity. In this study, the offsite accident consequence was evaluated for the severe accidentscenario of the US Surry nuclear power plant. For each accident scenario, the radiation source termand the meteorological data of the site of Surry nuclear power plant were used. For the probabilisticconsequence assessment, the WinMACCS computer code was used. For the deterministicconsequence assessment, the RASCAL computer code was used. As a result of the offsiteconsequence assessment, the ratio of the result of the RASCAL computer code to the WinMACCScomputer code was evaluated. In the case of LTSBO, it was 0.53~4.24 times. In the case of STSBO,it was 0.57~3.73 times. In the case of ISLOCA, it was 0.24~2.39 times. In the case of TISGTR, itwas 0.16~1.08 times. These differences were due to the differences in the radiation source term,meteorological data, and exposure modeling methods. The results of offsite consequence assessmentwere evaluated at the same order. It was 0.16 times in minimum, 4.24 times in maximum. Therefore,it is expected that the validity and reliability of probabilistic safety assessment can be judgedeconomically. The results of this study can be used as a basis for establishing a domestic level 3probabilistic safety assessment system.