• 한국식품저장유통학회지
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• 제21권3호
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• pp.315-320
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• 2014

본 연구에서는 후춧가루의 위생화를 위해 감마선, 전자선 및 X-선을 조사한 후 이에 따른 미생물학적 및 관능적 품질변화를 평가하였다. 후춧가루에 감마선, 전자선 및 X-선을 2, 4, 6, 8 및 10 kGy로 각각 조사한 후 미생물 변화와 관능품질 변화를 평가한 결과, 미생물의 경우 선종에 관계없이 흡수선량이 증가할수록 미생물 제어 효과가 증가하는 것으로 나타났으며, 선종별 D10값의 경우 2.24-2.75 kGy범위를 보였으며 방사선 선종에 따른 유의차가 없는 것으로 나타났다. 색도의 경우 명도, 적색도 및 황색도 모두 방사선 선종에 따른 변화가 없는 것으로 판단하였다. 관능적 품질 역시 방사선 선종에 관계없이 흡수선량에 따라 품질저하가 발생되는 것으로 나타났다. 이상의 결과를 종합하여 볼 때 방사선 선종에 따른 후춧가루의 품질변화 차이가 없는 것으로 판단하였으며, 이상의 결과는 X-선의 상업적 이용을 위한 기초 연구 자료로 활용될 수 있을 것으로 사료되었다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2477-2481
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• 2013

Aims and Background: The purpose of the research was to study the prognostic value of tumor 18F-FDG PET-based parameters in neoadjuvant chemoradiation for patients with squamous esophageal carcinoma. Methods: Sixty patients received chemoradiation therapy followed by esophagectomy and two 18FDG-PET examinations at pre- and post-radiation therapy. PET-based metabolic-response parameters were calculated based on histopathologic response. Linear regression correlation and Cox proportional hazards models were used to determine prognostic value of all PET-based parameters with reference to overall survival. Results: Sensitivity (88.2%) and specificity (86.5%) of a percentage decrease of SUVmax were better than other PET-based parameters for prediction of histopathologic response. Only percentage decrease of SUVmax and tumor length correlated with overall survival time (linear regression coefficient ${\beta}$: 0.704 and 0.684, P<0.05). The Cox proportional hazards model indicated higher hazard ratio (HR=0.897, P=0.002) with decrease of SUVmax compared with decrease of tumor size (HR=0.813, P=0.009). Conclusion: Decrease of SUVmax and tumor size are significant prognostic factors in chemoradiation of esophageal carcinoma.

• Radiation Oncology Journal
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• 제11권2호
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• pp.193-203
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• 1993

In understanding radiosensitivity a new concept of inherent radiosensitivity based on individuality and heterogeneity within a population has recently been explored. There has been some discussion of possible mechanism underlying differences in radiosensitivity between cells. Ataxia telangiectasia (AT), a rare autosomal recessive genetic disorder, is characterized by hypersensitivity to ionizing radiation and other DNA damaging agents at the cellular level. There have been a lot of efforts to describe the cause of this hypersensitivity to radiation. At the cellular level, chromosome repair kinetics study would be an appropriate approach. The purpose of this study was to better understand radiosensitivity En an approach to investigate kinetics of induction and repair of $G_2$ chromatic bleaks using normal, AT heterozygous (ATH), and AT homozygous lymphoblastoid cell lines. In an attempt to estimate initial damage, $9-{\beta}-D-arabinosyl-2-fluoroadenine,$ an inhibitor of DNA synthesis and repair, was used in this study. It was found from this study that radiation induces higher chromatid breaks in AT than in normal and ATH cells. There was no significant differences of initial chromatid breaks between normal and ATH cells. Repair kinetics was the same for all. So the higher level of breaks in AT $G_2$ cells is thought to be a reflection of the increased initial damage. The amount of initial damage correlated well with survival fraction at 2 Gy of cell survival curve following radiation. Therefore, the difference of radiosensitivity in terms of $G_2$ chromosomal sensitivity is thought to result from the difference of initial damage.

• Oncology Letters
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• 제41권5호
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• pp.3119-3126
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• 2019

Redd1 is a stress response protein that functions as a repressor of mTORC1, a central regulator of protein translation, resulting in the inhibition of cell growth and metabolism. However, paradoxically, high Redd1 expression favors cancer progression and generates resistance to cancer therapy. Herein, we revealed that constitutive overexpression of Redd1 induced HSP27 and HSP70 expression in lung cancer cells. The expression of Redd1, HSP27 and HSP70 was highly increased in lung cancer tissues compared with that in normal lung tissues. Inhibition of HSP27 or HSP70 suppressed AKT phosphorylation, which was induced by constitutive overexpression of Redd1 and enhanced the inhibitory effects on viability of Redd1-overexpressing cells. Inhibition of AKT phosphorylation resulted in a decrease of HSP27 and HSP70 expression in Redd1-overexpressing cells. These data indicated that HSPs and AKT in Redd1-overexpressing cells positively regulated the function and expression of each other and were involved in lung cancer cell survival. Knockdown of HSP27, HSP70 or AKT enhanced ionizing radiation (IR) sensitivity, particularly in lung cancer cells in which Redd1 was stably overexpressed. Collectively, constitutive overexpression of Redd1 led to HSP27 and HSP70 induction and AKT activation, which were involved in lung cancer cell survival and resistance to IR, suggesting that Redd1 may be used as a therapeutic target for lung cancer.

• Asian Pacific Journal of Cancer Prevention
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• 제15권16호
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• pp.6649-6655
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• 2014

Radiation therapy is an important treatment for head and neck squamous cell carcinoma (HNSCC). However, how to promote radiation sensitivity in HNSCC remains a challenge. This study aimed to investigate the radiosensitizing effects of fenofibrate on HNSCC and explore the underlying mechanisms. HNSCC cell lines CNE-2 and KB were subjected to ionizing radiation (IR), in the presence or absence of fenofibrate treatment. Cell growth and survival, apoptosis and cell cycle were evaluated. In addition, CNE-2 cells were xenografted into nude mice and subjected to IR and/or fenofibrate treatment. The expression of cyclinB and CDK1 was detected by Western blotting. Our results showed that fenofibrate efficiently radiosensitized HNSCC cells and xenografts in mice, and induced apoptosis and G2/M arrest via reducing the activity of the CDK1/cyclinB1 kinase complex. These data suggest that fenofibrate could be a promising radiosensitizer for HNSCC radiotherapy.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1994년도 94 Symposium on Plant science September 10, 1994 Ewha Womans University, Seoul, Korea 94 식물학 심포지움 환경 스트레스와 식물의 반응
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• pp.29-39
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• 1994

Serious issues about the changes in the environmental conditions on earth associated with human activities have arisen, and the interest in these problems has increased. It is urgent to determine how the expansion of terrestrial UV-B radiation due to the stratospheric ozone depletion influences living matters. In this connection, we have been investigating the effects of UV-B radiation on the growth of rice cultivars (Oryza sativa L.). We report here some physiological and genetic aspects of resistance to inhibitory effects of UV-B radiation on growth of rice cultivars as described below. Elevated UV radiation containing large amount of UV-B and a small amount of UV-C inhibited the development of plant height, the photosynthetic rate and the chlorophyll content in rice plants in a phytotron. Similar results were obtained in experiments, in which elevated UV-V radiation. Similar results were obtained in experiments, in which elevated UV-B radiation (transmission down to 290 nm) was applied instead of UV-B radiation containing a small amount of UV-C. The inhibitory effects of UV radiation was alleviated by the elevated CO2 atmospheric environment or by the exposure to the high irradiance visible radiation. The latter suggested the possibility that the resistance to the effects of UV radiation was either due to a lower sensitivity to UV radiation or to a greater ability to recover from the injury caused by UV radiation through the exposure to visible radiation. The examination of cultivar differences in the resistance to UV radiation-caused injuries among 198 rice cultivars belonging to 5 Asian rice ecotypes (aus, aman, boro, bulu and tjeleh) from the Bengal region and Indonesia and to Japanese lowland and upland rice groups showed the following: Various cultivars having different sensitivities to the effects of UV radiation were involved in the same ecotype and the same group, and that the Japanese lowland rice group and the boro ecotype were more resistant. Among Japanese lowland rice cultivars, Sasanishiki (one of the leading varieties in Japan) exhibited more resistance to UV rakiation, while Norin 1 showed less resistance, although these two cultivars are closely related. It was thus indicated that the resistance to the inhibitory effects of UV radiation of rice cultivars is not simply due to the difference in the geographical situation where rice cultuvars are cultivated. Form the genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice using F2 plants generated by reciprocally crossing Sasanishiki and Norin 1 and F3 lines generated by self-fertilizing F2 plants, it was evident that the resistance to the inhibitory of elebated UV radiation in these rice plants was controlled by recessive polygenes.

• Radiation Oncology Journal
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• 제21권3호
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• pp.216-221
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• 2003

목적: Cyclooxygenase-2 (COX-2)를 과발현하는 A549 인간폐암세포주와 발현하지 않는 MCF-7 인간유방암세포주에서 선택적 COX-2 억제제인 celecoxib의 방사선 감수성 증진 작용을 관찰하고자 하였다. 대상 및 방법: A549 세포와 MCF-7 세포에 대해서 방사선 혹은 방사선과 celecoxib를 병용 투여한 후에 clonogenic radiation survival 실험을 시행하였다. 같은 실험을 각각 $10\%$와 $1\%$의 FBS를 포함한 배지에서 반복하였다. 각 세포에 방사선과 celecoxib를 동시 혹은 단독 투여한 후에 각 실험 그룹의 세포사멸을 측정하였다. 결과: 약물 투여 기간 동안 $10\%$의 혈청을 포함한 배지 조건에서 배양된 A549세포에서는, $30\muM$과 $50\muM$ 농도의 celecoxib가 투여된 상태에서 surviving fraction=0.1에서의 Radiation enhancement ratio (RER)가 각각 1.58과 1.81로 celecoxib가 A549 세포의 방사선 감수성을 증가시켰다. 이러한 방사선 감수성의 증가는 세포를 $1\%$의 혈청을 포함한 배지에서 배양하였을때는 소실되었다. MCF-7 세포에서는 $10\%$와 $1\%$ 혈청을 포함한 각각의 배지조건 하에서celecoxib에 의한 방사선 감수성의 변화가 관찰되지 않았다. A549와 MCF-7 세포의 각 그룹에서 세포사멸을 측정한 결과 celecoxib와 방사선이 병용 투여되었을 때 유도되는 세포사멸은 상호 상승적이지 않은 것으로 나타났다. 결론: COX-2 선택적 억제제인 celecoxib는 COX-2를 과발현하는 A549 세포에서 선택적으로 방사선 감수성을 증진시켰으며, 저농도의 혈청을 포함한 배지 조건에서는 이러한 효과가 소실되었다. COX-2를 발현하지 않는 MCF-7 세포주에서는 celecoxib에 의해서 방사선 감수성이 변화되지 않았으며, 이러한 celecoxib의 방사선 감수성 증진 작용 기전에 세포 사멸은 관여하지 않는 것으로 보인다.

• Radiation Oncology Journal
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• 제19권2호
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• pp.163-170
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• 2001

목적 : 방사선조사후 세포의 생존 분획은 세포집락 측정기법으로 확인하는 것이 표준이나 많은 비용과 시간이 소요되는 단점을 갖고 있다. 이에 생존 세포의 tetrazolium염의 자색 formazan 침전물로의 환원시키는 능력에 그 기반을 둔 MTT 기법을 사용하여 세포집락 측정기법을 대체하기 위한 기법으로서의 유용성과 그 실행상의 최적조건을 규명하고자 하였다. 방법 : PCI-1, SNU-1066, NCI-H630, RKO등의 세포주에 0, 2, 4, 6, 8, 10 Gy의 방사선을 조사한 후 세포집락 측정 기법과 MTT기법으로 세포 생존 분획을 조사하였다. 세포집락 측정기법은 $25\;cm^2$ 폴리스티렌 배양 플라스크에 방사선량에 따라 다른 수의 세포를 분주한 후 24시간 동안 배양 후 방사선을 조사하였고 이를 $10\~14$일 동안 배양 후 염색하여 생성된 세포집락의 수를 측정하였다. MTT기법은 침전물의 용해과정이 필요없는 Premix WST-1 시약을 이용하여 시행하였다. MTT기법은 각각의 세포주에서 세포수와 흡광도간의 선형관계와 최적 실험조건을 확인한 이후 시행하였다. 이 기법은 방사선을 조사받은 세포에서는 지수적 성장을 회복한 이후와 방사선을 조사받지 않은 세포는 4회 이상의 세포분열을 거친 후에 시행하였다. 세포집락 측정기법 및 MTT기법을 통하여 얻은 세포 생존율을 구한 후 이를 지표로 비교하였다. 결과 : 각 기법으로 얻은 세포 생존율의 표준편차는 $5\%$ 내외였다. 2가지 방법으로 구한 세포 생존율은 t-test로 비교하였을 때 $0\~4\;Gy$에서는 통계적으로 유의한 차이가 없었으며 회귀분석 결과는 선형적 관계가 있었다$(R^2=0.975-0.992)$. MTT 기법의 시행에 최적인 세포수는 배양효율에 따라 다른 것으로 나타났는데, 배양효율이 $30\%$ 이상이면 300개 이하가, $30\%$ 미만인 경우는 $500\~1,000$개가 적당한 것으로 확인되었다. MTT기법은 6 배가시간 경과 이후에 시행하는 것이 세포집락 측정기법과 가장 근접하였으며 적어도 4 배가시간 이후에 시행하는 것이 필요할 것으로 사료되었다. 이에 따르면 배가시간이 3일 이하인 세포주가 세포 민감성 측정방법으로서 MTT 기법이 세포 집락 측정 기법을 대체하여 사용하기에 적합한 것으로 사료되었다. 결론 : 이상에서, MTT기법을 이용하여 방사선조사 후의 세포생존을 측정하기 위해서는 예비실험을 통해 각 세포주에서의 최적의 조건을 찾는 것이 필수적이며 이 조건하에서 MTT기법을 시행해야만 방사선에 의한 세포 민감성 측정에 이용될 수 있음을 확인하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.402-405
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• 2006

Radiometric calibration of optical image data is necessary to convert raw digital number (DN) value of each pixel into a physically meaningful measurement (radiance). To extract rather quantitative information regarding biophysical characteristics of the earth surface materials, radiometric calibration is often essential procedure. A sensor detects the radiation of sunlight interacted atmospheric constituents. Therefore, the amount of the energy reaching at the sensor is quite different from the initial amount reflected from the surface. To achieve the target reflectance after atmospheric correct, an initial step is to convert DN value to at-sensor radiance. A linear model, the simplest radiometric model, is applied to averaged spectral radiance for this conversion. This study purposes to analyze the sensitivity of several factors affecting on radiance for carrying out absolute radiometric calibration of panchromatic images from KOMPSAT2 launched at July, 2006. MODTRAN is used to calculate radiance at sensor and reflectance of target is measured by a portable spectro-radiometer at the same time the satellite is passing the target for the radiometric calibration. As using different contents of materials composing of atmosphere, the differences of radiance are investigated. Because the spectral sensitivity of panchromatic images of KOMPSAT2 ranges from 500 to 900 nm, the materials causing scattering in visible range are mainly considered to analyze the sensitivity. According to the verified sensitivity, direct measurement can be recommenced for absolute radiometric calibration.

• Journal of Radiation Protection and Research
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• 제43권2호
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• pp.66-74
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• 2018

Background: Tumor response to anticancer therapies can much be influenced by microenvironmental factors. In this study, we determined the effect of these microenvironmental factors on DNA methylation using A549 human lung adenocarcinoma cell line. Materials and Methods: We subjected A549 cells to various conditions mimicking tumor microenvironment including hypoxia, acidosis (sodium lactate), oxidative stress ($H_2O_2$), bystander effect (supernatant from doxorubicin (Dox)-treated or irradiated cells), and immune cell infiltration (supernatant from THP-1 or Jurkat T cells). Genomic DNA was isolated from these cells and analyzed for DNA methylation. Clonogenic cell survival, gene expression, and metabolism were analyzed in cells treated with some of these conditions. Results and Discussion: We found that DNA methylation level was significantly decreased in A549 cells treated with conditioned media from Dox-treated cells or Jurkat T cells, or sodium lactate, indicating an active transcription. To determine whether the decreased DNA methylation affects radiation sensitivity, we exposed cells to these conditions followed by 6 Gy irradiation and found that cell survival was significantly increased by sodium lactate while it was decreased by conditioned media from Dox-treated cells. We further observed that cells treated with conditioned media from Dox-treated cells exhibited significant changes in expression of genes including BAX and FAS (involved in apoptosis), NADPH dehydrogenase (mitochondria), EGFR (cellular survival) and RAD51 (DNA damage repair) while sodium lactate increased cellular metabolism rather than changing the gene expression. Conclusion: Our results suggest that various tumor microenvironmental factors can differentially influence DNA methylation and hence radiosensitivity and gene expression in A549 cancer cells.