• Radiation Oncology Journal
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• 제12권2호
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• pp.129-141
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• 1994

Intracellular ions which have a major role in cellular function have been reported to affect repair of radiation damage. Recently it has been reported that ouabain sensitizes A549 tumor cellls but not CCL-120 normal cells to radiation. Ouabain inhibits the $Na^+-K^+$-pump rapidly thus it increases intracellular Na concentration, Vanadate which is distributed extensively in almost all living organisms is known to be a $Na^+-K^+$-ATPase inhibitors, This study was performed to see any change in radiosensitivity of tumor cell by vanadate and any role of $Na^+-K^+$ATPase in radiosensitization. Experiments have been carried out by pretreatment with vanadate in human cell line(A549, JMG) and mouse cell line(L1210, spleen). For the cell survival MTT assay was performed for A549 and JMC cells and frypan blue dye exclusion test for L120, and spleen cells. Measurements of $Na^+-K^+$-ATPase activity in control, vanadate treated cell, radiation treated cell (9 Gy for A549 and JMG, 2 Gy for L1201, spleen), and combined $10^{-6}M$ vanadate and radiation treated cells were done. The results were summerized as fellows. 1. L1210 cell was most radiosensitive, and spleen cell and JMG cell were intermediate, and A549 cell was least radiosensitive. 2. Mininum or no cytotoxicity was seen with vanadate below concentration of $10^{-6}M$. 3. In A549 cells there was a little change in radiosensitivity with treatment of vanadate. However radiation sensitization was shown in low dose level of radiation i. e. 2- Gy. In JMG cells no change in radiosensitivity was noted. Both L1210 and spleen cell had radiosensitization but change was greater in tumor cell. 4. $Na^+-K^+$-ATPase activity was inhibited significantly in tumor cell by treatment of vanadate. 5. Radiaiton itself inhibited $Na^+-K^+$-ATPase activity of tumor cell with high $Na^+-K^+$-ATPase concention. Increase in radiosensitivity by vanadate was closely associated with orginal $Na^+-K^+$-ATPase contents. From the above results vanadate had little cytotoxicity and it sensitized tumor cells to radiation. Inhibitory effect of vanadate on $Na^+-K^+$-ATPase activity might be one of the contributing factors for radiosensitization to tumor cells which has greater enzyme activity than that of normal cell. It was suggested vanadate could be used as a potential radiosensitizer for tumor cells.

• Radiation Oncology Journal
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• 제38권2호
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• pp.99-108
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• 2020

Purpose: The probability of recurrence of cancer after adjuvant or definitive radiotherapy in patients with human papillomavirus-negative (HPV(-)) head and neck squamous cell carcinoma (HNSCC) varies for each patient. This study aimed to identify and validate radiation sensitivity signature (RSS) of patients with HPV(-) HNSCC to predict the recurrence of cancer after radiotherapy. Materials and Methods: Clonogenic survival assays were performed to assess radiosensitivity in 14 HNSCC cell lines. We identified genes closely correlated with radiosensitivity and validated them in The Cancer Genome Atlas (TCGA) cohort. The validated RSS were analyzed by ingenuity pathway analysis (IPA) to identify canonical pathways, upstream regulators, diseases and functions, and gene networks related to radiosensitive genes in HPV(-) HNSCC. Results: The survival fraction of 14 HNSCC cell lines after exposure to 2 Gy of radiation ranged from 48% to 72%. Six genes were positively correlated and 35 genes were negatively correlated with radioresistance, respectively. RSS was validated in the HPV(-) TCGA HNSCC cohort (n = 203), and recurrence-free survival (RFS) rate was found to be significantly lower in the radioresistant group than in the radiosensitive group (p = 0.035). Cell death and survival, cell-to-cell signaling, and cellular movement were significantly enriched in RSS, and RSSs were highly correlated with each other. Conclusion: We derived a HPV(-) HNSCC-specific RSS and validated it in an independent cohort. The outcome of adjuvant or definitive radiotherapy in HPV(-) patients with HNSCC can be predicted by analyzing their RSS, which might help in establishing a personalized therapeutic plan.

• Radiation Oncology Journal
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• 제10권2호
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• pp.155-161
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• 1992

눈의 수정체는 방사선에 매우 예민한 장기이며 비교적 적은 선량에서도 백내장의 원인이 될 수 있다. 그러므로 두경부암의 방사선치료에서 수정체를 최대한 차폐하면서 병소에 집중 조사하는 방법이 개발되어야 한다. 저자는 안구의 표면에서 0.5 cm 깊이에 위치하며 폭 1 cm인 눈의 수정체를 최대한 차폐하면서 주위 병소를 치료하기 위하여 원자번호가 높은 차폐물질을 이용하였으며 최적조사조건은 측정실험을 통하여 결정하였고 이를 임상치료에 응용하였다. 수정체의 차폐기구는 제작하기 쉽고 차폐효과가 큰 혼합금속(Cerrobend)이 적당하였으며 두께 7.5 cm와 직경 1 cm의 원뿔기둥모양이 가장 이상적이었다. 차폐기둥의 밑면과 표면과의 거리가 l0 cm일 때 수정체에 가장 적은 선량이 부여되며 병소에는 비교적 많은 선량이 부여된다. 이때 각막(Cornea, 1 mm), 수정체 (Eye Lens, 5 mm), 망막(Retina, 25 mm) 및 병소(Tumor, 50 mm 이상)의 선량은 차폐물이 없을 때와 비교하여 각각 $10.0\%$, $15.2\%$, $21.5\%$ 및 $23.2\%$로 측정되었다.

• 치과방사선
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• 제13권1호
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• pp.17-27
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• 1983

The author observed the effects of /sup 60/Co irradiation on the development and subcellular structure of tongue tissue of the fetal rats. The lower left abdomen of mothers were exposed to radiation on 15½th day of gestation with 300R. The fetuses were removed on the 6hr, 14hr, 24hr, 48hr and 72hr after irradiation and the light microscopic and electron microscopic observations of the lingual epithelium, lamina propria and muscle layer were carried out. The results were as follows: 1. The irradiated fetuses showed the retardation of filiform papillae formation. 2. Epithelial cells revealed fusion and myelination of mitochondria, large autolysosomes, increased lipid droplets, retardation of tonofilaments and desmosome formation. 3. In the lamina propria, undifferentiated cells showed bleb formation of nuclear membrane, pyknosis and fragmentation of nucleus, edema of cytoplasm I and nucleus, increased auto-lysosomes, dilatation of cell membrane and cell necrosis. Also, collagenous fibril formation was inhibited by irradiation. 4. In the muscle layer, growth of myotubes was inhibited. Myotubes showed swelling of mitochondria, loss of mitochondrial cristae, autolysosomes, retardation of myofibril formation, and large vacuoles. Undifferentiated cells adjacent myotube contained pyknotic nucleus and autolysosomes. 5. Among the various tissues of tongue, it seems that mesenchymal cells were most radiosensitive.

• The Plant Pathology Journal
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• 제31권2호
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• pp.176-180
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• 2015

Postharvest diseases cause losses in a wide variety of crops around the world. Irradiation, a useful nonchemical approach, has been used as an alternative treatment for fungicide to control plant fungal pathogens. For a preliminary study, ionizing radiations (gamma, X-ray, or e-beam irradiation) were evaluated for their antifungal activity against Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer through mycelial growth, spore germination, and morphological analysis under various conditions. Different fungi exhibited different radiosensitivity. The inhibition of fungal growth showed in a dose-dependent manner. Three fungal pathogens have greater sensitivity to the e-beam treatment compared to gamma or X-ray irradiations. The inactivation of individual fungal-viability to different irradiations can be considered between 3-4 kGy for B. cinerea and 1-2 kGy for P. expansum and R. stolonifer based on the radiosensitive and radio-resistant species, respectively. These preliminary data will provide critical information to control postharvest diseases through radiation.

• 환경생물
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• 제20권1호
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• pp.35-39
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• 2002

The significance of cell ploidy and repair ability for the radioprotective efficiency of cysteamine was studied in DNA repair - proficient and repair - deficient yeast cells irradiated $^{60}C0\;\gamma-rays.$ Results have been obtained for the cell survival of two groups of yeasts-diplont and haplont cells, both in haploid and diploid states. For diploid Saccharomyces cerevisiae yeast cells, the correlation between the radio-protective action of cysteamine and the cell repair capacity was demonstrated. Such a correlation was not clearly expressed for haploid yeast cells. In addition, evidence was obtained indicating that the degree of the radioprotective action was independent of the number of chromosome sets in haplont yeast Pichia guilliermondii cells and in some radiosensitive mutants defective in the diploid-specific recovery. It is concluded on this basis that the radioprotective action may involve the cellular recovery process, which may be mediated by a recombination-like mechanism, for which the diploid state is required. The results obtained clearly show that the radioprotective effect was dependent on DNA repair status and indicate that the mechanism of the radioprotective action may be realized on the level of primary radiation damage production as well as on the level of postradiation recovery from potentially lethal radiation damage.

• Nuclear Engineering and Technology
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• 제40권7호
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• pp.551-560
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• 2008

Radiation has stochastic aspects in its generation, its choice of interaction mode during traveling in media, and its impact on living bodies. In certain circumstances, like in high dose environments resulting from low-LET radiation, the variance in its impact on a target volume is negligible. On the contrary, in low dose environments, especially when they are attributed to high-LET radiation, the impact on the target carries with it a large variance. This variation is more significant for smaller target volumes. Microdosimetric techniques, which have been developed to estimate the distribution of radiation energy deposited to cellular and subcellular-sized targets, contrast with macrodosimetric techniques which count only the average value. Since cells and DNA compounds are the critical targets in human bodies, microdosimetry, or dose estimation by microscopic approach, helps one better analyze the biological effects of radiation on the human body. By utilizing microbeam systems designed for individual cell irradiation, scientists have discovered that human cells exhibit radiosensitive reactions without being hit themselves (bystander effect). During the past 10 or more years, a new therapeutic protocol using discontinuous multiple micro-slit beams has been investigated for its clinical application. It has been suggested that the beneficial bystander effect is the essence of this protocol.

• 한국동물학회지
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• 제10권1호
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• pp.17-20
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• 1967

The present experiment was perform to investigate the frequencies of chromosome aberration with special regard to the chromosome groups and the various time intervals after X-irradiation (60 r) in ormal human foetus cells grown in culture. The cytological preparations were prepared at every 5 through 30 hours after X-irradiation by the air-drying method. 1. The frequencies of chormosome aberration are on the whole decreased as tie elapses after irradiation and this is thought to be due to gradual recovery with time . However, a slight increase in frequencies is observed at 25 and 30 hours after irradiation respectively. This shows that the cells at the these periods are more sensitivity to X-irradation , and those cells are thought to be at G$_2$ and late S stage at the time of irradiation respectively, so t is evident that G$_2$ and late S stages a the time of irradiation respectively , so it is evident that G$_2$ and late S stages are more sensitive to X-irradiation than any other stages. 2. The frequencies of chormosome aberration are decreased in descending order of chormosome group number. The differences among these frequencies are highly significant statistically . Therefore it can be concluded that there is a highly significant difference in radiosensitivity among chromosome groups. that is, the chromosomes of the group A are the most radiosensitive , followed by B, C, D ,E and G in descending order.

• Asian Pacific Journal of Cancer Prevention
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• 제16권16호
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• pp.7285-7290
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• 2015

Background: Although radiotherapy is one of the most effective strategies in the treatment of cancers, it is associated with short and long term side effects on normal tissues. Zataria multiflora Boiss (Laminacea) (ZM) has several biological properties such as antioxidant and anti-inflammation activities.Here we investigated cell killing effects of a hydroalcoholic Zataria multiflora extract on cell death induced by ionizing radiation in a human glioblastoma cell line (A172) and human non-malignant fibroblasts (HFFF2) in vitro. Materials and Methods: A172 and HFFF2 cells were treated with a hydroalcoholic extract of dried aerial parts of Zataria multiflora at different concentrations (25, 50, 100, 150 and $200{\mu}g/ml$) and then exposed to ionizing radiation (IR). Cell proliferation and DNA fragmentation were evaluated. Thymol content in the extract was analyzed and quantified by HPLC methods. Results: A172 cell proliferation was significantly inhibited by ZM. The percentage cell survival was $91.8{\pm}8.57$ for cells treated with $200{\mu}g/ml$ of ZM extract alone while it was $76.0{\pm}4.27$ and $66.2{\pm}8.42$ for cells treated with ZM and exposed to IR at doses of 3Gy and 6Gy, respectively. Radiation-induced apoptosis in A172 cells was significantly increased following treatment with ZM at doses of $200{\mu}g/ml$. ZM extract did not exhibit any enhanced cell killing effects and apoptosis caused by IR on HFFF2 cells. Conclusions: These data show selective radiosensitization effects of ZM in A172 cells apparently due to increased radiation-induced apoptosis.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1495-1504
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• 2017

In a previous study, a set of polygon-mesh (PM)-based skin models including a $50-{\mu}m-thick$ radiosensitive target layer were constructed and used to calculate skin dose coefficients (DCs) for idealized external beams of electrons. The results showed that the calculated skin DCs were significantly different from the International Commission on Radiological Protection (ICRP) Publication 116 skin DCs calculated using voxel-type ICRP reference phantoms that do not include the thin target layer. The difference was as large as 7,700 times for electron energies less than 1 MeV, which raises a significant issue that should be addressed subsequently. In the present study, therefore, as an extension of the initial, previous study, skin DCs for three other particles (photons, protons, and helium ions) were calculated by using the PM-based skin models and the calculated values were compared with the ICRP-116 skin DCs. The analysis of our results showed that for the photon exposures, the calculated values were generally in good agreement with the ICRP-116 values. For the charged particles, by contrast, there was a significant difference between the PM-model-calculated skin DCs and the ICRP-116 values. Specifically, the ICRP-116 skin DCs were smaller than those calculated by the PM models-which is to say that they were under-estimated-by up to ~16 times for both protons and helium ions. These differences in skin dose also significantly affected the calculation of the effective dose (E) values, which is reasonable, considering that the skin dose is the major factor determining effective dose calculation for charged particles. The results of the current study generally show that the ICRP-116 DCs for skin dose and effective dose are not reliable for charged particles.