PURPOSE: We conducted clonogenic assay using human cancer cell lines (MKN-45, PC-14, Y-79, HeLa) to investigate a correlation between the parameters of radiosensitivity. MATERIALS AND METHODS: Human cancer cell lines were irradiated with single doses of 1, 2, 3, 5, 7 and 10Gy for the study of radiosensitivity and sublethal damage repair capacity was assessed with two fractions of 5Gy separated with a time interval of 0, 1, 2, 3, 4, 6 and 24 hours. Surviving fraction was assessed with clonogenic assay using Sperman-K rber method and mathematical analysis of survival curves was done with linear-quadratic (LQ), multitarget-single hit (MS) model and mean inactivation dose (D). RESULTS: Surviving fractions at 2Gy (SF2) were variable among the cell lines, ranged from 0.174 to 0.85. The SF2 of Y-79 was lowest and that of PC-14 was highest (p<0.05, t-test). LQ model analysis showed that the values of alpha for Y-79, MKN-45, HeLa and PC-14 were 0.603, 0.356, 0.275 and 0.102 respectively, and those of beta were 0.005, 0.016, 0.025 and 0.027 respectively. Fitting to MS model showed that the values of Do for Y-79, MKN-45, HeLa and PC-14 were 1.59, 1.84, 1.88 and 2.52 respectively, and those of n were 0.97, 1.46, 1.52 and 1.69 respectively. The s calculated by Gauss-Laguerre method were 1.62, 2.37, 2.61 and 3.95 respectively. So the SF2 was significantly correlated with alpha, Do and D. Their Pearson correlation coefficiencics were -0.953 and 0.993, 0.999 respectively (p<0.05). Sublethal damage repair was saturated around 4 hours and recovery ratios (RR) at plateau phase ranged from 2 to 3.79. But RR was not correlated with SF2, alpha, beta, Do, D. CONCLUSION: The intrinsic radiosensitivity was very different among the tested human cell lines. Y-79 was the most sensitive and PC-14 was the least sensitive. SF2 was well correlated with alpha, Do, and D. RR was high for MKN-45 and HeLa but had nothing to do with radiosensitivity parameters. These basic parameters can be used as baseline data for various in vitro radiobiological experiments.
Cell Line* ; Humans* ; Radiation Tolerance*

PURPOSE: We conducted clonogenic assay using human cancer cell lines (MKN-45, PC-14, Y-79, HeLa) to investigate a correlation between the parameters of radiosensitivity. MATERIALS AND METHODS: Human cancer cell lines were irradiated with single doses of 1, 2, 3, 5, 7 and 10Gy for the study of radiosensitivity and sublethal damage repair capacity was assessed with two fractions of 5Gy separated with a time interval of 0, 1, 2, 3, 4, 6 and 24 hours. Surviving fraction was assessed with clonogenic assay using Sperman-K rber method and mathematical analysis of survival curves was done with linear-quadratic (LQ), multitarget-single hit (MS) model and mean inactivation dose (D). RESULTS: Surviving fractions at 2Gy (SF2) were variable among the cell lines, ranged from 0.174 to 0.85. The SF2 of Y-79 was lowest and that of PC-14 was highest (p<0.05, t-test). LQ model analysis showed that the values of alpha for Y-79, MKN-45, HeLa and PC-14 were 0.603, 0.356, 0.275 and 0.102 respectively, and those of beta were 0.005, 0.016, 0.025 and 0.027 respectively. Fitting to MS model showed that the values of Do for Y-79, MKN-45, HeLa and PC-14 were 1.59, 1.84, 1.88 and 2.52 respectively, and those of n were 0.97, 1.46, 1.52 and 1.69 respectively. The s calculated by Gauss-Laguerre method were 1.62, 2.37, 2.61 and 3.95 respectively. So the SF2 was significantly correlated with alpha, Do and D. Their Pearson correlation coefficiencics were -0.953 and 0.993, 0.999 respectively (p<0.05). Sublethal damage repair was saturated around 4 hours and recovery ratios (RR) at plateau phase ranged from 2 to 3.79. But RR was not correlated with SF2, alpha, beta, Do, D. CONCLUSION: The intrinsic radiosensitivity was very different among the tested human cell lines. Y-79 was the most sensitive and PC-14 was the least sensitive. SF2 was well correlated with alpha, Do, and D. RR was high for MKN-45 and HeLa but had nothing to do with radiosensitivity parameters. These basic parameters can be used as baseline data for various in vitro radiobiological experiments.
Cell Line* ; Humans* ; Radiation Tolerance*

No abstract available
Adenocarcinoma* ; Humans* ; Radiation Tolerance* ; Stomach*

To investigate the relationship between Radiosensitivity and postirradiation recovery in human cancer cells, a study was performed using human cancer cell lines-A549, CaSki, SNU-C5 and PCI-13. for the study of radiosensitivity, single doses of 2, 4, 6, 8, 10, 12, and 14 Gy were given and for postirradiation recovery, two fractions of 4 Gy were separated with a time interval of 0, 0.5, 1,1.5, 2, 2.5, 3, 4, 5, or 6 hours. Surviving fraction was estimated using colony forming ability. Surviving fractions at 2 Gy (SF2) were 0.496 (0.570-0.412) for A549, 0.496 (0.660-0.332) for CaSki, 0.386 (0.576-0.216) for SNU-C5, and 0.185(0.247-0.123) for PCI-13. By statistical analysis the SF2 of PCI-13 was lower significantly than those of others (p<0.05). this difference was also observed at 4,6 and 8 Gy dose levels. At 6 and 8 Gy the surviving fractions of SMU-C5 were also lower significantly than A549 and CaSki(p<0.05). By the analysis with linear quadratic model, the value of alpha for A549, CaSki, SNU-C5 and PCI-13 were 0.3016, 0.3212, 0.4327 and 0.8423, respectively, and those of betawere 0.024929, 0.02009, 0.03349 and 0.00059, respectively. So, the value of alpha showed increasing tendency with decreasing SF2.By the multitarget single hit model the values of Do for A549, CaSki, SUN-C5 and PCI-13 were 1.97, 1.97,1.46 and 0.81, respectively, and those of n were 1.53, 1.50, 1.56 and 2.28, respectively. So, the value of Do decreased with decreasing SF2. Post-irradiation recovery reached plateau at around 2 hours. Recovery ratio at plateau phase ranged from 1.2 to 4.2; the value were 1.2 for PCI-13, 3.2 for CaSki, 3.3 for SNU-C5, and 4.2 for A549. Recovery rate well correlated with SF2, and increased with increasing Do and decreasing alpha. According to above results, the intrinsic radiosensitivity was quite different among the tested cell ilnes; PCI-13 was the most sensitive and A549 and CaSki was similar. This difference of radiosensitivity is thought to be partly due to the difference in amount of postirradiation recovery. By linear quadratic model the difference of alpha values was very high, and by multitarget single hit model the difference of Do value was significantly high among four cell lines.
Cell Line* ; Humans* ; Radiation Tolerance*

PURPOSE: A sensitive predictive assay is necessary to determine the total radiation dose according to sensitivity of individual cancer cell lines. This study is performed to determine whether the radiation sensitivity is correlated with the changes in telomerase activity after irradiation. MATERIALS AND METHODS: Two colorectal cancer cell lines with different radiation sensitivity were used. In order to confirm the difference in radiation sensitivity, we used a calorimetric assay. Telomerase activities were measured using the PCR-based telomeric repeat amplification protocol (TRAP). RESULTS: We confirmed the difference in radiation sensitivity between NCI-H630 and NCI-H716. Survival fractions at 2 Gy were 0.836 for NCI-H630 and 0.317 for NCI-H716. Telomerase activity increased after irradiation with NCI-H630, which was more resistant to radiation, whereas telomerase activity decreased with NCI-H730. But dose-dependent change of telomerase activity was not confirmed. CONCLUSION: Our results suggested that telomerase activity change after irradiation could be used as a predictive assay for radiation response. Further studies with different cell lines and tumor tissues are necessary.
Cell Line ; Colorectal Neoplasms ; Radiation Tolerance ; Telomerase*

Humans ; Laryngeal Neoplasms ; radiotherapy ; Radiation Tolerance ; Radiotherapy

To determine the radiosensitivity and dose-urvival characteristics of jejunal crypt cells, experimental study was done using total 40 mice. Single irradiation of 1,000rad to 1,600rad was delivered to whole bodies of mice, using a cesium 137 animal irradiator. The number of regenerating crypts per jejunal circumference was counted, by using a jejunal crypt cell assay technique, and dose response curve was measured. The average number of jejunal crypt per circumference in control group was 140+/-10. Mean lethal dose(D0) of mouse jejunal crypt cell was 135rad.
Animals ; Cesium ; Jejunum* ; Mice* ; Radiation Tolerance*

Radiation sensitivity data was generated for two human cancer cell lines(KB, RPMI 2650) and human primary gingival fibroblast was tested three times using a viable cell number counting with a hemocytometer, MTT(3-[4,5-dimethylthiazol 2-yl]-2,5-dipheny tetrazolium bromide) assay, and LDH(Lactate dehydrogenase) assay. Single irradiation of 2, 4, 6, 10, 15, 20 Gy were aplied to the tumor cell lines and the primary cultured gingical fibroblast. The two fractions of 4 Gy an d 10 Gy were seperated with a 4 hour time interval. The irradiation was done with 241.5 cGy/min dose rate using 137 Cs MK cell irradiator at room temperature. The obtained results were as followed: 1. There was significantly different viable cell numbers as the amount of radiation dose on the tested cells were cell number counted with a hemocytometer, In fractions, there were more viable cells remaining, 2. Phase-contrast microscopically, radiation-induced morphologic changes were pronounced on the tumor cells, however, a lmost no differences on the gingival fibroblast. 3. There was significantly different absorbance at 2 Gy on RPMI 2650, 4 Gy on KB and GF in MTT assay. In fractions, the absorbance was significantly higher on KB. 4. THe level of extracellular LDH activity in the experimental group was significantly higher in the 2-4 Gy than the co ntrol group. 5. The total level of extracellular and intracellular LDH activity was decreased as increased amounts of radiation dose was applied.
Cell Count ; Cell Line, Tumor* ; Fibroblasts ; Humans ; Radiation Tolerance*

The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chomotherapy . For this study, cell surviving curves were obtained for mouse lymphoma YAC-1 cell line using semiautomated MTT assay. 2, 4, 6, 8, 10Gy were irradiated at a dose rate of 210cGy/min using 60Co Irradiator ALDORADO 8. After irra diation, YAC-1 cell lines(3X10(4) cells/ml) were exposed to bleomycin or cisplatin for 1 hour. The viable cells were determined for each radiation dose and/or each concentration of drug at the 4th day. And they w ere compared to control values. The obtained results were as follows: 1. The surviving curve with gentle slope was obtained after irradiation of 2, 4, 6, 8, 10Gy on YAC-1 cell line. 2. The cytotoxicity of bleomycin or cisplatin was increased significantly at all concentration of 0.2microgram/ml, microgram/ml an d 20microgram/ml on YAC-1 cell line (P<0.01). 3. There were no significant differences of surviving fractions among 4Gy, 6Gy, and 8Gy after irradiation of each radia tion dose with 2microgram/ml of bleomycin compared with irradiation only on YAC-1 cell line(P<0.05). 5. There were significant differences of surviving fractions between the groups of irradiation only and the groups of i rradiation with 2microgram/ml of bleomycin or cisplatin at all doses of 2, 4, 6, 8 and 10Gy on YAC-1 cell line(P<0.05).
Animals ; Bleomycin ; Cell Line* ; Cisplatin ; Lymphoma ; Mice ; Radiation Tolerance* ; Radiotherapy

PURPOSE: Esophageal tolerance is needed to guide the safe administration of stereotactic radiosurgery (SRS). We evaluated comprehensive dose-volume parameters of acute esophageal toxicity in patients with spinal metastasis treated with SRS. MATERIALS AND METHODS: From May 2008 to May 2011, 30 cases in 27 patients with spinal metastasis received single fraction SRS to targets neighboring esophagus. Endpoints evaluated include length (mm), volume (mL), maximal dose (Gy), and series of dose-volume thresholds from the dose-volume histogram (volume of the organ treated beyond a threshold dose). RESULTS: The median time from the start of irradiation to development of esophageal toxicity was 2 weeks (range, 1 to 12 weeks). Six events of grade 1 esophageal toxicity occurred. No grade 2 or higher events were observed. V15 of external surface of esophagus was found to predict acute esophageal toxicity revealed by multivariate analysis (odds radio = 1.272, p = 0.047). CONCLUSION: In patients with spinal metastasis who received SRS for palliation of symptoms, the threshold dose-volume parameter associated with acute esophageal toxicity was found to be V15 of external surface of esophagus. Restrict V15 to external surface of esophagus as low as possible might be safe and feasible in radiosurgery.
Esophagus ; Humans ; Multivariate Analysis ; Neoplasm Metastasis ; Radiation Tolerance ; Radiosurgery*