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: 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*

Humans ; Laryngeal Neoplasms ; radiotherapy ; Radiation Tolerance ; Radiotherapy

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*

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*

PURPOSE: The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. MATERIALS AND METHODS: Four human cancer cell lines-PCI-1, SNU-1066, NCI-H630 and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy. For clonogenic assay, cells in 25 cm2 flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10~14 days. For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. RESULTS: There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R2 value of 0.975~0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was after 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. CONCLUSION: In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least.
Cell Count ; Cell Line ; Humans ; Radiation Tolerance* ; Tetrazolium Salts

The purpose of this study was to evaluate the usefulness of reducing of craniofacial radiation dose using automatic exposure control (AEC) technique in the 64 multi-detector computed tomography (MDCT). We used SOMATOM Definition 64 multi-detector CT, and head of whole body phantom (KUPBU-50, Kyoto Kagaku CO. Ltd). The protocol were helical scan method with 120 kVp, 1 sec of rotation time, 5 mm of slice thickness and increment, 250 mm of FOV, 512x512 of matrix size, 64x0.625 mm of collimation, and 1 of pitch. The evaluation of dose reducing effect was compared the fixed tube current of 350 with AEC technique. The image quality was measured the noise using standard deviation of CT number. The range of craniofacial bone was to mentum end from calvaria apex, which devided three regions: calvaria~superciliary ridge (1 segment), superciliary ridge~acanthion (2 segment), and acanthion~mentum (3 segment). In the fixed tube current technique, CTDIvol was 57.7 mGy, DLP was 640.2 mGy.cm in the all regions. The AEC technique was showed that 1 segment were 30.7 mGy of CTDIvol, 340.7 mGy.cm of DLP, 2 segment were 46.5 mGy of CTDIvol, 515.0 mGy.cm of DLP, and 3 segment were 30.3 mGy of CTDIvol, 337.0 mGy.cm of DLP. The standard deviation of CT number was 2.622 with the fixed tube current technique and 3.023 with the AEC technique in the 1 segment, was 3.118 with the fixed tube current technique and 3.379 with the AEC technique in the 2 segment, was 2.670 with the fixed tube current technique and 3.186 with the AEC technique in the 3 segment. The craniofacial radiation dose using AEC Technique in the 64 MDCT was evaluated the usefulness of reducing for the eye, the parotid and thyroid with high radiation sensitivity particularly.
Chin ; Eye ; Head ; Noise ; Radiation Tolerance ; Skull ; Thyroid Gland

In the present study, a perfluorochemical emulsion (Fluosol-DA 20%) did not alter Do and and Dq values on cell survival curve, indicating that the lack of a direct effect of Fluosol-DA 20% on cellular radiosensitivity in vitro. The effect of Fluosol-DA 20% injection in combination with carbogen breathing was determined on the hupoxic cell fraction in SCK tumors. The hypoxic cell fraction in control SCK tumors was 0.39. This value decreased to 0.05 when the mice were i.v. injected with 12 ml/kg of Fluosol-DA 20% in a carbogen atomosphere. The measured mean and median PO2 values with a microelectorde in the control tumors was 9 mmHg and 4 mmHg, respectively. The treatment of the SCK tumors in the host mice with injected Fluosol-DA 20% in combination with carbogen breathing increased the mean and median PO2 values to 67 mmHg and 62 mmHg, respectively. Using carbogen breathing alone caused a moderate increase of tumor PO2. But Fluosol-DA 20% injection alone caused little change PO2 in the tumor. It was concluded that the combination of Fluosol-DA injection and carbogen breathing is an effective means to improve oxygenation of tumors.
Animals ; Cell Survival ; Mice ; Oxygen* ; Radiation Tolerance ; Respiration