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*

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

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*

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*

Humans ; Laryngeal Neoplasms ; radiotherapy ; Radiation Tolerance ; Radiotherapy

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

We tried to establish the theoretical basis of clinical use of combined modality of hyperthermia and radiation therapy. For this purpose, we made an in vitro experiment in order to get the synergistic and/or additive effects on the cell killing of hyperthermia combined with radiation therapy by using the microwave-hyperthermia machine already installed at our department. In our experiment, we use two human cell lines: MKN-45(adenocarcinoma of stomach) and K-562(leukemia cell lines). In cases of combined treatments of hyperthermia and gamma-irradiation, the therapeutic effect was the highest in the simultaneous trial. Hyperthermia after gamma irradiation showed slightly higher therapeutic effect than that before irradiation without significant difference, but its effect was the same in the interval of 6 hours between hyperthermia and irradiation. The higher temperature and the longer treatment time were applied, the higher therapeutic effects were observed. We could observe the thermoresistance by time elapse at 43 degree C. When hyperthermia was done for 30 minutes at the same temperature, thermal enhancement ratio(TER) at D0.01(dose required surviving fraction of 0.01) were 2.5+/-0.08, 3.75+/-0.18, and 5.0+/-0.15 at 43 degree C, 44 degree C, and 45 degree C respectively in K-562 leukemia cell lines. Our experimental data showed that more cell killing effect can be obtained in the leukemia cell lines, although they usually are known to be radiosensitive, when treated with combined hyperthermia and radiation therapy. Furthermore, our data show that leukemia cell lines May have various intrinsic radiosensitivity, especially in vitro experiments. The magnitude of cell killing effect, however, will be less than that of MKN-45.
Cell Line* ; Fever* ; Homicide ; Humans* ; Leukemia ; 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*