Combined Effects of Gamma-irradiation and Hyperthermia on the Human Cell Lines for Various Temperatures and Time Sequences / 대한치료방사선과학회지

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.

Evaluation of DNA Double Strand Breaks in Human and Mouse Lymphocyte Following gamma-Irradiation / 대한치료방사선과학회지

The evaluation of radiation-induced DNA double strand breaks(DSB) was made following irradiation of human lymphocytes, murille lymphocytes and EL-4 leukemia cells over a wide dose range of 60Co g-rays. In lipopolysacchande(LPS) or phytohemagglutinin(PHA)-stimulated murine lymphocytes, the slopes of the strand scission factor(SSF) revealed that lymphocytes with LPS increased DNA DSB formation by a factor of 1.432 (p<0.005). Furthermore, strand break production was relatively inefficient in the T lymphocytes compared to the B lymphocytes. And EL-4 leukemia cells were found to form significantly more DNA DSB to a greater extent than normal lymphocytes (p<0.705). The in vitro studies of the intrinsic radiosensitivity between human lymphocytes and murine lymphocytes showed similar phasic kinetics. However, murine lymphocytes were lower in DNA DSB formation and higher in the relative radiation dose of 10 percent DNA strand breaks at 3.5 hours following g-irradiation than human lymphocytes. Though it is difficult to interpret these results, these differences may be result from environmental and genetic factors. From our data, if complementary explanations for this difference will be proposed, the differences in the dose-effect relationship for the induction of DSB between humans and mice must be related to interspecies variations in the physiological condition of the peripheral blood in vitro and not to differences in the intrinsic radiation sensitivity of the lymphocytes. These results can be estimated on the basis of dose-effect correlation enabling the interpretation of clinical response and the radiobiological parameters of cytometrical assessment.

Quantitative Analysis of DNA Single-strand Breaks in EL 4 cells and Mouse Spleen Lymphocytes after Irradiation / 대한치료방사선과학회지

The filter elution technique was used to assay Co-60 g ray-induced DNA single-strand breaks (SSB) in EL 4 mouse leukemia cell and spleen lymphocyte. The lymphocytes were stimulated with lipopolysaccharide (LPS, 20 mug/ml) to label [3H] thymidine. EL 4 cells and lymphocytes in suspension were exposed at 0degree C to gy, 1 gy, 5 gy, 10 gy of Co-60 radiation and elution procedure was performed at PH 12.1. The number of DNA single-strand breaks increased with increasing doses of g rays. The strand scission factor (SSF) was estimated in each experiment (eluted volume 21 ml. The slope for EL 4 cells was 0.01301+/-0.00096 gy-1(n=5) and the slope for lymphocytes was 0.01097+/-0.00091 gy-1(n=5). The slopes were significantly different (p<0.005). Thus EL 4 cells were more sensitive to induction of DNA SSB by ionizing radiation than lymphocytes.

Computed tomography of malignant maxillary sinus tumors

CT was done 81 times on 63 proven malignant maxillary sinus tumors for 3 years from Feb.1979 to May 1982 atSeoul National University Hospital. Pre-treatment CT were 54 and post-treatment CT were 31 on 28 patient. Theresult were as follows; 1. The most frequent histopathologic diagnosis was 44 cases (69.8%) of squamous cellcarcinoma. Others were 5 cases (7.9%) of adenoid cystic carcinoma, 3 cases (4.8%) of olfactory neuroblastoma, 3cases (4.8%) of malignant lymphoma, 2 cases (3.2%) of melanoma, 2 cases (3.2%) of malignant fibrous histiocytoma,a rhabdomyosarcoma, a basal cell carcioma, a fibrosarcoma and a metastatic carcinoma from thyroid follicular adenocarcinoma. 2. The CT findings in 54 untreated malignant maxillary sinus tumors were sinus opacification, softtissue mass, and bone destruction in all cases. Other findings were fat plane obliteration (70%),osteosclerosis(59%), bone erosion and displacement (46%), low densities within soft tissue mass (27%), and airdensitis wiithin soft soft tissue mass (27%), and air densities within soft tissue mass(13%). 3. The value of pre-treatment CT in malignant maxillary sinus tumors were outlining the disease process especially soft tissuesuch as orbit, infratemporal fossa, pterygopalatine fossa, nasopharynx, pterygoid fossa and intracranialextension, and CT is the choice of diagnostic modality to determine the prognosis and the therapeutic planning insurgery and/or radiotherapy. 4. Post-treatment CT is also helpful to evalute the change in tumor size andpost-treatment complication.

Early response of the mouse skin to superfractionated irradiation

A study has been made on the skin response of mouse hind limb to radiation to evaluate the difference of skin response to superfractionation and conventional fractionation schedules, and to optimize the time interval betweenfractions and the dose per fraction in the superfractionated irradiation. 96 mouse hind limbs were dvided into 12groups and were irradiated with 10 consecutive fractions by intervals of 6, 12 or 24 hours and dose per fractionsof 400, 500, 600 or 700 rads. The skin changes of the irradiated hind limb were observed for 30 days and the skin response were analyzed. The results are as follows; 1. There was no significant difference of early skin response along the time interval, from 6 to 24 hours, up to 600 rads per fraction. 2. Mean duration to maximum skin reaction in superfractionation (15.48±2.80 days) is shorter than in conventional fractionation (18.05±3.20 days)by 2.57 days. (p<0.05). 3. Optimum time interval betwen fractions in superfractionation may be 6 hours or less. 4. Optimum dose per fraction in superfractionation may be 500 rads or less.