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Media type:
E-Article
Title:
Differential Cytotoxic Effects of Hyperthermia below and above 43°C Alone or Combined with X Irradiation
Contributor:
Dikomey, Ekkehard
Published:
Academic Press, Inc., 1981
Published in:
Radiation Research, 88 (1981) 3, Seite 489-501
Language:
English
ISSN:
0033-7587;
1938-5404
Origination:
Footnote:
Description:
<p>The effect of hyperthermia alone or combined with X irradiation on the proliferative capacity of CHO cells was studied for temperatures between 41 and 46°C. For heat treatments in the range 41-43°C or 43-46°C, the Arrhenius plot yielded an inactivation energy of 417 ± 28 and 167 ± 16 kcal/mole, respectively. Hyperthermia at 42 and 45°C, which by itself killed 10% of the cells, was combined with single X-ray doses ranging up to 7 Gy or with fractionated irradiation with two doses of 3 Gy. A mathematical description was developed to determine the effect of hyperthermia on repair of sublethal damage. At 37°C sublethal damage was repaired with a half-time of 43.3 min. At 42°C, hyperthermia accelerated the fixation of damage and enhanced repair of remaining sublethal damage, reducing the half-time to 19.3 min. In contrast, hyperthermia at 45°C did not affect fixation of damage but depressed the rate of repair of sublethal damage, thus increasing the half-time to 83 min.</p>