Effect of hyperthermia on the radiosensitivity of normal and malignant cells in mice

Abstract

The effect of systemic hyperthermia on the in vivo radiation response of normal and malignant mouse cells was evaluated. X-irradiation of L1210 cells and Ehrlich ascites cells at body temperatures above 41 degrees C resulted in strongly enhanced tumor cell death. The magnitude of this thermal effect increased with increasing temperatures. Hypoxic tumor cells were particularly sensitive to combined heat-radiation treatment. L1210 leukemia cells did not become resistant to the sensitizing effects of hyperthermia even after repeated heat exposures over several transplant generations. The sensitizing action of hyperthermia varied with different heating strategies. Heating before or during irradiation did not materially alter the radiation response of tumor cells. Maximal potentiation of radiation damage was achieved only when the tumorous mice were subjected to at least 20 minutes heat incubation after irradiation. LD studies on ICR mice revealed that moderate hyperthermia (41.5 degrees C) does not alter the radiation response of normal body tissues. These findings indicate that it is possible to devise hyperthermic treatment regimens that drastically enhance radiation-induced tumor cell death in vivo without reducing the radioresistance of normal tissues.

Effect of elevated temperatures on the radiation sensitivity of yeast cells of different species

“…The synergistic effect of heat and ionizing radiation has been demonstrated mainly using model tumor systems [1,4,10,11], or mammalian cell culture in vitro [2,3,7,16,24]. The synergistic effect of heat and ionizing radiation has been demonstrated mainly using model tumor systems [1,4,10,11], or mammalian cell culture in vitro [2,3,7,16,24].…”

“…It was shown that hypoxic cells appeared to be especially sensitive to radiation when exposed to hyperthermic conditions [ 14]. The sequence of heat and ionizing radiation application was very important [3,11,16,24]. The sequence of heat and ionizing radiation application was very important [3,11,16,24].…”

Estimated number of children with cancer eligible for hyperthermia based on population- and treatment-related criteria

“…Other study groups have focused on treatment strategies with additional HT in childhood cancer. Although some pre-clinical (Cavaliere et al 1967, Hofer et al 1976, Willnow 1981, Moriyama et al 1986, 1993, Rama and Prasad 1986, Koole and Schipper 1990, Page et al 1992, Wiedemann et al 1992 and clinical studies in paediatric oncology (Schipper et al 1987, Otte 1988, Willnow et al 1989, Romanowski et al 1993, Wessalowski et al 1998) disclosed an objective heat-induced response modi® cation of chemotherapy radiotherapy, especially in tumours that failed to respond to standard therapies, various ethical and clinical aspects have to be considered for an appropriate case selection in childhood cancer. The goals which must be addressed in the selection of a patient population which can bene® t from HT must be (a) an improved rate of remissions, (b) a decrease in mutilating surgical procedures, and (c) the avoidance of high-dose radiation, particularily in infants and toddlers.…”

On the Preparation of82Br-Biomolecules. A Direct Bromination via Neutron Irradiated Bromates

“…5-iodo-2'-deoxyuridine is widely used for the labelling of DNA for several purposes [14][15][16] and it might be possible that 5-®^Br-2'-deoxyuridine can find applications in radiation biology (electrons of average energy of 136.8 keV [17] and 90% ränge in water 0.626 mm [18]). …”