Fractionation of combined heat and radiation in asynchronous CHO cells. I. Effects on radiation sensitivity

Journal Article · Thu Nov 01 04:00:00 EST 1979 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3575066· OSTI ID:5686185

Henle, K J; Tomasovic, S P; Dethlefsen, L A

Hyperthermia (10 min at 45/sup 0/C) immediately prior to graded radiation doses (hX) reduced the D/sub 0/ by a factor of 1.4 from that of the radiation-only survival curve (X). However, fractionated treatment consisting of 10 min at 45/sup 0/C + 4 Gy (hx) followed at various times by hX (hx + time + hX) resulted in a D/sub 0/ which increased with longer fractionation intervals and for an interval of 24 h was 1.4 times that of the control heat-radiation survival curve (hX) and thus became similar to the D/sub 0/ of the control radiation survival curve (X). Furthermore, a radiation survival curve 24 h after 10 min at 45/sup 0/C + 4 Gy (hx + 24 + X) showed a D/sub 0/ which was larger than that of the control radiation survival curve (X), but the increase was less (factor of 1.2) than that for the fractionation of hx + 24 + hX relative to hX. The fractionation of radiation alone (x + 24 + X), or a pretreatment by heat alone (h + 24 + X) did not increase significantly the D/sub 0/ of the radiation survival curve over that of the control (X). However, a pretreatment by radiation alone, 24 h before combined heat and radiation (x + 24 + hX), increased the D/sub 0/ also by a factor of 1.4 compared to that of the hX control. However, in contrast to the control radiation survival curve (X) and the fractionation survival curve hx + 24 + hX, the fractionation survival curve x + 24 + hX had no shoulder (n = 1). These results indicate that cell killing by combined heat and radiation in fractionated protocols cannot be predicted from the inactivation kinetics of combined heat and radiation based on single treatments when the fractionation interval is more than one cell-cycle time.

• Research Organization: Univ. of Utah, Salt Lake City
• OSTI ID: 5686185
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 80:2; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY TEMPERATURE
ENERGY
FRACTIONATION
HEAT
HYPERTHERMIA
IRRADIATION
RADIATION EFFECTS
RADIATIONS
RADIOSENSITIVITY
SEPARATION PROCESSES
SYNERGISM
TEMPERATURE EFFECTS