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 Title: The effects of hyperthermia and ionizing radiation on chicken erythrocytes: A possible model for terminally differentiated tissues Author(s): Lee, Susan Wei Shenn Doctoral Committee Chair(s): Ducoff, Howard S. Department / Program: Physiology Discipline: Physiology Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Biology, Cell Biology, Animal Physiology Health Sciences, Radiology Abstract: The objective of this study was to investigate effects of hyperthermia and ionizing radiation on terminally-differentiated tissues. Chicken red blood cells (RBC's), which are nucleated and have limited genetic activity, were used as the model. "Spontaneous" hemolysis in isotonic-glucose medium was used to score the effects of heat and/or radiation on chicken RBC's. Heat damage was also measured by potassium leakage and by osmotic fragility.Virtually no hemolysis occurred immediately after heating; 1-2 days were required for significant hemolysis to develop. Hemolysis increased with heating temperature and duration. Heat shock of 30-90 minutes at 42.6$\sp\circ$C just before heat challenge of 40 minutes at 51.5$\sp\circ$C or heat shock of 15 minutes at 43.1$\sp\circ$C with 0-2 hour incubation at 35$\sp\circ$C prior to the same challenge induced thermotolerance, but the levels of heat resistance achieved were different. Similar experiments were performed using potassium leakage as the endpoint. Leakage was measurable immediately after heating; it increased with heating duration. There was no correlation between leakage and hemolysis. Potassium leakage was not suitable for studying thermotolerance. An inverse relationship between osmotic fragility and temperature (4$\sp\circ$-40$\sp\circ$C) was observed, but at 51.5$\sp\circ$C osmotic fragility returned to the 22$\sp\circ$C level. Thermotolerance was observed but it was not stable.Chicken RBC's exposed to 0-100 Gy at a dose rate of 10 Gy/minute hemolyzed in a dose-dependent manner when scored 1-3 days after irradiation. A threshold of at least 35 Gy was observed. Split-dose experiments showed that chicken RBC's were able to repair radiation damage; the half time for maximum recovery was 28.6 minutes at 35$\sp\circ$C. Recovery from $\gamma$ radiation was affected by the interfraction temperature since incubation at 35$\sp\circ$C achieved greater recovery than at 22$\sp\circ$C.The combination of hyperthermia and radiation produced more hemolysis than either heat or radiation alone. Postirradiation heating was the only protocol that caused prompt hemolysis and it also induced the greatest amount of hemolysis. The amount of hemolysis induced by preirradiation heating was very similar to that of heat alone. Additional hemolysis at 24-48 hours after treatment was similar for all heated groups regardless of radiation exposure. Less prompt hemolysis was recorded when irradiated RBC's were incubated for 2-24 hours prior to heat treatment. Issue Date: 1991 Type: Text Language: English URI: http://hdl.handle.net/2142/23185 Rights Information: Copyright 1991 Lee, Susan Wei Shenn Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9210888 OCLC Identifier: (UMI)AAI9210888
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