Radiation research
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To evaluate the function of the reticuloendothelial system and macrophage-monocyte system, blood samples from Thorotrast patients and age-matched healthy controls were used to determine the titer of plasma antibodies to lipid A and the numbers of several lymphocyte subclasses in peripheral blood and for an autoradiographic study of peripheral blood monocytes. The titer of plasma IgM class antibodies to lipid A was significantly elevated in the Thorotrast patients. ⋯ Autoradiography showed that alpha-particle tracks were emitted from the monocytes isolated from the peripheral blood of Thorotrast patients. Thus the depressed function of the reticuloendothelial system resulted in the activation of the macrophage-monocyte system in the Thorotrast patients.
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Human promyelocytic leukemia (HL60) cells were irradiated with 10 or 50 Gy of X rays and studied for up to 72 h postirradiation to determine the mode of death and assess changes in the nuclear matrix. After 50 Gy irradiation, cells were found to die early, primarily by apoptosis, while cells irradiated with 10 Gy died predominantly by necrosis. Disassembly of the nuclear lamina and degradation of the nuclear matrix protein lamin B occurred in cells undergoing radiation-induced apoptosis or necrosis. ⋯ Disassembly of the nuclear lamina during radiation-induced necrosis occurred much later (between 30-60 h after irradiation), and a different cleavage pattern of lamin B was observed. Degradation of the nuclear lamina was also inhibited in apoptosis-resistant BCL2-overexpressing HL60 cells exposed to 50 Gy until approximately 48 h after irradiation. These data indicate that breakdown of the nuclear matrix may be a common element in radiation-induced apoptosis and necrosis, but that the mechanisms and temporal patterns of breakdown of the nuclear lamina during apoptosis are distinct from those of necrosis.