The effects of indium-111 decay on pBR322 DNA
- Harvard Medical School, Boston, MA (United States); and others
We have compared the effectiveness in causing DNA strand breaks of the Auger electron emitter In-111 bound to DNA or free in aqueous solution with that of gamma rays. Supercoiled DNA from pBR322 plasmid labeled with tritiated thymidine was purified and mixed with In-111 chloride in the absence or presence of DTPA, a chelator that prevents binding of indium to DNA. The reaction mixture was stored at 4{degrees}C to accumulate radiation dose from the decay of In-111. The DNA was then resolved by gel electrophoresis into supercoiled (DNA I), nicked circular (DNA II), and linear (DNA III) forms, representing undamaged DNA, single-strand breaks (ssb), and double-strand breaks (dsb), respectively. The Do values of pBR322 DNA exposed to gamma irradiation from external Cs-137 and the decay of In-111 with or without DTPA were 3.21{plus_minus}0.13, 2.73{plus_minus}0.12 and 1.16{plus_minus}0.08 Gy, respectively. In the absence of DTPA, the binding of In-111 to DNA was 14.6%, and the RBE was 12.1{plus_minus}4.7. The increased effectiveness of In-111 appears mainly due to the increased yield of ssb because G(ssb)s of In-111 and Cs-137 (2.87{plus_minus}0.26) x 10E-8 mol/J and (1.08{plus_minus}0.06) x 10E-8 mol/J, respectively, are approximately in the same proportion as their Do values. Differences in dsb yields representing high-LET type damage were inconclusive because of statistical scatter in the results.
- OSTI ID:
- 198029
- Report Number(s):
- CONF-940605--
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 35; ISSN 0161-5505; ISSN JNMEAQ
- Country of Publication:
- United States
- Language:
- English
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