Marcus Unverricht-Yeboah, Kathrin Holtmann, Ralf Kriehuber
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引用次数: 4
Abstract
Purpose: Ionizing radiation causes various types of DNA damage e.g. single strand breaks (SSB) and double strand breaks (DSB), whereby the SSB/DSB ratio is shifted toward the DSB with increasing LET. For the DNA-incorporated Auger electron emitter Iodine-125 a SSB/DSB ratio of 5.4:1 is calculated based on computer simulations. In the presented work the SSB/DSB ratio of DNA-incorporated Iodine-125 was experimentally determined and compared to external homogenous γ-irradiation.
Materials and methods: Iodine-125-iododeoxyuridine (I-125-UdR) was incorporated into the DNA of SCL-II cells and cells were subsequently frozen for decay accumulation. Accordingly, external γ-irradiation (Cs-137) experiments were performed in frozen cells. After exposure the neutral or alkaline Comet Assay was performed to quantify DSB or DSB and SSB, respectively. Automated quantification of the comets was performed using the Olive Tail Moment (Metafer CometScan; MetaSystems). Calculation of absorbed dose for Auger electrons on cellular level is extremely biased due to the exclusive DNA localization of I-125-UdR. To avoid dose calculation the γ-H2AX assay was used in order to allow the comparison of the Comet Assay data between both investigated radiation qualities.
Results: For low-LET γ-radiation, a SSB/DSB ratio of 10:1 was determined. In contrast, a lower SSB/DSB ratio of 6:1 was induced by DNA-incorporated Iodine-125 which compares very well to the calculated values of Pomplun and co-authors.
Conclusion: DNA-incorporated Iodine-125 induces a high-LET type DNA damage pattern in respect to SSB/DSB ratio.
期刊介绍：
The International Journal of Radiation Biology publishes original papers, reviews, current topic articles, technical notes/reports, and meeting reports on the effects of ionizing, UV and visible radiation, accelerated particles, electromagnetic fields, ultrasound, heat and related modalities. The focus is on the biological effects of such radiations: from radiation chemistry to the spectrum of responses of living organisms and underlying mechanisms, including genetic abnormalities, repair phenomena, cell death, dose modifying agents and tissue responses. Application of basic studies to medical uses of radiation extends the coverage to practical problems such as physical and chemical adjuvants which improve the effectiveness of radiation in cancer therapy. Assessment of the hazards of low doses of radiation is also considered.
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