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Updated: Jul 24, 2026

Immunofluorescent Detection of Two Thymidine Analogues (CldU and IdU) in Primary Tissue
Published on: December 7, 2010
Chemical modification of 5-[125I]iodo-2'-deoxyuridine toxicity in mammalian cells in vitro
M A Walicka1, S J Adelstein, A I Kassis
1Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
Purpose:
To address the cytotoxic effects of DNA-incorporated (125)I in Chinese hamster V79 lung fibroblasts under various scavenging conditions.
Methods:
The toxic effects of DNA-incorporated 5-[(125)I]iodo-2'-deoxyuridine ((125)IdUrd) were assessed by the colony-forming assay with cells incubated in medium containing serum and/or dimethyl sulphoxide (DMSO). Experiments were carried out at 0.3 or -135 degrees C.
Results:
When (125)I decays were accumulated at 0.3 degrees C in 10% serum 0, 5 or 10% DMSO, no radioprotection was afforded by 5% DMSO, while the dose modification factor (DMF) for 10% DMSO was 2.0. For cells accumulating decays at 135 degrees C in the presence of 5 or 10% serum, DMSO was radioprotective (DMF= 1.8-1.9). D(0) obtained at each serum concentration correlated strongly (R=0.999) with the scavenging capacity of DMSO. Under these experimental conditions, 10% serum is approximately 3.6 times more protective than 5% serum.
Conclusions:
The contribution of indirect mechanisms to the toxicity of (125)I decaying within mammalian cell nuclear DNA can be demonstrated not only with DMSO, but also with the hydroxy radical scavengers present in serum.
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