These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Rationale of 5-(125)I-iodo-4'-thio-2'-deoxyuridine as a potential iodinated proliferation marker.
    Author: Toyohara J, Hayashi A, Sato M, Tanaka H, Haraguchi K, Yoshimura Y, Yonekura Y, Fujibayashi Y.
    Journal: J Nucl Med; 2002 Sep; 43(9):1218-26. PubMed ID: 12215562.
    Abstract:
    UNLABELLED: The aim of this investigation was to synthesize and test a novel metabolically stable iodinated nucleoside as a proliferation-imaging agent for SPECT. METHODS: 5-Iodo-4'-thio-2'-deoxyuridine (ITdU) and 5-iodo-1-(4-thio-beta-D-arabinofuranosyl)uracil (ITAU) were tested. The radiolabeling of ITdU and ITAU with (125)I was achieved by a destannylation reaction of the trimethylstannyl precursor of each nucleoside. The products were isolated in high yields and with >99% radiochemical purities. RESULTS: (125)I-ITdU was effectively phosphorylated by cytosolic nucleoside kinases and specifically incorporated into a thymidine kinase-expressing L-M cell rather than a thymidine kinase-deficient mutant L-M (TK(-)) cell. In addition, an in vitro cell metabolism study of (125)I-ITdU clarified that (125)I-ITdU was effectively and specifically incorporated into a DNA fraction (>90% at 60 min). Therefore, (125)I-ITdU was proven to be an ideal DNA synthesis marker such as 5-(125)I-iodo-2'-deoxyuridine (IUdR). In contrast, (125)I-ITAU was neither remarkably phosphorylated by cytosolic nucleoside kinases nor notably incorporated into an L-M cell rather than an L-M (TK(-)) cell. (125)I-ITdU and (125)I-ITAU showed a higher resistance to phosphorolytic cleavage by recombinant thymidine phosphorylase than did (125)I-IUdR. Furthermore, biodistribution of (125)I-ITdU and (125)I-ITAU revealed better in vivo stability of radioiodination than that of (125)I-IUdR. (125)I-ITdU also displayed a significantly higher uptake in proliferating organs (thymus, spleen, small intestine, and bone) than in nonproliferating organs (brain, muscle, liver, and lung), as did (125)I-IUdR, at 18 h after injection. As indicated by the in vitro study, (125)I-ITAU did not show any significant uptake in proliferating organs. CONCLUSION: Radioiodine-labeled ITdU is potentially useful as a proliferation-imaging agent, and further studies should clarify the usefulness of this compound as a tumor-imaging agent.
    [Abstract] [Full Text] [Related] [New Search]