| Abstract: |
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was measured in two C6 glioma cell lines (C6(m) and C6(a)) with different growth characteristics. Animals with intracerebral (i.c.) C6(a) tumors had a mean survival of 16 days, whereas only 1 of 20 animals with i.c. C6(m) tumors died during an 8-wk period of observation. The growth of i.c. C6(m) tumors could be described by the Gompertz equation; tumor doubling time increased from 1.9 to 5.2 days between Days 8 and 16 after tumor inoculation. Corresponding measurements of 131I-IUdR uptake and retention (24 hr after IUdR administration) by i.c. C6(m) tumors were also time-dependent and decreased from 0.075 to 0.027 to 0.011 %dose/g in 8-, 10- and 16-day-old tumors, respectively. Iodine-131-IUdR uptake in 'rapidly growing' i.c. C6(a) tumors was substantially higher (0.30 %dose/g at 24 hr) than that in 'slowly growing' i.c. C6(m) tumors and corresponded with differences in the survival data. Subcutaneous C6(a) tumors had comparable high uptake values (0.49 %dose/g at 24 hr), and 93% of total tumor radioactivity was recovered in DNA 24 hr after IUdR administration. Clearance of radioactivity was rapid in nonproliferative tissues; more than 80% of plasma radioactivity was cleared in 24 hr. Tumor-to-cortex radioactivity ratios ranged from 100/1 to 120/1 and 150/1 between 24, 48 and 96 hr after IUdR injection respectively. A 'washout strategy,' which reduces tissue background activity and increases specificity for PET and SPECT imaging of IUdR-DNA incorporation, is possible with longer- lived radioisotopes of iodine. |
| Keywords: |
survival; nonhuman; comparative study; positron emission tomography; brain tumor; glioma; brain neoplasms; animal cell; animal; animal experiment; animal model; tumor cells, cultured; iodine 131; drug retention; drug uptake; iodine radioisotopes; glioma cell; rat; radioactivity; rats; tumor growth; single photon emission computer tomography; rats, wistar; tomography, emission-computed; tomography, emission-computed, single-photon; drug dna binding; cell dna; clearance; idoxuridine; male; priority journal; article; support, u.s. gov't, non-p.h.s.; rats, inbred wf
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