Non-invasive technique to study the efficacy of radiomodifiers

Bone marrow aspiration and biopsy are used for evaluating bone marrow, but the method is invasive and cannot be repeated very frequently in the same individual. Bone marrow imaging using 99mTc-labelled sulphur colloid was used as a non-invasive technique to study the proliferative activity of bone marrow and the efficacy of the various radiomodifiers. The bone marrow imaging was done in rabbits following different treatments i.e. (i) exposed to 4 Gy whole body irradiation, (ii) treated with diltiazem (20 mg/kg b.w., i.p.) followed by 4 Gy exposure and (iii) treated with 2-deoxy-D-glucose (2-DG) (200 mg/kg b.w., i.p.) followed by 4 Gy exposure. In the animals given gamma irradiation alone on 8th and 15th day following irradiation, the bone marrow activity was found to be decreased by 31% and 45% respectively and returned to control level by 7th week; the corresponding decrease in diltiazem treated rabbits was 16% and 9% only. However, in rabbits treated with 2-DG, the bone marrow activity decreased by 8% and 14% on 8th and 15th day respectively. In both drug treated groups, the bone marrow activity returned to control levels by fifth week. Total leukocyte counts (TLC) in the peripheral blood decreased by 85% and 90% on 7th and 14th day respectively in rabbits given gamma irradiation alone. However, in the diltiazem treated rabbits, the decrease in TLC was 62% and 66% in first and second week respectively; the corresponding values were 60% and 72% in 2-DG treated rabbits. It may be concluded that the technique may be used to study the radiation injuries and also the efficacy of the various radiomodifiers. (author)