astatine and Carcinoma--Ehrlich-Tumor

Determination of the biological effect of the alpha emitter (211)At on cellular level as well as the assessment of dosimetric data in a tumour model in vivo.. Transplantation of malignant ascitic cells in mice intraperitoneally and estimation of tumour characteristics (doubling time of the cells, mean survival of the animals following an i.p. application of a defined tumour cell number). (211)At labelled human serum albumin microspheres B-20 (MSP) of varying activity were injected into tumour bearing mice intraperitoneally. The effectiveness of the therapy was evaluated by means of determination of the duration of cell cycle arrest as well as the microscopic analysis of the rate of abnormal mitotic cells due to radiation induced damage. Furthermore, dose dependence of survival was evaluated.. Three days following the intraperitoneally application of 8 x 10(6) tumour cells, 50-600 kBq (211)At-MSP were applied into the abdominal cavity. Considering the volume of ascites at this time and the administered activity, dose calculations were performed. An activity of 50 kBq caused a dose of 0.84 Gy. The increase of radiation induced effect on ascitic tumour cells was correlated with the dose. Between the duration of the cell cycle arrest and the administered activity, a directly proportional correlation was found. The mean survival of non-treated animals was 16.9 +/- 3.7 days. The prolongation of the survival was proportional to the activity administered. Using a dosage of 10 Gy, five animals out of 16 survived.. Therapy of malignant ascitic cells using (211)At-MSP was effective in vivo. For tumour therapy, the (211)At represents a highly effective alternative to usually applied beta emitters.

Topics: Animals; Astatine; Carcinoma, Ehrlich Tumor; Disease Models, Animal; Dose-Response Relationship, Radiation; Drug Carriers; Female; Male; Mice; Mice, Inbred CBA; Microspheres; Serum Albumin

The biological effect of 211At alpha-particles has been investigated using the Chinese hamster fibroblasts and Ehrlich carcinoma cells growth in vitro. The mean energy of 211At alpha-particles is 6.8 MeV, LET in tissue is 70-160 keV/microns; the half-life period of decomposition of 211At is 7.2 h. The end-points used were a decrease in the mitotic activity, an elevation of the number of degenerating cells, cell with chromosome aberrations and the cell survival. The RBE of alpha-particles in comparison with 60Co gamma-rays is close to 3.

Topics: Alpha Particles; Animals; Astatine; Carcinoma, Ehrlich Tumor; Cricetinae; Cricetulus; Energy Transfer; Fibroblasts; Half-Life; Models, Biological; Radiotherapy, High-Energy; Tumor Cells, Cultured