polonium and Precancerous-Conditions

Rat tracheal epithelial cells exhibited exponential cell killing when exposed to 210Po alpha particles as single cell suspensions or in the intact tissue. Survival of cells in the intact tissue was not significantly different from that observed with cell suspensions. Comparison of survival of cells exposed in suspension to 300 kVpX rays yielded an RBE of 6.3. Measurements of basal cell nuclei were used to determine that a single traversal of a cell nucleus had a high probability of causing cell inactivation. This was also observed in mink lung cells and CHO cells exposed in an identical manner. There were no significant increases in frequencies of preneoplastic transformation observed for a range of exposures (0.0007 to 0.05 alpha particles/micron2). Examination of intact tracheal transplants which were irradiated with alpha particles also failed to reveal any preneoplastic or neoplastic changes.

Topics: Alpha Particles; Animals; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Cells, Cultured; CHO Cells; Cricetinae; Epithelium; Male; Neoplasms, Radiation-Induced; Polonium; Precancerous Conditions; Rats; Rats, Inbred F344; Suspensions; Trachea; Tracheal Neoplasms

The pathogenesis of 210Po-induced tumors in the peripheral lung of Syrian golden hamsters has been studied in a serial sacrifice experiment utilizing both plastic (glycol methacrylate) and routine paraffin embedding procedures for lung sections. A rapid progression from hyperplasia of bronchiolar-type cells that appear in the alveolar region to malignant tumors was documented. Tumors began appearing as early as 15 weeks after the first intratracheal instillation of 210Po.

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Cricetinae; Hyperplasia; Lung Neoplasms; Male; Mesocricetus; Neoplasms, Experimental; Neoplasms, Radiation-Induced; Polonium; Precancerous Conditions; Time Factors