THE BIOLOGICAL EFFECTS OF AUGER ELECTRONS COMPARED TO ALPHA-PARTICLESAND LI IONS

The present study reports the results of V-79 Chinese hamster cell sur vival studies in which Auger electron emission was stimulated in gadol inium (Gd) after thermal neutron capture, When a porphyrin that had pr eviously been labeled with boron ((BOPP)-B-10) was also labeled with G d (Gd-(BOPP)-B-10), the cells were incubated with Gd-(BOPP)-B-10 to as sess the compound's ability to physiologically transport the Gd into t he cell, and localize the Gd atoms in or near the cell's critical targ et, presumably the DNA. It was anticipated that Auger electron emissio n, stimulated during the Gd-157 (n, gamma) Gd-158 interaction, would i mpart additional high LET damage to that observed from the alpha-parti cle and Li ion during the B-10(n, alpha) Li-7 reaction, Following irra diation with thermal neutrons from the Brookhaven Medical Research Rea ctor, the effectiveness of the Auger electrons was determined by compa ring the response of cells incubated with (BOPP)-B-10, where damage wa s imparted by the boron neutron capture (BNC) products, to that from G d-(BOPP)-B-10, with equal concentration of B-10 in both solutions, An Auger effectiveness factor of similar to 2 was found for the Gd-(BOPP) -B-10 cells, The Auger effectiveness observed with Gd strongly suggest ed that the (BOPP)-B-10 molecule physiologically transported the Gd3ion intracellularly where it probably bound to DNA, Others have report ed that Gd3+ does, in fact, complex with DNA, While depositing less en ergy per interaction than the high LET BNC reaction by-products, Auger electron ionization was more effective.