IONIZING RADIATION DISRUPTS CELLULAR ACTIVITIES BY CHEMICALLY DAMAGING PROTEIN AND DEOXYRIBONUCLEIC ACID (DNA) MOLECULES.

IONIZING RADIATION DISRUPTS CELLULAR ACTIVITIES BY CHEMICALLY DAMAGING PROTEIN AND DEOXYRIBONUCLEIC ACID (DNA) MOLECULES. ONE OF THE ABUNDANTLY FORMED CHEMICAL MODIFICATIONS OF DNA IS THYMIDINE DIOL (TD), FORMED BY THE ADDITION OF HYDROXYL RADICALS TO THYMIDINE. THE OBJECTIVE OF THIS PHASE I RESEARCH IS TO DEVELOP A MOLECULAR RADIATION DOSIMETER WHICH DIRECTLY MEASURES LOW-LEVEL RADIATION DAMAGE TO THE DNA OF EXPOSED TISSUES. THIS INTRACELLULAR MOLECULAR DOSIMETER WILL BE USED IN PHASE II TO EVALUATE THE EFFICACY OF RADIOPROTECTIVE DRUGS IN PREVENTING RADIATION INDUCED DAMAGE TO DNA. 60CO-GAMMA IRRADIATED DNA WILL BE ENZYMATICALLY HYDROLYSED TO NUCLEOSIDES. THE THYMIDINE DIOL WILL BE ISOLATED ON A HIGH-PERFORMANCE AFFINITY CHROMATOGRAPHY COLUMN. TO DETECT THIS MOLECULE, IT WILL BE DERIVATISED WITH FLUORESCEIN ISOTHIOCYANATE. THE RESULTING 5-THIOURETHANE WILL BE CHROMATOGRAPHICALLY ISOLATED FROM OTHER SUBSTANCES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND DETECTED BY FLUOROMETRY. THE SENSITIVITY OF THIS ASSAY IS EXPECTED TO DETECT ONE TD PER MILLION BASE PAIRS OF DNA.