The overall objective of this research is to provide quantitative information on the yield, variety and fate of ionizing radiation- induced DNA base damage in cells and in DNA models in vitro. Cell models are selected from strains of Escherichia coli and related procaryotes that have genetically characterized mutations in genes specific for various DNA repair enzymes. Selected Strains include cells deficient in excision repair (e.g., uvrABC mutants); inducible repair (e.g., lexA, recA); exonucleosidic processing (recBC., xth, etc.) and other pertinent repair pathways. In this phase of our long range research, we will add studies on radiation- induced base damage in cells that are deficient in catalase (katEFG) and/or superoxide dismutase enzymes (sodAB). These studies will aid in determining the effects of the molecular radiolysis products, O2- and H2O2, on cellular DNA damage without exogenous chemical modifiers such as H2O2 or paraquat. Procedures for the measurement of DNA base damage in cells and in model DNA that have been developed in previous years include chromatography, radiolabeling, and monoclonal antibody assays, chromatography procedures include multiproduct HPLC assays of DNA nucleoside or base hydrolysates using both UV and radioactive flow detection. Monoclonal antibody assays include recently-developed ELISA procedures to measure thymine glycol and dihydrothymine in cellular DNA isolates. These procedures will be used in (ongoing) studies on thymine base damage and in future studies on purine and cytosine damage. Since most of the initial yield of chemical DNA damage is cells is formed and the yields by cellular repair or exogenous chemicals. Research providing insight into these mechanisms will benefit our understanding of radiation cell killing and mutagenesis.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
7R01CA043324-06
Application #
3185541
Study Section
Radiation Study Section (RAD)
Project Start
1985-11-01
Project End
1992-03-31
Budget Start
1990-08-01
Budget End
1991-03-31
Support Year
6
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Type
Schools of Public Health
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Claycamp, H G; Luo, D (1994) Plutonium-catalyzed oxidative DNA damage in the absence of significant alpha-particle decay. Radiat Res 137:114-7
Claycamp, H G; Huang, H (1993) Zinc deficiency in antibody-conjugated alkaline phosphatase inhibits enzyme activity in ELISAs. Biotechniques 14:348-50
Claycamp, H G; Ho, K K (1993) Background and radiation-induced 8-hydroxy-2'-deoxyguanosine in gamma-irradiated Escherichia coli. Int J Radiat Biol 63:597-607
Huang, H; Claycamp, H G (1993) DNA excision repair as a component of adaptation to low doses of ionizing radiation in Escherichia coli. Int J Radiat Biol 64:613-9
Claycamp, H G (1992) Phenol sensitization of DNA to subsequent oxidative damage in 8-hydroxyguanine assays. Carcinogenesis 13:1289-92
DeRose, C M; Claycamp, H G (1991) Oxidative stress effects on conjugational recombination and mutation in catalase-deficient Escherichia coli. Mutat Res 255:193-200
Claycamp, H G; McCormick, M L; DeRose, C M et al. (1990) Superoxide dismutase and media dependence of far-UV radiation resistance in thiol-treated cells. Int J Radiat Biol 58:449-61
Claycamp, H G; DeRose, C M (1990) The dependence of thiol-inducible radiation resistance in Escherichia coli K12 on the medium and catalytic metal. Radiat Res 124:266-72
Claycamp, H G; Ho, K K; DeRose, C (1990) Thiol and hydrogen peroxide modification of recA induction in UV-irradiated wild-type and catalase-deficient Escherichia coli K12. Mutat Res 235:101-9
DeRose, C; Claycamp, H G (1989) Dimethylformamide-induced changes in the radiation survival of low- and high-passage intestinal epithelial cells (IEC-17) in vitro. Radiat Res 118:269-82

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