This proposal is focused on the mechanism of the tissue injury caused by exposure to the herbicide, paraquat. Because of its inherent chemical stability, paraquat may pose a serious problem in the environment, as a consequence of its accumulation in soil and crops. Subsequently, it may enter into the water supply and food chain and eventually into the human body. Paraquat in vivo undergoes an enzyme-catalyzed cyclic one-electron reduction and reoxidation which results in the formation of superoxide radicals. Tissue injury caused by paraquat is believed to be associated with molecular oxygen production. The molecular oxygen-induced tissue injury had been often observed to be greatly enhanced by traces of transition metals. An obligatory role for traces of Cu and Fe in the mediation of tissue injury caused by paraquat has been recently demonstrated in a bacterial model and in mice. The experiments proposed in this application are designed to a) determine the degree of correlation between the dose of paraquat, the cellular level of transition metals, and the observed intensity of in vivo production of free radicals, and b) determine the degree of correlation between the dose of paraquat, the cellular level of transition metals, and the observed severity of injury to the organism. An evaluation of the results of studies described in a) and b) should provide insights into the relationship between the level of in vivo free radical production and the degree of biological damage. The dose of paraquat will be varied and the cellular level of transition metals will be manipulated in order to determine how these parameter affect both free radical production and cellular injury. Two biological models will be used: E. coli and mice. In studying each model we will employ three recently developed methods for monitoring the in vivo production of free radicals: 1) HPLC combined with electrochemical detection (HPLC-ECD) of 8-OH-2-deoxyguanosine in DNA, as a measure of .OH attack on chromosomes and subsequent damage to DNA structure, 2) HPLC-EDC analyses of the conversion of salicylate into dihydroxybenzoate as a reporter of the production of .OH radicals in the cytoplasm of cells, and 3) electron paramagnetic resonance (EPR) determination of spin adducts formed from a variety of oxygen- and carbon-centered free radicals as a measure of free radical production in cell membranes. This proposal offers a unique approach for critical evaluation of the role of free radicals in tissue injury in vivo.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES004296-03
Application #
3252354
Study Section
Toxicology Study Section (TOX)
Project Start
1987-05-01
Project End
1991-04-30
Budget Start
1989-05-01
Budget End
1991-04-30
Support Year
3
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Oklahoma Medical Research Foundation
Department
Type
DUNS #
937727907
City
Oklahoma City
State
OK
Country
United States
Zip Code
73104
Floyd, Robert A (2009) Serendipitous findings while researching oxygen free radicals. Free Radic Biol Med 46:1004-13
Gutteridge, J M; Cao, W; Chevion, M (1991) Bleomycin-detectable iron in brain tissue. Free Radic Res Commun 11:317-20
Har-El, R; Chevion, M (1991) Zinc(II) protects against metal-mediated free radical induced damage: studies on single and double-strand DNA breakage. Free Radic Res Commun 12-13 Pt 2:509-15
Chevion, M (1991) Protection against free radical-induced and transition metal-mediated damage: the use of ""pull"" and ""push"" mechanisms. Free Radic Res Commun 12-13 Pt 2:691-6
Zer, H; Freedman, J H; Peisach, J et al. (1991) Inverse correlation between resistance towards copper and towards the redox-cycling compound paraquat: a study in copper-tolerant hepatocytes in tissue culture. Free Radic Biol Med 11:9-16
Chevion, M; Korbashi, P; Katzhandler, J et al. (1990) Zinc--a redox-inactive metal provides a novel approach for protection against metal-mediated free radical induced injury: study of paraquat toxicity in E. coli. Adv Exp Med Biol 264:217-22
Floyd, R A (1990) Role of oxygen free radicals in carcinogenesis and brain ischemia. FASEB J 4:2587-97
Gutteridge, J M; Nagy, I; Maidt, L et al. (1990) ADP-iron as a Fenton reactant: radical reactions detected by spin trapping, hydrogen abstraction, and aromatic hydroxylation. Arch Biochem Biophys 277:422-8
Floyd, R A; West, M S; Eneff, K L et al. (1990) Conditions influencing yield and analysis of 8-hydroxy-2'-deoxyguanosine in oxidatively damaged DNA. Anal Biochem 188:155-8
Floyd, R A (1990) The development of a sensitive analysis for 8-hydroxy-2'-deoxyguanosine. Free Radic Res Commun 8:139-41

Showing the most recent 10 out of 15 publications