title: Improved sensitivity for imaging spin trapped hydroxyl radical at 250 MHz.
abstract: Radicals, including hydroxyl, superoxide, and nitric oxide, play key signaling roles in vivo. Reaction of these free radicals with a spin trap affords more stable paramagnetic nitroxides, but concentrations in vivo still are so low that detection by electron paramagnetic resonance (EPR) is challenging. Three innovative enabling technologies have been combined to substantially improve sensitivity for imaging spin-trapped radicals at 250 MHz. 1) Spin-trapped adducts of BMPO have lifetimes that are long enough to make imaging by EPR at 250 MHz feasible. 2) The signal-to-noise ratio of rapid-scan EPR is substantially higher than for conventional continuous-wave EPR. 3) An improved algorithm permits image reconstruction with a spectral dimension that encompasses the full 50 G spectrum of the BMPO-OH spin adduct without requiring the wide sweeps that would be needed for filtered backprojection. A 2D spectral-spatial image is shown for a phantom containing ca. 5 μM BMPO-OH.
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, 2101 E. Wesley Ave., Denver, Colorado 80208 (USA).
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Biller
authors.forename: Mark
authors.initials: M
authors.lastname: Tseitlin
authors.forename: Deborah G
authors.initials: DG
authors.lastname: Mitchell
authors.forename: Zhelin
authors.initials: Z
authors.lastname: Yu
authors.forename: Laura A
authors.initials: LA
authors.lastname: Buchanan
authors.forename: Hanan
authors.initials: H
authors.lastname: Elajaili
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Rosen
authors.forename: Joseph P Y
authors.initials: JP
authors.lastname: Kao
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Eaton
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Eaton
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000737:chemistry*; D019097:Spin Trapping
chemical_list: C441196:5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide; D003497:Cyclic N-Oxides; D017665:Hydroxyl Radical
keywords: EPR imaging; hydroxyl radicals; image reconstruction; rapid-scan EPR; spin-trapping