Abstract
The detection of free radicalsin vivo is very important for the study of many physiologic and pathologic conditions. Free radicals have been implicated in a number of diseases such as ischemia, inflammation, kidney damage, and cancer. Proton-electron double-resonance imaging (PEDRI) allows the indirect detection of free radicals via the Overhauser effect. Nitroxide free radicals used forin vivo PEDRI studies present spectra with two or three lines, but most PEDRI experiments performed to date have used only single-line electron paramagnetic resonance (EPR) irradiation. There is theoretical evidence that simultaneous irradiation of multiple EPR transitions could increase the maximum achievable PEDRI enhancement. From the experimental point of view, this requires the combined use of a suitable multiple-frequency EPR source and a multiple-tuned EPR resonator. A novel radiofrequency (RF) triple-tuned loop-gap resonator for use in PEDRI has recently been developed, and dynamic nuclear polarization (DNP) data were reported. In the present study we describe a new PEDRI apparatus, equipped with a triple-tuned resonator, that is suitable for simultaneous double-or triple-EPR irradiation of nitroxide free radicals. In particular, the details of the EPR hardware used to generate the two or three EPR frequencies are given, and PEDRI images obtained with simultaneous multiple EPR irradiation are shown. Moreover, DNP experimental results showing the increase of the enhancement as a function of the EPR power for single and simultaneous double EPR irradiation are presented. The main goal of this apparatus is to improve the sensitivity and/or to reduce EPR irradiation power in a PEDRI experiment. This is likely to be particularly important in future biologic applications of PEDRI where the applied power must be optimized to reduce sample heating.
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References
Eaton GR, Eaton SS, Hono K, Eds. (1991)EPR Imaging and in vivo EPR. Boca Raton: CRC Press.
Hoff AJ, Ed. (1989)Advanced EPR: Application in Biology and Biochemistry. Amsterdam: Elsevier.
Zweier JL, Flaherty JT, Weisfeldt ML (1987) Direct measurement of free-radical generation following reperfusion of ischemic myocardium.Proc Natl Acad Sci USA 84: 1404–1407.
Komarov A, Mattson D, Jones MM,et al. (1993) In vivo spin trapping of nitric oxide in mice.Biochem Biophys Res Commun 195: 1191–1198.
Bacic G, Nigels MJ, Magin RL,et al. (1989) In vivo localized ESR spectroscopy reflecting metabolism.Magn Reson Med 10: 266–272.
Halpern HJ, Bowman MK, Nelson AC,et al. (1989) Imaging radio frequency electron-spin-resonance spectrometer with high resolution and sensitivity forin vivo measurements.Rev Sci Instrum 60: 1040–1050.
Alecci M, Ferrari M, Quaresima V,et al. (1994) Simultaneous 280 MHz EPR imaging of rat organs during nitroxide free radical clearance.Biophys J 67: 1274–1279.
Bourg J, Krishna MC, Mitchell JB,et al. (1993) Radiofrequency FT EPR spectroscopy and imaging.J Magn Reson Series B 102: 112–115.
Lurie DJ, Nicholson I, Foster MA, Mallard JR (1990) Free radicals imaged in vivo in the rat by using proton-electron double-resonance imaging.Philos Trans R Soc Lond 333: 453–456.
Grucker D (1990) In vivo detection of injected free radicals by Overhauser effect imaging.Mag Reson Med 14: 140–147.
Lurie DJ, Nicholson I (1993) Proton-Electron Double-Resonance Imaging of Exogenous and Endogenous FreeRadicals In-Vivo. InProceedings of International School of Physics ‘Enrico Fermi’, Course CXXIII, Nuclear Magnetic Double Resonance. B. Maraviglia, Ed. Amsterdam: North-Holland.
Hausser KH, Stehlik D (1968) Dynamic nuclear polarization in liquids.Adv Magn Reson 3: 79–139.
McCallum SJ, Alecci M, Lurie DJ (1996) Modification of a whole-body NMR imager into a radio frequency EPR spectrometer suitable for in vivo measurements.Meas Sci Technol 7: 1012–1018.
Nicholson I, Lurie DJ, Robb FJ (1994) The application of PEDRI techniques to proton mobility studies.J Magn Reson Series B 104: 250–255.
Abragam A (1961)The Principles of Nuclear Magnetism. Oxford: Oxford University Press.
Nicholson I (1991)Proton Electron Double Resonance Imaging of Free Radicals, PhD Thesis, Aberdeen University.
Trommel J, Epker JH, Leunbach I, Mehlkopf AF (1994) Heisenberg exchange effects in dinamic nuclear polarization imaging.Proceedings: Society of Magnetic Resonance, San Francisco, p. 727.
Alecci M, Nicholson I, Lurie DJ (1996) A novel multiple-tuned radiofrequency loop-gap resonator for use in PEDRI.J Magn Reson Series B 110: 82–86.
Alecci M, Lurie DJ, Nicholson I,et al. (1996) Increasing PEDRI sensitivity with multiple simultaneous EPR irradiation of nitroxide free radicals.Proceedings: International Society of Magnetic Resonance Medicine, New York, p. 1384.
Hutchison JMS, Edelstein WA, Johnson GJ (1980) A whole-body NMR imaging machine.J Phys E Sci Instrum 13: 947–955.
Breit G, Rabi II (1931) Measurement of nuclear spin.Phys Rev. 38: 2082–2083.
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On leave from Instituto Professionale Statale Indostra Artigianato, Pianeta Signorini, 67100-L'Aquila, Italy
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Alecci, M., Lurie, D.J., Nicholson, I. et al. Young investigator award presentation at the 13th annual meeting of the esmrmb, september 1996, prague. MAGMA 4, 187–193 (1996). https://doi.org/10.1007/BF01772006
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DOI: https://doi.org/10.1007/BF01772006