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Biller JR, McPeak JE. EPR Everywhere. APPLIED MAGNETIC RESONANCE 2021; 52:1113-1139. [PMID: 33519097 PMCID: PMC7826499 DOI: 10.1007/s00723-020-01304-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/16/2020] [Accepted: 12/06/2020] [Indexed: 06/12/2023]
Abstract
This review is inspired by the contributions from the University of Denver group to low-field EPR, in honor of Professor Gareth Eaton's 80th birthday. The goal is to capture the spirit of innovation behind the body of work, especially as it pertains to development of new EPR techniques. The spirit of the DU EPR laboratory is one that never sought to limit what an EPR experiment could be, or how it could be applied. The most well-known example of this is the development and recent commercialization of rapid-scan EPR. Both of the Eatons have made it a point to remain knowledgeable on the newest developments in electronics and instrument design. To that end, our review touches on the use of miniaturized electronics and applications of single-board spectrometers based on software-defined radio (SDR) implementations and single-chip voltage-controlled oscillator (VCO) arrays. We also highlight several non-traditional approaches to the EPR experiment such as an EPR spectrometer with a "wand" form factor for analysis of the OxyChip, the EPR-MOUSE which enables non-destructive in situ analysis of many non-conforming samples, and interferometric EPR and frequency swept EPR as alternatives to classical high Q resonant structures.
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Affiliation(s)
| | - Joseph E. McPeak
- University of Denver, Denver, CO 80210 USA
- Berlin Joint EPR Laboratory and EPR4Energy, Department Spins in Energy Conversion and Quantum Information Science (ASPINS), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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2
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Development of multifunctional Overhauser-enhanced magnetic resonance imaging for concurrent in vivo mapping of tumor interstitial oxygenation, acidosis and inorganic phosphate concentration. Sci Rep 2019; 9:12093. [PMID: 31431629 PMCID: PMC6702349 DOI: 10.1038/s41598-019-48524-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 08/07/2019] [Indexed: 12/18/2022] Open
Abstract
Tumor oxygenation (pO2), acidosis (pH) and interstitial inorganic phosphate concentration (Pi) are important parameters of the malignant behavior of cancer. A noninvasive procedure that enables visualization of these parameters may provide unique information about mechanisms of tumor pathophysiology and provide clues to new treatment targets. In this research, we present a multiparametric imaging method allowing for concurrent mapping of pH, spin probe concentration, pO2, and Pi using a single contrast agent and Overhauser-enhanced magnetic resonance imaging technique. The developed approach was applied to concurrent multifunctional imaging in phantom samples and in vivo in a mouse model of breast cancer. Tumor tissues showed higher heterogeneity of the distributions of the parameters compared with normal mammary gland and demonstrated the areas of significant acidosis, hypoxia, and elevated Pi content.
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3
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Jugniot N, Duttagupta I, Rivot A, Massot P, Cardiet C, Pizzoccaro A, Jean M, Vanthuyne N, Franconi JM, Voisin P, Devouassoux G, Parzy E, Thiaudiere E, Marque SRA, Bentaher A, Audran G, Mellet P. An elastase activity reporter for Electronic Paramagnetic Resonance (EPR) and Overhauser-enhanced Magnetic Resonance Imaging (OMRI) as a line-shifting nitroxide. Free Radic Biol Med 2018; 126:101-112. [PMID: 30092349 DOI: 10.1016/j.freeradbiomed.2018.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 12/19/2022]
Abstract
Pulmonary inflammatory diseases are a major burden worldwide. They have in common an influx of neutrophils. Neutrophils secrete unchecked proteases at inflammation sites consequently leading to a protease/inhibitor imbalance. Among these proteases, neutrophil elastase is responsible for the degradation of the lung structure via elastin fragmentation. Therefore, monitoring the protease/inhibitor status in lungs non-invasively would be an important diagnostic tool. Herein we present the synthesis of a MeO-Suc-(Ala)2-Pro-Val-nitroxide, a line-shifting elastase activity probe suitable for Electron Paramagnetic Resonance spectroscopy (EPR) and Overhauser-enhanced Magnetic Resonance Imaging (OMRI). It is a fast and sensitive neutrophil elastase substrate with Km = 15 ± 2.9 µM, kcat/Km = 930,000 s-1 M-1 and Km = 25 ± 5.4 µM, kcat/Km = 640,000 s-1 M-1 for the R and S isomers, respectively. These properties are suitable to detect accurately concentrations of neutrophil elastase as low as 1 nM. The substrate was assessed with broncho-alveolar lavages samples derived from a mouse model of Pseudomonas pneumonia. Using EPR spectroscopy we observed a clear-cut difference between wild type animals and animals deficient in neutrophil elastase or deprived of neutrophil Elastase, Cathepsin G and Proteinase 3 or non-infected animals. These results provide new preclinical ex vivo and in vivo diagnostic methods. They can lead to clinical methods to promote in time lung protection.
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Affiliation(s)
- Natacha Jugniot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Indranil Duttagupta
- Aix Marseille Univ., CNRS, ICR, UMR 7273, case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France
| | - Angélique Rivot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Philippe Massot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Colleen Cardiet
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Anne Pizzoccaro
- Equipe "Inflammation et Immunité de l'Epithélium Respiratoire" - EA7426 Faculté de Médecine Lyon Sud, 165, Chemin du Grand Revoyet, 69495 Pierre Bénite, France
| | - Marion Jean
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Nicolas Vanthuyne
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Jean-Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Pierre Voisin
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Gilles Devouassoux
- Equipe "Inflammation et Immunité de l'Epithélium Respiratoire" - EA7426 Faculté de Médecine Lyon Sud, 165, Chemin du Grand Revoyet, 69495 Pierre Bénite, France
| | - Elodie Parzy
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France
| | - Eric Thiaudiere
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France.
| | - Sylvain R A Marque
- Aix Marseille Univ., CNRS, ICR, UMR 7273, case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France; Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, Pr. Lavrentjeva 9, 630090 Novosibirsk, Russia.
| | - Abderrazzak Bentaher
- Equipe "Inflammation et Immunité de l'Epithélium Respiratoire" - EA7426 Faculté de Médecine Lyon Sud, 165, Chemin du Grand Revoyet, 69495 Pierre Bénite, France.
| | - Gérard Audran
- Aix Marseille Univ., CNRS, ICR, UMR 7273, case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France.
| | - Philippe Mellet
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS, Université de Bordeaux, F-33076 Bordeaux, France; INSERM, 33076 Bordeaux Cedex, France.
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Duttagupta I, Jugniot N, Audran G, Franconi JM, Marque SRA, Massot P, Mellet P, Parzy E, Thiaudière E, Vanthuyne N. Selective On/Off-Nitroxides as Radical Probes to Investigate Non-radical Enzymatic Activity by Electron Paramagnetic Resonance. Chemistry 2018; 24:7615-7619. [PMID: 29722459 DOI: 10.1002/chem.201800866] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Indexed: 12/13/2022]
Abstract
A nitroxide carrying a peptide specific to the binding pocket of the serine proteases chymotrypsin and cathepsin G is prepared. This peptide is attached as an enol ester to the nitroxide. Upon enzymatic hydrolysis of the peptide, the enol ester moiety is transformed into a ketone moiety. This transformation affords a difference of 5 G in phosphorus hyperfine coupling constant between the electronic paramagnetic resonance (EPR) signals of each nitroxide. This property is used to monitor the enzymatic activity of chymotrypsin and cathepsin G by EPR. Michaelis constants were determined and match those reported for conventional optical probes.
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Affiliation(s)
- Indranil Duttagupta
- Aix Marseille Univ, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France
| | - Natacha Jugniot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France
| | - Gérard Audran
- Aix Marseille Univ, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France
| | - Jean-Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France
| | - Sylvain R A Marque
- Aix Marseille Univ, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France.,N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Pr. Laurentjeva 9, Novosibirsk, 630090, Russia
| | - Philippe Massot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France
| | - Philippe Mellet
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France.,INSERM, 33076, Bordeaux Cedex, France
| | - Elodie Parzy
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France
| | - Eric Thiaudière
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076, Bordeaux Cedex, France
| | - Nicolas Vanthuyne
- Aix Marseille Univ., CNRS, ISM2, UMR 7313, Avenue Escadrille Normandie-Niemen, 13397, Marseille Cedex 20, France
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Kishimoto S, Krishna MC, Khramtsov VV, Utsumi H, Lurie DJ. In Vivo Application of Proton-Electron Double-Resonance Imaging. Antioxid Redox Signal 2018; 28:1345-1364. [PMID: 28990406 PMCID: PMC5910041 DOI: 10.1089/ars.2017.7341] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 10/05/2017] [Indexed: 01/01/2023]
Abstract
SIGNIFICANCE Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO2), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH+ forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. CRITICAL ISSUES High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. FUTURE DIRECTIONS PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345-1364.
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Affiliation(s)
- Shun Kishimoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Murali C. Krishna
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Valery V. Khramtsov
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia
- Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia
| | - Hideo Utsumi
- School of Pharmaceutical Sciences, The University of Shizuoka, Shizuoka, Japan
| | - David J. Lurie
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
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Khramtsov VV, Bobko AA, Tseytlin M, Driesschaert B. Exchange Phenomena in the Electron Paramagnetic Resonance Spectra of the Nitroxyl and Trityl Radicals: Multifunctional Spectroscopy and Imaging of Local Chemical Microenvironment. Anal Chem 2017; 89:4758-4771. [PMID: 28363027 PMCID: PMC5513151 DOI: 10.1021/acs.analchem.6b03796] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This Feature overviews the basic principles of using stable organic radicals involved in reversible exchange processes as functional paramagnetic probes. We demonstrate that these probes in combination with electron paramagnetic resonance (EPR)-based spectroscopy and imaging techniques provide analytical tools for quantitative mapping of critical parameters of local chemical microenvironment. The Feature is written to be understandable to people who are laymen to the EPR field in anticipation of future progress and broad application of these tools in biological systems, especially in vivo, over the next years.
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Affiliation(s)
- Valery V. Khramtsov
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Andrey A. Bobko
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Mark Tseytlin
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Benoit Driesschaert
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
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Eto H, Hyodo F, Nakano K, Utsumi H. Selective Imaging of Malignant Ascites in a Mouse Model of Peritoneal Metastasis Using in Vivo Dynamic Nuclear Polarization-Magnetic Resonance Imaging. Anal Chem 2016; 88:2021-7. [PMID: 26796949 DOI: 10.1021/acs.analchem.5b04821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The presence of malignant ascites in advanced cancer patients is associated with both a poor prognosis and quality of life with a risk of abdominal infection and sepsis. Contemporary noninvasive visualization methods such as ultrasound, computed tomography, and magnetic resonance imaging (MRI) often struggle to differentiate malignant ascites from surrounding tissues. This study aimed to determine the utility of selective H2O imaging in the abdominal cavity with a free radical probe and deuterium oxide (D2O) contrast agent using in vivo dynamic nuclear polarization-MRI (DNP-MRI). Phantom imaging experiments established a linear relationship between H2O volume and image intensity using in vivo DNP-MRI. Similar results were obtained when the radical-D2O probe was used to determine selective and spatial information on H2O in vivo, modeled by the injection of saline into the abdominal cavity of mice. To demonstrate the utility of this method for disease, malignant ascites in peritoneal metastasis animal model was selected as one of the typical examples. In vivo DNP-MRI of peritoneal metastasis animal model was performed 7-21 days after intraperitoneal injection of luciferase, stably expressing the human pancreatic carcinoma (SUIT-2). The image intensity with increasing malignant ascites was significantly increased at days 7, 16, and 21. This increase corresponded to in vivo tumor progression, as measured by bioluminescent imaging. These results suggest that H2O signal enhancement in DNP-MRI using radical-D2O contrast is positively associated with the progression of dissemination and could be a useful biomarker for malignant ascites with cancer metastasis.
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Affiliation(s)
- Hinako Eto
- Innovation Center for Medical Redox Navigation, Kyushu University , 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Fuminori Hyodo
- Innovation Center for Medical Redox Navigation, Kyushu University , 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kenji Nakano
- Innovation Center for Medical Redox Navigation, Kyushu University , 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hideo Utsumi
- Innovation Center for Medical Redox Navigation, Kyushu University , 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Audran G, Bosco L, Brémond P, Franconi J, Koonjoo N, Marque SRA, Massot P, Mellet P, Parzy E, Thiaudière E. Enzymatically Shifting Nitroxides for EPR Spectroscopy and Overhauser‐Enhanced Magnetic Resonance Imaging. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Gérard Audran
- Aix‐Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie‐Niemen, 13397 Marseille Cedex 20 (France)
| | - Lionel Bosco
- Aix‐Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie‐Niemen, 13397 Marseille Cedex 20 (France)
| | - Paul Brémond
- Aix‐Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie‐Niemen, 13397 Marseille Cedex 20 (France)
| | - Jean‐Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Neha Koonjoo
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Sylvain R. A. Marque
- Aix‐Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie‐Niemen, 13397 Marseille Cedex 20 (France)
| | - Philippe Massot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Philippe Mellet
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
- INSERM, 33076 Bordeaux Cedex (France)
| | - Elodie Parzy
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Eric Thiaudière
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
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Audran G, Bosco L, Brémond P, Franconi JM, Koonjoo N, Marque SRA, Massot P, Mellet P, Parzy E, Thiaudière E. Enzymatically Shifting Nitroxides for EPR Spectroscopy and Overhauser-Enhanced Magnetic Resonance Imaging. Angew Chem Int Ed Engl 2015; 54:13379-84. [PMID: 26376730 DOI: 10.1002/anie.201506267] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Indexed: 11/12/2022]
Abstract
In vivo investigations of enzymatic processes using non-invasive approaches are a long-lasting challenge. Recently, we showed that Overhauser-enhanced MRI is suitable to such a purpose. A β-phosphorylated nitroxide substrate prototype exhibiting keto-enol equilibrium upon enzymatic activity has been prepared. Upon enzymatic hydrolysis, a large variation of the phosphorus hyperfine coupling constant (Δa(P)=4 G) was observed. The enzymatic activities of several enzymes were conveniently monitored by electronic paramagnetic resonance (EPR). Using a 0.2 T MRI machine, in vitro and in vivo OMRI experiments were successfully performed, affording a 1200% enhanced MRI signal in vitro, and a 600% enhanced signal in vivo. These results highlight the enhanced imaging potential of these nitroxides upon specific enzymatic substrate-to-product conversion.
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Affiliation(s)
- Gérard Audran
- Aix-Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20 (France).
| | - Lionel Bosco
- Aix-Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20 (France)
| | - Paul Brémond
- Aix-Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20 (France).
| | - Jean-Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France).
| | - Neha Koonjoo
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Sylvain R A Marque
- Aix-Marseille Université, CNRS, ICR, UMR 7273, Case 551, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20 (France).
| | - Philippe Massot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Philippe Mellet
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France). .,INSERM, 33076 Bordeaux Cedex (France).
| | - Elodie Parzy
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France)
| | - Eric Thiaudière
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS, Case 93, University Bordeaux Segalen, 146 rue Leo Saignat, 33076 Bordeaux Cedex (France).
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