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Shah SA, Reagan CE, Bresticker JE, Wolpe AG, Good ME, Macal EH, Billcheck HO, Bradley LA, French BA, Isakson BE, Wolf MJ, Epstein FH. Obesity-Induced Coronary Microvascular Disease Is Prevented by iNOS Deletion and Reversed by iNOS Inhibition. JACC Basic Transl Sci 2023; 8:501-514. [PMID: 37325396 PMCID: PMC10264569 DOI: 10.1016/j.jacbts.2022.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 02/04/2023]
Abstract
Coronary microvascular disease (CMD) caused by obesity and diabetes is major contributor to heart failure with preserved ejection fraction; however, the mechanisms underlying CMD are not well understood. Using cardiac magnetic resonance applied to mice fed a high-fat, high-sucrose diet as a model of CMD, we elucidated the role of inducible nitric oxide synthase (iNOS) and 1400W, an iNOS antagonist, in CMD. Global iNOS deletion prevented CMD along with the associated oxidative stress and diastolic and subclinical systolic dysfunction. The 1400W treatment reversed established CMD and oxidative stress and preserved systolic/diastolic function in mice fed a high-fat, high-sucrose diet. Thus, iNOS may represent a therapeutic target for CMD.
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Affiliation(s)
- Soham A. Shah
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Claire E. Reagan
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Julia E. Bresticker
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Abigail G. Wolpe
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Miranda E. Good
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Edgar H. Macal
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Helen O. Billcheck
- Department of Cardiovascular Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Leigh A. Bradley
- Department of Cardiovascular Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Brent A. French
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
| | - Brant E. Isakson
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA
| | - Matthew J. Wolf
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
- Department of Cardiovascular Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Frederick H. Epstein
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
- The Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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2
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Rančić A, Babić N, Orio M, Peyrot F. Structural Features Governing the Metabolic Stability of Tetraethyl-Substituted Nitroxides in Rat Liver Microsomes. Antioxidants (Basel) 2023; 12:antiox12020402. [PMID: 36829960 PMCID: PMC9952648 DOI: 10.3390/antiox12020402] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/11/2023] Open
Abstract
Nitroxides are potent tools for studying biological systems by electron paramagnetic resonance (EPR). Whatever the application, a certain stability is necessary for successful detection. Since conventional tetramethyl-substituted cyclic nitroxides have insufficient in vivo stability, efforts have recently been made to synthesize more stable, tetraethyl-substituted nitroxides. In our previous study on piperidine nitroxides, the introduction of steric hindrance around the nitroxide moiety successfully increased the resistance to reduction into hydroxylamine. However, it also rendered the carbon backbone susceptible to modifications by xenobiotic metabolism due to increased lipophilicity. Here, we focus on a new series of three nitroxide candidates with tetraethyl substitution, namely with pyrrolidine, pyrroline, and isoindoline cores, to identify which structural features afford increased stability for future probe design and application in in vivo EPR imaging. In the presence of rat liver microsomes, pyrrolidine and pyrroline tetraethyl nitroxides exhibited a higher stability than isoindoline nitroxide, which was studied in detail by HPLC-HRMS. Multiple metabolites suggest that the aerobic transformation of tetraethyl isoindoline nitroxide is initiated by hydrogen abstraction by P450-FeV = O from one of the ethyl groups, followed by rearrangement and further modifications by cytochrome P450, as supported by DFT calculations. Under anaerobic conditions, only reduction by rat liver microsomes was observed with involvement of P450-FeII.
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Affiliation(s)
- Aleksandra Rančić
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
| | - Nikola Babić
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
| | - Maylis Orio
- iSm2, Aix-Marseille University, CNRS, Centrale Marseille, F-13397 Marseille, France
| | - Fabienne Peyrot
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
- Institut National Supérieur du Professorat et de l’Education (INSPE) de l’Académie de Paris, Sorbonne Université, F-75016 Paris, France
- Correspondence:
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3
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D'Alonzo RA, Gill S, Rowshanfarzad P, Keam S, MacKinnon KM, Cook AM, Ebert MA. In vivo noninvasive preclinical tumor hypoxia imaging methods: a review. Int J Radiat Biol 2021; 97:593-631. [PMID: 33703994 DOI: 10.1080/09553002.2021.1900943] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tumors exhibit areas of decreased oxygenation due to malformed blood vessels. This low oxygen concentration decreases the effectiveness of radiation therapy, and the resulting poor perfusion can prevent drugs from reaching areas of the tumor. Tumor hypoxia is associated with poorer prognosis and disease progression, and is therefore of interest to preclinical researchers. Although there are multiple different ways to measure tumor hypoxia and related factors, there is no standard for quantifying spatial and temporal tumor hypoxia distributions in preclinical research or in the clinic. This review compares imaging methods utilized for the purpose of assessing spatio-temporal patterns of hypoxia in the preclinical setting. Imaging methods provide varying levels of spatial and temporal resolution regarding different aspects of hypoxia, and with varying advantages and disadvantages. The choice of modality requires consideration of the specific experimental model, the nature of the required characterization and the availability of complementary modalities as well as immunohistochemistry.
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Affiliation(s)
- Rebecca A D'Alonzo
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, Australia
| | - Suki Gill
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, Australia.,Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Australia
| | - Pejman Rowshanfarzad
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, Australia
| | - Synat Keam
- School of Medicine, The University of Western Australia, Crawley, Australia
| | - Kelly M MacKinnon
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, Australia
| | - Alistair M Cook
- School of Medicine, The University of Western Australia, Crawley, Australia
| | - Martin A Ebert
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, Australia.,Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Australia.,5D Clinics, Claremont, Australia
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4
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Shah SA, Cui SX, Waters CD, Sano S, Wang Y, Doviak H, Leor J, Walsh K, French BA, Epstein FH. Nitroxide-enhanced MRI of cardiovascular oxidative stress. NMR IN BIOMEDICINE 2020; 33:e4359. [PMID: 32648316 PMCID: PMC7904044 DOI: 10.1002/nbm.4359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 04/08/2020] [Accepted: 06/03/2020] [Indexed: 06/07/2023]
Abstract
BACKGROUND In vivo imaging of oxidative stress can facilitate the understanding and treatment of cardiovascular diseases. We evaluated nitroxide-enhanced MRI with 3-carbamoyl-proxyl (3CP) for the detection of myocardial oxidative stress. METHODS Three mouse models of cardiac oxidative stress were imaged, namely angiotensin II (Ang II) infusion, myocardial infarction (MI), and high-fat high-sucrose (HFHS) diet-induced obesity (DIO). For the Ang II model, mice underwent MRI at baseline and after 7 days of Ang II (n = 8) or saline infusion (n = 8). For the MI model, mice underwent MRI at baseline (n = 10) and at 1 (n = 8), 4 (n = 9), and 21 (n = 8) days after MI. For the HFHS-DIO model, mice underwent MRI at baseline (n = 20) and 18 weeks (n = 13) after diet initiation. The 3CP reduction rate, Kred , computed using a tracer kinetic model, was used as a metric of oxidative stress. Dihydroethidium (DHE) staining of tissue sections was performed on Day 1 after MI. RESULTS For the Ang II model, Kred was higher after 7 days of Ang II versus other groups (p < 0.05). For the MI model, Kred , in the infarct region was significantly elevated on Days 1 and 4 after MI (p < 0.05), whereas Kred in the noninfarcted region did not change after MI. DHE confirmed elevated oxidative stress in the infarct zone on Day 1 after MI. After 18 weeks of HFHS diet, Kred was higher in mice after diet versus baseline (p < 0.05). CONCLUSIONS Nitroxide-enhanced MRI noninvasively quantifies tissue oxidative stress as one component of a multiparametric preclinical MRI examination. These methods may facilitate investigations of oxidative stress in cardiovascular disease and related therapies.
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Affiliation(s)
- Soham A Shah
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Sophia X Cui
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | | | - Soichi Sano
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia, Virginia, USA
| | - Ying Wang
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia, Virginia, USA
| | - Heather Doviak
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia, Virginia, USA
| | - Jonathan Leor
- Neufield Cardiac Research Institute, Sheba Medical Center, Tel-Aviv University, Tel-Hashomer, Ramat Gan, Israel
| | - Kenneth Walsh
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia, Virginia, USA
| | - Brent A French
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Frederick H Epstein
- Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
- Radiology, University of Virginia, Charlottesville, Virginia, USA
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Babić N, Orio M, Peyrot F. Unexpected rapid aerobic transformation of 2,2,6,6-tetraethyl-4-oxo(piperidin-1-yloxyl) radical by cytochrome P450 in the presence of NADPH: Evidence against a simple reduction of the nitroxide moiety to the hydroxylamine. Free Radic Biol Med 2020; 156:144-156. [PMID: 32561320 DOI: 10.1016/j.freeradbiomed.2020.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/29/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022]
Abstract
Aminoxyl radicals (nitroxides) are a class of compounds with important biomedical applications, serving as antioxidants, spin labels for proteins, spin probes of oximetry, pH, or redox status in electron paramagnetic resonance (EPR), or as contrast agents in magnetic resonance imaging (MRI). However, the fast reduction of the radical moiety in common tetramethyl-substituted cyclic nitroxides within cells, yielding diamagnetic hydroxylamines, limits their use in spectroscopic and imaging studies. In vivo half-lives of commonly used tetramethyl-substituted nitroxides span no more than a few minutes. Therefore, synthetic efforts have focused on enhancing the nitroxide stability towards reduction by varying the electronic and steric environment of the radical. Tetraethyl-substitution at alpha position to the aminoxyl function proved efficient in vitro against reduction by ascorbate or cytosolic extracts. Moreover, 2,2,6,6-tetraethyl-4-oxo(piperidin-1-yloxyl) radical (TEEPONE) was used successfully for tridimensional EPR and MRI in vivo imaging of mouse head, with a reported half-life of over 80 min. We decided to investigate the stability of tetraethyl-substituted piperidine nitroxides in the presence of hepatic microsomal fractions, since no detailed study of their "metabolic stability" at the molecular level had been reported despite examples of the use of these nitroxides in vivo. In this context, the rapid aerobic transformation of TEEPONE observed in the presence of rat liver microsomal fractions and NADPH was unexpected. Combining EPR, HPLC-HRMS, and DFT studies on a series of piperidine nitroxides - TEEPONE, 4-oxo-2,2,6,6-tetramethyl(piperidin-1-yloxyl) (TEMPONE), and 2,2,6,6-tetraethyl-4-hydroxy(piperidin-1-yloxyl) (TEEPOL), we propose that the rapid loss in paramagnetic character of TEEPONE is not due to reduction to hydroxylamine but is a consequence of carbon backbone modification initiated by hydrogen radical abstraction in alpha position to the carbonyl by the P450-Fe(V)=O species. Besides, hydrogen radical abstraction by P450 on ethyl substituents, leading to dehydrogenation or hydroxylation products, leaves the aminoxyl function intact but could alter the linewidth of the EPR signal and thus interfere with methods relying on measurement of this parameter (EPR oximetry).
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Affiliation(s)
- Nikola Babić
- Université de Paris, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601, CNRS, F-75006, Paris, France
| | - Maylis Orio
- Aix-Marseille Univ., CNRS, Centrale Marseille, ISm2, Marseille, France
| | - Fabienne Peyrot
- Université de Paris, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601, CNRS, F-75006, Paris, France; Sorbonne Université, Institut National Supérieur Du Professorat et de L'Éducation (INSPE) de L'Académie de Paris, F-75016, Paris, France.
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6
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New synthetic route to 2,2,6,6-tetraethylpiperidin-4-one: A key-intermediate towards tetraethyl nitroxides. Tetrahedron Lett 2019. [DOI: 10.1016/j.tetlet.2019.151207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Effects of Photodynamic Therapy with Redaporfin on Tumor Oxygenation and Blood Flow in a Lung Cancer Mouse Model. Sci Rep 2019; 9:12655. [PMID: 31477749 PMCID: PMC6718604 DOI: 10.1038/s41598-019-49064-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 08/08/2019] [Indexed: 11/24/2022] Open
Abstract
Three photodynamic therapy (PDT) protocols with 15 min, 3 h and 72 h drug-to-light time intervals (DLIs) were performed using a bacteriochlorin named redaporfin, as a photosensitizer. Blood flow and pO2 changes after applying these protocols were investigated in a Lewis lung carcinoma (LLC) mouse model and correlated with long-term tumor responses. In addition, cellular uptake, cytotoxicity and photocytotoxicity of redaporfin in LLC cells were evaluated. Our in vitro tests revealed negligible cytotoxicity, significant cellular uptake, generation of singlet oxygen, superoxide ion and hydroxyl radicals in the cells and changes in the mechanism of cell death as a function of the light dose. Results of in vivo studies showed that treatment focused on vascular destruction (V-PDT) leads to a highly effective long-term antineoplastic response mediated by a strong deprivation of blood supply. Tumors in 67% of the LLC bearing mice treated with V-PDT regressed completely and did not reappear for over 1 year. This significant efficacy can be attributed to photosensitizer (PS) properties as well as distribution and accurate control of oxygen level and density of vessels before and after PDT. V-PDT has a greater potential for success than treatment based on longer DLIs as usually applied in clinical practice.
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8
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Tseytlin O, Guggilapu P, Bobko AA, AlAhmad H, Xu X, Epel B, O'Connell R, Hoblitzell EH, Eubank TD, Khramtsov VV, Driesschaert B, Kazkaz E, Tseytlin M. Modular imaging system: Rapid scan EPR at 800 MHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 305:94-103. [PMID: 31238278 PMCID: PMC6656609 DOI: 10.1016/j.jmr.2019.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 06/05/2023]
Abstract
An electron paramagnetic resonance (EPR) imaging system has been custom built for use in pre-clinical and, potentially, clinical studies. Commercial standalone modules have been used in the design that are MATLAB-controlled. The imaging system combines digital and analog technologies. It was designed to achieve maximum flexibility and versatility and to perform standard and novel user-defined experiments. This design goal is achieved by frequency mixing of an arbitrary waveform generator (AWG) output at the intermediate frequency (IF) with a constant source frequency (SF). Low noise SF at 250, 750, and 1000 MHz are available in the system. A wide range of frequencies from near-baseband to L-band can be generated as a result. Two-stage downconversion at the signal detection side is implemented that enables multi-frequency EPR capability. In the first stage, the signal frequency is converted to IF. A novel AWG-enabled digital auto-frequency control method that operates at IF is described that is used for automatic resonator tuning. Quadrature baseband EPR signal is generated in the second downconversion step. The semi-digital approach of mixing low-noise frequency sources with an AWG permits generation of arbitrary excitation patterns that include but are not limited to frequency sweeps for resonator tuning and matching, continuous-wave, and pulse sequences. Presented in this paper is the demonstration of rapid scan (RS) EPR imaging implemented at 800 MHz. Generation of stable magnetic scan waveforms is critical for the RS method. A digital automatic scan control (DASC) system was developed for sinusoidal magnetic field scans. DASC permits tight control of both amplitude and phase of the scans. A surface loop resonator was developed using 3D printing technology. RS EPR imaging system was validated using sample phantoms. In vivo imaging of a breast cancer mouse model is demonstrated.
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Affiliation(s)
- Oxana Tseytlin
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Priyaankadevi Guggilapu
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Andrey A Bobko
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Hussien AlAhmad
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Industrial & Management Systems Engineering, West Virginia University, Morgantown, WV 26506, USA
| | - Xuan Xu
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Boris Epel
- Center for EPR Imaging In Vivo Physiology, University of Chicago, IL 60637, USA
| | - Ryan O'Connell
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Emily H Hoblitzell
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Microbiology, Immunology & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Timothy D Eubank
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Microbiology, Immunology & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Valery V Khramtsov
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Benoit Driesschaert
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506, USA
| | - Eiad Kazkaz
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Mark Tseytlin
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA.
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Chen NT, Barth ED, Lee TH, Chen CT, Epel B, Halpern HJ, Lo LW. Highly sensitive electron paramagnetic resonance nanoradicals for quantitative intracellular tumor oxymetric images. Int J Nanomedicine 2019; 14:2963-2971. [PMID: 31118615 PMCID: PMC6503311 DOI: 10.2147/ijn.s194779] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/11/2019] [Indexed: 01/25/2023] Open
Abstract
Purpose: Tumor oxygenation is a critical parameter influencing the efficacy of cancer therapy. Low levels of oxygen in solid tumor have been recognized as an indicator of malignant progression and metastasis, as well as poor response to chemo- and radiation therapy. Being able to measure oxygenation for an individual's tumor would provide doctors with a valuable way of identifying optimal treatments for patients. Methods: Electron paramagnetic resonance imaging (EPRI) in combination with an oxygen-measuring paramagnetic probe was performed to measure tumor oxygenation in vivo. Triarylmethyl (trityl) radical exhibits high specificity, sensitivity, and resolution for quantitative measurement of O2 concentration. However, its in vivo applications in previous studies have been limited by the required high dosage, its short half-life, and poor intracellular permeability. To address these limitations, we developed high-capacity nanoformulated radicals that employed fluorescein isothiocyanate-labeled mesoporous silica nanoparticles (FMSNs) as trityl radical carriers. The high surface area nanostructure and easy surface modification of physiochemical properties of FMSNs enable efficient targeted delivery of highly concentrated, nonself-quenched trityl radicals, protected from environmental degradation and dilution. Results: We successfully designed and synthesized a tumor-targeted nanoplatform as a carrier for trityl. In addition, the nanoformulated trityl does not affect oxygen-sensing capacity by a self-relaxation or broadening effect. The FMSN-trityl exhibited high sensitivity/response to oxygen in the partial oxygen pressure range from 0 to 155 mmHg. Furthermore, MSN-trityl displayed outstanding intracellular oxygen mapping in both in vitro and in vivo animal studies. Conclusion: The highly sensitive nanoformulated trityl spin probe can profile intracellular oxygen distributions of tumor in a real-time and quantitative manner using in vivo EPRI.
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Affiliation(s)
- Nai-Tzu Chen
- Institute of New Drug Development, China Medical University, Taichung 40402, Taiwan
| | - Eugene D Barth
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Tsung-Hsi Lee
- Department of Biological Science and Technology, China Medical University, Taichung 40402, Taiwan
| | - Chin-Tu Chen
- Department of Radiology, University of Chicago, Chicago, IL 60637 USA
| | - Boris Epel
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.,Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA
| | - Leu-Wei Lo
- Department of Radiology, University of Chicago, Chicago, IL 60637 USA.,Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan 35053, Taiwan
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10
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Elksnis A, Martinell M, Eriksson O, Espes D. Heterogeneity of Metabolic Defects in Type 2 Diabetes and Its Relation to Reactive Oxygen Species and Alterations in Beta-Cell Mass. Front Physiol 2019; 10:107. [PMID: 30837889 PMCID: PMC6383038 DOI: 10.3389/fphys.2019.00107] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Type 2 diabetes (T2D) is a complex and heterogeneous disease which affects millions of people worldwide. The classification of diabetes is at an interesting turning point and there have been several recent reports on sub-classification of T2D based on phenotypical and metabolic characteristics. An important, and perhaps so far underestimated, factor in the pathophysiology of T2D is the role of oxidative stress and reactive oxygen species (ROS). There are multiple pathways for excessive ROS formation in T2D and in addition, beta-cells have an inherent deficit in the capacity to cope with oxidative stress. ROS formation could be causal, but also contribute to a large number of the metabolic defects in T2D, including beta-cell dysfunction and loss. Currently, our knowledge on beta-cell mass is limited to autopsy studies and based on comparisons with healthy controls. The combined evidence suggests that beta-cell mass is unaltered at onset of T2D but that it declines progressively. In order to better understand the pathophysiology of T2D, to identify and evaluate novel treatments, there is a need for in vivo techniques able to quantify beta-cell mass. Positron emission tomography holds great potential for this purpose and can in addition map metabolic defects, including ROS activity, in specific tissue compartments. In this review, we highlight the different phenotypical features of T2D and how metabolic defects impact oxidative stress and ROS formation. In addition, we review the literature on alterations of beta-cell mass in T2D and discuss potential techniques to assess beta-cell mass and metabolic defects in vivo.
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Affiliation(s)
- Andris Elksnis
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Mats Martinell
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Olof Eriksson
- Science for Life Laboratory, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Daniel Espes
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.,Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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11
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Molecular Probes for Evaluation of Oxidative Stress by In Vivo EPR Spectroscopy and Imaging: State-of-the-Art and Limitations. MAGNETOCHEMISTRY 2019. [DOI: 10.3390/magnetochemistry5010013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Oxidative stress, defined as a misbalance between the production of reactive oxygen species and the antioxidant defenses of the cell, appears as a critical factor either in the onset or in the etiology of many pathological conditions. Several methods of detection exist. However, they usually rely on ex vivo evaluation or reports on the status of living tissues only up to a few millimeters in depth, while a whole-body, real-time, non-invasive monitoring technique is required for early diagnosis or as an aid to therapy (to monitor the action of a drug). Methods based on electron paramagnetic resonance (EPR), in association with molecular probes based on aminoxyl radicals (nitroxides) or hydroxylamines especially, have emerged as very promising to meet these standards. The principles involve monitoring the rate of decrease or increase of the EPR signal in vivo after injection of the nitroxide or the hydroxylamine probe, respectively, in a pathological versus a control situation. There have been many successful applications in various rodent models. However, current limitations lie in both the field of the technical development of the spectrometers and the molecular probes. The scope of this review will mainly focus on the latter.
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12
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Bonnitcha P, Grieve S, Figtree G. Clinical imaging of hypoxia: Current status and future directions. Free Radic Biol Med 2018; 126:296-312. [PMID: 30130569 DOI: 10.1016/j.freeradbiomed.2018.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/30/2018] [Accepted: 08/14/2018] [Indexed: 12/20/2022]
Abstract
Tissue hypoxia is a key feature of many important causes of morbidity and mortality. In pathologies such as stroke, peripheral vascular disease and ischaemic heart disease, hypoxia is largely a consequence of low blood flow induced ischaemia, hence perfusion imaging is often used as a surrogate for hypoxia to guide clinical diagnosis and treatment. Importantly, ischaemia and hypoxia are not synonymous conditions as it is not universally true that well perfused tissues are normoxic or that poorly perfused tissues are hypoxic. In pathologies such as cancer, for instance, perfusion imaging and oxygen concentration are less well correlated, and oxygen concentration is independently correlated to radiotherapy response and overall treatment outcomes. In addition, the progression of many diseases is intricately related to maladaptive responses to the hypoxia itself. Thus there is potentially great clinical and scientific utility in direct measurements of tissue oxygenation. Despite this, imaging assessment of hypoxia in patients is rarely performed in clinical settings. This review summarises some of the current methods used to clinically evaluate hypoxia, the barriers to the routine use of these methods and the newer agents and techniques being explored for the assessment of hypoxia in pathological processes.
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Affiliation(s)
- Paul Bonnitcha
- Northern and Central Clinical Schools, Faculty of Medicine, Sydney University, Sydney, NSW 2006, Australia; Chemical Pathology Department, NSW Health Pathology, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia; Kolling Institute of Medical Research, University of Sydney, St Leonards, New South Wales 2065, Australia.
| | - Stuart Grieve
- Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre and Sydney Medical School, University of Sydney, NSW 2050, Australia
| | - Gemma Figtree
- Kolling Institute of Medical Research, University of Sydney, St Leonards, New South Wales 2065, Australia; Cardiology Department, Royal North Shore Hospital, St Leonards, New South Wales 2065, Australia
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13
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Stamenković S, Pavićević A, Mojović M, Popović-Bijelić A, Selaković V, Andjus P, Bačić G. In vivo EPR pharmacokinetic evaluation of the redox status and the blood brain barrier permeability in the SOD1 G93A ALS rat model. Free Radic Biol Med 2017; 108:258-269. [PMID: 28366802 DOI: 10.1016/j.freeradbiomed.2017.03.034] [Citation(s) in RCA: 9] [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: 01/10/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 12/14/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting the motor pathways of the central nervous system. Although a number of pathophysiological mechanisms have been described in the disease, post mortem and animal model studies indicate blood-brain barrier (BBB) disruption and elevated production of reactive oxygen species as major contributors to disease pathology. In this study, the BBB permeability and the brain tissue redox status of the SOD1G93A ALS rat model in the presymptomatic (preALS) and symptomatic (ALS) stages of the disease were investigated by in vivo EPR spectroscopy using three aminoxyl radicals with different cell membrane and BBB permeabilities, Tempol, 3-carbamoyl proxyl (3CP), and 3-carboxy proxyl (3CxP). Additionally, the redox status of the two brain regions previously implicated in disease pathology, brainstem and hippocampus, was investigated by spectrophotometric biochemical assays. The EPR results indicated that among the three spin probes, 3CP is the most suitable for reporting the intracellular redox status changes, as Tempol was reduced in vivo within minutes (t1/2 =2.0±0.5min), thus preventing reliable kinetic modeling, whereas 3CxP reduction kinetics gave divergent conclusions, most probably due to its membrane impermeability. It was observed that the reduction kinetics of 3CP in vivo, in the head of preALS and ALS SOD1G93A rats was altered compared to the controls. Pharmacokinetic modeling of 3CP reduction in vivo, revealed elevated tissue distribution and tissue reduction rate constants indicating an altered brain tissue redox status, and possibly BBB disruption in these animals. The preALS and ALS brain tissue homogenates also showed increased nitrilation, superoxide production, lipid peroxidation and manganese superoxide dismutase activity, and a decreased copper-zinc superoxide dismutase activity. The present study highlights in vivo EPR spectroscopy as a reliable tool for the investigation of changes in BBB permeability and for the unprecedented in vivo monitoring of the brain tissue redox status, as early markers of ALS.
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Affiliation(s)
- Stefan Stamenković
- University of Belgrade - Faculty of Biology, Center for Laser Microscopy, Studentski trg 3, 11158 Belgrade, Serbia
| | - Aleksandra Pavićević
- University of Belgrade - Faculty of Physical Chemistry, EPR Laboratory, Studentski trg 12-16, 11158 Belgrade, Serbia
| | - Miloš Mojović
- University of Belgrade - Faculty of Physical Chemistry, EPR Laboratory, Studentski trg 12-16, 11158 Belgrade, Serbia
| | - Ana Popović-Bijelić
- University of Belgrade - Faculty of Physical Chemistry, EPR Laboratory, Studentski trg 12-16, 11158 Belgrade, Serbia
| | - Vesna Selaković
- Institute for Medical Research, Military Medical Academy, Crnotravska 17, 11000 Belgrade, Serbia
| | - Pavle Andjus
- University of Belgrade - Faculty of Biology, Center for Laser Microscopy, Studentski trg 3, 11158 Belgrade, Serbia.
| | - Goran Bačić
- University of Belgrade - Faculty of Physical Chemistry, EPR Laboratory, Studentski trg 12-16, 11158 Belgrade, Serbia
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Yamamoto S, Watabe T, Ikeda H, Kanai Y, Ichikawa K, Nakao M, Kato K, Hatazawa J. Development of a PET/OMRI combined system for simultaneous imaging of positron and free radical probes for small animals. Med Phys 2016; 43:5676. [PMID: 27782727 DOI: 10.1118/1.4963215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Positron emission tomography (PET) has high sensitivity for imaging radioactive tracer distributions in subjects. However, it is not possible to image free radical distribution in a subject by PET. Since free radicals are quite reactive, they are related to many diseases, including but not limited to cancer, inflammation, strokes, and heart disease. The Overhauser enhanced magnetic resonance imaging (OMRI) is so far the only method that images free radical distribution in vivo. By combining PET and OMRI, a new hybrid imaging modality might be developed that can simultaneously image the radioactive tracer and free radical distributions. For this purpose, the authors developed a PET/OMRI combined system for small animals. METHODS The developed PET/OMRI system used an optical fiber-based PET system combined with a permanent magnet-based OMRI system. The optical fiber-based PET system uses flexible optical fiber bundles. Eight optical fiber-based block detectors were arranged in a 56 mm diameter ring to form a PET system. The LGSO blocks were located inside the field-of-view (FOV) of the OMRI, and the position sensitive photomultiplier tubes were positioned behind the OMRI to minimize the interference between the PET and the OMRI. The OMRI system used a 0.0165 T permanent magnet. The system has an electron spin resonance coil to enhance the MRI signal using the Overhauser effect to image the free radical in the FOV of the PET/OMRI system. RESULTS The spatial resolution and sensitivity of the optical fiber-based PET system were 1.2 mm FWHM and 1.2% at the central FOV, respectively. The OMRI system imaged the distribution of a nitroxyl radical (NXR) solution. The interference between PET and OMRI was small. Simultaneous imaging of the positron radiotracer and the NXR solution was successfully conducted with the developed PET/OMRI system for phantom and small animal studies. CONCLUSIONS The authors developed a PET/OMRI combined system with the potential to provide interesting new results in molecular imaging research, such as in vivo molecular and free radical distributions.
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Affiliation(s)
- Seiichi Yamamoto
- Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Aichi 461-8673, Japan
| | - Tadashi Watabe
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Hayato Ikeda
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Yasukazu Kanai
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Kazuhiro Ichikawa
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka 812-8582, Japan
| | | | - Katsuhiko Kato
- Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Aichi 461-8673, Japan
| | - Jun Hatazawa
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
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15
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Biller JR, Mitchell DG, Tseytlin M, Elajaili H, Rinard GA, Quine RW, Eaton SS, Eaton GR. Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo. J Vis Exp 2016. [PMID: 27768025 DOI: 10.3791/54068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH•, NO•). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique. A variety of phantom configurations have been tested, with spatial resolution varying from 1 to 6 mm, and spectral width of the reporter molecules ranging from 16 µT (160 mG) to 5 mT (50 G). A cross-loop bimodal resonator decouples excitation and detection, reducing the noise, while the rapid scan effect allows more power to be input to the spin system before saturation, increasing the EPR signal. This leads to a substantially higher signal-to-noise ratio than in conventional CW EPR experiments.
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Affiliation(s)
- Joshua R Biller
- Department of Chemistry and Biochemistry, University of Denver; Magnetic Imaging Group, Applied Physics Division, Physical Measurements Laboratory, National Institute of Standards and Technology
| | | | - Mark Tseytlin
- Department of Radiology, Geisel School of Medicine, Dartmouth University; Department of Biochemistry, West Virginia University
| | - Hanan Elajaili
- Department of Chemistry and Biochemistry, University of Denver
| | - George A Rinard
- Department of Electrical and Computer Engineering, University of Denver
| | | | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver;
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Maulucci G, Bačić G, Bridal L, Schmidt HH, Tavitian B, Viel T, Utsumi H, Yalçın AS, De Spirito M. Imaging Reactive Oxygen Species-Induced Modifications in Living Systems. Antioxid Redox Signal 2016; 24:939-58. [PMID: 27139586 PMCID: PMC4900226 DOI: 10.1089/ars.2015.6415] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
SIGNIFICANCE Reactive Oxygen Species (ROS) may regulate signaling, ion channels, transcription factors, and biosynthetic processes. ROS-related diseases can be due to either a shortage or an excess of ROS. RECENT ADVANCES Since the biological activity of ROS depends on not only concentration but also spatiotemporal distribution, real-time imaging of ROS, possibly in vivo, has become a need for scientists, with potential for clinical translation. New imaging techniques as well as new contrast agents in clinically established modalities were developed in the previous decade. CRITICAL ISSUES An ideal imaging technique should determine ROS changes with high spatio-temporal resolution, detect physiologically relevant variations in ROS concentration, and provide specificity toward different redox couples. Furthermore, for in vivo applications, bioavailability of sensors, tissue penetration, and a high signal-to-noise ratio are additional requirements to be satisfied. FUTURE DIRECTIONS None of the presented techniques fulfill all requirements for clinical translation. The obvious way forward is to incorporate anatomical and functional imaging into a common hybrid-imaging platform. Antioxid. Redox Signal. 24, 939-958.
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Affiliation(s)
- Giuseppe Maulucci
- 1 Institute of Physics, Catholic University of Sacred Heart , Roma, Italy
| | - Goran Bačić
- 2 Faculty of Physical Chemistry, University of Belgrade , Belgrade, Serbia
| | - Lori Bridal
- 3 Laboratoire d'Imagerie Biomédicale, Sorbonne Universités and UPMC Univ Paris 06 and CNRS and INSERM , Paris, France
| | - Harald Hhw Schmidt
- 4 Department of Pharmacology and Personalised Medicine, CARIM, Faculty of Health, Medicine & Life Science, Maastricht University , Maastricht, the Netherlands
| | - Bertrand Tavitian
- 5 Laboratoire de Recherche en Imagerie, Université Paris Descartes, Hôpital Européen Georges Pompidou , Service de Radiologie, Paris, France
| | - Thomas Viel
- 5 Laboratoire de Recherche en Imagerie, Université Paris Descartes, Hôpital Européen Georges Pompidou , Service de Radiologie, Paris, France
| | - Hideo Utsumi
- 6 Innovation Center for Medical Redox Navigation, Kyushu University , Fukuoka, Japan
| | - A Süha Yalçın
- 7 Department of Biochemistry, School of Medicine, Marmara University , İstanbul, Turkey
| | - Marco De Spirito
- 1 Institute of Physics, Catholic University of Sacred Heart , Roma, Italy
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17
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Bačić G, Pavićević A, Peyrot F. In vivo evaluation of different alterations of redox status by studying pharmacokinetics of nitroxides using magnetic resonance techniques. Redox Biol 2015; 8:226-42. [PMID: 26827126 PMCID: PMC4753396 DOI: 10.1016/j.redox.2015.10.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 10/25/2015] [Indexed: 12/22/2022] Open
Abstract
Free radicals, particularly reactive oxygen species (ROS), are involved in various pathologies, injuries related to radiation, ischemia-reperfusion or ageing. Unfortunately, it is virtually impossible to directly detect free radicals in vivo, but the redox status of the whole organism or particular organ can be studied in vivo by using magnetic resonance techniques (EPR and MRI) and paramagnetic stable free radicals - nitroxides. Here we review results obtained in vivo following the pharmacokinetics of nitroxides on experimental animals (and a few in humans) under various conditions. The focus was on conditions where the redox status has been altered by induced diseases or harmful agents, clearly demonstrating that various EPR/MRI/nitroxide combinations can reliably detect metabolically induced changes in the redox status of organs. These findings can improve our understanding of oxidative stress and provide a basis for studying the effectiveness of interventions aimed to modulate oxidative stress. Also, we anticipate that the in vivo EPR/MRI approach in studying the redox status can play a vital role in the clinical management of various pathologies in the years to come providing the development of adequate equipment and probes.
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Affiliation(s)
- Goran Bačić
- EPR Laboratory, Faculty of Physical Chemistry, University of Belgrade, 11000 Belgrade, Serbia
| | - Aleksandra Pavićević
- EPR Laboratory, Faculty of Physical Chemistry, University of Belgrade, 11000 Belgrade, Serbia
| | - Fabienne Peyrot
- LCBPT, UMR 8601 CNRS - Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France; ESPE of Paris, Paris Sorbonne Université, 75016 Paris, France
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18
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Biller JR, Tseitlin M, Quine RW, Rinard GA, Weismiller HA, Elajaili H, Rosen GM, Kao JPY, Eaton SS, Eaton GR. Imaging of nitroxides at 250MHz using rapid-scan electron paramagnetic resonance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 242:162-8. [PMID: 24650729 PMCID: PMC4081024 DOI: 10.1016/j.jmr.2014.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/15/2014] [Accepted: 02/18/2014] [Indexed: 05/12/2023]
Abstract
Projections for 2D spectral-spatial images were obtained by continuous wave and rapid-scan electron paramagnetic resonance using a bimodal cross-loop resonator at 251MHz. The phantom consisted of three 4mm tubes containing different (15)N,(2)H-substituted nitroxides. Rapid-scan and continuous wave images were obtained with 5min total acquisition times. For comparison, images also were obtained with 29s acquisition time for rapid scan and 15min for continuous wave. Relative to continuous wave projections obtained for the same data acquisition time, rapid-scan projections had significantly less low-frequency noise and substantially higher signal-to-noise at higher gradients. Because of the improved image quality for the same data acquisition time, linewidths could be determined more accurately from the rapid-scan images than from the continuous wave images.
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Affiliation(s)
- Joshua R Biller
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States
| | - Mark Tseitlin
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States
| | - Richard W Quine
- Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States; School of Engineering and Computer Science, University of Denver, Denver, CO 80208, United States
| | - George A Rinard
- Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States; School of Engineering and Computer Science, University of Denver, Denver, CO 80208, United States
| | - Hilary A Weismiller
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States
| | - Hanan Elajaili
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States
| | - Gerald M Rosen
- Center for Biomedical Engineering and Technology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States; Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD 21201, United States
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States; Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States; Center for EPR Imaging in Vivo Physiology, University of Denver, Denver, CO 80208, United States.
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19
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Gustafsson H, Hallbeck M, Lindgren M, Kolbun N, Jonson M, Engström M, de Muinck E, Zachrisson H. Visualization of oxidative stress in ex vivo biopsies using electron paramagnetic resonance imaging. Magn Reson Med 2014; 73:1682-91. [DOI: 10.1002/mrm.25267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/26/2014] [Accepted: 04/04/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Håkan Gustafsson
- Department of Medical Technology (MTÖ), Radiation Physics; Department of Medical and Health Sciences, Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Sweden
| | - Martin Hallbeck
- Department of Clinical Pathology and Clinical Genetics, and Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Mikael Lindgren
- Department of Physics; Norwegian University of Science and Technology; Trondheim Norway
- IFM-Department of Chemistry; Linköping University; Linköping Sweden
| | - Natallia Kolbun
- Department of Medical Technology (MTÖ), Radiation Physics; Department of Medical and Health Sciences, Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Sweden
| | - Maria Jonson
- IFM-Department of Chemistry; Linköping University; Linköping Sweden
| | - Maria Engström
- Department of Medical Technology (MTÖ), Radiation Physics; Department of Medical and Health Sciences, Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Sweden
| | - Ebo de Muinck
- Department of Clinical Physiology, Division of Cardiovascular Medicine, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
| | - Helene Zachrisson
- Department of Clinical Physiology, Division of Cardiovascular Medicine, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
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Biller JR, Elajaili H, Meyer V, Rosen GM, Eaton SS, Eaton GR. Electron spin-lattice relaxation mechanisms of rapidly-tumbling nitroxide radicals. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 236:47-56. [PMID: 24056272 PMCID: PMC3952064 DOI: 10.1016/j.jmr.2013.08.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 08/13/2013] [Accepted: 08/14/2013] [Indexed: 05/12/2023]
Abstract
Electron spin relaxation times at 295 K were measured at frequencies between 250 MHz and 34 GHz for perdeuterated 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (PDT) in five solvents with viscosities that result in tumbling correlation times, τR, between 4 and 50 ps and for three (14)N/(15)N pairs of nitroxides in water with τR between 9 and 19 ps. To test the impact of structure on relaxation three additional nitroxides with τR between 10 and 26 ps were studied. In this fast tumbling regime T2(-1)~T1(-1) at frequencies up to about 9 GHz. At 34 GHz T2(-1)>T1(-1) due to increased contributions to T2(-1) from incomplete motional averaging of g-anisotropy, and T2(-1)-T1(-1) is proportional to τR. The contribution to T1(-1) from spin rotation is independent of frequency and decreases as τR increases. Spin rotation dominates T1(-1) at 34 GHz for all τR studied, and at all frequencies studied for τR=4 ps. The contribution to T1(-1) from modulation of nitrogen hyperfine anisotropy increases as frequency decreases and as τR increases; it dominates at low frequencies for τR>~15 ps. The contribution from modulation of g anisotropy is significant only at 34 GHz. Inclusion of a thermally-activated process was required to account for the observation that for most of the radicals, T1(-1) was smaller at 250 MHz than at 1-2 GHz. The significant (15)N/(14)N isotope effect, the small H/D isotope effect, and the viscosity dependence of the magnitude of the contribution from the thermally-activated process suggest that it arises from intramolecular motions of the nitroxide ring that modulate the isotropic A values.
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Affiliation(s)
- Joshua R. Biller
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80208
| | - Hanan Elajaili
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80208
| | - Virginia Meyer
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80208
| | - Gerald M. Rosen
- Department of Pharmaceutical Sciences, Center for EPR Imaging in Vivo Physiology, and Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, MD 21201
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80208
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80208
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21
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Johnson DH, Ahmad R, He G, Samouilov A, Zweier JL. Compressed sensing of spatial electron paramagnetic resonance imaging. Magn Reson Med 2013; 72:893-901. [PMID: 24123102 DOI: 10.1002/mrm.24966] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/26/2013] [Accepted: 09/03/2013] [Indexed: 12/20/2022]
Abstract
PURPOSE To improve image quality and reduce data requirements for spatial electron paramagnetic resonance imaging (EPRI) by developing a novel reconstruction approach using compressed sensing (CS). METHODS EPRI is posed as an optimization problem, which is solved using regularized least-squares with sparsity promoting penalty terms, consisting of the l1 norms of the image itself and the total variation of the image. Pseudo-random sampling was employed to facilitate recovery of the sparse signal. The reconstruction was compared with the traditional filtered back-projection reconstruction for simulations, phantoms, isolated rat hearts, and mouse gastrointestinal (GI) tracts labeled with paramagnetic probes. RESULTS A combination of pseudo-random sampling and CS was able to generate high-fidelity EPR images at high acceleration rates. For three-dimensional (3D) phantom imaging, CS-based EPRI showed little visual degradation at nine-fold acceleration. In rat heart datasets, CS-based EPRI produced high quality images with eight-fold acceleration. A high resolution mouse GI tract reconstruction demonstrated a visual improvement in spatial resolution and a doubling in signal-to-noise ratio (SNR). CONCLUSION A novel 3D EPRI reconstruction using compressed sensing was developed and offers superior SNR and reduced artifacts from highly undersampled data.
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Affiliation(s)
- David H Johnson
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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Eaton SS, Eaton GR. The world as viewed by and with unpaired electrons. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:151-63. [PMID: 22975244 PMCID: PMC3496796 DOI: 10.1016/j.jmr.2012.07.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 06/01/2023]
Abstract
Recent advances in electron paramagnetic resonance (EPR) include capabilities for applications to areas as diverse as archeology, beer shelf life, biological structure, dosimetry, in vivo imaging, molecular magnets, and quantum computing. Enabling technologies include multifrequency continuous wave, pulsed, and rapid scan EPR. Interpretation is enhanced by increasingly powerful computational models.
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Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
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