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Liu Y, Lehnert T, Mayr T, Gijs MAM. Antimicrobial susceptibility testing by measuring bacterial oxygen consumption on an integrated platform. LAB ON A CHIP 2021; 21:3520-3531. [PMID: 34286790 DOI: 10.1039/d1lc00296a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Cellular respiration is a fundamental feature of metabolic activity and oxygen consumption can be considered as a reliable indicator of bacterial aerobic respiration, including for facultative anaerobic bacteria like E. coli. Addressing the emerging global health challenge of antimicrobial resistance, we performed antimicrobial susceptibility testing using the bacterial oxygen consumption rate (OCR) as a phenotypic indicator. We demonstrated that microbial exposure to antibiotics showed systematic OCR variations, which enabled determining minimum inhibitory concentrations for three clinically relevant antibiotics, ampicillin, ciprofloxacin, and gentamicin, within a few hours. Our study was performed by using photoluminescence-based oxygen sensing in a microchamber format, which enabled reducing the sample volume to a few hundred microliters. OCR modeling based on exponential bacterial growth allowed estimating the bacterial doubling time for various culture conditions (different types of media, different culture temperature and antibiotic concentrations). Furthermore, correlating metabolic heat production data, as obtained by nanocalorimetry in the same type of microchamber, and OCR measurements provided further insight on the actual metabolic state and activity of a microbial sample. This approach represents a new path towards more comprehensive microbiological studies performed on integrated miniaturized systems.
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Affiliation(s)
- Yang Liu
- Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
| | - Thomas Lehnert
- Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
| | - Torsten Mayr
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, 80 Graz, Austria
| | - Martin A M Gijs
- Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
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2
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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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3
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Olowe R, Sandouka S, Saadi A, Shekh-Ahmad T. Approaches for Reactive Oxygen Species and Oxidative Stress Quantification in Epilepsy. Antioxidants (Basel) 2020; 9:E990. [PMID: 33066477 PMCID: PMC7602129 DOI: 10.3390/antiox9100990] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 12/27/2022] Open
Abstract
Oxidative stress (OS) and excessive reactive oxygen species (ROS) production have been implicated in many neurological pathologies, including acute seizures and epilepsy. Seizure-induced damage has been demonstrated both in vitro and in several in vivo seizure and epilepsy models by direct determination of ROS, and by measuring indirect markers of OS. In this manuscript, we review the current reliable methods for quantifying ROS-related and OS-related markers in pre-clinical and clinical epilepsy studies. We first provide pieces of evidence for the involvement of different sources of ROS in epilepsy. We then discuss general methods and assays used for the ROS measurements, mainly superoxide anion, hydrogen peroxide, peroxynitrite, and hydroxyl radical in in vitro and in vivo studies. In addition, we discuss the role of these ROS and markers of oxidative injury in acute seizures and epilepsy pre-clinical studies. The indirect detection of secondary products of ROS such as measurements of DNA damage, lipid peroxidation, and protein oxidation will also be discussed. This review also discusses reliable methods for the assessment of ROS, OS markers, and their by-products in epilepsy clinical studies.
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Affiliation(s)
| | | | | | - Tawfeeq Shekh-Ahmad
- The Institute for Drug Research, The School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel; (R.O.); (S.S.); (A.S.)
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Implantable microchip containing oxygen-sensing paramagnetic crystals for long-term, repeated, and multisite in vivo oximetry. Biomed Microdevices 2019; 21:71. [PMID: 31286244 DOI: 10.1007/s10544-019-0421-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
EPR oximetry is established as a viable method for measuring the tissue oxygen level (partial pressure of oxygen, pO2) in animal models; however, it has not yet been established for measurements in humans. EPR oximetry requires an oxygen-sensing paramagnetic probe (molecular or particulate) to be placed at the site/organ of measurement, which may pose logistical and safety concerns, including invasiveness of the probe-placement procedure as well as lack of temporal stability and sensitivity for long-term (repeated) measurements, and possible toxicity in the short- and long-term. In the past, we have developed an implantable oxygen-sensing probe, called OxyChip, which we have successfully established for oximetry in pre-clinical animal models (Hou et al. Biomed. Microdevices 20, 29, 2018). Currently, OxyChip is being evaluated in a limited clinical trial in cancer patients. A major limitation of OxyChip is that it is a large (1.4 mm3) implant and hence not suitable for measuring oxygen heterogeneity that may be present in solid tumors, chronic wounds, etc. In this report, we describe the development of a substantially smaller version of OxyChip (0.07 mm3 or 70 cubic micron), called mChip, that can be placed in the tissue of interest using a 23G syringe-needle with minimal invasiveness. Using in vitro and in vivo models, we have shown that the microchip provides adequate EPR sensitivity, stability, and biocompatibility and thus enables robust, repeated, and simultaneous measurement from multiple implants providing mean and median pO2 values in the implanted region. The mChips will be particularly useful for those applications that require repeated measurements of mean/median pO2 in superficial tissues and malignancies.
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Daimiel I. Insights into Hypoxia: Non-invasive Assessment through Imaging Modalities and Its Application in Breast Cancer. J Breast Cancer 2019; 22:155-171. [PMID: 31281720 PMCID: PMC6597408 DOI: 10.4048/jbc.2019.22.e26] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 04/15/2019] [Indexed: 12/11/2022] Open
Abstract
Oxygen is crucial to maintain the homeostasis in aerobic cells. Hypoxia is a condition in which cells are deprived of the oxygen supply necessary for their optimum performance. Whereas oxygen deprivation may occur in normal physiological processes, hypoxia is frequently associated with pathological conditions. It has been identified as a stressor in the tumor microenvironment, acting as a key mediator of cancer development. Numerous pathways are activated in hypoxic cells that affect cell signaling and gene regulation to promote the survival of these cells by stimulating angiogenesis, switching cellular metabolism, slowing their growth rate, and preventing apoptosis. The induction of dysregulated metabolism in cancer cells by hypoxia results in aggressive tumor phenotypes that are characterized by rapid progression, treatment resistance, and poor prognosis. A non-invasive assessment of hypoxia-induced metabolic and architectural changes in tumors is advisable to fully improve breast cancer (BC) patient management, by potentially reducing the need for invasive biopsy procedures and evaluating tumor response to treatment. This review provides a comprehensive overview of the molecular changes in breast tumors secondary to hypoxia and the non-invasive imaging alternatives to evaluate oxygen deprivation, with an emphasis on their application in BC and the advantages and limitations of the currently available techniques.
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Affiliation(s)
- Isaac Daimiel
- Department of Radiology, Breast Imaging Service, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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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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7
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Nezakati T, Seifalian A, Tan A, Seifalian AM. Conductive Polymers: Opportunities and Challenges in Biomedical Applications. Chem Rev 2018; 118:6766-6843. [DOI: 10.1021/acs.chemrev.6b00275] [Citation(s) in RCA: 354] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Toktam Nezakati
- Google Inc.., Mountain View, California 94043, United States
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery and Interventional Science, University College London, London NW3 2QG, United Kingdom
| | - Amelia Seifalian
- UCL Medical School, University College London, London WC1E 6BT, United Kingdom
| | - Aaron Tan
- UCL Medical School, University College London, London WC1E 6BT, United Kingdom
| | - Alexander M. Seifalian
- NanoRegMed Ltd. (Nanotechnology and Regenerative Medicine Commercialization Centre), The London Innovation BioScience Centre, London NW1 0NH, United Kingdom
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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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9
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Sato-Akaba H, Emoto MC, Hirata H, Fujii HG. Design and testing of a 750MHz CW-EPR digital console for small animal imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 284:48-58. [PMID: 28961477 DOI: 10.1016/j.jmr.2017.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 09/15/2017] [Accepted: 09/16/2017] [Indexed: 05/12/2023]
Abstract
This paper describes the development of a digital console for three-dimensional (3D) continuous wave electron paramagnetic resonance (CW-EPR) imaging of a small animal to improve the signal-to-noise ratio and lower the cost of the EPR imaging system. A RF generation board, an RF acquisition board and a digital signal processing (DSP) & control board were built for the digital EPR detection. Direct sampling of the reflected RF signal from a resonator (approximately 750MHz), which contains the EPR signal, was carried out using a band-pass subsampling method. A direct automatic control system to reduce the reflection from the resonator was proposed and implemented in the digital EPR detection scheme. All DSP tasks were carried out in field programmable gate array ICs. In vivo 3D imaging of nitroxyl radicals in a mouse's head was successfully performed.
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Affiliation(s)
- Hideo Sato-Akaba
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Miho C Emoto
- Center for Medical Education, Sapporo Medical University, Sapporo, Hokkaido 060-8556, Japan
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido 060-0814, Japan
| | - Hirotada G Fujii
- Center for Medical Education, Sapporo Medical University, Sapporo, Hokkaido 060-8556, Japan
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10
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Colliez F, Gallez B, Jordan BF. Assessing Tumor Oxygenation for Predicting Outcome in Radiation Oncology: A Review of Studies Correlating Tumor Hypoxic Status and Outcome in the Preclinical and Clinical Settings. Front Oncol 2017; 7:10. [PMID: 28180110 PMCID: PMC5263142 DOI: 10.3389/fonc.2017.00010] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/10/2017] [Indexed: 12/30/2022] Open
Abstract
Tumor hypoxia is recognized as a limiting factor for the efficacy of radiotherapy, because it enhances tumor radioresistance. It is strongly suggested that assessing tumor oxygenation could help to predict the outcome of cancer patients undergoing radiation therapy. Strategies have also been developed to alleviate tumor hypoxia in order to radiosensitize tumors. In addition, oxygen mapping is critically needed for intensity modulated radiation therapy (IMRT), in which the most hypoxic regions require higher radiation doses and the most oxygenated regions require lower radiation doses. However, the assessment of tumor oxygenation is not yet included in day-to-day clinical practice. This is due to the lack of a method for the quantitative and non-invasive mapping of tumor oxygenation. To fully integrate tumor hypoxia parameters into effective improvements of the individually tailored radiation therapy protocols in cancer patients, methods allowing non-invasively repeated, safe, and robust mapping of changes in tissue oxygenation are required. In this review, non-invasive methods dedicated to assessing tumor oxygenation with the ultimate goal of predicting outcome in radiation oncology are presented, including positron emission tomography used with nitroimidazole tracers, magnetic resonance methods using endogenous contrasts (R1 and R2*-based methods), and electron paramagnetic resonance oximetry; the goal is to highlight results of studies establishing correlations between tumor hypoxic status and patients’ outcome in the preclinical and clinical settings.
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Affiliation(s)
- Florence Colliez
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Bernard Gallez
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Bénédicte F Jordan
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
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11
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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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12
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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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13
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Epel B, Bowman MK, Mailer C, Halpern HJ. Absolute oxygen R1e imaging in vivo with pulse electron paramagnetic resonance. Magn Reson Med 2013; 72:362-8. [PMID: 24006331 DOI: 10.1002/mrm.24926] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 07/26/2013] [Accepted: 07/29/2013] [Indexed: 01/19/2023]
Abstract
PURPOSE Tissue oxygen (O2) levels are among the most important and most quantifiable stimuli to which cells and tissues respond through inducible signaling pathways. Tumor O2 levels are major determinants of the response to cancer therapy. Developing more accurate measurements and images of tissue O2 partial pressure (pO2), assumes enormous practical, biological, and medical importance. METHODS We present a fundamentally new technique to image pO2 in tumors and tissues with pulse electron paramagnetic resonance (EPR) imaging enabled by an injected, nontoxic, triaryl methyl (trityl) spin probe whose unpaired electron's slow relaxation rates report the tissue pO2. Heretofore, virtually all in vivo EPR O2 imaging measures pO2 with the transverse electron spin relaxation rate, R2e, which is susceptible to the self-relaxation confounding O2 sensitivity. RESULTS We found that the trityl electron longitudinal relaxation rate, R1e, is an order of magnitude less sensitive to confounding self-relaxation. R1e imaging has greater accuracy and brings EPR O2 images to an absolute pO2 image, within uncertainties. CONCLUSION R1e imaging more accurately determines oxygenation of cancer and normal tissue in animal models than has been available. It will enable enhanced, rapid, noninvasive O2 images for understanding oxygen biology and the relationship of oxygenation patterns to therapy outcome in living animal systems.
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Affiliation(s)
- Boris Epel
- Center for EPR Imaging In Vivo Physiology, The University of Chicago, Department of Radiation and Cellular Oncology (MC 1105), Chicago, Illinois, USA
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14
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Elas M, Magwood JM, Butler B, Li C, Wardak R, DeVries R, Barth ED, Epel B, Rubinstein S, Pelizzari CA, Weichselbaum RR, Halpern HJ. EPR oxygen images predict tumor control by a 50% tumor control radiation dose. Cancer Res 2013; 73:5328-35. [PMID: 23861469 DOI: 10.1158/0008-5472.can-13-0069] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Clinical trials to ameliorate hypoxia as a strategy to relieve the radiation resistance it causes have prompted a need to assay the precise extent and location of hypoxia in tumors. Electron paramagnetic resonance oxygen imaging (EPR O2 imaging) provides a noninvasive means to address this need. To obtain a preclinical proof-of-principle that EPR O2 images could predict radiation control, we treated mouse tumors at or near doses required to achieve 50% control (TCD50). Mice with FSa fibrosarcoma or MCa4 carcinoma were subjected to EPR O2 imaging and immediately radiated to a TCD50 or TCD50 ± 10 Gy. Statistical analysis was permitted by collection of approximately 1,300 tumor pO2 image voxels, including the fraction of tumor voxels with pO2 less than 10 mm Hg (HF10). Tumors were followed for 90 days (FSa) or 120 days (MCa4) to determine local control or failure. HF10 obtained from EPR images showed statistically significant differences between tumors that were controlled by the TCD50 and those that were not controlled for both FSa and MCa4. Kaplan-Meier analysis of both types of tumors showed that approximately 90% of mildly hypoxic tumors were controlled (HF10%< 10%), and only 37% (FSA) and 23% (MCa4) tumors controlled if hypoxic. EPR pO2 image voxel distributions in these approximately 0.5 mL tumors provide a prediction of radiation curability independent of radiation dose. These data confirm the significance of EPR pO2 hypoxic fractions. The 90% control of low HF10 tumors argue that 0.5 mL subvolumes of tumors may be more sensitive to radiation and may need less radiation for high tumor control rates. Cancer Res; 73(17); 5328-35. ©2013 AACR.
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Affiliation(s)
- Martyna Elas
- Departments of Radiation and Cellular Oncology and Radiology, Pritzker School of Medicine, Chicago, Illinois, USA
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Redler G, Barth ED, Bauer KS, Kao JPY, Rosen GM, Halpern HJ. In vivo electron paramagnetic resonance imaging of differential tumor targeting using cis-3,4-di(acetoxymethoxycarbonyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxyl. Magn Reson Med 2013; 71:1650-6. [PMID: 23776127 DOI: 10.1002/mrm.24813] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 03/27/2013] [Accepted: 04/26/2013] [Indexed: 12/21/2022]
Abstract
PURPOSE Electron paramagnetic resonance spectroscopy promises quantitative images of important physiologic markers of animal tumors and normal tissues, such as pO(2), pH, and thiol redox status. These parameters of tissue function are conveniently reported by tailored nitroxides. For defining tumor physiology, it is vital that nitroxides are selectively localized in tumors relative to normal tissue. Furthermore, these paramagnetic species should be specifically taken up by cells of the tumor, thereby reporting on both the site of tumor formation and the physiological status of the tissue. This study investigates the tumor localization of the novel nitroxide, cis-3,4-di(acetoxymethoxycarbonyl)-2,2,5,5-tetramethyl-1-pyrrolidin-yloxyl 3 relative to the corresponding di-acid 4. METHODS We obtained images of nitroxide 3 infused intravenously into C3H mice bearing 0.5-cm(3) FSa fibrosarcoma on the leg, and compared these with images of similar tumors infused with nitroxide 4. RESULTS The ratio of spectral intensity from within the tumor-bearing region to that of normal tissue was higher in the mice injected with 3 relative to 4. CONCLUSION This establishes the possibility of tumor imaging with a nitroxide with intracellular distribution and provides the basis for EPR images of animal models to investigate the relationship between crucial aspects of tumor microenvironment and malignancy and its response to therapy.
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Affiliation(s)
- Gage Redler
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois, USA; Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, Illinois, USA
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16
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Bézière N, Decroos C, Mkhitaryan K, Kish E, Richard F, Bigot-Marchand S, Durand S, Cloppet F, Chauvet C, Corvol MT, Rannou F, Xu-Li Y, Mansuy D, Peyrot F, Frapart YM. First Combined in Vivo X-Ray Tomography and High-Resolution Molecular Electron Paramagnetic Resonance (EPR) Imaging of the Mouse Knee Joint Taking into Account the Disappearance Kinetics of the EPR Probe. Mol Imaging 2012. [DOI: 10.2310/7290.2011.00042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Nicolas Bézière
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Christophe Decroos
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Karen Mkhitaryan
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Elizabeth Kish
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Frédéric Richard
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Stéphanie Bigot-Marchand
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Sylvain Durand
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Florence Cloppet
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Caroline Chauvet
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Marie-Thérèse Corvol
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - François Rannou
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Yun Xu-Li
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Daniel Mansuy
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Fabienne Peyrot
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
| | - Yves-Michel Frapart
- From CNRS UMR 8601, Université Paris Descartes, LCPBT; CNRS UMR 8145, Université Paris Descartes, MAP5, Université Paris Descartes, LIPADE, EA2517, Université Paris Descartes, INSERM UMR-S747, Department of Physical Medicine and Rehabilitation, Cochin Hospital (AP-HP), Université Paris Descartes; and Université Paris Sorbonne-IUFM de Paris, Paris, France
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17
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Elas M, Hleihel D, Barth ED, Haney CR, Ahn KH, Pelizzari CA, Epel B, Weichselbaum RR, Halpern HJ. Where it's at really matters: in situ in vivo vascular endothelial growth factor spatially correlates with electron paramagnetic resonance pO2 images in tumors of living mice. Mol Imaging Biol 2012; 13:1107-13. [PMID: 20960236 PMCID: PMC3210947 DOI: 10.1007/s11307-010-0436-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Purpose Tumor microenvironments show remarkable tumor pO2 heterogeneity, as seen in prior EPR pO2 images (EPROI). pO2 correlation with hypoxia response proteins is frustrated by large rapid pO2 changes with position. Procedures To overcome this limitation, biopsies stereotactically located in the EPROI were used to explore the relationship between vascular endothelial growth factor A (VEGF) concentrations in living mouse tumors and the local EPROI pO2. Results Quantitative ELISA VEGF concentrations correlated (p = 0.0068 to 0.019) with mean pO2, median pO2, and the fraction of voxels in the biopsy volume with pO2 less than 3, 6, and 10 Torr. Conclusions This validates EPROI hypoxic fractions at the molecular level and provides a new paradigm for the assessment of the relationship, in vivo, between hypoxia and hypoxia response proteins. When translated to human subjects, this will enhance understanding of human tumor pathophysiology and cancer response to therapy.
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Affiliation(s)
- Martyna Elas
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, USA
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18
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Seifi P, Epel B, Sundramoorthy SV, Mailer C, Halpern HJ. Frequency bandwidth extension by use of multiple Zeeman field offsets for electron spin-echo EPR oxygen imaging of large objects. Med Phys 2011; 38:3062-8. [PMID: 21815379 DOI: 10.1118/1.3590365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
PURPOSE Electron spin-echo (ESE) oxygen imaging is a new and evolving electron paramagnetic resonance (EPR) imaging (EPRI) modality that is useful for physiological in vivo applications, such as EPR oxygen imaging (EPROI), with potential application to imaging of multicentimeter objects as large as human tumors. A present limitation on the size of the object to be imaged at a given resolution is the frequency bandwidth of the system, since the location is encoded as a frequency offset in ESE imaging. The authors' aim in this study was to demonstrate the object size advantage of the multioffset bandwidth extension technique. METHODS The multiple-stepped Zeeman field offset (or simply multi-B) technique was used for imaging of an 8.5-cm-long phantom containing a narrow single line triaryl methyl compound (trityl) solution at the 250 MHz imaging frequency. The image is compared to a standard single-field ESE image of the same phantom. RESULTS For the phantom used in this study, transverse relaxation (T(2e)) electron spin-echo (ESE) images from multi-B acquisition are more uniform, contain less prominent artifacts, and have a better signal to noise ratio (SNR) compared to single-field T(2e) images. CONCLUSIONS The multi-B method is suitable for imaging of samples whose physical size restricts the applicability of the conventional single-field ESE imaging technique.
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Affiliation(s)
- Payam Seifi
- Department of Radiation and Cellular Oncology, Center for EPR Imaging In Vivo Physiology, The University of Chicago, Chicago, Illinois 60637, USA
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19
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Kumar S, Patel S, Jyoti A, Keshari RS, Verma A, Barthwal MK, Dikshit M. Nitric oxide-mediated augmentation of neutrophil reactive oxygen and nitrogen species formation: Critical use of probes. Cytometry A 2011; 77:1038-48. [PMID: 20886639 DOI: 10.1002/cyto.a.20975] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previous reports from this laboratory and others demonstrated NO-mediated biphasic modulation of NADPH oxidase and attenuation of neutrophil reactive oxygen species generation, whereas recently we reported augmentation in DCF fluorescence following NO treatment. These discrepancies seem to be due to utilization of different probes/methods to assess effect of NO on reactive oxygen and nitrogen species (ROS/RNS, reactive species) generation. This study aims to look into this and evaluate NO-mediated enzymatic reactive species formation by using multiple probes, human neutrophils/HL60 cells and various interventions. Addition of NO donor, SNP or SNAP (100 nM-1 mM) to PMNs suspension, exhibited a concentration- and time-dependent augmentation in DCF fluorescence, but reduced DHE fluorescence. Collective generation of reactive species was confirmed by enhanced DMPO-nitrone adduct, dityrosine and rhodamine-123 and quenching of scopoletin. NO also enhanced bacterial killing, without altering phagocytosis. Addition of NO to HL-60 cells lacking functional NADPH oxidase enhanced reactive species formation, indicating importance of other enzyme(s) too. NO-dependent ROS/RNS generation was substantially reduced by NADPH oxidase inhibitor (DPI), MPO inhibitor (ABAH), or NOS inhibitor (7-NI). However, 7-NI reduced MPO activity, warranting reappraisal of those reports, which implied NOS in reactive species formation. The results obtained demonstrated NO-mediated reactive species augmentation in human PMNs. Furthermore, superoxide scavenging by NO seems to be the key process in the decrease of DHE fluorescence and suggest usefulness of DCF as the most appropriate probe to measure the NO-mediated modulation of reactive oxygen species in particular in various pathological situations.
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Affiliation(s)
- Sachin Kumar
- Pharmacology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, India
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20
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Bobko AA, Kirilyuk IA, Gritsan NP, Polovyanenko DN, Grigor’ev IA, Khramtsov VV, Bagryanskaya EG. EPR and Quantum Chemical Studies of the pH-sensitive Imidazoline and Imidazolidine Nitroxides with Bulky Substituents. APPLIED MAGNETIC RESONANCE 2010; 39:437-451. [PMID: 22162912 PMCID: PMC3234120 DOI: 10.1007/s00723-010-0179-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The X- and W-band electron paramagnetic resonance (EPR) spectroscopies were employed to investigate a series of imidazolidine nitroxide radicals with different number of ethyl and methyl substituents at positions 2 and 5 of a heterocycle in liquid and frozen solutions. The influence of the substituents on the line shape and width was studied experimentally and analyzed using quantum chemical calculations. Each pair of the geminal ethyl groups in the positions 2 or 5 of the imidazolidine ring was found to produce an additional hyperfine splitting (hfs) of about 0.2 mT in the EPR spectra of the nitroxides. The effect was attributed to the hfs constant of only one of four methylene hydrogen atoms of two geminal ethyl substituents not fully averaged by ethyl group rotation and ring puckering. In accordance with this assumption, the substitution of hydrogen atoms of CH(2) groups in 2,2,5,5-tetraethyl-substituted imidazolidine nitroxides by deuterium leads to the substantial narrowing of EPR lines which could be useful for many biochemical and biomedical applications, including pH-monitoring. W-band EPR spectra of 2,2,5,5-tetraethyl-substituted imidazolidine nitroxide and its 2,2,5,5-tetraethyl-d(8) deuterium-substituted analog measured at low temperatures demonstrated high sensitivity of their g-factors to pH, which indicates their applicability as spin labels possessing high stability.
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Affiliation(s)
- A. A. Bobko
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - I. A. Kirilyuk
- Novosibirsk Institute of Organic Chemistry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N. P. Gritsan
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - D. N. Polovyanenko
- International Tomography Center, Russian Academy of Sciences, Institutskaya 3A, Novosibirsk 630090, Russia
| | - I. A. Grigor’ev
- Novosibirsk Institute of Organic Chemistry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - V. V. Khramtsov
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - E. G. Bagryanskaya
- International Tomography Center, Russian Academy of Sciences, Institutskaya 3A, Novosibirsk 630090, Russia
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21
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Bertuglia S, Intaglietta M. pO(2) and ROS/RNS measurements in the microcirculation in hypoxia. Methods Mol Biol 2010; 594:19-41. [PMID: 20072907 DOI: 10.1007/978-1-60761-411-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We expose methods for in vivo assessment of oxygen, nitric oxide (NO), and reactive oxygen species (ROS)/reactive nitrogen species (RNS), in the microcirculation during normoxia and hypoxia. We provide an example of the related mechanisms of ROS/RNS and oxygen level in the process of regulating capillary perfusion. Namely, we discuss the real time pO(2) measurements in vivo in the microvessels and tissues of the hamster cheek pouch and window chamber preparations during normoxia and hypoxia, as well as the corresponding changes in ROS/RNS in systemic blood during normoxia and hypoxia under conditions where NO availability is maximally reduced.
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Affiliation(s)
- Silvia Bertuglia
- CNR Institute of Clinical Physiology, University of Pisa, Pisa, Italy.
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22
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Bobko AA, Dhimitruka I, Eubank TD, Marsh CB, Zweier JL, Khramtsov VV. Trityl-based EPR probe with enhanced sensitivity to oxygen. Free Radic Biol Med 2009; 47:654-8. [PMID: 19523513 PMCID: PMC2739013 DOI: 10.1016/j.freeradbiomed.2009.06.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 06/03/2009] [Accepted: 06/05/2009] [Indexed: 11/27/2022]
Abstract
An asymmetric derivative of the triarylmethyl radical, TAM-H, containing one aldehyde and two carboxyl groups, was synthesized. The electron paramagnetic resonance (EPR) spectrum of TAM-H is characterized by a doublet of narrow lines with a linewidth of 105 mG under anoxic conditions and hyperfine interaction constant of 245 mG. The partial overlap of the components of the doublet results in enhanced sensitivity of the spectral amplitudes ratio to oxygen compared with oxygen-induced linewidth broadening of a single line. Application of the TAM-H probe allows for EPR measurements in an extended range of oxygen pressures from atmospheric to 1 mm Hg, whereas the EPR spectrum linewidth of the popular TAM-based oxygen sensor Oxo63 is practically insensitive to oxygen partial pressures below 20 mm Hg. Enhanced sensitivity of the TAM-H probe relative to Oxo63 was demonstrated in the detection of oxygen consumption by Met-1 cancer cells. The TAM-H probe allowed prolonged measurements of oxygen depletion during the hypoxia stage and down to true anoxia (<or=1.5 mm Hg).
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Affiliation(s)
- Andrey A Bobko
- Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
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23
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Vanea ES, Levêque P, Abboud F, Bol A, Denis JM, Kolbun N, Vynckier S, Gallez B. Evaluation of the dose distribution gradient in the close vicinity of brachytherapy seeds using electron paramagnetic resonance imaging. Magn Reson Med 2009; 61:1225-31. [DOI: 10.1002/mrm.21947] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Vikram DS, Ahmad R, Rivera BK, Kuppusamy P. Mapping of Oxygen Concentration in Biological Samples Using EPR Imaging. Isr J Chem 2008. [DOI: 10.1560/ijc.48.1.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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25
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Elas M, Bell R, Hleihel D, Barth ED, McFaul C, Haney CR, Bielanska J, Pustelny K, Ahn KH, Pelizzari CA, Kocherginsky M, Halpern HJ. Electron paramagnetic resonance oxygen image hypoxic fraction plus radiation dose strongly correlates with tumor cure in FSa fibrosarcomas. Int J Radiat Oncol Biol Phys 2008; 71:542-9. [PMID: 18474313 DOI: 10.1016/j.ijrobp.2008.02.022] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 02/10/2008] [Accepted: 02/13/2008] [Indexed: 11/26/2022]
Abstract
PURPOSE Tumor hypoxia has long been known to produce resistance to radiation. In this study, electron paramagnetic resonance (EPR) oxygen imaging was investigated for its power to predict the success of tumor control according to tumor oxygenation level and radiation dose. METHODS AND MATERIALS A total of 34 EPR oxygen images were obtained from the legs of C3H mice bearing 0.5-cm(3) FSa fibrosarcomas under both normal (air breathing) and clamped tumor conditions. Under the same conditions as those during which the images were obtained, the tumors were irradiated to a variety of doses near the FSa dose at which 50% of tumors were cured. Tumor tissue was distinguished from normal tissue using co-registration of the EPR oxygen images with spin-echo magnetic resonance imaging of the tumor and/or stereotactic localization. The tumor voxel statistics in the EPR oxygen image included the mean and median partial pressure of oxygen and the fraction of tumor voxels below the specified partial pressure of oxygen values of 3, 6, and 10 mm Hg. Bivariate logistic regression analysis using the radiation dose and each of the EPR oxygen image statistics to determine which best separated treatment failure from success. RESULTS The measurements of the dose at which 50% of tumors were cured were similar to those found in published data for this syngeneic tumor. Bivariate analysis of 34 tumors demonstrated that tumor cure correlated with dose (p = 0.004) and with a <10 mm Hg hypoxic fraction (p = 0.023). CONCLUSION Our results have shown that, together, radiation dose and EPR image hypoxic fraction separate the population of FSa fibrosarcomas that are cured from those that fail, thus predicting curability.
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Affiliation(s)
- Martyna Elas
- Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA
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26
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Enabling Sensor Technologies for the Quantitative Evaluation of Engineered Tissue. Ann Biomed Eng 2007; 36:30-40. [DOI: 10.1007/s10439-007-9399-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 10/23/2007] [Indexed: 10/22/2022]
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Fujii H, Itoh K, Pandian RP, Sakata M, Kuppusamy P, Hirata H. Measuring brain tissue oxygenation under oxidative stress by ESR/MR dual imaging system. Magn Reson Med Sci 2007; 6:83-9. [PMID: 17690538 DOI: 10.2463/mrms.6.83] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The in vivo measurement of oxygen in tissues is of great interest because of oxygen's fundamental role in life. Many methods have been developed for such measurement, but all have been limited, especially with regard to repeated measurement, degree of invasiveness, and sensitivity. We describe electron spin resonance (ESR) oximetry with paramagnetic oxygen-sensing probe for in vivo measurement of oxygen in brain tissues by home-made ESR/MR dual imaging spectroscopy. Lithium 5, 9, 14, 18, 23, 27, 32, 36-octa-n-butoxy-2,3-naphthlocyanine (LiNc-BuO) radical was employed as the solid oxygen-sensing probe, and we confirmed its ability to report partial pressure of oxygen (pO(2)) in brain tissues of live animals under normal and pathological conditions for more than a month. pO(2) measurements could also be made repeatedly on the same animal and at the same location. The implantation site of LiNc-BuO in examined rats was verified by 0.5 T magnetic resonance (MR) imaging. Septic-shock rats were used to monitor tissue oxygenation during pathological state. A decline in pO(2) levels from severe hypotension during sepsis was detected, and generation of nitric oxide (NO) in brain tissues was confirmed by NO spin trapping. ESR oximetry using oxygen-sensing probe and NO spin-trapping can be used to monitor pO(2) change and NO production simultaneously and repeatedly at the same site in examined animals.
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Affiliation(s)
- Hirotada Fujii
- School of Health Sciences, Sapporo Medical University, Sapporo, Japan.
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Abstract
The purpose of this review is to provide an overview of the methods available for imaging tissue oxygenation. The following imaging methods are reviewed: phosphorescence, near-infrared (NIR), positron emission tomography (PET), magnetic resonance imaging ((19)F MRI and BOLD MRI), and electron paramagnetic resonance (EPR). The methods are based on different principles and differ in their ability to accurately quantify tissue oxygenation, either the absolute value of a particular measure of oxygenation (partial pressure of oxygen, concentration), or a parameter related to it (oxygen saturation). Methods that can provide images of relative changes in oxygenation or visualization of hypoxia in a specific tissue of interest are also considered valuable tools for biomedical research and clinical applications.
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Affiliation(s)
- Deepti S Vikram
- Center for Biomedical EPR Spectroscopy and Imaging, Comprehensive Cancer Center, Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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Ichikawa K, Sakabe E, Kuninobu KI, Yamori T, Tsuruo T, Yao T, Tsuneyoshi M, Utsumi H. Application of in vivo ESR/spin-probe technique to monitor tumor in vivo in mouse footpad. Antioxid Redox Signal 2007; 9:1699-707. [PMID: 17665970 DOI: 10.1089/ars.2007.1719] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The redox status of tumors inoculated into the footpads of mice was investigated by using an in vivo ESR/spin-probe technique. A single-cell suspension of a metastatic subclone of colon carcinoma NL-17 was inoculated into the footpads of Balb/c mice. At 12, 24, 48, and 96 h after the inoculation, a spin probe, either carbamoylor carboxy-PROXYL, was intravenously injected, and then the ESR spectra of each footpad were separately obtained under a one-dimensional magnetic-field gradient. The change in the ESR signal intensity of the spin probe was closely related to the tumor volume in the footpads, but no significant difference was observed between carbamoyl- and carboxy-PROXYL. The in vivo ESR signal decay of carbamoyl-PROXYL, which is related to the conversion of the nitroxyl radical to hydroxylamine, was enhanced in the inoculated footpads but not in the reference one. The ESR signal decay was not influenced by coadministration of radical scavengers, SOD, catalase, mannitol, or dimethylthiourea, suggesting that the redox status but not reactive oxygen species generation played a role in the enhanced signal decay.
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Affiliation(s)
- Kazuhiro Ichikawa
- Department of Bio-function Science, Graduate School of Pharmaceutical Sciences, Kyushu University, Kyushu, Japan
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Matsumoto KI, Subramanian S, Murugesan R, Mitchell JB, Krishna MC. Spatially resolved biologic information from in vivo EPRI, OMRI, and MRI. Antioxid Redox Signal 2007; 9:1125-41. [PMID: 17571957 DOI: 10.1089/ars.2007.1638] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
EPR spectroscopy can give biologically important information, such as tissue redox status, pO2, pH, and microviscosity, based on variation of EPR spectral characteristics (i.e., intensity, linewidth, hyperfine splitting, and spectral shape of free radical probes. EPR imaging (EPRI) can obtain 1D-3D spatial distribution of such spectral components using several combinations of magnetic field gradients. Overhauser enhanced MRI (OMRI) is a double-resonance technique of electron and nuclear spins. Because the Overhauser enhancement depends on transverse relaxation rate of the electron spin, OMRI can provide pO2 information indirectly, along with a high-resolution MR image. MRI can also indirectly detect paramagnetic behaviors of free radical contrast agents. Imaging techniques and applications relating to paramagnetic species (i.e., EPRI, OMRI, and MRI) have the potential to obtain maximally 5D information (i.e., 3D spatial + 1D spectral + 1D temporal dimensions, theoretically). To obtain suitable dimensionality, several factors, such as the EPR spectral information, spatial resolution, temporal resolution, will have to be taken into account. For this review, the EPRI, OMRI, and MRI applications for the study biological systems were evaluated for researchers to apply the method of choice and the mode of measurements to specific experimental systems.
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Affiliation(s)
- Ken-ichiro Matsumoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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Som S, Potter LC, Ahmad R, Kuppusamy P. A parametric approach to spectral-spatial EPR imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 186:1-10. [PMID: 17276111 PMCID: PMC2020527 DOI: 10.1016/j.jmr.2006.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 12/12/2006] [Accepted: 12/16/2006] [Indexed: 05/13/2023]
Abstract
Continuous wave electron paramagnetic resonance imaging for in vivo mapping of spin distribution and spectral shape requires rapid data acquisition. A spectral-spatial imaging technique is presented that provides an order of magnitude reduction in acquisition time, compared to iterative tomographic reprojection. The proposed approach assumes that spectral shapes in the sample are well-approximated by members from a parametric family of functions. A model is developed for the spectra measured with magnetic field modulation. Parameters defining the spin distribution and spectral shapes are then determined directly from the measurements using maximum a posteriori probability estimation. The approach does not suffer approximation error from limited sweep width of the main magnetic field and explicitly incorporates the variability in signal-to-noise ratio versus strength of magnetic field gradient. The processing technique is experimentally demonstrated on a one-dimensional phantom containing a nitroxide spin label with constant g-factor. Using an L-band EPR spectrometer, spectral shapes and spin distribution are accurately recovered from two projections and a spectral window which is comparable to the maximum linewidth of the sample.
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Affiliation(s)
- Subhojit Som
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Lee C. Potter
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
- * Corresponding Author. Fax: +1-614-292-7596, E-mail address: (Lee C. Potter)
| | - Rizwan Ahmad
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
| | - Periannan Kuppusamy
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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Chan LW, Hapdey S, English S, Seidel J, Carson J, Sowers AL, Krishna MC, Green MV, Mitchell JB, Bacharach SL. The influence of tumor oxygenation on (18)F-FDG (fluorine-18 deoxyglucose) uptake: a mouse study using positron emission tomography (PET). Radiat Oncol 2006; 1:3. [PMID: 16722588 PMCID: PMC1436004 DOI: 10.1186/1748-717x-1-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 02/28/2006] [Indexed: 11/29/2022] Open
Abstract
Background This study investigated whether changing a tumor's oxygenation would alter tumor metabolism, and thus uptake of 18F-FDG (fluorine-18 deoxyglucose), a marker for glucose metabolism using positron emission tomography (PET). Results Tumor-bearing mice (squamous cell carcinoma) maintained at 37°C were studied while breathing either normal air or carbogen (95% O2, 5% CO2), known to significantly oxygenate tumors. Tumor activity was measured within an automatically determined volume of interest (VOI). Activity was corrected for the arterial input function as estimated from image and blood-derived data. Tumor FDG uptake was initially evaluated for tumor-bearing animals breathing only air (2 animals) or only carbogen (2 animals). Subsequently, 5 animals were studied using two sequential 18F-FDG injections administered to the same tumor-bearing mouse, 60 min apart; the first injection on one gas (air or carbogen) and the second on the other gas. When examining the entire tumor VOI, there was no significant difference of 18F-FDG uptake between mice breathing either air or carbogen (i.e. air/carbogen ratio near unity). However, when only the highest 18F-FDG uptake regions of the tumor were considered (small VOIs), there was a modest (21%), but significant increase in the air/carbogen ratio suggesting that in these potentially most hypoxic regions of the tumor, 18F-FDG uptake and hence glucose metabolism, may be reduced by increasing tumor oxygenation. Conclusion Tumor 18F-FDG uptake may be reduced by increases in tumor oxygenation and thus may provide a means to further enhance 18F-FDG functional imaging.
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Affiliation(s)
- Linda W Chan
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Sebastien Hapdey
- Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Sean English
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Jurgen Seidel
- Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Joann Carson
- Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Anastasia L Sowers
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Murali C Krishna
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Michael V Green
- Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - James B Mitchell
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Stephen L Bacharach
- Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
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Williams BB, Pan X, Halpern HJ. EPR imaging: the relationship between CW spectra acquired from an extended sample subjected to fixed stepped gradients and the Radon transform of the resonance density. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 174:88-96. [PMID: 15809176 DOI: 10.1016/j.jmr.2005.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Revised: 12/31/2004] [Indexed: 05/24/2023]
Abstract
EPR spectroscopy can be extended to a spectroscopic imaging modality by applying magnetic field gradients across the sample to encode spatial information in the measured spectra. In this work, we present a mathematical model of the EPR imaging process in terms of the Radon transform. We describe a model for electron paramagnetic resonance imaging, derive its explicit relationship to the Radon transform, and discuss several options for reconstructing the sample absorption and dispersion densities. An important extension to previous descriptions is the incorporation of large amplitude magnetic field modulation, which can be used to improve the signal-to-noise ratio for continuous wave signal acquisition. Magnetic field modulation is shown to cause well understood changes in the shapes of spectra in the reconstructed images, but does not affect the spatial resolution achieved in these images. Since many of the novel image reconstruction strategies and noise filtering algorithms that have been developed for other modalities start from this formalism, this work allows for their direct application to EPR imaging. This promises to lead to further improvements in EPR imaging techniques.
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Affiliation(s)
- Benjamin B Williams
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, USA
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Takeshita K, Ozawa T. Recent progress in in vivo ESR spectroscopy. JOURNAL OF RADIATION RESEARCH 2004; 45:373-384. [PMID: 15613782 DOI: 10.1269/jrr.45.373] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The generation of free radicals and redox status is related to various diseases and injuries that are related to radiation, aging, ischemia-reperfusion, and other oxidative factors. In vivo electron spin resonance (ESR) spectroscopy is noninvasive and detects durable free radicals in live animals. ESR spectrometers for in vivo measurements operate at a lower frequency (approximately 3.5 GHz, approximately 1 GHz, 700 MHz, and approximately 300 MHz) than usual (9-10 GHz). Several types of resonators have been designed to minimize the dielectric loss of electromagnetic waves caused by water in animal bodies. In vivo ESR spectroscopy and its imaging have been used to analyze radical generation, redox status, partial pressure of oxygen and other conditions in various disease and injury models related to oxidative stress with probes, such as nitroxyl radicals. Through these applications, the clarification of the mechanisms related to oxidative diseases (injuries) and the accumulation of basic data for radiological cancer therapy are now ongoing. In vivo ESR measurement is performed in about 10 laboratories worldwide, including ours. To introduce in vivo ESR spectroscopy to life scientists, this article reviews the recent progress of in vivo ESR spectroscopy in instrumentation and its application to the life sciences.
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Affiliation(s)
- Keizo Takeshita
- Redox Regulation Research Group, National Institute of Radiological Sciences, Chiba, Japan.
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Liu S, Shi H, Liu W, Furuichi T, Timmins GS, Liu KJ. Interstitial pO2 in ischemic penumbra and core are differentially affected following transient focal cerebral ischemia in rats. J Cereb Blood Flow Metab 2004; 24:343-9. [PMID: 15091115 DOI: 10.1097/01.wcb.0000110047.43905.01] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Stroke causes heterogeneous changes in tissue oxygenation, with a region of decreased blood flow, the penumbra, surrounding a severely damaged ischemic core. Treatment of acute ischemic stroke aims to save this penumbra before its irreversible damage by continued ischemia. However, effective treatment remains elusive due to incomplete understanding of processes leading to penumbral death. While oxygenation is central in ischemic neuronal death, it is unclear exactly what actual changes occur in interstitial oxygen tension (pO2) in ischemic regions during stroke, particularly the penumbra. Using the unique capability of in vivo electron paramagnetic resonance (EPR) oximetry to measure localized interstitial pO2, we measured both absolute values, and temporal changes of pO2 in ischemic penumbra and core during ischemia and reperfusion in a rat model. Ischemia rapidly decreased interstitial pO2 to 32% +/- 7.6% and 4% +/- 0.6% of pre-ischemic values in penumbra and core, respectively 1 hour after ischemia. Importantly, whilst reperfusion restored core pO2 close to its pre-ischemic value, penumbral pO2 only partially recovered. Hyperoxic treatment significantly increased penumbral pO2 during ischemia, but not in the core, and also increased penumbral pO2 during reperfusion. These divergent, important changes in pO2 in penumbra and core were explained by combined differences in cellular oxygen consumption rates and microcirculation conditions. We therefore demonstrate that interstitial pO2 in penumbra and core is differentially affected during ischemia and reperfusion, providing new insights to the pathophysiology of stroke. The results support normobaric hyperoxia as a potential early intervention to save penumbral tissue in acute ischemic stroke.
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Affiliation(s)
- Shimin Liu
- College of Pharmacy and Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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36
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Tarpey MM, Wink DA, Grisham MB. Methods for detection of reactive metabolites of oxygen and nitrogen: in vitro and in vivo considerations. Am J Physiol Regul Integr Comp Physiol 2004; 286:R431-44. [PMID: 14761864 DOI: 10.1152/ajpregu.00361.2003] [Citation(s) in RCA: 423] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Facile detection of reactive oxygen and nitrogen species in biologic systems is often problematic. This is a result of the numerous cellular mechanisms, both enzymatic and nonenzymatic involved in their catabolism/decomposition, the complex and overlapping nature of their reactivities, as well as the often limited intracellular access of detector systems. This review describes approaches to the direct and indirect measurement of different reactive metabolites of oxygen and nitrogen. Particular attention to a method's applicability for in vivo determinations will be addressed.
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Affiliation(s)
- Margaret M Tarpey
- Department of Anesthesiology, University of Alabama at Birmingham, 35294, USA
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37
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Anzai K, Saito K, Takeshita K, Takahashi S, Miyazaki H, Shoji H, Lee MCI, Masumizu T, Ozawa T. Assessment of ESR-CT imaging by comparison with autoradiography for the distribution of a blood-brain-barrier permeable spin probe, MC-PROXYL, to rodent brain. Magn Reson Imaging 2004; 21:765-72. [PMID: 14559341 DOI: 10.1016/s0730-725x(03)00118-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Blood-brain-barrier (BBB)-permeable, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-yloxy (MC-PROXYL) and BBB-impermeable carbamoyl-PROXYL were used to assess the ESR imaging technique by comparing with autoradiography. For this purpose, spin probes, 14C-labeled at their five-membered ring, [14C]MC-PROXYL and [14C]carbamoyl-PROXYL, were newly synthesized. These probes were i.p. or i.v. injected into rats and autoradiograms were recorded. The autoradiograms of rat head showed that [14C]MC-PROXYL distributed well in the brain compared to [14C]carbamoyl-PROXYL. In vivo ESR spectra and two-dimensional ESR images of isolated rat brain treated with MC- or carbamoyl-PROXYL also indicated the extensive distribution of MC-PROXYL but not carbamoyl-PROXYL in the rat brain. The three-dimensional ESR images of the head of rats and mice were consistent with the fact that MC-PROXYL but not carbamoyl-PROXYL is incorporated into the brain. The ESR-CT images were better for mice than rats. However, the quality of the ESR-CT images was still not satisfactory. Although the resolution and sensitivity of the ESR-CT images were worse than those of the autoradiographic images, the former technique has unique features and advantages; e.g., functional, noninvasive and three-dimensional detection.
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Affiliation(s)
- Kazunori Anzai
- National Institute of Radiological Sciences, Anagawa, Chiba 263-8555, Japan.
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38
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Lan M, Beghein N, Charlier N, Gallez B. Carbon blacks as EPR sensors for localized measurements of tissue oxygenation. Magn Reson Med 2004; 51:1272-8. [PMID: 15170849 DOI: 10.1002/mrm.20077] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
New electron paramagnetic resonance (EPR) oximetry probes were identified in the class of carbon black materials. These compounds exhibit very high oxygen sensitivity and favorable EPR characteristics for biological applications. At low pO(2), the linewidth is particularly sensitive to changes in oxygen tension (sensitivity of 750 mG/mmHg). The application of the probes for oximetry was demonstrated in vivo: the pO(2) was measured in muscle in which the blood flow was temporarily restricted as well as in tumor-bearing mice during a carbogen breathing challenge. The responsiveness to pO(2) was stable in muscle for at least 3 months. No toxicity was observed using these materials in cellular experiments and in histological studies performed 2, 7, and 28 days after implantation. In view of their EPR characteristics (high sensitivity) as well as the well-characterized production procedure that make them available on a large scale, these probes can be considered as very promising tools for future developments in EPR oximetry.
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Affiliation(s)
- Minbo Lan
- Laboratory of Medicinal Chemistry and Radiopharmacy, Université Catholique de Louvain, Brussels, Belgium
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39
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Gordillo GM, Schlanger R, Wallace WA, Bergdall V, Bartlett R, Sen CK. Protocols for topical and systemic oxygen treatments in wound healing. Methods Enzymol 2004; 381:575-85. [PMID: 15063699 DOI: 10.1016/s0076-6879(04)81037-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gayle M Gordillo
- Laboratory of Molecular Medicine, Department of Surgery, The Ohio State University Medical Center, Columbus, Ohio 43210, USA
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40
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Ilangovan G, Zweier JL, Kuppusamy P. Microximetry: simultaneous determination of oxygen consumption and free radical production using electron paramagnetic resonance spectroscopy. Methods Enzymol 2004; 381:747-62. [PMID: 15063710 DOI: 10.1016/s0076-6879(04)81048-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Govindasamy Ilangovan
- Biomedical EPR Spectroscopy & Imaging Center, The Ohio State University, Columbus, Ohio 43210, USA
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41
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Taube AG, Subramanian S, Murugesan R, Devasahayam N, Mitchell JB, Krishna MC, Cook JA. An application system for automation of constant-time radio frequency electron paramagnetic resonance imaging. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2003; 72:127-138. [PMID: 12941517 DOI: 10.1016/s0169-2607(02)00124-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A Windows based application system for data collection, Fourier reconstruction and analysis of pure phase encoded constant-time radio frequency electron paramagnetic resonance (EPR) images, is described. The graphical user interface (GUI) of the system was written in MATLAB version 5.0, using its built-in GUI utilities. Design considerations of the application system included speed, flexibility and user-friendly data display and analysis. To maximize the speed of image data collection, MATLAB's built-in C interface system, MEX was not used for data collection. Instead, MATLAB programs call the C programs from the DOS prompt directly, based on the data collection parameters entered through the GUI. Computational procedures included various digital signal-processing steps such as filtering, interpolation etc. for the Fourier reconstruction of 2D, and 3D EPR images from the pure phase encoded data. Examples of 2D images illustrating the performance of the system are presented. Although the application system has been developed for the specific purpose of EPR imaging, it can easily be adapted to other areas such as magnetic resonance microscopy as well.
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Affiliation(s)
- Andrew G Taube
- Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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42
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Matsumoto KI, Chandrika B, Lohman JAB, Mitchell JB, Krishna MC, Subramanian S. Application of continuous-wave EPR spectral-spatial image reconstruction techniques for in vivo oxymetry: Comparison of projection reconstruction and constant-time modalities. Magn Reson Med 2003; 50:865-74. [PMID: 14523974 DOI: 10.1002/mrm.10594] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this study we report the application of continuous-wave (CW) electron paramagnetic resonance (EPR) constant-time spectral spatial imaging (CTSSI) for in vivo oxymetry. 2D and 3D SSI studies of a phantom and live mice were carried out using projection reconstruction (PR) and constant-time (CT) modalities using a CW-EPR spectrometer/imager operating at 300 MHz frequency. Distortion of line shape, which is inherent in the PR method, was minimized by the CTSSI modality. It was also found that CTSSI offers improved noise reduction, restores a smoother line shape, and gives high convergence of estimated values. Spatial resolution was also improved by CTSSI, although fundamental spectral line-width broadening was observed. Although additional corrections are required for accurate estimations of spectral line width, CTSSI was able to demonstrate distinct differences in oxygen tension between a tumor and the normal legs of a C3H mouse. The PR method, on the other hand, was unable to make such a distinction unequivocally with the triarylmethyl spin probes. CTSSI promises to be a more suitable method for quantitative in vivo oxymetric studies using radiofrequency EPR imaging (EPRI).
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Affiliation(s)
- Ken-ichiro Matsumoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Lawler C, Suk WA, Pitt BR, Croix CMS, Watkins SC. Multimodal optical imaging. Am J Physiol Lung Cell Mol Physiol 2003; 285:L269-80. [PMID: 12851207 DOI: 10.1152/ajplung.00424.2002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The recent resurgence of interest in the use of intravital microscopy in lung research is a manifestation of extraordinary progress in visual imaging and optical microscopy. This review evaluates the tools and instrumentation available for a number of imaging modalities, with particular attention to recent technological advances, and addresses recent progress in use of optical imaging techniques in basic pulmonary research.1 Limitations of existing methods and anticipated future developments are also identified. Although there have also been major advances made in the use of magnetic resonance imaging, positron emission tomography, and X-ray and computed tomography to image intact lungs and while these technologies have been instrumental in advancing the diagnosis and treatment of patients, the purpose of this review is to outline developing optical methods that can be evaluated for use in basic research in pulmonary biology.
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Affiliation(s)
- Cindy Lawler
- National Institute of Environmental Health Sciences, Research Traingle Park, North Carolina 27709, USA
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44
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Abstract
Electron paramagnetic resonance (EPR) methods can be used to study tissue pO(2) (PtO(2)) in anesthetized or awake animals (EPR oximetry). The method takes advantage of the fact that some paramagnetic materials have an EPR linewidth that is sensitive to the pO(2) in which the material is located. This article provides an overview of the method of EPR oximetry using implanted particulate materials as the sensors of pO(2). Characteristics of these materials are described to help the reader understand the factors involved in choosing the optimum particulate material. Examples of biological studies are included that show how EPR oximetry may be used on both awake and anesthetized animals.
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Affiliation(s)
- Jeff F Dunn
- NMR and EPR Research Centers, Diagnostic Radiology, Dartmouth Medical School, Hanover, NH 03755, USA.
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45
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Elas M, Williams BB, Parasca A, Mailer C, Pelizzari CA, Lewis MA, River JN, Karczmar GS, Barth ED, Halpern HJ. Quantitative tumor oxymetric images from 4D electron paramagnetic resonance imaging (EPRI): methodology and comparison with blood oxygen level-dependent (BOLD) MRI. Magn Reson Med 2003; 49:682-91. [PMID: 12652539 DOI: 10.1002/mrm.10408] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This work presents a methodology for obtaining quantitative oxygen concentration images in the tumor-bearing legs of living C3H mice. The method uses high-resolution electron paramagnetic resonance imaging (EPRI). Enabling aspects of the methodology include the use of injectable, narrow, single-line triaryl methyl spin probes and an accurate model of overmodulated spectra. Both of these increase the signal-to-noise ratio (SNR), resulting in high resolution in space (1 mm)(3) and oxygen concentrations (approximately 3 torr). Thresholding at 15% the maximum spectral amplitude gives leg/tumor shapes that reproduce those in photographs. The EPRI appears to give reasonable oxygen partial pressures, showing hypoxia (approximately 0-6 torr, 0-10(3) Pa) in many of the tumor voxels. EPRI was able to detect statistically significant changes in oxygen concentrations in the tumor with administration of carbogen, although the changes were not increased uniformly. As a demonstration of the method, EPRI was compared with nearly concurrent (same anesthesia) T(2)*/blood oxygen level-dependent (BOLD) MRI. There was a good spatial correlation between EPRI and MRI. Homogeneous and heterogeneous T(2)*/BOLD MRI correlated well with the quantitative EPRI. This work demonstrates the potential for EPRI to display, at high spatial resolution, quantitative oxygen tension changes in the physiologic response to environmental changes.
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Affiliation(s)
- Martyna Elas
- Department of Radiation and Cellular Oncology, University of Chicago Medical Center, 5841 S. Maryland Avenue, Chicago, IL 60637, USA
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He G, Evalappan SP, Hirata H, Deng Y, Petryakov S, Kuppusamy P, Zweier JL. Mapping of the B1 field distribution of a surface coil resonator using EPR imaging. Magn Reson Med 2002; 48:1057-62. [PMID: 12465117 DOI: 10.1002/mrm.10302] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Surface coil resonators have been widely used to perform topical EPR spectroscopy. They are usually positioned adjacent to or implanted within the body. For EPR applications these resonators have a number of important advantages over other resonator designs due to their ease of sample accessibility, mechanical fabrication, implementation of electronic tuning and coupling functions, and low susceptibility to sample motions. However, a disadvantage is their B(1) field inhomogeneity, which limits their usefulness for 3D imaging applications. We show that this problem can be addressed by mapping and correcting the B(1) field distribution. We report the use of EPR imaging (EPRI) to map the B(1) distribution of a surface coil resonator. We show that EPRI provides a fast, accurate, and reliable technique to evaluate the B(1) distribution. 3D EPRI was performed on phantoms, prepared using three different saline concentrations, to obtain the B(1) distribution. The information obtained from the phantoms was used to correct the images of living animals. With the use of this B(1) correction technique, surface coil resonators can be applied to perform 3D mapping of the distribution of free radicals in biological samples and living systems.
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Affiliation(s)
- Guanglong He
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, The Ohio State University, College of Medicine, Columbus, Ohio 43210-1252, USA
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47
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Baudelet C, Gallez B. How does blood oxygen level-dependent (BOLD) contrast correlate with oxygen partial pressure (pO2) inside tumors? Magn Reson Med 2002; 48:980-6. [PMID: 12465107 DOI: 10.1002/mrm.10318] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Blood oxygen level-dependent (BOLD) contrast-based functional MRI (fMRI) has been reported as a method to assess the evolution of tumor oxygenation after hyperoxic treatments, because of its sensitivity to changes in blood flow and deoxyhemoglobin content. However a number of questions remain: 1) In view of tumor heterogeneity, how good is the correlation between the MR parameters in gradient-echo imaging (signal intensity (SI) or effective transverse relaxation time (T(*)(2))) and local tumor oxygen partial pressure (pO(2))? 2) Is the magnitude of the change in SI or T(*)(2) a quantitative marker for variation in pO(2)? 3) Is initial T(*)(2) a good marker for initial pO(2)? To address these questions, murine tumors were imaged during respiratory challenges at 4.7 Tesla, using fiber-optic microprobes to simultaneously acquire tumor pO(2) and erythrocyte flux. The BOLD signal response (SI and T(*)(2)) was temporally correlated with changes in pO(2). However, the magnitude of the signal bore no absolute relation to pO(2) across tumors, i.e., a given change in SI corresponded to a 25 mmHg pO(2) change in one tumor, but to a 100 mmHg change in another. The initial T(*)(2) value did not reliably predict tumor oxygenation at the beginning of the experiment. In conclusion, the major advantages of the technique include noninvasiveness, high spatial resolution, and real-time detection of pO(2) fluctuations. Information afforded by the BOLD imaging technique is qualitative in nature and may be combined with other techniques capable of providing an absolute measure of pO(2).
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Affiliation(s)
- Christine Baudelet
- Laboratory of Medicinal Chemistry and Radiopharmacy, Université Catholique de Louvain, Brussels, Belgium
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48
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Ilangovan G, Li H, Zweier JL, Krishna MC, Mitchell JB, Kuppusamy P. In vivo measurement of regional oxygenation and imaging of redox status in RIF-1 murine tumor: effect of carbogen-breathing. Magn Reson Med 2002; 48:723-30. [PMID: 12353291 DOI: 10.1002/mrm.10254] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of this study was to noninvasively monitor tumor oxygenation and redox status during hyperoxygenation treatment, such as carbogen-breathing, in a murine tumor model using in vivo electron paramagnetic resonance (EPR) spectroscopy and imaging techniques. The study was performed using implanted lithium phthalocyanine (LiPc) microcrystals as the oximetry probe and 3-carbamoylproxyl (3-CP) as the redox probe in RIF-1 tumors implanted in the upper hind leg of C3H mice. Repetitive measurements of pO(2) from the same tumors as a function of tumor growth (8-24 mm in size) showed that the tumors were hypoxic and that the tumor pO(2) values were decreasing with tumor growth. Carbogen-breathing mostly showed an increase in the tumor oxygenation, although there were considerable variations in the magnitude of change among the tumors. The pharmacokinetic studies with 3-CP showed a significant decrease in the overall tumor reduction status in the carbogen-breathing mice. Spatially resolved (imaging) pharmacokinetic data over the tumor volume were obtained to visualize the distribution of the redox status within the tumor. The redox images of the tumor in the air-breathing mice showed significant heterogeneity in the magnitude and spatial distribution of reducing equivalents. On carbogen-breathing the tissue reduction status decreased considerably, with a concomitant decrease in the heterogeneity of distribution of the redox status. The results suggest that 1) carbogen-breathing considerably enhances tissue oxygenation and significantly decreases the redox status in RIF-1 tumor, and 2) changes in the magnitude and distribution of the redox status within the tumor volume during carbogen-breathing are correlated with the increased tissue oxygenation.
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Affiliation(s)
- Govindasamy Ilangovan
- EPR Center, Division of Cardiology, Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
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49
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Subramanian S, Yamada KI, Irie A, Murugesan R, Cook JA, Devasahayam N, Van Dam GM, Mitchell JB, Krishna MC. Noninvasive in vivo oximetric imaging by radiofrequency FT EPR. Magn Reson Med 2002; 47:1001-8. [PMID: 11979580 DOI: 10.1002/mrm.10133] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A novel method, called relaxo-oximetry, for rapid spatially resolved in vivo measurements of oxygen concentration using time-domain radiofrequency (RF) electron paramagnetic resonance (EPR) is described. Time-domain data from triaryl methyl (TAM)-based single-electron contrast agents were processed by systematic deletion of the initial time points to arrive at T2*-weighted discrimination of signal amplitudes. In experiments involving phantoms, the line widths [ approximately (T2*)(-1)] increased as a function of oxygen, and the slope (line width/pO(2)) was the same for both absorption- and magnitude-mode line shapes. Line widths derived from T2* weighting and the computed pO(2) values agreed favorably with the measured ones from phantoms of known oxygen tension. In vivo relaxo-oximetry was performed on C3H mice, and it was found that the liver was more hypoxic than the kidneys. For tumors, 2D oxygen maps were generated while the animal breathed room air or Carbogen(R) (95% O(2)/5% CO(2)). Carbogen(R) enhanced oxygen concentration within the tumor, and the pO(2) histograms showed considerable heterogeneity. Clark electrode oxygen measurements on organs and tumors were in good agreement with tissue oxygen measurements done by relaxo-oximetry. Thus, from a single spatial image data set, pO(2) measurements can be done noninvasively by relaxo-oximetry, and 3D imaging can be performed in less than 3 min.
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Affiliation(s)
- Sankaran Subramanian
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1002, USA
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50
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Krishna MC, English S, Yamada K, Yoo J, Murugesan R, Devasahayam N, Cook JA, Golman K, Ardenkjaer-Larsen JH, Subramanian S, Mitchell JB. Overhauser enhanced magnetic resonance imaging for tumor oximetry: coregistration of tumor anatomy and tissue oxygen concentration. Proc Natl Acad Sci U S A 2002; 99:2216-21. [PMID: 11854518 PMCID: PMC122345 DOI: 10.1073/pnas.042671399] [Citation(s) in RCA: 256] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An efficient noninvasive method for in vivo imaging of tumor oxygenation by using a low-field magnetic resonance scanner and a paramagnetic contrast agent is described. The methodology is based on Overhauser enhanced magnetic resonance imaging (OMRI), a functional imaging technique. OMRI experiments were performed on tumor-bearing mice (squamous cell carcinoma) by i.v. administration of the contrast agent Oxo63 (a highly derivatized triarylmethyl radical) at nontoxic doses in the range of 2-7 mmol/kg either as a bolus or as a continuous infusion. Spatially resolved pO(2) (oxygen concentration) images from OMRI experiments of tumor-bearing mice exhibited heterogeneous oxygenation profiles and revealed regions of hypoxia in tumors (<10 mmHg; 1 mmHg = 133 Pa). Oxygenation of tumors was enhanced on carbogen (95% O(2)/5% CO(2)) inhalation. The pO(2) measurements from OMRI were found to be in agreement with those obtained by independent polarographic measurements using a pO(2) Eppendorf electrode. This work illustrates that anatomically coregistered pO(2) maps of tumors can be readily obtained by combining the good anatomical resolution of water proton-based MRI, and the superior pO(2) sensitivity of EPR. OMRI affords the opportunity to perform noninvasive and repeated pO(2) measurements of the same animal with useful spatial (approximately 1 mm) and temporal (2 min) resolution, making this method a powerful imaging modality for small animal research to understand tumor physiology and potentially for human applications.
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Affiliation(s)
- Murali C Krishna
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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