How In Vivo EPR Measures and Images Oxygen

Epel, Boris; Redler, Gage; Halpern, Howard J.

doi:10.1007/978-1-4939-0620-8_15

Cited by 30 publications

(28 citation statements)

References 19 publications

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“…After the invention of the trityl probe Oxo63, which shows high biostability, low toxicity, and a single peak with extremely narrow linewidth due to the position of the unpaired electron three bonds away from proton atoms in its chemical structure, EPRI for oximetry became feasible. Currently, successful EPRI oximetry with pulsed EPR is performed by sampling dimensional k space using projection‐based or single‐point imaging (SPI) methods . In our laboratory, substantial mechanical development enabled high spatial resolution (~200 μm) and temporal resolution (~3 min) using pulsed EPR with SPI …”

Section: Epr Po2 Imagingmentioning

confidence: 99%

Direct and indirect assessment of cancer metabolism explored by MRI

et al. 2018

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Magnetic resonance-based approaches to obtain metabolic information on cancer have been explored for decades. Electron paramagnetic resonance (EPR) has been developed to pursue metabolic profiling and successfully used to monitor several physiologic parameters such as pO , pH, and redox status. All these parameters are associated with pathophysiology of various diseases. Especially in oncology, cancer hypoxia has been intensively studied because of its relationship with metabolic alterations, acquiring treatment resistance, or a malignant phenotype. Thus, pO imaging leads to an indirect metabolic assessment in this regard. Proton electron double-resonance imaging (PEDRI) is an imaging technique to visualize EPR by using the Overhauser effect. Most biological parameters assessed in EPR can be visualized using PEDRI. However, EPR and PEDRI have not been evaluated sufficiently for clinical application due to limitations such as toxicity of the probes or high specific absorption rate. Hyperpolarized (HP) C MRI is a novel imaging technique that can directly visualize the metabolic profile. Production of metabolites of the HP C probe delivered to target tissue are evaluated in this modality. Unlike EPR or PEDRI, which require the injection of radical probes, C MRI requires a probe that can be physiologically metabolized and efficiently hyperpolarized. Among several methods for hyperpolarizing probes, dissolution dynamic nuclear hyperpolarization is a widely used technique for in vivo imaging. Pyruvate is the most suitable probe for HP C MRI because it is part of the glycolytic pathway and the high efficiency of pyruvate-to-lactate conversion is a distinguishing feature of cancer. Its clinical applicability also makes it a promising metabolic imaging modality. Here, we summarize the applications of these indirect and direct MR-based metabolic assessments focusing on pO and pyruvate-to-lactate conversion. The two parameters are strongly associated with each other, hence the acquired information is potentially interchangeable when evaluating treatment response to oxygen-dependent cancer therapies.

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Section: Epr Po2 Imagingmentioning

confidence: 99%

Direct and indirect assessment of cancer metabolism explored by MRI

et al. 2018

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“…A detailed description of EPR oximetry spectroscopy and imaging is available in literature 102425555657. Briefly, EPR cannot directly detect O 2 at 37°C even though O 2 has two unpaired electrons.…”

Section: Oximetry Methods For Cerebral Po2 Measurementsmentioning

confidence: 99%

“…Quantitative and repetitive measurements of O 2 levels in deeper and specific cerebral tissue, in vivo and in real time, remains a technical challenge and efforts have been made to improve methods for evaluating cerebral pO 2 . Among the common methods, electron paramagnetic resonance (EPR), a technique that uniquely detects and characterizes molecules with unpaired electrons, can measure several different, unique and distinctive biological parameters including tissue pO 2 in vivo and in real time 1516171819202122232425…”

Section: Introductionmentioning

confidence: 99%

In vivo electron paramagnetic resonance oximetry and applications in the brain

Weaver

Liu

2017

Med Gas Res

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Molecular oxygen (O2) is essential to brain function and mechanisms necessary to regulate variations in delivery or utilization of O2 are crucial to support normal brain homeostasis, physiology and energy metabolism. Any imbalance in cerebral tissue partial pressure of O2 (pO2) levels may lead to pathophysiological complications including increased reactive O2 species generation leading to oxidative stress when tissue O2 level is too high or too low. Accordingly, the need for oximetry methods, which assess cerebral pO2 in vivo and in real time, is imperative to understand the role of O2 in various metabolic and disease states, including the effects of treatment and therapy options. In this review, we provide a brief overview of the common in vivo oximetry methodologies for measuring cerebral pO2. We discuss the advantages and limitations of oximetry methodologies to measure cerebral pO2 in vivo followed by a more in-depth review of electron paramagnetic resonance oximetry spectroscopy and imaging using several examples of current electron paramagnetic resonance oximetry applications in the brain.

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“…A new type of oxygen sensitive macroscopic probe (oxygen-sensing paramagnetic lithium crystals encapsulated in a biocompatible polymer, called OxyChips) was developed [106] and is already at the stage of preclinical evaluation for long-term EPR oximetry [107,108]. All these approaches were successfully used for in vivo oximetry [109,110] and in vivo imaging [109,111]. They also present new opportunities for studies of photosynthesis but were not yet applied for these studies.…”

Section: IIImentioning

confidence: 99%

Oxygenic photosynthesis: EPR study of photosynthetic electron transport and oxygen-exchange, an overview

Тихонов

Subczynski

2018

Cell Biochem Biophys

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In this review, we consider the applications of electron paramagnetic resonance (EPR) methods to the study of the relationships between the electron transport and oxygen-exchange processes in photosynthetic systems of oxygenic type. One of the purposes of this article is to encourage scientists to use the advantageous EPR oximetry approaches to study oxygen-related electron transport processes in photosynthetic systems. The structural organization of the photosynthetic electron transfer chain and the EPR approaches to the measurements of molecular oxygen (O 2) with O 2-sensitive species (nitroxide spin labels and solid paramagnetic particles) are briefly reviewed. In solution, the collision of O 2 with spin probes causes the broadening of their EPR spectra and the reduction of their spin-lattice relaxation times. Based on these effects, tools for measuring O 2 concentration and O 2 diffusion in biological systems have been developed. These methods, named "spin-label oximetry," include not only nitroxide spin labels, but also other stable free radicals with narrow EPR lines, as well as particulate probes with EPR spectra sensitive to molecular oxygen (lithium phthalocyanine, coals, and India ink). Applications of EPR approaches for measuring O 2 evolution and consumption are illustrated using examples of photosynthetic systems of oxygenic type, chloroplasts in situ (green leaves), and cyanobacteria.

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How In Vivo EPR Measures and Images Oxygen

Cited by 30 publications

References 19 publications

Direct and indirect assessment of cancer metabolism explored by MRI

Direct and indirect assessment of cancer metabolism explored by MRI

In vivo electron paramagnetic resonance oximetry and applications in the brain

Oxygenic photosynthesis: EPR study of photosynthetic electron transport and oxygen-exchange, an overview

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