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Barakat RM, Turcani M, Al-Khaledi G, Kilarkaje N, Al-Sarraf H, Sayed Z, Redzic Z. Low oxygen in inspired air causes severe cerebrocortical hypoxia and cell death in the cerebral cortex of awake rats. Neurosci Lett 2024; 818:137515. [PMID: 37865187 DOI: 10.1016/j.neulet.2023.137515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 09/12/2023] [Accepted: 10/09/2023] [Indexed: 10/23/2023]
Abstract
Type 1 respiratory failure (T1RF) is associated with secondary acute brain injury (sABI). The underlying mechanisms of sABI could include injury to brain cells mediated either by hypoxia or by lung injury-triggered inflammation. To elucidate to what extent T1RF causes hypoxia and a consequent hypoxic injury in the brain in the absence of lung injury, we exposed healthy, conscious Sprague-Dawley rats to 48 h long low partial pressure of O2 in inspired air (PiO2) (7.5-8 % O2 in N2, CO2 < 0.5 %, normal barometric pressure) and measured the partial pressure of oxygen in the premotor cortex (PtO2), cerebral blood flow (CBF), lactate concentrations, and cell death. Low PiO2 significantly affected PtO2, which was 52.3 (SD 2.1) mmHg when PiO2 was normal but declined to 6.4 (SD 3.8) mmHg when PiO2 was low for 1 h. This was accompanied by increased lactate concentrations in plasma, CSF, and premotor cortex. Low PiO2 elevated the number of dead cells in the cerebral cortex from 5.6 (SD 4.8) % (when PiO2 was normal) to 20.5 (SD 4.1) % and 32.37 (SD 6.5) % after 24 h and 48 h exposure to low PiO2, respectively. The Mann-Kendall test could not detect any monotonic increase or decrease in pial blood flow during the 48 h exposure to low PiO2. In summary, our findings suggest that exposure to low PiO2 caused a severe hypoxia in the cerebral cortex, which triggers a massive cell death. Since these conditions mimic T1RF, hypoxic injury could be an important underlying cause of T1RF-induced sABI.
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Affiliation(s)
- Rawan M Barakat
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Marian Turcani
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Ghanim Al-Khaledi
- Department of Pharmacology, College of Medicine, Kuwait University, Kuwait
| | | | - Hameed Al-Sarraf
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zeinab Sayed
- Department of Physiology, College of Medicine, Kuwait University, Kuwait
| | - Zoran Redzic
- Department of Physiology, College of Medicine, Kuwait University, Kuwait.
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The Challenges of O 2 Detection in Biological Fluids: Classical Methods and Translation to Clinical Applications. Int J Mol Sci 2022; 23:ijms232415971. [PMID: 36555613 PMCID: PMC9786805 DOI: 10.3390/ijms232415971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/10/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Dissolved oxygen (DO) is deeply involved in preserving the life of cellular tissues and human beings due to its key role in cellular metabolism: its alterations may reflect important pathophysiological conditions. DO levels are measured to identify pathological conditions, explain pathophysiological mechanisms, and monitor the efficacy of therapeutic approaches. This is particularly relevant when the measurements are performed in vivo but also in contexts where a variety of biological and synthetic media are used, such as ex vivo organ perfusion. A reliable measurement of medium oxygenation ensures a high-quality process. It is crucial to provide a high-accuracy, real-time method for DO quantification, which could be robust towards different medium compositions and temperatures. In fact, biological fluids and synthetic clinical fluids represent a challenging environment where DO interacts with various compounds and can change continuously and dynamically, and further precaution is needed to obtain reliable results. This study aims to present and discuss the main oxygen detection and quantification methods, focusing on the technical needs for their translation to clinical practice. Firstly, we resumed all the main methodologies and advancements concerning dissolved oxygen determination. After identifying the main groups of all the available techniques for DO sensing based on their mechanisms and applicability, we focused on transferring the most promising approaches to a clinical in vivo/ex vivo setting.
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Weaver J, Liu KJ. A Review of Low-Frequency EPR Technology for the Measurement of Brain pO2 and Oxidative Stress. APPLIED MAGNETIC RESONANCE 2021; 52:1379-1394. [PMID: 35340811 PMCID: PMC8945541 DOI: 10.1007/s00723-021-01384-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/24/2021] [Accepted: 06/30/2021] [Indexed: 06/14/2023]
Abstract
EPR can uniquely measure paramagnetic species. Although commercial EPR was introduced in 1950s, the early studies were mostly restricted to chemicals in solution or cellular experiments using X-band EPR equipment. Due to its limited penetration (<1 mm), experiments with living animals were almost impossible. To overcome these difficulties, Swartz group, along with several other leaders in field, pioneered the technology of low frequency EPR (e.g., L-band, 1-2 GHz). The development of low frequency EPR and the associated probes have dramatically expanded the application of EPR technology into the biomedical research field, providing answers to important scientific questions by measuring specific parameters that are impossible or very difficult to obtain by other approaches. In this review, which is aimed at highlighting the seminal contribution from Swartz group over the last several decades, we will focus on the development of EPR technology that was designed to deal with the potential challenges arising from conducting EPR spectroscopy in living animals. The second half of the review will be concentrated on the application of low frequency EPR in measuring cerebral tissue pO2 changes and oxidative stress in various physiological and pathophysiological conditions in the brain of animal disease models.
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Affiliation(s)
- John Weaver
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Ke Jian Liu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
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Impact of Inhibition of the Mitochondrial Pyruvate Carrier on the Tumor Extracellular pH as Measured by CEST-MRI. Cancers (Basel) 2021; 13:cancers13174278. [PMID: 34503089 PMCID: PMC8428345 DOI: 10.3390/cancers13174278] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/22/2021] [Accepted: 07/30/2021] [Indexed: 12/11/2022] Open
Abstract
(1) Background: The acidosis of the tumor micro-environment may have profound impact on cancer progression and on the efficacy of treatments. In the present study, we evaluated the impact of a treatment with UK-5099, a mitochondrial pyruvate carrier (MPC) inhibitor on tumor extracellular pH (pHe); (2) Methods: glucose consumption, lactate secretion and extracellular acidification rate (ECAR) were measured in vitro after exposure of cervix cancer SiHa cells and breast cancer 4T1 cells to UK-5099 (10 µM). Mice bearing the 4T1 tumor model were treated daily during four days with UK-5099 (3 mg/kg). The pHe was evaluated in vivo using either chemical exchange saturation transfer (CEST)-MRI with iopamidol as pHe reporter probe or 31P-NMR spectroscopy with 3-aminopropylphosphonate (3-APP). MR protocols were applied before and after 4 days of treatment; (3) Results: glucose consumption, lactate release and ECAR were increased in both cell lines after UK-5099 exposure. CEST-MRI showed a significant decrease in tumor pHe of 0.22 units in UK-5099-treated mice while there was no change over time for mice treated with the vehicle. Parametric images showed a large heterogeneity in response with 16% of voxels shifting to pHe values under 7.0. In contrast, 31P-NMR spectroscopy was unable to detect any significant variation in pHe; (4) Conclusions: MPC inhibition led to a moderate acidification of the extracellular medium in vivo. CEST-MRI provided high resolution parametric images (0.44 µL/voxel) of pHe highlighting the heterogeneity of response within the tumor when exposed to UK-5099.
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Dudylina AL, Ivanova MV, Kalatanova AV, Kalenikova EI, Makarov VG, Makarova MN, Shumaev KB, Ruuge EK. The Generation of Superoxide Radicals by Cardiac Mitochondria and the Antioxidant Effect of the Water-Soluble Form of Ubiquinol-10. Biophysics (Nagoya-shi) 2019. [DOI: 10.1134/s0006350919020052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Superoxide Formation in Cardiac Mitochondria and Effect of Phenolic Antioxidants. Cell Biochem Biophys 2018; 77:99-107. [PMID: 30218405 DOI: 10.1007/s12013-018-0857-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 09/04/2018] [Indexed: 12/13/2022]
Abstract
Since mitochondria are the main cellular source of reactive oxygen species, it is important to study the effect of dietary phenolic compounds on the level of ROS in these organelles. Using the EPR spectroscopy and TIRON probe, the ability of the investigated phenols (quercetin, rutin, caffeic acid, curcumin, and resveratrol) to scavenge superoxide anion radicals generated by isolated heart mitochondria of Wistar rats under variable oxygen partial pressure was studied. It was shown that during a 10 min incubation, caffeic acid in concentrations of 10-500 μM most effectively scavenged superoxide radicals formed in the complex III of the mitochondrial respiratory chain. A comparable antioxidant effect of rutin under these experimental conditions was observed at higher concentrations of 1-10 mM. The antioxidant activity of quercetin in the concentration range of 10-500 μM during the first minutes of incubation was higher than that of caffeic acid. Of the phenolic compounds studied, curcumin had the least effect on the superoxide radicals.
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Sullender CT, Mark AE, Clark TA, Esipova TV, Vinogradov SA, Jones TA, Dunn AK. Imaging of cortical oxygen tension and blood flow following targeted photothrombotic stroke. NEUROPHOTONICS 2018; 5:035003. [PMID: 30137881 PMCID: PMC6062776 DOI: 10.1117/1.nph.5.3.035003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/02/2018] [Indexed: 05/24/2023]
Abstract
We present a dual-modality imaging system combining laser speckle contrast imaging and oxygen-dependent quenching of phosphorescence to simultaneously map cortical blood flow and oxygen tension ( pO 2 ) in mice. Phosphorescence signal localization is achieved through the use of a digital micromirror device (DMD) that allows for selective excitation of arbitrary regions of interest. By targeting both excitation maxima of the oxygen-sensitive Oxyphor PtG4, we are able to examine the effects of excitation wavelength on the measured phosphorescence lifetime. We demonstrate the ability to measure the differences in pO 2 between arteries and veins and large changes during a hyperoxic challenge. We dynamically monitor blood flow and pO 2 during DMD-targeted photothrombotic occlusion of an arteriole and highlight the presence of an ischemia-induced depolarization. Chronic tracking of the ischemic lesion over eight days revealed a rapid recovery, with the targeted vessel fully reperfusing and pO 2 returning to baseline values within five days. This system has broad applications for studying the acute and chronic pathophysiology of ischemic stroke and other vascular diseases of the brain.
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Affiliation(s)
- Colin T. Sullender
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Andrew E. Mark
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Taylor A. Clark
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Tatiana V. Esipova
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Theresa A. Jones
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Andrew K. Dunn
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
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Shumaev KB, Dudylina AL, Ivanova MV, Pugachenko IS, Ruuge EK. Dinitrosyl iron complexes: Formation and antiradical action in heart mitochondria. Biofactors 2018; 44:237-244. [PMID: 29469215 DOI: 10.1002/biof.1418] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 01/25/2018] [Indexed: 02/02/2023]
Abstract
Mitochondria are widely known as a major source of reactive oxygen and nitrogen species for the cardiovascular system. Numerous studies established that superoxide anion radical production by heart mitochondria is only slightly suppressed under conditions of deep hypoxia, but is completely blocked under anoxia. It was found also that dinitrosyl iron complexes (DNIC) compare favourably with other physiologically active derivatives of nitric oxide (NO). DNIC with glutathione effectively scavenge superoxide radicals generated by mitochondria at different partial pressures of oxygen. Under conditions of simulated hypoxia, the synthesis of thiol-containing DNIC takes place in mitochondria and is concomitant with a significant decrease in the concentration of NO metabolites at the reoxygenation step. Free NO required for DNIC synthesis is generated in the reaction of S-nitrosothiols with superoxide or during single-electron oxidation of the nitroxyl radical (HNO) by coenzyme Q. Plausible mechanisms of antiradical effects of DNIC and their protective role in oxidative stress induced by hypoxia/reoxygenation of myocardial tissues are considered. © 2018 BioFactors, 44(3):237-244, 2018.
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Affiliation(s)
- Konstantin B Shumaev
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, 119071, Russia
- National Medical Research Centre for Cardiology, Moscow, 121552, Russia
| | - Arina L Dudylina
- Faculty of Physics, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Marina V Ivanova
- National Medical Research Centre for Cardiology, Moscow, 121552, Russia
| | - Igor S Pugachenko
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, 119071, Russia
| | - Enno K Ruuge
- National Medical Research Centre for Cardiology, Moscow, 121552, Russia
- Faculty of Physics, Lomonosov Moscow State University, Moscow, 119234, Russia
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Dudylina AL, Ivanova MV, Shumaev KB, Ruuge EK. The generation of superoxide radicals by complex III in heart mitochondria and the antioxidant effect of dinitrosyl iron complexes at different partial pressures of oxygen. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916020032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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10
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Desmet CM, Lafosse A, Vériter S, Porporato PE, Sonveaux P, Dufrane D, Levêque P, Gallez B. Application of Electron Paramagnetic Resonance (EPR) Oximetry to Monitor Oxygen in Wounds in Diabetic Models. PLoS One 2015; 10:e0144914. [PMID: 26659378 PMCID: PMC4679295 DOI: 10.1371/journal.pone.0144914] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/26/2015] [Indexed: 11/18/2022] Open
Abstract
A lack of oxygen is classically described as a major cause of impaired wound healing in diabetic patients. Even if the role of oxygen in the wound healing process is well recognized, measurement of oxygen levels in a wound remains challenging. The purpose of the present study was to assess the value of electron paramagnetic resonance (EPR) oximetry to monitor pO2 in wounds during the healing process in diabetic mouse models. Kinetics of wound closure were carried out in streptozotocin (STZ)-treated and db/db mice. The pO2 was followed repeatedly during the healing process by 1 GHz EPR spectroscopy with lithium phthalocyanine (LiPc) crystals used as oxygen sensor in two different wound models: a full-thickness excisional skin wound and a pedicled skin flap. Wound closure kinetics were dramatically slower in 12-week-old db/db compared to control (db/+) mice, whereas kinetics were not statistically different in STZ-treated compared to control mice. At the center of excisional wounds, measurements were highly influenced by atmospheric oxygen early in the healing process. In pedicled flaps, hypoxia was observed early after wounding. While reoxygenation occurred over time in db/+ mice, hypoxia was prolonged in the diabetic db/db model. This observation was consistent with impaired healing and microangiopathies observed using intravital microscopy. In conclusion, EPR oximetry using LiPc crystals as the oxygen sensor is an appropriate technique to follow wound oxygenation in acute and chronic wounds, in normal and diabetic animals. Nevertheless, the technique is limited for measurements in pedicled skin flaps and cannot be applied to excisional wounds in which diffusion of atmospheric oxygen significantly affects the measurements.
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Affiliation(s)
- Céline M. Desmet
- Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Aurore Lafosse
- Endocrine Cell Therapy Unit, Center of Tissue/Cell Therapy, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium
- Plastic and Reconstructive Surgery Unit, Cliniques Universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium
| | - Sophie Vériter
- Endocrine Cell Therapy Unit, Center of Tissue/Cell Therapy, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium
| | - Paolo E. Porporato
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Pierre Sonveaux
- Pole of Pharmacology, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Denis Dufrane
- Endocrine Cell Therapy Unit, Center of Tissue/Cell Therapy, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium
| | - Philippe Levêque
- Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Bernard Gallez
- Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
- * E-mail:
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Roussakis E, Li Z, Nichols AJ, Evans CL. Sauerstoffmessung in der Biomedizin - von der Makro- zur Mikroebene. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201410646] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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12
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Roussakis E, Li Z, Nichols AJ, Evans CL. Oxygen-Sensing Methods in Biomedicine from the Macroscale to the Microscale. Angew Chem Int Ed Engl 2015; 54:8340-62. [DOI: 10.1002/anie.201410646] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/05/2015] [Indexed: 12/15/2022]
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Zhong J, Sakaki M, Okada H, Ahrens ET. In vivo intracellular oxygen dynamics in murine brain glioma and immunotherapeutic response of cytotoxic T cells observed by fluorine-19 magnetic resonance imaging. PLoS One 2013; 8:e59479. [PMID: 23667419 PMCID: PMC3648573 DOI: 10.1371/journal.pone.0059479] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 02/14/2013] [Indexed: 12/31/2022] Open
Abstract
Noninvasive biomarkers of anti-tumoral efficacy are of great importance to the development of therapeutic agents. Tumor oxygenation has been shown to be an important indicator of therapeutic response. We report the use of intracellular labeling of tumor cells with perfluorocarbon (PFC) molecules, combined with quantitative ¹⁹F spin-lattice relaxation rate (R₁) measurements, to assay tumor cell oxygen dynamics in situ. In a murine central nervous system (CNS) GL261 glioma model, we visualized the impact of Pmel-1 cytotoxic T cell immunotherapy, delivered intravenously, on intracellular tumor oxygen levels. GL261 glioma cells were labeled ex vivo with PFC and inoculated into the mouse striatum. The R₁ of ¹⁹F labeled cells was measured using localized single-voxel magnetic resonance spectroscopy, and the absolute intracellular partial pressure of oxygen (pO₂) was ascertained. Three days after tumor implantation, mice were treated with 2×10⁷ cytotoxic T cells intravenously. At day five, a transient spike in pO₂ was observed indicating an influx of T cells into the CNS and putative tumor cell apoptosis. Immunohistochemistry and quantitative flow cytometry analysis confirmed that the pO₂ was causally related to the T cells infiltration. Surprisingly, the pO₂ spike was detected even though few (∼4×10⁴) T cells actually ingress into the CNS and with minimal tumor shrinkage. These results indicate the high sensitivity of this approach and its utility as a non-invasive surrogate biomarker of anti-cancer immunotherapeutic response in preclinical models.
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Affiliation(s)
- Jia Zhong
- Department of Biological Sciences and Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Masashi Sakaki
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Brain Tumor Program, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, United States of America
| | - Hideho Okada
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Brain Tumor Program, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, United States of America
| | - Eric T. Ahrens
- Department of Biological Sciences and Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
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Dyson A, Simon F, Seifritz A, Zimmerling O, Matallo J, Calzia E, Radermacher P, Singer M. Bladder tissue oxygen tension monitoring in pigs subjected to a range of cardiorespiratory and pharmacological challenges. Intensive Care Med 2012; 38:1868-76. [PMID: 23052956 DOI: 10.1007/s00134-012-2712-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 09/06/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE A fall in tissue oxygen tension (tPO(2)) is an early indicator of organ hypoxia in both patients and animal models. We previously demonstrated the utility of bladder tPO(2) in various rodent shock models. As a prelude to clinical testing, we aimed to provide further validation of bladder tPO(2) monitoring in a large animal model undergoing a range of cardiorespiratory insults and vasoactive drug interventions. METHODS Anaesthetized, mechanically ventilated, instrumented female pigs (n = 8) were subjected to a range of short-term cardiorespiratory (changes in inspired oxygen concentration (FiO(2)), haemorrhage, positive end-expiratory pressure) and pharmacologic (inotrope, pressor) challenges. Global haemodynamics, arterial and pulmonary blood gases and bladder tPO(2) were measured before and after each challenge. RESULTS Bladder tPO(2) values fell in line with increasing degrees of hypoxaemia and haemorrhage, and were restored during resuscitation. These changes often preceded those seen in global haemodynamics, arterial base excess and lactate. The rise in bladder tPO(2) with hyperoxia, performed as an oxygen challenge test, was incrementally blunted by progressive haemorrhage. Dobutamine and norepinephrine both increased cardiac output and global O(2) delivery, but had no effect on bladder tPO(2) or lactataemia in these healthy pigs. CONCLUSIONS In this pig model bladder tPO(2) provides a sensitive indicator of organ hypoxia compared to traditional biochemical markers during various cardiorespiratory challenges. This technique offers a potentially useful tool for clinical monitoring.
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Affiliation(s)
- Alex Dyson
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, Cruciform Building, Gower St, London, WC1E 6BT, UK.
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Krishna MC, Matsumoto S, Yasui H, Saito K, Devasahayam N, Subramanian S, Mitchell JB. Electron Paramagnetic Resonance Imaging of Tumor pO2. Radiat Res 2012; 177:376-86. [DOI: 10.1667/rr2622.1] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
PURPOSE OF REVIEW The holy grail of circulatory monitoring is an accurate, continuous and relatively noninvasive means of assessing the adequacy of organ perfusion. This could be then advantageously used to direct therapeutic interventions to prevent both under-treatment and over-treatment and thus improve outcomes. However, in view of the heterogeneous response (adaptive or maladaptive) of different organs to various shock states, any monitor of perfusion adequacy cannot reflect every organ system, but should at least detect early deterioration in a 'canary' organ. Tissue oxygen tension reflects the balance between local oxygen supply and demand, and could thus be a potentially useful monitoring modality. This article examines the different technologies available and reviews the current literature regarding its utility as a monitor. RECENT FINDINGS Tissue oxygen tension, measured at a variety of sites in both human and laboratory studies, does appear to be a sensitive indicator of organ perfusion in different shock states. However, responses can vary not only between organs and between different shock states, but also over time. These changes reflect the particular oxygen supply-demand balance present in that tissue bed at that specific time point in the disease process. The response to a dynamic oxygen challenge test provides further information that allows severity to be more readily differentiated. SUMMARY Monitoring of tissue oxygen tension may offer a potentially useful tool for clinical management though significant validation needs to be first performed to confirm its promise.
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Hempel C, Combes V, Hunt NH, Kurtzhals JAL, Grau GER. CNS hypoxia is more pronounced in murine cerebral than noncerebral malaria and is reversed by erythropoietin. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1939-50. [PMID: 21854739 DOI: 10.1016/j.ajpath.2011.06.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 05/18/2011] [Accepted: 06/28/2011] [Indexed: 01/13/2023]
Abstract
Cerebral malaria (CM) is associated with high mortality and risk of sequelae, and development of adjunct therapies is hampered by limited knowledge of its pathogenesis. To assess the role of cerebral hypoxia, we used two experimental models of CM, Plasmodium berghei ANKA in CBA and C57BL/6 mice, and two models of malaria without neurologic signs, P. berghei K173 in CBA mice and P. berghei ANKA in BALB/c mice. Hypoxia was demonstrated in brain sections using intravenous pimonidazole and staining with hypoxia-inducible factor-1α-specific antibody. Cytopathic hypoxia was studied using poly (ADP-ribose) polymerase-1 (PARP-1) gene knockout mice. The effect of erythropoietin, an oxygen-sensitive cytokine that mediates protection against CM, on cerebral hypoxia was studied in C57BL/6 mice. Numerous hypoxic foci of neurons and glial cells were observed in mice with CM. Substantially fewer and smaller foci were observed in mice without CM, and hypoxia seemed to be confined to neuronal cell somas. PARP-1-deficient mice were not protected against CM, which argues against a role for cytopathic hypoxia. Erythropoietin therapy reversed the development of CM and substantially reduced the degree of neural hypoxia. These findings demonstrate cerebral hypoxia in malaria, strongly associated with cerebral dysfunction and a possible target for adjunctive therapy.
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Affiliation(s)
- Casper Hempel
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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18
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Liu S, Shah SJ, Wilmes LJ, Feiner J, Kodibagkar VD, Wendland MF, Mason RP, Hylton N, Hopf HW, Rollins MD. Quantitative tissue oxygen measurement in multiple organs using 19F MRI in a rat model. Magn Reson Med 2011; 66:1722-30. [PMID: 21688315 DOI: 10.1002/mrm.22968] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/24/2011] [Accepted: 03/23/2011] [Indexed: 11/10/2022]
Abstract
Measurement of individual organ tissue oxygen levels can provide information to help evaluate and optimize medical interventions in many areas including wound healing, resuscitation strategies, and cancer therapeutics. Echo planar (19) F MRI has previously focused on tumor oxygen measurement at low oxygen levels (pO(2)) <30 mmHg. It uses the linear relationship between spin-lattice relaxation rate (R(1)) of hexafluorobenzene (HFB) and pO(2). The feasibility of this technique for a wider range of pO(2) values and individual organ tissue pO(2) measurement was investigated in a rat model. Spin-lattice relaxation times (T(1) = 1/R(1)) of hexafluorobenzene were measured using (19) F saturation recovery echo planar imaging. Initial in vitro studies validated the linear relationship between R(1) and pO(2) from 0 to 760 mmHg oxygen partial pressure at 25, 37, and 41°C at 7 Tesla for hexafluorobenzene. In vivo experiments measured rat tissue oxygen (ptO2) levels of brain, kidney, liver, gut, muscle, and skin during inhalation of both 30 and 100% oxygen. All organ ptO(2) values significantly increased with hyperoxia (P < 0.001). This study demonstrates that (19) F MRI of hexafluorobenzene offers a feasible tool to measure regional ptO2 in vivo, and that hyperoxia significantly increases ptO2 of multiple organs in a rat model.
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Affiliation(s)
- Siyuan Liu
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143-0464, USA
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19
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He JW, Kashyap D, Trevino LA, Liu H, Peng YB. Simultaneous absolute measures of glabrous skin hemodynamic and light-scattering change in response to formalin injection in rats. Neurosci Lett 2011; 492:59-63. [PMID: 21281696 DOI: 10.1016/j.neulet.2011.01.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/21/2011] [Accepted: 01/23/2011] [Indexed: 12/20/2022]
Abstract
Subcutaneous injection of formalin is a well-known model to study the nature of inflammatory pain. One of the cardinal signs of inflammation is redness, as a result of increased blood perfusion. We used an optical technology, light reflectance spectroscopy, to noninvasively obtain absolute measures of cutaneous hemodynamic components, including the concentrations of oxy- ([HbO]), deoxy- ([Hb]), total-hemoglobin ([HbT]), oxygen saturation (SO(2)), and the reduced light-scattering coefficient (μs'). The objective is to assess the effect of formalin-induced skin inflammation on the aforementioned parameters. Six rats were injected with formalin (50 μl, 3%) into left hind paw under pentobarbital anesthesia. Our results indicate prolonged increases in [HbO], [HbT], and SO(2) post injection only in the ipsilateral side. No statistically significant changes in [Hb] and μ(s)' occurred in either side. The arterial blood influx tends to be the major attribute of local hyperemia during inflammation. Thereby, [HbO] appears to be superior to [Hb] in measuring inflammation. In conclusion, the needle-probe-based light reflectance can be a feasible means to obtaining absolute measures of skin hemodynamic and light-scattering parameters when studying inflammatory pain.
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Affiliation(s)
- Ji-Wei He
- Department of Psychology, College of Science, University of Texas at Arlington, Arlington, TX 76019-0528, USA
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20
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Kadayakkara DKK, Janjic JM, Pusateri LK, Young WB, Ahrens ET. In vivo observation of intracellular oximetry in perfluorocarbon-labeled glioma cells and chemotherapeutic response in the CNS using fluorine-19 MRI. Magn Reson Med 2010; 64:1252-9. [PMID: 20860007 DOI: 10.1002/mrm.22506] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 03/19/2010] [Accepted: 04/20/2010] [Indexed: 01/15/2023]
Abstract
Preclinical development of therapeutic agents against cancer could greatly benefit from noninvasive markers of tumor killing. Potentially, the intracellular partial pressure of oxygen (pO(2) ) can be used as an early marker of antitumor efficacy. Here, the feasibility of measuring intracellular pO(2) of central nervous system glioma cells in vivo using (19) F magnetic resonance techniques is examined. Rat 9L glioma cells were labeled with perfluoro-15-crown-5-ether ex vivo and then implanted into the rat striatum. (19) F MRI was used to visualize tumor location in vivo. The mean (19) F T(1) of the implanted cells was measured using localized, single-voxel spectroscopy. The intracellular pO(2) in tumor cells was determined from an in vitro calibration curve. The basal pO(2) of 9L cells (day 3) was determined to be 45.3 ± 5 mmHg (n = 6). Rats were then treated with a 1 × LD10 dose of bischloroethylnitrosourea intravenously and changes in intracellular pO(2) were monitored. The pO(2) increased significantly (P = 0.042, paired T-test) to 141.8 ± 3 mmHg within 18 h after bischloroethylnitrosourea treatment (day 4) and remained elevated (165 ± 24 mmHg) for at least 72 h (day 6). Intracellular localization of the perfluoro-15-crown-5-ether emulsion in 9L cells before and after bischloroethylnitrosourea treatment was confirmed by histological examination and fluorescence microscopy. Overall, noninvasive (19) F magnetic resonance techniques may provide a valuable preclinical tool for monitoring therapeutic response against central nervous system or other deep-seated tumors.
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Affiliation(s)
- Deepak K K Kadayakkara
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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21
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Ortiz-Prado E, Natah S, Srinivasan S, Dunn JF. A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: the effect of acute and chronic hypoxia on brain tissue PO(2). J Neurosci Methods 2010; 193:217-25. [PMID: 20817029 DOI: 10.1016/j.jneumeth.2010.08.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 08/19/2010] [Accepted: 08/23/2010] [Indexed: 10/19/2022]
Abstract
The level of tissue oxygenation provides information related to the balance between oxygen delivery, oxygen utilization, tissue reactivity and morphology during physiological conditions. Tissue partial pressure of oxygen (PtO(2)) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO(2). In this study we present a novel fiber optic method to measure brain PtO(2). This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO(2), has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO(2) was studied during acute hypoxia, as well as before and after 28 days of high altitude acclimatization. A sensor was chronically implanted in the frontal cortex of eight Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO(2) declines by 80% and 76% pre- and post-acclimatization, respectively, when the fraction of inspired oxygen declines from 0.21 to 0.08. In addition, a linear relationship between brain PtO(2) and inspired O(2) levels was demonstrated r(2)=0.98 and r(2)=0.99 (pre- and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO(2) by approximately 35%. This paper demonstrates the use of a novel chronically implanted fiber optic based sensor for measuring absolute PtO(2). It shows a very strong linear relationship in awake animals between inspired O(2) and tissue O(2), and shows that there is a proportional increase in PtO(2) over a range of inspired values after exposure to chronic hypoxia.
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Affiliation(s)
- E Ortiz-Prado
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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22
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Frolov AE, Sviryaeva IV, Ruuge EK, Trubitsin BV, Tikhonov AN. EPR spectra of the trimethyl-1,4-benzoquinone anion-radical: Results of calculations by the density functional method and their comparison with experiment. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2010. [DOI: 10.1134/s0036024410090189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Sviryaeva IV, Mertsalova AS, Ruuge EK. Formation of superoxide radicals in isolated cardiac mitochondria: Effect of low oxygen concentration. Biophysics (Nagoya-shi) 2010. [DOI: 10.1134/s0006350910020119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Masamoto K, Obata T, Kanno I. Intracortical microcirculatory change induced by anesthesia in rat somatosensory cortex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 662:57-61. [PMID: 20204771 DOI: 10.1007/978-1-4419-1241-1_7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The present study aimed to characterize microcirculatory responses to anesthesia in brain tissue. With multi-photon excitation fluorescence microscopy, intra-cortical capillary dimension and red blood cell (RBC) flow were successfully visualized up to a depth of approximately 0.6 mm from the cortical surface in rats anesthetized with either isoflurane or alpha-chloralose. We observed that the diameter of the major cerebral artery was approximately 100 microm under isoflurane, but approximately 75 microm under alpha-chloralose. The capillary diameter was observed to be larger under alpha-chloralose than isoflurane: 5.1 +/- 1.2 microm vs. 4.8 +/- 1.1 microm, respectively. A significant difference in the mean RBC speed measured in single capillaries was observed: 0.4 +/- 0.4 mm/s under alpha-chloralose vs. 1.5 +/- 0.4 mm/s under isoflurane. In agreement with these observations, arterio-venous transit-time and laser-Doppler flowmetry consistently showed a significant reduction of the RBC and plasma blood speed under alpha-chloralose relative to isoflurane. These findings may indicate that local blood flow regulatory mechanisms exist at the capillary level for the balance of oxygen supply and demand induced by anesthesia in the brain tissue.
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Affiliation(s)
- Kazuto Masamoto
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
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25
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Taie S, Ono J, Iwanaga Y, Tomita S, Asaga T, Chujo K, Ueki M. Hypoxia-inducible factor-1α has a key role in hypoxic preconditioning. J Clin Neurosci 2009; 16:1056-60. [DOI: 10.1016/j.jocn.2008.09.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/02/2008] [Accepted: 09/03/2008] [Indexed: 10/20/2022]
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26
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Dyson A, Stidwill R, Taylor V, Singer M. The impact of inspired oxygen concentration on tissue oxygenation during progressive haemorrhage. Intensive Care Med 2009; 35:1783-91. [DOI: 10.1007/s00134-009-1577-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 05/21/2009] [Indexed: 11/28/2022]
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27
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Dinguizli M, Beghein N, Gallez B. Retrievable micro-inserts containing oxygen sensors for monitoring tissue oxygenation using EPR oximetry. Physiol Meas 2008; 29:1247-54. [DOI: 10.1088/0967-3334/29/11/001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Fong AY, Corcoran AE, Zimmer MB, Andrade DV, Milsom WK. Respiratory rhythm of brainstem-spinal cord preparations: Effects of maturation, age, mass and oxygenation. Respir Physiol Neurobiol 2008; 164:429-40. [PMID: 18948229 DOI: 10.1016/j.resp.2008.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 08/28/2008] [Accepted: 09/12/2008] [Indexed: 10/21/2022]
Abstract
We examined the effect of age, mass and the presence of the pons on the longevity (length of time spontaneous respiratory-related activity is produced) of brainstem-spinal cord preparations of neonatal rodents (rats and hamsters) and the level of oxygenation in the medulla respiratory network in these preparations. We found the longevity of the preparations from both species decreased with increasing postnatal age. Physical removal of the pons increased respiratory frequency and the longevity of the preparation. However, tissue oxygenation at the level of the medullary respiratory network was not affected by removal of the pons or increasing postnatal age (up to postnatal day 4). Taken together, these data suggest that the effect of removing the pons on respiratory frequency and the longevity of brainstem-spinal cord preparations with increasing postnatal age are primarily due to postnatal development and appear to be unrelated to mass or changes in levels of tissue oxygenation.
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Affiliation(s)
- Angelina Y Fong
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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29
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Van Eyck AS, Jordan BF, Gallez B, Heilier JF, Van Langendonckt A, Donnez J. Electron paramagnetic resonance as a tool to evaluate human ovarian tissue reoxygenation after xenografting. Fertil Steril 2008; 92:374-81. [PMID: 18692811 DOI: 10.1016/j.fertnstert.2008.05.012] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 04/30/2008] [Accepted: 05/01/2008] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To develop electron paramagnetic resonance (EPR) oximetry as a tool to characterize the oxygen environment in human ovarian xenografts in the early postgrafting period. DESIGN Prospective experimental study. SETTING Gynecology research unit in a university hospital. PATIENT(S) Biopsies were obtained from 6 women aged 22-35 years. INTERVENTION(S) Frozen-thawed human ovarian tissue fragments were grafted to an intraperitoneal site in nude mice. Before grafting, lithium phthalocyanine, an oxygen reporter, was implanted inside the fragments. MAIN OUTCOME MEASURE(S) To monitor partial pressure of oxygen (pO(2)) by EPR on postgrafting days 3, 5, 7, 10, 14, 17, and 21 and validate the technique by histologic assessment. RESULT(S) A period of hypoxia was identified before day 5, followed by gradual but significant oxygenation over the next 5 days, suggesting an active process of graft revascularization. Reoxygenation kinetics in human ovarian xenotransplants were quantified. CONCLUSION(S) Our data validated the EPR oximetry technique as a tool to monitor pO(2) in ovarian grafting. The critical early period of hypoxia was identified, and the first steps of reoxygenation were characterized. In the future, our model may be used to evaluate new freezing and grafting protocols with the aim of reducing potential cryoinjury and initial ischemia-reperfusion damage.
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Affiliation(s)
- Anne-Sophie Van Eyck
- Department of Gynecology, Faculty of Medicine, Université catholique de Louvain, Louvain, Cliniques Universitaires St. Luc, Avenue Hippocrate 10, Brussels, Belgium
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30
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Taie S, Ueki M, Chujo K, Asaga T, Iwanaga Y, Ono J, Maekawa N. Urinary trypsin inhibitor ameliorates renal tissue oxygenation after ischemic reperfusion in rats. J Anesth 2008; 22:149-54. [DOI: 10.1007/s00540-007-0602-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 12/14/2007] [Indexed: 11/25/2022]
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31
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Williams BB, Hou H, Grinberg OY, Demidenko E, Swartz HM. High spatial resolution multisite EPR oximetry of transient focal cerebral ischemia in the rat. Antioxid Redox Signal 2007; 9:1691-8. [PMID: 17678442 DOI: 10.1089/ars.2007.1723] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In vivo electron paramagnetic resonance (EPR) spectroscopy can provide direct noninvasive, continuous, and repeatable measurements of oxygen in tissues. High-spatial-resolution multisite (HSRMS) oximetry is an EPR technique that uses applied magnetic field gradients to extend this capability to multiple implanted probes within the sample and accurately to estimate their respective local pO(2) values. These capabilities are crucial in experiments in which pO(2) varies across space and time and in which information about these variations is needed to describe physiologic and pathophysiologic phenomena and evaluate their responses to interventions such as therapy. One important application is the investigation of transient focal ischemia in the rat brain and the effects of treatment with hyperoxygenation. We used HSRMS oximetry with overmodulation to measure brain tissue oxygenation in a rat stroke model using lithium phthalocyanine as the oxygen probe. Oxygen measurements were made in a small cohort of rats at four implant sites during ischemia and reperfusion after transient focal ischemia initiated by occlusion of the middle cerebral artery. These measurements demonstrate the capabilities of the HSRMS oximetry technique and set the stage for more extensive physiologic studies.
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Affiliation(s)
- Benjamin B Williams
- Dartmouth EPR Center, Department of Radiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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32
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Abstract
Brain function depends exquisitely on oxygen for energy metabolism. Measurements of brain tissue oxygen tension, by a variety of quantitative and qualitative techniques, going back for >50 years, have led to a number of significant conclusions. These conclusions have important consequences for understanding brain physiology as it is now being explored by techniques such as blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI) and near-infrared spectroscopy (NIRS). It has been known for some time that most of the measured oxygen tensions are less than venous pO2 and are distributed in a spatially and temporally heterogeneous manner on a microregional scale. Although certain large-scale methods can provide reproducible average brain pO2 measurements, no useful concept of a characteristic oxygen tension or meaningful average value for brain tissue oxygen can be known on a microregional level. Only an oxygen field exists with large local gradients due to local tissue respiration, and the most useful way to express this is with a pO2 distribution curve or histogram. The neurons of the brain cortex normally exist in a low-oxygen environment and on activation are oxygenated by increases in local capillary blood flow that lead to increases in hemoglobin saturation and tissue oxygen.
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Affiliation(s)
- Obinna Ndubuizu
- Department of Physiology and Anatomy, Case Western Reserve University, Cleveland, Ohio 44106-4930, USA
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33
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Khan N, Williams BB, Hou H, Li H, Swartz HM. Repetitive tissue pO2 measurements by electron paramagnetic resonance oximetry: current status and future potential for experimental and clinical studies. Antioxid Redox Signal 2007; 9:1169-82. [PMID: 17536960 PMCID: PMC2921178 DOI: 10.1089/ars.2007.1635] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Tissue oxygen plays a crucial role in maintaining tissue viability and in various diseases, including responses to therapy. Useful knowledge has been gained by methods that can give limited snapshots of tissue oxygen (e.g., oxygen electrodes) or evidence of a history of tissue hypoxia (e.g., EF5) or even indirect evidence by monitoring oxygen availability in the circulatory system (e.g., NMR methods). Each of these methods has advantages and significant limitations. EPR oximetry is a technique for direct measurement of tissue pO2, which has several advantages over the other existing methods for applications in which the parameter of interest is the pO2 of tissues, and information is needed over a time course of minutes to hours, and/or for repetitive measurements over days or weeks or years. The aim of this article is to provide an overview of EPR oximetry using particulates to readers who are not familiar with this technique and its potential in vivo and clinical applications. The data presented here are from the experiments currently being carried out in our laboratory. We are confident that in vivo EPR oximetry will play a crucial role in the understanding and clinical management of various pathologies in the years to come.
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Affiliation(s)
- Nadeem Khan
- EPR Center for Viable Systems, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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34
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Abstract
Tissue Po2 (tPo2) reflects the balance between local O2 supply and demand and, thus, could be a useful monitoring modality. However, the consistency and amplitude of the tPo2 response in different organs during different cardiorespiratory insults is unknown. Therefore, we investigated the effects of endotoxemia, hemorrhage, and hypoxemia on tPo2 measured in deep and peripheral organ beds. We compared arterial pressure, blood gas and lactate levels, descending aortic and renal blood flow, and tPo2 in skeletal muscle, bladder epithelium, liver, and renal cortex during 1) LPS infusion (10 mg/kg), 2) sequential removal of 10% of circulating blood volume, and 3) reductions in inspired O2 concentration in an anesthetized Wistar rat model with values measured in sham-operated animals. Different patterns were seen in each of the shock states, with condition-specific variations in the degree of acidemia, lactatemia, and tissue O2 responses between organs. Endotoxemia resulted in a rise in bladder tPo2 and an early fall in liver tPo2 but no significant change in muscle and renal cortical tPo2. Progressive hemorrhage, however, produced proportional declines in liver, muscle, and bladder tPo2, but renal cortical tPo2 was maintained until profound blood loss had occurred. By contrast, progressive hypoxemia resulted in proportional decreases in tPo2 in all organ beds. This study highlights the heterogeneity of responses in different organ beds during different shock states that are likely related to local changes in O2 supply and utilization. Whole body monitoring is not generally reflective of these changes.
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Affiliation(s)
- Alex Dyson
- Bloomsbury Institute of Intensive Care Medicine, University College London, Gower Street, London, UK
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35
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Abramovic Z, Sentjurc M, Kristl J, Khan N, Hou H, Swartz HM. Influence of different anesthetics on skin oxygenation studied by electron paramagnetic resonance in vivo. Skin Pharmacol Physiol 2006; 20:77-84. [PMID: 17143012 DOI: 10.1159/000097654] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 08/21/2006] [Indexed: 11/19/2022]
Abstract
The effects of two general anesthetics on skin oxygenation in mice are evaluated by electron paramagnetic resonance oximetry. Up to now no data on the effects of different anesthetics on skin oxygenation could be found. In this study animals were anesthetized with ketamine/xylazine or isoflurane, and partial pressure of oxygen (pO(2)) in the skin, heart rate and hemoglobin oxygen saturation were followed as a function of time and inhaled oxygen concentration. The skin pO(2) significantly increased continuously for about 60 min in mice anesthetized with isoflurane and remained constant after that. During ketamine/xylazine anesthesia, the pO(2) in the skin only slightly decreased. The skin pO(2) increased with higher inspired oxygen concentrations for both anesthetics groups. When breathing 21% oxygen, mice anesthetized with isoflurane had two-fold higher pO(2) in the skin compared to mice anesthetized with ketamine/xylazine. The heart rate was significantly lower in animals anesthetized with ketamine/xylazine, while hemoglobin saturation was almost the same in both groups at all inhaled oxygen concentrations. These results show that the type of anesthesia is an important parameter that needs to be considered in experiments where skin pO(2) is followed.
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Affiliation(s)
- Z Abramovic
- Laboratory for Biophysics, Jozef Stefan Institute, Ljubljana, Slovenia.
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36
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Matsumoto A, Matsumoto S, Sowers AL, Koscielniak JW, Trigg NJ, Kuppusamy P, Mitchell JB, Subramanian S, Krishna MC, Matsumoto KI. Absolute oxygen tension (pO(2)) in murine fatty and muscle tissue as determined by EPR. Magn Reson Med 2006; 54:1530-5. [PMID: 16276490 DOI: 10.1002/mrm.20714] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The absolute partial pressure of oxygen (pO(2)) in the mammary gland pad and femoral muscle of female mice was measured using EPR oximetry at 700 MHz. A small quantity of lithium phthalocyanine (LiPc) crystals was implanted in both mammary and femoral muscle tissue of female C3H mice. Subsequent EPR measurements were carried out 1-30 days after implantation with or without control of core body temperature. The pO(2) values in the tissue became stable 2 weeks after implantation of LiPc crystals. The pO(2) level was found to be higher in the femoral muscle than in the mammary tissue. However, the pO(2) values showed a strong dependence on the core body temperature of the mice. The pO(2) values were responsive to carbogen (95% O(2), 5% CO(2)) breathing even 44-58 days after the implantation of LiPc. The LiPc linewidth was also sensitive to changes in the blood supply even 60 days after implantation of the crystals. This study further validates the use of LiPc crystals and EPR oximetry for long-term non-invasive assessment of pO(2) levels in tissues, underscores the importance of maintaining normal body core temperature during the measurements, and demonstrates that mammary tissue functions at a lower pO(2) level than muscle in female C3H mice.
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Affiliation(s)
- Atsuko Matsumoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892-1002, USA
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37
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Dinguizli M, Jeumont S, Beghein N, He J, Walczak T, Lesniewski PN, Hou H, Grinberg OY, Sucheta A, Swartz HM, Gallez B. Development and evaluation of biocompatible films of polytetrafluoroethylene polymers holding lithium phthalocyanine crystals for their use in EPR oximetry. Biosens Bioelectron 2006; 21:1015-22. [PMID: 16368480 DOI: 10.1016/j.bios.2005.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/18/2005] [Accepted: 03/18/2005] [Indexed: 11/17/2022]
Abstract
Electron paramagnetic resonance (EPR) oximetry is a powerful technology that allows the monitoring of oxygenation in tissues. The measurement of tissue oxygenation can be achieved using lithium phthalocyanine (LiPc) crystals as oxygen reporters. In order to have biocompatibility for the sensing system and to assure long-term stability in the responsiveness of the system, we developed films of Teflon AF 2400 with embedded LiPc crystals. These systems can be used as retrievable inserts or parts of an implantable resonator or catheter. Atomic force microscopy studies revealed that the surface of the films was regular and planar. The response to oxygen of the sensor (EPR linewidth as a function of pO(2)) remained unchanged after implantation in mice, and was not affected by sterilization or irradiation. The use of resonators, holding LiPc embedded in Teflon AF 2400, implanted in the gastrocnemius muscle of rabbits allowed the monitoring of oxygen during several weeks. Several assays also demonstrated the biocompatibility of the system: (1) no hemolytic effect was noted; (2) no toxicity was found using the systemic injection test of extracts; (3) histological analysis in rabbit muscle in which the films were implanted for 1 week or 3 months was similar to standard polyethylene biocompatible devices. These advanced oxygen sensors are promising tools for future pre-clinical and clinical developments of EPR oximetry. These developments can be applied for other applications of biosensors where there is a need for oxygen permeable membranes.
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Affiliation(s)
- M Dinguizli
- Biomedical Magnetic Resonance Unit, Laboratory of Medicinal Chemistry and Radiopharmacy, Université Catholique de Louvain, Brussels, Belgium
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Hou H, Khan N, O'Hara JA, Grinberg OY, Dunn JF, Abajian MA, Wilmot CM, Demidenko E, Lu S, Steffen RP, Swartz HM. Increased oxygenation of intracranial tumors by efaproxyn (efaproxiral), an allosteric hemoglobin modifier: In vivo EPR oximetry study. Int J Radiat Oncol Biol Phys 2005; 61:1503-9. [PMID: 15817356 DOI: 10.1016/j.ijrobp.2004.12.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 12/27/2004] [Accepted: 12/28/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE To determine quantitatively the changes in oxygenation of intracranial tumors induced by efaproxiral, an allosteric hemoglobin modifier. Efaproxiral reduces hemoglobin-oxygen binding affinity, which facilitates oxygen release from hemoglobin into surrounding tissues and potentially increases the pO(2) of the tumors. METHODS AND MATERIALS The study was performed on 10 male Fisher 344 rats with 9L intracranial tumors. Electron paramagnetic resonance (EPR) oximetry was used to measure quantitatively the changes in the pO(2) in the tumors. Lithium phthalocyanine (LiPc) crystals were implanted in the tumors and in the normal brain tissue in the opposite hemispheres. We monitored the cerebral pO(2) starting 7 to 10 days after the tumor cells were implanted. NMR imaging determined the position and size of tumor in the brain. After an initial baseline EPR measurement, efaproxiral (150 mg/kg) was injected intravenously over 15 minutes, and measurements of tumor and normal brain oxygen tension were made alternately at 10-minute intervals for the next 60 minutes; the procedure was repeated for 6 consecutive days. RESULTS Efaproxiral significantly increased the pO(2) of both the intracranial tumors and the normal brain tissue on all days. The maximum increase was reached at 52.9 to 59.7 minutes and 54.1 to 63.2 minutes after injection, respectively. The pO(2) returned to baseline values at 106 to 126.5 minutes after treatment. The maximum tumor and normal tissue pO(2) values achieved after efaproxiral treatment from Day 1 through Day 6 ranged from 139.7 to 197.7 mm Hg and 103.0 to 135.9 mm Hg, respectively. The maximum increase in tumor tissue pO(2) values from Day 2 to Day 5 was greater than the maximum increase in normal tissue pO(2). CONCLUSION We obtained quantitative data on the timing and extent of efaproxiral-induced changes in the pO(2) of intracerebral 9L tumors. These results illustrate a unique and useful capability of in vivo EPR oximetry to obtain repeated noninvasive measurements of tumor oxygenation over a number of days. The information on the dynamics of tumor pO(2) after efaproxiral administration illustrates the ability of efaproxiral to increase intracranial tumor oxygenation.
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Affiliation(s)
- Huagang Hou
- Department of Diagnostic Radiology, EPR Center for the Study of Viable Systems, Dartmouth Medical School, Hanover, NH, USA
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O'Hara JA, Hou H, Demidenko E, Springett RJ, Khan N, Swartz HM. Simultaneous measurement of rat brain cortex PtO2using EPR oximetry and a fluorescence fiber-optic sensor during normoxia and hyperoxia. Physiol Meas 2005; 26:203-13. [PMID: 15798296 DOI: 10.1088/0967-3334/26/3/006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electron paramagnetic resonance (EPR) oximetry is a promising, relatively non-invasive method of monitoring tissue partial pressure of oxygen (PtO(2)) that has proven useful in following changes in PtO(2) under various physiologic and pathophysiologic conditions. Optimal utilization of the method will be facilitated by systematic comparisons with other available methods. Here, we report on the absolute values and changes of rat brain PtO(2) using EPR oximetry and the OxyLite, an oxygen monitor based on fluorescence quenching, at adjacent locations in the same brain. EPR oximetry utilizes an implanted oxygen-sensitive material and reports tissue PtO(2) at the surface of the material. OxyLite measures PtO(2) using the fluorescence lifetime of a chromophore fixed to the tip of an optical fiber that is inserted into tissue. Measurements were made at a depth of 2-3 mm into the cortex during normoxia and during breathing of carbogen (95% O(2):5% CO(2)) followed by a return to normoxia. We conclude that in this study (1) PtO(2) values reported by the two methods are similar but not exactly the same, (2) both methods can record a baseline and rapid changes in PtO(2), (3) changes in PtO(2) induced by increasing FiO(2) from 0.26 to 0.95 (carbogen) were similar by the two methods and (4) in some rats breathing carbogen, absolute values of PtO(2) were above the sensitive range of the OxyLite method.
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Affiliation(s)
- Julia A O'Hara
- EPR Center for the Study of Viable Systems, Dartmouth Medical School, Hanover, NH 03755, USA.
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Hou H, Grinberg OY, Grinberg SA, Demidenko E, Swartz HM. Cerebral tissue oxygenation in reversible focal ischemia in rats: multi-site EPR oximetry measurements. Physiol Meas 2005; 26:131-41. [PMID: 15742885 DOI: 10.1088/0967-3334/26/1/012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Multi-site electron paramagnetic resonance (EPR) oximetry was used in vivo to measure the partial pressure of oxygen (pO2) in reversible focal ischemia in rats. The cerebral tissue pO2 was measured simultaneously and continuously at two sites on the ischemic side and one on the normal side of the brain in the same animal prior to and at several time points after ischemia and reperfusion. The O2 at the three different sites in brain was stable over 30 min of baseline measurements. During the first 120 min of ischemia, statistically significant decreases in brain pO2 from baseline were consistently observed in the ischemic core and perifocal area. The mean values varied during the 120 min of ischemia. Reperfusion resulted in an immediate increase in PO2, but there were no significant differences between the sites over time. The result of this study seems promising for the study of ischemia and reperfusion. It appears that the technique can provide information on the PO2 under the experimental conditions needed for such a study. The levels of PO2 that occurred in these experiments are readily resolvable by multi-site EPR oximetry. In addition, the ability simultaneously to measure the pO2 in several sites provides important additional information that should help to differentiate between changes in the PO2 due toglobal or local mechanisms.
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Affiliation(s)
- Huagang Hou
- EPR Center for the Study of Viable Systems, Dartmouth Medical School, Hanover, NH, USA
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Hou H, Grinberg OY, Grinberg SA, Khan N, Dunn JF, Swartz HM. Cerebral PtO2, acute hypoxia, and volatile anesthetics in the rat brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 566:179-85. [PMID: 16594151 DOI: 10.1007/0-387-26206-7_25] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We describe our results on the effect in rats of two commonly used, volatile anesthetics on cerebral tissue PO2 (PtO2) and other physiological parameters at FiO2 levels ranging from 0.35 to 0.1. The study was performed in 12 rats that had lithium phthalocyanine (LiPc) crystals implanted in the left cerebral cortex. FiO2 was maintained at 0.35 during surgical manipulation and baseline EPR measurements, after which time, each animal was exposed to varying levels of FiO2 (0.26, 0.21, 0.15, and 0.10) for 30 minutes at each level. No significant difference in PtO2 was observed between the isoflurane and halothane groups at any FiO2 level, and the cerebral arterial PO2 (PaO2) also was similar for both groups. However, the cerebral PtO2 under both isoflurane and halothane anesthesia was lower during hypoxia (FiO2 < or = 0.15) than under normoxia (FiO2 = 0.21) and there was a significant difference in mean arterial blood pressure (MABP) between isoflurane and halothane groups under both mild and severe hypoxia. The pH and cerebral arterial PCO2 (PaCO2) were similar for the halothane and isoflurane groups during normoxia (FiO2 = 0.21) and mild hypoxia (FiO2 = 0,15), but following severe hypoxia (FiO2 = 0.10), both parameters were lower in the halothane anesthetized animals. These results confirm that cerebral PO2 cannot be inferred directly from measurements of other parameters, indicating that methodology incorporating continuous direct measurement of brain oxygen will lead to a better understanding of cerebral oxygenation under anesthesia and hypoxia.
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Grinberg OY, Hou H, Roche MA, Merlis J, Grinberg SA, Khan N, Swartz HM, Dunn JF. Modeling of the response of ptO2 in rat brain to changes in physiological parameters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 566:111-8. [PMID: 16594142 DOI: 10.1007/0-387-26206-7_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
It is known that oxygen tension in tissue (ptO2) will change in response to an alteration of physiological parameters including: pCO2 in arterial blood, blood flow, capillary density, oxygen carrying capacity, and p50 of hemoglobin. We have used modeling to compute the change of PtO2 in response to changes of each physiological parameter and related these changes to experimental data. The oxygen distribution in a Krogh cylinder was computed assuming a linear decrease of hemoglobin saturation from the arterial to the venous end of the capillary. Parameters of the model were used to compute the baseline cerebral PtO2 expressed as the mean value of the PtO2 over the whole cylinder. These parameters were adjusted to derive PtO2 values close to those measured at the relevant experimental conditions. Then each desired parameter was varied to calculate the change in PtO2 related to this parameter. Effects of different factors on cerebral PtO2 were modeled and compared with experimental values obtained with various experimental interventions including: changing CBF, modifying p50 with the allosteric modifier RSR13, modification of capillary density, and hemoglobin content. An acceptable agreement of the computed and the experimental changes of the cerebral PtO2 was obtained for these experimental conditions.
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Abstract
Oxygen is a critical variable in oxidative damage. It can be a direct reactant in one or more of the pertinent reactions that result in oxidative damage. It also is an essential substrate for mitochondrial respiration and many other essential synthetic and degradative reactions. The level of oxygen can have a regulatory role, affecting the rate and direction of metabolic processes and physiological functions that are germane to the pathophysiological processes that are being studied. Its supply to tissue and to cells is therefore a critical parameter governing normal homeostasis. The level of oxygen at specific sites may affect cell signaling. It therefore seems clear that it can be very useful to measure oxygen when studying oxidative damage. In order for the measurements of oxygen to be most useful, it often is essential to measure the amount of oxygen at particular sites and under appropriate conditions. These needs require methodology that can make sensitive and localized measurements of oxygen. Electron paramagnetic resonance (EPR) oximetry is such a technique, plus it has the capability of making repeated measurements from the same site non-invasively. The principles and applications of EPR oximetry to viable systems, including cell suspensions and intact animals, are described in this paper.
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Affiliation(s)
- Harold M Swartz
- EPR Center for the Study of Viable Systems, Department of Radiology, Dartmouth Medical School, Hanover, NH 03755, USA.
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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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