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Rathbone E, Fu D. Quantitative Optical Imaging of Oxygen in Brain Vasculature. J Phys Chem B 2024. [PMID: 38991095 DOI: 10.1021/acs.jpcb.4c01277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The intimate relationship between neuronal activity and cerebral oxygenation underpins fundamental brain functions like cognition, sensation, and motor control. Optical imaging offers a noninvasive approach to assess brain oxygenation and often serves as an indirect proxy for neuronal activity. However, deciphering neurovascular coupling─the intricate interplay between neuronal activity, blood flow, and oxygen delivery─necessitates independent, high spatial resolution, and high temporal resolution measurements of both microvasculature oxygenation and neuronal activation. This Perspective examines the established optical techniques employed for brain oxygen imaging, specifically functional near-infrared spectroscopy, photoacoustic imaging, optical coherence tomography, and two-photon phosphorescent lifetime microscopy, highlighting their fundamental principles, strengths, and limitations. Several other emerging optical techniques are also introduced. Finally, we discuss key technological challenges and future directions for quantitative optical oxygen imaging, paving the way for a deeper understanding of oxygen metabolism in the brain.
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Affiliation(s)
- Emily Rathbone
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Dan Fu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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Hiura M, Funaki A, Shibutani H, Takahashi K, Katayama Y. Dissociated coupling between cerebral oxygen metabolism and perfusion in the prefrontal cortex during exercise: a NIRS study. Front Physiol 2023; 14:1165939. [PMID: 37565141 PMCID: PMC10411551 DOI: 10.3389/fphys.2023.1165939] [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: 02/14/2023] [Accepted: 07/07/2023] [Indexed: 08/12/2023] Open
Abstract
Purpose: The present study used near-infrared spectroscopy to investigate the relationships between cerebral oxygen metabolism and perfusion in the prefrontal cortex (PFC) during exercises of different intensities. Methods: A total of 12 recreationally active men (age 24 ± 6 years) were enrolled. They performed 17 min of low-intensity exercise (ExL), followed by 3 min of moderate-intensity exercise (ExM) at constant loads. Exercise intensities for ExL and ExM corresponded to 30% and 45% of the participants' heart rate reserve, respectively. Cardiovascular and respiratory parameters were measured. We used near-infrared time-resolved spectroscopy (TRS) to measure the cerebral hemoglobin oxygen saturation (ScO2) and total hemoglobin concentration ([HbT]), which can indicate the cerebral blood volume (CBV). As the cerebral metabolic rate for oxygen (CMRO2) is calculated using cerebral blood flow (CBF) and ScO2, we assumed a constant power law relationship between CBF and CBV based on investigations by positron emission tomography (PET). We estimated the relative changes in CMRO2 (rCMRO2) and CBV (rCBV) from the baseline. During ExL and ExM, the rate of perceived exertion was monitored, and alterations in the subjects' mood induced by exercise were evaluated using the Profile of Moods Scale-Brief. Results: Three minutes after exercise initiation, ScO2 decreased and rCMRO2 surpassed rCBV in the left PFC. When ExL changed to ExM, cardiovascular variables and the sense of effort increased concomitantly with an increase in [HbT] but not in ScO2, and the relationship between rCMRO2 and rCBV was dissociated in both sides of the PFC. Immediately after ExM, [HbT], and ScO2 increased, and the disassociation between rCMRO2 and rCBV was prominent in both sides of the PFC. While blood pressure decreased and a negative mood state was less prominent following ExM compared with that at rest, ScO2 decreased 15 min after exercise and rCMRO2 surpassed rCBV in the left PFC. Conclusion: Dissociated coupling between cerebral oxidative metabolism and perfusion in the PFC was consistent with the effort required for increased exercise intensity and associated with post-exercise hypotension and altered mood status after exercise. Our result demonstrates the first preliminary results dealing with the coupling between cerebral oxidative metabolism and perfusion in the PFC using TRS.
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Affiliation(s)
- Mikio Hiura
- Center for Brain and Health Sciences, Aomori University, Aomori, Japan
| | - Akio Funaki
- Faculty of Sociology, Aomori University, Aomori, Japan
| | | | - Katsumi Takahashi
- Faculty of Creative Engineering, Kanagawa Institute of Technology, Atsugi, Japan
| | - Yoichi Katayama
- Center for Brain and Health Sciences, Aomori University, Aomori, Japan
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Hashem M, Wu Y, Dunn JF. The Effect of Hypercapnia on Cortical Metabolic Rate and Mitochondrial Redox Status. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1438:15-20. [PMID: 37845433 DOI: 10.1007/978-3-031-42003-0_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Hypercapnia is commonly used as a vasodilatory stimulus in both basic and clinical research. There have been conflicting reports about whether cerebral metabolic rate of oxygen (CMRO2) is maintained at normal levels during increases of cerebral blood flow (CBF) and oxygen delivery caused by hypercapnia.This study aims to provide insight into how hypercapnia may impact CMRO2 and brain mitochondrial function. We introduce data from mouse cortex collected with a novel multimodality system which combines MRI and near-infrared spectroscopy (NIRS). We quantify CBF, tissue oxygen saturation (StO2), oxidation state of the mitochondrial enzyme cytochrome c oxidase (CCO), and CMRO2.During hypercapnia, CMRO2 did not change while CBF, StO2, and the oxidation state of CCO increased significantly. This paper supports the conclusion that hypercapnia does not change CMRO2. It also introduces the application of a multimodal NIRS-MRI system which enables non-invasive quantification of CMRO2, and other physiological variables, in the cerebral cortex of mouse models.
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Affiliation(s)
- Mada Hashem
- Department of Radiology, University of Calgary, Calgary, AB, Canada.
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
| | - Ying Wu
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jeff F Dunn
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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Siwicka-Gieroba D, Robba C, Gołacki J, Badenes R, Dabrowski W. Cerebral Oxygen Delivery and Consumption in Brain-Injured Patients. J Pers Med 2022; 12:1763. [PMID: 36573716 PMCID: PMC9698645 DOI: 10.3390/jpm12111763] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 12/30/2022] Open
Abstract
Organism survival depends on oxygen delivery and utilization to maintain the balance of energy and toxic oxidants production. This regulation is crucial to the brain, especially after acute injuries. Secondary insults after brain damage may include impaired cerebral metabolism, ischemia, intracranial hypertension and oxygen concentration disturbances such as hypoxia or hyperoxia. Recent data highlight the important role of clinical protocols in improving oxygen delivery and resulting in lower mortality in brain-injured patients. Clinical protocols guide the rules for oxygen supplementation based on physiological processes such as elevation of oxygen supply (by mean arterial pressure (MAP) and intracranial pressure (ICP) modulation, cerebral vasoreactivity, oxygen capacity) and reduction of oxygen demand (by pharmacological sedation and coma or hypothermia). The aim of this review is to discuss oxygen metabolism in the brain under different conditions.
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Affiliation(s)
- Dorota Siwicka-Gieroba
- Department of Anaesthesiology and Intensive Care, Medical University in Lublin, 20-954 Lublin, Poland
| | - Chiara Robba
- Department of Anesthesiology and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, 16132 Genoa, Italy
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, 16132 Genoa, Italy
| | - Jakub Gołacki
- Department of Anaesthesiology and Intensive Care, Medical University in Lublin, 20-954 Lublin, Poland
| | - Rafael Badenes
- Department of Anesthesiology and Surgical-Trauma Intensive Care, Hospital Clinic Universitari, University of Valencia, 46010 Valencia, Spain
| | - Wojciech Dabrowski
- Department of Anaesthesiology and Intensive Care, Medical University in Lublin, 20-954 Lublin, Poland
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Ioanas HI, Schlegel F, Skachokova Z, Schroeter A, Husak T, Rudin M. Hybrid fiber optic-fMRI for multimodal cell-specific recording and manipulation of neural activity in rodents. NEUROPHOTONICS 2022; 9:032206. [PMID: 35355657 PMCID: PMC8936941 DOI: 10.1117/1.nph.9.3.032206] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 01/19/2022] [Indexed: 05/08/2023]
Abstract
Significance: Multiscale imaging holds particular relevance to neuroscience, where it helps integrate the cellular and molecular biological scale, which is most accessible to interventions, with holistic organ-level evaluations, most relevant with respect to function. Being inextricably interdisciplinary, multiscale imaging benefits substantially from incremental technology adoption, and a detailed overview of the state-of-the-art is vital to an informed application of imaging methods. Aim: In this article, we lay out the background and methodological aspects of multimodal approaches combining functional magnetic resonance imaging (fMRI) with simultaneous optical measurement or stimulation. Approach: We focus on optical techniques as these allow, in conjunction with genetically encoded proteins (e.g. calcium indicators or optical signal transducers), unprecedented read-out and control specificity for individual cell-types during fMRI experiments, while leveraging non-interfering modalities. Results: A variety of different solutions for optical/fMRI methods has been reported ranging from bulk fluorescence recordings via fiber photometry to high resolution microscopy. In particular, the plethora of optogenetic tools has enabled the transformation of stimulus-evoked fMRI into a cell biological interrogation method. We discuss the capabilities and limitations of these genetically encoded molecular tools in the study of brain phenomena of great methodological and neuropsychiatric interest-such as neurovascular coupling (NVC) and neuronal network mapping. We provide a methodological description of this interdisciplinary field of study, and focus in particular on the limitations of the widely used blood oxygen level dependent (BOLD) signal and how multimodal readouts can shed light on the contributions arising from neurons, astrocytes, or the vasculature. Conclusion: We conclude that information from multiple signaling pathways must be incorporated in future forward models of the BOLD response to prevent erroneous conclusions when using fMRI as a surrogate measure for neural activity. Further, we highlight the potential of direct neuronal stimulation via genetically defined brain networks towards advancing neurophysiological understanding and better estimating effective connectivity.
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Affiliation(s)
- Horea-Ioan Ioanas
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- Massachusetts Institute of Technology, Department of Biological Engineering, Cambridge, Massachusetts, United States
- Dartmouth College, Center for Open Neuroscience, Hanover, New Hampshire, United States
- Address all correspondence to Markus Rudin, ; Horea-Ioan Ioanas,
| | - Felix Schlegel
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
| | - Zhiva Skachokova
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
| | - Aileen Schroeter
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- University of Zurich, USZ Innovation Hub, Zurich, Switzerland
| | - Tetiana Husak
- Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, Cambridge, Massachusetts, United States
| | - Markus Rudin
- University of Zurich Institute for Biomedical Engineering, ETH, Zürich, Switzerland
- The LOOP Zurich, Zurich, Switzerland
- Address all correspondence to Markus Rudin, ; Horea-Ioan Ioanas,
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Hashem M, Shafqat Q, Wu Y, Rho JM, Dunn JF. Abnormal Oxidative Metabolism in the Cuprizone Mouse Model of Demyelination: an in vivo NIRS-MRI Study. Neuroimage 2022; 250:118935. [PMID: 35091079 DOI: 10.1016/j.neuroimage.2022.118935] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 12/11/2022] Open
Abstract
Disruptions in oxidative metabolism may occur in multiple sclerosis and other demyelinating neurological diseases. The impact of demyelination on metabolic rate is also not understood. It is possible that mitochondrial damage may be associated with many such neurological disorders. To study oxidative metabolism with one model of demyelination, we implemented a novel multimodal imaging technique combining Near-Infrared Spectroscopy (NIRS) and MRI to cuprizone mouse model. The cuprizone model is used to study demyelination and may be associated with inhibition of mitochondrial function. Cuprizone mice showed reduced oxygen extraction fraction (-39.1%, p≤0.001), increased tissue oxygenation (6.4%, p≤0.001), and reduced cerebral metabolic rate of oxygen in cortical gray matter (-62.1%, p≤0.001). These changes resolved after the cessation of cuprizone exposure and partial remyelination. A decrease in hemoglobin concentration (-34.4%, p≤0.001), but no change in cerebral blood flow were also observed during demyelination. The oxidized state of the mitochondrial enzyme, Cytochrome C Oxidase (CCO) increased (46.3%, p≤0.001) while the reduced state decreased (-34.4%, p≤0.05) significantly in cuprizone mice. The total amount of CCO did not change significantly during cuprizone exposure. Total CCO did decline after recovery both in control (-23.1%, p≤0.01) and cuprizone (-28.8%, p≤0.001) groups which may relate to age. A reduction in the magnetization transfer ratio, indicating demyelination, was found in the cuprizone group in the cerebral cortex (-3.2%, p≤0.01) and corpus callosum (-5.5%, p≤0.001). In summary, we were able to detect evidence of altered CCO metabolism during cuprizone exposure, consistent with a mitochondrial defect. We observed increased oxygenation and reduced metabolic rate associated with reduced myelination in the gray and white matter. The novel multimodal imaging technique applied here shows promise for noninvasively assessing parameters associated with oxidative metabolism in both mouse models of neurological disease and for translation to study oxidative metabolism in the human brain.
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Affiliation(s)
- Mada Hashem
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Alberta, Canada T2N 4N1; Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1; Hotchkiss Brain Institute, University of Calgary, Alberta, Canada, T2N 4N1; Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada, T2N 4N1
| | - Qandeel Shafqat
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1; Hotchkiss Brain Institute, University of Calgary, Alberta, Canada, T2N 4N1; Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada, T2N 4N1
| | - Ying Wu
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1; Hotchkiss Brain Institute, University of Calgary, Alberta, Canada, T2N 4N1; Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada, T2N 4N1
| | - Jong M Rho
- Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada, T2N 4N1
| | - Jeff F Dunn
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1; Hotchkiss Brain Institute, University of Calgary, Alberta, Canada, T2N 4N1; Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada, T2N 4N1.
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Hashem M, Wu Y, Dunn JF. Quantification of cytochrome c oxidase and tissue oxygenation using CW-NIRS in a mouse cerebral cortex. BIOMEDICAL OPTICS EXPRESS 2021; 12:7632-7656. [PMID: 35003857 PMCID: PMC8713667 DOI: 10.1364/boe.435532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/06/2021] [Accepted: 11/05/2021] [Indexed: 05/05/2023]
Abstract
We provide a protocol for measuring the absolute concentration of the oxidized and reduced state of cytochrome c oxidase (CCO) in the cerebral cortex of mice, using broadband continuous-wave NIRS. The algorithm (NIR-AQUA) allows for absolute quantification of CCO and deoxyhemoglobin. Combined with an anoxia pulse, this also allows for quantification of total hemoglobin, and tissue oxygen saturation. CCO in the cortex was 4.9 ± 0.1 μM (mean ± SD, n=6). In normoxia, 84% of CCO was oxidized. We include hypoxia and cyanide validation studies to show CCO can be quantified independently to hemoglobin. This can be applied to study oxidative metabolism in the many rodent models of neurological disease.
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Affiliation(s)
- Mada Hashem
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Alberta, Canada T2N 4N1, Canada
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Alberta, Canada T2N 4N1, Canada
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada T2N 4N1, Canada
| | - Ying Wu
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Alberta, Canada T2N 4N1, Canada
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada T2N 4N1, Canada
| | - Jeff F. Dunn
- Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Alberta, Canada T2N 4N1, Canada
- Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Alberta, Canada T2N 4N1, Canada
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Qi Y, Wang X, Mao J. Quantitative assessment of cerebral metabolism and hemodynamics in small-for-gestational-age (SGA) newborns. Quant Imaging Med Surg 2021; 11:2321-2332. [PMID: 34079704 DOI: 10.21037/qims-20-1040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background Small-for-gestational-age (SGA) newborns represent approximately 10% of births worldwide and 45% of births in some countries. It has been suggested that SGA might cause learning difficulties and behavioral abnormalities in childhood, yet the neurobiological basis for this is poorly understood. In this study, we employed several advanced imaging techniques-including T2-relaxation-under-spin-tagging (TRUST) magnetic resonance imaging (MRI), and phase-contrast (PC) MRI-to quantify oxygen extraction fraction (OEF), global cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2) to elucidate pathophysiological vulnerabilities of SGA neonates. Methods A total of 41 newborns were enrolled in this study, consisting of 29 SGA and 12 appropriate-for-gestational-age (AGA) neonates. The SGA group was further divided into subgroups with and without abnormalities on structural MRI, denoted as SGA-a (N=17) and SGA-n (N=12). TRUST and PC MRI were performed to determine OEF, CBF, and CMRO2. Linear regression analyses were performed to examine physiological parameters' dependence on scan age, gender, and group. Similar analyses were conducted for birth weight and brain volume. Receiver operating characteristic (ROC) curves were used to test physiological parameters' ability to different diagnostic groups. Results Regression analysis revealed that CMRO2 was significantly lower (P=0.04) in the SGA group relative to the AGA group. When further stratifying the SGA participants into SGA-a and SGA-n subgroups, the SGA-a subgroup was found to have the most pronounced physiological deficits, with a lower CMRO2 (P=0.004) and lower CBF (P=0.007) than those in the AGA group. Conversely, CMRO2 (P=0.40) and CBF (P=0.90) in the SGA-n subgroup were not different from those of the AGA group. Accordingly, CBF in the SGA-a group was significantly lower (P=0.01) than that of the SGA-n group and CMRO2 also showed a difference (P=0.09). Additionally, CMRO2 (P=0.002) and CBF (P=0.04) showed an age-related increase during this early developmental period. In analyzing the SGA-a subgroup relative to the remaining neonates, the area under curve (AUC) values were 0.6, 0.6, 0.7, 0.8, and 0.5 for birth weight, OEF, CMRO2, CBF, and brain volume, respectively. In analyzing the SGA-a subgroup relative to the SGA-n subgroup, AUC values were 0.5, 0.6, 0.7, 0.8, and 0.5 for birth weight, OEF, CMRO2, CBF, and brain volume. Conclusions Structural damage in SGA-a neonates is associated with cerebral hemodynamic and metabolic deficits. SGA neonates with normal CBF and CMRO2reveal minimal structural abnormalities. Physiological imaging may help identify SGA patients at high risk of developing irreversible brain damage.
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Affiliation(s)
- Ying Qi
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xiaoming Wang
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Jian Mao
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
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Qi Y, He J. Neurophysiologic Profiling of At-Risk Low and Very Low Birth-Weight Infants Using Magnetic Resonance Imaging. Front Physiol 2021; 12:638868. [PMID: 33833688 PMCID: PMC8021729 DOI: 10.3389/fphys.2021.638868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
Low birth-weight (LBW) and very low birth-weight (VLBW) newborns have increased risks of brain injuries, growth failure, motor difficulties, developmental coordination disorders or delay, and adult-onset vascular diseases. However, relatively little is known of the neurobiologic underpinnings. To clarify the pathophysiologic vulnerabilities of such neonates, we applied several advanced techniques for assessing brain physiology, namely T2-relaxation-under-spin-tagging (TRUST) magnetic resonance imaging (MRI) and phase-contrast (PC) MRI. This enabled quantification of oxygen extraction fraction (OEF), global cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2). A total of 50 neonates (LBW-VLBW, 41; term controls, 9) participated in this study. LBW-VLBW neonates were further stratified as those with (LBW-VLBW-a, 24) and without (LBW-VLBW-n, 17) structural MRI (sMRI) abnormalities. TRUST and PC MRI studies were undertaken to determine OEF, CBF, and CMRO2. Ultimately, CMRO2 proved significantly lower (p = 0.01) in LBW-VLBW (vs term) neonates, both LBW-VLBW-a and LBW-VLBW-n subsets showing significantly greater physiologic deficits than term controls (p = 0.03 and p = 0.04, respectively). CMRO2 and CBF in LBW-VLBW-a and LBW-VLBW-n subsets did not differ significantly (p > 0.05), although OEF showed a tendency to diverge (p = 0.15). However, OEF values in the LBW-VLBW-n subset differed significantly from those of term controls (p = 0.02). Compared with brain volume or body weight, these physiologic parameters yield higher area-under-the-curve (AUC) values for distinguishing neonates of the LBW-VLBW-a subset. The latter displayed distinct cerebral metabolic and hemodynamic, whereas changes were marginal in the LBW-VLBW-n subset (i.e., higher OEF and lower CBF and CMRO2) by comparison. Physiologic imaging may therefore be useful in identifying LBW-VLBW newborns at high risk of irreversible brain damage.
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Affiliation(s)
- Ying Qi
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Jingni He
- Department of Surgery, Shengjing Hospital of China Medical University, Shenyang, China
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Impaired brain function improved by L-carnitine in patients with cirrhosis: evaluation using near-infrared spectroscopy. Sci Rep 2020; 10:13566. [PMID: 32782294 PMCID: PMC7419306 DOI: 10.1038/s41598-020-70585-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 07/20/2020] [Indexed: 02/07/2023] Open
Abstract
To evaluate the effects of l-carnitine on impaired brain function in patients with liver cirrhosis. We conducted a retrospective cohort study that included sequential 80 liver cirrhosis patients with impaired brain function evaluated using near-infrared spectroscopy (NIRS). Among them, l-carnitine was administered to 48 patients. The NIRS data and blood ammonia level at baseline and after 8 weeks of treatment were compared between patients administered with l-carnitine (l-carnitine group) and those who were not (control group). The NIRS data at baseline were similar between the l-carnitine and control groups (0.04 ± 0.04 vs. 0.04 ± 0.05 mMmm, p = n.s), whereas those in the l-carnitine group (n = 48) were significantly better than that of the control group at 8 weeks of treatment (n = 32) (0.103 ± 0.081 vs. 0.040 ± 0.048 mMmm, p < 0.001). In the l-carnitine group, 35.4% (17/48) of patients had hyperammonemia. The NIRS data of the l-carnitine group at 8 weeks of treatment were significantly improved than that of the control group, irrespective of baseline ammonia levels (0.11 ± 0.09 vs. 0.04 ± 0.05 mMmm, p = 0.005, and 0.10 ± 0.06 vs. 0.02 ± 0.03 mMmm, p = 0.003, for normal baseline ammonia and elevated ammonia levels, respectively). In the multivariate analysis, l-carnitine administration (odds ratio [OR] 3.51, 95% confidence interval [CI] 1.23–9.99, p = 0.019) and baseline NIRS data of ≤ 0.07 mMmm (OR 5.21, 95% CI 1.69–16.0, p = 0.0041) were found as independent significant factors. l-carnitine improves impaired brain function in patients with liver cirrhosis.
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Yu L, Thurston EMS, Hashem M, Dunn JF, Whelan PJ, Murari K. Fiber photometry for monitoring cerebral oxygen saturation in freely-moving rodents. BIOMEDICAL OPTICS EXPRESS 2020; 11:3491-3506. [PMID: 33014546 PMCID: PMC7510909 DOI: 10.1364/boe.393295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/16/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
Hemodynamic parameters, such as tissue oxygen saturation and blood volume fraction, are important markers of brain physiology. They are also widely used surrogate markers of electrophysiological activity. Here, we present a single fiber spectroscopic (SFS) system for monitoring cerebral oxygen saturation in localized, non-line-of-sight brain regions in freely-moving rodents. We adapted the implantation ferrule and patch cable design from commercialized optogenetics and fiber photometry systems, enabling stereotaxic fiber implantation, longitudinal tissue access and measurement from freely-moving animals. The optical system delivers and collects light from the brain through a 200 µm-core-diameter, 0.39NA multimode fiber. We robustly measured oxygen saturation from phantoms with different optical properties mimicking brain tissue. In mice, we demonstrated, for the first time, measurements of oxygen saturation from a highly-localized, targeted brain region over 31 days and continuous measurements from a freely-moving animal for over an hour. These results suggest that single fiber spectroscopy has enormous potential for functional brain monitoring and investigating neurovascular coupling in freely-moving animals. In addition, this technique can potentially be combined with fiber photometry systems to correct for hemodynamic artifacts in the fluorescence detection.
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Affiliation(s)
- Linhui Yu
- University of Calgary, Schulich School of Engineering, Electrical and Computer Engineering, Calgary, Canada
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
| | - Elizabeth M. S. Thurston
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
- University of Calgary, Department of Neuroscience, Calgary, Canada
- These authors contributed equally to this work
| | - Mada Hashem
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
- University of Calgary, Biomedical Engineering Graduate Program, Calgary, Canada
- These authors contributed equally to this work
| | - Jeff F. Dunn
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
- University of Calgary, Biomedical Engineering Graduate Program, Calgary, Canada
| | - Patrick J. Whelan
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
- University of Calgary, Department of Neuroscience, Calgary, Canada
| | - Kartikeya Murari
- University of Calgary, Schulich School of Engineering, Electrical and Computer Engineering, Calgary, Canada
- University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
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