1
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Tomoto T, Zhang R. Arterial Aging and Cerebrovascular Function: Impact of Aerobic Exercise Training in Older Adults. Aging Dis 2024; 15:1672-1687. [PMID: 38270114 PMCID: PMC11272215 DOI: 10.14336/ad.2023.1109-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/09/2023] [Indexed: 01/26/2024] Open
Abstract
Advanced age is the major risk factor for dementia including Alzheimer's disease. The clinical effects of recently developed anti-amyloid therapy for Alzheimer's disease were modest and the long-term outcome is unknown. Thus, an in-depth understanding of the mechanisms of brain aging is essential to develop preventive interventions to maintain cognitive health in late life. Mounting evidence suggests that arterial aging manifested as increases in central arterial stiffness is associated closely with cerebrovascular dysfunction and brain aging while improvement of cerebrovascular function with aerobic exercise training contributes to brain health in older adults. We summarized evidence in this brief review that 1) increases in central arterial stiffness and arterial pulsation with age are associated with increases in cerebrovascular resistance, reduction in cerebral blood flow, and cerebrovascular dysfunction, 2) aerobic exercise training improves cerebral blood flow by modifying arterial aging as indicated by reductions in cerebrovascular resistance, central arterial stiffness, arterial pulsation, and improvement in cerebrovascular function, and 3) improvement in cerebral blood flow and cerebrovascular function with aerobic exercise training may lead to improvement in cognitive function. These findings highlight the associations between arterial aging and cerebrovascular function and the importance of aerobic exercise in maintaining brain health in older adults.
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Affiliation(s)
- Tsubasa Tomoto
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Departments of Neurology
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Departments of Neurology
- Internal Medicine, and
- Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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2
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Dempsey S, Argus F, Maso Talou GD, Safaei S. An interaction graph approach to gain new insights into mechanisms that modulate cerebrovascular tone. Commun Biol 2024; 7:404. [PMID: 38570584 PMCID: PMC10991376 DOI: 10.1038/s42003-024-06064-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 03/18/2024] [Indexed: 04/05/2024] Open
Abstract
Mechanisms to modulate cerebrovascular tone are numerous, interconnected, and spatially dependent, increasing the complexity of experimental study design, interpretation of action-effect pathways, and mechanistic modelling. This difficulty is exacerbated when there is an incomplete understanding of these pathways. We propose interaction graphs to break down this complexity, while still maintaining a holistic view of mechanisms to modulate cerebrovascular tone. These graphs highlight the competing processes of neurovascular coupling, cerebral autoregulation, and cerebral reactivity. Subsequent analysis of these interaction graphs provides new insights and suggest potential directions for research on neurovascular coupling, modelling, and dementia.
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Affiliation(s)
- Sergio Dempsey
- Auckland Bioengineering Institute, University of Auckland, Level 6/70 Symonds Street, Grafton, Auckland, 1010, New Zealand.
| | - Finbar Argus
- Auckland Bioengineering Institute, University of Auckland, Level 6/70 Symonds Street, Grafton, Auckland, 1010, New Zealand
| | - Gonzalo Daniel Maso Talou
- Auckland Bioengineering Institute, University of Auckland, Level 6/70 Symonds Street, Grafton, Auckland, 1010, New Zealand
| | - Soroush Safaei
- Auckland Bioengineering Institute, University of Auckland, Level 6/70 Symonds Street, Grafton, Auckland, 1010, New Zealand
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3
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Li W, Tiedt S, Lawrence JH, Harrington ME, Musiek ES, Lo EH. Circadian Biology and the Neurovascular Unit. Circ Res 2024; 134:748-769. [PMID: 38484026 DOI: 10.1161/circresaha.124.323514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 02/14/2024] [Indexed: 03/19/2024]
Abstract
Mammalian physiology and cellular function are subject to significant oscillations over the course of every 24-hour day. It is likely that these daily rhythms will affect function as well as mechanisms of disease in the central nervous system. In this review, we attempt to survey and synthesize emerging studies that investigate how circadian biology may influence the neurovascular unit. We examine how circadian clocks may operate in neural, glial, and vascular compartments, review how circadian mechanisms regulate cell-cell signaling, assess interactions with aging and vascular comorbidities, and finally ask whether and how circadian effects and disruptions in rhythms may influence the risk and progression of pathophysiology in cerebrovascular disease. Overcoming identified challenges and leveraging opportunities for future research might support the development of novel circadian-based treatments for stroke.
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Affiliation(s)
- Wenlu Li
- Neuroprotection Research Laboratories, Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston (W.L., E.H.L.)
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
| | - Steffen Tiedt
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
- Institute for Stroke and Dementia Research, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany (S.T.)
| | - Jennifer H Lawrence
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
- Department of Neurology, Washington University School of Medicine, St. Louis, MO (J.H.L., E.S.M.)
| | - Mary E Harrington
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
- Neuroscience Program, Smith College, Northampton, MA (M.E.H.)
| | - Erik S Musiek
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
- Department of Neurology, Washington University School of Medicine, St. Louis, MO (J.H.L., E.S.M.)
| | - Eng H Lo
- Neuroprotection Research Laboratories, Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston (W.L., E.H.L.)
- Consortium International pour la Recherche Circadienne sur l'AVC, Munich, Germany (W.L., S.T., J.H.L., M.E.H., E.S.M., E.H.L.)
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4
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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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5
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Zeylan M, Senyuz S, Picón-Pagès P, García-Elías A, Tajes M, Muñoz FJ, Oliva B, Garcia-Ojalvo J, Barbu E, Vicente R, Nattel S, Ois A, Puig-Pijoan A, Keskin O, Gursoy A. Shared Proteins and Pathways of Cardiovascular and Cognitive Diseases: Relation to Vascular Cognitive Impairment. J Proteome Res 2024; 23:560-573. [PMID: 38252700 PMCID: PMC10846560 DOI: 10.1021/acs.jproteome.3c00289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 09/29/2023] [Accepted: 12/06/2023] [Indexed: 01/24/2024]
Abstract
One of the primary goals of systems medicine is the detection of putative proteins and pathways involved in disease progression and pathological phenotypes. Vascular cognitive impairment (VCI) is a heterogeneous condition manifesting as cognitive impairment resulting from vascular factors. The precise mechanisms underlying this relationship remain unclear, which poses challenges for experimental research. Here, we applied computational approaches like systems biology to unveil and select relevant proteins and pathways related to VCI by studying the crosstalk between cardiovascular and cognitive diseases. In addition, we specifically included signals related to oxidative stress, a common etiologic factor tightly linked to aging, a major determinant of VCI. Our results show that pathways associated with oxidative stress are quite relevant, as most of the prioritized vascular cognitive genes and proteins were enriched in these pathways. Our analysis provided a short list of proteins that could be contributing to VCI: DOLK, TSC1, ATP1A1, MAPK14, YWHAZ, CREB3, HSPB1, PRDX6, and LMNA. Moreover, our experimental results suggest a high implication of glycative stress, generating oxidative processes and post-translational protein modifications through advanced glycation end-products (AGEs). We propose that these products interact with their specific receptors (RAGE) and Notch signaling to contribute to the etiology of VCI.
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Affiliation(s)
- Melisa
E. Zeylan
- Computational
Sciences and Engineering, Graduate School of Science and Engineering, Koç University, Istanbul 34450, Türkiye
| | - Simge Senyuz
- Computational
Sciences and Engineering, Graduate School of Science and Engineering, Koç University, Istanbul 34450, Türkiye
| | - Pol Picón-Pagès
- Laboratory
of Molecular Physiology, Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Anna García-Elías
- Laboratory
of Molecular Physiology, Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Marta Tajes
- Laboratory
of Molecular Physiology, Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Francisco J. Muñoz
- Laboratory
of Molecular Physiology, Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Baldomero Oliva
- Laboratory
of Structural Bioinformatics (GRIB), Department of Medicine and Life
Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Jordi Garcia-Ojalvo
- Laboratory
of Dynamical Systems Biology, Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08002, Spain
| | - Eduard Barbu
- Institute
of Computer Science, University of Tartu, Tartu, 50090, Estonia
| | - Raul Vicente
- Institute
of Computer Science, University of Tartu, Tartu, 50090, Estonia
| | - Stanley Nattel
- Department
of Medicine and Research Center, Montreal Heart Institute and Université
de Montréal; Institute of Pharmacology, West German Heart and
Vascular Center, University Duisburg-Essen,
Germany; IHU LIRYC and Fondation Bordeaux Université, Bordeaux 33000, France
| | - Angel Ois
- Department
of Neurology, Hospital Del Mar. Hospital
Del Mar - Medical Research Institute and Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Albert Puig-Pijoan
- Department
of Neurology, Hospital Del Mar. Hospital
Del Mar - Medical Research Institute and Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Ozlem Keskin
- Department
of Chemical and Biological Engineering, Koç University, Istanbul 34450, Türkiye
| | - Attila Gursoy
- Department
of Computer Engineering, Koç University, Istanbul 34450, Türkiye
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6
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Sams A, Haanes KA, Holm A, Kazantzi S, Mikkelsen LF, Edvinsson L, Brain S, Sheykhzade M. Heterogeneous vasomotor responses in segments from Göttingen Minipigs coronary, cerebral, and mesenteric artery: A comparative study. Vascul Pharmacol 2023; 153:107231. [PMID: 37730143 DOI: 10.1016/j.vph.2023.107231] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 09/22/2023]
Abstract
Göttingen Minipigs (GM) are used as an important preclinical model for cardiovascular safety pharmacology and for evaluation of cardiovascular drug targets. To improve the translational value of the GM model, the current study represents a basic characterization of vascular responses to endothelial regulators and sympathetic, parasympathetic, and sensory neurotransmitters in different anatomical origins. The aim of the current comparative and descriptive study is to use myography to characterize the vasomotor responses of coronary artery isolated from GM and compare the responses to those obtained from parallel studies using cerebral and mesenteric arteries. The selected agonists for sympathetic (norepinephrine), parasympathetic (carbachol), sensory (calcitonin gene-related peptide, CGRP), and endothelial pathways (endothelin-1, ET-1, and bradykinin) were used for comparison. Further, the robust nature of the vasomotor responses was evaluated after 24 h of cold storage of vascular tissue mimicking the situation under which human biopsies are often kept before experiments or grafting is feasible. Results show that bradykinin and CGRP consistently dilated, and endothelin consistently contracted artery segments from coronary, cerebral, and mesenteric origin. By comparison, norepinephrine and carbachol, had responses that varied with the anatomical source of the tissues. To support the basic characterization of GM vasomotor responses, we demonstrated the presence of mRNA encoding selected vascular receptors (CGRP- and ETA-receptors) in fresh artery segments. In conclusion, the vasomotor responses of isolated coronary, cerebral, and mesenteric arteries to selected agonists of endothelial, sympathetic, parasympathetic, and sensory pathways are different and the phenotypes are similar to sporadic human findings.
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Affiliation(s)
- Anette Sams
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Clinical Experimental Research, Rigshospitalet, Glostrup, Denmark; Epoqe Pharma, Ole Maaloes Vej 3, 2200 Copenhagen N, Denmark.
| | | | - Anja Holm
- Department of Clinical Experimental Research, Rigshospitalet, Glostrup, Denmark; Center for RNA Medicine, Department of Clinical Medicine, Aalborg University, Copenhagen, Denmark
| | - Spyridoula Kazantzi
- Department of Clinical Experimental Research, Rigshospitalet, Glostrup, Denmark
| | | | - Lars Edvinsson
- Department of Clinical Experimental Research, Rigshospitalet, Glostrup, Denmark
| | - Susan Brain
- Section of Vascular Biology & Inflammation, School of Cardiovascular Medicine & Research, BHF Centre of Excellence, King's College London, London, United Kingdom
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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7
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James S, Sanggaard S, Akif A, Mishra SK, Sanganahalli BG, Blumenfeld H, Verhagen JV, Hyder F, Herman P. Spatiotemporal features of neurovascular (un)coupling with stimulus-induced activity and hypercapnia challenge in cerebral cortex and olfactory bulb. J Cereb Blood Flow Metab 2023; 43:1891-1904. [PMID: 37340791 PMCID: PMC10676132 DOI: 10.1177/0271678x231183887] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 06/22/2023]
Abstract
Carbon dioxide (CO2) is traditionally considered as metabolic waste, yet its regulation is critical for brain function. It is well accepted that hypercapnia initiates vasodilation, but its effect on neuronal activity is less clear. Distinguishing how stimulus- and CO2-induced vasodilatory responses are (dis)associated with neuronal activity has profound clinical and experimental relevance. We used an optical method in mice to simultaneously image fluorescent calcium (Ca2+) transients from neurons and reflectometric hemodynamic signals during brief sensory stimuli (i.e., hindpaw, odor) and CO2 exposure (i.e., 5%). Stimuli-induced neuronal and hemodynamic responses swiftly increased within locally activated regions exhibiting robust neurovascular coupling. However, hypercapnia produced slower global vasodilation which was temporally uncoupled to neuronal deactivation. With trends consistent across cerebral cortex and olfactory bulb as well as data from GCaMP6f/jRGECO1a mice (i.e., green/red Ca2+ fluorescence), these results unequivocally reveal that stimuli and CO2 generate comparable vasodilatory responses but contrasting neuronal responses. In summary, observations of stimuli-induced regional neurovascular coupling and CO2-induced global neurovascular uncoupling call for careful appraisal when using CO2 in gas mixtures to affect vascular tone and/or neuronal excitability, because CO2 is both a potent vasomodulator and a neuromodulator.
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Affiliation(s)
- Shaun James
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Simon Sanggaard
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Adil Akif
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Sandeep K Mishra
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | | | - Hal Blumenfeld
- Department of Neurology, Yale University, New Haven, CT, USA
- Department of Neuroscience, Yale University, New Haven, CT, USA
| | - Justus V Verhagen
- Department of Neuroscience, Yale University, New Haven, CT, USA
- John B. Pierce Laboratory, New Haven, CT, USA
| | - Fahmeed Hyder
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Peter Herman
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
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8
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Siddiqui M, Pinti P, Brigadoi S, Lloyd-Fox S, Elwell CE, Johnson MH, Tachtsidis I, Jones EJH. Using multi-modal neuroimaging to characterise social brain specialisation in infants. eLife 2023; 12:e84122. [PMID: 37818944 PMCID: PMC10624424 DOI: 10.7554/elife.84122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/10/2023] [Indexed: 10/13/2023] Open
Abstract
The specialised regional functionality of the mature human cortex partly emerges through experience-dependent specialisation during early development. Our existing understanding of functional specialisation in the infant brain is based on evidence from unitary imaging modalities and has thus focused on isolated estimates of spatial or temporal selectivity of neural or haemodynamic activation, giving an incomplete picture. We speculate that functional specialisation will be underpinned by better coordinated haemodynamic and metabolic changes in a broadly orchestrated physiological response. To enable researchers to track this process through development, we develop new tools that allow the simultaneous measurement of coordinated neural activity (EEG), metabolic rate, and oxygenated blood supply (broadband near-infrared spectroscopy) in the awake infant. In 4- to 7-month-old infants, we use these new tools to show that social processing is accompanied by spatially and temporally specific increases in coupled activation in the temporal-parietal junction, a core hub region of the adult social brain. During non-social processing, coupled activation decreased in the same region, indicating specificity to social processing. Coupling was strongest with high-frequency brain activity (beta and gamma), consistent with the greater energetic requirements and more localised action of high-frequency brain activity. The development of simultaneous multimodal neural measures will enable future researchers to open new vistas in understanding functional specialisation of the brain.
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Affiliation(s)
- Maheen Siddiqui
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
| | - Paola Pinti
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
| | - Sabrina Brigadoi
- Department of Development and Social Psychology, University of PadovaPadovaItaly
- Department of Information Engineering, University of PadovaPadovaItaly
| | - Sarah Lloyd-Fox
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
| | - Clare E Elwell
- Department of Medical Physics and Biomedical Engineering, University College LondonLondonUnited Kingdom
| | - Mark H Johnson
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College LondonLondonUnited Kingdom
| | - Emily JH Jones
- Centre for Brain and Cognitive Development, Birkbeck, University of LondonLondonUnited Kingdom
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9
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Gonye EC, Bayliss DA. Criteria for central respiratory chemoreceptors: experimental evidence supporting current candidate cell groups. Front Physiol 2023; 14:1241662. [PMID: 37719465 PMCID: PMC10502317 DOI: 10.3389/fphys.2023.1241662] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023] Open
Abstract
An interoceptive homeostatic system monitors levels of CO2/H+ and provides a proportionate drive to respiratory control networks that adjust lung ventilation to maintain physiologically appropriate levels of CO2 and rapidly regulate tissue acid-base balance. It has long been suspected that the sensory cells responsible for the major CNS contribution to this so-called respiratory CO2/H+ chemoreception are located in the brainstem-but there is still substantial debate in the field as to which specific cells subserve the sensory function. Indeed, at the present time, several cell types have been championed as potential respiratory chemoreceptors, including neurons and astrocytes. In this review, we advance a set of criteria that are necessary and sufficient for definitive acceptance of any cell type as a respiratory chemoreceptor. We examine the extant evidence supporting consideration of the different putative chemoreceptor candidate cell types in the context of these criteria and also note for each where the criteria have not yet been fulfilled. By enumerating these specific criteria we hope to provide a useful heuristic that can be employed both to evaluate the various existing respiratory chemoreceptor candidates, and also to focus effort on specific experimental tests that can satisfy the remaining requirements for definitive acceptance.
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Affiliation(s)
- Elizabeth C. Gonye
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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10
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Li K, Abbott SBG, Guyenet PG, Bayliss DA. JP-RL-2023-285396: Reply to 'Letter to the Editor' (JP-LE-2023-285385). J Physiol 2023; 601:4173-4175. [PMID: 37610165 DOI: 10.1113/jp285396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 08/24/2023] Open
Affiliation(s)
- Keyong Li
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Stephen B G Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
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11
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Li K, Gonye EC, Stornetta RL, Bayliss CB, Yi G, Stornetta DS, Baca SM, Abbott SB, Guyenet PG, Bayliss DA. The astrocytic Na + -HCO 3 - cotransporter, NBCe1, is dispensable for respiratory chemosensitivity. J Physiol 2023; 601:3667-3686. [PMID: 37384821 PMCID: PMC10528273 DOI: 10.1113/jp284960] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/02/2023] [Indexed: 07/01/2023] Open
Abstract
The interoceptive homeostatic mechanism that controls breathing, blood gases and acid-base balance in response to changes in CO2 /H+ is exquisitely sensitive, with convergent roles proposed for chemosensory brainstem neurons in the retrotrapezoid nucleus (RTN) and their supporting glial cells. For astrocytes, a central role for NBCe1, a Na+ -HCO3 - cotransporter encoded by Slc4a4, has been envisaged in multiple mechanistic models (i.e. underlying enhanced CO2 -induced local extracellular acidification or purinergic signalling). We tested these NBCe1-centric models by using conditional knockout mice in which Slc4a4 was deleted from astrocytes. In GFAP-Cre;Slc4a4fl/fl mice we found diminished expression of Slc4a4 in RTN astrocytes by comparison to control littermates, and a concomitant reduction in NBCe1-mediated current. Despite disrupted NBCe1 function in RTN-adjacent astrocytes from these conditional knockout mice, CO2 -induced activation of RTN neurons or astrocytes in vitro and in vivo, and CO2 -stimulated breathing, were indistinguishable from NBCe1-intact littermates; hypoxia-stimulated breathing and sighs were likewise unaffected. We obtained a more widespread deletion of NBCe1 in brainstem astrocytes by using tamoxifen-treated Aldh1l1-Cre/ERT2;Slc4a4fl/fl mice. Again, there was no difference in effects of CO2 or hypoxia on breathing or on neuron/astrocyte activation in NBCe1-deleted mice. These data indicate that astrocytic NBCe1 is not required for the respiratory responses to these chemoreceptor stimuli in mice, and that any physiologically relevant astrocytic contributions must involve NBCe1-independent mechanisms. KEY POINTS: The electrogenic NBCe1 transporter is proposed to mediate local astrocytic CO2 /H+ sensing that enables excitatory modulation of nearby retrotrapezoid nucleus (RTN) neurons to support chemosensory control of breathing. We used two different Cre mouse lines for cell-specific and/or temporally regulated deletion of the NBCe1 gene (Slc4a4) in astrocytes to test this hypothesis. In both mouse lines, Slc4a4 was depleted from RTN-associated astrocytes but CO2 -induced Fos expression (i.e. cell activation) in RTN neurons and local astrocytes was intact. Likewise, respiratory chemoreflexes evoked by changes in CO2 or O2 were unaffected by loss of astrocytic Slc4a4. These data do not support the previously proposed role for NBCe1 in respiratory chemosensitivity mediated by astrocytes.
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Affiliation(s)
- Keyong Li
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Elizabeth C. Gonye
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Ruth L. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | | | - Grace Yi
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Daniel S. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Serapio M. Baca
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Stephen B.G. Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Patrice G. Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Douglas A. Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
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12
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Barros LF, Ruminot I, Sandoval PY, San Martín A. Enlightening brain energy metabolism. Neurobiol Dis 2023:106211. [PMID: 37352985 DOI: 10.1016/j.nbd.2023.106211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/06/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023] Open
Abstract
Brain tissue metabolism is distributed across several cell types and subcellular compartments, which activate at different times and with different temporal patterns. The introduction of genetically-encoded fluorescent indicators that are imaged using time-lapse microscopy has opened the possibility of studying brain metabolism at cellular and sub-cellular levels. There are indicators for sugars, monocarboxylates, Krebs cycle intermediates, amino acids, cofactors, and energy nucleotides, which inform about relative levels, concentrations and fluxes. This review offers a brief survey of the metabolic indicators that have been validated in brain cells, with some illustrative examples from the literature. Whereas only a small fraction of the metabolome is currently accessible to fluorescent probes, there are grounds to be optimistic about coming developments and the application of these tools to the study of brain disease.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile.
| | - I Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
| | - P Y Sandoval
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
| | - A San Martín
- Centro de Estudios Científicos (CECs), Valdivia, Chile; Facultad de Ciencias para el Cuidado de La Salud, Universidad San Sebastián, Valdivia, Chile
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13
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Rivers RJ, Meininger CJ. The Tissue Response to Hypoxia: How Therapeutic Carbon Dioxide Moves the Response toward Homeostasis and Away from Instability. Int J Mol Sci 2023; 24:ijms24065181. [PMID: 36982254 PMCID: PMC10048965 DOI: 10.3390/ijms24065181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/02/2023] [Accepted: 03/05/2023] [Indexed: 03/30/2023] Open
Abstract
Sustained tissue hypoxia is associated with many pathophysiological conditions, including chronic inflammation, chronic wounds, slow-healing fractures, microvascular complications of diabetes, and metastatic spread of tumors. This extended deficiency of oxygen (O2) in the tissue sets creates a microenvironment that supports inflammation and initiates cell survival paradigms. Elevating tissue carbon dioxide levels (CO2) pushes the tissue environment toward "thrive mode," bringing increased blood flow, added O2, reduced inflammation, and enhanced angiogenesis. This review presents the science supporting the clinical benefits observed with the administration of therapeutic CO2. It also presents the current knowledge regarding the cellular and molecular mechanisms responsible for the biological effects of CO2 therapy. The most notable findings of the review include (a) CO2 activates angiogenesis not mediated by hypoxia-inducible factor 1a, (b) CO2 is strongly anti-inflammatory, (c) CO2 inhibits tumor growth and metastasis, and (d) CO2 can stimulate the same pathways as exercise and thereby, acts as a critical mediator in the biological response of skeletal muscle to tissue hypoxia.
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Affiliation(s)
- Richard J Rivers
- Department of Anesthesia and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Cynthia J Meininger
- Department of Medical Physiology, Texas A&M University School of Medicine, Bryan, TX 77807, USA
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14
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Barros LF, Ruminot I, Sotelo-Hitschfeld T, Lerchundi R, Fernández-Moncada I. Metabolic Recruitment in Brain Tissue. Annu Rev Physiol 2023; 85:115-135. [PMID: 36270291 DOI: 10.1146/annurev-physiol-021422-091035] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Information processing imposes urgent metabolic demands on neurons, which have negligible energy stores and restricted access to fuel. Here, we discuss metabolic recruitment, the tissue-level phenomenon whereby active neurons harvest resources from their surroundings. The primary event is the neuronal release of K+ that mirrors workload. Astrocytes sense K+ in exquisite fashion thanks to their unique coexpression of NBCe1 and α2β2 Na+/K+ ATPase, and within seconds switch to Crabtree metabolism, involving GLUT1, aerobic glycolysis, transient suppression of mitochondrial respiration, and lactate export. The lactate surge serves as a secondary recruiter by inhibiting glucose consumption in distant cells. Additional recruiters are glutamate, nitric oxide, and ammonium, which signal over different spatiotemporal domains. The net outcome of these events is that more glucose, lactate, and oxygen are made available. Metabolic recruitment works alongside neurovascular coupling and various averaging strategies to support the inordinate dynamic range of individual neurons.
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Affiliation(s)
- L F Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile; .,Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile;
| | - I Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile; .,Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile;
| | - T Sotelo-Hitschfeld
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - R Lerchundi
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), MIRCen, Fontenay-aux-Roses, France
| | - I Fernández-Moncada
- NeuroCentre Magendie, INSERM U1215, University of Bordeaux, Bordeaux, France
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15
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Hariharan A, Robertson CD, Garcia DCG, Longden TA. Brain capillary pericytes are metabolic sentinels that control blood flow through a K ATP channel-dependent energy switch. Cell Rep 2022; 41:111872. [PMID: 36577387 PMCID: PMC10187957 DOI: 10.1016/j.celrep.2022.111872] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 10/10/2022] [Accepted: 11/30/2022] [Indexed: 12/28/2022] Open
Abstract
Despite the abundance of capillary thin-strand pericytes and their proximity to neurons and glia, little is known of the contributions of these cells to the control of brain hemodynamics. We demonstrate that the pharmacological activation of thin-strand pericyte KATP channels profoundly hyperpolarizes these cells, dilates upstream penetrating arterioles and arteriole-proximate capillaries, and increases capillary blood flow. Focal stimulation of pericytes with a KATP channel agonist is sufficient to evoke this response, mediated via KIR2.1 channel-dependent retrograde propagation of hyperpolarizing signals, whereas genetic inactivation of pericyte KATP channels eliminates these effects. Critically, we show that decreasing extracellular glucose to less than 1 mM or inhibiting glucose uptake by blocking GLUT1 transporters in vivo flips a mechanistic energy switch driving rapid KATP-mediated pericyte hyperpolarization to increase local blood flow. Together, our findings recast capillary pericytes as metabolic sentinels that respond to local energy deficits by increasing blood flow to neurons to prevent energetic shortfalls.
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Affiliation(s)
- Ashwini Hariharan
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Colin D Robertson
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Daniela C G Garcia
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA; Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD, USA.
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16
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Astrocytes amplify neurovascular coupling to sustained activation of neocortex in awake mice. Nat Commun 2022; 13:7872. [PMID: 36550102 PMCID: PMC9780254 DOI: 10.1038/s41467-022-35383-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 11/30/2022] [Indexed: 12/24/2022] Open
Abstract
Functional hyperemia occurs when enhanced neuronal activity signals to increase local cerebral blood flow (CBF) to satisfy regional energy demand. Ca2+ elevation in astrocytes can drive arteriole dilation to increase CBF, yet affirmative evidence for the necessity of astrocytes in functional hyperemia in vivo is lacking. In awake mice, we discovered that functional hyperemia is bimodal with a distinct early and late component whereby arteriole dilation progresses as sensory stimulation is sustained. Clamping astrocyte Ca2+ signaling in vivo by expressing a plasma membrane Ca2+ ATPase (CalEx) reduces sustained but not brief sensory-evoked arteriole dilation. Elevating astrocyte free Ca2+ using chemogenetics selectively augments sustained hyperemia. Antagonizing NMDA-receptors or epoxyeicosatrienoic acid production reduces only the late component of functional hyperemia, leaving brief increases in CBF to sensory stimulation intact. We propose that a fundamental role of astrocyte Ca2+ is to amplify functional hyperemia when neuronal activation is prolonged.
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17
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Liu X, Czosnyka M, Robba C, Ming D. Editorial: Cerebral autoregulation and neurovascular coupling in brain disorders. Front Neurol 2022; 13:1001342. [PMID: 36158967 PMCID: PMC9501687 DOI: 10.3389/fneur.2022.1001342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 08/17/2022] [Indexed: 12/03/2022] Open
Affiliation(s)
- Xiuyun Liu
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
| | - Marek Czosnyka
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Chiara Robba
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, Genoa, Italy
- San Martino Policlinico Hospital, Istituto di Ricovero e Cura a Carattere Scientifico for Oncology and Neuroscience, Genoa, Italy
| | - Dong Ming
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
- *Correspondence: Dong Ming
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18
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Skow RJ, Brothers RM, Claassen JAHR, Day TA, Rickards CA, Smirl JD, Brassard P. On the use and misuse of cerebral hemodynamics terminology using Transcranial Doppler ultrasound: a call for standardization. Am J Physiol Heart Circ Physiol 2022; 323:H350-H357. [PMID: 35839156 DOI: 10.1152/ajpheart.00107.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cerebral hemodynamics (e.g., cerebral blood flow) can be measured and quantified using many different methods, with Transcranial Doppler ultrasound (TCD) being one of the most commonly utilized approaches. In human physiology, the terminology used to describe metrics of cerebral hemodynamics are inconsistent, and in some instances technically inaccurate; this is especially true when evaluating, reporting, and interpreting measures from TCD. Therefore, this perspectives article presents recommended terminology when reporting cerebral hemodynamic data. We discuss the current use and misuse of the terminology in the context of using TCD to measure and quantify cerebral hemodynamics and present our rationale and consensus on the terminology that we recommend moving forward. For example, one recommendation is to discontinue use of the term "cerebral blood flow velocity" in favor of "cerebral blood velocity" with precise indication of the vessel of interest. We also recommend clarity when differentiating between discrete cerebrovascular regulatory mechanisms, namely cerebral autoregulation, neurovascular coupling, and cerebrovascular reactivity. This will be a useful guide for investigators in the field of cerebral hemodynamics research.
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Affiliation(s)
- Rachel J Skow
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| | - R Matthew Brothers
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| | - Jurgen A H R Claassen
- Department of Geriatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Caroline A Rickards
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Jonathan D Smirl
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Canada
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