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Bailey DM. Oxygen and brain death; back from the brink. Exp Physiol 2020; 104:1769-1779. [PMID: 31605408 DOI: 10.1113/ep088005] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/09/2019] [Indexed: 12/25/2022]
Abstract
NEW FINDINGS • What is the topic of this review? To explore the unique evolutionary origins of the human brain and critically appraise its energy budget, including limits of oxygen and glucose deprivation during anoxia and ischaemia. • What advances does it highlight? The brain appears to be more resilient to substrate depletion than traditionally thought, highlighting greater resilience and an underappreciated capacity for functional recovery. ABSTRACT The human brain has evolved into an unusually large, complex and metabolically expensive organ that relies entirely on a continuous supply of O2 and glucose. It has traditionally been assumed that its exorbitant energy budget, combined with little to no energy reserves, renders it especially vulnerable to anoxia and ischaemia, with substrate depletion and progression towards cell death largely irreversible and rapid. However, new and exciting evidence suggests that neurons can survive for longer than previously thought, highlighting an unexpected resilience and underappreciated capacity for functional recovery that has changed the way we think about brain cell death. Nature has the potential to unlock some of the mysteries underlying ischaemic survival, with select vertebrates having solved the problem of anoxia-hypoxia tolerance over millions of years of evolution. Better understanding of their survival strategies, including remarkable adaptations in brain physiology and redox homeostasis, might help to identify new therapeutic targets for human diseases characterized by O2 deprivation, ischaemia-reperfusion injury and ageing.
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Affiliation(s)
- Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, Glamorgan, UK
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Calverley TA, Ogoh S, Marley CJ, Steggall M, Marchi N, Brassard P, Lucas SJE, Cotter JD, Roig M, Ainslie PN, Wisløff U, Bailey DM. HIITing the brain with exercise: mechanisms, consequences and practical recommendations. J Physiol 2020; 598:2513-2530. [PMID: 32347544 DOI: 10.1113/jp275021] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/15/2020] [Indexed: 01/30/2023] Open
Abstract
The increasing number of older adults has seen a corresponding growth in those affected by neurovascular diseases, including stroke and dementia. Since cures are currently unavailable, major efforts in improving brain health need to focus on prevention, with emphasis on modifiable risk factors such as promoting physical activity. Moderate-intensity continuous training (MICT) paradigms have been shown to confer vascular benefits translating into improved musculoskeletal, cardiopulmonary and cerebrovascular function. However, the time commitment associated with MICT is a potential barrier to participation, and high-intensity interval training (HIIT) has since emerged as a more time-efficient mode of exercise that can promote similar if not indeed superior improvements in cardiorespiratory fitness for a given training volume and further promote vascular adaptation. However, randomised controlled trials (RCTs) investigating the impact of HIIT on the brain are surprisingly limited. The present review outlines how the HIIT paradigm has evolved from a historical perspective and describes the established physiological changes including its mechanistic bases. Given the dearth of RCTs, the vascular benefits of MICT are discussed with a focus on the translational neuroprotective benefits including their mechanistic bases that could be further potentiated through HIIT. Safety implications are highlighted and components of an optimal HIIT intervention are discussed including practical recommendations. Finally, statistical effect sizes have been calculated to allow prospective research to be appropriately powered and optimise the potential for detecting treatment effects. Future RCTs that focus on the potential clinical benefits of HIIT are encouraged given the prevalence of cognitive decline in an ever-ageing population.
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Affiliation(s)
- Thomas A Calverley
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - Shigehiko Ogoh
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK.,Department of Biomedical Engineering, Faculty of Engineering, Toyo University, Saitama, Japan
| | - Christopher J Marley
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - Martin Steggall
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - Nicola Marchi
- Cerebrovascular and Glia Research Laboratory, Department of Neuroscience, Institute of Functional Genomics, Montpellier, France
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Marc Roig
- Faculty of Medicine, McGill University, Montreal, Canada
| | - Philip N Ainslie
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK.,Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, BC, Canada
| | - Ulrik Wisløff
- The Cardiac Exercise Research Group, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.,School of Human Movement and Nutrition Science, University of Queensland, Queensland, Australia
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
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Bailey DM. Elemental 'particle physics-iology'; the Big Bang behind being human. Exp Physiol 2020; 105:401-407. [PMID: 31943409 DOI: 10.1113/ep088292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/13/2020] [Indexed: 01/03/2023]
Affiliation(s)
- Damian Miles Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
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Homologous bd oxidases share the same architecture but differ in mechanism. Nat Commun 2019; 10:5138. [PMID: 31723136 PMCID: PMC6853902 DOI: 10.1038/s41467-019-13122-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/22/2019] [Indexed: 11/25/2022] Open
Abstract
Cytochrome bd oxidases are terminal reductases of bacterial and archaeal respiratory chains. The enzyme couples the oxidation of ubiquinol or menaquinol with the reduction of dioxygen to water, thus contributing to the generation of the protonmotive force. Here, we determine the structure of the Escherichia coli bd oxidase treated with the specific inhibitor aurachin by cryo-electron microscopy (cryo-EM). The major subunits CydA and CydB are related by a pseudo two fold symmetry. The heme b and d cofactors are found in CydA, while ubiquinone-8 is bound at the homologous positions in CydB to stabilize its structure. The architecture of the E. coli enzyme is highly similar to that of Geobacillus thermodenitrificans, however, the positions of heme b595 and d are interchanged, and a common oxygen channel is blocked by a fourth subunit and substituted by a more narrow, alternative channel. Thus, with the same overall fold, the homologous enzymes exhibit a different mechanism. Cytochrome bd oxidases couple quinol oxidation and the release of protons to the periplasmic side with proton uptake from the cytoplasmic side to reduce dioxygen to water and they are the terminal reductases in bacterial and archaeal respiratory chains. Here the authors present the cryo-EM structure of Escherichia coli bd oxidase and discuss mechanistic implications.
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Tipton M. Heresy and transparency: Is sunlight the best disinfectant? Exp Physiol 2019; 104:1439-1440. [DOI: 10.1113/ep088084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Mike Tipton
- Extreme Environments Laboratory, Department of Sport & Exercise ScienceUniversity of Portsmouth Portsmouth UK
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Miller DJ, Eisner DA. Electro‐physics‐iology clarified? No spooky action required. Exp Physiol 2019; 104:1432-1433. [DOI: 10.1113/ep087931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 06/24/2019] [Indexed: 11/08/2022]
Affiliation(s)
| | - David A. Eisner
- Unit of Cardiac PhysiologyManchester Academic Health Science CentreUniversity of Manchester3.18 Core Technology Facility Manchester UK
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Bailey DM. Electrons or ions? That is the (quantum) question! Exp Physiol 2019; 104:985-986. [PMID: 31148325 DOI: 10.1113/ep087660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 02/25/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Glamorgan, UK
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