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Katagiri A, Fujii N, Dobashi K, Lai YF, Tsuji B, Nishiyasu T. Effects of sodium bicarbonate ingestion on ventilatory and cerebrovascular responses in resting heated humans. Am J Physiol Regul Integr Comp Physiol 2024; 327:R400-R409. [PMID: 39102461 DOI: 10.1152/ajpregu.00161.2024] [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: 06/20/2024] [Revised: 07/22/2024] [Accepted: 07/23/2024] [Indexed: 08/07/2024]
Abstract
Hyperthermia stimulates ventilation in humans. This hyperthermia-induced hyperventilation may be mediated by the activation of peripheral chemoreceptors implicated in the regulation of respiration in reaction to various chemical stimuli, including reductions in arterial pH. Here, we investigated the hypothesis that during passive heating at rest, the increases in arterial pH achieved with sodium bicarbonate ingestion, which could attenuate peripheral chemoreceptor activity, mitigate hyperthermia-induced hyperventilation. We also assessed the effect of sodium bicarbonate ingestion on cerebral blood flow responses, which are associated with hyperthermia-induced hyperventilation. Twelve healthy men ingested sodium bicarbonate (0.3 g/kg body weight) or sodium chloride (0.208 g/kg). One hundred minutes after the ingestion, the participants were passively heated using hot-water immersion (42°C) combined with a water-perfused suit. Increases in esophageal temperature (an index of core temperature) and minute ventilation (V̇E) during the heating were similar in the two trials. Moreover, when V̇E is expressed as a function of esophageal temperature, there were no between-trial differences in the core temperature threshold for hyperventilation (38.0 ± 0.3 vs. 38.0 ± 0.4°C, P = 0.469) and sensitivity of hyperthermia-induced hyperventilation as assessed by the slope of the core temperature-V̇E relation (13.5 ± 14.2 vs. 15.8 ± 15.5 L/min/°C, P = 0.831). Furthermore, middle cerebral artery mean blood velocity (an index of cerebral blood flow) decreased similarly with heating duration in both trials. These results suggest that sodium bicarbonate ingestion does not mitigate hyperthermia-induced hyperventilation and the reductions in cerebral blood flow index in resting heated humans.NEW & NOTEWORTHY Hyperthermia leads to hyperventilation and associated cerebral hypoperfusion, both of which may impair heat tolerance. This hyperthermia-induced hyperventilation may be mediated by peripheral chemoreceptors, which can be activated by reductions in arterial pH. However, our results suggest that sodium bicarbonate ingestion, which can increase arterial pH, is not an effective intervention in alleviating hyperthermia-induced hyperventilation and cerebral hypoperfusion in resting heated humans.
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Affiliation(s)
- Akira Katagiri
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Naoto Fujii
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- Advanced Research Initiative for Human High Performance, University of Tsukuba, Ibaraki, Japan
| | - Kohei Dobashi
- Faculty of Education, Hokkaido University of Education, Hokkaido, Japan
| | - Yin-Feng Lai
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Bun Tsuji
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- Advanced Research Initiative for Human High Performance, University of Tsukuba, Ibaraki, Japan
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Allison EY, Mei Y, Coombs GB, Mizzi V, Ismayilov H, Al-Khazraji BK. Effects of single- and bilateral limb immersion on systemic and cerebral hemodynamic responses to the cold pressor test. J Appl Physiol (1985) 2024; 137:873-882. [PMID: 39088646 DOI: 10.1152/japplphysiol.00328.2024] [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: 05/06/2024] [Revised: 07/30/2024] [Accepted: 07/31/2024] [Indexed: 08/03/2024] Open
Abstract
The cold pressor test (CPT) involves cold water immersion of either the upper or lower limb(s) and elicits increases in sympathetic nervous activity (SNA), heart rate (HR), and mean arterial pressure (MAP) via stimulation of pain and cutaneous thermoreceptors. Greater pain perception during the CPT is associated with greater increases in SNA and more robust physiological responses. Due to potential differential sensitivity to both painful and thermal stimuli between upper and lower limbs, as well as potential effects of total exposure area, it is unclear whether the choice of limb(s) in CPT protocol design differentially affects systemic and cerebral hemodynamic responses. Our objective was to assess systemic and cerebral hemodynamic and ventilatory responses to different CPT protocols of the hand (CPTH), foot (CPTF), or bilateral feet (CPTBF). We hypothesized CPTBF would elicit greatest physiological responses due to increased exposure area to the cold stimulus. Twenty-eight (14 M, 14 F) healthy young adults [23.4 (SD: 2.4) yr] participated in three 3-min CPT protocols during a single visit. Blood pressure, HR, middle cerebral artery blood velocity (MCAv) and cerebrovascular conductance index, and end-tidal carbon dioxide ([Formula: see text]) were averaged over the final 30 s of each minute of the CPT for each protocol, and perceived pain was recorded at the end of each minute of the CPT. We found significant effects of the time-CPT protocol interaction on systolic blood pressure (P = 0.02), diastolic blood pressure (P < 0.01), MAP (P < 0.01), and HR (P < 0.001). There were no differences between CPT protocols on either MCAv (P = 0.4) or cerebrovascular conductance index (P = 0.1). HR responses peaked in the first minute of the CPT, and changes from baseline were greater in CPTBF [Δ14(16) beats/min] compared with CPTH [Δ5(13) beats/min; P = 0.01] and CPTF [Δ4.04(13.3) beats/min; P = 0.02]. MAP responses peaked in minute 2 of the CPT, and changes from baseline were greater in CPTH [Δ12(8) mmHg) and CPTBF (Δ13(9) mmHg] compared with CPTF [Δ8(7) mmHg; P < 0.01]. Perceived pain was significantly greater in the CPTBF [CPT1 7(2.3), CPT2 6.5(2.3), CPT3 6(3)] condition compared with CPTH [CPT1 6(1.3), CPT2 6(2.3), CPT3 6(2.3)] and CPTF [CPT1 6(3.0), CPT2 6(2.0), CPT3 5.5(3.0)] protocols at all three stages of the CPT (P ≤ 0.01). Our findings suggest choice of limb(s) in CPT protocols may lead to differences in systemic hemodynamic responses, with pain perception potentially influencing these responses. Based on our results, we suggest that choice of limb should be considered in future design of CPT studies, with hand CPT providing the best balance between participant tolerability and robust physiological responses.NEW & NOTEWORTHY Choice of limb(s) in cold pressor test (CPT) studies appears to influence systemic hemodynamics. Hand and bilateral feet induce more robust responses than single-foot CPT, potentially due to increased exposure area and pain perception. Despite no significant cerebrovascular effects, a sustained hyperventilatory response was noted in bilateral feet CPT. Hand CPTs may provide a balance between robust physiological responses and tolerability. These findings underscore the need for careful limb selection in future CPT studies.
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Affiliation(s)
- Elric Y Allison
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Yixue Mei
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Geoff B Coombs
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
- School of Psychology and Sport Science, Bangor University, Bangor, Wales, United Kingdom
| | - Vanessa Mizzi
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Huseyn Ismayilov
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Baraa K Al-Khazraji
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
- School of Biomedical Engineering, Faculty of Engineering, McMaster University, Hamilton, Ontario, Canada
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Clough RH, Panerai RB, Ladthavorlaphatt K, Robinson TG, Minhas JS. The complexity of cerebral blood flow regulation: the interaction of posture and vasomotor reactivity. J Appl Physiol (1985) 2024; 137:892-902. [PMID: 39143908 DOI: 10.1152/japplphysiol.00851.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 08/09/2024] [Accepted: 08/09/2024] [Indexed: 08/16/2024] Open
Abstract
Arterial carbon dioxide ([Formula: see text]) and posture influence the middle (MCAv) and posterior (PCAv) cerebral artery blood velocities, but there is paucity of data about their interaction and need for an integrated model of their effects, including dynamic cerebral autoregulation (dCA). In 22 participants (11 males, age 30.2 ± 14.3 yr), blood pressure (BP, Finometer), dominant MCAv and nondominant PCAv (transcranial Doppler ultrasound), end-tidal CO2 (EtCO2, capnography), and heart rate (HR, ECG) were recorded continuously. Two recordings (R) were taken when the participant was supine (R1, R2), two taken when the participant was sitting (R3, R4), and two taken when the participant was standing (R5, R6). R1, R3, and R5 consisted of 3 min of 5% CO2 through a mask and R2, R4, and R6 consisted of 3 min of paced hyperventilation. The effects of [Formula: see text] were expressed with a logistic curve model (LCM) for each parameter. dCA was expressed by the autoregulation index (ARI), derived by transfer function analysis. Standing shifted LCM to the left for MCAv (P < 0.001), PCAv (P < 0.001), BP (P = 0.03), and ARI (P = 0.001); downward for MCAv and PCAv (both P < 0.001), and upward for HR (P < 0.001). For BP, LCM was shifted downward by sitting and standing (P = 0.024). For ARI, the hypercapnic range of LCM was shifted upward during standing (P < 0.001). A more complete mapping of the combined effects of posture and arterial CO2 on the cerebral circulation and peripheral variables can be obtained with the LCM over a broad physiological range of EtCO2 values.NEW & NOTEWORTHY Data from supine, sitting, and standing postures were measured. Modeling the data with logistic curves to express the effects of CO2 reactivity on middle cerebral artery blood velocity (MCAv), posterior cerebral artery blood velocity (PCAv), heart rate, blood pressure (BP), and the autoregulation index (ARI), provided a more comprehensive approach to study the interaction of arterial CO2 with posture than in previous studies. Above all, shifts of the logistic curve model with changes in posture have shown interactions with [Formula: see text] that have not been previously demonstrated.
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Affiliation(s)
- Rebecca H Clough
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Kannaphob Ladthavorlaphatt
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- Medical Diagnostics Unit, Thammasat University Hospital, Thammasat University, Pathumthani, Thailand
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
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Caldwell HG, Hoiland RL, Bain AR, Howe CA, Carr JMJR, Gibbons TD, Durrer CG, Tymko MM, Stacey BS, Bailey DM, Sekhon MS, MacLeod DB, Ainslie PN. Evidence for direct CO 2 -mediated alterations in cerebral oxidative metabolism in humans. Acta Physiol (Oxf) 2024; 240:e14197. [PMID: 38958262 DOI: 10.1111/apha.14197] [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: 11/15/2023] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/04/2024]
Abstract
AIM How the cerebral metabolic rates of oxygen and glucose utilization (CMRO2 and CMRGlc, respectively) are affected by alterations in arterial PCO2 (PaCO2) is equivocal and therefore was the primary question of this study. METHODS This retrospective analysis involved pooled data from four separate studies, involving 41 healthy adults (35 males/6 females). Participants completed stepwise steady-state alterations in PaCO2 ranging between 30 and 60 mmHg. The CMRO2 and CMRGlc were assessed via the Fick approach (CBF × arterial-internal jugular venous difference of oxygen or glucose content, respectively) utilizing duplex ultrasound of the internal carotid artery and vertebral artery to calculate cerebral blood flow (CBF). RESULTS The CMRO2 was altered by 0.5 mL × min-1 (95% CI: -0.6 to -0.3) per mmHg change in PaCO2 (p < 0.001) which corresponded to a 9.8% (95% CI: -13.2 to -6.5) change in CMRO2 with a 9 mmHg change in PaCO2 (inclusive of hypo- and hypercapnia). The CMRGlc was reduced by 7.7% (95% CI: -15.4 to -0.08, p = 0.045; i.e., reduction in net glucose uptake) and the oxidative glucose index (ratio of oxygen to glucose uptake) was reduced by 5.6% (95% CI: -11.2 to 0.06, p = 0.049) with a + 9 mmHg increase in PaCO2. CONCLUSION Collectively, the CMRO2 is altered by approximately 1% per mmHg change in PaCO2. Further, glucose is incompletely oxidized during hypercapnia, indicating reductions in CMRO2 are either met by compensatory increases in nonoxidative glucose metabolism or explained by a reduction in total energy production.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony R Bain
- Department of Kinesiology, Faculty of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Cody G Durrer
- Centre for Physical Activity Research, Rigshospitalet, Copenhagen, Denmark
| | - Michael M Tymko
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Human Cerebrovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Mypinder S Sekhon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Kells AM, Moir ME, Coombs GB, D'Souza AW, Klassen SA, Al-Khazraji BK, Shoemaker JK. No influence of steady-state postural changes on cerebrovascular compliance in humans. Appl Physiol Nutr Metab 2024; 49:1210-1216. [PMID: 38776557 DOI: 10.1139/apnm-2023-0447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The aim of this study was to determine the effect of posture changes on vascular compliance in intracranial (brain) versus extracranial vascular beds (forearm). Eighteen young adults (nine females) performed a supine-to-seated-to-standing protocol involving 5 min of rest in each position. Continuous blood pressure, middle cerebral artery (MCA) blood velocity, and brachial artery blood velocity were recorded at each posture. Three to five consecutive steady-state cardiac cycles at each posture were analyzed by a four-element lumped parameter modified Windkessel model to calculate vascular compliance. Mean arterial pressure (MAP) increased from supine to seated (76(9) vs. 81(12) mmHg; P = 0.006) and from supine to standing (76(9) vs. 82(13) mmHg; P = 0.034). Mean blood flow was greater in the MCA relative to the forearm (forearm: 40(5) mL·min-1, MCA: 224(17) mL·min-1; main effect P < 0.001). Conversely, vascular resistance (forearm: 3.25(0.50) mmHg-1·mL·min-1, brain: 0.36(0.04) mmHg-1·mL·min-1; main effect P < 0.001) and compliance (forearm: 0.010(0.001) mL·min-1·mmHg-1, brain: 0.005(0.001) mL·min-1·mmHg-1; main effect P = 0.001) were greater in the forearm compared to the brain. Significant main effects of posture were observed with decreasing values in upright positions for mean blood flow (P = 0.001) in both vascular beds, but not for resistance (P = 0.163) or compliance (P = 0.385). There were no significant interaction effects between vascular bed and posture for mean flow (P = 0.057), resistance (P = 0.258), or compliance (P = 0.329). This study provides evidence that under steady-state conditions, posture does not affect cerebrovascular compliance.
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Affiliation(s)
- Alicia M Kells
- School of Kinesiology, Western University, London, ON, Canada
| | - M Erin Moir
- School of Kinesiology, Western University, London, ON, Canada
| | - Geoff B Coombs
- School of Kinesiology, Western University, London, ON, Canada
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | | | - Stephen A Klassen
- School of Kinesiology, Western University, London, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Baraa K Al-Khazraji
- School of Kinesiology, Western University, London, ON, Canada
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - J Kevin Shoemaker
- School of Kinesiology, Western University, London, ON, Canada
- Department of Physiology and Pharmacology, Western University, London, ON, Canada
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Katayama T, Takahashi K, Yahara O. Atrial fibrillation, hypertension, and the cerebral vasodilatory reserve. Hypertens Res 2024; 47:2586-2588. [PMID: 38898245 DOI: 10.1038/s41440-024-01758-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/16/2024] [Accepted: 05/28/2024] [Indexed: 06/21/2024]
Abstract
Schematic representation for the cascade model of atrial fibrillation, hypertension, the cerebral vasodilatory reserve, and cognitive decline.
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Affiliation(s)
| | - Kae Takahashi
- Department of Neurology, Asahikawa City Hospital, Asahikawa, Japan
| | - Osamu Yahara
- Department of Neurology, Asahikawa City Hospital, Asahikawa, Japan
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Jeyarajan G, Ayaz A, Herold F, Zou L, Heath M. A single bout of aerobic exercise does not alter inhibitory control preparatory set cerebral hemodynamics: Evidence from the antisaccade task. Brain Cogn 2024; 179:106182. [PMID: 38824809 DOI: 10.1016/j.bandc.2024.106182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/21/2024] [Accepted: 05/21/2024] [Indexed: 06/04/2024]
Abstract
A single bout of exercise improves executive function (EF) and is a benefit - in part -attributed to an exercise-mediated increase in cerebral blood flow enhancing neural efficiency. Limited work has used an event-related protocol to examine postexercise changes in preparatory phase cerebral hemodynamics for an EF task. This is salient given the neural efficiency hypothesis' assertion that improved EF is related to decreased brain activity. Here, event-related transcranial Doppler ultrasound was used to measure pro- (saccade to target) and antisaccades (saccade mirror-symmetrical target) preparatory phase middle cerebral artery velocity (MCAv) prior to and immediately after 15-min of aerobic exercise. Antisaccades produced longer reaction times (RT) and an increased preparatory phase MCAv than prosaccades - a result attributed to greater EF neural activity for antisaccades. Antisaccades selectively produced a postexercise RT reduction (ps < 0.01); however, antisaccade preparatory phase MCAv did not vary from pre- to postexercise (p=0.53) and did not correlate with the antisaccade RT benefit (p = 0.31). Accordingly, results provide no evidence that improved neural efficiency indexed via functional hyperemia is linked to a postexercise EF behavioural benefit. Instead, results support an evolving view that an EF benefit represents the additive interplay between interdependent exercise-mediated neurophysiological changes.
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Affiliation(s)
- Gianna Jeyarajan
- School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - Azar Ayaz
- School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - Fabian Herold
- Faculty of Health Sciences Brandenburg, University of Potsdam, Potsdam, Germany
| | - Liye Zou
- Body-Brain-Mind Laboratory, School of Psychology, Shenzhen University, Shenzhen, China
| | - Matthew Heath
- School of Kinesiology, University of Western Ontario, London, ON, Canada; Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada; Canadian Centre for Activity and Aging, University of Western Ontario, London, ON, Canada.
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Cardim D, Giardina A, Ciliberti P, Battaglini D, Berardino A, Uccelli A, Czosnyka M, Roccatagliata L, Matta B, Patroniti N, Rocco PRM, Robba C. Short-term mild hyperventilation on intracranial pressure, cerebral autoregulation, and oxygenation in acute brain injury patients: a prospective observational study. J Clin Monit Comput 2024; 38:753-762. [PMID: 38310592 PMCID: PMC11297838 DOI: 10.1007/s10877-023-01121-2] [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: 10/14/2023] [Accepted: 12/18/2023] [Indexed: 02/06/2024]
Abstract
Current guidelines suggest a target of partial pressure of carbon dioxide (PaCO2) of 32-35 mmHg (mild hypocapnia) as tier 2 for the management of intracranial hypertension. However, the effects of mild hyperventilation on cerebrovascular dynamics are not completely elucidated. The aim of this study is to evaluate the changes of intracranial pressure (ICP), cerebral autoregulation (measured through pressure reactivity index, PRx), and regional cerebral oxygenation (rSO2) parameters before and after induction of mild hyperventilation. Single center, observational study including patients with acute brain injury (ABI) admitted to the intensive care unit undergoing multimodal neuromonitoring and requiring titration of PaCO2 values to mild hypocapnia as tier 2 for the management of intracranial hypertension. Twenty-five patients were included in this study (40% female), median age 64.7 years (Interquartile Range, IQR = 45.9-73.2). Median Glasgow Coma Scale was 6 (IQR = 3-11). After mild hyperventilation, PaCO2 values decreased (from 42 (39-44) to 34 (32-34) mmHg, p < 0.0001), ICP and PRx significantly decreased (from 25.4 (24.1-26.4) to 17.5 (16-21.2) mmHg, p < 0.0001, and from 0.32 (0.1-0.52) to 0.12 (-0.03-0.23), p < 0.0001). rSO2 was statistically but not clinically significantly reduced (from 60% (56-64) to 59% (54-61), p < 0.0001), but the arterial component of rSO2 (ΔO2Hbi, changes in concentration of oxygenated hemoglobin of the total rSO2) decreased from 3.83 (3-6.2) μM.cm to 1.6 (0.5-3.1) μM.cm, p = 0.0001. Mild hyperventilation can reduce ICP and improve cerebral autoregulation, with minimal clinical effects on cerebral oxygenation. However, the arterial component of rSO2 was importantly reduced. Multimodal neuromonitoring is essential when titrating PaCO2 values for ICP management.
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Affiliation(s)
- Danilo Cardim
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alberto Giardina
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Viale Benedetto XV 16, Genova, Italy
| | - Pietro Ciliberti
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Viale Benedetto XV 16, Genova, Italy
| | - Denise Battaglini
- Department of Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Andrea Berardino
- Department of Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Antonio Uccelli
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
- DINOGMI, University of Genova, Genova, Italy
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Luca Roccatagliata
- Department of Neuroradiology, IRCCS Ospedale Policlinico San Martino, Genova, Italy
- DISSAL, University of Genova, Genova, Italy
| | - Basil Matta
- Neurocritical Care Unit, Addenbrooke's Hospital, Cambridge, UK
| | - Nicolo Patroniti
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Viale Benedetto XV 16, Genova, Italy
- Department of Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Chiara Robba
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Viale Benedetto XV 16, Genova, Italy
- Department of Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genova, Italy
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Gaspary JFP, Edgar L, Lopes LFD, Rosa CB, Siluk JCM. Translational insights into the hormetic potential of carbon dioxide: from physiological mechanisms to innovative adjunct therapeutic potential for cancer. Front Physiol 2024; 15:1415037. [PMID: 39086932 PMCID: PMC11288912 DOI: 10.3389/fphys.2024.1415037] [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: 04/09/2024] [Accepted: 06/18/2024] [Indexed: 08/02/2024] Open
Abstract
Background Carbon dioxide (CO2), traditionally viewed as a mere byproduct of cellular respiration, plays a multifaceted role in human physiology beyond simple elimination through respiration. CO2 may regulate the tumor microenvironment by significantly affecting the release of oxygen (O2) to tissues through the Bohr effect and by modulating blood pH and vasodilation. Previous studies suggest hypercapnia (elevated CO2 levels) might trigger optimized cellular mechanisms with potential therapeutic benefits. The role of CO2 in cellular stress conditions within tumor environments and its impact on O2 utilization offers a new investigative area in oncology. Objectives This study aims to explore CO2's role in the tumor environment, particularly how its physiological properties and adaptive responses can influence therapeutic strategies. Methods By applying a structured translational approach using the Work Breakdown Structure method, the study divided the analysis into six interconnected work packages to comprehensively analyze the interactions between carbon dioxide and the tumor microenvironment. Methods included systematic literature reviews, data analyses, data integration for identifying critical success factors and exploring extracellular environment modulation. The research used SMART criteria for assessing innovation and the applicability of results. Results The research revealed that the human body's adaptability to hypercapnic conditions could potentially inform innovative strategies for manipulating the tumor microenvironment. This could enhance O2 utilization efficiency and manage adaptive responses to cellular stress. The study proposed that carbon dioxide's hormetic potential could induce beneficial responses in the tumor microenvironment, prompting clinical protocols for experimental validation. The research underscored the importance of pH regulation, emphasizing CO2 and carbonic acid's role in modulating metabolic and signaling pathways related to cancer. Conclusion The study underscores CO2 as vital to our physiology and suggests potential therapeutic uses within the tumor microenvironment. pH modulation and cellular oxygenation optimization via CO2 manipulation could offer innovative strategies to enhance existing cancer therapies. These findings encourage further exploration of CO2's therapeutic potential. Future research should focus on experimental validation and exploration of clinical applications, emphasizing the need for interdisciplinary and collaborative approaches to tackle current challenges in cancer treatment.
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Affiliation(s)
| | - Lee Edgar
- Elastro Crete, LLC. Research and Development Department, Veyo, UT, United States
| | - Luis Felipe Dias Lopes
- Department of Administrative Sciences, Federal University of Santa Maria, Santa Maria, Brazil
| | - Carmen Brum Rosa
- Production Engineering Department, Federal University of Santa Maria, Santa Maria, Brazil
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10
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Li H, Liu Z, Sun W, Li T, Dong X. Interpretable machine learning for the prediction of death risk in patients with acute diquat poisoning. Sci Rep 2024; 14:16101. [PMID: 38997450 PMCID: PMC11245468 DOI: 10.1038/s41598-024-67257-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 07/09/2024] [Indexed: 07/14/2024] Open
Abstract
The aim of this study was to develop and validate predictive models for assessing the risk of death in patients with acute diquat (DQ) poisoning using innovative machine learning techniques. Additionally, predictive models were evaluated through the application of SHapley Additive ExPlanations (SHAP). A total of 201 consecutive patients from the emergency departments of the First Hospital and Shengjing Hospital of China Medical University admitted for deliberate oral intake of DQ from February 2018 to August 2023 were analysed. The initial clinical data of the patients with acute DQ poisoning were collected. Machine learning methods such as logistic regression, random forest, support vector machine (SVM), and gradient boosting were applied to build the prediction models. The whole sample was split into a training set and a test set at a ratio of 8:2. The performances of these models were assessed in terms of discrimination, calibration, and clinical decision curve analysis (DCA). We also used the SHAP interpretation tool to provide an intuitive explanation of the risk of death in patients with DQ poisoning. Logistic regression, random forest, SVM, and gradient boosting models were established, and the areas under the receiver operating characteristic curves (AUCs) were 0.91, 0.98, 0.96 and 0.94, respectively. The net benefits were similar across all four models. The four machine learning models can be reliable tools for predicting death risk in patients with acute DQ poisoning. Their combination with SHAP provides explanations for individualized risk prediction, increasing the model transparency.
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Affiliation(s)
- Huiyi Li
- Department of Emergency Medicine, The First Hospital of China Medical University, Shenyang, China
| | - Zheng Liu
- Department of Emergency Medicine, The First Hospital of China Medical University, Shenyang, China
| | - Wenming Sun
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - Tiegang Li
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, China.
| | - Xuesong Dong
- Department of Emergency Medicine, The First Hospital of China Medical University, Shenyang, China.
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11
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Goossen RL, Schultz MJ, Tschernko E, Chew MS, Robba C, Paulus F, van der Heiden PLJ, Buiteman-Kruizinga LA. Effects of closed loop ventilation on ventilator settings, patient outcomes and ICU staff workloads - a systematic review. Eur J Anaesthesiol 2024; 41:438-446. [PMID: 38385449 PMCID: PMC11064903 DOI: 10.1097/eja.0000000000001972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
BACKGROUND Lung protective ventilation is considered standard of care in the intensive care unit. However, modifying the ventilator settings can be challenging and is time consuming. Closed loop modes of ventilation are increasingly attractive for use in critically ill patients. With closed loop ventilation, settings that are typically managed by the ICU professionals are under control of the ventilator's algorithms. OBJECTIVES To describe the effectiveness, safety, efficacy and workload with currently available closed loop ventilation modes. DESIGN Systematic review of randomised clinical trials. DATA SOURCES A comprehensive systematic search in PubMed, Embase and the Cochrane Central register of Controlled Trials search was performed in January 2023. ELIGIBILITY CRITERIA Randomised clinical trials that compared closed loop ventilation with conventional ventilation modes and reported on effectiveness, safety, efficacy or workload. RESULTS The search identified 51 studies that met the inclusion criteria. Closed loop ventilation, when compared with conventional ventilation, demonstrates enhanced management of crucial ventilator variables and parameters essential for lung protection across diverse patient cohorts. Adverse events were seldom reported. Several studies indicate potential improvements in patient outcomes with closed loop ventilation; however, it is worth noting that these studies might have been underpowered to conclusively demonstrate such benefits. Closed loop ventilation resulted in a reduction of various aspects associated with the workload of ICU professionals but there have been no studies that studied workload in sufficient detail. CONCLUSIONS Closed loop ventilation modes are at least as effective in choosing correct ventilator settings as ventilation performed by ICU professionals and have the potential to reduce the workload related to ventilation. Nevertheless, there is a lack of sufficient research to comprehensively assess the overall impact of these modes on patient outcomes, and on the workload of ICU staff.
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Affiliation(s)
- Robin L Goossen
- From the Department of Intensive Care, Amsterdam University Medical Centres, location 'AMC', Amsterdam, the Netherlands (RLG, MJS, FP, LAB-K), Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand (MJS), Nuffield Department of Medicine, University of Oxford, Oxford, UK (MJS), Department of Anaesthesia, General Intensive Care and Pain Management, Medical University Wien, Vienna, Austria (MJS, ET), Department of Anaesthesia and Intensive Care, Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden (MSC), Unit of Anaesthesia and Intensive Care, IRCCS Policlinico San Martino, Genoa, Italy (CR), ACHIEVE, Centre of Applied Research, Amsterdam University of Applied Sciences, Faculty of Health, Amsterdam (FP), Department of Intensive Care, Reinier de Graaf Hospital, Delft, the Netherlands (PL.J.H, LAB-K)
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12
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Persaud P, Belfry GR, Heath M. Menstrual cycle status does not impact exercise-based changes in cerebral blood flow or executive function benefits. J Sports Sci 2024; 42:1061-1071. [PMID: 39052669 DOI: 10.1080/02640414.2024.2382566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 07/13/2024] [Indexed: 07/27/2024]
Abstract
A single bout of exercise enhances executive function (EF) and may relate to an increase in cerebral blood flow (CBF). A limitation in the current literature is that biologically female participants are underrepresented given some evidence that changes in hormone levels across the menstrual cycle impact physiological and psychological variables. Here, biologically female participants completed separate single bouts of moderate intensity exercise (80% of estimated lactate threshold) during the follicular (FOL) and luteal (LUT) phases of their menstrual cycle. In addition, biologically male participants completed a same duration/intensity exercise session. Middle cerebral artery velocity (MCAv) was used to estimate CBF and pre- and postexercise EF was assessed via the antisaccade task. Results showed that resting MCAv was larger in the LUT than FOL phase; however, the exercise-mediated increase in MCAv was equivalent between menstrual cycle phases, and between female and male participants. Antisaccade reaction times reliably decreased from pre- to postexercise and frequentist and non-frequentist statistics demonstrated that the magnitude of the decrease was equivalent across FOL and LUT phases, and between female and male participants. Thus, results evince that menstrual cycle status should not serve as a basis limiting biologically female participants' inclusion in research examining exercise and EF.
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Affiliation(s)
- Priyanka Persaud
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
| | - Glen R Belfry
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
- Canadian Centre for Activity and Aging, University of Western Ontario, London, ON, Canada
| | - Matthew Heath
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
- Canadian Centre for Activity and Aging, University of Western Ontario, London, ON, Canada
- Graduate Program in Neuroscience, University of Western Ontario, London, ON, Canada
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13
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Weijs RWJ, Oudegeest-Sander MH, Hopman MTE, Thijssen DHJ, Claassen JAHR. Cerebrovascular CO 2 reactivity and dynamic cerebral autoregulation through the eighth decade of life and their implications for cognitive decline. J Cereb Blood Flow Metab 2024; 44:712-725. [PMID: 38064286 PMCID: PMC11197147 DOI: 10.1177/0271678x231219568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 11/09/2023] [Accepted: 11/16/2023] [Indexed: 04/26/2024]
Abstract
Aging is accompanied by a decrease in cerebral blood flow (CBF), especially in the presence of preclinical cognitive decline. The role of cerebrovascular physiology including regulatory mechanisms of CBF in processes underlying aging and subclinical cognitive decline is, however, not fully understood. We explored changes in cerebrovascular CO2 reactivity and dynamic cerebral autoregulation (dCA) through the eighth decade of life, and their relation with early cognitive decline. After 10.9 years, twenty-eight (age, 80.0 ± 3.5 years; 46% female) out of forty-eight healthy older adults who had participated in a previous study (age at baseline, 70 ± 4 years; 42% female), underwent repeated transcranial Doppler assessments. Linear mixed-model analyses revealed small reductions in cerebrovascular CO2 reactivity with aging (-0.37%/mmHg, P = 0.041), whereas dCA was modestly enhanced (gain: -0.009 cm/s/mmHg, P = 0.038; phase: +8.9 degrees, P = 0.004). These changes were more pronounced in participants who had developed subjective memory complaints at follow-up. Our observations confirm that dCA is not impaired in aging, despite lower cerebral perfusion and cerebrovascular reactivity. Altogether, this unique longitudinal study highlights the involvement of cerebrovascular health in preclinical cognitive decline, which is of clinical relevance in the development of dementia management strategies.
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Affiliation(s)
- Ralf WJ Weijs
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Madelijn H Oudegeest-Sander
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Geriatric Medicine, Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maria TE Hopman
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dick HJ Thijssen
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Jurgen AHR Claassen
- Department of Geriatric Medicine, Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
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14
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Sprick JD, Sabino‐Carvalho J, Mekonnen E, McGranahan M, Zanuzzi M, DaCosta D, Park J. Cerebrovascular carbon dioxide reactivity is intact in chronic kidney disease. Physiol Rep 2024; 12:e15998. [PMID: 38570312 PMCID: PMC10990926 DOI: 10.14814/phy2.15998] [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: 02/22/2024] [Revised: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024] Open
Abstract
Chronic kidney disease (CKD) is characterized by an elevated risk for cerebrovascular disease including stroke. One mechanism that may contribute to this heightened risk is an impairment in cerebrovascular carbon dioxide reactivity (CVR). We compared CVR between CKD patients stages III-IV and controls (CON) without CKD but matched for hypertension and diabetes status. CVR was measured via 5% CO2 inhalation followed by voluntary hyperventilation in 14 CKD and 11 CON participants while mean arterial pressure, end-tidal carbon dioxide, and middle cerebral artery blood velocity (MCAv) were measured continuously. CVR was quantified as the linear relationship between etCO2 and MCAv. We observed no difference in CVR between groups. Hypercapnic CVR: CKD = 1.2 ± 0.9 cm/s/mm Hg, CON = 1.3 ± 0.8 cm/s/mm Hg, hypocapnic CVR: CKD = 1.3 ± 0.9 cm/s/mm Hg, CON = 1.5 ± 0.7 cm/s/mm Hg, integrated CVR: CKD = 1.5 ± 1.1 cm/s/mm Hg, CON = 1.7 ± 0.8 cm/s/mm Hg, p ≥ 0.48. Unexpectedly, CVR was inversely related to estimated glomerular filtration rate in CKD (R2 = 0.37, p = 0.02). We report that CVR remains intact in CKD and is inversely related to eGFR. These findings suggest that other mechanisms beyond CVR contribute to the elevated stroke risk observed in CKD.
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Affiliation(s)
- Justin D. Sprick
- Department of Kinesiology, Health Promotion and RecreationUniversity of North TexasDentonTexasUSA
| | - Jeann Sabino‐Carvalho
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Elsa Mekonnen
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Melissa McGranahan
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Matias Zanuzzi
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Dana DaCosta
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Jeanie Park
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
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15
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Allison EY, Al-Khazraji BK. Cerebrovascular adaptations to habitual resistance exercise with aging. Am J Physiol Heart Circ Physiol 2024; 326:H772-H785. [PMID: 38214906 PMCID: PMC11221804 DOI: 10.1152/ajpheart.00625.2023] [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: 10/02/2023] [Revised: 01/10/2024] [Accepted: 01/10/2024] [Indexed: 01/13/2024]
Abstract
Resistance training (RT) is associated with improved metabolism, bone density, muscular strength, and lower risk of osteoporosis, sarcopenia, and cardiovascular disease. Although RT imparts many physiological benefits, cerebrovascular adaptations to chronic RT are not well defined. Participation in RT is associated with greater resting peripheral arterial diameters, improved endothelial function, and general cardiovascular health, whereas simultaneously linked to reductions in central arterial compliance. Rapid blood pressure fluctuations during resistance exercise, combined with reduced arterial compliance, could lead to cerebral microvasculature damage and subsequent cerebral hypoperfusion. Reductions in cerebral blood flow (CBF) accompany normal aging, where chronic reductions in CBF are associated with changes in brain structure and function, and increased risk of neurodegeneration. It remains unclear whether reductions in arterial compliance with RT relate to subclinical cerebrovascular pathology, or if such adaptations require interpretation in the context of RT specifically. The purpose of this narrative review is to synthesize literature pertaining to cerebrovascular adaptations to RT at different stages of the life span. This review also aims to identify gaps in the current understanding of the long-term impacts of RT on cerebral hemodynamics and provide a mechanistic rationale for these adaptations as they relate to aging, cerebral vasculature, and overall brain health.
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Affiliation(s)
- Elric Y Allison
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Baraa K Al-Khazraji
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
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16
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Panerai RB, Davies A, Clough RH, Beishon LC, Robinson TG, Minhas JS. The effect of hypercapnia on the directional sensitivity of dynamic cerebral autoregulation and the influence of age and sex. J Cereb Blood Flow Metab 2024; 44:272-283. [PMID: 37747437 PMCID: PMC10993882 DOI: 10.1177/0271678x231203475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/24/2023] [Accepted: 09/05/2023] [Indexed: 09/26/2023]
Abstract
The cerebral circulation responds differently to increases in mean arterial pressure (MAP), compared to reductions in MAP. We tested the hypothesis that this directional sensitivity is reduced by hypercapnia. Retrospective analysis of 104 healthy subjects (46 male (44%), age range 19-74 years), with five minute recordings of middle cerebral blood velocity (MCAv, transcranial Doppler), non-invasive MAP (Finometer) and end-tidal CO2 (capnography) at rest, during both poikilocapnia and hypercapnia (5% CO2 breathing in air) produced MCAv step responses allowing estimation of the classical Autoregulation Index (ARIORIG), and corresponding values for both positive (ARI+D) and negative (ARI-D) changes in MAP. Hypercapnia led to marked reductions in ARIORIG, ARI+D and ARI-D (p < 0.0001, all cases). Females had a lower value of ARIORIG compared to males (p = 0.030) at poikilocapnia (4.44 ± 1.74 vs 4.74 ± 1.48) and hypercapnia (2.44 ± 1.93 vs 3.33 ± 1.61). The strength of directional sensitivity (ARI+D-ARI-D) was not influenced by hypercapnia (p = 0.46), sex (p = 0.76) or age (p = 0.61). During poikilocapnia, ARI+D decreased with age in females (p = 0.027), but not in males. Directional sensitivity was not affected by hypercapnia, suggesting that its origins are more likely to be inherent to the mechanics of vascular smooth muscle than to myogenic pathways.
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Affiliation(s)
- Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
- NIHR Leicester Biomedical Research Centre, BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Aaron Davies
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
| | - Rebecca H Clough
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
| | - Lucy C Beishon
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
- NIHR Leicester Biomedical Research Centre, BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, UK
- NIHR Leicester Biomedical Research Centre, BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
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17
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Robba C, Battaglini D, Abbas A, Sarrió E, Cinotti R, Asehnoune K, Taccone FS, Rocco PR, Schultz MJ, Citerio G, Stevens RD, Badenes R. Clinical practice and effect of carbon dioxide on outcomes in mechanically ventilated acute brain-injured patients: a secondary analysis of the ENIO study. Intensive Care Med 2024; 50:234-246. [PMID: 38294526 PMCID: PMC10907416 DOI: 10.1007/s00134-023-07305-3] [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: 10/16/2023] [Accepted: 12/09/2023] [Indexed: 02/01/2024]
Abstract
PURPOSE The use of arterial partial pressure of carbon dioxide (PaCO2) as a target intervention to manage elevated intracranial pressure (ICP) and its effect on clinical outcomes remain unclear. We aimed to describe targets for PaCO2 in acute brain injured (ABI) patients and assess the occurrence of abnormal PaCO2 values during the first week in the intensive care unit (ICU). The secondary aim was to assess the association of PaCO2 with in-hospital mortality. METHODS We carried out a secondary analysis of a multicenter prospective observational study involving adult invasively ventilated patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracranial hemorrhage (ICH), or ischemic stroke (IS). PaCO2 was collected on day 1, 3, and 7 from ICU admission. Normocapnia was defined as PaCO2 > 35 and to 45 mmHg; mild hypocapnia as 32-35 mmHg; severe hypocapnia as 26-31 mmHg, forced hypocapnia as < 26 mmHg, and hypercapnia as > 45 mmHg. RESULTS 1476 patients (65.9% male, mean age 52 ± 18 years) were included. On ICU admission, 804 (54.5%) patients were normocapnic (incidence 1.37 episodes per person/day during ICU stay), and 125 (8.5%) and 334 (22.6%) were mild or severe hypocapnic (0.52 and 0.25 episodes/day). Forced hypocapnia and hypercapnia were used in 40 (2.7%) and 173 (11.7%) patients. PaCO2 had a U-shape relationship with in-hospital mortality with only severe hypocapnia and hypercapnia being associated with increased probability of in-hospital mortality (omnibus p value = 0.0009). Important differences were observed across different subgroups of ABI patients. CONCLUSIONS Normocapnia and mild hypocapnia are common in ABI patients and do not affect patients' outcome. Extreme derangements of PaCO2 values were significantly associated with increased in-hospital mortality.
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Affiliation(s)
- Chiara Robba
- Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
- Department of Surgical Science and Integrated Diagnostic, University of Genova, Genoa, Italy.
| | - Denise Battaglini
- Anesthesia and Intensive Care, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Abbas Abbas
- Department of Surgical Science and Integrated Diagnostic, University of Genova, Genoa, Italy
| | - Ezequiel Sarrió
- Department of Surgery, University of Valencia, Valencia, Spain
| | - Raphael Cinotti
- Department of Anaesthesia and Critical Care, CHU Nantes, Nantes Université, Hôtel Dieu, 44000, Nantes, France
- UMR 1246 SPHERE "MethodS in Patients-Centered Outcomes and HEalth Research", INSERM, IRS2 22 Boulevard Benoni Goulin, University of Nantes, University of Tours, 44200, Nantes, France
| | - Karim Asehnoune
- Department of Anaesthesia and Critical Care, CHU Nantes, Nantes Université, Hôtel Dieu, 44000, Nantes, France
| | - Fabio S Taccone
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), Brussels, Belgium
| | - Patricia R Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Av. Carlos Chagas Filho, 373, Rio de Janeiro, Brazil
| | - Marcus J Schultz
- Department of Clinical Medicine, University of Oxford Nuffield, Oxford, Oxfordshire, 105596, UK
- Department of Intensive Care, Amsterdam University Medical Centers, Location 'AMC', Amsterdam, The Netherlands
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand
| | - Giuseppe Citerio
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Department of Neurosciences, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy
| | - Robert David Stevens
- Department of Anesthesiology and Critical Care, John Hopkins University School of Medicine, 733 N Broadway, Baltimore, MD, 21205, USA
| | - Rafael Badenes
- Department of Surgery, University of Valencia, Valencia, Spain
- Department Anesthesiology and Surgical-Trauma Intensive Care, University Clinic Hospital, Valencia, Spain
- INCLIVA Biomedical Research Institute, Valencia, Spain
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Sobczyk O, Sayin ES, Poublanc J, Duffin J, Para A, Fisher JA, Mikulis DJ. The Choroid Plexus as an Alternative Locus for the Identification of the Arterial Input Function for Calculating Cerebral Perfusion Metrics Using MRI. AJNR Am J Neuroradiol 2023; 45:44-50. [PMID: 38164530 PMCID: PMC10756570 DOI: 10.3174/ajnr.a8099] [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: 09/26/2023] [Accepted: 11/02/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND AND PURPOSE MR imaging-based cerebral perfusion metrics can be obtained by tracing the passage of a bolus of contrast through the microvasculature of the brain parenchyma. Thus, the temporal signal pattern of the contrast agent is typically measured over a large artery such as the MCA to generate the arterial input function. The largest intracranial arteries in the brain may not always be suitable for selecting the arterial input function due to skull base susceptibility artifacts or reduced size from steno-occlusive disease. Therefore, a suitable alternative arterial input function window would be useful. The choroid plexus is a highly vascular tissue composed essentially of arterialized blood vessels and acellular stroma with low metabolic requirements relative to its blood flow and may be a suitable alternative to identify the arterial input function. MATERIALS AND METHODS We studied 8 healthy participants and 7 patients with gliomas who were administered a bolus of gadolinium. We selected an arterial input function from both the left and right M1 segments of the MCA and both lateral ventricles of the choroid plexus for each participant. We compared the changes in the T2* signal and the calculated resting perfusion metrics using the arterial input functions selected from the MCA and choroid plexus. RESULTS We found no systematic difference between resting perfusion metrics in GM and WM when calculated using an arterial input function from the MCA or choroid plexus in the same participant. CONCLUSIONS The choroid plexus provides an alternative location from which an arterial input function may be sampled when a suitable measure over an MCA is not available.
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Affiliation(s)
- Olivia Sobczyk
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management (O.S., J.AF.), University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Ece Su Sayin
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
- Department of Physiology (E.S.S., J.D., J.A.F.), University of Toronto, Toronto, Ontario, Canada
| | - Julien Poublanc
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
| | - James Duffin
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
- Department of Physiology (E.S.S., J.D., J.A.F.), University of Toronto, Toronto, Ontario, Canada
| | - Andrea Para
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
| | - Joseph A Fisher
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management (O.S., J.AF.), University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology (E.S.S., J.D., J.A.F.), University of Toronto, Toronto, Ontario, Canada
| | - David J Mikulis
- From the Joint Department of Medical Imaging and the Functional Neuroimaging Lab (O.S., E.S.S., J.P., J.D., A.P., J.A.F., D.J.M.), University Health Network, Toronto, Ontario, Canada
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19
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Moreira TS, Mulkey DK, Takakura AC. Update on vascular control of central chemoreceptors. Exp Physiol 2023. [PMID: 38153366 DOI: 10.1113/ep091329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/11/2023] [Indexed: 12/29/2023]
Abstract
At least four mechanisms have been proposed to elucidate how neurons in the retrotrapezoid (RTN) region sense changes in CO2 /H+ to regulate breathing (i.e., function as respiratory chemosensors). These mechanisms include: (1) intrinsic neuronal sensitivity to H+ mediated by TASK-2 and GPR4; (2) paracrine activation of RTN neurons by CO2 -responsive astrocytes (via a purinergic mechanism); (3) enhanced excitatory synaptic input or disinhibition; and (4) CO2 -induced vascular contraction. Although blood flow can influence tissue CO2 /H+ levels, there is limited understanding of how control of vascular tone in central CO2 chemosensitive regions might contribute to respiratory output. In this review, we focus on recent evidence that CO2 /H+ -induced purinergic-dependent vasoconstriction in the ventral parafacial region near RTN neurons supports respiratory chemoreception. This mechanism appears to be unique to the ventral parafacial region and opposite to other brain regions, including medullary chemosensor regions, where CO2 /H+ elicits vasodilatation. We speculate that this mechanism helps to maintain CO2 /H+ levels in the vicinity of RTN neurons, thereby maintaining the drive to breathe. Important next steps include determining whether disruption of CO2 /H+ vascular reactivity contributes to or can be targeted to improve breathing problems in disease states, such as Parkinson's disease.
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Affiliation(s)
- Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
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20
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Talbot JS, Perkins DR, Tallon CM, Dawkins TG, Douglas AJM, Beckerleg R, Crofts A, Wright ME, Davies S, Steventon JJ, Murphy K, Lord RN, Pugh CJA, Oliver JL, Lloyd RS, Ainslie PN, McManus AM, Stembridge M. Cerebral blood flow and cerebrovascular reactivity are modified by maturational stage and exercise training status during youth. Exp Physiol 2023; 108:1500-1515. [PMID: 37742137 PMCID: PMC10988468 DOI: 10.1113/ep091279] [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: 05/04/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
NEW FINDINGS What is the central question of this study? Gonadal hormones modulate cerebrovascular function while insulin-like growth factor 1 (IGF-1) facilitates exercise-mediated cerebral angiogenesis; puberty is a critical period of neurodevelopment alongside elevated gonadal hormone and IGF-1 activity: but whether exercise training across puberty enhances cerebrovascular function is unkown. What is the main finding and its importance? Cerebral blood flow is elevated in endurance trained adolescent males when compared to untrained counterparts. However, cerebrovascular reactivity to hypercapnia is faster in trained vs. untrained children, but not adolescents. Exercise-induced improvements in cerebrovascular function are attainable as early as the first decade of life. ABSTRACT Global cerebral blood flow (gCBF) and cerebrovascular reactivity to hypercapnia (CV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) are modulated by gonadal hormone activity, while insulin-like growth factor 1 facilitates exercise-mediated cerebral angiogenesis in adults. Whether critical periods of heightened hormonal and neural development during puberty represent an opportunity to further enhance gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ is currently unknown. Therefore, we used duplex ultrasound to assess gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ in n = 128 adolescents characterised as endurance-exercise trained (males: n = 30, females: n = 36) or untrained (males: n = 29, females: n = 33). Participants were further categorised as pre- (males: n = 35, females: n = 33) or post- (males: n = 24, females: n = 36) peak height velocity (PHV) to determine pubertal or 'maturity' status. Three-factor ANOVA was used to identify main and interaction effects of maturity status, biological sex and training status on gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Data are reported as group means (SD). Pre-PHV youth demonstrated elevated gCBF and slowerCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response times than post-PHV counterparts (both: P ≤ 0.001). gCBF was only elevated in post-PHV trained males when compared to untrained counterparts (634 (43) vs. 578 (46) ml min-1 ; P = 0.007). However,CV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response time was faster in pre- (72 (20) vs. 95 (29) s; P ≤ 0.001), but not post-PHV (P = 0.721) trained youth when compared to untrained counterparts. Cardiorespiratory fitness was associated with gCBF in post-PHV youth (r2 = 0.19; P ≤ 0.001) andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response time in pre-PHV youth (r2 = 0.13; P = 0.014). Higher cardiorespiratory fitness during adolescence can elevate gCBF while exercise training during childhood primes the development of cerebrovascular function, highlighting the importance of exercise training during the early stages of life in shaping the cerebrovascular phenotype.
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Affiliation(s)
- Jack S. Talbot
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Dean R. Perkins
- Department of Sport ScienceUniversity of InnsbruckInnsbruckAustria
| | - Christine M. Tallon
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Tony G. Dawkins
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Andrew J. M. Douglas
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Ryan Beckerleg
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Andrew Crofts
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Melissa E. Wright
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Saajan Davies
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Jessica J. Steventon
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Rachel N. Lord
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Christopher J. A. Pugh
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Jon L. Oliver
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
- Sports Performance Research Institute New ZealandAUT UniversityAucklandNew Zealand
| | - Rhodri S. Lloyd
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
- Sports Performance Research Institute New ZealandAUT UniversityAucklandNew Zealand
- Centre for Sport Science and Human PerformanceWaikato Institute of TechnologyWaikatoNew Zealand
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Ali M. McManus
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Mike Stembridge
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
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21
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Brassard P, Roy MA, Burma JS, Labrecque L, Smirl JD. Quantification of dynamic cerebral autoregulation: welcome to the jungle! Clin Auton Res 2023; 33:791-810. [PMID: 37758907 DOI: 10.1007/s10286-023-00986-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023]
Abstract
PURPOSE Patients with dysautonomia often experience symptoms such as dizziness, syncope, blurred vision and brain fog. Dynamic cerebral autoregulation, or the ability of the cerebrovasculature to react to transient changes in arterial blood pressure, could be associated with these symptoms. METHODS In this narrative review, we go beyond the classical view of cerebral autoregulation to discuss dynamic cerebral autoregulation, focusing on recent advances pitfalls and future directions. RESULTS Following some historical background, this narrative review provides a brief overview of the concept of cerebral autoregulation, with a focus on the quantification of dynamic cerebral autoregulation. We then discuss the main protocols and analytical approaches to assess dynamic cerebral autoregulation, including recent advances and important issues which need to be tackled. CONCLUSION The researcher or clinician new to this field needs an adequate comprehension of the toolbox they have to adequately assess, and interpret, the complex relationship between arterial blood pressure and cerebral blood flow in healthy individuals and clinical populations, including patients with autonomic disorders.
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Affiliation(s)
- 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, Québec, Canada.
| | - Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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22
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Anderson GK, Davis KA, Bhuiyan N, Rusy R, Rosenberg AJ, Rickards CA. The effect of oscillatory hemodynamics on the cardiovascular responses to simulated hemorrhage during isocapnia. J Appl Physiol (1985) 2023; 135:1312-1322. [PMID: 37881852 PMCID: PMC10911761 DOI: 10.1152/japplphysiol.00241.2023] [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: 04/18/2023] [Revised: 10/17/2023] [Accepted: 10/20/2023] [Indexed: 10/27/2023] Open
Abstract
During cerebral hypoperfusion induced by lower body negative pressure (LBNP), cerebral tissue oxygenation is protected with oscillatory arterial pressure and cerebral blood flow at low frequencies (0.1 Hz and 0.05 Hz), despite no protection of cerebral blood flow or oxygen delivery. However, hypocapnia induced by LBNP contributes to cerebral blood flow reductions, and may mask potential protective effects of hemodynamic oscillations on cerebral blood flow. We hypothesized that under isocapnic conditions, forced oscillations of arterial pressure and blood flow at 0.1 Hz and 0.05 Hz would attenuate reductions in extra- and intracranial blood flow during simulated hemorrhage using LBNP. Eleven human participants underwent three LBNP profiles: a nonoscillatory condition (0 Hz) and two oscillatory conditions (0.1 Hz and 0.05 Hz). End-tidal (et) CO2 and etO2 were clamped at baseline values using dynamic end-tidal forcing. Cerebral tissue oxygenation (ScO2), internal carotid artery (ICA) blood flow, and middle cerebral artery velocity (MCAv) were measured. With clamped etCO2, neither ICA blood flow (ANOVA P = 0.93) nor MCAv (ANOVA P = 0.36) decreased with LBNP, and these responses did not differ between the three profiles (ICA blood flow: 0 Hz: 2.2 ± 5.4%, 0.1 Hz: -0.4 ± 6.6%, 0.05 Hz: 0.2 ± 4.8%; P = 0.56; MCAv: 0 Hz: -2.3 ± 7.8%, 0.1 Hz: -1.3 ± 6.1%, 0.05 Hz: -3.1 ± 5.0%; P = 0.87). Similarly, ScO2 did not decrease with LBNP (ANOVA P = 0.21) nor differ between the three profiles (0 Hz: -2.6 ± 3.3%, 0.1 Hz: -1.6 ± 1.5%, 0.05 Hz: -0.2 ± 2.8%; P = 0.13). Contrary to our hypothesis, cerebral blood flow and tissue oxygenation were protected during LBNP with isocapnia, regardless of whether hemodynamic oscillations were induced.NEW & NOTEWORTHY We examined the role of forcing oscillations in arterial pressure and blood flow at 0.1 Hz and 0.05 Hz on extra- and intracranial blood flow and cerebral tissue oxygenation during simulated hemorrhage (using lower body negative pressure, LBNP) under isocapnic conditions. Contrary to our hypothesis, both cerebral blood flow and cerebral tissue oxygenation were completely protected during simulated hemorrhage with isocapnia, regardless of whether oscillations in arterial pressure and cerebral blood flow were induced. These findings highlight the protective effect of preventing hypocapnia on cerebral blood flow under simulated hemorrhage conditions.
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Affiliation(s)
- Garen K Anderson
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - K Austin Davis
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Nasrul Bhuiyan
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ryan Rusy
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Alexander J Rosenberg
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
- Physiology Department, Midwestern University, Downers Grove, Illinois, United States
- Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Caroline A Rickards
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
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23
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Abdali K, Chen X, Ross S, Davis S, Zhou Z, Mallet RT, Shi X. Mechanisms maintaining cerebral perfusion during systemic hypotension are impaired in elderly adults. Exp Biol Med (Maywood) 2023; 248:2464-2472. [PMID: 38057956 PMCID: PMC10903242 DOI: 10.1177/15353702231209416] [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: 08/02/2023] [Accepted: 09/11/2023] [Indexed: 12/08/2023] Open
Abstract
Postural hypotension abruptly lowers cerebral perfusion, producing unsteadiness which worsens with aging. This study addressed the hypothesis that maintenance of cerebral perfusion weakens in the elderly due to less effective cerebrovascular autoregulation and systemic cardiovascular responses to hypotension. In healthy elderly (n = 13, 68 ± 1 years) and young (n = 13, 26 ± 1 years) adults, systemic hypotension was induced by rapid deflation of bilateral thigh cuffs after 3-min suprasystolic occlusion, while heart rate (HR), mean arterial pressure (MAP), and blood flow velocity of the middle cerebral artery (VMCA) were recorded. VMCA/MAP indexed cerebrovascular conductance (CVC). Durations and rates of recovery of MAP and VMCA from their respective postdeflation nadirs were compared between the groups. Thigh-cuff deflation elicited similar hypotension and cerebral hypoperfusion in the elderly and young adults. However, the time elapsed (TΔ) from cuff deflation to the nadirs of MAP and VMCA, and the time for full recovery (TR) from nadirs to baselines were significantly prolonged in the elderly subjects. The response rates of HR (ΔHR, i.e. cardiac factor), MAP (ΔMAP, i.e. vasomotor factor), and CVC following cuff deflation were significantly slower in the elderly. Collectively, the response rates of the cardiac, vasomotor, and CVC factors largely explained TRVMCA. However, the TRVMCA/ΔMAP slope (-3.0 ± 0.9) was steeper (P = 0.046) than the TRVMCA/ΔHR slope (-1.1 ± 0.4). The TRVMCA/ΔCVC slope (-2.4 ± 0.6) was greater (P = 0.072) than the TRVMCA/ΔHR slope, but did not differ from the TRVMCA/ΔMAP slope (P = 0.52). Both cerebrovascular autoregulatory and systemic mechanisms contributed to cerebral perfusion recovery during systemic hypotension, and the vasomotor factor was predominant over the cardiac factor. Recovery from cerebral hypoperfusion was slower in the elderly adults because of the age-diminished rates of the CVC response and cardiovascular reflex regulation. Systemic vasoconstriction predominated over increased HR for restoring cerebral perfusion after abrupt onset of systemic hypotension.
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Affiliation(s)
- Kulsum Abdali
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Xiaoan Chen
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Jishou University, Jishou 416000, China
| | - Sarah Ross
- Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Sandra Davis
- Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Zhengyang Zhou
- Departments of Biostatistics & Epidemiology, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert T Mallet
- Departments of Physiology and Anatomy, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Xiangrong Shi
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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24
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Carter KJ, Ward AT, Al-Subu A, Wilson AD, Zevin EL, Serlin RC, Eldridge M, Wieben O, Schrage WG. An oral glucose tolerance test does not affect cerebral blood flow: role of NOS. Am J Physiol Regul Integr Comp Physiol 2023; 325:R759-R768. [PMID: 37842740 PMCID: PMC11178292 DOI: 10.1152/ajpregu.00169.2022] [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: 07/01/2022] [Revised: 09/11/2023] [Accepted: 10/06/2023] [Indexed: 10/17/2023]
Abstract
Animal data indicate that insulin triggers a robust nitric oxide synthase (NOS)-mediated dilation in cerebral arteries similar to the peripheral tissue vasodilation observed in healthy adults. Insulin's role in regulating cerebral blood flow (CBF) in humans remains unclear but may be important for understanding the links between insulin resistance, diminished CBF, and poor brain health outcomes. We tested the hypothesis that an oral glucose challenge (oral glucose tolerance test, OGTT), which increases systemic insulin and glucose, would acutely increase CBF in healthy adults due to NOS-mediated vasodilation, and that changes in CBF would be greater in anterior regions where NOS expression or activity may be greater. In a randomized, single-blind approach, 18 young healthy adults (24 ± 5 yr) underwent magnetic resonance imaging (MRI) with a placebo before and after an OGTT (75 g glucose), and 11 of these adults also completed an NG-monomethyl-l-arginine (l-NMMA) visit. Four-dimensional (4-D) flow MRI quantified macrovascular CBF and arterial spin labeling (ASL) quantified microvascular perfusion. Subjects completed baseline imaging with a placebo (or l-NMMA), then consumed an OGTT followed by MRI scans and blood sampling every 10-15 min for 90 min. Contrary to our hypothesis, total CBF (P = 0.17) and global perfusion (P > 0.05) did not change at any time point up to 60 min after the OGTT, and no regional changes were detected. l-NMMA did not mediate any effect of OGTT on CBF. These data suggest that insulin-glucose challenge does not acutely alter CBF in healthy adults.
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Affiliation(s)
- Katrina J Carter
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
| | - Aaron T Ward
- Deparment of Center for Health Disparities Research, University of Wisconsin, Madison, Wisconsin, United States
| | - Awni Al-Subu
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Allen D Wilson
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Erika L Zevin
- Department of Pediatrics, University School of Medicine, Indianapolis, Indiana, United States
| | - Ronald C Serlin
- Department of Educational Psychology, University of Wisconsin, Madison, Wisconsin, United States
| | - Marlowe Eldridge
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, United States
- Department of Radiology, University of Wisconsin, Madison, Wisconsin, United States
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
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25
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Freeberg KA, Craighead DH, Heinbockel TC, Rossman MJ, Jackman RA, Jankowski LR, Ludwig KR, Chonchol M, Bailey EF, Seals DR. Time-efficient, high-resistance inspiratory muscle strength training increases cerebrovascular reactivity in midlife and older adults. Am J Physiol Heart Circ Physiol 2023; 325:H1059-H1068. [PMID: 37682232 PMCID: PMC10908405 DOI: 10.1152/ajpheart.00351.2023] [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: 06/14/2023] [Revised: 08/22/2023] [Accepted: 09/06/2023] [Indexed: 09/09/2023]
Abstract
Aging is associated with increased risk for cognitive decline and dementia due in part to increases in systolic blood pressure (SBP) and cerebrovascular dysfunction. High-resistance inspiratory muscle strength training (IMST) is a time-efficient, intensive respiratory training protocol (30 resisted inspirations/day) that lowers SBP and improves peripheral vascular function in midlife/older adults with above-normal SBP. However, whether, and by what mechanisms, IMST can improve cerebrovascular function is unknown. We hypothesized that IMST would increase cerebrovascular reactivity to hypercapnia (CVR to CO2), which would coincide with changes to the plasma milieu that improve brain endothelial cell function and enhance cognitive performance (NIH Toolbox). We conducted a 6-wk double-blind, randomized, controlled clinical trial investigating high-resistance IMST [75% maximal inspiratory pressure (PImax); 6×/wk; 4 females, 5 males] vs. low-resistance sham training (15% PImax; 6×/wk; 2 females, 5 males) in midlife/older adults (age 50-79 yr) with initial above-normal SBP. Human brain endothelial cells (HBECs) were exposed to participant plasma and assessed for acetylcholine-stimulated nitric oxide (NO) production. CVR to CO2 increased after high-resistance IMST (pre: 1.38 ± 0.66 cm/s/mmHg; post: 2.31 ± 1.02 cm/s/mmHg, P = 0.020). Acetylcholine-stimulated NO production increased in HBECs exposed to plasma from after vs. before the IMST intervention [pre: 1.49 ± 0.33; post: 1.73 ± 0.35 arbitrary units (AU); P < 0.001]. Episodic memory increased modestly after the IMST intervention (pre: 95 ± 13; post: 103 ± 17 AU; P = 0.045). Cerebrovascular and cognitive function were unchanged in the sham control group. High-resistance IMST may be a promising strategy to improve cerebrovascular and cognitive function in midlife/older adults with above-normal SBP, a population at risk for future cognitive decline and dementia.NEW & NOTEWORTHY Midlife/older adults with above-normal blood pressure are at increased risk of developing cognitive decline and dementia. Our findings suggest that high-resistance inspiratory muscle strength training (IMST), a novel, time-efficient (5-10 min/day) form of physical training, may increase cerebrovascular reactivity to CO2 and episodic memory in midlife/older adults with initial above-normal blood pressure.
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Affiliation(s)
- Kaitlin A Freeberg
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Daniel H Craighead
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Thomas C Heinbockel
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Matthew J Rossman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Rachel A Jackman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Lindsey R Jankowski
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Katelyn R Ludwig
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Michel Chonchol
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - E Fiona Bailey
- Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona, United States
| | - Douglas R Seals
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
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26
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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Carr JMJR, Day TA, Ainslie PN, Hoiland RL. The jugular venous-to-arterial P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during rebreathing and end-tidal forcing: Relationship with cerebral perfusion. J Physiol 2023; 601:4251-4262. [PMID: 37635691 DOI: 10.1113/jp284449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/11/2023] [Indexed: 08/29/2023] Open
Abstract
We examined two assumptions of the modified rebreathing technique for the assessment of the ventilatory central chemoreflex (CCR) and cerebrovascular CO2 reactivity (CVR), hypothesizing: (1) that rebreathing abolishes the gradient between the partial pressures of arterial and brain tissue CO2 [measured via the surrogate jugular venousP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and arterialP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference (Pjv-a CO2 )] and (2) rebreathing eliminates the capacity of CVR to influence the Pjv-a CO2 difference, and thus affect CCR sensitivity. We also evaluated these variables during two separate dynamic end-tidal forcing (ETF) protocols (termed: ETF-1 and ETF-2), another method of assessing CCR sensitivity and CVR. Healthy participants were included in the rebreathing (n = 9), ETF-1 (n = 11) and ETF-2 (n = 10) protocols and underwent radial artery and internal jugular vein (advanced to jugular bulb) catheterization to collect blood samples. Transcranial Doppler ultrasound was used to measure middle cerebral artery blood velocity (MCAv). The Pjv-a CO2 difference was not abolished during rebreathing (6.2 ± 2.6 mmHg; P < 0.001), ETF-1 (9.3 ± 1.5 mmHg; P < 0.001) or ETF-2 (8.6 ± 1.4 mmHg; P < 0.001). The Pjv-a CO2 difference did not change during the rebreathing protocol (-0.1 ± 1.2 mmHg; P = 0.83), but was reduced during the ETF-1 (-3.9 ± 1.1 mmHg; P < 0.001) and ETF-2 (-3.4 ± 1.2 mmHg; P = 0.001) protocols. Overall, increases in MCAv were associated with reductions in the Pjv-a CO2 difference during ETF (-0.095 ± 0.089 mmHg cm-1 s-1 ; P = 0.001) but not during rebreathing (-0.028 ± 0.045 mmHg · cm-1 · s-1 ; P = 0.067). These findings suggest that, although the Pjv-a CO2 is not abolished during any chemoreflex assessment technique, hyperoxic hypercapnic rebreathing is probably more appropriate to assess CCR sensitivity independent of cerebrovascular reactivity to CO2 . KEY POINTS: Modified rebreathing is a technique used to assess the ventilatory central chemoreflex and is based on the premise that the rebreathing method eliminates the difference between arterial and brain tissueP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Therefore, rebreathing is assumed to isolate the ventilatory response to central chemoreflex stimulation from the influence of cerebral blood flow. We assessed these assumptions by measuring arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and middle cerebral artery blood velocity during modified rebreathing and compared these data against data from another test of the ventilatory central chemoreflex using hypercapnic dynamic end-tidal forcing. The difference between arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ remained present during both rebreathing and end-tidal forcing tests, whereas middle cerebral artery blood velocity was associated with theP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during end-tidal forcing but not rebreathing. These findings offer substantiating evidence that clarifies and refines the assumptions of modified rebreathing tests, enhancing interpretation of future findings.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
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Vinetti G, Micarelli A, Falla M, Randi A, Dal Cappello T, Gatterer H, Brugger H, Strapazzon G, Rauch S. Surgical masks and filtering facepiece class 2 respirators (FFP2) have no major physiological effects at rest and during moderate exercise at 3000-m altitude: a randomised controlled trial. J Travel Med 2023; 30:taad031. [PMID: 36881665 PMCID: PMC10481409 DOI: 10.1093/jtm/taad031] [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: 12/23/2022] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/09/2023]
Abstract
BACKGROUND During the COVID-19 pandemic, the use of face masks has been recommended or enforced in several situations; however, their effects on physiological parameters and cognitive performance at high altitude are unknown. METHODS Eight healthy participants (four females) rested and exercised (cycling, 1 W/kg) while wearing no mask, a surgical mask or a filtering facepiece class 2 respirator (FFP2), both in normoxia and hypobaric hypoxia corresponding to an altitude of 3000 m. Arterialised oxygen saturation (SaO2), partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), heart and respiratory rate, pulse oximetry (SpO2), cerebral oxygenation, visual analogue scales for dyspnoea and mask's discomfort were systematically investigated. Resting cognitive performance and exercising tympanic temperature were also assessed. RESULTS Mask use had a significant effect on PaCO2 (overall +1.2 ± 1.7 mmHg). There was no effect of mask use on all other investigated parameters except for dyspnoea and discomfort, which were highest with FFP2. Both masks were associated with a similar non-significant decrease in SaO2 during exercise in normoxia (-0.5 ± 0.4%) and, especially, in hypobaric hypoxia (-1.8 ± 1.5%), with similar trends for PaO2 and SpO2. CONCLUSIONS Although mask use was associated with higher rates of dyspnoea, it had no clinically relevant impact on gas exchange at 3000 m at rest and during moderate exercise, and no detectable effect on resting cognitive performance. Wearing a surgical mask or an FFP2 can be considered safe for healthy people living, working or spending their leisure time in mountains, high-altitude cities or other hypobaric environments (e.g. aircrafts) up to an altitude of 3000 m.
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Affiliation(s)
- Giovanni Vinetti
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | | | - Marika Falla
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto (TN), Italy
- Department of Neurology, General Hospital of Bolzano, Bolzano, Italy
| | - Anna Randi
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto (TN), Italy
| | - Tomas Dal Cappello
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Institute for Sports Medicine, Alpine Medicine and Health Tourism (ISAG), UMIT TIROL-Private University for Health Sciences and Health Technology, Hall in Tirol, Austria
| | - Hermann Brugger
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Simon Rauch
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Department of Anaesthesiology and Intensive Care Medicine, Hospital of Merano (SABES-ASDAA), Merano (BZ), Italy; Lehrkrankenhaus der Paracelsus Medizinischen Privatuniversität
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Dalton C, Ahn J, Jeyarajan G, Krigolson OE, Heath M. Distinct cortical haemodynamics during squat-stand and continuous aerobic exercise do not influence the magnitude of a postexercise executive function benefit. J Sports Sci 2023; 41:1459-1470. [PMID: 37884880 DOI: 10.1080/02640414.2023.2275086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/18/2023] [Indexed: 10/28/2023]
Abstract
A single bout of aerobic exercise benefits executive function (EF). A potential mechanism for this benefit is an exercise-mediated increase in cerebral blood flow (CBF) that elicits vascular endothelial shear-stress improving EF efficiency. Moderate intensity continuous aerobic exercise (MCE) asymptotically increases CBF, whereas continuous body weight squat-stand exercise (SSE) provides a large amplitude oscillatory response. Some work has proposed that an increase in CBF oscillation amplitude provides the optimal shear-stress for improving EF and brain health. We examined whether a large amplitude oscillatory CBF response associated with a single bout of SSE imparts a larger postexercise EF benefit than an MCE cycle ergometer protocol. Exercise changes in middle cerebral artery velocity (MCAv) were measured via transcranial Doppler ultrasound to estimate CBF, and pre- and postexercise EF was assessed via the antisaccade task. MCE produced a steady state increase in MCAv, whereas SSE produced a large amplitude MCAv oscillation. Both conditions produced a postexercise EF benefit that null hypothesis and equivalence tests showed to be comparable in magnitude. Accordingly, we provide a first demonstration that a single bout of SSE benefits EF; however, the condition's oscillatory CBF response does not impart a larger benefit than a time- and intensity-matched MCE protocol.
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Affiliation(s)
- Connor Dalton
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
| | - Joshua Ahn
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
| | - Gianna Jeyarajan
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
| | - Olave E Krigolson
- Centre for Biomedical Research, University of Victoria, Victoria, BC, Canada
| | - Matthew Heath
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
- Canadian Centre for Activity and Aging, University of Western Ontario, London, ON, Canada
- Graduate Program in Neuroscience, University of Western Ontario, London, ON, Canada
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Carr JMJR, Hoiland RL, Fernandes IA, Schrage WG, Ainslie PN. Recent insights into mechanisms of hypoxia-induced vasodilatation in the human brain. J Physiol 2023. [PMID: 37655827 DOI: 10.1113/jp284608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023] Open
Abstract
The cerebral vasculature manages oxygen delivery by adjusting arterial blood in-flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro- and macrovascular dilatation. This contemporary review focuses on in vivo human work - with reference to seminal preclinical work where necessary - on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a - likely non-obligatory - combination of: (1) nitric oxide synthases, (2) deoxygenation-coupled S-nitrosothiols, (3) potassium channel-related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin-related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex-, heredity-, age-, and disease-related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for Researching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Igor A Fernandes
- Department of Health and Kinesiology, Purdue University, Indiana, USA
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Hoiland RL, Robba C, Menon DK, Citerio G, Sandroni C, Sekhon MS. Clinical targeting of the cerebral oxygen cascade to improve brain oxygenation in patients with hypoxic-ischaemic brain injury after cardiac arrest. Intensive Care Med 2023; 49:1062-1078. [PMID: 37507572 PMCID: PMC10499700 DOI: 10.1007/s00134-023-07165-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023]
Abstract
The cerebral oxygen cascade includes three key stages: (a) convective oxygen delivery representing the bulk flow of oxygen to the cerebral vascular bed; (b) diffusion of oxygen from the blood into brain tissue; and (c) cellular utilisation of oxygen for aerobic metabolism. All three stages may become dysfunctional after resuscitation from cardiac arrest and contribute to hypoxic-ischaemic brain injury (HIBI). Improving convective cerebral oxygen delivery by optimising cerebral blood flow has been widely investigated as a strategy to mitigate HIBI. However, clinical trials aimed at optimising convective oxygen delivery have yielded neutral results. Advances in the understanding of HIBI pathophysiology suggest that impairments in the stages of the oxygen cascade pertaining to oxygen diffusion and cellular utilisation of oxygen should also be considered in identifying therapeutic strategies for the clinical management of HIBI patients. Culprit mechanisms for these impairments may include a widening of the diffusion barrier due to peri-vascular oedema and mitochondrial dysfunction. An integrated approach encompassing both intra-parenchymal and non-invasive neuromonitoring techniques may aid in detecting pathophysiologic changes in the oxygen cascade and enable patient-specific management aimed at reducing the severity of HIBI.
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Affiliation(s)
- Ryan L Hoiland
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
- Division of Neurosurgery, Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada.
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada.
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, BC, Canada.
| | - Chiara Robba
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - David K Menon
- Department of Medicine, University Division of Anaesthesia, University of Cambridge, Cambridge, UK
| | - Giuseppe Citerio
- School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Claudio Sandroni
- Department of Intensive Care, Emergency Medicine and Anaesthesiology, Fondazione Policlinico Universitario "Agostino Gemelli", IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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van Campen C(LMC, Rowe PC, Verheugt FWA, Visser FC. Influence of end-tidal CO 2 on cerebral blood flow during orthostatic stress in controls and adults with myalgic encephalomyelitis/chronic fatigue syndrome. Physiol Rep 2023; 11:e15639. [PMID: 37688420 PMCID: PMC10492011 DOI: 10.14814/phy2.15639] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 09/10/2023] Open
Abstract
Brain perfusion is sensitive to changes in CO2 levels (CO2 reactivity). Previously, we showed a pathological cerebral blood flow (CBF) reduction in the majority of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients during orthostatic stress. Limited data are available on the relation between CO2 and CBF changes in ME/CFS patients. Therefore, we studied this relation between ME/CFS patients and healthy controls (HC) during tilt testing. In this retrospective study, supine and end-tilt CBF, as measured by extracranial Doppler flow, were compared with PET CO2 data in female patients either with a normal heart rate and blood pressure (HR/BP) response or with postural orthostatic tachycardia syndrome (POTS), and in HC. Five hundred thirty-five female ME/CFS patients and 34 HC were included. Both in supine position and at end-tilt, there was a significant relation between CBF and PET CO2 in patients (p < 0.0001), without differences between patients with a normal HR/BP response and with POTS. The relations between the %CBF change and the PET CO2 reduction were both significant in patients and HC (p < 0.0001 and p = 0.0012, respectively). In a multiple regression analysis, the patient/HC status and PET CO2 predicted CBF. The contribution of the PET CO2 to CBF changes was limited, with low adjusted R2 values. In female ME/CFS patients, CO2 reactivity, as measured during orthostatic stress testing, is similar to that of HC and is independent of the type of hemodynamic abnormality. However, the influence of CO2 changes on CBF changes is modest in female ME/CFS patients.
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Affiliation(s)
| | - Peter C. Rowe
- Department of PaediatricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
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Singh MV, Uddin MN, Singh VB, Peterson AN, Murray KD, Zhuang Y, Tyrell A, Wang L, Tivarus ME, Zhong J, Qiu X, Schifitto G. Initiation of combined antiretroviral therapy confers suboptimal beneficial effects on neurovascular function in people with HIV. Front Neurol 2023; 14:1240300. [PMID: 37719766 PMCID: PMC10500594 DOI: 10.3389/fneur.2023.1240300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/14/2023] [Indexed: 09/19/2023] Open
Abstract
Introduction Due to advances in combined anti-retroviral treatment (cART), there is an increased burden of age-related cerebrovascular disease (CBVD), in people living with HIV (PWH). The underlying CNS injury can be assessed by measuring cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). Methods 35 treatment-naïve PWH and 53 HIV negative controls (HC) were enrolled in this study. Study participants underwent T1-weighted anatomical, pseudo-continuous arterial spin labeling, and resting-state functional MRI to obtain measures of CBF and CVR prior to starting cART treatment and at two-time points (12 weeks and 2 years) post-cART initiation. Controls were scanned at the baseline and 2-year visits. We also measured plasma levels of microparticles of endothelial and glial origin and well-known endothelial inflammation markers, ICAM-1 and VCAM-1, to assess HIV-associated endothelial inflammation and the interaction of these peripheral markers with brain neurovascular function. Results HIV infection was found to be associated with reduced CVR and increased levels of endothelial and glial microparticles (MPs) prior to initiation of cART. Further, CVR correlated negatively with peripheral MP levels in PWH. Discussion Our results suggest that while cART treatment has a beneficial effect on the neurovascular function after initiation, these benefits are suboptimal over time.
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Affiliation(s)
- Meera V. Singh
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, United States
| | - Md Nasir Uddin
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, United States
| | - Vir B. Singh
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | | | - Kyle D. Murray
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, United States
| | - Yuchuan Zhuang
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States
| | - Alicia Tyrell
- Clinical and Translational Science Institute, University of Rochester, Rochester, NY, United States
| | - Lu Wang
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States
| | - Madalina E. Tivarus
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
- Department of Neuroscience, University of Rochester, Rochester, NY, United States
| | - Jianhui Zhong
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, United States
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
- Department of Neuroscience, University of Rochester, Rochester, NY, United States
| | - Xing Qiu
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States
| | - Giovanni Schifitto
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
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Corkery AT, Miller KB, Loeper CA, Tetri LH, Pearson AG, Loggie NA, Howery AJ, Eldridge MW, Barnes JN. Association between serum prostacyclin and cerebrovascular reactivity in healthy young and older adults. Exp Physiol 2023; 108:1047-1056. [PMID: 37170828 PMCID: PMC10524213 DOI: 10.1113/ep090903] [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: 10/14/2022] [Accepted: 04/17/2023] [Indexed: 05/13/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the relationship between prostacyclin and cerebrovascular reactivity to hypercapnia before and after administration of a cyclooxygenase inhibitor, indomethacin, in healthy young and older adults? What is the main finding and importance? Serum prostacyclin was not related to cerebrovascular reactivity to hypercapnia before or after administration of indomethacin. However, in older adults, serum prostacyclin was related to the magnitude of change in cerebrovascular reactivity from before to after indomethacin administration. This suggests that older adults with higher serum prostacyclin may rely more on cyclooxygenase products to mediate cerebrovascular reactivity. ABSTRACT Platelet activation may contribute to age-related cerebrovascular dysfunction by interacting with the endothelial cells that regulate the response to vasodilatory stimuli. This study evaluated the relationship between a platelet inhibitor, prostacyclin, and cerebrovascular reactivity (CVR) in healthy young (n = 35; 25 ± 4 years; 17 women, 18 men) and older (n = 12; 62 ± 2 years; 8 women, 4 men) adults, who were not daily aspirin users, before and after cyclooxygenase inhibition. Prostacyclin was determined by levels of 6-keto-prostaglandin F1α (6-keto PGF1α) in the blood. CVR was assessed by measuring the middle cerebral artery blood velocity response to hypercapnia using transcranial Doppler ultrasound before (CON) and 90 min after cyclooxygenase inhibition with indomethacin (INDO). In young adults, there were no associations between prostacyclin and middle cerebral artery CVR during CON (r = -0.14, P = 0.415) or INDO (r = 0.27, P = 0.118). In older adults, associations between prostacyclin and middle cerebral artery CVR during CON (r = 0.53, P = 0.075) or INDO (r = -0.45, P = 0.136) did not reach the threshold for significance. We also evaluated the relationship between prostacyclin and the change in CVR between conditions (ΔCVR). We found no association between ΔCVR and prostacyclin in young adults (r = 0.27, P = 0.110); however, in older adults, those with higher baseline prostacyclin levels demonstrated significantly greater ΔCVR (r = -0.74, P = 0.005). In conclusion, older adults with higher serum prostacyclin, a platelet inhibitor, may rely more on cyclooxygenase products for cerebrovascular reactivity to hypercapnia.
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Affiliation(s)
- Adam T Corkery
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Kathleen B Miller
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Carissa A Loeper
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Laura H Tetri
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Andrew G Pearson
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Nicole A Loggie
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Anna J Howery
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
| | - Marlowe W Eldridge
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin Madison, Madison, WI, USA
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Addis A, Baggiani M, Citerio G. Intracranial Pressure Monitoring and Management in Aneurysmal Subarachnoid Hemorrhage. Neurocrit Care 2023; 39:59-69. [PMID: 37280411 PMCID: PMC10499755 DOI: 10.1007/s12028-023-01752-y] [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] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 05/12/2023] [Indexed: 06/08/2023]
Abstract
Aneurysmal subarachnoid hemorrhage is a medical condition that can lead to intracranial hypertension, negatively impacting patients' outcomes. This review article explores the underlying pathophysiology that causes increased intracranial pressure (ICP) during hospitalization. Hydrocephalus, brain swelling, and intracranial hematoma could produce an ICP rise. Although cerebrospinal fluid withdrawal via an external ventricular drain is commonly used, ICP monitoring is not always consistently practiced. Indications for ICP monitoring include neurological deterioration, hydrocephalus, brain swelling, intracranial masses, and the need for cerebrospinal fluid drainage. This review emphasizes the importance of ICP monitoring and presents findings from the Synapse-ICU study, which supports a correlation between ICP monitoring and treatment with better patient outcomes. The review also discusses various therapeutic strategies for managing increased ICP and identifies potential areas for future research.
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Affiliation(s)
- Alberto Addis
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Neurological Intensive Care Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico San Gerardo dei Tintori, Monza, Italy
| | | | - Giuseppe Citerio
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
- Neurological Intensive Care Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico San Gerardo dei Tintori, Monza, Italy.
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36
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Ivanova MV, Pappas I. Understanding recovery of language after stroke: insights from neurovascular MRI studies. FRONTIERS IN LANGUAGE SCIENCES 2023; 2:1163547. [PMID: 38162928 PMCID: PMC10757818 DOI: 10.3389/flang.2023.1163547] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Stroke causes a disruption in blood flow to the brain that can lead to profound language impairments. Understanding the mechanisms of language recovery after stroke is crucial for the prognosis and effective rehabilitation of people with aphasia. While the role of injured brain structures and disruptions in functional connectivity have been extensively explored, the relationship between neurovascular measures and language recovery in both early and later stages has not received sufficient attention in the field. Fully functioning healthy brain tissue requires oxygen and nutrients to be delivered promptly via its blood supply. Persistent decreases in blood flow after a stroke to the remaining non-lesioned tissue have been shown to contribute to poor language recovery. The goal of the current paper is to critically examine stroke studies looking at the relationship between different neurovascular measures and language deficits and mechanisms of language recovery via changes in neurovascular metrics. Measures of perfusion or cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) provide complementary approaches to understanding neurovascular mechanisms post stroke by capturing both cerebral metabolic demands and mechanical vascular properties. While CBF measures indicate the amount of blood delivered to a certain region and serve as a proxy for metabolic demands of that area, CVR indices reflect the ability of the vasculature to recruit blood flow in response to a shortage of oxygen, such as when one is holding their breath. Increases in CBF during recovery beyond the site of the lesion have been shown to promote language gains. Similarly, CVR changes, when collateral vessels are recruited to help reorganize the flow of blood in hypoperfused regions, have been related to functional recovery post stroke. In the current review, we highlight the main findings in the literature investigating neurovascular changes in stroke recovery with a particular emphasis on how language abilities can be affected by changes in CBF and CVR. We conclude by summarizing existing methodological challenges and knowledge gaps that need to be addressed in future work in this area, outlining a promising avenue of research.
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Affiliation(s)
- Maria V. Ivanova
- Department of Psychology, University of California, Berkeley, Berkeley, CA, United States
| | - Ioannis Pappas
- USC Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, United States
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van Campen C(LMC, Rowe PC, Visser FC. Comparison of a 20 degree and 70 degree tilt test in adolescent myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients. Front Pediatr 2023; 11:1169447. [PMID: 37252045 PMCID: PMC10213432 DOI: 10.3389/fped.2023.1169447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 04/17/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction During a standard 70-degree head-up tilt test, 90% of adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) develop an abnormal reduction in cerebral blood flow (CBF). A 70-degree test might not be tolerated by young ME/CFS patients because of the high incidence of syncopal spells. This study examined whether a test at 20 degrees would be sufficient to provoke important reductions in CBF in young ME/CFS patients. Methods We analyzed 83 studies of adolescent ME/CFS patients. We assessed CBF using extracranial Doppler measurements of the internal carotid and vertebral arteries supine and during the tilt. We studied 42 adolescents during a 20 degree and 41 during a 70 degree test. Results At 20 degrees, no patients developed postural orthostatic tachycardia (POTS), compared to 32% at 70 degrees (p = 0.0002). The CBF reduction during the 20 degree tilt of -27(6)% was slightly less than during the reduction during a 70 degree test [-31(7)%; p = 0.003]. Seventeen adolescents had CBF measurements at both 20 and 70 degrees. The CBF reduction in these patients with both a 20 and 70 degrees test was significantly larger at 70 degrees than at 20 degrees (p < 0.0001). Conclusions A 20 degree tilt in young ME/CFS patients resulted in a CBF reduction comparable to that in adult patients during a 70 degree test. The lower tilt angle provoked less POTS, emphasizing the importance of using the 70 degree angle for that diagnosis. Further study is needed to explore whether CBF measurements during tilt provide an improved standard for classifying orthostatic intolerance.
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Affiliation(s)
| | - Peter C. Rowe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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38
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Shariffi B, Lloyd IN, Cessac ME, Harper JL, Limberg JK. Reproducibility and diurnal variation in middle cerebral artery blood velocity in healthy humans. Exp Physiol 2023; 108:692-705. [PMID: 36951536 PMCID: PMC10148902 DOI: 10.1113/ep090873] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 03/02/2023] [Indexed: 03/24/2023]
Abstract
NEW FINDINGS What is the central question of this study? We sought to establish between-day reproducibility in estimates of middle cerebral artery blood velocity (MCAv) and cerebrovascular reactivity (CVR) in young, healthy male and female adults in tightly controlled experimental conditions. What is the main finding and its importance? Measures of MCAv assessed during morning, afternoon and evening hours are reproducible between days. There is diurnal variation in CVR, with values being highest during the evening compared with the morning. Greater diurnal variation in CVR is associated with more efficient sleep and greater nocturnal blood pressure dipping. These data enhance our understanding of modulators of MCAv and CVR. ABSTRACT Transcranial Doppler (TCD) is used to assess cerebral blood velocity (CBV) and cerebrovascular reactivity (CVR). Assessments of TCD reproducibility are limited, and few include multiple within-day measurements. We sought to establish reproducibility of CBV and CVR in healthy adults during three time periods (morning, afternoon and evening). We hypothesized that CBV and CVR measured at the same time of day are reproducible between days. We also hypothesized that CBV and CVR exhibit diurnal variation, with measurements being higher in the evening compared with morning/afternoon hours. Twelve adults [six male and six female, 27 years (95% CI, 22-31 years)] completed three measurements (morning, afternoon and evening) on two separate days in controlled conditions (e.g., meals, activity and sleep). Middle cerebral artery blood velocity (MCAv, TCD) was measured continuously at rest and during two CVR tests (end-expiratory apnoea and carbogen inhalation). Intraclass correlation coefficients for resting MCAv showed moderate to good reproducibility, which did not differ between morning, afternoon and evening (0.87, 0.56 and 0.67, respectively; P > 0.05). Intraclass correlation coefficients for peak MCAv during apnoea (0.80, 0.46 and 0.65, respectively; P > 0.05) and minute 2 of carbogen inhalation (0.81, 0.74 and 0.73, respectively; P > 0.05) were also not different from morning compared with afternoon/evening. Time of day had no effect on resting MCAv (F = 0.69, P = 0.51, ƞp 2 = 0.06) or the peak response to apnoea (F = 1.00, P = 0.39, ƞp 2 = 0.08); however, peak MCAv during carbogen breathing exhibited diurnal variation, with highest values in the evening (F = 3.41, P = 0.05, ƞp 2 = 0.24). Measures of CBV and CVR assessed via TCD during morning, afternoon and evening hours are reproducible between days. There is diurnal variation in the MCAv response to carbogen exposure, with CVR being highest during evening compared with morning hours.
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Affiliation(s)
- Brian Shariffi
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Iman N. Lloyd
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Mikala E. Cessac
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Jennifer L. Harper
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Jacqueline K. Limberg
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
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Zhu B, Li H, Xie C, Sun M, Mai C, Xie Z, Wu Z, Zhang J, Nie L. Photoacoustic Microscopic Imaging of Cerebral Vessels for Intensive Monitoring of Metabolic Acidosis. Mol Imaging Biol 2023:10.1007/s11307-023-01815-8. [DOI: 10.1007/s11307-023-01815-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 02/23/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023]
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Zhou D, Lv Y, Lin Q, Wang C, Fei S, He W. Association between rate of change in PaCO 2 and functional outcome for patients with hypercapnia after out-of-hospital cardiac arrest: Secondary analysis of a randomized clinical trial. Am J Emerg Med 2023; 65:139-145. [PMID: 36634567 DOI: 10.1016/j.ajem.2023.01.004] [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: 09/27/2022] [Revised: 12/10/2022] [Accepted: 01/02/2023] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Normocapnia is suggested for post resuscitation care. For patients with hypercapnia after cardiac arrest, the relationship between rate of change in partial pressure of carbon dioxide (PaCO2) and functional outcome was unknown. METHODS This was the secondary analysis of Resuscitation Outcomes Consortium (ROC) amiodarone, lidocaine, and placebo (ALPS) trial. Patients with at least 2 PaCO2 recorded and the first indicating hypercapnia (PaCO2 > 45 mmHg) after return of spontaneous circulation (ROSC) were included. The rate of change in PaCO2 was calculated as the ratio of the difference between the second and first PaCO2 to the time interval. The primary outcome was modified Rankin Score (mRS), dichotomized to good (mRS 0-3) and poor (mRS 4-6) outcomes at hospital discharge. The independent relationship between rate of change in PaCO2 and outcome was investigated with multivariable logistic regression model. RESULTS A total of 746 patients with hypercapnia were included for analysis, of which 264 (35.4%) patients had good functional outcome. The median rate of change in PaCO2 was 4.7 (interquartile range [IQR] 1.7-12) mmHg per hour. After adjusting for confounders, the rate of change in PaCO2 (odds ratio [OR] 0.994, confidence interval [CI] 0.985-1.004, p = 0.230) was not associated the functional outcome. However, rate of change in PaCO2 (OR 1.010, CI 1.001-1.019, p = 0.029) was independently associated with hospital mortality. CONCLUSIONS For OHCA patients with hypercapnia on admission, the rate of change in PaCO2 was not independently associated with functional outcome; however, there was a significant trend that higher decreased rate was associated with increased hospital mortality.
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Affiliation(s)
- Dawei Zhou
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
| | - Yi Lv
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Qing Lin
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Chao Wang
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shuyang Fei
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Wei He
- Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China
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Stacey BS, Hoiland RL, Caldwell HG, Howe CA, Vermeulen T, Tymko MM, Vizcardo‐Galindo GA, Bermudez D, Figueroa‐Mujíica RJ, Gasho C, Tuaillon E, Hirtz C, Lehmann S, Marchi N, Tsukamoto H, Villafuerte FC, Ainslie PN, Bailey DM. Lifelong exposure to high-altitude hypoxia in humans is associated with improved redox homeostasis and structural-functional adaptations of the neurovascular unit. J Physiol 2023; 601:1095-1120. [PMID: 36633375 PMCID: PMC10952731 DOI: 10.1113/jp283362] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023] Open
Abstract
High-altitude (HA) hypoxia may alter the structural-functional integrity of the neurovascular unit (NVU). Herein, we compared male lowlanders (n = 9) at sea level (SL) and after 14 days acclimatization to 4300 m (chronic HA) in Cerro de Pasco (CdP), Péru (HA), against sex-, age- and body mass index-matched healthy highlanders (n = 9) native to CdP (lifelong HA). Venous blood was assayed for serum proteins reflecting NVU integrity, in addition to free radicals and nitric oxide (NO). Regional cerebral blood flow (CBF) was examined in conjunction with cerebral substrate delivery, dynamic cerebral autoregulation (dCA), cerebrovascular reactivity to carbon dioxide (CVRCO2 ) and neurovascular coupling (NVC). Psychomotor tests were employed to examine cognitive function. Compared to lowlanders at SL, highlanders exhibited elevated basal plasma and red blood cell NO bioavailability, improved anterior and posterior dCA, elevated anterior CVRCO2 and preserved cerebral substrate delivery, NVC and cognition. In highlanders, S100B, neurofilament light-chain (NF-L) and T-tau were consistently lower and cognition comparable to lowlanders following chronic-HA. These findings highlight novel integrated adaptations towards regulation of the NVU in highlanders that may represent a neuroprotective phenotype underpinning successful adaptation to the lifelong stress of HA hypoxia. KEY POINTS: High-altitude (HA) hypoxia has the potential to alter the structural-functional integrity of the neurovascular unit (NVU) in humans. For the first time, we examined to what extent chronic and lifelong hypoxia impacts multimodal biomarkers reflecting NVU structure and function in lowlanders and native Andean highlanders. Despite lowlanders presenting with a reduction in systemic oxidative-nitrosative stress and maintained cerebral bioenergetics and cerebrovascular function during chronic hypoxia, there was evidence for increased axonal injury and cognitive impairment. Compared to lowlanders at sea level, highlanders exhibited elevated vascular NO bioavailability, improved dynamic regulatory capacity and cerebrovascular reactivity, comparable cerebral substrate delivery and neurovascular coupling, and maintained cognition. Unlike lowlanders following chronic HA, highlanders presented with lower concentrations of S100B, neurofilament light chain and total tau. These findings highlight novel integrated adaptations towards the regulation of the NVU in highlanders that may represent a neuroprotective phenotype underpinning successful adaptation to the lifelong stress of HA hypoxia.
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Affiliation(s)
- Benjamin S. Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Ryan L. Hoiland
- Department of Anaesthesiology, Pharmacology and Therapeutics, Vancouver General HospitalUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Cellular and Physiological Sciences, Faculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Hannah G. Caldwell
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Connor A. Howe
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Tyler Vermeulen
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Michael M. Tymko
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
- Faculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
- Department of Medicine, Faculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Gustavo A. Vizcardo‐Galindo
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Daniella Bermudez
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Rómulo J. Figueroa‐Mujíica
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Christopher Gasho
- Division of Pulmonary and Critical CareLoma Linda University School of MedicineLoma LindaCAUSA
| | - Edouard Tuaillon
- Department of Infectious DiseasesUniversity of MontpellierMontpellierFrance
| | - Christophe Hirtz
- LBPC‐PPCUniversité de Montpellier, IRMB CHU de Montpellier, INM INSERMMontpellierFrance
| | - Sylvain Lehmann
- LBPC‐PPCUniversité de Montpellier, IRMB CHU de Montpellier, INM INSERMMontpellierFrance
| | - Nicola Marchi
- Laboratory of Cerebrovascular and Glia Research, Department of Neuroscience, Institute of Functional GenomicsUniversity of MontpellierMontpellierFrance
| | - Hayato Tsukamoto
- Faculty of Sport and Health ScienceRitsumeikan UniversityKusatsuShigaJapan
| | - Francisco C. Villafuerte
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Philip N. Ainslie
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Damian M. Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
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Paré M, Obeid H, Labrecque L, Drapeau A, Brassard P, Agharazii M. Cerebral blood flow pulsatility and cerebral artery stiffness acutely decrease during hemodialysis. Physiol Rep 2023; 11:e15595. [PMID: 36808481 PMCID: PMC9937783 DOI: 10.14814/phy2.15595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 01/19/2023] [Indexed: 02/19/2023] Open
Abstract
End-stage kidney disease (ESKD) is associated with increased arterial stiffness and cognitive impairment. Cognitive decline is accelerated in ESKD patients on hemodialysis and may result from repeatedly inappropriate cerebral blood flow (CBF). The aim of this study was to examine the acute effect of hemodialysis on pulsatile components of CBF and their relation to acute changes in arterial stiffness. In eight participants (age: 63 ± 18 years, men: 5), CBF was estimated using middle cerebral artery blood velocity (MCAv) assessed with transcranial Doppler ultrasound before, during, and after a single hemodialysis session. Brachial and central blood pressure, along with estimated aortic stiffness (eAoPWV) were measured using an oscillometric device. Arterial stiffness from heart to MCA was measured as the pulse arrival time (PAT) between electrocardiogram (ECG) and transcranial Doppler ultrasound waveforms (cerebral PAT). During hemodialysis, there was a significant reduction in mean MCAv (-3.2 cm/s, p < 0.001), and systolic MCAv (-13.0 cm/s, p < 0.001). While baseline eAoPWV (9.25 ± 0.80 m/s) did not significantly change during hemodialysis, cerebral PAT increased significantly (+0.027 , p < 0.001) and was associated with reduced pulsatile components of MCAv. This study shows that hemodialysis acutely reduces stiffness of arteries perfusing the brain along with pulsatile components of blood velocity.
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Affiliation(s)
- Mathilde Paré
- CHU de Québec Research Center, L'Hôtel‐Dieu de Québec HospitalQuébec CityQuebecCanada
- Research Center of the Institute Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuebecCanada
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuebecCanada
| | - Hasan Obeid
- CHU de Québec Research Center, L'Hôtel‐Dieu de Québec HospitalQuébec CityQuebecCanada
| | - Lawrence Labrecque
- Research Center of the Institute Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuebecCanada
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuebecCanada
| | - Audrey Drapeau
- Research Center of the Institute Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuebecCanada
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuebecCanada
| | - Patrice Brassard
- Research Center of the Institute Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuebecCanada
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuebecCanada
| | - Mohsen Agharazii
- CHU de Québec Research Center, L'Hôtel‐Dieu de Québec HospitalQuébec CityQuebecCanada
- Division of Nephrology, Faculty of MedicineUniversité Laval, QuébecQuébec CityQuebecCanada
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Skinner BD, Weaver SRC, Lucas SJE, Lucas RAI. Menstrual phase influences cerebrovascular responsiveness in females but may not affect sex differences. Front Physiol 2023; 13:1035452. [PMID: 36685202 PMCID: PMC9846518 DOI: 10.3389/fphys.2022.1035452] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Background and aims: Sex differences in the rate and occurrence of cerebrovascular diseases (e.g., stroke) indicate a role for female sex hormones (i.e., oestrogen and progesterone) in cerebrovascular function and regulation. However, it remains unclear how cerebrovascular function differs between the sexes, and between distinct phases of the menstrual cycle. This study aimed to compare cerebrovascular-CO2 responsiveness in 1) females during the early follicular (EF), ovulatory (O) and mid-luteal (ML) phases of their menstrual cycle; and 2) males compared to females during phases of lower oestrogen (EF) and higher oestrogen (O). Methods: Eleven females (25 ± 5 years) complete experimental sessions in the EF (n = 11), O (n = 9) and ML (n = 11) phases of the menstrual cycle. Nine males (22 ± 3 years) completed two experimental sessions, approximately 2 weeks apart for comparison to females. Middle and posterior cerebral artery velocity (MCAv, PCAv) was measured at rest, during two stages of hypercapnia (2% and 5% CO2 inhalation) and hypocapnia (voluntary hyperventilation to an end-tidal CO2 of 30 and 24 mmHg). The linear slope of the cerebral blood velocity response to changes in end-tidal CO2 was calculated to measure cerebrovascular-CO2 responsiveness.. Results: In females, MCAv-CO2 responsiveness to hypocapnia was lower during EF (-.78 ± .45 cm/s/mmHg) when compared to the O phase (-1.17 ± .52 cm/s/mmHg; p < .05) and the ML phase (-1.30 ± .82; p < .05). MCAv-CO2 responsiveness to hypercapnia and hypo-to-hypercapnia, and PCAv-CO2 responsiveness across the CO2 range were similar between menstrual phases (p ≥ .20). MCAv-CO2 responsiveness to hypo-to hypercapnia was greater in females compared to males (3.12 ± .91 cm/s/mmHg vs. 2.31 ± .46 cm/s/mmHg; p = .03), irrespective of menstrual phase (EF or O). Conclusion: Females during O and ML phases have an enhanced vasoconstrictive capacity of the MCA compared to the EF phase. Additionally, biological sex differences can influence cerebrovascular-CO2 responsiveness, dependent on the insonated vessel.
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Affiliation(s)
- Bethany D. Skinner
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom,*Correspondence: Bethany D. Skinner,
| | - Samuel R. C. Weaver
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Rebekah A. I. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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44
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Panerai RB, Brassard P, Burma JS, Castro P, Claassen JA, van Lieshout JJ, Liu J, Lucas SJ, Minhas JS, Mitsis GD, Nogueira RC, Ogoh S, Payne SJ, Rickards CA, Robertson AD, Rodrigues GD, Smirl JD, Simpson DM. Transfer function analysis of dynamic cerebral autoregulation: A CARNet white paper 2022 update. J Cereb Blood Flow Metab 2023; 43:3-25. [PMID: 35962478 PMCID: PMC9875346 DOI: 10.1177/0271678x221119760] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response to changes in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is often described as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) can be assessed using multiple techniques, with transfer function analysis (TFA) being the most common. A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet) that is focused on CA strove to improve TFA standardization by way of introducing data acquisition, analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvement and refinement of the original recommendations, as well as for the inclusion of new guidelines to reflect recent advances in the field. This second edition of the white paper contains more robust, evidence-based recommendations, which have been expanded to address current streams of inquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods, estimating alternative dCA metrics, and incorporating dCA quantification into clinical trials. Implementation of these new and revised recommendations is important to improve the reliability and reproducibility of dCA studies, and to facilitate inter-institutional collaboration and the comparison of results between studies.
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Affiliation(s)
- Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, and Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Joel S Burma
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Pedro Castro
- Department of Neurology, Centro Hospitalar Universitário de São João, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Jurgen Ahr Claassen
- Department of Geriatric Medicine and Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Johannes J van Lieshout
- Department of Internal Medicine, Amsterdam, UMC, The Netherlands and Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, UK
| | - Jia Liu
- Institute of Advanced Computing and Digital Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen University Town, Shenzhen, China
| | - Samuel Je Lucas
- School of Sport, Exercise and Rehabilitation Sciences and Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Georgios D Mitsis
- Department of Bioengineering, McGill University, Montreal, Québec, QC, Canada
| | - Ricardo C Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Stephen J Payne
- Institute of Applied Mechanics, National Taiwan University, Taipei
| | - Caroline A Rickards
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Andrew D Robertson
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel D Rodrigues
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Jonathan D Smirl
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - David M Simpson
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
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Carr JM, Ainslie PN, MacLeod DB, Tremblay JC, Nowak-Flück D, Howe CA, Stembridge M, Patrician A, Coombs GB, Stacey BS, Bailey DM, Green DJ, Hoiland RL. Cerebral O 2 and CO 2 transport in isovolumic haemodilution: Compensation of cerebral delivery of O 2 and maintenance of cerebrovascular reactivity to CO 2. J Cereb Blood Flow Metab 2023; 43:99-114. [PMID: 36131560 PMCID: PMC9875354 DOI: 10.1177/0271678x221119442] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study investigated the influence of acute reductions in arterial O2 content (CaO2) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO2 reactivity (CVR) in 11 healthy males (age; 28 ± 7 years: body mass index; 23 ± 2 kg/m2). Radial artery and internal jugular vein catheters provided measurement of blood pressure and gases, quantification of cerebral metabolism, cerebral CO2 washout, and trans-cerebral nitrite exchange (ozone based chemiluminescence). Prior to and following haemodilution, the partial pressure of arterial CO2 (PaCO2) was elevated with dynamic end-tidal forcing while gCBF was measured with duplex ultrasound. CVR was determined as the slope of the gCBF response and PaCO2. Replacement of ∼20% of blood volume with an equal volume of 5% human serum albumin (Alburex® 5%) reduced haemoglobin (13.8 ± 0.8 vs. 11.3 ± 0.6 g/dL; P < 0.001) and CaO2 (18.9 ± 1.0 vs 15.0 ± 0.8 mL/dL P < 0.001), elevated gCBF (+18 ± 11%; P = 0.002), preserved cerebral oxygen delivery (P = 0.49), and elevated CO2 washout (+11%; P = 0.01). The net cerebral uptake of nitrite (11.6 ± 14.0 nmol/min; P = 0.027) at baseline was abolished following haemodilution (-3.6 ± 17.9 nmol/min; P = 0.54), perhaps underpinning the conservation of CVR (61.7 ± 19.0 vs. 69.0 ± 19.2 mL/min/mmHg; P = 0.23). These findings demonstrate that the cerebrovascular responses to acute anaemia in healthy humans are sufficient to support the maintenance of CVR.
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Affiliation(s)
- Jay Mjr Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - David B MacLeod
- Human Pharmacology & Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Daniela Nowak-Flück
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Alexander Patrician
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Nedlands, Western Australia
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7.,Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada
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46
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Reed EL, Worley ML, Kueck PJ, Pietrafasa LD, Schlader ZJ, Johnson BD. Cerebral vascular function following the acute consumption of caffeinated artificially- and sugar sweetened soft drinks in healthy adults. Front Hum Neurosci 2022; 16:1063273. [PMID: 36618993 PMCID: PMC9815463 DOI: 10.3389/fnhum.2022.1063273] [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: 10/06/2022] [Accepted: 11/30/2022] [Indexed: 12/24/2022] Open
Abstract
Chronic consumption of sugar- and artificially-sweetened beverages (SSB and ASB) are associated with an increased risk of stroke but it is unclear how acute consumption influences cerebral vascular function. Purpose: We hypothesized that: (1) acute consumption of SSB and ASB would augment dynamic cerebral autoregulation (dCA) and attenuate cerebral vascular reactivity to hypercapnia (CVRCO2) compared to water; and (2) dCA and CVRCO2 would be attenuated with SSB compared to ASB and water. Methods: Twelve healthy adults (age: 23 ± 2 years, four females) completed three randomized trials where they drank 500 ml of water, SSB (Mountain Dew®), or ASB (Diet Mountain Dew®). We measured mean arterial pressure (MAP), middle and posterior cerebral artery blood velocities (MCAv and PCAv), and end-tidal CO2 tension (PETCO2). Cerebral vascular conductance was calculated as cerebral artery blood velocity/MAP (MCAc and PCAc). Twenty min after consumption, participants completed a 5 min baseline, and in a counterbalanced order, a CVRCO2 test (3%, 5%, and 7% CO2 in 3 min stages) and a dCA test (squat-stand tests at 0.10 Hz and 0.05 Hz for 5 min each) separated by 10 min. CVRCO2 was calculated as the slope of the linear regression lines of MCAv and PCAv vs. PETCO2. dCA was assessed in the MCA using transfer function analysis. Coherence, gain, and phase were determined in the low frequency (LF; 0.07-0.2 Hz) and very low frequency (VLF; 0.02-0.07 Hz). Results: MCAv and MCAc were lower after SSB (54.11 ± 12.28 cm/s, 0.58 ± 0.15 cm/s/mmHg) and ASB (51.07 ± 9.35 cm/s, 0.52 ± 1.0 cm/s/mmHg) vs. water (62.73 ± 12.96 cm/s, 0.67 ± 0.11 cm/s/mmHg; all P < 0.035), respectively. PCAc was also lower with the ASB compared to water (P = 0.007). MCA CVRCO2 was lower following ASB (1.55 ± 0.38 cm/s/mmHg) vs. water (2.00 ± 0.57 cm/s/mmHg; P = 0.011) but not after SSB (1.90 ± 0.67 cm/s/mmHg; P = 0.593). PCA CVRCO2 did not differ between beverages (P > 0.853). There were no differences between beverages for coherence (P ≥ 0.295), gain (P ≥ 0.058), or phase (P ≥ 0.084) for either frequency. Discussion: Acute consumption of caffeinated SSB and ASB resulted in lower intracranial artery blood velocity and conductance but had a minimal effect on cerebral vascular function as only MCA CVRCO2 was altered with the ASB compared to water.
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Affiliation(s)
- Emma L. Reed
- Human Integrative Physiology Lab, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, United States
| | - Morgan L. Worley
- Human Integrative Physiology Lab, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, United States
| | - Paul J. Kueck
- Human Integrative Physiology Lab, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, United States
| | - Leonard D. Pietrafasa
- Human Integrative Physiology Lab, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, United States
| | - Zachary J. Schlader
- H.H. Morris Human Performance Laboratories, Department of Kinesiology, Indiana University, Bloomington, IN, United States
| | - Blair D. Johnson
- Human Integrative Physiology Lab, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, United States,H.H. Morris Human Performance Laboratories, Department of Kinesiology, Indiana University, Bloomington, IN, United States,*Correspondence: Blair D. Johnson
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47
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Carr JMJR, Howe CA, Gibbons TD, Tymko MM, Steele AR, Vizcardo-Galindo GA, Tremblay JC, Ainslie PN. Cerebral endothelium-dependent function and reactivity to hypercapnia: the role of α 1-adrenoreceptors. J Appl Physiol (1985) 2022; 133:1356-1367. [PMID: 36326471 DOI: 10.1152/japplphysiol.00400.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
We assessed hypercapnic cerebrovascular reactivity (CVR) and endothelium-dependent function [cerebral shear-mediated dilation (cSMD)] in the internal carotid artery (ICA) with and without systemic α1-adrenoreceptor blockade via Prazosin. We hypothesized that CVR would be reduced, whereas cSMD would remain unchanged, after Prazosin administration when compared with placebo. In 15 healthy adults (3 female, 26 ± 4 years), we conducted ICA duplex ultrasound during CVR [target +10 mmHg partial pressure of end-tidal carbon dioxide ([Formula: see text]) above baseline, 5 min] and cSMD (+9 mmHg [Formula: see text] above baseline, 30 s) using dynamic end-tidal forcing with and without α1-adrenergic blockade (Prazosin; 0.05 mg/kg) in a placebo-controlled, double-blind, and randomized design. The CVR in the ICA was not different between placebo and Prazosin (P = 0.578). During CVR, the reactivities of mean arterial pressure and cerebrovascular conductance to hypercapnia were also not different between conditions (P = 0.921 and P = 0.664, respectively). During Prazosin, cSMD was lower (1.1 ± 2.0% vs 3.8 ± 3.0%; P = 0.032); however, these data should be interpreted with caution due to the elevated baseline diameter (+1.3 ± 3.6%; condition: P = 0.0498) and lower shear rate (-14.5 ± 23.0%; condition: P < 0.001). Therefore, lower cSMD post α1-adrenoreceptor blockade might not indicate a reduction in cerebral endothelial function per se, but rather, that α1-adrenoreceptors contribute to resting cerebral vascular restraint at the level of the ICA.NEW & NOTEWORTHY We assessed steady-state hypercapnic cerebrovascular reactivity and cerebral endothelium-dependent function, with and without α1-adrenergic blockade (Prazosin), in a placebo-controlled, double-blind, and randomized study, to assess the contribution of α1-adrenergic receptors to cerebrovascular CO2 regulation. After administration of Prazosin, cerebrovascular reactivity to CO2 was not different compared with placebo despite lower blood flow, whereas cerebral endothelium-dependent function was reduced, likely due to elevated baseline internal carotid arterial diameter. These findings suggest that α1-adrenoreceptor activity does not influence cerebral blood flow regulation to CO2 and cerebral endothelial function.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada.,Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.,Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew R Steele
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Gustavo A Vizcardo-Galindo
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
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Su R, Zhou J, Zhu N, Chen X, Zhou JX, Li HL. Efficacy and safety of remifentanil dose titration to correct the spontaneous hyperventilation in aneurysmal subarachnoid haemorrhage: protocol and statistical analysis for a prospective physiological study. BMJ Open 2022; 12:e064064. [PMID: 36351728 PMCID: PMC9664281 DOI: 10.1136/bmjopen-2022-064064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION Spontaneous hyperventilation (SHV) is common in aneurysmal subarachnoid haemorrhage (aSAH). The reduction in arterial partial pressure of carbon dioxide (PaCO2) may change the brain physiology, such as haemodynamics, oxygenation, metabolism and may lead to secondary brain injury. However, how to correct SHV safely and effectively in patients with aSAH has not been well investigated. The aim of this study is to investigate the efficacy and safety of remifentanil dose titration to correct hyperventilation in aSAH, as well as the effect of changes in PaCO2 on cerebral blood flow (CBF). METHODS AND ANALYSIS This study is a prospective, single-centre, physiological study in patients with aSAH. The patients who were mechanically ventilated and who meet with SHV (tachypnoea combined with PaCO2 <35 mm Hg and pH >7.45) will be enrolled. The remifentanil will be titrated to correct the SHV. The predetermined initial dose of remifentanil is 0.02 μg/kg/min and will be maintained for 30 min, and PaCO2 and CBF will be measured. After that, the dose of remifentanil will be sequentially increased to 0.04, 0.06, and 0.08 μg/kg/min, and the measurements for PaCO2 and CBF will be repeated 30 min after each dose adjustment and will be compared with their baseline values. ETHICS AND DISSEMINATION This study has been approved by the Institutional Review Board of Beijing Tiantan Hospital, Capital Medical University (KY 2021-006-02) and has been registered at ClinicalTrials.gov. The results of this study will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER NCT04940273.
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Affiliation(s)
- Rui Su
- Capital Medical University, Department of Critical Care Medicine, Beijing Tiantan Hospital, Beijing, Beijing, China
| | - Jianfang Zhou
- Capital Medical University, Department of Critical Care Medicine, Beijing Tiantan Hospital, Beijing, Beijing, China
| | - Ning Zhu
- Capital Medical University, Department of Critical Care Medicine, Beijing Tiantan Hospital, Beijing, Beijing, China
| | - Xiaolin Chen
- Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing, Beijing, China
| | - Jian-Xin Zhou
- Capital Medical University, Department of Critical Care Medicine, Beijing Tiantan Hospital, Beijing, Beijing, China
- Capital Medical University, Department of Critical Care Medicine, Beijing Shijitan Hospital, Beijing, Beijing, China
| | - Hong-Liang Li
- Capital Medical University, Department of Critical Care Medicine, Beijing Tiantan Hospital, Beijing, Beijing, China
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49
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Chilakala SK, Parfenova H, Pourcyrous M. The effects of sodium bicarbonate infusion on cerebrovascular function in newborn pigs. Pediatr Res 2022; 92:729-736. [PMID: 34862458 PMCID: PMC9163205 DOI: 10.1038/s41390-021-01876-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/11/2021] [Accepted: 11/13/2021] [Indexed: 11/09/2022]
Abstract
BACKGROUND Sodium bicarbonate (NaHCO3) is no longer recommended by the Neonatal Resuscitation Program (NRP), but is still being used by some neonatologists. The effects of NaHCO3 on cerebral hemodynamics are unclear. Therefore, we investigated the effects of NaHCO3 on cerebral blood flow (CBF) and cerebrovascular function using a newborn piglet model. METHODS Newborn pigs were anesthetized, intubated, and ventilated. Cranial windows were implanted to evaluate changes in pial arteriolar diameters (PADs) as a surrogate for CBF during a 4-h intravenous infusion of 3% NaHCO3. Cerebrovascular reactivity to vasodilators and vasoconstrictors was investigated during vehicle control and during NaHCO3 infusion. RESULTS NaHCO3 infusion caused significant and progressive pial arteriolar vasoconstrictions. During NaHCO3 infusion, cerebrovascular reactivity was preserved. Adding vasodilators decreased cerebral vasoconstriction, while adding vasoconstrictors exaggerated cerebral vasoconstriction. CONCLUSIONS Intravenous infusion of NaHCO3 over 4 h caused progressive vasoconstriction of pial arterioles. Cerebrovascular function evaluated by the responses of pial arterioles to physiologically relevant vasoconstrictors and vasodilators was preserved during NaHCO3 infusion. A notable additional reduction of PADs was observed during NaHCO3 infusion in the presence of vasoconstrictors. Extrapolating our findings to human neonates should alarm the clinicians that using NaHCO3 in neonates may cause cerebral hypoperfusion. IMPACT Cerebral vasoconstriction occurs during slow infusion of 3% diluted NaHCO3. Cerebral vasoconstriction is exaggerated when another vasoconstrictor is added during NaHCO3 infusion. Cerebrovascular function is preserved during NaHCO3 infusion. Clinicians should be aware of the risk of cerebral hypoperfusion with NaHCO3 infusion in vulnerable neonates.
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Affiliation(s)
- Sandeep K Chilakala
- Department of Pediatrics, University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Massroor Pourcyrous
- Department of Pediatrics, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA. .,Department of Physiology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA. .,Department of Obstetrics/Gynecology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA.
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50
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Hadjihambi A, Cudalbu C, Pierzchala K, Simicic D, Donnelly C, Konstantinou C, Davies N, Habtesion A, Gourine AV, Jalan R, Hosford PS. Abnormal brain oxygen homeostasis in an animal model of liver disease. JHEP Rep 2022; 4:100509. [PMID: 35865351 PMCID: PMC9293761 DOI: 10.1016/j.jhepr.2022.100509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/23/2022] [Accepted: 05/10/2022] [Indexed: 01/15/2023] Open
Abstract
Background & Aims Increased plasma ammonia concentration and consequent disruption of brain energy metabolism could underpin the pathogenesis of hepatic encephalopathy (HE). Brain energy homeostasis relies on effective maintenance of brain oxygenation, and dysregulation impairs neuronal function leading to cognitive impairment. We hypothesised that HE is associated with reduced brain oxygenation and we explored the potential role of ammonia as an underlying pathophysiological factor. Methods In a rat model of chronic liver disease with minimal HE (mHE; bile duct ligation [BDL]), brain tissue oxygen measurement, and proton magnetic resonance spectroscopy were used to investigate how hyperammonaemia impacts oxygenation and metabolic substrate availability in the central nervous system. Ornithine phenylacetate (OP, OCR-002; Ocera Therapeutics, CA, USA) was used as an experimental treatment to reduce plasma ammonia concentration. Results In BDL animals, glucose, lactate, and tissue oxygen concentration in the cerebral cortex were significantly lower than those in sham-operated controls. OP treatment corrected the hyperammonaemia and restored brain tissue oxygen. Although BDL animals were hypotensive, cortical tissue oxygen concentration was significantly improved by treatments that increased arterial blood pressure. Cerebrovascular reactivity to exogenously applied CO2 was found to be normal in BDL animals. Conclusions These data suggest that hyperammonaemia significantly decreases cortical oxygenation, potentially compromising brain energy metabolism. These findings have potential clinical implications for the treatment of patients with mHE. Lay summary Brain dysfunction is a serious complication of cirrhosis and affects approximately 30% of these patients; however, its treatment continues to be an unmet clinical need. This study shows that oxygen concentration in the brain of an animal model of cirrhosis is markedly reduced. Low arterial blood pressure and increased ammonia (a neurotoxin that accumulates in patients with liver failure) are shown to be the main underlying causes. Experimental correction of these abnormalities restored oxygen concentration in the brain, suggesting potential therapeutic avenues to explore.
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Key Words
- 1H-MRS, proton magnetic resonance spectroscopy
- AIT, Animal Imaging and Technology
- ALT, alanine transaminase
- ATZ, acetazolamide
- Ala, alanine
- Asc, ascorbate
- Asp, aspartate
- BDL, bile duct ligation
- BOLD, blood oxygen level dependent
- BP, blood pressure
- CBF, cerebral blood flow
- CIBM, Center for Biomedical Imaging
- CLD, chronic liver disease
- CMRO2, cerebral metabolic rate of oxygen
- CNS, central nervous system
- Chronic liver disease
- Cr, creatine
- EPFL, Ecole Polytechnique Fédérale de Lausanne
- GABA, γ-aminobutyric acid
- GPC, glycerophosphocholine
- GSH, glutathione
- Glc, glucose
- Gln, glutamine
- Glu, glutamate
- HE, hepatic encephalopathy
- Hyperammonaemia
- Ins, myo-inositol
- Lac, lactate
- MAP, mean arterial pressure
- NAA, N acetylaspartate
- NO, nitric oxide
- OP, ornithine phenylacetate
- Ornithine phenylacetate
- Oxygen
- PCho, phosphocholine
- PCr, phosphocreatine
- PE, phenylephrine
- Phenylephrine
- SPECIAL, spin echo full intensity acquired localised
- TE, echo time
- Tau, taurine
- VOI, volume of interest
- [18F]-FDG PET, [18F]-fluorodeoxyglucose positron emission tomography
- eNOS, endothelial nitric oxide synthase
- fMRI, functional magnetic resonance imaging
- hepatic encephalopathy
- mHE, minimal HE
- pCO2, partial pressure of carbon dioxide
- pO2, partial pressure of oxygen
- tCho, total choline
- tCr, total creatine
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Affiliation(s)
- Anna Hadjihambi
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free Hospital, Rowland Hill Street, London, UK
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
- The Roger Williams Institute of Hepatology London, Foundation for Liver Research, London, UK
- Faculty of Life Sciences and Medicine, King’s College London, London, UK
| | - Cristina Cudalbu
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Katarzyna Pierzchala
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Dunja Simicic
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Chris Donnelly
- Institute of Sports Science and Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Christos Konstantinou
- The Roger Williams Institute of Hepatology London, Foundation for Liver Research, London, UK
- Faculty of Life Sciences and Medicine, King’s College London, London, UK
| | - Nathan Davies
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free Hospital, Rowland Hill Street, London, UK
| | - Abeba Habtesion
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free Hospital, Rowland Hill Street, London, UK
| | - Alexander V. Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Rajiv Jalan
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free Hospital, Rowland Hill Street, London, UK
- European Foundation for the Study of Chronic Liver Failure
| | - Patrick S. Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, UK
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