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Somani YB, Boidin M, Peggen MAG, Wanders I, Proctor DN, Low DA, Jones H, Lip GYH, Thijssen DHJ. Single and 7-day handgrip and squat exercise prevents endothelial ischemia-reperfusion injury in individuals with cardiovascular disease risk factors. Am J Physiol Regul Integr Comp Physiol 2024; 326:R79-R87. [PMID: 37899755 DOI: 10.1152/ajpregu.00168.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 10/31/2023]
Abstract
Whole body exercise provides protection against endothelial ischemia-reperfusion (IR) injury. In this crossover study, we examined the effects of 1) single bout of local exercise (handgrip, squats) on endothelial responses to IR, and 2) if 7 days of daily local exercise bolsters these effects in individuals with cardiovascular disease (CVD) risk factors. Fifteen participants (9 women, 58 ± 5 yr, ≥2 CVD risk factors) attended the laboratory for six visits. Subsequent to familiarization (visit 1), during visit 2 (control) brachial artery flow-mediated dilation (FMD) was measured before and after IR (15-min upper-arm ischemia, 15-min reperfusion). One week later, participants were randomized to 4 × 5-min unilateral handgrip (50% maximal voluntary contraction, 25 rpm) or squat exercises (15 rpm), followed by IR plus FMD measurements. Subsequently, home-based exercise was performed (6 days), followed by another visit to the laboratory for the IR protocol plus FMD measurements (18-24 h after the last exercise bout). After a 2-wk washout period, procedures were repeated with the alternative exercise mode. For a single exercise bout, we found a significant IR injury × exercise mode interaction (P < 0.01) but no main effect of injury (P = 0.08) or condition (P = 0.61). A lower post-IR FMD was evident after control (pre-IR: 4.3 ± 2.1% to post-IR: 2.9 ± 1.9%, P < 0.01) but not after handgrip (pre-IR: 3.8 ± 1.6% to post-IR: 3.4 ± 1.5%, P = 0.31) or squats (pre-IR: 3.9 ± 1.8% to post-IR: 4.0 ± 1.9%, P = 0.74). After 7 days of daily exercise, we found no change in FMD post-IR following handgrip (pre-IR: 4.3 ± 1.9% to post-IR: 4.7 ± 3.2%) or squats (pre-IR: 3.7 ± 2.1% to post-IR: 4.7 ± 3.0%, P > 0.05). Single bouts of dynamic, local exercise (handgrip, squats) provide remote protection against endothelial IR-induced injury in individuals with CVD risk factors, with 1-wk daily, home-based exercise preserving these effects for up to 24 h following the last exercise bout.NEW & NOTEWORTHY We show that single bouts of dynamic handgrip and squat exercise provide remote protection against endothelial ischemia-reperfusion (IR)-induced injury in individuals with cardiovascular disease (CVD) risk factors, with 1-wk daily, home-based exercise preserving these effects for up to 24 h following the last exercise bout.
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Affiliation(s)
- Yasina B Somani
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- Department of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
- Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool, United Kingdom
| | - Maxime Boidin
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- Department of Sport and Exercise Sciences, Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
- Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool, United Kingdom
| | - Mandy A G Peggen
- Department of Medical Biosciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Iris Wanders
- Department of Medical Biosciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - David N Proctor
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Gregory Y H Lip
- Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool, United Kingdom
- Department of Clinical Medicine, Danish Center for Clinical Health Services, Aalborg University, Aalborg, Denmark
| | - Dick H J Thijssen
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- Department of Medical Biosciences, Radboud University Medical Centre, Nijmegen, The Netherlands
- Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool, United Kingdom
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Westbrooks J, Low DA, Brownlee TE. Determining the definition and components of successful soccer referee performance. J Sports Sci 2023; 41:2187-2192. [PMID: 38389389 DOI: 10.1080/02640414.2024.2317641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 02/05/2024] [Indexed: 02/24/2024]
Abstract
There has been little work examining the intricacies of what makes a soccer referee successful. The aim of this study was to determine what the definition of a successful referee performance is and what are the characteristics of a successful referee from a broad range of stakeholders in Major League Soccer (MLS) and the Professional Referees Organisation (PRO). The study used Delphi methodology to ask 6 MLS General Managers, 2 MLS Coaches,1 MLS League Officer, 4 PRO Referees and 10 PRO Assistant Referees, 8 PRO Staff and 5 PRO Assessors, and 2 PRO2 Referees two questions: 1. Their definition of a successful referee performance. 2. Their opinion on the characteristics of a successful referee. The result was a 7-point definition of a successful referee performance and 26 characteristics of a successful referee. There were ten characteristics that overlapped with previous work examining successful referees. This study was able to develop a definition of a successful referee performance and determine the characteristics of a successful referee.
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Affiliation(s)
- John Westbrooks
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
- Sports Performance, Professional Referee Organization, New York, USA
| | - David A Low
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Thomas E Brownlee
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
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Jensen SJ, Ruhe ZC, Williams AF, Nhan DQ, Garza-Sánchez F, Low DA, Hayes CS. Paradoxical Activation of a Type VI Secretion System Phospholipase Effector by Its Cognate Immunity Protein. J Bacteriol 2023; 205:e0011323. [PMID: 37212679 PMCID: PMC10294671 DOI: 10.1128/jb.00113-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/03/2023] [Indexed: 05/23/2023] Open
Abstract
Type VI secretion systems (T6SSs) deliver cytotoxic effector proteins into target bacteria and eukaryotic host cells. Antibacterial effectors are invariably encoded with cognate immunity proteins that protect the producing cell from self-intoxication. Here, we identify transposon insertions that disrupt the tli immunity gene of Enterobacter cloacae and induce autopermeabilization through unopposed activity of the Tle phospholipase effector. This hyperpermeability phenotype is T6SS dependent, indicating that the mutants are intoxicated by Tle delivered from neighboring sibling cells rather than by internally produced phospholipase. Unexpectedly, an in-frame deletion of tli does not induce hyperpermeability because Δtli null mutants fail to deploy active Tle. Instead, the most striking phenotypes are associated with disruption of the tli lipoprotein signal sequence, which prevents immunity protein localization to the periplasm. Immunoblotting reveals that most hyperpermeable mutants still produce Tli, presumably from alternative translation initiation codons downstream of the signal sequence. These observations suggest that cytosolic Tli is required for the activation and/or export of Tle. We show that Tle growth inhibition activity remains Tli dependent when phospholipase delivery into target bacteria is ensured through fusion to the VgrG β-spike protein. Together, these findings indicate that Tli has distinct functions, depending on its subcellular localization. Periplasmic Tli acts as a canonical immunity factor to neutralize incoming effector proteins, while a cytosolic pool of Tli is required to activate the phospholipase domain of Tle prior to T6SS-dependent export. IMPORTANCE Gram-negative bacteria use type VI secretion systems deliver toxic effector proteins directly into neighboring competitors. Secreting cells also produce specific immunity proteins that neutralize effector activities to prevent autointoxication. Here, we show the Tli immunity protein of Enterobacter cloacae has two distinct functions, depending on its subcellular localization. Periplasmic Tli acts as a canonical immunity factor to block Tle lipase effector activity, while cytoplasmic Tli is required to activate the lipase prior to export. These results indicate Tle interacts transiently with its cognate immunity protein to promote effector protein folding and/or packaging into the secretion apparatus.
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Affiliation(s)
- Steven J. Jensen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Zachary C. Ruhe
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - August F. Williams
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Dinh Q. Nhan
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Fernando Garza-Sánchez
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - David A. Low
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Christopher S. Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, California, USA
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Jensen SJ, Ruhe ZC, Williams AF, Nhan DQ, Garza-Sánchez F, Low DA, Hayes CS. Paradoxical activation of a type VI secretion system (T6SS) phospholipase effector by its cognate immunity protein. bioRxiv 2023:2023.03.28.534661. [PMID: 37034769 PMCID: PMC10081291 DOI: 10.1101/2023.03.28.534661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Type VI secretion systems (T6SS) deliver cytotoxic effector proteins into target bacteria and eukaryotic host cells. Antibacterial effectors are invariably encoded with cognate immunity proteins that protect the producing cell from self-intoxication. Here, we identify transposon insertions that disrupt the tli immunity gene of Enterobacter cloacae and induce auto-permeabilization through unopposed activity of the Tle phospholipase effector. This hyper-permeability phenotype is T6SS-dependent, indicating that the mutants are intoxicated by Tle delivered from neighboring sibling cells rather than by internally produced phospholipase. Unexpectedly, an in-frame deletion of tli does not induce hyper-permeability because Δ tli null mutants fail to deploy active Tle. Instead, the most striking phenotypes are associated with disruption of the tli lipoprotein signal sequence, which prevents immunity protein localization to the periplasm. Immunoblotting reveals that most hyper-permeable mutants still produce Tli, presumably from alternative translation initiation codons downstream of the signal sequence. These observations suggest that cytosolic Tli is required for the activation and/or export of Tle. We show that Tle growth inhibition activity remains Tli-dependent when phospholipase delivery into target bacteria is ensured through fusion to the VgrG β-spike protein. Together, these findings indicate that Tli has distinct functions depending on its subcellular localization. Periplasmic Tli acts as a canonical immunity factor to neutralize incoming effector proteins, while a cytosolic pool of Tli is required to activate the phospholipase domain of Tle prior to T6SS-dependent export.
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Heithoff DM, Mahan SP, Barnes V L, Leyn SA, George CX, Zlamal JE, Limwongyut J, Bazan GC, Fried JC, Fitzgibbons LN, House JK, Samuel CE, Osterman AL, Low DA, Mahan MJ. A broad-spectrum synthetic antibiotic that does not evoke bacterial resistance. EBioMedicine 2023; 89:104461. [PMID: 36801104 PMCID: PMC10025758 DOI: 10.1016/j.ebiom.2023.104461] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 02/17/2023] Open
Abstract
BACKGROUND Antimicrobial resistance (AMR) poses a critical threat to public health and disproportionately affects the health and well-being of persons in low-income and middle-income countries. Our aim was to identify synthetic antimicrobials termed conjugated oligoelectrolytes (COEs) that effectively treated AMR infections and whose structures could be readily modified to address current and anticipated patient needs. METHODS Fifteen chemical variants were synthesized that contain specific alterations to the COE modular structure, and each variant was evaluated for broad-spectrum antibacterial activity and for in vitro cytotoxicity in cultured mammalian cells. Antibiotic efficacy was analyzed in murine models of sepsis; in vivo toxicity was evaluated via a blinded study of mouse clinical signs as an outcome of drug treatment. FINDINGS We identified a compound, COE2-2hexyl, that displayed broad-spectrum antibacterial activity. This compound cured mice infected with clinical bacterial isolates derived from patients with refractory bacteremia and did not evoke bacterial resistance. COE2-2hexyl has specific effects on multiple membrane-associated functions (e.g., septation, motility, ATP synthesis, respiration, membrane permeability to small molecules) that may act together to negate bacterial cell viability and the evolution of drug-resistance. Disruption of these bacterial properties may occur through alteration of critical protein-protein or protein-lipid membrane interfaces-a mechanism of action distinct from many membrane disrupting antimicrobials or detergents that destabilize membranes to induce bacterial cell lysis. INTERPRETATION The ease of molecular design, synthesis and modular nature of COEs offer many advantages over conventional antimicrobials, making synthesis simple, scalable and affordable. These COE features enable the construction of a spectrum of compounds with the potential for development as a new versatile therapy for an imminent global health crisis. FUNDING U.S. Army Research Office, National Institute of Allergy and Infectious Diseases, and National Heart, Lung, and Blood Institute.
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Affiliation(s)
- Douglas M Heithoff
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA
| | - Scott P Mahan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA; Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA, 95616, USA
| | - Lucien Barnes V
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA
| | - Semen A Leyn
- Infectious and Inflammatory Diseases Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Cyril X George
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA
| | - Jaime E Zlamal
- Infectious and Inflammatory Diseases Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Jakkarin Limwongyut
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA; Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Guillermo C Bazan
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA; Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA; Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Jeffrey C Fried
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, CA, 93105, USA; Department of Pulmonary and Critical Care Medicine, Santa Barbara Cottage Hospital, Santa Barbara, CA, 93105, USA
| | - Lynn N Fitzgibbons
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, CA, 93105, USA; Division of Infectious Diseases, Santa Barbara Cottage Hospital, Santa Barbara, CA, 93105, USA
| | - John K House
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, 2570, Australia
| | - Charles E Samuel
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA
| | - Andrei L Osterman
- Infectious and Inflammatory Diseases Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - David A Low
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA.
| | - Michael J Mahan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA.
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Bannell DJ, Montrezol FT, Maxwell JD, Somani YB, Low DA, Thijssen DHJ, Jones H. Impact of handgrip exercise and ischemic preconditioning on local and remote protection against endothelial reperfusion injury in young men. Am J Physiol Regul Integr Comp Physiol 2023; 324:R329-R335. [PMID: 36572551 DOI: 10.1152/ajpregu.00061.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ischemic preconditioning (IPC), cyclical bouts of nonlethal ischemia, provides immediate protection against ischemic injury, which is evident both locally and remotely. Given the similarities in protective effects of exercise with ischemic preconditioning, we examined whether handgrip exercise also offers protection against endothelial ischemia-reperfusion (IR) injury and whether this protection is equally present in the local (exercised) and remote (contralateral, nonexercised) arm. Fifteen healthy males (age, 24 ± 3 yr; body mass index, 25 ± 2 kg/m2) attended the laboratory on three occasions. Bilateral brachial artery flow-mediated dilation (FMD) was examined at rest and after a temporary IR injury in the upper arm. Before the IR injury, in the dominant (local) arm, participants performed (randomized, counterbalanced): 1) 4 × 5 min unilateral handgrip exercise (50% maximal voluntary contraction), 2) 4 × 5 min unilateral IPC (220 mmHg), or 3) 4 × 5 min rest (control). Data were analyzed using repeated-measures general linear models. Allometrically scaled FMD declined after IR in the control condition (4.6 ± 1.3% to 2.2 ± 1.7%, P < 0.001), as well as following handgrip exercise (4.6 ± 1.6% to 3.4 ± 1.9%, P = 0.01), however, was significantly attenuated with IPC (4.5 ± 1.4% to 3.8 ± 3.5%, P = 0.14). There were no differences between the local and remote arm. Our findings reinforce the established protective effects of IPC in young, healthy males and also highlight a novel strategy to protect against IR injury with handgrip exercise, which warrants further study.
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Affiliation(s)
- Daniel J Bannell
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | | | - Joseph D Maxwell
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Yasina B Somani
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - David A Low
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
| | - Dick H J Thijssen
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom.,Department of Physiology, Radboud Institute of Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Helen Jones
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom
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Bartelli NL, Passanisi VJ, Michalska K, Song K, Nhan DQ, Zhou H, Cuthbert BJ, Stols LM, Eschenfeldt WH, Wilson NG, Basra JS, Cortes R, Noorsher Z, Gabraiel Y, Poonen-Honig I, Seacord EC, Goulding CW, Low DA, Joachimiak A, Dahlquist FW, Hayes CS. Author Correction: Proteolytic processing induces a conformational switch required for antibacterial toxin delivery. Nat Commun 2022; 13:6251. [PMID: 36271082 DOI: 10.1038/s41467-022-34174-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Nicholas L Bartelli
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Victor J Passanisi
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Karolina Michalska
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA.,Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, USA.,Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - Kiho Song
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
| | - Dinh Q Nhan
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Hongjun Zhou
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Bonnie J Cuthbert
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA
| | - Lucy M Stols
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
| | - William H Eschenfeldt
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
| | - Nicholas G Wilson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Jesse S Basra
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Ricardo Cortes
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Zainab Noorsher
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Youssef Gabraiel
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Isaac Poonen-Honig
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Elizabeth C Seacord
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Celia W Goulding
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA.,Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - David A Low
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA.,Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, USA.,Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Frederick W Dahlquist
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA.,Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Christopher S Hayes
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA. .,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA.
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8
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Barton T, Low DA, Thijssen DHJ, Romviel S, Sloots M, Smit CAJ, Janssen TWJ. Twelve-Week Daily Gluteal and Hamstring Electrical Stimulation Improves Vascular Structure and Function, Limb Volume, and Sitting Pressure in Spinal Cord Injury: A Pilot Feasibility Study. Am J Phys Med Rehabil 2022; 101:913-919. [PMID: 36104843 DOI: 10.1097/phm.0000000000001929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We examined the long-term effects of low-intensity electrical stimulation on (micro)vasculature and sitting pressure of a home-based, wearable electrical stimulation device in a pilot feasibility study. DESIGN In a cohort observation before-after trial, nine middle-aged male (n = 8) and female (n = 1) individuals (48 ± 15 yrs) with American Spinal Injury Association A-C classified chronic (1-24 yrs) spinal cord injury underwent 12 wks of self-administered daily, low-intensity gluteal and hamstring electrical stimulation (50 Hz, 6 hrs [30-min electrical stimulation, 15-min rest]). Common femoral artery diameter and blood blow were determined with ultrasound, skin vascular function during local heating was assessed using Laser-Doppler flowmetry, thigh volume was estimated using leg circumferences and skinfolds, and interface sitting pressure was measured using pressure mapping. RESULTS Resting common femoral artery diameter increased (0.73 ± 0.20 to 0.79 ± 0.22 cm, P < 0.001) and baseline common femoral artery blood flow increased (0.28 ± 0.12 to 0.40 ± 0.15 l/min, P < 0.002). Gluteal cutaneous vascular conductance showed a time*temperature interaction (P = 0.01) with higher conductance at 42°C after 12 wks. Ischial peak pressure decreased (P = 0.003) by 32 ± 23 mm Hg and pressure gradient decreased (23 ± 7 to 16 ± 6 mm Hg, P = 0.007). Thigh volume increased (+19%, P = 0.01). CONCLUSIONS Twelve-week daily home-based gluteal and hamstring electrical stimulation is feasible and effective to improve (micro)vasculature and sitting pressure, and electrical stimulation may have clinical implications for ameliorating pressure ulcers and (micro)vascular complications in spinal cord injury.
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Affiliation(s)
- Thomas Barton
- From the Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom (TB, DAL, DHJT); Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands (DHJT); Amsterdam Rehabilitation Research Center, Reade, Amsterdam, the Netherlands (SR, MS, CAJS, TWJJ); Department of Rehabilitation and Sports Medicine for Top Athletes, University Medical Center Utrecht, Utrecht, the Netherlands (MS); and Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands (TWJJ)
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9
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Bartelli NL, Passanisi VJ, Michalska K, Song K, Nhan DQ, Zhou H, Cuthbert BJ, Stols LM, Eschenfeldt WH, Wilson NG, Basra JS, Cortes R, Noorsher Z, Gabraiel Y, Poonen-Honig I, Seacord EC, Goulding CW, Low DA, Joachimiak A, Dahlquist FW, Hayes CS. Proteolytic processing induces a conformational switch required for antibacterial toxin delivery. Nat Commun 2022; 13:5078. [PMID: 36038560 PMCID: PMC9424206 DOI: 10.1038/s41467-022-32795-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 08/12/2022] [Indexed: 02/08/2023] Open
Abstract
Many Gram-negative bacteria use CdiA effector proteins to inhibit the growth of neighboring competitors. CdiA transfers its toxic CdiA-CT region into the periplasm of target cells, where it is released through proteolytic cleavage. The N-terminal cytoplasm-entry domain of the CdiA-CT then mediates translocation across the inner membrane to deliver the C-terminal toxin domain into the cytosol. Here, we show that proteolysis not only liberates the CdiA-CT for delivery, but is also required to activate the entry domain for membrane translocation. Translocation function depends on precise cleavage after a conserved VENN peptide sequence, and the processed ∆VENN entry domain exhibits distinct biophysical and thermodynamic properties. By contrast, imprecisely processed CdiA-CT fragments do not undergo this transition and fail to translocate to the cytoplasm. These findings suggest that CdiA-CT processing induces a critical structural switch that converts the entry domain into a membrane-translocation competent conformation.
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Affiliation(s)
- Nicholas L Bartelli
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Victor J Passanisi
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Karolina Michalska
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
- Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - Kiho Song
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
| | - Dinh Q Nhan
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Hongjun Zhou
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Bonnie J Cuthbert
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA
| | - Lucy M Stols
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
| | - William H Eschenfeldt
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
| | - Nicholas G Wilson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Jesse S Basra
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Ricardo Cortes
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Zainab Noorsher
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Youssef Gabraiel
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Isaac Poonen-Honig
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Elizabeth C Seacord
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Celia W Goulding
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA
- Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - David A Low
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Lemont, IL, USA
- Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Frederick W Dahlquist
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Christopher S Hayes
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA.
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA.
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France-Ratcliffe M, Hopkins ND, Low DA, Cocks MS, Jones H, Sheen KS, Sprung VS. Perceptions of Antenatal Exercise in Pregnant Females and the Impact of COVID-19. Int J Environ Res Public Health 2022; 19:10635. [PMID: 36078351 PMCID: PMC9518533 DOI: 10.3390/ijerph191710635] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/11/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
Exercise during pregnancy presents many benefits for the mother and baby. Yet, pregnancy is characterised by a decrease in exercise. Studies have reported barriers to antenatal exercise. The coronavirus (COVID-19) pandemic may have further exacerbated barriers to antenatal exercise as pregnant females faced many challenges. Rich, in-depth exploration into pregnant female's perceived barriers to antenatal exercise during COVID-19 is imperative. Questionnaires reporting physical activity levels were completed by all participants (n = 14). Semi-structured interviews were conducted between November 2020 and May 2021 in the UK. Interviews were analysed using thematic analysis and revealed four main themes: 'Perceptions of being an active person shaping activity levels in pregnancy', 'How do I know what is right? Uncertainty, seeking validation and feeling informed', 'Motivators to antenatal exercise' and 'A process of adaptations and adjustment'. Findings indicate that the COVID-19 pandemic exacerbated barriers to antenatal exercise and highlight the importance of direct psychosocial support and clear, trustworthy information. Findings also support the fundamental need for better education amongst healthcare professionals regarding antenatal exercise.
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Affiliation(s)
- Madeleine France-Ratcliffe
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - Nicola D. Hopkins
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - David A. Low
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - Matthew S. Cocks
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - Helen Jones
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - Kayleigh S. Sheen
- Faculty of Health, School of Psychology, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
| | - Victoria S. Sprung
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, UK
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Mawhinney C, Heinonen I, Low DA, Han C, Jones H, Kalliokoski KK, Kirjavainen A, Kemppainen J, DI Salvo V, Lolli L, Cable NT, Gregson W. Cool-Water Immersion Reduces Postexercise Quadriceps Femoris Muscle Perfusion More Than Cold-Water Immersion. Med Sci Sports Exerc 2022; 54:1085-1094. [PMID: 35220370 DOI: 10.1249/mss.0000000000002898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The muscle perfusion response to postexercise cold-water immersion (CWI) is not well understood. We examined the effects of graded postexercise CWI upon global and regional quadriceps femoris muscle perfusion using positron emission tomography and [15O]H2O. METHODS Using a matched-group design, 30 healthy men performed cycle ergometer exercise at 70% V̇O2peak to a core body temperature of 38°C, followed by either 10 min of CWI at 8°C, 22°C, or seated rest (control). Quadriceps muscle perfusion; thigh and calf cutaneous vascular conductance; intestinal, muscle, and local skin temperatures; thermal comfort; mean arterial pressure; and heart rate were assessed at preexercise, postexercise, and after CWI. RESULTS Global quadriceps perfusion was reduced beyond the predefined minimal clinically relevant threshold (0.75 mL per 100 g·min-1) in 22°C water versus control (difference (95% confidence interval (CI)), -2.5 (-3.9 to -1.1) mL per 100 g·min-1). Clinically relevant decreases in muscle perfusion were observed in the rectus femoris (-2.0 (-3.0 to -1.0) mL per 100 g·min-1) and vastus lateralis (-3.5 (-4.9 to -2.0) mL per 100 g·min-1) in 8°C water, and in the vastus lateralis (-3.3 (-4.8 to -1.9) mL per 100 g·min-1) in 22°C water versus control. The mean effects for vastus intermedius and vastus medialis perfusion were not clinically relevant. Clinically relevant decreases in thigh and calf cutaneous vascular conductance were observed in both cooling conditions. CONCLUSIONS The present findings revealed that less noxious CWI (22°C) promoted clinically relevant postexercise decreases in global quadriceps muscle perfusion, whereas noxious cooling (8°C) elicited no effect.
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Affiliation(s)
| | | | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Chunlei Han
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, FINLAND
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Kari K Kalliokoski
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, FINLAND
| | - Anna Kirjavainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, FINLAND
| | - Jukka Kemppainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, FINLAND
| | | | | | - N Tim Cable
- Institute of Sport, Manchester Metropolitan University, Manchester, UNITED KINGDOM
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12
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Bannell DJ, Cocks M, Goodson N, Taylor C, Peçanha T, Jones H, Low DA, Sprung VS. P216 Promoting physical activity using mobile health technology in people living with rheumatoid arthritis: MOTIVATE RA. Rheumatology (Oxford) 2022. [DOI: 10.1093/rheumatology/keac133.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background/Aims
People with rheumatoid arthritis (RA) commonly experience pain and stiffness which reduces engagement in physical activity (PA). The range of health benefits associated with PA are now well established, and include improvements in cardiovascular health and symptoms associated with RA. However, people with RA are more inactive than the general population and face unique barriers to becoming more active. Mobile health (mHealth) technology (i.e. fitness watches and apps) may provide an effective and economical solution to promoting PA in this population. Therefore, the aim of the current study is to assess the effectiveness of mHealth technology to increase PA levels and reduce disease activity in people living with RA.
Methods
Following ethical approval, 13 females diagnosed with RA were randomised to either an mHealth (n=7, age 47 ± 14 years; BMI 30 ± 5 kg/m2) or a conventional care (CC) intervention group (n=6, age 50 ± 11 years; BMI 25 ± 3 kg/m2). The CC group were provided with online educational material to increase PA whereas the mHealth group were provided with a personalised, progressive walking programme delivered via mHealth technology with ongoing support throughout the 12-week intervention. Prior to (week 0) and following (week 12) the intervention, participants conducted assessments remotely, with guidance from the research team. At each time point all participants wore a GT9X ActiGraph PA monitor for 7 days to quantify PA and completed a RADAI-5 questionnaire to monitor disease activity Change data between weeks 0 and 12 were analysed using independent t-tests and reported as mean difference (95% confidence intervals).
Results
Intervention groups were well matched in terms of age [3 years (95% CI= -12, 19); P=0.66] but differed for BMI [-5 kg/m2 (95% CI= -10, -0.1); P=0.05]. Preliminary analyses reveal no significant difference in steps per day between the mHealth vs. CC groups [323 steps/day (95% CI= -2273, 1632; P=0.72]. Similarly, no difference in RADAI-5 score was observed between the mHealth and CC groups [0.09 (95% CI= -0.28, 4.6); P=0.61].
Conclusion
These preliminary data identify the potential effectiveness of a PA programme to increase PA levels in people with RA delivered via mHealth, though positive changes in mHealth are very small at this early stage. These data, in full, will be important in identifying whether this technology could be used as a cost effective, non-pharmacological management strategy for RA.
Disclosure
D.J. Bannell: None. M. Cocks: None. N. Goodson: None. C. Taylor: None. T. Peçanha: None. H. Jones: None. D.A. Low: None. V.S. Sprung: None.
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Affiliation(s)
- Daniel J Bannell
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Matthew Cocks
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Nicola Goodson
- Department of Rheumatology, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UNITED KINGDOM
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Chloe Taylor
- School of Science and Health, Western Sydney University, Sydney, AUSTRALIA
| | - Tiago Peçanha
- Applied Physiology & Nutrition Research Group, Faculty of Medicine, University of Sao Paulo, Liverpool, BRAZIL
| | - Helen Jones
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - David A Low
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Victoria S Sprung
- School of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
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13
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Maxwell JD, Bannell DJ, Brislane A, Carter SE, Miller GD, Roberts KA, Hopkins ND, Low DA, Carter HH, Thompson A, Claassen JAHR, Thijssen DHJ, Jones H. The impact of age, sex, cardio-respiratory fitness, and cardiovascular disease risk on dynamic cerebral autoregulation and baroreflex sensitivity. Eur J Appl Physiol 2022; 122:1531-1541. [PMID: 35429292 PMCID: PMC9132800 DOI: 10.1007/s00421-022-04933-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 03/08/2022] [Indexed: 11/10/2022]
Abstract
Background Humans display an age-related decline in cerebral blood flow and increase in blood pressure (BP), but changes in the underlying control mechanisms across the lifespan are less well understood. We aimed to; (1) examine the impact of age, sex, cardiovascular disease (CVD) risk, and cardio-respiratory fitness on dynamic cerebral autoregulation and cardiac baroreflex sensitivity, and (2) explore the relationships between dynamic cerebral autoregulation (dCA) and cardiac baroreflex sensitivity (cBRS). Methods 206 participants aged 18–70 years were stratified into age categories. Cerebral blood flow velocity was measured using transcranial Doppler ultrasound. Repeated squat-stand manoeuvres were performed (0.10 Hz), and transfer function analysis was used to assess dCA and cBRS. Multivariable linear regression was used to examine the influence of age, sex, CVD risk, and cardio-respiratory fitness on dCA and cBRS. Linear models determined the relationship between dCA and cBRS. Results Age, sex, CVD risk, and cardio-respiratory fitness did not impact dCA normalised gain, phase, or coherence with minimal change in all models (P > 0.05). cBRS gain was attenuated with age when adjusted for sex and CVD risk (young–older; β = − 2.86 P < 0.001) along with cBRS phase (young–older; β = − 0.44, P < 0.001). There was no correlation between dCA normalised gain and phase with either parameter of cBRS. Conclusion Ageing was associated with a decreased cBRS, but dCA appears to remain unchanged. Additionally, our data suggest that sex, CVD risk, and cardio-respiratory fitness have little effect.
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14
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Miller GD, Maxwell JD, Thompson A, Cable NT, Low DA, George KP, Jones H. The effects of exercise training in the cold on cerebral blood flow and cerebrovascular function in young healthy individuals. Auton Neurosci 2022; 238:102945. [PMID: 35176639 DOI: 10.1016/j.autneu.2022.102945] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 11/09/2021] [Accepted: 01/16/2022] [Indexed: 11/17/2022]
Abstract
Exercise elicits acute increases in cerebral blood flow velocity (CBFv) and provokes long-term beneficial effects on CBFv, thereby reducing cerebrovascular risk. Acute exposure to a cold stimulus also increases CBFv. We compared the impact of exercise training in cold and thermoneutral environments on CFBv, cerebrovascular function and peripheral endothelial function. Twenty-one (16 males, 22 ± 5 years) individuals were randomly allocated to either a cold (5 °C) or thermoneutral (15 °C) exercise intervention. Exercise consisted of 50-min cycling at 70% heart rate max, three times per week for eight weeks. Transcranial Doppler was used to determine pre and post intervention CBFv, dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity (CVRCO2). Conduit endothelial function, microvascular function and cardiorespiratory fitness were also assessed. Cardiorespiratory fitness improved (2.91 ml.min.kg-1, 95%CI 0.49, 5.3; P = 0.02), regardless of exercise setting. Neither intervention had an impact on CBFv, CVRCO2, FMD or microvascular function (P > 0.05). There was a significant interaction between time and condition for dCA normalised gain with evidence of a decrease by 0.192%cm.s-1.%mmHg-1 (95%CI -0.318, -0.065) following training in the cold and increase (0.129%cm.s-1.%mmHg-1, 95%CI 0.011, 0.248) following training in the thermoneutral environment (P = 0.001). This was also evident for dCA phase with evidence of an increase by 0.072 rad (95%CI -0.007, 0.152) following training in the cold and decrease by 0.065 (95%CI -0.144, 0.014) radians following training in the thermoneutral environment (P = 0.02). Both training interventions improved fitness but CBFv, CVRCO2 and peripheral endothelial function were unaltered. Exercise training in the cold improved dCA whereas thermoneutral negated dCA.
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Affiliation(s)
- G D Miller
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - J D Maxwell
- Manchester University NHS Foundation Trust, Manchester, UK
| | - A Thompson
- Wolfson Centre for Personalised Medicine, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - N T Cable
- The Institute of Sport, Manchester Metropolitan University, Manchester, UK
| | - D A Low
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - K P George
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - H Jones
- Research Institute of Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK.
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15
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Heithoff DM, Barnes L, Mahan SP, Fox GN, Arn KE, Ettinger SJ, Bishop AM, Fitzgibbons LN, Fried JC, Low DA, Samuel CE, Mahan MJ. Assessment of a Smartphone-Based Loop-Mediated Isothermal Amplification Assay for Detection of SARS-CoV-2 and Influenza Viruses. JAMA Netw Open 2022; 5:e2145669. [PMID: 35089353 PMCID: PMC8800074 DOI: 10.1001/jamanetworkopen.2021.45669] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Importance A critical need exists in low-income and middle-income countries for low-cost, low-tech, yet highly reliable and scalable testing for SARS-CoV-2 virus that is robust against circulating variants. Objective To assess whether a smartphone-based assay is suitable for SARS-CoV-2 and influenza virus testing without requiring specialized equipment, accessory devices, or custom reagents. Design, Setting, and Participants This cohort study enrolled 2 subgroups of participants (symptomatic and asymptomatic) at Santa Barbara Cottage Hospital. The symptomatic group consisted of 20 recruited patients who tested positive for SARS-CoV-2 with symptoms; 30 asymptomatic patients were recruited from the same community, through negative admission screening tests for SARS-CoV-2. The smartphone-based real-time loop-mediated isothermal amplification (smaRT-LAMP) was first optimized for analysis of human saliva samples spiked with either SARS-CoV-2 or influenza A or B virus; these results then were compared with those obtained by side-by-side analysis of spiked samples using the Centers for Disease Control and Prevention (CDC) criterion-standard reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) assay. Next, both assays were used to test for SARS-CoV-2 and influenza viruses present in blinded clinical saliva samples obtained from 50 hospitalized patients. Statistical analysis was performed from May to June 2021. Exposures Testing for SARS-CoV-2 and influenza A and B viruses. Main Outcomes and Measures SARS-CoV-2 and influenza infection status and quantitative viral load were determined. Results Among the 50 eligible participants with no prior SARS-CoV-2 infection included in the study, 29 were men. The mean age was 57 years (range, 21 to 93 years). SmaRT-LAMP exhibited 100% concordance (50 of 50 patient samples) with the CDC criterion-standard diagnostic for SARS-CoV-2 sensitivity (20 of 20 positive and 30 of 30 negative) and for quantitative detection of viral load. This platform also met the CDC criterion standard for detection of clinically similar influenza A and B viruses in spiked saliva samples (n = 20), and in saliva samples from hospitalized patients (50 of 50 negative). The smartphone-based LAMP assay was rapid (25 minutes), sensitive (1000 copies/mL), low-cost (<$7/test), and scalable (96 samples/phone). Conclusions and Relevance In this cohort study of saliva samples from patients, the smartphone-based LAMP assay detected SARS-CoV-2 infection and exhibited concordance with RT-qPCR tests. These findings suggest that this tool could be adapted in response to novel CoV-2 variants and other pathogens with pandemic potential including influenza and may be useful in settings with limited resources.
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Affiliation(s)
- Douglas M Heithoff
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara
| | - Lucien Barnes
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
| | - Scott P Mahan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis
| | - Gary N Fox
- Department of Materials and Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara
| | - Katherine E Arn
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, California
| | - Sarah J Ettinger
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, California
| | - Andrew M Bishop
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, California
| | - Lynn N Fitzgibbons
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, California
- Division of Infectious Diseases, Santa Barbara Cottage Hospital, Santa Barbara, California
| | - Jeffrey C Fried
- Department of Medical Education, Santa Barbara Cottage Hospital, Santa Barbara, California
- Department of Pulmonary and Critical Care Medicine, Santa Barbara Cottage Hospital, Santa Barbara, California
| | - David A Low
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara
| | - Charles E Samuel
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
| | - Michael J Mahan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara
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16
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Peçanha T, Bannell DJ, Sieczkowska SM, Goodson N, Roschel H, Sprung VS, Low DA. Effects of physical activity on vascular function in autoimmune rheumatic diseases: a systematic review and meta-analysis. Rheumatology (Oxford) 2021; 60:3107-3120. [PMID: 33521818 DOI: 10.1093/rheumatology/keab094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/18/2020] [Accepted: 01/05/2021] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES To summarize existing evidence and quantify the effects of physical activity on vascular function and structure in autoimmune rheumatic diseases (ARDs). METHODS Databases were searched (through March 2020) for clinical trials evaluating the effects of physical activity interventions on markers of micro- and macrovascular function and macrovascular structure in ARDs. Studies were combined using random effects meta-analysis, which was conducted using Hedges' g. Meta-analyses were performed on each of the following outcomes: microvascular function [i.e. skin blood flow or vascular conductance responses to acetylcholine (ACh) or sodium nitropusside (SNP) administration]; macrovascular function [i.e. brachial flow-mediated dilation (FMD%) or brachial responses to glyceryl trinitrate (GTN%); and macrovascular structure [i.e. aortic pulse wave velocity (PWV)]. RESULTS Ten studies (11 trials) with a total of 355 participants were included in this review. Physical activity promoted significant improvements in microvascular [skin blood flow responses to ACh, g = 0.92 (95% CI 0.42, 1.42)] and macrovascular function [FMD%, g = 0.94 (95% CI 0.56, 1.02); GTN%, g = 0.53 (95% CI 0.09, 0.98)]. Conversely, there was no evidence for beneficial effects of physical activity on macrovascular structure [PWV, g = -0.41 (95% CI -1.13, 0.32)]. CONCLUSIONS Overall, the available clinical trials demonstrated a beneficial effect of physical activity on markers of micro- and macrovascular function but not on macrovascular structure in patients with ARDs. The broad beneficial impact of physical activity across the vasculature identified in this review support its role as an effective non-pharmacological management strategy for patients with ARDs.
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Affiliation(s)
- Tiago Peçanha
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Laboratory of Assessment and Conditioning in Rheumatology, Rheumatology Division, Hospital das Clínicas HCFMUSP, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Daniel J Bannell
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University
| | - Sofia Mendes Sieczkowska
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Laboratory of Assessment and Conditioning in Rheumatology, Rheumatology Division, Hospital das Clínicas HCFMUSP, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Nicola Goodson
- Liverpool University Hospitals NHS Foundation Trust, Aintree University Hospital, Liverpool, UK
| | - Hamilton Roschel
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Laboratory of Assessment and Conditioning in Rheumatology, Rheumatology Division, Hospital das Clínicas HCFMUSP, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Victoria S Sprung
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University
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17
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Speretta GF, Fornasiero A, Johns JA, Hopkins N, Thijssen DH, Low DA. Effects of Breaking up Deskwork with Physical Activity Combined with Tea Consumption on Cerebrovascular Function, Mood, and Affect. International Journal of Cardiovascular Sciences 2021. [DOI: 10.36660/ijcs.20200209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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18
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Barton TJ, Low DA, Bakker EA, Janssen T, de Groot S, van der Woude L, Thijssen DHJ. Response to Letter to the Editor on "Traditional Cardiovascular Risk Factors Strongly Underestimate the 5-Year Occurrence of Cardiovascular Morbidity and Mortality in Spinal Cord Injured Individuals". Arch Phys Med Rehabil 2021; 102:2269-2270. [PMID: 34283995 DOI: 10.1016/j.apmr.2021.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 05/31/2021] [Indexed: 10/20/2022]
Affiliation(s)
- Thomas J Barton
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - David A Low
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Esmee A Bakker
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Thomas Janssen
- Amsterdam Rehabilitation Research Center/Reade, Amsterdam, the Netherlands
| | - Sonja de Groot
- University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences, Groningen, the Netherlands; Amsterdam Rehabilitation Research Center/Reade, Amsterdam, the Netherlands
| | - Lucas van der Woude
- University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences, Groningen, the Netherlands
| | - Dick H J Thijssen
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands
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Callovini A, Fornasiero A, Savoldelli A, Stella F, Low DA, Pellegrini B, Schena F, Bortolan L. Effects of three-exercise sessions in the heat on endurance cycling performance. J Therm Biol 2021; 98:102925. [PMID: 34016347 DOI: 10.1016/j.jtherbio.2021.102925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 03/22/2021] [Accepted: 03/27/2021] [Indexed: 11/16/2022]
Abstract
PURPOSE To investigate the effects of a very short-term acclimation protocol (VSTAP) on performance, physiological and perceptual responses to exercise in the heat. METHODS 12 trained male cyclists (age 31.2 ± 7; weight 71.3 ± 7 kg, VO2max: 58.4 ± 3.7 mL/kg/min) randomly performed two Time to Exhaustion Tests (TTE) at 75% of normothermic peak power output (PPO), one in normothermia (N,18°C-50% RH) and one in the heat (H,35°C-50% RH), before and after a VSTAP intervention, consisting of 3 days-90 min exercise (10min at 30% of PPO+80 min at 50% of PPO) in H (≈4.5h of heat exposure). Performance time of TTEs and physiological and perceptual variables of both TTEs and training sessions (T1, T2 and T3) were evaluated. RESULTS Magnitude Based Inferences (MBI) revealed 92/6/1% and 62/27/11% chances of positive/trivial/negative effects of VSTAP of improving performance in H (+17%) and in N (+9%), respectively. Heart Rate (HR) decreased from T1 to T3 (p < 0.001) and T2 to T3 (p < 0.001), whereas Tympanic Temperature (TyT) decreased from T1 to T2 (p = 0.047) and from T1 to T3 (p = 0.007). Furthermore, despite the increased tolerance to target Power Output (PO) throughout training sessions, RPE decreased from T1 to T3 (p = 0.032). CONCLUSIONS The VSTAP determined meaningful physiological (i.e. decreased HR and TyT) and perceptual (i.e. decreased RPE) adaptations to submaximal exercise. Furthermore, showing good chances to improve performance in the heat, it represents a valid acclimation strategy to be implemented when no longer acclimation period is possible. Finally, no cross-over effect of the VSTAP on performance in temperate conditions was detected.
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Affiliation(s)
- Alexa Callovini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Alessandro Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Aldo Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Federico Stella
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
| | - David A Low
- Liverpool John Moores University, Research Institute for Sport and Exercise Sciences (RISES), Liverpool, United Kingdom.
| | - Barbara Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Federico Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Lorenzo Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy; Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
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20
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Roberts KA, Draijer R, Hopkins ND, de Graaf Y, Holder SM, Carter SE, Thijssen DHJ, Low DA. Impact of green tea on the deleterious cardiometabolic effects of 7-days unhealthy lifestyle in young healthy males. Physiol Rep 2021; 9:e14720. [PMID: 33682367 PMCID: PMC7937942 DOI: 10.14814/phy2.14720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The aim of this study was to examine if catechin-rich green tea abrogates the negative effects of 7-days of physical inactivity and excessive calorie-intake on insulin homeostasis and peripheral vascular function. METHODS Using a randomized, double-blind, crossover design, twelve healthy men (29 ± 6 yrs) underwent 7-days unhealthy lifestyle (UL), including physical inactivity (-50% steps/day) and overfeeding (+50% kcal/day). This was combined with green tea consumption (UL-tea; 3 doses/day) or placebo (UL-placebo). Before and after each intervention, we examined postprandial blood glucose and insulin (3-h after a 1,202 kcal meal) and upper and lower limb vascular function (flow-mediated dilation (FMD%)) and carotid artery reactivity (CAR%). RESULTS UL-placebo increased postprandial glucose and insulin, while UL-tea decreased postprandial glucose and insulin (Time*Intervention interaction effects: both p < 0.05). UL-placebo decreased CAR% and femoral FMD%, while UL-tea prevented these effects (Time*Intervention interaction effects of p < 0.04 and p < 0.001, respectively). There was no main effect of Time or Time*Intervention interaction (both p > 0.05) for brachial FMD%. CONCLUSION Seven days of physical inactivity and overfeeding impair insulin homeostasis and vascular function. These effects were mitigated by a daily intake of catechin-rich green tea.
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Affiliation(s)
- Kirsty A Roberts
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - Richard Draijer
- Unilever Foods Innovation Centre, Wageningen, The Netherlands
| | - Nicola D Hopkins
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - Young de Graaf
- Unilever Foods Innovation Centre, Wageningen, The Netherlands
| | - Sophie M Holder
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - Sophie E Carter
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
| | - Dick H J Thijssen
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK.,Department of Physiology, Research Institute for Health Science, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - David A Low
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UK
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21
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Fornasiero A, Savoldelli A, Stella F, Callovini A, Bortolan L, Zignoli A, Low DA, Mourot L, Schena F, Pellegrini B. Response to Chaen and Trapellieni re: "Shortening Work-Rest Durations Reduces Physiological and Perceptual Load During Uphill Walking in Simulated Cold High-Altitude Conditions," by Fornasiero et al. High Alt Med Biol 2021; 22:105-106. [PMID: 33783236 DOI: 10.1089/ham.2020.0217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Alessandro Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Aldo Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Federico Stella
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Alexa Callovini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Lorenzo Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Andrea Zignoli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Industrial Engineering, University of Trento, Trento, Italy
| | - David A Low
- Liverpool John Moores University, Research Institute for Sport and Exercise Sciences (RISES), Liverpool, United Kingdom
| | - Laurent Mourot
- Laboratory of Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform (EA 3920), University of Bourgogne Franche Comté, Besançon, France
- Division for Physical Education, National Research Tomsk Polytechnic University, Tomsk, Russia
| | - Federico Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Barbara Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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22
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Wäneskog M, Halvorsen T, Filek K, Xu F, Hammarlöf DL, Hayes CS, Braaten BA, Low DA, Poole SJ, Koskiniemi S. Escherichia coli EC93 deploys two plasmid-encoded class I contact-dependent growth inhibition systems for antagonistic bacterial interactions. Microb Genom 2021; 7:mgen000534. [PMID: 33646095 PMCID: PMC8190604 DOI: 10.1099/mgen.0.000534] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/29/2021] [Indexed: 01/27/2023] Open
Abstract
The phenomenon of contact-dependent growth inhibition (CDI) and the genes required for CDI (cdiBAI) were identified and isolated in 2005 from an Escherichia coli isolate (EC93) from rats. Although the cdiBAIEC93 locus has been the focus of extensive research during the past 15 years, little is known about the EC93 isolate from which it originates. Here we sequenced the EC93 genome and find two complete and functional cdiBAI loci (including the previously identified cdi locus), both carried on a large 127 kb plasmid. These cdiBAI systems are differentially expressed in laboratory media, enabling EC93 to outcompete E. coli cells lacking cognate cdiI immunity genes. The two CDI systems deliver distinct effector peptides that each dissipate the membrane potential of target cells, although the two toxins display different toxic potencies. Despite the differential expression and toxic potencies of these CDI systems, both yielded similar competitive advantages against E. coli cells lacking immunity. This can be explained by the fact that the less expressed cdiBAI system (cdiBAIEC93-2) delivers a more potent toxin than the highly expressed cdiBAIEC93-1 system. Moreover, our results indicate that unlike most sequenced CDI+ bacterial isolates, the two cdi loci of E. coli EC93 are located on a plasmid and are expressed in laboratory media.
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Affiliation(s)
- Marcus Wäneskog
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Tiffany Halvorsen
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, California, USA
| | - Klara Filek
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Present address: Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Feifei Xu
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Disa L. Hammarlöf
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Present address: Science for Life Laboratory, KTH, Sweden
| | - Christopher S. Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, California, USA
| | - Bruce A. Braaten
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, California, USA
| | - David A. Low
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, California, USA
| | - Stephen J. Poole
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, California, USA
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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23
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Zignoli A, Fornasiero A, Rota P, Muollo V, Peyré-Tartaruga LA, Low DA, Fontana FY, Besson D, Pühringer M, Ring-Dimitriou S, Mourot L. Oxynet: A collective intelligence that detects ventilatory thresholds in cardiopulmonary exercise tests. Eur J Sport Sci 2021; 22:425-435. [PMID: 33331795 DOI: 10.1080/17461391.2020.1866081] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The problem of the automatic determination of the first and second ventilatory thresholds (VT1 and VT2) from cardiopulmonary exercise test (CPET) still leads to controversy. The reliability of the gold standard methodology (i.e. expert visual inspection) feeds into the debate and several authors call for more objective automatic methods to be used in the clinical practice. In this study, we present a framework based on a collaborative approach, where a web-application was used to crowd-source a large number (1245) of CPET data of individuals with different aerobic fitness. The resulting database was used to train and test an artificial intelligence (i.e. a convolutional neural network) algorithm. This automatic classifier is currently implemented in another web-application and was used to detect the ventilatory thresholds in the available CPET. A total of 206 CPET were used to evaluate the accuracy of the estimations against the expert opinions. The neural network was able to detect the ventilatory thresholds with an average mean absolute error of 178 (198) mlO2/min (11.1%, r = 0.97) and 144 (149) mlO2/min (6.1%, r = 0.99), for VT1 and VT2 respectively. The performance of the neural network in detecting VT1 deteriorated in case of individuals with poor aerobic fitness. Our results suggest the potential for a collective intelligence system to outperform isolated experts in ventilatory thresholds detection. However, the inclusion of a larger number of VT1 examples certified by a community of experts will be likely needed before the abilities of this collective intelligence can be translated into the clinical use of CPET.
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Affiliation(s)
- A Zignoli
- Department of Industrial Engineering, University of Trento, Trento, Italy.,CeRiSM Research Centre, University of Verona, Trento, Italy.,ProM Facility, Trentino Sviluppo, Trento, Italy
| | - A Fornasiero
- CeRiSM Research Centre, University of Verona, Trento, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - P Rota
- Department of Information Engineering and Computer Science, University of Trento, Trento, Italy
| | - V Muollo
- Department of Medicine, Clinical and Experimental Biomedical Sciences, University of Verona, Verona, Italy
| | - L A Peyré-Tartaruga
- Exercise Research Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - D A Low
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - F Y Fontana
- Team Novo Nordisk professional cycling team, Atlanta, USA
| | - D Besson
- INSERM, CIC 1432, Module Plurithématique, Plateforme d'Investigation Technologique, Dijon, France.,CHU Dijon-Bourgogne, Centre d'Investigation Clinique, Module Plurithématique, Plateforme d'Investigation Technologique, Dijon, France
| | - M Pühringer
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
| | - S Ring-Dimitriou
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
| | - L Mourot
- EA3920 Prognostic Factors and Regulatory Factors of Cardiac and Vascular Pathologies, Exercise Performance Health Innovation (EPHI) platform, University of Bourgogne Franche-Comté, Besançon, France.,National Research Tomsk Polytechnic University, Tomsk, Russia
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24
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Peçanha T, de Brito LC, Fecchio RY, de Sousa PN, Silva ND, Couto PG, de Abreu AP, da Silva GV, Mion D, Low DA, de Moraes Forjaz CL. Activation of Mechanoreflex, but not Central Command, Delays Heart Rate Recovery after Exercise in Healthy Men. Int J Sports Med 2020; 42:602-609. [DOI: 10.1055/a-1297-4475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AbstractThis study tested the hypotheses that activation of central command and muscle mechanoreflex during post-exercise recovery delays fast-phase heart rate recovery with little influence on the slow phase. Twenty-five healthy men underwent three submaximal cycling bouts, each followed by a different 5-min recovery protocol: active (cycling generated by the own subject), passive (cycling generated by external force) and inactive (no-cycling). Heart rate recovery was assessed by the heart rate decay from peak exercise to 30 s and 60 s of recovery (HRR30s, HRR60s fast phase) and from 60 s-to-300 s of recovery (HRR60−300s slow phase). The effect of central command was examined by comparing active and passive recoveries (with and without central command activation) and the effect of mechanoreflex was assessed by comparing passive and inactive recoveries (with and without mechanoreflex activation). Heart rate recovery was similar between active and passive recoveries, regardless of the phase. Heart rate recovery was slower in the passive than inactive recovery in the fast phase (HRR60s=20±8vs.27 ±10 bpm, p<0.01), but not in the slow phase (HRR60−300s=13±8vs.10±8 bpm, p=0.11). In conclusion, activation of mechanoreflex, but not central command, during recovery delays fast-phase heart rate recovery. These results elucidate important neural mechanisms behind heart rate recovery regulation.
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Affiliation(s)
- Tiago Peçanha
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Leandro Campos de Brito
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
- School of Physical Education and Sport, Sao Paulo, University of Sao Paulo, Brazil
| | - Rafael Yokoyama Fecchio
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Patricia Nascimento de Sousa
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Natan Daniel Silva
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Andrea Pio de Abreu
- Hipertension Unit, General Hospital, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Giovanio Vieira da Silva
- Hipertension Unit, General Hospital, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Decio Mion
- Hipertension Unit, General Hospital, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - David A. Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom of Great Britain and Northern Ireland
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25
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Brislane Á, Jones H, Holder SM, Low DA, Hopkins ND. The Effect of Exercise During Pregnancy on Maternal and Offspring Vascular Outcomes: a Pilot Study. Reprod Sci 2020; 28:510-523. [PMID: 33258064 PMCID: PMC7808996 DOI: 10.1007/s43032-020-00302-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/20/2020] [Indexed: 01/28/2023]
Abstract
The aim of this pilot study is to obtain estimates for the change in maternal cerebrovascular (primary) and offspring vascular structure (secondary) during healthy pregnancy that includes structured exercise. Eighteen pregnant women self-assigned to a moderate-intensity aerobic exercise intervention or a control group. Maternal cerebral blood flow (CBF) at the middle cerebral artery, cerebro- and peripheral-vascular function was assessed at the end of each trimester. Offspring carotid artery intima-media thickness (IMT) was measured within 12 weeks of birth. For exploratory purposes, we performed statistical analysis to provide estimates of the change for primary and secondary outcome variables. Maternal CBF reduced (− 8 cm s−1 [− 14 to − 2]) with evidence of change to cerebral autoregulation (normalised gain: 0.12 %cm s−1% mmHg−1mmHg/% [− 0.18 to 0.40]) during pregnancy. Offspring carotid IMT was smaller in the exercise group (− 0.04 mm [− 0.12–0.03]) compared with controls. Based upon this data, a sample size of 33 and 57 in each group is required for low-frequency normalised gain and offspring IMT, respectively. This would provide 90% power to detect statistically significant (P < 0.05) between group differences in a randomised controlled trial. CBF is reduced in pregnancy, possibly due to reduced vascular resistance and altered maternal cerebral autoregulation. Maternal exercise had negligible effects on cerebrovascular adaptation to pregnancy, but we observed lower offspring carotid artery wall thickness following maternal exercise. Our directional findings and sample size estimations should be explored in a fully powered randomised control trial. Clinical trial registration: The trial was registered on March 14th at https://register.clinicaltrials.gov (NCT03079258). Participant enrolment began on 3rd April 2016.
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Affiliation(s)
- Áine Brislane
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK.
- School of Sport, York St. John University, Lord Mayor's Walk, York, YO31 7EX, UK.
| | - Helen Jones
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Sophie M Holder
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - David A Low
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Nicola D Hopkins
- Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
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26
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Kleinnibbelink G, Stens NA, Fornasiero A, Speretta GF, Van Dijk AP, Low DA, Oxborough DL, Thijssen DH. The acute and chronic effects of high-intensity exercise in hypoxia on blood pressure and post-exercise hypotension: A randomized cross-over trial. Medicine (Baltimore) 2020; 99:e22411. [PMID: 32991471 PMCID: PMC7523751 DOI: 10.1097/md.0000000000022411] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Acute exercise leads to an immediate drop in blood pressure (BP), also called post-exercise hypotension (PEH). Exercise in hypoxia is related to additional vasodilation, potentially contributing to more profound PEH. Therefore, we investigated the impact of hypoxia versus normoxia on the magnitude of PEH. Second, we examined whether these changes in PEH relate to the BP-lowering effects of 12-week exercise training under hypoxia. METHODS In this prospective study, 21 healthy individuals (age 22.2 ± 3.0 years, 14 male) performed a 45-minute high-intensity running exercise on 2 different days in a random order, under hypoxia (fraction of inspired oxygen 14.5%) and normoxia (fraction of inspired oxygen 20.9%). BP was examined pre-exercise (t = 0) and at t = 15, t = 30, t = 45, and t = 60 minutes post-exercise. Afterward, subjects took part in a 12-week hypoxic running exercise training program. Resting BP was measured before and after the 12-week training program. RESULTS Acute exercise induced a significant decrease in systolic BP (systolic blood pressure [SBP], P = .001), but not in diastolic BP (diastolic blood pressure [DBP], P = .113). No significant differences were observed in post-exercise BP between hypoxic and normoxic conditions (SBP, P = .324 and DBP, P = .204). Post-exercise changes in SBP, DBP, and mean arterial pressure significantly correlated to the 12-week exercise training-induced changes in SBP (r = 0.557, P = .001), DBP (r = 0.615, P < .001), and mean arterial pressure (r = 0.458, P = .011). CONCLUSION Our findings show that hypoxia does not alter the magnitude of PEH in healthy individuals, whilst PEH relates to the BP-lowering effects of exercise. These data highlight the strong link between acute and chronic changes in BP.
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Affiliation(s)
- Geert Kleinnibbelink
- Department of Physiology
- Department of Cardiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Niels A. Stens
- Department of Physiology
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Alessandro Fornasiero
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- CeRiSM Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Guilherme F. Speretta
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- Department of Physiological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Arie P.J. Van Dijk
- Department of Cardiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - David A. Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - David L. Oxborough
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Dick H.J. Thijssen
- Department of Physiology
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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27
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Barton TJ, Low DA, Bakker EA, Janssen T, de Groot S, van der Woude L, Thijssen DHJ. Traditional Cardiovascular Risk Factors Strongly Underestimate the 5-Year Occurrence of Cardiovascular Morbidity and Mortality in Spinal Cord Injured Individuals. Arch Phys Med Rehabil 2020; 102:27-34. [PMID: 32861666 DOI: 10.1016/j.apmr.2020.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/26/2020] [Accepted: 07/23/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To explore whether traditional models of cardiovascular disease (CVD) risk prediction correctly predict CVD events across a median 5.7-year follow-up period in individuals with spinal cord injury (SCI) and whether adding SCI-related characteristics (ie, lesion level) to the prediction model can improve the prognostic value. DESIGN Retrospective analysis of patient records. SETTING Observation at the start of active rehabilitation of participants in a multicenter cohort study, "Restoration of (Wheelchair) Mobility in SCI Rehabilitation," in the Netherlands. PARTICIPANTS Patients with SCI (N=200) The patients were 74% men, aged 40±14 years, and with an American Spinal Injury Association (ASIA) impairment score of A through D. Forty percent had tetraplegia, and 69% were motor complete. INTERVENTIONS Risk profiling/not applicable. MAIN OUTCOME MEASURES Survival status and cardiovascular morbidity and mortality qwere obtained from medical records. Five-year Framingham Risk Scores (FRS) and the FRS ability to predict events assessed using receiver operating characteristic (ROC) curves with corresponding areas under the curve (AUC) and 95% confidence intervals (CI). Kaplan-Meier curves and the log-rank test were used to assess the difference in clinical outcome between participants with an FRS score lower or higher than the median FRS score for the cohort. SCI-related factors associated with CVD events, ASIA impairment, motor completeness, level of injury, and sports participation before injury were explored using univariate and multivariate Cox proportional hazard regression. RESULTS The median 5-year FRS was 1.36%. Across a median follow-up period of 5.7 years, 39 developed a CVD event, including 10 fatalities. Although the FRS markedly underestimated the true occurrence of CVD events, the Kaplan-Meier curves and the log-rank test showed that the risk ratio for individuals with an FRS score less than the median FRS (eg, low risk) versus a score greater than the median FRS (high risk) was 3.2 (95% CI, 1.6-6.5; P=.001). Moreover, ROC with corresponding AUCs suggests acceptable accuracy of the FRS to identify individuals with increased risk for future CVD events (ROC AUC of 0.71; 95% CI, 0.62-0.82). Adding ASIA impairment (0.74; 95% CI, 0.66-0.82), motor impairment (0.74; 95% CI, 0.66-0.83), level of injury (0.72; 95% CI, 0.63-0.81), or active engagement in sport before injury (0.72; 95% CI, 0.63-0.88) to the FRS did not improve the level of discrimination. CONCLUSIONS Our 5.7-year retrospective study reveals that cardiovascular risk factors and risk models markedly underestimate the true risk for CVD events in individuals with SCI. Nonetheless, these markers successfully distinguish between SCI individuals at high versus low risk for future CVD events. Our data may have future clinical implications, both related to (cutoff values of) CVD risk factors, but also for (earlier) prescription of (non)pharmacologic strategies against CVD in SCI individuals.
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Affiliation(s)
- Thomas J Barton
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - David A Low
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Esmee A Bakker
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Thomas Janssen
- Amsterdam Rehabilitation Research Center, Reade, Amsterdam, the Netherlands
| | - Sonja de Groot
- Amsterdam Rehabilitation Research Center, Reade, Amsterdam, the Netherlands; University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences; Groningen, the Netherlands
| | - Lucas van der Woude
- University of Groningen, University Medical Center Groningen, Center of Human Movement Sciences; Groningen, the Netherlands
| | - Dick H J Thijssen
- Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, the Netherlands.
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Abstract
All bacteria must compete for growth niches and other limited environmental resources. These existential battles are waged at several levels, but one common strategy entails the transfer of growth-inhibitory protein toxins between competing cells. These antibacterial effectors are invariably encoded with immunity proteins that protect cells from intoxication by neighboring siblings. Several effector classes have been described, each designed to breach the cell envelope of target bacteria. Although effector architectures and export pathways tend to be clade specific, phylogenetically distant species often deploy closely related toxin domains. Thus, diverse competition systems are linked through a common reservoir of toxin-immunity pairs that is shared via horizontal gene transfer. These toxin-immunity protein pairs are extraordinarily diverse in sequence, and this polymorphism underpins an important mechanism of self/nonself discrimination in bacteria. This review focuses on the structures, functions, and delivery mechanisms of polymorphic toxin effectors that mediate bacterial competition.
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Affiliation(s)
- Zachary C Ruhe
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA;
| | - David A Low
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA; .,Biomolecular Science and Engineering Program, University of California, Santa Barbara, California 93106, USA
| | - Christopher S Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA; .,Biomolecular Science and Engineering Program, University of California, Santa Barbara, California 93106, USA
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Fornasiero A, Savoldelli A, Stella F, Callovini A, Bortolan L, Zignoli A, Low DA, Mourot L, Schena F, Pellegrini B. Shortening Work-Rest Durations Reduces Physiological and Perceptual Load During Uphill Walking in Simulated Cold High-Altitude Conditions. High Alt Med Biol 2020; 21:249-257. [PMID: 32412801 DOI: 10.1089/ham.2019.0136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Fornasiero, Alessandro, Aldo Savoldelli, Federico Stella, Alexa Callovini, Lorenzo Bortolan, Andrea Zignoli, David A. Low, Laurent Mourot, Federico Schena, and Barbara Pellegrini. Shortening work-rest durations reduces physiological and perceptual load during uphill walking in simulated cold high-altitude conditions. High Alt Med Biol. 21:249-257, 2020. Background: We investigated the effects of two different work-rest durations on the physiological and perceptual responses to a simulated mountain hike in a cold hypoxic environment. Materials and Methods: Twelve healthy nonacclimatized active men (age 31.3 ± 5.3 years, body mass index 22.4 ± 1.5 kg/m2) completed a 80-minute work-matched intermittent exercise on a motorized treadmill (25% incline, fixed self-selected speed), in a simulated mountain environment (-25°C, FiO2 = 11%, ≈5000 m a.s.l.), wearing extreme cold weather gear, once with short (20 × 3 minutes walking with 1 minute rest; SHORT) and once with long (10 × 6 minutes walking with 2 minutes rest; LONG) work-rest durations. Heart rate (HR), pulse oxygen saturation (SpO2), rate of perceived exertion (RPE), and thermal sensation (TS) were assessed throughout the exercise protocols. Cardiac autonomic modulation was assessed before (PRE) and after exercise (POST) in supine position, as well as during standing resting periods by means of HR recovery (HRR) assessment. Results: SpO2 and TS were similar (p > 0.05) in SHORT and LONG protocols. HR and RPE were increased, and HRR reduced during LONG compared to SHORT (p < 0.05). Parasympathetic activity indices were reduced at POST after both protocols (p < 0.05), but to a lesser extent after SHORT (p < 0.05). Conclusions: Reduced work-rest durations are associated with improved perceptual responses and less perturbation of cardiac autonomic balance, compared to longer work-rest durations. Shorter exercise periods from more frequent breaks during hikes at high altitude may represent a valid strategy to limit the impact of exercise under extreme environmental conditions.
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Affiliation(s)
- Alessandro Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Aldo Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Federico Stella
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Alexa Callovini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Lorenzo Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Andrea Zignoli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Industrial Engineering, University of Trento, Trento, Italy
| | - David A Low
- Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
| | - Laurent Mourot
- Laboratory of Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform (EA 3920), University of Bourgogne Franche-Comté, Besançon, France.,Tomsk Polytechnic University, Tomsk, Russia
| | - Federico Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Barbara Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Mawhinney C, Heinonen I, Low DA, Han C, Jones H, Kalliokoski KK, Kirjavainen A, Kemppainen J, Di Salvo V, Weston M, Cable T, Gregson W. Changes in quadriceps femoris muscle perfusion following different degrees of cold-water immersion. J Appl Physiol (1985) 2020; 128:1392-1401. [PMID: 32352343 DOI: 10.1152/japplphysiol.00833.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We examined the influence of graded cold-water immersion (CWI) on global and regional quadriceps muscle perfusion with positron emission tomography (PET) and [15O]H2O. In 30 healthy men [33 ± 8 yr; 81 ± 10 kg; 184 ± 5 cm; percentage body fat: 13 ± 5%; peak oxygen uptake (V̇o2peak): 47 ± 8 mL·kg-1·min-1] quadriceps perfusion, thigh and calf cutaneous vascular conductance (CVC), intestinal, muscle, and local skin temperatures, thermal comfort, mean arterial pressure, and heart rate were assessed before and after 10 min of CWI at 8°C, 15°C, or 22°C. Global quadriceps perfusion did not change beyond a clinically relevant threshold (0.75 mL·100 g·min-1) in any condition and was similar between conditions {range of differences [95% confidence interval (CI)]: 0.1 mL·100 g·min-1 (-0.9 to 1.2 mL·100 g·min-1) to 0.9 mL·100 g·min-1 (-0.2 to 1.9 mL·100 g·min-1)}. Muscle perfusion was greater in vastus intermedius (VI) compared with vastus lateralis (VL) (2.2 mL·100 g·min-1; 95% CI 1.5 to 3.0 mL·100 g·min-1) and rectus femoris (RF) (2.2 mL·100 g·min-1; 1.4 to 2.9 mL·100 g·min-1). A clinically relevant increase in VI muscle perfusion after immersion at 8°C and a decrease in RF muscle perfusion at 15°C were observed. A clinically relevant increase in perfusion was observed in VI in 8°C compared with 22°C water (2.3 mL·100 g·min-1; 1.1 to 3.5 mL·100 g·min-1). There were no clinically relevant between-condition differences in thigh CVC. Our findings suggest that CWI (8-22°C) does not reduce global quadriceps muscle perfusion to a clinically relevant extent; however, colder water increases (8°C) deep muscle perfusion and reduces (15°C) superficial muscle (RF) perfusion in the quadriceps muscle.NEW & NOTEWORTHY Using positron emission tomography, we report for the first time muscle perfusion heterogeneity in the quadriceps femoris in response to different degrees of cold-water immersion (CWI). Noxious CWI temperatures (8°C) increase perfusion in the deep quadriceps muscle, whereas superficial quadriceps muscle perfusion is reduced in cooler (15°C) water. Therefore, these data have important implications for the selection of CWI approaches used in the treatment of soft tissue injury, while also increasing our understanding of the potential mechanisms underpinning CWI.
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Affiliation(s)
- Chris Mawhinney
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.,College of Sports Science and Technology, Mahidol University, Salaya, Thailand
| | - Ilkka Heinonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Clinical Physiology and Nuclear Medicine, University of Turku, Turku, Finland.,Rydberg Laboratory of Applied Sciences, University of Halmstad, Halmstad, Sweden
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Chunlei Han
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Kari K Kalliokoski
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Anna Kirjavainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Jukka Kemppainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Valter Di Salvo
- Football Performance and Science Department, Aspire Academy, Doha, Qatar
| | - Matthew Weston
- School of Health and Social Care, Teesside University, Middlesbrough, United Kingdom.,Football Performance and Science Department, Aspire Academy, Doha, Qatar
| | - Tim Cable
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Warren Gregson
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.,Football Performance and Science Department, Aspire Academy, Doha, Qatar
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Thomas SD, Carter HH, Jones H, Thijssen DH, Low DA. Effects of Acute Exercise on Cutaneous Thermal Sensation. Int J Environ Res Public Health 2020; 17:ijerph17072491. [PMID: 32268472 PMCID: PMC7177974 DOI: 10.3390/ijerph17072491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/02/2020] [Accepted: 04/02/2020] [Indexed: 11/16/2022]
Abstract
The aim of this study was to assess the effect of exercise intensity on the thermal sensory function of active and inactive limbs. In a randomised and counterbalanced manner, 13 healthy young male participants (25 ± 6 years, 1.8 ± 0.1 m, 77 ± 6 kg) conducted: (1) 30-min low-intensity (50% heart rate maximum, HRmax; LOW) and (2) 30-min high-intensity (80% HRmax; HIGH) cycling exercises, and (3) 30 min of seated rest (CONTROL). Before, immediately after, and 1 h after, each intervention, thermal sensory functions of the non-dominant dorsal forearm and posterior calf were examined by increasing local skin temperature (1 °C/s) to assess perceptual heat sensitivity and pain thresholds. Relative to pre-exercise, forearm heat sensitivity thresholds were increased immediately and 1 hr after HIGH, but there were no changes after LOW exercise or during CONTROL (main effect of trial; p = 0.017). Relative to pre-exercise, calf heat sensitivity thresholds were not changed after LOW or HIGH exercise or during CONTROL (main effect of trial; p = 0.629). There were no changes in calf (main effect of trial; p = 0.528) or forearm (main effect of trial; p = 0.088) heat pain thresholds after exercise in either LOW or HIGH or CONTROL. These results suggest that cutaneous thermal sensitivity function of an inactive limb is only reduced after higher intensity exercise but is not changed in a previously active limb after exercise. Exercise does not affect heat pain sensitivity in either active or inactive limbs.
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Affiliation(s)
- Samuel D. Thomas
- Research Institute of Sports & Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; (S.D.T.); (H.H.C.); (H.J.); (D.H.J.T.)
| | - Howard H. Carter
- Research Institute of Sports & Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; (S.D.T.); (H.H.C.); (H.J.); (D.H.J.T.)
| | - Helen Jones
- Research Institute of Sports & Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; (S.D.T.); (H.H.C.); (H.J.); (D.H.J.T.)
| | - Dick H.J. Thijssen
- Research Institute of Sports & Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; (S.D.T.); (H.H.C.); (H.J.); (D.H.J.T.)
- Department of Physiology, Radboud University Nijmegen Medical Centre, 6525 GA Nijmegen, The Netherlands
| | - David A. Low
- Research Institute of Sports & Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; (S.D.T.); (H.H.C.); (H.J.); (D.H.J.T.)
- Correspondence: ; Tel.: +44-015-1904-6244
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Mullington CJ, Low DA, Strutton PH, Malhotra S. A mechanistic study of the tremor associated with epidural anaesthesia for intrapartum caesarean delivery. Int J Obstet Anesth 2020; 43:56-64. [PMID: 32169261 DOI: 10.1016/j.ijoa.2020.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 02/06/2020] [Accepted: 02/17/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND It is not known if the tremor associated with an epidural top-up dose for intrapartum caesarean delivery is thermoregulatory shivering. A tremor is only shivering if it has the same frequency profile as cold stress-induced shivering. Thermoregulatory shivering is a response to a reduction in actual body temperature, whereas non-thermoregulatory shivering may be triggered by a reduction in sensed body temperature. This mechanistic study aimed to compare: 1. the frequency profiles of epidural top-up tremor and cold stress-induced shivering; and 2. body temperature (actual and sensed) before epidural top-up and at the onset of tremor. METHODS Twenty obstetric patients received an epidural top-up for intrapartum caesarean delivery and 20 non-pregnant female volunteers underwent a cold stress. Tremor, surface electromyography, core temperature, skin temperature (seven sites) and temperature sensation votes (a bipolar visual analog score ranging from -50 to +50 mm) were recorded. RESULTS The mean (SD) primary oscillation (9.9 (1.9) Hz) frequency of epidural top-up tremor did not differ from that of cold stress-induced shivering (9.0 (1.6) Hz; P=0.194), but the mean (SD) burst frequency was slower (6.1 (1.2) × 10-2 Hz vs 6.9 (0.7) × 10-2 Hz, respectively; P=0.046). Before the epidural top-up dose, the mean (SD) core temperature was 37.6 (0.6) °C. Between the epidural top-up dose and the onset of tremor the mean (SD) core temperature did not change (-0.1 (0.1) °C; P=0.126), the mean (SD) skin temperature increased (+0.4 (0.4) °C; P=0.002) and the mean (SD) temperature sensation votes decreased (-12 (16) mm; P=0.012). CONCLUSION These results suggest that epidural top-up tremor is a form of non-thermoregulatory shivering triggered by a reduction in sensed body temperature.
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Affiliation(s)
| | - D A Low
- School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | | | - S Malhotra
- Department of Anaesthesia, Fiona Stanley Hospital, Murdoch, Perth, Australia
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Low DA, Jones H, Cable NT, Alexander LM, Kenney WL. Historical reviews of the assessment of human cardiovascular function: interrogation and understanding of the control of skin blood flow. Eur J Appl Physiol 2019; 120:1-16. [PMID: 31776694 PMCID: PMC6969866 DOI: 10.1007/s00421-019-04246-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/19/2019] [Indexed: 02/06/2023]
Abstract
Several techniques exist for the determination of skin blood flow that have historically been used in the investigation of thermoregulatory control of skin blood flow, and more recently, in clinical assessments or as an index of global vascular function. Skin blood flow measurement techniques differ in their methodology and their strengths and limitations. To examine the historical development of techniques for assessing skin blood flow by describing the origin, basic principles, and important aspects of each procedure and to provide recommendations for best practise. Venous occlusion plethysmography was one of the earliest techniques to intermittently index a limb’s skin blood flow under conditions in which local muscle blood flow does not change. The introduction of laser Doppler flowmetry provided a method that continuously records an index of skin blood flow (red cell flux) (albeit from a relatively small skin area) that requires normalisation due to high site-to-site variability. The subsequent development of laser Doppler and laser speckle imaging techniques allows the mapping of skin blood flow from larger surface areas and the visualisation of capillary filling from the dermal plexus in two dimensions. The use of iontophoresis or intradermal microdialysis in conjunction with laser Doppler methods allows for the local delivery of pharmacological agents to interrogate the local and neural control of skin blood flow. The recent development of optical coherence tomography promises further advances in assessment of the skin circulation via three-dimensional imaging of the skin microvasculature for quantification of vessel diameter and vessel recruitment.
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Affiliation(s)
- David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK.
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - N Tim Cable
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Liverpool, UK
| | - Lacy M Alexander
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
| | - W Larry Kenney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
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Woodward KA, Draijer R, Thijssen DHJ, Low DA. Polyphenols and Microvascular Function in Humans: A Systematic Review. Curr Pharm Des 2019; 24:203-226. [PMID: 29119919 DOI: 10.2174/1381612823666171109103939] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/20/2017] [Accepted: 11/02/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Polyphenol-rich dietary sources are acknowledged to have potential cardiovascular health benefits, particularly in reducing cardiovascular disease risk. METHODS This systematic review sought to determine the effect of polyphenol-rich foods and beverages upon microvascular function, which is of considerable importance in its contribution towards the pathophysiology of microvascular-related complications but also in the future development of (macro-vessel) cardiovascular disease. RESULTS Overall, consumption of polyphenol-rich foods and beverages demonstrate improved microvascular function, although this is dependent upon the polyphenol source, the dose of the product, the duration of consumption and the population group studied. Most subgroups reviewed suggest an overall beneficial effect on microvascular function, particularly grape-derived products, cocoa, tea, pine bark and Rutaceae aurantiae. Other groups remain equivocal and require further study due to the limited research performed to date. CONCLUSION Polyphenols are abundant in the human diet and this systematic review demonstrates that they are an inexpensive, non-pharmacological approach for improving cardiovascular health in currently healthy individuals and in populations with microvascular dysfunction.
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Affiliation(s)
- Kirsty A Woodward
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Richard Draijer
- Unilever Research & Development, Olivier van Noortlaan 120, 3133 AT, Vlaardingen, Netherlands
| | - Dick H J Thijssen
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.,Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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Abstract
OBJECTIVE Menopausal hot flushes negatively impact quality of life and may be a biomarker of cardiovascular and metabolic disease risk; therefore understanding the physiology of hot flushes is important. Current thinking is that a small elevation (∼0.03-0.05C) in core temperature surpasses a sweating threshold (that is reduced in the menopause), sweating is activated, and a hot flush ensues. Nevertheless, more recent studies examining thermoregulatory control question whether core temperature per se can explain the trigger for a hot flush. The primary aim of this study was to assess the contribution of increases in core temperature on the occurrence of menopausal hot flushes. METHODS For this purpose, 108 hot flushes were objectively assessed in a laboratory setting in 72 symptomatic postmenopausal women (aged 45.8 ± 5.1 years; body mass index 25.9 ± 4.5 kg/m) from five previously reported studies. Women rested, wearing a tube-lined suit (or trousers), which was perfused with 34C water. A subset then underwent mild heat stress (48°C water). Sweat rate, skin blood flow, blood pressure, heart rate, skin, and core temperature were measured continuously throughout. A hot flush was objectively identified during rest (spontaneous hot flush) or mild heating as an abrupt increase in sternal sweat rate. Further, a subset of symptomatic postmenopausal women (n = 22) underwent whole-body passive heating for 60 minutes to identify core temperature thresholds and sensitivities for sweat rate and cutaneous vasodilation, which were compared to a subset of premenopausal women (n = 18). Data were analyzed using t tests and/or general linear modeling, and are presented as mean (95% confidence interval). RESULTS In the 20 minutes before a spontaneous hot flush, core temperature increased by 0.03 ± 0.12C (P < 0.05), but only 51% of hot flushes were preceded by an increase in core temperature. During mild heating, 76% of hot flushes were preceded by an increase in core temperature. The temperature thresholds for sweating were similar, but the vasodilatory threshold was higher in postmenopausal compared with premenopausal women (37.1 ± 0.2 vs 36.8 ± 0.3°C; P = 0.06). CONCLUSION We provide new evidence that menopausal hot flushes are unlikely triggered by an increase in core temperature. These findings provide important information about the physiology of hot flushes that have implications for treatment and management options for menopausal hot flushes.
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Affiliation(s)
- Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, England
| | - Tom G Bailey
- Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Australia
| | - David A Barr
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, England
| | - Madeleine France
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, England
| | - Rebekah A I Lucas
- School of Sport, Exercise and Rehabilitative Sciences, University of Birmingham, Birmingham, UK
| | - Craig G Crandall
- Department of Internal Medicine, University of Texas Southwestern and Texas Health Presbyterian Hospital Dallas, TX
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, England
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Ruhe ZC, Subramanian P, Song K, Nguyen JY, Stevens TA, Low DA, Jensen GJ, Hayes CS. Programmed Secretion Arrest and Receptor-Triggered Toxin Export during Antibacterial Contact-Dependent Growth Inhibition. Cell 2019; 175:921-933.e14. [PMID: 30388452 DOI: 10.1016/j.cell.2018.10.033] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/31/2018] [Accepted: 09/05/2018] [Indexed: 12/21/2022]
Abstract
Contact-dependent growth inhibition (CDI) entails receptor-mediated delivery of CdiA-derived toxins into Gram-negative target bacteria. Using electron cryotomography, we show that each CdiA effector protein forms a filament extending ∼33 nm from the cell surface. Remarkably, the extracellular filament represents only the N-terminal half of the effector. A programmed secretion arrest sequesters the C-terminal half of CdiA, including the toxin domain, in the periplasm prior to target-cell recognition. Upon binding receptor, CdiA secretion resumes, and the periplasmic FHA-2 domain is transferred to the target-cell outer membrane. The C-terminal toxin region of CdiA then penetrates into the target-cell periplasm, where it is cleaved for subsequent translocation into the cytoplasm. Our findings suggest that the FHA-2 domain assembles into a transmembrane conduit for toxin transport into the periplasm of target bacteria. We propose that receptor-triggered secretion ensures that FHA-2 export is closely coordinated with integration into the target-cell outer membrane. VIDEO ABSTRACT.
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Affiliation(s)
- Zachary C Ruhe
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Poorna Subramanian
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kiho Song
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Josephine Y Nguyen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Taylor A Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - David A Low
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, Pasadena, CA 91125, USA.
| | - Christopher S Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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Hesketh K, Shepherd SO, Strauss JA, Low DA, Cooper RJ, Wagenmakers AJM, Cocks M. Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content. Am J Physiol Heart Circ Physiol 2019; 317:H114-H123. [PMID: 31074654 DOI: 10.1152/ajpheart.00816.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Passive heat therapy (PHT) has been proposed as an alternative intervention to moderate-intensity continuous training (MICT) in individuals who are unable or unwilling to exercise. This study aimed to make the first comparison of the effect of PHT and MICT on 1) skeletal muscle capillarization and endothelial-specific endothelial nitric oxide synthase (eNOS) content and 2) mitochondrial density, glucose transporter 4 (GLUT4), and intramuscular triglyceride (IMTG) content. Twenty young sedentary males (21 ± 1 yr, body mass index 25 ± 1 kg/m2) were allocated to either 6 wk of PHT (n = 10; 40-50 min at 40°C in a heat chamber, 3×/wk) or MICT (n = 10; time-matched cycling at ~65% V̇o2peak). Muscle biopsies were taken from the vastus lateralis muscle before and after training. Immunofluorescence microscopy was used to assess changes in skeletal muscle mitochondrial density (mitochondrial marker cytochrome c oxidase subunit 4), GLUT4, and IMTG content, capillarization, and endothelial-specific eNOS content. V̇o2peak and whole body insulin sensitivity were also assessed. PHT and MICT both increased capillary density (PHT 21%; MICT 12%), capillary-fiber perimeter exchange index (PHT 15%; MICT 12%) (P < 0.05), and endothelial-specific eNOS content (PHT 8%; MICT 12%) (P < 0.05). However, unlike MICT (mitochondrial density 40%; GLUT4 14%; IMTG content 70%) (P < 0.05), PHT did not increase mitochondrial density (11%, P = 0.443), GLUT4 (7%, P = 0.217), or IMTG content (1%, P = 0.957). Both interventions improved aerobic capacity (PHT 5%; MICT 7%) and whole body insulin sensitivity (PHT 15%; MICT 36%) (P < 0.05). Six-week PHT in young sedentary males increases skeletal muscle capillarization and eNOS content to a similar extent as MICT; however, unlike MICT, PHT does not affect skeletal muscle mitochondrial density, GLUT4, or IMTG content. NEW & NOTEWORTHY The effect of 6-wk passive heat therapy (PHT) compared with moderate-intensity continuous training (MICT) was investigated in young sedentary males. PHT induced similar increases in skeletal muscle capillarization and endothelial-specific endothelial nitric oxide synthase content to MICT. Unlike MICT, PHT did not improve skeletal muscle mitochondrial density, glucose transporter 4, or intramuscular triglyceride content. These microvascular adaptations were paralleled by improvements in V̇o2peak and insulin sensitivity, suggesting that microvascular adaptations may contribute to functional improvements following PHT.
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Affiliation(s)
- Katie Hesketh
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
| | - Sam O Shepherd
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
| | - Juliette A Strauss
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
| | - Robert J Cooper
- Institute of Aging and Chronic Disease, University of Liverpool , Liverpool , United Kingdom
| | - Anton J M Wagenmakers
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
| | - Matthew Cocks
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
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Chee G, O’Connell D, Yang YM, Singhrao K, Low DA, Lewis JH. McSART: an iterative model-based, motion-compensated SART algorithm for CBCT reconstruction. ACTA ACUST UNITED AC 2019; 64:095013. [DOI: 10.1088/1361-6560/ab07d6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Wagenmakers AJM, Hesketh K, Shepherd SO, Strauss JA, Low DA, Cooper RJ, Cocks M. Passive Heat Therapy in Sedentary Humans Improves Aerobic Capacity and Insulin Sensitivity via Increases in Skeletal Muscle Capillarisation and eNOS. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.701.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Anton JM Wagenmakers
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
| | - Katie Hesketh
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
| | - Sam O Shepherd
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
| | - Juliette A Strauss
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
| | - David A Low
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
| | - Robert J Cooper
- Institute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolUnited Kingdom
| | - Matthew Cocks
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLiverpoolUnited Kingdom
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Miyasato RS, Silva-Batista C, Peçanha T, Low DA, de Mello MT, Piemonte ME, Ugrinowitsch C, Forjaz CL, Kanegusuku H. Cardiovascular Responses During Resistance Exercise in Patients With Parkinson Disease. PM R 2018; 10:1145-1152. [DOI: 10.1016/j.pmrj.2018.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 04/17/2018] [Accepted: 04/27/2018] [Indexed: 11/30/2022]
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Michalska K, Quan Nhan D, Willett JLE, Stols LM, Eschenfeldt WH, Jones AM, Nguyen JY, Koskiniemi S, Low DA, Goulding CW, Joachimiak A, Hayes CS. Functional plasticity of antibacterial EndoU toxins. Mol Microbiol 2018; 109:509-527. [PMID: 29923643 PMCID: PMC6173971 DOI: 10.1111/mmi.14007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2018] [Indexed: 01/05/2023]
Abstract
Bacteria use several different secretion systems to deliver toxic EndoU ribonucleases into neighboring cells. Here, we present the first structure of a prokaryotic EndoU toxin in complex with its cognate immunity protein. The contact-dependent growth inhibition toxin CdiA-CTSTECO31 from Escherichia coli STEC_O31 adopts the eukaryotic EndoU fold and shares greatest structural homology with the nuclease domain of coronavirus Nsp15. The toxin contains a canonical His-His-Lys catalytic triad in the same arrangement as eukaryotic EndoU domains, but lacks the uridylate-specific ribonuclease activity that characterizes the superfamily. Comparative sequence analysis indicates that bacterial EndoU domains segregate into at least three major clades based on structural variations in the N-terminal subdomain. Representative EndoU nucleases from clades I and II degrade tRNA molecules with little specificity. In contrast, CdiA-CTSTECO31 and other clade III toxins are specific anticodon nucleases that cleave tRNAGlu between nucleotides C37 and m2 A38. These findings suggest that the EndoU fold is a versatile scaffold for the evolution of novel substrate specificities. Such functional plasticity may account for the widespread use of EndoU effectors by diverse inter-bacterial toxin delivery systems.
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Affiliation(s)
- Karolina Michalska
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL, USA
| | - Dinh Quan Nhan
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Julia L E Willett
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Lucy M Stols
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL, USA
| | - William H Eschenfeldt
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL, USA
| | - Allison M Jones
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Josephine Y Nguyen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - David A Low
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA.,Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
| | - Celia W Goulding
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA.,Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Christopher S Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA.,Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
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O'Connell D, Ruan D, Thomas DH, Dou TH, Lewis JH, Santhanam A, Lee P, Low DA. A prospective gating method to acquire a diverse set of free-breathing CT images for model-based 4DCT. Phys Med Biol 2018; 63:04NT03. [PMID: 29350191 DOI: 10.1088/1361-6560/aaa90f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Breathing motion modeling requires observation of tissues at sufficiently distinct respiratory states for proper 4D characterization. This work proposes a method to improve sampling of the breathing cycle with limited imaging dose. We designed and tested a prospective free-breathing acquisition protocol with a simulation using datasets from five patients imaged with a model-based 4DCT technique. Each dataset contained 25 free-breathing fast helical CT scans with simultaneous breathing surrogate measurements. Tissue displacements were measured using deformable image registration. A correspondence model related tissue displacement to the surrogate. Model residual was computed by comparing predicted displacements to image registration results. To determine a stopping criteria for the prospective protocol, i.e. when the breathing cycle had been sufficiently sampled, subsets of N scans where 5 ⩽ N ⩽ 9 were used to fit reduced models for each patient. A previously published metric was employed to describe the phase coverage, or 'spread', of the respiratory trajectories of each subset. Minimum phase coverage necessary to achieve mean model residual within 0.5 mm of the full 25-scan model was determined and used as the stopping criteria. Using the patient breathing traces, a prospective acquisition protocol was simulated. In all patients, phase coverage greater than the threshold necessary for model accuracy within 0.5 mm of the 25 scan model was achieved in six or fewer scans. The prospectively selected respiratory trajectories ranked in the (97.5 ± 4.2)th percentile among subsets of the originally sampled scans on average. Simulation results suggest that the proposed prospective method provides an effective means to sample the breathing cycle with limited free-breathing scans. One application of the method is to reduce the imaging dose of a previously published model-based 4DCT protocol to 25% of its original value while achieving mean model residual within 0.5 mm.
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Affiliation(s)
- D O'Connell
- Department of Radiation Oncology, University of California, Los Angeles, CA 90095, United States of America
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Atkinson CL, Carter HH, Thijssen DHJ, Birk GK, Cable NT, Low DA, Kerstens F, Meeuwis I, Dawson EA, Green DJ. Localised cutaneous microvascular adaptation to exercise training in humans. Eur J Appl Physiol 2018; 118:837-845. [DOI: 10.1007/s00421-018-3813-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 11/11/2017] [Indexed: 02/03/2023]
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Peçanha T, Forjaz CLDM, Low DA. Passive Heating Attenuates Post-exercise Cardiac Autonomic Recovery in Healthy Young Males. Front Neurosci 2017; 11:727. [PMID: 29311799 PMCID: PMC5742592 DOI: 10.3389/fnins.2017.00727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 12/13/2017] [Indexed: 11/13/2022] Open
Abstract
Post-exercise heart rate (HR) recovery (HRR) presents a biphasic pattern, which is mediated by parasympathetic reactivation and sympathetic withdrawal. Several mechanisms regulate these post-exercise autonomic responses and thermoregulation has been proposed to play an important role. The aim of this study was to test the effects of heat stress on HRR and HR variability (HRV) after aerobic exercise in healthy subjects. Twelve healthy males (25 ± 1 years, 23.8 ± 0.5 kg/m2) performed 14 min of moderate-intensity cycling exercise (40–60% HRreserve) followed by 5 min of loadless active recovery in two conditions: heat stress (HS) and normothermia (NT). In HS, subjects dressed in a whole-body water-perfused tube-lined suit to increase internal temperature (Tc) by ~1°C. In NT, subjects did not wear the suit. HR, core and skin temperatures (Tc and Tsk), mean arterial pressure (MAP) skin blood flow (SKBF), and cutaneous vascular conductance (CVC) were measured throughout and analyzed during post-exercise recovery. HRR was assessed through calculations of HR decay after 60 and 300 s of recovery (HRR60s and HRR300s), and the short- and long-term time constants of HRR (T30 and HRRt). Post-exercise HRV was examined via calculations of RMSSD (root mean square of successive RR intervals) and RMS (root mean square residual of RR intervals). The HS protocol promoted significant thermal stress and hemodynamic adjustments during the recovery (HS-NT differences: Tc = +0.7 ± 0.3°C; Tsk = +3.2 ± 1.5°C; MAP = −12 ± 14 mmHg; SKBF = +90 ± 80 a.u; CVC = +1.5 ± 1.3 a.u./mmHg). HRR and post-exercise HRV were significantly delayed in HS (e.g., HRR60s = 27 ± 9 vs. 44 ± 12 bpm, P < 0.01; HRR300s = 39 ± 12 vs. 59 ± 16 bpm, P < 0.01). The effects of heat stress (e.g., the HS-NT differences) on HRR were associated with its effects on thermal and hemodynamic responses. In conclusion, heat stress delays HRR, and this effect seems to be mediated by an attenuated parasympathetic reactivation and sympathetic withdrawal after exercise. In addition, the impact of heat stress on HRR is related to the magnitude of the heat stress-induced thermal stress and hemodynamic changes.
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Affiliation(s)
- Tiago Peçanha
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Cláudia L de Moraes Forjaz
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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Mawhinney C, Low DA, Jones H, Green DJ, Costello JT, Gregson W. Cold Water Mediates Greater Reductions in Limb Blood Flow than Whole Body Cryotherapy. Med Sci Sports Exerc 2017; 49:1252-1260. [PMID: 28141620 DOI: 10.1249/mss.0000000000001223] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Cold-water immersion (CWI) and whole body cryotherapy (WBC) are widely used recovery methods in an attempt to limit exercise-induced muscle damage, soreness, and functional deficits after strenuous exercise. The aim of this study was to compare the effects of ecologically valid CWI and WBC protocols on postexercise lower limb thermoregulatory, femoral artery, and cutaneous blood flow responses. METHODS Ten males completed a continuous cycle exercise protocol at 70% maximal oxygen uptake until a rectal temperature of 38°C was attained. Participants were then exposed to lower-body CWI (8°C) for 10 min, or WBC (-110°C) for 2 min, in a randomized crossover design. Rectal and thigh skin, deep, and superficial muscle temperatures, thigh, and calf skin blood flow (laser Doppler flowmetry), superficial femoral artery blood flow (duplex ultrasound), and arterial blood pressure were measured before, and for 40 min post, cooling interventions. RESULTS Greater reductions in thigh skin (CWI, -5.9°C ± 1.8°C; WBC, 0.2°C ± 0.5°C; P < 0.001) and superficial (CWI, -4.4°C ± 1.3°C; WBC, -1.8°C ± 1.1°C; P < 0.001) and deep (CWI, -2.9°C ± 0.8°C; WBC, -1.3°C ± 0.6°C; P < 0.001) muscle temperatures occurred immediately after CWI. Decreases in femoral artery conductance were greater after CWI (CWI, -84% ± 11%; WBC, -59% ± 21%, P < 0.02) and thigh (CWI, -80% ± 5%; WBC, -59% ± 14%, P < 0.001), and calf (CWI, -73% ± 13%; WBC, -45% ± 17%, P < 0.001) cutaneous vasoconstriction was greater after CWI. Reductions in rectal temperature were similar between conditions after cooling (CWI, -0.6°C ± 0.4°C; WBC, -0.6°C ± 0.3°C; P = 0.98). CONCLUSION Greater reductions in blood flow and tissue temperature were observed after CWI in comparison with WBC. These novel findings have practical and clinical implications for the use of cooling in the recovery from exercise and injury.
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Affiliation(s)
- Chris Mawhinney
- 1Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM; 2School of Sport Science, Exercise and Health, The University of Western Australia, Perth, AUSTRALIA; and 3Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UNITED KINGDOM
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Michalska K, Gucinski GC, Garza-Sánchez F, Johnson PM, Stols LM, Eschenfeldt WH, Babnigg G, Low DA, Goulding CW, Joachimiak A, Hayes CS. Structure of a novel antibacterial toxin that exploits elongation factor Tu to cleave specific transfer RNAs. Nucleic Acids Res 2017; 45:10306-10320. [PMID: 28973472 PMCID: PMC5737660 DOI: 10.1093/nar/gkx700] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/29/2017] [Indexed: 12/23/2022] Open
Abstract
Contact-dependent growth inhibition (CDI) is a mechanism of inter-cellular competition in which Gram-negative bacteria exchange polymorphic toxins using type V secretion systems. Here, we present structures of the CDI toxin from Escherichia coli NC101 in ternary complex with its cognate immunity protein and elongation factor Tu (EF-Tu). The toxin binds exclusively to domain 2 of EF-Tu, partially overlapping the site that interacts with the 3'-end of aminoacyl-tRNA (aa-tRNA). The toxin exerts a unique ribonuclease activity that cleaves the single-stranded 3'-end from tRNAs that contain guanine discriminator nucleotides. EF-Tu is required to support this tRNase activity in vitro, suggesting the toxin specifically cleaves substrate in the context of GTP·EF-Tu·aa-tRNA complexes. However, superimposition of the toxin domain onto previously solved GTP·EF-Tu·aa-tRNA structures reveals potential steric clashes with both aa-tRNA and the switch I region of EF-Tu. Further, the toxin induces conformational changes in EF-Tu, displacing a β-hairpin loop that forms a critical salt-bridge contact with the 3'-terminal adenylate of aa-tRNA. Together, these observations suggest that the toxin remodels GTP·EF-Tu·aa-tRNA complexes to free the 3'-end of aa-tRNA for entry into the nuclease active site.
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Affiliation(s)
- Karolina Michalska
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Grant C Gucinski
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA
| | - Fernando Garza-Sánchez
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
| | - Parker M Johnson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Lucy M Stols
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - William H Eschenfeldt
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Gyorgy Babnigg
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - David A Low
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
| | - Celia W Goulding
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.,Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Christopher S Hayes
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
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O’Connell D, Thomas DH, Dou TH, Aliotta E, Lewis JH, Lamb JM, Lee P, Low DA. Adaptive weighted median filtering for reduced blurring when fusing co-registered fast helical CT images. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa889d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kavi LA, Nuttall M, Low DA, Opie-Moran M, Nicholson LM, Caldow EJ, Kavi KS, Newton JL. 151A profile of a UK paediatric population with postural tachycardia syndrome. Europace 2017. [DOI: 10.1093/europace/eux283.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
This study assessed the additive effects of passive heating and exercise on cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV). Twelve healthy young men (25 ± 1 yr, 23.8 ± 0.5 kg/m2) randomly underwent two experimental sessions: heat stress (HS; whole body heat stress using a tube-lined suit to increase core temperature by ~1°C) and normothermia (NT). Each session was composed of a preintervention rest (REST1); HS or NT interventions; postintervention rest (REST2); and 14 min of cycling exercise [7 min at 40%HRreserve (EX1) and 7 min at 60%HRreserve (EX2)]. Heart rate and finger blood pressure were continuously recorded. cBRS was assessed using the sequence (cBRSSEQ) and transfer function (cBRSTF) methods. HRV was assessed using the indexes standard deviation of RR intervals (SDNN) and root mean square of successive RR intervals (RMSSD). cBRS and HRV were not different between sessions during EX1 and EX2 (i.e., matched heart rate conditions: EX1 = 116 ± 3 vs. 114 ± 3 and EX2 = 143 ± 4 vs. 142 ± 3 beats/min but different workloads: EX1 = 50 ± 9 vs. 114 ± 8 and EX2 = 106 ± 10 vs. 165 ± 8 W; for HS and NT, respectively; P < 0.01). However, when comparing EX1 of NT with EX2 of HS (i.e., matched workload conditions but with different heart rates), cBRS and HRV were significantly reduced in HS (cBRSSEQ = 1.6 ± 0.3 vs. 0.6 ± 0.1 ms/mmHg, P < 0.01; SDNN = 2.3 ± 0.1 vs. 1.3 ± 0.2 ms, P < 0.01). In conclusion, in conditions matched by HR, the addition of heat stress to exercise does not affect cBRS and HRV. Alternatively, in workload-matched conditions, the addition of heat to exercise results in reduced cBRS and HRV compared with exercise in normothermia. NEW & NOTEWORTHY The present study assessed cardiac baroreflex sensitivity during the combination of heat and exercise stresses. This is the first study to show that prior whole body passive heating reduces cardiac baroreflex sensitivity and autonomic modulation of heart rate during exercise. These findings contribute to the better understanding of the role of thermoregulation on cardiovascular regulation during exercise.
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Affiliation(s)
- Tiago Peçanha
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo , Sao Paulo , Brazil
| | - Cláudia L M Forjaz
- Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of Sao Paulo , Sao Paulo , Brazil
| | - David A Low
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University , Liverpool , United Kingdom
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