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Barnes SJK, Bjerkan J, Clemson PT, Newman J, Stefanovska A. Phase coherence-A time-localized approach to studying interactions. CHAOS (WOODBURY, N.Y.) 2024; 34:073155. [PMID: 39052926 DOI: 10.1063/5.0202865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 06/13/2024] [Indexed: 07/27/2024]
Abstract
Coherence measures the similarity of progression of phases between oscillations or waves. When applied to multi-scale, nonstationary dynamics with time-varying amplitudes and frequencies, high values of coherence provide a useful indication of interactions, which might otherwise go unnoticed. However, the choice of analyzing coherence based on phases and amplitudes (amplitude-weighted phase coherence) vs only phases (phase coherence) has long been seen as arbitrary. Here, we review the concept of coherence and focus on time-localized methods of analysis, considering both phase coherence and amplitude-weighted phase coherence. We discuss the importance of using time-localized analysis and illustrate the methods and their practicalities on both numerically modeled and real time-series. The results show that phase coherence is more robust than amplitude-weighted phase coherence to both noise perturbations and movement artifacts. The results also have wider implications for the analysis of real data and the interpretation of physical systems.
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Affiliation(s)
- S J K Barnes
- Physics Department, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - J Bjerkan
- Physics Department, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - P T Clemson
- Physics Department, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - J Newman
- Department of Mathematics and Statistics, University of Exeter, Exeter, United Kingdom
| | - A Stefanovska
- Physics Department, Lancaster University, Lancaster LA1 4YB, United Kingdom
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2
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Serov D, Tankanag A, Astashev M. Low-frequency oscillations of murine skin microcirculations and periodic changes of [Ca 2+ ] i and [NO] i levels in murine endotheliocytes: An effect of provocative tests. Cell Biol Int 2021; 46:427-442. [PMID: 34882893 DOI: 10.1002/cbin.11743] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/07/2021] [Accepted: 12/04/2021] [Indexed: 01/14/2023]
Abstract
The five frequency intervals of skin blood oscillation were described: cardiac, respiratory, myogenic, neurogenic, and endothelial. The endothelial interval is derived into NO-independent and NO-dependent. The exact molecular, cell, or systemic mechanisms of endothelial oscillations generation are unclear. We proposed that oscillations of Ca2+ and NO in endotheliocytes may be possible sources of skin blood perfusion (SBP) oscillations in endothelial interval. To examine our hypothesis we compared the oscillations of cytoplasmic Ca2+ and NO ([Ca2+ ]i and [NO]i ) concentration in cultured murine microvascular endotheliocytes and SBP oscillations in mice. Local heating test and model hypoxia were used as tools to evaluate an interconnection of studied parameters. [Ca2+ ]i and [NO]i were measured simultaneously by Fura-2 AM and DAF-FM. The SBP was measured by laser Doppler flowmetry. The [Ca2+ ]i and [NO]i oscillations at 0.005-0.01 Hz were observed in endotheliocytes, that coincides the ranges of NO-independent endothelial interval. Heating decreased amplitude of [Ca2+ ]i and [NO]i oscillations in cells in NO-independent endothelial interval, while amplitudes of SBP oscillations increased in NO-independent and NO-dependent intervals. Hypoxia reduced the [NO]i oscillations amplitude. Heating test during hypoxia increased NO-independent endothelial SBP oscillations and decreased myogenic ones, did not effect on [NO]i oscillations, and shifted [Ca2+ ]i oscillations peak from 0.005-0.01 Hz to 0.01-0.018 Hz. We observed the [Ca2+ ]i and [NO]i oscillations synchronization within a cell and between cells for the first time. Heating abolished these synchronizations. Therefore low-frequency [Ca2+ ]i and [NO]i oscillations in endotheliocytes may be considered as modulators of low-frequency endothelial SBP oscillations.
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Affiliation(s)
- Dmitriy Serov
- Institute of Cell Biophisics, Russian Academy of Sciences, Laboratory of Cellular Neurobiology, Pushchino, Moscow region, Russia.,Prokhorov General Physics Institute of the Russian Academy of Sciences, Biophotonics Center, Moscow, Russia
| | - Arina Tankanag
- Institute of Cell Biophisics, Russian Academy of Sciences, Laboratory of Cellular Neurobiology, Pushchino, Moscow region, Russia
| | - Maksim Astashev
- Institute of Cell Biophisics, Russian Academy of Sciences, Laboratory of Cellular Neurobiology, Pushchino, Moscow region, Russia.,Prokhorov General Physics Institute of the Russian Academy of Sciences, Biophotonics Center, Moscow, Russia
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Palacios J, Benites J, Owen GI, Morales P, Chiong M, Nwokocha CR, Paredes A, Cifuentes F. Impact of the Potential Antitumor Agent 2-(4-Hydroxyphenyl) Amino-1,4-Naphthoquinone (Q7) on Vasomotion Is Mediated by the Vascular Endothelium, But Not Vascular Smooth Muscle Cell Metabolism. J Cardiovasc Pharmacol 2021; 77:245-252. [PMID: 33105322 DOI: 10.1097/fjc.0000000000000940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 10/13/2020] [Indexed: 12/25/2022]
Abstract
ABSTRACT Vasomotion is defined as rhythmic oscillations in arterial diameter that regulate the blood flow and blood pressure. Because antitumor treatment may impair vascular functions and increase the blood pressure, we sought to evaluate whether a new naphthoquinone derivative, postulated as an antitumor agent, manifests adverse effects on vascular function. In this article, we evaluated the toxicity of 2-(4-hydroxyphenyl) amino-1,4-naphthoquinone (Q7) and its effects on vascular vasomotion in 3 models of vascular structure: endothelial cells, aortic ring, and smooth muscle cells. Although showing nontoxic effects, Q7 inhibited the formation of capillary-like structures of the EA.hy926 endothelial cell line grown on Matrigel. In exvivo experiments with aortic rings precontracted with phenylephrine (PE, 10-6 M), Q7 (10-5 M) significantly (P < 0.05) reduced vascular rhythmic contractions induced by the acetylcholine (ACh; 10-7-10-5 M), whereas sodium nitroprusside (a nitric oxide donor; 10-8 M) recovered the vasomotion. Furthermore, Q7 (10-5 M) did not decrease KCl-induced vascular rhythmic contractions in the aortic rings precontracted with BaCl2 (a nonselective K+ channel blocker; 10-3 M). Vascular smooth muscle cells (A7r5) preincubated with Q7 (10-5 M) for 3 hours also demonstrated a reduced glucose uptake. However, the Adenosine Triphosphate content was unaffected, suggesting that the rapid reduction in vasomotion observed in vascular reactivity experiments did not involve cellular metabolism but may be due to faster mechanisms involving endothelial nitric oxide and K+ channels leading to oscillations in intracellular Ca2+. In summary, the naphthoquinone derivative Q7 presents low cytotoxicity yet may alter the endothelial cell response and vasomotion in the absence of changes in smooth muscle cell metabolism.
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Affiliation(s)
- Javier Palacios
- Departamento de Química y Farmacia, Facultad Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile
| | - Julio Benites
- Departamento de Química y Farmacia, Facultad Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile
| | - Gareth I Owen
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Advanced Center for Chronic Diseases, ACCDiS, CEMC, Department of Biochemistry and Molecular Biology, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile
| | - Pablo Morales
- Advanced Center for Chronic Diseases, ACCDiS, CEMC, Department of Biochemistry and Molecular Biology, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile
| | - Mario Chiong
- Advanced Center for Chronic Diseases, ACCDiS, CEMC, Department of Biochemistry and Molecular Biology, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile
| | - Chukwuemeka R Nwokocha
- Department of Basic Medical Sciences Physiology Section, Faculty of Medical Sciences, The University of the West Indies, Mona, Kingston, Jamaica
| | - Adrián Paredes
- Departamento de Química, Facultad de Ciencias Básicas, Universidad de Antofagasta, Antofagasta, Chile; and
| | - Fredi Cifuentes
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
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Dudele A, Rasmussen PM, Østergaard L. Sural Nerve Perfusion in Mice. Front Neurosci 2020; 14:579373. [PMID: 33362454 PMCID: PMC7758475 DOI: 10.3389/fnins.2020.579373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/09/2020] [Indexed: 11/13/2022] Open
Abstract
Peripheral nerve function is metabolically demanding and nerve energy failure has been implicated in the onset and development of diabetic peripheral neuropathy and neuropathic pain conditions. Distal peripheral nerve oxygen supply relies on the distribution of red blood cells (RBCs) in just a few, nearby capillary-sized vessels and is therefore technically challenging to characterize. We developed an approach to characterize distal sural nerve hemodynamics in anesthetized, adult male mice using in vivo two-photon laser scanning microscopy. Our results show that RBC velocities in mouse sural nerve vessels are higher than those previously measured in mouse brain, and are sensitive to hindlimb temperatures. Nerve blood flow, measured as RBC flux, however, was similar to that of mouse brain and unaffected by local temperature. Power spectral density analysis of fluctuations in RBC velocities over short time intervals suggest that the technique is sufficiently sensitive and robust to detect subtle flow oscillations over time scales from 0.1 to tens of seconds. We conclude that in vivo two-photon laser scanning microscopy provides a suitable approach to study peripheral nerve hemodynamics in mice, and that local temperature control is important during such measurements.
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Affiliation(s)
- Anete Dudele
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,The International Diabetic Neuropathy Consortium, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Mondrup Rasmussen
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,The International Diabetic Neuropathy Consortium, Aarhus University Hospital, Aarhus, Denmark.,Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
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A novel MRI analysis for assessment of microvascular vasomodulation in low-perfusion skeletal muscle. Sci Rep 2020; 10:4705. [PMID: 32170106 PMCID: PMC7070083 DOI: 10.1038/s41598-020-61682-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/02/2020] [Indexed: 11/24/2022] Open
Abstract
Compromised microvascular reactivity underlies many conditions and injuries, but its assessment remains difficult, particularly in low perfusion tissues. In this paper, we develop a new mathematical model for the assessment of vasomodulation in low perfusion settings. A first-order model was developed to approximate changes in T1 relaxation times as a result of vasomodulation. Healthy adult rats (N = 6) were imaged on a 3-Tesla clinical MRI scanner, and vasoactive response was probed on gadofosveset using hypercapnic gases at 20% and 5% CO2 to induce vasoconstriction and vasodilation, respectively. MRI included dynamic 3D T1 mapping and T1-weighted images during gas challenge; heart rate was continuously monitored. Laser Doppler perfusion measurements were performed to corroborate MRI findings. The model was able to identify hypercapnia-mediated vasoconstriction and vasodilation through the partial derivative \documentclass[12pt]{minimal}
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\begin{document}$$\frac{\partial {T}_{1}}{\partial t}$$\end{document}∂T1∂t. MRI on animals revealed gradual vasoconstriction in the skeletal muscle bed in response to 20% CO2 followed by gradual vasodilation on transitioning to 5% CO2. These trends were confirmed on laser Doppler perfusion measurements. Our new mathematical model has the potential for detecting microvascular dysfunction that manifests in the early stages across multiple metabolic and ischemic pathologies.
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