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Procedure: Ultrasound

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Total 63 results found since Jan 2013.

Cardiac stroke volume variability measured non-invasively by three methods for detection of central hypovolemia in healthy humans
ConclusionCardiac stroke volume estimated by ultrasound Doppler and by arterial blood pressure curve showed parallel variations beat-to-beat during simulated hemorrhage, whereas impedance cardiography did not appear to track beat-to-beat changes in cardiac stroke volume. The variability in cardiac stroke volume was decreased during mild and moderate hypovolemia and could be used for early detection of hypovolemia.
Source: European Journal of Applied Physiology - September 9, 2016 Category: Physiology Source Type: research

The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke
We quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post stroke) and nine controls participated. Throughout fatiguing contractions, the discharge timings of individual motor units were identified by decomposition of high-density surface EMG signals. After five consecutive contractions, a blood flow measurement through the femoral artery was obtained using an ultrasound machine and probe designed for vascular ...
Source: Frontiers in Physiology - May 9, 2019 Category: Physiology Source Type: research

Shear wave ultrasound elastography of the biceps brachii can be used as a precise proxy for passive elbow torque in individuals with hemiparetic stroke
Precise and objective methods for quantifying passive joint torques are absent in stroke rehabilitation, leaving rehabilitation specialists to subjectively assess its impact on function. Here, we compare shear wave ultrasound elastography of the biceps brachii muscle with a mechatronic method (criterion measure) of measuring elbow flexion torque over a range of elbow angles. Differences are evaluated between arms. Data support the clinical application of shear wave ultrasound elastography, especially in the absence of bedside mechatronics. AbstractMuscle tissue is prone to changes in composition and architecture following ...
Source: Physiological Reports - May 20, 2023 Category: Physiology Authors: Michael D. Ellis, Netta Gurari, Ninette T. A. Gerritsen, Sabrina M. Lee, Amy Wang, Julius P. A. Dewald Tags: ORIGINAL ARTICLE Source Type: research

Chronic Vagal Nerve Stimulation Prevents High-Salt Diet-Induced Endothelial Dysfunction and Aortic Stiffening in Stroke-Prone Spontaneously Hypertensive Rats.
In conclusion, chronic VNS prevents hypertension-induced endothelial dysfunction and aortic stiffening in an animal model of severe hypertension. We speculate that anti-inflammatory mechanisms may contribute to these effects. PMID: 27208157 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - May 19, 2016 Category: Physiology Authors: Chapleau MW, Rotella DL, Reho JJ, Rahmouni K, Stauss HM Tags: Am J Physiol Heart Circ Physiol Source Type: research

Ultrasound stimulates formation and release of vasoactive compounds in brain endothelial cells.
Abstract Stroke outcome is improved by therapeutic ultrasound. This benefit is presumed to be principally from ultrasound-mediated thrombolysis. We hypothesized that the therapeutic benefit of ultrasound in stroke may, in part, be mediated by release of beneficial vasoactive substances. Accordingly we investigated the effect of ultrasound on levels of cytochrome P450, lipoxygenase and cyclooxygenase metabolites of arachidonic acid as well as adenosine release and endothelial nitric oxide synthase (eNOS) phosphorylation in primary brain endothelial cells in-vitro. Brain endothelial cells were exposed to 1.05 MHz ul...
Source: American Journal of Physiology. Heart and Circulatory Physiology - June 19, 2015 Category: Physiology Authors: Davis CM, Ammi AY, Alkayed NJ, Kaul S Tags: Am J Physiol Heart Circ Physiol Source Type: research

Glutamate Transport and Preterm Brain Injury
Silvia Pregnolato1*, Elavazhagan Chakkarapani1, Anthony R. Isles2 and Karen Luyt1 1Department of Neonatal Neurology, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom 2Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom Preterm birth complications are the leading cause of child death worldwide and a top global health priority. Among the survivors, the risk of life-long disabilities is high, including cerebral palsy and impairment of movement, cognition, and beh...
Source: Frontiers in Physiology - April 23, 2019 Category: Physiology Source Type: research

Respiratory sinus arrhythmia stabilizes mean arterial blood pressure at high-frequency interval in healthy humans
Conclusions RSA magnitude is lower and mean arterial blood pressure variability is greater during IPPV than during metronome breathing. We conclude that in healthy humans, RSA stabilizes mean arterial blood pressure at respiratory frequency.
Source: European Journal of Applied Physiology - November 9, 2014 Category: Physiology Source Type: research

In vivo assessment of coronary flow and cardiac function after bolus adenosine injection in adenosine receptor knockout mice
In this study, we used ultrasound imaging to measure the in vivo effects of adenosine on coronary blood flow (left coronary artery) and cardiac function in anesthetized wild‐type, A1 knockout (KO), A2AKO, A2BKO, A3KO, A1, and A3 double KO (A1/3 DKO) and A2A and A2B double KO (A2A/2B DKO) mice in real time. Echocardiographic and Doppler studies were performed using a Visualsonic Vevo 2100 ultrasound system. Coronary blood flow (CBF) baseline data were obtained when animals were anesthetized with 1% isoflourane. Diameter (D) and velocity time integral (VTI) were measured on the left coronary arteries (CBF = ((π/4) ×...
Source: Physiological Reports - June 13, 2016 Category: Physiology Authors: Bunyen Teng, Stephen L. Tilley, Catherine Ledent, S. Jamal Mustafa Tags: Original Research Source Type: research

Age-Dependence of Flow Homeostasis in the Left Ventricle
Conclusions: In average, blood spends 1 to 3 beats inside the LV with very low shear stress rates. The apical region is the most prone to blood stasis, particularly in mid-aged adults. The washout of blood in the normal LV is age-dependent due to physiological changes in the degree of apical penetration of the filling waves. Introduction Cardioembolic stroke is a major source of mortality and disability worldwide and blood stasis one of its major determinants (Adams et al., 1986). Left ventricular (LV) function has evolved to maximize mechanical efficiency and ensure organ perfusion at a low cost of energy and fill...
Source: Frontiers in Physiology - April 25, 2019 Category: Physiology Source Type: research

Sex-specific association between inflammation and endothelial function relevant gene and vulnerable carotid plaque
Conclusion: The rs4845625 polymorphism in IL6R has sex-specific effects on vulnerable carotid plaque in Chinese Han high-risk individuals for stroke. Our findings provide a plausible genetic basis underlying the sex difference in carotid plaque vulnerability.
Source: Frontiers in Physiology - August 19, 2022 Category: Physiology Source Type: research

Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 meters
This article is protected by copyright. All rights reserved.PMID:36165275 | DOI:10.1113/JP283419
Source: The Journal of Physiology - September 27, 2022 Category: Physiology Authors: M G Rieger C M Tallon D R Perkins K J Smith M Stembridge S Piombo S Radom-Aizik D M Cooper P N Ainslie A M McManus Source Type: research

Cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia in humans.
Abstract We characterized the cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia. Ten healthy males participated under three experimental conditions: 1) hypercapnia (HCA, PetCO2: +10mmHg) induced by inhalation of a CO2-enriched gas mixture; 2) muscle metaboreflex activation (MMA) induced by 5 min of local circulatory occlusion following 1 min of 50% MVC isometric handgrip under normocapnia; and 3) HCA+MMA combination. We measured mean arterial pressure (MAP, finger photoplethysmography), heart rate (HR, electrocardiography) and cardiac output (CO, Doppler ultrasound); calculated ...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - April 22, 2015 Category: Physiology Authors: Delliaux S, Ichinose M, Watanabe K, Fujii N, Nishiyasu T Tags: Am J Physiol Regul Integr Comp Physiol Source Type: research

Acute effects of glucagon ‐like peptide‐1, GLP‐19–36 amide, and exenatide on mesenteric blood flow, cardiovascular parameters, and biomarkers in healthy volunteers
Abstract Glucagon‐like peptide‐1 (GLP‐1, GLP‐17–36amide) and its sister peptide glucagon‐like peptide 2 (GLP‐2) influence numerous intestinal functions and GLP‐2 greatly increases intestinal blood flow. We hypothesized that GLP‐1 also stimulates intestinal blood flow and that this would impact on the overall digestive and cardiovascular effects of the hormone. To investigate the influence of GLP‐1 receptor agonism on mesenteric and renal blood flow and cardiovascular parameters, we carried out a double‐blinded randomized clinical trial. A total of eight healthy volunteers received high physiological s...
Source: Physiological Reports - February 23, 2017 Category: Physiology Authors: Lasse Bremholm, Ulrik B. Andersen, Mads Hornum, Linda Hilsted, Simon Veedfald, Bolette Hartmann, Jens Juul Holst Tags: Original Research Source Type: research

Does gradual change in head positioning affect cerebrovascular physiology?
This study assessed the reproducibility of cerebral hemodynamic parameters before, during, and after a gradual change of head positioning in a nonstroke group. Despite significant transient changes in cerebral blood velocity (CBV) and other hemodynamic parameters, dynamic cerebral autoregulation (dCA) calculated over a 5‐min period was not affected by gradual changes in head positioning. These findings provide the necessary framework to study the effects of head positioning in patients with acute stroke and other conditions associated with cerebral or vascular perturbations.
Source: Physiological Reports - February 8, 2018 Category: Physiology Authors: Man Y. Lam, Victoria J. Haunton, Thompson G. Robinson, Ronney B. Panerai Tags: Original Research Source Type: research