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Cardiac physiology

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https://www.readbyqxmd.com/read/29141185/increased-cross-bridge-recruitment-contributes-to-transient-increase-in-force-generation-beyond-maximal-capacity-in-human-myocardium
#1
Nima Milani-Nejad, Jae-Hoon Chung, Benjamin D Canan, Vadim V Fedorov, Bryan A Whitson, Ahmet Kilic, Peter J Mohler, Paul M L Janssen
Cross-bridge attachment allows force generation to occur, and rate of tension redevelopment (ktr) is a commonly used index of cross-bridge cycling rate. Tension overshoots have been observed briefly after a slack-restretch ktr maneuver in various species of animal models and humans. In this study, we set out to determine the properties of these overshoots and their possible underlying mechanism. Utilizing human cardiac trabeculae, we have found that tension overshoots are temperature-dependent and that they do not occur at resting states...
November 12, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/29138472/functional-characterization-of-the-ucp1-associated-oxidative-phenotype-of-human-epicardial-adipose-tissue
#2
Kanta Chechi, Pierre Voisine, Patrick Mathieu, Mathieu Laplante, Sébastian Bonnet, Frédéric Picard, Philippe Joubert, Denis Richard
Brown fat presence and metabolic activity has been associated with lower body mass index, higher insulin sensitivity and better cardiometabolic profile in humans. We, and others, have previously reported the presence of Ucp1, a marker of brown adipocytes, in human epicardial adipose tissue (eAT). Characterization of the metabolic activity and associated physiological relevance of Ucp1 within eAT, however, is still awaited. Here, we validate the presence of Ucp1 within human eAT and its 'beige' nature. Using in-vitro analytical approaches, we further characterize its thermogenic potential and demonstrate that human eAT is capable of undergoing enhanced uncoupling respiration upon stimulation...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29137910/tamponade-hemodynamic-and-echocardiographic-diagnosis
#3
REVIEW
Mark J Kearns, Keith R Walley
Cardiac tamponade is a medical emergency that can be readily reversed with timely recognition and appropriate intervention. The clinical diagnosis of cardiac tamponade requires synthesis of a constellation of otherwise non-specific features, based on an understanding of the underlying pathophysiology. Whereas echocardiographic examination is a central component of diagnosis, alone it is insufficient to establish the physiologic diagnosis of hemodynamically significant cardiac tamponade. The hemodynamic diagnosis of cardiac tamponade requires clinical evidence of low cardiac output and stroke volume in the setting of elevated cardiac filling pressures, with evidence of increased sympathetic tone (tachycardia, peripheral vasoconstriction, etc), and exclusion of other causes of shock as the primary problem (particularly cardiogenic shock)...
November 11, 2017: Chest
https://www.readbyqxmd.com/read/29137484/the-role-of-endogenous-reactive-oxygen-species-in-cardiac-myocyte-autophagy
#4
J-P Wang, R-F Chi, J Liu, Y-Z Deng, X-B Han, F-Z Qin, B Li
Autophagy is implicated in the maintenance of cardiac homeostasis. Autophagy is activated in heart failure, in which reactive oxygen species (ROS) are increased. Exogenous ROS have been shown to induce cardiomyocyte autophagy alterations. However, little is known about the influences of physiological levels of endogenous ROS on cardiomyocyte autophagy. In the present study, we tested the hypothesis that endogenous ROS in cardiomyocytes play an important role in inducing autophagy. Cultured H9C2 cardiomyocytes or Sprague-Dawley rats were treated with the antioxidant N-acetyl-cysteine (NAC) or the superoxide dismutase mimic tempol under the basal or nutrient deprivation conditions...
November 10, 2017: Physiological Research
https://www.readbyqxmd.com/read/29137478/effects-of-increased-myocardial-tissue-concentration-of-myristic-palmitic-and-palmitoleic-acids-on-the-course-of-cardiac-atrophy-of-the-failing-heart-unloaded-by-heterotopic-transplantation
#5
M Pokorný, I Mrázová, J Malý, J Pirk, I Netuka, Z Vaňourková, Š DoleŽelová, L Červenková, H Maxová, V Melenovský, J Šochman, J Sadowski, L Červenka
The present experiments were performed to evaluate if increased heart tissue concentration of fatty acids, specifically myristic, palmitic and palmitoleic acids that are believed to promote physiological heart growth, can attenuate the progression of unloading-induced cardiac atrophy in rats with healthy and failing hearts. Heterotopic abdominal heart transplantation (HT(x)) was used as a model for heart unloading. Cardiac atrophy was assessed from the ratio of the native- to-transplanted heart weight (HW)...
November 10, 2017: Physiological Research
https://www.readbyqxmd.com/read/29137144/impact-of-labile-zinc-on-heart-function-from-physiology-to-pathophysiology
#6
REVIEW
Belma Turan, Erkan Tuncay
Zinc plays an important role in biological systems as bound and histochemically reactive labile Zn(2+). Although Zn(2+) concentration is in the nM range in cardiomyocytes at rest and increases dramatically under stimulation, very little is known about precise mechanisms controlling the intracellular distribution of Zn(2+) and its variations during cardiac function. Recent studies are focused on molecular and cellular aspects of labile Zn(2+) and its homeostasis in mammalian cells and growing evidence clarified the molecular mechanisms underlying Zn(2+)-diverse functions in the heart, leading to the discovery of novel physiological functions of labile Zn(2+) in parallel to the discovery of subcellular localization of Zn(2+)-transporters in cardiomyocytes...
November 12, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29135598/cardiac-arrest-in-the-operating-room-resuscitation-and-management-for-the-anesthesiologist-part-1
#7
Vivek K Moitra, Sharon Einav, Karl-Christian Thies, Mark E Nunnally, Andrea Gabrielli, Gerald A Maccioli, Guy Weinberg, Arna Banerjee, Kurt Ruetzler, Gregory Dobson, Matthew McEvoy, Michael F O'Connor
Cardiac arrest in the operating room and procedural areas has a different spectrum of causes (ie, hypovolemia, gas embolism, and hyperkalemia), and rapid and appropriate evaluation and management of these causes require modification of traditional cardiac arrest algorithms. There is a small but growing body of literature describing the incidence, causes, treatments, and outcomes of circulatory crisis and perioperative cardiac arrest. These events are almost always witnessed, frequently known, and involve rescuer providers with knowledge of the patient and their procedure...
November 10, 2017: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/29135467/univariate-and-multivariate-conditional-entropy-measures-for-the-characterization-of-short-term-cardiovascular-complexity-under-physiological-stress
#8
Martina Valente, Michal Javorka, Alberto Porta, Vlasta Bari, Jana Krohova, Barbora Czippelova, Zuzana Turianikova, Giandomenico Nollo, Luca Faes
A defining feature of physiological systems under the neuroautonomic regulation is their dynamical complexity. The most common approach to assess physiological complexity from short-term recordings, i.e. to compute the rate of entropy generation of an individual system by means of measures of conditional entropy (CE), does not consider that complexity may change when the investigated system is part of a network of physiological interactions. This study aims at extending the concept of short-term complexity towards the perspective of network physiology, defining multivariate CE measures whereby multiple physiological processes are accounted for in the computation of entropy rates...
November 14, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29133490/auscultation-while-standing-a-basic-and-reliable-method-to-rule-out-a-pathologic-heart-murmur-in-children
#9
Bruno Lefort, Elodie Cheyssac, Nathalie Soulé, Jacques Poinsot, Marie-Catherine Vaillant, Alaeddin Nassimi, Alain Chantepie
PURPOSE: The distinction between physiologic (innocent) and pathologic (organic) heart murmurs is not always easy in routine practice, leading too often to unnecessary cardiology referrals and expensive investigations. We aimed to test the hypothesis that the complete disappearance of murmur on standing can exclude cardiac disease in children. METHODS: From January 2014 to January 2015, we prospectively included 194 consecutive children aged 2 to 18 years who were referred for heart murmur evaluation to pediatric cardiologists at 2 French medical centers...
November 2017: Annals of Family Medicine
https://www.readbyqxmd.com/read/29133341/the-trafficking-protein-ehd2-positively-regulates-cardiac-sarcolemmal-katp-channel-surface-expression-role-in-cardioprotection
#10
Hua Qian Yang, Kundan Jana, Michael J Rindler, William A Coetzee
ATP-sensitive K(+) (KATP) channels uniquely link cellular energy metabolism to membrane excitability and are expressed in diverse cell types that range from the endocrine pancreas to neurons and smooth, skeletal, and cardiac muscle. A decrease in the surface expression of KATP channels has been linked to various disorders, including dysregulated insulin secretion, abnormal blood pressure, and impaired resistance to cardiac injury. In contrast, up-regulation of KATP channel surface expression may be protective, for example, by mediating the beneficial effect of ischemic preconditioning...
November 13, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/29132626/early-hospital-mortality-prediction-of-intensive-care-unit-patients-using-an-ensemble-learning-approach
#11
Aya Awad, Mohamed Bader-El-Den, James McNicholas, Jim Briggs
BACKGROUND: Mortality prediction of hospitalized patients is an important problem. Over the past few decades, several severity scoring systems and machine learning mortality prediction models have been developed for predicting hospital mortality. By contrast, early mortality prediction for intensive care unit patients remains an open challenge. Most research has focused on severity of illness scoring systems or data mining (DM) models designed for risk estimation at least 24 or 48h after ICU admission...
December 2017: International Journal of Medical Informatics
https://www.readbyqxmd.com/read/29131882/time-course-response-of-the-heart-and-circulatory-system-to-active-postural-changes
#12
Jo P Pauls, Llion Roberts, Tom Burgess, John/F Fraser, Shaun/D Gregory, Geoff Tansley
Rotary blood pumps (RBPs) used for mechanical circulatory support of heart failure patients cannot passively change pump flow sufficiently in response to frequent variations in preload induced by active postural changes. A physiological control system that mimics the response of the healthy heart is needed to adjust pump flow according to patient demand. Thus, baseline data is required on how the healthy heart (i.e. heart rate (HR) and cardiac output (CO)) and circulatory system (i.e. systemic vascular resistance (SVR)) respond...
November 13, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29131758/titin-gene-and-protein-functions-in-passive-and-active-muscle
#13
Wolfgang A Linke
The thin and thick filaments of muscle sarcomeres are interconnected by the giant protein titin, which is a scaffolding filament, signaling platform, and provider of passive tension and elasticity in myocytes. This review summarizes recent insight into the mechanisms behind how titin gene mutations cause hereditary cardiomyopathy and how titin protein is mechanically active in skeletal and cardiac myocytes. A main theme is the evolving role of titin as a modulator of contraction. Topics include strain-sensing via titin in the sarcomeric A-band as the basis for length-dependent activation, titin elastic recoil and refolding of titin domains as an energy source, and Ca(2+)-dependent stiffening of titin stretched during eccentric muscle contractions...
November 13, 2017: Annual Review of Physiology
https://www.readbyqxmd.com/read/29129433/nanoparticulate-specific-effects-of-silver-on-teleost-cardiac-contractility
#14
Neal Ingraham Callaghan, Kenneth Javier Williams, J Craig Bennett, Tyson James MacCormack
Silver nanoparticles (nAg), due to their biocidal properties, are common in medical applications and are used in more consumer products than any other engineered nanomaterial. This growing abundance, combined with their ability to translocate across the epithelium and bioaccumulate, suggests that internalized nAg may present a risk of toxicity to many organisms in the future. However, little experimentation has been devoted to cardiac responses to acute nAg exposure, even though nAg is known to disrupt ion channels even when ionic Ag(+) does not...
November 9, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29128608/a-retrospective-comparison-of-survivors-and-non-survivors-of-massive-pulmonary-embolism-receiving-veno-arterial-extracorporeal-membrane-oxygenation-support
#15
Bennet George, Marc Parazino, Hesham R Omar, George Davis, Maya Guglin, John Gurley, Susan Smyth
INTRODUCTION: While the optimal care of patients with massive pulmonary embolism (PE) is unclear, the general goal of therapy is to rapidly correct the physiologic derangements propagated by obstructive clot. Extracorporeal membrane oxygenation (ECMO) in this setting is promising, however the paucity of data limits its routine use. Our institution expanded the role of ECMO as an advanced therapy option in the initial management of massive PE. The purpose of this project was to evaluate ECMO-treated patients with massive PE at an academic medical center and report shortterm mortality outcomes...
November 8, 2017: Resuscitation
https://www.readbyqxmd.com/read/29128512/the-role-of-%C3%AE-ii-spectrin-in-cardiac-health-and-disease
#16
REVIEW
Mohamed H Derbala, Aaron S Guo, Peter J Mohler, Sakima A Smith
Spectrins are large, flexible proteins comprised of α-β dimers that are connected head-to-head to form the canonical heterotetrameric spectrin structure. Spectrins were initially believed to be exclusively found in human erythrocytic membrane and are highly conserved among different species. βII spectrin, the most common isoform of non-erythrocytic spectrin, is found in all nucleated cells and forms larger macromolecular complexes with ankyrins and actins. Not only is βII spectrin a central cytoskeletal scaffolding protein involved in preserving cell structure but it has also emerged as a critical protein required for distinct physiologic functions such as posttranslational localization of crucial membrane proteins and signal transduction...
November 8, 2017: Life Sciences
https://www.readbyqxmd.com/read/29127235/cardiac-performance-is-limited-by-oxygen-delivery-to-the-mitochondria-in-the-crystalloid-perfused-working-heart
#17
Sarah Kuzmiak-Glancy, Raul Covian, Armel N Femnou, Brian Glancy, Rafael Jaimes, Anastasia M Wengrowski, Kara Garrott, Stephanie French, Robert S Balaban, Matthew W Kay
The left ventricular (LV) working, crystalloid-perfused heart is used extensively to evaluate basic cardiac function, pathophysiology, and pharmacology. Crystalloid-perfused hearts may be limited by oxygen delivery, as adding oxygen carriers increases myoglobin oxygenation and improves myocardial function. However, whether decreased myoglobin oxygen saturation impacts oxidative phosphorylation (OxPhos) is unresolved since myoglobin has a much lower affinity for oxygen than cytochrome c oxidase (COX). In the present study, a laboratory-based synthesis of an affordable perfluorocarbon (PFC) emulsion was developed to increase perfusate oxygen-carrying capacity without impeding optical absorbance assessments...
November 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29127187/apobec2-deficiency-causes-mitochondrial-defects-and-mitophagy-in-skeletal-muscle
#18
Yusuke Sato, Hideaki Ohtsubo, Naohiro Nihei, Takane Kaneko, Yoriko Sato, Shin-Ichi Adachi, Shinji Kondo, Mako Nakamura, Wataru Mizunoya, Hiroshi Iida, Ryuichi Tatsumi, Cristina Rada, Fumiaki Yoshizawa
Apobec2 is a member of the activation-induced deaminase/apolipoprotein B mRNA editing enzyme catalytic polypeptide cytidine deaminase family expressed in differentiated skeletal and cardiac muscle. We previously reported that Apobec2 deficiency in mice leads to a shift in muscle fiber type, myopathy, and diminished muscle mass. However, the mechanisms of myopathy caused by Apobec2 deficiency and its physiologic functions are unclear. Here we show that, although Apobec2 localizes to the sarcomeric Z-lines in mouse tissue and cultured myotubes, the sarcomeric structure is not affected in Apobec2-deficient muscle...
November 10, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/29125447/multiple-echocardiography-abnormalities-associated-with-endoscopic-third-ventriculostomy-failure
#19
Ashish H Shah, George M Ibrahim, Jun Sasaki, John Ragheb, Sanjiv Bhatia, Toba N Niazi
OBJECTIVE Although endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) has gained increasing prominence in the management of hydrocephalus caused by intraventricular hemorrhage of prematurity, the rates of long-term shunt independence remain low. Furthermore, limited evidence is available to identify infants who might benefit from the procedure. The authors tested the hypothesis that elevated venous pressure that results from comorbid cardiac disease might predispose patients to ETV/CPC failure and shunt dependence...
November 10, 2017: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/29124742/lactate-improves-saps-3-prognostication
#20
P Andersson, A Frigyesi
INTRODUCTION: Lactate concentration is known to be a strong predictor of mortality, but is not included in any of the major intensive care scorings systems such as the Simplified Acute Physiology Score (SAPS 3). The objective of this study was to investigate the prognostic value of lactate concentration when combined with SAPS 3. MATERIALS AND METHODS: In the period of 2008 to June 2017 the general intensive care unit at Skåne University Hospital in Lund, Sweden had 5141 first-time admissions...
November 10, 2017: Acta Anaesthesiologica Scandinavica
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