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Dissertations / Theses on the topic 'Cardiovascular system'
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1
Chen, Chun-Cheng Richard 1977. "Automated cardiovascular system identification." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/81537.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 64-65).
by Chun-Cheng Chen.
S.B.and M.Eng.
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Ng, Kuen-to. "The gender difference and association between social position and cardiovascular risk factors in Hong Kong /." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38030354.
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Levick, Scott P. "Inflammation and cardiovascular remodelling /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19090.pdf.
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Getmans’ka, V. "Amyloidosis in the cardiovascular system." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45034.
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In the most industrialized countries with a high degree of urbanization (including Ukraine), the leading cause of morbidity and mortality is occupied by diseases of the cardiovascular system. Detection of amyloidosis is prognostically the most serious complication for patients with various diseases of the cardiovascular system, causes the development of functional organ failure and patient's death.
The aim of the work is a detailed study of amyloidosis problems, especially its etiology and pathogenesis.
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D'Arienzo, Maria Pia. "Cardiovascular System: Modelling and Optimization." Doctoral thesis, Universita degli studi di Salerno, 2016. http://hdl.handle.net/10556/2224.
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2014 - 2015A conservation law is a partial di_erential equation, in which the variable is a quantity which remains constant in time, that is it cannot be created and destroyed. Thanks to the conservation laws it is possible to de_ne models able to describe real systems in which something is stored. Fluid dynamic models, which are based on them, have a wide range of applications, because they can be used to describe blood ows, tra_c evolution on street networks of big cities or on motorways of big states, data ows on telecommunication networks, ows of goods on supply chains, electric networks, etc. ... [edited by author]
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Maa, Ming-Hokng 1977. "Alterations in cardiovascular regulation and function assessed using cardiovascular system identification." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86525.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 65-67).
by Ming-Hokng Maa.
S.B.and M.Eng.
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Williams, Maro R. I. 1974. "Dehydroepiandrosterone action in the cardiovascular system." Monash University, Dept. of Medicine, 2002. http://arrow.monash.edu.au/hdl/1959.1/7927.
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Vargas, JoseÌ Juan SuaÌrez. "Physical modelling of the cardiovascular system." Thesis, Lancaster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444643.
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Smith, Kirsten Elisabeth. "Carbohydrates, insulin and the cardiovascular system." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546513.
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Li, Wai-sum Rachel, and 李蕙琛. "Effects of abacavir on cardiovascular system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46330288.
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Maksuti, Elira. "Imaging and modeling the cardiovascular system." Doctoral thesis, KTH, Medicinsk bildteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196538.
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Understanding cardiac pumping function is crucial to guiding diagnosis, predicting outcomes of interventions, and designing medical devices that interact with the cardiovascular system. Computer simulations of hemodynamics can show how the complex cardiovascular system is influenced by changes in single or multiple parameters and can be used to test clinical hypotheses. In addition, methods for the quantification of important markers such as elevated arterial stiffness would help reduce the morbidity and mortality related to cardiovascular disease. The general aim of this thesis work was to improve understanding of cardiovascular physiology and develop new methods for assisting clinicians during diagnosis and follow-up of treatment in cardiovascular disease. Both computer simulations and medical imaging were used to reach this goal. In the first study, a cardiac model based on piston-like motions of the atrioventricular plane was developed. In the second study, the presence of the anatomical basis needed to generate hydraulic forces during diastole was assessed in heathy volunteers. In the third study, a previously validated lumped-parameter model was used to quantify the contribution of arterial and cardiac changes to blood pressure during aging. In the fourth study, in-house software that measures arterial stiffness by ultrasound shear wave elastography (SWE) was developed and validated against mechanical testing. The studies showed that longitudinal movements of the atrioventricular plane can well explain cardiac pumping and that the macroscopic geometry of the heart enables the generation of hydraulic forces that aid ventricular filling. Additionally, simulations showed that structural changes in both the heart and the arterial system contribute to the progression of blood pressure with age. Finally, the SWE technique was validated to accurately measure stiffness in arterial phantoms.QC 20161115
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Corrado, Cesare. "The cardiovascular system: a numerical study." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427527.
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The aim of this thesis concerns the mathematical and numerical study of the cardiovascular system. This work covers the three related main brances of study, dealing with artery modeling, valves modeling and heart modeling. The work is thus subdivided into three parts, each one dealing with a specific branch. In each part this work starts by a specific known in licterature problem and suggests original improvements aimed at obtaining a more accurate solution and/or a cheaper computational cost.
In the first part a new one dimensional model for the compliant vessels is proposed, capable of reproducing also the effects related to the fluid-structure interaction which are loosed by the classical models present in licterature. In particular it is show that with a cheaper modification it is possible to reproduce also in a one dimensional model the so called added mass effect, an effect related to the multidimensionality of the flow field as concerns the flows into compliant pipes.
In the same parts an analytical solution for the unsteady motion in an undefined rigid pipe is proposed, taking into account of the transitory effects. As far as the pulsating flow is concerned, the reference solution classically adopted in literature is represented by the Womersley one. Even though accourate, this latter allows the only study of the motion when the flow is fully developed; conversely it is not capable of reproducing what happens, for example, immediately after a sudden pressure drop. In this work a new solution capable of reproducing also the motion when not fully developed is proposed.
As far as applications is concerned, two particular cases are studied: the starting of an extracorporeal device (fluid initially at rest) and a double variation of pressure (non-homogeneus initial conditions), consisting of a sudden drop followed by a sudden raise (i. e., this is what happens during a fainting).
In the second part a stability estimate concerning the immersed finite elements method is reported. Up to now, in literautre the structural description is performed through linear piecewise continuous polinomial; in this work a new estimation is performed for a structural description performed by piecewise continuous polinomial of an arbitrary order, clearly comprehensive of the linear case.
Moreover, for the implicit case only, it is demonstrated that a stability limit from below exists for the time step size; even though not determinable. Numerical examples will enforce the results obtained.
A comparison between the ALE and the IFEM schemes is also performed for the simulation of an immersed structure. The results show that whenever the ALE computational cost increases proportionally to the structure displacement (as a consequence of the fluid mesh distorsion), the IFEM formulation does not depend on structure displacement.
The third part deals with the heart electro-mechanical coupling. The heart electrical activity is typically reproduced through the data obtained by the electro-cardiogram, a non-invasive medical device furnishing the graphical representation in time of the extracellular potential differences between different body locations. Up to now the study of the heart activity was performed by treating independently the electrophysiology and the mechanics, i.e. without considering a feedback between them. In this work the solution is determined by considering the electro-mechanical feedback, arising a non-linear fully coupled problem, being both solutions (electro physiology and mechanics) depending on each other. As a results a changing in the heart conductivity is present, affecting the electro-cardiogram graph in some terminations. Moreover different distributions between the problem solved with feedback and the one solved without for both the trans-membrane and the extracellular potentials are present.Lo scopo di questa tesi riguarda lo studio di matematico e numerico del sistema cardiovascolare. Questo lavoro comprende i tre rami principali correlati allo studio del sistema cardiovascolare, riguardanti la modellazione delle arterie, la modellazione valvole cardiache e la modellazione dell'elettromeccanica cardiaca. Il lavoro è suddiviso in tre parti, ognuna delle quali tratta un ramo specifico. In ogni parte questo lavoro il punto di partenza è rappresentato da un problema specifico e noto in letteratura; vengono quindi suggerite soluzioni originali finalizzate ad ottenere una soluzione più accurata e / o con un costo computazionale più conveniente. Nella prima parte viene proposto un nuovo modello monodimensionale per le arterie, in grado di riprodurre anche gli effetti legati all'interazione fluido-struttura, non presenti nei modelli classici presenti in letteratura. In particolare, si dimostra che con una modifica molto economica in termini computazionali è possibile riprodurre anche in un modello unidimensionale il cosiddetto effetto massa aggiunta, un effetto legato alla multidimensionalità del campo di moto quando si ha a che fare con condotti deformabili. Viene inoltre proposta una soluzione analitica per il moto a transitorio del flusso in un condotto rigido di lunghezza indefinita. Per quanto riguarda i flussi a regime periodico, la soluzione classica di riferimento adottata in letteratura è rappresentata dal flusso alla Womersley. Anche se precisa, quest'ultima consente solamente lo studio del moto quando il flusso è completamente sviluppato; al contrario, non è in grado di riprodurre ciò che accade, per esempio, subito dopo una variazione improvvisa di pressione. In questa tesi viene proposta una soluzione in grado di riprodurre anche il moto quando non è pienamente sviluppato. Dal punto di vista applicativo vengono studiati due casi particolari: l'avvio di un dispositivo di circolazione extra-corporea (fluido inizialmente a riposo) e una doppia variazione di pressione (condizioni iniziali non omogenee), costituita da un calo improvviso di pressione seguito da un ristabilirsi della pressione iniziale, come accade nei casi di svenimento. Nella seconda parte si determina una stima della stabilità relativamente al metodo degli elementi finiti immersi. Fino ad oggi, in letteratura la descrizione strutturale viene eseguita tramite polinomi continui lineari a tratti; in questo lavoro una nuova stima viene effettuata quando la struttura sia descritta da polinomi continui a tratti di ordine arbitrario, stima che chiaramente comprende come caso particolare quello dei polinomi lineari. Inoltre per il solo caso implicito, si dimostra che esiste anche un limite inferiore, anche se non determinabile esplicitamente, per l'incremento temporale, per avere stabilità dello schema numerico. Degli esempi numerici mostrano l'attendibilità dei risultati ottenuti. Si presenta inoltre un confronto fra i metodi ALE e IFEM per il caso della simulazione di una struttura immersa, come potrebbe essere una valvola cardiaca. I risultati hanno evidenziato che lo schema ALE presenta un costo di calcolo (in termini di sotto-iterazioni necessarie per arrivare a convergenza) proporzionale allo spostamento della struttura (come conseguenza della distorsione della griglia su cui viene risolto il moto del fluido), mentre la formulazione IFEM ne rimane indipendente. La terza parte si occupa dell'accoppiamento elettromeccanico dell'attività cardiaca. L'attività elettrica cardiaca viene in genere analizzata attraverso i dati ottenuti dalla elettro-cardiogramma, un dispositivo medico non invasivo capace di rappresentare graficamente l'andamento nel tempo delle differenze di potenziale extracellulare sussistente tra differenti posizioni del corpo. Fino ad oggi lo studio della attività cardiaca è stato effettuato trattando in maniera indipendente l'elettro-fisiologia e la meccanica, cioè senza considerare l'esistenza di un feedback tra di loro. In questo lavoro la soluzione viene determinata considerando il feedback elettro-meccanico, attraverso la soluzione di un problema non lineare completamente accoppiato, essendo entrambe le soluzioni (elettro fisiologia e meccanica) reciprocamente dipendenti. A causa del cambiamento del tensore conduttività, dovuto alla deformazione cardiaca, in alcune terminazioni dell'elettro-cardiogramma si riscontrano risultati differenti dal caso in cui si supponga il cuore fisso nello spazio. Inoltre, si sono riscontrate distribuzioni differenti tra il problema risolto con feedback e quello risolto senza feedback, sia per quanto concerne il potenziale trans-membranale, sia per quanto concerne il potenziale extracellulare.
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Leung, Yiu-por. "Coping strategies of cardiovascular disease patients." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19470125.
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Djietror, Godwin A. Elliott Susan J. "Towards an understanding of geographic variation in cardiovascular disease mortality and morbidity in Ontario, 1986--1994 /." *McMaster only, 2003.
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Barreto, Mitya M. "Application of dual-energy computed tomography to the evalution of coronary atherosclerotic plaque." Cleveland, Ohio : Cleveland State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1266528762.
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Thesis (D.Eng.)--Cleveland State University, 2009.Abstract. Title from PDF t.p. (viewed on Mar. 3, 2010). Includes bibliographical references (p. 150-170). Available online via the OhioLINK ETD Center and also available in print.
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Hsu, Anna. "Hydrogen sulphide (H2S) and the cardiovascular system." Thesis, King's College London (University of London), 2012. http://kclpure.kcl.ac.uk/portal/en/theses/hydrogen-sulphide-h2s-and-the-cardiovascular-system(53365106-ee0f-4a29-a626-c9f80e5cef80).html.
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Hydrogen sulfide (H2S) has relatively recently been added to a list of endogenously produced gaseous signalling molecules. Our understanding of the science of H2S has advanced rapidly in recent years as exemplified by the fact that within a mere 10 years a range of H2S releasing drugs have already been discovered and some indeed are entering clinical trials. However, the precise biological roles of endogenous H2S are not fully understood. In this respect, slow releasing H2S donors, such as GYY4137, have played a part in elucidating the complex roles of this gas in the body and are also beginning to show promise as possible therapeutics in inflammation - an area in which the function of H2S remains ambiguous. This thesis attempts to provide some additional clarity to the biological significance endogenous H2S. The first part of this work examines the release of endothelial cell derived H2S in vitro and the consequences of knocking out nitric oxide synthase on tissue H2S biosynthesis in mice. As part of this study, I show that the methods currently utilised to measure H2S are insufficiently sensitive/reliable to demonstrate the release of H2S synthesis from endothelial cells in vitro. In addition, data reported herein has demonstrated that knocking out endothelial cell nitric oxide synthase (eNOS) results in a presumably compensatory increase in tissue H2S synthesising activity associated with increased protein levels of the H2S synthesising enzyme, cystathionine-γ-lyase (CSE). The second part of this thesis examines the role of H2S in inflammation and provides further evidence for its anti-inflammatory activity both in vitro and in vivo. In addition, this thesis has shown the ‘added benefit’ of slow-releasing H2S donors (c.f. 3 conventional sulpide salt based donors) in that the H2S released from slow-releasing donors is sustained and does not instantaneously expose cells to potentially cytotoxic amounts of H2S. Identifying a need for additional slow releasing H2S donors attempts were made to examine the H2S releasing ability and antioxidant capacity of a library of additional compounds. As a result of this work, a novel compound, ZJ802 was shown to exhibit more potent antioxidant ability than the currently commercially available H2S donors and was further shown to exhibit anti-inflammatory activity both in vitro and in vivo. Overall, the roles of H2S in physiology are not clear. Current methods to detect H2S are flawed. Thus, the necessity for pharmacological tools, such as slow releasing H2S donors and selective H2S synthesising enzyme inhibitors, cannot be overemphasised. Whilst the possible use of H2S donors in the clinic has been raised there is still a need for more detailed preclinical, pharmacokinetic and long term drug safety and toxicological studies.
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Cho, Jinsoo. "Velocity-based cardiac segmentation and motion-tracking." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180106/unrestricted/cho%5Fjinsoo%5F200312%5Fphd.pdf.
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Davies, Robert J. O. "Sleep disordered breathing and the cardiovascular system." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404009.
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Hammer, Fabian. "Corticosteroid hormone action in the cardiovascular system." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1436/.
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The cardiovascular system (CVS) has emerged as an important target of corticosteroid hormones. Mineralocorticoid receptor antagonists provide cardiovascular protection and are now routinely used in disorders such as primary hyperaldosteronism, resistant hypertension and congestive heart failure (CHF) but the underlying molecular mechanisms of corticosteroid hormone action remain unclear. We have characterised corticosteroid hormone action and metabolism by 11β- hydroxysteroid-dehydrogenases (11β-HSDs) in isolated adult rat cardiomyocytes (CM) and cardiac fibroblasts (cFb). We have detected 11β-HSD1 expression and activity in CM and cFb where it facilitates glucocorticoid hormone action, whereas 11β-HSD2 was absent. We have shown differential gene regulation by aldosterone (Aldo) and corticosterone in CM and identified novel Aldo target genes which may provide insights into the molecular mechanisms of Aldo action. We have also studied the role of corticosteroids in essential hypertension and the effect of spironolactone (Spiro) upon their secretion and metabolism in patients with chronic kidney disease. We have shown that mineralocorticoids but not glucocorticoids are involved in elevated blood pressure in essential hypertension and that Spiro treatment results in compensatory activation of the renin-angiotensinaldosterone system (RAAS), whereas glucocorticoid secretion and metabolism remain unchanged. In summary, these data provide novel molecular and clinical insights into corticosteroid hormone action in the CVS.
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Schaible, Niccole Stephanie. "Minimum Entropy Generation in the Cardiovascular System." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29323.
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This study was performed under the motivation to find a scheme that could
describe the complex behavior of cardiovascular homeostasis. This is hypothesized to
be manifested in a thermodynamic description of the cardiovascular system (CVS).
Seen from a thermodynamic framework, the mechanics of blood flow can be gauged in
similar terms as metabolic exchange at the capillaries - thereby providing a holistic
and novel perspective on overall CVS function. Entropy generation, a thermodynamic calculation, represents lost work and is hypothesized to reveal something about the "optimal" state of the CVS. In particular, it is hypothesized that the CVS state that generates minimal entropy, given certain
constraints, will be physiologically preferred and that cardiovascular control operates
to find this state. This will be tested by first proposing a method to calculate entropy
generation in the CVS, and secondly characterizing entropy generation across unique
CVS states by simulation of a mathematical model.
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Gobin, Reeta Rukmini Devi. "Metabolic syndrome and cardiovascular disease." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610102.
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Wang, Lu Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Experimental investigation and mathematical modelling of human cardiovascular system during exercise." Awarded by:University of New South Wales. Electrical Engineering & Telecommunications, 2007. http://handle.unsw.edu.au/1959.4/40598.
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The hypothesis in this dissertation is that the mathematical and physiological models can be developed to estimate cardiac output and metabolic demand of exercising individual from simple non-invasive physiological parameters such as heart rate, respiration, working rate and body movement (using multiple triaxial accelerometers). The models developed could be incorporated as part of a closed loop control system for cardiac pacemaker and/or heart assist devices. A reliable measurement system has been developed to measure cardiac output, heart rate, body movement and respiratory variables and to process and analyze the data coming from the measurements. Analyzing, designing and modelling of the measurement system have also been conducted. The foremost is to model the mixing chamber based gas measurement system and the other is to analyze and compensate the orientation error of triaxial accelerometers on the assessment of energy expenditure. Two mathematical models and one physiological model have been developed in the current research. The first mathematical model is to estimate steady state energy expenditure using a nonlinear regression method from the outputs of triaxial accelerometers. Results show that the proposed nonlinear model is better than both the traditional linear models and the earlier nonlinear models. The second mathematical model emphasizes on investigating the key central cardiovascular response to the steady state of incremental exercise. The modeling results show that all the studied cardiovascular parameters response to exercise nonlinearly except heart rate which responses to exercise linearly. Furthermore, based on a previous model developed in the Biomedical Systems Laboratories in UNSW and the reliable experimental data, a physiological model has been established to successfully estimate both the cardiac output and the metabolic demand with heart rate and workload as its input.
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Saikus, Christina Elena. "Towards mri-guided cardiovascular interventions." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44912.
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Imaging guidance may allow minimally invasive alternatives to open surgical exposure and help reduce procedure risk and morbidity. The inherent vascular and soft-tissue contrast of MRI make it an appealing imaging modality to guide cardiovascular interventional procedures. Advances in real-time MRI have made MRI-guided procedures a realistic possibility. The MR environment, however, introduces additional challenges to the development of compatible, conspicuous and safe devices. The overall goal of this work was to enable selected MRI-guided cardiovascular interventional procedures with clearly visible MR devices. In the first part of this work, we developed actively visualized devices for three distinct MRI-guided interventional procedures and techniques to assess their signal performance. We then investigated factors influencing complex device safety in the MR environment and evaluated a technique to better determine and monitor potential device heating. This input contributed to the development of a system to further improve device safety with continual device monitoring and dynamic scanner feedback control. In the final part of this work, we demonstrated the utility of MRI guidance and actively visualized devices to enable traditional and complex cardiovascular access. Together these provide important elements to bring MRI-guided cardiovascular interventional procedures closer to clinical implementation.
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Hooper, Justin Shane. "Cardiovascular Effects Evoked by Airway Nociceptive Reflexes in Healthy and Cardiovascular Diseased Rats." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6258.
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Acute inhalation of airborne pollutants alters cardiovascular function and has been shown to have its greatest affects on individuals with pre-existing cardiovascular disease. Evidence suggests that pollutant-induced activation of airway sensory nerves via the gating of ion channels is critical to these systemic responses. Here, we have investigated the cardiovascular responses evoked by inhalation of AITC (TRPA1 agonist) and capsaicin (TRPV1 agonist) in healthy Sprague Dawley (SD) and Wistar Kyoto (WKY) rats, and cardiovascular diseased Spontaneously Hypertensive (SH) rats. Inhalation of the agonists by healthy SD and WKY rats caused significant bradycardia, atrio-ventricular (AV) block and prolonged PR-Intervals. Inhalation of TRP agonists caused differential cardiovascular responses in the cardiovascular diseased SH rats, such that the TRP agonists evoked brady-tachy with AV block and premature ventricular contractions (PVCs). Bradycardic responses to AITC were inhibited by the TRP channel blocker ruthenium red and the muscarinic antagonist atropine, but atropine did not prevent the tachycardic responses seen in the SH rats. Adrenergic inhibition with atenolol prevented the tachycardic responses, but did not prevent the bradycardic responses evoked by AITC in the SH rats. In healthy rats, AITC inhalation also caused a biphasic blood pressure response: a brief hypertensive phase followed by a hypotensive phase, while evoking hypertension in the SH rats. Atropine accentuated the hypertensive phase in all animals, while preventing the hypotension in the healthy animals. In all animals, AITC-evoked heart rate responses were not abolished by terazosin, the [U+F061]1 adrenoceptor inhibitor, which prevented the hypertensive responses. Anesthetics had profound effects on AITC-evoked bradycardia and AV block, which was abolished by urethane, ketamine and isoflurane. Nevertheless, AITC inhalation caused bradycardia and AV block in paralyzed and ventilated rats following pre-collicular decerebration. In conclusion, we provide evidence that activation of TRP channels expressed on nociceptive airway sensory nerves causes significant cardiovascular effects in healthy rats via reflex modulation of the autonomic nervous system (ANS), and that these effects are exacerbated in cardiovascular diseased rats.
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Willeit, Peter. "Natriuretic peptides and cardiovascular disease." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648533.
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Lau, Kui-kai Gary. "Surrogate markers of atherosclerosis and cardiovascular disease." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40733749.
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McCain, Wilfred C. "Cardiovascular components of organophosphorus-induced delayed neuropathy." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41691.
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The focus of this study was to assess the cardiovascular effects in hens of a single 2.5 mg/kg intramuscular injection of phenyl saligenin phosphate (PSP) into the breast muscle. Parameters were measured at 1, 3, 7, and 20 days post treatment. All hens developed clinical signs of delayed neuropathy by day 10 and these signs were maximal by day 20. Alterations of measured parameters were observed prior to the onset of clinical signs of organophosphorus-induced delayed neuropathy (OPIDN) (days 1, 3, and 7) as well as when maximal clinical signs were evident (days 15-21). Significant decreases in the activities of brain NTE and plasma cholinesterase as well as decreases in weight and the level of pcO2 and an increase in peripheral resistance were observed prior to evidence of clinical signs of OPIDN. When maximal signs of OPIDN were present, brain NTE and plasma cholinesterase were at control levels but brain cholinesterase was significantly increased. Significant decreases in body weight and arterial pCO2 and significant increases in limb venous flow, arterial blood pressure, and hematocrit were seen at this time.Master of Science
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Vedantham, Srinivasan. "Design and characterization of a high-resolution cardiovascular imager." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0607102-164425.
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Thesis (Ph. D.)--Worcester Polytechnic Institute.Keywords: Detector design and characterization; modulation transfer function; digital fluoroscopy. Includes bibliographical references (p. 150-160).
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Selby, Nicholas Michael. "The haemodynamic and cardiovascular effects of dialysis." Thesis, University of Nottingham, 2007. http://eprints.nottingham.ac.uk/10311/.
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Patients on dialysis are subject to hugely elevated rates of cardiovascular mortality. This thesis describes research work focusing on the large scale haemodynamic changes that occur during dialysis and how they may negatively impact on the cardiovascular system. Our results show that the haemodynamic disturbances that occur during haemodialysis are of sufficient magnitude to cause left ventricular (LV) regional wall motion abnormalities, reflecting subclinical myocardial ischaemia (myocardial stunning). This is pertinent as in non-dialysis patients repeated episodes of myocardial stunning lead to chronic heart failure, and in dialysis patients the presence of LV dysfunction dramatically increases the risk of death. We also explore how the haemodynamic effects of dialysis and the genesis of LV regional wall motion abnormalities can be ameliorated by using various interventions comprising of biofeedback dialysis (Hemocontrol and Diacontrol), cooling the dialysate and acetate free paired haemodiafiltration (PHF). We also examine the haemodynamic and metabolic effects of peritoneal dialysis (both continuous ambulatory and automated peritoneal dialysis) and show that these are much greater than previously thought. We also investigate possible mechanisms underlying these changes, namely alterations in cardiac filling and systemic glucose absorption leading to hyperinsulinaemia, and go on to examine the differential effects of the commercially available peritoneal dialysis solutions. Finally, we examine whether regional LV function is affected by the haemodynamic changes of CAPD.
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劉巨基 and Kui-kai Gary Lau. "Surrogate markers of atherosclerosis and cardiovascular disease." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40733749.
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Kors, Deborah Joy. "Does social support reduce cardiovascular stress reactivity only if you want support: a test of a match/mismatch hypothesis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0032/NQ38917.pdf.
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Alganga, Husam S. F. "Effect of hypoxia on the cardiovascular sphingolipid system." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8517/.
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Sphingosine kinase 1 (SK1) catalyses the synthesis of the important bioactive sphingolipid sphingosine-1-phosphate (S1P), that has an important role in vascular tone regulation and cardioprotection against ischaemia/reperfusion injury. The work presented in this thesis describes the influence of short periods of hypoxia on expression of SK1 in vascular endothelium and how this may regulate vascular function. The aims were achieved by using wire myography to study vascular function and confocal microscopy for the studies of expression and distribution of SK1 under normoxic and hypoxic conditions. In the first study, it was found that exposure of isolated rat coronary artery to a short period of hypoxia increases SK1 expression and ser225 phosphorylation. It was also demonstrated that the hypoxia-induced increase in SK1 expression was reduced by pre-treatment with cycloheximide, a protein synthesis inhibitor, SKi, a non-selective SK inhibitor and PF543, a selective SK1 inhibitor. However, pre-treatment with proteasomal and/or lysosomal inhibitors did not increase SK1 expression under normoxia or hypoxia. Similarity, SK1 expression was also increased in aortic endothelium following exposure to short-term hypoxia and this effect was also inhibited by cycloheximide, SKi and PF543. Collectively, these data suggest that hypoxia increases SK1 synthesis in coronary and aortic endothelium. Moreover, the SKi-induced reduction in SK1 expression in coronary endothelium was reversed by proteasomal and/or lysosomal inhibitors, indicating that SKi stimulates both proteasomal and lysosomal degradation of SK1 under normoxia and hypoxia. In chapter two, it was demonstrated that S1P and CYM5541, an S1P3 agonist, induced dose-dependent relaxation in endothelium-intact aortic rings, whereas the S1P1 agonist SEW2871 was without effect. The S1P stimulated relaxation was significantly enhanced in endothelium-intact aortic rings subjected to short-term hypoxia and this effect was entirely endothelium-dependent. Interestingly, the vasorelaxation response to S1P was inhibited by pre-treatment with SKi and PF543 but not ROMe, a selective SK2 inhibitor under both normoxia and hypoxia. A nitric oxide synthase inhibitor also inhibited the S1P-induced relaxation in aortic rings. Moreover, the enhanced relaxation response to S1P due to hypoxia was maintained in aortae obtained from spontaneously hypertensive Wistar Kyoto rats. These findings suggest that the vasorelaxation response to S1P under normoxia and the enhanced response under hypoxia are mediated by SK1 and NO. In chapter five, it was found that hypoxia did not change the SK1b expression in HUVECs and pre-treatment with SKi or cycloheximide exerted no effect under both normoxia and hypoxia. However, proteasomal and/or lysosomal inhibitors increased SK1 expression under hypoxic conditions. In heart tissue, no significant difference was seen in expression of SK1 following exposure to hypoxia. However, SK1 expression was reduced by pre-treatment with SK inhibitors and cycloheximide under normoxia but not hypoxia. SK1a was identified in heart tissue, which is more sensitive to the degradation-induced by SK inhibitors than SK1b. In summary, the results of this study imply that short-term hypoxia induces an increase in SK1 expression in coronary and aortic vascular endothelium. The increased SK1 induced by hypoxia appears to mediate the enhanced vasorelaxation response to S1P in endothelium-intact aortae. In HUVECs and heart tissue, it is likely that hypoxia induces resistance of SK1 to SK inhibitor-induced downregulation through a compensatory increase in SK1 expression.
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Wall, Jason A. "Mechanisms of mitogen activated kinase kinase 6 mediated cardioprotection /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3185930.
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Kebbel, Andrew D. "Development of cardiovascular nanodevices for the detection of vulnerable plaque." Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1185478006.
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Welsh, Paul. "Inflammatory markers as novel predictors of cardiovascular disease." Connect to e-thesis, 2008. http://theses.gla.ac.uk/86/.
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Thesis (Ph.D.) - University of Glasgow, 2008.Ph.D. thesis submitted to the Division of Cardiovascular and Medical Sciences, Faculty of Medicine, University of Glasgow, 2008. Includes bibliographical references. Print version also available.
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Snyder, Kristi Karin. "Einsteinian perspectives thermal therapies in cardiovascular model systems /." Diss., Online access via UMI:, 2004.
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Loke, Wai Mun. "Cardiovascular protective effects of dietary polyphenols." University of Western Australia. School of Biomedical and Chemical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0051.
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Polyphenols are naturally-occurring phytochemicals, which form an integral part of the human diet. Results from epidemiological studies have associated polyphenol intake with reduced risk of cardiovascular diseases. Previous human intervention studies suggested that dietary polyphenols exert their cardioprotective effects through their antioxidant and anti-inflammatory effects. While most in vitro experiments have not accounted for the bioavailability and metabolism of these polyphenols, our work has provided direct evidence, using quercetin, that metabolic transformation, together with bioavailability, exert profound effects on bioactivity. We examined the effect of quercetin and its major metabolites on the production of pro-inflammatory eicosanoids by human leukocytes. Studies comparing free radical scavenging, antioxidant activity and eicosanoid production demonstrate that there are different structural requirements for antioxidant and anti-inflammatory activity. We also investigated the effect of metabolic transformation on flavonoid bioactivity by comparing the activity of quercetin and its major metabolites to inhibit inflammatory eicosanoid production from human leukocytes. Quercetin was a potent inhibitor of leukotriene B4 formation in leukocytes (IC50 ~ 2µM), and its activity was dependent on specific structural features, particularly the 2,3 double bond of the C ring. Functionalisation of the 3'-OH group with either methyl or sulfate reduced inhibitory activity up to 50% while a glucuronide substituent at the 3-OH effectively removed the leukotriene B4 inhibitory activity. The major quercetin metabolite quercetin-3'-O-sulfate retained considerable lipoxygenase inhibitory activity (IC50 ~ 7 µM) while quercetin-3-O-glucuronide maintained antioxidant activity but had no lipoxygenase inhibitory activity at physiologically relevant concentrations. We conclude that structural modification of quercetin due to metabolic transformation had a profound effect on bioactivity, and that the structural features required for antioxidant activity of 8 quercetin and related flavonoids were unrelated to those required for inhibition of inflammatory eicosanoids.
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Leung, Yiu-por, and 梁耀波. "Coping strategies of cardiovascular disease patients." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31978125.
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Lo, Carman, and 盧嘉雯. "Effects of antiretroviral drugs on the vascular system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197117.
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The introduction of antiretroviral drugs has dramatically increased the lifespan of human immunodeficiency virus (HIV)-infected patients, shifting the major concern towards long-term morbidity and mortality, particularly an increased risk of cardiovascular complications. Antiretroviral therapy has been proposed to be one of the contributing factors. However, existing evidence for the role of antiretroviral therapy in the development of cardiovascular diseases is controversial. Therefore, in the present thesis, the effects of several antiretroviral drugs on the vascular system were investigated.
In view of the contribution of vascular inflammation in the development of cardiovascular diseases, the first study examined the effects of acute treatment of efavirenz, indinavir, saquinavir, lopinavir and ritonavir on the release of major inflammatory markers, interleukin (IL)-8, soluble intercellular adhesion molecule 1 (ICAM-1) and monocyte adhesion molecule 1 (MCP-1) in human umbilical vein endothelial cells in the absence or presence of lipopolysaccharide, a pro-inflammatory stimulus. The results demonstrated that efavirenz and the combination of lopinavir and ritonavir, at concentrations present in human plasma, reduced the IL-8 release, but not that of soluble ICAM-1 and MCP-1 in endothelial cells exposed to lipopolysaccharide. The data, therefore, suggest that efavirenz and lopinavir plus ritonavir may possibly have anti-inflammatory effects. Since these findings seems to contradict with the increased incidence of cardiovascular diseases associated with antiretroviral therapy, in vivo experiments were performed to further characterized the effects of antiretroviral drugs on the cardiovascular system.
In the second study, the atherogenic effects of long-term treatment (eight weeks) with efavirenz, abacavir and lamivudine, alone or in combination (as used clinically), were investigated in apolipoprotein E deficient (Apo-E-/-) mice (hyperlipidemic/atherosclerotic model) and the corresponding wild-type mice of both genders. All drug treatments had no effects on the lipid profile, nitrotyrosine expression in the liver (an indication of oxidative stress) and the degree of atherosclerotic lesions in all mice. Efavirenz and lamivudine did not have any significant effects on acetylcholine- and sodium nitroprusside-induced relaxations in all mice. Abacavir and the combination of the three drugs did not have any effects on acetylcholine-induced relaxation in aortae of wild-type mice, but impaired acetylcholine-induced relaxation in those of male Apo-E-/- mice without affecting sodium nitroprusside-induced relaxation. The reduction in relaxation was likely mediated by the cyclooxygenase pathway since indomethacin restored the reduction in relaxation. In male Apo-E-/- mice, IL-6 levels were increased by abacavir and the combined treatment, whereas serum amyloid P component (SAP) levels remained unchanged. Although no differences in the development of atherosclerotic lesions were observed, female Apo-E-/- mice receiving abacavir had better lipid profiles, no impairment in acetylcholine-induced relaxation and decreased serum IL-6 and SAP levels compared to male Apo-E-/- mice, revealing a vasculoprotective role of the female gender.
In conclusion, the data suggest that certain, but not all, antiretroviral drugs may increase the risk of cardiovascular diseases, and that this risk may be exacerbated in hyperlipidemia but reduced in females. Antiretroviral drugs should be cautiously prescribed to HIV-infected patients to minimize cardiovascular adverse effects.published_or_final_version
Pharmacology and Pharmacy
Master
Master of Philosophy
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Hedrick, Michael Scott. "Aspects of cardiovascular oxygen transport in vertebrates." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3404.
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The hematological and rheological characteristics of blood from a number of vertebrates was compared to assess possible species differences in blood viscosity that may influence cardiovascular oxygen transport. Nucleated red blood cells (RBCs) were more viscous (measured by cone-plate viscometry) in comparison with enucleate (mammalian) RBCs at hematocrits greater than 40% when measured at equivalent temperatures. The lower viscosity of enucleate RBCs is attributed to an enhanced deformability of enucleate cells in comparison to nucleated cells.
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Chan, Hiu-ting, and 陳曉庭. "The effect of diet intake on vascular function and therapeutic effect of cardiovascular medicine in patients with cardiovascular disease." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50434342.
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Cardiovascular diseases (CVDs) remain to be the leading causes of morbidity and mortality in Hong Kong and worldwide. Among different modifiable risk factors, dietary pattern is on the major determinant for CVD and overall mortality. Other than pharmacological therapies for cardiovascular risk factors, such as hypertension, hyperlipidemia and diabetes, maintaining a healthy diet is a more sustainable method in general population to prevent CVDs. Current lifestyle intervention in the West countries focus on high intake of fruit and vegetables with more than 400g per day and limited saturated fats with less than 10% of energy, there is very limited data on impact of dietary pattern on CVDs in Chinese. Prior studies among Chinese in Hong Kong have shown that only half of the local population fell within these recommended ranges for fat, saturated fatty acid and cholesterol intakes.
Several different dietary patterns have been recommended for CVDs prevention based on: i) food groups, such as Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet; ii) macronutrients: the low-carbohydrate diet, low glycemic index diet, very-low- fat diet and iii) nutrition or vitamin supplement. However, the effect of different dietary patterns based on modulations of food group, macronutrients and particular micronutrients on vascular structure and function in Chinese subjects is unclear. In the first part of this thesis, the relationships between different dietary pattern and surrogate markers of subclinical atherosclerosis and vascular function in different high risk populations for CVDs were investigated.
In Chapter 3, we compared the assessment of dietary pattern in Chinese using different tool, including Food Frequency Questionnaire (FFQ); Dietary Record; and Dietitian assessment. In this study, we demonstrated that suitable dietary assessments tools should be chosen for the assessment of different dietary pattern, according to characteristics of assessments.
In Chapter 4, the relationship between the fruit intake and subclinical atherosclerosis as measured by carotid intimal thickness (IMT) was investigated in patient with type II diabetes mellitus (DM). Our results showed that high fruit intake was associated with lower burden of carotid atherosclerosis, independent of level of vitamin intake in patients with type II DM.
In Chapter 5, we compared the impact of high carbohydrate diet on arterial stiffness between control subjects without CVDs and patients with high risk for CVDs. Our findings showed that high carbohydrate diet mainly affected patients with established CVDs, and their increased arterial stiffness was associated with an elevation of blood pressure.
In Chapter 6, we determined the effect of dietary vitamin intake on oxidative stress in patients with high risk of CVDs. In those high risk patients for CVDs, we demonstrated that increased dietary intake of vitamin A, beta-carotene and alpha tocopherol were associated with decreased oxidative stress, but these relationships were not observed in those control subjects without CVDs. It is likely attributed to the higher systemic oxidative stress levels in patients with high risk of CVDs.
On the other hand, food intake may also affect the clinical efficacy of cardiovascular therapies. In particularly, it has been well established that herbal intake which is commonly used by Chinese can affect the anticoagulant effect of warfarin on patients with non-valvular atrial fibrillation (AF). Thus, in this second part of the thesis, we investigated the effect of concomitant herbal intake on anticoagulation control in patients with non-valvular AF treated with warfarin. Our results showed that patients with AF treated with warfarin had limited knowledge on potential interaction between herbal substances in foods and warfarin, in which increased herbal substances intake significantly reduced the percentage time of anticoagulant effect within the therapeutic range. Moreover, a single section of education on knowledge of herbal ingredients did not improve their percentage time of therapeutic range for these patients.
In conclusion, these findings suggest that dietary pattern in Chinese might have significant impact of vascular function in patients with type II DM and high risk for CVDs. Moreover, the herbal substances in the diet among Chinese could have significant impact of the therapeutic effects in some of the cardiovascular medications, such as warfarin. Future clinical studies will be needed to confirm these potential beneficial effects of particular diet intake on vascular function in patients with high risks of CVDs as well as potential interaction between herbal substances in Chinese diet and cardiovascular medications.published_or_final_version
Medicine
Doctoral
Doctor of Philosophy
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Dong, Rumei. "Modeling of the cardiovascular system with integrated finite elemant and electrical analog methods /." View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/fullcit/3239905.
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Assomull, Ravi Gulab. "Cardiovascular magnetic resonance in dilated cardiomyopathy." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607644.
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Wang, Angela Yee-Moon Medicine UNSW. "Cardiovascular risk in long-term peritoneal dialysis patients." Awarded by:University of New South Wales. Medicine, 2005. http://handle.unsw.edu.au/1959.4/23050.
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Cardiovascular disease is responsible for at least half of all deaths in end-stage renal disease patients on maintenance dialysis and is attributed to the very high prevalence of left ventricular hypertrophy and dysfunction, cardiac failure, coronary artery disease and other atherosclerotic complications. Apart from traditional risk factors such as smoking, hypertension, diabetes and dyslipidemia, these patients are at risk of accelerated atherosclerosis and other cardiovascular complications as a result of non-traditional risk factors such as inflammation, anemia, increased oxidative stress, hyperparathyroidism and excessive calcium phosphorus load. In recent years, there is an increasing recognition of calcification complications in patients on dialysis. However, the importance and prognostic value of calcification in patients on peritoneal dialysis is not known. Residual renal function has a significant contribution to the overall survival in patients on peritoneal dialysis but whether it is in any way related to cardiovascular death and complications in patients on peritoneal dialysis is not known. Inflammation is highly prevalent in dialysis patients and is considered to play a pathogenic role in cardiovascular disease. In this thesis, we evaluated some of these relatively novel factors that may predispose peritoneal dialysis patients to an increased risk of cardiovascular complications and mortality, including calcification, loss of residual renal function and inflammation. A number of important conclusions were drawn from these studies. First, valvular calcification is a marker of atherosclerosis and shows important associations with malnutrition and inflammation and is an important predictor of mortality and cardiovascular deaths in peritoneal dialysis patients. Second, inflammation, as denoted by either C-reactive protein or vascular cell adhesion molecule-1 shows an important association with residual renal function and cardiac hypertrophy and is associated with mortality and cardiovascular risk in peritoneal dialysis patients. Third, loss of residual renal function is an important cardiovascular risk and combines adversely with C-reactive protein and cardiac hypertrophy to increase cardiovascular mortality in peritoneal dialysis patients. Fourth, resting hypermetabolism and the malnutrition, inflammation and atherosclerosis syndrome are associated phenomena that parallel the decline of residual renal function and predict an increased mortality and cardiovascular death in peritoneal dialysis patients.
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Barker, Ann Elizabeth. "Wild Blueberry Consumption and Risks for Cardiovascular Disease." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/BarkerAE2006.pdf.
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Kwape, Lemogang Daniel. "Diet and cardiovascular disease risk factors in Botswana." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211324.
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Cardiovascular disease (CVD) is the leading cause of mortality and morbidity worldwide. In Sub-Saharan Africa, rates of CVD are increasing rapidly, but there is little evidence about the potential determinants of CVD risk in this population. This thesis investigated CVD risk factors in Gaborone, capital city of Botswana, by (i) documenting CVD risk factors in this population, (ii) investigating the association between diet and CVD risk factors and (iii) assessing the association between diet and risk of CVD. 787 adults were recruited. Of these 566 were generally “healthy” with no history of CVD, while 221 (“diseased”) had at least one reported CVD condition, hypertension or diabetes. The median (interquartile range) age was 27 (23, 32) and 52 (42, 62) years for healthy and diseased participants respectively. All participants completed an interview administered questionnaire, including a food frequency questionnaire. Height, weight, waist circumference and blood pressure were measured, and a non-fasting blood sample was obtained for analysis of lipids, lipoproteins and glucose. A high prevalence of overweight and obesity (36.8%), particularly in women (50.0%), and low HDL cholesterol (<1.0 mmol/L men and <1.3 mmol/L women) (62.6%) was found. High levels of triglycerides, LDL cholesterol, glucose and high blood pressure were also found in this population of young adults in Gaborone. Total fat and/or saturated fat intake (as percentage energy) was significantly linearly associated with increased LDL cholesterol (p=0.017), triglycerides (p=0.048), glucose (p=0.044) and with decreased HDL cholesterol (p=0.021). However, fibre, polyunsaturated fatty acids and dietary patterns were not independently associated with CVD risk factors. Carbohydrates intake was significantly associated with increased risk of disease. Unexpectedly, saturated fat intake was associated with reduced disease risk, but weakened after nutrients adjustment. CVD risk factors are relatively high in this population. These results suggest a need for further research on CVD in Botswana.
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Norton, Cynthia Ann. "The Effect of Whole Wild Blueberries on Endothelial Function of the Sprague-Dawley Rat as Related to Cardiovascular Disease." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/NortonCA2003.pdf.
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Wang, Siqi. "NONINVASIVE ASSESSMENT AND MODELING OF DIABETIC CARDIOVASCULAR AUTONOMIC NEUROPATHY." UKnowledge, 2012. http://uknowledge.uky.edu/cbme_etds/5.
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Noninvasive assessment of diabetic cardiovascular autonomic neuropathy (AN): Cardiac and vascular dysfunctions resulting from AN are complications of diabetes, often undiagnosed. Our objectives were to: 1) determine sympathetic and parasympathetic components of compromised blood pressure regulation in patients with polyneuropathy, and 2) rank noninvasive indexes for their sensitivity in diagnosing AN. Continuous 12-lead electrocardiography (ECG), blood pressure (BP), respiration, regional blood flow and bio-impedance were recorded from 12 able-bodied subjects (AB), 7 diabetics without (D0), 7 with possible (D1) and 8 with definite polyneuropathy (D2), during 10 minutes supine control, 30 minutes 70-degree head-up tilt and 5 minutes supine recovery. During the first 3 minutes of tilt, systolic BP decreased in D2 while increased in AB. Parasympathetic control of heart rate, baroreflex sensitivity, and baroreflex effectiveness and sympathetic control of heart rate and vasomotion were reduced in D2, compared with AB. Baroreflex effectiveness index was identified as the most sensitive index to discriminate diabetic AN.
Four-dimensional multiscale modeling of ECG indexes of diabetic autonomic neuropathy: QT interval prolongation which predicts long-term mortality in diabetics with AN, is well known. The mechanism of QT interval prolongation is still unknown, but correlation of regional sympathetic denervation of the heart (revealed by cardiac imaging) with QT interval in 12-lead ECG has been proposed. The goal of this study is to 1) reproduce QT interval prolongation seen in diabetics, and 2) develop a computer model to link QT interval prolongation to regional cardiac sympathetic denervation at the cellular level. From the 12-lead ECG acquired in the study above, heart rate-corrected QT interval (QTc) was computed and a reduced ionic whole heart mathematical model was constructed. Twelve-lead ECG was produced as a forward solution from an equivalent cardiac source. Different patterns of regional denervation in cardiac images of diabetic patients guided the simulation of pathological changes. Minimum QTc interval of lateral leads tended to be longer in D2 than in AB. Prolonging action potential duration in the basal septal region in the model produced ECG and QT interval similar to that of D2 subjects, suggesting sympathetic denervation in this region in patients with definite neuropathy.
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Ostertag, Luisa Martha. "The impact of dietary polyphenols on human platelets : integrating functional and nutrigenomic analyses." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=185749.
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This thesis aims to integrate functional and nutrigenomics analyses to examine how dietary polyphenols affect human platelet function and thus may contribute to the prevention of cardiovascular diseases. Initially, 26 low molecular weight phenolic compounds were screened for their effects on platelet aggregation and P-selectin expression in vitro. Only high, non-physiological concentrations of some phenolics showed anti-platelet effects. In parallel we conducted a systematic review of the literature to assess how polyphenol-rich foodstuffs, beverages, or extracts affect platelet function in humans. Cocoa-derived flavan-3-ols were the only class of dietary polyphenols that consistently showed anti-platelet effects in both, acute and chronic settings. Consequently we conducted an acute randomised-controlled human intervention study in which healthy volunteers consumed three different types of chocolates containing different amounts of flavan-3-ols. We found that flavan-3-ol-enriched dark chocolate beneficially affected ex vivo bleeding time, platelet aggregation and P-selectin expression. These effects were gender-dependent. Bioavailability of cocoa-derived flavan-3-ols, as assessed by a targeted metabolomics approach, was also gender-dependent. Using a platelet proteomics approach, we found subtle changes in platelet protein levels 2 h after consumption of flavan-3-ol-enriched chocolate in men, which may partly explain the observed anti-platelet effects. Finally, we assessed whether flavan-3-ols are internalised in platelets after consumption of dark chocolate. No internalisation could be found up to 2.5 h after chocolate ingestion, despite these compounds appearing in plasma. In conclusion, flavan- 3-ol-enriched dark chocolate beneficially affects platelet function in a gender-dependent way, but underpinning mechanisms are still unknown. Furthermore, current insights into their bioavailability cannot fully explain the ability of flavan-3-ols to affect platelet function. Successful future progress of research into the bioavailability and mechanisms of flavan-3- ols in vitro and in vivo will depend on the availability of pure standards for the major human metabolites of flavan-3-ols.
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Mo, Yee-yan. "Effects of dietary soy isoflavones for cardiovascular disease (Review)." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42997525.
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