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New Approaches in Cardiac Optical Mapping
Švrček, Martin ; Kizek, René (referee) ; Sovka, Pavel (referee) ; Provazník, Ivo (advisor)
This dissertation deals with new approaches in cardiac optical mapping. The principle of cardiac optical mapping as well as the current research in this field was described. The new measurement system was developed and its characteristics presented. The system design allows epicardial and endocardial mapping, employing new ratiometric techniques in 2D acquisition and simultaneous electrical and optical mapping. The measured characteristics of fluorescent dye di-4-ANEPPSS were presented. The relation between movement and consequent motion artifacts is well described. Several new approaches in signal processing were proposed, including new ratiometry technique and using image registration to suppress motion artifacts. The algorithm for elastic image registration of optical signals and innovative method for verification of registration process were presented. Application of all proposed approaches and its results are included and discussed.
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Current genomic and cytogenomic methods in analysis of chromosome rearrangements
Buryšová, Sára ; Sember, Alexandr (advisor) ; Mandáková, Terezie (referee)
Chromosome rearrangements represent one of the major mechanisms driving the eukaryotic genome evolution. They may significantly contribute to reproductive isolation and diversification, including the evolution of complex life-history traits linked e.g. with local adaptation. They are structural changes leading to alteration in the morphology and/or number of chromosomes, which can have a direct effect on the evolution of genes and their expression profiles, the frequency and distribution of recombination in the genome, and the functional dynamics of processes operating in the interphase nucleus. However, they may be also causal for etiology (or a consequence) of inherent diseases and tumorigenesis. The study of chromosome rearrangements and the mechanisms of their emergence is related to the identification and characterization of rearrangement breakpoints (i.e. where double-strand break occurred and chromosome segments subsequently rejoined). One possibility is to analyze chromosomes and interspecific changes in the arrangement of linkage groups/synteny blocks using cytogenetic and cytogenomic methods (e.g. cross-species mapping of whole-chromosome hybridization probes). More detailed insight is provided by comparative genomics, nowadays mainly represented by so-called third-generation methods (the...
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Effect of temperature on arrhythmogenesis during heart development
Vostárek, František ; Sedmera, David (advisor) ; Tomek, Viktor (referee) ; Naňka, Ondřej (referee)
5 Abstract: Aims: The main objective of this work was to analyze in detail the effects of acute temperature changes on the function of isolated chick embryonic heart in vitro in comparison with natural conditions in ovo. Methods: The effects of temperature change (34 řC, 37 řC and 40 řC - hypo-, normo- and hyperthermia, respectively) on calcium dynamics in four days old isolated chick hearts in vitro were investigated by high-speed calcium optical imaging. For comparison and validation of in vitro measurements, experiments were also performed in ovo using videomicroscopy. Artificial electrical stimulation experiments were performed in vitro and in ovo to uncover conduction limits of different heart segments. Results: We observed almost linear dependence of sinus frequency on temperature in our temperature range. Sinus frequency during hypothermia and hyperthermia in vitro and in ovo changed about 20% in comparison with normothermia. We observed no significant changes in amplitude of calcium transients during temperature change to hypothermia but hyperthermia caused a significant decrease in amplitude of calcium transients (atria 35%, ventricles 38%). We observed a wide spectrum of arrhythmias, which occurred spontaneously even during normothermia in vitro. Occurrence of arrhythmias in vitro significantly...
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Role of Nkx2.5 in development and electrophysiology of the mouse heart
Hámor, Peter ; Sedmera, David (advisor) ; Neckář, Jan (referee)
Role of Nkx2.5 in development and electrophysiology of the mouse heart Prague 2016 Peter Hámor, B.S. ABSTRACT The objective of this thesis is to investigate the role of Nkx2.5 gene dosage on electrophysiology of the mouse heart in prenatal stage of its development. The main goal of this work is to search for differences in conduction of electric impulses through the embryonic mouse hearts of different genotype. Special method of capturing the conduction of electric impulse through myocardium, called optical mapping, was used to visualize the electrical activity. Thanks to this method I was able to construct images and videos capturing the spread of the impulse with identification of the beginning of the activation and its direction in the heart. These outputs, or optical maps, help to define anomalies and defects in mutants compared with a normal functioning heart. The thesis focuses on the expression of the transcription factor Nkx2.5 and regulatory components related with the correct formation and physiology of the heart until 9.5 days post coitum. Embryos at this developmental stage were optically mapped and analysed according to their genotype. While the wild type and heterozygote mouse embryos exhibited high degree of similarity, the homozygous mutants were dramatically different. Considering this work...
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Mechanisms of conduction system development in vertebrates
Šaňková, Barbora ; Sedmera, David (advisor) ; Neckář, Jan (referee) ; Melenovský, Vojtěch (referee)
Group of specialized cells that form cardiac conduction system is responsible for generation and coordinated propagation of the electrical impulse in the heart. Changes in its development can be connected with arrhythmias; therefore, a good level of knowledge is necessary and relevant for basic science and clinical practice. For correct development of the conduction system are important genes coding gap junctions proteins, ion channels, transcription factors and other molecules involved in signaling cascades (endothelin, neuregulin). Development of conduction system is determined in addition to genetic factors also by epigenetics and environmental factors. This thesis with its individual papers on which it is based is addressing different aspects of conduction system development, which appears to be a complex process. Another feature which is linking all papers together, is the methodological approach enabling us to study function of the conduction system - optical mapping. In the first publication we studied by the means of in vitro organ culture the impact of work load without interfering hemodynamics on the conduction system maturation in the chick embryonic heart. The phenotype observed during experiments was developmental regression of conduction system maturation together with changes in...
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Effect of temperature on arrhythmogenesis during heart development
Vostárek, František
5 Abstract: Aims: The main objective of this work was to analyze in detail the effects of acute temperature changes on the function of isolated chick embryonic heart in vitro in comparison with natural conditions in ovo. Methods: The effects of temperature change (34 řC, 37 řC and 40 řC - hypo-, normo- and hyperthermia, respectively) on calcium dynamics in four days old isolated chick hearts in vitro were investigated by high-speed calcium optical imaging. For comparison and validation of in vitro measurements, experiments were also performed in ovo using videomicroscopy. Artificial electrical stimulation experiments were performed in vitro and in ovo to uncover conduction limits of different heart segments. Results: We observed almost linear dependence of sinus frequency on temperature in our temperature range. Sinus frequency during hypothermia and hyperthermia in vitro and in ovo changed about 20% in comparison with normothermia. We observed no significant changes in amplitude of calcium transients during temperature change to hypothermia but hyperthermia caused a significant decrease in amplitude of calcium transients (atria 35%, ventricles 38%). We observed a wide spectrum of arrhythmias, which occurred spontaneously even during normothermia in vitro. Occurrence of arrhythmias in vitro significantly...
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Effect of temperature on arrhythmogenesis during heart development
Vostárek, František
5 Abstract: Aims: The main objective of this work was to analyze in detail the effects of acute temperature changes on the function of isolated chick embryonic heart in vitro in comparison with natural conditions in ovo. Methods: The effects of temperature change (34 řC, 37 řC and 40 řC - hypo-, normo- and hyperthermia, respectively) on calcium dynamics in four days old isolated chick hearts in vitro were investigated by high-speed calcium optical imaging. For comparison and validation of in vitro measurements, experiments were also performed in ovo using videomicroscopy. Artificial electrical stimulation experiments were performed in vitro and in ovo to uncover conduction limits of different heart segments. Results: We observed almost linear dependence of sinus frequency on temperature in our temperature range. Sinus frequency during hypothermia and hyperthermia in vitro and in ovo changed about 20% in comparison with normothermia. We observed no significant changes in amplitude of calcium transients during temperature change to hypothermia but hyperthermia caused a significant decrease in amplitude of calcium transients (atria 35%, ventricles 38%). We observed a wide spectrum of arrhythmias, which occurred spontaneously even during normothermia in vitro. Occurrence of arrhythmias in vitro significantly...
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Effect of temperature on arrhythmogenesis during heart development
Vostárek, František ; Sedmera, David (advisor) ; Tomek, Viktor (referee) ; Naňka, Ondřej (referee)
5 Abstract: Aims: The main objective of this work was to analyze in detail the effects of acute temperature changes on the function of isolated chick embryonic heart in vitro in comparison with natural conditions in ovo. Methods: The effects of temperature change (34 řC, 37 řC and 40 řC - hypo-, normo- and hyperthermia, respectively) on calcium dynamics in four days old isolated chick hearts in vitro were investigated by high-speed calcium optical imaging. For comparison and validation of in vitro measurements, experiments were also performed in ovo using videomicroscopy. Artificial electrical stimulation experiments were performed in vitro and in ovo to uncover conduction limits of different heart segments. Results: We observed almost linear dependence of sinus frequency on temperature in our temperature range. Sinus frequency during hypothermia and hyperthermia in vitro and in ovo changed about 20% in comparison with normothermia. We observed no significant changes in amplitude of calcium transients during temperature change to hypothermia but hyperthermia caused a significant decrease in amplitude of calcium transients (atria 35%, ventricles 38%). We observed a wide spectrum of arrhythmias, which occurred spontaneously even during normothermia in vitro. Occurrence of arrhythmias in vitro significantly...
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Mechanisms of conduction system development in vertebrates
Šaňková, Barbora ; Sedmera, David (advisor) ; Neckář, Jan (referee) ; Melenovský, Vojtěch (referee)
Group of specialized cells that form cardiac conduction system is responsible for generation and coordinated propagation of the electrical impulse in the heart. Changes in its development can be connected with arrhythmias; therefore, a good level of knowledge is necessary and relevant for basic science and clinical practice. For correct development of the conduction system are important genes coding gap junctions proteins, ion channels, transcription factors and other molecules involved in signaling cascades (endothelin, neuregulin). Development of conduction system is determined in addition to genetic factors also by epigenetics and environmental factors. This thesis with its individual papers on which it is based is addressing different aspects of conduction system development, which appears to be a complex process. Another feature which is linking all papers together, is the methodological approach enabling us to study function of the conduction system - optical mapping. In the first publication we studied by the means of in vitro organ culture the impact of work load without interfering hemodynamics on the conduction system maturation in the chick embryonic heart. The phenotype observed during experiments was developmental regression of conduction system maturation together with changes in...
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Role of Nkx2.5 in development and electrophysiology of the mouse heart
Hámor, Peter ; Sedmera, David (advisor) ; Neckář, Jan (referee)
Role of Nkx2.5 in development and electrophysiology of the mouse heart Prague 2016 Peter Hámor, B.S. ABSTRACT The objective of this thesis is to investigate the role of Nkx2.5 gene dosage on electrophysiology of the mouse heart in prenatal stage of its development. The main goal of this work is to search for differences in conduction of electric impulses through the embryonic mouse hearts of different genotype. Special method of capturing the conduction of electric impulse through myocardium, called optical mapping, was used to visualize the electrical activity. Thanks to this method I was able to construct images and videos capturing the spread of the impulse with identification of the beginning of the activation and its direction in the heart. These outputs, or optical maps, help to define anomalies and defects in mutants compared with a normal functioning heart. The thesis focuses on the expression of the transcription factor Nkx2.5 and regulatory components related with the correct formation and physiology of the heart until 9.5 days post coitum. Embryos at this developmental stage were optically mapped and analysed according to their genotype. While the wild type and heterozygote mouse embryos exhibited high degree of similarity, the homozygous mutants were dramatically different. Considering this work...
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