Succinate is one of the intermediate in the Krebs cycle, which in recent years has been shown to interfere with other cellular events, some of which may affect cardiac ischemic tolerance. The aim of this project was to clarify its cardioprotective role in rat hearts subjected to acute ischemia-reperfusion. The myocardial resistance to acute ischemia (infarct size and incidence and severity of ischemic and reperfusion arrhythmias) was analyzed using the Langendorff method of isolated perfused heart at a constant flow with acute succinate administration. Local ischemia was induced by ligation of left anterior descending coronary artery. Acute administration of 1 mM succinate before 60 minutes of ischemia or before reperfusion only had a beneficial effect on reducing the infarct size by 25-30 % compared to the control group. At the same time, it had an adverse effect on the incidence and severity of ischemic and reperfusion arrhythmias. Key words: Succinate, heart, rat, heart-attack, ventricular arrhythmias

In adult heart, pressure overload leads to cardiac hypertrophy. Higher propensity of hypertrophied myocardium to life-threatening arrhythmia is attributed to structural, mechanical and electrical remodeling. Pro-arrhythmogenic remodeling comprise several factors depending on an experimental model and a stage of heart failure. This thesis aims to characterize the impact of these factors in our unique model of pressure overloaded neonatal rat heart. The constriction of abdominal aorta was performed at postnatal day 2 in male Wistar rats. Decreased body weight, significant since week 6, was observed during development of cardiomegaly. At 12 weeks, the heart to body weight ratio was increased by 45 % and by 109 % in group with compensated (AC I) and decompensated (AC II) heart failure, respectively. At this age, the ECG was recorded and histological and immunohistochemical measurements were performed to analyze the pro-arrhythmogenic remodeling of working myocardium and cardiac conduction system. The markers of pro-arrhytmogenic remodeling such as significant prolongation of QT and QTc intervals were observed in the ECG recordings of AC II animals. However, spontaneously occurring arrhythmias was not detected. Further analysis of working myocardium showed decrease in Cx43 expression and its...

In this master’s thesis, a mechanical design of an in-column secondary electrons (SE) detector is presented. It is an ultravacuum compatible fibre-scintillation detector designed for use in an ultrahigh vacuum scanning electron microscope (UHV SEM). The designed in-column SE detector was manufactured and tested upon overcoming R&D challenges. The first section of this thesis deals with theoretical basis needed for understanding of functional principles of UHV SEM system and means of SE’s detection. In the second section, mechanical design of the in-column SE detector is described. The last section describes functionality of the designed detector. Effectiveness of light shielding of the detector was tested and the detective quantum efficiency was measured. Finally, images created by the designed in-column detector and an in-chamber SE detector were evaluated and compared.

Ventricular premature beats are ectopic changes in the ECG signal. Detection of ventricular extrasystoles on 12leads ECG was created in MATLAB. At first my work involves whether the ventricular premature beats comes from the right or the left ventricle. Another algorithm evaluates the incidence outflow tract of the chamber. If the previous algorithm shows signs of indecision, another algorithm is used for detection of ventricular extrasystoles at another location in the left ventricle. The last step is to narrow the area of detection which makes it easier to find the place of origin.