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The role of Akt kinase in cardioprotective mechanisms induced by chronic hypoxia
Grešíková, Milada ; Žurmanová, Jitka (advisor) ; Svatoňová, Anna (referee)
Cardiovascular diseases (CVDs) are the most widely spread diseases of modern civilization. Mechanisms involved in the protection of myocardial tissue are for that very reason in the focus of cardiovascular research. The adaptation to chronic hypoxia has been studied for many years in the context of its positive effects on heart function and its increased tolerance to ischemia-reperfusion (I/R) injury. This Master thesis describes the role of Akt kinase in the mechanisms leading to myocardial protection against I/R injury using the model of adaptation to chronic normobaric hypoxia (CNH). The hearts from male Wistar rats, that were kept in normoxic or hypoxic conditions (O2 0.1) for the period of 3 weeks, were retrogradely perfused by oxygenated Krebs-Henseleit solution and then subjected to 10 min of ischemia and 10 min of reperfusion. Samples prepared from left ventricles (LV) of experimental hearts were later used for protein analyses. The adaptation to CNH leads to increased phosphorylation of Akt kinase on Ser473, but it did not affect the phosphorylation on Thr308 nor the total protein level of Akt. A significant increase in Bcl-2/Bax ratio was also observed in hearts adapted to CNH. This Master thesis further elucidates, how Akt signaling pathway and its activation are affected by short...
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Energy metabolism of skeletal muscle
Elkalaf, Moustafa GamalEldin Mahmoud Mohamed ; Anděl, Michal (advisor) ; Drahota, Zdeněk (referee) ; Žurmanová, Jitka (referee)
Skeletal muscle is the largest tissue in the body and plays a marked role in the homeostasis of the body metabolic state. Mitochondria have been proven to contribute to the pathophysiology of various metabolic diseases, either due to defects in their bioenergetic properties or the production of reactive oxygen species. In this work murine myoblasts C2C12 were used as a model of skeletal muscle in vitro, and rat muscle was used to prepare homogenate enriched in the mitochondrial fraction. This work investigates the changes in respiratory parameters in models where mitochondrial oxidative phosphorylation is induced by changing the available consumable substrates in the culture media, such as replacing glucose by galactose, and the effect of treating the cells with high glucose concentration during the process of differentiation on mitochondrial performance. It also investigates the changes in bioenergetic profiles in samples treated with inactive derivatives of the widely used triphenylphosphonium (TPP+) salts to target mitochondria by various probes and antioxidants. The methods used in this study included evaluating mitochondrial parameters in intact and permeabilized cells by real time measurement of the oxygen consumption rate using the extracellular flux analyzer, measuring the enzymatic...
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Gene expression of selected genes in heart of long-term cold acclimated rat under mild conditions
Marvanová, Aneta ; Žurmanová, Jitka (advisor) ; Nováková, Olga (referee)
Beneficial effect of hardening or cold adaptation for human health has been known for many decades. Beneficial or detrimental effect depends on the regimen and intensity of the adaptation and thus it is very important to pay attention to them. It has been shown in previous studies that cold adaptation of animals at a low temperature 0-4 žC is accompanied by dehydration and the damage of kidneys. As our best knowledge, the effect of mild cold adaptation on the molecular mechanisms in the heart has not been studied until now. The first aim of this study was to set up a new model of cold adaptation without any negative effects on the organism. The second aim was to assess mRNA levels of selected genes related to the important mechanisms associated with energy metabolism and cardio-protective signaling pathways in the left ventricle. Results obtained using the new model for cold adaptation at 102 řC did not show any negative changes in the blood or urine parameters and body fluid balance was maintained. Screening of mRNAs showed that chronic adaptation might affect the phenotype of the heart, transcriptional activity of the antioxidant system and of the pro-apoptotic genes, lowers adrenergic signaling and moderate glucose metabolism in cardiomyocytes. Key words: cold adaptation, heart, gene...
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Ischemia-reperfusion injury in cold acclimated rats
Vebr, Pavel ; Žurmanová, Jitka (advisor) ; Alánová, Petra (referee)
The effect of cold acclimation on body of mammals has been studied for many decades by using relatively low temperatures for acclimation (6-10 řC). The results of these experiments have shown the important role of the adrenergic and thyroid system during acclimation and negative impact on renal system at the same time. In contrast, a recent study on winter swimmers suggests a possibility of positive influence of hardening on cardiovascular system. There is no available study investigating a relationship between cold adaptation and ischemia-reperfusion injury. The aim of this study was to establish a protocol of isolated rat heart and its fixation at our workplace. Furthermore, to find the impact of mild cold acclimation on the ischemia-reperfusion injury of rat. Methods of ex vivo heart perfusion and fixation were successfully established. The effect of 5 weeks long cold acclimation in 10 ± 2 řC on left ventricle ischemia-reperfusion injury was observed. Powered by TCPDF (www.tcpdf.org)
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Autophagy as a biochemical phenomenon of neurodegeneration
Čechová, Kateřina ; Vrajová, Monika (advisor) ; Žurmanová, Jitka (referee)
Autophagy is a nonspecific catabolic process which targets damaged organelles, proteins and intracellular pathogens. Autophagy becomes less efficient with normal and also with accelerated aging. Electron microscopy studies on brain of patients with Alzheimer's disease provide evidence that autophagy is involved in the neurodegenerative process. Stimulation of autophagy has a neuroprotective effect and help to degrade changed or aggregated proteins.
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The role of Akt / protein kinase B in healthy and hypertrophied heart
Heleš, Mário ; Žurmanová, Jitka (advisor) ; Hrdlička, Jaroslav (referee)
Protein kinase B, or Akt kinase is expressed in almost all tissues. Two main isoforms in heart are Akt1 and Akt2, which are responsible for regulation of metabolism, growth and survival of cardiomyocytes. Akt kinase is among other pathways stimulated by insulin receptor and mechanoreceptor cascades and its main targets are mTORC1, AMPK and GSK- 3β. Akt kinase is activated in presence of chronic hemodynamic overload of heart. In dependence of intensity and duration of overload, Akt participate in triggering of either adaptive, fully reversible hypertrophy or detrimental irreversible form of hypertrophy, which causes impairment of pumping function of heart and can lead to heart failure. Many more factors with complex interactions participate in cardiac hypertrophy beside Akt kinase. Key words: heart, hypertrophy, Akt/protein kinase B, cardiac remodeling, insulin- like growth factor
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The role of mitochondrial creatine kinase and hexokinase in cardioprotective mechanisms induced by chronic hypoxia
Wasková, Petra ; Žurmanová, Jitka (advisor) ; Drahota, Zdeněk (referee) ; Nováková, Olga (referee)
IN ENGLISH The ischemia-reperfusion (I/R) injury, which is a consequence of myocardial infarction, represents a major cause of death worldwide. One of the most effective cardioprotective interventions increasing the resistance of hearts to the I/R injury is the adaptation to a chronic hypoxia (CH). However, the molecular mechanisms of CH are still not well understood. The most important factors responsible for the I/R injury are reactive oxygen species (ROS) produced by complexes I and III within the mitochondrial electron transport chain. Potential candidates maintaining ROS at a low level are mitochondrial creatine kinase (mtCK) and two hexokinase isoforms (HK1 and HK2). These enzymes highly support the mitochondrial oxidative phosphorylation by increasing the availability of ADP for complex V of the respiratory chain. In addition, the HK binding to mitochondria inhibits binding of the pro- apoptotic protein BAX, thereby protecting cardiac cells against apoptosis. Besides the mitochondrial CK isoform, there are two cytosolic CK (CKM and CKB) present in cardiomyocytes that help to maintain energy homeostasis. Based on the known anatomical and physiological differences between the left (LV) and the right (RV) ventricles, the first study focused on the comparing ventricles in terms of the energy...
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Energy metabolism of heart at high altitude and during physical exercise
Flégrová, Eliška ; Žurmanová, Jitka (advisor) ; Kolář, David (referee)
1 ABSTRACT Heart is a highly oxidative tissue with the ability to modulate its energetic metabolism according to prevailing conditions of the organism. Stress conditions such as exercise and prolonged staying at high altitude induce a fetal gene programme leading to increased carbohydrate and decreased fatty acid utilization. It seems that mitochondrial fuction and the changes in redox state of the cell play a key role in activation of various transcriptional factors, mainly HIF-1α modulating expression of numerous signalling and metabolic pathways as well as changes in structural proteins in the heart. Activation of these mechanisms results in cardioprotective phenotype which increased the tolerance of the heart to acute lack of oxygen. Understanding the mechanisms of these adaptive changes is important for the development of tools that would help reduce the effects of acute myocardial infarction in humans.
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Gene expression of enzymes involved in the regulation of apoptosis in rat moycardium - effect of chronic and acute hypoxia
Blahová, Tereza ; Žurmanová, Jitka (advisor) ; Kalous, Martin (referee)
Adaptation to chronic hypoxia provides myocardial protection against ischemia - reperfusion injury (IR). Cardioprotective effect of adaptation depends on the degree and duration of hypoxic exposure and daily regime of adaptation. Certain protective regimes of adaptations to hypoxia have been reported to activate proapoptotic signaling pathways and bioactive sphingolipids were recently shown to play important role in the regulation of apoptosis in the heart. We aimed to determine the mRNA level of selected genes related to apoptotic pathways and to sphingolipid metabolism in two models of hypoxic adaptation, continous normobaric hypoxia (CNH 10% O2) with different exposures (4h, 48h, 120h, 21days) and intermitent hypobaric hypoxia (IHH 7000 m, 8h/day). Both ventricles, LV and RV, were analysed after adaptation to CNH and only LV was analysed after IHH adaptation. Our results show that both types of adaptation increased mRNA of proapoptotic genes, CNH mainly in RV and IHH in LV. Furthermore, increased expressions of proapoptotic genes were accompanied by the increase of expression of enzymes producing predominantly protective kinds of sphingolipids. The exact role of apoptosis and sphingolipid signaling molecules in endogenous myocardial protection requires further research. Key words: Apoptosis,...
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Effect of chronic hypoxia on antioxidative capacity of rat myocardium.
Závišková, Kristýna ; Nováková, Olga (advisor) ; Žurmanová, Jitka (referee)
Adaptation to chronic hypoxia activates endogenous signaling cascades, which lead to cardiac protection against acute ischemia/reperfusion (I/R) injury. The molecular mechanism of this phenomenon has not been fully clarified yet. However, it was proved that reactive oxygen species (ROS) take part in cardioprotective signaling pathway inducted by chronic hypoxia. The high level of ROS must be precisely regulated by antioxidative system of a cell. The aim of diploma thesis was to examine the effect of intermittent hypobaric hypoxia (IHH, 7 000 m) on relative amount of antioxidative enzymes (peroxiredoxin 6 - PRX6, thioredoxin 1 and 2 - TRX1 and TRX2, thioredoxin reductase 1 - TRXR1) and also enzymes of iron metabolism (heme oxygenase 1 and 2 - HO1 and HO2, aconitase 1 and 2 - ACO1 and ACO2), which participate in regulation of cell redox state. Moreover, we studied the effect of adaptation to IHH and an antioxidant tempol on relative amount of calcium-independent phospholipase A2 (iPLA2). iPLA2 can remove peroxidized fatty acids from membrane phospholipids. On the other hand, iPLA2 can damage cell in I/R conditions. All enzymes were studied in homogenates from normoxic and IHH adapted rat left ventricular myocardium by Western blot. Adaptation to IHH caused a decrease of PRX6 and on the opposite an increase of...
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