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The use of magnetic resonance spectroscopy for studying glucose metabolism
Kratochvílová, Simona ; Pelikánová, Terezie (advisor) ; Štich, Vladimír (referee) ; Polák, Jan (referee)
Magnetic resonance spectroscopy (MRS) is a noninvasive technique that enables to follow metabolic processes in selected tissues in vivo. Recently the attention has been focused on metabolic mapping in target organs of insulin action to describe the pathophysiology of insulin resistance. The aim of our study was to present the practical application of ³¹P (phosphorus) MRS and ¹H (proton) MRS in metabolic studies of skeletal muscle in insulin resistant subjects and in subjects with impaired fasting glucose. The third study was aimed to evaluate the brain metabolism with ¹H MRS in healthy controls and subjects with type 1 diabetes during hyperinsulinemia. ¹H and ³¹P MRS were performed using a MR Scanner Siemens Vision operating at 1,5 Tesla. To assess the parameters of glucose metabolism and insulin action oral glucose tolerance test and hyperinsulinemic euglycemic clamp were performed. The study 1 was aimed to evaluate the skeletal muscle (m. soleus) energetic metabolism in the offspring of hypertensive parents (OH) with a higher level of insulin resistance. The concentrations of selected high energy phosphates (phosphocreatine, inorganic phosphate, adenosintriphosphate, phosphomonoesters, phosphodiesters) were evaluated with ³¹P MRS. Their amount in OH was comparable to healthy controls. However we...
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Sleep apnea syndrome as risk factor for development metabolic impairments
Weiszenstein, Martin ; Polák, Jan (advisor) ; Donič, Viliam (referee) ; Malínská, Hana (referee)
Excessive accumulation of adipose tissue is causally related to the development of insulin resistance and glucose intolerance with subsequent development of type 2. diabetes and increased cardiovascular mortality. Although there is relatively convincing epidemiological evidence, mechanisms mediating adverse effects of obesity and associated metabolic disorders still remain only partially elucidated. Among the factors that may play a causal role were determined increased lipolytic activity and related increased release of free fatty acids from adipose tissue. Excessive accumulation of adipose tissue, including all related comorbidities is associated with the development of sleep disorders including obstructive sleep apnea syndrome (OSA). OSA is a relatively common disease that is characterized by the partial obturation of the upper airway during sleep, the so-called Intermittent hypoxia. IH according to the severity of the resulting decrease in hemoglobin saturation is also associated with adipose tissue hypoxia. As confirmed in this study, both mild and severe hypoxia in adipose tissue, even upon exposure to cell cultures resulted in increased lipolytic activity and increased accumulation of triglycerides compared to control conditions. Furthermore, it was confirmed that pharmacological intervention...
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The role of adrenergic signaling in cardioprotection induced by adaptation to chronic hypoxia
Hahnová, Klára ; Novotný, Jiří (advisor) ; Polák, Jan (referee) ; Babula, Petr (referee)
Cardiovascular diseases are currently one of the most common causes of morbidity and mortality in the Western world. Adaptation to chronic hypoxia can contribute to the improvement of ischemic tolerance of myocardium but exact molecular mechanisms leading to the development of a cardioprotective phenotype are still unclear. There are some indications that point to the possible role of β-adrenergic signaling in these processes. In the first part of the thesis, we examined the effect of protective continuous (CNH; 24 h/day) and nonprotective intermittent (INH; 23 h/day hypoxia, 1 h/day reoxygenation) normobaric hypoxia on β-adrenergic signaling in the right (RV) and left ventricles (LV) of Wistar rats. Both hypoxic models led to decrease in the number of β1-adrenergic receptors (β1-ARs) in the RV. There were no significant changes in β-ARs in LV preparations. Although adenylyl cyclase (AC) activity stimulated through Gs proteins was decreased in the RV and increased in the LV after adaptation to CNH and INH, there were no significant changes in the expression of dominant AC 5/6 isoforms. Expression of Gs proteins was decreased in RV in both hypoxic models. These results suggest that chronic normobaric hypoxia may have a strong effect on myocardial β-adrenergic signaling without differences between...
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Adipokines (leptin and adiponectin) as predictors of weight loss and weight regain during one year period following the 10-week low caloric diet (NUGENOB study)
Drahoš, Jan ; Polák, Jan (advisor)
In the Czech republic, about 20% of women and 16% of men are obese. The key role in the etiology of obesity plays the imbalance between energy intake and expenditure, which is influenced by many factors, including leptin and adiponectin. Leptin is secreted mainly from adipocytes and it's levels increase with cell fat content and body fat percentage. Leptin itself is supposed to lead to weight loss, both by decreasing appetite and increasing energy expenditure. But high levels of leptin can be a signal of so called leptin resistance, a state in which leptin is losing it's effects. Adiponectin is secreted exclusively from adipose tissue. In obese people, lower levels of adiponectin were proven (i.e. adiponectin levels are in a negative correlation with body fat percentage). That's consistent with the fact that adiponectin is affecting a range of metabolic prosesses and thus improves insulin sensitivity and metabolic profile. For evaluation, we used a database of almost 750 subjects, that was build under the Nugenob study, conducted in 8 cities in 7 european countries. Al the participants were measured their anthropometric and biochemical parameters at the baseline and after 10 weeks of a standardized weight reduction program. The czech center retested the patient once again 1 year after the initial...
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The concept of beauty in Ficino's commentary De amore and its influence on Renaissance aesthetics
Polák, Ján ; Dykast, Roman (advisor) ; Dadejík, Ondřej (referee)
The aim of this study is to examine piece of work of Marsilio Ficino known as De amore according to the characteristic of author's life and work, and to demonstrate its influence on Renaissance aesthetic. The main motive of the writing that was composed as commentary of Plato's Symposion is the function of love in the cosmology inspired by neoplatonists, mainly Plotinus. Ficino's principal contribution to the Renaissance and modern thinking is translation and development of Plato's work including his conception of double love. This study summarizes Ficino's life and work, afterward it examines writing itself emphasizing aesthetic themes and then demonstrates the influence of Ficino's conception of love on selected works of Renaissance literature. The selection of texts exposes transformation of this conception from piece of work directly inspired by Ficino's theory passing through writing in which is this theory confronted with formal literary requirements to the texts demonstrating dominance of literary form over philosophical content. Keywords Marsilio Ficino*Renaissance Platonism*Renaissance aesthetic*platonic love
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Role of adipose tissue in the ethiopatogenesis of insulin resistance
Polák, Jan ; Štich, Vladimír (advisor) ; Hainer, Vojtěch (referee) ; Kazdová, Ludmila (referee) ; Rossmeisl, Martin (referee)
Adipose tissue is involved in etiopathogenesis of insulin resistance and subsequent metabolic disorders including type 2 diabetes mellitus and atherosclerosis. Mechanisms responsible for this association are investigated vigorously. One of the well accepted mechanisms linking excessive accummulation of adipose tissue with a development of insulin resistance are free fatty acids, which are released into circulation after hydrolysis of triglycerides stored in adipose tissue in a process of lipolysis. Impairments in a regulation of lipolysis are described in obese patients and lead to increased plasma level of free fatty acids and to impaired mobilisation of energy stores during exercise. In this PhD thesis, regulation of lipolysis in subcutaneous abdominal adipose tissuewas investigated using microdialysis technique. In the first paper we have observed that dysregulation in catecholamine-induced lipolysis and impaired insulin action in adipose tissue can be improved by dynamic-strength training in obese men. In the second study, we have demonstrated significant involvement of newly discovered lipolytic pathway mediated by atrial natriuretic peptide in lipolysis stimulation during exercise. Adipose tissue is producing several protein substances with regulatory and endocrine functions collectively named...
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Emerging cardiovascular risk markers in diagnostics and therapy
Tůmová, Eva ; Vrablík, Michal (advisor) ; Freiberger, Tomáš (referee) ; Polák, Jan (referee)
Cardiovascular diseases (CVD) have been one of the leading causes of morbidity and mortality in developed countries with an enormous influence on individual health and significant socioeconomic impact as well. The aim of most physicians in recent decades is to seek the best possible predicative risk factor (RF) (or combination of several RF) which could help to determine the individual risk of developing CVD. This risk stratification can be used to identify the high risk patients and treatment intensification or establishment of early preventive measures. Currently, several RF of atherosclerosis and CVD are commonly used to individualize health care. However, individuals with low levels of these RF suffer of CVD, therefore the effort to find as much as possible specific RF still persists. In recent years, the inflammatory markers, crucial in the atherosclerosis development, raise great expectation In our studies, we focused on investigating the levels of inflammatory parameters in specific groups of patients (obese children and patients with metabolic syndrome) and observed the effect of weight loss following lifestyle changes. Our main concern was lipoprotein-associated phospholipase A2 (Lp-PLA2), oxidized LDL particles (ox-LDL) and myeloperoxidase (MPO). The results demonstrated significantly...
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