The aim of the study was to evaluate the impact of simulated acute hyperglycemia (HG) on PI3K/Akt signaling in preconditioned and non -preconditioned isolated rat hearts perfused with Krebs -Henseleit solution containing normal (11 mmol/l) or elevated (22 mmol/l) glucose subjected to ischemia -reperfusion. Ischemic preconditioning (IP) was induced by two 5 -min cycle s of coronary occlusion followed by 5 -min reperfusion. Protein levels of Akt, phosphorylated (activated) Akt (P-Akt), as well as contents of BAX protein were assayed (Western blotting) in cytosolic fraction of myocardial tissue samples taken prior to and a fter 30 -min global ischemia and 40- min reperfusion. In “normoglycemic ” conditions (NG), IP significantly increased P -Akt at the end of long -term ischemia, while reperfusion led to its decrease together with the decline of BAX levels as compared to non- pre conditioned hearts. On the contrary, under HG conditions, P -Akt tended to decline in IP - hearts after long -term ischemia, and it was significantly higher after reperfusion than in non -preconditioned controls . No significant influence of IP on BAX levels at the end of I/R was observed under HG conditions . It seems that high glucose may influence IP -induced activation of Akt and its downstream targets, as well as maintain persistent Akt activity that may be detrimental for the heart under above conditions., M. Zálešák, P. Blažíček, I. Gablovský, V. Ledvényiová, M. Barteková, A. Ziegelhöffer, T. Ravingerová., and Obsahuje bibliografii
We investigated and evaluated post-irradiation survival in cyclooxygenase-2-deficient (COX-2 KO) mice. Thirty-day survival following exposure of COX-2 KO mice to a lethal dose of 8.5 Gy of γ-rays was observed to be statistically significantly lower in both males and females, as well as when the sexes were merged, in comparisons with their wild-type counterparts. These findings were related to the previous observations concerning the detrimental influence of the COX-2 genetic disruption on hematopoiesis in sublethally irradiated mice. Deteriorated postirradiation survival of COX-2 KO mice confirmed the previously anticipated conclusion regarding negative influence of the antiinflammatory action of COX-2 deficiency under the conditions of exposure of the animals to ionizing radiation., M. Hofer, Z. Hoferová, A. Gruzdev, L. Dušek, M. Falk., and Obsahuje bibliografii
Resistance to vitamin D has been known for decades as vitamin D resistant rickets, caused by mutations of the gene encoding for vitamin D receptor (VDR). Findings of extra-skeletal effects of vitamin D and learning of the molecular mechanisms used by its biologically active metabolite calcitriol revealed other ways leading to its impaired sensitivity. Calcitriol takes advantage of both genomic and non-genomic mechanisms through its binding to vitamin D receptor, located not only in the cell nuclei but also in a perinuclear space. On the genomic level the complex of calcitriol bound to VDR binds to the DNA responsive elements of the controlled gene in concert with another nuclear receptor, retinoid X receptor, and expression of the VDR itself is controlled by its own ligand. These elements were found not only in the promotor region, but are scattered over the gene DNA. The gene expression includes a number of nuclear transcription factors which interact with the responsive elements and with each other and learning how they operate would further contribute to revealing causes of the impaired vitamin D sensitivity. Finally, the examples of major disorders are provided, associated with impairment of the vitamin D function and its receptor., L. Máčová, M. Bičíková, R. Hampl., and Obsahuje bibliografii
Fatty liver disease associated with obesity is an important medical problem and the mechanisms for lipid accumulation in hepatocytes are not fully elucidated yet. Recent findings indicate that mitochondria play an importan t role in this process. Our data on hepatocytes in which mitochondria are in contact with other cytosolic structures importan t for their function, extend observations obtained on isolated mitochondria and confirm inhibition of Complex I activity in hepatocytes isolated from rats fed by high fat diet (HFD) compared with controls fed by standard diet (STD). Furthermore we have found that HFD- hepatocytes are more sensitive to the peroxidative stress because under these conditions also Complex II activity is disturbed. Therefore in HFD animals decrease of Complex I activity cannot be compensated by Complex II substrates as in STD hepatocytes. Our data thus indicates that combination of HFD and peroxidative stress potentiates HFD damaging effect of mitochondria because both branches of the respiratory chain (NADH- and flavoprotein-dependent) are disturbed., T. Garnol ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The electrical properties of the supported lipid bilayer membrane (s-BLM) of egg phosphatidylcholine (PC) selfassembled on agar surface were examined. To characterize the insulating properties of s-BLMs, electrochemical impedance spectroscopy (EIS) was used. The analysis of impedance spectra in terms of an equivalent circuit of agar/electrolyte and agar/s-BLM/electrolyte in the frequency range of 0.1 Hz-10 kHz was performed. The high-density lipoproteins (HDL)/s-BLM interaction in the concentration range from 20 μg/ml to 80 μg/ml of HDL was investigated. It is evident that treatment of s-BLM with HDL resulted in an increase of the lipid film resistance and a decrease of membrane capacitance., M. Legiň, G. Laputková, J. Sabo, L. Vojčíková., and Obsahuje bibliografii
The objective of this study was to find out the implication of QRS duration in dogs with rapid pacing-induced heart failure. Sixteen Beagle dogs were implanted with transvenous cardiac pacemakers and underwent rapid right ventricular pacing for 3 weeks at 260 bpm to induce hear t failure. Dogs were divided into two groups according to the QRS duration: 9 with normal QRS duration (<100 ms) and 7 wi th prolonged QRS duration (≥100 ms). Cardiac systolic functi on and size was analyzed by real time 3-dimensional echocardiography and left ventricular dyssynchrony was assessed by speckle tracking strain imaging. Congestive heart failure developed 3 weeks after rapid right ventricular pacing. Dogs with prolonged QRS duration showed more extensive radial strain and circumferential strain dyssynchrony than dogs with norm al QRS duration. At the end of 4-week recovery, greater improvemen t of left ventricular ejection fraction and left ventricular end-systolic volume was detected in dogs with normal QRS duration. The findings suggested that left ventricular dyssynchrony, indicated by a prolonged QRS duration, predicted an unsatisfying recovery in dogs with rapid pacing- induced heart failure. QRS duration had the potential to be a prognostic indicator for dogs with heart failure., Y. Wang ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
There are five subtypes of muscarinic receptors that serve various important physiological functions in the central nervous system and the periphery. Mental functions like attention, learning, and memory are attributed to the muscarinic M1 subtype. These functions decline during natural aging and an early deficit is typical for Alzheimer´s disease. In addition, stimulation of the M1 receptor increases non-amyloidogenic processing of the amyloid precursor protein and thus prevents accumulation of noxious β-amyloid fragments. The selectivity of classical muscarinic agonists among receptor subtypes is very low due to the highly conserved nature of the orthosteric binding site among receptor subtypes. Herein we summarize some recent studies with the functionally-selective M1 agonist xanomeline that indicate complex pharmacological profile of this drug that includes interactions with and activation of receptor from both orthosteric and ectopic binding sites, and the time-dependent changes of ligand binding and receptor activation. These findings point to potential profitability of exploitation of ectopic ligands in the search for truly selectiev muscarinic receptor agonists., J. Jakubík, P. Michal, E. Machová, V. Doležal., and Obsahuje bibliografii a bibliografické odkazy
The need of better labelling of fats in processed animal origin products is urgent. The lack of information makes it possible to exclude n-3 fatty acids in preparations of foods. The higher fat content, the higher n-6/n-3 ratio seems to be a rule. It is desirable to broaden the labelling into which oils have been used when foods are processed. The dietary balance of n-6 and n-3 fatty acids is important for homeostasis and normal development in humans. The ratio between n-6/n-3 fatty acids suggested to be evolutionary developed is between 1 and 4. The main conclusion is that the fat sources used during processing and preparation of convenient foods have the largest impact on the food FA content and composition. A proposal is therefore that this should be declared on the product label especially the n-3 FA content. It is also of large importance to increase consumption of freshwater fish fed suitable feeds containing n-3 fatty acids in central Europe to enable a generally lower n-6/n-3 ratio in the human diet. Therefore optimizing feeds to freshwater fish in culture is urgent and important., J. Picková., and Obsahuje seznam literatury
There is a growing interest for the beneficial effect of magnesium (Mg) in cardiovascular disorders. A number of cardiovascular disorders including myocardial infarction, arrhythmias and congestive heart failure have been associated with low extracellular or intracellular concentrations of Mg. The efficiency of the preconditioning effect of Mg on cardiac function and infarct size in the globally ischemic-reperfused isolated rat heart was studied together with the role of ATP-sensitive potassium (KATP) channels in protection induced by Mg. Rat hearts were Langendorff perfused, subjected to 30 min of global ischemia and 90 min of reperfusion, including treatment groups which focused on different times of Mg (8 mmol/l) use. Infarct size was measured by triphenyltetrazolium chloride (TTC) method. The left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). The administration of Mg before ischemia had an anti-infarct effect in rat hearts and improved cardiac function. The protective effects of magnesium was abolished by the blocking of KATP channels and suggests that K-ATP channel has an important role in the heart protection effect of Mg as a preconditioning agent., M. Bazargan, M. Faghihi, M. Chitsaz., and Obsahuje bibliografii a bibliografické odkazy
Autophagy is the basic catabolic mechanism that involves degradation of dysfunctional cellular components through the action of lysosome as well as supplying energy and compounds for the synthesis of essential biomacromolecules. This process enables cells to survive stress from the external environment like nutrient deprivation. Autophagy is important in the breakdown of proteins, carbohydrates and lipids as well. Furthermore, recent studies have shown that autophagy is critical in wide range of normal human physiological processes, and defective autophagy is associated with diverse diseases, including lysosomal storage disease, myopathies, neurodegeneration and various metabolic disorders. This review summarizes the most up-to-date findings on what role autophagy plays in metabolism., Z. Papáčková, M. Cahová., and Obsahuje bibliografii