Tumor necrosis factor a (TNFa) was found to be significantly increased in skeletal muscles and retroperitoneal fat of obese insulin-resistant Koletsky rats as compared to control Wistar rats. This increase was accompanied by a depression of insulin receptor protein tyrosine kinase (PTK) activity. Neither the insulin-binding capacity nor insulin receptor affinity were related to this TNFa increase in these tissues. In the liver, no significant changes of TNFa content and only a lowering of insulin-binding capacity were found. It is concluded that an increased TNFa content in muscles and fat (but not in the liver) contributes to insulin resistance by lowering insulin receptor protein tyrosine kinase activity, while other insulin receptor characteristics (insulin-binding capacity and affinity of insulin receptors to the hormone) do not seem to be influenced by this factor., A. Hřebíček, M. Rypka, Z. Chmela, J. Veselý, M. Kantorová, V. Golda., and Obsahuje bibliografii
Endogenous regulators, such as angiotensin-II (AngII), endothelin-1 (ET-1) and urotensin-II (U-II) are released from various cell types and their plasma levels are elevated in several cardiovascular diseases. The present study evaluated a potential crosstalk between these systems by investigating if the myocardial effects of U-II are modulated by AngII or ET-1. Effects of U-II (10-8 , 10 -7 , 10 -6 M) were tested in rabbit papillary muscles in the absence and in the presence of losartan (selective AT1 receptor antagonist), PD-145065 ( nonselective ET-1 receptors antagonist), losartan plus PD-145065, AngII or ET-1. U-II promoted concentration-dependent negative inotropic and lusitropic effects that were abolished in all experimental conditions. Also, U-II increased resting muscle length up to 1.008±0.002 L/Lmax. Correcting it to its initial value resulted in a 19.5±3.5 % decrease of resting tension, indicating increased muscle distensibility. This effect on muscle length was completely abolished in the presence of losartan and significantly attenuated by PD-145065 or losartan plus PD-145065. This effect was increased in the presence of AngII, resulting in a 27.5±3.9 % decrease of resting tension, but was unaffected by the presence of ET-1. This study demonstrated an interaction of the U-II system with the AngII and ET-1 systems in terms of regulation of systolic and diastolic function., A. P. Fontes-Sousa ... [et al.]., and Obsahuje seznam literatury
This study appears from an experiment previously carried out in New Zealand white rabbits. Allogenic mesenchymal stem cells (MSCs) were transplanted into an iatrogenically-created defect in the lateral section of the distal physis of the left femur in 10 miniature pigs. The right femur with the same defect served as a control. To transfer MSCs, a freshly prepared porous scaffold was used, based on collagen and chitosan, constituting a compact tube into which MSCs were implanted. The pigs were euthanized four months after the transplantation. On average, the left femur with transplanted MSCs grew more in length (0.56±0.14 cm) compared with right femurs with physeal defect without transplanted MSCs (0.14 ± 0.3 cm). The average angular (valgus) deformity of the left femur had an angle point of 0.78°, following measurement and X-ray examination, whereas in the right femur without transplantation it was 3.7°. The initial results indicate that preventive transplantation of MSCs into a physeal defect may prevent valgus deformity formation and probably also reduce disorders of the longitudinal bone growth. This part of our experiment is significant in the effort to advance MSCs application in human medicine by using pig as a model, which is the next step after experimenting on rabbits., L. Plánka ... [et al.]., and Obsahuje seznam literatury
Electrogastrography (EGG) is a non-invasive method for the assessment of gastric myoelectrical activity. Porcine EGG is comparable with human one. The purpose of this study was to evaluate the effect of atropine and neostigmine on the EGG in experimental pigs. Adult female pigs were administrated atropine (1.5 mg i.m., n=6) and neostigmine (0.5 mg i.m., n=6) after the baseline EGG, followed by a 90-min trial recording (MMS, Enschede, the Netherlands). Running spectral analysis was used for the evaluation. The results were expressed as dominant frequency of slow waves and EGG power (areas of amplitudes). Neostigmine increased continuously the dominant frequency and decreased significantly the EGG power. Atropine did not change the dominant frequency significantly. However, atropine increased significantly the EGG power (areas of amplitudes) from basal values to the maximum at the 10-20-min interval. After that period, the areas of amplitudes decreased significantly to the lowest values at the 60-90-min interval. In conclusion, cholinergic and anticholinergic agents affect differently EGG in experimental pigs., J. Květina, I. Tachecí, M. Pavlík, M. Kopáčová, S. Rejchrt, T. Douda, M. Kuneš, J. Bureš., and Obsahuje bibliografii
The purpose of this study was to determine the production of metalloproteinases (MMP) 2 and 9 following UV-B irradiation in human corneal epithelial cells and fibroblasts. Epithelial cells and fibroblasts were separated from human donor corneas and exposed to UV-B lamp irradiation for 20, 40, 80 and 120 s. Media samples were collected at 8, 24, 48 and 72 h and gelatinase A and B production was assayed by the ELISA test. Statistical significance of production was assessed by the paired t-test. Increased production of MMP-2 was found in human corneal fibroblasts in response to UV-B irradiation. A statistically significant production of MMP-2 was not observed in human corneal epithelial cells following UV-B exposure. We did not detect any increase in MMP-9 after irradiation in either epithelial cells or fibroblasts. MMP-2 is produced by the corneal fibroblasts in the acute phase after UV-B irradiation. MMP-9 is not released in vitro following UV-B irradiation damage and therefore does not directly participate in the pathophysiology of acute photokeratitis., I. Kozák, D. Klisenbauer, T. Juhás., and Obsahuje bibliografii
The purpose of this study was to determine the role of lipotoxicity in vascular smooth muscle (VSM). C1-BODIPY 500/510 C12 used to assess the ability of VSM A7r5 cells to transport long-chain fatty acids showed that lipid transport did not appear to limit metabolism. Thin layer chromatography revealed that storage of transported fatty acid occurred primarily as mono- and diglycerides and fatty acids but not as triglycerides. We used lipid-induced apoptosis as a measure of lipotoxicity and found that 1.5 mM palmitate (6.8:1) bound to albumin resulted in a 15-fold increase in the number of apoptotic cells compared to the control at 24 hours. This apoptosis did not seem to be due to an increase in reactive oxygen species (ROS) since VSM cells incubated in palmitate showed less ROS production than cells incubated in albumin only. Similar exposure to oleate did not significantly increase the number of apoptotic cells compared to the control. Oleate actually significantly attenuated the apoptosis induced by palmitate, suggesting that unsaturated fatty acids have a protective effect on cells undergoing palmitate-induced apoptosis. These results suggest that vascular smooth muscle is vulnerable to lipotoxicity and that this lipotoxicity may play a role in the development of atherosclerosis., H. M. Mattern, C. D. Hardin., and Obsahuje bibliografii a bibliografické odkazy
The aim of this study is to define the possible effects of vegetable oils used as vitamin E vehicle on the electrical activity of the rat heart. To test the possible effects of vitamin E vehicles we studied the effect of i.p. injected corn oil, hazelnut oil or peanut oil on the action potential parameters recorded in both papillary and left atrial muscle strips. Four experimental groups were used. The control group was injected (i.p.) with distilled water, while the three remaining groups received injections of corn oil, hazelnut oil, or peanut oil for five weeks (in a dose of 0.4 ml/kg/day - minimum amount of oil in which vitamin E could be dissolved). We used borosilicated (15-20 MΩ) capillary electrodes and intracellular action potentials (AP) were recorded in isolated papillary and left atrium muscle strips. While administration of three different types of vegetable oil had no significant effect on AP parameters of papillary muscle, they significantly prolonged the repolarization phase of AP in atrial strips. These results show that vegetable oils used as vitamin E vehicles may alter the electrical activity of the heart in a tissue-dependent manner. The present data indicate that the possible effect of vegetable oil vehicles should be kept in mind while evaluating the possible effects of in vivo vitamin E administration., S. Ozdemir, M. Ayaz, T. Tuncer, M. Ugur, B. Turan., and Obsahuje bibliografii
To investigate the vestibular and somatosensory interaction in human postural control, a galvanic vestibular stimulation of cosine bell shape resulting in a small forward or backward body lean was paired with three vibrations of both soleus muscles. The induced body lean was registered by the position of the center of foot pressure (CoP). During a quiet stance with eyes closed the vibration of both soleus muscles with frequency (of) 40 Hz, 60 Hz and 80 Hz resulted in the body lean backward with velocities related to the vibration frequencies. The vestibular galvanic stimulation with the head turned to the right caused forward or backward modification of CoP backward response to the soleus muscles vibration and peaked at 1.5-2 s following the onset of the vibration. The effect of the paired stimulation was larger than the summation of the vestibular stimulation during the quiet stance and a leg muscle vibration alone. The enhancement of the galvanic stimulation was related to the velocity of body lean induced by the leg muscle vibration. The galvanic vestibular stimulation during a faster body movement had larger effects than during a slow body lean or the quiet stance. The results suggest that velocity of a body postural movement or incoming proprioceptive signal from postural muscles potentiate the effects of simultaneous vestibular stimulations on posture., O. Dzurková, F. Hlavačka., and Obsahuje bibliografii a bibliografické odkazy
Hypoxia stimulates ventilation, but when it is sustained, a decline in the ventilatory response is seen. The mechanism responsible for this decline lies within the CNS, but still remains unknown. In this study, we attempted to elucidate the possible role of hypoxia-induced depression of respiratory neurons by comparing the ventilatory response to hypoxia in intact rats and those with denervated carotid bodies. A whole-body plethysmograph was used to measure tidal volume, frequency of breathing and minute ventilation (VE) in awake and anesthetized intact rats and rats after carotid body denervation during exposure to hypoxia (FIO2 0.1). Fifteen-minute hypoxia induced an initial increase of VE in intact rats (to 248 % of control ventilation in awake and to 227 % in anesthetized rats) followed by a consistent decline (to 207 % and 196 % of control VE, respectively). Rats with denervated carotid bodies responded with a smaller increase in VE (to 134 % in awake and 114 % in anesthetized animals), but without a secondary decline (145 % and 129 % of control VE in the 15th min of hypoxia). These results suggest that afferentation from the carotid bodies and/or the substantial increase in ventilation are crucial for the biphasicity of the ventilatory response to sustained hypoxia and that a central hypoxic depression cannot fully explain the secondary decline in VE., H. Maxová, M. Vízek., and Obsahuje bibliografii
Visfatin is a multi-functional molecule that can act intracellularly and extracellularly as an adipokine, cytokine and enzyme. One of the main questions concerning visfatin is the mechanism of its secretion; whether, how and from which cells visfatin is released. The objective of this in vitro study was to observe the active secretion of visfatin from 3T3-L1 preadipocytes and adipocytes, HepG2 hepatocytes, U-937, THP-1 and HL-60 monocytes and macrophages. The amount of visfatin in media and cell lysate was always related to the intracellular enzyme, glyceraldehyde-3- phosphate dehydrogenase (GAPDH), to exclude the passive release of visfatin. Visfatin was not found in media of 3T3-L1 preadipocytes. In media of 3T3-L1 adipocytes and HepG2 hepatocytes, the ratio of visfatin to the amount of GAPDH was identical to cell lysates. Hence, it is likely that these cells do not actively secrete visfatin in a significant manner. However, we found that significant producers of visfatin are differentiated macrophages and that the amount of secreted visfatin depends on used cell line and it is affected by the mode of differentiation. Results show that 3T3-L1 adipocytes and HepG2 hepatocytes released visfatin only passively during the cell death. U-937 macrophages secrete visfatin in the greatest level from all of the tested cell lines., P. Svoboda, E. Křížová, K. Čeňková, K. Vápenková, J. Zídková, V. Zídek, V. Škop., and Obsahuje bibliografii