Attention has recently been focused on endothelial function after a single high-fat meal, i.e. on the anticipated direct atherogenic effect of triglyceride-rich lipoproteins. Our study was designed to investigate the effect of a low-fat diet given for four weeks followed by a high-fat diet for another four weeks. At the end of each dietary period, a non-invasive ultrasound investigation of endothelial function of the brachial artery was performed along with laboratory tests. Endothelial function was measured immediately before the dietary load and after three and six hours in 11 healthy volunteers. The results were expressed as percentage of the changes in artery diameter at rest and during hyperemia; the data were processed using computer technology. When compared to the low-fat regimen, the total cholesterol content rose after the high-fat diet from 4.28 mmol/l to 5.15 mmol/l (p<0.05) in the whole group of volunteers. There was no difference between both dietary regimens in baseline triglycerides. The brachial artery dilatation under basal conditions was 5.26±2.88 mm after the high-fat diet compared with the value of 3.13±3.01 mm (p<0.05) after the low-fat diet. When measured individually endothelial function in the whole group of volunteers in the course of the day, the degree of arterial dilatation after one month on low-fat diet was 3.13±3.0 %, 3.88±2.5 % and 5.23±3.3 % at single measurement. When comparing arterial dilatation at two closest measurements, a non-significant trend, p>0.05 was seen in either case. The following values were obtained after one month on the high-fat diet: 5.26±2.9 %, 4.47±1.7 %, and 6.2±3.6 %; again showing a non-significant trend of p>0.05. In this study, a single high-fat meal at the different dietary regimen did not significantly influence the vasoreactivity of the brachial artery in young volunteers., T. Šejda, J. Kovář, J. Piťha, R. Cífková, E. Švandová, R. Poledne., and Obsahuje bibliografii
The present paper deals with the regeneration of splenic tissue after autologous transplantation. Control and transplanted rats (60 days after operation (106 cells per injection). The effect of a primary response was studied by a single injection, long-lasting bacteraemia was imitated by 5 injections in weekly intervals. Spleens and transplants were investigated by flow-cytometry and immunohistochemistry. Additionally, the proliferation activity and the specific antibody production against Escherichia coli proteins were tested. Flow-cytometric analysis showed altered behaviour of T-helper cells and B-cells in transplants following a primary response, whereas in the multiple injection group a difference between the splenic and transplant response was restricted to macrophages and MHC II+ cells. The results of the morphometric analysis revealed that the cellular composition of unstimulated transplants was very similar to that of the spleen with some subtle alterations. Only the marginal zone showed more striking differences concerning the homing of several cell classes. Under stimulatory conditions, these subtle alterations became more drastic so that CD5 + cells, B-cells and macrophages responded in an abnormal manner in both groups. The analysis of thymidine kinase disclosed decreased activity in the spleen after weekly antigen stimulation. The stimulation index of all transplant groups was significantly lower than that of the spleen. The specific antibody (IgG) production after a single immunization was highest in the transplant group. All groups responded after the multiple challenge. In conclusion, the results demonstrate that splenic transplants differs in several, but subtle aspects from normal splenic tissue. The main reason for most of these alterations may be a slightly misguided recirculation and/or homing of cells.
Contrary to clinical trials, experimental studies revealed that diabetes mellitus (DM) may initiate, besides increased myocardial vulnerability to ischemia-reperfusion injury (I/R) and pro/antioxidant dysbalance, development of adaptation leading to an enhanced tolerance to I/R. The aims were to characterize 1) susceptibility to ischemia-induced ventricular arrhythmias in the diabetic rat heart 2) its response to antioxidant N-acetylcysteine (NAC ) and a NOS inhibitor L-NAME, and 3) the effect of DM on endogenous antioxidant systems. Seven days after streptozotocin injection (65 mg/kg, i.p.), Langendorff-perfused control (C) and DM hearts were subjected to 30-min occlusion of the LAD coronary artery with or without prior 15-min treatment with L-NAME (100 μM) or NAC (4 mM). Total number of ventricular premature beats (VPB), as well the total duration of ventricular tachycardia (VT) were reduced in the DM group (from 533±58 and 37.9±10.2 s to 224.3±52.6 and 19±13.5 s; P<0.05). In contrast to the antiarrhythmic effects of L-NAME and NAC in controls group (VPB 290±56 and 74±36, respectively; P<0.01 vs. control hearts), application of both drugs in the diabetics did not modify arrhythmogenesis (L-NAME: VPB 345±136, VT 25±13 s; NAC: VPB 207±50, VT 12±3.9 s; P>0.05 vs non-treated diabetic hearts). Diabetic state was associated with significantly elevated levels of CoQ 10 and CoQ 9 (19.6±0.8 and 217.3±9.5 vs. 17.4± 0. 5 and 185.0±5.0 nmol/g, respectively, in controls; P<0.05), as well as α-tocopherol (38.6±0.7 vs. 31.5±2.1 nmol/g in controls; P<0.01) in the myocardial tissue. It is concluded that early period of DM is associated with enhanced resistance to ischemia-induced arrhythmias. Diabetes mellitus might induce adaptive processes in the myocardium leading to lower susceptibility to antioxidant and L-NAME treatment., J. Matejíková, J. Kucharská, D. Pancza, T. Ravingerová., and Obsahuje bibliografii a bibliografické odkazy
Sudden death is a possible occurrence for newborns younger than 1 year with severe aortic coarctation (CoA) before surgical correction. In our previous study, we showed a significant increase of QTc-D and JTc-D in newborns with isolated severe aortic coarctation, electrocardiog raphic parameters that clinical and experimental studies have suggested could reflect the physiological variability of regional and ventricular repolarization and could provide a substrate for life-threatening ventricular arrhythmias. The aim of the current study was to evaluate the effect of surgical repair of CoA on QTc-d, JTc-d in severe aortic coarctation newborns with no associated congenital cardiac malformations. The study included 30 newborns (18M; 70±12 h old) affected by severe congenit al aortic coarct ation, without associated cardiac malformation s. All newborns underwent to classic extended end-to-end repair. Echocardiographic and electrocardiographic measurements were performed in each patient 24 h before and 24 h afte r the interventional procedure and at the end of the follow-up period, 1 month after the surgical correction. All patients at baseline, 24 h and one month after CoA surgical repair did not significantly differ in terms of heart rate, weight, height, and echocardiographic parameters. There were no statistically significant differences in QTc-D (111.7±47.4 vs 111.9±63.8 ms vs 108.5±55.4 ms; P =0.4) and JTc-D (98.1±41.3 vs 111.4±47.5 vs 105.1±33.4 ms; P =0.3) before, 24 h and 1 month after CoA surgical correction. In conclusions, our study did not show a statistically signif icant decrease in QTc-D and JTc- D, suggesting the hypothesis that the acute left ventricular afterload reduction, related to successful CoA surgical correction, may not reduce the ventricular electrical instability in the short- term follow-up., G. Nigro ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Two different isolated skeletal muscles of Japanese quail were used. The influence of branched chain amino acids on the fractional rate of protein synthesis (FSR) was evaluated using 14C-tyrosine. The addition of 0.5 mM valine, leucine or isoleucine to the incubation medium significantly decreased (P<0.05) the value of FSR in extensor metacarpalis radialis. In the ambiens muscle only the application of leucine increased the FSR significantly while valine and isoleucine were without any effect., J. Antalíková, J. Jankela, M. Baranovská., and Obsahuje bibliografii
C-type natriuretic peptides (CNP) play an inhibitory role in smooth muscle motility of the gastrointestinal tract, but the effect of CNP on delayed rectifier potassium currents is still unclear. This study was designed to investigate the effect of CNP on delayed rectifier potassium currents and its mechanism by using conventional whole-cell patch- clamp technique in guinea-pig gastric myocytes isolated by collagenase. CNP significantly inhibited delayed rectifier potassium currents [IK (V)] in dose-dependent manner, and CNP inhibited the peak current elicited by depolarized step pulse to 86.1±1.6 % (n=7, P<0.05), 78.4±2.6 % (n=10, P< 0.01) and 67.7±2.3 % (n=14, P<0.01), at concentrations of 0.01 μmol/l, 0.1 μmol/l and 1 μmol/l, respectively, at +60 mV. When the cells were preincubated with 0.1 μmol/l LY83583, a guanylate cyclase inhibitor, the 1 μmol/l CNP-induced inhibition of IK (V) was significantly impaired but when the cells were preincubated with 0.1 μmol/l zaprinast, a cGMP-sensitive phosphodiesterase inhibitor, the 0.01 μmol/l CNP-induced inhibition of IK (V) was significantly potentiated. 8-Br-cGMP, a membrane permeable cGMP analogue mimicked inhibitory effect of CNP on IK (V). CNP-induced inhibition of IK (V) was completely blocked by KT5823, an inhibitor of cGMP-dependent protein kinase (PKG). The results suggest that CNP inhibites the delayed rectifier potassium currents via cGMP-PKG signal pathway in the gastric antral circular myocytes of the guinea-pig., H. Y. Xu, X. Huang, M. Yang, J.-B. Sun, L.-H. Piao, Y. Zhang, L. Gao, W.-X. Xu., and Obsahuje bibliografii a bibliografické odkazy
The study investigated the effects of different CaCl2 concentrations (2, 5, and 10 mM) on photosynthetic enzymatic activities, photosynthesis, and chlorophyll fluorescence of tung tree seedlings under drought conditions. Plants were sprayed with either CaCl2 or distilled water until run-off. Irrigation was then withheld to induce drought stress. The strength of drought stress was evaluated by relative leaf water content and soil water content, which was 27.3 and 9.5% on day 0 and day 12, respectively. Drought stress decreased activities of ribulose-1,5-bisphosphate carboxylase/oxygenase and phosphoenolpyruvate carboxylase, chlorophyll (a+b) content, net photosynthetic rate, stomatal conductance, transpiration rate, electron transport rate, the maximal quantum yield of PSII photochemistry, and effective quantum yield of PSII in tung tree seedlings. The CaCl2 pretreatments alleviated the negative effect of drought stress to some degree on all the parameters mentioned above., Z. Li, X. F. Tan, K. Lu, Z. M. Liu, L. L. Wu., and Obsahuje bibliografii
The increase of radical forms of mitochondrial respiratory chain compounds (MRCC) is an indicator of an increased risk of the formation of oxygen radicals. Using electron paramagnetic resonance (EPR), we found an increase of signals corresponding to ubisemichinone radical (·QH) and ironsulfur proteins radical forms (·FeS) of these respiratory chain compounds during ischemia in the isolated perfused rat heart (·QH increased from 1.51 to 3.08, ·FeS1 from 1.14 to 2.65 arbitrary units). During the 5-min reperfusion, the signals returned to normoxic levels. In isolated mitochondria exposed to anoxia and reoxygenation the radical forms of ·QH and ·FeS2 changed in a similar manner as in the intact heart. A combination of in vivo captopril treatment and in vitro L-arginine administration significantly decreased the levels of MRCC radicals in the isolated myocardium (·QH from 2.61 to 1.72 and ·FeS1 from 1.82 to 0.46 under normoxia; ·QH from 4.35 to 2.66 and ·FeS1 from 1.93 to 1.35 during ischemia). This decrease in MRCC radical forms was associated with increased NO levels in the perfusate, determined as NO2-/ NO3-, as well as tissue NO levels determined using EPR as the dinitrosyl iron complex (DNIC). These results provide new information about the cardioprotective effects of ACE inhibitors and L-arginine., H. Vavřínková, M. Tutterová, P. Stopka, J. Divišová, L. Kazdová, Z. Drahota., and Obsahuje bibliografii
The aim of this paper is to investigate the influence of COM (Cellular Organic Matter) produced by Microcystis aeruginosa on the process of water purification by destabilisation and subsequent aggregation of the impurity particles. The research was carried out with a raw water into which COM was added. The removal efficiency of the most significant components of COM, i.e. polysaccharides and proteins, was investigated. It was found that the removal efficiency of polysaccharides and proteins was dependent on the reaction conditions (pH, type of destabilisation reagent and its dosage). The removal efficiency of COM was relatively low. It was about 46% and 41% using ferric sulphate and aluminium sulphate aggregation, respectively. In comparison to the other organic components of COM, mainly polysaccharides, the proteins are removed with a higher efficiency. The GPC analyses of the residual COM showed that the proteins of higher molecular weight were aggregated with a higher efficiency. and Cílem práce je opis vlivu buněčných organických látek (COM) produkovaných sinicí Microcystis aeruginosa na proces úpravy vody pomocí destabilizace a následné agregace znečišťujících příměsí. Výzkum byl uskutečňován se syntetickou surovou vodou, do které byly přidány COM získané laboratorní kultivací M. aeruginosa. V průběhu laboratorních testů byla sledována především účinnost odstranění dvou základních složek COM, tj. polysacharidů a proteinů. Bylo zjištěno, že tato účinnost závisí především na reakčních podmínkách (typu a dávce destabilizačního činidla a pH). Účinnost odstranění COM byla poměrně nízká, maximální dosažená účinnost byla 46% při destabilizaci pomocí síranu železitého a 41% při použití síranu hlinitého. Bylo zjištěno, že s vyšší účinností jsou odstraňovány proteiny, obzvláště pak proteiny s vyšší molekulovou hmotností.
Chemical modification of purifíed phosphoenolpyravate carboxylase (PEPC) from the crassulacean acid metabolism plant Crassula argentea Thunb. with the histidyl reagent diethylpyrocarbonate (DEPC) resulted in a transient increase in activity followed by a decrease of activity with time. This biphasic response was observed when the modifíed enzyme was assayed at both low (sub-K,^ and saturating substráte (phosphoenolpyruvate, PEP) concentrations. There was an approximate 25- fold difference in the apparent rate constants for the activation and inhibition phases. This is in contrast to what we háve observed under similar conditions for the C4 enzyme from Zea mays L. for which only inhibition of activity occurs. Spectral studies indicated that up to 7 of the potential 20 histidine residues per subunit were modifíed, at least 3 of which were necessary for activity. The biphasic response of the Crassula enzyme was dependent on the concentration of DEPC. Progressively less inactivation was observed when modifying the enzyme with lower concentrations of DEPC. Chemical modification of PEPC with 75 pM DEPC resulted in a form of the enzyme with a lower K^, and higher This was concomitant with the modification of 4 histidines per subímit. Changes in the response of the enzyme to allosteric effectors were also observed; with modification the enzyme was desensitized to malate inhibition and glucose-6-phosphate activation. The Kj of the modifíed enzyme for malate increased over 15-fold. This was consistent with fluorescence binding studies using the extrinsic conformationalprobe S-anilino-l-naphthalenesulfonate which indicated the elimination of binding of malate and increased binding of the substráte to PEPC. Protection studies showed that malate desensitization was delayed by the presence of malate during modification. Malate also slowed the initial rate of histidine modifícation as measured spectrophotometrically. Thus histidine plays a role in the malate site of Crassula PEPC.