We studied the ability of the ECG to detect pathological changes in isoproterenol-induced remodeling of rat heart. Myocardial hypertrophy in rats was induced by repeated injections of isoproterenol (5 mg/kg s.c. 7 days, Iso5, n=7). Single overdose of isoproterenol (150 mg/kg s.c., Iso150, n=7) evoked myocardial infarction followed with ventricular remodeling. The electrocardiograms were recorded in anesthetized animals (thiopenthal 45 mg/kg i.p.) and myocardial contractile performance was analyzed in isolated hearts perfused according to Langendorff. The hypertrophic hearts were characterized by increased heart and left ventricular (LV) weight as well as by thicker LV free wall and interventricular septum. Mean values of LV contraction did not significantly differ from controls. Longer QT interval, QRS complex, negative Q and S waves, higher R amplitude were typical characteristics for Iso5 rats. Iso150 animals showed tendency to decreased systolic blood pressure and heart frequency. Decrease in the thickness of LV compared to Iso5 as well as impaired LV function were related to the dilated left ventricle. Iso150 ECG showed longer QRS and QT, deepened negativity of S wave and mild decrease of RII compared to Iso5. Voltage criteria showed that Sokolow-Lyon index is a good predictor of left ventricular hypertrophy in isoproterenol-induced cardiac remodeling without systemic hypertension., E. Kráľová, T. Mokráň, J. Murín, T. Stankovičová., and Obsahuje bibliografii a bibliografické odkazy
Electrode migration is the most common complication of spinal
cord stimulation (SCS). The problem of longitudinal migration has
already been solved, but lateral migration remains the most
common current complication. The present article describes new
electrodes fixation opportunities for the reduction of lateral
migration in SCS. The pig was chosen as an animal model to
illustrate a new protocol of electrode fixation for the control of
lateral and longitudinal migration. The displacement of the
electrode was measured using two different optical methods: the
digital image stereo-correlation and the digital image processing
methods. Fixation with two anchors has always considerably
reduced electrode displacement and when fixation is done with two
anchors and a loop then lateral migration is reduced by 62.5 %
and longitudinal migration is reduced by 94.1 %. It was shown that
the results are significantly different at the α=0.001 significance
level. Based on a statistical evaluation it is possible to state that the
differences between experimental results obtained for three
different protocols of lead fixation are statistically significant and
we can recommend the new fixation method for common practice.
This paper is devoted to yet unpublished electrode-less methods (ELM) of cell layers impedance measurement based on transformer principle. The main advantage of ELM is elimination uncertainties caused by interface between electrodes and measured electrolyte. The method of avoiding distortion caused by non-ideal transformer transfer function (“deconvolution”) and errors caused by residual voltage is described. The modification of original transformer based method allowing to measure an impedance of inserted object is proposed. Results of several calibration measurements confirming the proper function of ELM including example of transepithelial resistance of cells layer are presented. Crucial parts of measuring system and recommendation for their realization are included., J. Krůšek, S. Ďáďo., and Obsahuje bibliografii
To evaluate the direct effects of a barbiturate on cerebral functions without its influence on brain perfusion pressure, circulatory hormones and metabolites, the electroencephalogram (EEG) was studied in the isolated rat head. Male Wistar rats were anesthetized, and EEG electrodes were inserted into the cranium. A Krebs-Ringer bicarbonate buffer solution containing heparinized rat whole blood, 20 mmol/l glucose, 200 mmol/l mannitol and 0.1 mg/ml dexamethasone was used for the perfusate. The bilateral common carotid arteries were cannulated, pumped at a rate of 6 ml/min and the head was isolated. The venous effluent was reoxygenated and recirculated into the brain. Twenty-five min after isolation of the heads pentobarbital was added to the perfusate at concentrations of 0.1, 0.5 and 2.5 mg/ml. EEG was recorded before and during perfusion. EEG activity could be recorded for more than 25 min after the beginning of perfusion. EEG activity gradually declined from 42±5 μV before perfusion (in vivo) to 4±1 μV at 25 min after the beginning of perfusion. Then, 3 min after the addition of pentobarbital, the EEG activity became significantly higher in the high dose groups; 12±3 μV in the 0.5 mg/ml group (p<0.05) and 12±1 μV in 2.5 mg/ml group (p<0.05) compared with the group without pentobarbital (2±2 μV). The present study suggests that a barbiturate has mitigating effects on the brain damage induced by the in vitro brain perfusion., A. Tagawa, O. Mokuda, Y. Sakamoto, N. Shimizu., and Obsahuje bibliografii
This paper represents the Romanian contribution in the frame of the European Co-operation "COST ACTION 625" and it is centered on an electromagnetic methodology for the natural hazard assessment due to both the seismic events and associated active faults which are considered to be sources of the most significant landslides in the Subcarpathian area (Romania). This methodology was established according to the geotectonic features of the seismic-active Vrancea zone and Provita de Sus landslide area. Subsequently, a specific approach regarding the electromagnetic precursory parameters, selected according to the temporal invariability criterion for a 2D geoelectric structure in non-seismic condition, taking into consideration their daily mean distribution versus intermediate depth seismic events recorded simultaneously, was elaborated. A similar electromagnetic technique conveying to additional parameters and models concerning the evolution in time of the landslide phenomena was also imposed, so that a disaster forecasting become possible., Dumitru Stanica and Maria Stanica., and Obsahuje bibliografii
In the mammalian autonomic nervous system, tonic and phasic neurons can be differentiated on firing patterns in response to long depolarizing current pulse. However, the similar firing patterns in the somatic primary sensory neurons and their functional significance are not well investigated. Here, we identified two types of neurons innervating somatic sensory in rat dorsal root ganglia (DRG). Tonic neurons fire action potentials (APs) in an intensity-dependent manner, whereas phasic neurons typically generate only one AP firing at the onset of stimulation regardless of intensity. Combining retrograde labeling of somatic DRG neurons with fluorescent tracer DiI, we further find that these neurons demonstrate distinct changes under inflammatory pain states induced by complete Freund’s adjuvant (CFA) or bee venom toxin melittin. In tonic neurons, CFA and melittin treatments significantly decrease rheobase and AP durations (depolarization and repolarization), enhance amplitudes of overshoot and afterhyperpolarization (AHP), and increase the number of evoked action potentials. In phasic neurons, however, the same inflammation treatments cause fewer changes in these electrophysiological parameters except for the increased overshoot and decreased AP durations. In the present study, we find that tonic neurons are more hyperexcitable than phasic neurons after peripheral noxious inflammatory stimulation. The results indicate the distinct contributions of two types of DRG neurons in inflammatory pain., Y.-Q. Yu, X.-F. Chen, Y. Yang, F. Yang, J. Chen., and Obsahuje bibliografii
Elektrická vodivost v zemské kůře závisí jen málo na konkrétním horninovém složení geologických útvarů, často však velmi citlivě indikuje zóny s anomálními geochemickými a termodynamickými podmínkami či zóny mechanického porušení horninového prostředí. Elektromagnetická pole indukovaná přirozenými variacemi zemského magnetického pole extraterestrického původu a měřená na povrchu Země umožňují vymezit tyto anomální zóny v měřítku celé zemské kůry, a rovněž hlouběji v zemském plášti. Magnetotelurický a magnetovariační výzkum, který z těchto poznatků vychází, se tak stává cenným zdrojem geofyzikální informace o vnitrozemském prostředí. Elektrický model zemské kůry na přechodu mezi Českým masivem a Západními Karpatami zřetelně ukazuje, jak povrchová geologická stavba pokračuje v hlubinných změnách v rozložení elektrické vodivosti v rámci jednotlivých regionálních geologických jednotek., Josef Pek., and Obsahuje seznam literatury
Electrical properties of agricultural products depend on the distribution and transport of electric charges occurring in their structure. Light is electromagnetic radiation with a wavelength corresponding to a photon energy of few electron volts. From a first principal‘s point of view, electrical properties of agricultural products can be diveded into two fundamentally different groups, i.e. active and passive electric properties. Passive electrical properties are very close to the electrical properties of non-living objects, which react with the presence of an electromagnetic field at the lowest, i.e. atomic and particularly molecular levels. These properties are very important from an engineering point of view. The methods of measurement of these properties and the obtained data represent the main content of this contribution., Jiří Blahovec., and Obsahuje rozsáhlý seznam literatury