The electro-ultrasonic spectroscopy was used as a non-destructive testing method for the magnesium composites evaluation. AC current varying with frequency fE and the ultrasonic signal varying with frequency fU are applied on the conducting sample and a new intermodulation signal on the frequency f m given by the superposition or subtraction of exciting frequencies is measured on the sample. We have measured on intermodulation frequency fm = fE – fU. This method can be used as a diagnostic tool for the quality and reliability assessment. The sample resistance is influenced by the ultrasonic signal. The ultrasonic signal changes the contact area between the conducting grains in the sample structure and then resistance is modulated by the frequency of ultrasonic excitation. The electrical charge and also the electrical current flowing through the sample structure are conserved. In case the contact area between the conducting grains is changing then the current density is changed. This leads to the resistivity change of measured structure. We suppose that for the sample with more defects in the structure the influence of the ultrasonic signal is more pronounced and the resistance change is higher. and Pomocí elektro-ultrazvukové nedestruktivní spektroskopie byl testován vzorek z hořčíkové slitiny. Tato metoda je založena na střídavém elektrickém proudu o frekvenci f e, který prochází vzorkem a ultrazvukovým vlněním o frekvenci f U. Na rozdílové a součtové frekvenci těchto dvou signálů vzniká nový intermodulační signál f m. Velikost tohoto signálu je závislá jak na velikosti budicích signálů, tak na struktuře testovaného materiálu a celkových defektech obsažených ve vzorku. rezistivita materiálu se mění v závislosti na ultrazvukovém vlnění. Ultrazvukový signál mění oblast kontaktu mezi vodivými zrny ve struktuře materiálu s frekvencí ultrazvukového vlnění f U. Tímto se mění proudová hustota ve vzorku, protože elektrický náboj a proud procházející vzorkem jsou konstantní. Předpokládáme, že vzorky, které obsahují více defektů ve své struktuře, budou mít vyšší hodnotu změny odporu než vzorky bez defektů.
One of the significant limiting complications of paclitaxel is
painful peripheral neuropathy during its therapy for several types
of cancers. Our recent study showed that impairment of
Nrf2-antioxidant response element (Nrf2-ARE) and upregulation
of oxidative signals in the dorsal root ganglion (DRG) of rats with
treatment of paclitaxel result in neuropathic pain. The purpose of
this study was to examine the beneficial role played by
electroacupuncture (EA) in modifying neuropathic pain evoked by
paclitaxel via Nrf2-ARE and oxidative mechanisms. Behavioral
test was performed to determine mechanical and thermal
sensitivity in rats. Western Blot analysis and ELISA were used to
examine expression of Nrf2-ARE and superoxide dismutases
(SOD); and the levels of products of oxidative stress in the DRG.
Our data showed that paclitaxel increased mechanical and
thermal sensitivity and this was accompanied with impaired
Nrf2-ARE and SOD in the DRG and amplified products of
oxidative stress (i.e. 8-isoprostaglandin F2α and 8-hydroxy-2’-
deoxyguanosine). EA treatment largely restored the levels of
Nrf2-ARE/SOD and inhibited products of oxidative stress and
thereby attenuated mechanical and thermal hypersensitivity
induced by paclitaxel. In conclusion, we revealed specific
signaling pathways leading to paclitaxel-evoked neuropathic pain,
including impairment of Nrf2-ARE and heightened oxidative
signals. We further provided evidence for the role of EA in
alleviating paclitaxel-neuropathic pain via these molecular
mediators.
An increased risk of myocardial ischemic changes was demonstrated in patients suffering from panic disorder (PD). Using classical ECG methods, this risk cannot be evaluated in most patients. We measured the vectocardiogram (VCG) using Frank orthogonal leads and body surface maps (BSM) including 12-lead ECG. In our study of 11 PD patients (2 men, 9 women), without any seizures and pharmacological treatment and without cardiovascular symptoms, we found marked sinus tachycardia (heart rate 90.1±12.2 min-1) and a shorter R-R interval (678±93.6 ms) than in 27 controls (heart rate 73.6±7.7min-1, R-R 822.7±86.4 ms) (5 men, 22 women) (p<0.001). The VCG measured spatial QRS-STT angle was more opened (70.3±24.5°) than in the control group (49.5±19.5°) (p<0.05). The maximum (extremum) in depolarization (DIAM max 30, 40) and repolarization (RIAM max 35) of body surface isoarea and isointegral (RIIM max) maps was less positive (p<0.001) and the minimum (DIAM min 40) was less negative than in the controls (p<0.05) even in the period free of a panic attack. Our results showed the changes in the heart electric field parameters occurred in PD patients when compared to the control group., K. Pišvejcová, I. Paclt, J. Slavíček, O. Kittnar, A. Dohnalová, E. Kitzlerová., and Obsahuje bibliografii
Diabetes mellitus (DM) has been known for many years to be associated with poor cardiovascular prognosis. Due to the sensitive neuropathy, the coronary artery disease in diabetic patients is frequently asymptomatic. Also twelve leads resting ECG can be within normal limits even in an advanced stage of coronary artery disease. Therefore in addition to the standard ECG other electrocardiographic procedures started to be studied in order to find some typical signs of myocardial damages caused by DM. Repeatedly reported results showed in DM patients without cardiovascular complications the tachycardia, shortening of the QRS and QT intervals, increase of the dispersion of QT interval, decreased amplitudes of depolarization waves, shortened activation time of ventricular myocardium and a flattening of T waves confirmed by the lower value of maximum and minimum in repolarization body surface isopotential maps. Most of these changes are even more pronounced in patients with cardiac autonomic neuropathy. Comparison with similar ECG changes in other diseases suggests that the electrocardiographic changes in DM patients are not specific and that they are particularly caused by an increased tone of the sympathetic nervous system what was indirectly confirmed by the heart rate variability findings in these patients., O. Kittnar., and Obsahuje bibliografii
Tricyclic antidepressant drugs dosulepine (TCA), serotonin selective reuptake inhibitor (SSRI) and prophylactic agent with antidepressant effect lithium carbonicum (Li) have different cardiovascular side-effects. We compared them in the prophylactic therapy of periodic affective disorder in remission with TCA, SSRI and Li. Our previous papers confirmed the most prominent effects of heart electric field parameters in TCA patients (Slavíček et al. 1998). In the present work we studied for the first time the dose-dependent changes of ECG, body surface potential maps (BSPM - parameter DIAM 30, 40) in 43 TCA dosulepine, 40 SSRI citalopram and 30 Li outpatients (Hamilton scale: HAMD£10; age 40±5 years; treated for depressive disorders or bipolar disorders). The daily doses of dosulepine were 50-250 mg, citalopram 20-80 mg, Li plasma levels 0.66±0.08 meq/l. The electrocardiogram (ECG), vectorcardiogram (VCG), and BSPM were measured and calculated by the Cardiag 112.1 diagnostic system. The results have shown a relation between the dose of dosulepine and extremum (maximum and minimum) of depolarization isoarea map in dosulepine, but not in citalopram patients. The repolarization BSPM changes were most pronounced in SSRI patients. Lithium in long-term prophylaxy (1-22 years) caused only minimal ECG BSPM changes. The present results correspond with our previous observations., I. Paclt, J. Slavíček, A. Dohnalová, E. Kitzlerová, K. Pišvejcová., and Obsahuje bibliografii
Cardiac resynchronization therapy (CRT) has proven efficacious in reducing or even eliminating cardiac dyssynchrony and thus improving heart failure symptoms. However, quantification of mechanical dyssynchrony is still difficult and identification of CRT candidates is currently based just on the morphology and width of the QRS complex. As standard 12-lead ECG brings only limited information about the pattern of ventricular activation, we aimed to study changes produced by different pacing modes on the body surface potential maps (BSPM). Total of 12 CRT recipients with symptomatic heart failure (NYHA II-IV), sinus rhythm and QRS width ≥120 ms and 12 healthy controls were studied. Mapping system Biosemi (123 unipolar electrodes) was used for BSPM acquisition. Maximum QRS duration, longest and shortest activation times (ATmax and ATmin) and dispersion of QT interval (QTd) were measured and/or calculated during spontaneous rhythm, single-site right- and left-ventricular pacing and biventricular pacing with ECHO-optimized AV delay. Moreover we studied the impact of CRT on the locations of the early and late activated regions of the heart. The average values during the spontaneous rhythm in the group of patients with dyssynchrony (QRS 140.5±10.6 ms, ATmax 128.1±10.1 ms, ATmin 31.8±6.7 ms and QTd 104.3±24.7 ms) significantly
differed from those measured in the control group (QRS 93.0±10.0 ms, ATmax 79.1±3.2 ms, ATmin 24.4±1.6 ms and QTd 43.6±10.7 ms). Right ventricular pacing (RVP) improved significantly only ATmax [111.2±10.6 ms (p<0.05)] but no other measured parameters. Left ventricular pacing (LVP) succeeded in improvement of all parameters [QRS 105.1±8.0 ms (p<0.01), ATmax 103.7±7.1 ms (p<0.01), ATmin 20.2±3.7 ms (p<0.01) and QTd 52.0±9.4 ms (p<0.01)]. Biventricular pacing (BVP) showed also a beneficial effect in all parameters [QRS 121.3±8.9 ms (p<0.05), ATmax 114.3±8.2 ms (p<0.05), ATmin 22.0±4.1 ms (p<0.01) and QTd 49.8±10.0 ms (p<0.01)]. Our results proved beneficial outcome of LVP and BVP in evaluated parameters (what seems to be important particularly in the case of activation times) and revealed a complete return of activation
times to normal distribution when using these CRT modalities.
Electrocardiography (ECG) in rats is a widely applied experimental method in basic cardiovascular research. The technique of ECG recordings is simple; however, the interpretation of electrocardiographic parameters is challenging. This is because the analysis may be biased by experimental
settings, such as the type of anesthesia, the strain or age of animals. Here, we aimed to review electrocardiographic parameters in rats, their normal range, as well as the effect of experimental settings on the parameters variation. Furthermore, differences and similarities between rat and human ECG are discussed in the context of translational cardiovascular research.
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