Proper classification of action potentials from extracellular recordings is essential for making an accurate study of neuronal behavior. Many spike sorting algorithms have been presented in the technical literature. However, no comparative analysis has hitherto been performed. In our study, three widely-used publicly-available spike sorting algorithms (WaveClus, KlustaKwik, OSort) were compared with regard to their parameter settings. The algorithms were evaluated using 112 artificial signals (publicly available online) with 2-9 different neurons and varying noise levels between 0.00 and 0.60. An optimization technique based on Adjusted Mutual Information was employed to find near-optimal parameter settings for a given artificial signal and algorithm. All three algorithms performed significantly better (p<0.01) with optimized parameters than with the default ones. WaveClus was the most accurate spike sorting algorithm, receiving the best evaluation score for 60% of all signals. OSort operated at almost five times the speed of the other algorithms. In terms of accuracy, OSort performed significantly less well (p<0.01) than WaveClus for signals with a noise level in the range 0.15-0.30. KlustaKwik achieved similar scores to WaveClus for signals with low noise level 0.00-0.15 and was worse otherwise. In conclusion, none of the three compared algorithms was optimal in general. The accuracy of the algorithms depended on proper choice of the algorithm parameters and also on specific properties of the examined signal.

• MeSH
• akční potenciály fyziologie   MeSH
• algoritmy MeSH
• elektrofyziologie metody   MeSH
• lidé MeSH
• neurony fyziologie   MeSH
• počítačové zpracování signálu MeSH
• validace softwaru MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• validační studie MeSH

Fetal phonocardiography is a non-invasive, completely passive and low-cost method based on sensing acoustic signals from the maternal abdomen. However, different types of interference are sensed along with the desired fetal phonocardiography. This study focuses on the comparison of fetal phonocardiography filtering using eight algorithms: Savitzky-Golay filter, finite impulse response filter, adaptive wavelet transform, maximal overlap discrete wavelet transform, variational mode decomposition, empirical mode decomposition, ensemble empirical mode decomposition, and complete ensemble empirical mode decomposition with adaptive noise. The effectiveness of those methods was tested on four types of interference (maternal sounds, movement artifacts, Gaussian noise, and ambient noise) and eleven combinations of these disturbances. The dataset was created using two synthetic records r01 and r02, where the record r02 was loaded with higher levels of interference than the record r01. The evaluation was performed using the objective parameters such as accuracy of the detection of S1 and S2 sounds, signal-to-noise ratio improvement, and mean error of heart interval measurement. According to all parameters, the best results were achieved using the complete ensemble empirical mode decomposition with adaptive noise method with average values of accuracy = 91.53% in the detection of S1 and accuracy = 68.89% in the detection of S2. The average value of signal-to-noise ratio improvement achieved by complete ensemble empirical mode decomposition with adaptive noise method was 9.75 dB and the average value of the mean error of heart interval measurement was 3.27 ms.

• MeSH
• algoritmy MeSH
• fonokardiografie metody   MeSH
• počítačové zpracování signálu * MeSH
• poměr signál - šum MeSH
• vlnková analýza * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• iontová výměna MeSH
• kolon cytologie   fyziologie   MeSH
• krysa rodu rattus MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare hereditary arrhythmia. The onset of clinical symptoms usually occurs during childhood, and is typically related to exercise. The aim of our study was to describe the clinical characteristics of seven Czech families with CPVT and the results of mutational analysis of the RyR2 gene in these families. METHODS: The subjects and their relatives were investigated at the participating departments. They underwent basic clinical investigation, and history was focused on possible CPVT symptoms, that is, syncopes during exercise. Bicycle ergometry was performed to obtain electrocardiogram recording during adrenergic stimulation. In all the investigated individuals, blood samples were taken for mutation analysis of the RyR2 gene. RESULTS: To date, seven families have been investigated, comprising 11 adults and 13 children. In seven CPVT patients, the indication for examination was syncope during exercise. Diagnosis was confirmed by bicycle ergometry-induced polymorphic ventricular tachycardia. In one relative, polymorphic ventricular tachycardia was also induced. All eight affected individuals were treated with β-blockers and in two, a cardioverter-defibrillator was implanted due to recurrent syncopi. Coding variants of the RyR2 gene were found in four probands. CONCLUSIONS: This is a systematic description of CPVT families in the Czech Republic. Our data support the importance of exercise testing for the diagnosis of CPVT. In addition, RyR2 gene coding variants were found in 50% of affected individuals.

• MeSH
• dítě MeSH
• dospělí MeSH
• genetická predispozice k nemoci genetika   MeSH
• heterozygot MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• komorová tachykardie diagnóza   genetika   MeSH
• lidé MeSH
• mladý dospělý MeSH
• mutace genetika   MeSH
• rodokmen MeSH
• ryanodinový receptor vápníkového kanálu genetika   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel contains 12 transmembrane (TM) regions that are presumed to form the channel pore. However, there is no direct evidence clearly illustrating the involvement of these transmembrane regions in the actual CFTR pore structure. To obtain insight into the architecture of the CFTR channel pore, we used patch clamp recording techniques and a strategy of co-mutagenesis of two potential pore-forming transmembrane regions (TM1 and TM6) to investigate the collaboration of these two TM regions. We performed a range of specific functional assays comparing the single channel conductance, anion binding, and anion selectivity properties of the co-mutated CFTR variants, and the results indicated that TM1 and TM6 play vital roles in forming the channel pore and, thus, determine the functional properties of the channel. Furthermore, we provided functional evidence that the amino acid threonine (T338) in TM6 has synergic effects with lysine (K95) in TM1. Therefore, we propose that these two residues have functional collaboration in the CFTR channel pore and may collectively form a selective filter.

• MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• křečci praví MeSH
• membránové potenciály * MeSH
• metoda terčíkového zámku MeSH
• mutageneze cílená MeSH
• protein CFTR genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Extracellular microelectrode recording (MER) is a prominent technique for studies of extracellular single-unit neuronal activity. In order to achieve robust results in more complex analysis pipelines, it is necessary to have high quality input data with a low amount of artifacts. We show that noise (mainly electromagnetic interference and motion artifacts) may affect more than 25% of the recording length in a clinical MER database. NEW METHOD: We present several methods for automatic detection of noise in MER signals, based on (i) unsupervised detection of stationary segments, (ii) large peaks in the power spectral density, and (iii) a classifier based on multiple time- and frequency-domain features. We evaluate the proposed methods on a manually annotated database of 5735 ten-second MER signals from 58 Parkinson's disease patients. COMPARISON WITH EXISTING METHODS: The existing methods for artifact detection in single-channel MER that have been rigorously tested, are based on unsupervised change-point detection. We show on an extensive real MER database that the presented techniques are better suited for the task of artifact identification and achieve much better results. RESULTS: The best-performing classifiers (bagging and decision tree) achieved artifact classification accuracy of up to 89% on an unseen test set and outperformed the unsupervised techniques by 5-10%. This was close to the level of agreement among raters using manual annotation (93.5%). CONCLUSION: We conclude that the proposed methods are suitable for automatic MER denoising and may help in the efficient elimination of undesirable signal artifacts.

• MeSH
• artefakty * MeSH
• evokované potenciály fyziologie   MeSH
• Fourierova analýza MeSH
• hluk MeSH
• lidé MeSH
• mikroelektrody škodlivé účinky   MeSH
• mozek cytologie   MeSH
• neurony fyziologie   MeSH
• počítačové zpracování signálu * MeSH
• support vector machine MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The most frequent hereditary hearing loss is caused by mutations in the GJB2 gene coding for the gap junction beta 2 protein Connexin 26 (Cx26). In contrast to many studies performed in patients with bi-allelic mutations, audiometric studies on heterozygotes are sparse and often contradictory. To evaluate hearing function in heterozygous carriers of the GJB2 c.35delG mutation, audiometry over the extended frequency range and the recording of otoacoustic emissions (OAEs), i.e., transient-evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs), were performed in a group of parents and grandparents of deaf children homozygous for the GJB2 c.35delG mutation. The comparison of audiograms between control and heterozygous subjects was enabled using audiogram normalization for age and sex. Hearing loss, estimated with this procedure, was found to be significantly larger in GJB2 c.35delG heterozygous females in comparison with controls for the frequencies of 8-16 kHz; the deterioration of hearing in heterozygous men in comparison with controls was not statistically significant. A comparison of TEOAE responses and DPOAE levels between GJB2 c.35delG heterozygotes and controls did not reveal any significant differences. The results prove the importance of using audiometry over the extended frequency range and audiogram normalization for age and sex to detect minor hearing impairments, even in a relatively small group of subjects of different ages.

• MeSH
• dospělí MeSH
• genetická predispozice k nemoci genetika   MeSH
• genetické markery genetika   MeSH
• heterozygot * MeSH
• incidence MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• konexiny genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace genetika   MeSH
• percepční nedoslýchavost diagnóza   epidemiologie   patofyziologie   MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• sluchové testy statistika a číselné údaje   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

N-methyl-D-aspartate (NMDA) receptors are highly expressed in the CNS, mediate the slow component of excitatory transmission and play key roles in synaptic plasticity and excitotoxicity. These ligand-gated ion channels are heteromultimers composed of NR1 and NR2 subunits activated by glycine and glutamate. In this study, patch-clamp recordings were used to study the temperature sensitivity of recombinant NR1/NR2B receptors expressed in human embryonic kidney (HEK) 293 cells. Rate constants were assessed by fitting a six-state kinetic scheme to time courses of transient macroscopic currents induced by glutamate at 21.9-46.5 degrees C. Arrhenius transformation of the rate constants characterizing NMDA receptor channel activity indicates that the most sensitive were the rate constants of desensitization (temperature coefficient Q(10)=10.3), resensitization (Q(10)=4.6) and unbinding (Q(10)=3.6). Other rate constants and the amplitude of single-channel currents were less temperature sensitive. Deactivation of responses mediated by NR1/NR2B receptors after a brief application of glutamate was best fit by a double exponential function (tau(fast): Q(10)=3.7; tau(slow): Q(10)=2.7). From these data, we conclude that desensitization/resensitization of the NMDA receptor and glutamate unbinding are especially temperature sensitive and imply that at physiological temperatures the channel kinetics play an important role in determining amplitude and time course of NMDA receptor-mediated postsynaptic currents and these receptors mediated synaptic plasticity.

• MeSH
• algoritmy MeSH
• buněčné linie MeSH
• elektrofyziologie MeSH
• financování organizované MeSH
• gating iontového kanálu fyziologie   MeSH
• kinetika MeSH
• kyselina glutamová metabolismus   MeSH
• ledviny cytologie   metabolismus   MeSH
• lidé MeSH
• metoda terčíkového zámku MeSH
• receptory N-methyl-D-aspartátu fyziologie   genetika   účinky léků   MeSH
• rekombinantní proteiny MeSH
• statistické modely MeSH
• techniky in vitro MeSH
• teplota MeSH
• transfekce MeSH
• Check Tag
• lidé MeSH

Muscle coordination during periodic movements is often studied using the average envelope of the electromyographic (EMG) signal. We show that this method causes a loss of important information, and potentially gives rise to errors in analysis of muscle activity coordination. We created four simulated two-channel surface EMG signals, in order to compare the results of muscle onset/cessation detection, performed on the average EMG envelope and the EMG envelopes in every single movement cycle. Our results show that the common method using the average EMG envelope is unable to reveal certain important characteristics of the EMG signals, while the analysis performed on individual cycles accentuates this information. This ability was verified on 16-channel surface EMGs obtained during walking and cycling. By detecting muscle activity in individual movement cycles, we could observe fine changes in muscle coordination. Moreover, muscles with questionable reliability of activity detection were distinguished and highlighted in the presented summary figures. In the second part of the paper, our publicly available set of MATLAB files for surface EMG signal processing is described.

• MeSH
• cyklistika fyziologie   MeSH
• elektromyografie metody   MeSH
• kosterní svaly fyziologie   MeSH
• lidé MeSH
• počítačová simulace MeSH
• počítačové zpracování signálu * MeSH
• svalová kontrakce fyziologie   MeSH
• uživatelské rozhraní počítače MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Patch clamp method developed more than 30 years ago is widely used for investigation of cellular excitability manifested as transmembrane ionic current and/or generation of action potentials. This technique could be applied to measurement of ionic currents flowing through individual (single) ion channels or through the whole assembly of ion channels expressed in the whole cell. Whole cell configuration is more common for measurement of ion currents and the only one enabling measurement of action potentials. This method allows detailed analysis of mechanisms and structural determinants of voltagedependent gating of ion channels as well as regulation of channel activity by intracellular signaling pathways and pharmacological agents.

• MeSH
• akční potenciály MeSH
• biologické modely MeSH
• buněčná membrána metabolismus   MeSH
• financování organizované MeSH
• gating iontového kanálu MeSH
• iontové kanály metabolismus   MeSH
• lidé MeSH
• membránové potenciály MeSH
• metoda terčíkového zámku MeSH
• vápníková signalizace MeSH
• vápníkové kanály - typ T metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• přehledy MeSH