Κυριακή, 28 Οκτωβρίου 2018

Cerebral Evoked Potentials in Patients at an Early Stage of Schizophrenia

Visual and auditory EPs (with special attention to their cognitive components) were examined in 33 patients with newly diagnosed schizophrenia (a group of patients, Pat; all subjects obtained supporting pharmacotherapy) and 30 mentally healthy subjects (a control group, Contr). Reversive chess patterns with the squares of 60 or 120 ang. sec were used as stimuli in the case of visual EPs, while tones of different frequencies, 1.0 and 4.0 kHz, were used for initiation of auditory EPs. The odd-ball paradigm was used; the probabilities of significant stimuli (i.e., signals) at each sensory modality were 20 or 50%. The amplitudes and latencies of generally differentiated EP components, with special attention to the P1, N1, P2, N2, P3 (P300), and N4 waves, were measured; in addition, the latencies (times) of sensorimotor reactions (SMRs) to presentation of the signal stimuli (pushing the button) were recorded. The averaged latencies of visual N1, P2, N2, P300, and N4 (at the 50% probability) and of N2, P300, and N4 (20% probability) in patients with schizophrenia were significantly longer than those in the control. Besides, the amplitudes of visual P2 and N2 (50% probability) and of P2, P300, and N4 (20% probability) were significantly lower than in the control. At auditory stimulation, the latencies of nearly all EP components in the Pat group at both 50 and 20% probabilities of significant stimuli were longer that in the norm, but the differences did not reach the significance level. The amplitudes of components P1–N2 in auditory EPs at the 50% probability were significantly lower than in the control. Significantly longer latencies (times) of the SMRs were observed in the Pat group at both auditory and visual stimulation and at both probabilities of significant stimuli. It is concluded that the cognitive deficit in patients with schizophrenia is probably more clearly reflected in the parameters of visual EPs, while changes in the positive symptoms of this disease are more reflected in the parameters of auditory EPs.



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Automated Diagnosis of Encephalopathy Based on Empirical Mode EEG Decomposition

In this study, an empirical mode decomposition (EMD) technique has been applied for EEG signals to identify a neurological disease state qualified as encephalopathy. The EMD technique is an efficient method for decomposing nonstationary and nonlinear signals, which makes it suitable for biosignal processing. This technique generates various components of the signal called intrinsic mode functions (IMFs) whose features are examined for the diagnosis of the disease. We found significant differences between the healthy and patient groups for both statistical and nonlinear parameters of IMFs of the recorded EEGs, which makes those suitable for the diagnosis of encephalopathy. Statistical values, namely minimum, maximum, mean, and standard deviation, and nonlinear parameters, namely approximate entropy and sample entropy of the IMFs, were calculated. Both these features were fed to a Support Vector Machine (SVM) classifier, and their performance parameters were evaluated. It is concluded that statistical parameters, as well as nonlinear parameters of the EEG IMFs, are prospective potential features for automated diagnosis of encephalopathy.



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Doxorubicin-Induced Cardiomyopathy in Rats: Behavior of the Animals in the Open Field

Under conditions of the open field test, 30 control Wistar rats and 30 rats with experimental cardiomyopathy (CMP) were examined with recording of four behavioral indices, (i) number of crossed squares (intensity of locomotion), (ii) number of rearings (vertical stands), (iii) number of examined holes in the arena, and (iv) number of grooming episodes, within a 28-day-long observation period. The CMP state was induced by five i.p. injections of 5.0 mg/kg of doxorubicin with one-week-long intervals. As was found, all behavioral indices of control rats demonstrated considerable (sometime statistically significant) variations within the observation period (this fact has probably attracted insufficient attention in analogous experiments with long-lasting observation periods). The development of doxorubicininduced CMP resulted in considerable suppression of all types of behavioral activity, relatively moderate within the first week of observation and dramatic within late phases of the observation period. The dynamics of the numbers of rearings and grooming phenomena were complex, with noticeable increases on days 3 and 14. The dynamics of the numbers of rearings and inspection of the holes in both experimental groups were significantly dissimilar, which indicates that these behavioral phenomena are related to different aspects of the research/orientatinal activity. In general, a state of increased anxiety followed by the development of a depression-like state was observed in CMP rats. These negative shifts in behavioral activity are believed to result from general CMP-induced insufficiency of blood supply of the brain and development of hypoxia in the latter; specific direct effects of doxorubicin on some cerebral structures seem to be unlikely.



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Functional Connections in the Human Cerebral Cortex at Repetitive Flexions and Extensions of the Fingers

In 10 subjects, EEGs were recorded during realization of repetitive movements of the fingers of the dominant hand and production of the static efforts by the fingers. The test included four stages: resting state, the maintenance of the fingers in the maximally extended fingers and those squeezed into a fist, and repetitive flexions/extensions of the fingers. Values of the spectral power of the α and β EEG rhythms and levels of coherence of oscillations in different leads were measured. As was found, repetitive movements of the fingers are accompanied by significant increases in values of the hyperbolic coherence spectrum between a number of the central and frontal leads of the neocortex. The patterns of the respective changes for the α and β rhythms significantly differed from each other. It is concluded that the control of repetitive finger movements is not based on a mechanism of the central pattern generators; such finger movements should be more adequately interpreted as a consequence of the discrete voluntary movements.



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Sympathetic Nerve Activity-Induced Blood Pressure Fluctuations are Stacked on Linearly: A Simulation Study

A possible mechanism to fit the empirical relationship between the power spectrum of the variability of sympathetic nerve activity (PSNA) and blood pressure (PBP) is described. Since the BP rise depends on the magnitude of SNA with an S-mode relationship, we assume that a single BP rise is independent of the SNA frequency, while two successive SNA-induced BP fluctuations are stacked on linearly. The damping function was used to model the BP fluctuations caused by SNA, and the box function was used to model the SNA compound action potential. We quantified the logistic relationship (PSNA = cPBP ∙ 10kf) between the frequency and power spectrum of these two functions. The simulation data showed the physiological rationality of the empirical relationship between the PSNA and PBP and supported the assumption that the BP stack-on is linear and independent of the SNA frequency.



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Polymorphism of the DRD2 Gene in a Mexican Population with Mental Deviations

The important functions of dopamine (DA) in emotional behavior, control of voluntary movements, memory, and attention have been recognized. To date, the 939 C/T (rs6275) polymorphism of this gene has been implicated in association with alcohol and drug abuse and also with schizophrenia. We examined the allele frequencies of 939CT (rs6275) polymorphism of the DRD2 gene and those of the respective genotypes in a Mexican population (n = 166) with mental deviations and a history of suicide attempts and psychiatric diagnoses (101 suicidal individuals from Mexico City and 65 patients recruited from psychiatry outpatients of Tabasco, México). The most common allele found in both subpopulations was the T allele (about 60% and 69%, respectively). In addition to the Mexican population, the frequencies were compared with those in some Asian and American populations. Thus, a noticeable difference of the distribution of the 939 C/T (rs6275) was observed in patients with the above-mentioned mental deviations, as well as in the Asian population with a diagnosis of schizophrenia. Future studies are necessary to evaluate mentally unhealthy populations to observe the role of the above polymorphism in the susceptibility to psychiatric diseases.



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Expression of α7 Nicotinic ACh Receptors in Blood Mononuclear Cells: Correlation with Impaired Baroreflex Sensitivity in Patients with Heart Failure

Autonomic imbalance, including depleted parasympathetic drive, is a fundamental pathophysiological feature of heart failure (HF). In clinical studies, parasympathetic withdrawal is assessed using arterial baroreflex sensitivity (BRS). Parasympathetic activity can also be tracked based on the assessment of molecular elements of cholinergic signaling in target cells. Hence, we investigated whether BRS is associated with the mRNA expression of nicotinic cholinergic receptors (α7nAChR) in peripheral blood mononuclear cells (PBMCs) in subjects with and without HF. We examined 39 patients with stable systolic HF (35 men, 4 women, age 56 ± 13 years, left ventricular ejection fraction, LVEF, 30 ± 9%) and 17 healthy subjects (6 men, 11 women, age 60 ± 11 years, LVEF 64 ± 9%). BRS was assessed using a phenylephrine test. Relative transcript levels of α7nAChRs in PBMCs were analyzed using a real-time PCR. Patients with HF, as compared to healthy subjects, demonstrated much higher expression of α7nAChR mRNA in PBMCs (4.4 ± 2.2 vs. 1.4 ± 2.2 AU; P < 0.01) without a difference in BRS (P > 0.2). In a combined sampling including subjects with and without HF, BRS negatively correlated with the content of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) (r = –0.43, P < 0.05). In such sampling, α7nAChR expression in PBMCs also negatively correlated with LVEF (r = –0.39, P < 0.05) and was positively associated with plasma NT-proBNP (r = 0.38, P < 0.01), but without associations with other clinical and laboratory measures. Expression of α7nAChRs in PMBCs is inversely correlated with BRS (r = –0.50, P < 0.01). Thus, autonomic imbalance confirmed by physiological tests is accompanied by increased expression of α7 nicotinic receptors on circulating immune cells.



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Molecular Docking of Phenylethylamine and CGP54626 to an Extracellular Domain of the GABA B -Receptor

Molecular docking of the extracellular domain of the GABAB1a subunit (whose spatial structure was identified by molecular simulation of a full-size GABAB receptor) with the GABA antagonists phenylethylamine and CGP54626 was examined. The spatial structure of the molecules of the above antagonists was obtained using the PubChem database of chemical compounds and mixtures. Detection and analysis of the interaction sites of phenylethylamine with the extracellular domain of subunit GABAB1а of the GABAB receptor was performed using the SwissDock web-service. Docking results were estimated using the FullFitness parameter and free energy analysis of binding of the antagonists to the receptor. The results of molecular docking of phenylethylamine and CGP54626 to the extracellular domain of subunit GABAB1a of the GABAB receptor, as well as a comparative analysis of these data with the results of molecular docking of baclofen to the mentioned receptor, have demonstrated that all binding sites for both antagonists and agonist, located either under or in the "claws" of the subunit molecule, are completely or partially structured by specific groups of amino acid residues. The sites differ from each other in their molecular volumes and density of filling with the above residues. According to the mentioned estimated parameters, the binding sites for baclofen, phenylethylamine, and CGP54626 located in the claws have higher motility and binding energy than similar sites positioned under the claws. In the latter case, the respective sites have higher "rigidity" and lower motility. It has been revealed that the main principle of forming the binding sites for antagonists is the formation of the main matrix elements of baclofen-binding sites located under the claws or in the latter, respectively, with subsequent creation of new groups of amino acids and/or supplying the existing ones with additional amino acid residues. As for antagonist/agonist binding sites, this process is likely to occur via the hydrogen bonds with the constituents of the former, namely amino acid residues threonine and serine, which are the most reaction-capable ones due to their hydroxylic groups. It has been assumed that one of the possible mechanisms of conformation-dependent impact of baclofen-, phenylethylamine-, and CGP54626-binding sites under the claws on the formation of sites to these compounds in the claws is based on the fact that agonist/antagonist-activated transfers of "rigidly"-packed sites, located under the claws and causing conformational transformations of polypeptide chains, are realized, in general, for greater distances. Stabilization of interaction between such sites is likely to occur via the formation of bonds between cations (positively charged radicals of polar charged amino acids in the sites under the claws) and π-electrons of aromatic rings of nonpolar and polar uncharged amino acids in the sites located in the claws.



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Ethical Responsibilities of the Authors



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The electrodiagnosis of Guillain-Barré syndrome subtypes: where do we stand?

In 2012 we reviewed the criteria employed for the electrodiagnosis of Guillain-Barré syndrome (GBS) cautioning about their inadequacy and advocating the development of more reliable criteria sets (Uncini and Kuwabara, 2012). This was timely because since the 1990s the electrodiagnosis of GBS have become more complicated because besides acute inflammatory demyelinating polyradiculoneuropathy (AIDP), two primary axonal subtypes: acute motor axonal neuropathy (AMAN) and acute motor and sensory axonal neuropathy (AMSAN), associated with antecedent Campylobacter jejuni infection and autoantibodies against gangliosides were recognized.

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Your guide to improving your EMS agency's safety culture (eBook)

Learn about the biggest drivers of transforming a fear-based culture into a Just Culture

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Simultaneous monitoring of Ca2+ responses and salivary secretion in live animals reveals a threshold intracellular Ca2+ concentration for salivation

Experimental Physiology, Volume 0, Issue ja, -Not available-.


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Passive heat therapy for cerebral protection: new ideas of age‐old concepts

The Journal of Physiology, Volume 0, Issue ja, -Not available-.


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