Repolarization Process Research Articles

Remote Monitoring of Cardiovascular Risks of Medical Rehabilitation of Ischemic Stroke Patients Using Information and Telecommunication Systems

Due to the high incidence of cerebral stroke, the relevance of the problem of medical rehabilitation for this category of patients is beyond doubt. The increase in disability rates due to movement disorders among stroke survivors (3.2 per 100,000 population) necessitates the introduction of innovative rehabilitation technologies. Patients with cerebral stroke have a high risk of cardiocerebral complications, which should not limit the possibilities of medical rehabilitation. Therefore, the control of possible MR-risks is an important organizational aspect and can be implemented through the introduction of information and communication (ICT) and telemedicine technologies. Conducting dynamic telemetric ECG monitoring during of medical rehabilitation allows to prevent the development of possible cardiovascular risks and personalize the medical rehabilitation program. Aim. To study the effectiveness of remote tele-ECG monitoring based on information and communication technologies for assessing the cardiovascular risks of medical rehabilitation in patients with ischemic stroke. Material and methods. The study included 83 patients with ischemic stroke, mean age 55 [51; 57]), women – 44.6%, men – 55.4%; 42 patients in the early and 41 patients in the late recovery periods of ischemic stroke. All patients underwent a complex of multimodal rehabilitation techniques to restore hand dysfunction and statolocomotor disorders, carried out sequentially during one visit. For the purpose of dynamic control of probable cardiovascular risks, objectification of the state of the cardiovascular system, correction of the intensity and duration of rehabilitation loads, a portable information and communication technologies-based telecardiac complex was used for ECG registration. The ECG parameters were assessed in real time, as well as the stored data on the CardioOblako service. Results and discussion. The spectrum of ECG changes in patients in the early and late recovery periods of ischemic stroke was revealed. The dependence of ECG indexes and their dynamics on the duration of ischemic stroke and its subtype was determined. Asymptomatic changes in the form of heart rhythm disorders (14,4% – supraventricular rhythm disorders, 9,6% – ventricular extrasystoles of the 1st class), as well as repolarization processes (9,6% of cases) were registered during the course of rehabilitation measures. When discussing the results obtained, the probable neurogenic character of cardiac rhythm and conduction disturbances as a consequence of central neurogenic cardiovascular regulation, which is stabilized by central nervous system neuroplasticity over time, is emphasized. At the same time, the literature indicates that these processes can be regulated by therapeutic and rehabilitative measures. In our study, correction of the intensity and duration of rehabilitation loads normalized the changes of ECG indices registered in the process of medical rehabilitation. Conclusion. We determined the need for a comprehensive cardiovascular risk assessment program for patients with IS with the participation of a therapist/cardiologist using dynamic telemetric ECG monitoring during of medical rehabilitation for the timely detection and prevention of cardiovascular complications of medical rehabilitation, personalization of the medical rehabilitation program.

Repolarization processes in lead-free KNN ceramics

In this work, we studied the nature of repolarization processes in KNN-0.05Ta ceramics in the temperature range of structural phase transition. We have found the anomalous behavior of reverse dependences ε'(Ε =), while measuring the response in weak ac-fields in the sample exposed to the constant bias field. Behavior of ε'(Ε =) was compared with the polarization loops measured in sinusoidal fields of various amplitudes.

A complementary resistive switching neuron

The complementary resistive switching (CRS) memristor has originally been proposed for use as the storage element or artificial synapse in large-scale crossbar array with the capability of solving the sneak path problem, but its usage has mainly been hampered by the inherent destructiveness of the read operation (switching ‘1’ state to ‘ON’ or ‘0’ state). Taking a different perspective on this ‘undesired’ property, we here report on the inherent behavioral similarity between the CRS memristor and a leaky integrate-and-fire (LIF) neuron which is another basic neural computing element, in addition to synapse. In particular, the mechanism behind the undesired read destructiveness for storage element and artificial synapse can be exploited to naturally realize the LIF and the ensuing spontaneous repolarization processes, followed by a refractory period. By means of this biological similarity, we demonstrate a Pt/Ta2O5−x /TaO y /Ta CRS memristor that can exhibit these neuronal behaviors and perform various fundamental neuronal operations, including additive/subtractive operations and coincidence detection. These results suggest that the CRS neuron, with its bio-interpretability, is a useful addition to the family of memristive neurons.

Effect of Hypothermia on Myocardial Depolarization and Repolarization in Neonates with Hypoxic-Ischemic Encephalopathy Due to Asphyxia.

Therapeutic hypothermia (TH) is effective for neonatal hypoxic-ischemic encephalopathy (HIE). The combination of abnormal myocardial repolarization and fatal arrhythmia in patients with accidental hypothermia has prompted clinical validation of the proarrhythmic potential of TH. However, to our knowledge, there have been few clinical studies on myocardial depolarization and repolarization abnormalities caused by TH in neonates. Therefore, we investigated the effects of TH on neonatal myocardial depolarization and repolarization by capturing the waveform changes in electrocardiograms (ECGs) associated with body temperature (BT) before and after TH. We included three neonates with HIE diagnosed at birth who were treated with TH in our hospital. The heart rate, RR interval, P wave duration, PR interval, QRS duration, QT interval, corrected QT (QTc) interval by Fridericia's formula, J point-T end (JT) interval, corrected JT (JTc) interval by Fridericia's formula, T peak-T end (Tpe) interval, Tpe/QT, and QRS/QTc were calculated retrospectively using an ECG. The correlations of ECG parameters recorded concurrently with 33 samples in which BT measurements were confirmed were performed. BT and heart rate were positively correlated (R: 0.589, p = 0.0003). BT was negatively correlated with Tpe/QT (R: - 0.470, p = 0.0058), the QTc interval (R: - 0.680, p < 0.0001), and the corrected JT interval (R: - 0.697, p < 0.0001). TH does not affect atrial or ventricular depolarization but prolongs the ventricular repolarization process in a temperature-dependent manner.

Downregulation of hERG channel expression by tyrosine kinase inhibitors nilotinib and vandetanib predominantly contributes to arrhythmogenesis

Cardiotoxicity by tyrosine kinase inhibitors remains an important concern. Nilotinib and vandetanib clinically carry high proarrhythmic risk and the exact mechanism underlying arrhythmogenesis is not fully understood. In this study, we investigated the effects of nilotinib and vandetanib on the abundance of human ether-á-go-go-related gene (hERG) K+ channel and assessed the potential role of acute hERG blockage versus chronic effects in arrhythmogenesis. We found that both nilotinib and vandetanib prolonged the field potential duration reflecting the repolarisation process and induced cellrythmias of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in a time-and concentration-dependent manner after, after chronic exposure. Patch-clamp recordings revealed significant reductions of hERG current densities by nilotinib or vandetanib after chronic incubation with hERG-HEK293 cells in addition to the acute inhibition. Western blot analysis showed that nilotinib and vandetanib decreased mature hERG protein (155-kDa) expression, in a greater extent than that of the immature form (135-kDa). A serum and glucocorticoid kinase 1 (SGK1) activator, C4-ceramide, prevented the nilotinib-and vandetanib-induced hERG protein downregulation and thus the incidence of cellrrhythmias. Taken together, our data demonstrated that the downregulation of hERG channel abundance on the cellular membrane predominantly contributed to the proarrhythmic effect of nilotinib and vandetanib.

Differentiated search for disease in a patient with hyperthyroisis with a prevailing syndrome of cardiovascular disorders. Clinical case

Background. Elderly patients in the presence of iodine deficiency most often develop functional autonomy of the thyroid gland, accompanied by dysfunction— hyperthyroidism. Due to an excess of thyroid hormones, thyrotoxic cardiomyopathy is formed, in which in most cases there is a syndrome of heart rhythm disturbances— atrial fibrillation. The aim of the study: to find out the algorithm for the differential search for a disease in the presence of hyperthyroidism with severe cardiovascular disorders using the example of a specific elderly patient from real clinical practice. Clinical case. A 61-year-old patient was hospitalized in the intensive care unit for arrhythmogenic shock against the background of an attack of atrial fibrillation. The absence of myocardial infarction, pulmonary embolism, acute adrenal insufficiency was stated. The examination revealed a significant decrease in the level of TSH along with an increase in the levels of thyroid hormones without the phenomena of autoaggression, hyperglycemia, hypocholesterolemia, a tendency to hypoproteinemia, leukopenia. An increase in the thyroid gland, heterogeneity of the structure with hypovascularization, the presence of small multiple nodular formations that require clarification were determined. The patient has atrial fibrillation with variability in blood pressure, impaired repolarization processes, hyperkinetic type of hemodynamics, reflecting cardiomyopathy. In this case, there are all prerequisites for the development of functional autonomy of the thyroid gland: age, endemic region, absence of autoimmune changes, dermopathy, ophthalmopathy. Attention is drawn to the severity of manifestations of thyrotoxic heart with dyshormonal and catabolic syndromes, superimposed on comorbid coronary heart disease, hypertension. Conclusions. Hyperthyroidism in the elderly is manifested primarily by cardiovascular disorders, most often with the presence of an arrhythmia syndrome in the form of atrial fibrillation, which can provoke arrhythmogenic shock. Functional autonomy of the thyroid gland with the formation of thyrotoxic cardiomyopathy has specific clinical course, especially in comorbid conditions, which significantly impairs the quality of life.

Attraction vs. Alignment as Drivers of Collective Motion

Moving animal groups exhibit a range of fascinating behaviors. The standard explanation for how these groups form and function is that the individual animals interact via attraction, repulsion, and alignment, where alignment is proposed to drive the collective motion. However, it has been shown both experimentally and theoretically that alignment interactions are not required to induce group level alignment. In particular, via the use of self-propelled particle models it has been established that several other mechanisms induce group level alignment (aka polarization) in combination with attraction alone. However, no systematic comparison of these mechanisms among themselves, or with explicit alignment, has been presented and it remains unclear how, or even if, they can be distinguished at the collective level. Here, we introduce two previously unreported mechanisms, burst-and-glide and burst-and-stop, and show via simulation that they also induce polarization in combination with attraction alone. Then, we compare the polarization inducing characteristics of six mechanisms; asymmetric interactions, asynchrony, anticipation, burst-and-glide, burst-and stop, and explicit alignment. We show that the mechanisms induce polarization in different parts of the attraction parameter space, that the route to polarization from uniformly random initial conditions, as well as repolarization following strong perturbations, is markedly different among the mechanisms. In particular, we find that alignment based and non-alignment based mechanisms can be distinguished via their polarization and repolarization processes. These findings further challenge the current alignment based theory of collective motion and may contribute to a more versatile theory of collective motion across scales.

Комплексний підхід до терапії інфаркту міокарда, поєднаного з неалкогольною жировою хворобою печінки

Актуальність. У комплексному лікуванні інфаркту міокарда (ІМ), поєднаного з неалкогольною жировою хворобою печінки (НЖХП), актуальним є застосування лікарських засобів із протективними властивостями. Мета дослідження — вивчити ефективність Тіотриазоліну та препарату знежирених збагачених соєвих фосфоліпідів у комплексному лікуванні хворих у гострому періоді ІМ, поєднаного зі стеатозом печінки або неалкогольним стеатогепатитом. Матеріали і методи. Обстежено 47 хворих із гострим ІМ із зубцем Q, поєднаним із НЖХП. Дослідження електричної активності серця проводилося на вдосконаленому поліграфі з реєстрацією електро- та векторкардіограми до і після тритижневої терапії базисними препаратами 16 хворих (13 чоловіків і 3 жінок, середній вік — 60,50 ± 3,74 року), із доданням Тіотриазоліну — 16 хворих (8 чоловіків і 8 жінок, середній вік — 62,94 ± 2,71 року), Тіотриазоліном та препаратом знежирених збагачених соєвих фосфоліпідів у комбінації з базисною терапією — 15 хворих (10 чоловіків і 5 жінок) віком від 36 до 75 років (середній вік — 60,00 ± 3,36 року). Результати. Під час лікування базисними препаратами спостерігалося подальше зменшення електрорушійної сили серця з уповільненням проведення імпульсу та порушенням процесів пізньої реполяризації в міокарді шлуночків і передсердь за зменшення зони пошкодження в лівому шлуночку й перевантаження передсердь. Одночасне застосування Тіотриазоліну та базисних препаратів спричинило мінімальні позитивні зрушення в електрорушійній силі серця. Крім того, відзначалося збільшення зони ішемії за рахунок зменшення зони пошкодження міокарда, більш виражена нормалізація порожнини лівого передсердя та реєструвалася стабілізація процесів реполяризації в передсердях. Застосування лікувального комплексу, до складу якого входили базисні препарати, Тіотриазолін і препарат знежирених збагачених соєвих фосфоліпідів, сприяло знач­ному збільшенню біопотенціалів міокарда шлуночків за локального поліпшення швидкісних показників і більш вираженому відновленню кардіоміоцитів на периферії зони пошкодження. Результати впливу комбінації застосованих препаратів на показники передсердного компонента електричної активності серця вказують на значне опосередковане гемодинамічне розвантаження передсердь, спочатку поліпшене скорочувальною здатністю лівого шлуночка з подальшою нормалізацією процесів реполяризації в міокарді передсердь. Висновки. Одночасне використання Тіотриазоліну та препарату знежирених збагачених соєвих фосфоліпідів у хворих на НЖХБ в гострому періоді ІМ із зубцем Q потенціює позитивні властивості обох лікарських засобів. У зв’язку з цим можна рекомендувати призначення вищевказаних препаратів для комплексного лікування даної категорії пацієнтів.

Seasonal changes of electrophysiological heterogeneities in the rainbow trout ventricular myocardium.

IntroductionThermal adaptation in fish is accompanied by morphological and electrophysiological changes in the myocardium. Little is known regarding seasonal changes of spatiotemporal organization of ventricular excitation and repolarization processes. We aimed to evaluate transmural and apicobasal heterogeneity of depolarization and repolarization characteristics in the rainbow trout in-situ ventricular myocardium in summer and winter conditions.MethodsThe experiments were done in summer-acclimatized (SA, 18°C, n = 8) and winter-acclimatized (WA, 3°C, n = 8) rainbow trout (Oncorhynchus mykiss). 24 unipolar electrograms were recorded with 3 plunge needle electrodes (eight lead terminals each) impaled into the ventricular wall. Activation time (AT), end of repolarization time (RT), and activation-repolarization interval (ARI, a surrogate for action potential duration) were determined as dV/dt min during QRS-complex, dV/dt max during T-wave, and RT-AT difference, respectively.ResultsThe SA fish demonstrated relatively flat apicobasal and transmural AT and ARI profiles. In the WA animals, ATs and ARIs were longer as compared to SA animals (p≤0.001), ARIs were shorter in the compact layer than in the spongy layer (p≤0.050), and within the compact layer, the apical region had shorter ATs and longer ARIs as compared to the basal region (p≤0.050). In multiple linear regression analysis, ARI duration was associated with RR-interval and AT in SA and WA animals. The WA animals additionally demonstrated an independent association of ARIs with spatial localization across the ventricle.ConclusionCold conditions led to the spatial redistribution of repolarization durations in the rainbow trout ventricle and the formation of repolarization gradients typically observed in mammalian myocardium.

Directional reorientation of migrating neutrophils is limited by suppression of receptor input signaling at the cell rear through myosin II activity

To migrate efficiently to target locations, cells must integrate receptor inputs while maintaining polarity: a distinct front that leads and a rear that follows. Here we investigate what is necessary to overwrite pre-existing front-rear polarity in neutrophil-like HL60 cells migrating inside straight microfluidic channels. Using subcellular optogenetic receptor activation, we show that receptor inputs can reorient weakly polarized cells, but the rear of strongly polarized cells is refractory to new inputs. Transient stimulation reveals a multi-step repolarization process, confirming that cell rear sensitivity to receptor input is the primary determinant of large-scale directional reversal. We demonstrate that the RhoA/ROCK/myosin II pathway limits the ability of receptor inputs to signal to Cdc42 and reorient migrating neutrophils. We discover that by tuning the phosphorylation of myosin regulatory light chain we can modulate the activity and localization of myosin II and thus the amenability of the cell rear to ‘listen’ to receptor inputs and respond to directional reprogramming.

TSSF-hERG: A machine-learning-based hERG potassium channel-specific scoring function for chemical cardiotoxicity prediction

The human ether-à-go-go-related gene (hERG) encodes the Kv11.1 voltage-gated potassium ion (K+) channel that conducts the rapidly activating delayed rectifier current (IKr) in cardiomyocytes to regulate the repolarization process. Some drugs, as blockers of hERG potassium channels, cannot be marketed due to prolonged QT intervals, as well known as cardiotoxicity. Predetermining the binding affinity values between drugs and hERG through in silico methods can greatly reduce the time and cost required for experimental verification. In this study, we collected 9,215 compounds with AutoDock Vina’s docking structures as training set, and collected compounds from four references as test sets. A series of models for predicting the binding affinities of hERG blockers were built based on five machine learning algorithms and combinations of interaction features and ligand features. The model built by support vector regression (SVR) using the combination of all features achieved the best performance on both tenfold cross-validation and external verification, which was selected and named as TSSF-hERG (target-specific scoring function for hERG). TSSF-hERG is more accurate than the classic scoring function of AutoDock Vina and the machine-learning-based generic scoring function RF-Score, with a Pearson’s correlation coefficient (Rp) of 0.765, a Spearman’s rank correlation coefficient (Rs) of 0.757, a root-mean-square error (RMSE) of 0.585 in a tenfold cross-validation study. All results demonstrated that TSSF-hERG would be useful for improving the power of binding affinity prediction between hERG and compounds, which can be further used for prediction or virtual screening of the hERG-related cardiotoxicity of drug candidates.

High frame rate speckle tracking echocardiography to assess diastolic function

Abstract Background Left ventricular (LV) strain rate (SR) during isovolumic relaxation (SRIVR) and early diastolic filling (SRe) has previously been shown to correlate with the invasive gold standard for LV diastolic function (i.e. the time constant of LV pressure decay tau). However, the translation of these biomarkers to the clinic has been hampered by technical limitations. Indeed, conventional speckle tracking (STE) is limited by its temporal resolution, whereas tissue Doppler imaging (TDI) is angle-dependent, labor-intensive and thus rarely used clinically nowadays. Purpose The aim of this study was to show that these limitations could be overcome by using a recently proposed STE algorithm operating on high frame rate (HFR) imaging data. Methods 37 subjects (age: 64±12, 81% male) were included in the study; 16 had cardiac amyloidosis, 12 were undergoing clinically indicated left and/or right heart cardiac catheterization and 9 were healthy volunteers. Since the sequence of left ventricular activation and thus the repolarization process (i.e. relaxation) starts at mid septum, we measured SRIVR and SRe in the mid septal segment in an apical 4 chamber view using a commercially available clinical system with: (1) TDI (frame rate (FR) ∼142 Hz); (2) STE (FR ∼65 Hz). Moreover, subjects were scanned with HD-PULSE, an experimental high frame ultrasound scanner (FR ∼915 Hz) and then a manually placed contour was tracked during the cardiac cycle by a custom-made 2D HFR STE algorithm, to compute and extract SRIVR and SRe from the mid septum. Since TDI is considered the reference method to assess SR, conventional as well as HFR STE values were correlated against the TDI SR values. Results In 3 subjects, SRIVR could not be reliably assessed with the clinical STE approach, which we attributed to the relatively low temporal resolution of the images; all other measurements could be made in all subjects. For both biomarkers, HFR STE values correlated better with the TDI reference measurements than the clinical STE estimates (Fig.1). The latter estimates showed a systematic underestimation (bias −0.19 1/s (p&amp;lt;0.01) and −0.46 1/s (p&amp;lt;0.01) for SRIVR and SRe respectively) while no significant bias was observed for the HFR STE values. Similarly, the limits of agreement of the HFR STE values were narrower (−0.45 to +0.54 1/s and −0.94 to +0.86 1/s) than those of the clinical STE measurements (−0.85 to +0.48 1/s and −1.32 to +0.41 1/s). Conclusions These results show that HFR STE offers a reliable way to assess novel biomarkers of diastolic function in a user-friendly manner and can therefore facilitate their incorporation to the clinical practice. Funding Acknowledgement Type of funding sources: None.

Specific features of electrocardiograms in infants with intrauterine growth restriction and developmental delays

Aim. Assessment of electrocardiographic indicators in infants born on time with delayed intrauterine growth and mild development.&#x0D; Materials and methods. Under the supervision of 164 infants. From mothers with an aggravated somatic and obstetric-gynecological history, 139 children were born: 71 (gr. 1) with delayed intrauterine growth and development of mild severity, 68 (gr. 2) without delayed intrauterine growth and development. The control group (gr. 3) consisted of 25 practically healthy children born to practically healthy mothers. All children were born full-time. They were examined in dynamics at the age of 1 (n=154), 3 (n=142), 6 (n=133), 12 (n=130) months. A comprehensive analysis of the data of history, physical examination, electrocardiography was carried out. There was no medical intervention. The duration of the study is 3 years. Heart rate, incidence of early ventricular repolarization syndrome and nonspecific disorders of the repolarization process were evaluated; in the II standard retraction, morphology, amplitude in millimeters and width in seconds of the tooth P; duration in seconds of PQ interval (PR), QRS complex and QT interval; morphology, amplitude in millimeters of tooth T. Non-parametric methods of statistical analysis were used.&#x0D; Results. The median amplitude of the tooth P on day 23 in children of subgr. 1b, compared with children of gr. 3, is 0.2 mm less; 1 month in children of gp. 1 (1b), compared with children of gp. 3, less by 0.1 mm; at 3 months in children of subgp. 1a, compared with children of subgp. 1b, less by 0.35 mm, in children of subgp. 1b, compared with children of gp. 3, more by 0.2 mm; at 6 months in children of gp. 1 (1a and 1b), compared with children of gr. 3, more by 0.2 mm; at 12 months in children of subgp. 1a, compared with children of subgp. 1b, less by 0.2 mm, in children of subgp. 1b, compared with children of gr. 2, more by 0.2 mm, in children of gp. 1 (1a), compared with children of gr. 3, less by 0.2 (0.5) mm, and, compared with children of gr. 3, less by 0.2 mm. From 3 to 6 months increased in children of subgp. 1a by 0.35 mm. In children of gp. 1st (1a), a slowdown from 23 days to 1 month of intradermal conduction by 0.01 s, from 1 to 3 months of intraventricular conduction by 0.01 s, from 3 to 6 months of intradermal conduction by 0.01 s. Electrical systole in children of gr. 1 slowed from 1 to 3 and from 3 to 6 months by 0.01 s; in children of subgp. 1a from 1 to 3 months increased by 0.01 s, from 3 to 6 months decreased by 0.01 s, from 6 to 12 months increased by 0.01 s. Median tooth amplitude T on 23 days, 1 month in children of gp. 1 (1a and 1b), compared to children of gr. 3, more by 0.4 mm and 0.3 mm, respectively; at 3 months in children of subgp. 1a, compared with children of subgp. 1b, less by 0.35 mm, and, compared with children of gr. 2, less by 0.2 mm, in children of subgp. 1b, compared with children of gr. 2 more by 0.15 mm, in children of gp. 1 (1b), compared with children of gr. 3, more by 0.3 (0.45) mm; at 12 months in children of subgp. 1b, compared with children of gr. 2, more by 0.4 mm, in children of gp. 1 (1a), compared with children of gp. 3, less by 0.3 mm. From 23 days to 1 month in children of gp. 1 (1a) increased by 0.8 mm.&#x0D; Conclusion. Certain peculiarities of electrocardiogram in dynamics of growth and development of the organism of infants born on time with delay of intrauterine growth and development of mild severity related to volume overload of atrium, enlargement of interventricular septum, hypoxia, sympathetic activity, requiring corrective events are revealed.

Structural-electrical remodeling of myocardium in neurological deficits in patients with ischemic stroke: is there a connection?

Abstract Funding Acknowledgements Type of funding sources: None. Theoretical and clinical questions of the correlation between structural-electrical remodeling of the heart and the severity of neurological deficits at stroke have not been developed or remain controversial so far. Available data in the literature suggests the key role of structural myocardial disorders mainly in hemorrhagic stroke, and cardiocerebral syndrome is considered only from the standpoint of cardioembolic stroke. The aim of the study. To study the peculiarities of structural-electrical remodeling of myocardium with severity of neurological deficit in patients with ischemic stroke. Materials and methods. 111 patients with ischemic stroke in the left hemisphere and 75 patients in the right brain hemisphere were examined. The average age was 56.7 ± 5.58 years. All subjects underwent an ultrasound examination of the heart using the ALOKA SSD 5000 apparatus (Japan) and the QT dispersion using the Polyspectro-8EX apparatus (Russia). Duration of QT dispersion interval more than 50 ms was considered pathological. Research results. Structural remodeling of the heart in patients with ischemic stroke was manifested by the prevalence of high values of the finite-systolic volume of the left ventricle in comparison with patients without stroke (45.8 ± 21.0 vs. 37.7 ± 16.9 ml; p &amp;lt; 0.05), and the finite-diastolic volume of the left ventricle (114.3 ± 38.5 vs. 100.9 ± 35.3 ml; p &amp;lt; 0.05), mainly in the right hemispheric localization of the stroke. Hypertrophy of the ventricular septum (11.3 ± 2.1 and 11.1 ± 2.2) and the posterior wall of the left ventricle (10.4 ± 1.8 and 10.3 ± 2.1 mm) was observed irrespective of the localization of the stroke, which was higher in comparison with patients without stroke (9.4 ± 1.5 mm). Violations of repolarization processes and their severity were characterized by higher values of duration of the corrected QT interval in patients with structural changes of myocardium in comparison with the patients without structural remodeling (0,46 ± 0,03 and 0,44 ± 0,02 sec; p = 0,025). The conjugation of the severity of the neurological deficit (7 and more points on the NIHSS scale) was associated with the terminal-systolic size of the LV (p = 0.025) and myocardial hypertrophy (11.3 ± 1.86 vs. 10.96 ± 1.8 mm; p = 0.04) in comparison with patients with a neurological deficit of less than 7 points (31.7 ± 3.6 vs. 30.68 ± 3.86 mm; p &amp;lt; 0.025). The severity of the neurological deficit according to the Goldstein criteria correlated with higher values of the corrected (56.0 ± 23.93 vs. 41.6 ± 23.3 ms.; p = 0.043) and normalized QT (17.5 ± 6.533 vs. 12.8 ± 6.7 ms.; p = 0.019) values in comparison with the lower neurological deficit. A similar relationship was revealed by the Brott criteria. Conclusions. Thus, the direct connection between structural-electrical remodeling of the heart and neurological deficit revealed in the course of the study reflects the cardiocerebral relationships in ischemic stroke.

Sparse Representation for Cardiac Electrical Activity Imaging in Magnetocardiography

Signal sparsity has been widely discussed in communication system, cloud computing, multimedia processing and computational biology. Reconstructing the sparsely distributed current sources of the heart by means of non-invasive magnetocardiography (MCG) measurement and various optimization methods provides a new way to solve the inverse problem of the cardiac magnetic field. The problem of sparse source location of MCG is in the time series of MCG measurement caused by active sparse current source, can the spatiotemporal source be reconstructed accurately and effectively? For the above problem, the scientific contributions of the paper include: (1) A modified focal underdetermined system solver algorithm is proposed for a sparse solution, by combing with dynamic regularization factor and smoothed sparse constraint; (2) Lead field matrix is reduced by prior information of cardiac magnetic field map to reduce under-determination; (3) Spatiotemporal sources are reconstructed for non-invasive cardiac electrical activity imaging. The results of real MCG data demonstrate the effectiveness of this method for cardiac electrical activity imaging. The temporal and spatial changes of the current sources are similar to the depolarization and repolarization process of the ventricle.

Silent myocardial ischemia in patients with type 2 diabetes mellitus: a clinical case

Background. Type 2 diabetes mellitus (DM) is an important medical, social, and economic problem due to the high prevalence of the disease, which often leads to disability and significantly increases mortality in elderly people. One of the causes of coronary heart disease (CHD) in patients with type 2 DM is autonomic cardiovascular neuropathy, which is characterized by damage to the autonomic nervous system and manifests itself in a varying clinical picture, including silent myocardial ischemia (SMI). The prevalence of SMI among patients with type 2 DM is much higher than in people without it. The purpose was to study the clinical case of a patient with type 2 DM and CHD, raise awareness of the prevalence and influence of type 2 DM on CHD progression by focusing on diagnostic research and treatment strategies. Materials and methods. The clinical case of the detected silent ischemia in a patient with type 2 DM was analyzed. The complaints were as following: high blood pressure, moderate shortness of breath during walking, pain, and numbness of the lower extremities. Anamnesis: type 2 DM over 20 years; endovascular stenting of the right common iliac artery due to obliterating atherosclerosis of the arteries of the lower extremities; hypertension over 10 years; obesity. Based on this data, CHD was suspected. Results. The Holter monitoring revealed rare episodes of reversible ischemic repolarization. ECG demonstrated the deviation of the electrical axis to the left, hypertrophy of the left ventricular myocardium, diffuse violation of repolarization processes. Ultrasound of the heart found aortic atherosclerosis, left ventricular myocardial hypertrophy, a moderate decrease in myocardial contractility. Ultrasound of vessels of the lower extremities showed the signs of obliterating atherosclerosis with decompensation of peripheral blood flow. Coronary angiography demonstrated left coronary artery with critical subocclusions (90 %), right coronary artery with chronic occlusion in the middle segment (100 %). There was established the diagnosis: coronary heart disease (silent ischemia); diffuse stenotic atherosclerosis of the coronary artery (coronary angiography May 2019); arterial hypertension II stage, degree 2; HF II stage; II NYHA; type 2 diabetes mellitus, insulin-dependent, decompensated; obesity I stage; obliterating atherosclerosis of the arteries of the lower extremities (condition after endovascular stenting of the right common iliac artery on January 2018); chronic pancreatitis in remission, peptic ulcer of the duodenum (operated in 1981); chronic cholecystitis in remission. The treatment was prescribed: insulin therapy, nebivolol, eplerenone, candesartan, clopidogrel, rosuvastatin. Coronary artery bypass grafting is recommended. Conclusions. Thereby, timely diagnosis and adequate treatment can avoid complications of type 2 DM and improve quality and lifetime. With type 2 DM, CHD is often masked and remains undiagnosed, leading to complications and death, therefore more attention to such patients is needed.

The study of the temporal evolution of the electric energy dependence on polarization in Rb2ZnCl4 crystal in ferroelectric phase near the Curie point

The process of Rb2ZnCl4 crystal repolarization under the harmonic electric field influence in the ferroelectric phase near the Curie temperature was studied by the harmonic analysis method. The study of current density harmonics arising in the sample under the harmonic field influence allowed plotting the electric energy density Wc dependence on the polarization Pc measured in the dynamics. The Wc (Pc ) time evolution was obtained after shifting of the domain structure from the equilibrium position by an alternating electric field. It was found that during relaxation the shape of Wc (Pc ) changed significantly.

Role of RhoGAP Rgd1 in Pkc1 signaling-related actin repolarization under heat shock stress in Saccharomyces cerevisiae

BackgroundA serine/threonine kinase Pkc1 is the sole protein kinase C in the budding yeast Saccharomyces cerevisiae, and plays an important role in the regulation of polarized growth and stress responses such as those due to heat shock. Exposure of cells to high temperature transiently arrests polarized growth and leads to depolarization of the actin cytoskeleton, followed by actin repolarization during adaptation to heat shock stress. Actin repolarization is ensured by the activation of Pkc1 signaling; however, the molecular mechanisms underlying this phenomenon remain poorly understood. MethodsUsing an overexpression construct of a constitutively active mutant of Pkc1 (Pkc1R398P), we explored the Pkc1 target molecules involved in actin repolarization. ResultsPKC1R398P overexpression as well as heat shock stress increased the phosphorylation levels of Rho GTPase-activating protein (RhoGAP) Rgd1. Rgd1 was found to contribute to Pkc1-signaling-related actin repolarization during adaptation to heat shock stress in a GAP activity-independent manner, with Ser148 in Rgd1 playing a crucial role. Furthermore, Rgd1 was involved in the maintenance of phosphorylation status of the mitogen-activated protein (MAP) kinase Mpk1, a downstream effector of Pkc1, under heat shock stress. ConclusionsRgd1 is a target of Pkc1 signaling under conditions of heat shock stress, and required for the normal process of actin repolarization during adaptation to heat shock stress. General significanceOur results provide insights into the molecular mechanism underlying Pkc1-mediated modulation of actin repolarization under heat shock stress.

Design of Rate-Compatible Polar Codes Based on Non-Uniform Channel Polarization

In this article we propose a technique for polar codes (PC) construction for any code length. By default, PC construction is limited to code length proportional to the power of two. To construction the code length arbitrary, puncturing, shortening and extension techniques must be applied. However, performance is degraded with the use of these techniques. Other ways to design polar codes with arbitrary code length but which have encoding and decoding with higher complexity such as multi-kernel, concatenated codes and specific constructions for belief propagation (BP) or successive cancellation list (SCL) decoding. The polarization theory is generalized for non-uniform channels (NUC) and with this approach we can construction rate-compatible PC and variable code length. We developed an implementation algorithm based on the of PC construction by Gaussian approximation (NUPGA). In a scenario where the transmission is over an additive white Gaussian noise (AWGN) channel and under successive cancellation (SC) decoding, the PC construction of arbitrary code length can be implemented with NUPGA. With NUPGA we re-polarize the projected synthetic channels by choosing more efficiently the positions of the information bits. In addition, we present a generalization of the Gaussian approximation (GA) for the polarization and re-polarization processes and an extension technique for PC. The PC construction based on NUPGA present better performance than the existing techniques as shown in the simulations of this work.

Розробка математичної моделі перемикання електричної поляризації у сегнетоелектричному конденсаторі

In this paper, a mathematical model of switching the electrical polarization of a ferroelectric capacitor was developed, which adequately reflects the processes of writing and reading in the elements of FRAM-memory and is suitable for developing automated design of ferroelectric storage elements and devices. Physical models of switching electrical polarization in a ferroelectric capacitor are found only in isolated cases of crystallization under certain assumptions about the dimension of domains, the processes of their nucleation, growth and overlap. Therefore, the work carried out the transfer of the known geometric-probabilistic model of melt crystallization to the processes of repolarization of ferroelectrics. For this crystallization model, two variants of its practical implementation have been developed — for χ- and β-processes. Accordingly, in the mathematical model we can distinguish two components, calling them χ- and β-models of switching polarization in a ferroelectric capacitor. The difference between the developed model and others is that in the crystallization model the initial value of polarization is introduced and mixed (temporal and spatial) normalization of the parameters of the ferroelectric material is performed. In particular, the concept of characteristic time is introduced, which is the time of doubling the radius of embryos in fields with intensities much larger than the activation fields; characteristic volume, which for the χ-process is equal to the volume repolarized by germination over the characteristic time, and for the β-process — the initial volume, polarized in the direction of the field before its application and the relative field of activation of germination and growth of domains. Generalized normalized models with mixed rationing proved to be more convenient for setting certain requirements for the parameters of ferroelectric material in order to obtain the specified characteristics of ferroelectric storage elements in terms of speed and intensity of switching currents.