Activation Sequence Research Articles

Tailoring Magnetite-Nanoparticle-Based Nanocarriers for Gene Delivery: Exploiting CRISPRa Potential in Reducing Conditions.

Gene delivery has emerged as a promising alternative to conventional treatment approaches, allowing for the manipulation of gene expression through gene insertion, deletion, or alteration. However, the susceptibility of gene delivery components to degradation and challenges associated with cell penetration necessitate the use of delivery vehicles for effective functional gene delivery. Nanostructured vehicles, such as iron oxide nanoparticles (IONs) including magnetite nanoparticles (MNPs), have demonstrated significant potential for gene delivery applications due to their chemical versatility, biocompatibility, and strong magnetization. In this study, we developed an ION-based delivery vehicle capable of releasing linearized nucleic acids (tDNA) under reducing conditions in various cell cultures. As a proof of concept, we immobilized a CRISPR activation (CRISPRa) sequence to overexpress the pink1 gene on MNPs functionalized with polyethylene glycol (PEG), 3-[(2-aminoethyl)dithio]propionic acid (AEDP), and a translocating protein (OmpA). The nucleic sequence (tDNA) was modified to include a terminal thiol group and was conjugated to AEDP's terminal thiol via a disulfide exchange reaction. Leveraging the natural sensitivity of the disulfide bridge, the cargo was released under reducing conditions. Physicochemical characterizations, including thermogravimetric analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy, confirmed the correct synthesis and functionalization of the MNP-based delivery carriers. The developed nanocarriers exhibited remarkable biocompatibility, as demonstrated by the hemocompatibility, platelet aggregation, and cytocompatibility assays using primary human astrocytes, rodent astrocytes, and human fibroblast cells. Furthermore, the nanocarriers enabled efficient cargo penetration, uptake, and endosomal escape, with minimal nucleofection. A preliminary functionality test using RT-qPCR revealed that the vehicle facilitated the timely release of CRISPRa vectors, resulting in a remarkable 130-fold overexpression of pink1. We demonstrate the potential of the developed ION-based nanocarrier as a versatile and promising gene delivery vehicle with potential applications in gene therapy. The developed nanocarrier is capable of delivering any nucleic sequence (up to 8.2 kb) once it is thiolated using the methodology explained in this study. To our knowledge, this represents the first MNP-based nanocarrier capable of delivering nucleic sequences under specific reducing conditions while preserving functionality.

Regional patterns of activation during induced ventricular fibrillation in Brugada Syndrome

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The activation pattern of induced ventricular fibrillation (VF) in Brugada Syndrome (BS) is not well known. Objectives The aim is to establish a hypothesis about temporal activation in the right ventricle (RV) during induced VF in BS patients. Methods We examined the sequence of electrical activation in RV during induced VF by programmed stimulation (PS) in 8 patients diagnosed with BS. The 12 ECG leads were analyzed and the electrograms (EGMs) were recorded from a quadripolar catheter placed in the RV apex or in the right ventricular outflow tract (RVOT), from which ventricular fibrillation was induced. Results ECG recordings and EGMs of VF were analyzed in 8 patients diagnosed with BS. VF was induced from the RV apex and the RVOT in 6 and 2 patients respectively. From the onset of induced VF to the appearance of sinusoidal waves, three activation areas were observed based on ECG morphology and the activation timing of the right ventricular EGM: apex, moderator band (MB), and RVOT. The first activated area coincided from where VF was induced. The second activated area was the MB in 6 patients. Following RV apex activation, a sinusoidal signal appeared in 2 patients with no activation area being distinguished. Activation was from the MB to RVOT and toward the RV apex in 3 and 2 patients respectively. Conclusion In ventricular fibrillation induced in Brugada Syndrome, the activation pattern is sequential from RVOT to RV apex and vice versa through the moderator band.

Gap junctions desynchronize a neural circuit to stabilize insect flight

Insect asynchronous flight is one of the most prevalent forms of animal locomotion used by more than 600,000 species. Despite profound insights into the motor patterns1, biomechanics2,3 and aerodynamics underlying asynchronous flight4,5, the architecture and function of the central-pattern-generating (CPG) neural network remain unclear. Here, on the basis of an experiment–theory approach including electrophysiology, optophysiology, Drosophila genetics and mathematical modelling, we identify a miniaturized circuit solution with unexpected properties. The CPG network consists of motoneurons interconnected by electrical synapses that, in contrast to doctrine, produce network activity splayed out in time instead of synchronized across neurons. Experimental and mathematical evidence support a generic mechanism for network desynchronization that relies on weak electrical synapses and specific excitability dynamics of the coupled neurons. In small networks, electrical synapses can synchronize or desynchronize network activity, depending on the neuron-intrinsic dynamics and ion channel composition. In the asynchronous flight CPG, this mechanism translates unpatterned premotor input into stereotyped neuronal firing with fixed sequences of cell activation that ensure stable wingbeat power and, as we show, is conserved across multiple species. Our findings prove a wider functional versatility of electrical synapses in the dynamic control of neural circuits and highlight the relevance of detecting electrical synapses in connectomics.

Detection of the most dominant drivers of atrial fibrillation based on repetitive activity in sequential electro-anatomical mapping

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work is part of Personalize AF. This project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860974, This work was also supported by the Swiss National Supercomputing Centre (CSCS), project s1074. Introduction Detecting and targeting the most dominant drivers of atrial fibrillation (AF) might improve the outcome of AF ablation procedures. We hypothesize that dominant drivers entrain their vicinity in a temporally and spatially stable manner resulting in local as well as adjacent repetitive activation patterns. Purpose We present a novel approach to detect the most dominant drivers of AF based on driver repetitiveness and the degree to which they entrain their vicinity. Methods We retrospectively analyzed a dataset of high-density bi-atrial sequential mapping in ablation-naive persistent AF patients (n=13, 30s recording per site). Candidate drivers (focal activity or re-entry) were detected based on local activation time analysis of unipolar electrograms. Focal activity was defined as radial spread of activation, re-entry as a circular activation sequence on at least 4 splines of the mapping catheter that covered >50% of the AF cycle length. As a measure of driver stability, we determined the driver's local repetitiveness (in % of recording). As a measure of driver-associated entrainment, we determined the directionally coherent repetitiveness of adjacent recordings within 30 mm (Figure 1). Following our hypothesis, most dominant drivers can be recognized by their high local and directional coherent adjacent repetitiveness. Results A total of 459 recordings were analyzed (35±5 per patient). We detected 130 focal activities (10±3 per patient) and 42 re-entries (4±2 per patient) in total. The spatial distribution of all drivers is shown in Figure 2 (blue bars). Focal activities were more repetitive than re-entries (Figure 2, median [IQR] 3.2% [1.9%, 5.6%] vs. 1.8% [1.8%, 2.2%], p<0.001 Mann-Whitney U-test). When applying a 90th percentile threshold (8.2%) to both the local and directional coherent adjacent repetitiveness to detect the most dominant drivers, we were able to detect 9 dominant drivers (all focal activities, 7 patients). Most dominant drivers were located in the upper right atrium or left pulmonary vein region (Figure 2). Interestingly, only 9 of the 130 initially detected drivers (7%) showed an activation pattern in line with a repetitive entrainment of their vicinity. Furthermore, in 6 patients (46%), no dominant drivers were detected. This might indicate that not all patients have temporally and spatially stable drivers. Conclusion In this abstract we present a novel methodology to detect the most dominant drivers of AF. Using this method, we found that some (but not all) patients have temporally and spatially stable drivers that are able to entrain their vicinity.

PE-454609-1 MYOCARDIAL WORK IN VENTRICULAR PREEXCITATION

Ventricular preexcitation alters the electromechanical activation sequence and may induce left ventricular (LV) contractile discoordination and pathologic remodelling in selected cases. To evaluate LV myocardial work before and after accessory pathway (AP) ablation in patients with WPW preexcitation and to compare them to normal controls. Mechanical activation mapping and myocardial work calculation was performed in 11 pediatric patients with the WPW syndrome/pattern and left sided or paraseptal APs undergoing catheter ablation (successful in 10/11) and 8 healthy age-matched controls using speckle tracking echocardiography and the GE ECHOPAC version 204.57.0.745 software with the integrated AFI module. An 18-segmental echocardiographic LV model was used. Global LV myocardial work efficiency (GWE) was calculated as the ratio of global constructive work to the sum of global constructive and global wasted work (GWW). The time from delta wave onset to R wave peak in lead V6 (delta to R) was used to quantify the degree of preexcitation. Before ablation GWW was higher (164 vs 102 mmHg%, P=0.015) and GWE lower (median 91 vs 94%, P=0.010) in patients vs controls. After successful ablation GWW decreased from 164 to 93 mmHg% (P=0.006) and GWE increased from 91.1 to 94.0 % (P=0.006). GWE tended to correlate negatively with the delta to R interval (R=0.59, P=0.056). Before ablation, segmental WE increased with distance from ventricular AP insertion from median 69.5 % at AP location to 98.0 % in distant segments (P<0.001). After ablation, WE was equally distributed among LV segments (Figure). Mechanical activation mapping localized APs with a median (IQR) segmental distance of 0 (0-1) segments from the EP mapped location. Ventricular preexcitation induces significant LV myocardial work inefficiency in segments adjacent to AP which correlates with the degree of preexcitation and is normalized after ablation. The amount of wasted work in asymptomatic preexcitation may be considered when assessing the potential for pathologic LV remodelling or discussing the indication for prophylactic ablation. Mechanical activation mapping may be used to localize manifest APs.

PO-03-088 TWO-DIMENSIONAL SPECKLE TRACKING ECHOCARDIOGRAPHY SHOWS THAT LEFT BUNDLE BRANCH PACING MAINTAINS LEFT VENTRICULAR GLOBAL LONGITUDINAL STRAIN AND CONTRACTILITY COMPARED TO RIGHT VENTRICULAR APICAL PACING

Pacemaker-dependent patients with right ventricular (RV) apical pacing are at increased risk for reduced left ventricular function, ventricular dyssynchrony, and the development of pacing-induced heart failure. Physiological pacing of the conduction system through the left bundle branch (LBB) has been shown to have improved synchrony of the ventricles and a more physiological activation sequence. Direct comparison of left ventricular (LV) strain using LBB and RVAP in paired experiments in the same animals or patients has not been published. Evaluate the changes to the left ventricular mechanics (global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and left ventricular ejection fraction (LVEF) through LBB pacing compared to RV pacing using two-dimensional speckle tracking echocardiography. Under anesthesia, six mixed breed hounds had pacing leads from two ICDs (CobaltTM XT DR, Medtronic, Inc) implanted at the RV apex (6947 Sprint Quattro SecureTM, Medtronic, Inc) and the LBB (3830 SelectSecureTM, Medtronic, Inc). Echocardiographic measurements were taken for sinus rhythm, LBB pacing, and RV pacing to evaluate the LV strain, and contractility. Two-dimensional speckle tracking was performed following the pacing procedure to determine GLS, and LVEF from the four-chamber apical views, GCS, and GRS from the short-axis views. In our study, LV GLS was maintained better during LBB pacing when compared to LV GLS during RV pacing. The magnitude of GLS was not significantly different between sinus and LBB pacing, but was significantly lower for RV pacing than both sinus and LBB pacing (Fig. A). GCS only showed a significant difference between sinus and RV pacing (Fig. B), while GRS did not show differences between any of the groups (Fig. C). Results for the LV ejection fraction followed a similar pattern as the GLS. There was not a significant difference in LVEF for sinus and LBB pacing, but LVEF was significantly lower for RV pacing compared to both sinus and LBB pacing (Fig. D). LBB pacing preserves GLS, and the LVEF better than RV apical pacing and is similar to sinus beats. This further supports LBB pacing as a preferred method of pacing for preserving contractility for patients with pacemakers.

Hyposensitizing effect of high altitude and immunogenetic law

The studies were carried out in 24 sexually mature male guinea pigs. They were used as model of immediate-type allergic reaction (active cutaneous anaphylaxis). The animals were divided in 2 groups: control and experimental. The control group was housed in the mountain valley during the study, and the experimental group stayed for 45 days in high mountains (Anzob, 3375 m above sea level). On the day +30, all animals were sensitized with horse serum. On the 12th day of sensitization, blood was taken for analysis, and on the 15th day, an allergic reaction was provoked. We have revealed that, under high-altitude conditions, the severity of reaction was 1.5 times lower than in controls. Moreover, the animals kept in highlands exhibited lower contents of T and B lymphocytes, and IgE antibodies than in the control group. On the contrary, the numbers of phagocytically active neutrophils, as well as total effect of phagocytosis, proved to be higher in this group. This shift may be facilitated by hypoxia, since aerobic processes are known to prevail in the energy metabolism of lymphocytes, and anaerobic processes dominate in neutrophils. The allergic conditions are developed in three stages. Immunological stage is the first and main one, and allergic restructuring of the body immunity largely depends on it. What is the matter of reconstruction under the high-altitude conditions? We suggest, that, along with Haeckel–M ller biogenetic rule, there is also an immunogenetic law: “The activation sequence of events in the body’s defense system is a reproduction of phylogenesis, i.e., switching of subsequent link in defense system follows the evolutionary principles of complication and improvement. Namely, with respect to failing of previous link to completely eliminate the antigen in defense system”. One may conventionally consider that the first protective barrier against antigens is the most evolutionarily ancient structure, i.e., skin and mucous membrane; the second represents factors of nonspecific defense (phagocytosis, lysozyme, interferon, etc.); the third barrier is presented by cellular immunity (T effector cells, etc.), with humoral immunity serving as the fourth barrier. The fifth protective barrier provides evolutionarily late defense, i.e. allergic reaction, which is triggered by Ig E antibodies. On the mentioned basis, one may state that the decreased allergic reaction (the 5th barrier) in the animals from the experimental group was caused by adaptive changes in protective mechanisms of body. One may suggest that, under the high-altitude conditions an increase was observed in functional activity of phagocytes (2nd barrier), along with a decrease in activity of lymphocytes, i.e., cell populations responsible for the evolutionary later protective barriers.

Adaptive Two-Stream Consensus Network for Weakly-Supervised Temporal Action Localization.

Weakly-supervised temporal action localization (W-TAL) aims to classify and localize all action instances in untrimmed videos under only video-level supervision. Without frame-level annotations, it is challenging for W-TAL methods to clearly distinguish actions and background, which severely degrades the action boundary localization and action proposal scoring. In this paper, we present an adaptive two-stream consensus network (A-TSCN) to address this problem. Our A-TSCN features an iterative refinement training scheme: a frame-level pseudo ground truth is generated and iteratively updated from a late-fusion activation sequence, and used to provide frame-level supervision for improved model training. Besides, we introduce an adaptive attention normalization loss, which adaptively selects action and background snippets according to video attention distribution. By differentiating the attention values of the selected action snippets and background snippets, it forces the predicted attention to act as a binary selection and promotes the precise localization of action boundaries. Furthermore, we propose a video-level and a snippet-level uncertainty estimator, and they can mitigate the adverse effect caused by learning from noisy pseudo ground truth. Experiments conducted on the THUMOS14, ActivityNet v1.2, ActivityNet v1.3, and HACS datasets show that our A-TSCN outperforms current state-of-the-art methods, and even achieves comparable performance with several fully-supervised methods.

Convergent Double Coronary Sinus Potentials During Atrial Tachycardia

The analysis of the patterns and timing of coronary sinus activation provides a rapid stratification of the most likely macro-re-entrant atrial tachycardias and points toward the likely origin of centrifugal ones by comparing the left atrial and coronary sinus activation sequence and morphology during sinus rhythm and atrial tachycardia. The analysis of both the near- and far-field electrogram morphology of atrial signals also gives important clues in determining the mechanism of the arrhythmia.

Prevalence, clinical and angiography of Coronary Artery Disease in patients with chest pain with left bundle branch block in Iraqi Centers of Heart Disease

Introduction and Aim: Left bundle branch block (LBBB), is seen on the electrocardiograms, when the His-Purkinje system disrupts the normal sequence of activation is changed in the left bundle branch block, leading to specific appearance on the electrocardiograms. Left bundle branch blocks usually occur in patients associated with advanced heart conduction disorders. In this study we aimed to study the prevalence of significant CAD in patients with chest pain and left bundle branches block sent to invasive coronary angiography and study clinical and angiography with distribution of CAD risk factors in our study population. Methodology: This investigation is a single center retrospective cohort study that included 400 patients who underwent coronary angiography with left bundle branch block on their ECGs. The study was carried out in the Iraqi Center for Heart Disease between April 2017 and May 2022. Data regarding their age, gender, related risk factors, electrocardiography, echo and left ventricular function was noted. Data was subjected to statistical analysis using the Minitab program. Results: The prevalence of CAD was 41% among the 400 patients who had LBBB. Demographic data showed age, hypertension, and diabetes mellitus to be a risk factor associated with CAD. The related anatomy of the left bundle branch block in 98 patients showed single or multiple coronary artery disease and likely reduced ejection fraction (&lt;50%). Conclusion: The prevalence of LBBB is more common in males than in females. The biggest risk factor for cardiovascular disease in those with LBBB and coronary artery disease is hypertension, which is followed by age and diabetes mellitus. Thus, coronary angiography should be used in cardiac tests to identify CAD in individuals with LBBB.

Estimation of left ventricular activation sequence in patients with heart failure using two-dimensional speckle tracking echocardiography

Evaluation of longitudinal strain (LS) from two-dimensional echocardiography is useful for global and regional left ventricular (LV) dysfunction assessment. We determined whether the LS reflects contraction process in patients with asynchronous LV activation. We studied 144 patients with an ejection fraction ≤ 35%, who had left bundle branch block (LBBB, n = 42), right ventricular apical (RVA) pacing (n = 34), LV basal- or mid-lateral pacing (n = 23), and no conduction block (Narrow-QRS, n = 45). LS distribution maps were constructed using 3 standard apical views. The times from the QRS onset-to-early systolic positive peak (Q-EPpeak) and late systolic negative peak (Q-LNpeak) were measured to determine the beginning and end of contractions in each segment. Negative strain in LBBB initially appeared in the septum and basal-lateral contracted late. In RVA and LV pacing, the contracted area enlarged centrifugally from the pacing site. Narrow-QRS showed few regional differences in strain during the systolic period. The Q-EPpeak and Q-LNpeak exhibited similar sequences characterized by septum to basal-lateral via the apical regions in LBBB, apical to basal regions in RVA pacing, and lateral to a relatively large delayed contracted area between the apical- and basal-septum in LV pacing. Differences in Q-LNpeaks between the apical and basal segments in delayed contracted wall were 107 ± 30 ms in LBBB, 133 ± 46 ms in RVA pacing, and 37 ± 20 ms in LV pacing (p < 0.05, between QRS groups). Specific LV contraction processes were demonstrated by evaluating the LS distribution and time-to-peak strain. These evaluations may have potential to estimate the activation sequence in patients with asynchronous LV activation.

Mechanistic aspect for the atom transfer radical polymerization of itaconimide monomers with methyl methacrylate: a computational study

Abstract Atom transfer radical polymerization (ATRP) is a versatile &amp; famous technique for the synthesis of well defined molecular architectures. In ATRP, there is a dynamic equilibrium exists between active &amp; dormant species. Therefore, ATRP progress through a sequence of activation &amp; deactivation cycles, ending upon complete monomer consumption &amp; termination reactions are minimized. This paper presents a systematic computational study on kinetics &amp; thermodynamics associates in the ATRP of itaconimide monomers &amp; methyl methacrylate (MMA). For this, the copolymerization system is modeled as a unimer, dimer &amp; trimer of various itaconimides &amp; MMA monomer. The density functional theory with B3LYP functional &amp; 6–31 + G(d)/LanL2DZ basis sets is used in the prediction of geometries &amp; energetics associated with the dissociation of terminal R–X bond present in the unimer, dimer &amp; trimer. The relative equilibrium constant (K ATRP) for the ATRP activation/deactivation steps is calculated from the free energy values associated with dissociation of R–X bond. The relative K ATRP values of dimer &amp; trimer of selected monomers is compared with their respective unimer. From the transition state geometries of the dimeric propagating radical, activation energy is calculated. The gas phase rate coefficients for propagation (k p) (of itaconimides &amp; MMA copolymerization) are calculated using the standard transition state theory. The effect of system parameters such as solvent, temperature &amp; substituent on K ATRP &amp; k p values of dimer is investigated systematically. The change in the initiating system &amp; temperature has significant effect on k p values as compared to solvent &amp; various substituent. The K ATRP values of dimer &amp; trimer dormant species are higher as compared to their respective monomeric species. The neighboring monomer &amp; penultimate monomer plays vital role in kinetics &amp; thermodynamics associated with copolymerization. The obtained initial results show that the mechanism of copolymerization of itaconimide monomers &amp; MMA follows penultimate model.

An iterative neural processing sequence orchestrates feeding

Feeding requires sophisticated orchestration of neural processes to satiate appetite in natural, capricious settings. However, the complementary roles of discrete neural populations in orchestrating distinct behaviors and motivations throughout the feeding process are largely unknown. Here, we delineate the behavioral repertoire of mice by developing a machine-learning-assisted behavior tracking system and show that feeding is fragmented and divergent motivations for food consumption or environment exploration compete throughout the feeding process. An iterative activation sequence of agouti-related peptide (AgRP)-expressing neurons in arcuate (ARC) nucleus, GABAergic neurons in the lateral hypothalamus (LH), and in dorsal raphe (DR) orchestrate the preparation, initiation, and maintenance of feeding segments, respectively, via the resolution of motivational conflicts. The iterative neural processing sequence underlying the competition of divergent motivations further suggests a general rule for optimizing goal-directed behaviors.

Noninvasive electromyometrial imaging of human uterine maturation during term labor

Electromyometrial imaging (EMMI) was recently developed to image the three-dimensional (3D) uterine electrical activation during contractions noninvasively and accurately in sheep. Herein we describe the development and application of a human EMMI system to image and evaluate 3D uterine electrical activation patterns at high spatial and temporal resolution during human term labor. We demonstrate the successful integration of the human EMMI system during subjects’ clinical visits to generate noninvasively the uterine surface electrical potential maps, electrograms, and activation sequence through an inverse solution using up to 192 electrodes distributed around the abdomen surface. Quantitative indices, including the uterine activation curve, are developed and defined to characterize uterine surface contraction patterns. We thus show that the human EMMI system can provide detailed 3D images and quantification of uterine contractions as well as novel insights into the role of human uterine maturation during labor progression.

Trifunctional nanoprecipitates ductilize and toughen a strong laminated metastable titanium alloy

Metastability-engineering, e.g., transformation-induced plasticity (TRIP), can enhance the ductility of alloys, however it often comes at the expense of relatively low yield strength. Here, using a metastable Ti-1Al-8.5Mo-2.8Cr-2.7Zr (wt.%) alloy as a model material, we fabricate a heterogeneous laminated structure decorated by multiple-morphological α-nanoprecipitates. The hard α nanoprecipitate in our alloy acts not only as a strengthener to the material, but also as a local stress raiser to activate TRIP in the soft matrix for great uniform elongation and as a promoter to trigger interfacial delamination toughening for superior fracture resistance. By elaborately manipulating the activation sequence of lamellar-thickness-dependent deformation mechanisms in Ti-1Al-8.5Mo-2.8Cr-2.7Zr alloys, the yield strength of the present submicron-laminated alloy is twice that of equiaxed-coarse grained alloys with the same composition, yet without sacrificing the large uniform elongation. The desired mechanical properties enabled by this strategy combining the laminated metastable structure and trifunctional nanoprecipitates provide new insights into designing ultra-strong and ductile materials with great toughness.

Multiple Temporal Pooling Mechanisms for Weakly Supervised Temporal Action Localization

Recent action localization works learn in a weakly supervised manner to avoid the expensive cost of human labeling. Those works are mostly based on the Multiple Instance Learning framework, where temporal pooling is an indispensable part that usually relies on the guidance of snippet-level Class Activation Sequences (CAS) . However, we observe that previous works only leverage a simple convolutional neural network for the generation of CAS, which ignores the weak discriminative foreground action segments and the background ones, and meanwhile, the relationship between different actions has not been considered. To solve this problem, we propose multiple temporal pooling mechanisms (MTP) for a more sufficient information utilization. Specifically, with the design of the Foreground Variance Branch, Dual Foreground Attention Branch and Hybrid Attention Fine-tuning Branch, MTP can leverage more effective information from different aspects and generate different CASs to guide the learning of temporal pooling. Moreover, different loss functions are designed for a better optimization of individual branches, aiming to effectively distinguish the action from the background. Our method shows excellent results on the THUMOS14 and ActivityNet1.2 datasets.

Release of immunomodulatory peptides at bacterial membrane interfaces as a novel strategy to fight microorganisms

Cationic and amphiphilic peptides can be used as homing devices to accumulate conjugated antibiotics to bacteria-enriched sites and promote efficient microbial killing. However, just as important as tackling bacterial infections, is the modulation of the immune response in this complex microenvironment. In the present report, we designed a peptide chimaera called Chim2, formed by a membrane-active module, an enzyme hydrolysis site and a formyl peptide receptor 2 (FPR2) agonist. This molecule was designed to adsorb onto bacterial membranes, promote their lysis, and upon hydrolysis by local enzymes, release the FPR2 agonist sequence for activation and recruitment of immune cells. We synthesized the isolated peptide modules of Chim2 and characterized their biological activities independently and as a single polypeptide chain. We conducted antimicrobial assays, along with other tests aiming at the analyses of the cellular and immunological responses. In addition, assays using vesicles as models of eukaryotic and prokaryotic membranes were conducted and solution structures of Chim2 were generated by 1H NMR. Chim2 is antimicrobial, adsorbs preferentially to negatively charged vesicles while adopting an α-helix structure and exposes its disorganized tail to the solvent, which facilitates hydrolysis by tryptase-like enzymes, allowing the release of the FPR2 agonist fragment. This fragment was shown to induce accumulation of the cellular activation marker, lipid bodies, in mouse macrophages and the release of immunomodulatory interleukins. In conclusion, these data demonstrate that peptides with antimicrobial and immunomodulatory activities can be considered for further development as drugs.

Co-optimizing component allocation and activation sequence in heterogeneous 1-out-of-n standby system exposed to shocks

• A heterogeneous 1-out-of- n standby system must perform a given amount of work. • System components are located at positions with different shock rates. • Components shock resistance deteriorates with number of survived shocks. • Algorithm for mission success probability evaluation is suggested. • Optimal component allocation and activation sequencing problem is solved. Motivated by real-world applications of cloud computing and unmanned aerial vehicles (UAVs), this paper models a heterogeneous 1-out-of- n standby system with n components that can be allocated to different physical positions exposed to different random shocks. The shocks cause a component to fail with certain probability, depending on the shock rate determined by the component's position and mode (standby or operation). Different components have different shock resistances. The system must perform a specified amount of work to accomplish the mission. The mission success probability (MSP) depends on both position allocation and activation sequence of the system components. We make contributions by formulating and solving the joint optimal allocation and activation sequence (AAS) problem to maximize the MSP. The solution methodology encloses a new numerical algorithm for deriving the MSP of the considered heterogeneous 1-out-of- n standby system under any given AAS, and the application of the genetic algorithm for solving the proposed optimization problem. A detailed case study of a multi-UAV standby system performing a surveillance mission is provided to demonstrate the proposed model and influences of several parameters (component performance rate, component shock resistance parameter, and shock rates) on the MSP and AAS optimization solutions.

A comprehensive framework for evaluation of high pacing frequency and arrhythmic optical mapping signals.

Introduction: High pacing frequency or irregular activity due to arrhythmia produces complex optical mapping signals and challenges for processing. The objective is to establish an automated activation time-based analytical framework applicable to optical mapping images of complex electrical behavior. Methods: Optical mapping signals with varying complexity from sheep (N = 7) ventricular preparations were examined. Windows of activation centered on each action potential upstroke were derived using Hilbert transform phase. Upstroke morphology was evaluated for potential multiple activation components and peaks of upstroke signal derivatives defined activation time. Spatially and temporally clustered activation time points were grouped in to wave fronts for individual processing. Each activation time point was evaluated for corresponding repolarization times. Each wave front was subsequently classified based on repetitive or non-repetitive events. Wave fronts were evaluated for activation time minima defining sites of wave front origin. A visualization tool was further developed to probe dynamically the ensemble activation sequence. Results: Our framework facilitated activation time mapping during complex dynamic events including transitions to rotor-like reentry and ventricular fibrillation. We showed that using fixed AT windows to extract AT maps can impair interpretation of the activation sequence. However, the phase windowing of action potential upstrokes enabled accurate recapitulation of repetitive behavior, providing spatially coherent activation patterns. We further demonstrate that grouping the spatio-temporal distribution of AT points in to coherent wave fronts, facilitated interpretation of isolated conduction events, such as conduction slowing, and to derive dynamic changes in repolarization properties. Focal origins precisely detected sites of stimulation origin and breakthrough for individual wave fronts. Furthermore, a visualization tool to dynamically probe activation time windows during reentry revealed a critical single static line of conduction slowing associated with the rotation core. Conclusion: This comprehensive analytical framework enables detailed quantitative assessment and visualization of complex electrical behavior.

Proarrhythmic effect of bipolar epicardial left ventricular stimulation in CRT resolved maintaining biventricular pacing with unipolar-cathodical configuration: A peculiar case report.

The effect of cardiac resynchronization therapy (CRT) on the risk of ventricular arrhythmias is controversial. Several studies reported a decreased risk, but some studies reported a potential proarrhythmic effect of epicardial left ventricular pacing resolved upon discontinuation of biventricular pacing (BiVp). A 67-year-old woman with a history of heart failure due to nonischemic cardiomyopathy and left bundle branch block was hospitalized for CRT device implantation. Unpredictably, as soon as the leads have been connected to the generator, an electrical storm (ES) occurred with relapsing self-resolving polymorphic ventricular tachycardia (PVT) triggered by ventricular extra beats with short-long-short sequences. The ES was resolved without interrupting BiVp switching to unipolar left ventricular (LV) pacing. This allowed to keep CRT active with extreme clinical benefit for the patient and to demonstrate that the cause of the PVT was the anodic capture of bipolar LV stimulation. Reverse electrical remodeling was also demonstrated after 3 months of effective BiVp. Proarrhythmic effect of CRT is a rare but significant complication of CRT, and it may compel to discontinuation of the BiVp. The reversal of the physiological transmural activation sequence of epicardial LV pacing and subsequent prolonging of corrected QT interval have been speculated as the most probable explanation, but our case highlights the possibility that the anodic capture may play a relevant role in PVT genesis.