Open State Research Articles

The open to closed D-loop conformational switch determines length in filopodia-like actin bundles

Filopodia, microspikes and cytonemes are implicated in sensing the environment and in dissemination of morphogens, organelles and pathogens across tissues. Their major structural component is parallel bundles of actin filaments that assemble from the cell membrane. Whilst the length of filopodia is central to their function, it is not known how their lengths are determined by actin bundle dynamics. Here, we identified a set of monoclonal antibodies that lengthen filopodia-like structures formed in a cell-free reconstitution system, and used them to uncover a key molecular switch governing length regulation. Using immunolabelling, enzyme-linked immunosorbent assays, immunoprecipitation and immunoblock experiments, we identified four antibodies that lengthen actin bundles by selectively binding the open DNase 1-binding loop (D-loop) of actin filaments. The antibodies inhibit actin disassembly and their effects can be alleviated by providing additional actin or cofilin. This work indicates that maintaining an open state of the actin filament D-loop is a mechanism of generating long filopodia-like actin bundles.

DrowsiScan: Early Detection of Driver Drowsiness using Deep Learning

In recent years, the rise in car accident fatalities has become a significant global concern, with road security emerging as a critical issue. Among the various factors contributing to road accidents, driver drowsiness stands out as a leading cause. This project aims to address this issue by developing a real-time driver drowsiness detection system using advanced machine vision techniques and deep learning models. Drowsy Driver Detection System has been developed using a non- intrusive machine vision based concepts. The system uses a small snap security camera that points directly towards the driver’s face and monitors the driver eyes in order to descry fatigue. In such a case when fatigue is detected, a warning signal is issued to warn the driver. This report describes how to detect the eyes, and also how to determine if the eyes are open state or close state. The algorithm developed is unique to any presently published papers, which was a primary ideal objective of the project. The system deals with using information attained for the double interpretation of the image to find the edges of the face, which narrows the area of where the eyes located. Once the face is detected, the eyes are found by computing the horizontal averages in the area. Taking into account the knowledge that eye regions in the face present great intensity changes, the eyes are located by chancing the significant intensity changes in the face. Once the eyes are located, measuring the distances between the intensity changes in the eye area determine whether the eyes are in open state or close state.A large distance corresponds to eye check. still, the system draws the conclusion that the driver is falling asleep and issues a warning signal, If the eyes are set up closed for 5 successive frames. The system is also suitable to detect when the eyes can not be set up, and works under reasonable lighting conditions.

Unconventional Thermal Rectification in Assemblies of Supertetrahedral T3-Type Sn4In6Se20 Clusters.

Going beyond the conventional design paradigm with atoms as building blocks, we propose the concept of cluster-assembled thermal rectifiers comprising metal chalcogenide supertetrahedral clusters. Different from the experimentally reported T4,∞ and T5,∞, for the first time we assemble T3-Sn4In6Se20 clusters into a stable T3,∞ framework without needing extra ions, based on which the thermal rectification (TR) effect is explored using machine-learning molecular dynamics and the mode-resolved phonon Boltzmann transport equation. The tetrahedron-shaped cluster assembly serves as a novel TR switch, where the open state shows an outstanding TR efficiency (∼40%) arising from the asymmetric lateral confinement due to not only the phonon particle behavior but also the phonon wave nature. The prism-shaped assembly has a symmetric skeleton but with asymmetric surface roughness induced by clusters, thus exhibiting an unusual TR effect, distinguished from atom-based symmetric systems with atomically flat surfaces. Our findings demonstrate the unique potential of cluster assemblies for unconventional thermal rectification.

Kinetics-Based State Definitions for Discrete Binding Conformations of T4 L99A in MD via Markov State Modeling.

As a model system, the binding pocket of the L99A mutant of T4 lysozyme has been the subject of numerous computational free energy studies. However, previous studies have failed to fully sample and account for the observed changes in the binding pocket of T4 L99A upon binding of a congeneric ligand series, limiting the accuracy of results. In this work, we resolve the closed, intermediate, and open states for T4 L99A previously reported in experiment in MD and establish definitions for these states based on the dynamics of the system. From this analysis, we arrive at two primary conclusions. First, assignment of simulation trajectories into discrete states should not be done simply based on RMSD to crystal structures as this can result in misassignment of states. Second, the different metastable conformations studied here need to be carefully treated, as we estimate the time scales for conformational interconversion to be on the order of 102 to 103 ns─far longer than time scales for typical binding calculations. We conclude with a discussion on the need to develop enhanced sampling methods to generally account for significant changes in protein conformation due to relatively small ligand perturbations.

Membrane lipid homeostasis dually regulates conformational transition of phosphoethanolamine transferase EptA

The phosphoethanolamine transferase EptA utilizes phosphatidylethanolamine (PE) in the bacterial cell membrane to modify the structure of lipopolysaccharide, thereby conferring antimicrobial resistance on Gram-negative pathogens. Previous studies have indicated that excessive consumption of PE can disrupt the cell membrane, leading to cell death. This implies the presence of a regulatory mechanism for EptA catalysis to maintain a balance between antimicrobial resistance and bacterial growth. Through microsecond-scale all-atom molecular dynamics simulations, we demonstrate that membrane lipid homeostasis modulates the conformational transition and catalytic activation of EptA. The conformation of EptA oscillates between closed and open states, ensuring the precise spatiotemporal sequence of substrates binding. Interestingly, the conformation of EptA is significantly influenced by its surrounding lipid microenvironment, particularly the PE proportion in the membrane. PE-rich membrane conditions initiate and stabilize the open conformation of EptA through both orthosteric and allosteric effects. Importantly, the reaction mediated by EptA gradually depletes PE in the membrane, ultimately hindering its conformational transition and catalytic activation. These findings collectively establish a self-promoted model, illustrating the regulatory mechanism of EptA during the development of antibiotic resistance.

A structural analysis of the splice-specific functional impact of the pathogenic familial hemiplegic migraine type 1 S218L mutation on Cav2.1 P/Q-type channel gating

P/Q-type (Cav2.1) calcium channels mediate Ca2+ influx essential for neuronal excitability and synaptic transmission. The CACNA1A gene, encoding the Cav2.1 pore forming subunit, is highly expressed throughout the mammalian central nervous system. Alternative splicing of Cav2.1 pre-mRNA generates diverse channel isoforms with distinct biophysical properties and drug affinities, which are differentially expressed in nerve tissues. Splicing variants can also affect channel function under pathological conditions although their phenotypic implication concerning inherited neurological disorders linked to CACNA1A mutations remains unknown. Here, we quantified the expression of Cav2.1 exon 24 (e24) spliced transcripts in human nervous system samples, finding different levels of expression within discrete regions. The corresponding Cav2.1 variants, differing by the presence (+) or absence (Δ) of Ser-Ser-Thr-Arg residues (SSTR) in the domain III S3-S4 linker, were functionally characterized using patch clamp recordings. Further, the + /ΔSSTR isoforms were used to demonstrate the differential impact of the Familial Hemiplegic Migraine Type 1 (FHM-1) S218L mutation, located in the domain I S4-S5 linker, on the molecular structure and electrophysiological properties of Cav2.1 isoforms. S218L has a prominent effect on the voltage-dependence of activation of +SSTR channels when compared to ΔSSTR, indicating a differential effect of the mutation depending on splice-variant context. Structural modeling based upon Cav2.1 cryo-EM data provided further insight reflecting independent contributions of amino acids in distant regions of the channel on gating properties. Our modelling indicates that by increasing hydrophobicity the Leu218 mutation contributes to stabilizing a structural conformation in which the domain I S4-S5 linker is oriented alongside the inner plasma membrane, similar to that occurring when S4 is translocated upon activation.The SSTR insertion appears to exert an influence in the local electric field of domain III due to an change in the distribution of positively charged regions surrounding the voltage sensing domain, which we hypothesize impacts its movement during the transition to the open state. In summary, we reveal molecular changes correlated with distinct functional effects provoked by S218L FHM-1 mutation in hCav2.1 splice isoforms whose differential expression could impact the manifestation of the neurological disorder.

Structural basis for inositol pyrophosphate gating of the phosphate channel XPR1.

Precise regulation of intracellular phosphate (Pi) is critical for cellular function, with xenotropic and polytropic retrovirus receptor 1 (XPR1) serving as the sole Pi exporter in humans. The mechanism of Pi efflux, activated by inositol pyrophosphates (PP-IPs), has remained unclear. This study presents cryo-electron microscopy structures of XPR1 in multiple conformations, revealing a transmembrane pathway for Pi export and a dual-binding activation pattern for PP-IPs. A canonical binding site is located at the dimeric interface of Syg1/Pho81/XPR1 (SPX) domains, and a second site, biased toward PP-IPs, is found between the transmembrane and SPX domains. By integrating structural studies with electrophysiological analyses, we characterized XPR1 as an inositol phosphates (IPs)/PP-IPs-activated phosphate channel. The interplay among its transmembrane domains, SPX domains, and IPs/PP-IPs orchestrates the conformational transition between its closed and open states.

Ratio of AT and GC Pairs in the Zones of Open States Genesis in DNA Molecules.

There is an assumption about the presence of a specific nucleotides sequence in DNA molecule, which contributes to the genesis of open states (OS). In addition, it would be logical to assume that OS zones should form in DNA regions with a large proportion of Adenine-Thymine (AT) pairs, since they contain fewer hydrogen bonds than Guanine- Cytosine (GC) base pairs. However, studies have shown that in areas rich in AT pairs, the probability of open states will not always be higher. In this work, for two genes containing different numbers of regions with a large AT pairs proportion, we calculated the ratio of AT and GC pairs in the OS zones. For calculations, we used a coarse-grained angular mechanical DNA model. It has been established that small OS zones can appear on any part of the DNA molecule. They mainly consist of AT pairs, but as the size of OS zones increases, the content of AT pairs in them decreases. The occurrence of long-length OS zones is "tied" to regions of the DNA molecule with a large proportion of AT pairs; if there are several such areas, then, depending on the magnitude of the torque, OS zones can arise in different areas of the gene. Thus, the genesis probability of large OS zones in a DNA segment depends not only on the "strength" of the nucleotide sequence of this area, but also on the factors determining the dynamics of DNA.

Numerical Simulation of the Diffusion Characteristics of Odor Pollutants of Waste Bunkers in Waste Incineration Plant

This paper utilizes the waste bunker of a waste incineration plant as the analysis model. It analyzes the airflow characteristics under various unloading door opening states and the air flow velocity through CFD simulation. The simulation analysis results show that when one unloading door is opened, it is recommended to adjust the opening amplitude or set an air outlet to optimize the airflow distribution. If two unloading doors are opened, it is advised to prioritize the two middle unloading doors (M4, M5) or the two rightmost doors (M7, M8). Furthermore, the exhaust port located relatively far from the unloading door should be closed to reduce the turbulence of the airflow. When all unloading doors are opened, the air flow velocity at the unloading door needs to be increased to achieve an efficient exhaust effect and prevent negative pressure problems at low speed. The results offer theoretical support for odor control technologies and provide valuable design recommendations for air outlets and unloading doors in municipal waste incineration plants. Additionally, this study proposes optimization strategies and effective solutions for addressing odor pollutant diffusion in waste incineration facilities.

Unveiling Cas8 Dynamics and Regulation within a transposon-encoded Cascade-TniQ Complex.

The Vibrio cholerae Cascade-TniQ complex unveiled a new paradigm in biology, demonstrating that CRISPR-associated proteins can direct DNA transposition. Despite the tremendous potential of "knocking in" genes at desired sites, the mechanisms underlying DNA binding and transposition remain elusive. In this system, a conformational change of the Cas8 protein is essential for DNA binding, yet how it occurs is unclear. Here, structural modeling and free energy simulations reconstruct the Cas8 helical bundle and reveal an open-to-close conformational transition at key steps of the complex's function. We show that when Cascade-TniQ binds RNA, the Cas8 bundle changes conformation mediated by the interaction with the Cas7.1 protein. This interaction alleviates unfavorable contacts and synchronizes Cas8's shift with neighboring subunits, lowering the barrier for the transition to the open state, a critical requirement for DNA binding. As DNA fully pairs with RNA, the open state becomes increasingly accessible, favoring interactions with DNA and aiding the formation of an R-loop. These outcomes provide the first dynamic representation of a critical conformational change in one of the largest CRISPR systems and illustrate its role at critical steps of the Cascade-TniQ biophysical function, advancing our understanding of nucleic acid binding and transposition mechanisms.

Altering Active-Site Loop Dynamics Enhances Standalone Activity of the Tryptophan Synthase Alpha Subunit.

The α-subunit (TrpA) of the allosterically regulated bifunctional tryptophan synthase αββα enzyme catalyzes the retro-aldol cleavage of indole-glycerol phosphate (IGP) to d-glyceraldehyde 3-phosphate (G3P) and indole. The activity of the enzyme is highly dependent on the β-subunit (TrpB), which allosterically regulates and activates TrpA for enhanced function. This contrasts with the homologous BX1 enzyme from Zea mays that can catalyze the same reaction as TrpA without requiring the presence of any additional binding partner. In this study, we computationally evaluated and compared the conformational landscapes of the homologous ZmBX1 and ZmTrpA enzymes. Our results indicate that enhanced TrpA standalone activity requires the modulation of the conformational dynamics of two relevant active-site loops, loop 6 and 2, that need to be synchronized for accessing the catalytically activated closed state for IGP cleavage, as well as open states for favoring indole/G3P release. Taking as inspiration the evolutionary blueprint ZmBX1 and using our developed correlation-based tool shortest path map focused on the rate-determining conformational transition leading to the catalytically activated closed state, we computationally designed a variant named ZmTrpASPM4-L6BX1, which displays a 163-fold improvement in catalytic efficiency for the retro-aldol cleavage of IGP. This study showcases the importance of fine-tuning the conformational dynamics of active-site loops for altering and improving function, especially in those cases in which a conformational change is rate determining.

Computational reverse protein engineering of a lipase from Pseudomonas aeruginosa in n-hexane

This study used computational methodologies to investigate the behavior of Pseudomonas aeruginosa PAO1 lipase (PAL) in n-hexane. Molecular dynamics simulations were employed to evaluate perturbations on the structural stability of the secondary structures of the lipase. B-factor analysis served as an indirect stability measure, while gorge radii indicated enzymatic activity. Findings reveal that the α3 helix significantly influences the structural stability of PAL, though stability-activity relationships remain complex. Mutant forms characterized by dual-lids — including mutants of 310−2, α6, and the triple-point mutant of the eight β-strands — exhibited highly open gorges throughout simulations, with flexibility in typically rigid residues of non-310 lid1 helices and highly flexible dual-lid 310 helices. Perturbation of lid 310−2, especially prominent in the α8 mutant, suggests a potential trigger mechanism, as its gorge radii fluctuated considerably between open and closed states. Other significant regions include the α2 helix and the α7–α8 loop, which displayed substantial flexibility in both highly open and closed systems, indicating their roles as hinges in the dual-lid configuration. Most mutant forms tended to remain open, with only three mutants — α7, α1, and α2 — remaining rigidly closed, supporting reports that lipases prefer an open state in organic media. For potential enhancement, the proline mutant of 310−2 (R119P) emerged as the most promising, balancing stability and dual-lid flexibility. Collectively, these findings offer insights into structural dynamics of PAL, elucidate its gating mechanism, and identify strategies for enhancing stability, with implications for biotechnological applications.

Nanoparticles encapsulating phosphatidylinositol derivatives promote neuroprotection and functional improvement in preclinical models of ALS via a long-lasting activation of TRPML1 lysosomal channel

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease currently incurable, in which motor neuron degeneration leads to voluntary skeletal muscle atrophy. Molecularly, ALS is characterized by protein aggregation, synaptic and organellar dysfunction, and Ca2+ dyshomeostasis. Of interest, autophagy dysfunction is emerging as one of the main putative targets of ALS therapy. A tune regulation of this cleansing process is affordable by a proper stimulation of TRPML1, one of the main lysosomal channels. However, TRPML1 activation by PI(3,5)P2 has low open probability to remain in an active conformation. To overcome this drawback we developed a lipid-based formulation of PI(3,5)P2 whose putative therapeutic potential has been tested in in vitro and in vivo ALS models.Pharmacodynamic properties of PI(3,5)P2 lipid-based formulations (F1 and F2) on TRPML1 activity have been characterized by means of patch-clamp electrophysiology and Fura-2AM video-imaging in motor neuronal cells. Once selected for the ability to stabilize TRPML1 activity, the most effective preparation F1 was studied in vivo to measure neuromuscular function and survival of SOD1G93A ALS mice, thereby establishing its therapeutic profile.F1, but not PI(3,5)P2 alone, stabilized the open state of the lysosomal channel TRPML1 and increased the persistence of intracellular calcium concentration ([Ca2+]i). Then, F1 was effective in delaying motor neuron loss, improving innervated endplants and muscle performance in SOD1G93A mice, extending overall lifespan by an average of 10 days. Of note F1 prevented gliosis and autophagy dysfunction in ALS mice by restoring PI(3,5)P2 level.Our novel self-assembling lipidic formulation for PI(3,5)P2 delivery exerts a neuroprotective effect in preclinical models of ALS mainly regulating dysfunctional autophagy through TRPML1 activity stabilization.

Identification of characteristics of conceptual prototype of microprocessor resource-saving relay protection system

The object of the study is the conceptual prototype of a microprocessor resource-saving relay protection system. Currently, relay protection ensures electrical networks reliable and efficient work, however, the traditional architecture is proprietary, not allowing to fix and replace damaged parts without a company specialist. Therefore, the open-architecture relay protection is a very pressing issue, but the problem lies in meeting the relay protection requirements. The data transmission protocols nRF and ESP-NOW, Hall sensors evaluation for AC current measurement determination and sensor accuracy improvement was implemented. Experimental validation demonstrated that nRF and ESP-NOW protocols meet the delay and reliability requirements, however, the nRF protocol is more suitable due to its flexibility and obstacle penetration. The data demonstrated that the most effective conditions are without obstacles at 15 meters from the modem and with obstacles 5 meters from the modem. The experiment of Hall sensors characteristics determination demonstrated the accuracy of current measurement with the set values of the opening and closing currents. Nevertheless, it is not accurate (12.45 %) for the relay protection application. Therefore, the application of the changing values of the opening and closing currents is more effective and accuracy reaches 6.92 %. As a result, the service life of the Hall sensor was determined, and even after 10 million openings, the open state time remained unchanged. Therefore, the approximation function for current amplitude determination depending on open state time was found. On the other hand, Hall sensors may suffer from temperature drift and require further optimization to be fully reliable. The study limitation is the current range from 0 to 800 A

Динаміка електрокерованих паливних клапанів реактивних двигунів малої тяги на «зеленому» паливі

Recently, the leading space countries have paid much attention to searching for and using new types of untoxic “green” propellants. Developments of 0.1 N to 220 N “green”-propellant thrusters have been reported, and some of them have been successfully tested in flight conditions. Liquid-propellant spacecraft thrusters are actuators of a spacecraft in-orbit motion control system. They are actuated from command signals of the spacecraft control system by applying a voltage to the electromagnet coils of the propellant valves of each of the engines that are to feed the propellant during a specified time interval to produce a required thrust impulse. A problem common to liquid-propellant thrusters irrespective of the propellant type is a thruster start-up delay with respect to the command signal and a thruster shut-down delay with respect to the electromagnet coil de-energizing. In other words, the thruster response is shifted with respect to the command signal. Because of this, the valve parameters must be chosen in such a way as to minimize the delay effect. The goal of this work is to determine design parameters of electrically controlled propellant valves that would provide an efficient in-orbit operation of “green”-propellant thrusters with a minimum of electric energy consumption. To determine these parameters, use was made of a branch standard, the procedure of work with which was based on empirical data and verified by numerical simulation. The key factor in shortening the thruster start-up delay is to reduce the seat-to-tip valve plate travel on condition that a required propellant amount is fed to the reaction chamber. However, this extends the shut-down delay, which has a harmful effect in the short-impulse operation mode. It is shown by calculation that after the electromagnetic parameters have reached their steady-state values, the voltage can be reduced by 30 to 40 per cent of its nominal value with the valve kept in an open state, after which the valve closes with a shorter delay. In addition, this way of valve energizing reduces the total electric energy consumption for valve operation. The mathematical model of valve dynamics allows one to determine the valve operation parameters in the case of short command signals probable in flight conditions. In such a case, a valve does not open to a full extent, which results in a low specific impulse. The results of this study may be used in the development of “green”-propellant thrusters.

Assessing Drug Product Shelf Life Using the Accelerated Stability Assessment Program: A Case Study of a GLPG4399 Capsule Formulation.

Objective: To evaluate and project the shelf life of GLPG4399, an early-phase clinical drug formulation by applying the Accelerated Stability Assessment Program (ASAP) approach. Methods: Forced degradation conditions were implemented to identify the stability-limiting degradation product. The drug and its degradation products were separated using a validated liquid chromatography method. Then, the selected clinical capsule formulation was placed in a glass vial and exposed to accelerated short-term conditions of combinations of high- and low-level heat and humidity in an open state for 5 weeks. The liquid chromatography results were evaluated using the ASAP, which is based on the moisture-modified Arrhenius principle. The resulting data were fitted using a suitable diffusion kinetics method. Results: The developed model was applied to predict the shelf life of the drug product when using clinically appropriate primary packaging (high-density polyethylene container). The derived stability parameters of the moisture-modified Arrhenius equation were the Arrhenius collision frequency, activation energy, and humidity sensitivity constant. The goodness of fit parameters R2 (>0.95) and goodness of prediction Q2 (>0.80) parameters for the selected model were acceptable. The results of the accelerated, short-term stability study were verified against real-time, long-term 12-month data. Conclusions: We demonstrated the application of the ASAP approach to evaluate the shelf life of a GLPG4399 solid capsule formulation. The studied ASAP approach can be extended to evaluate the stability and shelf-life estimations of other early-phase clinical formulations.

The Effects of Inhibitor Chivosazole A on Actin Interacting with Profilin: A Theoretical Study

AbstractActin is highly conserved and contributes to numerous cellular activities. Profilin, one of actin binding proteins, promotes the exchange rate of nucleotide of actin, which leads to a fast elongation of actin filament. To slow down the elongation of filament, chivosazole A (ChivoA) is developed as an inhibitor of blocking actin‐profilin interaction. Intriguingly, known from the solved crystal structure, ChivoA does not bind on the interface between actin and profilin. Here, molecular dynamics (MD) simulation is used to study the possible mechanism how ChivoA inhibits actin‐profilin interaction. First, principal component analysis and representative structures comparisons reveal that the conformation of ChivoA‐bound actin is restrained at a closed state, whereas a trend toward an open state is found in profilin‐bound actin. Then, Peptide Gaussian accelerated MD shows that ChivoA limits the ability of the DNase I binding loop (D‐loop) swings and enlarges a distance between two major profilin binding regions. On the contrary, the distance between these two regions of profilin‐bound actin decreases in a clamp‐like motion mode. Finally, binding energies are calculated by molecular mechanics/poisson‐boltzmann surface area method and display that the ChivoA‐bound actin is less favorable for profilin binding.

Evaluation of fatigue damage of structural steel based on attenuation of laser-induced surface acoustic wave

ABSTRACT In this paper, the fatigue damage degree of low-alloy structural steel is evaluated by using the attenuation characteristics of laser-induced surface acoustic wave (SAW) during propagation. Taking the typical structural steel material Q345 as an example, a cracks model of fatigue damage is established, and the finite element method is used to solve the model. The results showed that the attenuation coefficient of SAW can reflect the depth and density of fatigue cracks. The surface measurement experiments of specimens with stress cycles of 0, 50000, 100000, 150000, and 200,000 showed that with the increase of stress cycles, the attenuation coefficient of SAW increases as a whole, indicating that it is feasible to evaluate the fatigue damage degree based on the attenuation of SAW. A method of applying tensile stress to the material to improve the sensitivity of fatigue damage evaluation is proposed. The tensile stress is used to offset the horizontal amplitude of the SAW, keeping the fatigue cracks in an open state and increasing the attenuation coefficient of SAW. The attenuation coefficient measurement experiment shows that this method is feasible.

Variability in youth coach concussion education requirements across states.

Youth sports coaches play a critical role in proper concussion recognition and management, reinforcing the need for coach concussion education. As of 2021, most states have statutory and policy measures mandating concussion education for coaches. In practice, these mandates have been enacted through state legislatures and their respective youth sport governing bodies. Prior studies have found significant variations in the contents of state-level concussion risk reduction policies and have raised questions about their specificity. To expand on previous analyses to provide an overview of youth sports coach concussion education, highlighting variations in state policies and discrepancies between state mandates and youth sport governing bodies. This report utilized qualitative content analysis to characterize and compare U.S. state and governing body concussion education requirements for youth sport coaches. State concussion statutes were identified via the National Conference of State Legislatures and Open States databases, and governing body handbooks/bylaws were obtained via their websites. Two researchers independently coded the policies, and discrepancies were resolved through consensus meetings with additional youth traumatic brain injury experts. We found significant variability in educational requirements and their implementation. A majority (68%; n = 34) of states require the completion of concussion education training for coaches. Notably, many states designate responsibility for enforcement and implementation of provisions to another party but just four state statutes delineate explicit consequences for noncompliance. Additionally, only 12 state statutes extend mandates to noninterscholastic sports, limiting their reach. In most cases, independent sanctioning authorities implement more stringent policies than the minimum acceptable standard established by state law. Our findings provide a coded data set of youth coach concussion laws and independent sanctioning authority guidelines that can be used in future research efforts. Further research investigating a relationship between the strength of coach concussion education policies and relevant youth and adolescent concussion-related metrics is required.

Fluctuations in Medium Viscosity May Affect the Stability of the CAG Tract in the ATXN2 Gene.

Background: Trinucleotide repeats are the cause of many neurodegenerative diseases that are currently incurable. In this regard, the question of the causes of occurrence and methods of prevention or treatment of diseases caused by the expansion of repeats in the CAG tract of the ATXN2 gene remains relevant. Previously, it was shown that the frequency of occurrence of additional OS (open states) zones increases with increasing length of the CAG tract, and the value inverse to the frequency correlates with the age of disease onset. Methods: In this work, the influence of the viscosity of the medium and the external torque on the stability of the CAG tract in the ATXN2 gene was studied using mathematical modeling methods. Results: It has been established that the probability of the appearance of additional OS zones of significant size increases with an increase in the CAG of the tract (k > 40 CAG repeats) for all viscosity values, however, at k ≤ 40, the change in viscosity does not significantly affect the probability of additional OS zones in the tract. Conclusions: It was found that under normal conditions (absence of pathology), viscosity does not have a reliable effect on the stability of the DNA molecule, but when pathology appears, an increase in viscosity contributes to an increase in DNA stability, and, accordingly, a decrease has a negative effect on the stabilization of the DNA molecule. In the zone of close to incomplete penetrance of the disease, viscosity does not have a reliable effect on the stability of the CAG tract.