Non-active Regions Research Articles

Super-Resolution Analysis of the Origins of the Elementary Events of ER Calcium Release in Dorsal Root Ganglion Neurons.

Coordinated events of calcium (Ca2+) released from the endoplasmic reticulum (ER) are key second messengers in excitable cells. In pain-sensing dorsal root ganglion (DRG) neurons, these events can be observed as Ca2+ sparks, produced by a combination of ryanodine receptors (RyR) and inositol 1,4,5-triphosphate receptors (IP3R1). These microscopic signals offer the neuronal cells with a possible means of modulating the subplasmalemmal Ca2+ handling, initiating vesicular exocytosis. With super-resolution dSTORM and expansion microscopies, we visualised the nanoscale distributions of both RyR and IP3R1 that featured loosely organised clusters in the subplasmalemmal regions of cultured rat DRG somata. We adapted a novel correlative microscopy protocol to examine the nanoscale patterns of RyR and IP3R1 in the locality of each Ca2+ spark. We found that most subplasmalemmal sparks correlated with relatively small groups of RyR whilst larger sparks were often associated with larger groups of IP3R1. These data also showed spontaneous Ca2+ sparks in <30% of the subplasmalemmal cell area but consisted of both these channel species at a 3.8-5 times higher density than in nonactive regions of the cell. Taken together, these observations reveal distinct patterns and length scales of RyR and IP3R1 co-clustering at contact sites between the ER and the surface plasmalemma that encode the positions and the quantity of Ca2+ released at each Ca2+ spark.

Development of Forbush Decreases Associated with Coronal Ejections from Active Regions and non-Active Regions

In this paper, we study the development of Forbush decreases associated with coronal mass ejectionsfrom active regions accompanied by solar flares and filament eruptions from non-active regions usingthe database of Forbush effects and interplanetary disturbances created at IZMIRAN. We compared thedevelopment of two types of Forbush decreases during solar cycles 23–24, the maxima of these cycles, andthe minimum between them. Using statistical methods, we studied the distributions of time intervals from thebeginning of the Forbush decrease to registration: the minimum cosmic ray density, the maximum hourlydecrease in density, the maximum cosmic ray anisotropy, the maximum solar wind velocity, the maximumstrength of the interplanetary magnetic field, and the minimum of the Dst index. The difference in the developmentof two types of Forbush decreases was compared when the interplanetary disturbance contains ordoes not contain a magnetic cloud near the Earth. The results showed that flare-associated events developfaster than filament-associated events, even at close values of the solar wind parameters. The difference in thedevelopment of two types of Forbush decreases is more noticeable in the case of the presence of a magneticcloud near the Earth’s orbit. The largest difference between the time parameters in the two types of events isobserved for the time of registration of the maximum intensity of the interplanetary magnetic field. The mainphase of the two types of Forbush decreases is the same at the solar cycle 23 maximum and longer for filament-associated events at the cycle 24 maximum and 23–24 minimum. Considering all time parameters, thedifference in the development of the two types of Forbush decreases is more noticeable at the maximum ofcycle 23 and at the minimum of cycle 23–24 than at the maximum of cycle 24

Development of Forbush Decreases Associated with Coronal Ejections from Active Regions and non-Active Regions

Development of Forbush Decreases Associated with Coronal Ejections from Active Regions and non-Active Regions

Study of AlGaN-based deep ultraviolet laser diodes using one-way step-shaped quantum barriers and symmetrical step-shaped electron and hole blocking layers

To improve the carrier injection efficiency and optimize the performance of the AlGaN-based deep ultraviolet laser diodes (DUV-LDs), one-way step-shaped quantum barriers (OWS-QBs), a symmetrical step-shaped electron blocking layer (SS-EBL), and a symmetrical step-shaped hole blocking layer (SS-HBL) are proposed. Crosslight software is used to simulate the DUV-LDs with a traditional structure, with OWS-QBs, and with OWS-QBs, a SS-EBL, and a SS-HBL. The simulation results and physical mechanism analysis indicate that the SS-EBL, SS-HBL, and OWS-QBs contribute to the increased carrier concentration in the quantum wells, the reduced carrier leakage in the nonactive regions, the increased stimulated emission rate, the reduced threshold current and threshold voltage, and the enhanced output power and electro-optical conversion efficiency of DUV-LDs.

An exploratory study of machine learning techniques applied to therapeutic energies particle tracking in microdosimetry using the novel hybrid detector for microdosimetry (HDM)

In this work we present an advanced random forest-based machine learning (ML) model, trained and tested on Geant4 simulations. The developed ML model is designed to improve the performance of the hybrid detector for microdosimetry (HDM), a novel hybrid detector recently introduced to augment the microdosimetric information with the track length of particles traversing the microdosimeter. The present work leads to the following improvements of HDM: (i) the detection efficiency is increased up to 100%, filling not detected particles due to scattering within the tracker or non-active regions, (ii) the track reconstruction algorithm precision. Thanks to the ML models, we were able to reconstruct the microdosimetric spectra of both protons and carbon ions at therapeutic energies, predicting the real track length for every particle detected by the microdosimeter. The ML model results have been extensively studied, focusing on non-accurate predictions of the real track lengths. Such analysis has been used to identify HDM limitations and to understand possible future improvements of both the detector and the ML models.

Forbush decreases associated with coronal mass ejections from active and non-active regions: statistical comparison

ABSTRACT In this paper, Forbush decreases (FDs) from 1997 to 2020 associated with coronal mass ejections from active and non-active regions are compared between themselves and to FDs caused by high-speed streams from coronal holes. The two types of sporadic FDs are also compared when corresponding solar wind (SW) disturbances contain, or do not contain, magnetic clouds (MCs) near Earth. Cosmic ray density and anisotropy variations, SW speed, interplanetary magnetic field (IMF) strength, and geomagnetic indices have been examined using statistical methods. The results reveal that these parameters are larger for FDs associated with active region (AR) ejections and have highly skewed distributions for both types of sporadic events. In the same ranges of SW parameters, FD magnitude is larger for flare-associated events; more efficient modulation occurs in FDs associated with AR ejections. Differences between FDs associated with AR and non-AR ejections are more pronounced when an MC is registered. For IMF strength and geomagnetic indices, differences between the distributions depend more upon MC presence or absence than on the type of solar source. Correlation of IMF strength and SW speed differs slightly between FDs caused by AR and non-AR ejections regardless of the presence or absence of an MC, akin to the partial correlation between FD magnitude and IMF strength. Difference between the speeds of disturbed and background SW is larger for FDs associated with AR ejections especially when an MC is registered; the interaction region of different-speed SW streams occurs more frequently in interplanetary disturbances induced by AR ejections.

Schiff’s base with center of symmetry as an effective corrosion inhibitor for mild steel in acid medium: Electrochemical & simulation studies

Green and efficient corrosion inhibitors have received widespread attention from various disciplines due to their wide application in petrochemical and other fields. However, because of its inability to fully understand the corrosion inhibition mechanism, the understanding of corrosion inhibition performance is limited. In this work, we synthesized a Schiff base (1, 2−1H-Benzoimidazol-2-yl)-(1, 2-diphenyl-ethylidene)-amine) (BDEA) with centre of symmetry structure by 2-aminobenzimidazole and benzyl. The central symmetric distribution of the heteroatoms has a higher coordination effect, thus, the adsorption performance has been outstanding. Characterization of synthesized compound was done using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analysis. The corrosion inhibition property of the synthesized Schiff base on X80 steel was determined using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM) analysis in 1 M HCl medium. Surface analyses of the alloy samples were performed using atomic force microscopy (AFM) analysis and contact angle measurement. BDEA can effectively protect X80 steel corrosion in 1 M HCl medium and the maximum efficiency obtained was 94.26 %. The surface analysis further proved that morphology of the metal surface was more protected in the presence of BDEA. In addition, the production of the reaction between BDEA and Fe3+ were studied by UV–vis spectrum analysis, and the mechanism was deliberated. The study of SECM showed that BDEA could adsorb both active and non-active regions on the metal surface at the same time. DFT studies suggested that the inhibition efficiency of its neutral as well as protonated form followed the order of η(protonated form) >η(neutral form) using DFT-based quantum chemical calculations. Besides, the degradation of BDEA showed that temperature had a significant effect on the degradation rate of BDEA using total organic carbon (TOC) analysis. Thermogravimetric analysis (TGA) indicated BDEA had admirable thermal stability. The influence of molecular behavior on corrosion inhibition performance is revealed from the perspective of structural characteristics. This work provides strong evidence for revealing the effect of structure on corrosion inhibition mechanism.

Data segmentation based on the local intrinsic dimension

One of the founding paradigms of machine learning is that a small number of variables is often sufficient to describe high-dimensional data. The minimum number of variables required is called the intrinsic dimension (ID) of the data. Contrary to common intuition, there are cases where the ID varies within the same data set. This fact has been highlighted in technical discussions, but seldom exploited to analyze large data sets and obtain insight into their structure. Here we develop a robust approach to discriminate regions with different local IDs and segment the points accordingly. Our approach is computationally efficient and can be proficiently used even on large data sets. We find that many real-world data sets contain regions with widely heterogeneous dimensions. These regions host points differing in core properties: folded versus unfolded configurations in a protein molecular dynamics trajectory, active versus non-active regions in brain imaging data, and firms with different financial risk in company balance sheets. A simple topological feature, the local ID, is thus sufficient to achieve an unsupervised segmentation of high-dimensional data, complementary to the one given by clustering algorithms.

Understanding the Moisture Variance in Precipitating Shallow Cumulus Convection

AbstractThe impact of precipitation in shallow cumulus convection on the moisture variance and third‐order moments of moisture is investigated with the help of large‐eddy simulations. Three idealized simulations based on the Rain in Cumulus over the Ocean field experiment are analyzed: one nonprecipitating, on a smaller domain, and two precipitating cases, on a larger domain with different initial profiles of moisture. Results show that precipitation and the associated cloud organization lead to increased generation of higher‐order moments (HOM) of moisture compared to the nonprecipitating case. To understand the physical mechanism and the role of individual processes in this increase, budgets of HOM of moisture are studied. Microphysics directly decreases the generation of HOM of moisture, but this effect is not dominant. The gradient production term is identified as the main source term in the HOM budgets. The influence of the gradient production term on moisture variance is further examined separately in cloud active and nonactive regions. The main contribution to the gradient production term comes from the smaller cloud active region because of the stronger moisture flux. Further analyses of the horizontal and vertical cross sections of moisture fluctuations show that the precipitation‐induced downdrafts and updrafts are the main mechanism for the generation of moisture variance. The variance increase is linked to shallow dry downdraft regions with horizontal divergence in the subcloud layer, moist updrafts with horizontal convergence in the bulk cloud layer, and finally wider areas of horizontal divergence in the cloud inversion layer.

Coronagraphic Observations of Si x λ14301 and Fe xiii λ10747 Linearly Polarized Spectra Using the SOLARC Telescope

Abstract The forbidden Si x emission line at 14301 Å has been identified as a potentially valuable polarized diagnostic for solar coronal magnetic fields; however, the only polarized Si x measurements achieved to date have been during eclipses and at comparatively low spatial and spectral resolution. Here we report spectropolarimetric observations of both the Si x 14301 Å and more well-established Fe xiii 10747 Å coronal lines acquired with the 0.45 m aperture SOLARC coronagraph atop Haleakalā. Using its fiber-based integral field spectropolarimeter, we derive observations sampled at radial intervals of 0.05 (i.e., ∼50″) with a spectral resolving power of ≈36,000. Results for both lines, which represent averages over different active and nonactive regions of the corona, indicate a relatively flat radial variation for the line widths and line centers and a factor of ≈2–3 decrease in polarized brightness between 1.05 and 1.45 . Averaging over all the measurements the mean and standard deviations of line properties for Si x 14301 Å and Fe xiii 10747 Å are, respectively, FWHM of 3.0 ± 0.4 Å and 1.6 ± 0.1 Å, line-integrated polarized brightness of 0.07 ± 0.03 and 0.3 ± 0.3 erg s−2 cm−2 sr−1, where the uncertainty quoted reflects a large sample variance, and line center wavelengths 14300.7 ± 0.2 Å and 10746.3 ± 0.1 Å. The polarized brightness for both lines may be underestimated by up to a factor of 5 due to limitations in the photometric calibration. When accounting for this uncertainty we find consistency between our observations and previous measurements of the two lines as well as theoretical calculations and affirm the potential of the Si x line as a polarized diagnostic of the solar corona.

Magnetic instability of filaments in different solar regions

AbstractMagnetic instability is a key consideration for filament eruptions and subsequent CMEs. In this contribution we are considering different magnetic conditions for active and non-active regions, such as coronal hole regions and quiet sun, and also active regions of a simple magnetic configuration. The aim is to assess magnetic instability through potential and non-potential field modelling and 3D evaluation of the magnetic decay index. Some eruptive examples from solar cycle 24 using HMI/SDO data are presented, complemented with observations of AIA/SDO.

Helium and carbon isotope signatures of gas exhalations in the westernmost part of the Pannonian Basin (SE Austria/NE Slovenia): Evidence for active lithospheric mantle degassing

We present new isotope (C, He, Ne, Ar, partly N) and compositional data from the free gas phase of fourteen degassing sites in the westernmost part of the Pannonian Basin near the Austria/Slovenia borderline. Based on these data, the origin of the gases and the degree of modification of the gas signatures due to interaction processes during migration are evaluated. The isotope signatures indicate an origin of helium and CO2 predominantly in the subcontinental mantle. Measured 3He/4He ratios from 4.95 to 6.32 Ra include the highest ones recorded in the whole Pannonian Basin system. Only at three locations in the periphery of the degassing center, a substantial admixture of crustal helium was found. The CO2 in the mofette gases and at the sites with the highest 3He/4He ratios (~6.3 Ra) is characterized by δ13C values of −3.5‰. In comparison with MORB (Mid-ocean Ridge Basalt), it is thus slightly enriched in 13C. The 3He/4He isotope ratios within the range typical for the subcontinental lithospheric mantle (SCLM) point to a fast, localized fluid transport from the magmatic reservoir to the surface.There are only few sites in European non-active volcanic regions where free gases with unmodified SCLM helium isotope signature escape at the surface. A comparison of the elemental and isotopic geochemical characteristics of gases with SCLM-helium signature from four different regions (Massif Central/France, Eifel/Germany, Eger Rift/Czech Republic and the westernmost part of the Pannonian Basin system) indicates that the European SCLM in general is characterized by a reservoir more enriched in 13C compared to MORB.

Computational and experimental analysis of TMS-induced electric field vectors critical to neuronal activation

Objective. Transcranial magnetic stimulation (TMS) represents a powerful technique to noninvasively modulate cortical neurophysiology in the brain. However, the relationship between the magnetic fields created by TMS coils and neuronal activation in the cortex is still not well-understood, making predictable cortical activation by TMS difficult to achieve. Our goal in this study was to investigate the relationship between induced electric fields and cortical activation measured by blood flow response. Particularly, we sought to discover the E-field characteristics that lead to cortical activation. Approach. Subject-specific finite element models (FEMs) of the head and brain were constructed for each of six subjects using magnetic resonance image scans. Positron emission tomography (PET) measured each subject’s cortical response to image-guided robotically-positioned TMS to the primary motor cortex. FEM models that employed the given coil position, orientation, and stimulus intensity in experimental applications of TMS were used to calculate the electric field (E-field) vectors within a region of interest for each subject. TMS-induced E-fields were analyzed to better understand what vector components led to regional cerebral blood flow (CBF) responses recorded by PET. Main results. This study found that decomposing the E-field into orthogonal vector components based on the cortical surface geometry (and hence, cortical neuron directions) led to significant differences between the regions of cortex that were active and nonactive. Specifically, active regions had significantly higher E-field components in the normal inward direction (i.e., parallel to pyramidal neurons in the dendrite-to-axon orientation) and in the tangential direction (i.e., parallel to interneurons) at high gradient. In contrast, nonactive regions had higher E-field vectors in the outward normal direction suggesting inhibitory responses. Significance. These results provide critical new understanding of the factors by which TMS induces cortical activation necessary for predictive and repeatable use of this noninvasive stimulation modality.

Lower limb conduit artery endothelial responses to acute upper limb exercise in spinal cord injured and able-bodied men.

Vascular improvements in the nonactive regions during exercise are likely primarily mediated by increased shear rate (SR). Individuals with spinal cord injury (SCI) experience sublesional vascular deconditioning and could potentially benefit from upper body exercise-induced increases in lower body SR. The present study utilized a single bout of incremental arm-crank exercise to generate exercise-induced SR changes in the superficial femoral artery in an effort to evaluate the acute postexercise impact on superficial femoral artery endothelial function via flow-mediated dilation (FMD), and determine regulatory factors in the nonactive legs of individuals with and without SCI. Eight individuals with SCI and eight age, sex, and waist-circumference-matched able-bodied (AB) controls participated. Nine minutes of incremental arm-crank exercise increased superficial femoral artery anterograde SR (P = 0.02 and P < 0.01), retrograde SR (P < 0.01 and P < 0.01), and oscillatory shear index (OSI) (P < 0.001 and P < 0.001) in both SCI and AB, respectively. However, these SR alterations resulted in acute postexercise increases in FMD in the AB group only (SCI 6.0 ± 1.2% to 6.3 ± 2.7%, P = 0.74; AB 7.5 ± 1.4% to 11.2 ± 1.4%, P = 0.03). While arm exercise has many cardiovascular benefits and results in changes in SR patterns in the nonactive legs, these changes are not sufficient to induce acute changes in FMD among individuals with SCI, and therefore are less likely to stimulate exercise training-associated improvements in nonactive limb endothelial function. Understanding the role of SR patterns on FMD brings us closer to designing effective strategies to combat impaired vascular function in both healthy and clinical populations.

EG-17 * SUV420-MEDIATED HETEROCHROMATIN CHANGES IN PEDIATRIC BRAIN CANCERS

Silencing mechanisms play a role in genomic stability by maintaining condensed, non-active regions of the genome. SUV420 enzymes contain a SET domain conferring methyltransferase activity toward histones. The Histone H4 lysine 20 trimethylation (H4K20me3) mark maintained by SUV420H2 is associated with heterochromatin formation and gene silencing, whereas the dimethylated mark (H4K20me2) is associated with DNA repair. In studies of epigenetic factors in large patient cohorts with ependymoma, it was found that SUV420H2 expression was lost or diminished in patients with reciprocal increases in prognostic markers such as hTERT. To better understand the normal function of Suv4-20H1/H2 enzyme in neural progenitors, and pathological changes in cancers, a variety of differentiation paradigms were used. The NT2D1 neurally restricted cell line, and BGO1V and H9 human embryonic stem cells (ESCs), and differentiated progeny, were used alongside tumors to better understand enzyme targets and functional outcomes (e.g.,lineage, differentiation, regional chromatin modifications). Lineage stages were verified with stage-specific markers by immunofluorescence and qPCR. Suv4-20 H1 and H2 were present in ESCs and neural progenitors and decreased thereafter. RNAi knockdown of SUV420 enzymes led to decreased H4K20 methylation in cancer cells. DNA methylation microarrays and ChIP-PCR suggest 1) that SUV420 is not regulated by DNA methylation in ependymomas; 2) that active chromatin marks such as H3K4 dimethylation are enriched near the transcriptional start site in the SUV420H2 gene, and 3) that hTERT is hyper-methylated at specific CpG islands and histones in a tumor sub-group-specific manner. This data supports the hypothesis that Suv4-20H2 is highly active in progenitor cells and functionally lost in some brain cancers. These studies begin to elucidate coincident mechanisms of gene silencing active in neural progenitors that may be altered in a subset of pediatric brain cancers.

The Three Mycobacterium tuberculosis Antigen 85 Isoforms Have Unique Substrates and Activities Determined by Non-active Site Regions

The three isoforms of antigen 85 (A, B, and C) are the most abundant secreted mycobacterial proteins and catalyze transesterification reactions that synthesize mycolated arabinogalactan, trehalose monomycolate (TMM), and trehalose dimycolate (TDM), important constituents of the outermost layer of the cellular envelope of Mycobacterium tuberculosis. These three enzymes are nearly identical at the active site and have therefore been postulated to exist to evade host immunity. Distal to the active site is a second putative carbohydrate-binding site of lower homology. Mutagenesis of the three isoforms at this second site affected both substrate selectivity and overall catalytic activity in vitro. Using synthetic and natural substrates, we show that these three enzymes exhibit unique selectivity; antigen 85A more efficiently mycolates TMM to form TDM, whereas C (and to a lesser extent B) has a higher rate of activity using free trehalose to form TMM. This difference in substrate selectivity extends to the hexasaccharide fragment of cell wall arabinan. Mutation of secondary site residues from the most active isoform (C) into those present in A or B partially interconverts this substrate selectivity. These experiments in combination with molecular dynamics simulations reveal that differences in the N-terminal helix α9, the adjacent Pro(216)-Phe(228) loop, and helix α5 are the likely cause of changes in activity and substrate selectivity. These differences explain the existence of three isoforms and will allow for future work in developing inhibitors.

An analytical expression for the determination of in situ stress state from borehole data accounting for breakout size

Knowledge of the in situ stress state in rock and soil deposits is very important in many problems in civil, mining and petroleum engineering and energy development, as well as in geology and geophysics. The prediction of the response of rock masses interacting with underground structures is highly influenced by the stress field. For example, as pointed out in [1], in civil and mining engineering, in situ stresses control the distribution and magnitude of the stresses around underground openings such as tunnels, mines, shaft or caverns. Stress concentrations in the excavation walls may be large enough to overstress the rock, mobilize the strength of the rock mass and induce failure. On the other hand, tensile stresses in excavation walls may open existing fractures or create new ones which could result in block stability problems. An exact prediction of in situ stress acting over a rock mass, together with its spatial variation, is a very complex topic; the current stress state is a mixed consequence of tectonic conditions and of mechanical effects due to local thermochemo-hydraulic conditions. Due to the complex nature of rocks and rock masses, the stress field is rarely homogeneous and also its time evolution can be significant within a geological formation. Stress state is a symmetric second-order tensor and so it is defined by six independent components, e.g. the three principal stresses and the three principal directions. Stresses in rocks cannot be measured directly and can only be inferred by disturbing the rock. Amadei and Stephansonn [2] presented a detailed summary of the available sources of information from which it is possible to obtain the in situ stress state, involving hydraulic methods (i.e. hydraulic and sleeve fracturing), relief methods, jacking methods, strain recovery methods, borehole failure methods as well as fault-slip data analysis and earthquake focal mechanisms. Zoback [4] proposed an overview of a possible strategy to characterize the stress field: the vertical stress can be determined from the equilibrium in the vertical direction, i.e. by integration of the density logs, while observations of the geometrical arrangement of drilling-induced tensile fractures are an effective way to check whether the vertical stress is a principal stress. The orientation of the other principal stresses can be determined from wellbore observations, recent geologic observations and earthquake focal mechanisms, as well as from stress recovery methods. The magnitude of the minimum principal stress can be estimated from the analysis of hydraulic fracturing and leak-off tests, while the pore pressure can be either measured directly or estimated with some caution from geophysical logs or seismic data. In this paper the vertical stress is assumed to be a principal stress, so that the remaining two directions are supposed to be horizontal. This assumption is reliable for non-active regions or regions already relaxed from the previous tectonical stress. As pointed out by Bell [3], the free surface of sedimentary basins is generally horizontal, so that the principal stress directions are, to a good approximation, horizontal and vertical. From a practical point of view, if the vertical direction is assumed to be a principal one, it is sufficient to know just a horizontal principal direction, since the remaining one is orthogonal to the plane on which the other two are lying. Throughout the paper, Sv will represent the principal vertical in situ stress, SH represents the maximum horizontal in situ stress and Sh represents the minimum horizontal in situ stress, whose magnitude can be evaluated through hydraulic fracturing or leak off tests (except for reverse faulting regimes). Assuming that Sv and Sh are known, the aim of the note is to present a methodology for the definition of some boundaries for

Electrical current-induced gradual failure of crystalline Ge2Sb2Te5 for phase-change memory

Electrical failure in crystalline Ge2Sb2Te5 was observed under a direct current bias, which induces a steady degradation of the electrical conductivity. This failure is induced by electromigration because alternating current bias stressing does not trigger this behavior. Nano-scaled voids were generated during current stressing, which explains the gradual increase in the quantitative resistance. Each nano-void previously comprised a molten phase that was induced by localized melting, which produced compositional variation during the solidification process. The phase-change memory can be damaged by electrical stressing in the non-active regions.

Hyperbaric Oxygen Induces Late Neuroplasticity in Post Stroke Patients - Randomized, Prospective Trial

BackgroundRecovery after stroke correlates with non-active (stunned) brain regions, which may persist for years. The current study aimed to evaluate whether increasing the level of dissolved oxygen by Hyperbaric Oxygen Therapy (HBOT) could activate neuroplasticity in patients with chronic neurologic deficiencies due to stroke.Methods and FindingsA prospective, randomized, controlled trial including 74 patients (15 were excluded). All participants suffered a stroke 6–36 months prior to inclusion and had at least one motor dysfunction. After inclusion, patients were randomly assigned to "treated" or "cross" groups. Brain activity was assessed by SPECT imaging; neurologic functions were evaluated by NIHSS, ADL, and life quality. Patients in the treated group were evaluated twice: at baseline and after 40 HBOT sessions. Patients in the cross group were evaluated three times: at baseline, after a 2-month control period of no treatment, and after subsequent 2-months of 40 HBOT sessions. HBOT protocol: Two months of 40 sessions (5 days/week), 90 minutes each, 100% oxygen at 2 ATA. We found that the neurological functions and life quality of all patients in both groups were significantly improved following the HBOT sessions while no improvement was found during the control period of the patients in the cross group. Results of SPECT imaging were well correlated with clinical improvement. Elevated brain activity was detected mostly in regions of live cells (as confirmed by CT) with low activity (based on SPECT) – regions of noticeable discrepancy between anatomy and physiology.ConclusionsThe results indicate that HBOT can lead to significant neurological improvements in post stroke patients even at chronic late stages. The observed clinical improvements imply that neuroplasticity can still be activated long after damage onset in regions where there is a brain SPECT/CT (anatomy/physiology) mismatch.Trial RegistrationClinicalTrials.gov NCT00715897

Low-barrier hydrogen bonds in proteins

Hydrogen bonding interactions are one of the most important chemical interactions among materials, especially biological materials, which help confer specificity, which is crucial for their efficient functioning. Recently, low-barrier hydrogen bonds (LBHBs) have been proposed to play a critical role in enzyme catalysis. In this review, tools to identify LBHBs are described, along with analyses of neutron crystal structures of small molecules to identify geometric parameters characteristic of LBHBs, which are assumed to be characterized by dynamic disorder along the hydrogen bond (H-bond) of the bonding hydrogen atom. The analysis of protein structures determined by neutron diffraction indicates that LBHBs are found to occur in both active site and non-active site regions of a protein. Moreover, very short H-bonds are observed in the vicinity of folding cores identified through nuclear magnetic resonance studies on two proteins, SUMO-1 and HIV-1 protease. This observation suggests that LBHBs may also be important in the context of folding of proteins.