Water/organic liquid interface properties with amine, carboxyl, thiol, and methyl terminal groups as seen from MD simulations

Molecular dynamics simulations were performed to study structural and dynamic properties of polar butanamine/water/butanamine, pentanoic acid/water/pentanoic acid, butanethiol/water/butanethiol, and nonpolar pentane/water/pentane systems. The mass density profiles along the interface normal to the organic liquid/water system, the difference in the local structure of H2 O molecules in bulk and in the vicinity of interface, as well as the diffusion behavior of water molecules at the interface with above-mentioned organic liquids have been investigated. Our MD simulation has shown that the diffusion of water molecules across the water/organic liquid interface is influenced by the hydrogen bondsn HB between water molecules and the terminal groups of organic liquids. It was found that the loss of the hydrogen bondsn HB in the nonpolar organic liquid leads to a decrease in the value of the normal component of the diffusion coefficientD z , while the tangential diffusion coefficients, bothD x andD y , increase.

Electrically driven kinklike distorting waves in microsized liquid crystals

Electrically driven kinklike distortion regimes in a microsized liquid crystal channel have been investigated both experimentally and analytically. Kinklike distortion waves were excited by the interaction between the electric field E and the gradient ∇n[over ̂] of the director field in a homogeneously aligned liquid crystal (HALC) channel. Having obtained the evolution of the normalized light intensity, which was recorded by the high-speed camera, the process of excitation and evolution of the traveling wave in the HALC channel was visualized for the first time. It was shown, based on a nonlinear extension of the classical Ericksen-Leslie theory, that in the case when the electric field E≫E_{th}, the flow of liquid crystal material completely stops and a new mechanism for converting the electric field arises in the form of the electrically driven distorting traveling kinklike wave, which can be excited in the LC channel, composed of 4-n-pentyl-4^{'}-cyanobiphenyl molecules.

Early Alterations in Structural and Functional Properties in the Neuromuscular Junctions of Mutant FUS Mice

Amyotrophic lateral sclerosis (ALS) is manifested as skeletal muscle denervation, loss of motor neurons and finally severe respiratory failure. Mutations of RNA-binding protein FUS are one of the common genetic reasons of ALS accompanied by a 'dying back' type of degeneration. Using fluorescent approaches and microelectrode recordings, the early structural and functional alterations in diaphragm neuromuscular junctions (NMJs) were studied in mutant FUS mice at the pre-onset stage. Lipid peroxidation and decreased staining with a lipid raft marker were found in the mutant mice. Despite the preservation of the end-plate structure, immunolabeling revealed an increase in levels of presynaptic proteins, SNAP-25 and synapsin 1. The latter can restrain Ca2+-dependent synaptic vesicle mobilization. Indeed, neurotransmitter release upon intense nerve stimulation and its recovery after tetanus and compensatory synaptic vesicle endocytosis were markedly depressed in FUS mice. There was a trend to attenuation of axonal [Ca2+]in increase upon nerve stimulation at 20 Hz. However, no changes in neurotransmitter release and the intraterminal Ca2+ transient in response to low frequency stimulation or in quantal content and the synchrony of neurotransmitter release at low levels of external Ca2+ were detected. At a later stage, shrinking and fragmentation of end plates together with a decrease in presynaptic protein expression and disturbance of the neurotransmitter release timing occurred. Overall, suppression of synaptic vesicle exo-endocytosis upon intense activity probably due to alterations in membrane properties, synapsin 1 levels and Ca2+ kinetics could be an early sign of nascent NMJ pathology, which leads to neuromuscular contact disorganization.

Skeletal photoinduced rearrangement of diarylethenes: ethene bridge effects

A skeletal photorearrangement involving UV-induced 6π-electrocyclization of diarylethenes with various ethene bridges has been studied. It has been found that deprotonation is the predominant step among the three possible alternative reaction pathways (radical abstraction, deprotonation, or sigmatropic shift) following 6π-electrocyclization, and incorporation of an electronegative carbonyl group into the geminal position to the phenyl residue results in a reduction in the reaction time and an increase in the yield of the desired product. The significant increase in the reaction time in less polar solvents (toluene, TCM) also indicates a large contribution of the deprotonation step to the skeletal photorearrangement of diarylethenes. Performing the reaction in toluene in the presence of tertiary amines leads to a reduction in the reaction time and an increase in the yield of the desired product. The best results were achieved when the reaction was carried out in toluene in the presence of DIPEA. The experimental results are in good agreement with the DFT calculations.

[The significance of the glymphatic pathway in the relationship between the sleep-wake cycle and neurodegenerative diseases]

Selective and progressive death of neurons is a characteristic feature of the process of neurodegeneration and leads to corresponding neuronal dysfunctions. Neurodegenerative diseases represent a heterogeneous group of clinically distinct disorders with similar molecular mechanisms of pathogenesis. They are based on the processes of abnormal aggregation of proteins, the formation of fibrillary insoluble structures and their deposition in the form of histopathological inclusions in the tissues of the nervous system. Disturbance of homeostatic functions that regulate neuronal ion and energy metabolism, biosynthesis and degradation of proteins and nucleotides, chronic hypoxia and the penetration of toxic and inflammatory substances into the brain from the bloodstream not only cause metabolic changes associated with age and disorders in the sleep-wake cycle, but also contribute to the development of neurodegenerative diseases. In animal studies, clearance pathways have been identified in which solutes and specific tracers are excreted perivascular into the meningeal lymphatics. The glymphatic pathway promotes the removal of metabolites, including Aβ amyloid and tau protein, from the parenchymal extracellular space of the brain. The glymphatic system is discussed to be more efficient during natural sleep, and fluid dynamics through this pathway exhibit daily fluctuations and are under circadian control. This review systematizes the key aspects and the data of recent research on the role of the glymphatic pathway and astroglial AQP-4 as its main determinant in maintaining homeostatic fluid circulation in the brain in normal and pathological conditions, in particular in relation to the regulatory role of the sleep-wake cycle and in development of neurodegeneration.

[The significance of glymphatic pathway in the relationship between the sleep-wake cycle and neurodegenerative diseases]

Selective and progressive death of neurons is a characteristic feature of the process of neurodegeneration and leads to corresponding neuronal dysfunctions. Neurodegenerative diseases represent a heterogeneous group of clinically distinct disorders with similar molecular mechanisms of pathogenesis. They are based on the processes of abnormal aggregation of proteins, the formation of fibrillary insoluble structures and their deposition in the form of histopathological inclusions in the tissues of the nervous system. Disturbance of homeostatic functions that regulate neuronal ion and energy metabolism, biosynthesis and degradation of proteins and nucleotides, chronic hypoxia and the penetration of toxic and inflammatory substances into the brain from the bloodstream not only cause metabolic changes associated with age and disorders in the sleep-wake cycle, but also contribute to the development of neurodegenerative diseases. In animal studies, clearance pathways have been identified in which solutes and specific tracers are excreted perivascular into the meningeal lymphatics. The glymphatic pathway promotes the removal of metabolites, including Aβ amyloid and tau protein, from the parenchymal extracellular space of the brain. The glymphatic system is discussed to be more efficient during natural sleep, and fluid dynamics through this pathway exhibit daily fluctuations and are under circadian control. This review systematizes the key aspects and scientific data of recent studies on the role of the glymphatic pathway and astroglial AQP-4 as its main determinant in maintaining homeostatic fluid circulation in the brain in normal and pathological conditions, in particular in relation to the regulatory role of the sleep-wake cycle and in development of neurodegeneration.

[Changes in sleep patterns and the doom-scrolling (doom-surfing) phenomenon as modifiable risk factors for anxiety due to continuous stress of the COVID-19 pandemic]

OBJECTIVE

To evaluate the modifiable daily behavior patterns associated with increased anxiety indicators in the general population in response to the COVID-19 pandemic.

MATERIAL AND METHODS

The study examined the characteristics of the Russian population (n=7777) of the international multicenter project COMET-G. In particular, variables were targeted to describe deviations in the behavior of adults during the period of application of measures of social isolation in connection with the pandemic, and revealing a relationship with the total score on the Spielberger State Anxiety Scale (STAI-S). Among these variables, experts selected those that could potentially be subject to change in the short term, that is, act as manageable or modifiable risk factors for the development of anxiety. The selected variables were analyzed in a statistical PLS-model to identify indicators that make the most significant contribution to the increase in the total anxiety score.

RESULTS

Our statistical model explained 48.4% of the variability in the STAI-S anxiety total scores related to changes in daily life habits. In particular, doom-scrolling/doom-surfing about the spread of the virus and the COVID-19 pandemic, changes in sleep patterns and usual daily life activities due to social isolation measures presented as factors significantly contributing to the increase of state anxiety.

CONCLUSION

Given the manageable or modifiable risk factors that we have identified, public awareness and therapeutic recommendations, pointing to the need to (I) control the amount of time spent in the internet and monitor their internet-based content consumption, (II) regulate sleep-wake patterns, (III) maintain daily habits and household activities, may reduce the likelihood of developing anxiety disorders in the context of the impact of a global chronic stress due to the COVID-19 pandemic and associated social isolation measures.

Therapy of Organophosphate Poisoning via Intranasal Administration of 2-PAM-Loaded Chitosomes

Chitosan-decorated liposomes were proposed for the first time for the intranasal delivery of acetylcholinesterase (AChE) reactivator pralidoxime chloride (2-PAM) to the brain as a therapy for organophosphorus compounds (OPs) poisoning. Firstly, the chitosome composition based on phospholipids, cholesterol, chitosans (Cs) of different molecular weights, and its arginine derivative was developed and optimized. The use of the polymer modification led to an increase in the encapsulation efficiency toward rhodamine B (RhB; ~85%) and 2-PAM (~60%) by 20% compared to conventional liposomes. The formation of monodispersed and stable nanosized particles with a hydrodynamic diameter of up to 130 nm was shown using dynamic light scattering. The addition of the polymers recharged the liposome surface (from -15 mV to +20 mV), which demonstrates the successful deposition of Cs on the vesicles. In vitro spectrophotometric analysis showed a slow release of substrates (RhB and 2-PAM) from the nanocontainers, while the concentration and Cs type did not significantly affect the chitosome permeability. Flow cytometry and fluorescence microscopy qualitatively and quantitatively demonstrated the penetration of the developed chitosomes into normal Chang liver and M-HeLa cervical cancer cells. At the final stage, the ability of the formulated 2-PAM to reactivate brain AChE was assessed in a model of paraoxon-induced poisoning in an in vivo test. Intranasal administration of 2-PAM-containing chitosomes allows it to reach the degree of enzyme reactivation up to 35 ± 4%.

Charge Fluctuations on a Flat Interface between Dielectric and Electrolyte or Dense Plasma

An interface between a dielectric and a medium containing charge carriers with moderate mobility is considered. In equilibrium, stochastic fluxes of positive and negative particles toward the surface have equal average current density j₀, and we suppose that the surface absorbs all falling charges. All over the surface, this results in the emergence of oppositely charged spots of various sizes D fluctuating and interacting with each other. Fourier expansion reduces this collection of interacting spots to the ensemble of independently fluctuating charge density waves. An exact solution of the Poisson equation for a single wave on a flat surface was obtained and provided strict proof that a fluctuating electric field is quite strong just above each charge spot but diminishes exponentially with the distance from the plane. The lifetime τ of a charge spot is inversely proportional to the density j₀ of the stochastic current while proportional to j0τ fluctuation's amplitudes independent of j₀. The fluctuation's parameter dependence on the charge spot's size D can vary according to the conducting medium properties.

[Study of the effectiveness of neuroprotective therapy in restoring motor function in patients during the acute period of ischemic stroke]

OBJECTIVE

The purpose of the work was to study the effect of neuroprotective therapy with Cellex on the features of recovery of movement disorders in patients in the acute period of ischemic stroke.

MATERIAL AND METHODS

A single-center randomized study was conducted to assess the efficacy and safety of the use of neuroprotective therapy with Cellex in patients in the acute period of ischemic stroke. The study included 60 patients with a stroke duration of no more than 3 days in the middle cerebral artery area and vertebrobasillar area with moderate and severe central hemiparesis. Patients of the study group received 1 ml of Cellex. subcutaneously 1 time per day for 10 days. All patients received drug therapy and rehabilitation measures within the framework of the standard of care for patients with ischemic stroke.

RESULTS

Against the background of the therapy, by the end of the study on days 14-21, the study and control groups showed a significant improvement according to clinical scales: NIHSS, mRS, RMI. The patients of the study group showed a more pronounced recovery of motor function, relative to the comparison group, according to motor scales: «A-D» FMA (54 [53; 62] and 42 [34; 51], p=0.03), «E-F» FMA (29 [28; 33] and 25 [18; 27], p=0.03), ARAT (47 [48; 57], 32 [24; 48], p=0.046). Among the patients of the study group, by the end of the study, the severity of mild stroke was 67%, relative to the comparison group 11% (χ²_1df=6.48; p=0.01). The use of neuroprotective therapy in the form of Cellex had a positive effect on both the prognostic score and the long-term assessment according to the SSS scale, due to the regression of motor disorders of the upper and lower extremities.

CONCLUSION

The study has demonstrated the effectiveness of the use of neuroprotective therapy in the treatment of movement disorders in patients in the acute period of ischemic stroke. Therapy with Cellex helped to reduce the severity of stroke, and had a positive effect on the prognosis of the disease.

[Motor rehabilitation of patients in the acute period of stroke using virtual reality technology]

OBJECTIVE

To study an effect of adjuvant rehabilitation using implicit virtual reality on the dynamics of the motor function of the lower extremities in patients in the acute period of ischemic stroke.

MATERIALS AND METHODS

The study was carried out to assess the effectiveness and safety of rehabilitation using virtual reality in 60 patients with lower central paresis in the acute period of ischemic stroke, lasting from 3 to 5 days. Patients of the study group additionally received rehabilitation using the hardware-software complex ReviVR, which allows to stimulate the patient's plantar surface by means of pneumo cuffs synchronously with the step of his animated body. Animation of movement was demonstrated to the patient using virtual reality glasses. The duration of the classes was 10 days, 20-25 minutes each. The total duration of rehabilitation measures in the study and comparison groups was 3-4 hours.

RESULTS

A significant regression on NIHSS (3 [-4; -1] and -1 [-2; 0], p<0.001) and a progress on RMI (3 [1; 3] and 2 [0; 2], p<0.001, respectively), between the study group and the control group were found. Changes on FMA-LE section (E-F) occurred on day 10, between the study and comparison groups (9 [5; 16] and 4 [0; 7], respectively, p=0.04). The improvement in FMA-LE out of synergy, in the standing position, indicated an increased readiness of the patient to form an independent walk.

CONCLUSION

The study has shown that the use of virtual reality rehabilitation increases the effectiveness of motor rehabilitation in patients with lower central paresis in the acute period of stroke.

[Sleep disorders in synucleinopathy]

The article highlights the current state of the problem of sleep disorders in various neurodegenerative diseases. The clinical picture and diagnosis of these disorders are described in detail. Separately, the emphasis is made on the mechanisms underlying development of these disorders and their features in various forms of synucleinopathies. The mediator and physiological changes that underlie sleep disorders in various nosological units of synucleinopathies are discussed in detail. The current attitude to certain sleep disorders as predictors of neurodegenerative diseases is evaluated. The role of the glymphatic system in the development of these disorders is considered. Also, modern therapeutic strategies for sleep disorders in neurodegenerative diseases are discussed.

Electrically driven nematic flow in microfluidic capillary with radial temperature gradient

An electrically driven fluid pumping principle and a mechanism of kinklike distortion of the director field n[over ̂] in the microsized nematic volume has been described. It is shown that the interactions, on the one hand, between the electric field E and the gradient of the director's field ∇n[over ̂], and, on the other hand, between the ∇n[over ̂] and the temperature gradient ∇T arising in a homogeneously aligned liquid crystal microfluidic channel, confined between two infinitely long horizontal coaxial cylinders, may excite the kinklike distortion wave spreading along normal to both cylindrical boundaries. Calculations show that the resemblance to the kinklike distortion wave depends on the value of radially applied electric field E and the curvature of these boundaries. Calculations also show that there exists a range of parameter values (voltage and curvature of the inner cylinder) producing a nonstandard pumping regime with maximum flow near the hot cylinder in the horizontal direction.

Electrically driven nematic flow in microfluidic devices containing a temperature gradient

Fluid pumping principle has been developed utilizing the interaction, on the one hand, between the electric field E and the gradient ∇n[over ̂] of the director's field, and, on the other hand, between the ∇n[over ̂] and the temperature ∇T gradient arising in a homogeneously aligned liquid crystal (HALC) microfluidic channel. Calculations, based upon the nonlinear extension of the classical Ericksen-Leslie theory, with accounting the entropy balance equation, show that due to the coupling among the ∇T, ∇n,[over ̂] and E in the HALC microfluidic channel the horizontal flow v=v_{x}i[over ̂]=ui[over ̂] may be excited. The direction and magnitude of v is influenced both by the heat flux q across the microfluidic channel and the strength of the electric field E. The results of calculations showed that the dependence of the maximum value of the equilibrium velocity distribution |u_{max}(E/E_{th})| across the LC channel versus electric field E/E_{th} is characterized by maximum value at E/E_{th}=2.0. In the case when the electric field E≫E_{th}, the horizontal flow of the LC material completely stops and a novel mechanism of converting of the electric field in the form of the kinklike wave reorientation of the director field n[over ̂] can be excited in the LC channel.

Nonmechanical principle for producing a flow in a homogeneously aligned microfluidic nematic channel

Nonmechanical fluid pumping principle has been developed utilizing the interactions of both the director [Formula: see text] and velocity v fields and temperature T redistribution across a two-dimensional homogeneously-aligned nematic (HAN) microfluidic channel under the influence both of a heat flux [Formula: see text] and the surface electric field E₀, originating from the surface charge density [Formula: see text]. The heat flux [Formula: see text] is caused by the laser beam pulse focused on the channel's boundary, whereas the normally directed electric field is due to electric double layers, that is naturally created within the liquid crystal near a charged surface. Calculations, based upon the nonlinear extension of the classical Ericksen-Leslie theory, with accounting the entropy balance equation, show that due to the coupling between the [Formula: see text] and [Formula: see text], in the HAN microfluidic channel the vortical flow [Formula: see text] may be excited. The direction and magnitude of [Formula: see text] is influenced by [Formula: see text] and E₀, as well as by the thickness of the HAN microfluidic channel.

Photochemical rearrangement of diarylethenes: synthesis of functionalized phenanthrenes

A novel protocol for the synthesis of functionalized phenanthrenes through photocyclization of diarylethenes (DAE) under UV irradiation is proposed. The reaction proceeds through 6π-electrocyclization with the formation of a cyclic (closed) intermediate that undergoes a rearrangement affording unsymmetrical phenanthrenes in good yields. However, in contrast to benzene derivatives, the photocyclization of naphthalene diarylethenes proceeds more slowly, which is confirmed by DFT calculations. The transformation was performed on a 1 mmol scale. The scalability showed that the diarylethenes bearing oxazole, thiazole, pyrazole and imidazole as aryl moieties are more prone to photorearrangement and can be used in preparative organic synthesis.

Kinklike pressure wave in the microsized twisted nematic volume

We have described a novel mechanism of the kinklike pressure P(z-vt) response of the microsized twisted nematic volume under the effect of externally applied electric field E directed parallel to the restricted surfaces and induced by a strong local disturbance of the director field n[over ̂]. It is found that the torques acting on the director n[over ̂] may excite the pressure traveling wave spreading along the normal to both boundaries, whose resemblance to a kink-like wave increases with increasing the value of the applied electric field greater than some critical value E_{cr}.

Structural and optical properties of free-standing smectic films

We have carried out a complex numerical study of the structural, thermodynamic and optical properties of the partially fluorinated 5-n -alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) free-standing smectic film in air under the action of the external electric field [Formula: see text]. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show a stepwise reduction of the value of the Helmholtz free energy and the reflectivity of the partially fluorinated smectic film in air, as the temperature is raised above the bulk smectic-A-isotropic transition value. It has been shown, by solving the self-consistent nonlinear equations for the orientational and translational order parameters, that the electric field [Formula: see text] may not only affect the layer-thinning transition sequences, but also change the first multilayer jump in the film thickness, whereas practically does not affect the reflectivity R(N) of the partially fluorinated N -layer smectic film in air. In the range of film thicknesses investigated, the reduction of the R(N) is, at least, qualitatively in agreement with the experimentally observed decrease of the optical reflectivity with the decrease of N.

Nature of thermally excited vortical flow in a microsized nematic volume

The theoretical description of the reorientational dynamics in the case of a hybrid-oriented two-dimensional (2D) liquid crystal (LC) cell, under the influence of a temperature gradient ∇T, caused by a heat flux q directed at an angle α across the lower bounding surface with the orientational defect, has been presented. Our calculations, based on the appropriate nonlinear extension of the classical Ericksen-Leslie theory, show that due to interaction between ∇T and the gradient of the director field ∇n[over ̂] in the LC sample a thermally excited vortical fluid flow is maintained in the bulk of the nematic volume. In order to elucidate the role of both the orientational defect and the heat flux q in formation of the vortical flow in the microsized LC volume, we have analyzed the response of the LC material confined in the microsized 2D volume on the effect of the laser beam focused on the bounding surface.

Pharmacodynamics of the Glutamate Receptor Antagonists in the Rat Barrel Cortex

Epipial application is one of the approaches for drug delivery into the cortex. However, passive diffusion of epipially applied drugs through the cortical depth may be slow, and different drug concentrations may be achieved at different rates across the cortical depth. Here, we explored the pharmacodynamics of the inhibitory effects of epipially applied ionotropic glutamate receptor antagonists CNQX and dAPV on sensory-evoked and spontaneous activity across layers of the cortical barrel column in urethane-anesthetized rats. The inhibitory effects of CNQX and dAPV were observed at concentrations that were an order higher than in slices in vitro, and they slowly developed from the cortical surface to depth after epipial application. The level of the inhibitory effects also followed the surface-to-depth gradient, with full inhibition of sensory evoked potentials (SEPs) in the supragranular layers and L4 and only partial inhibition in L5 and L6. During epipial CNQX and dAPV application, spontaneous activity and the late component of multiple unit activity (MUA) during sensory-evoked responses were suppressed faster than the short-latency MUA component. Despite complete suppression of SEPs in L4, sensory-evoked short-latency multiunit responses in L4 persisted, and they were suppressed by further addition of lidocaine suggesting that spikes in thalamocortical axons contribute ∼20% to early multiunit responses. Epipial CNQX and dAPV also completely suppressed sensory-evoked very fast (∼500 Hz) oscillations and spontaneous slow wave activity in L2/3 and L4. However, delta oscillations persisted in L5/6. Thus, CNQX and dAPV exert inhibitory actions on cortical activity during epipial application at much higher concentrations than in vitro, and the pharmacodynamics of their inhibitory effects is characterized by the surface-to-depth gradients in the rate of development and the level of inhibition of sensory-evoked and spontaneous cortical activity.

Laser-excited motion of liquid crystals confined in a microsized volume with a free surface

The thermally excited vortical flow in a microsized liquid crystal (LC) volume with a free LC-air interface has been investigated theoretically based on the nonlinear extension of the Ericksen-Leslie theory, with accounting the entropy balance equation. Analysis of the numerical results show that due to interaction between the gradients of the director field ∇n[over ̂] and temperature field ∇T, caused by the focused heating, the thermally excited vortical fluid flow is maintained in the vicinity of the heat source. Calculations show that the magnitude and direction of the velocity field v, as well as the height of the LC-air interface are influenced by the depth of the heat penetration in the LC volume. It has been shown that there is the point in the vicinity of the LC-air interface where the thermally excited vortical flow changes the direction from anticlockwise to clockwise.

[Effectiveness of reslip (doxylamine) in short-term insomnia: multicenter comparative randomized study]

AIM

Evaluate the efficiency of reslip (doxylamine) in short-term insomnia in comparison with donormyl in multicenter comparative randomized study.

MATERIAL AND METHODS

The study was conducted in 6 medical centers and included 60 patients aged from 30 to 59 years with short-term insomnia. Patients were divided into two groups: in first one patients took reslip and in the second one donormyl in same dosage and regimen.

RESULTS

The complete clinical remission of insomnia was achieved in majority of patients in both groups. Indicators of insomnia severity, sleep quality and daytime sleepiness in both groups improved with a high significance. Side effects were mild and in most cases did not result in treatment cessation. No significant differences between the groups in terms of clinical efficacy were found.

CONCLUSION

Short-term doxylamine intake causes significant positive clinical effect in short-term insomnia with satisfactory acceptability by patients. Russian doxylamine Reslip correlates well with donormil regarding the clinical efficacy and acceptability and can be used in clinical practice for the short-term insomnia treatment.

[Melatonin - known problems and perspectives of clinical usage]

The article discusses well-known and ongoing studies of mechanisms of action of melatonin. The main clinical effects of melatonin are discussed. The emphasis on the chronobiological effect of melatonin, its adaptogenic and anti-carcinogenic properties has been done in the article. The most frequent manifestations of epiphyseal melatonin deficiency are various functional disorders in the form of insomnia, anxiety or depressive disorders. Recommendations on the effective use of melatonin in its deficiency due to pathology are given.

Local structural ordering in surface-confined liquid crystals

The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. Extending the McMillan mean field theory to include finite systems, it has been shown that confining surfaces can induce complex orientational and translational ordering of molecules. Typically, local smectic A, nematic, and isotropic phases have been shown to coexist in certain temperature ranges, provided that confining cells are sufficiently thick, albeit finite. Due to the nonlocality of surface interactions, the spatial arrangement of these local phases can display, in general, an unexpected complexity along the surface normal direction. In particular, molecules located in the vicinity of surfaces can still be organized in smectic layers, even though nematic and/or isotropic order can simultaneously appear in the interior of cells. The resulting surface freezing of smectic layers has been confirmed to occur even for rather weak surface interactions. The surface interactions cannot, however, prevent smectic layers from melting relatively close to system boundaries, even when molecules are still arranged in layers within the central region of the system. The internal interfaces, separating individual liquid-crystal phases, are demonstrated here to form fronts of local finite-size transitions that move across cells under temperature changes. Although the complex molecular ordering in surface confined liquid-crystal systems can essentially be controlled by temperature variations, specific thermal properties of these systems, especially the nature of the local transitions, are argued to be strongly conditioned to the degree of molecular packing.

Translational diffusion across a free-standing smectic film above the bulk smectic-A-isotropic transition temperature

Calculations of translational self-diffusion coefficient in free-standing smectic films during a series of layer-thinning transitions as the temperature is raised above the bulk smectic-A-isotropic transition have been carried out. A molecular model based upon the random walk theory is applied for calculating the translational diffusion coefficient (TDC) D_{∥} across the smectic film both in the bulk of the film, as well as in the vicinity of the bounding surfaces. Calculations of D_{∥} require the set of the orientational and translational order parameters (OPs) which have been obtained by using the extended McMillan approach with anisotropic forces. The effect of E on the orientational and translational OPs, as well as on the TDC of smectic films has been investigated. A reasonable agreement between the theoretically predicted and the experimentally obtained data on the TDC in the bulk of the partially fluorinated H10F5MOPP film has been obtained. We also found, in agreement with the experimentally observed behavior of D_{∥}(N)(N=25,13,11,10), that the translational diffusion coefficient in the bulk of the film gradually increases as the film thickness N is decreased.

INTEGRAL ALGORITHM OF P300 RECOGNITION IN EEG FOR BCI APPLICATION

Aim - developing the integral algorithm of recognition of the evoked potential (ERP-response) to a target visual stimulus and testing of the proposed algorithm on the wireless 5-channel electroencephalograph Emotiv Insight with “dry” electrodes. Materials and methods. The objects of the study were the EEG records of five volunteers. Were used 5-channel wireless EEG headset Emotiv Insight, self-developed software «eSpeller», software environment MathWork® MATLAB R2015a. Results. It was found that the proposed integral algorithm of recognition of electrical activity of the cerebral cortex to a target visual stimulus shows the accuracy of the detection from 71.5% to 90.6% with the average value 80.1+7.2%, using EEG headset Emotiv Insight. Conclusion. The algorithm shows a high level of reliability of recognition of evoked potential to a target visual stimulus, does not require large computing power, sophisticated classification methods and machine learning. The testing of the algorithm suggests the possibility of using the electroencephalograph Emotiv Insight with "dry" electrodes in the development of BCI.

The effect of surfaces on molecular ordering in thin liquid-crystal systems

A theoretical method for analyzing the interplay between pair long-range intermolecular forces and nonlocal, relatively short-range, surface interactions in liquid crystals, confined between plates of thin planar cells, is developed. It is shown that this method, as involving the concept of local orientational and translational order parameters, enables detailed investigations of the emergence of smectic A, nematic, and isotopic phases, as well as yields an insight into phase transitions between them, in cases of systems strongly affected by surfaces. The evidence of various surface effects, including the coexistence of different phases and the inward propagation of surface melting under the increase of temperature, is also given. The underlying numerical procedure, based on the algorithm of self-consistent calculations of local order parameters, is found to be very effective, allowing one to consider model systems of rather large thicknesses, corresponding to thicknesses of real sample cells.

Orientational relaxation in free-standing smectic C film driven by rotating circular frame

The pecularities in the cˆ-director reorientation in free-standing smectic C film without of defects and stretched between two circular frames, the rest outer and rotating inner, have been investigated theoretically based on the hydrodynamic theory including the cˆ-director motion and with accounting for backflow. Since the orientation of the cˆ-director is fixed at the rims of the smectic film, the shear flow induced by rotating frame winds up of the cˆ-director field. It is found that the higher shearing flow produces the greater twisting rotation of the cˆ-director around the normal to the smectic film directed in the opposite sense with respect to the direction of the angular velocity. Calculations also show that the relaxation dynamics of the cˆ-director field depends crucially on the curvature of the inner rotating frame.

Squeezing-out dynamics in free-standing smectic films

We have carried out a theoretical study of the dynamics of the removal of one smectic layer from the N-layer free-standing smectic film during the layer-thinning process. Squeezing-out is initiated by a thermally activated nucleation process in which a density fluctuation forms a small hole. The dynamics of the bounding area during the layer-thinning transition N → N - 1, when the nucleation occurs in the center of the circular smectic film and the squeezed-out area increases up to the edge of the circular smectic area, is studied by the use of the conservation laws for mass and linear momentum. The disjoining pressure is the main factor that is responsible for the driving out of one smectic layer from the N-layer smectic film.

Transition Helmholtz free energy, entropy, and heat capacity of free-standing smectic films in water: a mean-field treatment

Using the extended McMillan's mean field approach with anisotropic forces a study of both the structural and thermodynamic properties of free-standing smectic film (FSSF) in water on heating to the isotropic temperature is carried out numerically. By solving the self-consistent nonlinear equations for the order parameters, we obtained that the smectic-A-isotropic (AI) transition occurs through the series of layer-thinning transitions causing the films to thin in the stepwise manner as the temperature is increased above the bulk smectic-A-isotropic temperature TAI(bulk). With enhanced pair interactions in the bounding layers, the smectic-isotropic transition corresponds to smectic melting of the central layers. The effects of surface "enhanced" pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy and entropy, as well as the temperature dependence of the heat capacity of FSSFs, have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained - by means of optical microscopy and ellipsometry techniques - data of the temperature when the thin decylcyanobiphenyl smectic film immersing in water ruptures has been obtained.

[Computer search for molecular mechanisms of ulcerogenic action of nonsteroidal antiinflammatory drugs]

"Peptic ulcers" is the most frequent side effect of non-steroidal anti-inflammatory drugs (NSAIDs). Experimental data indicate that pathogenesis of peptic ulcers cannot be explained only by the inhibition of cyclooxygenases. The knowledge about other molecular mechanisms of action of drugs related with development of peptic ulcers could be useful for design of new safe NSAIDs. However, considerable time and material resources are needed for corresponding experimental research. For simplification of experimental search, we have developed an approach for in silico identification of probable molecular mechanisms of action of drugs related with its side effects. We have created the set of NSAIDs containing 85 substances with data about structures and side effects. The computer program PASS (Prediction of Activity Spectra for Substances) predicting more than 3000 molecular mechanisms of action based on structural formula of substances was used to estimate unknown molecular mechanisms of action for these set of NSAIDs. Statistically significant relationships between predicted molecular mechanisms of action and development of peptic ulcers have been established. We have discovered twenty-six molecular mechanisms of action (two known previously and twenty-four new) which probably related with development of peptic ulcers. By analyzing of Gene Ontology data, signal and metabolic pathways, publications in Medline, we formulated hypotheses about the role of ten molecular mechanisms of action in pathogenesis of peptic ulcer.

Surface tension and disjoining pressure of free-standing smectic films above the bulk smectic-A-isotropic transition temperature

We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films for the case of enhanced pair interaction in the bounding layers. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show that the layer-thinning transitions are characterized by abrupt drops to lower values, both for a disjoining pressure and a fluctuation-induced long-range interaction between the smectic film surfaces, and then continues to increase with a larger positive slope. Reasonable agreement between the theoretically predicted and the experimentally obtained data on the surface tension of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) film has been obtained.

Gamma oscillations in the somatosensory cortex of newborn rats

Here we addressed a question of whether gamma oscillations previously described in the whisker-related barrel cortex are a universal pattern of activity in the somatosensory cortex of newborn rats. Intracortical recording of local field potentials and action potentials in neurons using multisite silicon electrodes in 2-7-day-old rats showed that mechanical stimulation of single fingers or specific areas on the plantar or back side of the foot evoked early gamma oscillations followed by spindle-burst oscillations in the corresponding regions of the somatosensory cortex. Early gamma oscillations had maximum amplitude in layer IV of the somatosensory cortex and effectively synchronized action potentials in layer IV neurons. It was concluded that early gamma oscillations evoked by activation of the topographic sensory input are a universal activity pattern of the entire somatosensory cortex of newborn rats.

[Posture disorders in patients with multiple sclerosis]

Impairment of stability in the vertical posture is one of the most common or, sometimes, a key symptom in patients with multiple sclerosis (MS). Reduction of postural control is often correlated with the severity of neurological deficit and is thought to be a leading factor that impacts on social and working activities of the patient with MS. We studied disturbances of postural control depending on the lesion of a functional system and evaluated the involvement of a corresponding system in the functions of postural control in 61 patients with confirmed MS. Patients were stratified into five groups according to lesion location: visual, motor, sensory, cerebellar or spine stem systems. The maximal impairment of static postural control corresponded to the maximal lesion of the sensory system. Compensatory mechanisms of the activation of central and neuromuscular.

Dynamics of the modulated distortions in confined nematic liquid crystals

The peculiarities in the dynamics of the director reorientation in confined nematic liquid crystals (LCs) under the influence of a strong electric field E have been investigated theoretically based on the hydrodynamic theory including the director motion with appropriate boundary and initial conditions. Analysis of the numerical results for the turn-on process provides an evidence for the appearance of the spatially periodic patterns in confined LC film, only in response to the suddenly applied strong E. It has been shown that there is a threshold value of the amplitude of the thermal fluctuations of the director over the LC sample which provides the nonuniform rotation mode rather than the uniform one, whereas the lower values of the amplitude dominate the uniform mode. During the turn-off process, the reorientation of the director to the direction preferred by the surfaces is characterized by the complex destruction of the initially periodic structure to a monodomain state.

Field-induced director dynamics in confined nematic liquid crystals imposed by a strong orthogonal electric field

The field-induced director dynamics for a low molar mass nematic liquid crystal (LC) has been investigated theoretically based on the hydrodynamic theory including the director motion with appropriate boundary and initial conditions. Analysis of the numerical results for the turn-on process provides evidence for the appearance of the spatially periodic patterns in 4-n-pentyl-4'-cyanobiphenyl LC film, only in response to the suddenly applied strong electric field orthogonal to the magnetic field. It has been shown that at the values of the voltage of 200 V across the 194.7 μm LC film and the magnetic field of 7.05 T directed at the angle α=1.57(~89.99°) between two fields, there is a threshold value of the amplitude of the thermal fluctuations of the director over the LC sample which provides the nonuniform rotation mode rather than the uniform one, whereas the lower values both of the amplitude and the angle α [<1.565(~88.81°)] dominate the uniform mode. During the turn-off process, the reorientation of the director to its equilibrium orientation is characterized by the complex destruction of the initially periodic structure to a monodomain state.

[Assessment of the risk of the transition of a monofocal clinically isolated syndrome to clinically definite multiple sclerosis]

We followed up 102 patients with a monofocal clinically isolated syndrome (CIS) during 8 years. Factors determining its transition to definite multiple sclerosis were singled out according to the data of anamnesis and MRI scans. Age of patients at the onset of CIS and the volume of demyelination measured by the first MRI were the most significant predictors of the transition of CIS to definite multiple sclerosis. A mathematical model based on logistic regression analysis for the estimation of the risk of this transition is suggested.

Influence of an external field on the surface tension of free-standing smectic films

We have carried out a theoretical study of the effect of the electric field E on the thermodynamical properties and surface tension γ of free-standing smectic films. Calculations, based upon the extended McMillan approach with anisotropic forces, show a stepwise reduction and increase of the values of the Helmholtz free energy f and γ, respectively, per partially fluorinated 5-n-alkyl-2-[4-n-(perfluoroalkyl-metheleneoxy)phenyl] (H10F5MOPP) molecule, as the temperature is raised above that for the bulk smectic-A-isotropic transition. Calculations show that E may not only affect the layer-thinning transition sequence, but also change the first multilayer jump in the thickness and increase the value of γ per H10F5MOPP molecule. Reasonable agreement between the theoretically predicted and the experimentally obtained data on γ of the partially fluorinated H10F5MOPP film has been obtained.

[Experimental and modelling investigation of the mechanism of synaptic vesicles recycling]

Under the condition of microelectrode recording and fluorescence microscopy with dye FM 1-43 the research of exo- endocytosis of synaptic vesicle in motor nerve terminals (NT) of frog cutaneous pectoris and white mice diaphragm muscles during high frequency stimulation (20 imp/s) was carried out. A mathematical modeling allowed us to conclude that the obtained experimental data can be explained in the following framework. Three pools of synaptic vesicles are involved in neurotransmitter release in the frog motor NT. Recovery of these pools is provided by endocytosis of two types: fast endocytosis with limited capacity and slow endocytosis. Fast-reconstructing vesicles refills the mobilization pool and slow endocytosis recovers the reserve pool. Our modelling investigation has revealed in frog NT independent recruiting of reserve and mobilization pools to the neurotransmitter secretion, i.e. this pools work concurrently. Experimental data, obtained on mice preparations, are well described with the framework of two-pools model including single type of endocytosis (fast endocytosis).

Field-induced periodic distortions in a nematic liquid crystal: deuterium NMR study and theoretical analysis

The peculiarities in the dynamic of the director reorientation in a liquid crystal (LC) film under the influence of the electric E field directed at an angle α to the magnetic B field have been investigated both experimentally and theoretically. Time-resolved deuterium NMR spectroscopy is employed to investigate the field-induced director dynamics. Analysis of the experimental results, based on the predictions of hydrodynamic theory including both the director motion and fluid flow, provides an evidence for the appearance of the spatially periodic patterns in 4-n-pentyl-4'-cyanobiphenyl LC film, at the angles α>60∘, in response to the suddenly applied E. These periodic distortions produce a lower effective rotational viscosity. This gives a faster response of the director rotation than for a uniform mode, as observed in our NMR experiment.

[Overcoming resistance of tuberculosis infectious agent by isoniazid-silver nanocomposite]

The antituberculous activity of a nanocomposite based on nanoparticulate silver and isoniazid has been studied on the model of drug-resistant tuberculosis in a group of 65 white mice. The possibility of overcoming the resistance of the tuberculosis activator by the proposed nanocomposite of isoniazid and nanoparticulate silver is demonstrated in terms of the survival index, biometric data, bacteriological and pathomorphological parameters. Dose-dependent parameters of the presence of nanoparticulate silver in the composite structure are established. The results of preclinical research scientifically prove good prospects for using nanoparticulate silver in the treatment of drug-resistant tuberculosis.

[Expression of the catalytic antibodies in eukaryotic systems]

Expression of recombinant antibodies in mammalian cells is one of key problems in immunobiotechnology. Alternatively, expression of a broad panel of antibodies and of their fragments may be effectively done in yeast cells. We obtained expression strains of the methylotrophic beast Pichia pastoris producing single chain human catalytic antibody A17 (A.17scFv), Fab-fragment (A.17Fab) and full-size light chain (A.17Lch). These antibodies were characterized in terms of functional activity. The capacity to specifically bind and transform organophosphorus compounds has been demonstrated for A.17scFv and A.17Fab. The loss of activity of the antibody light chain when expressed alone indicates that the active site is formed by both heavy and light chains of the antibody. We determined the reversible constant Kd and the first order constant (k2) of the reaction of the covalent modification of A.17scFv and A.17Fab by irreversible inhibitor of the serine proteases p-nitrophenyl 8-methyl-8-azobicyclo[3.2.1]phosphonate (Phosphonate X). Calculated values indicate that activity of the antibodies expressed in yeast is similar to the full-size antibody A17 and single chain antibody A.17 expressed in CHO and E. coli cells respectively.

Transition entropy, Helmholtz free energy, and heat capacity of free-standing smectic films above the bulk smectic-A-isotropic transition temperature: a mean-field treatment

We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films (FSSFs) for two cases of enhanced pair interactions in the bounding layers. Calculations, based upon the extended McMillan's approach with anisotropic forces, shows a stepwise reduction of the value of the heat capacity as the temperature is raised above the bulk smectic A-isotropic transition. The effects of surface "enhanced" pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy, and entropy of FSSFs have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained--by means of calorimetric techniques--data on the heat capacity of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) (H10F5MOPP) films has been obtained.

Thermal and flexoelectric effects on nematodynamics in a microvolume cylindrical cavity

We have considered a homogeneously aligned liquid crystal (HALC) microvolume, confined between two infinitely long horizontal coaxial cylinders subjected to both a temperature gradient nabla T and radially applied electric field E. We have investigated dynamic field pumping, i.e., studied the interaction between director, velocity, electric fields, as well as, a radially applied temperature gradient, where the inner cylinder is kept at a lower temperature than the outer one. Flexoelectric polarization P has been taken into account as well, and modeled via the classical Meyer treatment. In order to elucidate the role of nabla T, E, and P in producing hydrodynamic flow, we have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across the HALC cavity. Calculations show that there exists a range of parameter values (voltage and curvature of the inner cylinder) producing a kinklike orientation process in the system, as well as a nonstandard pumping regime with maximum flow near the hot cylinder.

Effect of electric field and temperature gradient on the orientational dynamics of liquid crystals in a microvolume cylindrical cavity

We have considered a homogeneously aligned liquid crystal (HALC) microvolume confined between two infinitely long horizontal coaxial cylinders and investigated dynamic field pumping, i.e., studied the interactions between director, velocity, and electric E fields as well as a radially applied temperature gradient inverted Delta T, where the inner cylinder is kept at a lower temperature than the outer one. In order to elucidate the role of inverted Delta T in producing hydrodynamic flow u, we have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across the HALC cavity. Calculations show that only under the influence of inverted Delta T does the initially quiescent HALC sample settle down to a stationary flow regime with horizontal component of velocity u(eq)(r). The effects of inverted Delta T and of the size of the HALC cavity on magnitude and direction of u(eq)(r) have been investigated for a number of hydrodynamic regimes. Calculations also showed that E influences only the director redistribution across the HALC but not the magnitude of the velocity u(eq)(r).

QNA-based 'Star Track' QSAR approach

In the existing quantitative structure-activity relationship (QSAR) methods any molecule is represented as a single point in a many-dimensional space of molecular descriptors. We propose a new QSAR approach based on Quantitative Neighbourhoods of Atoms (QNA) descriptors, which characterize each atom of a molecule and depend on the whole molecule structure. In the 'Star Track' methodology any molecule is represented as a set of points in a two-dimensional space of QNA descriptors. With our new method the estimate of the target property of a chemical compound is calculated as the average value of the function of QNA descriptors in the points of the atoms of a molecule in QNA descriptor space. Substantially, we propose the use of only two descriptors rather than more than 3000 molecular descriptors that apply in the QSAR method. On the basis of this approach we have developed the computer program GUSAR and compared it with several widely used QSAR methods including CoMFA, CoMSIA, Golpe/GRID, HQSAR and others, using ten data sets representing various chemical series and diverse types of biological activity. We show that in the majority of cases the accuracy and predictivity of GUSAR models appears to be better than those for the reference QSAR methods. High predictive ability and robustness of GUSAR are also shown in the leave-20%-out cross-validation procedure.

In silico method for identification of promising anticancer drug targets

In recent years, the accumulation of the genomics, proteomics, transcriptomics data for topological and functional organization of regulatory networks in a cell has provided the possibility of identifying the potential targets involved in pathological processes and of selecting the most promising targets for future drug development. We propose an approach for anticancer drug target identification, which, using microarray data, allows discrete modelling of regulatory network behaviour. The effect of drugs inhibiting a particular protein or a combination of proteins in a regulatory network is analysed by simulation of a blockade of single nodes or their combinations. The method was applied to the four groups of breast cancer, HER2/neu-positive breast carcinomas, ductal carcinoma, invasive ductal carcinoma and/or a nodal metastasis, and to generalized breast cancer. As a result, some promising specific molecular targets and their combinations were identified. Inhibitors of some identified targets are known as potential drugs for therapy of malignant diseases; for some other targets we identified hits in the commercially available sample databases.

Director reorientation in a hybrid-oriented liquid-crystal film induced by thermomechanical effect

We have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across a two-dimensional (2D) hybrid-oriented liquid-crystal (HOLC) cell under the influence of a heat flow directed normal to the upper bounding surface, whereas on the rest boundaries the temperature is kept constant. Calculations based upon the nonlinear extension of the classical Ericksen-Leslie theory shows that the HOLC material under the influence of the heat flow, after some time, more than the time of relaxation, for instance, of the director field in the HOLC cell, settles down to the rest state regime, where the horizontal and vertical components of the velocity vector are equal to zero, and the temperature field across the LC cell finally reaches the value of temperature on the lower and two lateral bounding surfaces. The role of hydrodynamic flow in the relaxation processes of the temperature field to its equilibrium distribution across the 2D HOLC cell, containing 4-n-pentyl-4'-cyanobiphenyl, has been investigated, for a number of dynamic regimes.

Liquid-crystal pumping in a cylindrical capillary with radial temperature gradient

Dynamic field pumping principle has been developed utilizing the interactions of both the director and velocity fields and a temperature gradient inverted deltaT. The orientational dynamics in the hybrid-oriented liquid-crystal (HOLC) microvolume confined between two infinitely long coaxial cylinders under the influence of the radially directed inverted deltaT has been investigated. We have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across the HOLC cavity between two cylinders under the influence of inverted deltaT, when the liquid-crystal cavity is heated both from outer (inner) to inner (outer) bounding cylinders. Calculations show that under the influence of inverted deltaT the initially quiescent HOLC drop settles down to a stationary flow regime, with the horizontal u(st)(r) component of velocity. The effects of inverted deltaT , of the character of the preferred anchoring of the average molecular direction to the restricted cylinders, and of the size of the HOLC cavity on magnitude and direction of hydrodynamic flow--for a number of hydrodynamic regimes--has been investigated.