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Alpha-synuclein is a protein, the conformational changes of which lead to the development of such socially significant diseases as Parkinson's disease and amyotrophic lateral sclerosis. The methods for differential diagnostics of these diseases based on the use of alpha-synuclein in a non-native conformation obtained from patients as a seed for inducing fibrillogenesis and studying the morphology of the resulting amyloid-like fibrils were described in a number of studies. The authors associate such properties of the seed with the presence of post-translational modifications in the protein obtained from patients. At the same time, the production of fibrils differing in morphology from recombinant alpha-synuclein under various conditions of fibrillogenesis is also described. In this work, we show that the formation of morphologically distinct fibril types from recombinant alpha-synuclein lacking post-translational modifications is possible under the same conditions, and that spontaneously arising different fibril types, when used as a seed for fibrillogenesis, lead to the formation of recombinant protein fibrils morphological similar to the parental seed. The results of the work can be used both in studying the fundamental mechanisms of conformation transfer and in developing test systems for synucleinopathies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A critical analysis of the known theories of functioning of H + -selective electrodes (H + -SEs) based on neutral amine-type carriers is given. A model of specific ion association is proposed, according to which, in membranes plasticized with 2-nitrophenyloctyl ether, the protonated ionophore and cation-exchanger form much stronger ion pairs with inorganic ions extracted from the sample solution than with each other, and simple equations that describe the lower and upper limit detection (pH UDL and pH LDL ) are obtained. A feasible and reliable method for quantifying the p K a values of ionophores in the membrane phase from potentiometric data is substantiated. The efficiency of using single-ion partition coefficients and ion pair formation constants for a priori quantitative description of the H + -SE response in solutions of various compositions has been demonstrated for the first time. It is shown that the width of the dynamic response range of such electrodes depends on the nature of the tertiary amino group, and the reasons for the observed effect are discussed.

To date, the mechanisms of biomineralization induced by bacterial cells in the context of biofilm formation remain the subject of intensive studies. In this study, we analyzed the influence of the medium components on the induction of CaCO 3 precipitation by the Bacillus cereus cells and composition of the extracellular matrix (ECM) formed in the submerged culture. While the accumulation of extracellular polysaccharides and amyloids appeared to be independent of the presence of calcium and urea during the growth, the accumulation of extracellular DNA (eDNA), as well as precipitation of calcium carbonate, required the presence of both ingredients in the medium. Removal of eDNA, which was sensitive to treatment by DNase, did not affect other matrix components but resulted in disruption of cell network formation and a sixfold decrease in the precipitate yield. An experiment with a cell-free system confirmed the acceleration of mineral formation after the addition of exogenous salmon sperm DNA. The observed pathway for the formation of CaCO 3 minerals in B. cereus planktonic culture included a production of exopolysaccharides and negatively charged eDNA lattice promoting local Ca 2+ supersaturation, which, together with an increase in the concentration of carbonate ions due to pH rise, resulted in the formation of an insoluble precipitate of calcium carbonate. Precipitation of amorphous CaCO 3 on eDNA matrix was followed by crystal formation via the ACC-vaterite-calcite/aragonite pathway and further formation of larger mineral aggregates in complex with extracellular polymeric substances. Taken together, our data showed that DNA in extracellular matrix is an essential factor for triggering the biomineralization in B. cereus planktonic culture., (© 2023. The Author(s).)

Hepatitis B virus core antigen (HBc) with the insertion of four external domains of the influenza A M2 protein (HBc/4M2e) form virus-like particles whose structure was studied using a combination of molecular modeling and cryo-electron microscopy (cryo-EM). It was also shown that self-assembling of the particles occurs inside bacterial cells, but despite the big inner volume of the core shell particle, purified HBc/4M2e contain an insignificant amount of bacterial proteins. It was shown that a fragment of the M2e corresponding to 4M2e insertion is prone to formation of amyloid-like fibrils. However, as the part of the immunodominant loop, M2e insertion does not show a tendency to intermolecular interaction. A full-atomic HBc-4M2e model with the resolution of about 3 Å (3.13 Å for particles of Т = 4 symmetry, 3.7 Å for particles of Т = 3 symmetry) was obtained by molecular modeling methods based on cryo-EM data., Competing Interests: Declaration of Competing Interest The authors have declared that no competing interests exist., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A feasible, fast and reliable method for estimating ion association constants in PVC plasticized membranes of ion-selective electrodes from potentiometric data has been theoretically and experimentally substantiated. The method is based on the established fact of complete dissociation of salts of quaternary ammonium cations R 4 N  +  An ‒ (except for those containing methyl substituents at the nitrogen atom) in a membrane plasticized with o-nitrophenyl octyl ether (o-NPOE). Therefore, the boundary potential at the interface of the membrane with an aqueous solution of R 4 N + depends only upon the concentrations of the corresponding solution and the ion exchanger in the membrane and is independent of the presence of a lipophilic ionic additive (LIA), which makes it possible to use such ions as reference ones in the internal filling solution. If the ions studied (i + ) are capable of forming ion associates with the ion exchanger, then the introduction of LIA into the membrane will lead to a decrease in the concentration of free i + ions and to a corresponding increase in the boundary potential, from which the ion association constant can be directly calculated. The results obtained agree with the known literature data and the results of quantum chemical calculations. The prospective of applying the proposed method to the study of other membrane compositions is discussed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Purpose: Assessment of the indices of macular capillary blood flow and subfoveal choroidal thickness (SCT) using optical coherence tomography angiography in patients with retinal manifestations of ocular ischemic syndrome (RMOIS) associated with atherosclerotic internal carotid artery stenosis., Material and Methods: The study included 34 patients (68 eyes): 21 men, 13 women with RMOIS in one eye. All patients were divided into 2 groups depending on the severity of atherosclerotic internal carotid artery stenosis and ophthalmoscopic picture of the fundus. To obtain objective information we analyzed the degree of decrease in the main indices characterizing macular microcirculation and SCT depending on the severity of RMOIS., Results and Discussion: Analysis of the results showed relationship between the severity of RMOIS and the deficit in macular microcirculation. The macula of the patients with mild RMOIS was characterized by a decrease in the density of superficial vascular plexus (SVP) and the density of deep capillary plexus (DCP) by 13.5% and 10.5% compared to the controls, respectively; in moderate RMOIS - by 19.7% and 14.6%; in severe RMOIS - by 35.9% and 28%, respectively. With an increase in the severity of RMOIS, the area of the foveal avascular zone increased too: in mild degree RMOIS - by 19%, in moderate - by 38.6%, in severe - by 51%. In proportion to the severity of RMOIS, SCT was reduced: in mild degree RMOIS - by only 8%, in moderate - by 22%, and in severe - by 29.8% of the control., Conclusion: The conducted research indicates that pathological changes in RMOIS extend to the entire capillary network of the macula and SCT. With increase in the degree of RMOIS, ischemic changes in all capillary layers of the central parts of the retina proportionally increase in comparison with the control group by 1.15 times in mild degree, by 1.24 times in moderate degree, and by 1.5 times in severe RMOIS.

The work is devoted to the study of the structural characteristics of the myeloperoxidase-ceruloplasmin-thrombin complex using small-angle neutron scattering methods in combination with computer modeling, as well as surface plasmon resonance and solid-phase enzyme assay. We have previously shown that the functioning of active myeloperoxidase during inflammation, despite the presence in the blood of an excess of ceruloplasmin which inhibits its activity, is possible due to the partial proteolysis of ceruloplasmin by thrombin. In this study, the myeloperoxidase-ceruloplasmin-thrombin heterohexamer was obtained in vitro. The building of a heterohexamer full-atomic model in silico, considering the glycosylation of the constituent proteins, confirmed the absence of steric barriers for the formation of protein-protein contacts. It was shown that the partial proteolysis of ceruloplasmin does not affect its ability to bind to myeloperoxidase, and a structural model of the heterohexamer was obtained using the small-angle neutron scattering method., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

An experimentally simple method for the direct determination of single-ion partition coefficients between water and a PVC membrane plasticized with o-NPOE is suggested. The method uses the traditional assumption of equal single-ion partition coefficients for some reference cation and anion, in this case tetraphenylphosphonium (TPP + ) and tetraphenylborate (TPB - ). The method is based on an integrated approach, including direct study of some salts' distribution between water and membrane phases, estimation of ion association constants, and measurements of unbiased selectivity coefficients for ions of interest, including the reference ones. The knowledge of distribution coefficients together with ion association constants allows for direct calculation of the multiple of the single-ion partition coefficients for the corresponding cation and anion, while the knowledge of unbiased selectivity coefficients together with ion association constants allows for immediate estimation of the single-ion partition coefficients for any ion under study, if the corresponding value for the reference ion is known. Both potentiometric and extraction studies are inherently equilibrium-based techniques, while traditionally accepted methods such as voltammetry and diffusion are kinetical. The inner coherent scale of single-ion partition coefficients between water and membrane phases was constructed.

Lake Vostok is the deepest lake of Antarctica but has poor accessibility for study due to a thick glacial cover, however, water samples of this lake have become available for study just recently. Previously, only the microbiome of the ice cover samples was characterized. Here we report results of bacteriological seeding with subsequent identification of the heterotrophic microorganisms (bacteria and micellar fungi) present by 16S rDNA sequencing as well as results of a direct molecular study of the water microbiome. Surprisingly, the data obtained gave evidence of a predominant occurrence of common chemoorganotrophs that were rather psychrotolerant than psychrophilic. We isolated and described strains belonging to eight heterotrophic microbial species able to grow in a rich medium: six bacterial strains belonging to the species Microbacterium testaceum and Microbacterium trichothecenolyticum , Brevundimonas diminuta , Sphingomonas oligophenolica , Sphingomonas sp. and Sphingobium limneticum ; and two fungal strains belonging to Dendryphion sp. and Cladosporium fusiforme . Direct study of 16S rDNA purified water samples confirmed the predominance of the Brevundimonas , Microbacterium, Bradyrhizobium , and Bacillus ( Bacillus cereus ) genera .

The influenza NS1 protein is involved in suppression of the host immune response. Recently, there is growing evidence that prion-like protein aggregation plays an important role in cellular signaling and immune responses. In this work, we obtained a recombinant, influenza A NS1 protein and showed that it is able to form amyloid-like fibrils in vitro. Using proteolysis and subsequent mass spectrometry, we showed that regions resistant to protease hydrolysis highly differ between the native NS1 form (NS1-N) and fibrillar form (NS1-F); this indicates that significant structural changes occur during fibril formation. We also found a protein fragment that is capable of inducing the process of fibrillogenesis at 37 °C. The discovery of the ability of NS1 to form amyloid-like fibrils may be relevant to uncovering relationships between influenza A infection and modulation of the immune response., Competing Interests: Declaration of competing interest None., (Copyright © 2021 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Two influenza A nucleoprotein variants (wild-type: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance between nucleoprotein complex strands. The isolated complexes of two ribonucleoprotein variants were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDF E REGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDF G REGYS). It was also shown that the SGYDF E REGYS peptide is capable of interacting with a monomeric nucleoprotein (wild type); this interaction's equilibrium dissociation constant is five orders of magnitude lower than for the SGYDF G REGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins were studied at temperatures of 15, 32, and 37 °C. SANS data show that the structures of the studied complexes at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.Communicated by Ramaswamy H. Sarma.

Rhegmatogenous retinal detachment (RRD) is one of the most severe eye diseases typically occurring in people of working age. The annual rates of primary vision disability in patients with RRD is 2-9%., Purpose: To increase the functional effectiveness of endovitreal surgery in patients with RRD by including Cytoflavin in the system of postoperative rehabilitation., Material and Methods: The study involved 68 patients with RRD aged 37 to 65 years. Patients underwent vitrectomy using the 25 Gauge technology with endolaser coagulation of rupture zones and silicone oil tamponade in the vitreous cavity. Three months after the surgery, silicone oil was removed from the vitreous cavity. Patients were divided into 2 groups: the main - 34 people who received Cytoflavin in addition to standard therapy, and the control - 34 people receiving only standard postoperative treatment. The time course of the treatment's functional effectiveness was analyzed using best corrected visual acuity (BCVA) and macular photosensitivity. Laser Doppler flowmetry (LDF) was used to register the microcirculation and microcirculation efficiency indices. Morphological signs of macular ischemia were registered by optical coherence tomography angiography (OCT-A)., Results: Patients of the main group showed higher level of restoration of macular function compared with the control group. The increase in functional activity of the macular area correlated with postoperative dynamics of restoration of central retinal thickness. Analysis of LDF and OCT-A indices showed that improvement of visual functions in patients treated with Cytoflavin is directly related to restoration of chorioretinal blood flow., Conclusion: The use of Cytoflavin in patients after endovitreal surgery of RRD led to improvement of BCVA by an average of 2.6 times and photosensitivity of the macula by 2 times. The visual functions of patients improved after using Cytoflavin due to its positive effect on chorioretinal microcirculation and the density of macular capillary plexuses.

In quantum mechanics, the theory of quantum transitions is grounded on the convergence of a series of time-dependent perturbation theory. In nuclear and atomic physics, this series converges because the dynamics of quantum transitions (quantum jumps) are absent by definition. In molecular and chemical physics, on the contrary, the dynamics of "quantum" transitions, being determined by the joint motion of a light electron (or electrons) and very heavy nuclei, are present by definition, and the series of time-dependent perturbation theory becomes singular. An exception is the dynamic problem for stationary states in the Born-Oppenheimer adiabatic approximation, when the electronic subsystem turns out to be "off" from the general dynamic process and therefore is not dynamically full-fledged: it only forms an electric potential in which the nuclei oscillate. Removing the aforementioned singularity can be accomplished in two ways. The first method was consisted of introducing an additional postulate in the form of the Franck-Condon principle into molecular quantum mechanics, in which the adiabatic approximation is used. The second method was proposed by the author and consisted of damping the singular dynamics of the joint motion of an electron and nuclei in the intermediate (transient) state of molecular "quantum" transitions by introducing chaos. This chaos arises only during molecular quantum transitions and is called dozy chaos. Formally, the damping is carried out by replacing an infinitely small imaginary addition in the spectral representation of the complete Green's function of the system with its finite quantity. The damping chaos (dozy chaos) leads to the continuity of the energy spectrum in the molecular transient state, which is a sign of classical mechanics. Meanwhile, the initial and final states of the molecule obey quantum mechanics in the adiabatic approximation. Molecular quantum mechanics, which takes into account the chaotic dynamics of the transient state of molecular "quantum" transitions, can be called quantum-classical (dozy-chaos) mechanics. The efficacy of the damping for the aforementioned singularity was previously shown by dozy-chaos mechanics of elementary electron transfers in condensed matter, which is the simplest case of dozy-chaos mechanics, and its applications to a whole number of problems, especially to the optical spectra in polymethine dyes and their aggregates. This paper provides a regular exposition of this dozy-chaos (quantum-classical) mechanics of the elementary electron transfers. The main results of its applications presented in the introduction are also described., (© 2019 The Author(s).)

This work focuses on the study of multimeric alpha-lactalbumin oleic acid and lactoferrin oleic acid complexes. The purpose of the research is to study possible mechanisms involved in their pro-apoptotic activities, as seen in some tumor cell cultures. Complexes featuring oleic acid (OA) with human alpha-lactalbumin (hAl) or with bovine alpha-lactalbumin (bAl), and human lactoferrin (hLf) were investigated using small-angle neutron scattering (SANS). It was shown that while alpha-lactalbumin protein complexes were formed on the surface of polydisperse OA micelles, the lactoferrin complexes comprised a monodisperse system of nanoscale particles. Both hAl and hLf complexes appeared to interact with the chromatin of isolated nuclei affecting chromatin structural organization. The possible roles of these processes in the specific anti-tumor activity of these complexes are discussed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Communicated by Ramaswamy H. Sarma.

Computer simulations of ion-selective membrane electrodes using diffusion layer models based on finite-differences principle for calculating diffusion processes in both phases and taking into account the local ion exchange equilibrium at the interface are successfully used for clarifying and even predicting the influence of different diffusion factors on several time-dependent characteristics of electrodes. It is shown here that a well-established approach based on the assumption of the constant concentration of the interfering ion in the sample solution fails for solutions containing strongly interfering ions where the concentration of the interfering ion in the boundary layer of the solution can be far lower in comparison with its concentration in the bulk. The limitation is demonstrated by a drastic discrepancy between experimental and calculated curves for the dependence of potential on time. This limitation can be overcome by taking into account the change of the interfering ion concentration in the boundary layer in accordance with the electroneutrality condition. A good agreement between simulation results and experimental data is demonstrated., Competing Interests: The authors declare no competing financial interest.

In a number of conformational diseases, intracellular accumulation of proteins bearing non-native conformations occurs. The search for compounds that are capable of hindering the formation and accumulation of toxic protein aggregates and fibrils is an urgent task. Present fluorescent methods of fibrils' detection prevent simple real-time observations. We suppose to use green fluorescent protein fused with target protein and fluorescence lifetime measurement technique for this purpose. The recombinant proteins analyzed were produced in E. coli. Mass spectrometry was used for the primary structure of the recombinant proteins and post-translational modifications identification. The fluorescence lifetime of the superfolder green fluorescent protein (SF) and the SF protein fused with islet amyloid polypeptide (SF-IAPP) were studied in polyacrylamide gel using Fluorescent-Lifetime Imaging Microscopy (FLIM). It was shown that the SF average fluorescence lifetime in gel slightly differs from that of the SF-IAPP monomer under these conditions. SF-IAPP does not lose the ability to form amyloid-like fibrils. Under the same conditions (in polyacrylamide gel), SF and SF-IAPP monomers have similar fluorescence time characteristics and the average fluorescence lifetime of SF-IAPP in fibrils significantly decreases. We propose the application of FLIM to the measurement of average fluorescence lifetimes of fusion proteins (amyloidogenic protein-SF) in the context of studies using cellular models of conformational diseases., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To assess the etiological significance of herpesviral infection (HVI) in patients with acute idiopathic optic neuritis (ON) using clinical and laboratory monitoring., Material and Methods: Clinical and laboratory examinations were conducted for 10 years and were based on the results of etiological monitoring of 79 patients (85 eyes) with acute idiopathic ON in the period of 2005-2015., Results: During a complex examination of 79 patients with acute idiopathic ON, various infectious pathogens were diagnosed in 75 people (94.9±2.1%). HVI was clearly dominant (69 patients - 87.3±2.4%). These patients were divided into 3 etiological groups. The first group - 34 people with herpesviral monoinfection; the second group - 15 people with mixed viral-viral infections; the third group - 20 people with mixed viral-bacterial infections. In the general population of patients with acute idiopathic ON associated with HVI, herpes simplex virus-1 is the most frequent (by more than 2.5 times), the infections of Epstein-Barr virus and cytomegalovirus were detected less often (p<0.05). Active current HVI in the general group of patients was diagnosed in 58 patients (84%). At the same time, reactivation of chronic infection (79.7%) was noted to be prevalent, while primary acute HVI was diagnosed rarely (4.3%). The remaining 11 patients (16%) had chronic persistent HVI., Conclusion: Clinical and laboratory monitoring of HVI in patients with acute idiopathic ON has shown the etiological role of herpesviruses in its development. Based on a complex of serological markers in enzyme-linked immunoassay reactions of blood serum, it was found that in patients with acute idiopathic ON the frequency of herpesviral infection is 87.3±2.4%. The proportion of active (etiologically significant) herpesviral infection is 84% of the total group. The results of the clinical and laboratory studies are of great practical importance for verification of the etiologic diagnosis and selection of adequate etiopathogenetic therapy in patients with acute idiopathic ON associated with HVI.

It is shown that a simple dynamic diffusion model of the boundary potential based on a separate, step-by-step, account of ion transfer across the membrane/aqueous solution interface and the diffusion processes within both phases which was proposed earlier for describing the response of ionophore-free membranes, can be successfully used for ionophore-based membranes as well. The model makes it possible to carry out both separate and joint account of the effects of co-extraction, transmembrane transport and ion exchange on the boundary potential and retains robustness in all the variants studied. The model adequately describes the ionophore-based electrode response over the entire range of concentrations and allows one to clearly demonstrate the dependence of lower detection limit on such parameters as the diffusion coefficients and the concentration of electroactive substances in the membrane phase, the thickness of the diffusion layer in the sample solution, the duration of the measurement, and the composition of the internal reference solution. The results of numerical simulation are in good agreement with the experimental data presented in the literature. As all the factors of influence considered above can easily be regulated in more or less wide limits, but at the same time, an estimation of their cumulative effect is not always possible on an intuitive level, the present model can be of practical interest for justifying the ways of optimizing the design of the ISE and the algorithm for performing measurements in solving specific analytical problems., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, we present molecular dynamics simulations of the antiviral drug triazavirine, that affects formation of amyloid-like fibrils of the model peptide (SI). According to our simulations, triazavirine is able to form linear supramolecular structures which can act as shields and prevent interactions between SI monomers. This model, as validated by simulations, provides an adequate explanation of triazavirine's mechanism of action as it pertains to SI peptide fibril formation.

One of the main problems in the area of influenza prophylaxis and pandemic prevention is the development of cross-reactive vaccines, i.e. vaccines directed against all subtypes of human influenza viruses. Such vaccines are being developed in many countries for more than 10 years. A number of vaccines are presently undergoing clinical trials. We created Uniflu candidate vaccine based on recombinant HBc4M2e protein consisting of 4 tandem-connected copies of the highly conserved ectodomain of M2 protein of the influenza A virus. These 4 copies were genetically fused to the carrier protein, namely hepatitis B core antigen. Commercially available Derinat was used as adjuvant in the candidate vaccine. Preclinical studies on laboratory animals (mice, ferrets) demonstrated that immunization with Uniflu leads to significantly higher level of specific immunoglobulins in the blood and bronchoalveolar lavages. Moreover, it produces immunoglobulins belonging to subtype IgG2a that is the most important mediator of antibody-dependent cytotoxicity. The vaccine under review stimulates the proliferation of T-lymphocytes, as well as the formation of CD4+ and CD8+ T-cells synthesizing ɣ-IFN. When infected with the lethal doses (5 LD50) of influenza A viruses of the subtypes H1N1, H2N2, H3N2, and H1N1pdm09, immunized animals typically developed mild form of illness. This kept them alive in 90-100% of cases, which demonstrated almost complete protection from death. Replication of the virus in the lungs of immunized mice was reduced by 1.8-4.8 log10. High immunogenicity of the vaccine, and reduced clinical symptoms following experimental infection, were demonstrated in ferrets as well. The developed recombinant vaccine Uniflu has high specific activity and cross-protection. Uniflu can be proposed as pre-pandemic vaccine, provided that it passes clinical trials.

The influenza virus polymerase complex is a promising target for new antiviral drug development. It is known that, within the influenza virus polymerase complex, the PB1 subunit region from the 1st to the 25th amino acid residues has to be is in an alpha-helical conformation for proper interaction with the PA subunit. We have previously shown that PB1(6-13) peptide at low concentrations is able to interact with the PB1 subunit N-terminal region in a peptide model which shows aggregate formation and antiviral activity in cell cultures. In this paper, it was shown that PB1(6-13) peptide is prone to form the amyloid-like fibrillar aggregates. The peptide homo-oligomerization kinetics were examined, and the affinity and characteristic interaction time of PB1(6-13) peptide monomers and the influenza virus polymerase complex PB1 subunit N-terminal region were evaluated by the SPR and TR-SAXS methods. Based on the data obtained, a hypothesis about the PB1(6-13) peptide mechanism of action was proposed: the peptide in its monomeric form is capable of altering the conformation of the PB1 subunit N-terminal region, causing a change from an alpha helix to a beta structure. This conformational change disrupts PB1 and PA subunit interaction and, by that mechanism, the peptide displays antiviral activity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A simple dynamic model of the phase boundary potential of ion-selective electrodes is presented. The model is based on the calculations of the concentration profiles of the components in membrane and sample solution phases by means of the finite difference method. The fundamental idea behind the discussed model is that the concentration gradients in both membrane and sample solution phases determine only the diffusion of the components inside the corresponding phases but not the transfer across the interface. The transfer of the components across the interface at any time is determined by the corresponding local interphase equilibria. According to the presented model, each new calculation cycle begins with the correction of the components' concentrations in the near-boundary (first) layers of the membrane and solution, based on the constants of the interphase equilibria and the concentrations established at a given time as a result of diffusion. The corrected concentrations of the components in the boundary layers indicate the start of a new cycle every time with respect to the calculations of diffusion processes inside each phase from the first layer to the second one, and so on. In contrast to the well-known Morf's model, the above-mentioned layers do not comprise an imaginary part and are entirely localized in the corresponding phases, and this allows performing the calculations of the equilibrium concentrations by taking into account material balance for each component. The model remains operational for any realistic scenarios of the electrode functioning. The efficiency and predictive ability of the proposed model are confirmed by comparing the results of calculations with the experimental data on the dynamics of the potential change of a picrate-selective electrode in nitrate solutions when determining the selectivity coefficients using the methods recommended by IUPAC.

Anti-influenza drugs and vaccines have a limited effect due to the high mutation rate of virus genome. The direct impact on the conservative virus genome regions should significantly improve therapeutic effectiveness. The RNA interference mechanism (RNAi) is one of the modern approaches used to solve this problem. In this work, we have investigated the antiviral activity of small interfering RNA (siRNA) against the influenza A/PR/8/34 (H1N1), targeting conserved regions of NP and PA. Polycations were used for intracellular siRNA delivery: chitosan's derivatives (methylglycol and quaternized chitosan), polyethyleneimine, lipofectamine, and hybrid organic/non-organic microcapsules. A comparative study of these delivery systems with fluorescent labeled siRNA was conducted. The antiviral activity of three small interfering RNAs targeting the NP (NP-717, NP-1496) and PA (PA-1630) influenza A viruses genes was demonstrated, depending on the chosen carrier. The most effective intracellular delivery and antiviral activity were observed for hybrid microcapsules.

Results on the theoretical explanation of the shape of optical bands in polymethine dyes, their dimers and aggregates are summarized. The theoretical dependence of the shape of optical bands for the dye monomers in the vinylogous series in line with a change in the solvent polarity is considered. A simple physical (analytical) model of the shape of optical absorption bands in H-aggregates of polymethine dyes is developed based on taking the dozy-chaos dynamics of the transient state and the Frenkel exciton effect in the theory of molecular quantum transitions into account. As an example, the details of the experimental shape of one of the known H-bands are well reproduced by this analytical model under the assumption that the main optical chromophore of H-aggregates is a tetramer resulting from the two most probable processes of inelastic binary collisions in sequence: first, monomers between themselves, and then, between the resulting dimers. The obtained results indicate that in contrast with the compact structure of J-aggregates (brickwork structure), the structure of H-aggregates is not the compact pack-of-cards structure, as stated in the literature, but a loose alternate structure. Based on this theoretical model, a simple general (analytical) method for treating the more complex shapes of optical bands in polymethine dyes in comparison with the H-band under consideration is proposed. This method mirrors the physical process of molecular aggregates forming in liquid solutions: aggregates are generated in the most probable processes of inelastic multiple binary collisions between polymethine species generally differing in complexity. The results obtained are given against a background of the theoretical results on the shape of optical bands in polymethine dyes and their aggregates (dimers, H*- and J-aggregates) previously obtained by V.V.E., Competing Interests: The author declares no competing interests.

Aim: to study the frequency of misdiagnosis of cataract in patients with optic nerve pathology or amblyopia and to identify its main causes., Material and Methods: The study enrolled 381 patients (381 eyes) wrongly diagnosed with cataract. A standard set of eye tests was performed. In-depth examination of the macular area was done through biomicroscopy with contactless aspheric lenses of 60 and 90 D. Part of the patients underwent optical coherence tomography and static perimetry as well as examination of electrical sensitivity threshold and electrical lability of the optic nerve., Results: In 190 patients (190 eyes - 49.9%), the true cause of central vision impairment was optic nerve pathology associated with its partial atrophy of different origins: vascular (77.8%) or post-traumatic (22.2%). Glaucomatous atrophy of the optic nerve was found in 175 patients within the age range from 57 to 70 years (175 eyes - 45.9%). These were newly diagnosed cases of advanced open-angle glaucoma. In 16 eyes (4.2%), the true cause of low vision appeared to be amblyopia of some type: strabismic (9 eyes - 56.3%), refractive (4 eyes - 25%), or mixed (3 eyes - 18.7%)., Conclusion: The main diagnostic errors of attending ophthalmologists were the following: underestimation of the discrepancy between low visual functions and small degree of lens opacity as well as the neglect of careful examination of the fundus (specifically, the optic disc and macula), additional perimetry, thorough history taking, and cover-testing for suspected amblyopia.

Aim: to compare the effectiveness of biomicroscopy (BMS) and optical coherence tomography (OCT) in recognizing prognostically unfavorable signs in peripheral vitreoretinal dystrophy (PVRD) patients., Material and Methods: A total of 131 cases of equatorial PVRD (91 eyes of 56 patients) were assessed. The mean patient's age was 24.7 years. The length of the anterior-posterior axis of the eyeball averaged 25.36±1.12 mm. Prevalence of particular warning signs in PVRD patients at BMS or OCT was comparatively analyzed., Results: In 46 eyes with lattice dystrophy it was difficult to determine the presence of vitreoretinal traction at BMS; at OCT, areas of retinal adhesion to the posterior hyaloid membrane (PHM) along the edges of PVRD zones were revealed in all eyes. Of 31 eyes with «snail tracks» defects of the retina, 6 were diagnosed at BMS; in OCT scans of these patients, the PHM appeared firmly fixed along the edges of PVRD zones in all cases. As to horseshoe retinal tears (valve-like tears), BMS allowed to visualize vitreoretinal tractions in 7 of 12 eyes, while OCT revealed a tight contact between the PHM and the apex of the retinal flap in 11 of 12 eyes. In 7 eyes with retinoschisis we failed to detect any retinal traction at either BMS or OCT. In «non-differentiable» PVRD, BMS was also not able to reveal any vitreoretinal traction, while OCT was - in all 12 cases., Conclusion: OCT has proved much more effective than BMS in recognizing prognostically unfavorable signs in particular clinical forms of PVRD, such as vitreoretinal tractions, retinal defects, and intraretinal cavities.

The role of Tamm-Horsfall protein in pathogenesis of urolithiasis was analyzed. The study of oligomeric forms of protein was carried out using technique of dynamic light scattering. The sampling of 57 patients with urolithiasis and 51 patients of control group of comparative age and gender were examined. The degree of purification of Tamm-Horsfall protein was controlled using denaturant electrophoresis in polyacridine amyl gel. The reversing change of oligomeric form of protein with molecule size 2 Mda in polymeric form 28 Mda under impact of guanidinhydrochloride. Under urolithiasis, the form of protein associated with non-organic components and with size of macromolecular complex larger than 1500 nm was detected. The diagnostic criterion of urolithiasis was proposed based on totality of biochemical and biophysical analyses of urine.

Background: Influenza A virus (IAV) is a segmented negative-sense RNA virus that causes seasonal epidemics and periodic pandemics in humans. Two regions (nucleotide positions 82-148 and 497-564) in the positive-sense RNA of the NS segment fold into a multi-branch loop or hairpin structures., Results: We studied 25,384 NS segment positive-sense RNA unique sequences of human and non-human IAVs in order to predict secondary RNA structures of the 82-148 and 497-564 regions using RNAfold software, and determined their host- and lineage-specific distributions. Hairpins prevailed in avian and avian-origin human IAVs, including H1N1pdm1918 and H5N1. In human and swine IAV hairpins distribution varied between evolutionary lineages., Conclusions: These results suggest a possible functional role for these RNA secondary structures and the need for experimental evaluation of these structures in the influenza life cycle.

Sepsis is a generalized infection accompanied by response of the body that manifests in a clinical and laboratory syndrome, namely, in the systemic inflammatory response syndrome (SIRS) from the organism to the infection. Although sepsis is a widespread and life-threatening disease, the assortment of drugs for its treatment is mostly limited by antibiotics. Therefore, the search for new cellular targets for drug therapy of sepsis is an urgent task of modern medicine and pharmacology. One of the most promising targets is the adenosine A(2A) receptor (A(2A)AR). The activation of this receptor, which is mediated by extracellular adenosine, manifests in almost all types of immune cells (lymphocytes, monocytes, macrophages, and dendritic cells) and results in reducing the severity of inflammation and reperfusion injury in various tissues. The activation of adenosine A(2A) receptor inhibits the proliferation of T cells and production of proinflammatory cytokines, which contributes to the activation of the synthesis of anti-inflammatory cytokines, thereby suppressing the systemic response. For this reason, various selective A(2A)AR agonists and antagonists may be considered to be drug candidates for sepsis pharmacotherapy. Nevertheless, they remain only efficient ligands and objects of pre-clinical and clinical trials. This review examines the molecular mechanisms of inflammatory response in sepsis and the structure and functions of A(2A)AR and its role in the pathogenesis of sepsis, as well as examples of using agonists and antagonists of this receptor for the treatment of SIRS and sepsis.

By means of spectrophotometric assay we investigated interaction of the dye Congo red (CR) with fibrils of model proteins--hen egg white lysozyme, recombinant human beta2-microglobulin (b2M) and recombinant human transthyretin (TTR). The commercial dye sample was found to contain a significant amount of impurities. Methods for the dye purification are disclosed and CR molar extinction coefficient at 490 nm (ε490) was determined to be 3.3 x 10(4) M(-1) x cm(-1) at pH above 6.0. Formation of the CR-fibril complex results in changes in the dye visible absorption spectrum. According to the data on titration of fibril solutions with excess of the dye, CR binds to lysozyme fibrils at a ratio of about 5 molecules per protein monomer within fibril structure, to b2M fibrils--about 4 molecules per monomer, to TTR fibrils--about 4 molecules per subunit of the protein.

Ebola hemorrhagic fever (EHF) epidemic currently ongoing in West Africa is not the first among numerous epidemics in the continent. Yet it seems to be the worst EHF epidemic outbreak caused by Ebola virus Zaire since 1976 as regards its extremely large scale and rapid spread in the population. Experiments to study the agent have continued for more than 20 years. The EHF virus has a relatively simple genome with seven genes and additional reading frame resulting from RNA editing. While being of a relatively low genetic capacity, the virus can be ranked as a standard for pathogenicity with the ability to evade the host immune response in uttermost perfection. The EHF virus has similarities with retroviruses, but belongs to (-)RNA viruses of a nonretroviral origin. Genetic elements of the virus, NIRV, were detected in animal and human genomes. EHF virus glycoprotein (GP) is a class I fusion protein and shows more similarities than distinctions in tertiary structure with SIV and HIV gp41 proteins and even influenza virus hemagglutinin. EHF is an unusual infectious disease, and studying the molecular basis of its pathogenesis may contribute to new findings in therapy of severe conditions leading to a fatal outcome.

Aim: To study the frequency of patients with macular pathology being wrongly diagnosed with cataract and possible reasons for this to occur., Material and Methods: A total of 1390 patients (1390 eyes), in whom cataract turned out to be not the main cause of visual impairment, were recruited as research subjects. To reveal the reasons for misdiagnosis, we resorted to methods of ophthalmic examination that are available at ambulatory care facilities, i.e. visual acuity measurement, slit lamp biomicroscopy of the anterior and posterior eye segments, direct and indirect ophthalmoscopy., Results: In most patients (72.6%) visual acuity was decreased due to macular pathology, especially age-related macular degeneration (AMD)--736 eyes (72.9%). Less common were degenerative myopia (10%), idiopathic macular hole (8.4%), epiretinal macular fibrosis (5.1%), and secondary macular changes of vascular, traumatic, or inflammatory genesis (3.6%). In 76.6% of eyes with macular pathology ophthalmoscopy was perfectly feasible and could be performed by a local ophthalmologist. Only in 23.4% of cases there was a dense posterior capsule opacification or nuclear cataract that impeded visualization of macular structures., Conclusions: The main reason for misdiagnosis of macular pathology and referring the patient to cataract surgeon was the neglect of apparent discordance between visual acuity and lens transparency. One should aim at adequate assessment of macular zone by all means, including non-contact ophthalmoscopy with 60 or 90 D aspherical lenses or Hruby lens and red-free examination.

Ebola hemorrhagic fever (EHF) epidemic currently ongoing in West Africa is not the first among numerous epidemics in the continent. Yet it seems to be the worst EHF epidemic outbreak caused by Ebola virus Zaire since 1976 as regards its extremely large scale and rapid spread in the population. Experiments to study the agent have continued for more than 20 years. The EHF virus has a relatively simple genome with seven genes and additional reading frame resulting from RNA editing. While being of a relatively low genetic capacity, the virus can be ranked as a standard for pathogenicity with the ability to evade the host immune response in uttermost perfection. The EHF virus has similarities with retroviruses, but belongs to (-)RNA viruses of a nonretroviral origin. Genetic elements of the virus, NIRV, were detected in animal and human genomes. EHF virus glycoprotein (GP) is a class I fusion protein and shows more similarities than distinctions in tertiary structure with SIV and HIV gp41 proteins and even influenza virus hemagglutinin. EHF is an unusual infectious disease, and studying the molecular basis of its pathogenesis may contribute to new findings in therapy of severe conditions leading to a fatal outcome., (© Pleiades Publishing, Inc. 2015.)

This study is devoted to the antiviral activity of peptide fragments from the PB1 protein - a component of the influenza A RNA polymerase. The antiviral activity of the peptides synthesized was studied in MDCK cell cultures against the pandemic influenza strain A/California/07/2009 (H1N1) pdm09. We found that peptide fragments 6-13, 6-14, 26-30, 395-400, and 531-540 of the PB1 protein were capable of suppressing viral replication in cell culture. Terminal modifications i.e. N-acetylation and C-amidation increased the antiviral properties of the peptides significantly. Peptide PB1 (6-14) with both termini modified showed maximum antiviral activity, its inhibitory activity manifesting itself during the early stages of viral replication. It was also shown that the fluorescent-labeled analog of this peptide was able to penetrate into the cell. The broad range of virus-inhibiting activity of PB1 (6-14) peptide was confirmed using a panel of influenza A viruses of H1, H3 and H5 subtypes including those resistant to oseltamivir, the leading drug in anti-influenza therapy. Thus, short peptide fragments of the PB1 protein could serve as leads for future development of influenza prevention and/or treatment agents., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Influenza A virus is one of the major human pathogens. Despite numerous efforts to produce absolutely effective anti-influenza drugs or vaccines, no such agent has been developed yet. One of the main reasons for this complication is the high mutation rate and the specific structure of influenza A viruses genome. For more than 25 years since the first mapping of the viral genome, it was believed that its 8 genome segments encode 10 proteins. However, the proteome of influenza A viruses has turned out to be much more complex than previously thought. In 2001, the first accessory protein, PB1-F2, translated from the alternative open reading frame, was discovered. Subsequently, six more proteins, PB1-N40, PA-X, PA-N155, PA-N182, M42, and NS3, have been found. It is important to pay close attention to these novel proteins in order to evaluate their role in the pathogenesis of influenza, especially in the case of outbreaks of human infections with new avian viruses, such as H5N1 or H7N9. In this review we summarize the data on the molecular mechanisms used by influenza A viruses to expand their proteome and on the possible functions of the recently discovered viral proteins., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The fibrillogenesis of a peptide corresponding to residues 35-51 of human α-lactalbumin (¹GYDTQAIVENNESTEYG¹⁷) can be dramatically enhanced by the addition of a tetrapeptide TDYG homologous to its C-terminus (TEYG). Generation of spontaneous hydrolytic products similar to this peptide was demonstrated by mass-spectrometry analysis of GYDTQAIVENNESTEYG peptide solution components during fibrillogenesis. Possible mechanisms and roles of short peptides in protein metabolism are discussed.

The diagnostic oligonucleotide microarray for subtyping of human and animal influenza A viruses (IAVs) was developed. We proposed a simple method of the fluorescent labeling of genomic segments of all known IAVs subtypes, the composition of the hybridization buffer, as well as the software of the data processing. 48 IAVs strains of different subtypes were analyzed using our microarray. All of them were identified, while 45 of 48 strains were unambiguously subtyped.

Myocilin is a protein with a molecular weight near 50 kDa. It is expressed in almost all organs and tissues. We showed that the peptide DQLETQTRELETAYSNLLRD corresponding to N-terminal Leucine zipper motif (LZM) of the protein is able to form amyloid-like fibrils. The possible role of this motif in myocilin aggregation is discussed.

A mirror-symmetry motif was discovered in the N-terminus of the influenza virus PB1 protein. Structure of peptide comprised of the corresponding part of PB1 (amino acid residues 6-25) was investigated by circular dichroism and in silico modeling. We found that peptide PB1 (6-25) in solution assumes beta-hairpin conformation. A truncated peptide PB1 (6-13), containing only half of the mirror-symmetry motif, appeared to stabilize the beta-structure of the original peptide and, at high concentrations, was capable of reacting with peptide to form insoluble aggregates in vitro. Ability of PB1 (6-13) peptide to interact with the N-terminal domain of PB1 protein makes it a potential antiviral agent that inhibits PA-PB1 complex formation by affecting PB1 N-terminus structure.

Transcription of eukaryotic genes is regulated by phosphorylation of serine residues of heptapeptide repeats of the carboxy-terminal domain (CTD) of RNA polymerase II (RNAPII). We previously reported that protein phosphatase-1 (PP1) dephosphorylates RNAPII CTD in vitro and inhibition of nuclear PP1-blocked viral transcription. In this article, we analyzed the targeting of RNAPII by PP1 using biochemical and mass spectrometry analysis of RNAPII-associated regulatory subunits of PP1. Immunoblotting showed that PP1 co-elutes with RNAPII. Mass spectrometry approach showed the presence of U2 snRNP. Co-immunoprecipitation analysis points to NIPP1 and PNUTS as candidate regulatory subunits. Because NIPP1 was previously shown to target PP1 to U2 snRNP, we analyzed the effect of NIPP1 on RNAPII phosphorylation in cultured cells. Expression of mutant NIPP1 promoted RNAPII phosphorylation suggesting that the deregulation of cellular NIPP1/PP1 holoenzyme affects RNAPII phosphorylation and pointing to NIPP1 as a potential regulatory factor in RNAPII-mediated transcription.

The possibility of obtaining recombinant fibrillogenic fusion proteins such as transthyretin (TTR) and β2-microglobulin (β2M) with a superfolder green fluorescent protein (sfGFP) was studied. According to the literature data, sfGFP is resistant to denaturating influences, does not aggregate during renaturation, possesses improved kinetic characteristics of folding, and folds well when fused to different polypeptides. The corresponding DNA constructs for expression in Escherichia coli were created. It could be shown that during expression of these constructs in E. coli, soluble forms of the fusion proteins are synthesized. Efficient isolation of the fusion proteins was performed with the help of nickel-affinity chromatography. For this purpose a polyhistidine sequence (6-His-tag) was incorporated into the C-terminus of the sfGFP. We could show that the purified fusion proteins contained full-size sequences of the most amyloidogenic TTR variant, TTR(L55P) and β2M, and also sfGFP possessing fluorescent properties. In the course of fibrillogenesis both fusion proteins demonstrated their ability to form fibrils that were clearly detectable by atomic force microscopy. Furthermore, with the help of confocal microscopy we were able to reveal structures (exhibiting fluorescence) that are formed during fibrillogenesis. Thus, the use of sfGFP has made it possible to avoid formation of inclusion bodies (IB) during the synthesis of recombinant fusion proteins and to obtain soluble forms of TTR(L55P) and β2M that are suitable for further studies.

Patients with a family history of diabetes mellitus should undergo complex antistress protection of the macula for the prevention of its stress-induced lesions during cataract phacoemulsification with intraocular lens implantation. A differential algorithm of stress protection therapy has been developed in relation to the phase of surgical stress, the use of which is to enhance the tolerance of vegetovascular, hemodynamic, and metabolic systems to the aggressive components of surgical stress, thus reducing the incidence of transient subclinical and clinical macular edema.

Optical coherent tomography (OCT) shows that in patients with diabetes mellitus (DM), a macular morphological response to cataract phacoemulsification (CPE) with intaocular lens (IOL) implantation proceeds as 3 types: 1) areactive without macular morphological changes; 2) hyperreactive with the development of reversible subclinical macular edema; and 3) aggressive with the transition of stress-induced retinal morphological lesions to clinically significant diabetic macular edema. Morphological differences in OCT parameters were established to have impact on the effect of visual rehabilitation. Following 3-4 months of CPE with IOL implantation in DM patients with the areactive type of a macular morphological response to surgical stress, the increase in visual acuity exceeded that observed in the hyperactive and aggressive types of a macular response by 12.8 and 57.7%, respectively. The findings suggest that medical preventive measures reducing the negative consequences of surgical stress should be implemented in DM patients at catarrhal surgery.

The present work was undertaken to evaluate a new minimally invasive method of surgical management of varicose disease by means of the TriVex unit. The method is based on transillumination of saphenous veins in an aqueous medium, which makes it possible to perform radical removal thereof form separate punctures under visual control with the help of a specially designed vein stripper. Transillumination-assisted phlebectomy (TIP) was compared with microphlebectomy (MPE) according to the Varady's technique. We operated on a total of one hundred and eight patients suffering from varicose disease of the lower extremities. All of them underwent duplex scanning of the veins. Group One (study group) was composed of fifty-six patients subjected to TIP within the scope of a comprehensive treatment for varicose disease. Group Two consisted of fifty-two patients who were subjected to removal of varicosely altered affluents on the crus by means of microphlebectomy. The results of surgical management for varicose disease were analysed according to the following parameters, the duration of a surgical intervention, intensity of the pain syndrome in the postoperative extremity, a cosmetic outcome by visual analogue scales, and the incidence rate of complications. The obtained findings demonstratively showed that the duration of the operation in the study group was substantially shorter, averagely amounting to 35.5+/-6.2 minutes, as compared with as long as 65.0+/-6.2 minutes (P<0.0001) in the control group. The number of incisions in the study group turned out to be also significantly less than that in the control group, amounting to 4.0+/-1.3 vs. 12.0+/-2.5 (p<0.0001), which largely contributed to both a decrease in the level of the pain syndrome and obtaining aesthetically pleasing cosmetic outcomes. Hence, TIP being a minimally invasive procedure in surgical management of varicose disease, by its clinical efficiency appeared to be not inferior and at least equivalent to microphlebectomy, displaying at the same time certain advantages over the latter, consisting in the very positive cosmetic outcome obtained, a lesser operative injury inflicted, and shorter terms of rehabilitation of the patients involved.

Symmetrical peptide GYDTQAIVENNESTEYG (WT, Wild Type) identical to 35-51 aminoacid residues of human alpha-lactalbumin (HLA) and peptide GYDTQTVVNNNGHTDYG (ID, IDeal symmetry) homologous to beta-domain of mammalian alpha-lactalbumins can form amyloid-like fibrils in conditions required for fibrillogenesis of HLA. The latter peptide can also form fibrils in deionized water. Fibrils formed by these peptides can cause forming of HLA amyloid-like aggregates in physiological conditions. These results provide an evidence for presence of amyloidogenic determinant in beta-domain of alpha-lactalbumin. Thus, symmetry in the primary structure may play the role in fibrillogenesis of proteins.

The influence of the ISE membrane composition on the selectivity for primary, secondary, tertiary, and quaternary alkylammonium cations, as well as for cations of physiologically active amines, has been investigated. Factors studied include the effect of plasticizer (2-nitrophenyl octyl ether, o-NPOE; dibutyl phthalate, DBP; dinonyl adipate, DNA; tris(2-ethylhexyl) phosphate, TEHP) and ion exchanger (potassium tetrakis(4-chlorophenyl)borate, K(TpClPB); potassium tris(nonyloxy)benzenesulfonate, K(TNOBS)), as well as that of the lipophilic cationic additive (tetradecylammonium nitrate, (TDA)NO(3)) and neutral carrier (dibenzo-18-crown-6) presence in membrane. It has been established that plasticizer nature affects K(i,j)(pot) values both when the target and/or foreign ions have non-ionic polar groups capable of specific interaction with plasticizer, and when the only difference consists in the substitution degree of their ionic groups. K(i,j)(pot) values for quaternary alkylammonium cations over primary-tertiary ones change in the following order: TEHP>DBP approximately DNA>o-NPOE. The highest K(i,j)(pot) value change is achieved for the primary-quaternary alkylammonium cation pair, amounting to 3 and 4.7 orders for membranes containing K(TNOBS) and K(TpClPB) as ion exchangers, respectively. In its turn, the ion exchanger influence on the selectivity depends on plasticizer nature, it being maximal for o-NPOE (about 2 orders) and practically non-existent for TEHP. On the whole, as compared to K(TpClPB)-based ISEs, those based on K(TNOBS) show higher selectivity for primary-tertiary alkylammonium cations over quaternary ones. Incorporation of (TDA)NO(3) into membrane causes further improvement of selectivity for primary-tertiary alkylammonium cations in the case of K(TNOBS) only. The maximal total effect of the ion exchanger and lipophilic ionic additive is observed for ISEs with DNA-plasticized membranes and is over 3 orders. The influence of crown ether on the selectivity also depends significantly upon ion exchanger and plasticizer nature. For ISEs with o-NPOE-plasticized membranes the K(i,j)(pot) value changes can be as great as 3 (ion exchanger K(TNOBS)) and even 4.5 (ion exchanger K(TpClPB)) orders. On the contrary, for ISEs with TEHP-plasticized membranes the crown ether effect on the selectivity is unessential. The results obtained are explained by peculiarities of organic ammonium cations solvating by plasticizer and association of cations with ion exchangers.