Prospects for the use of graphene-based biological sensors in the early diagnosis of Alzheimer's disease (review of literature).

Among the most significant challenges presented to modern medicine is the problem of cognitive disorders. The relevance of her research is determined by the wide spread of disorders of the higher cortical functions, their significant negative impact on the quality of life of patients, as well as high economic costs on the part of the state and the patient's relatives aimed at organizing medical, diagnostic and rehabilitation processes. The main cause of cognitive impairment in the elderly is Alzheimer's disease. Currently, the criteria for the diagnosis of this nosological form have been developed and are widely used in practice. However, it should be noted that their use is most effective if the patient has a detailed clinical picture, at the stage of dementia. In addition, they provide for the study of biomarkers in a number of cases in the cerebrospinal fluid or using positron emission tomography, which presents certain technical difficulties. Especially significant problems arise in the pre-dement stages. This situation dictates the need to search for new promising diagnostic methods that will have high sensitivity and specificity, as well as the possibility of application in the early stages of Alzheimer's disease, including in outpatient settings. The article provides information about modern methods of computer neuroimaging, discusses the research directions of individual biomarkers, and also shows the prospects for using diagnostic test panels developed on the basis of graphene biosensors, taking into account the latest achievements of nanotechnology and their integration into medical science.

Cold and distant: structural features of the nucleoprotein complex of a cold-adapted influenza A virus strain.

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 (SGYDFEREGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDFGREGYS). It was also shown that the SGYDFEREGYS 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 SGYDFGREGYS 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.

Formation and Luminescent Properties of Al2O3:SiOC Nanocomposites on the Base of Alumina Nanoparticles Modified by Phenyltrimethoxysilane.

Al2O3:SiOC nanocomposites were synthesized by thermal treatment of fumed alumina nanoparticles modified by phenyltrimethoxysilane. The effect of annealing temperature in inert ambient on structure and photoluminescence of modified alumina powder was studied by IR spectroscopy as well as photoluminescence spectroscopy with ultraviolet and X-ray excitation. It is demonstrated that increase of annealing temperature results in formation of silica precipitates on the surface of alumina particles that is accompanied by development and spectral evolution of visible photoluminescence. These observations are discussed in terms of structural transformation of the surface of Al2O3 particles.

EVOLUTIONARY DYNAMICS OF STRUCTURAL AND FUNCTIONAL DOMAINS OF INFLUENZA A VIRUS NS1 PROTEIN.

Influenza A virus (IAV) NS1 protein is one of the key viral factors responsible for virus-host interactions. NS1 counteracts host antiviral defense, participates in the processing and export of cellular mRNAs, regulates the activity of viral RNA polymerase and the expression of viral genes, and influences the cellular signaling systems. Multiple NS1 functions are carried out due to the interactions with cellular factors, the number of which exceeds one hundred. It is noteworthy that only two segments of IAV genome - NS and NP - did not undergo reassortment and evolved in the course of genetic drift, beginning with the pandemic of 1918 to the present. This fact may indicate the importance of NS1 and its numerous interactions with cellular factors in the interspecific adaptation of the virus. The review presents data on the evolution of the human IAV NS1 protein and analysis of the amino acid substitutions in the main structural and functional domains of NS1 protein during evolution.

COMPARISON OF INFLUENZA A VIRUS INHIBITION IN VITRO BY SIRNA COMPLEXES WITH CHITOSAN DERIVATIVES, POLYETHYLENEIMINE AND HYBRID POLYARGININE-INORGANIC MICROCAPSULES.

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.

[EFFECT OF REPEATED SPACE FLIGHTS ON OCULAR TRACKING].

The paper reports the results of studying the vestibular and ocular intersensory interactions and eye tracking function in 32 cosmonauts on maiden and repeated missions to the International space station. Mission duration ranged from 125 to 215 days. The cosmonauts were tested twice pre launch (baseline data collection) and on days R + 1/2, 4/5 and 8/9. Video oculography was used to test eye movements. It was found that in the majority of cosmonauts who had no experience of long-duration space missions the eye tracking function remained impaired significantly till R + 8/9. In cosmonauts who had already encountered with microgravity, obvious changes in eye tracking were observed on R + 1/2 only and, residual, on R + 4/5. On recovery, a new eye tracking strategy was acquired only by cosmonauts who had the first touch with spaceflight microgravity.

The influenza A virus NS genome segment displays lineage-specific patterns in predicted RNA secondary structure.

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.

[Adenosine A2A receptor as a drug target for treatment of sepsis].

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.

[Ebola hemorrhagic fever: Properties of the pathogen and development of vaccines and chemotherapeutic agents].

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.

[VESTIBULAR FUNCTION AFTER REPEATED SPACE FLIGHTS].

Results of the vestibular function testing of 32 cosmonauts on return from repeated 125- to 215-day space flights (SF) on the International space station are presented. The cosmonauts were tested twice before flight (baseline data collection) and on days 1-2, 4-5 and 8-9 after landing. Electro- and video-oculography were used to register simultaneously eye and head movements. It was found that deadaptation following a repeated stay in long-duration SF takes statistically much shorter time. Most often, atypical vestibular disorders and changed patterns of the otolith-semicircular canal interaction are observed in cosmonauts who have made their maiden flights to microgravity.

Ebola hemorrhagic fever: Properties of the pathogen and development of vaccines and chemotherapeutic agents.

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.

Synthesis and antiviral activity of PB1 component of the influenza A RNA polymerase peptide fragments.

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.

Comparative evaluation of effectiveness of IAVchip DNA microarray in influenza A diagnosis.

The paper describes comparative evaluation of IAVchip DNA microarray, reverse transcription PCR (RT-PCR), and real-time RT-PCR versus virus isolation in chicken embryos and shows their diagnostic effectiveness in detection and subtyping of influenza A virus. The tests were evaluated with use of 185 specimens from humans, animals, and birds. IAVchip DNA microarray demonstrates higher diagnostic effectiveness (99.45%) in early influenza A diagnosis as compared to the real-time PCR (98.38%) and RT-PCR (96.22%), thus showing its clear superiority. Diagnostic sensitivity of IAVchip DNA microarray (100%) exceeds the same of RT-PCR (95.95%) and real-time RT-PCR (97.96%) in the range of estimated confidence intervals. IAVchip DNA microarray and real-time RT-PCR displayed equal diagnostic specificity (98.85%), while diagnostic specificity of RT-PCR was 96.40%. IAVchip DNA microarray has an advantage over the other tests for influenza A diagnosis and virus identification as a more rapid method that allows performing simultaneous detection and subtyping of about tens of specimens within one experiment during 8-10 hours. The developed IAVchip DNA microarray is a general test tool that enables identifying simultaneously 16 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes of influenza A virus and also to screen the influenza A viruses from humans, animals, and birds by M and NP genes.

Molecular mechanisms enhancing the proteome of influenza A viruses: an overview of recently discovered proteins.

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.

[Universal diagnostic oligonucleotide microarray for subtyping of human and animal influenza A viruses].

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.

[Relations between CTR1 gene activity and copper status in different rat organs].

CTR1 gene (SLC31A1 according to Entrez data base) product is the main candidate for the role of eukaryotic copper importer, whose tissue-specific function is still unclear. In this research steady state CTR1-mRNA level was measured with semiquantitative RT-PCR analysis and compared with copper status in rat organs, in which copper metabolism is changed during development (liver, cerebellum, choroid plexus and mammary gland). It has been shown that CTR1 gene activity correlates with the rate of both intracellular and extracellular copper-containing enzymes formation. In mesenchymal origin cells of newborns the CTR1 gene activity decreases when high copper concentrations in cell nucleus is reached. According to phylogenetic analysis CTR1 has the most conservative transmembrane domains 2 and 3 (TMD), containing 7 amino acid residues able to coordinate copper atom. A model of cuprophylic channel has been proposed, which is formed by TMD2 and TMD3 in homotrimeric CTR1 complex. In this model copper is transported through the channel to cytosolic C-terminal motif His-Cys-His, which ability to coordinate Cu(I) was assessed by molecular modeling (MM+, ZINDO/1). Theoretical possibility of copper transfer from His-Cys-His CTR1 C-terminal motif to cytosolic Cys-X-X-Cys Cu(I) chaperon sites has been shown. The role of CTR1 in copper metabolism as copper donor and acceptor is discussed.

[Effect of long-term microgravity on the vestibular function].

Comprehensive computerized oculomotor testing was used to investigate the vestibular function in 9 Russian members of ISS crews 3-9 on days 1 (2), 4 (5) and 8 (9) of return from long-term stay in microgravity (126 to 195 days). The vestibular function was assessed by the static otolith-cervical-ocular reflex, dynamic otolith-cervical-ocular reactions, vestibular reactivity, and spontaneous oculomotor activity. The postflight investigations revealed functional disorders in the peripheral (an increased vestibular reactivity, absent or damped otolith-cervical-ocular reflex), and central (spontaneous typical and atypical nystagmus, gaze nystagmus) vestibular analyzer. The pattern and extent of vestibular disorders after long-term exposure in microgravity were individual by character; however, some of the vestibular reactions, including disappearance or considerable damping of the static otolith-cervical-ocular reflex, exaggerated vestibular reactivity and spontaneous eye movements, displayed consistency.