Qualitative real-time RT-PCR assay for nOPV2 poliovirus detection.

Based on the success of the Sabin2-based vaccine, a next-generation nOPV2 poliovirus vaccine has been developed. For epidemic monitoring and conducting epidemiological investigations, it is necessary to have a diagnostic assay with the ability to differentiate this variant from others. Here we describe such a real-time RT-PCR assay. The region with the cre insertion in the 5'-UTR was chosen as the target, and the limit of detection was 103 copies/mL (2.5×103 copies/mL using Probit analysis) determined using armored RNA particles. Sensitivity and specificity were 86.28 - 100 % and 76.84 - 100 %, respectively (with 95 % CI). Thus, this method can be effectively used when it is necessary to make a differential diagnosis of poliovirus strains.

Impact of conjugated polymer addition on the properties of paraffin-asphaltene blends for heat storage applications: Insight from computer modeling and experiment.

Adding carbon nanoparticles into organic phase change materials (PCMs) such as paraffin is a common way to enhance their thermal conductivity and to improve the efficiency of heat storage devices. However, the sedimentation stability of such blends can be low due to aggregation of aromatic carbon nanoparticles in the aliphatic paraffin environment. In this paper, we explore whether this important issue can be resolved by the introduction of a polymer agent such as poly(3-hexylthiophene) (P3HT) into the paraffin-nanoparticle blends: P3HT could ensure the compatibility of aromatic carbon nanoparticles with aliphatic paraffin chains. We employed a combination of experimental and computational approaches to determine the impact of P3HT addition on the properties of organic PCMs composed of paraffin and carbon nanoparticles (asphaltenes). Our findings clearly show an increase in the sedimentation stability of paraffin-asphaltene blends, when P3HT is added, through a decrease in average size of asphaltene aggregates as well as in an increase of the blends' viscosity. We also witness the appearance of the yield strength and gel-like behavior of the mixtures. At the same time, the presence of P3HT in the blends has almost no effect on their thermophysical properties. This implies that all properties of the blends, which are critical for heat storage applications, are well preserved. Thus, we demonstrated that adding polyalkylthiophenes to paraffin-asphaltene mixtures led to significant improvement in the performance characteristics of these systems. Therefore, the polymer additives can serve as promising compatibilizers for organic PCMs composed of paraffins and asphaltenes and other types of carbon nanoparticles.

Current State-of-the-Art and Unresolved Problems in Using Human Induced Pluripotent Stem Cell-Derived Dopamine Neurons for Parkinson's Disease Drug Development.

Human induced pluripotent stem (iPS) cells have the potential to give rise to a new era in Parkinson's disease (PD) research. As a unique source of midbrain dopaminergic (DA) neurons, iPS cells provide unparalleled capabilities for investigating the pathogenesis of PD, the development of novel anti-parkinsonian drugs, and personalized therapy design. Significant progress in developmental biology of midbrain DA neurons laid the foundation for their efficient derivation from iPS cells. The introduction of 3D culture methods to mimic the brain microenvironment further expanded the vast opportunities of iPS cell-based research of the neurodegenerative diseases. However, while the benefits for basic and applied studies provided by iPS cells receive widespread coverage in the current literature, the drawbacks of this model in its current state, and in particular, the aspects of differentiation protocols requiring further refinement are commonly overlooked. This review summarizes the recent data on general and subtype-specific features of midbrain DA neurons and their development. Here, we review the current protocols for derivation of DA neurons from human iPS cells and outline their general weak spots. The associated gaps in the contemporary knowledge are considered and the possible directions for future research that may assist in improving the differentiation conditions and increase the efficiency of using iPS cell-derived neurons for PD drug development are discussed.

Characterization of Motor Activity of Spermatozoa in Adult Progeny of Female Rats with Experimental Type 1 Diabetes Mellitus.

We studied the influence of maternal experimental streptozotocin-induced type 1 diabetes mellitus on motility of spermatozoa in adult progeny. A decrease in the summary count of spermatozoa and changes in their subpopulation composition were revealed. Specifically, the count of nonfertile spermatozoa (immotile and jerking cells) increased, while fertile fraction (progressively motile and low motile cells) decreased. These shifts were responsible for lower index of spermatozoon motility (proportion of fertile to infertile sums of spermatozoa) in the progeny of females with experimental type 1 diabetes mellitus. These results persuasively demonstrated the negative impact of maternal diabetes mellitus on the motor activity of the male germ cells in the progeny under experimental conditions.

The Use of Human Induced Pluripotent Stem Cells for Testing Neuroprotective Activity of Pharmacological Compounds.

Development of therapeutic preparations involves several steps, starting with the synthesis of chemical compounds and testing them in different models for selecting the most effective and safest ones to clinical trials and introduction into medical practice. Cultured animal cells (both primary and transformed) are commonly used as models for compound screening. However, cell models display a number of disadvantages, including insufficient standardization (primary cells) and disruption of cell genotypes (transformed cells). Generation of human induced pluripotent stem cells (IPSCs) offers new possibilities for the development of high-throughput test systems for screening potential therapeutic preparations with different activity spectra. Due to the capacity to differentiate into all cell types of an adult organism, IPSCs are a unique model that allows examining the activity and potential toxicity of tested compounds during the entire differentiation process in vitro. In this work, we demonstrated the efficiency of IPSCs and their neuronal derivatives for selecting substances with the neuroprotective activity using two classes of compounds - melanocortin family peptides and endocannabinoids. None of the tested compounds displayed cyto- or embryotoxicity. Both melanocortin peptides and endocannabinoids exerted neuroprotective effect in the neuronal precursors and IPSC-derived neurons subjected to hydrogen peroxide. The endocannabinoid N-docosahexaenoyl dopamine exhibited the highest neuroprotective effect (~70%) in the differentiated cultures enriched with dopaminergic neurons; the effect of melanocortin Semax was ~40%. The possibility of using other IPSC derivatives for selecting compounds with the neuroprotective activity is discussed.

Expression and Functional Properties of NMDA and GABAA Receptors during Differentiation of Human Induced Pluripotent Stem Cells into Ventral Mesencephalic Neurons.

Ionotropic glutamate and GABA receptors regulate the differentiation and determine the functional properties of mature neurons. Both insufficient and excessive activity of these neurotransmission systems are associated with various nervous system diseases. Our knowledge regarding the expression profiles of these receptors and the mechanisms of their regulation during the differentiation of specialized human neuron subtypes is limited. Here the expression profiles of the NMDA and GABAA receptor subunits were explored during in vitro differentiation of human induced pluripotent stem cells (iPSCs) into ventral mesencephalic neurons. The correlation between the neuronal maturation and the expression dynamics of these genes was investigated, and the functional activity of these receptors was assessed by calcium imaging. The role of NMDA and GABAA receptors in neurite outgrowth and the development of spontaneous activity was analyzed using the viral transduction of neural progenitors with the reporter genes TagGFP and TagRFP. The data indicate that agonists of the investigated receptors can be employed for optimization of existing protocols for neural differentiation of iPSCs, in particular for acceleration of neuronal maturation.

Calcium-Dependent Desensitization of NMDA Receptors.

Glutamate receptors play the key role in excitatory synaptic transmission in the central nervous system (CNS). N-methyl-D-aspartate-activated glutamate receptors (NMDARs) are ion channels permeable to sodium, potassium, and calcium ions that localize to the pre- and postsynaptic membranes, as well as extrasynaptic neuronal membrane. Calcium entry into dendritic spines is essential for long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission. Both LTP and LTD represent morphological and functional changes occurring in the process of memory formation. NMDAR dysfunction is associated with epilepsy, schizophrenia, migraine, dementia, and neurodegenerative diseases. Prolonged activation of extrasynaptic NMDARs causes calcium overload and apoptosis of neurons. Here, we review recent findings on the molecular mechanisms of calcium-dependent NMDAR desensitization that ensures fast modulation of NMDAR conductance in the CNS and limits calcium entry into the cells under pathological conditions. We present the data on molecular determinants related to calcium-dependent NMDAR desensitization and functional interaction of NMDARs with other ion channels and transporters. We also describe association of NMDARs with lipid membrane microdomains.

Flow cytometric HyPer-based assay for hydrogen peroxide.

HyPer is a genetically encoded fluorogenic sensor for hydrogen peroxide which is generally used for the ratiometric imaging of H2O2 fluxes in living cells. Here, we demonstrate the advantages of HyPer-based ratiometric flow cytometry assay for H2O2, by using K562 and human mesenchymal stem cell lines expressing HyPer. We show that flow cytometry analysis is suitable to detect HyPer response to submicromolar concentrations of extracellularly added H2O2 that is much lower than concentrations addressed previously in the other HyPer-based assays (such as cell imaging or fluorimetry). Suggested technique is also much more sensitive to hydrogen peroxide than the widespread flow cytometry assay exploiting H2O2-reactive dye H2DCFDA and, contrary to the H2DCFDA-based assay, can be employed for the kinetic studies of H2O2 utilization by cells, including measurements of the rate constants of H2O2 removal. In addition, flow cytometry multi-parameter ratiometric measurements enable rapid and high-throughput detection of endogenously generated H2O2 in different subpopulations of HyPer-expressing cells. To sum up, HyPer can be used in multi-parameter flow cytometry studies as a highly sensitive indicator of intracellular H2O2.

Effect of Nerve Growth Factor on Neural Differentiation of Mouse Embryonic Stem Cells.

The cholinergic, GABAergic, and catecholaminergic neurons derived from mouse embryonic stem cells in a culture medium supplemented with recombinant NGF were phenotyped and scored. NGF stimulated generation of neurons, but not neuronal progenitors from embryonic stem cells and affected the proportion of specific types of neurons in cultures of differentiating embryonic stem cells. These findings open vista to employ NGF for generation of specific neuron types from embryonic stem cells for fundamental and toxicological studies.

The Transcriptional Changes of trim Genes Associated with Parkinson's Disease on a Model of Human Induced Pluripotent Stem Cells.

Over the last few years, in vitro models, based on patient-derived induced pluripotent stem cells (iPSCs), have received considerable attention for modeling different neurodegenerative disorders. Using this model, we analyzed transcription of 15 tripartite motif (trim) genes in iPSCs, derived from the different groups: Parkinson's disease (PD) patients bearing mutations in different genes, patient with the sporadic form of PD, and the healthy individuals. The transcription was observed during neuronal differentiation of the cells in vitro into neuronal stem cells and terminally differentiated neurons. The transcription of over 50 % of these genes, belonging to different sub-groups of the TRIM family, varied between PD patients and healthy individuals during the reprogramming of fibroblasts into iPSCs and the following neuronal differentiation. Moreover, the transcription of the trim6 and trim24 genes was different between cells, derived from PD patients, and control cells at all stages. The transcription of the four trim genes (trim5α, 26, 27, 31) remained unchanged during almost all investigated stages, compared with the controls. We suppose that the revealed changes in the transcription of several trim genes reflect their possible role in neurodegenerative processes at the early stages of PD. These genes may act as a gear unit between the PD progression and the deregulation of the immune system.

Investigation of the effects of GABA receptor agonists in the differentiation of human induced pluripotent stem cells into dopaminergic neurons.

The influence of GABA receptor agonists on the terminal differentiation in vitro of dopaminergic (DA) neurons derived from IPS cells was investigated. GABA-A agonist muscimol induced transient elevation of intracellular Ca2+ level ([Ca2+] i ) in the investigated cells at days 5 to 21 of differentiation. Differentiation of cells in the presence of muscimol reduced tyrosine hydroxylase expression. Thus, the presence of active GABA-A receptors, associated with phenotype determination via Ca2+-signalling was demonstrated in differentiating human DA neurons.

Downregulation of Purkinje Cell Activity by Modulators of Small Conductance Calcium-Activated Potassium Channels In Rat Cerebellum.

Small-conductance calcium-activated potassium channels (SK channels) are widely expressed in CNS tissues. Their functions, however, have not been well studied. Participation of SK channels in Purkinje cell (PC) pacemaker activity has been studied predominantly in vitro. Here we studied for the first time the effects of SK channel activation by NS309 or CyPPA on the PC simple spike frequency in vivo in adult (3 - 6 months) and aged (22 - 28 months) rats using extracellular microelectrode recordings. Both pharmacological agents caused a statistically significant decrease in the PC simple spike frequency. The maximum value of the decrease in the simple spike frequency did not depend on age, whereas a statistically significant inhibition of the spike frequency was achieved faster in aged animals than in adult ones. In experiments on cultured neurons PCs were identified by the expression of calbindin as the PC-specific marker. Registration of transmembrane currents in cerebellar neurons revealed the direct action of NS309 and CyPPA on the SK channels of PC consisted in the enhancement of outward potassium currents and action potential after-hyperpolarization. Thus, SK channel activators can compensate for age-related changes of the autorhythmic functions of the cerebellum.

[HOMOCYSTEINE-INDUCED MEMBRANE CURRENTS, CALCIUM RESPONSES AND CHANGES OF MITOCHONDRIAL POTENTIAL IN RAT CORTICAL NEURONS].

Homocysteine, a sulfur-containing amino acid, exhibits neurotoxic effects and is involved in the pathogenesis of several major neurodegenerative disorders. In contrast to well studied excitoxicity of glutamate, the mechanism of homocysteine neurotoxicity is not clearly understood. By using whole-cell patch-clamp, calcium imaging (fluo-3) and measurements of mitochondrial membrane potential (rhodamine 123) we studied transmembrane currents, calcium signals and changes in mitochondrial membrane potential induced by homocysteine versus responses induced by NMDA and glutamate in cultured rat cortical neurons. L-homocysteine (50 µM) induced inward currents that could be completely blocked by the selective antagonist of NMDA receptors - AP-5. In contrast to NMDA-induced currents, homocysteine-induced currents had a smaller steady-state amplitude. Comparison of calcium responses to homocysteine, NMDA or glutamate demonstrated that in all cortical neurons homocysteine elicited short, oscillatory-type calcium responses, whereas NMDA or glutamate induced sustained increase of intracellular calcium. Analysis of mitochondrial changes demonstrated that in contrast to NMDA homocysteine did not cause a drop of mitochondrial membrane potential at the early stages of action. However, after its long-term action, as in the case of NMDA and glutamate, the changes in mitochondrial membrane potential were comparable with the full drop of respiratory chain induced by protonophore FCCP. Our data suggest that in cultured rat cortical neuron homocysteine at the first stages of action induces neurotoxic effects through activation of NMDA-type ionotropic glutamate receptors with strong calcium influx through the channels of these receptors. The long-term action of homocysteine may lead to mitochondrial disfuction and appears as a drop of mitochondrial membrane potential.

[The effect of modulators of SK channels on simple spike firing frequency in the discharge of the cerebellar Purkinje cells in laboratory mice].

The effect of CyPPA, a positive modulator of small conductance calcium-activated potassium channels of type 3 and 2 (SK3/SK2), and of NS309, an activator of intermediate and small conductance calcium-activated potassium channels (IK/SK), on the activity of cerebellar Purkinje cells was studied in 2-month-old male mice. The use of 1 mM of CyPPA has led to a decrease of simple spike firing frequency in the discharge of Purkinje cells by 25%, on average, during 1 h after application. At the same time, application of 100 µM of NS309 has promoted a decrease in simple spike firing frequency by 47 %, on average, during 1 h after the beginning of the action. The obtained results confirm the hypothesis that SK channels participate in regulation of simple spike firing frequency in the discharge of Purkinje cells and are responsible for restriction of signal frequency. The effect of NS309 on simple spike firing frequency was more pronounced; therefore, the IK/SK channels may be suggested to play the cardinal role in regulation of spike activity of Purkinje cells. Since increasing simple spike frequency in the discharge of Purkinje cells is observed at many disturbances of motor activity, in particular, at spinocerebellar ataxia, it can be suggested that the studied compounds or substances of similar action are of interest as potential medicinal agents.

[Obtainment of chimeric blastocysts of mice by methods of laser nanosurgery].

The procedure of obtainment of chimeric blastocysts of mice by laser nanosurgery methods without using any other techniques is described. To perform the experiments, a special laser micromanipulator was invented. The murine embryonic stem cells (ESC), which were transformed with pEF-GFP vector, encoding the green fluorescent protein, were used in the experiments. ESC were introduced into the perivitelline space of murine embryos at the stage of 8 cells using the laser micromanipulator. The operated embryos were cultured in vitro until the stage of emergence from zona pellucida. The fluorescence and its precise localization were registered using a confocal microscope. It was shown for the first time that the inclusions of ESC introduced with the lased micromanipulator were found not only in the inner cell mass (ICM) but also in the trophectoderm of the chimeric blastocyst. The technology of nanosurgical operations at early stage preimplanted mammalian embryos using laser techniques opens great opportunities not only for solution of fundamental tasks of experimental embryology of mammals but also for obtainment of chimeric and transgenic animals with predetermined genotype.

[The features of postsynaptic currents in primary culture of rat cortical neurons].

The generation features of postsynaptic currents were studied in primary culture of cortical neurons at 7-20 days in vitro (DIV). The use of specific blockers of postsynaptic ion channels after 10 DIV revealed all types of electrical activity found in adult cortex including miniature inhibitory (mIPSCs), excitatory (mEPSCs) and spontaneous giant excitatory currents and spikes. The frequency of mEPSCs increased exponentially from 7 to 20 DIV doubling every 2.2 days in parallel with changes in action potentials generation. The mEPSCs generated by NMDA and AMPA or by only AMPA receptor activation were found. The inhibition of NMDA receptors by magnesium ions or AP5 were shown to modulate the frequency and amplitude of mEPSCs, which differ primary culture from brain slices possibly because of the lack of glial control of synaptic transmission.

[Quaternary structure formation by recombinant analogues of spider silk].

A study has been conducted on the morphology of artificial spider silk fibers, prepared from recombinant analogues of spiridons 1 and 2. It has been shown that by stretching out the "as spun" fiber, a reorganization of its spongy matrix occurs, which leads to the formation of microfibrills, followed by a reduction of the diameter of the fiber. The durability of an artificial fiber depends on the degree of stretching and on the substructure of the microfibrills. The model process of artificial fibers preparation reproduces to the great detail the natural process of spider web spinning. Future applications of this model include production of biomaterials with unique properties.

Apoptosis and the receptor specificity of its mechanisms during the neurotoxic action of glutamate.

The ratio of necrosis to apoptosis and the mechanisms of apoptosis were studied during neurodegeneration induced by glutamate and selective agonists of glutamate receptors - N-methyl-D-aspartate (NMDA) and kainate. Experiments were performed on primary cultures (seven days in vitro) of rat cerebral cortex neurons. Apoptosis and necrosis were identified using a vital fluorescence rapid test with staining with acridine orange and ethidium bromide. Immunocytochemistry in combination with confocal microscopy was used to visualize apoptotic proteins. Agonists (240 min) caused neuron death via both processes, though the proportion of necrotic cells when neurodegeneration was induced by NMDA and kainate was significantly less than when neurodegeneration was induced with glutamate. The neurotoxic effect of 3 mM glutamate was mediated via alpha-amino-3-(3-hydroxy-5-methylisoxazole-4-yl)propionate (AMPA) and kainate receptors, as it was blocked by 6-cyano-7-nitroquinoxalin-2,3-dione (CNQX). Activation of NMDA receptors led to the development of apoptosis without involvement of caspases, due to the direct action of apoptosis-inducing factor (AIF) on neuron nuclei. Activation of AMPA-kainate receptors was accompanied by the development of apoptosis via the caspase-dependent pathway. Thus, these data identified the receptor dependence of the mechanisms of apoptosis during the neurotoxic action of glutamate.

[Apoptosis and its receptor selective pathways during neurotoxic action of glutamate].

A contribution of necrosis and apoptotis as well as the particular apoptosis pathways in neuro-degeneration induced by glutamate and selective glutamate receptor agonists, NMDA and kainate, were studied. In experiments on primary neuron cultures of 7 days in vitro from embryonic rat cortex, the necrosis and apoptosis were recognized using vital fluorescence acridine orange and ethidium bromide staining. Immunostaining was used to visualize apoptotic peptides such as P53, Cas-3 and AIF. Death of neurons occurred by both necrosis and apoptosis following 240 min 3 mM glutamate, 30 microM NMDA and 30 microM kainate exposure. Quantities of necrotic neurons in the presence of NMDA and kainate were substantially reduced when compared to the glutamate action. The glutamate effects were realized through predominant activation of AMPA- and kainate receptors, since it could be greatly suppressed by 30 microM CNQX. AIF but not Cas-3, was found in a large amount of neurons when apoptosis was evoked by the selective NMDA receptor activation. On the contrary, during apoptosis induced by glutamate and kainate, many cells contained Cas-3 in nuclei rather than the AIF. The data suggest that apoptosis induced by the NMDA receptor activation develops through the caspase-3-independent pathway that involves direct AIF accumulation in nuclei. The AMPA/kainate receptor mediated apoptosis includes the caspase-3-dependent mechanism.