Interaction of corundum and quartz nanocrystals with erythrocyte membranes

Mechanisms of interaction of quartz and corundum nanocrystals with erythrocyte membranes were studied by means of atomic force microscopy and fluorescence analysis. Hydrophobic, chemically inert nanocrystals larger than a critical size (20–25 nm) can bind to erythrocyte membranes without damaging them. If the size of the nanocrystals is less than 15 nm, they can penetrate into the lipid bilayer membranes. This decreases the membrane microviscosity, and pores appear, which leads to cell lysis. A thermodynamic explication of the critical size of the nanocrystals is given.     

Molecular and genetic analysis of NS gene from high pathogenic strains of the avian influenza (H5N1) virus isolated in Kazakhstan

The high pathogenic strains of the avian influenza H5N1 virus isolated in Kazakhstan have NS of different genotypes. The influenza virus strains isolated in 2005 is of NS1E Qinghai genotype. A/swan/Mangystau/3/2006 strain is of NS2A genotype that is typical for Gs/Gd-like strains. The results of the analysis allow assuming that A/swan/Mangystau/3/2006 strain has been brought onto the territory of Kazakhstan from the European part of the continent along the Black Sea-Mediterranean flyway.     

Measurement and Correction of Microscopic Head Motion during Magnetic Resonance Imaging of the Brain

Magnetic resonance imaging (MRI) is a widely used method for non-invasive study of the structure and function of the human brain. Increasing magnetic field strengths enable higher resolution imaging; however, long scan times and high motion sensitivity mean that image quality is often limited by the involuntary motion of the subject. Prospective motion correction is a technique that addresses this problem by tracking head motion and continuously updating the imaging pulse sequence, locking the imaging volume position and orientation relative to the moving brain. The accuracy and precision of current MR-compatible tracking systems and navigator methods allows the quantification and correction of large-scale motion, but not the correction of very small involuntary movements in six degrees of freedom. In this work, we present an MR-compatible tracking system comprising a single camera and a single 15 mm marker that provides tracking precision in the order of 10 m and 0.01 degrees. We show preliminary results, which indicate that when used for prospective motion correction, the system enables improvement in image quality at both 3 T and 7 T, even in experienced and cooperative subjects trained to remain motionless during imaging. We also report direct observation and quantification of the mechanical ballistocardiogram (BCG) during simultaneous MR imaging. This is particularly apparent in the head-feet direction, with a peak-to-peak displacement of 140 m.     

Ferroptosis: an iron-dependent form of nonapoptotic cell death

Nonapoptotic forms of cell death may facilitate the selective elimination of some tumor cells or be activated in specific pathological states. The oncogenic RAS-selective lethal small molecule erastin triggers a unique iron-dependent form of nonapoptotic cell death that we term ferroptosis. Ferroptosis is dependent upon intracellular iron, but not other metals, and is morphologically, biochemically, and genetically distinct from apoptosis, necrosis, and autophagy. We identify the small molecule ferrostatin-1 as a potent inhibitor of ferroptosis in cancer cells and glutamate-induced cell death in organotypic rat brain slices, suggesting similarities between these two processes. Indeed, erastin, like glutamate, inhibits cystine uptake by the cystine/glutamate antiporter (system x(c)(-)), creating a void in the antioxidant defenses of the cell and ultimately leading to iron-dependent, oxidative death. Thus, activation of ferroptosis results in the nonapoptotic destruction of certain cancer cells, whereas inhibition of this process may protect organisms from neurodegeneration.     

Classification and function of GABAergic interneurons of the mammalian cerebral cortex

GABAergic interneurons make up about 20% of neurons in the cortex and are a heterogeneous group of cells. In recent years it has become clear that different populations of interneurons not only provide the balance of excitation and inhibition in neural networks but are also critically important for generation of rhythmic activity, successful processing of sensory information, implementation of synaptic plasticity and a number of other functions. We examine current approaches to classification of interneurons and review the properties and the functional role of basket cells, chandelier cells, neurogliaform interneurons, Martinotti cells, and some other classes of interneurons based on morphological, immunohistochemical, electrophysiological and optogenetic studies. Besides, we consider the opportunities of the selective impact on target population of interneurons and review the data on the role of different types of interneurons in the pathogenesis of epilepsy and schizophrenia.     

Analysis of interaction of bacterial cells and bacteriophages in conducting suspensions with an acoustic sensor

The possibility of analyzing bacterial cells infected by a specific bacteriophage, using Escherichia coli as an example, with an acoustic sensor directly in suspensions with different initial electrical conductivities was studied. The analysis was based on measurement of the time dependence of phase and the complete loss of output sensor signals of fixed frequency before and after biological interaction of microbial cells and bacteriophages. The aforementioned sensor makes it possible to detect bacterial cells and assess their viability in conducting suspensions. It was shown that the conductivity of the buffer solution should not exceed 10 μS/cm and the minimum detectable concentration of microbial cells was ~10⁴ cells/mL.     

Status epilepticus impairs synaptic plasticity in rat hippocampus and is followed by changes in expression of NMDA receptors

Cognitive deficits and memory loss are frequent in patients with temporal lobe epilepsy. Persistent changes in synaptic efficacy are considered as a cellular substrate underlying memory processes. Electrophysiological studies have shown that the properties of short-term and long-term synaptic plasticity in the cortex and hippocampus may undergo substantial changes after seizures. However, the neural mechanisms responsible for these changes are not clear. In this study, we investigated the properties of short-term and long-term synaptic plasticity in rat hippocampal slices 24 h after pentylenetetrazole (PTZ)-induced status epilepticus. We found that the induction of long-term potentiation (LTP) in CA1 pyramidal cells is reduced compared to the control, while short-term facilitation is increased. The experimental results do not support the hypothesis that status epilepticus leads to background potentiation of hippocampal synapses and further LTP induction becomes weaker due to occlusion, as the dependence of synaptic responses on the strength of input stimulation was not different in the control and experimental animals. The decrease in LTP can be caused by impairment of molecular mechanisms of neuronal plasticity, including those associated with NMDA receptors and/or changes in their subunit composition. Realtime PCR demonstrated significant increases in the expression of GluN1 and GluN2A subunits 3 h after PTZ-induced status epilepticus. The overexpression of obligate GluN1 subunit suggests an increase in the total number of NMDA receptors in the hippocampus. A 3-fold increase in the expression of the GluN2B subunit observed 24 h after PTZ-induced status epilepticus might be indicative of an increase in the proportion of GluN2B-containing NMDA receptors. Increased expression of the GluN2B subunit may be a cause for reducing the magnitude of LTP at hippocampal synapses after status epilepticus.