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The effect of transtraumatic epidural electrostimulation (TEES) above (T5) and below (L2) spinal cord injury in the lower thoracic region (T8-T9) in combination with treadmill exercise in pigs was evaluated using electrophysiological examination methods and behavioral tests. Two weeks after spinal cord injury, motor evoked potentials of m. soleus were recorded during electrostimulation at the level of T5 and L2 segments, which indicated activation of spinal cord structures above and below the focus of injury. After 6 weeks of TEES in combination with physical training, restoration of the characteristics of M-response and H-reflex of the soleus muscle in response to stimulation of the sciatic nerve, improvement of joint mobility, and appearance of voluntary motor activity in the hindlimbs were observed. Neuromodulation with TEES had been proven to be an effective way to stimulate posttraumatic spinal cord regeneration and can be used in the development of a neurorehabilitation protocol for patients with spinal cord injury. [ABSTRACT FROM AUTHOR]

The development of hypogravitational motor syndrome is an essential negative consequence of weightlessness for humans; an important role in the pathogenesis of this syndrome is played by changes in axons of the spinal tracts. Myelinated fibers and transcriptome of the spinal cord were studied in mice exposed to hypogravity during a 30-day flight on a biosatellite. Morphometric analysis of myelinated fibers of the spinal tracts showed a decrease in the thickness of the myelin sheath. Analysis of spinal cord transcriptome revealed a decrease in the expression of genes involved in the myelination of nerve fibers. These results suggest that the processes of nerve fiber myelination are involved in the development of the hypogravitational motor syndrome under weightless conditions; the 7-day readaptation period was found to be insufficient for reversion of the negative changes in the myelinated fibers of the spinal cord. [ABSTRACT FROM AUTHOR]

The data obtained by transcriptome analysis of lumbar spinal cord segments, sciatic nerve, and the respiratory diaphragm of the mice performed after a space flight on board Bion-M1 biosatellite were processed by bioinformatic methods aimed at elucidation of the regularities in hypogravity-induced transcriptome changes in various compartments of motor neurons. The study revealed abnormalities of axonal transport in spinal motor neurons provoked by weightlessness. These data agree with the results of electron microscopy examination of the spinal cord in experimental animals. In space group mice sacrificed on the landing day, the content of perinuclear ribosomes in lumbar motoneurons surpassed that in control mice or in the recovery group examined 1 week after the flight. The data corroborate our hypothesis on contribution of axonal transport disturbances into pathogenesis of hypogravity motor syndrome. They can be employed as a launching pad for further study of hypogravity-triggered motor disorder mechanisms in order to elaborate the preventive therapy against the development of hypogravity motor syndrome in space flights. [ABSTRACT FROM AUTHOR]

Abstract—The effects of ATP and adenosine on the parameters of the end plate currents of the frog's Rana ridibunda neuromuscular synapse in the presence of cesium ions that modulate synaptic transmission were studied to identify the involvement of K+ channels in the mechanism of inhibitory presynaptic action of purine derivatives in the neuromuscular synapse of cold-blooded animals. There was a difference between the effects caused by a half-hour and one-hour action of cesium ions on the amplitude of the terminal plate currents; similar difference we noted previously in the effects of barium ions, which are blockers of some subtypes of potassium channels. In the case of exposure to cesium for 1 h, the inhibitory effect of adenosine on the amplitude of the terminal plate currents remained stable; while the inhibitory effect of ATP on the amplitude of postsynaptic responses decreased by approximately 2.5 times. The data obtained may indicate that the presynaptic inhibitory effect of ATP on the secretion of the transmitter from nerve endings can be realized through Cs+-sensitive potassium channels of the nerve terminals. [ABSTRACT FROM AUTHOR]

Objectives. To study the structure and biomechanical characteristics of blood neutrophils on the background of exposure to titanium dioxide nanoparticles. Materials and methods. Blood neutrophils from 20 essentially healthy donors of both sexes aged 20–22 years were studied in vitro before and after exposure to titanium dioxide nanoparticles. Atomic force microscopy was used to measure neutrophil diameter and height, and the biomechanical properties of neutrophils (roughness and rigidity) were also studied. Results. Exposure to titanium dioxide nanoparticles was followed by decreases in the diameter, increases in the height, and increases in the rigidity of neutrophils, as well as growth in surface roughness. Conclusions. Changes in the structural-functional properties of neutrophils provide evidence of the possible cytotoxic actions of titanium dioxide nanoparticles. [ABSTRACT FROM AUTHOR]

We studied immunohistochemical and morphometric characteristics of the spermatogenic epithelium in rats against the background of peroral administration of nanoparticles containing titanium dioxide. Substantial degenerative changes in the spermatogenic epithelium were revealed: thinning, disorganization of layers, and detachment of sperm cells from the basement membrane. Immunohistochemical analysis revealed reduced proliferative activity and differentiation potential of epithelial cells, which was confirmed by changes in the expression of Ki-67 and c-kit markers. Our data attest to unfavorable effects of titanium dioxide nanoparticles on the structural and functional characteristics of the reproductive system in male rats leading to spermatogenesis disturbances. [ABSTRACT FROM AUTHOR]

In this work the reactive changes in rat hippocampus in response to intranasal administration of TiO2 nanoparticles (NPs) have been studied. The immunohistochemistry of animal hippocampi has shown an increase in the sensitivity of vascular endotheliocytes and macroglia to the vascular endothelial growth factor (VEGF) in hippocampi of the experimental group. The expression of the glial fibrillary acidic protein (GFAP) has been found to enhance, suggesting the increment of the reactive astrocytes amount in the studied brain area under the action of TiO2 NPs. According to the results of this research, we have deduced the compensatory reactions in hippocampus accompanied by astrocytic activation, processes of angiogenesis, and the impairment of neurogliar ratio under the action of TiO2 NPs. [ABSTRACT FROM AUTHOR]

In a spherically symmetric self-consistent approach (SSSA), the spin-1/2 J- J Heisenberg model on a two-dimensional square lattice is considered for two-time retarded spin-spin Green's functions. The spin excitation spectrum, ω( q), and spin gaps at symmetric points are obtained for the entire J- J diagram, i.e., for any ϕ, J = cosϕ, and J = sinϕ. The structure factor c and the correlation length ξ at finite temperature are calculated in the entire range of parameters. A radical difference in the behavior of the system in the upper, frustrated (0 ⩽ ϕ ⩽ π), and the lower, nonfrustrated (π ⩽ ϕ ⩽ 2π), regions of the diagram is demonstrated. In the latter region, there is a first-order phase transition that is unique on the phase diagram. For a weakly frustrated antiferromagnet ( J > J > 0), the results obtained are compared with the experimental dependence of ξ on temperature and doping level. A correspondence rule is proposed between frustration in a spin model and the doping of an antiferromagnet with holes. [ABSTRACT FROM AUTHOR]

The results of axonal regeneration in peripheral nerves and of the modulating effect of estrogens on the posttraumatic plasticity of motor neurons through the classical and alternative genomic mechanisms involving the activation of estrogen receptors ERα and ERβ and increased transcription of specific neuroprotective control genes. New mechanisms of the neuroprotective effect of estrogens related to the cross interaction of estrogens with intracellular signaling cascades of many other biologically active compounds, in particular, vascular endothelial growth factor and endothelin, are proposed. [ABSTRACT FROM AUTHOR]

Immunohistochemical study with monoclonal antibodies against fast myosin heavy chains showed that excision of a fragment of sciatic nerve does not change, while compression of the nerve decreased the relative content of fast muscle fibers in rat soleus muscle. The content of fast fibers in the muscles of contralateral limbs decreased in both models of denervation. Hence, contralateral limbs cannot be used as the control in experiments with disturbed neurotrophic function. Possible mechanisms underlying changes in the immunohistochemical profiles of experimental and contralateral limbs are discussed. [ABSTRACT FROM AUTHOR]

Immunohistochemical study with monoclonal antibodies to fast myosin heavy chains shows that physiological doses of dexamethasone do not affect the immunohistochemical profile of fast musculus plantaris and slow musculus soleus in guinea pig. Dexamethasone induces de novo formation of fast muscle fibers in denervated slow muscle and does not prevent expression of fast myosin after blockade of axonal transport. [ABSTRACT FROM AUTHOR]

Histochemical methods demonstrated that injection of the anabolic steroid phenobolin and exercise did not modify the content of fast and slow muscle fibers in the slow ( m. soleus) and fast ( m. plantaris and m. semimembranosus) muscles. Energy metabolism changed only in the fast muscles. After exercise the number of oxidative muscle fibers increased in both fast muscles and after injection of anabolic steroids in m. semimem-branosus. Combined exposure produced an additive effect. The content of glycolytic muscle fibers in m. plantaris increased under the effect of anabolic steroids. [ABSTRACT FROM AUTHOR]

The possible role of pulsed motoneuron activity in the regulation of the qualitative composition of the guinea pig slow skeletal muscle myosins is studied by immunohistochemical methods using monoclonal antibodies to the fast myosin heavy chains. Guinea pig intact musculus soleus contains only the slow muscle fibers. Blockade of axon transport by colchicine application on the sciatic nerve during intact pulsation leads to the expression of fast myosin. Tenotomy simultaneous with the axon transport blockade prevents the appearance of the fast muscle fibers. Our results indicate that pulsed activity of motoneuron as a factor of neurotrophic control regulates the qualitative composition of myosins, thus supporting the functional activity of the muscle. [ABSTRACT FROM AUTHOR]