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O S Sotnikov

Publications and source records attributed to O S Sotnikov.

At least 19 recordsLinked to original sources
PubMed2003

[Effect of the antibodies to gangliosides on the Retzius neuron electrical activity and the functional activity of sodium channels for incoming current in leech].

In the present study, the effect of antibodies to gangliosides on the Retzius neurons of the leech was investigated to study the spike activity and the functional activity of the Na-channels which generate the spike. A forty-minute incubation of the Retzius neurons in a 20% solution of antiganglioside serum in a Ringer solution provoked appearance of a double spike (a spike with two parts) connected with a decrease of the speed of the activation of the tetrodotoxin (TTX)-sensitive Nachannels. The high frequency synaptic activation of the neuron (10 Hz during 10 minutes) under the plasticity exchange of the gate system of the TTX-sensitive Na-channels. As a result of this, there was a disturbance of the habituation of the Retzius neuron to the high-frequency stimulation.

Action Potentials↗
PubMed2003

[Unmyelinated nerve fibers].

The paper presents a critical review of various current concepts of the structure and kinetics of unmyelinated nerve fiber. A classification of nerve fibers, different from the earlier ones, is proposed, that demonstrates not only the morphological fiber types, but also the kinetics of their reversible transition stages from non-glial to myelinated fiber. Evidence is presented to show the erroneousness of conceptions, still appearing in many publications, that consider the unmyelinated nerve fiber as "the Remak's cable type fiber". According to the current data, "Remak's fiber" is a glial-neurite complex, i.e. a bundle of unmyelinated nerve fibers covered with a single glial cell. Using the electron microscope, it was demonstrated that comparable glial-neurite complexes of myelinated nerve fibers, formed in CNS in a similar way by a single oligodendrocyte, cannot be named a single fiber. Cutting the nerves makes visible that the single fibers forming "the Remak's fiber" stem from different cells, therefore they cannot be a single "fiber". It has been shown for the first time experimentally, that in extreme situations, as a result of contraction of gliocyte processes, unmyelinated fibers may "leave" the glial-neurite complexes and become the nonglial fibers. Some data are presented that may serve as criteria for differentiation of unmyelinated fiber with a stratified sheath from developing myelinated fiber.

Animals↗
PubMed2002

[Axonal reaction precedes demyelination in experimental models of multiple sclerosis].

Taking into consideration that myelin phospholipids may be partially synthesized in neuronal bodies, while neurilemma readily reacts with antibodies against gangliosides by changing the properties of membrane ionic channels, the attempt was made to test the proposed assumption of the early axonal reaction in demyelinating processes in experimental models of multiple sclerosis. The models of chronic allergic encephalomyelitis in Lewis rats injected with homogenate of highly purified myelin or total brain gangliosides were used. First signs of demyelination (the destruction of intermediate dense lines) were demonstrated in the inner layers of myelin close to axon and were shown to develop synchronously with the aggregation of filamentous-tubular material in the neuroplasm. These changes are associated with significant shift of the ratio of myelin sheath thickness to axonal diameter (from 1:7-1:3 to 2:1-3:1). This swelling of myelin seems to be caused by neuroplasmic proteins aggregation, that must be accompanied by the drop in oncotic pressure and the separation of loosely-bound water fraction that may be assimilated by myelin. At light microscopic level the increase of myelin thickness is clearly observed that is in exact correspondence with the decrease in axonal diameter. The process starts with the exfoliation and swelling of the nodes of Ranvier and the incisures of myelin, which fuse after elongation, that corresponds to the total disintegration of myelin with the preservation of continuity of axon which appears to be harshly shrunken.

Animals↗
PubMed2001

[Neuron non-electrical functions].

Classical histological preparations of the metasympathetic nervous system treated with silver salts were compared with isolated neuron cultures to study non-electrical functions of the neurons. A hypothesis of a tissue trophic effect of the nervous tissue's receptors, is advanced. Proteolytic enzymes were shown to be a growth factor for surrounding tissues and to play a role of trophic agents. A permanent restructurisation seems to occur in formed plexuses of adult healthy animals.

Afferent Pathways↗
PubMed2001

[Structural organization of the acellular region of the sinoauricular nerve plexus in the dog heart at maximal motor activity].

The reactions of the dog sinoatrial node artery under hypo- and hyperkinesia were revealed by the serial semi-thin section morphometric analysis. Single maximal physical load may be a cause of significant changes in the main source of blood supply of the dog heart sinoauricular region. During 4 weeks period hypokinezia leads to decrease of structural and functional reserve of the artery. The following physical load causes acute reduction of the blood volume in the region of the right atrium of the heart. The individual peculiarities of the artery adaptive reactions are determined by the level of the heart functional activity and by the cardiac muscle metabolism, which should be taken into account when using maximal physical loads in clinic and in experimental studies.

Animals↗
PubMed2000

[Innervation of the humerus metaepiphysis in newborn and one year old children].

Analysis of home and foreign literature on metaepiphyseal cartilage innervation and blood supply was presented, data on these organ diseases substantiate theoretical and clinical significance of the study was performed. Using macro-microscopic preparation, histological study, automatic image analyzer branches of humerus proximal metaepiphysis were shown to originate from axillary and subscapulary nerves. Nerves and vessels penetrating in the cartilaginous canals form neurovascular complexes. Cartilaginous canals are located unevenly. Nervous structures were found in the canals and their characteristics was given.

Growth Plate↗
PubMed2000

[Quantitative analysis of morphogenesis of local nerve plexuses forming in tissue culture].

Discrete stages of formation of nervous plexuses in the culture of isolated neurons of a mollusc were analyzed autonomically. Area of plexus expansion (S1) and area, occupied by nerve structures (neurites and neuron bodies) were determined. It was demonstrated that despite intensive radial growth of peripheral neurites and S1 growth the density of plexus (S2/S1) was not changed. Relative acceleration of plexus expansion (as compared to S2 growth) registered on 40th and 50th hrs of cultivation indicates the absence of necessary cells in the plexus and development of contacts with adjacent local plexuses. Scanning of lamellar structures revealed submembranous aggregation of cytoskeleton apart from longitudinally directed cytoskeletal bands, which prevents one of the ways of neurite ramification. Elimination of lamellae between cytoskeletal bundles leads to formation of several neurites.

Animals↗
PubMed1999

[Morphogenesis of neuronal systems in tissue culture repeats the evolution of simpler nervous systems].

Comparison of simpler nervous systems of invertebrates and plexiganglionic systems cultivated in tissue culture was conducted for the first time. Their principal resemblance was discovered. By following up the kinetics of neuronal behaviour in culture similarity between mechanisms underlying the evolution of simpler nervous systems and processes of self assembly of neuronal systems was revealed. In both cases isolated nerve cells are replaced by primitive (archaic) nervous plexus that, in turn, becomes a plexiganglionic neuronal system. Final individual architecture of ganglia and mechanisms of formation of nerve ganglia and trunks coincide. Highly specialized unipolar neurons transform into archaic unipolar cells and display signs of chemotaxis. Resemblance of stages and mechanisms of the formation of all elementary nervous systems and neuronal systems in culture is explained by integrity of the neuron properties (adhesion and mobility of neuron bodies, extrusion and retraction of their processes and autotomy of nerve endings). Similar neuron potentialities in evolution and tissue culture underly the abundance of parallelisms between nervous systems in animals of unrelated phyla. In this aspect a possibility appeared to formulate another biogenetic postulate concerning general mechanisms of neurogenesis: morphogenesis of plexiganglionic neuronal systems in tissue culture represents fast and simplified repetition of the evolution of elementary nervous system of invertebrates.

Animals↗
PubMed1998

Kinetics of the structure of neurites in mollusk brain after its dissociation.

Using phase microscopy the behaviour of living neurons directly after their enzymatic isolation from ganglia of Clione limacina and Lymnaea stagnalis was studied. Apart from single-processed unipolar neurons, numerous dipolar and unipolar ones were found in mollusc which does not conform to neuron classification generally adopted. Disrupted neurons were seen to shorten gradually in Ringer solution and -1640 medium at the rate of 0.84-0.27 mm min. Serial photomicrography revealed that the process has two stages. Neurite retraction is interrupted by the expansion stage (extrusion and urgent regeneration). Duration of retraction and extrusion stages made 22.7-3.3 and 6.6-9.1 min respectively. Retraction speed was 24-0.5 mm/min while that of extrusion was 2.8-0.4 mm/min. different processes of the same neuron contract asynchronously. Process invagination leads to its rounding. Thus the cell acquires most thermodynamically stable from which is arranged to prompt its survival. Spherical neurons lacking processes migrate and demonstrate capacity of regeneration. As the conditions somehow resembling the experimental ones (high proteolytic activity of the medium and process loss in part of neurons) arise in cerebral trauma nidus of it is suggested that viable neuron behaviour is alike in this situation.

Animals↗
PubMed1996

[The intramural neural apparatus of the mesenteric lymphangion of the small intestine].

Concentration of nerve structures in the lymphangion wall directly correlates with myocyte number in its different regions. Maximal adrenergic and cholinergic fibres concentration was defined in valvular torus muscular cuff of the lymphangion and minimal--in the valvular sinus wall. Besides, as structural organization of adrenergic plexus does not differ from that of antichollinaestherase-positive one and electron microscopic photos display diverse cholinergic and monoaminergic mediator vesicles in same fibres a suggestion is made on the mixed mediator nature of intramural plexuses of the lymphangion.

Acetylcholinesterase↗
PubMed1992

Brain neurite-stimulating protein promotes formation of mechanosensory endings in sensory neuron.

In the present study we have shown that in the organotypic culture of dorsal root ganglia (DRG) of 10-11 day-old chick embryos, the neurite-stimulating protein (NSP) from bovine brain promotes the development of branching mechanosensory endings. The light and electron microscopic observation revealed that the morphological features of these sensory endings are similar to those in vivo. A mechanical stimulation of these endings elicited bursts of impulses in the sensory neurons.

Animals↗
PubMed1991

[The autotomy process of the microcirculatory bed receptors].

Autotomy of receptors' endings in the intestine's microvascular bed was shown to entail a real breaking off of the end-plates or large fragments of receptors with their subsequent degeneration. The process of autotomy can be reproduced in the tissue culture. The TV-computer analysis revealed the autotomy both in developing structures in early ontogeny and in mature tissue receptors in adult animals. The autotomy seems to be a part of receptors recycling, the latter being associated with retractile activity of preterminals and resembling the separation of cytosomes in apical secretion, thrombo- and erythropoiesis.

Adaptation, Physiological↗