Lubinska Phenomenon: Simultaneous Bidirectional Axoplasmic Flow in Nerve Fibers.

Experiments on live mollusk neurons isolated with a neurite fragmentsat its various levels demonstrated that axoplasm is characterized by mechanical strain realized in the form of retraction up to complete invagination of the axoplasm into the soma. Changes in axon geometry were attributed to neuroplasm movement. It was found that the direction of axoplasm movement depends on the location of adhesion points. It was always simultaneous and oppositely directed, as is the case with contractile myofibrils. The formation of distant paired adhesion sites can promote moving away of the axoplasm mass and organelles carried by it. The velocity and activity of axoplasm movement depend on the quantity and intensity of adhesion points along the axon.

[A case of irreversible cardiomyopathy induced by polychemotherapy].

The paper describes a case of irreversible dilated cardiomyopathy in a young female patient receiving polychemotherapy for breast cancer.

[Simultaneous opposite axonal currents in neural process. Retraction hypothesis].

Bidirectional axonal current of organelles and molecules in the nerve fibers was demonstrated using radioautography, the horseradish peroxidase and in virology. However, the mechanism of this phenomenon and regulation of the currents direction in axoplasm still remain not entirely understood. In this article we used the model of living single neurons of mollusk isolated with fragment of neural process at its different levels. It was proved that the axoplasm has a mechanical tone, which is realized in the form of retraction up to complete axoplasm invagination in the neuron soma. The geometry changing of the living axon was treated as its transport neuroplasm mass. It turned out that the direction of axoplasm mass depends on the location of its adhesion sites. It is always simultaneous and bidirectional opposite, as it is the case with contractile muscle fibers.

[Neuron contractile and electrical activities as affected by colchicine].

The purpose of this investigation was to analyze the contractile activity of traumatized nerve cell processes and to try to inhibit their retraction by colchicine solution. Isolated living neurons of mollusks (Lymnaea stagnalis and Planorbis comeus vulgaris) were studied using phase contrast and time-lapse microvideorecording. In the control group, contractile activity of nerve cell processes in Ringers solution was detected in 92% of cases. Application of colchicine resulted in the inhibition of retraction of nerve fibers in 86% of neurons. In the experiments designed to study neuron electrical activity, leech Retzius neurons were used. It was found that ganglion incubation in colchicine solution of increased the frequency of spontaneous pulse activity from 0.22 to 0.75 imp/s. The amplitude of spontaneous potentials decreased from 46.9 to 37 mV, the threshold was reduced by 18%, spontaneous spike duration increased from 4.3 ms to 7.1 ms, while the latent period of the response to irritating stimulus increased from 25.0 to 37.9 ms. During the irritation with a frequency of 7-10 Hz, neuron generated higher frequency of pulse activity, than in norm. Thus, it was possible to show, that cochicine can inhibit the contractive activity of the traumatized nerve cell processes, preserving an electroexcitable membrane in a satisfactory state. These results suggest that it is possible to partially inhibit the nerve fiber retraction in vivo, thus preventing the diastasis increase in the nerves that impedes their contact surgical approximation and promotes the development of a massive scar in severed area.

[Early reactive changes of myelin sheath in the area of myelin sheath gaps (nodes of Ranvier) in nerve fibers (a supravital study)].

Using the inverted phase contrast microscope, the supravital study of structural dynamics of single myelin sheath gaps (nodes of Ranvier) of isolated frog myelin nerve fibers was performed after mechanical injury and in the medium with the decreased ion force under the conditions which induce, in electrophysiological experiments, the expression of the axolemmal K+-channels in the paranodal area. Videorecording has shown that within this area the myelin sheath stratification appeared that was associated with the swelling of Schwann cell cytoplasm enclosed in the terminal membranous loops of myelin. An increase of the degree of stratification of the lamellar myelin complexes make them invisible in the light microscope; therefore, it is not the translocation of the myelin sheath from the node cleft that is recorded, as many authors believed, but a shift of only the visible border of the compact, yet unstratified myelin sheath. Hence, the removal of myelin (demyelination) was absent, and the electrophysiological effect can be accounted for by a significant fall of electrical resistance in paranodal area as a result of swelling of terminal loops and stratification of the myelin sheath. Preparations examination also revealed a decrease of the axonal diameter in, which is proportional to swelling of the myelin sheath terminal parts. Since the outer fiber diameter did not change, it can be concluded that the process observed is the result of swelling of the Schwann cell cytoplasm due to the axoplasm water fraction which may be a peculiar process of axo-glial interactions.

[Blood serum of patients with secondary progressive multiple sclerosis changes neuron electric activity].

An effect of 20% blood serum estimated by the changes of background and excited spike activity of Retzius' neuron by Hirudo medicinalis, which does not contain myelin, has been studied in 2 groups of patients. The first group comprised patients with serum, containing antibodies to gangliosides, and the second one--patients without such antibodies. Incubation of Reitzius neurons in the serum with GM1-antibodies within 40 min resulted in the change of spike form, increase of cell stimulation threshold by average 20%, reduction of the frequency of spontaneous impulse activity by average 28%, decrease of the spikes number in response to the lower frequency (0.5 Hz) synaptic stimulation and inhibition of adaptation to the high frequency (10 Hz) stimulation. The use of the serum without GM1-antibodies caused a different change of the spike form and increased the stimulation threshold by 8% and sparser background impulse activity of the neuron by 40%. During low frequency synaptic activation of the neuron (0.5%), there was sensitivity disturbance and inhibition of the electric response to the high frequency stimulation. The results suggest that neuron injuries in multiple sclerosis may develop before morphological appearances of myelin lesions.

Analysis of the effects of antibodies to gangliosides on the electrical activity of Retzius neurons in the leech and on the functional activity of influx sodium current channels.

The effects of anti-ganglioside antibodies on the functional states of two types of influx Na+ current channels were studied. Experiments used 20% anti-ganglioside antiserum prepared by standard methods by immunizing rabbits with total bovine brain gangliosides. These experiments showed that incubation of neurons in physiological saline containing antiserum induced discordance in the operation of the two types of influx current Na+ channels responsible for spike generation. This reaction was found to be associated with the slowed rate of activation of TTX-sensitive Na+ channels. Synaptic stimulation of cells in the presence of antiserum induced blockade of TTX-insensitive influx Na+ current channels. High-frequency synaptic activation of cells (10 Hz) showed that apart from blockade of TTX-insensitive Na+ channels, anti-ganglioside antibodies prevented plastic rearrangements in the gate system of TTX-sensitive Na+ channels. This resulted in impairment of the development of the acclimation process - the response of the neuron to high-frequency stimulation seen in normal conditions.

[Effect of the antibodies to gangliosides on the Retzius neuron electrical activity and the functional activity of sodium channels for incoming current in leech]. / Analiz vliianiia antitel k gangliozidam na élektricheskuiu aktivnost' neirona Rettsiusa piiavki i na funktsional'nuiu aktivnost' natrievykh kanalov vkhodiashchego toka.

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.

[Axonal reaction precedes demyelination in experimental models of multiple sclerosis]. / Reaktsiia aksonov predshestvuet demielinizatsii v éksperimental'nykh modeliakh rasseiannogo skleroza.

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.

[Tetrodotoxin effect on spontaneous and evoked impulse activity of leech Retzius neurons]. / Effekt tetrodotoksina na fonovuiu i vyzvannuiu impul'snuiu aktivnost' neirona Rettsiusa piiavki.

Investigation into the Retzius neuron response to synaptic low-, medium-, and high-frequency stimulation under the block of the TTX-sensitive sodium inflow channels, was performed in leeches. The TTX block affected the spontaneous unit activity and not the evoked activity, it altered the responses to low-frequency stimulation (sensitisation) and eliminated the responses to high-frequency activation (habituation). The findings suggest the fundamental plastic properties of the Retzius neurons to depend on functional characteristics of the TTX-sensitive sodium channels.

[The effect of gutimine and amtizol on the K, Na-pump activity of the nerve cell]. / Vliianie gutimina i amtizola na aktivnost' K, Na-nasosa nervnoi kletki.

The antihypoxants gutimine and amtisole, its cyclic derivative of 3.5-diamino-1,thia-2,4-diazole were tested for their effects on the activity of one of the most power-consuming functions of a nerve cell--on the activity of the K, Na-pump during normoxia. Gutimine was found to decrease K, Na-pump activity in the Retzius neurone by an average of 70% presumably due to its inhibitory effects of leakage currents. The experiments suggest that the preventive protective effect of gutimine is displayed at the membranous level. Amtisole was found to unchange the functional activity of the K, Na-pump in the Retzius neurone.