Effect of armin on the ultrastructure of the neuromuscular synapse]

Alterations induced by the cholinesterase inhibitor armin (5.10(-7) g/ml) in the ultrastructure of motor nerve endings of the rat phrenic diaphragmal preparations at rest or electric stimulation of the nerve were studied. It was shown that armin at rest induced ultrastructural lesions in the endings similar to those in the control preparations during nerve stimulation. Electric stimulation did not produce additional changes in the ultrastructure of the neuromuscular junction under armin action. It is suggested that the disorder of the nerve ending function may be of importance in the mechanism of the blocking action of armin on the neuromuscular transmission.     

About mechanisms of genesis,structure, and functional role of endogenous rhythms (To the 100-Annivesary of Aleksei Valentinovich Voino-Yasenetskii)

The work presents a short review of concepts of origin and representation of ancient (primary) endogenous rhythms whose period is in the near-second-near minute ranges. These rhythms are the basis for the appearance of the viscero-and somatomotor excitation in various functional systems of vertebrate and invertebrate animals. Based on literature data and the own studies, there has been considered a hypothesis of universality of mechanisms of generation of endogenous rhythms of a certain frequency range regardless of their localization. The recently performed new experimental works have confirmed and enlarged A.V. Voino-Yasenetskiis’s viewpoints suggested in the 1950–1980s. It has been shown that under effect of certain extreme or pathological factors, in excitable structures, functional dissolution of coordinational mechanisms can be observed; it is accompanied by a change of the activity pattern and reproduction in it of the ancient excitation rhythms absent in the normal state. The appeared atypical rhythmicity is similar with pathological activity described in clinical medicine. Development of further studies of mechanisms of reproduction of primary rhythms might be not only of fundamental, but also of certain practical interest.     

The effect of cell migration on the stability of immunogenic multicentric tumors

A mathematical model of the growth of multicentrical tumors under conditions of the tumor cells interactions with cytotoxic T-lymphocytes (CTL), natural resistant factors and cells and migration CTL between tumor focuses is presented. For any finite number of the tumor focuses at the comparatively low intensity migration of CTL the dynamic stability conditions among multicentrical tumors and the immune system were obtained.     

Viscoelastic properties of relaxed papillary muscle under physiological hypertrophy

Viscoelastic properties of relaxed rat papillary muscles in physiological hypertrophy (intensive swimming for 5 weeks) have been obtained. It has been ascertained that viscoelastic properties of hypertrophied muscles are not significantly distinguished from those of control papillary muscles. A three-dimensional model of myocardial fascicle has been verified in compliance with experimental data of biomechanical tests of hypertrophied muscles. Elastic and viscous parameters of structural elements of the model negligibly differ from the parameters of the model of a control muscle. It is shown that physiological hypertrophy has a slight influence on viscoelastic properties of papillary muscles.     

Ion-exchange properties of immobilized DNA: influence of the polymer concentration and the solvent nature on the exchange of alkali metals

The method of ion exchange on immobilized DNA, which allows to determine quantitative parameters of ion binding with a high precision, is used for studying of DNA ion selectivity. Insoluble ion exchangers on the DNA basis with the exchange capacity of 0.09 and 0.17 mg-equiv. per 1 g of dry gel are synthesized by means of immobilization of DNA gel in polyacrylamide gel. Constants of ion-exchange equilibrium for the exchanges K+-Na+ and K+-Li+ are determined on these exchangers in water and 50% water-dioxane solution. It is shown that DNA binds selectively only Li+. The selectivity to Li+ increases with the increase of DNA concentration in gel. The specific properties of Li+-DNA in solutions and in the solid state, for example, the impossibility of the B-A transition, are discussed. The selectivity reversal in favor of K+ is observed in water-dioxane solution. The cause of the selectivity reversal and the question of possible participation of cell polyelectrolytes in creation of ion gradients in the living cell are discussed.     

Study of the state of blood plasma by the spin probe method

To evaluate the potentialities of the spin probe method in examination of the blood plasma state, a study was made into the blood plasma bound nitroxyl radical 2,2,4,4-tetramethyl-1,2,3,4-tetrahydro-5,6-benzo-gamma-carbolin-3-oxyl in healthy rabbits and those with pronounced experimental atherosclerosis. The probe absorption by high molecular plasma components was assayed in order to determine the binding constants and concentration of the binding centers, mobility of adsorbed probes and polarity of their surroundings. In the course of experimental atherosclerosis development these parameters underwent changes correlating with those of blood plasma cholesterol level. The data obtained suggest that the spin probe method may be used for assessement of the plasma state for diagnostic and research purposes.