[Compensatory potentials of the central nervous system in premature newborn infants].

Compensatory potentials of the central nervous system (CNS) in preterm infants with a history of hypoxic-ischemic encephalopathy have been discussed with an emphasis on a need for revision of traditional perceptions. The use of new methods of evaluation of the developing brain indicates the phenomenon of its neurologic adaptability. It is suggested by a high incidence of CNS functional recovery in surviving preterm infants.

[Value of echoencephalography in the diagnosis of periventricular leukomalacia in children and the prognosis of their development].

The investigation was conducted to reveal reliable echographic features of early (necrotic) stages of periventricular leukomalacia (PVL) on the basis of retrospective analysis of echograms of decreased children (with postmortem diagnosis of PVL) and survived newborns with pronounced cystic changes in the periventricular areas (advanced PVL stage), which were revealed during dynamic echoencephalography. Altogether 268 echograms of 78 children with a birth-weight from 700 to 2400 g were analysed. All children but one were born preterm.

[New findings on the mechanism of action of blocking toxins on electrically excitable sodium channels].

The paper summarizes the results obtained from the 10-12 years studies on the mechanism of action of blocking toxins--tetrodotoxin (TTX) and saxitoxin (STX)--on voltage-operated sodium channels. Experimental data can be interpreted on the basis of two models of blocking action of toxins: channel blockade, when guanidine group of toxins penetrates into the channel and causes its blockade and allosteric action on sodium conductance. Special attention is devoted to peculiarities of cooperative interaction between the blockers and channels.

[Temperature-independence of the effect of osmotic pressure on the inward sodium current in the membrane of isolated spinal ganglion neurons of the rat].

The temperature dependence of the effect of transmembrane osmotic pressure on sodium TTX-sensitive inward current was studied on isolated neurons of rat dorsal root ganglia using intracellular perfusion under voltage clamp conditions. It was found that the effect of transmembrane osmotic pressure on the kinetic parameters of sodium current does not depend on temperature in a wide range (from 8 to 40 degrees C). The apparent values of activation energies for the activation and inactivation processes do not depend on osmolality.

[Properties of lipid bilayer membranes modified by brain Na+,K+-ATPase subunits].

Large (alpha) and small (beta) subunits (SU) of the enzyme were obtained from the high-purified Na+, K+-ATPase preparations of the cattle brain. Molecular masses of the subunits (95 and 55 kD, respectively) have been determined and the properties of bilayer lipid membranes (BLM) modified by them were investigated. The both proteins are capable of inducing the channel conductivity in BLM which is selective to alkaline metals ions in case of alpha-SU, alpha-SUE modified BLM possess some properties of Na+, K+-ATPase: the cardial glucosides at large and small doses have a specific action, the action of the above glycosides and vanadate differs; vanadate intensifies the inhibitory effect of ouabain; the cardial glycosides and K+ have an antagonistic action; the effect of ouabain depends on the content of Ca2+ in the medium.

[Ionophore properties of peptide fragments of brain Na+,K+-Atpase].

Polypeptide fragments from Na+, K+-ATPase of cattle brain are obtained by the bromocyan-treatment of the protein and subsequent gel filtration via sephadexes; the fragments were reconstructed into bilayer lipid membranes (BLM). Polypeptides of fractions I and II induce cationic and polypeptides of fraction IV--cationic-anionic conductivity of BLM. Neither sodium nor potassium selectivity of BLM modified by protein fragments of fractions I and II was observed.