[Resistance of natural and synthetic polyribonucleotide inducers of interferon to human blood ribonucleases]. / Ustoichivost' prirodnykh i sinteticheskikh poliribonukleotidnykh induktorov interferona k ribonukleazam chelovecheskoi krovi.

The resistance of polyribonucleotide inductors of interferon to blood ribonucleases was studied. Blood resistance of larifan and ridostin in the free and shielded state as well as that of the complexes of poly(I)-poly(C) and poly(G)-poly(C) were also investigated. A protective action of polylysine against the inductors was detected which, in case it had no effect on the biological activity of the drugs, could provide its recommendation as a compound for shielding the inductors.

[Synthesis and analysis of des-Met5-[D-Ala2]enkephalinamide analogs]. / Sintez i izuchenie analogov des-Met5-[D-Ala2]énkefalinamida.

The effects of N- and C-terminal oligoalanine insertions into des-Met5-[D-Ala2]enkephalin amide (I) on the biological activity and spatial structure were examined. The corresponding analogues were obtained by solid-phase synthesis using Sephadex LH-20 ac a polymeric support. Biological activity was assayed via changes in the pain threshold in the rat, body temperature, and also as affinity for opiate receptors. Active analogues were obtained upon modifying the carboxylic group in the tetrapeptide I with di- and tri-D-alanyls. The CD spectra of the C-derivatized analogyes were similar to those of the starting tetrapeptide I and [Met5]enkephalin, whereas the N-derivatized analogues showed essentially different CD spectra.

[Antiepileptic action of met-enkephalin and the rapid development of tolerance to its epileptogenic action]. / Protivoépilepticheskoe deistvie met-énkefalina i bystroe razvitie tolerantnosti k ego epileptiziruiushchemu deistviiu.

It has been shown in chronic experiments on rabbits with electrochemoelectrodes implanted into the dorsal hippocamp that the first administration of met-enkephalin in a dose of 60 to the hippocamp induced the development of an epileptogenic focus (EF) or potentiated the action of the penicillin-induced EF. The second administration of met-enkephalin in the same dose to the hippocamp (interval in a standard scheme of experiments 5 days) did not lead to the production of the EF, which attests to rapid development of tolerance to the epileptizing action of the peptide, with this tolerance being preserved for 20 subsequent days of observation over the animals. After tolerance developed, administration of 60 micrograms met-enkephalin 5 to 10 min before penicillin produced an antiepileptic action, thereby preventing the development of the EF. Met-enkephalin (0.1 and 1 microgram) did not epileptize hippocampal neurons but lowered the action of the penicillin-induced EF after the development of tolerance to the epileptizing action of a large dose of the peptide. The animals did not develop tolerance to the antiepileptic effect of met-enkephalin. The data obtained confirm the hypothesis that different opiate receptors are responsible for the epileptizing (delta-receptors) and antiepileptic (mu-receptors) action of the enkephalin. The effect of small doses of met-enkephalin appears to mirror to a greater degree the involvement of endogenous enkephalins in the epileptogenesis.

[Decreased acetylcholinesterase activity in the area of epileptogenic foci created by met-enkephalin in the hippocampus of rats]. / Snizhenie aktivnosti atsetilkholinesterazy v oblasti épileptogennykh ochagov, sozdannykh met-énkefalinom v gippokampe krys.

Experiments on rats with electrochemotrodes implanted in the left and right hippocamp have shown that in epileptogenic foci created by microinjections of met-enkephalin or D-ala-2-met-enkephalin into the hippocamp, acetylcholinesterase activity (AChE) was diminished. It is assumed that reduction in AChE activity is an adaptive mechanism by which the excitability of hippocampal inhibitory basket cells, which are sensitive to acetylcholine, is increased.