Atypical Acetylcholine Receptors on the Neurons of the Turkish Snail.

Using electrophysiology, the effect of nicotinic acetylcholine receptor (nAChR) ligands on acetylcholine-induced depolarization in the neurons of Helix lucorum snail was studied. It was found that the α-conotoxin PnIA [R9, L10], a selective antagonist of α7 nAChR, and α-cobratoxin (antagonist of α7 and muscle-type nAChR) suppressed neuronal depolarization. Fluorescence microscopy showed staining of the neurons with fluorescently labeled α-bungarotoxin; this staining was reduced by pretreatment with α-cobratoxin. Induced depolarization was also suppressed by α-conotoxin RgIA, a selective inhibitor of α9 nAChR. In contrast to Lymnaea stagnalis nAChR, which are weakly sensitive to neurotoxin II and α-conotoxin GI, antagonists of muscle-type nAChR, H. lucorum receptors were most effectively inhibited by these antagonists. The results obtained, as well as the previously found sensitivity of the receptors studied in this work to muscarinic receptor ligands, indicate an unusual atypical pharmacological profile of H. lucorum nAChR.

Effect of Ethosuximide on Audiogenic Epilepsy in Krushinsky-Molodkina Rats.

The anticonvulsant effect of ethosuximide (T-type calcium channel blocker) was evaluated in Krushinsky-Molodkina rats predisposed to audiogenic epilepsy. Ethosuximide given with drinking water (300 mg/kg/day) over 45 days slightly reduced proneness to audiogenic epilepsy and increased locomotor activity of the animals at the periphery of the open field. Neonatal administration of ethosuximide (3-4 mg per animal, from 2 to 10 days of life) insignificantly modulated the parameters of audiogenic epilepsy in these animals at the age of 1.5 months and reduced manifestation of audiogenic myoclonic convulsion that developed after long daily sound presentation started at the age of 3 months. The findings attested to a weak anticonvulsant effect of ethosuximide on tonic convulsions with its predominant effect on convulsions with forebrain focus location.

Study of Uridine Effect on the Development of Audiogenic Tonic Seizures in Krushinsky-Molodkina Strain Rats.

The latency of tonic seizure in response to loud sound (in rats of the Krushinsky-Molodkina strain with audiogenic epilepsy) had been slightly (although statistically significantly) longer after chronic uridine injections (100 mg/kg, i.p., three times a day during 9 or 12 days). The recovery time from the tonic seizure was shorter after 12 days of injections in comparison to the 9-day injection period. At the same time, the intensity of tonic seizures provoked by loud sound did not change after chronic uridine injections. The lack of uridine anticonvulsive effect demonstrated in the audiogenic epilepsy model contradicts the anticonvulsant effects of uridine in experiments with other seizure models, in which the epileptic foci were localized in the forebrain structures.

Remote effects of short-term neonatal hyperthermia in Krushinsky-Molodkina rats prone to audiogenic seizures strain.

Using the audiogenic seizure prone Krushinsky-Molodkina rat strain, it was demonstrated that short-term (5 min) exposure of 14-day-old pups to an elevated temperature (42°C) resulted in a significant decrease in audiogenic seizure severity at the age of 1 month. Presumably, this effect is determined by the activation of the heat-shock protein system (stress proteins).

Effect of chronic fluoxetine treatment on audiogenic epilepsy, symptoms of anxiety and depression in rats of four lines.

Anxiety (Anx) and depression (Dp) levels were evaluated in rats of 4 lines: 2 of them (KM and "4") exhibited audiogenic seizures (AS), and 2 (Wistar and "0") had no AS. In KM rats (with AS), Anx and Dp levels were higher than in Wistars (without AS), while in "4" and "0" rats with the related genetic background but contrasting in AS severity, Anx and Dp indices were not different. Fluoxetine treatment exerted antidepressant effect in all rat lines irrespective of its effect on AS. Thus, phenotypic expression of AS is not directly associated with the mechanisms of Anx and Dp development.

[Diffusion properties of water in the human crystalline lens during cataract development]. / Diffuzionnye svoistva vody v khrustalike cheloveka pri razvitii katarakty.

Normal and cataractal decapsulated lenses of man were studied by NMR method-spin echo to obtain information concerning efficient coefficients of self diffusion, times of spin-spin relaxation of water protons (T2) and water content in the lens (c) at 25 degrees C in the course of cataractogenesis. It has been found that the values T2 and c at 25 degrees C are much higher in the nuclei of completely turbid lenses than in the transparent ones; the self-diffusion coefficients in the turbid lenses were also higher. At -9 degrees C a significant decrease of the content of undestroyed by frost (bound) water was observed at the stage of mature cataract as compared to transparent lenses. It is suggested that the most specific differences between the nuclei of transparent and completely turbid lenses are related to increased diffusion mobility of water molecules, apparently, at the expense of damaged plasmic membranes of the lens fibres noted during cataract development.

[Azlocillin stability in solutions and the solid state]. / Ustoichivost' azlotsillina v rastvorakh i tverdom sostoianii.

Stability of azlocillin in aqueous solutions at pH 1.5-12.5 was studied at various temperatures. It was shown that degradation of the antibiotic proceeded as an irreversible first order reaction. Dependence of 1gk on the reverse temperature was described by the Arrhenius equation. The highest levels of azlocillin stability in solutions were observed at pH about 6.0. In solid state azlocillin was stable under the effect of the environmental factors. In the atmosphere of oxygen and carbon dioxide and on exposure to light the quality parameters of the antibiotic powder maintained at the control levels.

[Determination of the kanamycin B content of kanamycin preparations by column chromatography]. / Opredelenie soderzhaniia kanamitsina B v preparatakh kanamitsina metodom kolonochnoi khromatografii.

Kanamycin B content in kanamycin preparations was determined with column chromatography and PMR spectroscopy. It was shown that coincidence of the results obtained with both the procedures in analysis of the preparations subjected to additional recrystallization was satisfactory. With the use of nonrecrystallized preparations the admixtures interfered with the results in using the developed procedure.

[NMR study of the state of water in the human lens during cataract development]. / Izuchenie sostoianiia vody v khrustalike cheloveka pri razvitii katarakty metodom IaMR-spinovogo ékha.

Water proton spin-spin relaxation times (T2) and the content of bound, "non-freezable" at -9 degrees C water in both normal human lenses and human lenses of different stages of cataract progression (cataracta incipiens, nondum matura, mature hypermatura) were measured by NMR spin echoes method. By the stage of cataracta nondum matura, increase of bound water content and simultaneous, almost half decrease of the relaxation time (T2), were observed. However, on the following stages of cataract evaluation (almost mature, mature cataracts) a gradual decrease of bound water content is noted, but only for the mature cataract stage the water content significantly differs from that of the normal one. On the stage of hypermature cataract the presence of two unexchanged with each other fractions of water is found. The obtained data are explained by lens protein reconstructions during the cataract progression.

Photo-induced electron transport and water state in Rhodospirillum rubrum chromatophores.

It is shown that in bacterial chromatophores the pronounced changes in the free water content with a proton spin-spin relaxation time (T2) of 10(-3)--10(-2) s does not influence the efficiency of electron transfer from the photosynthetic reaction centre to the membrane pool of secondary acceptors. An abrupt inhibition of this process occurs only after the loss of the water with faster proton spin-spin relaxation time (T2 of 10(-4) s). The process is reversible. The water fraction in question is obviously bound to the chromatophore proteins and forms the primary hydration layer.

[NMR spin-echo study of the effect of hydration on the mobility and conformation of linear polyethyleneimine]. / Issledovanie vliianiia gidratatsii na podvizhnost' i konformatsiiu lineinogo poliétilenimina metodom spinovogo ékho IaMR

It has been shown that mobility of protons in different groups of linear polyethylenimine (LPEI) is sensitive to the formation of H-bonds between amino groups of a polymer. Upon hydration of LPEI most of direct bonds between amino groups are substituted by the bonds via water molecules. This results in a conformational change of the polymer. Similar process may also occur in biopolymers.

[Study of the embrotoxic properties of the repellent diethyltoluamide]. / Izuchenie émbriotoksicheskikh svoistv repellenta diétiltoluamida

With application to the skin of an albino female-rat over the whole period of its pregnancy of the repellent diethyltolueneamide (DETA) in doses of 100 and 1000 mg/kg the overall embryonal fatality was found to go up, the size and weight of the rattlings to be down; there was recorded a lagging development of the newborns and a high postnatal death rate. The preparation could easily overcome the placental barrier, it was demonstrable in the placenta, fetuses, as well as in the bodies of newborn rattlings, even 3 months after their birth.