[Picocyanobacteria in eutrophic reservoirs of the Middle Volga: abundance, production, viral infection].

During the summer season of 2010, abundance and productivity of picocyanobacteria in Gorky and Cheboksary Reservoirs have being examined. It is found out that in the eutrophic reservoirs of the Middle Volga abundance and biomass of picocyanobacteria, averaged over the water column, varied within the range of (34-322) x 10(3) cells/ml and 38-455 mg/m3 respectively. In more productive Cheboksary Reservoir, the contribution of picocyanobacteria in total biomass and production of phytoplankton (4.7 ± 0.7 and 8.3 ± 1.3% respectively) was lower than in less productive Gorky Reservoir (10.6 ± 2.1 and 19.2 ± 3.0% respectively). In both reservoirs, high level of picocyanobacteria infection by viruses was detected. The frequency of visible infected cells and virus-induced mortality of picocyanobacteria in Cheboksary Reservoir were substantially higher (3.2 ± 0.4% of total abundance and 21.8 ± 2.9% of daily production) than in Gorky Reservoir (1.7 ± 0.2% of total abundance and 11.0 ± 1.7% of daily production). The results obtained indicate that in eutrophic reservoirs during summer bloom of large cyanobacteria their abundance is regulated to a great extent by viruses.

[The antiamnestic effect of nootropic substances in rats].

It has been established in experiments in rats that some nootropic substances (oxyracetam, aniracetam, nooglutil, mexidol, new 3-hydroxypyridine derivative SK-170, piracetam and noopept) produce marked antiamnestic effect on various models of amnesia (induced by microwave irradiation, acute hypoxia, and motion sickness). At the same time, meclophenoxate exhibited antiamnestic effect in the first and second models of amnesia, while 9-aminoacridine derivative HTOS-404 was only effective in the model of amnesia caused by microwave irradiation. The antiamnestic effect of nooglutil and SK-170 was caused to a significant degree by activation of non-NMDA receptors of excitatory amino acids (generally AMPA receptors), while the effect of mexidol was related to GABA(A) receptors.

[Effect of nootropic agents on impulse activity of cerebral cortex neurons]. / Vliianie nootropov na impul'snuiu aktivnost' neironov kory bol'shogo mozga.

The effect of nootropes (semax, mexidol, and GVS-111) on the activity of individual neurons in various cerebral cortex regions was studied by microelectrode and microionophoresis techniques in cats immobilized by myorelaxants. It was established that the inhibiting effect of mexidol upon neurons in more than half of cases is prevented or significantly decreased by the GABA antagonists bicuculline and picrotoxin. The inhibiting effect of semax and GVS-111 upon neurons in more than half of cases is related to stimulation of the M-choline and NMDA receptors, respectively.

[Pharmacological treatment of memory disorders caused by hypoxia and cerebral ischemia in rats]. / Farmakologicheskaia korrektsiia narushenii mnesticheskikh funktsii, vyzvannykh gipoksiei i ishemiei golovnogo mozga u krys.

Experiments with white mongrel rats (both females and males) showed that nootropic substances, i.e. sodium hydroxybutyrate, pyracetam, oxyracetam, aniracetam, centrophinoxine, nooglutyl, mexydol, semax, amide L-pyroglutamyl-D-alanine, and MK-801, a specific noncontesting antagonist of the NMDA-receptor complex, significantly increased survivability of the animals following bilateral occlusion of the common carotid arteries. The nootrops prevented, partly or completely, mnestic disorders in the experimental rats. In contrast, MK-801 profoundly aggravated these disorders. Similar results were obtained with a model of hypoxic amnesia. Except for N-acetylglycine amide and amide L-pyroglutamyl-D-alanine, the nootrops fully or to a considerable extent blocked the development of mnestic disorders in hypoxic rats. The authors recommend novel nootrops (nooglutyl, mexidol, semax and GVS-111) for the pharmacological correction of mnestic disorders consequent to hypoxia or cerebral ischemia.

Determination of the fraction composition of blood lipoproteins by the small-angle X-ray scattering technique.

A new method for analyzing the fraction composition of blood lipoproteins (LP) was developed based on the small-angle X-ray scattering (SAXS) technique. The method allows quantitative determination of the contents of basic LP fractions (high-density LP, low-density LP, very low-density LP and their subfractions) in the blood plasma or serum. The results of LP analysis by the new method were compared with electron microscopy, ultracentrifugation and gel electrophoresis data. The results obtained by SAXS correlated with those obtained by traditional methods. The new method for the determination of the LP fraction composition in the blood is rapid (1-1.5 h), uses only one reagent (e.g., sucrose) and features a high accuracy and resolution up to LP subfractions. A total of 0.05 ml of the blood plasma or serum is required for an assay. The assays can be carried out in purified preparations or in the blood plasma or serum. The method developed can be used in clinical practice for diagnostics and in scientific research.

[Memory disorders due to extreme exposures and their pharmacological correction]. / Mnesticheskie rasstroistva, vyzvannye ékstremal'nymi vozdeistviiami, i ikh farmakologicheskaia korrektsiia.

The review contains the present-day data on new neurophysiological and neurochemical mechanisms of learning and memory processes disturbances induced by such extreme factors as microwaves, hypoxia [correction of hyghproxia], motion sickness, electro-convulsive shock, etc. The main attention is concentrated on the role of some nootropic drugs in preventing the memory-impairing effect of all these extreme factors. The current concept of the mechanisms action of the nootropics in these extreme conditions is discussed.

[The nootropic correction of disorders in learning and memory processes induced by extreme exposures]. / Korrektsiia nootropami narushenii protsessov obucheniia i pamiati, vyzvannykh nekotorymi ékstremal'nymi vozdeistviiami.

Experiments on rats demonstrated that the low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2), motion sickness, and electroconvulsive shock provoked the retrograde amnesia in the passive avoidance test. The oxyracetam (100 mg/kg, i.p.), aniracetam (50 mg/kg, i.p.), nooglutil (50 mg/kg, i.p.), meclofenoxate (50 mg/kg, i.p.), pyracetam (200 mg/kg, i.p.), and GABA (200 mg/kg, i.p) prevented the memory-impairing effect of all these extreme factors. On the contrary, the N-acetylglycinamide, semax, and other nootropic drugs were effective only under one or two extreme conditions.

Rates of benthic protozoan grazing on free and attached sediment bacteria measured with fluorescently stained sediment.

In order to determine the importance of benthic protozoa as consumers of bacteria, grazing rates have been measured by using monodispersed fluorescently labeled bacteria (FLB). However, high percentages of nongrazing benthic protists are reported in the literature. These are related to serious problems of the monodispersed FLB method. We describe a new method using 5-(4,6-dichlorotriazin-2-yl)-aminofluorescein (DTAF)-stained sediment to measure in situ bacterivory by benthic protists. This method is compared with the monodispersed FLB technique. Our estimates of benthic bacterivory range from 61 to 73 bacteria protist h and are about twofold higher than the results of the monodispersed FLB method. The number of nongrazing protists after incubation for 15 min with DTAF-stained sediment is in agreement with theoretical expectation. We also tested the relative affinity for FLB of protists and discuss the results with respect to a grazing model.

[Effect of low intensity and ultra high frequency electromagnetic irradiation on memory functions]. / Deistvie nizkointensivnogo élektromagnitnogo izlucheniia sverkhvysokoi chastoty na mnesticheskie funktsii.

The experiments on rats proved that low intensity electromagnetic waves result in retrograde amnesia due to benzodiazepine, gamma-aminobutyric acid and cholinergic mechanisms. Nootropic drug pyracethamum was proved to reduce the pathologic effect.

[The effect of ultrahigh-frequency electromagnetic radiation on learning and memory processes]. / Vliianie élektromagnitnogo izlucheniia sverkhvysokoi chastoty na protsessy obucheniia i pamiati.

Low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2) produced retrograde amnesia in the rat passive avoidance test. No effect was registered of microwave irradiation on the open field behavior and the pain sensitivity. Functional activity of the m-cholinergic receptors decreased, but their number increased in the brain cortex. It is suggested that cholinergic system plays an important role in the effects of electromagnetic field on memory processes.

[Lipid biosynthesis and metabolism of native and acetylated low density lipoproteins in macrophages stimulated by zymosan in vivo and in vitro]. / Biosintez lipidov i metabolizm nativnykh i atetilirovannykh lipoproteidov nizkoi plotnosti v makrofagakh, stimulirovannykh zimozanom in vivo i in vitro.

The effects of zymosan on lipid metabolism in mouse peritoneal macrophages (MPM) in vitro and in vivo were studied with special reference to the following parameters: i) 14C-oleate incorporation into cholesteryl esters (CE), triglycerides (TG), and phospholipids (PL) in MPM incubated with low density lipoproteins (LDL) and acetylated LDL; ii) cholesteryl-14C-oleate-acetyl LDL uptake and 125I-acetyl LDL degradation; iii) oxidative modification of LDL. Zymosan administered to mice caused significant stimulation of 14C-oleate incorporation into CE, TG, and PL with no effect on 3H-cholesterol (Ch) incorporation into CE or 3H-glycerol incorporation into TG and PL in MPM. The 14C-oleate incorporation into cellular lipids was unaffected by 18-hour incubation of MPM with zymosan (100-500 micrograms/ml) but increased after incubation of unstimulated MPM with blood serum and peritoneal fluid harvested harvested from zymosan-treated mice. One possible explanation of this phenomenon is oleyl-CoA formation induction in cytokine-stimulated MPM in vivo. Zymosan decreased the Ch-14C-oleate-acetyl LDL uptake, 125I-acetyl LDL degradation, and Ch esterification in the presence of acetyl LDL in MPM both in vitro and in vivo. An increase in Ch esterification after incubation of MPM with zymosan for 6-18 hours in the presence of LDL was accompanied by an increase in lipid peroxidation of LDL and its electrophoretic mobility. The data obtained suggest that the macrophage acetyl LDL receptor pathway may be inhibited by zymosan and that cytokines released from zymosan-stimulated cells may influence the generation of foam cells.

[A comparative study of the nootropic properties of piracetam and oxiracetam]. / Sravnitel'noe izuchenie nootropnykh svoistv piratsetama i oksiratsetama,

The behavioral activities of piracetam and oxiracetam were studied during the learning tests (active avoidance, passive avoidance, T-maize). The levels of the orientation reaction and emotionality of the animals were determined by the "open field" method. To achieve similar effects, injections of 10 mg/kg of oxiracetam and 100 mg/kg of piracetam intraperitoneally were required. Both nootropics facilitated the learning of the animals but failed to change their behavior in the open field. Piracetam was more effective in the active avoidance test and oxiracetam in the T-maize test. The data indicate some differences in the activities of piracetam and oxiracetam.

[Effects of oxiracetam and piracetam on the electrical activity of neurons of the cerebral cortex]. / O vliianii oksiratsetama i piratsetama na élektricheskuiu aktivnost' neironov kory golovnogo mozga.

The effect of oxiracetam and piracetam on the spontaneous impulse neuronal activity of the somatosensory cortex of the cat and rabbit was studied. Oxiracetam and piracetam when applied microiontophoretically changed neuronal activity by depressing in the majority of the cases studied or sometimes facilitating the spontaneous firing rate. A small percentage of neurons (about 30%) remains unaffected by the application of the nootropics. In some cases oxiracetam and piracetam diminished the depress effect of morphine and DADLE on the spontaneous impulse neuronal activity.

[The influence of piracetam on the effects of narcotic analgesics]. / Vliianie piratsetama na éffekty narkoticheskikh anal'getikov.

In experiments on white male mice there was studied the influence of piracetam (250-300 mg/kg) on the analgesic effect of ligands of different types of opioid receptors (morphine, 7.5 mg/kg, DADLE, 7.5 mg/kg, pentazocine, 15 mg/kg) and also on the action of morphine concerning the cardiovascular system and respiration. Piracetam was shown to possess the antagonistic properties with respect to some effects of morphine, however they are not of the universal character and do not depend on the interaction with a certain type of opioid receptors.

[Effects of piracetam on pain sensitivity and levels of beta-endorphin in blood and cAMP in the cerebral cortex of rats]. / Vliianie piratsetama na bolevuiu chuvstvitel'nost', uroven' beta-éndorfina v krovi i tsAMF v kore golovnogo mozga krys.

It has been shown, that piracetam by i.p. injection (10, 100, 400 mg/kg) or by consumption with drinking water 10, 100, 1000 mg/kg/day during 12 days delays extinction of conditioned reflex of passive avoidance and dose-dependence elevates exploratory activity in "open field", pain sensitivity threshold reduces to 70-75%. Prolonged consumption of 1000 mg/kg/day piracetam results in 3-fold decrease of beta-endorphin concentration in plasma (p less than 0.01) and 100 mg/kg/day--in 35% increase of cAMP content in rat brain cortex.

[Comparative influence of nootropic preparations on the emetic effect of morphine]. / Sravnitel'noe vliianie nootropnykh preparatov na émeticheskii éffekt morfina.

The effect of electroshock (ECS) and piracetam, oxiracetam or N-acetylglycinamide on the passive avoidance conditioned response in rats was studied. The antiemetic effect of the compounds was examined in cats as well. The results obtained allowed us to distinct the nootropic and antiemetic action of the drugs. The substances possessed a similar ability to prevent ECS-induced amnesia. On the contrary, oxiracetam completely prevented the emetic response to morphine at doses 100 times lower and piracetam at doses 10 times higher then those of the opioid. N-Acetylglycinamide had no antiemetic activity. The results obtained show that oxiracetam is 100 times more active in antiemetic test than piracetam. These data comprise the novel properties of nootropic drugs.

[Influence of piracetam on the effects of narcotic analgesics and opioid peptides]. / Vliianie piratsetama na éffekty narkoticheskikh anal'getikov i opioidnykh peptidov.

Piracetam possesses some properties not related to the nootropic activity. The purpose of the work was to study piracetam influence on effects of narcotic analgesics and opioid peptides at intracerebroventricular administration. In experiments on cats it was found that piracetam in a dose-dependent way prevented the emetic effect of morphine and leu-enkephalin. In experiments on rats (tail-flick test) piracetam was shown to be able of blocking the analgesic effect of fentanyl. Experiments on the study of the anticataleptogenic effect of piracetam also showed antagonism between piracetam and agonists of opioid receptors. Thus, it was shown on a number of models that piracetam exhibits antagonistic properties with respect of opioid peptides and narcotic analgesics.