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Biomedical subjects

I I Stepanov

Publications and source records attributed to I I Stepanov.

33 records · Page 2Linked to original sources
PubMedDate not supplied

[The embryo-protective action of antifein derivatives in chloridin-induced teratogenesis].

We studied the effect of propyl- and ethylnorantifein on chloridine-induced abnormalities of extremities in rat embryos. Chloridine (50 and 25 mg/kg, given through the gastric tube) was administered to rats on day 14 of pregnancy, and its embryotoxic effect was estimated from the state of fetuses and implantation sites on day 20 of prenatal development. Propylnorantifein had fetoprotective properties both after intraperitoneal (10 mg/kg) and after intraamniotic (6 and 0.06 micrograms) administration. Ethylnorantifein under similar conditions does not change the action of chloridine, and it prevents the appearance of developmental abnormalities only at the concentration of 0.06 microgram/embryo. These data are discussed in connection with different effects of antifein derivatives on chromatin proteinkinase, which phosphorylates HMG nonhistone proteins.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

[Effect of the population density on growth and regeneration in the snail Achatina fulica].

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Animals↗
PubMedDate not supplied

[The effect of ethanol on the food behavior of the snail Achatina fulica].

The feeding behaviour of the land snails Achatina fulica was used for investigation of the effects of different doses of ethanol. The time from the beginning of food (carrot) exposure till the removal of the carrot from the needle was measured. Regression analysis revealed the opportunity of approximation with exponential mathematical model of feeding behaviour time progressive decrease during food exposure. 1% ethanol solution injected into cephalopedal sinus inhibited the feeding behaviour to a small extent whereas 5% and 10% ethanol led to the facilitation of this behaviour. The increase of ethanol concentration from 20% to 40% in injected solution enhanced the inhibitory effect. The feeding behaviour is proposed to be employed as a model for investigation of ethanol neuronal effects.

Animals↗
PubMedDate not supplied

[The evolutionary aspects of the dynamic acquisition of simple conditioned reflexes].

The dynamics of elaboration of simple classical and instrumental conditioned reflexes in snails, rats, cars, dogs and humans was investigated. The dependence between the number of correct responses (in percentages) and the number of reinforcements was significantly approximated with exponential equation including the coefficient describing the initial level of conditioning. Regression analysis gave the opportunity to compare the dynamics of conditioning in different animal species.

Adult↗
PubMedDate not supplied

[Regression analysis of an instrumental conditioned tentacular reflex in the edible snail].

Regression analysis revealed the opportunity of approximation with exponential mathematical model of the learning curves of conditioned tentacle reflex. Retention of the reflex persisted for more than three weeks. There were some quantitative differences between conditioning of the right and the left tentacle. There was formation of the reflex in every session during spring period, but there was no retention between sessions. The conditioned tentacle reflex may be employed in neuropharmacological studies.

Animals↗
PubMedDate not supplied

[The humoral link in the mechanism of formation of conditioned food refusal in the edible snail].

Effect was studied of hemolymph of snails-donors with conditioned food refusal, on learning the same habit by snails-recipients. Facilitation was observed of the recipients' learning depending on the quantity of injected hemolymph and the type of conditioned stimulus. The hemolymph of pseudo-conditioned donors inhibited the learning of intact snails-recipients. The possibility is suggested of appearance in the hemolymph of conditioned snails of one or several chemical factors, capable to facilitate elaboration of the same conditioned reflex.

Animals↗
PubMedDate not supplied

[Specific and nonspecific components in the neurohumoral link of the conditioned food-refusal reflex in the edible snail].

On snails, the action was studied of hemolymph of donors with conditioned food refusal reflex on acquisition of the same habit by intact snails-recipients in case of coincidence or of difference of conditioned stimuli in donors and recipients. Specific component of the facilitating effect was distinctly manifest at selection of optimal doze of hemolymph and depended on the season. At non-optimal parameters of the experiment the specific component of the facilitating effect was masked by the non-specific one, or an inhibitory effect took place. The data obtained testify to multicomponent composition of the neurohumoral link in the mechanism of conditioned reflex formation.

Animals↗
PubMedDate not supplied

[Dynamics of elaboration of a conditioned reflex and differentiations in the snail].

It is shown that dynamics of percentage of conditioned food refusals by snails Helix pomatia and Helix lucorum is satisfactorily approximated by regression equation of exponential type with included coefficient reflecting the animals state before the beginning of learning. The ability is established of the snails to practically completely differentiate various alimentary conditioned stimuli. The introduction of differentiation always improved the reflex consolidation. Conditioned reactions to differentiation stimulus appeared at the elaboration stage and were absent at the stage of conditioned reflex consolidation.

Animals↗
PubMedDate not supplied

[Probability analysis of elements of rat behavior after sudden and signalled interruption of food reinforcement].

Probability analysis was carried out of the appearance of single elements of rats behaviour in the process of extinction of a conditioned alimentary motor reflex. The dynamics of effector behavioural components at a sudden cessation of reinforcement (usual schedule of extinction) was compared with cessation of reinforcement signalled by a previously differentiated signal and with reinforcement cessation preceded by a stimulus initially unknown to the animal. If the reinforcement cessation is signalled by a previously differentiated (negative) stimulus, in response to its action the animals "loose the aim", what is revealed in a rapid complete reduction of all elements of the goal-directed alimentary behaviour. Obviously differentiation signal actualises the memory trace of "nonreinforcement" which was formed in the previous negative experience of the animal; this is revealed in accelerated inhibition of the alimentary motor reflex under extinction.

Animals↗
PubMedDate not supplied

[Neurochemical analysis of the brain structures in the formation of adaptive behavior in chicken embryogenesis].

Studies have been made on the rate of biosynthesis of high molecular and neurospecific proteins in the hippocamp and archistriatum of chick embryos during the formation of adaptive changes in motor activity under controlled experimental conditions and unmonitored occasional stimulation. It was shown that during uncontrolled sensory stress the rate of synthesis of high molecular and neurospecific proteins in the structures investigated is increased whereas during learning these changes are absent.

Adaptation, Physiological↗
PubMedDate not supplied

[The effect of glutamic acid on the defensive and feeding behavior of the snail Helix lucorum].

Behavioural effects of glutamic acid injection into the body cavity were investigated in the land snail Helix lucorum. An injection itself induced some non-coordinated defensive reactions leading to a partial withdrawal into a shell. The defensive tentacle reflex was facilitated probably due to an activation of the tentacle muscles. The defensive reflex of the pneumostome closure changed in different directions depending on the injected dose of glutamic acid. Feeding behaviour was inhibited by a high dose of glutamic acid. The most pronounced inhibition of the feeding behaviour was induced by N-methyl-DL-aspartic acid.

Animals↗