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Biomedical subjects

A G Frolov

Publications and source records attributed to A G Frolov.

At least 19 recordsLinked to original sources
PubMed2005

The effects of systemic administration of selective antagonists of dopamine D1 and D2/D3 receptors on food-related and defensive (escape responses) conditioned paw-placing responses in cats.

Experiments were performed on cats to study the effects of systemic administration of antagonists of dopaminergic transmission on food-related and defensive (an escape response) operant conditioned reflexes acquired on the basis of the innate response of placing the forepaw on a support. Selective blockade of D1 receptors with SCH23390 (0.005-0.1 mg/kg) completely and selective blockade of D2/D3 receptors with raclopride (0.1-0.25 mg/kg) partially suppressed both reflexes. At these doses, both blockers had stronger actions on the defensive conditioned escape reflex than the food-related reflex: SCH23390 had significantly stronger inhibitory effects on both reflexes than raclopride.

Animals↗
PubMed2003

Instrumentalization of movements evoked by stimulation of the motor cortex by food reinforcement in dogs.

The possibility that hindlimb movements (elevations) evoked by stimulation of the corresponding contralateral area of the motor cortex could be instrumentalized by reinforcement with food was demonstrated, contradicting some previously published data. Operant movements (interstimulus voluntary high elevations of the hindlimb) were acquired as a result of consistent combinations: cortical stimulation - movement - food. Acquisition required more than 50-200 combinations. Delivery of food was accompanied by a click at exactly the moment at which the hindlimb reached the required height. The click became the food-related conditioned signal and served as a secondary operant reinforcement, which facilitated acquisition of the operant movement. These results support the view that the motor cortex can have an immediate role in forming "operant" temporary connections (motivation-movement) and that simple operant movements can be initiated via this arc.

Animals↗
PubMed1998

[A model of rat's urinary bladder tumor induced by subcutaneous injection of N-butyl-N-(4-hydroxybutyl)-nitrosamine].

A model of urinary bladder tumor was developed in the rat by subcutaneous injection of N-dibutyl-N-(4-hydroxybutyl) nitrosamine. A direct dose-tumor frequency correlation was established. Maximum effect (100%) was recorded with administration of 70 mg of the carcinogenic agent twice a week, for 3 months. Among neoplasms induced were transitional-cell and in situ carcinoma, and multiple papilloma of the bladder. Carcinogenesis was found to involve a significant rise in the activity of urinary beta-gluco-uronidase which may be used as a diagnostic testing procedure.

Animals↗
PubMed1995

[An experimental study of the tissue compatibility of titanium implants coated with hydroxyapatite and aluminum oxide by plasma spraying].

The reaction of bone tissue to implantation of cylindric titanium implants sprayed with hydroxyapatite and aluminum oxide was studied. The coating was characterized by a high biological histocompatibility. The elements of cellular reactions specific for foreign bodies were absent, this permitting us to refer such coating to bioactive materials. The strength of fixation in the bone was compatible to the strength of osseous tissue adjacent to bone tissue implant. The coating may be used in oral implantology, traumatology, and orthodontics.

Aluminum Oxide↗
PubMed1992

[The lithium carbonate promotion of urothelial tumors in rats induced with N-butyl-N-(4-hydroxybutyl)-nitrosamine].

The effect of lithium carbonate on promotion of N-butyl-N-(4-hydroxybutyl)-nitrosamine-induced bladder tumors in rats was studied. Lithium carbonate acted as promoter in bladder carcinogenesis resulting in a 6-fold increase in the tumor occurrence as compared to controls. The experiments with sequential injection of the agent showed its promoting effect to be most apparent within 3-6 months following exposure to the carcinogen.

Animals↗
PubMed1990

[Effects of forced diuresis on butylbutanolnitrosamine induction of bladder tumors in rats].

The study was concerned with the effect of forced diuresis on the frequency and morphologic pattern of bladder cancer induced with butylbutanolnitrosamine in rats. An 1.6 times increase in diuresis was followed by inhibition of bladder carcinogenesis, resulting in a 2.5-fold decrease in the tumor rate as compared to controls. The data obtained confirm the earlier suggested hypothesis of "urothelial contact" as well as epidemiologic data.

Animals↗
PubMed1990

[The dynamic changes in somatosensory input into the cortical motor area after damage to the somatosensory cortical zones in dogs].

Dynamics of changes in the somatosensory evoked potentials (EPs) in the foreleg motor cortex (MI) was studied in awake dogs in chronic experiments following lesions of the forelimb area in the somatosensory cortex (SI) or in area 5. Cortical ablations reduced the amplitude of the primary positive-negative wave of the EPs in ipsilateral MI down to 28-63% of the original one. Within three weeks recovery of the EPs was insignificant or was absent at all. So there was no correlation between the EPs changes and spontaneous recovery of precise avoidance movements of the foreleg which takes place two weeks after local ablation of the SI. After area 5 lesion the EPs in the MI did not recover in spite of complete recovery of the EPs in the adjoining area of SI after its initial reduction down to 53%. The long-lasting EPs reduction was apparently a result of destruction of somatotopic sensory inputs from SI (or area 5) to MI, since EPs in MI of the intact hemisphere and in the hindlimb area of MI on the side of the lesion either did not change or recovered during one or two weeks.

Animals↗
PubMed1985

[Role of gastrin in the development of gastrointestinal disorders in patients with acute intestinal infections].

Examination of 85 patients with acute intestinal infections (food toxoinfections of medium gravity) of non-established etiology, salmonellosis and acute dysentery) has revealed a significant increase in gastrin concentration in blood plasma both in the acute period and convalescence. The highest increase in blood plasma gastrin concentration was recorded during convalescence, particularly in patients with acute dysentery. Based on the data obtained, the conclusion is made about the involvement of gastrin in the development of gastrointestinal disorders and formation of the adaptation syndrome in acute intestinal infections.

Acute Disease↗
PubMed1983

The effect of instrumentalization of inborn reaction on its transformation into contrary directed escape response in dogs and the problem of reinforcement.

Transformation of inborn reaction of leg flexion into conditioned escape response of leg extension was studied. The model of the so called precise reflex was used. A dog could avoid or escape the shock applied to the paw by placing this paw in a narrow ,,safety zone located at a definite height above the floor. When the shock is applied to the paw located below this zone, the escape response is flexion, i.e., it coincides with the inborn reaction. When the paw is lifted above this zone, the escape response is extension, i.e., it is opposite to the inborn response. Success of such extension response acquisition depended on the sequence of training conditions. The dogs of Group I at the beginning were accustomed to escape from shock by lifting the paw into the ,,safety zone, i.e., inborn reaction was instrumentalized. A subsequent formation of conditioned extension was extremely difficult and it did not became strong in spite of a very long training. Lowering the paw into the ,,safety zone was usually slow. The dogs of group II were trained from the very beginning to escape from shock by leg extension. Contrary to the results obtained on group I this conditioned response was perfectly established. It was formed rapidly, only when active extension was paired regularly with termination (during extension) of the shock. It is suggested that conditioned connection from one functional center to another is formed and becomes stronger if evoked activity of the first center decreases during (or immediately after) the excitation of the second center.

Animals↗
PubMed1982

Biomechanical study of the mechanisms of postural adjustment accompanying learned and induced limb movements in cats and dogs.

Trajectories of the center of pressure and center of gravity projections were studied in dynamic conditions during learned movement and movement evoked by the motor cortex stimulation (induced movement) in dogs and cats. The learned movement began with initial displacement of the center of pressure towards the limb performing movement. It corresponded often with initial increasing of the performing limb pressure on support and it was a reason of initial acceleration of the center of gravity in the opposite direction. Induced movement began with decrease of the performing limb pressure on support. It could result in the initial displacement of the center of pressure in the wrong direction but usually it was corrected quickly and the general trajectories of the center of pressure and the center of gravity were similar to ones observed during learned movement. Results suggest different programs for movement and appropriate postural adjustment.

Animals↗