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Biomedical subjects

I V Soboleva

Publications and source records attributed to I V Soboleva.

14 recordsLinked to original sources
PubMed1992

[Interaction of human thrombin I fragment, prethrombin I, and alpha-thrombin with tissue thromboplastin].

The binding of 125I-labeled prothrombin fragment I. prethrombin I and alpha-thrombin to native and papain-treated tissue thromboplastin in the presence of CaCl2 of EDTA was studied. The experimental curves plotted in the Scatchard coordinates testify to the presence in thromboplastin of two types of fragment I binding sites: those with a high (Kd = 7.6 x 10(-6) M) and moderate (Kd = 1.3 x 10(-8) M) binding affinity. The parameters of fragment I binding and their changes reproduced, for the most part, the mode of prothrombin binding observed in previous studies. The experimental results provide indirect evidence in favour of a hydrophobic role of Ca(2+)-dependent binding of prothrombin fragment I to thromboplastin. The binding of prethrombin I was nonspecific and Ca(2+)-independent, whereas alpha-thrombin showed a relatively high level of nonspecific electrostatic binding which was competitively inhibited by Ca2+. Thromboplastin proteins interacted (both directly and in a Ca(2+)-independent fashion) with all the prothrombin derivatives under study.

Binding Sites↗
PubMed1989

[Interaction of human prothrombin with tissue thromboplastin].

The binding of 125I-labeled human prothrombin to native and papain-treated tissue thromboplastin in the presence of CaCl2 or EDTA was studied. The Scatchard plots for the protein binding suggest the presence at thromboplastin surface of two types of binding sites, high affinity [Kd(app) = 7.4.10(-8) M] and moderate affinity [Kd(app) = 7.9.10(-5) M]. The removal of Ca2+ did not influence the Kd (values for these) sites but markedly reduced their number. Proteolysis by papain caused a decrease in the affinity of high affinity sites without affecting the Kd values of the moderate affinity sites yet caused a proportional increase in the number of both high and moderate affinity sites in the presence of Ca2+. At low prothrombin concentrations a positive cooperativity of protein binding at high affinity sites in the presence of Ca2+ was observed.

Calcium↗
PubMed1981

[Effect of modifications of the protein moiety of thromboplastin (factor III) on its activity].

The role of protein moiety of tissue thromboplastin under its specific enzymatic modification and the effects of some protease inhibitors were studied. Treatment with HCl, pepsin and papain was followed by a decrease in the biological activity of thromboplastin, which was unaffected by the inhibitors of some proteolytic enzymes (DFP, monoiodoacetate and o-phenanthroline). It was assumed that the protein component of thromboplastin fulfils a structural function in the assembly of the lipoprotein matrix, on which surface the enzymatic reactions of blood coagulation are known to occur.

Humans↗
PubMedDate not supplied

[The neuronal organization of a focus of conditioned excitation in the cat sensory-motor cortex].

The activity of single units in the focus of conditioned excitation was studied during defensive conditioning to direct electrical stimulation of the cat sensorimotor cortex. Reorganizations of spike activity set in during the period of reflex elaboration, were manifest in the increased number of excited neurones and those which respond both to the conditioned and unconditioned stimuli. In the course of elaboration, the inhibitory phase of unit responses to direct electrical stimulation of the sensorimotor cortex was reduced, while the frequency of background unit spike activity was enhanced. Acute extinction of the reflex restored the initial duration of the inhibitory phase and reduced the frequency of the background activity.

Animals↗
PubMedDate not supplied

[Organization of interneuron interaction in the cerebral cortex of cats learning to distinguish visual stimuli].

Focal and impulse activity of neurones, recorded in pairs with one microelectrode, was studied in the field 18 of cat visual cortex, during learning of visual differentiation of shaped stimuli--light strips with different orientation one towards the other. Differences were found between functional properties of neighbouring visual neurones before learning and in learning dynamics. During learning, independently of visual signal stimuli orientation, reaction patterns of the same type were formed in neighbouring visual neurones.

Action Potentials↗
PubMedDate not supplied

[Circulation of soluble fibrin monomer in the body].

Circulation of administered monomeric fibrin was studied in comparison with fibrinogene. Bovine monomeric fibrin circulated in rabbit blood within several days and quickly penetrated into lymph. Period of half-elimination of monomeric fibrin from rabbit blood was 18 hrs and the period of half-elimination for fibrinogene constituted 30 hrs.

Animals↗
PubMedDate not supplied

[Participation of neurons of the associative cerebral cortex in the formation of a conditioned defensive reflex].

Neuronal activity was recorded in the frontal lateral gyrus of waking unanesthetized cats in the process of defensive conditioning. It has been found that at the beginning of learning, the frequency of neuronal prestimulus impulse activity was the highest and the ratio of neurones with tonic excitatory responses to conditioned stimulus was maximal. In the course of reflex elaboration, the frequency of prestimulus neuronal discharges decreased, and tonic excitatory responses gave place to phasic ones. In consolidated reflexes, conditioned responses of neurones in the associative cortex were mainly inhibitory; the correlation of the discharges frequency of the neighbouring nerve cells increased comparatively with the beginning of learning.

Animals↗
PubMedDate not supplied

[Neuronal organization of a focus of unconditioned excitation in the cat sensomotor cortex].

The impulse activity of sensorimotor area neurones, situated near the point of its direct electrical stimulation used as a reinforcing stimulus, was studied in cats. The rearrangement of impulse activity during reflex elaboration consisted in the reduction of frequency of background activity, in changes in the character of neuronal reactivity and of the pattern of response to the signal and reinforcing stimuli. During the reflex elaboration the percentage of polymodal neurones increased. Tonic response to the conditioned sound stimulus changed into a phasic one. The inhibitory component of responses to direct electrical stimulation of the sensorimotor cortex became more protracted.

Animals↗