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Biomedical subjects

V N Chikhman

Publications and source records attributed to V N Chikhman.

At least 19 recordsLinked to original sources
PubMed2003

[Computer morphometric analysis of dendrites of the type II Dogiel neurons].

Dendrites of type II Dogiel neurons (the local receptors) stained with silver nitrate impregnation by Bilschovsky-Gross method, were analyzed with computer morphometry in cat large intestine. The following parameters have been measured: an area of dendritic receptor field, total area of all receptor elements and total length of all receptor branches. Significant individual variability was noted in the values of these parameters: the maximum value exceeded the minimum one by a factor of 41, 29 and 45, respectively. No correlation between these three parameters has been found. It is suggested that the morphological diversity of dendrites found in this study may serve as a basis of the functional variability of type II Dogiel neurons.

Animals↗
PubMed2003

[Optical-geometrical parameters and perception threshold of the fragmented contour figures].

The thresholds of recognition of line drawings of common objects were measured using the Gollin-test procedure, in which separate random line fragments are displayed cumulatively up to the point of recognition. It was shown that the mean percentage of contour displayed at threshold recognition for different images was always about 12.5%, despite inter-subject variability between 5% and 25%. The comparative and spatial-frequency analysis of the geometrical parameters of images was carried out for different levels of fragmentation (before threshold, at threshold, and for the complete contour). The magnitude information of the Fourier domain image of figures was characterized by maximum at low and high levels of fragmentation, but at recognition threshold fragmentation it was characterized by minimum variability.

Adolescent↗
PubMed2002

[Comparison of postural and motor components in instrumental defense learning in dogs].

In 6 dogs, during the period of a complete formation of the "co-ordination" program of defensive reflex associated with maintaining flexion of the left hind-limb, the diagonal pattern of posture readjustment occurred very infrequently. Only during the period of a complete automation of the motor habit, a constant occurrence of the diagonal pattern of posture readjustment was observed in all realisations. These findings suggest that the diagonal pattern of posture readjustment occurs much later than the motor pattern necessary for solving the instrumental task.

Animals↗
PubMed2002

[Instrumental behavior in the activation or blockade of the neostriatum muscarinic receptors].

In four dogs, microinjections of carbacholine enhanced the tonic component and inhibited the physical component of the instrumental defence reflex, put in order the posture, and increased its components' amplitude. Microinjections of raclopride yielded a similar though a less obvious result. Differentiation stimuli provided the greatest effect of both substances. A sharp improvement occurred in differentiation of sound signals. Microinjections of pyrenzepine yielded an opposite result. The data obtained are explained proceeding from the idea of a presence of the neostriatum's two efferent outputs exerting opposite effects on their targets, and the role of muscarine and dopamine receptors in their triggering and blockade.

Animals↗
PubMed2000

[Blocking of cold paralysis of physiological functions].

For more than 100-year history of studying hypothermia a rewarming of a cooled organism was always considered as the only method of restoring the cold-paralysed physiological functions and the vital activity of an overcooled organism of homoiothermal animals and humans. The paper gives the results of applying the method developed at our Laboratory, of restoring the cold-paralysed important physiological functions after a continuous cooling of rats, without rewarming the animals.

Animals↗
PubMed2000

[Innervation of the humerus metaepiphysis in newborn and one year old children].

Analysis of home and foreign literature on metaepiphyseal cartilage innervation and blood supply was presented, data on these organ diseases substantiate theoretical and clinical significance of the study was performed. Using macro-microscopic preparation, histological study, automatic image analyzer branches of humerus proximal metaepiphysis were shown to originate from axillary and subscapulary nerves. Nerves and vessels penetrating in the cartilaginous canals form neurovascular complexes. Cartilaginous canals are located unevenly. Nervous structures were found in the canals and their characteristics was given.

Growth Plate↗
PubMed2000

[Quantitative analysis of morphogenesis of local nerve plexuses forming in tissue culture].

Discrete stages of formation of nervous plexuses in the culture of isolated neurons of a mollusc were analyzed autonomically. Area of plexus expansion (S1) and area, occupied by nerve structures (neurites and neuron bodies) were determined. It was demonstrated that despite intensive radial growth of peripheral neurites and S1 growth the density of plexus (S2/S1) was not changed. Relative acceleration of plexus expansion (as compared to S2 growth) registered on 40th and 50th hrs of cultivation indicates the absence of necessary cells in the plexus and development of contacts with adjacent local plexuses. Scanning of lamellar structures revealed submembranous aggregation of cytoskeleton apart from longitudinally directed cytoskeletal bands, which prevents one of the ways of neurite ramification. Elimination of lamellae between cytoskeletal bundles leads to formation of several neurites.

Animals↗
PubMed1999

[The structure of the white pulp of the spleen and the peripheral blood indices in rats under increased muscle activity].

The white pulp structure was studied in rat spleen white pulp in conditions of increased muscle activity as well as certain parameters of peripheral blood. 36 male outbred albino rats were involved. Experimental rats were subjected to the increased physical load (everyday swimming seances lasting from 10 to 40 hrs during 4 weeks). The number of erythrocytes, leukocytes and level of hemoglobin were determined in peripheral blood. Perimeter squares and density of lymphoid nodules (LN) and marginal zone (MZ) as well as LN minimal and maximal diameter and MZ minimal and maximal width were determined in histological sections prepared at the level of the organ portae using TV-computer set. Besides, marginal sinuses width were measured in nine sites in every LN as well as the capsule thickness in three sites and at the level of portae. The data obtained indicate that increased muscle activity causes reorganization of red and white pulp in the direction of growth of the red pulp square which is associated with the increase of erythropoietic function. The appearance of lymphoid nodules with germination centres indicates lymphocytopoietic function intensification while the significant increase of marginal zone morphometric parameters witnesses its participant in primary immune response. High correlation between certain blood indexes and the parameters of lymphoid nodules and marginal zones supports these data.

Adaptation, Physiological↗
PubMed1998

[The model of adaptive primary image processing].

A computer model of adaptive segmentation of the 2D visual objects was developed. Primary image descriptions are realised via spatial frequency filters and feature detectors performing as self-organised mechanisms. Simulation of the control processes related to attention, lateral, frequency-selective and cross-orientation inhibition, determines the adaptive image processing.

Models, Neurological↗
PubMed1981

[Principles of temporal processing of spectral information during vowel perception].

Pairs of "one-formant pulses" with 10 ms onset-to-onset interval and highly different F values for the first and the second pulse (LH and HL pairs) were used in vowel identification experiment. Response distributions corresponding to these stimuli and to "stationary" two-formant and one-formant pulse pairs were compared to calculate the phonetic distance between stimuli. The results are in favour of low-pass filtering of excitation pattern with sampling at the stimulus offset.

Computers↗