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Biomedical subjects

V A Safronov

Publications and source records attributed to V A Safronov.

At least 19 recordsLinked to original sources
PubMed1991

[Pathologic muscle coactivation after injury of the brachial plexus].

As many as 58 patients with injury to the nerve trunks of brachial plexus were examined. As a consequence of the generation of nerve fibers after injury to brachial plexus or after surgical treatment, marked coactivation of muscles including antagonistic ones may not infrequently occur in patients at voluntary efforts. That coactivation may give rise to a noticeable decrease of the power effect of limb muscles. It may turn out at the same time that the same motoneurons act as representatives in different muscles. The most probable mechanism of pathological coactivation is the branching of axons during their branching into separate little branches each of which can, via the nerve membranes, grow towards different muscles including antagonistic ones. The branching of nerve fibers towards different muscles is likely to occur at anastomoses of the nerve trunk membranes. Thus, peculiar "nerve anastomoses" may occur. Via those anastomoses, nerve impulses have a possibility of "flowing" from one nerve to the other one. The phenomenon described should be taken into consideration in reconstructive surgery on brachial plexus.

Arm↗
PubMed1988

[Association between synaptonemal complexes of sex and autosomal bivalents in male tx/ty mice as a possible cause of their sterility].

Electron microscopic study of total preparations of synaptonemal complexes of spermatocytes I from sterile heterozygous male mice--t12/tw18; tw5/twPa-1; twPa-1/tw18 was performed. T/tw18 and C3H/N fertile heterozygotes were used in each variant as control. The cells are karyotyped in all experiments, as based on the measurements of the length of 19 SC autosomes and SC sex complex. All sterile compounds (spermatocytes) demonstrate high frequency of different types of associations (72%) between sex chromosomes and the autosome 17 carrying a chromosomal aberration in the region of the T-locus. The heterozygotes tx/ty used in our experiments show no disruption of chromosome synapsis, when even studied under electron microscope, though some atypical changes in the ultrastructure of chromosome axes and frequent atypical associations of the axes of XY-sex bivalents in sterile heterozygous animals exist.

Alleles↗
PubMed1988

[Neuromuscular reactions to passive movements of the arm in patients with reactive states].

The results of clinical and physiological investigation of motor activity in 30 patients with various forms of reactive states with motor inhibition are discussed. Muscular tone changes and polymorphic neurologic signs were common for all the patients. Electromyography and mechanography revealed muscular dystonia, spasticity, rigidity and different responses to muscle stretching. All pathologic organic-like signs disappeared while clinical conditions of neurotic patients improved, hence, these are regarded as functional in nature.

Adult↗
PubMed1988

[Voluntary activity of the neck muscles in patients with spastic torticollis].

The authors investigated the characteristics of motor disorders in patients with spastic torticollis. The study involved registration of volitional tensions of the neck muscles in isometric conditions, i.e., when the patient's head was rigidly fixed with regard to the body. Using a tensometric dynamometer the following three moments of force were measured: one responsible for bending the head forward or backward; the second, for bending the head to the right or left shoulder; and the third, for turning the head round the longitudinal axis. The electrical activity of the neck muscles was recorded with the help of surface electrodes. It has been established that the development of volitional efforts by the neck muscles under isometric conditions is difficult or impossible if directed to the side where the patient's forcible turn of the head is directed.

Chronic Disease↗
PubMed1984

[Synaptonemal complexes in mammals. I. The nature and mechanism of the formation of centric chromosome fusions (Robertsonian translocations)].

The nature and mechanism of formation of chromosomes' centric fusion were studied in mammals using the spreading method and silver staining of pachytene chromosomes. The male mice carriers of Robertsonian translocations Rb (8, 17) 1IEM, animals with standard karyotypes and F1 hybrids were used. It was concluded that the centric fusions resulted from translocation events and do not differ from other simmetric structural rearrangements of the exchange types.

Animals↗
PubMed1979

[Effects of electric stimulation and destruction of the centrum medianum of the optic thalamus in patients with akinetic forms of parkinsonism].

Results of electrostimulation and destruction of the median centre of the thalamus in 15 patients with parkinsonism and in 7 patients with uncontrollable pain are presented. Reactions of activation and inhibition in the psychoemotional, somatic and vegetosensory spheres in response to the stimulation are described. Data on bioelectrical activity changes in the cortex of the large hemispheres are presented. Special studies of the effect of the median centre destruction on the muscular tone and tremor were carried out. In the akinetic forms of parkinsonism the effect of reactivation after the median centre destruction was found to be of little clinical importance.

Cerebral Cortex↗
PubMed1977

[Gamma rigidity in parkinsonism].

The paper presents the results of the study on a muscle tension in patients with parkinsonism. The great role in the maintenance of the motor tonic activity in parkinsonism is played by an increased excitability (of a static type) of the receptors of the muscle length. The assumption is made that an increased sensitivity in these receptors is the result of the increased fusiomotor activity. The author discusses a possibility of changes in the structure of intrafusal fibres in spindles of the muscle due to which these receptors can preserve an excited state for a long time.

Humans↗
PubMed1975

[The reflex on shortening (the Westphal phenomenon) in deforming muscular (torsion) dystrophy].

By the aid of an objective test the authors studied the reflex to a shortening (the Westphal phenomenon) which is a typical symptom of deforming muscular dystrophy, reflecting disorders of the muscular tone. It was demonstrated that prior to a development of a muscular spasm there were changes of the muscular activity due to an integration of excitation. It is being supposed that muscular spasms and dystonic hyperkinesis are generated on a spinal level. A disappearance of the Westphal phenomenon following operations on the basal ganglia, may indicate to the fact that the leading role in the genesis of this phenomenon belongs not only to the segmentary spinal apparatus, but to the supraspinal influence from the stem-subcortical brain structure.

Adolescent↗