[Neurogenesis in the central nervous system and prospects of regenerative neurology].

Discovery of neural stem cells (NSC) providing homeostatic adaptive and injury induced neural regeneration in the CNS of adult mammals, including Homo sapiens, is the most prominent accomplishment over the recent period of neurobiology research. NSC are concentrated in two neurogenic zones - side walls of lateral ventricle (subventricular zone) and hippocampal dentate gyrus (subgranular zone). In addition, new neurons may develop from other undifferentiated cells scattered throughout various CNS regions. Neurogenesis in adult mammals is an intensive process that leads to renewal of interneuron populations in such brain regions as olfactory bulbs and hippocampus by 5 and more percent per month. Advances in regenerative neurobiology may serve the foundation for the development of totally new technologies of treatment brain and spinal cord, as well as retina and optic nerve injuries and diseases based on the stimulation of reparative neurogenesis, design of conditions permissive for regeneration of nervous and glial cells and growth of nervous fibers, and on blocking factors inhibiting those two former processes.

[Specific ototoxic effects of monomycin in immature animals].

Dynamics of the hearing function was evaluated using immature animals based on the SSCP data. Morphological characteristics of the cochlear auditory ganglion were studied after administration of therapeutic doses of the ototoxic antibiotic monomycin. Untreated animals served as controls. The results of morphofunctional investigations were evaluated in comparison with the similar data obtained in adult cats after injection of the same doses of monomycin.

[An experimental model of focal brain ischemia in rats based on the endovascular microsurgery].

An endovascular model of focal brain ischemia in rats with controlled duration of reperfusion of 1h has been studied. The reliability of experimental model for localization and volume of ischemic lesion (basal ganglia, hippocampus, parietal-temporal regions; the volume of lesion focus on MRI T2-weighted image (T2-WI) in the first day after brain ischemia 146.4 +/- 44.7 mm3) has been worked out. We conducted the clinical monitoring including assessment of neurological deficit, behavioral tests and performed MRI of the brain on 1st, 5th and 10-17th days after the occlusion of middle cerebral artery (MCA), including regimes of diffusion-weighted image (DWI) and T2-WI, and carried out a histological study of the brain. The regress of neurological deficit was seen on the 14th day after surgery. Behavioral tests revealed the reduction of movement activity of animals in the case group 7 days after the MCA occlusion. Compared to the first day after surgery, the decrease of volume lesion focus on DWI and T2-WI was observed on the 5th day (p < 0.05) as well, with the following decrease to the 10-14th days. The histological picture in the lesion foci corresponded to the brain infarction on the 5th and 14th days after surgery.

[Spinal cord regeneration in rats after thoracic segmentectomy: growth and regeneration of nerve fibers].

As it was described in a previous paper (Morphology, 2005, v.127, Iss. 2), spinal cord (SC) consolidation after thoracic segmentectomy in rats took place via connective tissue scar formation in the area of trauma, which was accelerated when SC defect was filled with by the collagen gel (Spherogel). In this paper, on the basis of semithin section analysis and transmission electron microscopic study, it was shown that regenerating nerve fibers crossed the connective tissue within the formations, which were structurally identical to peripheral nerves. In the zones of rarified SC substance, caudally to the site of trauma, myelination of growing axons was realized by glial cells without the formation of the nerve truncs. In the white matter, within the fasciculi of SC lumbar segments, multiple thin regenerating fibers were seen in the area of degenerated myelinated nerve fibers.

[Spinal cord regeneration in rats after thoracic segmentectomy: restoration of the anatomical integrity of the spinal cord].

Spinal cord (SC) segmentectomy was performed at ThX level in 28 rats. The scar formation in place of surgery and the degree of restoration of anatomical integrity were studied in control rats (group I) and in rats, in which SC defect was replaced by either Spherogel neuromatrix (group II) or Spherogel containing dispersed embryonic nerve cells (group II). While in group I rats by weeks 1-2 SC defect was filled with fibrin masses, in rats of experimental groups II and III the formation of connective tissue scar was found by the same time. By weeks 10-11 these animals demonstrated partial restoration of motion in three joints of the hindlimb. In the scar tissue and in adjacent SC zones numerous regenerating thin myelinated nerve fibers were found. They were clearly demonstrated in the zones of cranial and caudal borders along the whole distance until the appearance of typical tissue of SC. In slides from the animals of control group, thin myelinated nerve fibers were found only in close proximity to SC substance, while in the scar tissue and in the cellular bands of the intermediate zone nerve fibers were scarce.

[Mechanosensitive ion channels]. / Mekhanosensitivnye ionnye kanaly.

The article concentrates on the concepts of mechanosensitive ion channels that are present in practically all cells of an organism. Considered are kinetic scheme and activation principles of mechanic-sensitive ion channels. The forces affecting those channels are discussed in detail. The qualities of the channels in lipid monolayer, bilayer and real cell membrane are under consideration. Discussed are various models that analyze possibilities of channel opening depending on the membrane tension. Under discussion are the data received from studying single channels, currents in whole-cell configuration and cloned channels built into bilayer, liposomes and membrane blebs. Problems of transmitting mechanic energy to the channel through the bilayer and through the cytoskeleton are investigated. Inhibitors and activators of mechanosensitive ion channels are mentioned and their effects are considered. The functional classification of mechanosensitive ion channels is given. Described are cation SACs, potassium SACs, Ca(2+)-sensitive and Ca(2+)-insensitive SACs, anion SACs, nonselective SACs and SICs. It is proved that mechanosensitive ion channels can produce considerable currents enough to change the cell electrogenesis.

[Ion mechanisms of the mechanoelectrical feedback in myocardial cells]. / Ionnye mekhanizmy mekhanoélektricheskoi obratnoi sviazi u kletok serdtsa.

This article is dedicated to the mechanism of mechano-electric feedback in heart. The evidence is briefly discussed on organ, tissue, cell and in details on cell membrane levels in case of application of one of applied mechanical stimulus to cardiomyocytes. Stretch of the hole heart or its tissue fragment causes quick starting repolarization of action potentials (AP)/monophasic action potentials (MAP), shift of AP/MAP plato to higher negative zone, appearance of peaks of stretch-induced depolarization (SID) on final phase of AP/MAP repolarization level, which are overgrowing into extra AP/extra MAP. Mechanical events (changes in length and force of contractions) change electrical processes by means of direct influence on cell membrane via stretch activated channels (SAC). Cardiomyocytes, isolated from animal atrium and animal and human ventricular are responsible for the stretch of depolarized membrane, prolongation of AP and appearance of extra AP (extra systoles). Analysis of experiments, conducted following the patch clamp method in whole cell configuration, shows that the main cause of that mechanical events is SAC current--ISAC. During negative potential ISAC is determined by incoming into the cell sodium ions and is negative. Negative ISAC is changing final phase of AP/MAP repolarization and causes SID, which is overgrowing into extra AP (extra systoles), in case that SID exceeds threshold. Fast AP repolarization and AP plato shift into higher negative zone is related to positive ISAC (living potassium ions through SAC), activation of IK and reduction of ISAC. Activation of ISAC and arrhythmia induction require lower mechanical stimulus for hypertrophied cardiomyocytes, in comparisment to healthy ones. Hypertrophy of cardiomyocytes can lead to expression of SAC therefore increasing channel density and ISAC maximum amplitude. In this article is discussing data, acquired by means of direct measurement of conduction of single SAC on the background of mechanical stimulation of the cardiomyocytes membrane. It contains characteristics of the estimated SACs. It is shown that blocking of conduction of ions through SAC prevents mechanically induced arrhythmia in healthy and hypertrophied cardiomyocytes, which transforms the problem of mechano-electric feedback in heart from purely fundamental into clinical one.

[Biomedical aspects of health preservation strategy: role of catecholaminergic neuronal populations]. / Biomeditsinskie aspekty strategii sokhraneniia zdorov'ia: rol' katekholaminergicheskikh neironal'nykh populiatsii.

Lifestyle, environmental factors, genetics, and medical care are the main factors that determine the health status of man. Of particular attention are biological mechanisms ensuring the body's adaptation to constantly changing environmental conditions. The noradrenergic neuronal populations, the sympathetic nervous system in particular, modulate metabolic processes and supports a variety of activities, making them relevant to changing living conditions. There is a clear correlation between the life span and the number of sympathetic nerve cells functioning during postnatal ontogenesis. The exposures that reduce the activity of peripheral and central noradrenergic neurons and slow down aging processes in them loosen the relationships between the inner and outer world to prevent hyperactivity and to prolong life.