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Biomedical subjects

M P Roshchevskiĭ

Publications and source records attributed to M P Roshchevskiĭ.

At least 19 recordsLinked to original sources
PubMed2003

[Current understanding of the pathogenesis of infectious diseases].

New experimental data in such research fields as molecular biology, biochemistry, genomics and others as well as the changes occurring in the medical-and-epidemiological situation in respect to a number of infectious diseases dictate the necessity to systemize and to revise the appropriate knowledge for the purpose of ensuring a more profound understanding of the processes providing a foundation for the relations within the system of "host--parasite". The article deals with modern aspects of investigating the pathogenesis of infectious diseases, i.e. issues of the genetic and of structural-and-functional organization as well as of regulation of the pathogenetic potential of microorganisms; and mechanism of antimicrobial protection of microorganisms including from the standpoint of evolutionary biology.

Communicable Diseases↗
PubMed2001

[Reflection of distribution of the epicardial ventricular potential on the dog body surface during electrical stimulation of the myocardium].

Electrical pacing of the apex, base, and free wall of the heart right and left ventricles, as well as the left ventricle's interventricular septum revealed that localisation of the ectopic focus determined the sequence of ventricular depolarisation, the site formation, and the pathway of displacement of the areas' positive and negative potentials and their extrema on the thoracic surface. Time of the mutual movement (inversion) of positive and negative zones on the body surface was found to depend on the pacing site in the wall of ventricles.

Animals↗
PubMed2001

[Effect of hypothermia on sequence of the ventricle epicardium repolarization in rabbits].

In anaesthetised rabbits at normal body temperature, the earliest ventricles' epicardial recovery occurs at the heart apex and adjacent left ventricle's surface whereas the latest one occurs at the epicardium of the right ventricle's base. A decrease in the mediastinum temperature to 32 degrees C reversed the recovery sequence. Following the cooling of the heart, the longest prolongation of the activation-recovery interval occurred at the heart apex area and the lowest one--at the right ventricle base.

Animals↗
PubMed1995

[The formation of cardiac-electric-field potentials on the surface of the heart and torso in vertebrate animals].

The comparative electrophysiological study of excitation process in heart with different types of organization have laid the foundation for solution of the problems of formation of cardioelectric field. It was shown, that the form of extracellular potentials on the epicardium correlated with different types of ventricle myocardial activation. Animals with the "flash" type of myocardial depolarization in most cases have the negative extracellular potentials in the greater part of the epicardial ventricular surface. Animals with the consecutive type of myocardial activation--the positive and biphase potentials. All myocardial layers (epicardial, intramural and endocardial) are electrophysiologically informative.

Animals↗
PubMed1990

[The dynamics of the form of the extracellular potentials and of the process of depolarization wave spreading in the intramural layers of the myocardium in dogs with experimental ischemia].

The reversal of directions and local delays or accelerations of the extracellular potentials evolution occurred at arrival of the depolarization wave after coronary occlusion in dogs. General patterns of directions of the activation spread changed relatively little when compared to normal. Apparently, in spite of the ligation of the left anterior descending coronary artery, ischemia was not achieved. There was some additional blood supply to the ischemic myocardium from deep collateral arterial branches. Therefore, the observed abnormalities of electrical potentials and the reversals of the depolarization wave direction only took place in local small zones of ischemic myocardium.

Animals↗
PubMed1988

[The electrical field of the heart in rats with spontaneous hypertension].

The body surface potential of the SHR rats' heart was differently distributed both at the beginning of ventricular activity and during the repolarization in 4- to 6-week- and in 8- to 11-month-old rats. The positive extreme moved cranially to the right in 4-6-week rats and cranially to the left in 8- to 11-month-old rats thus suggesting a predominance of the right ventricle function in young rats and the left ventricle hypertrophy in older ones. The primary character of the right ventricle hyperfunction in young rats SHR is considered as the 1st phase of the cardiovascular system response to genetically determined increase in the arterial pressure.

Aging↗
PubMed1979

[Sequence of the spread of excitation in bird heart ventricles].

Intramural multipolar technique revealed primary sites of excitation in the subendocardium of central areas of border line of the apical and middle thirds of the bird heart septum. From the zone of primary depolarization the excitation wave spread on the subendocardium of ventricles. A number of sites of negativity were observed over the epicardium. The main mass of myocardium of free walls and the lower two thirds of the septum are activated by means of myocardium of free walls and the lower two thirds of the septum are activated by means of multifocal depolarization. The base third of the septum is the last to be activated. These features of the excitation of bird myocardium can be accounted for by the special character of distribution of the Purkinje fibers in the muscles of myocardium ventricles.

Animals↗
PubMed1977

[Experimental study of successive range of excitation of the heart ventricles].

The succession of excitation spreading about the cardiac ventricles was studied in 28 dogs using the intramural multipolar technique. The primary foci of excitation were found in the zones of the subendocardium on the borderline between the lower and middle portions of the left side of the ventricular septum, and under the base of the anterior papillary muscle on the right side of the ventricular septum. The excitation of the interventricular septum throughout its thickness occurs first of all in the anterior part of its mid-portion where the depolarization waves moves exclusively from left to right. Lastly the posterior lateral subendocardial layers of the bases of the free walls and the upper portion of the ventricular septum are depolarized. In some parts of the interventricular septum and of the left free wall the excitation wave first reaches the zones located deeply under the endocardium, then spreads towards the endo- and epicardium, changing its direction several times.

Action Potentials↗
PubMed1977

[Chromotopography of ventricular depolarization in northern reindeer].

With the aid of intramural multipolar technique, the sequence of the heart ventricles depolarization was studied in deer. Electric potentials were led from 1500-1700 points in the myocardium. Primary foci of excitation were revealed in the subendocardium of the caudal and cranial areas of the middle third of left and cranial portions of the upper third of right side of the interventricle partition. Within 5-10 msec. the ventricles subendocardium is wholly involved into the wave of depolarization. For 10-20 msec., the main lot of free walls, the central and upper portions of the partition, are excited. This period is characterized by spreading of the depolarization wave from numerous foci of excitation in all directions. Last the upper portions of the pulmonary artery output cone (40-45 msec.) and portions of the interventricle partition adjacent to the ventricles basis (45-50 msec.), become excited.

Animals↗