Biomedical subjects

N N Mel'nikova

Publications and source records attributed to N N Mel'nikova.

At least 19 recordsLinked to original sources

PubMed2006

[Restoration of microcirculation in the brain during ischemia].

The work shows that, after slinging two carotids in rats, the blood pressure in the circle of Willis decreases to approximately 40 mm Hg. The developing ischemia is accompanied by a mass adhesion of leukocytes to the walls of the brain venules and smallest veins. In two hours after slinging, the blood pressure in the vessels of the circle of Willis decreases to 16-20 mm Hg. The rate of adhesion increases abruptly. In these vessels the leukocyte conglomerates are formed which results in complete occlusion of the vessels and the death of animals. These processes are shown to be reversible. The insertion of 4.0-4.5 ml of plasmosubstituent polyglucin into the vessels of the circle of Willis "washes away" the leukocyte conglomerates as well as a part of adhered leukocytes and restores the blood flow in the venules and smallest veins for 10-15 min.

Animals↗

PubMed2006

[Mechanisms of disrupting the microcirculation in the brain during deep hypothermia development].

The number of the acts of leukocyte adhesion per unit of the vessel length was shown to increase gradually in the venous brain vessels during gradual cooling of the white rat from the body temperature in the rectum of approximately 37 to 13.5 +/- 0.2 degrees C. Upon a very deep hypothermia at the level of body temperature of 15 degrees C, the adhesion ofleukocytes to the walls of the brain microvessels gains a mass character. As the body temperature decreases to 13.5 +/- 0.2 degrees C, the respiration gets arrested. This coincides with an aspecially abrupt increase in the number of the acts of adhesion and with stretching the venules and smallest veins. The dynamics of these phenomena resembles the development of the mass adhesion of leukocytes during various kinds of hypoxia. There are reasons to believe that the adhesion of leukosytes during hypothermia disrupts the microcirculation and provokes the development of hypoxia in the cooled brain.

Animals↗

PubMed2006

[The specific features of bacterial isolation and drug resistance of Mycobacteria in extrapulmonary tuberculosis].

The reduced viability and enzymatic activity of the pathogen from the foci of extrapulmonary tuberculosis are twice more frequently than those in pulmonary tuberculosis. The isolation of mycobacterial L-forms and the use of polymerase chain reaction significantly enhance the efficiency of the etiological diagnosis of extrapulmonary tuberculosis. There are extremely poor trends for drug resistance to develop in mycobacteria, in 2005 the rate of which was 92.5% in pulmonary tuberculosis and 83.4% in extrapulmonary tuberculosis. However, multidrug resistance is much less common in extrapulmonary tuberculosis than in pulmonary tuberculosis; the rates were 33.9 and 73.9%, respectively. Levofloxacin resistance was also completely preserved so the reserves for the treatment of extrapulmonary tuberculosis are higher than those in pulmonary tuberculosis.

Antitubercular Agents↗

PubMed2004

[The role of leukocytes in microcirculation dynamics in the norm and pathology].

The physiological functions grow to be more perfect and complicated in the process of evolution. However, a developing function could display some evidence of regress and, in certain cases, it can trigger serious diseases including autoimmune ones. Conventionally, we refer to the above cases as to "errors" of evolution. The present case study deals with a negative factor of leukocytes in the cerebral microcirculation. Leukocytes were shown, experimentally, to inhibit the capillary blood flow owing to their big volume (2-2.5-fold more versus that of erythrocytes). An increasing trend to adhesion due to hypoxia is responsible for shaping of leukocytes' conglomerates, which cause the occlusion of venules and of the smallest cerebral veins. It entails the effect known as "no re-flow" resulting in death.

Animals↗

PubMed2004

[The dynamics of leukocyte adhesion to the endothelium pial venules under massive blood loss].

The dynamics of leukocytes adhesion to brain microvenules endothelium of Wistar rats were studied under acute massive blood loss. Using the method of vital videomicroscope study of the influence of the influence of the blood volume reduction on the leukocyte-endothelium interaction is investigated. We studied vessels of the diameter under 30 mcm. It is shown that under progressing reduction of the system arterial pressure under 60 mm Hg, the number of leukocytes adhesion to venules' wall reached 20 +/- 3 on 100 mcm, but in terminal stage such acts are the greatest. It is supposed that as a result massive blood loss leukocytes turn out to be the direct reason of the deep pathological disturbances of microcirculation in the brain.

Animals↗

PubMed2004

[Leukocyte adhesion to walls of the rat pial venules in normoxia and during brain ischemia].

With the help of contact optic system direct observations were carried out on leukocyte movements and on the acts of their adhesion to the inner surface of the walls of pial venules of the rats in normoxia and ischemia resulting from ligating two carotid arteries. After ligating the carotid artery and subsequent gradual development of ischemia, an abrupt increase in the number of the acts of adhesion to the walls of pial venules was shown to occur, the leukocytes adhere to each other inside the venules. A complete occlusion of venules and small veins results, which can be one of the reasons for the animal death in brain ischemia.

Animals↗

PubMed2003

[Organization and differential staining of chromosomes from the endomitotic nucleus of trophocytes Calliphora erythrocephala (Diptera: Calliphoridae)].

The structure of primary polytene chromosomes and general architecture of nurse cell nuclei was studied in Calliphora erythrocephala using various methods of differential chromosome banding(G-, R-, C-banding; Ag- and DAPI staining), chromospecific DNA probes and fluorescence in situ hybridization. This analysis revealed differential compaction of particular chromosome regions. The localization of material of polytene chromosome 6 is retained after its rearrangement and the formation of the internal reticular structure of the nucleus. Polytene chromosomes of ovarian nurse cells were shown to have blocks of dense compact material; some of them were more intensely stained by AgNO3. The dynamics of the nucleolus formation was traces at all stages of chromosome polytenization in the C. erythrocephala nurse cells.

Animals↗

PubMed2003

[Morphodynamic analysis of the role of leukocytes in the microcirculation disorder of the cerebral cortex].

The aim of this work was to establish the reasons for the disturbances of microcirculation (no reflow) during various kinds of oxygen starvation of the brain. Using contact optics and video-recording, direct observations were performed and leukocyte and erythrocyte displacement was monitored in the blood vessels of rat cerebral cortex in vivo in normoxia, during the development of various kinds of oxygen deficiency up to the terminal periods of life of an organism. In normoxia leukocytes were shown to decelerate erythrocyte movement in capillaries and to cause the irregularity of the capillary blood flow. Using the color videofilm recording it was shown that at deep stages of brain oxygen deficiency the disturbances of microcirculation up to its complete cessation were explained by the occlusion of venous microvessels as a result of massive adhesion of leukocytes to the inner surface of venules and the smallest veins. The co-adhesion of leukocytes was also found to take place. The latter leads to the formation of large leukocyte aggregates in venous vessels, results in "no reflow" effect. Leukocyte aggregates in veins block the venous outflow from the brain and may become the immediate cause of organism death as a result of disruption of circulation and oxygen deficiency.

Animals↗

PubMed2001

[Identification of L-forms of Mycobacterium tuberculosis complex by polymerase chain reaction (PCR)].

Polymerase chain reaction (PCR) was used to verify the tuberculous origin of L-forms isolated from clinical non-respiratory samples from patients with extrapulmonary tuberculosis. PCR was made by using cultured L-forms obtained from negative and positive cultures. PCR used a total of 60 cultured L-forms different in the morphology of colonies and the rate of growth. The total count of L-forms yielding positive amplification with M. tuberculosis complex-specific primers was 51 (85%). L-form passages were subjected to PCR analysis. A total of 14 third-generation L-forms were examined. They turned out to be positive. Thus, the fact that L-forms isolated from nonrespiratory clinical samples from patients with tuberculosis are most commonly L-forms of M. tuberculosis was genetically substantiated.

Bacteriological Techniques↗

PubMed2001

[Effect of calcium ion level in blood on physiological functions in rat subjected to immersion hypothermia].

I.v. administration of disodium salt of the ethylenediamine tetra-acetic acid to continuously immersed white rats intensified the rats' amplitude and rate of the respiration movement. I.v. administration of calcium chloride to the cooled rats diminished by 11.3% the respiration movement amplitude and by 20.7%--the muscles electrical activity. The findings confirm important role of the calcium ions in infringement of physiological functions under conditions of hypothermia.

Animals↗

PubMed2001

[Effect of Na2H2EDTA on the viability of rats' organism during hypothermia].

Effects of C-binding Na2H2EDTA (disodium salt of ethylene diamine tetraacetic acid) on the thermal control function of muscles and respiration in anesthetized rats of the Wistar strain cooled up to deep hypothermia were studied. Experiments were performed with the use of two cooling models, i.e. in water (10 +/- 0.2 degrees C) and air (-5 +/- 1 degrees C). Intravenous injection of 1 cm3 of the 0.6% Na2H2EDTA solution at 0.25 ml/min. was made first at the brain T = 24.0 +/- 0.4 degrees C and repeated at the brain T = 20.1 +/- 0.3 degrees C. Five to six minutes following injection the electrical myoactivity and respiration rate and amplitude grew up. The control experiments with injection of physiological solution were with null results. Injection of Na2H2EDTA reduced the thermal viability lower range as concluded from the drop of no-breathing temperature threshold and increase in tolerance period till respiration standstill by 10-15 min. It is supposed that physiological functions paralyzed by continuous cooling can be recovered by reducing active calcium in blood with intravenous Na2H2EDTA. This opens up brand new vistas for application of calcium-binding substances to assist overcooled organism.

Animals↗

PubMed1991