Estimation of Renal Clearance in Hypertensive Rats According to fMRI Data.

Renal clearance in Wistar rats with multifactorial cardiovasorenal model of arterial hypertension was assessed by fMRI using (EPI_Diffusion_map) protocol after injection of extracellular contrast agent gadolinium Gd-DTPA. Linear regression analysis was used to assess local concentrations of the contrast agent in the abdominal aorta, kidney compartments, pelvis, and bladder areas. Detection of marker clearance in order to verify the glomerular filtration rate was performed by the RPP (Rutland-Patlak plot) method. In 3 months after hypertension modeling, glomerular filtration rate decreased by 2 times in comparison with the control (31.2±0.44 and 62.3±1.31 µl/min/100 g, respectively; p<0.001). Our findings can indicate the formation of hypertensive nephroangiosclerosis in rats with experimental arterial hypertension. It was found that kidney damage in hypertensive rats is associated with hypofiltration.

Structural and Functional Changes of the Thoracic Aorta in Experimental Arterial Hypertension.

The functional characteristics of the thoracic aorta in Wistar rat with experimental arterial hypertension were studied using MRI. The intravital images of the aorta were obtained using a synchronizer of cardiac and respiratory cycles. The pulse-gradient Turbo-spin-echo sequence and the BODY CARDIAC movie 10 mode were used. The unfavorable factor of increased BP initiated structural and functional changes in the thoracic aorta. At the initial stages, they manifested by an increase of the lumen and a decrease in endothelium-dependent vasodilation. Progression of arterial hypertension (3-6 months) was associated with narrowing of the lumen of both ascending and descending parts of the aorta. Deformation of the aortic arch due to increased density of the vascular wall was observed by the sixth month of the development of arterial hypertension.

Magnetic Resonance Imaging of Rat Brain in Assessment of the Neuroprotective Properties of Histochrome in Experimental Arterial Hypertension.

The neuroprotective effects of the course therapy with Histochrome in Wistar rats with modeled arterial hypertension were studied by using magnetic resonance imaging (MRI) in diffusion-weighted mode. The behavioral status of the animals was assessed using the open-field test. MRI analysis revealed more pronounced increase in the signaling characteristics of the brain tissue in hypertensive rats in comparison with the control (intact) animals. It was caused by excessive accumulation of fluid in the intra- and extracellular spaces of the brain tissue, which is associated with hypervolemia induced by the multifactorial cardiovasorenal model of hypertension. After a course of Histochrome injections to hypertensive rats, the cerebral microcirculation disorders were leveled, while the behavioral status was characterized by shortened latency of the visit to the center of the open field by 20% and improvement of cognitive activity (by 1.6 times) and the exploratory component (by 30%).

Estimation of the Morphofunctional Status of the Brain in Hypertensive Wistar Rats Using Diffusion-Weighted MRI.

Morphofunctional changes of the brain tissues of Wistar rats were studied based on the development of a multifactor cardiovasorenal model of arterial hypertension using MRI. An increase of the signal on the diffusion brain maps was recorded in 3 months, which indicated fluid accumulation in the intra- and extracellular space of the brain tissue. The data characterize the development of the pathogenetic mechanism of the hypervolemic variant of experimental arterial hypertension. The development of endothelial dysfunction in the brain vessels was manifested by predominance of abnormal constrictor reactions. In 6 months after arterial hypertension simulation, structural changes in the brain developed, such as leukoareosis, cystic encephalomalacia with dilated cerebrospinal fluid spaces and limited blood supply to brain tissue in the basins of the large cerebral arteries.

Magnetic Resonance Imaging in Assessment of Cardiac Remodeling in Rats with Experimental Arterial Hypertension.

Magnetic resonance imaging was employed to examine the morphofunctional status of myocardium in Wistar rats with multifactor cardiovasorenal model of arterial hypertension. In 3 months after the onset of experiment, the rats demonstrated a pronounced hypertrophy in left ventricular myocardium mostly due to thickening of the posterior and lateral walls against the background of relatively stable thickness of ventricular septum. The left ventricular endsystolic volume markedly increased in parallel with moderate increase of the end-diastolic volume. The standard calculated indices were used for precise assessment of the type of remodeling of individual myocardial structures. The study showed that multifactor arterial hypertension model was characterized by domination of hypertrophic mode of the left ventricular remodeling, whereas the concentric variant was observed more rarely by 2.5 times. The greatest alterations were observed in the posterior and lateral walls of the left ventricle, which could result from the hemodynamic effects of hypervolemic arterial hypertension.

Assessment of Nephroprotective Potential of Histochrome during Induced Arterial Hypertension.

Magnetic resonance tomography was employed to verify endothelial dysfunction of renal arteries in Wistar and OXYS rats under conditions of induced arterial hypertension. Angiography revealed changes in the size and form of renal arteries of hypertensive animals. In hypertensive rats, histochrome exerted a benevolent therapeutic effect in renal arteries: it decreased BP, diminished thrombus formation in fi ne capillaries and arterioles, demonstrated the anticoagulant properties, partially improved endothelial dysfunction of small renal arteries, and up-regulated the glomerular filtration.

Vasomotor activity of the aorta during chronic smoking modeling.

We studied vasomotor responses of aortic endothelium in a rat model of chronic smoking. It was found that long-term exposure to tobacco smoke (inhalation) impaired vasomotor function of the aortic endothelium leading to insufficient vasodilator activity and enhanced vasoconstriction. After the cessation of inhalations, vasomotor disturbances were not only preserved, but also exacerbated because of increased pathological endothelium-independent vasoconstriction.

Evaluation of effects of histochrome and mexidol on structural and functional characteristics of the brain in senescence-accelerated OXYS rats by magnetic resonance imaging.

The effects of histochrome and mexidol on the morphology and function of the brain and behavior were studied in senescence-accelerated OXYS and Wistar rats. MRI showed that signs of neurodegenerative changes were present in OXYS rats at the age of 3 months and were pronounced at the age of 12 months. Histochrome (1 mg/kg, 5 days) more effectively than mexidol (4 mg/kg, 7 days) reduced anxiety and increased exploratory activity of 1-year-old OXYS rats. Both drugs improved the morphology and function of the brain. Their effects consisting in correction of diffuse changes in the white matter and reduction of edema were comparable; in addition, histochrome reduced the intensity of demyelinization processes.

Antitumor activity of the immunomodulatory lead Cumaside.

A new immunomodulatory lead Cumaside that is a complex of monosulfated triterpene glycosides from the sea cucumber Cucumaria japonica and cholesterol possesses significantly less cytotoxic activity against sea urchin embryos and Ehrlich carcinoma cells than the corresponding glycosides. Nevertheless Cumaside has an antitumor activity against different forms of experimental mouse Ehrlich carcinoma in vivo both independently and in combination with cytostatics. The highest effect occurs at a treatment once a day for 7 days before the tumor inoculation followed by Cumaside treatment once a day for 7 days. Prophylactic treatment with Cumaside and subsequent therapeutic application of 5-fluorouracil suppressed the tumor growth by 43%.

Immunomodulatory properties of frondoside A, a major triterpene glycoside from the North Atlantic commercially harvested sea cucumber Cucumaria frondosa.

Frondoside A, a major triterpene glycoside from North Atlantic commercially harvested sea cucumber Cucumaria frondosa, possesses strong immunomodulatory properties in subtoxic doses. Frondoside A stimulates lysosomal activity of mouse macrophages in vivo at a maximal effective stimulatory dose of 0.2 microg per mouse and is maintained over 10 days. This glycoside also shows a 30% stimulation of lysosomal activity in mouse macrophages in vitro at concentrations of 0.1-0.38 microg/mL. Frondoside A enhances macrophage phagocytosis of the bacterium Staphylococcus aureus in vitro at a maximal effective concentration of 0.001 microg/mL. Frondoside A stimulates reactive oxygen species formation in macrophages in vitro at a maximal effective concentration of 0.001 microg/mL. Frondoside A stimulates an increase in the number of antibody plaque-forming cells (normally B-cells in spleen) in vivo with a maximal stimulatory effect at a concentration of 0.2 microg per mouse (stimulatory index, 1.86). Frondoside A has a weak effect upon immunoglobulin (Ig) M production after immunization with sheep erythrocytes in mice. Frondoside A does not stimulate Ig production in mice and does not significantly enhance the ovalbumin-stimulated IgM and IgG antibody levels in ovalbumin-immunized mice. Hence frondoside A is an immunostimulant of cell-based immunity including phagocytosis without a significant effect on amplification of humoral immune activity or adjuvant properties. Therefore, frondoside A may provide curative and/or preventive treatment options against diseases wherein a depleted immune status contributes to the pathological processes.

[Characteristics of a vasomotor endothelial function of the major and cerebral arteries in bronchial asthma].

We investigated endothelium dependent and independent activity of major and cerebral arteries in mice with experimental bronchial asthma. Regional features of endothelium dependent reactions of arteries were established. It was found that the carotid artery has greater vasomotor activity than the medial cerebral artery. Development of experimental bronchial asthma is associated with sharp reduction of reserve ability for endothelium independent dilatation against intensification of endothelium dependent dilatation; enhancement of constrictor effects of vascular endothelium in major and attenuation in cerebral compartments.

[Interrelation of vasomotor effects in the endothelium of the cerebral and main arteries in obstructive pulmonary diseases].

We have investigated vasomotor activity of the trunk and cerebral arteries in mice with obstructive pulmonary diseases. It was established, that endothelial dysfunction depends on the form of pulmonary disease and has regional vascular features. It was determined, that the maximal disturbances are shown in mice with chronic obstructive pulmonary disease. It express as infringement of regional autonomy vasomotor effects and pathological paradoxical vasoconstriction of cerebral vessels. Bronchial asthma associates with the discordant answer of the brain and trunk arteries with the moderate adaptation of a regional homeostasis.

Peculiarities of vasomotor reaction of cerebral vessels in arterial hypertension.

We studied vasomotor activity of rat cerebral vessels. Peculiarities of endothelium-dependent reactions of cerebral arteries in induced arterial hypertension were revealed. Quantitative and qualitative relationships between the parameters of the vasomotor apparatus of cerebral arteries and parameters of circulatory homeostasis were determined.

Endothelial dysfunction of cerebral and major arteries during chronic obstructive disease.

Vasomotor activity of the major and cerebral arteries was studied in mice with chronic obstructive pulmonary disease. Regional differences were revealed in the endothelium-dependent response of arteries. The development of chronic obstructive pulmonary disease was associated with a paradoxical response of the dilatational component of vasoregulation against the background of increased constrictive influences of the vascular endothelium in the major and cerebral vessels.

[Pathophysiological mechanisms of hemorrhagic stroke and the ways of differential therapy].

The changes developing in the perifocal area of hematoma and perspectives of antioxidant and chelate therapy were studied on the model of experimental hemorrhagic stroke and in clinical conditions. Microcirculatory, ischemic and inflammation disturbances with a certain time sequence were found in the perifocal areas. These changes, along with hypostasis and oxidative stress, form the pathobiochemical cascade of changes in hemorrhagic stroke and are potential therapeutic targets. Administering of an antioxidant and chelate drug histochrome reduces the intensity of changes in the perifocal area in the experimental conditions. In clinical conditions, it accelerates the dynamics of brain and meningeal symptoms regression and improves the blood rheological properties.

Effect of histochrome on brain vessels and research and exploratory activity of senescence-accelerated OXYS rats.

Changes in the diameter of brain vessels and intensity of collateral blood flow typical of chronic ischemia were detected by magnetic resonance imaging in senescence-accelerated OXYS rats demonstrating reduced (compared to Wistar rats) research and exploratory activity. Histochrome (antioxidant drug) produced positive effects on cerebral vessels in OXYS rats by stimulating collateral blood flow and acting as a vasodilator agent. Analysis of correlations showed that these effects of histochrome were closely related to its capacity to activate research and exploratory activity and reduce anxiety of OXYS rats in the open field test.

Immunomodulatory properties of Cumaside.

The medical lead, so-called Cumaside, was created on the basis of triterpene oligoglycosides from the Far-Eastern edible sea cucumber (holothurian) Cucumaria japonica and its immunomodulatory properties were studied. The haemolytic activity of Cumaside was significantly reduced in comparison with original glycosides due to the glycoside-cholesterol complex formation. The influence of Cumaside on mouse macrophages in low doses was accompanied by more then two-fold stimulation of lysosomal activity. This preparation was found to increase significantly the animal resistance against bacterial infections elicited by various pathogens. It stimulated phagocytosis, ROS formation, IL6 and TNF-alpha production in lymphocytes, increased the number of antibody producing cells and amplified the expression of several cell surface molecules (CD3, CD4, CD8) preliminary cultured with hydrocortisone. At the same time the preparation did not affect the delayed-type hypersensitivity, proliferative activity of lymphocytes, cytotoxic activity of NK-cells and cytokine IFNgamma and IL12p70 release. The mechanism of Cumaside action is discussed.

Noninvasive study of vasodilatory activity of albino rat cerebral arteries.

Vasodilating activity of rat cerebral vessels was studied. Methodological peculiarities and chronotropic limits of vasomotor testing were determined. Qualitative and quantitative parameters of dilatation of vessels were determined and similarity of rat dilatation responses and human vasodilatory activity was described.