Hybrid nonlinear resonance in Hamiltonian systems.

An electronic system in an atom can be considered Hamiltonian only at times shorter than the spontaneous relaxation time. However, this time is sufficient for resonant action on the electronic system and for the implementation of the resonance inherent in Hamiltonian systems. In practice, there may be a case when it is expedient to use a hybrid approach to study nonlinear resonance, in which the classical theory can be used to calculate the action-dependent nonlinear resonance frequency, and the quantum theory can be used to calculate its correction.

Quantum corrections to the classical model of the atom-field system.

The nonlinear-oscillating system in action-angle variables is characterized by the dependence of frequency of oscillation ω(I) on action I. Periodic perturbation is capable of realizing in the system a stable nonlinear resonance at which the action I adapts to the resonance condition ω(I(0))≃ω, that is, "sticking" in the resonance frequency. For a particular physical problem there may be a case when I≫ℏ is the classical quantity, whereas its correction ΔI≃ℏ is the quantum quantity.

Hemorheological changes in microcirculation: their mechanism and measurement technique.

Blood fluidity in the capillaries is affected significantly in diseases such as cardiac and brain infarcts, diabetic gangrene and many others. In view of the importance of physiology and pathology of capillary circulation, the hemorheological characteristics of the capillary blood flow are discussed in this article. Also, a new diagnosing technique for blood fluidity disorders is proposed.

Hemorheological, microvascular and hemodynamic disorders during coronary heart disease.

Significance of the hemorheological disorders in development of acute vascular syndromes is presently well known, but their role in pathogenesis of chronic coronary heart disease has not been yet sufficiently analyzed. Aim of the present study was the investigation of the relationship between the hemorheological, vascular and hemo-dynamic factors responsible for development of the coronary heart disease. We investigated 64 patients with coronary heart disease of the functional classes I-IV with and without the heart failure.

Hemorheological disorders in patients with type 1 or 2 diabetes mellitus and foot gangrene.

The aim of the present study was to evaluate blood rheological disorders, in particular RBC enhanced aggregation, and compare changes in these parameters in patients with type 1 and 2 diabetes mellitus. For evaluation of RBC aggregability in the present study we applied the "Georgian technique", which was developed and applied for several years in our laboratory. Its advantage is that it is a direct and quantitative method.

Comparison of erythrocyte aggregability changes during ischemic and hemorrhagic stroke.

The aim of this work was to perform a comparative investigation of erythrocyte aggregability changes in the peripheral and cerebral circulation during ischemic and hemorrhagic stroke. Subjects of the present study were patients with ischemic brain infarcts (14 patients) and with hemorrhagic stroke (21 patients) from the Intensive Care Unit of the Institute of Neurology and Neurosurgery. The blood samples were obtained from the following blood vessels: the common carotid artery carrying blood to the primarily damaged brain hemisphere, both jugular veins carrying blood from the primarily damaged and the contralateral hemispheres, as well as from the cubital vein to obtain specimens of the systemically circulating blood.

Hemorheological disorders during ischemic brain infarcts in patients with and without diabetes mellitus.

The aim of the present study was the comparative analysis of the role of specific hemorheological derangements in the pathogenesis of ischemic brain infarcts with and without diabetes mellitus. Blood plasma viscosity, as well as red blood cells (RBC) aggregability were quantitatively investigated in all patients during the study. Both of the above mentioned indices of hemorheological disorders were significantly higher in the patients with brain infarcts and diabetes mellitus as compared to the control and the group of ischemic brain infarcts without diabetes.

Hemorheological disorders in the microcirculation during septic shock in rats.

Objectives: The aim of the present study was the experimental analysis of blood rheological disorders in the microcirculation during endotoxic shock.

Methods: Experiments were carried out on 30 white laboratory rats of both sexes weighing about 200 g. The experimental animals were divided in two groups: the control group and the group undergoing experimental endotoxic shock.

Comparison of blood rheological changes in the microcirculation during experimental hemorrhagic and traumatic shock.

Objective: The aim of the present study was the analysis of the specific hemorheological disorders during the middle stages of experimental traumatic and hemorrhagic shock.

Methods: The following hemorheological properties were investigated: Red Blood Cell (RBC) aggregability, their deformability, and systemic hematocrit. The RBC aggregability was assessed by using the "Georgian technique".

About spread of local cerebral hemorheological disorders to whole body in critical care patients.

Purpose: The aim of the present pathophysiological studies was elucidation of the feasible mechanism of spread of the blood rheological disorders from the cerebral to systemic circulation, and vice versa.

Methods: The investigation was carried out in the critical care patients with the brain tissue damage related to stroke (cerebral ischemic infarcts as well as parenchymatous and subarachnoid hemorrhages). The applied diagnostic techniques provided us with valid and quantitative data revealing the degree of the red blood cell aggregability, the value of local hematocrit, and the blood plasma viscosity in the cerebral and systemic circulation.

Hemorheological disorders in the microcirculation following hemorrhage.

We analysed hemorheological disorders in the microcirculation of intestinal mesenterium of adult laboratory rats following massive exsanguinations when the mean arterial pressure dropped and then the hemorrhagic shock developed in the animals. The mesenteric microcirculation was analysed by the Texture Analysis System (Leitz, Wetzlar): (a) diameters of the afferent arterioles, capillaries, and efferent venules; (b) the blood flow velocity; (c) microvascular blood flow changes (during the RBC aggregation); (d) local microvascular hematocrit; and (e) the transformation of capillaries into plasmatic microvessels. During development of the hemorrhagic shock we found that the blood flow velocity decreased in all microvessels, there was an increased RBC aggregation which gradually enhanced in the mesenteric microvessels' lumen causing blood flow slowing down till appearance of stases.

Regional and systemic hemorheological disorders during feet diabetic gangrene.

We investigated the RBC aggregability in the patients with the foot diabetic gangrenes: in the venous blood samples taken from the damaged foot before its amputation, as well as from the cubital vein (the systemic circulation). The RBC aggregability was investigated with the "Georgian technique" that is sensitive and provided us with direct and quantitative data. We found that the RBC aggregability was higher by about 20%, in the blood flowing from the gangrenous tissue than in the systemic circulation.

Lipid peroxidation in the erythrocytes under condition of their increased aggregation.

The aim of the present study was investigation of the lipid peroxidation changes within the erythrocytes under conditions of increased RBC aggregation. This latter was produced both in the in vitro and in vivo conditions by the addition of Dextran T-500. For the in vitro studies blood samples were taken from the cubital veins of 15 healthy subjects.

Direct beneficial effect of insulin on blood rheological disorders in the microcirculation.

Under both the in vivo and in vitro conditions we investigated the insulin effect on the most significant factor disturbing the blood rheological disorders in the microcirculation, the red blood cell aggregability. The in vivo studies we carried out in the 42 insulin treated diabetic patients (diabetes mellitus type II), as well as conducted the in vitro investigations of the blood both of the diabetic patients (24) and of the healthy people (20) where the insulin was added to the blood ex vivo. The RBC aggregability in blood investigated with the "Georgian technique" was found significantly enhanced, by about 100 per cents in the diabetic patients.

Local hemorheological disorders during chronic inflammation.

Hemorheological parameters were investigated before, during, and after the standard burn of the distal part of the rabbits' ear shell (54 degrees C for 3 minutes). The erythrocyte aggregation was investigated with the "Georgian technique" and the local hematocrit was determined by centrifugation of blood samples from the inflammatory focus. In addition, we determined the size of the inflammatory edema in the ear shell.

Blood rheological abnormalities in the microcirculation during experimental traumatic shock.

Objective: To find whether the principal indices of blood rheological disorders related to the microcirculation undergo drastic changes during the traumatic shock.

Methods: RBC aggregability and deformability, as well as the systemic hematocrit, were assessed in white laboratory rats with the techniques that provided us with direct and quantitative data.

Results: We found that in the experimental animals the RBC aggregability was sharply increased, the RBC deformability significantly decreased, while the systemic hematocrit underwent considerable lowering during the traumatic shock.

Effect of nitric oxide initial blood levels on erythrocyte aggregability during 12 hours from ischemic stroke onset.

The aim of study was the investigation of blood nitric oxide (NO) and nitrates (NO2) levels in 12 hours of ischemic stroke onset and establishment of correlation of these data with erythrocyte aggregability and initial ischemic lesion size. 48 patients, aged 45 to 70 years, 26 female, 22 male were investigated. Glasgow Coma Scale (GCS) and National Institute Health Stroke Scale (NIHSS) assessed initial neurological impairment.

Hemorheological disorders and arteriolar resistance during ischemic heart disease.

It could be conjectured that the hemorheological disorders are involved in development of the ischemic heart disease. But this fact was so far insufficiently cleared up. The present studies were carried out in patients with various forms of chronic ischemic heart disease.

Basic factors determining the hemorheological disorders in the microcirculation.

Hemorheological properties and disorders are very specific in the microcirculation since blood is actually not a fluid in the capillaries and in the adjacent arterioles and venules. This is because almost half of the blood volume constitutes the red and white blood cells whose size is commensurable with the microvessels lumen. Based on perennial investigations we concluded that the advancement of blood in capillaries is primarily dependent on the "structure" of the flowing blood that determines the resistance to blood advancement in the microvessels rather than on the well-known hydrodynamic relationships characteristic for the larger blood vessels.

Blood rheological properties and lipid peroxidation in cerebral and systemic circulation of neurocritical patients.

The present study was aimed at investigating the red blood cell (RBC) aggregation and the parameters of lipid peroxidation - malondialdehyde (MDA) and MDA + 4-hydroxyalkenals (HAE) - in the blood of critically deteriorated stroke patients (brain infarcts, parenchymatous and subarachnoid hemorrhages) and in the control group. Measurements were made in blood samples from the common carotid artery, the both internal jugular and cubital veins. The RBC aggregation index was found to increase by about 80 per cent in both the cerebral and systemic circulation as compared to the control blood samples.

Regional hematocrit changes related to blood flow conditions in the arterial bed.

Present study was aimed at specifying both the anatomical and physiological factors determining the regional hematocrit alterations. These latter were investigated in blood samples from specific vascular branches of rabbits, as well as from the skin and the jugular veins (reflecting the cerebral microcirculation) of humans. Principal findings were as follows: (1) Blood in the heart left ventricle has a higher hematocrit than blood flowing in the hind legs.

Local RBC aggregation disturbing blood fluidity and causing stasis in microvessels.

Experiments in rat mesenterium were carried out under conditions when both pressure gradient in the chosen microvessels and their diameters were preserved constant. All details of the hemorheological events were directly visualized and documented by usage of appropriate microscopic video techniques. Intensified RBC aggregation locally produced in individual capillaries, immediately disturbs the normal blood flow structure inside their lumina and deranges the rheological properties of blood flow in the microvessels, which slows down till a full stop.

Arteriolar resistance and hemorheological disorders related to Raynaud's phenomenon.

The functional condition of resistance arteries in human hands was monitored with a noninvasive test. Blood flow velocity changes (Doppler flow meter) were monitored in the radial artery before and after a 1-min stop flow in the hand under conditions of stable systemic arterial pressure. In addition, the most significant parameter of hemorheological disorders in microcirculation, RBC aggregability, was investigated in the same patients' blood samples.

Blood flow structure related to red cell flow: determinant of blood fluidity in narrow microvessels.

The review article deals with phenomena of the blood flow structure (structuring) in narrow microvessels-capillaries and the adjacent arterioles and venules. It is particularly focused on the flow behavior of red blood cells (RBCs), namely, on their specific arrangements of mutual interaction while forming definite patterns of self-organized microvascular flow. The principal features of the blood flow structure in microvessels, including capillaries, include axial RBC flow and parietal plasma layer, velocity profile in larger microvessels, plug (or bolus) flow in narrow capillaries, and deformation and specific behavior of the RBCs in the flow.