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. The use of such a hybrid approach becomes necessary when the resonant value of the action does not exceed Planck's constant many times. It is shown in the work that if the external electromagnetic field has the form of a periodic series of light pulses with a high duty cycle, then the phenomenon of nonlinear hybrid resonance leads to the appearance of a line in the low-frequency region of the electronic spectrum. The broadening of this line is determined using the rms quantum fluctuations.

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. Naturally, dynamics of ΔI is described by the quantum equation of motion. In particular, in the moderate nonlinearity approximation ɛ≪(dω/dI)(I/ω)≪1/ɛ, where ɛ is the small parameter, the description of quantum state is reduced to the solution of the Mathieu-Schrödinger equation. The state formed as a result of sticking in resonance is an eigenstate of the operator ΔI that does not commute with the Hamiltonian H. Expanding the eigenstate wave functions in Hamiltonian eigenfunctions, one can obtain a probability distribution of energy level population. Thus, an inverse level population for times lower than the relaxation time can be obtained.

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. For evaluation of the hemorheological disorders we investigated its most significant symptom, the erythrocyte aggregability, with the "Georgian technique" that provided us with direct and quantitative data. We investigated also the tone of the hand's resistance arteries with an original non-invasive technique based on measurement of the flow velocity changes in the patients and in the healthy controls radial arteries by using the Doppler technique during standardized postischemic hyperemia. Echocardiographically we studied the standard characteristics of left ventricular function (systolic and diastolic volume, its mass and ejection fraction). ECG by standard leads and the blood pressure were investigated in all patients. We found that the rheological disorders are manifested in the early stages of the disease before its functional manifestation. The most pronounced hemorheological disorders were in evidence in the patients with unstable angina and heart failure. As to the arteriolar resistance index, it was increased only in 45 per cent of all the investigated patients and no significant difference between the patients with the heart failure and without it was found. There was a negative relationship between erythrocyte aggregability and the ejection fraction of the left ventricle and the positive correlation between erythrocyte aggregability and left ventricle hypertrophy (p<0.01). We concluded that the blood rheological disorders represent themselves a factor that plays a significant role in pathogenesis of the coronary heart disease. They are predictors of the disease and not only risk factors as it is generally believed. Measurement and correction of these disturbances in its early stages have a high clinical significance.

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". The RBC deformability was determined with the nuclepore membrane filter method of Reid. The hematocrit was measured by blood centrifugation. The results obtained were treated statistically by using the "Two sample T-test". RESULTS: We found that in the animals with traumatic shock the erythrocyte aggregability index increased by mean 181%, while in the hemorrhagic group this index on contrary decreased by mean 68% as compared to control group; The RBC deformability underwent a significant decrease during both traumatic and hemorrhagic shock: by a mean of 52% during the first and 62% during the second one. The systemic hematocrit decreased by a mean of 45% during the traumatic shock and by a mean of 50% during the hemorrhagic shock. CONCLUSION: The data obtained provide evidence that the hemorheological disorders are among the most significant microcirculatory disturbances in the pathogenesis of both the traumatic and the hemorrhagic shock.

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. Erythrocyte aggregation was evaluated by using the "Georgian technique". We found that the RBC aggregation indices increased in both the regional as well as the systemic circulation of the hemorrhagic stroke patients as compared to ischemic stroke patients. The results of the present study demonstrate different changes of erythrocyte aggregation in ischemic and hemorrhagic stroke patients. Therefore, the role of blood rheological properties in their pathogenesis seems also to be different.

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. In addition, rabbits experiments were carried out for analysis of the hemorheological disorders associated with the brain damage. RESULTS: Despite the local character of the patients primary brain damage, the hemorheological disorders were found regularly spread not only over the cerebral hemispheres, but even also the systemic circulation. Under such conditions they might cause the generalized brain tissue damage and play significant role in the subsequent damage-cascade of the whole brain. In addition, the rabbits experiments demonstrated pronounced hemorheological disorders in the cerebral cortex capillaries: increase of their numbers with RBC enhanced aggregation and blood stasis, as well as with lowering of the RBC deformability in the narrow capillary lumina. These changes befell simultaneously with increase of water contents in the cerebral tissue evidencing for edema development in the brain. CONCLUSION: Local cerebral hemorheological disorders might spread over the whole brain via the systemic circulation, thus promoting a generalized brain damage and being responsible for the critical state of the patients.

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. We investigated the most significant factor of rheological disorders in the microcirculation, the erythrocyte aggregability, with a technique that provided us with the direct and quantitative data. Simultaneously we investigated in the same patients the tone of the resistance arteries of the hand with an original non-invasive technique. We found that the erythrocyte aggregability increased almost twice in the blood of investigated patients as compared to the healthy control group. The aggregability was positively correlated with severity of the disease. The most pronounced hemorheological disorders were found in the patients with the heart failure. As to the arteriolar resistance index, it was increased only in 45 percent of all the investigated patients and no significant difference between the patients with the heart failure and without it was found available. We concluded that the blood rheological disorders represent themselves a factor that plays a significant role in pathogenesis of development of the heart disease.

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. CONCLUSION: The blood rheological properties are significantly disordered during development of 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. Patients were divided in mild and severe stroke groups. Control comprised 20 healthy individuals. Ischemic lesions were evaluated on conventional MRI scans. NO levels were measured by electron paramagnet resonance (EPR) method. NO2 levels were defined by spectrophotometer method. Erythrocyte aggregability index (EAI) was measured by sound method [Biorheology 30(2) (1993), 153-161]. Pearson correlation and multivariate model of logistic regression was applied. Significant negative correlation was established between NO initial blood levels and the EAI (r=-0.75; p<0.001), as well as between blood NO2 and NO initial levels and ischemic lesion size (r=-0.79, p<0.01; r=-0.61, p<0.02, respectively). Endothelialy derived NO correlates with erythrocyte aggregability and probably has a positive impact on restoration of cerebral blood flow in the initial stage of acute brain ischemia.

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. We found that the erythrocyte aggregability rised by 3.7 times in the venous blood flowing out from the inflammation focus while the hematocrit increased 1.6 times as compared to the microcirculation in the contralateral (control) ear shall. The thickness of this latter related to edema development increased three times. All the mentioned changes disappeared within five days after start of the experiments. We concluded that in the aseptic inflammatory foci the erythrocyte aggregability increases considerably in the microcirculation producing capillary stases and enhancing the local hematocrit. The hemorheological disorders were not spread to other parts of the circulatory bed.

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. During the in vivo studies 10 ml of the 10 percent Dextran T-500 solution was administered intravenously in six chinchilla rabbits. Another six animals were treated with rheopolyglucyne. The RBC aggregation in blood was investigated with the "Georgian technique". The malondialdehyde (the end product of lipid peroxidation) was determined in all cases by its reaction with thiobarbituric acid. We found that in the in vitro conditions, as well as in the in vivo studies, the lipid peroxidation was significantly increased in the erythrocytes during the enhanced RBC aggregation induced by addition of Dextran T-500. Therefore we suppose that the elevated RBC aggregation cause an increase of cell's lipid peroxidation and it is possible to think that appropriate prooxidant: antioxidant balance is shifted toward the pro-oxidants in the erythrocytes.

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. A part of the capillaries transformed into plasmatic vessels. Therefore the microcirculation demonstrated a significant decrease, this being related both to the lowered pressure gradient and to specific hemorheological disorders in the capillary networks.

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. MDA content appeared also significantly higher in the blood flowing out of the damaged hemisphere of the neurocritical patients as compared to the control group. In the blood flowing out of the damaged hemisphere of the neurocritical patients MDA as well as MDA + HAE content significantly exceeded the values found in blood samples of the jugular vein of the contralateral hemisphere, carotid artery and the cubital vein. The results of this study suggest a certain interdependence between the blood plasma lipid peroxidation and the RBC aggregation in the brain vessels following its damage.

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. The muscular tone of the resistance arteries was found to be a mean of 35% higher during Raynaud's phenomenon than in the healthy controls tested. The raised vascular tone was not related to the patients' age and had a pronounced tendency to rise with disease duration. RBC aggregability was a mean of 4% higher in the patients than in the healthy controls, and the difference was not reliable. We concluded that, among principal pathogenic factors which might cause deficiency of the blood supply to fingers, it is the enhanced tone of resistance arteries that is primarily responsible for the development of Raynaud's phenomenon, while hemorheological disorders are not, or are considerably less, involved in the development of the principal symptom of the disease, deficient blood supply to the fingers.

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. The actual blood flow structuring in microvessels seems to be a most significant factor in the development of pathological conditions, including arterial hypertension, brain and cardiac infarctions, inflammation, and many others. The blood flow structuring might become a basic concept in determining the blood rheological properties and disorders in the narrow microvessels. No solid theoretical (biorheological) basis of the blood flow structuring in microvessel has been found, but in the future it might become a foundation for a better understanding of the mechanisms of these properties under normal and pathological conditions in the narrowest microvessels 5 to 25 microm large. It is also a topic for further biorheological research directed to find the background of actual physiopathological phenomena in the microcirculation.

Comparative values of erythrocyte aggregability versus other indices of hemorheological disorders in patients with ischemic brain infarcts.

The aim of the present study is comparison of changes of principal hemorheological factors responsible for blood flow disorders in the microcirculation in patients with ischemic brain infarcts. It was found that in venous blood samples the erythrocyte aggregability (examined with a direct, highly sensitive, quantitative technique) was considerably more increased (by mean of 120%) than the blood plasma fibrinogen contents, blood plasma viscosity, and hematocrit which increased only by 23.7%, 7.4% and 3.6%, respectively, as compared to the same hemorheological factors in the healthy controls. These results led us to the following conclusion: among the other tests the enhanced erythrocyte aggregability, when measured with an appropriate technique, is the best diagnostic indicator of hemorheological derangements during development of the ischemic brain infarct.