Disorders in the Morphology and Nanostructure of Erythrocyte Membranes after Long-term Storage of Erythrocyte Suspension: Atomic Force Microscopy Study.

Disorders in the erythrocyte morphology and structure of their membranes during long-term storage of erythrocyte suspension (30 days at 4°C) were studied by atomic force microscopy. The morphology and nanostructure of erythrocyte membranes, biochemical parameters, ion exchange parameters, and hemoglobin spectra were recorded. The transformation of erythrocyte morphology and destruction of their membranes were observed throughout the storage period. Irreversible forms of spheroechinocytes and their fragments formed by the end of storage. The concentrations of potassium ions and lactate in solution of the blood preservatiive increased, while pH value decreased. Hemolysis detected by the erythrocyte "leakage" effect was observed starting from days 16-23 of storage.

Reversible zinc-induced injuries to erythrocyte membrane nanostructure.

Zinc-induced injuries to red blood cell membrane nanostructures at different zinc concentrations were studied by atomic force microscopy. In order to distinguish the intrinsic characteristics of membrane nanostructures, the membrane surfaces were represented by three orders using 3D Fourier transform. Increasing the concentrations of zinc ions modified the pattern of induced injuries: their depths and diameters and their number on the membrane surface test area increased. The injuries and their distribution for each order of membrane surface were analyzed. Albumin restored membrane nanosurface.

Macro- and microstructure of erythrocyte membranes under acute massive hemorrhage and subsequent blood reinfusion.

The authors studied changes in erythrocyte membrane nanostructure using a rodent model of hemorrhagic hypotension and resuscitation. Both macro- and microstructural elements were examined using atomic force microscopy. Membrane "roughness" was characterized using spatial Fourier transformation and was stratified according to the periodicity of the membrane. Acute hemorrhage resulted in an increase in the diameter and height of erythrocytes, which returned to baseline levels by the end of the hemorrhagic hypotensive period. The effect of hypotension on the erythrocyte surface was nonuniform. In those regions where damage was considerable, the rate of restoration of the membrane microstructure to baseline levels was prolonged. The less damaged surfaces were restored more rapidly to control values after reperfusion. More detailed use of atomic force microscopy in the definition of the erythrocyte membrane microstructure may further define the mechanisms of cellular functional restoration after hemorrhage.

Erythrocyte membrane surface after calibrated electroporation: visualization by atomic force microscopy.

Atomic force microscopy was used for examination of the surface of human erythrocyte membrane after calibrated electroporation and application of pharmacological agents. Three-order surface inhomogeneities were revealed with various spectral windows of Fourier transform to elaborate the quantitative criteria to assess the state of membrane surface. The size of structural alterations induced in the membranes by electroporation was 100-300 nm, which is comparable to the size of membrane matrix.

[The diagnostic of membranes' state after exposure of gamma-radiation of small doses].

There are the results of experimental research of the change of membranes' conditions under the action of gamma-radiation using the method of following membranes' electroporation of the accurate impulse of the electrical field for the analysis of defects after the action of gamma-radiation. As of the research material the suspension of erythrocytes was used. It was shown that the velocity of decreasing of the erythrocytes in the case of combined action of gamma-radiation and the impulse of the electrical field is more than the sum of such velocities in the case of the action of the factors separately. The method of the electroporation of the accurate impulse of the electircal field is obvious for the practicaland the analytical research of membranes' defects.

Effect of defibrillation pulses of different shapes on biomembranes: experimental study.

We studied the effects of high-voltage single, double unipolar, and double bipolar electric pulses of exponential or sine shape on erythrocyte membranes. Either single or double (mono- or bipolar) pulses were used. All pulses electroporated the membranes, and the electroporation threshold did not depend on the pulse shape. Two successive pulses decreased erythrocyte number in a nonadditive way. Similar to defibrillation of the whole heart, the effect of two bipolar pulses on erythrocytes was more pronounced than the effect of two unipolar pulses.

[Spatio-temporal changes in the metabolic processes in the blood-tissue system in the terminal states of the organism]. / Prostranstvenno-vremennye narusheniia protsessov obmena v sisteme krov'-tkan' pri terminal'nykh sostoianiiakh organizma.

The role of synergism in diffusion of oxygen from erythrocyte into interstitial liquid and water filtration through the capillary wall was studied on the model using the following parameters: hydrostatic pressure on arterial and venous ends of the capillary (Pa and Pb), oncotic blood and tissue pressure (Pob and Pot), pore radius in the capillary (r), the number of pores in the capillary (n) per m2, amount of the liquid released from the capillary (q(x)), gas diffusion coefficient (D), time of erythrocyte movement in the capillary (T), speed of oxygen consumption (V), maximal distance with adequate V (Xmax), characteristic time of diffusion (Topt). It is shown that diffuse and convective components of the metabolic process have their own contribution and in changed conditions they redistribute. In increased number and diameter of hydravlic pores the greatest role in tissue saturation with oxygen belongs to convective metabolism, but in this situation tissues contain areas lacking oxygen.

[The shape of high-voltage impulse and the effect of defibrillation]. / Vliianie formy vysokovol'tnogo impul'sa na éffekt defibriliatsii.

The paper discusses how to choose the optimum shape of a pulse for electric defibrillation of the heart. The authors' data are given on the values of an induced field in the contracting myocardial structure when a defibrillator evokes pulses. Mono- and bipolar pulse-induced changes of the transmembranous potential on the hyper- and depolarized sides of a cell are calculated. Mechanisms of defibrillation in the use of pulses of different shapes are considered.

Modeling of blood flow as the result of filtration-reabsorption processes in capillaries.

In our previous article (Am J Physiol Adv Physiol Educ 272: S26-S30, 1997) we proposed a model that permits analysis for the change of hemodynamics in vessels with local stenosis. This problem is connected with the blood-tissue metabolism. This article continues the classroom research on concepts related to blood flow physiology. We take into consideration the problem of the blood-tissue fluid exchange. A model based on basic principles of hydrodynamics and mathematics is proposed for analysis of "filtration-reabsorption equilibrium" and its disturbances under different external influences. It permits medical students to develop a scientific analytic approach to the solution of physiological and pathophysiological hemodynamics problems.

[A model of blood flow distribution during filtration-reabsorption processes in capillaries]. / Modelirovanie raspredelenie krovotoka pri fil'tratsionno-reabsorb tsionnykh protsessakh v kapilliarakh.

A model of blood flow in a capillary was constructed, which takes into account the movement of plasma through its porous wall. The functions of changes in pressure and the rate of blood flow along the capillary were calculated. It was shown that, in the general case, the distribution of hemodynamic parameters as a result of filtration-reabsorption processes is nonlinear. Possible mechanism of tissue edema resulting from the disturbance of the filtration-reabsorption equilibrium were analyzed.

[Segmental contractile activity of the left ventricle in life threatening arrhythmia]. / Segmentarnaia sokratitel'naia aktivnost' levogo zheludochka pri zhizneopasnykh aritmiiakh.

Intramural pressure (IMP) in the middle segment of the left ventricle and in the apex under ventricular extrasystoles was measured in experiments on the hearts of narcotized dogs. Early extrasystoles caused greater lowering of IMP and blood ejection. Bigeminia was associated with segmental and transmural nonuniformities of IMP which may be due to additional dragging effects in the myocardium. Magnitude of cardiac ejection under extrasystoles depends on nonuniform contractions of the segments of the left ventricle.

Modeling blood flow in vessels with changeable caliber for physiology and biophysics courses.

A model based on elementary principles of hydrodynamics and mathematics is proposed for classroom research on concepts related to blood flow physiology. This is an analog model of the vascular system in which blood flow is represented by electrical current flowing in a resistance circuit. The model permits analysis of the change in hemodynamics with local stenosis of both large and peripheral vessels.