[Electrical impedance tomography in pulmonology]. / Elektroimpedansnaia tomografiia v pul'monologii.

Application of a modern method of introscopy--electroimpedance tomography (EIT) for diagnosis of different types of lung diseases is described. The EIT system including measurement and collecting data devices, 16-electrodes array and IBM PC 486 computer was used. The results of analysis of electrotomograms have demonstrated that the EIT-system can be introduced for detecting abnormal lung fluid levels, pulmonary edema, diagnosis of lung cancer, emphysema, pleuritis, hydrothorax, sarcoidosis. The method provides high sensitivity to the changes in the body physiological state. Other advantages are: safety, fast measurements, ease of equipment transportation and maintenance, low cost.

[Use of electrical impedance tomography in detection of latent diseases during mass screening]. / Primenenie élektroimpedansnoi tomografii dlia vyiavleniia skrytykh form patologii pri massovykh obsledovaniiakh naseleniia.

The paper deals with the use of the present-day highly effective method of introscopy electric impedance tomography (EIT) for diagnosis latent abnormalities during mass screening. EIT images viscera and tissues on the basis of their electric conductivity differences. Reconstruction of the images reflecting the distribution of electric conductivity values in the body is made from the recording potentials onto the body's surface while passing currents through the electrodes located along the circumference of the body's part under study. The 16-electrode EIT system developed by Dipol (Moscow) was used to examine the distribution of electric conductivity values in the extremities and chest organs in healthy volunteers of both sexes and in patients with various pulmonary diseases.

Tone, autoregulatory properties, and wall thickness-to-radius ratio in skeletal muscle arterioles.

Internal diameter, wall thickness, wall thickness-to-radius ratio (W/r), and blood flow velocity in arterioles of different branching orders were measured in the rat cremaster muscle. The heterogeneity of W/r increased in more distal orders. During papaverine treatment, there was a direct correlation between vasodilation and W/r. When pressure was decreased by 20%, 42% of arterioles showed autoregulation; the remaining arterioles constricted in proportion to initial W/r. Similarly, the dilatation of arterioles with autoregulatory properties increased with initial W/r. It is concluded that W/r is an important parameter quantitatively related to tone, mechanical characteristics, and autoregulatory properties of arterioles.

[The tonus and relative thickness of the wall of skeletal muscle arterioles]. / Tonus i otnositel'naia tolshchina stenki arteriol skeletnoi myshtsy.

Inner diameter, absolute and relative wall thickness, and blood flow velocity in arterioles of different branching orders were measured in the rat skeletal (cremaster) muscle. It was found that as the branching order increased the heterogeneity of arterioles with respect to their relative wall thickness also grew. In response to papaverine-induced relaxation of the smooth muscle, there was a direct correlation between vasodilatation and the relative wall thickness. It was shown that a degree of smooth muscle shortening in different arterioles varied widely, the relative wall thickness being a measure (characteristic) of this shortening.

[Effects of thermal factors on the state of microcirculation of the small intestine in acute ischemia]. / Vliianie temperaturnykh vozdeistvii na sostoianie mikrotsirkuliatsii tonkoi kishki pri ostroi ishemii.

The influence of normo- (38 degrees C), hyper- (42 degrees C) and hypothermia (20 degrees C) on microcirculatory disturbances caused by acute local ischemia of the small intestine was investigated with the help of biomicroscopy as well as morphological methods. Ischemia was modeled by ligation of the intestine look eventrated through the abdominal wall incision of a rat onto the microscope stage for 1 h. It was shown that hyperthermia intensified microcirculatory disorders and stimulated destructive processes in tissues and hypothermia promoting microcirculation and decreasing metabolism and restrained the development of these processes. Important peculiarity of the microvascular response to ischemia, hyper- and hypothermia was revealed: heterogeneity of the reaction of different parts of microvascular bed. Appropriate evaluation of the microcirculation state in such conditions can be obtained taking into account not only the qualitative character of microvascular reaction but also an extent of this reaction manifestation in different parts of microvascular bed.

[Study of the trajectory of erythrocyte movement in microvessels using a method of automatic image analysis]. / Izuchenie traektorii dvizheniia éritrotsitov v mikrososudakh s pomoshch'iu metoda avtomaticheskogo analiza izobrazhenii.

Many physiological and pathological processes in the circulation are related to changes of blood rheological properties. Since blood represents a specific suspension of cells in plasma the mentioned changes are to a great degree dependent on behavior and interaction of red blood cells (RBC). For investigation of blood flow structure in microvessels we developed an algorithm and worked out a program for automatic treatment of RBC movement on the basis of automatic image analysis system "Leitz-TAS" (Ernst Leitz, FRG). The program was based on computation of coordinates of blood cell centers. Further we calculated the following values: the vector of displacements (S), its projection on both axes (dx, dy), their relationship (dy/dx), the relationship of RBC radial coordinate to vessel radius (y/R), and the velocity of RBC movements (V). Proceeding from these data we obtained such parameters, as e.g., the velocity profile, the radial displacements of red cells, etc. by which we could judge on the blood flow regime, the flow structure and changes of blood rheological properties.

[Effects of substance P and its fragments on microhemodynamics in animal experiments]. / Vliianie substantsii P i ee fragmentov na mikrogemodinamiku v éksperimente.

Action of the synthetic substance P (SP1-11) and its modified fragment (MSP1-4) on microhemodynamics was investigated in experiments. Significant hypotensive effect and reduction of blood flow velocity in rat mesenteric microvessels were produced by both substances, no changes of microvessels diameter were observed. Effective concentrations of the SP1-11 and MSP1-4 were revealed, being 10(-6) M and 10(-4) M, respectively. Organ specificity of substance P vascular effects is suggested.

[Limitation of ischemic necrosis by the use of antioxidant ionol]. / Ogranichenie ishemicheskogo nekroza s pomoshch'iu antioksidanta ionola.

Inhibitory effect of Ionol on lipid peroxidation (LPO) in the infarction zone and out of it after experimental myocardial infarction in the experiments on rats was investigated. The results of measurements, performed by two independent methods: point counting and the computer image analysis were compared. It was shown that LPO activation out of the ischaemic zone was prevented and dimensions of the ischaemic necrosis were limited by Ionol, which did not influence LPO activation in the ischaemic zone. Data obtained by both methods coincide qualitatively, the computer image analysis being more sensitive and effective.

[Microcirculatory disorders in acute ischemia of the small intestine and in the postischemic period]. / Narusheniia mikrotsirkuliatsii pri ostroi ishemii tonkoi kishki i v postishemicheskom periode.

Microcirculation in the small intestine of rats during ischemia (from 5 to 240 minutes) and in the period of reperfusion (from 60 minutes to 10 days) was studied by biomicroscopy. Ischemia was modelled by ligating the base of the intestinal loop. Sharp microhemodynamic disorders occurred during ischemia, compensatory mechanisms intensifying the blood flow were switched on, the microvascular channel, including vessels which previously did not function, were dilated. Mechanisms concerned with redistribution of fluid in the intra- and perivascular space were evidently the underlying factors of capillary dilatation. In the late-term periods of reperfusion ischemia leads to increase of the number of microvessels in the ischemic part of the organ.

[The distribution of blood flow velocity in the terminal bed of the rat mesentery]. / Raspredelenie skorosti krovotoka v terminal'nom rusle bryzheiki krys.

Blood flow velocities in microvessels of the rat intestinal mesentery were determined by means of prism-grating method. Mean velocity values in arterioles were 1.9 +/- 0.1, in venules 1.2 +/- 0.2, in capillaries 0.82 +/- 0.06 and in arteriole-venule anastomoses 1.7 +/- 0.2 mm/s. These values do not vary significantly in arterioles with internal diameter from 23.2 to 6.9 mm and in venules from 7.2 to 28.2 mm. The most significant velocity changes appear in the passage of arterioles into capillaries (50%) and between capillaries and venules (40%).

[The role of circular and tangential smooth-muscle fibers in arteriole constriction and closure]. / Rol' tsirkuliarnykh i tangentsial'nykh gladkomyshechnykh volokon v suzhenii i zakrytii arteriol.

Equations reflecting relationships between the thickness of blood vessel wall (w) and internal radius (r) of the vessel during the process of smooth muscle fiber contraction involved two types of the fibers orientation in vessel wall: at an angle of 45 degrees and 90 degrees to the longitudinal axis of the vessel. Experimental values of w and r were determined on arterioles of the rat mesentery after vasopressin or epinephrine administration. According to the degree of longitudinal and transversal efforts participation in the process of vessel closure, heterogeneity of the arterioles was revealed by comparison of the theoretical and experimental values of w and r. The ability of arterioles for closure did not depend on the initial value of relative vessel wall thickness (w/r).

[Rheologic and morphometric parameters of the microcirculation bed in the rabbit ear following local ischemia]. / Reologicheskie i morfometricheskie parametry mikrotsirkuliatornogo rusla ukha krolika posle lokal'noi ishemii.

Microvessels of the rabbit ear chamber and blood samples drawn from the internal ear vein were studied after 30-min ischemia. Total microvascular bed area augmented by 16%, total microvascular bed length increased by 9% and mean microvascular diameter increased by 6.7%. One hour after the onset of ischemia it is only the diameter that remains augmented. In the control experimental series apparent viscosity of the blood flowing from the ischemic area did not correlate with the degree of vascularization, negative relation with vessel length (p = --0.461) and positive relation with the diameter (p = 0.799) being revealed. After ischemia only the viscosity-diameter relation remained significant (p = 0.466). The correlation matrix 10 X 10 which reflected the connection between other parameters characterizing specificity of blood supply regulation is given.