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Biomedical subjects

B I Mazhbich

Publications and source records attributed to B I Mazhbich.

At least 19 recordsLinked to original sources
PubMed1995

Active and passive reaction of large arterial vessels to sublingual test with nitroglycerin.

The noninvasive method of oscillovasometry, devised previously, was applied to the estimation of arterial pressure, effective radius of large arterial vessels, a number of indices showing elastic vessel properties and change in tone of the vessels on the right upper limb just before sublingual administration of nitroglycerin (0.5 mg) to the patients and 4-5 min after it. A group of 96 patients with different levels of arterial pressure were examined. It was found that all the patients showed a pressure decrease and tachycardia, but about a half of them had a passive response in large arterial vessels in the form of a decrease in the vessel volume, while others showed a decrease in arterial vessel tone (vasodilation), i.e. an active vascular response. From the data we drew the conclusion that there are two types of vascular response (active and passive) and they do not depend on the initial level of arterial pressure. Nitroglycerin probably acts more effectively on large arteries with a high initial tone. The possible mechanism of this phenomenon is discussed.

Administration, Sublingual↗
PubMed1995

Transbronchial regional electroplethysmography of the lungs.

OBJECTIVE: The objective of this study was to describe a method of transbronchial regional electroplethysmography of the lungs. METHODS: The electrical resistance of a division of a lung, such as a segment or subsegment, as well as its pulsatile oscillation, were measured using a two-part process: A catheter-transducer was wedged into a small bronchus and the electrical resistance of a blood sample obtained from the same patient was measured. The electroplethysmograph (EPG) was developed for this purpose. The theory behind our method is based on a model of the lung as a three-component structure (blood-tissue-air). We performed experiments on isolated lung lobes of animals, using simultaneous electrometric and direct determination of physiologic indices for regional lung function. RESULTS: Equations have been proposed to calculate blood volume, Vb (+/- 10%); air volume, Va (+/- 11%); pulsatile increment of the blood volume, delta V (+/- 10%); and regional stroke volume, RSV (+/- 20%) per 100 cm3 of the lung. The proposed formulas yield an accuracy that is adequate for the clinical range of variations in Vb and Va, as well as delta V and RSV. Experiments on lung lobes indicate that the conductivity of lung tissue (gamma t) is not large. This allows one to calculate the above indices without our having obtained accurate values for conductivity. CONCLUSIONS: The method of Transbronchial regional electroplethysmography of the lungs is described and cases in which this method was used for clinical investigation are presented.

Adolescent↗
PubMed1993

[A stereological analysis of the tissue organization of the myocardium in long-term adaptation to alpine conditions].

Stereologic study of myocardium of Wistar rats after longterm living (during 10 months) at high altitude (at 3200 m above sea level) was carried out. It was shown that tissue reorganization of left ventricle myocardium under these conditions was characterized by significant decrease of the volume and surface densities of capillaries and endothelial cells, especially after living during 5 months in mountains. Simultaneously the processes of intracellular regeneration in cardiomyocytes were disordered, this manifesting as a rarity and lysis of sarcoplasm and also as atrophy of a part of cardiomyocytes. These changes were more pronounced after living during 10 months at high altitude.

Adaptation, Physiological↗
PubMed1991

[Postural changes in the pulmonary hemodynamics of rats under high-altitude conditions].

Transbronchial regional electroplethysmography and catheterization of pulmonary artery revealed alterations of pulmonary hemodynamic characteristics induced by changes of the gravitation body position in Wistar rats during 60- and 150-day stay at 3200-m altitude. The gravitational redistribution of blood volume and blood flow over various parts of lungs was less obvious than at the sea level. This seems to be due to a decreased compliance of the lung arterial vessels and to accompanying increased reactive part of hydraulic impedance.

Adaptation, Physiological↗
PubMed1989

Elasticity changes in the large arteries of human limbs in response to cycle ergometry performed with upper and lower limbs.

At rest and after cycle ergometry the elastic properties of the large arteries of limbs of healthy men were examined using an original non-invasive quantitative oscillometric method. It has been shown that in response to muscle work performed with the legs there is a decrease of the effective inner radius, and an increase of the characteristic impedance modulus and bulk modulus and of the elastic resistance of the intact and relaxed wall in the large arteries in the upper limbs. All these changes testify to an increase of vascular tension in the upper limbs. In response to work performed with the hands, there is an increase of the effective inner radius of large arteries of the upper limbs, a large increase of the pulsatile blood volume increment of the intact vessels and a decrease of the characteristic impedance modulus, of the bulk modulus and of the elastic resistance of the intact arterial wall. These changes indicate a decrease of the vascular tension of these arteries. In response to work performed either with the legs or with the hands a decrease of the effective inner radius of large arteries and an increase of the elastic resistance of the relaxed arterial wall were observed in the lower limbs, all these changes indicating relatively small changes in tone of these vessels. It is concluded that the wall tension of large arteries supplying blood to the muscles of non-working limbs is increased. Vascular tension changes in the arteries in working limbs are accounted for by the superimposition of centrally originating vasoconstriction with local vasodilatation, which also affects large arteries.

Adult↗
PubMed1989

[The hemodynamics of the lesser circulation and blood indices in rats under long-term high-altitude hypoxia].

Pulmonary hemodynamics in anesthetized rats was studied during long-term residence (2,5 and 10 months) at high altitude (3,200 m, Tien Shan). Transbronchial regional electroplethysmography and catheterization of pulmonary artery was used. It has been shown that at all periods of adaptation there was increased systolic pressure in pulmonary artery and practically unchanged diastolic one. Some regional redistributions of pulmonary blood flow and blood volume for five different lung parts were demonstrated. Hemoglobin content in erythrocytes was steadily increased while specific electric blood resistance, hematocrit, and number of erythrocytes did not change so significantly. The role of pulmonary arterial hypertension and changes of other studied indices of hemodynamics and red blood in adaptation to chronic high-altitude hypoxia are being discussed.

Adaptation, Physiological↗
PubMed1989

[The effect of high-altitude hypoxia on the lesser circulation in rats].

During ten-month stay at 3200 m altitude in the Tien Shan mountains a significant increase of systolic pressure and practically unchanged diastolic one in pulmonary artery were recorded in rats. A redistribution of the blood flow and volume occurred. An increased oxygen blood capacity was maintained through an elevated hemoglobin content in erythrocytes and an increase of their size but not of their number.

Altitude↗
PubMed1989

[Regional blood flow and air level in the lung segments in recurrent and chronic bronchitis in children].

Transbronchial regional electroplethysmography was employed to measure the blood flow and air content in 67 children aged 3-15 years. Of these, 44 children suffered from chronic bronchitis and 23 from bronchiectasis. Children with recurrent bronchitis examined during the inactive phase of the disease marked by clinicoendoscopic silence were used as controls. In children with chronic bronchitis who escaped bronchial deformity, the levels of the regional blood flow were similar to those seen in the controls. Meanwhile in diffuse deforming bronchitis the reduction of the blood flow was noted in the posterobasal segments on both sides. In local deformities and bronchiectasis the levels of the air content and blood flow were decreased in the affected area whereas in the adjacent part the blood flow was more intense as compared with the symmetrical part on the opposite side, which was likely to be connected with the irritative effect of the focus of lesion.

Bronchitis↗
PubMed1986

[Pressure in the pulmonary artery and transbronchial electroplethysmography in rats].

A complex technique for pulmonary circulation study involving catheterization of pulmonary artery and transbronchial electroplethysmography has been tested in rats. The technique permits pulmonary artery pressure measurement and registration of electrical resistance in the lung lobe of closed-chest animals with the subsequent estimation of blood flow, blood volume and air content in the lungs expressed in adequate units per unit of organ volume. The experimental data characterizing standard values of the above parameters in rats are presented.

Animals↗
PubMed1985

[Noninvasive quantitative determination of the modulus of characteristic impedance of human limb arteries].

A noninvasive method of quantitative evaluation of characteristic impedance modulus of human limb arteries based on blood pressure and blood vessel volume parameters is described. The differences in the value of characteristic impedance modulus in the upper and lower limb arteries in supine and resting subjects have been shown. Under postural effects the impedance changes in the lower limb arteries are proportional to those of mean blood pressure in these vessels. No significant impedance alterations on effort have been observed in these arteries. The impedance of the upper limb arteries increased in passive orthostatic position and after physical exercises of the lower limbs. Characteristic impedance modulus of these arteries decreased after physical exercises of the upper limbs.

Adult↗
PubMed1985

[Noninvasive assessment of the elastic properties and diameter of the major arterial vessels of the extremities in atherosclerosis].

A noninvasive method for the evaluation of the elastic properties of the major arterial vessels (the shoulder and lower third of the foot) in patients with arteriosclerosis and in healthy persons was previously worked out to study: elastic resistance of the intact and relaxed vascular wall, modulus of bulk elasticity, an internal (equivalent) vascular radius and some arterial pressure indices. A significant increment of elastic resistance of the relaxed wall of the arterial vessels was found in arteriosclerosis as compared to the control group which was unrelated directly with raised arterial pressure and could be used for diagnostic purposes. The presence of a high assymetry in a number of indices of the elastic behavior of the vascular wall on the same extremities suggested heterotopy and heterochronia of the changes observed.

Adult↗
PubMed1983

Noninvasive determination of elastic properties and diameter of human limb arteries.

A method involving application of a standard cuff on human limbs has been developed making it possible by a single procedure to make a quantitative determination of blood pressure, elastic resistance of "uninfluenced" an mechanically relaxed arterial vessel walls, their bulk modulus and effective inner diameter. The method which is based on the "elasticity reservoir theory" involves recording arterial pressure recordings during periods of gradual compression and evaluation of the pulsatile blood volume increment under the cuff at the on step wise decompression. The reproducibility of the results and the errors involved were estimated by comparing the results with measurements made on a physical model and on human limbs. This paper presents some results of the application of the method to 113 healthy persons and shows the age dependence of the examined parameters in the upper arms and in the lower leg.

Adolescent↗
PubMed1983

[Elastic properties of the arteries and hemodynamics of the human extremities during postural exposures].

A non-invasive method was applied to estimation of elastic properties, the effective inner radius, blood pressure, and a number of other parameters in limb arteries of healthy men under postural effects. The changes in elastic properties of arteries were shown to occur only in the lower limbs where gradient of hydrostatic pressure changed during the examination. In the arms, where this gradient is practically absent, elastic properties of arteries remained the same. The data obtained indicate that gradient of hydrostatic pressure is responsible for the changes observed.

Adult↗
PubMed1983

[Blood filling and elasticity of pulmonary vessels after section and stimulation of the vagus nerve].

Blood content and elasticity of lung vessels in the central and peripheral portions of the posterior lung lobes were measured in experiments on dogs with intact chest using regional electroplethysmography of the lungs and catheterization of pulmonary artery branches. Electric stimulation of vagosympathetic nerves in the central portion of the pulmonary lobe might give rise to a considerable increase in lung lobe blood content due to a neurogenic vasodilatory effect without pressure elevation in lung vessels. However, further increase in blood content was confined to reduced elasticity of these vessels and was hardly possible without a noticeable pressure rise in pulmonary circulation.

Animals↗