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Biomedical subjects

A A Lebedev

Publications and source records attributed to A A Lebedev.

At least 73 records · Page 4Linked to original sources
PubMed1977

[Water-electrolyte disorders in the acute period of a stroke].

In 100 patients with different forms of cerebral strokes the author studied the general water content. Its distribution in the organism. Na and K concentration in the plasma and erythrocytes and the general electrolyte content in spaces of the body. It was established that the most frequent syndromes of water-electrolyte disorders in the acute period of strokes is intracellular or general hydratation (81%). In parenchymatous-subarachnoidal hemorrhages the general dehydratation was combined with a hyperhydratation of the extracellular space, while in sichemic strokes there was an anhydridemia up to 10-18 days. A disturbance of the electrolyte metabolism was also expressed in a transmineralization with a drop of the general Na and K content due to intracellular losses. The K deficit was averagely 29% and the Na--15.5% and should be taken into consideration in a substitutive hydro-electrolyte therapy. Solutions with an increased K content should be used in order to compensate its deficit.

Acute Disease↗
PubMed1976

[The hydrodynamics of the superficial cortical nephrons of the rat kidney during a diuretic response].

Diuretic response to administration of mannitol, furozemide, ethaerynic acid, and euphyllinum was invariably followed by a considerable dilation of the lumen of proximal and distal tubular of the kidney surface nephrones. Simultaneously, a considerably reduced flow of the tubular fluid was always observed except after euphyllinum administration, the latter being followed by acceleration of the flow. Questions of interrelationships between the nephrone's hydrodynamic characteristics and the processes of glomerule filtration and tubular reabsorption of the fluid and electrolytes, are discussed.

Aminophylline↗
PubMed1976

[Effect of catecholamines on sodium resorption and oxygen tension in rat kidneys].

Functional significance of alpha- and beta-adrenoreceptors for the mechanism of catecholamines effect on sodium reabsorption and oxygen tension in the rat kidney, was studied. Adrenaline inhibited sodium excretion decreasing its filtration in glomeruli and stimulating its reabsorption in tubules. The oxygen tension in these conditions did not change in the renal cortex while oxygenation of the external cortical layer was significantly increased. The blocking agent for alpha-adrenoreceptors phentolamin abolished the inhibiting effect of adrenaline on the glomerular filtration and somewhat decreased the degree of oxygen tension growth in the external cortical layer, leaving the tubular effect unaltered. The blocking agent for beta-adrenoreceptors inderal did not affect the inhibitory action of adrenaline on the glomerular filtration but completely prevented its activating effect on the tubular reabsorption of sodium and on oxygenation of the external cortical layer. A conclusion was drawn that catecholamines stimulation of sodium reabsorption in the rat kidney follows excitation of beta-adrenoreceptors. The increase in oxygen tension in the external cortical layer under effect of catecholamines is supposed to improve energetic supply of the sodium active transport in the ascending portion of the Henle loops.

Animals↗
PubMed1975

Effects of certain diuretics on the electrophysiological characteristics of the nephron in the rat kidney.

Electrophysiological micropuncture techniques were used to study the effect of certain diuretics on transtubular transport of electrolytes in the rat kidney. The mercurial diuretic novurite caused a reduction of active sodium transport in the proximal tubule, measured by short-circuit current and increased permeability of the tubular wall to ions which led to a considerable drop in transtubular potential and transepithelial resistance. Ethacrynic acid decreased the short-circuit current in the proximal tubule, without changing the permeability characteristics of the nephron. Xanthine diuretic euphylline did not reduce the short-circuit current in the proximal segment of the nephron; however, it increased the transepithelial potential of the renal tubule. In the distal tubule, euphylline and ethacrynic acid increased the difference in transtubular potential, whereas novurite reduced the transtubular potential. An increase in the electrical gradient of the distal tubule as a result of euphylline and ethacrynic acid action may be responsible for increasing potassium excretion. A decrease of the transtubular potential in the potassium excretion under mercurial diuretic action. The reduction of tubular reabsorption as a result of diuretic action is due to drug effect on different levels of the transtubular-ion transport system.

Aminophylline↗
PubMed1975

[Treatment of pseudarthrosis of the tibia by the method of traction].

The report is based on the experience with treatment, using the method of dosaged distraction of 39 pseudarthroses and unhealing fractures of the tibia in 38 patients. Twenty three patients showed osteomyelitis, 32-shortening of crural bones and 27-their deformation. With the aim of distraction the G. A. Ilizarov apparatus was employed. Up to data, the treatment is termined in all 38 patients. Healing was gained after 36 operations in 35 patients. No union was obtained after 3 operations of distraction the osteosynthesis in avascular forms of pseudarthrosis. Some regularities in formation of the regenerate and its reoconstruction during the process of lasting fixation were studied in 25 patients.

Adolescent↗
PubMed1975

[Diuretics as factors regulating electrolyte transport through the wall of the kidney tubule].

The effects of furosemide, hydrochlorthiazide, triamteren and mannitol on the intratubular potential, electric resistance of the wall of the proximal and distal renal tubule and also changes in the magnitude of the short-circuited current that give an idea as to the tubular transport of sodium in the proximal section of nephron were explored electrophysiologically on a renal nephron of the rat. Furosemide and hydrochlorthiazide depressed the magnitude of the short-circuited current in the proximal end of nephron and raised the transtubular potential. Hydrochlorthiazide also tended to increase the electric resistance of the renal tubule wall. Triamteren forced down the potential in the proximal end of nephron, as well as the magnitude of the short-circuited current, but did not change the tubular wall resistance. Mannitol drastically reduced the tubular wall resistance and the intratubular potential, without affecting the short-circuited current. A classification of diuretics by the mode of their action on the electric parameters of the nephron is given.

Action Potentials↗
PubMed1975

[Complications in extrafocal compression and distraction for nonunion of the tibia].

While analysing the results of 118 operations for extrafocal compression, distraction and compression-distraction osteosynthesis with the G. A. Ilizarov apparatus in 116 patients showing nonunion of fractures and pseudarthrosis of the tibia, the author observed 53 various complications among 40 operations (33.9%). 78 operations were without any complications (66.1%). The greatest number of complications was noted while using a distraction method. Some recommendations on the treatment and prophylaxis of such complications are given.

Fracture Fixation↗
PubMed1973

Some results of medical investigations performed during the flight of the research orbital station Salyut.

The paper presents the main results of physiological studies carried out during the flight of the Salyut station. Details of atmospheric composition, diet, provisions for personal hygiene, the on-board medical kit, prophylactic measures, work and rest schedule are given. Methods of investigation, particularly for studying the cardiovascular response, are described, including tests using the application of lower body negative pressure. The subjective and objective in-flight condition of the cosmonauts is dealt with in detail. An evaluation of the cardiovascular response is made, as compared with previous flights, both at rest and during tests. Results of clinical and biochemical studies of the blood, certain indices of visual perception and microbiological investigations are described. It is concluded that the observed physiological changes are reversible.

Adaptation, Physiological↗