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Biomedical subjects

V M Vitvitskiĭ

Publications and source records attributed to V M Vitvitskiĭ.

At least 19 recordsLinked to original sources
PubMed1999

[Detrimental effects of Daunorubicin and Doxorubicin on human erythrocytes in vitro].

In isotonic medium, daunorubicin in the concentration range of 0.5-5.0 mg/ml of cells and doxorubicin in the concentration range of 0.2-1.0 mg/ml of cells caused hemoglobin (Hb) and K+ to efflux from red blood cells (RBC), to increase RBC size and to lower their deformability. Hb and K+ efflux rates were proportional to the antibiotic concentrations and remained stable for a few hours. Hb efflux did not change significantly in the 4-21 degrees C range (exempt at an experimental concentration of daunorubicin of 5.0 mg/ml of cells) but soared sharply at 37 degrees C. At the daunorubicin and doxorubicin concentration of 0.2 mg/ml of cells, Hb and K+ efflux virtually did not differ from control values. At the antibiotic concentration of 1.0 mg/ml of cells, 37 degrees C, Hb efflux rate was 0.34-5.6%, while that of K+(-) 1.0-8.2%, per hour, of possible maximum value. For the daunorubicin level of 5.0 mg/ml of cells, the respective values were 10 and 17%. At the daunorubicin concentration of 5.0 mg/ml, at 4 degrees C, Hb efflux from RBC was significantly higher than at 21 degrees C. RBC malleability, which was determined as their ability to pass through membrane filters having 3 mm dia pores, did not differ significantly from control values for a few hours antibiotic concentrations not exceeding 0.3 mg/ml of cells. At the antibiotic concentration of 1.0 mg/ml and higher RBC deformability dropped to zero within 10 min. ATP level in RBC practically remained identical to control values during incubation with the antibiotics for several hours.

Antibiotics, Antineoplastic↗
PubMed1999

[Immobilized forms of daunorubicin in patients with acute leukemia].

AIM: To study pharmacokinetics of liposomal daunorubicine DaunoXome and daunorubicine (rubomycin) associated with red cells: to assess their effectiveness and toxicity in patients with acute leukemia. MATERIALS AND METHODS: 7 patients with resistant or recurrent acute leukemia entered the trial. Of them 2 patients had acute myeloid leukemia. They received DaunoXome in dose 100 mg in days 1, 2 and 3 of 7 + 3 program. 1 patient had pretreated acute promyelocytic leukemia. This patient received 5-day course of DaunoXome in a dose 100 mg in the presence of ATRA therapy. 4 patients were given single dose daunorubicin associated with autoerythrocytes in the courses RACOP and 7 + 3 in a dose 45 mg/m2. Concentrations of free, bound and liposomal daunorubicin were determined spectrofluorimetrically in chlorophorm extracts of plasm, blood, liquor and bone marrow specimens. RESULTS: Immobilization of daunorubicin on the red cells and liposomes changes pharmacokinetics of the drug: peak concentrations change and the area under the concentration curve increases. Tolerance of DaunoXome and daunorubicine associated with red cells was satisfactory in all the cases: clinical and echo-CG signs of cordiotoxicity were absent, myelotoxicity was similar to that of free daunorubicine. DaunoXome was effective in 2 of 3 patients with acute myeloblastic leukemia. CONCLUSION: The findings are of practical interest for physicians designing new programs of therapy of acute leukemia.

Adolescent↗
PubMed1996

[Energy-dependent processes and metabolism of adenylates in human erythrocytes].

Amphotericin B (1-3 mg/l) decreases the ATP content in erythrocytes by 11-26% and stimulates the K+ efflux but has no effect on the adenylate pool. Adenosine added to the erythrocyte suspension increases the adenylate pool, maintains a high intracellular ATP level for 6-8 hours of incubation at 37 degrees C and diminishes the amphotericin B-induced leakage of K+. Incubation of erythrocytes without glucose for 4-5 hours leads to a 20-50% loss of ATP accompanied by a significant reduction of the adenylate pool. Further addition of glucose partly restores the ATP level. In the presence of adenosine the ATP concentration is restored far more pronounced reaching nearly the original level due to the increase of the adenylate pool.

Adenine Nucleotides↗
PubMed1993

[A filtration study of erythrocyte deformability].

The study of two flow methods (constant flow method and initial flow rate method) has been conducted to specify and compare methodological approaches to quantitation of red cell deformability. Washed red cells were resuspended in saline medium with glucose and albumin and examined for deformability by the above methods under different conditions. The parameters are presented to characterize flow curves obtained with the constant flow method. The authors have established optimal conditions for the measurements: the composition of the medium, the suspension HCT, leukocyte number, filtrate types, etc. With meeting of the above methodological requirements, both the methods permit quantitation of red cells deformability and can be utilized for stored blood and erythrocyte mass quality control.

Blood Flow Velocity↗
PubMed1993

[Use of antibiotics and their combinations with immunomodulators in treatment of experimental salmonellosis in albino rats].

Efficacy of the combined therapy of experimental salmonellosis was studied on albino rats with using ampicillin, gentamicin, tetracycline and immunomodulators such as levamisole and quadevite. The influence of the combined chemoimmunotherapy on the indices of the nonspecific resistance of the animals i.e. the titers of lysozyme and beta-lysines, the complement activity and the blood serum bactericidal index was investigated. An increase in the survival of the animals exposed to the combinations of tetracycline with levamisole and quadevite by comparison with the animal survival after the monotherapy was revealed. The combinations of gentamicin with quadevite and tetracycline with the immunomodulators significantly increased the blood serum bactericidal index.

Adjuvants, Immunologic↗
PubMed1992

[Effect of combined preventive use of quadevit with antibiotics on the survival and humoral immune response in experimental studies].

An attempt to correct with quadevit immunodepression due to prophylactic administration of benzylpenicillin and gentamicin for 6 days provided positive results. There was a significant increase in the quantities of Ig 19S and Ig 7S after the animal immunization with the bacterial antigen, an increase in the number of the AFCs in the spleen of the albino mice in response to administration of sheep erythrocytes and an increase in the survival rate of the animals with salmonellosis. The simultaneous use of quadevit with cefamezine and erythromycin did not lower the unfavourable influence of the antibiotics on the immune status of the animals.

Amino Acids↗
PubMed1991

[Immunomodulating effect of levamisole in antibiotic therapy].

The use of ampicillin, benzylpenicillin, gentamicin, erythromycin, cefamezine or cephaloridine in combination with levamisole aimed at increasing their efficacy and correcting the adverse reactions was studied. Immunological activity of the antibiotics was comparatively characterized by using standard methods. It was shown that the character of the antibiotic effect on the basic factors of nonspecific resistance and immunity was heterogeneous. Schemes for using the antibiotics in combination with levamisole for correcting the detected disorders in the immunity status of the experimental animals were developed.

Adjuvants, Immunologic↗
PubMed1986

[Effect of pH on the regulatory characteristics of energy metabolism in human erythrocytes].

The glucose consumption rate versus ATP content in human red cells (regulatory patterns of glycolysis) and ATP concentration versus glucose uptake rate in red cell suspension (regulatory patterns of total ATPases), when the rate of glucose uptake is constant and lower than the rate of glucose consumption at physiological conditions, were measured at different pH values. The shape of both types of kinetic curves was found to be dependent on the pH of the incubation medium but the same for the red cells taken from different donors. It is supposed that at alkaline pH, glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase reactions become the rate-limiting steps of glycolysis instead of hexokinase and phosphofructokinase under physiological conditions.

Adenosine Triphosphate↗
PubMed1986

[Metabolic changes leading to oxidative lysis of erythrocytes maintained in a normal state in vitro].

It was shown that in vitro oxidative hemolysis of human erythrocytes occurs as a result of a great increase in membrane permeability to cations leading to osmotic damage of the cells. Infusion at a steady rate with a solution of tert-butylhydroperoxide in an erythrocyte suspension resulted in a rapid fall of the reduced glutathione level down to 0, when the rate of infusion exceeded the maximal rate of pentose phosphate pathway. Under these conditions the potassium ions liberation from the erythrocytes began with the drop of the reduced glutathione level down to zero, and the hemoglobin liberation - at the moment when more than 60% of potassium ions were liberated from the erythrocytes. The kinetics of potassium ion liberation remained unchanged in anisotonic media, but hemoglobin liberation from the erythrocytes greatly increased in hypotonic media as compared with isotonic ones. The kinetics of K+ and hemoglobin liberation were correlated only with lipid peroxidation but not with the oxidation of protein SH-groups.

Cell Membrane Permeability↗
PubMed1985

[The 2,3-diphosphoglycerate shunt and stabilization of the ATP level in mammalian erythrocytes].

The mechanisms of regulation of energy metabolism in erythrocytes of various mammalian species were investigated. In native erythrocytes of man, sheep, cow, dog and mouse the dependencies of the rates of glucose uptake on ATP concentration (i.e., regulatory parameters of glycolysis) were measured. These parameters plotted in normalized coordinates are not species-specific (invariant). The dependence of the rate of ATP-consuming processes on ATP concentration has been studied for the first time in intact mammalian erythrocytes. This dependence was found to be linear only in the species, in whose erythrocytes the activity of 2,3-diphosphoglycerate shunt is practically zero. In all species under study, the stabilization of ATP level is provided for mainly by the hexokinase-phosphofructokinase system. A comparison of regulatory mechanisms of energy metabolism in mammalian (sheep, cow) erythrocytes, in which the 2,3-diphosphoglycerate shunt is absent, with human and animal erythrocytes, in which this pathway is active, points to the important role of the 2,3-diphosphoglycerate shunt in regulation of energy conversion in erythrocytes. This shunt operates as an additional stabilizer protecting the cell from extremal influences.

2,3-Diphosphoglycerate↗
PubMed1985

[Permeability of human erythrocytes to asparagine].

Asparagine is able to penetrate into human erythrocytes from the external medium. The dependence of the asparagine transport rate on its concentration can be described by the Michaelis-Menten equation with parameters: Km = 2.50 mM, V = 0.24 mmol/l cells per hour. Loading of erythrocytes with asparaginase does not influence their permeability to asparagine. Aspartate is accumulated inside these erythrocytes during incubation with asparagine, thus reflecting rapid transformation of penetrating asparagine by entrapped asparaginase.

Asparaginase↗
PubMed1984

[Steady-state dependence of the methemoglobin reduction rate on its concentration in intact human erythrocytes].

The rate of methemoglobin reduction by the methemoglobin reductase system of intact human erythrocytes was measured as a rate of pyruvate formation in a quasi-steady state. Various methemoglobin concentrations (up to 100%) were generated by sodium nitrite additions. The steady state methemoglobin levels were maintained by infusion of a nitrite solution at a rate of 2.8 mmol/h/l cells. The rate of pyruvate formation was proportional to the steady state methemoglobin concentration in the range from the physiological value to 100%, the maximal value being as high as 500 mumol/h/l cells. It was found that the rate of CO2 output by the erythrocytes markedly increased in the presence of 8 mM sodium nitrite, reaching up to about 40% of the possible maximal value.

Carbon Dioxide↗
PubMed1984

[Effect of glycolysis on the metabolism of adenylates in human erythrocytes].

The ATP content in human erythrocytes depleted without glucose falls down to half of the initial value within 2-3 hours and reaches practically zero within more than 10 hours. The ADP content increases 2-3-fold during the 1st hour after depletion and then slowly decreases. The AMP content increases 10-fold during several hours, but the rate of this process constantly decreases. The adenylate pool decreases at a constant rate ranging from 0.13 to 0.25 mmol/l cell. h; this is accompanied by accumulation of IMP. Addition of glucose to depleted erythrocytes results in partial recovery of the ATP level within 1-2 hours. The sooner glucose addition after the depletion, the greater the recovery. Simultaneously the ADP and AMP levels drastically decrease to new constant values. The decline of the adenylate pool ceases and the rate of IMP accumulation increases. Normally, the [ATP]/adenylate pool ratio lies within the small interval 0.85-0.94 irrespective of significant individual differences in the absolute values of [ATP]. This ratio is decreased during depletion and restored to the initial value after glucose addition. The mass-action ratio of the adenylate kinase reaction changes greatly during depletion and restoration of erythrocyte ATP.

2,3-Diphosphoglycerate↗
PubMed1982

[Regulatory characteristics of glycolysis in erythrocytes of sheep].

The regulatory properties of glycolysis in sheep erythrocytes (i. e. dependence of the rate of glucose uptake on ATP concentration) were investigated. A decrease of ATP concentration in the erythrocytes by arsenate causes a sharp rise in the rate of glycolysis, the maximal rate being reached at ATP concentration of about 70% of the original one. Further decrease of ATP lowers the rate of glycolysis; no steady-state rates of energy metabolism are observed within this concentration range. The parameters of glycolysis measured in erythrocytes of various species coincide when the rates of glycolysis are normalized in terms of its maximal value and that of ATP -- in terms of its value at which the maximal rate is reached. The identities of regulatory properties of glycolysis take place even upon two-fold differences in the absolute values of rates and concentrations.

Adenosine Triphosphate↗
PubMed1980

[Mathematical model for energy metabolism in erythrocytes. Independence of scaled glycolytic characteristics of individual features of the donors].

A mathematical model for energy metabolism of erythrocytes includes the first three enzymes of the Embden-Meyerhof pathway as well as total ATPase. It was assumed that the ATPase is strongly inhibited by AMP. The model was used to calculate the dependence of the rate of ATP production and glucose consumption on ATP concentration, i. e. characteristics of glycolysis. The scaled characteristics were plotted in relative units, the normal physiological values of the rates of glucose consumption and ATP concentration being taken for 100%. It was shown that the scaled characteristics show a coincidence, the precision being 20%, when the values of the enzyme activities and other parameters of the model vary within 100%. This agrees with the data, where the scaled characteristics of glycolysis in different donors (in all donors) coincide with experimental precision, while the values of the rates and concentrations with respect to the absolute value varied within 100%.

Adenosine Triphosphatases↗