PubMed Health⌕ Search

Biomedical subjects

A V Pichugin

Publications and source records attributed to A V Pichugin.

At least 19 recordsLinked to original sources
PubMed1989

[Lymphocyte subpopulations in the bone marrow of children].

Blood lymphocyte subpopulations, and bone marrow aspiration and biopsy materials were comparatively investigated in 10 children without hematologic or infectious diseases (the children had chest deformations and diaphragmatic hernias). Lymphocyte typing was conducted by the method of continuous cytofluorometry in a complete leucocyte suspension with the use of monoclonal antibodies. The results of the study have evidenced that the content of lymphocytes carrying T-cell markers in the aspiration material was twofold lower, and in the biopsy material fourfold lower than in the peripheral blood. The number of immature T-lymphocytes in the bone marrow is higher than their content in the peripheral blood. A total of 40% of aspiration cells and 60% of biopsy cells present in the lymphocytic window, do not carry lymphocytic markers. CD8+-lymphocytes prevail in the bone marrow.

Antibodies, Monoclonal↗
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

Transformations of glycolysis control characteristics in human erythrocytes during blood storage.

Changes in glycolysis control characteristics (dependence of glycolysis rate on ATP concentration) in erythrocytes were studied during the storage of donors blood with glucose citrate hemoconservant. During the first two weeks of storage the shape of glycolysis control characteristics in the erythrocytes could be shown to remain practically unchanged, which was represented by a bell-shaped curve such as in fresh erythrocytes. During this period the physiological point of glycolysis will move along the glycolysis control characteristics towards the maximum of the curve. Once the maximum of the physiological point has been reached, the shape of the curve can be seen to change. The maximum on the curve becomes less evident, moving down and to the left from its initial position. These changes will occur after two to four weeks of storage. In some cases the maximum on glycolysis control characteristics will disappear at the latest stages of storage. The changes observed will occur in blood of different donors at different moments of storage. The nature of the changes observed and their influence on erythrocyte viability are discussed.

Adenosine Triphosphate↗
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↗
PubMed1981

[Dependence of the rate of the pentose cycle reactions on the degree of glutathione reduction in erythrocytes].

The stationary dependence of the rate of pentose cycle in erythrocytes measured by CO2 production on the degree of glutathione reduction typical for the pentose cycle was established. The steady-state rate of oxidation from the physiological to maximal values was generated by the addition of tretbutylhydroperoxide, a substrate of the glutathione peroxidase reaction, to erythrocyte suspension at a constant rate. The steady-state rate of CO2 production was correlated with the rates of oxidant addition throughout the experiment. The parameters of the pentose cycle reactions under conditions when the maximal rate of the pentose cycle and glutathione pool (GSH+2 GSSG) are taken for 100%, coincided for all donors tested. The increase in the rate of pentose cycle from 0 to 60% of the maximal one had practically no effect on the concentration of GSH, which was as high as 90% of the overall glutathione pool, thus indicating a high stabilization degree of GSH (stabilization coefficient was about 15). A further increase of the rate up to maximal values resulted in a rapid fall of the GSH level down to 0. The data obtained support the previously described mathematical model for regulation of glutathione metabolism. The GSSG liberation from the erythrocytes was shown to be directly proportional to the stationary intracellular concentration of GSSG; the transport rate constant varied in different donors from 0.15 up to 0.6(-1). The increase of oxidation rates up to maximal values, when GSSG concentration was approximated to the glutathione pool leads to a reversible decrease of GSSG concentration, which destroys the steady-state equilibrium of the pentose cycle.

Carbon Dioxide↗
PubMed1981

[Interaction of the Embden-Meyerhof pathway and hexose monophosphate shunt in erythrocytes].

A mathematical model of glycolysis in human erythrocytes for the interaction between the Embden-Meyerhof and the pentose phosphate pathways has been developed. The characteristic surfaces, i. e. interdependencies between the rates of metabolite flows in both pathways and ATP and NADPH concentrations have been calculated. The model obtained is well correlated with the experimental data on glycolysis characteristic at low rates of the pentose phosphate pathway reactions. The model suggests that NADPH and GSH concentrations should be stabilized. At ATP and NADPH concentrations close to the physiological ones the Embden-Meyerhof and pentose phosphate pathways function practically independently. When the NADPH concentration is decreased below 80% of the physiological value, the system ceases to stabilize the ATP concentration. In its turn, a decrease of ATP concentration results in a corresponding decrease of the maximal rate of the pentose phosphate pathway.

Adenosine Triphosphate↗
PubMed1981

Regulation of glycolysis in human erythrocytes. The mechanism of ATP concentration stabilization.

The mathematical modelling of human erythrocyte energy metabolism has shown that stabilization of ATP concentration can be achieved if the curve representing the relation between glycolysis rate and ATP concentration (glycolysis characteristic) is bell-shaped with steeply descending part at physiologically normal ATP concentration. The glycolysis characteristic of human erythrocytes has been obtained experimentally. In erythrocytes of different donors the glycolysis characteristics are greatly different quantitatively, but have qualitatively similar bel-like shape with steeply descending part at physiologically normal ATP concentration. This characteristics can be made coincident for all donors if they are plotted in relative units taking for 100% the physiologically normal values of glycolysis rate and ATP for every individual donor. The coincidence of the normalized erythrocyte glycolysis characteristics for different donors can be achieved in the mathematical model of erythrocyte energy metabolism under the assumption that the phosphofructokinase rate depends effectively on the relation of ATP to adenylate pool and the total erythrocyte ATPase is strongly inhibited by AMP.

Adenosine Triphosphate↗
PubMedDate not supplied

[Quantitative model of human erythrocyte glycolysis. Region of cell viability determined by ATP concentration].

The boundaries of the cell vitality domain in the enzyme activity space are calculated on the basis of a mathematical model of erythrocyte glycolysis. The boundaries are determined by key metabolite concentrations. The results obtained are compared with experimental data related to erythrocytic enzymopathies. It is shown that theoretical boundary enzyme activities coincide with the activities of hexokinase and in some cases phosphofruktokinase in enzyme deficient erythrocytes.

Adenosine Triphosphatases↗
PubMedDate not supplied

[The recording of ATP in the erythrocytes using luciferase injected into the cells].

The luciferase preparation obtained from fireflies Luciola mingrelica has entrapped into the human erythrocytes by means of reversible osmotic lysis. The addition of luciferin to such erythrocytes leads to the appearance of luminescence, conditioned by the entrance of luciferin into the cells. Luciferin is uniformly distributed between cells and external medium. Luciferin transport through the erythrocyte membrane is a result of simple diffusion. Values of rate constant of luciferin transport through the membrane lie between 0.009-0.021 l/s 1 cells for erythrocytes of different donors. The maximum luminescence intensity increases monotonously with rise of temperature and luciferin concentration. The dependence of the maximum luminescence intensity on luciferin concentration is described by Michaelis kinetics. Obtained in different experiments, values of luciferase Michaelis constant for luciferin inside erythrocytes lie between 4.1-21.5 microM. Luminescence intensity of the luciferase containing erythrocytes depends on the intracellular ATP concentration. Under the same luciferin concentration the correlation of luminescence intensities of control erythrocytes with normal ATP level and erythrocytes depleted without glucose is near to correlation of their ATP concentrations. After the addition of glucose to the depleted erythrocytes their ATP concentration rises and luminescence intensity approaches to the level of control erythrocytes. Luciferase entrapment permit one to control rapid ATP concentration changes in the erythrocytes.

Adenosine Triphosphate↗
PubMedDate not supplied

[Characteristics of metabolism of human erythrocytes after long-term space flight].

Before and after the 150-day Salyut-7 flight the crewmembers were examined for their red blood metabolism, viz: major metabolic pathways (glycolytic and pentosophosphate), erythrocyte resistance, membrane permeability and lipid peroxidation rate. The resulting data indicate that the metabolic and membrane changes were not pathological and can be classified as adaptive.

Adenosine Triphosphate↗