[DNA degradation and repair in human laryngeal carcinoma HEp-2 cells after combined exposure to vitamin B12b and ascorbic acid].

The formation and accumulation of DNA fragments containing no more than 23,000 pairs of bases were observed under exposure of human larynx epidermoid carcinoma cells (Hep-2) to "chemical nuclease", oxycobalamin (vitamin B12b) and ascorbic acid (vitamin C). The obtained DNA damages were repaired more slowly than those induced by gamma-irradiation in the dose adequate to the level of DNA damages. DNA reparation was not revealed after washing the cells from vitamin B12b and ascorbic acid, and in the course of cell incubation with ascorbic acid.

[Generation of reactive forms of oxygen by polymorphonuclear leukocytes during hepatoma growth in the peritoneal cavity of animals].

In the present work, an attempt was made to analyse generation of reactive oxygen species (ROS) by polymorphonuclear leucocytes (PMN) in the course of tumour growth, using chemiluminescence (CL). A multiple increase in the capacity of polymorphonuclear leucocytes of generating active forms of oxygen in the course of tumor growth was discovered. Two causes of this process were found.

[Cytotoxic effect of energy supply system inhibitors on cells from Ehrlich ascite carcinoma].

It was shown that inhibitors of oxidative phosphorylation (cyanide, rotenone, and oligomycin) and very low concentrations of exogenous prooxidants exerted a pronounced cytotoxic effect on Ehrlich ascites carcinoma cells. We propose that cell injury by reactive oxygen forms is the cause of the cytotoxic effect of the studied inhibitors. It was shown via flow cytometry that inhibitors of oxidative phosphorylation and exogenous prooxidants block cell progress in the cell cycle and induce appearance of cells with reduced DNA content.

[Digitonin-sensitive calcium pool and its change during synchronous division of Tetrahymena pyriformis cells].

A very significant intracellular pool of calcium, sensitive to digitonin action and different from one of free cytozolic Ca2+, has been shown to exist in the cells of ciliate protozoan T. pyriformis. Calcium content in digitonin-sensitive pool NdigCa2+ has been estimated throughout the cell cycle in synchronized culture of T.

[The effect of catecholamines on the luminol-dependent chemiluminescence of rat polymorphonuclear leukocytes].

The effects of catecholamines on reactive oxygen species (ROS) generation by polymorphonuclear leucocytes were studied using chemiluminescence (CL). It has been found that catecholamines in 10(-9)-10(-10) M concentration range are able to increase reactive oxygen species generation. Within the micromolar concentration range (10(-6)-10(-5) M) cetacholamines (CA) strongly suppress CL intensity and ROS production.

[Biological role and mechanisms of realization of the Crabtree effect in rapidly proliferating cells. The role of Ca2+ ions].

Characteristic differences in energy supply systems in normal differentiated cells versus rapidly proliferating cells including tumor cells are summarized. Previously suggested mechanisms of the Crabtree effect (inhibition of respiration by glycolysis metabolites) are specifically evaluated. The effect cannot be explained by the competition of glycolysis systems with oxidative phosphorylation for ADP and Pi.

[Conditions for optimal production of active oxygen forms by rat polymorphonuclear leukocytes].

Using the procedure of lysis by ammonium chloride followed by differentiation centrifuging, the fraction of cells containing polymorphonuclear leucocytes was isolated from the whole rat blood to study the conditions of optimal production of oxygen forms was determined from the chemiluminescent cell response in the presence of luminol. It was shown that chemiluminescent cell response depends on the temperature, pH and osmolarity of the medium as well as on the presence of various concentrations of Ca2+ in the incubation medium. The maximal chemiluminescent response of polymorphonuclear leucocytes was observed at 35-37 degrees C, pH 7,6, osmolarity of 0,15 and Ca2+ concentration of 5-10 mM.

[Redistribution of Ca2+ ions in Ehrlich ascites carcinoma cells under the action of deoxyglucose and inhibitors of the intracellular Ca2+- transporting system].

Changes in free cytoplasmic Ca2+ ([Ca2+]i) in Ehrlich ascites tumour cells were studied under the effect of deoxyglucose and agents which modify transmembrane Ca2+ fluxes. It was shown that the reason for deoxyglucose-induced [Ca2+]i increase in Ca2+ release from internal stores and the influx from the external medium. Mitochondrial metabolic inhibitors (oligomycin+KCN, oligomycin++uncouplers of oxidative phosphorylation) induce themselves some rise in [Ca2+]i and increase the deoxyglucose effect on [Ca2+]i significantly.

[Characteristics of reversible and irreversible Ca2+-induced efflux of Ca2+ from mitochondria in permeabilized Ehrlich ascites carcinoma cells].

The Cyclosporin A-sensitive mitochondrial permeability transition in Ehrlich ascites tumour cells has been investigated. It was shown that Ca2+ ions induce both the self-reversible and irreversible mitochondrial permeability transition. ADP effectively inhibits the reversible but has no effect on the irreversible permeability transition.

[The effect of fluorocitrate on oxygen consumption and Ca2+ transport in the mitochondria of liver cells].

The effect of fluorocitrate on oxidative reactions and energy production systems of rat liver mitochondria has been studied. It was shown that oxidation of endogenous substrates and malate with pyruvate as well as the phosphorylation of the added ADP were inhibited by fluorocitrate. Inhibition of oxygen consumption by fluorocitrate induced the efflux of Ca2+ ions from mitochondria and a decrease in the Ca(2+)-accumulating capacity.

[Use of the principle of reverse problems for detecting processes, occurring in cells suspended in culture. II. Distribution of glutathione, SH groups, and optical density in the E. coli cell cycle].

A method was proposed for calculating the content of intracellular components during the cell cycle of an individual cell. The principle of reverse problems was used in the mathematical model proposed. The model allowed us to calculate changes of intracellular parameters of an individual cell from corresponding parameters measured in the whole culture.

[Character and reasons for change in mitochondrial ATP content during auto-oscillation of ion currents].

The changes in the adenosine triphosphate content in the course of ionic flux oscillations in mitochondria were estimated by using the chemiluminescence method. The ATP concentration changes were shown to be of cyclic character; the oscillations in the ATP content were shifted by 180 degrees C against those of K+ fluxes. The oligomycin-induced oxidative phosphorylation blocking changed (but did not eliminate) the oscillational character of the ATP content in mitochondrial suspensions.

[Changes in cAMP levels in bacterial cells during the cell cycle].

The changes in the cAMP level during the cell cycle in the synchronous cultures of E. coli were demonstrated. Two maxima in the cAMP level were revealed during each generation period.

[Interpretation of the phenomenon of K+ transport activation in Escherichia coli during transition to anaerobiosis].

Earlier it was demonstrated that the transition of E. coli K-12 cells to anaerobiosis is accompanied by the activation of K+ uptake. K+ that are additionally accumulated during the transition to anaerobiosis are released from the cells after the turning on of the respiratory chain.

[Membrane-bound Ca2+ in the mitochondria of Ehrlich ascitic tumor cells].

Ca2+ transport in mitochondria of Ehrlich ascite tumour cells and in liver mitochondria has been compared. It has been shown that in tumour cell mitochondria unlike liver ones even small amounts of Ca2+ caused marked increase in membrane-bound Ca2+ level. Therefore, a decrease in the electro-neutral Ca2+ efflux, stabilization of mitochondria membranes and inhibition of phosphorylated respiration were observed.

[Redistribution of Ca2+ ions in lymphocyte suspensions after treatment with an ionophore].

Ionophore A23187 induces three-phase kinetics of reduction of chlorotetracycline (CTC) lauded lymphocyte fluorescence: fast reduction, low increase and lower reduction of fluorescence. We suggested the following explanation of kinetics. The first phase is extinguishing of the Ca2+ - CTC complex fluorescence induced by ionophore A23187 perturbation of the cell membrane, the second one is the energy dependent Ca2+ entry into the cell and the third one is the slow efflux of Ca2+ ions from the cell to concentration gradient.

[Effect of low temperature shock and extracellular ice formation on the external and cytoplasmic membranes of Escherichia coli cells].

The effect of low temperature shock and extracellular ice formation on the properties of the outer and cytoplasmic membranes of E. coli K-12 cells was studied. The shock released intracellular K+ ions and inhibited the respiratory activity of the cells, suggesting that the cytoplasmic membrane was damaged.

[Kinetics of oxygen consumption, luminescence of pyridine nucleotides and the cyanine dye 3',3'-diethylthiodicarbocyanine iodide after energizing Ehrlich ascites carcinoma cells with glucose].

It has been shown that in the absence of inhibitors of oxidative phosphorylation, changes in fluorescence of 3',3'-diethylthiodicarbocyanine iodide (dis-C2-/5/) in a cell suspension of Ehrlich's ascites carcinoma reflect those in the transmembrane mitochondrial potential. Addition of glucose to the cells in the presence of respiratory inhibitors similar to rotenon induces oscillations in the membrane mitochondrial potential due to H+-ATPase that uses glycolytic ATP. The described changes in energy metabolism parameters are determined by impairment of the interplay between glycolysis and oxidative phosphorylation.

[Description of mitochondrial K+-transport system during intensive physical work].

The content of potassium ions in rat liver mitochondria after intensive physical work (continuous swimming) is increased approximately 2-fold, while the rate of K+ efflux from the mitochondria is significantly reduced. A considerable increase of the "calcium capacity" and a decrease of the respiration rate in state 4 were found. The experimental results indicate that during intensive physical work the mitochondrial membrane resistance to the damaging effects is enhanced.

[Reversible changes in the volume of isolated mitochondria in the course of ion flux oscillations between the mitochondria and the medium].

Glutaraldehyde has been used for electron microscopic studies of mitochondrial volume fluctuation during Sr2+--induced oscillation of ion fluxes. It has been shown that the observed ultrastructural and fluctuations of mitochondria is reversible to correlate with light-scattering value as well as to the direction of ion transfer. Determination of the intramitochondrial volume at different stages of oscillatory cycle shows the increase in the volume during the process of swelling up to 2.

[Effect of fasting on the content and transport of potassium ions in rat liver mitochondria].

The paper deals with the effect of fasting on the content and transport of potassium ions in the rat liver mitochondria as well as on oxidative phosphorylation. It is shown that the concentration of potassium ions in the mitochondria under fasting lowers by 20-30% at an average as compared to the control. The rate of potassium ions release from the mitochondria in the presence of DNP also lowers.

[Permeability of the membrane of the Escherichia coli envelope for ethidium bromide].

The interaction of ethidium bromide, a fluorescent dye, with Escherichia coli cells was studied. The envelope of intact cells was shown to be impermeable for ethidium bromide molecules. The dye penetrated however into E.