[Effect of steroid hormones on production of reactive oxygen species in mitochondria].

Among the targets of the steroid hormones are mitochondria, which as the main source of reactive oxygen species (ROS) in the cell play a central role in the development of various pathologies. We studied the effect of progesterone and its synthetic analogues on mitochondrial ROS production. It was found that progesterone activates the formation of superoxide anion and hydrogen peroxide in mitochondria during oxidation of complex I substrates of the respiratory chain and exerts no influence on production of ROS during oxidation of succinate, complex II substrate of the respiratory chain. Synthetic analogues of progesterone - medroxyprogesterone acetate, buterol, acetomepregenol, megestrol acetate, have different effects on ROS production, depending on their chemical structure. By the effectiveness of impact on ROS production in mitochondria all the steroids tested can be classified in the descending order as follows: progesterone > buterol > or = atsetomepregenol > medroxyprogesterone acetate > megestrol acetate. Activation of ROS production by progesterone and buterol has different mechanisms: progesterone acts as an inhibitor of NAD-dependent respiration, while buterol and acetomepregenol form noncovalently associated complexes by hydrogen bonds between the ester carbonyl at C3 and SH-groups of the respective targets.

Mechanism of superoxide anion generation in intact mitochondria in the presence of lucigenin and cyanide.

In the presence of cyanide and various respiratory substrates (succinate or pyruvate + malate) addition of high concentrations of lucigenin (400 microM; Luc2+) to rat liver mitochondria can induce a short-term flash of high amplitude lucigenin-dependent chemiluminescence (LDCL). Under conditions of cytochrome oxidase inhibition by cyanide the lucigenin-induced cyanide-resistant respiration (with succinate as substrate) was not inhibited by uncouplers (FCCP) and oligomycin. Increase in transmembrane potential (Deltaphi) value by stimulating F0F1-ATPase functioning (induced by addition of MgATP to the incubation medium) caused potent stimulation of the rate of cyanide-resistant respiration. At high Deltaphi values (in the presence of MgATP) cyanide resistant respiration of mitochondria in the presence of succinate or malate with pyruvate was insensitive to tenoyltrifluoroacetone (TTFA) or rotenone, respectively. However, in both cases respiration was effectively inhibited by myxothiazol or antimycin A. Mechanisms responsible for induction of LDCL and cyanide resistant mitochondrial respiration differ. In contrast to cyanide-resistant respiration, generation of LDCL signal, that was suppressed only by combined addition of Complex III inhibitors, antimycin A and myxothiazol, is a strictly potential-dependent process. It is observed only under conditions of high Deltaphi value generated by F0F1-ATPase functioning. The data suggest lucigenin-induced intensive generation of superoxide anion in mitochondria. Based on results of inhibitor analysis of cyanide-resistant respiration and LDCL, a two-stage mechanism of autooxidizable lucigenin cation-radical (Luc*+) formation in the respiratory chain is proposed. The first stage involves two-electron Luc2+ reduction by Complexes I and II. The second stage includes one-electron oxidation of reduced lucigenin (Luc(2e)). Reactions of Luc(2e) oxidation involve coenzyme Q-binding sites of Complex III. This results in formation of autooxidizable Luc*+ and superoxide anion generation. A new scheme for lucigenin-dependent electron pathways is proposed. It includes formation of fully reduced form of lucigenin and two-electron-transferring shunts of the respiratory chain. Lucigenin-induced activation of superoxide anion formation in mitochondria is accompanied by increase in ion permeability of the inner mitochondrial membrane.

Lucigenin-derived chemiluminescence in intact isolated mitochondria.

There are many data both in favor and against the use of lucigenin as a probe for superoxide anion (SA) in mitochondria, cells, and simple enzymatic systems. In the present work high concentrations (50-400 micro M) of lucigenin were used for continuous recording of rapid and reversible changes in the SA level in intact isolated mitochondria. The SA level in the presence of lucigenin rapidly and reversibly changed during the transition of the mitochondria from one functional state to another: under conditions of ATP synthesis from ADP and Pi, of Ca2+ accumulation, and of reverse electron transfer. Induction of a Ca2+,cyclosporin A-sensitive pore in mitochondria completely suppressed the lucigenin-derived chemiluminescence (LDC). The electron transfer in the Q-cycle of the respiratory chain complex III and high electric potential difference across the inner membrane of mitochondria were obligatory conditions for generation of a SA-dependent chemiluminescent signal. Based on our own and literature data, a scheme of LDC generation is suggested. The origin of superoxide anion detected in intact mitochondria with lucigenin is discussed.

Combined vitamins Bl2b and C induce the glutathione depletion and the death of epidermoid human larynx carcinoma cells HEp-2.

The combination of hydroxocobalamin (vitamin B12b) and ascorbic acid (vitamin C) can cause the death of tumor cells at the concentrations of the components at which they are nontoxic when administered separately. This cytotoxic action on epidermoid human larynx carcinoma cells HEp-2 in vitro is shown to be due to the hydrogen peroxide generated by the combination of vitamins B12b and C. The drop in the glutathione level preceding cell death was found to be the result of combined action of the vitamins. It is supposed that the induction of cell death by combined action of vitamins B12b and C is connected to the damage of the cell redox system.

[Puncture methods of the diagnosis and treatment under the control of US, CT and X-ray video image]. / Punktsionnye metody diagnostiki i lecheniia pod kontrolem UZ, KT i rentgenotelevizionnogo izobrazheniia.

Exploratory and therapeutical punctures were made in 454 patients under the control of ultrasound, CT, and X-ray teleimage. Diagnostic biopsies established the cytological and histological nature of diseases in 67.6% of cases, positive ultrasound-, CT-, and X-ray teleimage-controlled biopsies being 76.3, 64.9, and 71.4%, respectively. Beneficial effects of therapeutical interventions were obtained in 89.5% of patients.

[Role of tests of the total pressure of gases (O2 and CO2) in blood plasma in studying gaseous homeostasis in man]. / Rol' testov po summarnomu davleniiu gazov (O2 i CO2) v plazme krovi pri izuchenii gazovogo gomeostaza u cheloveka.

Sixty essentially healthy subjects were examined manometrically with blood withdrawn from the coronary sinus, pulmonary artery, aorta, veins of the right kidney and the right liver lobe. Together with the traditional parameters of the gas contents and gradients of plasma, it is proposed to use tests measuring additive O2 and CO2 parameters. It has been demonstrated that the above organs can be discriminated using tests that are additive with respect to the gas pressure. It is emphasized that the tests proposed here, when used in addition to the traditional ones, allow identification of the gas and non-gas parameters of homeostasis as a single system of tests to assess the human body function.