In vitro effects of folic acid on γ-glutamyltransferase and glutathione reductase activities in malignant lung and thymus tumors

In vitro effects of folic acid (10⁻⁵, 10⁻⁴, and 10⁻³ M) on activities of γ-glutamyltransferase and glutathione reductase, the enzymes involved in glutathione metabolism, were studied in tissue samples obtained after surgical treatment of the lungs and thymus. Folic acid did not change γ-glutamyltransferase activity in lung cancer tissue, but in thymoma tissue this substance in a concentration of 10⁻³ M inhibited it by 16%. Folic acid had no effects on glutathione reductase activity in benign tumors and normal lung and thymus tissues, but increased this activity in thymoma and lung cancer tissues. Activation of glutathione reductase was probably related to binding of folic acid in the allosteric center of the enzyme, which probably induced conformational changes in the catalytic center, acceleration of electron transport from NADPH₂ to oxidized glutathione via flavin adenine nucleotide, and intense production of reduced glutathione. Translated fromByulleten', Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 422–425, October, 2000     

Factors of the ovarian cancer resistance to combined chemotherapy with platinum preparations

The glutathione content and the activities of glutathione reductase, glutathione peroxidase, and glutathione S-transferase were measured in biopsy samples of epithelial ovarian cancer. It is shown that in stages 3–4 of ovarian cancer the effectiveness of chemotherapy correlates with the glutathione content and activity of glutathione S-transferase. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 12, pp. 651–654, December, 1996     

Metabolic preparation MP-33 as inductor of cell glutathione and glutathione-dependent enzymes

Metabolic preparation MP-33 induces cell glutathione and activities of glutathione S-transferase and glutathione peroxidase. This effect depends on the preparation composition. Single injection of MP-33 to rats considerably activates glutathione-dependent systems in the liver, heart, and erythrocytes. MP-33 is a more potent inductor than reduced glutathione. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 7, pp. 56–59, July, 1999     

Modification of ethylmethane sulfonate-induced mytagenesis with adrenaline

Experiments withCrepis capillaris dry seeds show that pretreatment with adrenaline hydrochloride and adrenaline hydrotartrate significantly reduces the number of aberrations induced by the supermutagen ethylmethane sulfonate. The effective concentration ranges for adrenaline adrenaline hydrotartrate and hydrochloride are 10⁻¹–10⁻⁷ M and 10⁻³–10⁻⁷ M, respectively. Adrenaline hydrochloride is more effective than adrenaline hydrotartrate (79.1vs. 65%, respectively). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 427–429, October, 1998     

Regulation of Antioxidants and Phase 2 Enzymes by Shear-Induced Reactive Oxygen Species in Endothelial Cells

Exposure of vascular endothelial cells (ECs) to steady laminar shear stress activates the NF-E2-related factor 2 (Nrf2) which binds to the antioxidant response element (ARE) and upregulates the expression of several genes. The onset of shear is known to increase the EC reactive oxygen species (ROS) production, and oxidative stress can activate the ARE. ARE-regulated genes include phase 2 enzymes, such as glutathione-S-transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1), and antioxidants, such as glutathione reductase (GR), glutathione peroxidase (GPx) and catalase. We examined how shear stress affects the antioxidant/phase 2 enzyme activities and whether ROS mediate these effects. ROS production, measured by dichlorofluorescin fluorescence, depended on level and time of shear exposure and EC origin, and was inhibited by either an endothelial nitric oxide synthase (eNOS) inhibitor or a superoxide dismutase (SOD) mimetic and peroxynitrite (ONOO⁻) scavenger. Shear stress (10 dynes/cm², 16 h) significantly increased the NQO1 activity, did not change significantly the glutathione (GSH) content, and significantly decreased the GR, GPx, GST and catalase activities in human umbilical vein ECs. Either eNOS inhibition or superoxide radical (O₂^•−)/ONOO⁻ scavenging differentially modulated the shear effects on enzyme activities suggesting that the intracellular redox status coordinates the shear-induced expression of cytoprotective genes.     

Effect of endothelin-1 on DNA synthesis in tracheal epithelium and smooth muscle cells in newborn albino rats

Repeated (5-fold) intraperitoneal injections of 5×10⁻⁹ mol/kg endothelin-1 inhibited DNA synthesis in tracheal epitheliocytes and activated lipid peroxidation in the lungs of newborn rats. Endothelin-1 in a dose of 5×10⁻⁸ mol/kg stimulated proliferative activity of tracheal smooth muscle cells and intensified lipid peroxidation in the blood, which aggravated observed changes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 3, pp. 294–296, March. 2000     

Mechanism of heart-rate acceleration caused by stimulation of vagal centers in the frog

The mechanism by which heart rate is increased upon stimulation of vagal centers is studied using frog heart preparations perfused with Ringer—Locke solution containing atropine and/or benzohexonium. Atropine stimulates vagus-induced heart-rate acceleration in dilutions of 10⁻⁶ and 10⁻⁵ g/ml. In a dilution of 10⁻⁴ g/ml both atropine and benzohexonium abolish vagal tachycardia. Rausedyl (3–4 injections, 5 mg/kg, at 18–20-h interval) prevents tachycardia. Stimulation of both halves of the medulla oblongata increases heart rate to a greater extent than stimulation of one half. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 7, pp. 16–20, July, 1997     

Recycle of dialysate from the artificial kidney by electrochemical degradation of waste metabolites: Continuous reactor investigations

Experiments are described on the continuous electrolytic decomposition of urea in dialysate and dialysate minus glucose and/or acetate. It was found that in addition to the urea removed, the glucose and acetate were oxidised substantially, especially at the higher power levels, and that there was an excess of ClO⁻, ClO ₂ ⁻ and ClO ₃ ⁻ ions produced. A pH drop of about 1 unit (acetate present) and 3–4 units (acetate absent) was also observed. It is concluded that these side effects would preclude clinical application, and that future work should concentrate on methods of eliminating these effects.     

Xymedon restores T-cell immune response inhibited by γ-irradiationin vivo: Interrelations with Ca2+-ATPase and DNA-relaxing activities

High radioprotective activity of xymedon was shown in mice. Radioprotective effects of this preparation were accompanied by restoration of the delayed-type hypersensitivity response and Ca²⁺-ATPase activity in splenocytes which were inhibited by γ-irradiation (3 Gy). At concentrations of 10⁻³ and 10⁻⁶ M xymedon stimulated the activity of DNA topoisomerase-I of splenocyte nuclei. Here we discuss a mechanism of radioprotective effects of pyrimidine derivatives associated with the inhibition of apoptosis of lymphoid cells and the stimulation of proliferation and differentiation of lymphoid precursor cells. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 1, pp. 66–70, January, 1999     

Antioxidant properties of thiamine

Thiamine (10⁻⁴–10⁻⁶ M) inhibits lipid peroxidation in rat liver microsome and free radical oxidation of oleic acidin vitro. Thiamine interacts with free radicals and hydroperoxides and is oxidized to thiochrome and thiamine disulfide. The antioxidant effect of thiamine is probably related to sucessive transfer of 2H⁺ from the NH₂ group of the pyrimidine ring and H⁺ from the thiazole ring (after its opening) to reactive substrates. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 9, pp. 303–305, September, 2000     

Antioxidant properties of thiamine

Thiamine (10⁻⁴–10⁻⁶ M) inhibits lipid peroxidation in rat liver microsome and free radical oxidation of oleic acidin vitro. Thiamine interacts with free radicals and hydroperoxides and is oxidized to thiochrome and thiamine disulfide. The antioxidant effect of thiamine is probably related to sucessive transfer of 2H⁺ from the NH₂ group of the pyrimidine ring and H⁺ from the thiazole ring (after its opening) to reactive substrates. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 9, pp. 303–305, September, 2000     

Effect of ultralow doses of thyroliberin on microviscosity of lipid components of biological membranes

Effects of the regulatory peptide thyroliberin on microviscosity of lipid components of endoplasmic reticulum biological membranes in mouse hepatocytes were studied by electron paramagnetic resonance. Thyroliberin in a concentration of 10⁻³–10⁻¹⁸ M decreased microviscosity of surface layers of membrane lipids. This decrease was the most pronounced (30%) under effects of 10⁻¹⁰ and 10⁻¹⁶ M thyroliberin. Physiological effects of thyroliberin corresponded to its influence on the membrane structure. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 1, pp. 38–40, January, 2000     

Factors influencing the immunomodulating effect of met-enkephalin: Role of mitogen dose,stage of cell activation,and time of opioid administration

Met-enkephalin in a concentration range of 10⁻¹⁵ to 10⁻⁹ M exhibited an immunomodulating effect upon concanavalin A-induced proliferation of mouse lymphocytesin vitro. The effect of met-enkephalin was shown to depend on the stage of lymphocyte activation, the time of opioid administration, and the dose of mitogen. Met-enkephalin produced the maximal effect when given in the phases of increase or decrease of the proliferative response. Met-enkephalin augmented the proliferative response to the suboptimal dose of concanavalin A and, on the contrary, inhibited the response to the optimal dose of mitogen. Administration of met-enkephalin at different times could both inhibit and stimulate proliferation depending on the stage of lymphocyte activation. An inhibitory effect was induced by δ-class opioid ligand, while κ-ligand was responsible for stimulation. Naloxone abolished the stimulating effect of opioids. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp. 398–401, April, 1995 Presented by R. V. Petrov, Member of the Russian Academy of Medical Sciences     

Effects of the nootropics piracetam and GVS-111 on voltage-dependent ion channels of neuronal membranes

The effect of two nootropics, piracetam and N-phenylacetyl-L-prolyglycine ethyl ester (GVS-111), is studied by measuring high-threshold K⁺ and Ca²⁺ currents in isolated snail neurons using a two-microelectrode patch-clamp technique. Piracetam and GVS-111 are shown to reduce the amplitude of both the K⁺ and the Ca²⁺ (to a lesser extent) current. The threshold concentrations for GVS-111 and piracetam are 10⁻⁹-10⁻⁸ M and 1–5×10⁻⁴ M, respectively. It is assumed that the antiamnestic effect of the nootropics is partially mediated by a blockade of ion channels of the neuronal membrane. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 151–155, February, 1996 Presented by G. N. Kryzhanovskii, Member of the Russian Academy of Medical Sciences     

Effects of dose and administration mode of endothelin 1 on the mean arterial pressure and heart rate in awake rats

The effects of bolus administration and short-term infusion of endothelin 1 in four doses (2×10⁻¹⁶, 2×10⁻¹⁴, 2×10⁻¹², and 2×10⁻¹⁰ mol/kg) on arterial pressure and heart rate were compared in awake rats. Infusion and bolus administration of the two highest doses increased arterial pressure and provoked bradycardia. Infusion of the two lowest doses increased heart rate without concomitant changes in arterial pressure, while bolus injection of endothelin 1 in the same doses decreased both arterial pressure and the heart rate. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 11, pp. 491–494, November, 1997     

Effects of synthetic bis-β-chloroethylamine estrogen derivatives on proliferation of skin sarcoma cells

The effects of four new synthetic bis-β-chloroethylamine-containing estrogens and known cytostatic agents chlorophenacyl and estradiol mustard were compared on monolayer cultures of transformed L-929 fibroblasts (from murine skin sarcoma). The drugs within the concentration range of 10⁻⁵-5×10⁻⁷M inhibited proliferation of cultured cells by 67%. Chlorophenacyl displayed the least antiproliferative activity (15% inhibition at 10⁻⁵M). Steroid nucleus introduced into the molecule enhanced antiproliferative activity of test drug in comparison with chlorophenacyl, probably due to accumulation of the hormone-cytostatic molecules in cells. Estradiol had no effect on proliferative activity of L-929 cells, and no specific estrogen-binding sites were found in cultured transformed fibroblasts. The antiproliferative effect of hormone-cytostatics on this culture is not mediated via specific interactions with estrogen receptors. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 6, pp. 695–697, June, 2000     

Effect of muscimol on the picrotoxinand bicuculline-induced delay in the desensitization of the GABA receptor/Cl− channel complex

Effects of picrotoxin and bicuculline on the muscimol-dependent³⁶Cl⁻ entry into synaptoneurosomes of the rat cerebral cortex are examined as well as desensitization of³⁶Cl⁻ entry at muscimol concentrations of 5 and 50 μM. At the 5 μM concentration (which is close to the muscimol IC₅₀), picrotoxin and bicuculline inhibited Cl⁻ entry into synaptoneurosomes and decreased the desensitization. At the 50 μM concentration, muscimol completely abolishes the bicuculline effects both on Cl⁻ entry and desensitization. Inhibition of Cl⁻ entry by picrotoxin is also abolished by 50 μM muscimol, whereas the picrotoxin-induced decrease in the desensitization rate is not. It is shown that both bicuculline effects result from inhibition of the GABA receptor, but the action of picrotoxin on the desensitization of Cl⁻ entry into synaptoneurosomes is not closely related to the functional activity of the GABA receptor/Cl⁻ channel complex. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 8, pp. 144–147, August, 1996     

Effect of the phenol antioxidant katavidan on autooxidation of microsomes exposed to visible light

A study is performed of the effect of the phenol antioxidant katavidan on autooxidation of microsomes from rat liver exposed to visible light. It is shown that katavidan in a concentration of 10⁻³ M inhibits but in concentrations of 10⁻⁵–10⁻⁷ M stimulates autooxidation of microsomes. No stimulation is observed under conditions of dark incubation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, № 10, pp. 393–394, October, 1994 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Effect of some lectins on the cholinergic structures of the frog heart

The effect of lectins (phytohemagglutinin — PHA, concanavalin A — ConA,Pisum sativum lectin — PSL,Ricinus communis lectin — RCL, and pokeweed mitogen — PWM) on the cardiac cholinoceptors is studied in experiments on isolated hearts of maleRana temporaria frogs. The test lectins in concentrations from 10⁻²³ to 10⁻³ are shown to exhibit cholinomimetic properties. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 252–255, September, 1994 Presented by A. D. Ado, Member of the Russian Academy of Medical Sciences     

Effect of elementary proline-containing peptides on functional activity of anticoagulation system and primary homeostasis

Elementary proline-containing peptides being added to rat platelet-rich plasma or platelet suspension in concentrations of 10⁻¹–10⁻⁷ mg/ml elicit a considerable antiplatelet effect. Efficiency of inhibition of platelet aggregation increases in the following order: Pro-Gly>Pro-Gly-Pro>Gly-Pro-Gly-Gly. Intravenous injection of these peptides activates blood anticoagulation system in experimental animals. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 496–499, May, 1998