Comparative study of the effect of amiridine on biological membranes

The effects of amiridine and of the comparable drugs tacrine and piracetam on synaptosomes and membranes of sarcoplasmic reticulum were studied by electron paramagnetic resonance; in addition, the effects of these drugs on the activity of Ca²⁺, Mg²⁺-dependent ATPase regulating calcium transport in neurons were investigated. In concentrations of 10⁻⁷ to 10⁻⁵ M the drugs did not affect the structure of synaptosomal membranes of rat brain. Amiridine and tacrine in a concentration of 0.1 mM reduced the rate of calcium ion transport across the sarcoplasmic reticulum membrane by inhibiting the function of Ca²⁺, Mg²⁺-dependent ATPase and induced marked changes of the structural rigidity of the protein part of the membrane. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N№ 11, pp. 503–505, November, 1995 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Polyunsaturated phosphatidylcholine micelle-induced decrease of atherogenicity of the serumin vitro

It is shown that polyunsaturated phosphatidylcholine administered in micelles stabilized by a plant-derived glycoside prevents the accumulation of cholesterol by cells incubated in atherogenic serum and, moreover, in certain cases causes a 1.4–1.5-fold drop of intracellular cholesterol as compared to control cells. The optimum antiatherogenic effect was achieved when using a micelle concentration of 100–200 μg/ml and an incubation time of at least 4 hours. The antiatherogenic effect was analogous to the effect of high density serum lipoproteins. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5 pp. 497–501, May, 1995 Presented by Yu. M. Lopukhin, Member of the Russian Academy of Medical Sciences     

Chemiluminescence study of the contents of the products of Cu2+-induced lipid peroxidation in different fractions of human blood lipoproteins

It is demonstrated that the content of the primary products of lipid peroxidation reaches the maximum after about 1-h incubation with Cu²⁺ and then declines. At a Cu²⁺ concentration of about 10–15 μM, the content of lipid peroxidation products is maximal; it does not rise with a further increase in the Cu²⁺ concentration. Comparison of the kinetics of lipid peroxidation in different lipoprotein fractions shows that low density lipoproteins are much more strongly oxidized than high density lipoproteins. A strong positive correlation between the amplitude of the chemiluminescence burst and the diene conjugate content is established in 79 independent measurements. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, pp. 144–148, February, 1995     

Impact of plasmin and its complexes with α2-macroglobulin or α2-antiplasmin on the proliferative activity of human lymphocyteson the proliferative activity of human lymphocytes

It is shown that plasmin in doses of 0.1, 1, or 10 μg/ml did not influence significantly phytohemagglutinin-induced proliferation of mononuclear lymphocytes in a 3-day culture with these cells. Their proliferative response to pokeweed mitogen was stimulated by plasmin in the dose of 10 μg/ml only. Biogenic complexes of plasmin with α₂-macroglobulin or α₂-antiplasmin induced a moderate reduction of spontaneous proliferation after 3 days of culture, and so did plasmin after 5 days; α₂-macroglobulin induced a dose-dependent comitogenic effect with phytohemagglutinin and pokeweed mitogen, while α₂-antiplasmin induced a dose-independent comitogenic effect with pokeweed mitogen. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 304–305, September, 1994 Presented by V. A. Trufakin, Member of the Russian Academy of Medical Sciences     

A study of the mechanism of action of befol on Ca2+ metabolism in cardiomyocytes using a FURA-2 fluorescent probe

The dynamics of the Ca-response of cardiomyocytes is studied and the efficiency of befol, verapamil, and amiodarone is compared using various experimental models of stimulation of [Ca²⁺]_i. Befol (1–5 μM) is shown to inhibit the caffeine-and strophanthin G-induced rise of [Ca²⁺]_i. Unlike verapamil and amiodarone, befol exhibits no Ca-blocking activity in modeled K-depolarization. It is concluded that the cardiotropic effect of befol is mediated through its primary action on Na⁺/Ca²⁺ exchange in cardiomyocytes, while the cardioplegic effect of verapamil and amiodarone is due to their ability to block the slow Ca²⁺ inward current. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 288–291, March, 1996     

Effect of Prooxidants on the survival of rabbits exposed toStaphylococcus aureus toxic shock exotoxin and on the chemiluminescence of their whole blood cellsin vivo

The prooxidant Adriablastin (Adriamycin) is shown to prolong the survival of Chinchilla rabbits exposed to the toxic shock exotoxin produced byStaphylococcus aureus as well as to exert a marked effect on the time course of both spontaneous and opsonized zymosan-stimulated chemiluminescence by whole blood cells of these animals. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 258–259, September, 1995 (Presented by Yu. A. Vladimirov, Member of the Russian Academy of Medical Sciences)     

Mechanisms of modulation of GABA-induced currents in isolated cerebellar cells by tacrine

Tacrine, when applied by the concentration clamp technique to isolated Purkinje cells from rat cerebellum, dose-dependently reduced the amplitude of GABA-activated chloride currents recorded by the patch clamp technique. Half-maximal inhibition (IC₅₀) of currents activated by 2 μM GABA was observed at a tacrine concentration of 107 μM. Tacrine produced a right shift of the dose-response curves for GABA-induced currents without affecting their peak amplitudes. It is suggested that suppression of GABA-induced currents caused by tacrine can not be attributed to its interaction with the benzodiazepine site of the GABA_A receptor. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 5, pp. 539–542, May, 1999     

Effect of human defensins on the cytoplasmic Ca2+ content in platelets

The effect of the total fraction of human defensins (HNP-1, HNP-2, and HNP-3) on the cytoplasmic Ca²⁺ content ([Ca²⁺]_i) in the platelets of healthy donors was studied. At concentrations of 0.1–40 μg/ml and an incubation time of 10 min defensins have no effect on [Ca²⁺]_i in platelets labeled with Fura-2AM. However, at higher concentrations (100 μg/ml) they increased platelet [Ca²⁺]_i. In addition, defensins (40 μg/ml) inhibited the Ca²⁺ increase in platelets induced by thrombin, adenosine diphosphate, and the lipopolysaccharide ofS. typhimurium endotoxin. The most pronounced inhibitory effect was observed in a suspension of thrombin-stimulated platelets. It is shown that the effect of human defensins on the functional activity of platelets is due to the alterations in the intracellular Ca²⁺. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 600–603, December, 1994     

Inhibition of platelet aggregation by monoclonal antibodies against glycoprotein IIb–IIIa complex

Monoclonal antibodies CRC64 are obtained against Ca²⁺-dependent glycoprotein IIb–IIIa complex of the platelet membrane which possess the ability to inhibit completely fibrinogen-dependent platelet aggregation. CRC64 is directed against the epitope formed by the glycoprotein IIb–IIIa complex and does not interact with proteins isolated after platelets are treated with ethylenediamine tetraacetate. Complete, reproducible blockade of platelet aggregation caused by 5 μM adenosine diphosphate is noted in an MCA concentration of 3 μg/ml, while in the case of a stronger inductor, namely 1 U/ml thrombin, platelet aggregation is inhibited in a concentration of 5 μg/ml. F(ab′)₂ fragments are also able to inhibit platelet aggregation completely and are usually effective in concentrations lower than native monoclonal antibodies. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 402–405, October, 1994 Presented by V. N. Smirnov, Member of the Russian Academy of Medical Sciences     

Comparative analysis of neuroprotective activity of new chemical agent Vp and piracetam

The effect of new agent Vp (9-butylamine-3,3-dimethyl-3,4-dihydroacridine-1(2H) hydrochloride) on lifetime of isolated mechanoreceptive crayfish neurons was evaluated by the duration of its impulse activity. Vp significantly and dose-dependently prolonged the lifetime of both spontaneously degrading neurons and neurons degrading under conditions of inhibition of various stages of the energy metabolism: glycolysis and oxidative phosphorylation. The effect of Vp in a concentration of 10⁻⁷ M surpassed that of amiridine. Piracetam also prolonged the lifetime of spontaneously degrading neurons, but only in very high concentration (10⁻² M). It is concluded that Vp possesses a neuroprotective activity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 4, pp. 430–433, April, 2000     

Effect of chlorophos (dipterex,trichlorphon) on high-threshold potassium and calcium channels of the neuronal membrane

The effect of chlorophos (dipterex, trichlorphon) on high-threshold potassium and calcium currents is studied on isolated snail neurons using the patch-clamp technique. Chlorophos (10–1000 μmol/liter) is found to reversibly lower the peak amplitude of a high-threshold potassium current by 30% on average and exerts two independent effects on a high-threshold calcium current: reversible lowering of the peak amplitude by 35% on average and, in 30% of cases, reversible inhibition of its activation, inactivation, and deactivation. this effect is abolished by adding diltiazem (a calcium channel antagonist) in a concentration of 100 μmol/liter to the medium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 59–62, January, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Effects of muscarine agonists and antagonists on vasopressin-stimulated water transport in the amphibian bladder

The effects of M₁ and M₂ cholinoceptors on stimulated water transport in the urinary bladder of the common frogRana temporaria L. are described. In the presence of pirenzepine, a selective M₁ cholinoceptor antagonist, carbachol stimulated water transport. Activation of M₂ cholinoceptors by oxotremorine in concentrations of 0.5–5.0 μM inhibited water transport, whereas their activation by this compound in higher concentrations (10–100 μM) stimulated it. The use of the phospholipase C inhibitor neomycin (0.5 mM) and the calmodulin inhibitor W-7 (1 mM) indicated that activation of M₂ cholinoceptors switches on phospholipid-Ca²⁺-calmodulin-dependent mechanisms. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 252–254, September, 1995 (Presented by P. V. Sergeev, Member of the Russian Academy of Medical Sciences)     

Effect of amiridine and tacrine on reuptake of neurotransmitters in experimental amnesia

It is demonstrated that a single administration of amiridine, tacrine, piracetam, and physostigmine has no effect on the reuptake of adrenalin, noradrenalin, dopamine, and glycine, or of γ-aminobutyric, glutamic, and aspartic acids. Scopolamine (single administration or a 20-day treatment) also has no effect on the reuptake of these neurotransmitters. Administration of amiridine to intact rats during a 20-day period leads to a decrease in the reuptake of dopamine and γ-aminobutyric acid. A course of amiridine therapy of rats after repeated administration of scopolamine results in a reduced reuptake of dopamine. Tacrine, piracetam, and physosostigmine exhibit no activity under the chosen experimental conditions. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5, pp. 512–514, May, 1995 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Role of glycolysis in the maintenance of the energy-synthesizing function of hepatocytes from rats adapted and nonadapted to hypoxia at different oxygen concentrations

It is demonstrated that the lactate-Po₂ dependence is the same in hepatocytes of rats with high and low resistance to hypoxia and does not correlate with phasic changes in the ATP concentration in the 890–50 μM O₂ region. Strong activation of lactate formation against the background of ATP decrease indicates that glycolysis is not the major mechanism determining the steady-state ATP level in the cell and affecting the ATP-Po₂ relationship in a wide range of oxygen concentrations. The intensity of glycolysis in hepatocytes of rats with high resistance to hypoxia is markedly increased after periodic adaptation to hypoxia but remains practically unchanged in the hepatocytes of low-resistance rats. This indicates that fundamentally different compensatory mechanisms are involved in this process in the liver of high- and low-resistance rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 1, pp. 28–32, January, 1995     

Mechanisms responsible for the resistance of tracheal smooth muscle to histamine in rats

A mechanographic study of contractile responses by tracheal smooth muscle segments of rats to a histaminergic agent showed that intact segments did not respond to histamine in the concentrations used (0.01–10 μM), whereas depolarized segments responded to histamine by dose-dependent contraction which were considerably enhanced following mechanical removal of the tracheal epithelium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 263–264, September, 1995     

Effect of pulsed infrared laser radiation on DNA synthesis in tissues of intact rats and during strenuous physical exercise

The motor zone of the rat brain cortex is subjected to pulsed infrared (0.89 μ) laser radiation, which is found to stimulate DNA synthesis both in intact animals and after strenuous physical exercise (swimming). Preliminary laser irradiation exerts a stress-limiting effect on cells of the brain cortex and thymus but does not prevent swimminginduced reduction of³H-thymidine incorporation in nuclear DNA of muscles. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 625–627, June, 1995 Presented by V. M. Bogolyubov, Member of the Russian Academy of Medical Sciences     

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 catalin on radical production in aqueous solutions and cross-linking in deoxyribonucleoprotein complex

The effect of catalin on cross-linking in the DNA-protein system is studied after illumination with visible and UV light. Catalin is shown to stimulate this process. The use of a hydroxylamine trap reveals that catalin (10–100 μM) induces the accumulation of free radicals in aqueous solutions as soon as 10 minutes after irradiation. A considerable amount of O ₂ ^- is fixed in the medium during illumination of catalin aqueous solution. Superoxide dismutase added to the incubation medium considerably reduced the number of recorded radicals. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 8, pp. 142–144, August, 1994 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Circulating serum interferon andits effect on the activity of human natural killer cells

The interferon content in the plasma of 6 healthy donors and 10 patients with multiple sclerosis and the effect of an 1-h treatment of mononuclear cells with autologous plasma on their natural killer activity are studiedin vitro using³H-uridine-labeled (3 μCi/ml) human erythromyeloleukosis cells K-562. The serum interferon content in healthy donors is 2.3±0.82 IU/ml, whereas that in patients is higher: 5.2±0.8 IU/ml. Autologous plasma does not affect the activity of natural killer cellsin vitro, whereas it increases the cytotoxicity of mononuclear cells obtained from patients with multiple sclerosis by 35–64%. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 619–622, December, 1994 Presented by S. V. Prozorovskii, Member of the Russian Academy of Medical Sciences     

Effect of thymoptin on the behavior of experimental animals

A study is made of the effect of thymoptin, a preparation containing a complex of acid peptides from the thymus, on the behavior of experimental animals. It is found that in a dose of 400 μg/kg the preparation enhances motor activity, raises the body temperature, augments pain sensitivity, stimulates behavior in the open field test, and facilitates learning and memory processes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121 N ^o 3, pp. 285–287, March, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences