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     

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     

Effects of sex hormones and antihormones on the activity of redox system enzymes of human erythrocyte glutathione

Effects of estradiol and testosterone and of the antiandrogens cyproterone acetate, niftolide, and antiestrogen tamoxifen on the activities of human erythrocyte glutathione peroxidase and glutathione reductase were studiedin vitro. In contrast to hormone preperations, antihormones in high concentrations (10⁻⁴−5×10⁻⁴ M) modified the enzyme activities. Cyproterone acetate and tamoxifen increased the activity of glutathione reductase, while tamoxifen stimulated glutathione reductase and inhibited glutathione peroxidase. Niftolide inhibited both enzymes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 8, pp. 185–187, August, 1997     

TNF controls the infiltration of dendritic cells into the site of <Emphasis Type="Italic">Leishmania major</Emphasis> infection

TNF-negative C57BL/6 (B6.TNF^−/−) mice are highly susceptible to Leishmania (L.) major infection and succumb rapidly to fatal leishmaniasis. A T helper type 1 (Th1) cell-mediated immune response is central for protective anti-leishmanial immunity. Therefore, the observed susceptibility of B6.TNF^−/− mice to L. major parasites could be caused by a deficiency in mounting a Th1 response. Analysis of infected footpads revealed, that B6.TNF^−/− mice exhibited a substantially diminished formation of DCs at the site of infection. Furthermore, Th1 cytokines such as IFN-γ were reduced in footpads of infected B6.TNF^−/− mice. Cutaneous reconstitution of B6.TNF^−/− mice with either bone marrow derived DCs (BM-DCs) or recombinant TNF simultaneous to infection resulted in an increased expression of cytokines such as IFN-γ and in an enhanced presence of Leishmania-antigen in skin draining lymph nodes. In addition, the individual time of survival was doubled. In conclusion we demonstrate that the expression of dermal TNF is necessary to provide an environment that initiates a local inflammatory response, but is not sufficient to induce protective immunity.     

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     

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     

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     

Non-invasive imaging of optical parameters of biological tissues

The normalised back-scattered intensity (NBI) profiles at various locations on the forearms of ten human subjects were obtained by moving the multi-probe of a laser reflectometer. The statistical analysis of the NBI data showed that the variation in the NBI was significantly higher at the ulnar region compared with that at other regions. For determination of the scattering (μ _s ) and absorption (μ _a ) coefficients and the anisotropy parameter g at each location on the forearm, these profiles were matched with the NBI profiles simulated by a Monte Carlo procedure (χ _0.99 ² ). For the reconstruction of images of variation of these parameters, the averaged values ofμ _a ,μ _s and g at all locations on the forearms of the subjects were determined. The absorption coefficient had a minimum (1.92 cm⁻¹) and maximum (2.21 cm⁻¹) at the wrist and the lateral region of the forearm, respectively. The scattering coefficient had a maximum (194 cm⁻¹) at the medial side and near the elbow, and a minimum (186 cm⁻¹) at the lateral side of the forearm. Similar changes in the anisotropy parameter were also observed. By interpolation of the data of each parameter on a 100×100 image matrix and after median filtering, colour-coded images of the variation in the optical parameters were constructed. These images could be useful for diagnostic and therapeutic applications of lasers.     

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     

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     

Estimation of transmembrane potential of thymic lymphocytes during dexamethasone-induced apoptosis

The use of potential-sensitive fluorescent probes allowed us to estimate transmembrane potentials of the plasma (Δφ_p) and mitochondrial (Δφ_m) membranes of rat thymocytes, which were −58±3 mV and −169±7 mV, respectively. Dexamethasone-induced apoptosis led to a significant decrease in Δφ_p (by 55%) and Δφ_m (by 17%). This effects of dexamethasone was dose- and time-dependent. Changes in Δφ_m were greater and preceded those in Δφ_p. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 1, pp. 117–120, January, 1999     

Pharmacogenetic determinants of variability in lipid-lowering response to pravastatin therapy

Pravastatin is mainly taken up from the circulation into the liver via organic anion-transporting polypeptide 1B1 (SLCO1B1 gene product). We examined the contribution of genetic variants in the SLCO1B1 gene and other candidate genes to the variability of pravastatin efficacy in 33 hypercholesterolemic patients. In the initial phase of pravastatin treatment (8 weeks), heterozygous carriers of the SLCO1B1*15 allele had poor low-density lipoprotein cholesterol (LDL-C) reduction relative to non-carriers (percent reduction: −14.1 vs −28.9%); however, the genotype-dependent difference in the cholesterol-lowering effect disappeared after 1 year of treatment. Cholesterol 7α-hydroxylase (CYP7A1) and apolipoprotein E (APOE) are known to contribute to lipid metabolism. Homozygous carriers of the CYP7A1 -204C allele or heterozygotes for both CYP7A1 -204C and APOE ε4 alleles showed significantly poorer LDL-C reduction compared to that in other genotypic groups after 1 year of treatment (−24.3 vs −33.1%). These results suggest that the SLCO1B1*15 allele is associated with a slow response to pravastatin therapy, and the combined genotyping of CYP7A1 and APOE genes is a useful index of the lipid-lowering effect of pravastatin.     

Effect of sarcolemmal anion transport system blockers on the development of ischemia-induced myocardial edema and recovery of contractile function during reperfusion

Subtotal 30-min ischemia leads to myoglobin release and increases water content in the heart. Reperfusion partially restores the developed pressure. Addition of furosemide (a Na⁺, K⁺, 2Cl⁻-sumport blocker) or NMA (inhibitor of Na⁺/H⁺-exchange) to perfusate decreases myocardial water content, reduces myoglobin loss, and completely restores myocardial contractile function. The low-rate perfusion of isolated heart and its reperfusion with solutions containing DIOA (inhibitor of K⁺, Cl⁻-co-transport) or IAA-94 (Cl⁻ channel blocker) increases water accumulation and myoglobin release from the myocardium, and deteriorated its contractile function during reperfusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 4, pp. 400–403, April, 1999     

Effect of polymerization on thermodynamic parameters of melting and stabilization of F-actin structure in normal and dystrophic canine myocardium

Differential scanning microcalorimetry was used to determine changes in enthalpy, entropy, and free energy of melting of purified myocardial fibrillar (F) actin from normal dogs and dogs with 2–3-month L-thyroxin-induced and athyreotic cardiomyopathy. Polymerization of globular (G) actin stabilizes protomer structure in both pathologies. However, the conformational changes in actin monomer caused by L-thyroxin-induced and, especially, by athyreotic cardiomyopathy decrease the free energy of the bonds between protomers in the synthesized F-actin. Binding energy between actin protomers modified in athyreotic cardiomyopathy (−12 kJ/mol) is 4 times below the control value (−48.7 kJ/mol), while in L-thyroxin-induced cardiomyopathy it little differs from the normal value (−40.8 kJ/mol). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 8, pp. 182–185, August, 1999     

Effect of picrotoxin and bicuculline on desensitization of the GABA receptor/Cl− ionophore complex

A study is performed of the effect of the convulsants picrotoxin and bicuculline, blockers of GABA-dependent Cl⁻-conductivity, on the rate of desensitization of muscimol-induced³⁶Cl⁻ entry into synaptoneurosomes isolated from rat cortex. Both picrotoxin and bicuculline, despite the difference in the mechanisms of inhibition of the GABA receptor/Cl⁻ ionophore complex, markedly reduce the rate of desensitization. However, the initial moment of the action of both convulsants is characterized by inhibition of Cl⁻ transport alone, without a drop of the rate of desensitization. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 8, pp. 160–163, August, 1994     

Effects of ambient and dietary cadmium on haematological parametres in Oreochromis mossambicus acclimatised to low- and high-calcium water

The haematological response to ambient (10μg Cd l⁻¹) or dietary (10μg Cd fish⁻¹ day⁻¹) cadmium for 2 and 14days was investigated in tilapia (Oreochromis mossambicus) acclimatised to low-calcium (0.2mM Ca²⁺) and high-calcium water (0.8mMCa²⁺). Significant reduction of erythrocytes (red blood cells), haemoglobin (Hb), packed cell volume (PCV), mean cell haemoglobin (MCH) and mean cell volume (MCV) occurred in fish exposed to ambient cadmium in low-calcium water. The anaemic response of significantly reduced Hb, PCV, MCH and MCV was also evident in fish exposed to dietary cadmium in low-calcium water. Except for increased mean cell volume of erythrocytes, both ambient and dietary cadmium had no effect on haematological indices in fish from high-calcium water. This study indicates that high-calcium water has a protective effect on cadmium toxicity.     

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     

Pharmacological analysis of the activity of phenazepam and flunitrazepam administered in superlow doses

Benzodiazepine tranquilizers, phenazepam and flunitrazepam, administered to random-bred albino male rats in superlow doses (10⁻⁹–10⁻¹⁵ mol/kg), are shown to exert an anxiolytic effect in the conflict test. In contrast to the case with the usual doses, the above effect is not accompanied by marked myorelaxant or sedative effects. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, № 2, pp. 164–166, February, 1996     

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