Oxaloacetate keto-enol tautomerase from bovine heart mitochondrial matrix

Bovine heart mitochondrial matrix contains two proteins possessing the oxaloacetate keto-enol tautomerase (EC 5.3.2.2) activity. A procedure for the isolation and purification of the enzymes to an electrophoretically homogeneous state has been developed. The purified proteins have molecular masses of 37 kD and 80 kD and catalyze the keto-enol oxaloacetate tautomerization reaction with the turnover numbers of approximately 3000 and approximately 2000 min-1. The both enzymes were found to differ significantly in all their physicochemical and kinetic properties. Fractionation of rat liver mitochondria revealed that the oxaloacetate keto-enol tautomerase activity is predominantly localized in the mitochondrial matrix. The essential role of oxaloacetate keto-enol tautomerase in the operation of the Krebs cycle is discussed.     

The effect of amiridin on the MPTP-induced Parkinson-like syndrome in monkeys]

Development of behavioral disturbances was investigated during N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration (0,2 mg/kg, i/m, at 48 h. intervals, total dose 11.2-13.2 mg/kg) in experiments on two monkeys Macaca rhesus. MPTP induced the complex of symptoms, which are typical for idiopathic Parkinson's disease. Administration of amiridine (0,25-0,4 mg/kg) to MPTP-treated monkeys caused gradual decline of Parkinson syndrome. Mechanisms of action of amiridine are discussed.     

Effect of tranquilizing agents on the blood level of endogenous ethanol in alcoholics

Experiments on alcohol addicts blood were made to study the time course of the endogenous ethanol level after a single administration of mebicar (1.5 g), a derivative of bicyclic bisuria, 50 ml of 5% sodium hydroxybutyric syrup, a derivative of gamma-hydroxybutyric acid, and 20 mg diazepam, a derivative of 1,4-benzodiazepines. The clinical effect was recorded simultaneously. It was established that different tranquilizers stimulate the increase in the endogenous ethanol level as regards the spectrum of psychotropic activity. This effect was the most pronounced with mebicar and to a less measure with diazepam.     

The effect of neurotropic substances on the self-stimulation reaction at the thalamic level]

The effect of d-amphetamine, cocaine, caffeine, morphine, imipramine, phenobarbital, LSD-25, benactyzine, meprobamate, diazepam, chloridiazepoxide on the lateral hypothalamic self-stimulation of rats was investigated. D-amphetamine, cocaine, caffeine, morphine, imipramine decreased the threshold of selfstimulation. Meprobamate, diazepam, chlordiazepoxide failed to influence this index, but increase the intensity of self-stimulation during the threshold, the optimum and more than the optimum cirrent intensity. Benactyzine, LSD-25, phenobarbital decreased the threshold and increased the frequency of self-stimulation during all the current intensities. A comparative study of the above results showed the agents of the first group to exert a direct stimulating action on the positive reinforcement system. Tranquillizers activated this system due to their depressive action on the negative reinforcement system. Benactyzine, LSD-25, phenobarbital activated the system and depressed the system of negative reinforcement.     

The activity of sphingomyelin cycle enzymes and concentration of sphingomyelin degradation products in rat liver in dynamics of acute toxic hepatitis

Activity of key enzymes of the sphingomyelin cycle and the content of its components (sphingomyelin, ceramide and sphingosine-1-phosphate) have been studied in livers of rats in dynamics of acute toxic hepatitis induced by subcutaneous administration of oil solution of CCl₄. Sphingomyelinase activity significantly increased already on early terms and remained increased over the whole period of observation. Ceramidase activity insignificantly differed from the control level. The levels of sphingomyelin and sphingosine-1-phosphate did not undergo marked changes while ceramide content significantly increased. The balance between liver content of ceramide (proapoptotic) and sphingosine-1-phosphate (the antiapoptotic factor) was shifted towards ceramide over the whole observation period. In sphingomyelin molecules there was a significant decrease in the content of the fatty acids C_18:1 and C_22:2, while in ceramide molecules and sphingosine-1-phosphate only the fatty acid C_22:2 changed. In spite of a significant decrease in the content of some unsaturated fatty acids, calculated unsaturation coefficients of the fatty acid component of the sphingomyelin cycle metabolites insignificantly differed from control. Taking into consideration literature data our results suggest involvement of ceramide-mediated apoptosis in the pathogenesis of acute toxic hepatitis. Elimination of damaged hepatocytes permits realization of repair processes and promotes optimization of cellular community in the liver.     

An experimental study of anti-amnestic activity of piracetam in orchidectomized rats]

The decrease of learning ability by 50% as assessed by passive avoidance test and the increase 28% of microviscosity of synaptosomal membranes from brain cortex were observed in rats in a month after orchidectomy as compared with that of intact or sham--operated animals. The treatment of orchidectomized rats with piracetam either by single application or in the course of 10 days applications in the daily dose of 250 mg/kg intraperitoneally failed to improve learning ability of animals in passive avoidance test and to produce a normalizing effect on the structure of membrane lipid matrix. The testosterone content in blood of orchidectomized rats was 10 times lower as compared with control and was not affected by treatment with piracetam.     

Uptake of adrenaline by rat brain synaptosomes. Effects of several psychotropic drugs]

Comparative study of the uptake of 3H-epinephrine (3H-EN) and 3H-norepinephrine (3H-NE) into rat brain crude synaptosomes and effect of psychotropic drugs of different classes on this process showed that isolated nerve terminals had their own transport system for EN. The crude synaptosomal fraction had two transport system's for EN; high-specific active uptake with high affinity (KM = 3.7 + 0.21 microM) and low-affinity uptake (KM2 = 98.0 + 47.5 microM). En accumulation was saturable, stereo-specific and inhibited by ouabain (3 X 10(-3) M), protoveratrine A and B (10(-4) M), NaN3 (2 X 10(-3) M), 2,4-dinitrophenol (2 X 10(-3) M), p-chloromercuribenzoate (10(-4) M). Actinomycin D had no effect on the uptake of 3H-EN. 3H-HE was accumulated by two uptake system: 1-high affinity uptake system with KM values of 0.49 + 0.13 microM, 2-low affinity uptake system with KM values of 21.1 + 7.71 microM. Amphetamine, mesocarb, chlorpromazine, fluphenazine and haloperidol were equally effective inhibitors of 3H-EN and 2H-HE uptake. Imipramine, phenazepam, diazepam and carbamazepine (5 X 10(-5) M) had no effect on the uptake of 3H-NE. Imipramine, zimelidine, norzimelidine and viloxazine (5 X 10(-5) M) were more potent inhibitors of the 3H-EN uptake than that of 3H-NE.     

Normalization of the adaptive avoidance reaction in rats using substances with nootropic activity

The system of double coaxial cylinders filled with water was used as a device for studying simple extrapolation behaviour of rats. The amount of rats which were able to dive under the lower edge of the inner cylinder, without reaching the bottom of the outer cylinder and the latency of this avoidance reaction were considered as a measure of extrapolation ability. This reaction was altered by the pretreatment of animals with cycloheximide, a protein synthesis inhibitor. Piracetam as a standard nootropic, sodium and lithium hydroxybutyrate as substances with a potential nootropic effect were shown to be able to antagonize the damaging effect of cycloheximide on the avoidance performance. Benzodiazepine tranquilizer, phenazepam, in contrast to nootropics, evokes additional worsening of extrapolation reaction. Normalization of avoidance disturbed by cycloheximide, can be used as an adequate and informative approach for screening of nootropics.     

Immunomodulating peptides, regulation of interleukin-2 expression and its possible mechanism]

The influence of some immunomodulation peptides SKD, R and L on the interleukin-2 (IL-2) synthesis in T-lymphocytes and possibility of their specific interaction with nucleotide sequences of IL-2 gene were studied. It was firstly shown that peptides R and L specifically interacted with regulatory nucleotide sequences of IL-2 gene and, possibly, play a key role in the immunomodulation actions on the IL-2 production.