Effect of somatostatin on presynaptic and postsynaptic glutamate receptors and postsynaptic GABA receptors in the neurons of rat brain.

We studied the effect of somatostatin on presinaptic NMDA receptors and postsinaptic GABA, NMDA, and AMPA receptors in rat brain. It was shown that somatostatin inhibits NMDA-induced (45)Ca(2+) uptake into synaptosomes isolated from rat brain cortex (IC50=2.8×10(-11) M). Somatostatin potentiates AMPA receptors and inhibits hippocampal NMDA receptors in the entire range of examined concentrations (10(-14)-10(-7) M); it also potentiates or inhibits GABA receptor currents in a concentration-dependent manner. Our results suggest that somatostatin modulates the function of ionotropic glutamate and GABA receptors and is involved in cognitive and neurodegenerative processes in the mammalian brain.

[Study of the neuroprotective action of hybrid structures based on fullerene C60].

The neuroprotective action of hybrid structures based on fullerene C60 with attached proline amino acid has been studied. Hybrid structures contained natural antioxidant carnosine or addends with one or two nitrate groups. It has been shown that all studied compounds had antioxidant activity and decreased the concentration of malondialdehyde in homogenates of the rat brain. Compound 1, which contained the antioxidant carnosine, has been found to be the most effective antioxidant. All compounds except IV and V inhibited the activity of monoamine oxidase B, while compounds I-IV increased the activity of monoamine oxidase A. All investigated compounds inhibited glutamate-induced Ca2+ uptake into synaptosomes of the rat brain cortex. Compound III, containing two nitrate groups, has been found to be the most effective inhibitor. This compound caused a significant increase of the currents of AMPA receptors (AMPA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid).

Effect of corticotropin-like intermediate lobe peptide on presynaptic and postsynaptic glutamate receptors and postsynaptic GABA receptors in rat brain.

We studied the effect of corticotropin-like intermediate lobe peptide (CLIP) on presynaptic NMDA receptors and postsynaptic GABA, NMDA, and AMPA receptors in rat brain. CLIP inhibited presynaptic and postsynaptic NMDA receptors, but potentiated postsynaptic GABA and AMPA receptors. Our results indicate that CLIP modulates function of ionotropic receptors for glutamate and GABA.

Effect of uridine of presynaptic NMDA and kainate receptor of rat brain cortex.

It was demonstrated that uridine affects presynaptic NMDA and kainite receptors of rat brain cortex. Uridine considerably inhibited (45)Ca2+ uptake into synaptoneurosomes (IC50 = 7.1 x 10(-12) M) under conditions NMDA stimulation and increased it under conditions AMPA stimulation (157.8%).

Effect of muramyl dipeptides on postsynaptic GABA, NMDA, and AMPA receptors and presynaptic NMDA receptors in rat brain.

We studied the effect of muramyl dipeptides on postsynaptic GABA, NMDA, and AMPA receptors and presynaptic NMDA receptors. L,D-Dipeptide more potently than L,L-dipeptide inhibited postsynaptic NMDA receptors, potentiated GABA and AMPA receptors, and inhibited (45)Ca(2+) uptake in synaptosomes from of rat brain cortex. Our results indicate that muramyl dipeptides modulate function of glutamate and GABA receptors.

Effect of prostaglandins E2 and D2 on presynaptic NMDA receptors in rat cerebral cortex.

We studied the effect of prostaglandins on presynaptic NMDA receptors. Prostaglandin E2 inhibited NMDA-induced (45)Ca2+ uptake by synaptosomes in low concentrations (IC50 approximately 10 microM), but potentiated it in higher concentrations. Prostaglandin D2 increased (45)Ca2+ uptake by synaptosomes during stimulation of NMDA receptors. Our results indicate that prostaglandins D2 and E2 modulate function of presynaptic NMDA receptors.

Specificity of glutamate receptors in P2 synaptosomal fraction from rat brain cortex.

Specificity of glutamate receptors in the P2 synaptosomal fraction from the cerebral cortex of newborn rats was studied by measuring (45)Ca(2+) uptake by synaptosomes in the presence of agonists of ionotropic and metabotropic glutamate receptors. It was shown that P2 synaptosomal fraction from rat cortex contains NMDA receptors, kainate receptors, and group 1 metabotropic receptors.

Effects of delta sleep-inducing peptide on pre- and postsynaptic glutamate and postsynaptic GABA receptors in neurons of the cortex, hippocampus, and cerebellum in rats.

We studied the effect of delta sleep-inducing peptide on GABA receptors of hippocampal and cerebellar neurons in rats. It was shown that delta sleep-inducing peptide considerably and dose-dependently potentiates GABA-activated currents in these neurons and blocks NMDA-activated potentiation in cortical and hippocampal neurons. The peptide modulates activity of presynaptic NMDA receptors, which is seen from changes in (45)Ca(2+) uptake into synaptosomes of the brain cortex after uptake stimulation with glutamate and NMDA.

Effect of interleukin-1beta on NMDA-induced 45Ca2+ uptake by synaptosomes of rat brain cortex.

The effect of interleukin-1beta on presynaptic NMDA receptors was evaluated by studying NMDA-induced 45Ca2+ uptake by synaptosomes from rat brain cortex. Interleukin-1beta inhibited 45Ca2+ uptake by synaptosomes. Our results indicate that interleukin-1beta modulates presynaptic NMDA receptors and is probably involved in the regulation of synaptic transmission in the central nervous system.

Comparison of mechanical energy expenditure of joint moments and muscle forces during human locomotion.

The mechanical energy expenditures (MEEs) of two human lower extremity models with different sources of mechanical energy - (1) muscles and (2) joint moments - were compared theoretically. Sources of mechanical energy producing movement of Model 1 were eight muscle, three of which were two-joint muscles. Sources of mechanical energy producing movement of Model 2 were net moments at its joints. These sources of mechanical energy were substituted by 11 one-joint muscles, with the assumption that antagonistic muscles did not produce force. Because of this assumption, summed MEE of all joint moments and all one-joint muscles of Model 2 were the same. It was shown that during the same movement the model with two-joint muscles could spend less mechanical energy than the model without two-joint muscles. This economy of mechanical energy realized by two-joint muscles was possible if (i) signs of the muscle powers which were produced by the two-joint muscle at both joints were opposite, (ii) moments produced by that muscle at each of the two joints had the same direction as the net joint moments at these joints, and (iii) muscles crossing these two joints from the opposite side did not produce force. Realization of these three conditions during human locomotion was checked experimentally. Electrical activity of eight lower extremity muscles of ten subjects was measured during treadmill walking and running. Based on this information, the periods where the muscles produce force were estimated. Moments and their power at joints of the lower extremity of two subjects performing walking and running were calculated using kinematics and ground reaction force measurements, and an inverse dynamics approach. It was shown that MEE of models with different sources of mechanical energy appeared to be different during certain periods of the swing phase. However, the magnitude of this difference was probably relatively small.

["Tendon" action of two-joint muscles during human locomotion: transfer of mechanical energy between links in shock-absorbing and push-off phases]. / "Sukhozhil'noe" deistvie dvusustavnykh myshts pri lokomotsiiakh cheloveka: peredacha mekhanicheskoi énergii mezhdu zven'iami v fazakh amortizatsii i ottalkivaniia.

We hale evaluated experimentally the amounts of the mechanical energy transferred by the two-joint muscles between the links of legs during squat vertical jumps and landings after jumping down from a height of 0.5. The experiments have been conducted on file healthy subjects in the course of locomotions. The coordinates of markers attached to the subjects' bodies and the ground reaction forces have been registered. The energy transferred by the two-joint muscles from and to the links forming each joint has been determined by integration of the difference between the power developed in the joint by the control moment and the total power of the muscles serving the given joint. It has been shown, that at squat vertical jump (the push-off phase) the two-joint muscles transfer mechanical energy from the proximal links of the leg to the distal ones: from pelvis to shank (by the rectus femoris m.), and from thigh to foot (by the gastrocnemius m.). At landing (the shock-absorbing phase) the two-joint muscles transfer energy from the distal to proximal links: from foot to thigh (by the gastrocnemius m.), and from shank to pelvis (by the rectus femoris m.). Thus the one-joint muscles of the proximal links compensate for the deficiency in the force developed by the one-joint muscles of the distal links due to the "tendon action" of the two-joint muscles. During push-off, the muscles of the proximal links contribute to increase in the energy of the distal links, and in the shock-absorbing phase, to its dissipation.

[Mechanical energy expenditure on human movement and the anthropomorphic mechanism]. / Mekhanicheskie énergozatraty na dvizhenie cheloveka i antropomorfnogo mekhanizma.

Mechanical energy expenditures of the man and anthropomorphic locomotion machine during movement are compared theoretically. Sources of the mechanical energy affecting movement of human's lower extremity are modelled by 8 muscles, 3 of which are the two-joint muscles. The model of the lower extremity of anthropomorphic locomotion machine is moved by joint moments. It was shown that in the same movement the model of the human lower extremity can spend less mechanical energy than that of the model of the anthropomorphic locomotion machine. It is caused by the presence of two-joint muscles in the first model. Such an economy of mechanical energy expenditures realized by the two-joint muscle is possible at simultaneous execution of three conditions: 1) signs of the muscle powers, which are produced by that muscle at both joints, are opposite; 2) moments produced by that muscle at each of both joints have the same direction with the joint moments at these joints; 3) one-joint antagonistic muscles are not active. An expression which makes it possible to estimate the mechanical energy savings by the two-joint muscles during humans' movement was developed.

[Clinical and biochemical parameters of parkinsonism induced by 1-methyl-4-phenyl-1,2,2,6-tetrahydropyridine and its methyl-phenyl and methoxy-phenyl derivatives in C57Bl/6 mice]. / Klinicheskie i biokhimicheskie pokazateli parkinsonizma, vyzvannogo 1-metil-4-fenil-1,2,3,6-tetragidropiridinom i ego metil-fenil- i metoksi-fenil-proizvodnymi u myshei C57Bl/6.

Possibility of ortho-, para-, meta-methylphenyl and methoxyphenyl-derivates of MPTP to produce parkinsonism was investigated. Only ortho-methylphenyl- and ortho-methoxyphenyl-derivates of MPTP cause a persistent loss in dopamine content in the brain and produced the clinical symptoms of parkinsonism. All substances produced Parkinsonian-like syndrome gives the symptoms of activation of nervous system during 0.5-1 h after injection and symptoms of depression in following 3 h of observations.

[Sanitaro-microbiologic aspects of the concurrent residence of man and animals in hermetic quarters]. / Sanitarno-mikrobiologicheskie aspekty sovmestnogo prebyvanie liudei i zhivotnykh v germetichnom pomeshchenii.

Men and animals (dogs) shared an enclosed environment for 30 days. The microorganisms on their skin and in the air were examined. Specific attention was given to staphylococcal pathogens that are potential causal agents of infectious diseases in enclosed bio-objects. The data obtained suggest that conditional pathogens can be exchanged between men and animals sharing an environment and clarify the mechanism(s) of their transfer. The experimental results have been used to develop prophylactic measures against diseases caused by conditional pathogens among men and animals sharing an enclosed environment.

[Effect of prethrombin I and prostaglandin E2 on thrombin-stimulated aggregation of rat platelets]. / Vliianie pretrombina I i prostaglandina E2 na stimuliruemuiu trombinom agregatsiiu trombotsitov krys.

Effect of inactive precursor of alpha-thrombin--prethrombin (Pre-I) and prostaglandin (PGE2) on aggregation of washed rat platelets induced by alpha-thrombin was studied. Pre-I inhibited dose-dependently the alpha-thrombin-induced platelet aggregation. K1 values for Pre-I of high and low affinity binding sites were equal to 0.9.10(-8) M and 0.56.10(-6) M, respectively. PGE2 inhibited the alpha-thrombin-induced aggregation after simultaneous addition and within 5 and 15 min of incubation with PGE2. Preincubation of platelets with alpha-thrombin within 15 min prevented the PGE2-induced aggregation but preincubation of platelets with Pre-I within 15 min did not influence the platelet aggregation, induced by PGE2.