Stimulation induced recurrent epileptiform discharges block cortical and subcortical spreading depression in rats

Blockade of the spread depression [SD] in chemically or electrically stimulated areas of the cerebral cortex was analyzed in a series of experiments performed in 40 curarized, locally anaesthetised rats. Longlasting stimulation of the cerebral cortex (0.5 to 1.7 mA, 6 Hz, 0.1 ms) elicited recurrent episodes of enhanced evoked potentials propagating to remote cortical areas [Co], the caudate nucleus [Cd], the hippocampus [Hi] and the thalamus [Th] and was accompanied by marked slow potential shifts (4-6 mV amplitude, 2-3 min duration, at 2-5 min intervals]. The projected discharge interfered with SD initiation and propagation in all the examined structures. The SD blockade was most pronounced during the episodes and almost absent in the intervals between them. The block was manifested by reduced amplitude and duration of the slow potential of SD. Pentobarbital [20 mg/kg] suppressed the recurrent discharges and eliminated the corresponding SD blockade. Recurrent excitability changes induced by Cd and Th stimulation elicited similar effects but the threshold was higher in Cd and Th than in Co. SD was less effectively blocked by the projected discharge than by stimulation of the same structure, particularly in the vicinity of the recording electrodes, where the blockade could be observed even under pentobarbital. The SD blockade outlasted stimulation by a considerably longer period of time in Th (about 10 min) than in the Cd (about 3 min). The onset of stimulation and the projected episodes sometimes elicited SD waves but SD blockade prevailed with continued stimulation. The present findings support the hypothesis that excessive neural activity increases the potassium clearance and thus prevents the autoregenerative accumulation of potassium ions, mediating SD propagation.     

FMN-reductase from Escherichia coli and its effect on the activity of luciferase from marine bacterium Vibrio fischeri]

Interactions of luciferases isolated from Vibrio fischeri 6 and Escherichia coli JM109(pF3) (bearing cloned V. fischeri luxAB genes) with FMN reductase isolated from E. coli JM109 were studied. FMN reductase formed a stable complex with luciferase, suggesting similar properties of the FMN reductases in the taxonomically close families Vibrionaceae and Enterobacteriaceae.     

Effect of T-activin on the production of immune interferon

A study was made of the effect of T-activin on the biosynthesis of immune gamma-interferon. It was shown that in 27% of patients with chronic nonspecific pulmonary diseases, production of gamma-interferon by lymphocytes was substantially reduced during exacerbation of inflammatory process in the lungs. It was discovered that T-activin was not an interferon inductor but enhanced its synthesis in patients with a low capacity of producing immune interferon even at small doses of interferon inductor. The preparation does not produce any effect on this process in normal subjects and in patients showing the normal level of gamma-interferon. Thus T-activin can be used for stimulation of interferonogenesis.     

The structure, growth and formation of bones in toxic exposure of the body to pesticides and antioxidant therapy]

In the experiment performed on 175 white male rats by means of a complex of morphological, biochemical and biomechanical methods peculiarities of structure, growth, outline formation and mineralization of the skeletal bones have been investigated under a toxic lesion of the organism with pesticides (chlorophose and keltan) and at a simultaneous administration of antioxidants of various groups (tocopherol, ionol, sodium selenit). Osteotoxic effect of the pesticides, manifested as an inhibition of bone growth, as a disbalance of mineral saturation and their composition, as a decrease in indices of firmness is leveled by means of therapeutic doses of the antioxidants. The stabilizing effect of the antioxidant applied correlates to the manifestation of the pesticides osteotoxic effect, to the ability of their cumulation in the organism and is directly connected with the supposed mechanism of damaging effect to the organism and/or cell. The expressiveness of the toxic effect of the chemical poison, in its turn, is defined not only by the dose, mechanism and duration of the effect, but by age peculiarities of the organism and by functional state of its reactivity. When the poisons are applied for a long time, in order to level their osteotoxic effect, a multiple increase of therapeutic doses of the antioxidants and a combined potentiation of their effect are necessary.