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A comprehensive study of the functioning of antioxidant system in rats with rotenone-induced parkinsonism was conducted. The development of pathology led to inhibition of the majority of the studied antioxidant enzymes in the brain and blood serum of animals, which can be associated with decompensation of oxidative stress under conditions of prolonged mitochondrial dysfunction. These changes apparently make an important contribution into neuronal degeneration in the cerebral cortex and striatum and motor disorders in experimental animals.

An experimental and theoretical study of electrical conductive properties of the vestibular labyrinth tissues is carried out. Using the theory of dynamic systems and experimental data on the measurements of amplitudes of electrical signal at the end of the vestibular nerve, the transfer function of the vestibular labyrinth is calculated and its frequency dependence is investigated. It is shown that the transfer function tends to its asymptotic value with increasing frequency. It is found that the transfer function of the vestibular labyrinth for stimulating impulses emanating from the electrode located in the posterior semicircular canal is significantly less than that for stimulating impulses from electrodes located in the superior and horizontal semicircular canals.

A theoretical and experimental study was performed of a frequency dependence of the amplitude-phase characteristics of the vestibular nerve stimulation signal and its changes during passage from the stimulating electrodes to the end of the vestibular nerve. To assess the influence of leakage currents on the change in the stimulating current pulse, a physico-mathematical model of the vestibular organ and electrical processes occurring in its tissues was developed on the basis of experimental data on electrophysical and anatomical characteristics of the vestibular labyrinth tissues by the example of a guinea pig. The calculations and measurements of the frequency dependence of the amplitude-phase characteristics of the stimulating signal at a recording electrode located in the Scarp’s ganglion are performed. It is established that the influence of leakage currents on the signal amplitude at the recording electrode is significant in the entire frequency range considered. Compensation of the influence of leakage currents will improve the stimulating signal quality and increase the transfer function of the vestibular implant.

Effects of Ca2+ ions on the intensity of lipid peroxidation, activities of guaiacol peroxidase, superoxide dismutase (SOD), and catalase, as well as on heat resistance of winter wheat (Triticum aestivium L.) coleoptiles were examined. A preliminary incubation of coleoptile segments in a 5 mM CaCl2 solution was shown to improve their survival rates after an injuring heat treatment (43.5°C). The effect of Ca2+ was suppressed by the inhibitor of Ca2+ channels (1 mM LaCl3). An incubation of coleoptiles in the presence of 5 mM CaCl2 prior to the stress treatment elevated the content of lipid peroxidation product, malondialdehyde (MDA) and stimulated the activities of guaiacol peroxidase, SOD, and catalase. After the heat exposure of untreated and Ca2+-treated seedlings, differential changes in MDA content and in activities of guaiacol peroxidase, SOD, and catalase were observed. It is concluded that a short-term oxidative stress arising in Ca2+-enriched plant tissues after the heat treatment is unrelated to their irreversible damage.

The effect is studied of different inorganic phosphorus concentrations on changes in growth rates of 7 diatom species isolated from the plankton of the Black Sea. All species examined increase their cell-division rate with increasing phosphorus concentration in the medium. The phosphorus concentrations have been determined above which division rate is not limited by phosphorus content in the medium. The non-limiting concentration amounts to V/V m =0.9. In the species studied, non-limiting concentrations ranged from 1 to 30 μg P/1. The highest values were obtained for relatively large-sized species. The ratio of cell surface to volume tended to be inversely related to the growth-rate-limiting concentration. Minimal values of phosphorus content in cells have been calculated to range from 0.6 to 4.0·10−17 g.at−P/μ−3. Based on a comparison of phosphate levels in the Black Sea with experimentally-derived rate-limiting concentrations, it is concluded that phosphorus does not limit the reproduction rate of phytoplankton in the more productive regions of the Black Sea or in the lower strata of the euphotic zone.