Non-obvious Problems in Clark Electrode Application at Elevated Temperature and Ways of Their Elimination.

Well-known cause of frequent failures of closed oxygen sensors is the appearance of gas bubbles in the electrolyte. The problem is traditionally associated with insufficient sealing of the sensor that is not always true. Study of a typical temperature regime of measurement system based on Clark sensor showed that spontaneous release of the gas phase is a natural effect caused by periodic warming of the sensor to a temperature of the test liquid. The warming of the sensor together with the incubation medium causes oversaturation of electrolyte by dissolved gases and the allocation of gas bubbles. The lower rate of sensor heating in comparison with the medium reduces but does not eliminate the manifestation of this effect. It is experimentally established, that with each cycle of heating of measuring system up to 37°C followed by cooling the volume of gas phase in the electrolyte (KCl; 60 g/L; 400 µ L) increased by 0.6 µ L approximately. Thus, during just several cycles it can dramatically degrade the characteristics of the sensor. A method was developed in which the oxygen sensor is heated in contact with the liquid, (depleted of dissolved gases), allowing complete exclusion of the above-mentioned effect.

[Molecular epidemiology of HIV-infection in drug addicts of Southern Ural]. / Molekuliarno-epidemiologicheskaia kharakteristika ochagov VICH-infektsii sredi narkomanov na Iuzhnom Urale.

The analysis of HIV-1 variants circulating among drug addicts in 16 settlements of the Sverdlov, Chelyabinsk and Orenburg regions (72, 90 and 42 patients respectively) was carried out. As shown by the serological analysis, the spread of HIV-1 variant IDU-A among the drug addicts in this area continued in this area and could be detected in 99.5% of the samples (203 out of 204 samples). These data were confirmed by the results of the analysis of 35 samples by the Heteroduplex Mobility Assay for genes env and gag. The analysis of nucleotide sequences of gene env revealed that HIV-1 variants in the Southern Urals, where the greatest outbreak of HIV infection in Russia had been registered, were genetically related to viruses of subtype A, detected earlier in this group of risk in other regions of Russia, as well as in Ukraine, Belarus and other East European countries.

[Variants of the pathogenetic therapy of myasthenia gravis]. / Varianty patogeneticheskoi terapii miastenii.

On the basis of neurological and electrophysiological examination of 43 patients with myasthenia as well as scintigraphy of the thymus in them, the authors consider variants of differentiated, pathogenetic, and correcting therapy of this disease.

[Dynamics of the bioelectrical activity of the brain in patients with intrasellar pituitary adenomas irradiated with a proton beam]. / Dinamika bioélektricheskoi aktivnosti golovnogo mozga u bol'nykh s éndoselliarnymi adenomami gipofiza, obluchennykh protonnym puchkom.

Sixty patients with pituitary endosellar adenomas irradiated with the proton beam were examined using EEG prior to and following irradiation in the period ranging from 14 days to 3 years. Fourteen days to three months after the proton irradiation, intensified irritation of the diencephalic structures was recorded. Later on, gradual normalization of bioelectrical activity was observed. Local changes in the temporal lobes, probably associated with the tissue response to irradiation by the proton beam were noted only in 8 out of the 60 patients.