Initial data on biological activity of taiga–steppe soils in the lower reaches of the Kolyma River

Microbiological and enzyme activities of extrazonal taiga-steppe soils in the lower reaches of the Kolyma River have been studied for the first time. Contrary to north-taiga cryometamorphic soils, predominating in the area, microbial cenoses under herb–sedge petrophytic and grass–sagebrush–herb thermophytic steppes are characterized by features typical for arid soils. The saturation of the soil profile with microorganisms is greater, and the development of actinomycetes is more intensive. The enzyme complex is characterized by high activity of dehydrogenases.     

Inhibition of ABC-transporter(s)' function in non-small cell lung cancer cells by platinum drugs]

With an account of the literature data that platinum drugs react with many cellular targets, including ATP and proteins, the authors suggested that disturbance of the function of energy-dependent ABC-transporters (markers of multidrug resistance, MDR) under the effect of platinum drugs could be a cause of increased efficacy of MDR agents (agents, MDR to which is developed by the classical mechanism) when used in combination with platinum drugs even in the treatment of multidrug resistant lung cancer. The cisplatin and carboplatin effect on accumulation of MDR doxorubicin in cells of non-small cell cancer was studied by flow cytometry with the use of biopsy specimens. The MDR phenotype of the tumors was determined by a change in doxorubicin intracellular accumulation under the action of the ABC-transporter(s)' inhibitors: verapamil and genistein (specific inhibitors of Pgp and MRP respectively) and sodium azide (an inhibitor of all energy-dependent ABC-transporters). The MDR phenotypes, i.e. Pgp-MRP+ or Pgp+MRP+, were detected in all the tumors investigated. Two types of changes in doxorubicin intracellular accumulation under the action of the inhibitors and the platinum drugs were shown: (a) an increase in doxorubicin cytoplasmic accumulation and (b) a change in subcellular distribution of the anthracycline (increased accumulation of doxorubicin in the cell nucleus and its higher binding to DNA). Cisplatin and carboplatin had an inhibitory effect on ABC-transporter(s) in all the tumors investigated but the effect of carboplatin was less pronounced. It was concluded that cisplatin and carboplatin stimulation of doxorubicin intracellular accumulation, as well as a change in subcellular distribution of the anthracycline under the action of the platinum drugs (increased doxorubicin accumulation in the cell nucleus) in multidrug resistant lung tumors could be at least partly explained by inhibition of the MDR transporter(s)' function. The results could provide a basis for the use of the sequential combination cisplatin (or carboplatin)-->doxorubicin in the treatment of multidrug resistant lung cancer.     

Pulsed microwave discharge in a capillary filled with atmospheric-pressure gas

A pulsed microwave coaxial capillary plasma source generating a thin plasma filament along the capillary axis in an atmospheric-pressure argon flow is described. The dynamics of filament formation is studied, and the parameters of the gas and plasma in the contraction region are determined. A physical model of discharge formation and propagation is proposed. The model is based on the assumption that, under the conditions in which the electric fields is substantially below the threshold value, the discharge operates in a specific form known as a self-sustained-non-self-sustained (SNS) microwave discharge.     

The spectral characteristics of the electrical activity in the rabbit brain during the hunger dominant]

By means of daily alimentary deprivation the dominant of hunger was created in rabbits. In response to acoustic stimuli summational swallowing and chewing movements appeared. Spectral analysis of the electrical brain activity showed the presence of primary dominant focus zone (lateral and ventromedial hypothalamus), characterized by an increase of spectrum power in delta-range while in the orbito-frontal, sensorimotor, parietal cerebral cortex, in the medial and lateral preoptic hypothalamic zones the power of biopotentials spectrum decreased within the whole analyzed frequency range.     

Ionic channels in Langmuir-Blodgett films imaged by a scanning tunneling microscope.

The molecular structure of channels formed by gramicidin A in a lipid membrane was imaged by a scanning tunneling microscope operating in air. The mono- and bimolecular films of lipid with gramicidin A were deposited onto a highly oriented pyrolitic graphite substrate by the Langmuir-Blodgett technique. It has been shown that under high concentration gramicidin A molecules can form in lipid films a quasi-regular, densely packed structure. Single gramicidin A molecules were imaged for the first time as well. The cavity of 0.4 +/- 0.05 nm in halfwidth was found on the scanning tunneling microscopy image of the gramicidin A molecule. The results of direct observation obtained by means of scanning tunneling microscope are in good agreement with the known molecular model of gramicidin A. It was shown that gramicidin A molecules can exist in a lipid monolayer as individual molecules or combined into clusters. The results demonstrate that scanning tunneling microscope can be used for high spatial resolution study of ionic channel structure.     

Heat stress in microwave irradiation

In experiments on 159 sexually mature dogs with an average weight of 6.5 + 0.71 kg, a study was made of the dynamics of physiological indices (rectal temperature, respiration and heart activity) of heat stress and various (%) effects of damage depending on power density (500, 300, 100 mV/cm2) and duration of microwave irradiation (2400 MHz). On the basis of the data obtained, it was established that the relationship between power density and duration of microwave irradiation with an equally probable (0.1%) effect of damage may be interpolated (100 < power density < 500) by an exponential equation of the type y = 1416 x-0.8156, where y = power density, mV/cm2, and x is the time of irradiation in minutes. The probability characteristic of adaptation possibilities of functionally critical values of damage not exceeding the indeterminate probability is obtained.