Radiodiagnosis of echinococcosis of the lungs]

The paper is devoted to analysis of radio-diagnostic findings of 79 patients with parietal round pulmonary formations. All the patients were investigated by x-ray and ultrasound, perfusion scintigraphy of the lungs with a postural test was performed in 43 of them. Diagnostic x-ray and echographic methods were compared and evaluated in terms of defining the origin of pulmonary formations. The origin of pulmonary formations was established by x-ray in 50 of 79 patients (63.3 per cent) whereas ultrasound findings proved correct in 74 of 79 patients (93.6 per cent). Perfusion scintigraphy can be recommended to patients with pulmonary echinococcosis only for limited indications when a necessity arises to assess the lesser circulatory state in terms of patients' functional operability.     

Mechanosensitivity of gramicidin A channels in bulged bilayer membranes at constant tension

Mechanoelectrical transduction in gramicidin A channels was studied in macroscopic planar lipid bilayer membranes bulged at constant tension. We found a supralinear increase in the single channel activity that was proportional to the square of membrane radius, but could not be accounted for by the increase in membrane surface area, or by recruitment of new channels. Extrapolated to biological membranes, these observations may suggest that the permeability of ion channels can be influenced simply by changing shape of the membrane, with or without stretching. Published in Russian in Biofizika, 2006, Vol. 51, No. 6, pp. 1014–1018. The text was submitted by the authors in English.     

A method for determining the CO2 released by resting cells of microorganisms during the oxidation of hydrocarbons

A method is proposed for determining the oxidation of hydrocarbon substrates by microorganisms. The method is based on measuring the evolution of CO2 into the medium when the substrate is oxidized by washed microbial cells adsorbed on a spongy surface and incubated in a closed space into which CO2-free air is passed.     

Gating of amiloride-sensitive Na(+) channels: subunit-subunit interactions and inhibition by the cystic fibrosis transmembrane conductance regulator

In search of the structural basis for gating of amiloride-sensitive Na(+) channels, kinetic properties of single homo and heterooligomeric ENaCs formed by the subunits with individual truncated cytoplasmic domains were studied in a cell-free planar lipid bilayer reconstitution system. Our results identify the N-terminus of the alpha-subunit as a major determinant of kinetic behavior of both homooligomeric and heterooligomeric ENaCs, although the carboxy-terminal domains of beta- and gamma-ENaC subunits play important role(s) in modulation of the kinetics of heterooligomeric channels. We also found that the cystic fibrosis transmembrane conductance regulator (CFTR) inhibits amiloride-sensitive channels, at least in part, by modulating their gating. Comparison of these data suggests that the modulatory effects of the beta- and gamma-ENaC subunits, and of the CFTR, may involve the same, or closely related, mechanism(s); namely, "locking" the heterooligomeric channels in their closed state. These mechanisms, however, do not completely override the gating mechanism of the alpha-channel.     

Mechanosensitivity of an epithelial Na+ channel in planar lipid bilayers: release from Ca2+ block.

A family of novel epithelial Na+ channels (ENaCs) have recently been cloned from several different tissues. Three homologous subunits (alpha, beta, gamma-ENaCs) from the core conductive unit of Na(+)-selective, amiloride-sensitive channels that are found in epithelia. We here report the results of a study assessing the regulation of alpha,beta,gamma-rENaC by Ca2+ in planar lipid bilayers. Buffering of the bilayer bathing solutions to [Ca2+] < 1 nM increased single-channel open probability by fivefold. Further investigation of this phenomenon revealed that Ca2+ ions produced a voltage-dependent block, affecting open probability but not the unitary conductance of ENaC. Imposing a hydrostatic pressure gradient across bilayers containing alpha,beta,gamma-rENaC markedly reduced the sensitivity of these channels to inhibition by [Ca2+]. Conversely, in the nominal absence of Ca2+, the channels lost their sensitivity to mechanical stimulation. These results suggest that the previously observed mechanical activation of ENaCs reflects a release of the channels from block by Ca2+.     

The innate immune receptor MDA5 limits rotavirus infection but promotes cell death and pancreatic inflammation

Melanoma differentiation‐associated protein 5 (MDA5) mediates the innate immune response to viral infection. Polymorphisms in IFIH1, the gene coding for MDA5, correlate with the risk of developing type 1 diabetes (T1D). Here, we demonstrate that MDA5 is crucial for the immune response to enteric rotavirus infection, a proposed etiological agent for T1D. MDA5 variants encoded by minor IFIH1 alleles associated with lower T1D risk exhibit reduced activity against rotavirus infection. We find that MDA5 activity limits rotavirus infection not only through the induction of antiviral interferons and pro‐inflammatory cytokines, but also by promoting cell death. Importantly, this MDA5‐dependent antiviral response is specific to the pancreas of rotavirus‐infected mice, similar to the autoimmunity associated with T1D. These findings imply that MDA5‐induced cell death and inflammation in the pancreas facilitate progression to autoimmune destruction of pancreatic β‐cells.     

Subalpine grassland carbon dioxide fluxes indicate substantial carbon losses under increased nitrogen deposition,but not at elevated ozone concentration

Ozone (O₃) and nitrogen (N) deposition affect plant carbon (C) dynamics and may change ecosystem C‐sink/‐source properties. We studied effects of increased background [O₃] (up to [ambient] × 2) and increased N deposition (up to +50 kg ha^?1 a^?1) on mature, subalpine grassland during the third treatment year. During 10 days and 13 nights, distributed evenly over the growth period of 2006, we measured ecosystem‐level CO₂ exchange using a static cuvette. Light dependency of gross primary production (GPP) and temperature dependency of ecosystem respiration rates (R_eco) were established. Soil temperature, soil water content, and solar radiation were monitored. Using R_eco and GPP values, we calculated seasonal net ecosystem production (NEP), based on hourly averages of global radiation and soil temperature. Differences in NEP were compared with differences in soil organic C after 5 years of treatment. The high [O₃] had no effect on aboveground dry matter productivity (DM), but seasonal mean rates of both R_eco and GPP decreased ca. 8%. NEP indicated an unaltered growing season CO₂–C balance. High N treatment, with a +31% increase in DM, mean R_eco increased ca. 3%, but GPP decreased ca. 4%. Consequently, seasonal NEP yielded a 53.9 g C m^?2 (±22.05) C loss compared with control. Independent of treatment, we observed a negative NEP of 146.4 g C m^?2 (±15.3). Carbon loss was likely due to a transient management effect, equivalent to a shift from pasture to hay meadow and a drought effect, specific to the 2006 summer climate. We argue that this resulted from strongly intensified soil microbial respiration, following mitigation of nutrient limitation. There was no interaction between O₃ and N treatments. Thus, during the 2006 growing season, the subalpine grassland lost >2% of total topsoil organic C as respired CO₂, with increased N deposition responsible for one‐third of that loss.