Phase changes in the permeability of the mouse blood-brain barrier after uneven gamma-irradiation

Two phases of changes in blood-brain-barrier permeability for sour fuchsin have been observed in the early period after head or body irradiation at 2.58 C/kg: an increase (up to 2 h) and a decrease (from 2 to 6 h). The correlation between the decrease in BBB permeability and the frequency of clinical manifestations of radiation disease has been established. BBB permeability progressively increased later after head irradiation (24-120 h) which was indicative of its absolute dysfunction. The changes observed may reflect redistribution of fluid and electrolytes in the vascular bed and tissues leading to the onset of brain tissue edema.     

Method of the anomalous time dependence of viscosity for registration of changes in conformational state of Escherichia coli cell genome

The sensitivity of the anomalous time dependence of viscosity to the concentration of the DNA-protein complexes (DNA + histone-like proteins of bacteria or, in other words, the genome) such as chromatin and the conformations of these complexes in lysates of E. coli AB1157 cells were studied. A linear region of the anomalous viscosity time dependence on the concentration of E. coli cells was found in which the interactions between single DNA-protein complexes can be neglected. The response of the genome of E. coli to ethidium bromide at concentrations of 0.0003-3 mg/ml was studied. Significant differences in the effect of ethidium bromide on E. coli cells in the stationary and logarithmic growth phases were found. The effect of heating cell lysates, the molar concentration of NaCl in lysates, and the addition of proteins into lysates on the parameters of the anomalous viscosity time dependence was studied. It was shown that proteins do not contribute significantly to the effect of anomalous viscosity time dependence. The results obtained confirm that the method is sensitive to changes in the conformational state of the genome of E. coli cells.     

Radioprotective capacity of indralin in reducing radiation injury to salivary glands

Radioprotective capacity of radioprotector indraline (alpha-1(B)-adrenoagonist) was studied by its effect on early displays of a local radiation injury to salivary glands in white rats after X-ray irradiation of an animal head with a dose of 18.7 Gy. Indraline was found to be capable to reduce a radiation injury to parotid glands registered by reduction of gland mass on 6th day after irradiation. In experiments on rats, radioprotective efficiency of indraline (100 mg/kg) in term of DRF is close to 1.5.     

Fibronectin matrix assembly requires distinct contributions from Rho kinases I and -II

Extracellular matrix is integral to tissue architecture and regulates many aspects of cell behavior. Fibronectin matrix assembly involves the actin cytoskeleton and the small GTPase RhoA, but downstream signaling is not understood. Here, down-regulation of either rho kinase isoform (ROCK I or -II) by small interfering RNA treatment blocked fibronectin matrix assembly, although the phenotypes were distinct and despite persistence of the alternate kinase. Remnant fibronectin on ROCK-deficient fibroblasts was mostly punctate and more deoxycholate soluble compared with controls. Fibronectin matrix assembly defects in ROCK-deficient cells did not result from decreased synthesis/secretion, altered fibronectin mRNA splicing, metalloproteinase activity, or alpha5beta1 integrin dysfunction. Rescue could be effected by ROCK protein restoration or phosphomimetic myosin light chain expression. However, the effect of ROCK I deficiency on fibronectin matrix assembly was secondary to altered cell surface morphology, rich in filopodia, resulting from high GTP-Cdc42 levels. Total internal reflection microscopy revealed that a submembranous pool of myosin light chain in control cells was missing in ROCK II-deficient cells and replaced by stress fibers. Together, two rho kinases contribute to fibronectin matrix assembly in a different manner and cortical myosin II-driven contractility, but not stress fibers, may be critical in this activity.     

Registration of changes in the nucleoide conformation based on the analysis of the time dependence of viscosity

The sensitivity of the method of anomalous time dependence of viscosity to changes in the conformation of DNA-protein complexes (such as nucleoide) by the action of (1) nalidixic acid on cells and (2) one- and two-charged ions Na+, Cl-, Cu2+, Ca2+, Mg2+, Zn2+, SO4(2-) on Escherichia coli cells has been studied. The data obtained suggest that the method anomalous time dependence of viscosity is highly sensitive to the conformation of high-molecular DNA-protein complexes. It was shown that the method anomalous time dependence of viscosity can be used to register cell sensitivity to changes in the concentration of one- and two-charged ions in suspension.     

Limiting Parameters of the Plasma Opening Switch

Implementing programs for nuclear fusion research and X-ray generation requires the creation of superpower generators based on plasma opening switches (POSs) capable of commutating currents as high as several tens of megaamperes at output voltages of up to 5 MV and higher. The physical mechanisms limiting the POS voltage are investigated. It is shown that, as the generator voltage U _g increases, the voltage multiplication factor k = U_POS/U_g (where U_POS is the POS voltage) decreases. An explanation for such a dependence is proposed, and the maximum value of the POS voltage is estimated. A POS design that enables operating in the above current and voltage ranges is considered. The design is based on applying an external magnetic field to the POS interelectrode gap, increasing the initial generator voltage, and decreasing the linear (along the perimeter of the outer electrode) density of the charge passing through the POS during the conduction phase.