Vladimír Rudajev

Prolonged agonist stimulation does not alter the protein composition of membrane domains in spite of dramatic changes induced in a specific signaling cascade

Protein composition of membrane domains prepared by three different procedures (mechanical homogenization, alkaline treatment with 1 M Na2CO3[pH 11.0], or extraction with nonionic detergent Triton X-100), and isolated from the bulk of plasma membranes by flotation on equilibrium sucrose density gradients, was analyzed by two-dimensional (2D) electrophoresis and compared in preparations from control (quiescent) and agonist-stimulated human embryonic kidney cells (HEK)293 or S49 cells. HEK293 cells (clone e2m11) stably expressing high levels of thyrotropin-releasing hormone receptor and G11α protein were stimulated by thyrotropin-releasing hormone and S49 lymphoma cells by the β-adrenergic receptor agonist isoprenaline. Whereas sustained exposure (16h) of both cell lines to the appropriate hormones led to substantial cellular redistribution and downregulation of the cognate G proteins (Gqα/G11α and Gsα, respectively), the distribution and levels of nonstimulated Gi proteins remained unchanged. The 2D electrophoretic analysis of membrane domains distinguished approx 150–170 major proteins in these structures and none of these proteins was significantly altered by prolonged agonist stimulation. Furthermore, specific immunochemical determination of a number of plasma membrane markers, including transmembrane and glycosyl-phosphatidylinositol-anchored peripheral proteins, confirmed that their detergent-extractability/solubility was not influenced by hormone treatment. Collectively, our present data indicate that sustained hormone stimulation of target cells does not alter the basic protein composition of membrane domain/raft compartments of the plasma membrane in spite of marked changes proceeding in a given signaling cascade.

Assessment of Fracture Properties from P-Wave Velocity Distribution

Seismic measurements carried out on peridotite rock outcrop showed that seismic wave velocity depends on the direction of propagation. It was found out that the velocity is influenced on system of fractures. The fracture sets can cause velocity dispersion. The theory of displacement discontinuity was applied for an explanation of fractures influence on the seismic wave propagation. According to this theory, the fracture stiffness can be assessed on the basis of velocity directional dependence. The measurements made proved experimentally the validity of this approach, specifically for the frequency interval from 500 Hz to 700 kHz.

Analysis of Acoustic Emission from Rock Samples Loaded to Long-Term Strength Limit

As shown in the previous papers by Rudajev,1, 2 the parameters of the statistical distribution of the acoustic emission (AE) are not random, although the origin of the acoustic signal is random in time. In the above papers it was shown that the parameters of distribution cohere with the strain stage of the loaded samples. The object of this paper is the analysis of the statistical distribution of AE, of the relation of their parameters to the process of fracturing, and mainly determining the probability of total fracture.

Βedrock instability of underground storage systems in the Czech Republic, Central Europe

Underground storage systems are currently being used worldwide for the geological storage of natural gas (CH4), the geological disposal of CO2, in geothermal energy, or radioactive waste disposal. We introduce a complex approach to the risks posed by induced bedrock instabilities in deep geological underground storage sites. Bedrock instability owing to underground openings has been studied and discussed for many years. The Bohemian Massif in the Czech Republic (Central Europe) is geologically and tectonically complex. However, this setting is ideal for learning about the instability state of rock masses. Longterm geological and mining studies, natural and induced seismicity, radon emanations, and granite properties as potential storage sites for disposal of radioactive waste in the Czech Republic have provided useful information. In addition, the Czech Republic, with an average concentration radon of 140 Bq m−3, has the highest average radon concentrations in the world. Bedrock instabilities might emerge from microscale features, such as grain size and mineral orientation, and microfracturing. Any underground storage facility construction has to consider the stored substance and the geological settings. In the Czech Republic, granites and granitoids are the best underground storage sites. Microcrack networks and migration properties are rock specific and vary considerably. Moreover, the matrix porosity also affects the mechanical properties of the rocks. Any underground storage site has to be selected carefully. The authors suggest to study the complex set of parameters from micro to macroscale for a particular place and type of rock to ensure that the storage remains safe and stable during construction, operation, and after closure.