Induction of murine hepatic glutathione S-transferase by dietary dehydroepiandrosterone

The naturally occurring steroid dehydroepiandrosterone (DHEA), when administered as a supplement to the diet of mice and rats, produces alterations in the relative concentrations of specific liver proteins; among these, a protein of Mr approximately 28 K is markedly induced by DHEA action. In the present study we identified the murine hepatic approximately 28 kDa protein as glutathione S-transferase subtype GT-8.7. Glutathione S-transferases belong to a gene superfamily that encode closely related proteins which are induced in liver and other tissues by various chemicals, including carcinogens and chemoprotective agents such as dietary antioxidants. Based on the above finding, we evaluated glutathione S-transferase activity in cytosols and microsomes prepared from liver tissue of mice fed either a control diet or a DHEA-containing diet (0.45%, by weight). The specific activity of hepatic cytosolic glutathione S-transferase in mice treated with DHEA up to 7 days was either unchanged or slightly decreased when compared to controls; however, treatment for 14 days or longer resulted in significant increases in activity. The specific activity of microsomal glutathione S-transferase also was increased by long-term DHEA treatment; however, its activity was approximately one-tenth of that in corresponding cytosols.     

Honeycomb-supported perovskite catalysts for high-temperature processes

Pechini route [US Patent No. 3,330,697 (1967)] was used for supporting perovskite-like systems on thin-wall corundum honeycomb support to prepare catalysts for high-temperature processes of methane combustion and selective oxidation into syngas. In this preparation, the surface of corundum monoliths walls was shown to be covered by strongly adhering porous perovskite layer formed by rounded crystals. At high temperatures when pore diffusion is expected to affect catalysts performance in fast reactions, this spatial distribution of the active component could be attractive. In the kinetically controlled region of methane oxidation, samples prepared via Pechini route possess activity comparable with that of samples made via support wet impregnation with mixed nitrate solutions, when an active component is uniformly distributed across the wall thickness. Corundum-supported lanthanum manganite and ferrite are the most active in the reaction of methane combustion, while its selective oxidation into syngas effectively proceeds on supported lanthanum cobaltite and nickelates. Corundum-supported perovskites are more thermally stable as compared with those on γ-alumina support.     

Phase composition and electrochemical behavior of ATsKM aluminum protector alloy

The phase composition has been determined for a new protector alloy that contains zinc, calcium, and magnesium together, with elevated amounts relative to standard alloy of the impurities iron, silicon, and copper. The quantitative composition of the phases has been determined. The mechanisms have been identified for the spontaneous dissolution and anodic dissolution of this alloy and the roles of the major phases have been established. There is a relationship between the phase composition of the alloy and the electrochemical behavior. Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos: 5-6(395), pp. 85–89, May–June, 1997.     

Structure and mechanical properties of the compositions of polyisocyanurate polymers with low molecular weight rubbers

The structure and properties of the compositions of polyisocyanurates modified with low molecular weight rubber networks have been investigated by means of dynamical mechanical analysis (DMA), electron microscopy, and stress-relaxation experiments. The network compositions consist of two different polymeric networks. The first component (macrodi-isocyanate based on low molecular weight polybutadiene or copolymers of tetrahydrofuran and propylene oxide) has bulky cross-linked points connected by short flexible chains. The second component (diphenylmethanediisocyanate) also has bulky cross-linked points of the same structure, but the linear fragments between them in this case are very small and rigid. These compositions result in the formation of the heterophase system. As a result, transparent samples were prepared, which differ from the mechanical properties of both the glassy and rubbery polymers. These materials have a modulus of elasticity (from 10³ to 10 MPa) that is usual for the transition zone between the glassy and rubbery states; nevertheless, these materials show elastic (and not viscoelastic) properties. For the materials investigated, the modulus is decreased not more than 10 times in the wide temperature interval from 200 to 500 K. A new state of the polymer, which differs from both the glassy and rubbery states, has been identified in the present case. © 1995 John Wiley & Sons, Inc.     

Generalized XML security views

We investigate a generalization of the notion of XML security view introduced by Stoica and Farkas (Proceedings of the 16th International Conference on Data and Applications Security (IFIP’02). IFIP Conference Proceedings, vol. 256, pp. 133–146. Kluwer, Dordrecht, 2002) and later refined by Fan et al. (Proceedings of the ACM SIG- MOD International Conference on Management of Data (SIGMOD’04), pp. 587–598. ACM Press, New York, 2004). The model consists of access control policies specified over DTDs with XPath expressions for data-dependent access control. We provide the notion of security views characterizing information accessible to authorized users. This is a trans- formed DTD schema that can be used by users for query formulation. We develop an algorithm to materialize an authorized version of the document from the view and an algorithm to construct the view from an access control specification. We show that our view construction combined with materialization produces the same result as the direct application of the DTD access specification on the document. We also propose a number of generalizations of possible security policies and show how they affect view construction algorithm. Finally, we provide an evaluation of our system.