Increased arginase II activity contributes to endothelial dysfunction through endothelial nitric oxide synthase uncoupling in aged mice

The incidence of cardiovascular disease is predicted to increase as the population ages. There is accumulating evidence that arginase upregulation is associated with impaired endothelial function. Here, we demonstrate that arginase II (ArgII) is upregulated in aortic vessels of aged mice and contributes to decreased nitric oxide (NO) generation and increased reactive oxygen species (ROS) production via endothelial nitric oxide synthase (eNOS) uncoupling. Inhibiting ArgII with small interfering RNA technique restored eNOS coupling to that observed in young mice and increased NO generation and decreased ROS production. Furthermore, enhanced vasoconstrictor responses to U46619 and attenuated vasorelaxation responses to acetylcholine in aged vasculature were markedly improved following siRNA treatment against ArgII. These results might be associated with increased L-arginine bioavailability. Collectively, these results suggest that ArgII may be a valuable target in age-dependent vascular diseases.     

Robust Metaheuristic Algorithm for Redundancy Optimization in Large-Scale Complex Systems

Based upon the general tabu search methodology, this paper develops a robust metaheuristic algorithm for the redundancy optimization in large-scale complex system reliability that performs a rigorous search of the “attractive” feasible space and is capable of escaping from a local solution. An illustrative example is provided and extensive computational results are reported on two test problems from the literature (Aggarwal, 1976; Shi, 1987) and also on randomly generated large-scale instances of complex systems with up to 200 components. The computational results indicate that the proposed metaheuristic algorithm possesses a superior robustness and efficiency for solving the class of hard optimization problems studied in this paper.     

A study on the photophysical properties of anthracene in zeolite

The photophysical behaviours of anthracene in zeolite Y were investigated using various steady state spectroscopic methods and a picosecond time-resolved fluorescence spectroscopic technique. A ¹²⁹Xe nuclear magnetic resonance (NMR) study shows that anthracene molecules can be optimally intercalated into the supercages of Na⁺- and Cu²⁺-exchanged zeolite Y at 570 and 520 K respectively. Anthracene introduced into the supercage of Na⁺-exchanged zeolite Y shows excimeric fluorescence with a lifetime of several nanoseconds, as well as monomeric fluorescence with a lifetime of 300 ps. The excimer forms immediately on absorption of a photon. Cu²⁺-exchanged zeolite Y with anthracene intercalation shows electron spin resonance (ESR) signals and absorption bands attributable to the stable, ground state anthracene cation radical, the Cu⁺ ion and the trapped electron in the copper ion cluster, indicating charge transfer from anthracene to the Cu²⁺ ion or copper ion cluster. The excitation energy of anthracene is quenched rapidly by the presence of copper ion.     

Synthesis of Silicate Zeolite Analogues Using Organic Sulfonium Compounds as Structure‐Directing Agents

A microporous crystalline silica zeolite of the MEL structure type and three other zeolite analogues composed of germanosilicate frameworks were synthesized using tributylsulfonium, triphenylsulfonium, or tri(para‐tolyl)sulfonium as the structure‐directing agent. The germanosilicates thus obtained had ISV, ITT, or a new zeolite structure depending on the synthesis conditions. The structure of the new germanosilicate was solved using X‐ray powder diffraction data with the aid of a charge‐flipping method. The solution indicated a crystal structure belonging to the P63/mmc space group with cell parameters of a=16.2003 Å and c=21.8579 Å. After calcination, the new germanosilicate material exhibited two types of accessible micropores with diameters of 0.61 and 0.78 nm.     

High Catalytic Activity of Palladium(II)‐Exchanged Mesoporous Sodalite and NaA Zeolite for Bulky Aryl Coupling Reactions: Reusability under Aerobic Conditions

Exchange for the better : Mesoporous sodalite and NaA zeolite exchanged with Pd²⁺ exhibit remarkably high activity and reusability in C? C coupling reactions under aerobic atmosphere. It is proposed that the catalytic reactions are mediated by a molecular Pd⁰ species generated in situ within the pores (see picture), which is oxidized back to Pd²⁺ by O₂, preventing the formation of catalytically inactive Pd⁰ agglomerates.

     

Msx2 mediates the inhibitory action of TNF-�� on osteoblast differentiation

TNF-α, a proinflammatory cytokine, inhibits osteoblast differentiation under diverse inflammatory conditions; however, the underlying mechanisms in terms of the TNF-α signaling pathway remain unclear. In this study, we examined the role of Msx2 in TNF-α-mediated inhibition of alkaline phosphatase (ALP) expression and the signaling pathways involved. TNF-α down-regulated ALP expression induced by bone morphogenetic protein 2 (BMP2) in C2C12 and Runx2^-/- calvarial cells. Over-expression of Msx2 suppressed BMP2-induced ALP expression. Furthermore, TNF-α induced Msx2 expression, and the knockdown of Msx2 by small interfering RNAs rescued ALP expression, which was inhibited by TNF-α. TNF-α activated the NF-κB and the JNK pathways. Inhibition of NF-κB or JNK activation reduced the inhibitory effect of TNF-α on ALP expression, whereas TNF-α-induced Msx2 expression was only suppressed by the inhibition of the NF-κB pathway. Taken together, these results indicate that Msx2 mediates the inhibitory action of TNF-α on BMP2-regulated osteoblast differentiation and that the TNF-α-activated NF-κB pathway is responsible for Msx2 induction.     

Adsorption and Thermogravimetric Methods for Monitoring Surface and Structural Changes in Ordered Mesoporous Silicas Induced by their Chemical Modification

The current work demonstrates that the standard adsorption analysis has a limited applicability for characterization of chemically modified porous silicas. Since low-pressure nitrogen adsorption isotherms are sensitive to the surface changes caused by chemical modification of silicas, these isotherms were successfully used to evaluate their surface heterogeneity during different stages of modification. The surface analysis was accomplished by using adsorption energy distributions and high-resolution comparative plots.     

Synthesis of thermally stable mesoporous cerium oxide with nanocrystalline frameworks using mesoporous silica templates

Highly ordered mesoporous cerium oxides, composed of nanocrystalline pore walls and exhibiting high thermal stability even at 973 K, were synthesized using mesoporous silica templates with hexagonal p6mm and cubic Ia3d symmetries.