Mechanisms Adopted by Dengue-2 Viruses to Induce Autophagy in Mammalian Cells

Dengue, the most rapidly spreading flavivirus, threatens to affect almost half of the human global population. We previously showed that dengue-2 protects canine kidney cells (MDCK) from cytotoxic chemicals. We showed, independently, that cell protection, as well as viral replication and maturation, are positively regulated by PI3K-dependent autophagy. However, we had not identified the specific pathway that induces autophagy in infected cells. The current study explores the role of a specific branch of the endoplasmic reticulum (ER) stress-mediated Unfolded Protein Response (UPR), the PERK/eIF2α/ATF4 pathway in the induction of autophagy by Dengue. We studied the relationship between the PERK pathway and induction of autophagy in infected MDCK and MEF cells. We extended this study to determine whether PERK activity correlates with protection of infected cells. Finally, we identified Ataxia Telangiectasia Mutated (ATM), a DNA damage response (DDR) protein as an upstream regulator of PERK, autophagy, and cell protection. Our data show that, when dengue infects cells, ATM is an early regulator that activates PERK, autophagy and cell protection. Since PERK and autophagy have been implicated in viral production, the current study identifies several putative targets for antiviral therapy, although these targets also serve multiple housekeeping functions (stress response, protein folding, and homeostasis) in the cell. Future studies should focus on the links between these pathways and identify an antiviral target that is redundant or non-essential for the host cell

Pd ion substituted CeO<SUB>2</SUB>: a superior de-NO<SUB>x</SUB> catalyst to Pt or Rh metal ion doped ceria

Pd, Pt and Rh ion doped CeO2, Ce1-xMxO2-&#948; (M = Pd2+, Pt2+, Rh3+) were synthesized by solution combustion synthesis method and the deNOx activity was investigated by NO + CO reaction. Ionically dispersed Pd in CeO2 was found to have better catalytic activity than ionically dispersed Pt or Rh in CeO2. High rates of NO conversion and high selectivity of N2 is observed over Ce0.98Pd0.02O2-&#948;. A bi-functional reaction mechanism is proposed, which fits very well with the experimental results. The oxide ion vacancy present in the CeO2 matrix seems to play an important role for product selectivity and high rate of reaction

Pd ion substituted CeO2CeO_2: A superior de−NOxde-NO_x catalyst to Pt or Rh metal ion doped ceria

Pd, Pt and Rh ion doped $CeO_2$, $Ce_{1-x}M_xO_{2-\delta}$(M = $Pd^{2+}$, $Pt^{2+}$, $Rh^{3+}$) were synthesized by solution combustion synthesis method and the $deNO_x$ activity was investigated by NO + CO reaction. Ionically dispersed Pd in $CeO_2$ was found to have better catalytic activity than ionically dispersed Pt or Rh in $CeO_2$. High rates of NO conversion and high selectivity of $N_2$ is observed over $Ce_{0.98}Pd_{0.02}O_{2-\delta}$. A bi-functional reaction mechanism is proposed, which fits very well with the experimental results. The oxide ion vacancy present in the $CeO_2$ matrix seems to play an important role for product selectivity and high rate of reaction

Synthesis, structure and photocatalytic activity of nano TiO2TiO_{2} and nano Ti1−xMxO2−δTi_{1-x}M_{x}O{2-\delta} (M = Cu, Fe, Pt, Pd, V, W, Ce, Zr)

We have synthesized 5-7 nm size, highly crystalline $TiO_{2}$ which absorbs radiation in the visible region of solar spectrum. The material shows higher photocatalytic activity both in UV and visible region of the solar radiation compared to commercial Degussa P25 $TiO_{2}$. Transition metal ion substitution for $Ti^{4+}$ creates mid-gap, states which act as recombination centers for electron-hole induced by photons thus reducing photocatalytic activity. However, Pt, Pd and Cu ion substituted $TiO_{2}$ are excellent CO oxidation and NO reduction catalysts at temperatures less than 100 degrees C

Catalysis for NOx abatement

Research in the field of NOx abatement has grown significantly in the past two decades. The general trend has been to develop new catalysts with complex materials in order to meet the stringent environmental regulations. This review discusses briefly about the different sources of NOx and its adverse effect on the ecosystem. The main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H2 or NH3 or hydrocarbons. The importance of understanding the mechanism of NO decomposition and reduction in presence of metal ion substituted catalysts is emphasized. Some conclusions are made on the various catalytic approaches to NOx abatement.NOx reduction Metal ion substitution Environmental catalysis

Catalysis for NO<SUB>x</SUB> abatement

Research in the field of NOx abatement has grown significantly in the past two decades. The general trend has been to develop new catalysts with complex materials in order to meet the stringent environmental regulations. This review discusses briefly about the different sources of NOx and its adverse effect on the ecosystem. The main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H2 or NH3 or hydrocarbons. The importance of understanding the mechanism of NO decomposition and reduction in presence of metal ion substituted catalysts is emphasized. Some conclusions are made on the various catalytic approaches to NOx abatement

Electro-oxidation Reaction of Methanol over Reducible Ce_{1–<i>x</i>–<i>y</i>}Ni_<i>x</i>Sr_<i>y</i>O_2−δ: A Mechanistic Probe of Participation of Lattice Oxygen

Methanol oxidation reaction crucially depends on the formation of −OOH species over the catalyst’s surface. Ni-based catalysts are by far the choice of materials, where the redox couple of Ni2+/Ni3+ facilitates the formation of −OOH species by surface reconstructions. However, it is challenging to oxidize Ni2+ as it generates charge-transfer orbitals near the Fermi energy level. One possible solution is to substitute Ni2+ with a reducible oxide support, which will not only facilitate the Ni2+ → Ni3+ oxidation but also adsorb oxygenated species like −OOH at a lower potential owing to its oxophilicity. This work shows with the help of structural and surface studies that the reducible CeO2 support in Ni and Sr co-doped Ce1–x–yNixSryO2−δ solid solution can easily facilitate Ni2+ → Ni3+ oxidation as well as evolution of lattice oxygen during the methanol oxidation reaction. While the Ni3+ species helped in formation of −OOH surface intermediates, the evolved lattice oxygen eased the CO oxidation process in order to bring out the better CO-tolerant methanol oxidation activity over Ce1–x–yNixSryO2−δ. The study shows the unique importance of the electronic interactions between the active site and support and involvement of lattice oxygen in the methanol oxidation reaction

Catalysis for NOx abatement

Research in the field of NOx abatement has grown significantly in the past two decades. The general trend has been to develop new catalysts with complex materials in order to meet the stringent environmental regulations. This review discusses briefly about the different sources of NOx and its adverse effect on the ecosystem. The main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H-2 or NH3 or hydrocarbons. The importance of understanding the mechanism of NO decomposition and reduction in presence of metal ion substituted catalysts is emphasized. Some conclusions are made on the various catalytic approaches to NOx abatement

Kinetics of photocatalytic reduction of NO by CO with Pd2+-Ion-Substituted Nano-TiO2

The objective of the present study is to develop the reaction mechanism and kinetics of photoreduction of NO by CO. For this purpose, the reactions were conducted in the presence of Pd-ion-substituted nano-TiO2, Ti1-xPdxO2-delta, which was synthesized via a solution combustion method. The photocatalytic activity was investigated with unsubstituted TiO2, 1% Pd/TiO2(imp), and Ti1-xPdxO2-delta (where x = 0.05-0.3). No appreciable NO conversion was observed over unsubstituted TiO2, although, despite competitive adsorption of NO and CO on the Pd2+ sites, there was a significant reduction of NO over Ti1-xPdxO2-delta. The kinetic model showed that the enhanced catalytic activity is due to the NO photodissociation at the oxide-ion vacancy