Platelet-activating Factor–mediated NF-κB Dependency of a Late Anaphylactic Reaction

Anaphylaxis is a life-threatening systemic allergic reaction with the potential for a recurrent or biphasic pattern. Despite an incidence of biphasic reaction between 5 and 20%, the molecular mechanism for the reaction is unknown. Using a murine model of penicillin V–induced systemic anaphylaxis, we show an autoregulatory cascade of biphasic anaphylactic reactions. Induction of anaphylaxis caused a rapid increase in circulating platelet-activating factor (PAF) levels. In turn, the elevated PAF contributes to the early phase of anaphylaxis as well as the subsequent activation of the nuclear factor (NF)-κB, a crucial transcription factor regulating the expression of many proinflammatory cytokines and immunoregulatory molecules. The induction of NF-κB activity is accompanied by TNF-α production, which, in turn, promotes late phase PAF synthesis. This secondary wave of PAF production leads eventually to the late phase of anaphylactic reactions. Mast cells do not appear to be required for development of the late phase anaphylaxis. Together, this work reveals the first mechanistic basis for biphasic anaphylactic reactions and provides possible therapeutic strategies for human anaphylaxis

A study on the overall efficiency of direct methanol fuel cell by methanol crossover current

This paper was presented to determine the methanol crossover and efficiency of a direct methanol fuel cell (DMFC) under various operating conditions such as cell temperature, methanol concentration, methanol flow rate, cathode flow rate, and cathode backpressure. The methanol crossover measurements were performed by measuring crossover current density at an open circuit using humidified nitrogen instead of air at the cathode and applied voltage with a power supply. The membrane electrode assembly (MEA) with an active area of 5 cm2 was composed of a Nafion 117 membrane, a Pt-Ru (4 mg/cm2) anode catalyst, and a Pt (4 mg/cm2) cathode catalyst. It was shown that methanol crossover increased by increasing cell temperature, methanol concentration, methanol flow rate, cathode flow rate and decreasing cathode backpressure. Also, it was revealed that the efficiency of the DMFC was closely related with methanol crossover, and significantly improved as the cell temperature and cathode backpressure increased and methanol concentration decreased.Direct methanol fuel cell (DMFC) Methanol crossover Efficiency Operating conditions

Lithium metal polymer cells assembled with gel polymer electrolytes containing ionic liquid

Gel polymer electrolytes containing a mixture of organic solvent and ionic liquid were prepared and their electrochemical properties were investigated. The gel polymer electrolytes exhibited good electrochemical stability and stable interfacial properties toward lithium metal. Using these gel polymer electrolytes, lithium metal polymer cells composed of a lithium anode and a LiFePO4 cathode were assembled, and their cycling performances were evaluated. The cells showed good cycling performance comparable to that of a cell assembled with gel polymer electrolyte containing only organic liquid electrolyte. The Li/LiFePO4 cells assembled with a gel polymer electrolyte containing ionic liquid are expected to be one of the promising candidates for high energy density lithium batteries with improved safety.close5

Preparation and Electrical Properties of Silicone Composite Films Based on Silver Nanoparticle Decorated Multi-Walled Carbon Nanotubes

The electrical properties of silicone composite films filled with silver (Ag) nanoparticle-decorated multi-walled carbon nanotubes (MWNT) prepared by solution processing are investigated. Pristine MWNT is oxidized and converted to the acyl chloride-functionalized MWNT using thionyl chloride, which is subsequently reacted with amine-terminated poly(dimethylsiloxane) (APDMS). Thereafter, APDMS-modified MWNT are decorated with Ag nanoparticles and then reacted with a poly(dimethylsiloxane) solution to form Ag-decorated MWNT silicone (Ag-decorated MWNT-APDMS/Silicone) composite. The morphological differences of the silicone composites containing Ag-decorated MWNT and APDMS-modified MWNT are observed by transmission electron microscopy (TEM) and the surface conductivities are measured by the four-probe method. Ag-decorated MWNT-APDMS/Silicone composite films show higher surface electrical conductivity than MWNT/silicone composite films. This shows that the electrical properties of Ag-decorated MWNT-APDMS/silicone composite films can be improved by the surface modification of MWNT with APDMS and Ag nanoparticles, thereby expanding their applications

Role of interleukin-6 in the control of DNA synthesis of hepatocytes: involvement of PKC, p44/42 MAPKs, and PPARdelta

Interleukin-6 (IL-6) is a pleiotropic cytokine with a pivotal role in normal hepatic growth and liver regeneration. Therefore, in the present study, we examined the effect of IL-6 on cell proliferation and the related signaling pathways in primary cultured chicken hepatocytes. IL-6 increased the level of [3H]thymidine incorporation in a time ( 6 hr)- and a dose ( 0.1 ng/ml)-dependent manner. Indeed, IL-6 increased the number of BrdU-positive cells and the total number of cells. IL-6 (10 ng/ml) increased the level of IL-6R and glycoprotein (gp) 130 (IL-6R) protein expression, Janus Kinase (JAK) 2, signal transducer and activator of transcription (STAT) 3, PKC, p44/42 MAPKs phosphorylation, and PPAR protein expression. Inhibition of each pathways blocked IL-6-induced [3H]thymidine incorporation increase. IL-6 increased c-fos, c-jun, and c-myc proto-oncogene mRNA levels and the percentage of cells in the S phase according to fluorescence-activated cell sorter (FACS) analysis. IL-6-induced G1/S phase progression was inhibited by AG 490 (2x10-5 M, JAK2 inhibitor), a STAT3 inhibitor peptide (10-5 M), bisindolylmaleimide I (10-6 M, PKC inhibitor), PD 98059 (10-5 M, p44/42 MAPKs blocker), or PPAR-specific small interfering RNAs (siRNAs). In conclusion, IL-6 stimulates the proliferation of primary cultured chicken hepatocytes through PKC, p44/42 MAPKs, and PPAR pathways.This study was supported by a Grant from Korea Rural Development Administration (BioGreen 21 Program, 20050301-034-487-007-0300). The authors acknowledge a graduate fellowship provided by the Ministry of Education, Science and Technology through the Brain Korea 21 Project, Korea

Enhanced Optical Output Power of Tunnel Junction GaN-Based Light Emitting Diodes with Transparent Conducting Al and Ga-Codoped ZnO Thin Films

High quality Al and Ga-codoped ZnO (AGZO) thin films were successfully deposited both on sapphire substrates and GaN-based light emitting diodes (LED) with a tunnel junction (TJ) layer by using the radio frequency magnetron sputtering technique at room temperature. The AGZO thin films grown on sapphire substrate showed high transparency (96.3% at 460 nm) and low resistivity (6.8 x 10(-4) Omega cm). The AGZO thin films deposited on the GaN-based LED with a TJ layer exhibited weak ohmic behavior although it improved slightly with the annealing. The optical output power of the TJ GaN-based LED with an AGZO transparent conducting layer was about 12.6mW at 20 mA, and the external quantum efficiency was 23.0%. These values are approximately 1.7 times larger than that of the TJ GaN-based LED with a conventional Ni/Au layer. (C) 2010 The Japan Society of Applied Physicclose3