Long-term SO2 dispersion modeling over a coastal region.

Air dispersion modeling over coastal regions has proven to be a remarkable challenge in the field of air quality. Many conventional plume dispersion models, such as ISC2 and HYSPLIT, are unable to model such dispersion with the precision that is necessary to accurately predict ground-level concentrations in coastal areas. Considering this, the present work was carried out with two primary objectives: i) to evaluate the effectiveness of currently available mathematical models in predicting plume dispersion over a coastal region and ii) to study the impact of sulfur dioxide emissions from a petroleum refinery over a different community located in the adjacent area. This study demonstrates that CALPUFF predictions are more reliable compared to those of the other models studied, however the operation of CALPUFF is highly data intensive and in many instances, it is difficult to obtain all required input data. This is a particular problem for regions outside ofthe United States of America where sufficient data is difficult to obtain. In addition, the study concluded that the predicted annual average SO2 concentrations in the nearby communities are well within regulatory limits.

Molecular mechanisms involved in human platelet aggregation by synergistic interaction of platelet-activating factor and 5-hydroxytryptamine.

Our recent studies have shown that co-activation of Gq and Gi proteins by 5-hydroxytryptamine (5-HT) and adrenaline show synergism in human platelet aggregation. This study was conducted to examine the mechanism(s) of synergistic interaction of 5-HT and platelet activating factor (PAF) in human platelets. We show that PAF, but not 5-HT, increased platelet aggregation in a concentration-dependent manner. However, low concentrations of 5-HT (2 microM) potentiated platelet aggregation induced by subthreshold concentration of PAF (40 nM) indicating a synergistic interaction between the two agonists and this synergism was blocked by receptor antagonists to either 5-HT or PAF. 5-HT also potentiated the effect of PAF on thromboxane A2 (TXA2) formation and phosphorylation of extracellularly regulated mitogen-activated protein kinases (ERK1/2). The synergism of 5-HT and PAF in platelet aggregation was inhibited by calcium (Ca2+) channel blockers, verapamil and diltiazem, phospholipase C (PLC) inhibitor, U73122, cyclooxygenase (COX) inhibitor, indomethacin, and MEK inhibitor, PD98059. These data suggest that synergistic effect of 5-HT and PAF on human platelet aggregation involves activation of PLC/Ca2+, COX and MAP kinase pathways.