Non-Opsonic Phagocytosis of Legionella pneumophila by Macrophages Is Mediated by Phosphatidylinositol 3-Kinase

Background: Legionella pneumophila, is an intracellular pathogen that causes Legionnaires ’ disease in humans, a potentially lethal pneumonia. L. pneumophila has the ability to enter and replicate in the host and is essential for pathogenesis. Methodology/Principal Findings: Phagocytosis was measured by cell invasion assays. Construction of PI3K mutant by PCR cloning and expression of dominant negative mutant was detected by Western blot. PI3K activity was measured by 32 P labeling and detection of phospholipids products by thin layer chromatography. Infection of macrophages with virulent L. pneumophila stimulated the formation of phosphatidylinositol 3-phosphate (PIP3), a phosphorylated lipid product of PI3K whereas two structurally distinct phosphatidylinositol 3 kinase (PI3K) inhibitors, wortmannin and LY294002, reduced L. pneumophila entry into macrophages in a dose-dependent fashion. Furthermore, PI3K activation led to Akt stimulation, a serine/threonine kinase, which was also inhibited by wortmannin and LY294002. In contrast, PI3K and protein kinase B (PKB/Akt) activities were lower in macrophages infected with an avirulent bacterial strain. Only virulent L. pneumophila increased lipid kinase activity present in immunoprecipitates of the p85a subunit of class I PI3K and tyrosine phosphorylated proteins. In addition, macrophages expressing a specific dominant negative mutant of PI3K reduced L. pneumophila entry into these cells. Conclusion/Significance: Entry of L. pneumophila is mediated by PI3K/Akt signaling pathway. These results suggest an important role for PI3K and Akt in the L. pneumophila infection process. They point to possible novel strategies fo

Interactions between decision making and performance monitoring within prefrontal cortex.

Our ability to judge the consequences of our actions is central to rational decision making. A large body of evidence implicates primate prefrontal regions in the regulation of this ability. It has proven extremely difficult, however, to separate functional areas in the frontal lobes. Using functional magnetic resonance imaging, we demonstrate complementary and reciprocal roles for the human orbitofrontal (OFC) and dorsal anterior cingulate cortices (ACd) in monitoring the outcome of behavior. Activation levels in these regions were negatively correlated, with activation increasing in the ACd and decreasing in the OFC when the selected response was the result of the participant's own decision. The pattern was reversed when the selected response was guided by the experimenter rather than the participant. These results indicate that the neural mechanisms underlying the way we assess the consequences of choices differ depending on whether we are told what to do or are able to exercise our volition

Evolving fuzzy systems

Article Outline: Glossary Definition of the Subject Introduction Evolving Clustering Evolving TS Fuzzy Systems Evolving Fuzzy Classifiers Evolving Fuzzy Controllers Application Case Studies Future Directions Acknowledgments Bibliograph