Observation of Highly Virtual Photon-Photon Collisions to Hadrons at TRISTAN

We have observed highly virtual ($Q^2>1.05 GeV^2$) photon-photon collisions to hadronic final states at $\sqrt{s_{e^+e^-}}=58 GeV$. The integrated luminosity of the data sample was 241pb$^{-1}$. Both scattered beam-electrons and scattered beam-positrons were detected using low-angle calorimeters (i.e., both photons were highly virtual, "double-tag"); we obtained 115 hadronic events with an estimated background of $10.2\pm1.1$. The cross section obtained was $4.11\pm0.66$pb in the $2<W_{\gamma \gamma}<25$ GeV and $Q^2_{\gamma, min}>2$ GeV region, while the lowest order quark-parton model predicted 3.00pb.Comment: 14 pages, latex (revtex), 2 figures, available at http://topsun1.kek.jp/~enomoto/dtag.p

Lung epithelium as a sentinel and effector system in pneumonia – molecular mechanisms of pathogen recognition and signal transduction

Pneumonia, a common disease caused by a great diversity of infectious agents is responsible for enormous morbidity and mortality worldwide. The bronchial and lung epithelium comprises a large surface between host and environment and is attacked as a primary target during lung infection. Besides acting as a mechanical barrier, recent evidence suggests that the lung epithelium functions as an important sentinel system against pathogens. Equipped with transmembranous and cytosolic pathogen-sensing pattern recognition receptors the epithelium detects invading pathogens. A complex signalling results in epithelial cell activation, which essentially participates in initiation and orchestration of the subsequent innate and adaptive immune response. In this review we summarize recent progress in research focussing on molecular mechanisms of pathogen detection, host cell signal transduction, and subsequent activation of lung epithelial cells by pathogens and their virulence factors and point to open questions. The analysis of lung epithelial function in the host response in pneumonia may pave the way to the development of innovative highly needed therapeutics in pneumonia in addition to antibiotics