Supergravity pp-wave solutions with 28 and 24 supercharges

We conduct an exhaustive search for solutions of IIA and IIB supergravity with augmented supersymmetry. We find a two-parameter family of IIB solutions preserving 28 supercharges, as well as several other IIA and IIB families of solutions with 24 supercharges. Given the simplicity of the pp-wave solution, the algorithm described here represents a systematic way of classifying all such solutions with augmented supersymmetry. By T-dualizing some of these solutions we obtain exact non-pp wave supergravity solutions (with 8 or 16 supercharges), which can be interpreted as perturbations of the AdS-CFT correspondence with irrelevant operators

Timing of Specimen Collection for Blood Cultures from Febrile Patients with Bacteremia▿

Bloodstream infections are an important cause of morbidity and mortality. Physician orders for blood cultures often specify that blood specimens be collected at or around the time of a temperature elevation, presumably as a means of enhancing the likelihood of detecting significant bacteremia. In a multicenter study, which utilized retrospective patient chart reviews as a means of collecting data, we evaluated the timing of blood culture collection in relation to temperature elevations in 1,436 patients with bacteremia and fungemia. The likelihood of documenting bloodstream infections was not significantly enhanced by collecting blood specimens for culture at the time that patients experienced temperature spikes. A subset analysis based on patient age, gender, white blood cell count and specific cause of bacteremia generally also failed to reveal any associations

<i>Pfi</i>t Is a Structurally Novel Crohn's Disease-Associated Superantigen

<div><p>T cell responses to enteric bacteria are important in inflammatory bowel disease. I2, encoded by the <i>pfi</i>T gene of <i>Pseudomonas fluorescens</i>, is a T-cell superantigen associated with human Crohn's disease. Here we report the crystal structure of <i>pfi</i>T at 1.7Å resolution and provide a functional analysis of the interaction of <i>pfi</i>T and its homolog, PA2885, with human class II MHC. Both <i>pfi</i>T and PA2885 bound to mammalian cells and stimulated the proliferation of human lymphocytes. This binding was greatly inhibited by anti-class II MHC HLA-DR antibodies, and to a lesser extent, by anti HLA-DQ and DP antibodies, indicating that the binding was class II MHC-specific. GST-<i>pfi</i>T efficiently precipitated both endogenous and <i>in vitro</i> purified recombinant HLA-DR1 molecules, indicating that <i>pfi</i>T directly interacted with HLA-DR1. Competition studies revealed that <i>pfi</i>T and the superantigen <i>Mycoplasma arthritidis</i> mitogen (MAM) competed for binding to HLA-DR, indicating that their binding sites overlap. Structural analyses established that <i>pfi</i>T belongs to the TetR-family of DNA-binding transcription regulators. The distinct structure of <i>pfi</i>T indicates that it represents a new family of T cell superantigens.</p></div

Binding of <i>pfi</i>T and PA2885 to human PBMC is dependent on the class II MHC HLA-DR.

<p>(<b>A</b>) Analysis of binding of FITC-labeled control SAg MAM to CD19⁺ human lymphocytes, in the presence of various anti-class II MHC and control antibodies. (<b>B</b>) Binding profile of FITC-labeled <i>pfi</i>T to CD19⁺ human lymphocytes. (<b>C</b>) Binding profile of FITC-labeled PA2885 to CD19⁺ human lymphocytes.</p