Contribution of the platelet activating factor signaling pathway to cerebral microcirculatory dysfunction during experimental sepsis by ExoU producing Pseudomonas aeruginosa.

Intravital microscopy was used to assess the involvement of ExoU, a Pseudomonas aeruginosa cytotoxin with phospholipase A2 activity, in dysfunction of cerebral microcirculation during experimental pneumosepsis. Cortical vessels from mice intratracheally infected with low density of the ExoU-producing PA103 P. aeruginosa strain exhibited increased leukocyte rolling and adhesion to venule endothelium, decreased capillar density and impaired arteriolar response to vasoactive acetylcholine.

Arginase-1 expression in granulomas of tuberculosis patients.

Mycobacterium tuberculosis (Mtb) is an intracellular pathogen able to survive and multiply within macrophages. Several mechanisms allow this bacterium to escape macrophage microbicidal activity. Mtb may interfere with the ability of mouse macrophages to produce antibactericidal nitric oxide, by inducing the expression of arginase 1 (Arg1).