This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'platelet activating factor causes all except: \nSelect and explain. \nA. Vasoconstriction, B. Bronchodilation, C. Causes platelet aggregation, D. transmits signals between cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: PAF is another phospholipid derived mediator having the following inflammatory effects: Platelet aggregation Vasoconstriction Bronchoconstriction At extremely low concentration, it may cause vasodilation and increased venular permeability Increases leukocyte adhesion to the endothelium (by enhancing integrin-mediated leukocyte binding), chemotaxis, degranulation, and the oxidative burst. Stimulates the synthesis of other mediators, paicularly eicosanoids, by leukocytes and other cells. ref robbins 9/e page 89', 'role': 'assistant'}]