WBR0739

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Physiology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A researcher is studying the role of a new medication for the prophylaxis against myocardial infarction. He explains that the medication acts on the arachidonic acid pathway and counteracts atherosclerosis by increasing compounds that inhibit platelet aggregation that is known to play a major role in the pathogenesis of coronary artery disease. According to the diagram below, the new medication most likely promotes which part of the pathway to achieve its therapeutic effect? File:WBR Arachidonic Pathway Adapted.png]]
Answer A	AnswerA::A
Answer A Explanation	AnswerAExp::LTB4 is a neutrophil chemotactic agent. It does not play a major role in preventing platelet aggregation.
Answer B	AnswerB::B
Answer B Explanation	AnswerBExp::LTC4 and LTD4 are pro-inflammatory agents that play a role in bronchoconstriction.
Answer C	AnswerC::C
Answer C Explanation	AnswerCExp::Prostacyclin is a major inhibitor of platelet aggregation.
Answer D	AnswerD::D
Answer D Explanation	AnswerDExp::Prostaglandins increase uterine tone, which may be utilized in pregnancy to induce labor. Prostaglandins also lower vascular and bronchial tone.
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::Thromboxane A2 has an opposing effect to prostacyclin. It increases platelet aggregation and plays a role in worsening atherosclerosis.
Right Answer	RightAnswer::C
Explanation	[[Explanation::The medication described must have properties that lower platelet aggregation to counteract the process of myocardial infarction that promotes platelet aggregation. Prostacyclin (PGI2) is a potent inhibitor of platelet aggregation; it also promotes vasodilation, bronchodilation, and decreases uterine tone. Since the medication increases compounds that inhibit platelet aggregation, the new compound must thus increase PGI2 and thus promote inhibition of platelet aggregation. Educational Objective: Prostacyclin inhibits platelet aggregation. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::arachidonic, WBRKeyword::acid, WBRKeyword::pathway, WBRKeyword::lipoxygenase, WBRKeyword::cycloxygenase, WBRKeyword::platelet, WBRKeyword::aggregation, WBRKeyword::prostacyclin, WBRKeyword::PGI2, WBRKeyword::thromboxane, WBRKeyword::inhibitor, WBRKeyword::inhibition, WBRKeyword::therapeutic, WBRKeyword::effect, WBRKeyword::effects, WBRKeyword::increase, WBRKeyword::decrease, WBRKeyword::atherosclerosis, WBRKeyword::myocardial, WBRKeyword::infarction, WBRKeyword::MI
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::