Residue at carbon 12 and a

12-Hydroxyeicosatetraenoic acid (12-HETE) is a derivative of the 20 carbon polyunsaturated fatty acid, arachidonic acid, containing a hydroxyl residue at carbon 12 and a 5Z,8Z,10E,14Z cis–trans configuration (Z=cis, E=trans) in its four double bonds. It was first found as a product of arachidonic acid metabolism made by human and bovine platelets through their 12S-lipoxygenase (i.e. ALOX12) enzyme(s). However, the term 12-HETE is ambiguous in that it has been used to indicate not only the initially detected \"S\" stereoisomer, 12S-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12(S)-HETE or 12S-HETE), made by platelets, but also the later detected \"R\" stereoisomer, 12(R)-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (also termed 12(R)-HETE or 12R-HETE) made by other tissues through their 12R-lipoxygenase enzyme, ALOX12B. The two isomers, either directly or after being further metabolized, have been suggested to be involved in a variety of human physiological and pathological reactions. Unlike hormones which are secreted by cells, travel in the circulation to alter the behavior of distant cells, and thereby act as endocrine signalling agents, these arachidonic acid metabolites act locally as autocrine signalling and/or paracrine signaling agents to regulate the behavior of their cells of origin or of nearby cells, respectively. In these roles, they may amplify or dampen, expand or contract cellular and tissue responses to disturbances.

Tietgensgade is a street in central Copenhagen, Denmark. It runs from H. C. Andersens Boulevard in the northeast to Kvægtorvgade at the Meat-Packing District in the southwest, linking Stormgade in the city centre with Ingerslevsgade and Halmtorvet/Sønder Boulevard in Vesterbro. The street follows the rear side of Tivoli Gardens and Copenhagen Central Station. The viaduct that carries it across the railway tracks at the central station is known as Tietgensbro. A series of staircases and lifts provides direct access from the viaduct to the station platforms.