An antihistamine is a type of pharmaceutical drug that opposes the activity of histamine receptors in the body.Antihistamines are subclassified according to the histamine receptor that they act upon: the two largest classes of antihistamines are H1-antihistamines and H2-antihistamines.n H3-antihistamine is a classification of drugs used to inhibit the action of histamine at the H3 receptor. H 3 receptors are primarily found in the brain and are inhibitory autoreceptors located on histaminergic nerve terminals, which modulate the release of histamine.
U.S. Secret Service. U.S. Secret Service, federal law-enforcement agency within the United States Department of Homeland Security tasked with the criminal investigation of counterfeiting and other financial crimes. After the assassination of Pres.
For the first time in U.S. history, the nation had in the OSS a single intelligence service engaged in all basic secret activities: espionage, covert action, propaganda, and counterintelligence. The following article is the first in a series that will explore the different branches of the Office of Strategic Services. This article focuses on the Secret Intelligence Branch. When the OSS was created in 1942, its leader Gen. William J. Donovan had not intended for it to be an organization of spies.