Discovery and development of direct Xa inhibitors Xa was identified as a promising target for the development of new anticoagulants in the early 1980s. In 1987 the first factor Xa inhibitor, the naturally occurring compound antistasin, was isolated from the salivary glands of the Mexican leech "Haementeria officinalis". Antistasin is a polypeptide and a potent Xa inhibitor. In 1990 another naturally occurring Xa inhibitor was isolated, tick anticoagulant peptide (TAP) from extracts of the tick "Ornithodoros moubata". TAP and antistasin were used to estimate factor Xa as a drug target. Blood coagulation is a complex process by which the blood forms clots. It is an essential part
Naturally occurring retirement community Naturally occurring retirement community A naturally occurring retirement community (NORC; ) is a term used to describe a community that has a large proportion of residents over 60 but was not specifically planned or designed to meet the needs of seniors living independently in their homes. NORCs may develop in three different ways: The demographic term "NORC" was first coined in the 1980s by Michael Hunt, a professor of urban planning at the University of Wisconsin-Madison. He defined NORCs as neighborhoods and housing developments, originally built for young families, in which 50 percent of the residents are 60 years or