Discovery and development of direct thrombin inhibitors the binding site for the globular amino-terminal domain and exosite 1 is the binding site for the acidic carboxy-terminal domain of hirudin. Native hirudin, a 65-amino-acid polypeptide, is produced in the parapharyngeal glands of medicinal leeches. Hirudins today are produced by recombinant biotechnology using yeast. These recombinant hirudins lack a sulfate group at Tyr-63 and are therefore called desulfatohirudins. They have a 10-fold lower binding affinity to thrombin compared to native hirudin, but remain a highly specific inhibitor of thrombin and have an inhibition constant for thrombin in the picomolar range. Renal clearance and degradation account for the most 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