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
Salivary gland therapy may impair salivary flow. Radiotherapy can cause permanent hyposalivation due to injury to the oral mucosa containing the salivary glands, resulting in xerostomia, whereas chemotherapy may cause only temporary salivary impairment. Graft versus host disease after allogeneic bone marrow transplantation may manifest as dry mouth and many small mucoceles. Salivary gland tumours may occur, including mucoepidermoid carcinoma, a malignant growth. A sialogram is a radiocontrast study of a salivary duct that may be used to investigate its function and for diagnosing Sjögren syndrome. The salivary glands of some species are modified to produce proteins - salivary amylase is found