Hirudin hirudin. Hirudin Hirudin is a naturally occurring peptide in the salivary glands of blood-sucking leeches (such as "Hirudo medicinalis") that has a blood anticoagulant property. This is fundamental for the leeches’ alimentary habit of hematophagy, since it keeps the blood flowing after the initial phlebotomy performed by the worm on the host’s skin. During his years in Birmingham and Edinburgh, John Berry Haycraft had been actively engaged in research and published papers on the coagulation of blood, and in 1884, he discovered that the leech secreted a powerful anticoagulant, which he named hirudin, although it was not isolated until the
DNA damage (naturally occurring) (or tolerance) are shown in this table. For a brief description of the steps in repair see DNA repair mechanisms or see each individual pathway. The schematic diagram indicates the roles of insufficient DNA repair in aging and cancer, and the role of apoptosis in cancer prevention. An excess of naturally occurring DNA damage, due to inherited deficiencies in particular DNA repair enzymes, can cause premature aging or increased risk for cancer (see DNA repair-deficiency disorder). On the other hand, the ability to trigger apoptosis in the presence of excess un-repaired DNA damage is critical for prevention of cancer. DNA