Jay McLean

Bedeutung für die Hirudotherapie

Jay McLean's contribution to hirudotherapy is the parallel-historical role his 1916 discovery played in establishing the second naturally-occurring anticoagulant principle of biological origin, parallel to John Berry Haycraft's 1884 isolation of hirudin from the medicinal leech. Working as a second-year medical student in William Henry Howell's physiology laboratory at Johns Hopkins, McLean isolated from canine hepatic and cardiac tissues an anticoagulant activity that Howell subsequently characterized and named heparin in 1918. The McLean-Howell-heparin lineage and the Haycraft-hirudin lineage together established the two foundational naturally-occurring anticoagulant principles of modern pharmacology: one from a parasitic invertebrate, the other from mammalian connective tissue. The subsequent twentieth-century pharmaceutical development of these two lineages diverged for several decades. Heparin was rapidly developed into a clinically-used parenteral anticoagulant in the late 1930s and 1940s and became the dominant anticoagulant of mid- and late-twentieth-century clinical medicine. Hirudin, by contrast, remained primarily a research tool and a biochemical curiosity until the late-twentieth-century recombinant-DNA era, when the cloning of the hirudin gene enabled the development of lepirudin, desirudin, and ultimately the synthetic direct thrombin inhibitor bivalirudin. The two lineages have since converged in the modern anticoagulant-pharmacology field. The American Society of Hirudotherapy regards Jay McLean as the discoverer of the principal mammalian-origin parallel to the leech-derived hirudin tradition. The historical question of credit between McLean (who isolated the activity) and Howell (who characterized and named the substance) has been the subject of considerable medical-historical debate; ASH regards the historical record as supporting both McLean's role in the original observation and Howell's role in the subsequent characterization, in a manner closely paralleling the broader history of biomedical discovery in which student-investigator-supervisor credit allocations are frequently complex.