Ariel Loewy died on February 13, 2001 of complications from an unexpected stroke. His passing is an immeasurable loss to his family and friends, and to his many academic and scientific colleagues around the world. Ariel was born in Bucharest, Romania on March 12, 1925. His family fled from the Nazis, first to England in 1936 and then to Canada in 1941. He received his B.Sc. and M.Sc. degrees in botany from McGill University in Montreal, and then came to the United States in 1948 to study at the University of Pennsylvania as a Harrison Fellow, where he obtained a Ph.D. in botany in 1951. Ariel carried out research as a National Institutes of Health fellow at Harvard University Medical School from 1950 to 1951, and as a National Research Council fellow at the University of Cambridge from 1952 to 1953. He returned to the United States to accept a faculty position in the Biology Department at Haverford College, where he remained until 2000. From 1983 to 1995, he held the Jack and Barbara Bush Professorship in the Natural Sciences. Ariel then became a Research Professor for five years, until he left Haverford College in June 2000 to join the Department of Pathology, Microbiology, and Immunology at the Philadelphia College of Osteopathic Medicine as an Adjunct Professor.

Ariel Loewy’s early research focused on the cell biology and biochemistry of non-muscle motility. Ariel's research career spanned fifty years, much of it devoted to studies of the factor XIII enzyme and the formation of isopeptide bonds in thrombosis. This work started during his time as a NIH Fellow at Harvard University. Ariel first identified factor XIII as a key element in the process of blood coagulation. His continuing work revealed for the first time the enzymatic nature of factor XIII and he characterized its transglutaminase crosslinking function. Ariel also developed purification techniques that are still used today, which enabled the production of factor XIII for treatment of clotting disorders.. Ariel's interest in factor XIII eventually extended to the isopeptidase enzyme, which hydrolyses the isopeptide bonds formed by factor XIII and other members of itstransglutaminase family. Most recently, his isopeptidase research focused on the disruption of the neurofibrillary tangles in the brain that cause symptoms of dementia in Alzheimer's disease and to the characterization of isopeptidase activity in biological tissues. At 75, Ariel was still very active; he was lead author in a review chapter on factor XIII published earlier this year and recently submitted a manuscript describing the role of erythrocytes in blood clot dissolution. This research is continued by his collaborators at the Philadelphia College of Osteopathic Medicine.

Ariel Loewy has served as an editor of the journal Thrombosis Research, on the Advisory Board of Biochemistry and Sigma Xi, and was referee in a number of study sections for the National Institutes of Health and National Science Foundation. His research efforts earned him the James P. Mitchell Foundation Award for Heart and Vascular Research in 1973 and recognition at the Third International Conference on Factor XIII in 1995. He was further awarded the Glenn Foundation Award for Outstanding Research in Aging at the 6th International Congress on Cell Biology and the 36th American Society for Cell Biology Annual Meeting in 1996.

Ariel was a devoted and passionate teacher. As Chairman of the Department of Biology, Ariel played a central role in its growth and development and was a key figure in the College leadership. He obtained a National Institutes of Health training grant for the Department, one of only three such grants given to undergraduate institutions. The funding allowed Ariel and his colleagues to develop the first undergraduate curriculum in the United States to focus primarily on molecular and cellular biology. This program integrated productive research with intensive teaching at the undergraduate level and became a model for undergraduate institutions, bringing Haverford College national recognition. Ariel's commitment to teaching led to his co-authoring two widely used biology textbooks for college undergraduates: "Cell Structure and Function" and "Biology”, former being the first textbook on cell biology. Both volumes have been translated into numerous foreign languages.

Ariel stood out for his creative non-dogmatic thinking in science, and for his special encouragement of young scientists. He influenced thousands of students who got their start in biology at Haverford College and mentored hundreds who worked with him in the lab or met him at scientific meetings. His genuine warmth and friendship stimulated many close friendships. Ariel's relentless inquisitive spirit and his dedication to encourage the same in his students made him the quintessential teacher-scholar. He developed a new focus on cell biology in undergraduate education.

Ariel's former students remember with genuine fondness and admiration their experiences with him at Haverford. Students were taught more than mere bench technique; Ariel impressed on us the intellectual coherence, rigour and inexorable honesty of experimental science. Undergraduate research in the Loewy laboratory was an unforgettable experience. We came to regard Ariel as not only a scientific mentor, but also a man of principle to whom one could freely turn for advice. Ariel's relationships with his students often evolved to close, respectful, warm and caring friendships. His laboratory provided an exhilarating introduction to real experimental science and inspired many to pursue research careers. Ariel's legacy lives on in these former students who model their research groups in part on their memories of the enchanted Loewy laboratory.

It was always an enjoyable experience for scientific colleagues to meet with Ariel at conferences. We remember him for his insightful and provocative discussions, and far-ranging conversations filled with humor and affection. He was especially open and gracious to newcomers in the transglutaminase field, often by inviting them for seminar visits to Haverford.

Ariel had a thoughtful charm and an infectious pleasure in sharing and exploring ideas that will be sorely missed. Ariel's sense of justice was an inspiration to his friends; he was an active and vocal proponent of peace and civil and human rights. His life was a broad, passionate inquiry into knowledge and philosophy: an extended conversation with Ariel could wander through unanticipated scientific, cultural, and political terrain. His passion for music has been passed on and shared by most of his family and many friends. He was famous for his love of food and cooking and for sharing stories and jokes with friends and colleagues. We admired and loved Ariel for his scholarship and humanity.

Ariel leaves his wife Martha and five children; the sons Michael, Andy and Daniel, and the daughters Eva and Ridley. He will be dearly missed by them, and by many scientific colleagues who are honored to call themselves his friends.


Vivien C. Yee, Cleveland Clinic Foundation, Ohio
John Weisel, University of Pennsylvania, Pennsylvania
David C. Teller, University of Washington, Washington
H. Ronald Kaback, University of California, Los Angeles and Howard Hughes Medical Institute, California
Jonathan Gallant, University of Washington, Washington
James E. Dahlberg, University of Wisconsin-Madison, Washington
Albert Dahlberg, Brown University, Rhode Island


Selected References

1. Loewy AG and Edsall JT. Studies on the formation of urea-insoluble fibrin. J. Biol.Chem. 1954; 211:829.
   
2. Loewy AG, Veneziale C, and Forman, M. Purification of the factor involved in the formation of the urea-insoluble fibrin. Bichem. Biophys. Acta. 1957; 26:670.
   
3. Loewy AG, Dunathan K, Kreil R, and Wolfinger HL Jr. Fibrinase. I. Purification of substrate and enzyme. J. Biol. Chem. 1961; 236:2625-2633.
   
4. Loewy AG, Dahlberg A, Dunathan K, Kreil R, and Wolfinger HL Jr. Fibrinase. II. Some physical properties. J. Biol. Chem. 1961; 236:2644-2647.
   
5. Loewy AG, Dunathan K, Gallant JA, and Gardner B. Fibrinase. III. Some enzymatic properties. J. Biol. Chem. 1961; 236:2644-2647.
   
6. Loewy AG, Gallant JA, and Dunathan K. Fibrinase. IV. Effect on fibrin stability. J. Biol. Chem. 1961; 236:2648-2654.
   
7. Loewy AG and Siekevitz P. Cell Structure and Function, 1st Edition. New York: Holt, Rinehart & Winston; 1963.
   
8. Loewy AG Fibrinase (Factor XIII). Thromb. Diath. Haemorrh. 1963; 13:109.
   
9. Loewy AG, Dahlberg JE, Dorwart WC, Weber MJ, and Eisele J. A transamidase mechanism for insoluble fibrin formation. Biochem. Biophys. Res. Comm. 1964; 15:177-181.
   
10. Loewy AG, Matacic S, and Darnell JH. Transamidase activity of the enzyme responsible for insoluble fibrin formation. Arch. Biochem. Biophys. 1966; 113:435-438.
    
11. Matacic S and Loewy AG. Transglutaminase actiivty of the fibrin crosslinking enzyme. Biochem. Biophys. Res.Commun. 1966; 24:858-866.
    
12. Loewy AG. Enzymatic control of insoluble fibrin formation. In: Laki K, editor. Fibrinogen. New York: Marcel Dekker; 1968. p. 185-223.
    
13. Loewy AG and Siekevitz P. Cell Structure and Function, 2nd Edition. New York: Holt, Rinehart & Winston; 1968.
    
14. Loewy AG. Wirkungsmechanismus des Faktors XIII. Thromb. Diath. Haemorrh. 1968; 28:1.
    
15. Matacic S and Loewy AG. The identification of isopeptide crosslinks in insoluble fibrin. Biochem. Biophys. Res. Commun. 1968; 30:356-362.
    
16. Loewy AG. A theory of covalent bonding in muscle contraction. J. Theor. Biol. 1968; 20:164-172.
    
17. Loewy AG. Mechanism of factor XIII. Thromb. Diath. Haemorrh. 1969; Suppl. 28:1-12.
    
18. Loewy AG. Mechanism of fibrin cross-linkage. Some historical remarks of uncertain objectivity. Thromb. Diath. Haemorrh. 1970; 23:103.
    
19. Dvilansky A, Britten AF, and Loewy AG. Factor XIII assay by an isotope method. I. Factor XIII (transamidase) in plasma serum, leucocytes, erythrocytes and platelets and evaluation of screening tests of clot solubility. Br. J. Haematol. 1970; 18:399-410.
    
20. Dvilanski A, Britten AF, and Loewy AG. Factor XIII assay by an isotope method. II. Heparin inhibition of factor XIII activation. Thromb. Diath. Haemorrh. 1970; 24:256-264.
    
21. Loewy AG. Biological motility, the conversion of chemical energy into work. In: Dethier VG et al, editors. Topics in the Study of Life. New York: Harper & Row; 1971.
    
22. Loewy AG. Some thoughts on the state in nature, biosynthetic origin, and function of factor XIII. Ann. N.Y. Acad. Sci. 1972; 202:41-58.
    
23. Ebert JD, Loewy AG, Miller RS, and Schneiderman HA. Biology. New York: Holt, Rinhart & Winston; 1973.
    
24. Birckbichler PJ, Dowben RM, Matacic S, and Loewy AG. Isopeptide bonds in membrane proteins from eukaryotic cells. Biochim. Biophys. Acta. 1973; 291:149-155.
    
25. Kessler D, Nachmias VT, and Loewy AG. Actomyosin content of Physarum plasmodia and detection of immunological cross-reactions with myosins from related species. J. Cell Biol. 1976; 69:393-406.
    
26. Matacic SS and Loewy AG. Presence of the N-episilon-(g-glutamic)lysine crosslink in cellular proteins. Biochem. Biophys. Acta. 1979; 176:263-268.
    
27. Matacic SS and Loewy AG. Modulation of the e-(g-glutamic)lysine cross-link in cellular proteins. Biochim. Biophys. Acta. 1979; 576:263-268.
    
28. Loewy AG and Matacic SS. Modulation of the e-(g-glutamic)lysine cross-link in cellular proteins. I. In vivo and in vitro studies. Biochim. Biophys. Acta. 1981; 668:167-176.
    
29. Loewy AG, Matacic SS, Rice P, and Stern J. Modulation of the e-(g-glutamic)lysine cross-link in cellular proteins. II. Fractionation studies. Biochim. Biophys. Acta. 1981; 668:177-185.
    
30. Loewy AG, Wilson FJ, Taggart NM, Green EA, Frasca P, Kaufman HS, and Sorrell MJ. A covalently cross-linked matrix in skeletal muscle fibers. Cell Motil. 1983; 3:463-483.
    
31. Loewy AG. Properties of a transcellular matrix in muscle cells. In: Oplatka A, editor. Biological Structure and Coupled Flows. New York: Academic Press; 1984.
    
32. Loewy AG. The N-e-(g-glutamic)lysine cross-link: method of analysis, occurrence in extracellular and cellular proteins. Meth. Enzymol. 1984; 107:241-257.
    
33. Loewy AG, Wilson FJ, Taggart NM, Kaufman HS, Northrop JL, Greene EA, and Frasca P. Studies of a covalently-crosslinked matrix in skeletal muscle fibers. Proc. NY Acad. Sci. 1985; 455:699-702.
    
34. Loewy AG. From fibrin to intracellular matrices. In: Musbek L, editor. Hemostasis and Cancer. Boca Raton: CRC Press; 1987.
    
35. Loewy AG, Dollahon N, Klainer P, and Wolfe K. An insoluble matrix of the nerve cytoskeleton. Protoplasma, 1988; [Suppl 2]:137-144.
    
36. Loewy AG, Siekevitz P, Gallant J, and Menninger JR. Cell Structure and Function, 3rd Edition. Philadelphia: Saunders College Publishing; 1991.
    
37. Harsfalvi J, Fesus L, Tarcsa E, Laczko J, and Loewy AG. The presence of a covalently cross-linked matrix in human platelets. Biochim. Biophys. Acta. 1991; 1073:268-274.
    
38. Loewy AG and Santer UV. A simple, economic in vitro fibrinolysis rate assay. Thromb. Res. 1992; 68:201-204.
    
39. Loewy AG, Santer UV, Wieczorek M, Blodgett JK, Jones SW, and Cheronis JC. Purification and characterization of a novel zinc-proteinase from cultures of Aeromonas hydrophila. J. Biol. Chem. 1993; 268:9071-9078.
    
40. Loewy AG, Santer UV, Wieczosek M, Blodgett J, Jones S, and Cheronis J. Regarding the reversal of N-episolon(g-glutamic)lysine crosslink formation. In: Factor XIII. Stuttgart-NY: Schattauer; 1993.
    
41. Loewy AG, Blodgett JK, Blasé FR, and May MH. Synthesis and use of a substrate for the detection of isopeptidase activity. Anal. Biochem. 1997; 246:111-117.
    
42. Balin BJ, Loewy AG, and Appelt DM. Analysis of transglutaminase-catalyzed isopeptide bonds in paired helical filaments and neurofibrillary tangles from Alzheimer's disease. Meth. Enzymol. 1999; 309:172-186.
    
43. Loewy AG, McDonagh J, Mikkola H, Teller DC, and Yee VC. Structure and Function of Factor XIII. In: Colman RW et al, editors. Hemostasis and Thrombosis, Fourth Edition. Philadelphia: Lippincott Williams & Wilkins; 2001.