Search the Health Library
Get the facts on diseases, conditions, tests and procedures.
I Want To...
I Want To...
Find Research Faculty
Enter the last name, specialty or keyword for your search below.
School of Medicine
Daniel Nyhan, M.B.B.Ch., M.D.
Director of Cardiac Anesthesia Division
Professor of Anesthesiology and Critical Care Medicine
Research Interests: Vascular Aging, Underlying Mechanisms
Request an Appointment
I live in Maryland
Request an appointment through My
I live outside of Maryland
I live outside of the United States
The Johns Hopkins Hospital
Appointment Phone: 410-955-7519
600 N. Wolfe Street
Sheikh Zayed Tower Suite 711
Baltimore, MD 21287 map
Dr. Daniel Nyhan is a professor of anesthesiology and critical care medicine and an associate professor of surgery at the Johns Hopkins University School of Medicine. Dr. Nyman serves as the director of the Cardiac Anesthesia Division and fellowship director of cardiac anesthesia at the Department of Anesthesiology and Critical Care Medicine. He''s also executive vice chairman of the department.
Dr. Nyhan received his B.Sc. degree in physiology and his M.B., B.Ch., B.A.O. (honors degree) from the University College Cork – National University of Ireland, Cork. He completed his residency at Johns Hopkins. He performed a fellowship in the Division of Cardiac Anesthesia at Johns Hopkins and a research fellowship in the Department of Anesthesiology and Critical Care Medicine at Johns Hopkins. Dr. Nyhan joined the Johns Hopkins faculty in 1987.
Prior to joining Johns Hopkins, Dr. Nyhan was an instructor of life sciences at Regional College in Cork, Ireland, and an instructor of physiology at University College Cork–National University of Ireland, Cork.
Dr. Nyhan's research interests include the underlying mechanisms of vascular aging.
He serves on the editorial board of the Journal of Cardiothoracic and Vascular Anesthesia and is a reviewer for the Anesthesiology journal. He is a member of the Faculty Senate at Johns Hopkins. He is a member of several professional organizations, including the American Society of Anesthesiologists and the Association of Cardiovascular Anesthesiologists.
- Director of Cardiac Anesthesia Division
- Executive Vice Chairman, ACCM, The Johns Hopkins University School of Medicine
- Professor of Anesthesiology and Critical Care Medicine
- Associate Professor of Surgery
- MD, Faculty Of Medicine National University (1979)
- Johns Hopkins University School of Medicine / Anesthesiology and Critical Care Medicine (1985)
- American Board of Anesthesiology / Anesthesiology (1986)
Research & Publications
Dr. Nyhan is interested in studying the vascular changes that accompany aging, determining the underlying causes and finding ways to reverse the process. With Dr. Dan Berkowitz, he uses a technique based on wave-form analysis to determine the rate at which a pulse wave is transmitted and reflected. The stiffer the blood vessel, the more quickly the pulse wave travels. In a clinical study, they found that not only do noncompliant blood vessels reduce cardiovascular function; the condition results in poorer outcome after cardiac surgery.
Drs. Nyhan and Berkowitz, with their colleague Dr. Artin Shoukas, are trying to determine the factors that mediate vascular stiffness. They are researching the effect of an enzyme known as arginase-II, found in the endothelial cells that line blood vessels. The amino acid arginine is required for the production of nitric oxide (NO) by nitric oxide synthase (NOS). NO is a critical molecule for the relaxation of vascular smooth muscle, and hence, vasorelaxation. However, arginase competes with NOS for the utilization of arginine; an elevation in arginase could lead to decreased production of NO and stiffer blood vessels.
In a recent study, their laboratory found that arginase inhibition improved NO production and decreased vascular stiffness in a preclinical model of atherosclerosis. Additional benefits were decreased production of reactive oxygen species and a decrease in total cholesterol plaque burden. Currently, researchers are trying to develop an inhibitor of arginase that can be used clinically.
Dr. Nyhan finds it highly gratifying to have the opportunity to work clinically and in the laboratory, and to see the relevance of each to the other. His hope is that in the future, this work in vascular biology will lead to new ways to improve vascular compliance and thereby improve cardiovascular function and perioperative risk.
Publications Since 2006
- White AR, Ryoo SW, Li D, Champion HC, Steppan J, Wang D, Nyhan D, Shoukas AA, Hare JM, Berkowitz DE. Knockdown of arginase 1 restores NO signaling in the vasculature of old rats. Hypertension 2006; 47:245-251.
- Gao WD, Da T, Nyhan D. Increased cross-bridge cycling rate in stunned myocardium. Am J Physiol Heart Circ Physiol 2006;290:H866-H893.
- Steppan J, Ryoo S, Schuleri KH, Gregg C, Hasan RK, White AR, Bugaj LJ, Khan M, Santhanam L, Nyhan D, Shoukas A, Hare J, Berkowitz DE. Arginase modulates myocardial contractility by a nitric oxide synthase-1 dependent mechanism. PNAS USA. 2006;103:4759-4764.
- Ryoo S, Lemmon C, Soucy KG, Gupta G, White AR, Nyhan D, Shoukas A, Romer LH, Berkowitz DE. Oxidized low-density lipoprotein-dependent endothelial arginase Hi activation contributes to impaired nitric oxide signaling. Circ Res. 2006;99: 951-960.
- Soucy KG, Ryoo S, Benjo A, Lim HK, Gupta G, Sohi JS, Elser J, Aon MA, Nyhan D, Shoukas AA, Berkowitz DE. Impaired shear stress-induced nitric oxide production through decreased NOS phosphorylation contributes to age-related vascular stiffeness. JAppI Physiol 2006;101:1751-1759.
- Lim HK, Lim HK, Ryoo S, Benjo A, Shuleri K, Miriel V, Baraban E, Camara A, Soucy K, Nyhan D, Shoukas A, Berkowitz DE. Mitochondrial arginase II constrains endothelial NOS-3 activity. AJP-Heart, Lung, Physiol. 2007;93:H3317-H3324.
- Berkowitz DE, Nyhan D. Critical role of the alpha-1 B adrenoreceptors in sympathetically-mediated pressor and contractile responses to hypotension. Circulation. In Review.
- Benjo A, Thompson RE, Fine D, Hogue CW, Alejo D, Kaw A, Gerstenblith G, Shah A, Berkowitz DE, Nyhan D. Pulse pressure predicts stroke development and acute renal failure after cardiac surgery. Hypertension. 2007;50:630-635.
- a. Tuday EC, Meek JV, Nyhan D, Shoukas AA, Berkowitz DE. Microgravity-induced changes in aortic stiffness and their role in orthostatic intolerance, J Appl Physiol, 2007;102:853-858. 9B.Associated Editorial: to be published in J Appl Physiol 2007;103:1-2.
- Santhanam L, Lim HK, Lim HK, Miriel V, Brown T, Patel M, Balanson S, Ryoo S, Anderson M, Irani K, Khanday F, Di Costanzo L, Nyhan D, Hare JM, Christianson DW, Rivers R, Shoukas A, Berkowitz DE. Inducible NO synthase dependent S-nitrosylation and activation of arginasel contributes to age-related endothelial dysfunction. Circ Res. 2007;101:692-702.
- Lim HK, Lim HK, Ryoo S, Benjo A, Shuleri K, Miriel V, Baraban E, Camara A, Soucy K, Nyhan D, Shoukas A, Berkowitz DE. Mitochondrial arginase II constrains endothelial NOS-3 activity. AJP - Heart, Circ Physiol. 2007;293:H3317-H3324.
- Ryoo S, Gupta G, Benjo A, Lim HK, Camara A, Sikka G, Lim HK, Sohi J, Santhanam L, Soucy K, tuday E, Baraban E, Hies M, Gerstenblith G, Nyhan D, Shoukas A, Christianson DW, Alp NJ, Champion HC, Huso D, Berkowitz DE. Endothelial arginase II: a novel target for the treatment of atherosclerosis, Circ Res. Circ Res. 2008;102:923-943.
- Tuday EC, Nyhan D, Shoukas AA, Berkowitz DE. Microgravity induced changes in aortic stiffness and its role in orthostatic intolerance, J Appl Physiol, 2007;102:853-858.
- Nyhan D, Berkowitz DE. Perioperative blood pressure management: does central vascular stiffness matter? Anesth Analg. 2008;107:1103-1106.
- Jandu SK, Webb AK, Pak A, Sevinc B, Nyhan D, Belkin AM, Flavahan NA, Berkowitz DE, Santhanam L. "Nitric oxide regulates tissue transglutaminase localization and function in the vasculature." Amino Acids. 2013 Jan;44(1):261-9. doi: 10.1007/s00726-011-1090-0. Epub 2011 Oct 8.
- Khan M, Steppan J, Schuleri KH, Ryoo S, Tuday E, Bugaj L, Santhanam L, Berkowitz T, Nyhan D, Shoukas AA, Berkowitz DE. "Erratum to: Upregulation of arginase-II contributes to decreased age-related myocardial contractile reserve." Eur J Appl Physiol. 2012 Dec;112(12):4189.
- Barodka V, Nyhan D, Berkowitz D. "About fACE: perioperative use of angiotensin-converting enzyme inhibitors." Circulation. 2012 Jul 17;126(3):249-51. doi: 10.1161/CIRCULATIONAHA.112.117671. Epub 2012 Jun 19.
- Khan M, Steppan J, Schuleri KH, Ryoo S, Tuday E, Bugaj L, Santhanam L, Berkowitz T, Nyhan D, Shoukas AA, Berkowitz DE. "Upregulation of arginase-II contributes to decreased age-related myocardial contractile reserve." Eur J Appl Physiol. 2012 Aug;112(8):2933-41. doi: 10.1007/s00421-011-2257-9. Epub 2011 Dec 8.
- Tuday E, Platts S, Nyhan D, Shoukas AA, Berkowitz DE. "A retrospective analysis on gender differences in the arterial stiffness response to microgravity exposure." Gravitational and Space Biology. 2011;25:51-53.
Chapters and Reviews since 2006
- Grogan K, Nyhan D, Berkowitz DE. Pharmacology of anesthetic drugs. IN: Cardiac Anesthesia; 5th Edition. JA Kaplan, D Reich, S Konstade, C Lake, eds. Elsevier/Saunders, New York, 2006. Chap 9, pp 165-212.
- Nyhan D, BlanckTJJ. Cardiac physiology. IN: Mechanisms of Anesthetic Action, 2nd Edition. IN: Basic and Applied Science for Anesthesia. HC Hemmings, Jr., PM Hopkins, eds. CV Mosby, London; Chapter 39.
- Steppan J, Berkowitz DE, Martinez E, Nyhan D. Diastolic heart function and the elderly. IN: Aging and Anesthesia. F Sieber, ed. McGraw-Hill, Philadelphia, Chapter 16, 2006.
- Simmonds P, Nyhan D, Berkowitz DE. Cardiovascular pharmacological agents. IN: The Johns Hopkins Manual of Cardiac Surgical Care, 2nd Edition. Eds. JV Conte, WA Baumgartner, SG Owens, T Dorman. Elsevier, Philadelphia, PA. Chapter 2, 2008.
- Dorman T, Nyhan D. Postoperative hemodynamic management. IN: The Johns Hopkins Manual of Cardiac Surgical Care, 2nd Edition. Eds. JV Conte, WA Baumgartner, SG Owens, T Dorman. Elsevier, Philadelphia, PA. Chapter 9, 2008.
- Grogan K, Nyhan D, Berkowitz D. Pharmacology of anesthetic drugs. IN: Cardiac Anesthesia, &h Edition. JA Kaplan, D Reich, S Konstade, C Lake, eds. Elsevier/Saunders, New York. Chapter 7, 2008.
Activities & Honors
- Merel Harmel Resident of the Year, The Johns Hopkins University School of Medicine, 1984
- College Scholar, University College Cork - National University of Ireland, 1977
- Welcome Trust Medical Scholarship, Medical Research Council, 1975
- Henry Hutchinson Scholarship, National University of Ireland, 1975
- American Heart Association
- American Society of Anesthesiologists
- Association of Cardiovascular Anesthesiologists
- Association of University Anesthesiologists
- Council on Circulation Research
- Maryland/DC Society of Anesthesiologists
- Royal College of Physicians of Ireland
- Society for Cardiovascular Anesthesia
- ACCM Representative, Johns Hopkins University School of Medicine, 2009
Medical School Council/Faculty of Senate
- ACCM Representative, Johns Hopkins University School of Medicine, 2007
Clinical Practice Association
- Chair, ACCM Associate Professor’s Faculty Development/Mentoring Committee, 2007
- Chairman, Johns Hopkins University School of Medicine, 1991 - 1997
Cardiac Service Quality/Assurance Committee
- Departmental Residency Recruitment/Interview Committee, Johns Hopkins University School of Medicine, 1988
Department of Anesthesiology and Critical Care Medicine
- Editorial board, Journal of Cardiothoracic and Vascular Anesthesia
- Education Committee, Society for Cardiovascular Anesthesia, 1998 - 2000
- Institutional Cardiovascular Task Force, Johns Hopkins University School of Medicine, 1991 - 1997
Videos & Media
Lectures and Presentations
State of the Department
Research Sponsored Grand Rounds , http://webcast.jhu.edu/Mediasite/Play/1016ba76137645a6bba47617c36e6af41d (07/03/2014)
Stiff Pipes: Pathobiology and Consequence of Vascular Aging
Grand Rounds , http://webcast.jhu.edu/Mediasite/Play/be3340a92c564b648fedf5cd0db8607e1d (08/15/2013)