R
Richard Hajdu
Researcher at Merck & Co.
Publications - 34
Citations - 4248
Richard Hajdu is an academic researcher from Merck & Co.. The author has contributed to research in topics: Receptor & Agonist. The author has an hindex of 24, co-authored 34 publications receiving 4065 citations. Previous affiliations of Richard Hajdu include United States Military Academy.
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Journal ArticleDOI
Alteration of lymphocyte trafficking by sphingosine-1-phosphate receptor agonists.
Suzanne M. Mandala,Richard Hajdu,James D. Bergstrom,Elizabeth J. Quackenbush,Jenny Xie,James A. Milligan,Rosemary A. Thornton,Gan-Ju Shei,Deborah Card,CarolAnn Keohane,Mark Rosenbach,Jeffrey J. Hale,Christopher L. Lynch,Kathleen M. Rupprecht,William H. Parsons,Hugh Rosen +15 more
TL;DR: It is shown that lymphocyte trafficking is altered by the lysophospholipid sphingosine-1-phosphate (S1P) and by a phosphoryl metabolites of the immunosuppressive agent FTY720.
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Mice Deficient in Sphingosine Kinase 1 Are Rendered Lymphopenic by FTY720
Maria L. Allende,Teiji Sasaki,Hiromichi Kawai,Ana Olivera,Yide Mi,Gerhild van Echten-Deckert,Richard Hajdu,Mark Rosenbach,Carol Ann Keohane,Suzanne M. Mandala,Sarah Spiegel,Richard L. Proia +11 more
TL;DR: The results with these Sphk1 null mice reveal that some key physiologic processes that require S1P receptor signaling, such as vascular development and proper lymphocyte distribution, can occur in the absence of SPHK1.
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Immune Cell Regulation and Cardiovascular Effects of Sphingosine 1-Phosphate Receptor Agonists in Rodents Are Mediated via Distinct Receptor Subtypes
Michael J. Forrest,S.-Y. Sun,Richard Hajdu,James D. Bergstrom,Deborah Card,George A. Doherty,Jeffrey J. Hale,Carol Ann Keohane,C. Meyers,James A. Milligan,Sander G. Mills,N. Nomura,Hugh Rosen,Mark Rosenbach,G.-J. Shei,I. I. Singer,M. Tian,S. West,V. White,Jenny Xie,Richard L. Proia,Suzanne M. Mandala +21 more
TL;DR: Three lines of evidence link S1P3 receptor activity with acute toxicity and cardiovascular regulation: compound potency on S 1P3 correlated with toxicity and bradycardia; the shift in potency of phosphorylated-FTY720 for inducing lymphopenia versus brady Cardia and hypertension was consistent with affinity for S1 p1 relative to S1p3; and toxicity, brady cardia, and hypertension were absent in S1 P3-/- mice.
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Metabolism of Thienamycin and Related Carbapenem Antibiotics by the Renal Dipeptidase, Dehydropeptidase-I
TL;DR: The reduction in clearance of THM and MK0787 from plasma of rats and rabbits after ligation of renal arteries indicate that the kidneys are responsible for 35 and 92%, respectively, of metabolic drug clearance, and despite this unusual degree of metabolism localized in the kidney, the plasma half-life of MK 0787 and its efficacy against experimental systemic infections in animals remain satisfactory.
Journal ArticleDOI
Preliminary animal pharmacokinetics of the parenteral antifungal agent MK-0991 (L-743,872).
Richard Hajdu,R Thompson,Jon G. Sundelof,Barbara A. Pelak,Frances Aileen Bouffard,James F. Dropinski,Helmut Kropp +6 more
TL;DR: Single daily doses of MK-0991 should provide adequate systemic levels of fungicidal activity as a result of its long half-life pharmacokinetics, wide distribution, and slowly accumulating concentrations in tissue.