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Oxidative Medicine and Cellular Longevity
Volume 2015, Article ID 839748, 7 pages
http://dx.doi.org/10.1155/2015/839748
Research Article

Insulin Therapy of Nondiabetic Septic Patients Is Predicted by para-Tyrosine/Phenylalanine Ratio and by Hydroxyl Radical-Derived Products of Phenylalanine

12nd Department of Medicine and Nephrological Centre, Faculty of Medicine, University of Pécs, Pacsirta Street 1, Pécs 7624, Hungary
2Department of Anaesthesia and Intensive Care, Faculty of Medicine, University of Pécs, Rákóczi Street 2, Pécs 7623, Hungary
3Department of Laboratory Medicine, Faculty of Medicine, University of Pécs, Ifjúság Street 13, Pécs 7624, Hungary

Received 10 January 2015; Accepted 3 March 2015

Academic Editor: Eric E. Kelley

Copyright © 2015 Szilárd Kun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hydroxyl radical converts Phe to para-, meta-, and ortho-Tyr (p-Tyr, m-Tyr, o-Tyr), while Phe is converted enzymatically to p-Tyr in the kidney and could serve as substrate for gluconeogenesis. Pathological isoforms m- and o-Tyr are supposed to be involved in development of hormone resistances. Role of Phe and the three Tyr isoforms in influencing insulin need was examined in 25 nondiabetic septic patients. Daily insulin dose (DID) and insulin-glucose product (IGP) were calculated. Serum and urinary levels of Phe and Tyr isoforms were determined using a rpHPLC-method. Urinary m-Tyr/p-Tyr ratio was higher in patients with DID and IGP over median compared to those below median ( and , resp.). Urinary m-Tyr and m-Tyr/p-Tyr ratio showed positive correlation with DID ( and , resp.) and with IGP ( and , resp.). Serum Phe was a negative predictor, while serum p-Tyr/Phe ratio was positive predictor of both DID and IGP. Urinary m-Tyr and urinary m-Tyr/p-Tyr, o-Tyr/p-Tyr, and (m-Tyr+o-Tyr)/p-Tyr ratios were positive predictors of both DID and IGP. Phe and Tyr isoforms have a predictive role in carbohydrate metabolism of nondiabetic septic patients. Phe may serve as substrate for renal gluconeogenesis via enzymatically produced p-Tyr, while hydroxyl radical derived Phe products may interfere with insulin action.