title: Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study.
abstract: OBJECTIVE
  Sepsis is associated with oxidative stress. Due to oxidative stress, three tyrosine isoforms, para-, meta-, and ortho-tyrosine (p-, m-, and o-Tyr), can be formed non-enzymatically in smaller amounts. p-Tyr is mainly formed physiologically in the kidneys through the activity of the phenylalanine hydroxylase enzyme. The three tyrosine isoforms may undergo different renal handling.
  
  
  METHODS
  Twenty septic patients were involved in the study and 25 healthy individuals served as controls. Blood and urine levels of p-, m-, and o-Tyr were measured on admission and four consecutive days.
  
  
  RESULTS
  Serum m-Tyr levels were higher in septic patients than in controls on days 2 (P = 0.031) and 3 (P = 0.035). Serum p-Tyr levels were lower in the cases than in controls on days 1 (P = 0.005) and 2 (P = 0.040), and subsequently normalized due to a day-by-day elevation (P = 0.002). The tendency of urinary m-Tyr concentration was decreasing (P = 0.041), while that of urinary p-Tyr concentration was increasing (P = 0.001). Fractional excretion of m-Tyr (FEm-Tyr) showed a decreasing tendency (P = 0.009), and was, on all days, higher than FEp-Tyr, which remained near-normal, less than 4%. Procalcitonin showed significant correlation with FEm-Tyr (r = 0.454; P < 0.001).
  
  
  CONCLUSIONS
  Our data suggest that the oxidative stress marker m-Tyr and physiologic p-Tyr may be handled differently in septic patients. The excretion of m-Tyr correlates with inflammation. m-Tyr may be actively secreted or produced in the kidney in some patients, whereas the decreased serum level of p-Tyr is a consequence of diminished renal production and not of renal loss.
authors.affiliation: a Department of Anaesthesia and Intensive Care, Faculty of Medicine , University of Pécs , Akác utca 1, H-7632 Hungary.
authors.forename: Lívia
authors.initials: L
authors.lastname: Szélig
authors.affiliation: b 2nd Department of Medicine and Nephrological Centre, Faculty of Medicine , University of Pécs , Pacsirta utca 1, H-7624 Hungary.
authors.forename: Szilárd
authors.initials: S
authors.lastname: Kun
authors.affiliation: a Department of Anaesthesia and Intensive Care, Faculty of Medicine , University of Pécs , Akác utca 1, H-7632 Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Woth
authors.affiliation: b 2nd Department of Medicine and Nephrological Centre, Faculty of Medicine , University of Pécs , Pacsirta utca 1, H-7624 Hungary.
authors.forename: Gergő A
authors.initials: GA
authors.lastname: Molnár
authors.affiliation: c Department of Laboratory Medicine, Faculty of Medicine , University of Pécs , Ifjúság út 13, H-7624 Hungary.
authors.forename: Zita
authors.initials: Z
authors.lastname: Zrínyi
authors.affiliation: c Department of Laboratory Medicine, Faculty of Medicine , University of Pécs , Ifjúság út 13, H-7624 Hungary.
authors.forename: Emese
authors.initials: E
authors.lastname: Kátai
authors.affiliation: d Department of Surgical Research and Techniques, Faculty of Medicine , University of Pécs , Kodály Z. utca 20, H-7624 Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Lantos
authors.affiliation: b 2nd Department of Medicine and Nephrological Centre, Faculty of Medicine , University of Pécs , Pacsirta utca 1, H-7624 Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Wittmann
authors.affiliation: a Department of Anaesthesia and Intensive Care, Faculty of Medicine , University of Pécs , Akác utca 1, H-7632 Hungary.
authors.forename: Lajos
authors.initials: L
authors.lastname: Bogár
authors.affiliation: c Department of Laboratory Medicine, Faculty of Medicine , University of Pécs , Ifjúság út 13, H-7624 Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Miseta
authors.affiliation: a Department of Anaesthesia and Intensive Care, Faculty of Medicine , University of Pécs , Akác utca 1, H-7632 Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Csontos
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D011446:Prospective Studies; D018805:Sepsis / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D014443:Tyrosine; C026741:2-tyrosine
keywords: Acute renal failure; Hydroxyl radical; Oxidative stress; Sepsis; Tyrosine