title: Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review.
abstract: Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases.
authors.forename: Gergő A
authors.initials: GA
authors.lastname: Molnár
authors.forename: Szilárd
authors.initials: S
authors.lastname: Kun
authors.forename: Eszter
authors.initials: E
authors.lastname: Sélley
authors.forename: Melinda
authors.initials: M
authors.lastname: Kertész
authors.forename: Lívia
authors.initials: L
authors.lastname: Szélig
authors.forename: Csaba
authors.initials: C
authors.lastname: Csontos
authors.forename: Katalin
authors.initials: K
authors.lastname: Böddi
authors.forename: Lajos
authors.initials: L
authors.lastname: Bogár
authors.forename: Attila
authors.initials: A
authors.lastname: Miseta
authors.affiliation: 2nd Department of Medicine and Nephrological Center, Medical School, University of Pécs, Pacsirta str. 1., H-7624 Pécs, Hungary. istvan.wittmann@aok.pte.hu.
authors.forename: István
authors.initials: I
authors.lastname: Wittmann
mesh_terms: D000208:Acute Disease; D000818:Animals; D002908:Chronic Disease; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D013237:Stereoisomerism; D014443:Tyrosine / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D014443:Tyrosine