BACKGROUND: Phenylalanine is converted to para- and ortho-tyrosine by hydroxyl free radical, or to para-tyrosine by the phenylalanine hydroxylase enzyme. The aim of this study was to measure para- and ortho-tyrosine in the urine and plasma of patients with chronic renal disease and/or diabetes, to obtain information on the renal handling of the different tyrosine isomers and, furthermore, to measure urinary levels of 8-epi-prostaglandin-F(2alpha), a marker of lipid peroxidation. METHODS: In our cross-sectional study we measured para-, ortho-tyrosine, and phenylalanine levels, using high performance liquid chromatography and 8-epi-prostaglandin-F(2alpha) with enzyme-linked immunosorbent assay (ELISA). We compared 4 groups: (1) controls (CONTR, N = 14), (2) patients with chronic kidney disease (CKD, N = 12), (3) patients with type 2 diabetes mellitus (DIAB, N = 17), (4) patients with chronic kidney disease and type 2 diabetes (DIAB-CKD, N = 19). RESULTS: We found a decreased plasma para-tyrosine level and decreased urinary para-tyrosine excretion in CKD patients, while the fractional excretion of para-tyrosine was similar in all 4 groups, approximately 1%. There was no difference in the plasma ortho-tyrosine levels between the groups. However, urinary ortho-tyrosine excretion was higher in all 3 groups of patients than in the CONTR group, and higher in DIAB and in DIAB-CKD patients than in CKD patients. The fractional excretion of ortho-tyrosine was significantly higher in DIAB and in DIAB-CKD patients than in the CONTR group. The fractional excretion of ortho-tyrosine exceeded 100% in the 2 diabetic groups. Urinary 8-epi-prostaglandin-F(2alpha)/creatinine ratio did not correlate with urinary ortho-tyrosine excretion. CONCLUSION: The difference between para-tyrosine levels of the groups is probably due to renal impairment, while there is indirect evidence for an increased tubular secretion or production of ortho-tyrosine in the kidney in diabetic patients with or without CKD.
BACKGROUND:Phenylalanine is converted to para- and ortho-tyrosine by hydroxyl free radical, or to para-tyrosine by the phenylalanine hydroxylase enzyme. The aim of this study was to measure para- and ortho-tyrosine in the urine and plasma of patients with chronic renal disease and/or diabetes, to obtain information on the renal handling of the different tyrosine isomers and, furthermore, to measure urinary levels of 8-epi-prostaglandin-F(2alpha), a marker of lipid peroxidation. METHODS: In our cross-sectional study we measured para-, ortho-tyrosine, and phenylalanine levels, using high performance liquid chromatography and 8-epi-prostaglandin-F(2alpha) with enzyme-linked immunosorbent assay (ELISA). We compared 4 groups: (1) controls (CONTR, N = 14), (2) patients with chronic kidney disease (CKD, N = 12), (3) patients with type 2 diabetes mellitus (DIAB, N = 17), (4) patients with chronic kidney disease and type 2 diabetes (DIAB-CKD, N = 19). RESULTS: We found a decreased plasma para-tyrosine level and decreased urinary para-tyrosine excretion in CKDpatients, while the fractional excretion of para-tyrosine was similar in all 4 groups, approximately 1%. There was no difference in the plasma ortho-tyrosine levels between the groups. However, urinary ortho-tyrosine excretion was higher in all 3 groups of patients than in the CONTR group, and higher in DIAB and in DIAB-CKDpatients than in CKDpatients. The fractional excretion of ortho-tyrosine was significantly higher in DIAB and in DIAB-CKDpatients than in the CONTR group. The fractional excretion of ortho-tyrosine exceeded 100% in the 2 diabetic groups. Urinary 8-epi-prostaglandin-F(2alpha)/creatinine ratio did not correlate with urinary ortho-tyrosine excretion. CONCLUSION: The difference between para-tyrosine levels of the groups is probably due to renal impairment, while there is indirect evidence for an increased tubular secretion or production of ortho-tyrosine in the kidney in diabeticpatients with or without CKD.
Authors: Gergő A Molnár; Esztella Zsóka Mikolás; István András Szijártó; Szilárd Kun; Eszter Sélley; István Wittmann Journal: World J Diabetes Date: 2015-04-15
Authors: Lívia Szélig; Szilárd Kun; Gábor Woth; Gergő A Molnár; Zita Zrínyi; Emese Kátai; János Lantos; István Wittmann; Lajos Bogár; Attila Miseta; Csaba Csontos Journal: Redox Rep Date: 2016-06-18 Impact factor: 4.412
Authors: Gergő A Molnár; Szilárd Kun; Eszter Sélley; Melinda Kertész; Lívia Szélig; Csaba Csontos; Katalin Böddi; Lajos Bogár; Attila Miseta; István Wittmann Journal: Curr Med Chem Date: 2016 Impact factor: 4.530
Authors: Marius A Øvrehus; Per Bruheim; Wenjun Ju; Leila R Zelnick; Knut A Langlo; Kumar Sharma; Ian H de Boer; Stein I Hallan Journal: Kidney Int Rep Date: 2018-10-17
Authors: Elizabeth M Morris; Susanna E Kitts-Morgan; Dawn M Spangler; Ibukun M Ogunade; Kyle R McLeod; David L Harmon Journal: Front Vet Sci Date: 2021-07-16
Authors: Szilárd Kun; Gergő A Molnár; Eszter Sélley; Lívia Szélig; Lajos Bogár; Csaba Csontos; Attila Miseta; István Wittmann Journal: Oxid Med Cell Longev Date: 2015-10-20 Impact factor: 6.543