TY - JOUR A1 - Espe, Katharina M. A1 - Raila, Jens A1 - Henze, Andrea A1 - Blouin, Katja A1 - Schneider, Andreas A1 - Schmiedeke, Daniel A1 - Krane, Vera A1 - Pilz, Stefan A1 - Schweigert, Florian J. A1 - Hocher, Berthold A1 - Wanner, Christoph A1 - Drechsler, Christiane T1 - Low plasma alpha-tocopherol concentrations and adverse clinical outcomes in diabetic hemodialysis patients JF - Clinical journal of the American Society of Nephrology N2 - Background and objectives Trials with the antioxidant vitamin E have failed to show benefit in the general population. Considering the different causes of death in ESRD, this study investigated the association between plasma concentrations of alpha-tocopherol and specific clinical outcomes in diabetic hemodialysis patients. Design, settings, participants, & measurements In 1046 diabetic hemodialysis patients (participants of the German Diabetes and Dialysis Study), alpha-tocopherol was measured in plasma by reversed-phase HPLC. By Cox regression analyses, hazard ratios were determined for prespecified end points according to baseline plasma alpha-tocopherol levels: sudden death (n=134), myocardial infarction (n=172), stroke (n=89), combined cardiovascular events (n=398), fatal infection (n=107), and all-cause mortality (n=508). Results Patients had a mean age of 66 8 years, and mean plasma alpha-tocopherol level was 22.8+/-9.6 mu mol/L. Levels of alpha-tocopherol were highly correlated to triglycerides (r=0.63, P<0.001). Patients in the lowest alpha-tocopherol quartile had (in unadjusted analyses) a 79% higher risk of stroke and a 31% higher risk of all-cause mortality compared with patients in the highest quartile. The associations were attenuated after adjustment for confounders (hazard ratio(stroke)=1.56, 95% confidence interval=0.75-3.25; hazard ratio(mortality)=1.22, 95% confidence interval=0.89-1.69, respectively). There was no association between alpha-tocopherol and myocardial infarction, sudden death, or infectious death. Conclusions Plasma alpha-tocopherol concentrations were not independently associated with cardiovascular outcomes, infectious deaths, or all-cause mortality in diabetic hemodialysis patients. The lack of association can partly be explained by a confounding influence of malnutrition, which should be considered in the planning of trials to reduce cardiovascular risk in dialysis patients. Y1 - 2013 U6 - https://doi.org/10.2215/CJN.04880511 SN - 1555-9041 VL - 8 IS - 3 SP - 452 EP - 458 PB - American Society of Nephrology CY - Washington ER - TY - JOUR A1 - Henze, Andrea A1 - Raila, Jens A1 - Scholze, Alexandra A1 - Zidek, Walter A1 - Tepel, Martin A1 - Schweigert, Florian J. T1 - Does N-Acetylcysteine modulate post-translational modifications of transthyretin in hemodialysis patients? JF - Antioxidants & redox signaling N2 - It is assumed that effects of the thiol antioxidant N-acetylcysteine (NAC) are mediated by interaction with protein-associated cysteine residues, however, information on protein level in vivo are missing. Therefore, we analyzed NAC-induced modifications of the protein transthyretin (TTR) in plasma of hemodialysis patients in a randomized, placebo-controlled study. TTR was selected due to its low molecular weight and the free cysteine residue in the polypeptide chain, which is known to be extensively modified by formation of mixed disulfides. The intravenous application of NAC during a hemodialysis session resulted in a substantial increase of native TTR from median 15% (range 8.8%-30%) to median 40% (37-50) and reduction of S-cysteinylated TTR [51% (44-60) vs. 6.6% (2.4-10)]. Additionally the pronounced formation of a TTR-NAC adduct was detected. However, all these modifications seemed to be reversible. Additionally, in vitro incubation of plasma with NAC confirmed the in vivo results and indicated that changes in post-translational modification pattern of TTR were a function of NAC concentration. Based on these observations and the essential metabolic and biochemical role of protein-associated cysteine residues we hypothesize that the interaction of NAC with proteins may explain altered protein functions due to modification of cysteine residues. Antioxid. Redox Signal. 19, 1166-1172. Y1 - 2013 U6 - https://doi.org/10.1089/ars.2012.5125 SN - 1523-0864 VL - 19 IS - 11 SP - 1166 EP - 1172 PB - Liebert CY - New Rochelle ER - TY - JOUR A1 - Münzner, Matthias A1 - Tuvia, Neta A1 - Deutschmann, Claudia A1 - Witte, Nicole A1 - Tolkachov, Alexander A1 - Valai, Atijeh A1 - Henze, Andrea A1 - Sander, Leif E. A1 - Raila, Jens A1 - Schupp, Michael T1 - Retinol-binding protein 4 and its membrane receptor STRA6 control adipogenesis by regulating cellular retinoid homeostasis and retinoic acid receptor alpha activity JF - Molecular and cellular biology N2 - Retinoids are vitamin A (retinol) derivatives and complex regulators of adipogenesis by activating specific nuclear receptors, including the retinoic acid receptor (RAR) and retinoid X receptor (RXR). Circulating retinol-binding protein 4 (RBP4) and its membrane receptor STRA6 coordinate cellular retinol uptake. It is unknown whether retinol levels and the activity of RAR and RXR in adipocyte precursors are linked via RBP4/STRA6. Here, we show that STRA6 is expressed in precursor cells and, dictated by the apo-and holo-RBP4 isoforms, mediates bidirectional retinol transport that controls RAR alpha activity and subsequent adipocyte differentiation. Mobilization of retinoid stores in mice by inducing RBP4 secretion from the liver activated RAR alpha signaling in the precursor cell containing the stromal-vascular fraction of adipose tissue. Retinol-loaded holo-RBP4 blocked adipocyte differentiation of cultured precursors by activating RAR alpha. Remarkably, retinol-free apo-RBP4 triggered retinol efflux that reduced cellular retinoids, RAR alpha activity, and target gene expression and enhanced adipogenesis synergistically with ectopic STRA6. Thus, STRA6 in adipocyte precursor cells links nuclear RAR alpha activity to the circulating RBP4 isoforms, whose ratio in obese mice was shifted toward limiting the adipogenic potential of their precursors. This novel cross talk identifies a retinoldependent metabolic function of RBP4 that may have important implications for the treatment of obesity. Y1 - 2013 U6 - https://doi.org/10.1128/MCB.00221-13 SN - 0270-7306 SN - 1098-5549 VL - 33 IS - 20 SP - 4068 EP - 4082 PB - American Society for Microbiology CY - Washington ER - TY - CHAP A1 - Henze, Andrea A1 - Raila, Jens A1 - Scholze, Alexandra A1 - Schweigert, Florian J. A1 - Tepel, Martin T1 - Administration of N-Acetylcyteine causes beneficial posttranslationalmodifications of transthyretin in hemodialysis patients T2 - Nephrology, dialysis, transplantation Y1 - 2013 SN - 0931-0509 VL - 28 IS - 2 SP - 164 EP - 164 PB - Oxford Univ. Press CY - Oxford ER -