@article{FreyHenzeNagletal.2009,
  author    = {Frey, Simone K. and Henze, Andrea and Nagl, Britta and Raila, Jens and Scholze, Alexandra and Tepel, Martin and Schweigert, Florian J. and Zidek, Walter},
  title     = {Effect of renal replacement therapy on retinol-binding protein 4 isoforms},
  issn      = {0009-8981},
  doi       = {10.1016/j.cca.2008.11.008},
  year      = {2009},
  abstract  = {Background: Retinol-binding protein 4 (RBP4) levels are elevated in the serum of patients with kidney dysfunction. We recently showed that RBP4 isoforms including apo-RBP4 (RBP4 not bound to retinol) and RBP4 truncated at the C-terminus (RBP4-L, RBP4-LL) are increased in the serum of patients with kidney diseases but not in serum of patients with various liver diseases. The aim of this study was to investigate the effect of renal replacement therapy on RBP4 isoforms. Methods: We investigated serum levels of RBP4, apo-RBP4, holo-RBP4, RBP4-L, RBP4-LL, retinol and transthyretin (TTR) in 18 hemodialysis (HD) patients, 30 patients after renal transplantation (RTx) and in 35 healthy controls. RBP4 and TTR levels were measured by enzyme-linked immunosorbent assay, apo- and holo-RBP4 by native electrophoresis, retinol by high performance liquid chromatography and RBP4-L and RBP4-LL were analyzed by mass spectrometry. Results: HD and RTx patients had elevated RBP4, apo-RBP4 and RBP4-LL levels compared to controls. RTx patients had elevated amounts of RBP4-L compared to controls and elevated RBP4 and apo-RBP4 levels compared to HD patients. Conclusion: The results demonstrate a strong correlation between kidney function and RBP4 isoforms and provide data for investigating the relation of RBP4 and insulin resistance in these patients.},
  language  = {en}
}
@article{FreySprangerHenzeetal.2009,
  author    = {Frey, Simone K. and Spranger, Joachim and Henze, Andrea and Pfeiffer, Andreas F. H. and Schweigert, Florian J. and Raila, Jens},
  title     = {Factors that influence retinol-binding protein 4-transthyretin interaction are not altered in overweight subjects and overweight subjects with type 2 diabetes mellitus},
  issn      = {0026-0495},
  doi       = {10.1016/j.metabol.2009.05.003},
  year      = {2009},
  abstract  = {Retinol-binding protein 4 (RBP4) is an adipokine bound in plasma to transthyretin (TTR), which prevents its glomerular filtration and subsequent catabolism in the kidney. Alterations of this interaction have been Suggested to be implicated in the elevation of RBP4 that are thought to contribute to the development Of insulin resistance associated with obesity and type 2 diabetes mellitus (T2DM). However, the factors linking RBP4 to TTR in humans are not clear. Therefore, this Study evaluated parameters influencing the RBP4-TTR interaction and their relation to obesity and T2DM. The RBP4 and TTR levels were quantified in plasma of 16 lean controls, 28 overweight controls, and 14 overweight T2DM patients by enzyme-linked immunosorbent assay. Transthyretin isoforms involved in RBP4 binding were determined by linear matrix-assisted laser desorption/ionization-time of flight-mass spectrometry after RBP4 coimmunoprecipitation. Holo-RBP4 (retinol-bound) and apo-RBP4 (retinol-free) were assessed by immunoblotting using nondenaturating polyacrylamide gel electrophoresis. Plasma levels of both RBP4 and TTR did not differ among the groups of lean controls, overweight controls, and overweight T2DM subjects. Using RBP4 immunoprecipitation, 4 mass signals were observed for TTR representing native, S-cysteinylated, S-cysteinglycinylated, and S-glutathionylated TTR. No differences in peak intensity of TTR isoforms were observed among the groups. Moreover, no differences in the ratio of holo- and apo-RBP4 were evident. The results suggest that circulating RBP4 and TTR were not affected by human obesity or T2DM, which might be attributed to the absence of alterations of TTR isoforms and the ratio of holo- and apo-RBP4 that might modify the TTR-RBP4 interaction.},
  language  = {en}
}
@phdthesis{Henze2009,
  author    = {Henze, Andrea},
  title     = {Chronic kidney disease and type 2 diabetes mellitus as factors influencing retinol-binding protein 4},
  address   = {Potsdam},
  pages     = {XI, 143 S. : Ill., graph. Darst.},
  year      = {2009},
  language  = {en}
}