TY  - JOUR
A1  - Hocher, Berthold
A1  - Armbruster, Franz Paul
A1  - Stöva, Stanka
A1  - Reichetzeder, Christoph
A1  - Groen, Hans Jürgen
A1  - Lieker, Ina
A1  - Khadzhynov, Dmytro
A1  - Slowinski, Torsten
A1  - Roth, Heinz Jürgen
T1  - Measuring Parathyroid Hormone (PTH) in patients with oxidative stress - do we need a fourth generation Parathyroid Hormone assay?
JF  - PLoS one
N2  - Oxidation of PTH at methionine residues results in loss of biological activity. PTH may be oxidized in patients with renal disease. The aim of this study was to develop an assay considering oxidation of PTH. Oxidized hPTH was analyzed by high resolution nano-liquid chromatography coupled to ESI-FTT tandem mass spectrometry (nanoLC-ESI-FT-MS/MS) directly and after proteolytic cleavage. The oxidized hPTH(1-84) sample shows TIC-peaks at 18-20 min and several mass peaks due to mass shifts caused by oxidations. No significant signal for oxidized hPTH(1-84) species after removal of oxidized PTH molecules by a specific column with monoclonal antibodies (MAB) raised against the oxidized hPTH was detectable. By using this column in samples from 18 patients on dialysis we could demonstrate that measured PTH concentrations were substantially lower when considering oxidized forms of PTH. The relationship between PTH concentrations determined directly and those concentrations measured after removal of the oxidized PTH forms varies substantially. In some patients only 7% of traditionally measured PTH was free of oxidation, whereas in other patients 34% of the traditionally measured PTH was real intact PTH. In conclusion, a huge but not constant proportion of PTH molecules are oxidized in patients requiring dialysis. Since oxidized PTH is biologically inactive, the currently used methods to detect PTH in daily clinical practice may not adequately reflect PTH-related bone and cardiovascular abnormalities in patients on dialysis.
Y1  - 2012
U6  - https://doi.org/10.1371/journal.pone.0040242
SN  - 1932-6203
VL  - 7
IS  - 7
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Nair, Anil V.
A1  - Hocher, Berthold
A1  - Verkaart, Sjoerd
A1  - van Zeeland, Femke
A1  - Pfab, Thiemo
A1  - Slowinski, Torsten
A1  - Chen, You-Peng
A1  - Schlingmann, Karl Peter
A1  - Schaller, Andre
A1  - Gallati, Sabina
A1  - Bindels, Rene J.
A1  - Konrad, Martin
A1  - Hönderop, Joost G.
T1  - Loss of insulin-induced activation of TRPM6 magnesium channels results in impaired glucose tolerance during pregnancy
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Hypomagnesemia affects insulin resistance and is a risk factor for diabetes mellitus type 2 (DM2) and gestational diabetes mellitus (GDM). Two single nucleotide polymorphisms (SNPs) in the epithelial magnesium channel TRPM6 ((VI)-I-1393, (KE)-E-1584) were predicted to confer susceptibility for DM2. Here, we show using patch clamp analysis and total internal reflection fluorescence microscopy, that insulin stimulates TRPM6 activity via a phosphoinositide 3-kinase and Rac1-mediated elevation of cell surface expression of TRPM6. Interestingly, insulin failed to activate the genetic variants TRPM6 ((VI)-I-1393) and TRPM6((KE)-E-1584), which is likely due to the inability of the insulin signaling pathway to phosphorylate TRPM6(T-1391) and TRPM6(S-1583). Moreover, by measuring total glycosylated hemoglobin (TGH) in 997 pregnant women as a measure of glucose control, we demonstrate that TRPM6((VI)-I-1393) and TRPM6((KE)-E-1584) are associated with higher TGH and confer a higher likelihood of developing GDM. The impaired response of TRPM6((VI)-I-1393) and TRPM6((KE)-E-1584) to insulin represents a unique molecular pathway leading to GDM where the defect is located in TRPM6.
KW  - kidney
KW  - distal convoluted tubule
KW  - transient receptor potential
KW  - vesicular trafficking
Y1  - 2012
U6  - https://doi.org/10.1073/pnas.1113811109
SN  - 0027-8424
VL  - 109
IS  - 28
SP  - 11324
EP  - 11329
PB  - National Acad. of Sciences
CY  - Washington
ER  -