@article{HocherArmbrusterStoevaetal.2012,
  author    = {Hocher, Berthold and Armbruster, Franz Paul and St{\"o}va, Stanka and Reichetzeder, Christoph and Groen, Hans J{\"u}rgen and Lieker, Ina and Khadzhynov, Dmytro and Slowinski, Torsten and Roth, Heinz J{\"u}rgen},
  title     = {Measuring Parathyroid Hormone (PTH) in patients with oxidative stress - do we need a fourth generation Parathyroid Hormone assay?},
  series = {PLoS one},
  volume    = {7},
  journal   = {PLoS one},
  number    = {7},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0040242},
  pages     = {10},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{HocherGroenSchumannetal.2012,
  author    = {Hocher, Berthold and Groen, Hans J{\"u}rgen and Schumann, Claudia and Tsuprykov, Oleg and Seifert, Susanne and Hitzler, Walter E. and Armbruster, Franz Paul},
  title     = {Vitamin D status from dried capillary blood samples},
  series = {Clinical laboratory : the peer reviewed journal for clinical laboratories and laboratories related to blood transfusion},
  volume    = {58},
  journal   = {Clinical laboratory : the peer reviewed journal for clinical laboratories and laboratories related to blood transfusion},
  number    = {7-8},
  publisher = {Clin Lab Publ., Verl. Klinisches Labor},
  address   = {Heidelberg},
  issn      = {1433-6510},
  doi       = {10.7754/Clin.Lab.2012.120429},
  pages     = {851 -- 855},
  year      = {2012},
  abstract  = {Background: Given the huge impact of vitamin D deficiency on a broad spectrum of diseases such as rickets, osteoporosis, mineral bone disease-vascular calcification syndrome, infectious diseases, but also several types of cancer and CNS diseases, reliable and simple methods to analyze the vitamin D status are urgently needed. Methods: We developed an easy technique to determine the 25-OH vitamin D status from dried blood samples on filter paper. This allows determination of the 25-OH vitamin D status independently of venous blood taking, since only sampling of capillary blood is required for this new method. We compared the results of vitamin D measurements from venous blood of 96 healthy blood donors with those from capillary blood taken from the same patients at the same time. The capillary blood was dried on filter paper using the D-Vital ID dry-blood collection system. Results: 25-OH vitamin D concentration data from extracted dried capillary blood filters correlated very well with data obtained after direct measurement of venous blood samples of the same blood donor (R: 0.7936; p<0.0001). The correlation was linear over the whole range of 25-OH vitamin D concentrations seen in this study. A Bland-Altman plot revealed good agreement between both tests. Conclusions: The D-Vital ID dry-blood collection system showed an excellent performance as compared to the classical way of 25-OH vitamin D measurement from venous blood. This new technique will facilitate easy and reliable measurement for vitamin D status, in particular, in rural or isolated areas, developing countries, and field studies.},
  language  = {en}
}