@inproceedings{DoyonSchmiedchenBayazitetal.2012,
  author    = {Doyon, Anke and Schmiedchen, Bettina and Bayazit, Aysun and Canpolat, Nur and Duzova, Ali and Kracht, Daniela and Litwin, Mieczyslaw and Niemirska, Anna and Sozeri, Betul and Zeller, Rene and Anarat, Ali and Caliskan, Salim and Mir, Sevgi and Shroff, Rukshana and Melk, Anette and W{\"u}hl, Elke and Schweigert, Florian J. and Querfeld, Uwe and Sch{\"a}fer, Franz},
  title     = {Altered arterial morphology and function in children with CKD Role of mineral-bone disorder},
  series = {Pediatric nephrology : journal of the International Pediatric Nephrology Association},
  volume    = {27},
  booktitle = {Pediatric nephrology : journal of the International Pediatric Nephrology Association},
  number    = {9},
  publisher = {Springer},
  address   = {New York},
  organization    = {4C Study Consortium},
  issn      = {0931-041X},
  pages     = {1606 -- 1607},
  year      = {2012},
  language  = {en}
}
@inproceedings{DoyonSchmiedchenBayazitetal.2012,
  author    = {Doyon, Anke and Schmiedchen, Bettina and Bayazit, Aysun and Canpolat, Nur and Duzova, Ali and Kracht, Daniela and Litwin, Mieczyslaw and Niemirska, Anna and Sozeri, Betul and Zeller, Rene and Ranchin, Bruno and Anarat, Ali and Caliskan, Salim and Mir, Sevgi and Melk, Anette and W{\"u}hl, Elke and Schweigert, Florian J. and Querfeld, Uwe and Sch{\"a}fer, Franz},
  title     = {Distribuion and determinants of serum vitamin d concentrations in european children with chronic kidney disease},
  series = {Pediatric nephrology : journal of the International Pediatric Nephrology Association},
  volume    = {27},
  booktitle = {Pediatric nephrology : journal of the International Pediatric Nephrology Association},
  number    = {9},
  publisher = {Springer},
  address   = {New York},
  organization    = {4C Consortium},
  issn      = {0931-041X},
  pages     = {1627 -- 1628},
  year      = {2012},
  language  = {en}
}
@article{PasslackSchmiedchenRailaetal.2016,
  author    = {Passlack, Nadine and Schmiedchen, Bettina and Raila, Jens and Schweigert, Florian J. and Stumpff, Friederike and Kohn, Barbara and Neumann, Konrad and Zentek, Juergen},
  title     = {Impact of Increasing Dietary Calcium Levels on Calcium Excretion and Vitamin D Metabolites in the Blood of Healthy Adult Cats},
  series = {PLoS one},
  volume    = {11},
  journal   = {PLoS one},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0149190},
  pages     = {47 -- 67},
  year      = {2016},
  abstract  = {Background Dietary calcium (Ca) concentrations might affect regulatory pathways within the Ca and vitamin D metabolism and consequently excretory mechanisms. Considering large variations in Ca concentrations of feline diets, the physiological impact on Ca homeostasis has not been evaluated to date. In the present study, diets with increasing concentrations of dicalcium phosphate were offered to ten healthy adult cats (Ca/phosphorus (P): 6.23/6.02, 7.77/7.56, 15.0/12.7, 19.0/17.3, 22.2/19.9, 24.3/21.6 g/kg dry matter). Each feeding period was divided into a 10-day adaptation and an 8-day sampling period in order to collect urine and faeces. On the last day of each feeding period, blood samples were taken. Results Urinary Ca concentrations remained unaffected, but faecal Ca concentrations increased (P < 0.001) with increasing dietary Ca levels. No effect on whole and intact parathyroid hormone levels, fibroblast growth factor 23 and calcitriol concentrations in the blood of the cats were observed. However, the calcitriol precursors 25(OH)D-2 and 25(OH)D-3, which are considered the most useful indicators for the vitamin D status, decreased with higher dietary Ca levels (P = 0.013 and P = 0.033). Increasing dietary levels of dicalcium phosphate revealed an acidifying effect on urinary fasting pH (6.02) and postprandial pH (6.01) (P < 0.001), possibly mediated by an increase of urinary phosphorus (P) concentrations (P < 0.001). Conclusions In conclusion, calcitriol precursors were linearly affected by increasing dietary Ca concentrations. The increase in faecal Ca excretion indicates that Ca homeostasis of cats is mainly regulated in the intestine and not by the kidneys. Long-term studies should investigate the physiological relevance of the acidifying effect observed when feeding diets high in Ca and P.},
  language  = {en}
}
@misc{PasslackSchmiedchenRailaetal.2016,
  author    = {Paßlack, Nadine and Schmiedchen, Bettina and Raila, Jens and Schweigert, Florian J. and Stumpff, Friederike and Kohn, Barbara and Neumann, Konrad and Zentek, J{\"u}rgen},
  title     = {Impact of increasing dietary calcium levels on calcium excretion and vitamin D metabolites in the blood of healthy adult cats},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {542},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-41130},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-411302},
  pages     = {19},
  year      = {2016},
  abstract  = {Background Dietary calcium (Ca) concentrations might affect regulatory pathways within the Ca and vitamin D metabolism and consequently excretory mechanisms. Considering large variations in Ca concentrations of feline diets, the physiological impact on Ca homeostasis has not been evaluated to date. In the present study, diets with increasing concentrations of dicalcium phosphate were offered to ten healthy adult cats (Ca/phosphorus (P): 6.23/6.02, 7.77/7.56, 15.0/12.7, 19.0/17.3, 22.2/19.9, 24.3/21.6 g/kg dry matter). Each feeding period was divided into a 10-day adaptation and an 8-day sampling period in order to collect urine and faeces. On the last day of each feeding period, blood samples were taken. Results Urinary Ca concentrations remained unaffected, but faecal Ca concentrations increased (P < 0.001) with increasing dietary Ca levels. No effect on whole and intact parathyroid hormone levels, fibroblast growth factor 23 and calcitriol concentrations in the blood of the cats were observed. However, the calcitriol precursors 25(OH)D-2 and 25(OH)D-3, which are considered the most useful indicators for the vitamin D status, decreased with higher dietary Ca levels (P = 0.013 and P = 0.033). Increasing dietary levels of dicalcium phosphate revealed an acidifying effect on urinary fasting pH (6.02) and postprandial pH (6.01) (P < 0.001), possibly mediated by an increase of urinary phosphorus (P) concentrations (P < 0.001). Conclusions In conclusion, calcitriol precursors were linearly affected by increasing dietary Ca concentrations. The increase in faecal Ca excretion indicates that Ca homeostasis of cats is mainly regulated in the intestine and not by the kidneys. Long-term studies should investigate the physiological relevance of the acidifying effect observed when feeding diets high in Ca and P.},
  language  = {en}
}
@phdthesis{Schmiedchen2014,
  author    = {Schmiedchen, Bettina},
  title     = {Vitamin D and its linkage between chronic kidney disease and cardiovascular integrity},
  pages     = {113},
  year      = {2014},
  language  = {en}
}
@article{SchmiedchenLongardtBuehreretal.2014,
  author    = {Schmiedchen, Bettina and Longardt, Ann Carolin and Buehrer, Christoph and Raila, Jens and Loui, Andrea and Schweigert, Florian J.},
  title     = {The relative dose response test based on retinol-binding protein 4 is not suitable to assess vitamin A status in very low birth weight infants},
  series = {Neonatology : fetal and neonatal research},
  volume    = {105},
  journal   = {Neonatology : fetal and neonatal research},
  number    = {2},
  publisher = {Karger},
  address   = {Basel},
  issn      = {1661-7800},
  doi       = {10.1159/000356773},
  pages     = {155 -- 160},
  year      = {2014},
  language  = {en}
}
@misc{SchmiedchenLongardtBuehreretal.2017,
  author    = {Schmiedchen, Bettina and Longardt, Ann Carolin and B{\"u}hrer, Christoph and Raila, Jens and Loui, Andrea and Schweigert, Florian J.},
  title     = {The Relative Dose Response Test Based on Retinol-Binding Protein 4 Is Not Suitable to Assess Vitamin A Status in Very Low Birth Weight Infants},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-399853},
  pages     = {6},
  year      = {2017},
  abstract  = {Background: The relative dose response (RDR) test, which quantifies the increase in serum retinol after vitamin A administration, is a qualitative measure of liver vitamin A stores. Particularly in preterm infants, the feasibility of the RDR test involving blood is critically dependent on small sample volumes. Objectives: This study aimed to assess whether the RDR calculated with retinol-binding protein 4 (RBP4) might be a substitute for the classical retinol-based RDR test for assessing vitamin A status in very preterm infants. Methods: This study included preterm infants with a birth weight below 1,500 g (n = 63, median birth weight 985 g, median gestational age 27.4 weeks) who were treated with 5,000 IU retinyl palmitate intramuscularly 3 times a week for 4 weeks. On day 3 (first vitamin A injection) and day 28 of life (last vitamin A injection), the RDR was calculated and compared using serum retinol and RBP4 concentrations. Results: The concentrations of retinol (p < 0.001) and RBP4 (p < 0.01) increased significantly from day 3 to day 28. On day 3, the median (IQR) retinol-RDR was 27\% (8.4-42.5) and the median RBP4-RDR was 8.4\% (-3.4 to 27.9), compared to 7.5\% (-10.6 to 20.8) and -0.61\% (-19.7 to 15.3) on day 28. The results for retinol-RDR and RBP4-RDR revealed no significant correlation. The agreement between retinol-RDR and RBP4-RDR was poor (day 3: Cohen's κ = 0.12; day 28: Cohen's κ = 0.18). Conclusion: The RDR test based on circulating RBP4 is unlikely to reflect the hepatic vitamin A status in preterm infants.},
  language  = {en}
}
@article{SchmiedchenLongardtLouietal.2016,
  author    = {Schmiedchen, Bettina and Longardt, Ann Carolin and Loui, Andrea and Buehrer, Christoph and Raila, Jens and Schweigert, Florian J.},
  title     = {Effect of vitamin A supplementation on the urinary retinol excretion in very low birth weight infants},
  series = {European journal of pediatrics : official organ of the Belgian Pediatric Association},
  volume    = {175},
  journal   = {European journal of pediatrics : official organ of the Belgian Pediatric Association},
  publisher = {Springer},
  address   = {New York},
  issn      = {0340-6199},
  doi       = {10.1007/s00431-015-2647-9},
  pages     = {365 -- 372},
  year      = {2016},
  abstract  = {Despite high-dose vitamin A supplementation of very low birth weight infants (VLBW, <1500 g), their vitamin A status does not improve substantially. Unknown is the impact of urinary retinol excretion on the serum retinol concentration in these infants. Therefore, the effect of high-dose vitamin A supplementation on the urinary vitamin A excretion in VLBW infants was investigated. Sixty-three VLBW infants were treated with vitamin A (5000 IU intramuscular, 3 times/week for 4 weeks); 38 untreated infants were classified as control group. On days 3 and 28 of life, retinol, retinol-binding protein 4 (RBP4), glomerular filtration rate, proteinuria, and Tamm-Horsfall protein were quantified in urine. On day 3 of life, substantial retinol and RBP4 losses were found in both groups, which significantly decreased until day 28. Notwithstanding, the retinol excretion was higher (P<0.01) under vitamin A supplementation as compared to infants of the control group. On day 28 of life, the urinary retinol concentrations were predictive for serum retinol concentrations in the vitamin A treated (P<0.01), but not in the control group (P=0.570). Conclusion: High urinary retinol excretion may limit the vitamin A supplementation efficacy in VLBW infants. Advanced age and thus postnatal kidney maturation seems to be an important contributor in the prevention of urinary retinol losses.},
  language  = {en}
}