@article{SchweigertKlingerHurtienneetal.2003,
  author    = {Schweigert, Florian J. and Klinger, Jeannine and Hurtienne, Andrea and Zunft, Hans-Joachim Franz},
  title     = {Vitamin A, carotenoid and vitamin E plasma concentrations in children from Laos in relation to sex and growth failure},
  year      = {2003},
  language  = {en}
}
@article{SchweigertHurtienneBathe2000,
  author    = {Schweigert, Florian J. and Hurtienne, Andrea and Bathe, Katharina},
  title     = {Improved extraction procedure for carotenoids from human milk},
  issn      = {0300-9831},
  year      = {2000},
  language  = {en}
}
@article{RohnerFreyMothesetal.2011,
  author    = {Rohner, Fabian and Frey, Simone K. and Mothes, Ralf and Hurtienne, Andrea and Hartong, Simone and Bosso, Patrice Emery and Bui, Mai and Schweigert, Florian J. and Northrop-Clewes, Christine},
  title     = {Quantification of vitamin A in palm oil using a fast and simple portable device method validation and comparison to high-performance liquid chromatography},
  series = {International journal for vitamin and nutrition research},
  volume    = {81},
  journal   = {International journal for vitamin and nutrition research},
  number    = {5},
  publisher = {Hogrefe},
  address   = {Bern},
  issn      = {0300-9831},
  doi       = {10.1024/0300-9831/a000081},
  pages     = {335 -- 342},
  year      = {2011},
  abstract  = {Vitamin A deficiency continues to be a global public health problem. Fortification of oil with vitamin A is considered a cost-effective, feasible strategy to prevent this problem but quality control poses a challenge to program implementation. To overcome this, we have validated a newly developed device that quantitatively measures the content of retinyl palmitate in refined palm oil, is simple to use, and yields immediate results. Linearity of analysis rand from 2.5-30 mg retinol equivalents (RE)/kg of palm oil, with 2.5 mg RE/kg being the determination limit; inter- and intra-assay precision ranged from 1.4-7.1 To. Comparison with a high-performance Liquid chromatography method showed high agreement between the methods (R-2 = 0.92; Limits of Agreement: -1.24 mg to 2.53 mg RE/kg), and further comparisons illustrate that the new device is useful in low resource settings. This device offers a field- and user-friendly solution to quantifying the vitamin A content in refined palm oil.},
  language  = {en}
}
@article{RailaEnjalbertMothesetal.2012,
  author    = {Raila, Jens and Enjalbert, Francis and Mothes, Ralf and Hurtienne, Andrea and Schweigert, Florian J.},
  title     = {Validation of a new point-of-care assay for determination of ss-carotene concentration in bovine whole blood and plasma},
  series = {Veterinary clinical pathology},
  volume    = {41},
  journal   = {Veterinary clinical pathology},
  number    = {1},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {0275-6382},
  doi       = {10.1111/j.1939-165X.2012.00400.x},
  pages     = {119 -- 122},
  year      = {2012},
  abstract  = {Background: beta-Carotene is an important precursor of vitamin A, and is associated with bovine fertility. beta-Carotene concentrations in plasma are used to optimize beta-carotene supplementation in cattle, but measurement requires specialized equipment to separate plasma and extract and measure beta-carotene, either using spectrophotometry or high performance liquid chromatography (HPLC). Objective: The objective of this study was to validate a new 2-step point-of-care (POC) assay for measuring beta-carotene in whole blood and plasma. Methods: beta-carotene concentrations in plasma from 166 cows were measured using HPLC and compared with results obtained using a POC assay, the iCheck-iEx-Carotene test kit. Whole blood samples from 23 of these cattle were also evaluated using the POC assay and compared with HPLC-plasma results from the same 23 animals. The POC assay includes an extraction vial (iEx Carotene) and hand-held photometer (iCheck Carotene). Results: Concentrations of beta-carotene in plasma measured using the POC assay ranged from 0.40 to 15.84 mg/L (n = 166). No differences were observed between methods for assay of plasma (mean +/- SD; n = 166): HPLC-plasma 4.23 +/- 2.35 mg/L; POC-plasma 4.49 +/- 2.36 mg/L. Similar good agreement was found when plasma analyzed using HPLC was compared with whole blood analyzed using the POC system (n = 23): HPLC-plasma 3.46 +/- 2.12 mg/L; POC-whole blood 3.67 +/- 2.29 mg/L. Conclusions: Concentrations of beta-carotene can be measured in blood and plasma from cattle easily and rapidly using a POC assay, and results are comparable to those obtained by the highly sophisticated HPLC method. Immediate feedback regarding beta-carotene deficiency facilitates rapid and appropriate optimization of beta-carotene supplementation in feed.},
  language  = {en}
}
@article{MuellerAltenkampRailaetal.2011,
  author    = {M{\"u}ller, Kerstin E. and Altenkamp, Rainer and Raila, Jens and Schmidt, Daniel and Dietrich, Robert and Hurtienne, Andrea and Wink, Michael and Krone, Oliver and Brunnberg, Leo and Schweigert, Florian J.},
  title     = {Plasma concentration of alpha-tocopherol in different free-ranging birds of prey},
  series = {European journal of wildlife research},
  volume    = {57},
  journal   = {European journal of wildlife research},
  number    = {5},
  publisher = {Springer},
  address   = {New York},
  issn      = {1612-4642},
  doi       = {10.1007/s10344-011-0516-z},
  pages     = {1043 -- 1049},
  year      = {2011},
  abstract  = {In this study, we investigated the alpha-tocopherol plasma concentrations in healthy free-ranging nestlings of the white-tailed sea eagle (Haliaeetus albicilla) (n=32), osprey (Pandion haliaetus) (n=39), northern goshawk (Accipiter gentilis) (n=25), common buzzard (Buteo buteo) (n=31), and honey buzzard (Pernis apivorus) (n=18) as well as of free-ranging adults of the white-tailed sea eagle (n=10), osprey (n=31), and northern goshawk (n=45). alpha-Tocopherol plasma concentrations were determined by reverse-phase high-performance liquid chromatography. alpha-Tocopherol plasma concentrations in nestlings of osprey, white-tailed sea eagle, and northern goshawk did not differ significantly amongst the species, but the common buzzard and honey buzzard nestlings had significantly lower alpha-tocopherol plasma concentrations than nestlings of the other species (both P<0.001). Adult male ospreys and white-tailed sea eagles had significantly higher alpha-tocopherol concentrations compared to adult females (both P<0.005). Adult ospreys and northern goshawks had significantly higher alpha-tocopherol plasma concentrations compared to their nestlings (both P<0.001). In adult female northern goshawks, plasma concentrations of alpha-tocopherol increased significantly before egg laying (P<0.001). These results demonstrate alpha-tocopherol plasma concentrations in birds of prey to be species specific and influenced by age and reproductive status.},
  language  = {en}
}
@article{MuellerRailaAltenkampetal.2012,
  author    = {Mueller, K. and Raila, Jens and Altenkamp, Rainer and Schmidt, D. and Dietrich, R. and Hurtienne, Andrea and Wink, M. and Krone, O. and Brunnberg, Leo and Schweigert, Florian J.},
  title     = {Concentrations of retinol, 3,4-didehydroretinol, and retinyl esters in plasma of free-ranging birds of prey},
  series = {Journal of animal physiology and animal nutrition},
  volume    = {96},
  journal   = {Journal of animal physiology and animal nutrition},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0931-2439},
  doi       = {10.1111/j.1439-0396.2011.01219.x},
  pages     = {1044 -- 1053},
  year      = {2012},
  abstract  = {This study investigated vitamin A compounds in the plasma of healthy free-ranging Central European raptors with different feeding strategies. Plasma samples of nestlings of white-tailed sea eagle [white-tailed sea eagle (WTSE), Haliaeetus albicilla) (n = 32), osprey (Pandion haliaetus) (n = 39), northern goshawk (Accipiter gentilis) (n = 25), common buzzard (Buteo buteo) (n = 31), and honey buzzard (Pernis apivorus) (n = 18) and adults of WTSE (n = 10), osprey (n = 31), and northern goshawk (n = 45) were investigated with reversed-phase-high-performance liquid chromatography (RP-HPLC). In WTSE, northern goshawks and common buzzards retinol were the main plasma component of vitamin A, whilst in ospreys and honey buzzards, 3,4-didehydroretinol predominated. The median of the retinol plasma concentration in the nestlings group ranged from 0.12 to 3.80 mu M and in the adult group from 0.15 to 6.13 mu M. Median plasma concentrations of 3,4-didehydroretinol in nestlings ranged from 0.06 to 3.55 mu M. In adults, northern goshawks had the lowest plasma concentration of 3,4-didehydroretinol followed by WTSE and ospreys. The plasma of all investigated species contained retinyl esters (palmitate, oleate, and stearate). The results show considerable species-specific differences in the vitamin A plasma concentrations that might be caused by different nutrition strategies.},
  language  = {en}
}
@article{LoehrkeVierguthKanitzetal.2004,
  author    = {L{\"o}hrke, B. and Vierguth, T. and Kanitz, W. and G{\"o}llnitz, K. and Becker, F. and Hurtienne, Andrea and Schweigert, Florian J.},
  title     = {High milk yield in dairy cows associated with oxidant stress},
  issn      = {1328-925X},
  year      = {2004},
  language  = {en}
}
@article{LohrkeViergutzKanitzetal.2005,
  author    = {Lohrke, B. and Viergutz, L. and Kanitz, W. and Becker, F. and Gollnitz, K. and Hurtienne, Andrea and Schweigert, Florian J.},
  title     = {Relationship between oxidant stress and milk productivity in dairy cows},
  issn      = {0005-9366},
  year      = {2005},
  abstract  = {An imbalance between formation and detoxification of oxygen radicals leads to oxidant stress that may increase in more intense oxidative metabolism caused by a high intake of metabolizable energy to provide metabolic intermediates for the milk synthesis and secretion. This hypothesis was tested using dairy cows and the concentration of hydroperoxides in lipids (LHP) extracted from circulative lipoprotein particles of low and very low density (LDL and VLDL/chylomicrons) as oxidant stress indicator. The particles were prepared by ultracentrifugation of serum obtained by coccygeal bleeding (13 cows, 1. parity, n=8 and 2. parity, n=5, lactation stage, 53 +/- 1.4 days post partum) and purified by precipitation. Concentrations of LHP-LDL/mg Lipoprotein correlated significantly with daily milk yield (r = 0.73, P = 0.004) or daily milk energy output (r = 0.77, P = 0.003) in contrast to LHP of VLDL/chylomicron particles. Thus, some evidence was obtained for an almost linear, positive relationship between milk productivity and oxidant stress occurring in LDL},
  language  = {en}
}