@article{IckrathWagnerScherzadetal.2017,
  author    = {Ickrath, Pascal and Wagner, Martin and Scherzad, Agmal and Gehrke, Thomas and Burghartz, Marc and Hagen, Rudolf and Radeloff, Katrin and Kleinsasser, Norbert and Hackenberg, Stephan},
  title     = {Time-Dependent Toxic and Genotoxic Effects of Zinc Oxide Nanoparticles after Long-Term and Repetitive Exposure to Human Mesenchymal Stem Cells},
  series = {International Journal of Environmental Research and Public Health},
  volume    = {14},
  journal   = {International Journal of Environmental Research and Public Health},
  number    = {12},
  doi       = {10.3390/ijerph14121590},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169932},
  pages     = {1590},
  year      = {2017},
  abstract  = {Zinc oxide nanoparticles (ZnO-NP) are widely spread in consumer products. Data about the toxicological characteristics of ZnO-NP is still under controversial discussion. The human skin is the most important organ concerning ZnO-NP exposure. Intact skin was demonstrated to be a sufficient barrier against NPs; however, defect skin may allow NP contact to proliferating cells. Within these cells, stem cells are the most important toxicological target for NPs. The aim of this study was to evaluate the genotoxic and cytotoxic effects of ZnO-NP at low-dose concentrations after long-term and repetitive exposure to human mesenchymal stem cells (hMSC). Cytotoxic effects of ZnO-NP were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Furthermore, genotoxicity was evaluated by the comet assay. For long-term observation over 6 weeks, transmission electron microscopy (TEM) was applied. The results of the study indicated cytotoxic effects of ZnO-NP beginning at high concentrations of 50 μg/mL and genotoxic effects in hMSC exposed to 1 and 10 μg/mL ZnO-NP. Repetitive exposure enhanced cyto- but not genotoxicity. Intracellular NP accumulation was observed up to 6 weeks. The results suggest cytotoxic and genotoxic potential of ZnO-NP. Even low doses of ZnO-NP may induce toxic effects as a result of repetitive exposure and long-term cellular accumulation. This data should be considered before using ZnO-NP on damaged skin.},
  language  = {en}
}
@article{PolatKaiserWohllebenetal.2017,
  author    = {Polat, B{\"u}lent and Kaiser, Philipp and Wohlleben, Gisela and Gehrke, Thomas and Scherzad, Agmal and Scheich, Matthias and Malzahn, Uwe and Fischer, Thomas and Vordermark, Dirk and Flentje, Michael},
  title     = {Perioperative changes in osteopontin and TGFβ1 plasma levels and their prognostic impact for radiotherapy in head and neck cancer},
  series = {BMC Cancer},
  volume    = {17},
  journal   = {BMC Cancer},
  number    = {6},
  doi       = {10.1186/s12885-016-3024-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157529},
  year      = {2017},
  abstract  = {Background: In head and neck cancer little is known about the kinetics of osteopontin (OPN) expression after tumor resection. In this study we evaluated the time course of OPN plasma levels before and after surgery. Methods: Between 2011 and 2013 41 consecutive head and neck cancer patients were enrolled in a prospective study (group A). At different time points plasma samples were collected: T0) before, T1) 1 day, T2) 1 week and T3) 4 weeks after surgery. Osteopontin and TGFβ1 plasma concentrations were measured with a commercial ELISA system. Data were compared to 131 head and neck cancer patients treated with primary (n = 42) or postoperative radiotherapy (n = 89; group B1 and B2). Results: A significant OPN increase was seen as early as 1 day after surgery (T0 to T1, p < 0.01). OPN levels decreased to base line 3-4 weeks after surgery. OPN values were correlated with postoperative TGFβ1 expression suggesting a relation to wound healing. Survival analysis showed a significant benefit for patients with lower OPN levels both in the primary and postoperative radiotherapy group (B1: 33 vs 11.5 months, p = 0.017, B2: median not reached vs 33.4, p = 0.031). TGFβ1 was also of prognostic significance in group B1 (33.0 vs 10.7 months, p = 0.003). Conclusions: Patients with head and neck cancer showed an increase in osteopontin plasma levels directly after surgery. Four weeks later OPN concentration decreased to pre-surgery levels. This long lasting increase was presumably associated to wound healing. Both pretherapeutic osteopontin and TGFβ1 had prognostic impact.},
  language  = {en}
}