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- ItemCell stimulation versus cell death induced by sequential treatments with pulsed electric fields and cold atmospheric pressure plasma(San Francisco, California, US : PLOS, 2018) Steuer, Anna; Wolff, Christina M.; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Kolb, Juergen F.Pulsed electric fields (PEFs) and cold atmospheric pressure plasma (CAP) are currently both investigated for medical applications. The exposure of cells to PEFs can induce the formation of pores in cell membranes and consequently facilitate the uptake of molecules. In contrast, CAP mainly acts through reactive species that are generated in the liquid environment. The objective of this study was to determine, if PEFs combined with plasma-treated cell culture medium can mutually reinforce effects on viability of mammalian cells. Experiments were conducted with rat liver epithelial WB-F344 cells and their tumorigenic counterpart WB-ras for a direct comparison of non-tumorigenic and tumorigenic cells from the same origin. Viability after treatments strongly depended on cell type and applied field strength. Notably, tumorigenic WB-ras cells responded more sensitive to the respective treatments than non-tumorigenic WB-F344 cells. More cells were killed when plasma-treated medium was applied first in combination with treatments with 100-μs PEFs. For the reversed treatment order, i.e. application of PEFs first, the combination with 100-ns PEFs resulted in a stimulating effect for non-tumorigenic but not for tumorigenic cells. The results suggest that other mechanisms, besides simple pore formation, contributed to the mutually reinforcing effects of the two methods.
- ItemScanning electron microscopy preparation of the cellular actin cortex: A quantitative comparison between critical point drying and hexamethyldisilazane drying(San Francisco, California, US : PLOS, 2021) Schu, Moritz; Terriac, Emmanuel; Koch, Marcus; Paschke, Stephan; Lautenschläger, Franziska; Flormann, Daniel A.D.The cellular cortex is an approximately 200-nm-thick actin network that lies just beneath the cell membrane. It is responsible for the mechanical properties of cells, and as such, it is involved in many cellular processes, including cell migration and cellular interactions with the environment. To develop a clear view of this dense structure, high-resolution imaging is essential. As one such technique, electron microscopy, involves complex sample preparation procedures. The final drying of these samples has significant influence on potential artifacts, like cell shrinkage and the formation of artifactual holes in the actin cortex. In this study, we compared the three most used final sample drying procedures: critical-point drying (CPD), CPD with lens tissue (CPD-LT), and hexamethyldisilazane drying. We show that both hexamethyldisilazane and CPD-LT lead to fewer artifactual mesh holes within the actin cortex than CPD. Moreover, CPD-LT leads to significant reduction in cell height compared to hexamethyldisilazane and CPD. We conclude that the final drying procedure should be chosen according to the reduction in cell height, and so CPD-LT, or according to the spatial separation of the single layers of the actin cortex, and so hexamethyldisilazane.