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End date: 2019 × DDC: 610 × search.filters.applied.f.series: Clinical Plasma Medicine 14 (2019) ×

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    Cold physical plasma-induced oxidation of cysteine yields reactive sulfur species (RSS)
    (Amsterdam [u.a.] : Elsevier, 2019) Bruno, Giuliana; Heusler, Thea; Lackmann, Jan-Wilm; Woedtke, Thomas von; Weltmann, Klaus-Dieter; Wende, Kristian
    Purpose: Studying plasma liquid chemistry can reveal insights into their biomedical effects, i.e. to understand the direct and indirect processes triggered by the treatment in a model or clinical application. Due to the reactivity of the sulfur atom, thiols are potential targets for plasma- derived reactive species. Being crucial for protein function and redox signaling pathways, their controllable modification would allow expanding the application range. Additionally, models to control and standardize CAP sources are desired tools for plasma source design. Methods: Cysteine, a ubiquitous amino acid, was used as a tracer compound to scavenge the reactive species produced by an argon plasma jet (kINPen). The resulting product pattern was identified via high-resolution mass spectrometry. The Ellman´s assay was used to screen CAP derived thiol consumption, and long-lived species deposition (hydrogen peroxide, nitrite, nitrate) was monitored in relation to the presence of cysteine. Results: The intensity of cysteine oxidation increased with treatment time and availability of oxygen in the feed gas. A range of products from cysteine was identified, in part indicative for certain treatment conditions. Several non-stable products occur transiently during the plasma treatment. Bioactive reactive sulfur species (RSS) have been found for mild treatment conditions, such as cysteine sulfoxides and cysteine-S-sulfonate. Considering the number of cysteine molecules in the boundary layer and the achieved oxidation state, short-lived species dominate in cysteine conversion. In addition, a boundary layer depletion of the tracer was observed. Conclusion: Translating these data into the in-vivo application, strong direct oxidation of protein thiol groups with subsequent changes in protein biochemistry must be considered. Plasma-derived RSS may in part contribute to the observed biomedical effects of CAP. Care must be taken to control the discharge parameter tightly as chemical dynamics at or in the liquid are subject to change easily. © 2019
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    Can the effect of cold physical plasma-derived oxidants be transported via thiol group oxidation?
    (Amsterdam [u.a.] : Elsevier, 2019) Heusler, Thea; Bruno, Giuliana; Bekeschus, Sander; Lackmann, Jan-Wilm; Woedtke, Thomas von; Wende, Kristian
    Purpose: Intra- and intercellular redox-signaling processes where found responsible in various physiological and pathological processes with cellular thiol groups as important signal transducers. Using cold atmospheric plasma (CAP), a similar oxidation pattern of thiol groups can be achieved. Hence, it must be clarified which role extracellular thiol groups play in mediating CAP effects and whether or not the effects of short-lived reactive species can be preserved in a molecule like cysteine. Methods: Physiological buffer solutions containing the amino acid cysteine were treated by an MHz argon plasma jet with molecular gas admixtures (kINPen) and transferred to cultured human keratinocytes. Cell proliferation, migratory activity, and metabolism were investigated. High-resolution mass spectrometry was used to estimate the impact of plasma generated species on thiol groups. Results: While treated physiologic cysteine concentrations showed no impact on cell behavior, artificially high concentrations decreased proliferation, migration and lactate secretion. GSH levels inside cells were stabilized. Conclusion: Extracellular thiol groups scavenge plasma-generated species and form a multitude of covalent modifications. Unexpectedly, human keratinocytes show only small functional consequences for treated physiologic cysteine concentrations. Results for high concentrated cysteine solutions indicate an improved cytostatic/cytotoxic impact by plasma treatment suggesting a potential application as a “preserving agent” of the chemical energy of plasma-derived species. © 2019 The Authors