The hazard assessment of nanostructured CeO [sub] 2-based mixed oxides on the zebrafish Danio rerio under environmentally relevant UV-A exposureAlbin Pintar
, Ilja Gasan Osojnik Črnivec
, Petar Djinović
, Anita Jemec
Abstract: The effect of nanomaterials on biota under realistic environmental conditions is an important question. However, there is still a lack of knowledge on how different illumination conditions alter the toxicity of some photocatalytic nanomaterials. We have investigated how environmentally relevant UV-A exposure (intensity 8.50 ± 0.61 W/m2, exposure dose 9.0 J/cm2) affected the toxicity of cerium oxide (CeO2)-based nanostructured materials to the early-life stages of zebrafish Danio rerio. Pure cerium oxide (CeO2), copper–cerium (CuO–CeO2) (with a nominal 10, 15 and 20 mol.% CuO content), cerium–zirconium (CeO2–ZrO2) and nickel and cobalt (Ni–Co) deposited over CeO2–ZrO2 were tested. It was found that under both illumination regimes, none of the tested materials affected the normal development or induced mortality of zebrafish early-life stages up to 100 mg/L. Only in the case of CuO–CeO2, the growth of larvae was decreased (96 h LOEC values for CuCe10, CuCe15 and CuCe20 were 50, 50 and 10 mg/L, respectively). To conclude, CeO2-based nanostructured materials are not severely toxic to zebrafish and environmentally relevant UV-A exposure does not enhance their toxicity.
Keywords: Nickel cobalt nanocrystalline catalysts, UV-A phototoxicity, UV-shielding, zebrafish
DiRROS - Published: 16.12.2014; Views: 8514; Downloads: 389
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Quantitative, absolute count-based T cell analysis of CD69 upregulation as a new methodology for in vitro diagnosis of delayed-type nickel hypersensitivityAna Koren
, Mira Šilar
, Helena Rupnik
, Mihaela Zidarn
, Peter Korošec
Abstract: Background: T cells play a major role in delayed-type hypersensitivity reactions. Their reactivity can be assessed by measuring the upregulation of the activation marker CD69, followed by proliferation and cytokine production. The aim of our study was to develop a novel, whole blood-based, quantitative, absolute count activation index (AI) analysis of CD69 upregulation on different subsets of T cells in nickel hypersensitive patients and compare it with the previously reported approaches. Methods: Ten patients with nickel allergy and nine healthy controls were included. CD69 expression of CD3+, CD3+CD4+ and CD3+CD8+ T cells in heparinized blood was determined with flow cytometry after incubation with nickel sulfate for 48 h. The absolute cell count of CD69+ cells was determined with microbeads. The production of the cytokines IL-2, IL-5, IL-13, and IFN-[gamma] was determined after nickel sulfate stimulation of PBMNCs for 48 h. Results: We showed that the most sensitive methodology is the absolute AI, which was calculated as the ratio between the absolute count of CD69-positive T cells stimulated with nickel and the absolute count of CD69-positive T cells in non-stimulated blood. This novel quantitative approach was more discriminative than the previously reported approaches in which T cell CD69 percentage AI and cytokine production are measured. Conclusions: Our results demonstrated that measuring the absolute CD69 AI is an accurate new approach to quantify antigen-specific T cells in the blood of patients with hypersensitivity reactions to nickel. This approach may be useful for better in vitro assessment of patients with delayed-type hypersensitivity reactions.
Keywords: allergy and immunology, delayed hypresensitivity, nickel, blood, CD antigenes, CD69
DiRROS - Published: 18.11.2020; Views: 691; Downloads: 125