Nanotoxicology in Safety Assessment of Nanomaterials

For safety assessment of nanomaterials (NMs), in vitro genotoxicity data based on welldesigned experiments is required. Metal-based NMs are amongst the most used in consumer products. In this chapter, we report results for three metal-based NMs, titanium dioxide (NM- 100), cerium dioxide (NM-212) and silver (NM-302) in V79 cells, using a set of in vitro genotoxicity assays covering different endpoints: the medium-throughput comet assay and its modified version (with the enzyme formamidopyrimidine DNA glycosylase, Fpg), measuring DNA strand beaks (SBs) and oxidized purines, respectively; the micronucleus (MN) assay, assessing chromosomal damage; and the Hprt gene mutation test. The results generated by this test battery showed that all NMs displayed genotoxic potential. NM-100 induced DNA breaks, DNA oxidation damage and point mutations but not chromosome instability. NM-212 increased the level of DNA oxidation damage, point mutations and increased the MN frequency at the highest concentration tested. NM-302 was moderately cytotoxic and induced gene mutations, but not DNA or chromosome damage. In conclusion, the presented in vitro genotoxicity testing strategy allowed the identification of genotoxic effects caused by three different metal-based NMs, raising concern as to their impact on human health. The results support the use of this in vitro test battery for the genotoxicity assessment of NMs, reducing the use of more expensive, time-consuming and ethically demanding in vivo assays, in compliance with the 3 R’s.This research was co-funded by the EC FP7 NANoREG (Grant Agreement NMP4-LA-2013–310584), the EC QualityNano Research Infrastructure project (Grant Agreement No: INFRA-2010-262163), through the QualityNano Transnational Access fellowships [NILU-TAF-410 and NILU-TAF-403] attributed to N. Vital and M. J. Silva and by the Portuguese Foundation for Science and Technology through ToxOmics (UIDB/00009/2020; UIDP/00009/2020). N. Vital work is also supported by the Portuguese Foundation for Science and Technology PhD Scholarship 2020.07168.BD.info:eu-repo/semantics/publishedVersio

Contribution to the hazard assessment of benchmark metallic nanomaterials through a set of in vitro genotoxicity assays

Background and Aim: Metall-based nanomaterials (NMs) are among the most commonly applied manufactured nanomaterials (NM). Regardless of the considerable efforts to assess their safety, the presently available data do not allow for general and consistent conclusions. Moreover, the validity of the classical in vitro testing systems for NMs hazard assessment has been questioned and needs confirmation. The present study aimed at evaluating the toxicity of three benchmark metallic NMs - titanium dioxide (NM-100),cerium dioxide (NM-212) and nanosilver - with different physicochemical properties, using a battery of in vitro genotoxicity assays, in an attempt to characterize their toxicity profile.This research was partially supported by funding through UID/BIM/00009/2013 (Centre for Toxicogenomics and Human Health, ToxOmics), Fundação para a Ciência e Tecnologia, Portugal, by the FP7 Project NANoREG (GA 310584) and by INSA (2013DGH860).N/

Potent protection of gallic acid against DNA oxidation: Results of human and animal experiments

a b s t r a c t Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a constituent of plant derived foods, beverages and herbal remedies. We investigated its DNA protective properties in a placebo controlled human intervention trial in single cell gel electrophoresis experiments. Supplementation of drinking water with GA (12.8 mg/person/d) for three days led to a significant reduction of DNA migration attributable to oxidised pyrimidines (endonuclease III sensitive sites) and oxidised purines (formamidopyrimidine glycosylase sensitive sites) in lymphocytes of healthy individuals by 75% and 64% respectively. Also DNA damage caused by treatment of the cells with reactive oxygen species (ROS) was reduced after GA consumption (by 41%). These effects were paralleled by an increase of the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathion-S-transferase-) and a decrease of intracellular ROS concentrations in lymphocytes, while no alterations of the total antioxidant capacity (TAC), of malondialdehyde levels in serum and of the urinary excretion of isoprostanes were found. Experiments with rats showed that GA reduces oxidatively damaged DNA in lymphocytes, liver, colon and lungs and protects these organs against ␥-irradiation-induced strand breaks and formation of oxidatively damaged DNAbases. Furthermore, the number of radiation-induced preneoplastic hepatic foci was decreased by 43% after oral administration of the phenolic. Since we did not find alterations of the TAC in plasma and lipid peroxidation of cell membranes but intracellular effects it is likely that the antioxidant properties of GA seen in vivo are not due to direct scavenging of radicals but rather to indirect mechanisms (e.g. protection against ROS via activation of transcription factors). As the amount of GA used in the intervention trial is similar to the daily intake in Middle Europe (18 mg/person/day), our findings indicate that it may contribute to prevention of formation of oxidatively damaged DNA in humans

Genetic variation associated with chromosomal aberration frequency : A genome-wide association study

Chromosomal aberrations (CAs) in human peripheral blood lymphocytes (PBL) measured with the conventional cytogenetic assay have been used for human biomonitoring of genotoxic exposure for decades. CA frequency in peripheral blood is a marker of cancer susceptibility. Previous studies have shown associations between genetic variants in metabolic pathway, DNA repair and major mitotic checkpoint genes and CAs. We conducted a genome-wide association study on 576 individuals from the Czech Republic and Slovakia followed by a replication in two different sample sets of 482 (replication 1) and 1288 (replication 2) samples. To have a broad look at the genetic susceptibility associated with CA frequency, the sample sets composed of individuals either differentially exposed to smoking, occupational/environmental hazards, or they were untreated cancer patients. Phenotypes were divided into chromosome- and chromatid-type aberrations (CSAs and CTAs, respectively) and total chromosomal aberrations (CAtot). The arbitrary cutoff point between individuals with high and low CA frequency was 2% for CAtot and 1% for CSA and CTA. The data were analyzed using age, sex, occupation/cancer and smoking history as covariates. Altogether 11 loci reached the P-value of 10−5 in the GWAS. Replication 1 supported the association of rs1383997 (8q13.3) and rs2824215 (21q21.1) in CAtot and rs983889 (5p15.1) in CTA analysis. These loci were found to be associated with genes involved in mitosis, response to environmental and chemical factors and genes involved in syndromes linked to chromosomal abnormalities. Identification of new genetic variants for the frequency of CAs offers prediction tools for cancer risk in future. 2018 Wiley Periodicals, Inc

Practical considerations for conducting ecotoxicity test methods with manufactured nanomaterials: what have we learnt so far?

This review paper reports the consensus of a technical workshop hosted by the European network, NanoImpactNet (NIN). The workshop aimed to review the collective experience of working at the bench with manufactured nanomaterials (MNMs), and to recommend modifications to existing experimental methods and OECD protocols. Current procedures for cleaning glassware are appropriate for most MNMs, although interference with electrodes may occur. Maintaining exposure is more difficult with MNMs compared to conventional chemicals. A metal salt control is recommended for experiments with metallic MNMs that may release free metal ions. Dispersing agents should be avoided, but if they must be used, then natural or synthetic dispersing agents are possible, and dispersion controls essential. Time constraints and technology gaps indicate that full characterisation of test media during ecotoxicity tests is currently not practical. Details of electron microscopy, dark-field microscopy, a range of spectroscopic methods (EDX, XRD, XANES, EXAFS), light scattering techniques (DLS, SLS) and chromatography are discussed. The development of user-friendly software to predict particle behaviour in test media according to DLVO theory is in progress, and simple optical methods are available to estimate the settling behaviour of suspensions during experiments. However, for soil matrices such simple approaches may not be applicable. Alternatively, a Critical Body Residue approach may be taken in which body concentrations in organisms are related to effects, and toxicity thresholds derived. For microbial assays, the cell wall is a formidable barrier to MNMs and end points that rely on the test substance penetrating the cell may be insensitive. Instead assays based on the cell envelope should be developed for MNMs. In algal growth tests, the abiotic factors that promote particle aggregation in the media (e.g. ionic strength) are also important in providing nutrients, and manipulation of the media to control the dispersion may also inhibit growth. Controls to quantify shading effects, and precise details of lighting regimes, shaking or mixing should be reported in algal tests. Photosynthesis may be more sensitive than traditional growth end points for algae and plants. Tests with invertebrates should consider non-chemical toxicity from particle adherence to the organisms. The use of semi-static exposure methods with fish can reduce the logistical issues of waste water disposal and facilitate aspects of animal husbandry relevant to MMNs. There are concerns that the existing bioaccumulation tests are conceptually flawed for MNMs and that new test(s) are required. In vitro testing strategies, as exemplified by genotoxicity assays, can be modified for MNMs, but the risk of false negatives in some assays is highlighted. In conclusion, most protocols will require some modifications and recommendations are made to aid the researcher at the bench. [Authors]]]> Nanostructures; Toxicity Tests; Ecotoxicology/methods; Guidelines; eng https://serval.unil.ch/resource/serval:BIB_5FCE25CBF6A9.P001/REF.pdf http://nbn-resolving.org/urn/resolver.pl?urn=urn:nbn:ch:serval-BIB_5FCE25CBF6A95 info:eu-repo/semantics/altIdentifier/urn/urn:nbn:ch:serval-BIB_5FCE25CBF6A95 info:eu-repo/semantics/submittedVersion info:eu-repo/semantics/openAccess Copying allowed only for non-profit organizations https://serval.unil.ch/disclaimer application/pdf oai:serval.unil.ch:BIB_5FCE8EA1AD9C 2022-02-19T02:22:28Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_5FCE8EA1AD9C Apprendre à suivre une règle : jeux d'alternance et constitution du sujet moral Erard, Y. info:eu-repo/semantics/bookPart incollection 2007 Morale et évolution biologique oai:serval.unil.ch:BIB_5FC219D991AA 2022-02-19T02:22:28Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_5FC219D991AA Réflexion sur la réduction de peine en cas de détention illicite Parein, Loïc info:eu-repo/semantics/article article 2015 Revue de l'avocat, vol. 4, no. 15, pp. 166-170 info:eu-repo/semantics/altIdentifier/pissn/1422-5778 fre https://serval.unil.ch/resource/serval:BIB_5FC219D991AA.P001/REF.pdf info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/restrictedAccess Restricted: indefinite embargo Copying allowed only for non-profit organizations https://serval.unil.ch/disclaimer application/pdf oai:serval.unil.ch:BIB_5FC2874DDD0E 2022-02-19T02:22:28Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_5FC2874DDD0E Radial Ultrasound-Assisted Transbronchial Biopsy: A New Diagnostic Approach for Non-Resolving Pulmonary Infiltrates in Neutropenic Hemato-Oncological Patients. info:doi:10.1007/s00408-016-9947-3 info:eu-repo/semantics/altIdentifier/doi/10.1007/s00408-016-9947-3 info:eu-repo/semantics/altIdentifier/pmid/27704258 Bernasconi, M. Casutt, A. Koutsokera, A. Letovanec, I. Tissot, F. Nicod, L.P. Lovis, A. info:eu-repo/semantics/article article 2016-12 Lung, vol. 194, no. 6, pp. 917-921 info:eu-repo/semantics/altIdentifier/eissn/1432-1750 urn:issn:0341-2040 <![CDATA[The role of radial-endobronchial ultrasound (R-EBUS) assisted transbronchial biopsy (TBB) for the diagnosis of peripheral pulmonary lesions is well established. However, no study has addressed its safety and value in hemato-oncological patients presenting with non-resolving infiltrates during persistent febrile neutropenia. To assess safety and feasibility of R-EBUS assisted TBB in severe thrombocytopenic and neutropenic patients. Over a period of 18 months, eight patients were assessed with R-EBUS assisted TBB after adequate platelet transfusion. This technique allowed precise localisation and sampling of the pulmonary lesions in seven of eight patients. In the seven patients, R-EBUS assisted TBB enabled treatment optimization. Invasive fungal infection was diagnosed in four patients, idiopathic acute fibrinous and organising pneumonia in three patients, and a granulomatous inflammation of undetermined origin in one patient. Importantly, no complications, such as bleeding, were observed. R-EBUS assisted TBB is a promising and safe procedure for the evaluation of nonresolving pulmonary infiltrates in febrile neutropenic hemato-oncological patients

The hCOMET project: international database comparison of results with the comet assay in human biomonitoring (baseline frequency of DNA damage and effect of main confounders)

The alkaline comet assay, or single cell gel electrophoresis, is one of the most popular methods for assessing DNA damage in the human population. One of the open issues concerning this assay is the identification of those factors that can explain the large inter-individual and inter-laboratory variation. International collaborative initiatives such as the hCOMET project - a COST Action launched in 2016 - represent a valuable tool to meet this challenge. The aims of hCOMET were to establish reference values for the level of DNA damage in humans, to investigate the effect of host factors, lifestyle, and exposure to genotoxic agents, and to compare different sources of assay variability. A database of 19,320 subjects was generated, pooling data from 105 studies run by 44 laboratories in 26 countries between 1999 and 2019. A mixed random effect log-linear model, in parallel with a classic meta-analysis, was applied to take into account the extensive heterogeneity of data, due to descriptor, specimen, and protocol variability. As a result of this analysis interquartile intervals of DNA strand breaks (which includes alkali-labile sites) were reported for tail intensity, tail length, and tail moment (comet assay descriptors). A small variation by age was reported in some datasets, suggesting higher DNA damage in oldest age-classes, while no effect could be shown for sex or smoking habit, although the lack of data on heavy smokers has still to be considered. Finally, highly significant differences in DNA damage were found for most exposures investigated in specific studies. In conclusion, these data, which confirm that DNA damage measured by the comet assay is an excellent biomarker of exposure in several conditions, may contribute to improving the quality of study design and to the standardization of results of the comet assay in humans populations.info:eu-repo/semantics/publishedVersio

The hCOMET project: International database comparison of results with the comet assay in human biomonitoring. Baseline frequency of DNA damage and effect of main confounders

The alkaline comet assay, or single cell gel electrophoresis, is one of the most popular methods for assessing DNA damage in human population. One of the open issues concerning this assay is the identification of those factors that can explain the large inter-individual and inter-laboratory variation. International collaborative initiatives such as the hCOMET project - a COST Action launched in 2016 - represent a valuable tool to meet this challenge. The aims of hCOMET were to establish reference values for the level of DNA damage in humans, to investigate the effect of host factors, lifestyle and exposure to genotoxic agents, and to compare different sources of assay variability. A database of 19,320 subjects was generated, pooling data from 105 studies run by 44 laboratories in 26 countries between 1999 and 2019. A mixed random effect log-linear model, in parallel with a classic meta-analysis, was applied to take into account the extensive heterogeneity of data, due to descriptor, specimen and protocol variability. As a result of this analysis interquartile intervals of DNA strand breaks (which includes alkali-labile sites) were reported for tail intensity, tail length, and tail moment (comet assay descriptors). A small variation by age was reported in some datasets, suggesting higher DNA damage in oldest age-classes, while no effect could be shown for sex or smoking habit, although the lack of data on heavy smokers has still to be considered. Finally, highly significant differences in DNA damage were found for most exposures investigated in specific studies. In conclusion, these data, which confirm that DNA damage measured by the comet assay is an excellent biomarker of exposure in several conditions, may contribute to improving the quality of study design and to the standardization of results of the comet assay in human populations