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- Cyto-genotoxic effects of distinct micro/nanocelluloses in human osteoblastic and mice fibroblastic cellsPublication . Ventura, Célia; Marques, Catarina; Cadete, João; Vilar, Madalena; Pedrosa, J.F.S.; Pinto, P.; Rosa, R.R.; Fernandes, S.N.; Godinho, M.H.; Ferreira, P.J.T.; Louro, Henriqueta; Silva, Maria JoãoThe unique characteristics of micro/nanocelluloses (MNCs) have been boosting their use in a wide variety of industrial and biomedical applications. With the expected decrease of their production cost, it is likely to observe an even faster growing adoption of these materials in the coming years. With the increasing use of MNCs comes an increased likelihood of human exposure to these materials, raising concerns about potential human health effects. The number of studies on the potential adverse effects of MNCs is still scarce and sometimes inconclusive. The aim of the present study is to shed some light on the impact of human exposure to cellulose-based nanomaterials. For that, three MNCs were produced from bleached Eucalyptus kraft pulp using different pretreatments. A microfibrillated (CMF) and a nanofibrillated cellulose (CNF) were respectively obtained by enzymatic and TEMPO-mediated oxidation pretreatments followed by high-pressure homogenization. In addition, cellulose nanocrystals (CNC) were obtained by acid hydrolysis with diluted sulfuric acid. The potential cytotoxicity of the MNCs was evaluated in vitro in two mammalian cell lines (human MG-63 osteoblasts and mice V79 lung fibroblasts) by the MTT and the clonogenic assays, and the genotoxicity was assessed by the micronucleus assay. Cytotoxicity was observed by the clonogenic assay in V79 cells, particularly for CNC, but not by the MTT assay. CNF induced micronuclei in both cell lines and nucleoplasmic bridges in MG-63 cells. CMF and CNC induced micronuclei and nucleoplasmic bridges in MG-63 cells, but not in V79 cells. From the results, it was concluded that under the tested conditions all MNCs present cytotoxicity and genotoxicity, although at different concentration levels, which may be related to their physicochemical differences, to the availability for cell uptake, and to differences in the DNA damage response of the cell model.
- Microbial Source Tracking as a Method of Determination of Beach Sand ContaminationPublication . Valério, Elisabete; Santos, Maria Leonor; Teixeira, Pedro; Matias, Ricardo; Mendonça, João; Ahmed, Warish; Brandão, JoãoBeach sand may act as a reservoir for numerous microorganisms, including enteric pathogens. Several of these pathogens originate in human or animal feces, which may pose a public health risk. In August 2019, high levels of fecal indicator bacteria (FIB) were detected in the sand of the Azorean beach Prainha, Terceira Island, Portugal. Remediation measures were promptly implemented, including sand removal and the spraying of chlorine to restore the sand quality. To determine the source of the fecal contamination, during the first campaign, supratidal sand samples were collected from several sites along the beach, followed by microbial source tracking (MST) analyses of Bacteroides marker genes for five animal species, including humans. Some of the sampling sites revealed the presence of marker genes from dogs, seagulls, and ruminants. Making use of the information on biological sources originating partially from dogs, the municipality enforced restrictive measures for dog-walking at the beach. Subsequent sampling campaigns detected low FIB contamination due to the mitigation and remediation measures that were undertaken. This is the first case study where the MST approach was used to determine the contamination sources in the supratidal sand of a coastal beach. Our results show that MST can be an essential tool to determine sources of fecal contamination in the sand. This study shows the importance of holistic management of beaches that should go beyond water quality monitoring for FIB, putting forth evidence for beach sand monitoring.