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A battery of in vivo and in vitro tests useful for genotoxic pollutant detection in surface waters
No full textAbstract
Since the 1980s, stricter water quality regulations have been promulgated in many countries
throughout the world. We discuss the application of a battery of both in vivo and in vitro
genotoxicity tests on lake water as a tool for a more complete assessment of surface water quality.
The lake water concentrated by adsorption on C18 silica cartridges were used for the following in
vitro biological assays: gene conversion, point mutation, mitochondrial DNA mutability assays on
the diploid Saccharomyces cerevisiae D7 strain, with or without endogenous P450 complex
induction; DNA damage on fresh human leukocytes by the comet. Toxicity testing on yeast and
human cells was also performed. In vivo genotoxicity was determined by the comet assay on two
well-established bio-indicator organisms of water quality (Cyprinus carpio erythrocytes and
Dreissena polymorpha haemocytes) exposed in situ. The in vivo experiments and the water
samplings were carried out during different campaigns to detect seasonal variations of both the
water contents and physiological state of the animals. Temperature and oxygen level seasonal
variations and different pollutant contents in the lake water appeared to affect the DNA migration in
carp and zebra mussel cells. Seasonal variability of lake water quality was also evident in the in
vitro genotoxicity and cytotoxicity tests, with regards to water pollutant quantity and quality (directacting
compounds or indirect-acting compounds on yeast cells). However, the measured biological
effects did not appear clearly related to the physical-chemical characteristics of lake waters.
Therefore, together with the conventional chemical analysis, mutagenicity/genotoxicity assays
should be included as additional parameters in water quality monitoring programs: their use could
permit the quantification of mutagenic hazard in surface waters
Role of glutamate receptors in tetrabrominated diphenyl ether (BDE-47) neurotoxicity in mouse cerebellar granule neurons.
No full textA mechanistic view of polybrominated diphenyl ether (PBDE) developmental neurotoxicity
No full textPolybrominated diphenyl ethers (PBDEs), extensively used in the past few decades as flame retardants in a variety of consumer products, have become world-wide persistent environmental pollutants. Levels in North America are usually higher than those in Europe and Asia, and body burden is 3-to-9-fold higher in infants and toddlers than in adults. The latter has raised concern for potential developmental toxicity and neurotoxicity of PBDEs. Experimental studies in animals and epidemiological observations in humans suggest that PBDEs may be developmental neurotoxicants. Pre- and/or post-natal exposure to PBDEs may cause long-lasting behavioral abnormalities, particularly in the domains of motor activity and cognition. The mechanisms underlying the developmental neurotoxic effects of PBDEs are not known, though several hypotheses have been put forward. One general mode of action relates to the ability of PBDEs to impair thyroid hormone homeostasis, thus indirectly affecting the developing brain. An alternative or additional mode of action involves a direct effect of PBDEs on nervous system cells; PBDEs can cause oxidative stress-related damage (DNA damage, mitochondrial dysfunction, apoptosis), and interfere with signal transduction (particularly calcium signaling), and with neurotransmitter systems. Important issues such as bioavailability and metabolism of PBDEs, extrapolation of results to low level of exposures, and the potential effects of interactions among PBDE congeners and between PBDEs and other contaminants also need to be taken into account
Cytotoxic and genotoxic potential of drinking water: a comparison between two different concentration methods.
No full textThe level of exposure to hazardous compounds through drinking water is low but it is maintained throughout
life, therefore representing a risk factor for human health. The use of techniques averaging the consumer's
exposure over time could be more useful than relying on intermittent grab samples that may misrepresent
average tap water concentrations due to short-term temporal variability. In this study, we compared the
induction of in vitro cytotoxic and genotoxic effects (DNA damage by the comet assay) in relation to different
sampling methods, i.e. exposure over time (semipermeable membrane devices, SPMDs, exposed for 30
days) or intermittent grab samples (5 weekly water sampling, C18 concentration). Waters with different
chemical characteristics were sampled to test the sensitivity of the two methods. We did not found any
positive correlation between the biological findings and water chemical parameters. SPMD extracts induced
a significantly greater DNA damage than C18. The different behaviour was specially found for the water
samples with a low level of organic compounds and when C18 extracts were highly cytotoxic. Our findings
suggest that SPMD could be of a great interest in assessing genotoxic contaminants in both raw and
drinking water, with great suitability for continuous monitoring. Furthermore, the results of this study have
confirmed the great importance of the biological assays in evaluating the effects of a complex mixture such
as water in addition to the conventional chemical examination of water quality
Involvement of histamine H1 and H4 receptors in a murine model of acute skin inflammation and pruritus
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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