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Preliminary evaluation of Aflatoxin M1 absorption/secretion profile on a Caco-2/TC7 clone, a human intestinal in vitro model, cultured on semi-permeable inserts
No full textAflatoxin M1 absorption and cytotoxicity on human intestinal in vitro model
No full textAflatoxinM1 (AFM1) is the principal hydroxylated Aflatoxin B1 (AFB1) metabolite and is detected in milk of mammals, after
consumption of feed contaminated with AFB1. As it is classified as probable human carcinogen (group 2B of the IARC), most
countries have regulated its maximum allowed levels in milk in order to reduce AFM1 risk (50 ng/kg the EU and 500 ng/kg in
the USA).
It was demonstrated that if AFB1 must be converted into its reactive epoxide to exert its effects, and the protein binding may
play an important role in its cytotoxicity. Conversely, the AFM1 epoxidation in human liver microsomes is very limited and
studies with human cell line (MCL5), expressing or not expressing cytochrome P450 enzymes, demonstrated a direct toxic
potential of AFM1 in absence of metabolic activation. For this reason, while AFM1 is generally considered a detoxification
product of AFB1 relatively to carcinogenicity and mutagenicity property, this is not always true for cytotoxicity activity.
Aim of this work is to evaluate the intestinal absorption of AFM1 using a human in vitro model, the Caco-2 cell line. Either the
parental Caco-2 cell line or its derived clone TC7, with higher metabolic competence, have been used. They were treated with
different concentrations of AFM1, that mirror the milk contamination level (0.3–32 nM corresponding to 10–10,000 ng/kg),
either in undifferentiated or in differentiated phase of growth. After 48 h of treatment in serum free medium, a dose dependent
absorption of AFM1 has been detected in both cell lines, especially in differentiated cells, while, no appreciable effects on cell
viability were observed, except for a general cellular suffering, revealed by LDH release, particularly evident in the
undifferentiated cells. As well, no metabolites or AFM1 conjugates have been detected.
The present results may be crucial for the evaluation of human risk to AFM1 exposure, in particular for children’s population,
due to their large use of milk and derivatives
Caco 2/TC7 cell line chracterization for intestinal absorption : a reliable in vitro model for the prediction of the oral dose fraction absorbed in human
No full textStudio in vitro con cellule caco-2 sul passaggio intestinale della Fumonisina B1 e dell'aminopentolo e ruolo della P-glicoproteina
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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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