1,720,957 research outputs found
Metalli e prodotti cosmetici: tracce inevitabili e rischio accettabile
No full textNella caratterizzazione del rischio bisogna prendere in considerazione due componenti: la tossicità intrinseca della sostanza e l’entità dell’esposizione.
Nel caso dell’esposizione a sostanze potenzialmente tossiche contenute in prodotti cosmetici, gli aspetti da valutare sono quelli relativi a una tossicità locale di tipo cutaneo (dovuti quindi ad un effetto acuto di tipo irritativo o sensibilizzante sul sito di applicazione, per esempio palpebre nel caso degli ombretti, o labbra per il rossetto), o quelli sistemici verificabili anche in tempi successivi all’applicazione, dovuti all’assorbimento della sostanza e alla sua distribuzione, attraverso il sangue, a tutto l’organismo.
Per ogni elemento contaminante, quali i metalli ritrovabili come tracce all’interno dei prodotti cosmetici, devono essere presi in considerazione la tossicità intrinseca, riscontrata a qualsiasi dose in modelli animali o cellulari, gli effetti cutanei correlati alla dose, la dose assorbita e la relazione fra quest’ultima ed eventuali effetti osservati sperimentalmente o su popolazione, cercando di identificare dei livelli di sicurezza d’uso.
In questo esercizio l’approccio verrà fatto a ritroso: si cercherà di stabilire se le trace tecnologicamente inevitabili di alcuni metalli (pimbo, cromo, arsenico, cadmio) all’interno degli ingredienti cosmetici e conseguentemente dei prodotti finite, presentano un rischio per la salute dei consumatori in diversi scenari di esposizione
Metals in cosmetics : an a posteriori safety evaluation
No full textAccording to EU Regulation No. 1223/2009/CE cosmetic products for daily use can contain '. technically unavoidable traces' of metals. This definition is too vague. Authorities should set well-defined limits, considering the risks associated with metal contamination of personal care products (PCPs).This paper characterizes the risk arising from a number of metals (antimony, arsenic, cadmium, cobalt, chromium, mercury, nickel, lead) that may occur in 'unavoidable traces" in raw materials and, consequently, in PCPs. A 'worst case scenario' was adopted, based on the following assumptions: (i) the individual ingredients contained the maximum amount in traces allowed for each metal; (ii) the hypothetical PCP was produced exclusively with that single ingredient; (iii) when absorption through the skin was not known, data related to oral absorption were used. Risk characterization was performed calculating the Systemic Exposure Dosage (SED) and the Margin of Safety (MoS=NOAEL or BMDL10/SED). Exposure to the allegedly 'technically unavoidable' maximum amounts of metals in cosmetic ingredients resulted in MoSs exceeding 100 (safety threshold) with one exception. This suggests that the availability of experimental dermal absorption rates could enable significant improvement in MoS, thus increasing safety levels. Although results are reassuring, the authors recommend minimization of contamination, according to the state of the art of manufacturing methods
EARLY MATERNAL DEPRIVATION MODULATES DISTRIBUTION OF INTERLEUKIN-1 AND NMDA RECEPTORS AT THE SYNAPTIC MEMBRANE
No full textSevere stress early in life induces changes in neuronal function, determining a different setting in synaptic organization, which could be implicated in promoting an adaptive response under physiological conditions and/or in stress-related disorders later in life.
The pro-inflammatory citokine Interleukin-1β (IL-1β) has been recognised as a central regulator of stress responses. IL-1β signal transduction in neurons occurs through the IL-1 receptor type I (IL-1-RI). We recently demonstrated in primary hippocampal neurons that IL-1RI is enriched at synaptic sites, where it co-localizes with, and binds to the GluN2B subunit of NMDA receptor (NMDAR) suggesting a functional interaction. In a model of maternal deprivation (MD) we investigated the expression and distribution at the post-synaptic site of IL-1RI, together with the GluN2A and GluN2B subunits of the NMDAR and the GluR1 and GluR2 subunits of the AMPA receptors, in the hippocampus and pre-frontal cortex of male and female rats.
24h of MD at PND9 significantly increases the levels of IL-1RI, as well as IL-1RI interaction with GluN2B, at the synapsis of hippocampal neurons at PND 45. This effect is sex-dependent, occurring only in male rats. No such alterations were observed in the prefrontal cortex as well as no enrichment of GluN2B and GluN2A at the synapse is evident in PND 45 MD rats. On the contrary, both GluR1 and GluR2 subunits of the AMPAR at the hippocampal synapse were reduced in 45 PND MD rats. The decrease of AMPAR subunits at the post-synapses of male MD rats was coupled to a decreased phosphorylation at Tyr-1472 of the GluN2B subunit of the NMDAR.
These data reveal a profound modification in the receptors organization at the post-synapses induced by MD in male rats hippocampi, suggesting the setting for an immature synapse which possibly affect neuronal sensitivity to both IL-1b and the glutamatergic neurotransmission
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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