1,720,955 research outputs found
Inquinanti genotossici nell'acqua
No full textL’inquinamento delle acque è un fenomeno globale entro il quale gli interrogativi posti dalla presenza di agenti mutageni, cancerogeni e teratogeni non possono essere considerati disgiuntamente da quelli relativi ad altri agenti tossici. I contaminanti genotossici presenti nell’ambiente acquatico possono essere individuati saggiando in vitro campioni ambientali e rilevando il danno genetico indotto dopo l’esposizione in organismi sentinella. Evidenze di questo tipo sono un segnale d’allarme per le potenziali conseguenze a lungo termine, definite dall’instaurarsi di cambiamenti nelle popolazioni, nelle specie e nelle comunità
degli organismi esposti. L’applicazione di biomarcatori di esposizione e di effetto in associazione alle
analisi chimiche può fornire le informazioni utili a individuare le fonti inquinanti e a stabilire adeguate misure
di protezione dei corpi idrici
Evaluation of chemopreventive activity of spinach extracts of plant grown in normal and hypoxic condition
No full textConsumption of fresh fruits and vegetables in the human diet is important to maintain a good health status and to prevent chronic diseases. It is well known that plant derived food is a powerful source of chemopreventive molecules such as antioxidants (polyphenols, catechins, etc..). Stress response represents a powerful stimulus for plants to produce metabolites with high value for human health. However, to date, this approach has not been extensively used yet, since too much mechanistic information is still lacking.
To find responses to this, we have investigated Spinach (Spinacia oleracea L., Chenopodiaceae) grown in normal or in hypoxic condition. Spinach leaves, commonly present in the human diet both raw and cooked, are a concentrate of bio-active compounds, molecules with a great medical value but rarely diffused in the Plant Kingdom such as phytoecdysteroids. The aqueous extracts of lyophilized Spinach leaves have been administered to tumoral colon cell line HT-29 to evaluate their chemoprotective effects. Cell viability assay (MTS) have been used to assess the antiproliferative activity while Comet Assay have been used to consider the cito-genotoxity of the extracts. The extracts of plants grown in hypoxic condition exert an antiproliferative activity greater than those grown in normal conditions. None of the extracts exerted any genotoxic activity when tested alone. To better understand the way of action of the antiproliferative activity we found, we tested the antioxidant activity of the extracts by the comet assay, after a co-treatment with a known oxidizing agent as H2O2, and the induction of apoptosis in HT-29 cell line by TUNEL assay.
Unexpectedly, the spinach extracts did not shown any antioxidants activity in vitro, meanwhile they seemed to induce apoptosis.
The analyses of the chemical composition of the extracts are ongoing, they could permit us to identify the chemical mixture present in the different extracts and which compound is responsible for the increased antiproliferative activity shown by the plants grown in hypoxia.
What we found does not confirm what reported by Moser that showed an antioxidant activity of spinach in in vivo studies. Taking into account these observations, we plan to simulate the digestion of the extracts to understand if the antioxidant activity could be due to a chemical modification of the original mixture
Antiproliferative and chemopreventive activity of Citrullus colocynthis Schrad extracts
No full textCitrullus colocynthis Schrad. is an endemic and wild native plant growing in arid
areas in the south of Tunisia. This cucurbitaceae is widely used in Tunisian folk
medicine for treating many diseases such as disorders related to the presence of free
radicals (i.e. inflammatory disorders, rheumatism, hypertension). In fact, recent
studies show that aqueous and acetone extracts of different parts of this plant
possess free radical scavenging and antioxidant properties.
The aim of the present study was to evaluate the antiproliferative and
chemoprotective activity towards DNA oxidative damage of different extract types
(aqueous, petroleum ether, chloroform, ethyl acetate, acetone, methanol) of different
plant parts (seeds, roots, stems, leaves and fruits) at different concentrations
(5÷500μg/ml). We also analyzed the major fraction and three pure products derived
from chromatographic separation of seeds and fruits chloroform extracts.
MTS and alkaline Comet Assay were performed on different kind of human tumor
and normal cell lines (HT29, colon cancer; A549 lung adenocarcinoma; HFL1, fetal
lung fibroblast). On HT29 cells, the chloroform extracts proved to be the more
interesting ones (GI50 values were lower with respect to the other compounds) and,
in particular, the leaves extract with a GI50 of 140μg/ml. This antiproliferative activity,
at the highest concentration tested (500μg/ml) seems to be related to a cytotoxic
effect (Trypan Blue method) and preliminary data obtained with the Tunel assay
suggests the apoptosis pathway involvement. The antiproliferative activity of leaves
chloroform extract was detected also on lung cell lines. In particular we have found
that the chloroform extracts of seeds, stem and fruits lead a higher antiproliferative
activity on tumoral A549 cells with respect to normal HFL1. Regarding the major
fraction and the pure products, only the product P1 exert an antiproliferative activity
(GI50: 160μg/ml) but only on HT29. DNA migration analysis of HT29 treated for 24h
with leaves chloroform extract or the P1 product (0.5÷50μg/ml) didn’t show any
induced DNA damage. The treatment of HT29 with H2O2 (100μM) as a known
oxidative agent, 5 minutes at 0° after 24h of trea tment with leaves chloroform
extract (5μg/ml), showed an antioxidative activity comparable to that of vitamin C
(1μM) as demonstrated by the significant reduction in the detected DNA migration.
Our results strongly support the pharmacological use of C. colocynthis Schrad
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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