1,721,034 research outputs found
Ruolo dei recettori di tipo “Toll” (TLR) nella infezione malarica
No full textMalaria mortality can reach 3 million, mostly in Africa. Plasmodium falciparum is the specie that can cause severe complications in humans. The parasites are transmitted to man (asexual phase) through the puncture of the mosquito Anopheles sp (sexual phase). Sometimes malaria can develop into severe complications. The mechanisms that are involved in the switch from a mild to a complicated disease are still not completely understood. Researchers have demonstrated that innate immunity is specific, so it can discriminate between self and non self (“pathogen-associated molecular patterns”- PAMPs) antigens through conserved receptors called “Toll-like receptors” (TLRs) (Akira 2004; Medzhitov 2004). GPI (Schofield 2002) and hemozoin (Pichangkul 2004) have been sugested as putative PAMPs for malaria. There are no data, however, that indicate which ty
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
The peculiar behavior of dihydroartemisinin in hypoxia: effect on endothelial cells
No full textArtemisinin derivatives are the most effective and safe antimalarial drugs presently available. They also exert antiangiogenic effects on human endothelium and tumours. Moreover, artemisinins are specifically cytotoxic against cancer cells and cause reduction of tumour grow in animal models. Therefore these compounds are promising drugs as adjuvants in anticancer chemotherapy.
Hypoxia plays a crucial role both in malaria and tumours. In severe malaria, the cytoadherence of infected erythrocytes to endothelial cells (ECs) generates microvascular occlusion and subsequent tissue hypoxia. In cancer, the growth of the tumour mass causes the failure of oxygen and nutrients supply. However, the role of oxygen deprivation in the mechanism of action of artemisinins has not been studied yet. To this purpose, we assessed the activity of dihydroartemisinin (DHA), the active metabolite of most artemisinins, on microvascular ECs (HMEC-1) both in normoxic or hypoxic (1% oxygen) conditions. The doses of DHA were chosen on the base of their pharmacological use: low doses (1μM or 0.5μM) are those reached in the plasma of artemisinins-treated malaria patients and high doses (50μM or 12.5μM) are similar to those used in literature as antitumor or antiangiogenic.
By measuring cell growth (MTT assay), we observed that DHA at high dose was more toxic in normoxia, whereas at low dose was more effective in hypoxia. Only the high dose of DHA induced significant apoptosis (measured as phosphatidylserine exposure and caspase activation) and cell cycle arrest in G2. These effects were more evident in normoxia than hypoxia.
The role of oxidative stress was also investigated. Again, only DHA 50μM induced ROS production and lipid peroxidation (measured as TBARS production). Doses higher than 10μM, induced ECs death through oxidative stress. We do not know at present whether the toxicity exerted by low doses of DHA under hypoxia could be exploited to reach pathogens or tumour cells in hypoxic niches. Taken together our results suggest that, depending on the pathologic situation, different doses of artemisinins could achieve different effects. This should be taken into account, for example, in the treatment of pregnant women with artemisinins and in the studies on the possible use of these drugs as antitumor agents.
Acknowledgments
The financial support of the FP6-IP18834 ANTIMAL and Università di Milano (PUR 2009) is acknowledged
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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