1,720,972 research outputs found
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
Dichlorodiphenyltrichloroethane, an old pesticide with a new mechanism of toxicity
No full textDichlorodiphenyltrichloroethane (DDT) is an organochlorine derivative known for its detrimental effect on human health. It was abundantly used as a pesticide and finally banned in many countries for its toxicity. Because of its extremely long half-life (up to 10 years), DDT is still blamed to cause health problems, due to the accumulation in the environment. We have previously shown that in vitro exposure to DDT causes severe membrane shedding with the release of vesicular organelles such as exosomes and/or ectosomes. A large body of evidence has shown that these vesicles, other than being directly involved in physiological exchanges of cellular materials, are implicated in the pathogenesis of several diseases such as viral and neurodegenerative diseases as well as tumorigenesis. In this short review, we discuss how the increased release of extracellular vesicles could explain the enhanced risk of diseases in patients exposed to organochlorine derivatives such as DDT
An internal ribosome entry site (IRES), present within the third cytoplasmic loop, drives the expression of the Carboxyl-terminal domain of the human muscarinic M2 receptor
No full textAn internal ribosome entry site (IRES) is a nucleotide sequence
that allows cap independent translation initiation by recruiting
the ribosome in proximity of an internal initiation codon. Here,
we describe an IRES driven mechanism of translation initiation
for the human muscarinic M2 receptor. The insertion of a stop
codon in the N-terminal of the third cytoplasmic loop of the M2
receptor, resulted in a mutant receptor (M2-stop) that was still able
to bind muscarinic ligands and to function. The insertion of the
stop codon resulted in the expression of a N-terminal receptor
fragment, constituted by the transmembrane regions I-V, and a
C-terminal receptor fragment, constituted by the transmembrane
regions V and VI. The two fragments could bind to each other
and reconstitute the functional muscarinic receptor. Translation of
the C-terminal fragment was not due to leaky scanning and reinitiation
of translation, as the insertion of a stable hairpin loop did
not prevent its translation. Mutagenesis of the three methionines
in frame after the stop codon, revealed that translation initiation
starts at the third methionine (codon 368). Western blot analysis
showed that the C-terminal fragment of the M2-stop receptor has
an apparent molecular mass of ~15.000 Dalton. Remarkably, a
fragment of the same molecular weight was found also in the
cells transfected with the wild type M2 receptor, suggesting that
the IRES driven mechanism of translation initiation is physiologically
functioning
Allosteric modulators of g protein-coupled dopamine and serotonin receptors: A new class of atypical antipsychotics
Full text linkSchizophrenia was first described by Emil Krapelin in the 19th century as one of the major mental illnesses causing disability worldwide. Since the introduction of chlorpromazine in 1952, strategies aimed at modifying the activity of dopamine receptors have played a major role for the treatment of schizophrenia. The introduction of atypical antipsychotics with clozapine broadened the range of potential targets for the treatment of this psychiatric disease, as they also modify the activity of the serotoninergic receptors. Interestingly, all marketed drugs for schizophrenia bind to the orthosteric binding pocket of the receptor as competitive antagonists or partial agonists. In recent years, a strong effort to develop allosteric modulators as potential therapeutic agents for schizophrenia was made, mainly for the several advantages in their use. In particular, the allosteric binding sites are topographically distinct from the orthosteric pockets, and thus drugs targeting these sites have a higher degree of receptor subunit specificity. Moreover, “pure” allosteric modulators maintain the temporal and spatial fidelity of native orthosteric ligand. Furthermore, allosteric modulators have a “ceiling effect”, and their modulatory effect is saturated above certain concentrations. In this review, we summarize the progresses made in the identification of allosteric drugs for dopamine and serotonin receptors, which could lead to a new generation of atypical antipsychotics with a better profile, especially in terms of reduced side effects
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
Integration and spatial organization of signaling by g protein-coupled receptor homo-and heterodimers
No full textInformation flow from a source to a receiver becomes informative when the recipient can process the signal into a meaningful form. Information exchange and interpretation is essential in biology and understanding how cells integrate signals from a variety of information-coding molecules into complex orchestrated responses is a major challenge for modern cell biology. In complex organisms, cell to cell communication occurs mostly through neurotransmitters and hor-mones, and receptors are responsible for signal recognition at the membrane level and information transduction inside the cell. The G protein-coupled receptors (GPCRs) are the largest family of membrane receptors, with nearly 800 genes coding for these proteins. The recognition that GPCRs may physically interact with each other has led to the hypothesis that their dimeric state can provide the framework for temporal coincidence in signaling pathways. Furthermore, the formation of GPCRs higher order oligomers provides the structural basis for organizing distinct cell compartments along the plasma membrane where confined increases in second messengers may be per-ceived and discriminated. Here, we summarize evidence that supports these conjectures, fostering new ideas about the physiological role played by receptor homo-and hetero-oligomerization in cell biology
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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