1,720,976 research outputs found
Three-dimensional reconstruction of interstitial extracellular vesicles in human liver as determined by electron tomography
Full text linkExtracellular vesicles (EVs) are lipid bilayer nanoparticles involved in cell-cell communication that are released into the extracellular space by all cell types. The cargo of EVs includes proteins, lipids, nucleic acids, and metabolites reflecting their cell of origin. EVs have recently been isolated directly from solid tissues, and this may provide insights into how EVs mediate communication between cells in vivo. Even though EVs have been isolated from tissues, their point of origin when they are in the interstitial space has been uncertain. In this study, we performed three-dimensional (3D) reconstruction using transmission electron tomography of metastatic and normal liver tissues with a focus on the presence of EVs in the interstitium. After chemical fixation of the samples and subsequent embedding of tissue pieces in resin, ultrathin slices (300 nm) were cut and imaged on a 120 ekV transmission electron microscopy as a tilt series (a series of subsequent images tilted at different angles). These were then computationally illustrated in a 3D manner to reconstruct the imaged tissue volume. We identified the cells delimiting the interstitial space in both types of tissues, and small distinct spherical structures with a diameter of 30-200 nm were identified between the cells. These round structures appeared to be more abundant in metastatic tissue compared to normal tissue. We suggest that the observed spherical structures in the interstitium of the metastatic and non-metastatic liver represent EVs. This work thus provides the first 3D visualization of EVs in human tissue.Three-dimensional (3D) reconstruction of both liver metastases and normal liver, using transmission electron tomography, identified spherical structures with a diameter of 30-200 nm in the interstitium of both types of tissues.imag
Selenite biotransformation and detoxification by Stenotrophomonas maltophilia SeITE02: Novel clues on the route to bacterial biogenesis of selenium nanoparticles
No full textA putative biosynthetic mechanism for selenium nanoparticles (SeNPs) and efficient reduction of selenite (SeO32-) in the bacterial strain Stenotrophomonas maltophilia SeITE02 are addressed here on the basis of information gained by a combined approach relying on a set of physiological, chemical/biochemical, microscopy, and proteomic analyses. S. maltophilia SeITE02 is demonstrated to efficiently transform selenite into elemental selenium (Se°) by reducing 100% of 0.5mM of this toxic oxyanion to Se° nanoparticles within 48h growth, in liquid medium. Since the selenite reducing activity was detected in the cytoplasmic protein fraction, while biogenic SeNPs showed mainly extracellular localization, a releasing mechanism of SeNPs from the intracellular environment is hypothesized. SeNPs appeared spherical in shape and with size ranging from 160nm to 250nm, depending on the age of the cultures. Proteomic analysis carried out on the cytoplasmic fraction identified an alcohol dehydrogenase homolog, conceivably correlated with the biogenesis of SeNPs. Finally, by Fourier Transformed Infrared Spectrometry, protein and lipid residues were detected on the surface of biogenic SeNPs. Eventually, this strain might be efficaciously exploited for the remediation of selenite-contaminated environmental matrices due to its high SeO32- reducing efficiency. Biogenic SeNPs may also be considered for technological applications in different fields
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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