1,721,003 research outputs found
HPTLC-MALDI MS for (glyco)sphingolipid multiplexing in tissues and blood: A promising strategy for biomarker discovery and clinical applications
No full textSphingolipids have hydrophilic and hydrophobic properties, different saturation and combination of the oligosaccharide chains and mass homology of species located in a narrow m/z region hampering their recognition. To target sphingolipids for diagnostic purposes, standardized methods for lipid extraction, quali- and quantitative assessments are required. In this study, HPTLC-MALDI MS was adopted to establish sphingolipid and glycosphingolipid profiles in muscle, brain and serum to create a database of molecules to be searched in the preclinical and clinical investigations. Specific protocols for lipid extraction were set up based on the characteristics of the tissue or/and fluids; this approach maximizes the HPTLC-MALDI MS analytical throughput both for lipids extracted in organic and aqueous phase. This study indicates that alkaline hydrolysis is necessary for the detection of low abundant species such as Gb3Cer and ceramides in serum and Gb4Cer, CerP and HexCer in muscle tissue. The high hydrophobicity of ceramides has been overcome by the development of HPTLC plate in chloroform:methanol/50:3.5, which increases the number and the intensity of low abundant Cer species. MS/MS analysis has been conducted directly on HPTLC plate allowing the molecular recognition; furthermore a dataset of spectra was acquired to create a database for future profiling of these molecules
Set-up for human sera MALDI profiling: the case of rhEPO treatment
No full textThe implementation of high-throughput technologies based on qualitative and quantitative methodologies for the characterization of complex protein mixtures is increasingly required in clinical laboratories. MALDI profiling is a robust and sensitive technology even though the serum high dynamic range imposes some limitations, preventing detection and identification of less abundant species. Efforts to increase the MALDI profiling detection ability are needed. A set-up has been performed for recombinant human erythropoietin (rhEPO) monitoring in serum analyzing the effects of two commercially available columns (MARS Hu7 and Hu14) for immunodepletion, and two matrices (α-cyano-4-hydroxycinnamic acid and 2’,4’-dihydroxyacetophenone) for spectra quality improvement.
Immunodepletion skills of both columns were determined by 2D-DIGE, which precisely revealed the efficacy of Hu14 in protein removal and in serum dynamic range decrement.
After optimization of the type of matrix and sample dilution, these new efficient conditions were used for serum profiling of ten healthy subjects before and after rhEPO treatment. The principal component analysis indicates that combination of Hu14 column and 2’,4’-dihydroxyacetophenone matrix increases data quality allowing to discriminate between treated and untreated samples, making serum MALDI profiling suitable for clinical monitoring of rhEPO
Set-up for MALDI profiling of human sera: the case of rhEPO teatment
No full textThe implementation of high-throughput technologies based on qualitative and quantitative methodologies for the characterization of complex protein mixtures is increasingly required in clinical laboratories. To this purpose, MALDI profiling appears a robust and sensitive technology even though the high dynamic range imposes a major limitation a hampering the identification of less abundant species and decreasing the quality of MALDI profiling for clinical implementations. A number of methodologies have been developed to overcome this issue and in this study the efficacy and reproducibility of immunodepletion for human serum profiling was investigated. Two commercially available columns (MARS Hu7 and Hu14) were tested. The effects of both on serum were assessed by 2D-DIGE: the comparison of eluted fraction from Hu14 versus Hu7 revealed the presence of a different protein distribution and of 128 differentially changed spots (p-value<0.01), out of them 114 were identified by mass spectrometry. In particular, 34 spots strongly decreased in Hu14 sample correspond to proteins and their isoforms expected to be significantly reduced by this column. In addition, the type of matrix and the sample dilution, representing crucial elements for MALDI profiling improvement, were determined. Finally, the selected experimental conditions were applied to sera profiling of 8 subjects before and after erythropoietin treatment. The results indicate that a combination of Hu14 column immunodepletion and DHAP matrix increases data quality and appears an appropriate approach for human serum profiling by MALDI
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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