104,983 research outputs found
Prevention of Ischemia-Reperfusion Injury in the Rat Liver by Atrial Natriuretic Peptide
No full textThis work characterizes the protective effects of ANP preconditioning in ischemia-reperfusion
injury of the isolated perfused rat liver. It was of particular interest to evaluate
the influence of ANP on the mode of cell death occurring during cold ischemia and
reperfusion and to elucidate the involved signal transduction pathways.
Apoptotic cell death was mainly seen after cold liver storage, whereas necrosis was
predominant in the reperfusion period.
It could be demonstrated for the first time that preconditioning with ANP was able to
reduce both apoptotic as well as necrotic cell death. After cold ischemia, in particular
hepatocytes were protected against apoptosis. After reperfusion, protection against
necrosis comprised hepatocytes and sinusendothelial cells predominantly in the periportal
liver areas.
As target molecules for ANP action, the cGMP-dependent protein kinases did not seem to
be responsible for the conferred cytoprotection. In the liver, no expression of these
kinases could be detected and a functional connection could not be derived. In contrast,
the cAMP-dependent protein kinases were identified to promote survival. This was further
supported by the ability of ANP to directly activate cAMP-dependent protein kinases in
livers and hepatocytes.
An early transcriptional induction of HO-1 by ANP independent of cGMP could be
demonstrated. The induction of heme oxygenase-1 by ANP might not be responsible for
the observed hepatoprotection, since inhibition of HO-1 activity did not abrogate the ANP
effect. Interestingly, cell-type specific evaluation detected that induction of HO-1 in livers
by ANP is exclusively restricted to Kupffer cells.
In summary, this thesis gives new insights into the actions of the cardiovascular hormone
ANP in IRI of the rat liver. This data helps to understand the mechanisms of how ANP
mediates cytoprotection by illuminating effects and potential pathways, an important
prerequisite for a rational application in therapy.
This work was supported by the Deutsche Forschungsgemeinschaft (DFG: Ge 576/14-2
and FOR 440/1, TP2)
Revisitando un clásico en clave feminista: Mujercitas (2019) de Greta Gerwig.
No full textEn 1868, Louisa May Alcott escribió Little Women (Mujercitas), su obra más conocida. La trama sigue las vidas de las hermanas Jo, Meg, Beth y Amy y las vicisitudes económicas que experimentan, sus inseguridades, la lucha por sus sueños, la búsqueda del amor o su batalla contra las restricciones sociales de la Norteamérica del siglo XIX. Tras el éxito cosechado, y por petición del público, la escritora escribió Good Wives (Aquellas Mujercitas) un año más tarde.
Greta Gerwig (California, 1983) es una actriz, directora, guionista y productora estadounidense. Su dirección de Barbie (2023), la película más taquillera del año, la consagra como una de las directoras más aclamadas del momento. Dio el salto a la dirección con Lady Bird (2017), la cual le valió la nominación al Oscar a la mejor dirección.
La atemporalidad de las obras de Louisa May Alcott queda reflejada en las numerosas adaptaciones cinematográficas que se han llevado a cabo a lo largo del tiempo. En su segunda película, Mujercitas (2019), Saoirse Ronan (Lady Bird) lidera el elenco junto a figuras destacadas como Meryl Streep y Emma Watson, así como a personalidades emergentes como Florence Pugh (Midsommar) y Timothée Chalamet (Call Me By Your Name).
Greta Gerwig aborda el texto original, diarios y cartas de la escritora estadounidense, y presenta el pasado y el presente de las protagonistas mediante el empleo de flashbacks. De este modo, ofrece una relectura contemporánea y feminista del clásico decimonónico, explorando los desafíos de las mujeres del siglo XX.
El objetivo de este trabajo consiste en analizar los contextos en los que se conciben ambas obras, realizar un análisis comparativo entre estas y esclarecer aquellas cuestiones responsables de la vigencia del clásico de la literatura dos siglos después.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
The protein tyrosine kinases EpsB and PtkA differentially affect biofilm formation in <em>Bacillus subtilis</em>
No full textThe Gram-positive soil bacterium Bacillus subtilis is able to choose between motile and sessile lifestyles. The sessile way of life, also referred to as biofilm, depends on the formation of an extracellular polysaccharide matrix and some extracellular proteins. Moreover, a significant portion of cells in a biofilm forms spores. The first two genes of the 15-gene operon for extracellular polysaccharide synthesis, epsA and epsB, encode a putative transmembrane modulator protein and a putative protein tyrosine kinase, respectively, with similarity to the TkmA/PtkA modulator/kinase couple. Here we show that the putative kinase EpsB is required for the formation of structured biofilms. However, an epsB mutant is still able to form biofilms. As shown previously, a ptkA mutant is also partially defective in biofilm formation, but this defect is related to spore formation in the biofilm. The absence of both kinases resulted in a complete loss of biofilm formation. Thus, EpsB and PtkA fulfill complementary functions in biofilm formation. The activity of bacterial protein tyrosine kinases depends on their interaction with modulator proteins. Our results demonstrate the specific interaction between the putative kinase EpsB and its modulator protein EpsA and suggest that EpsB activity is stimulated by its modulator EpsA.</p
Primary structure of the N-linked carbohydrate chains of calreticulin from spinach leaves
No full textCalreticulin is a multifunctional Ca2+-binding protein of the endoplasmic reticulum of most eukaryotic cells. The 56 kDa Calreticulin glycoprotein isolated from spinach (Spinacia oleracea L.) leaves was N-deglycosylated by PNGase-F digestion. The carbohydrate moiety was isolated by gel permeation chromatography and purified by high-pH anion-exchange chromatography. The fractions were investigated by 500 MHz H-1-NMR spectroscopy, in combination with monosaccharide analysis and fast-atom bombardment-mass spectrometry. The following carbohydrate structure could be established as the major component (Man(8)GlcNAc(2)):
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Heterogeneity was demonstrated by the presence of two minor components being Man(7)GlcNAc(2) lacking a terminal residue (D-1 or D-3), compared to the major component. A. cross-reactivity with an antibody against the endoplasmic reticulum retention signal HDEL was also found
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
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