1,721,008 research outputs found
Integrated proteomic analysis of normal and diseased red cells. Role of physiological stresses in erythrocyte signaling pathways
No full textIl globulo rosso è una cellula altamente specializzata per il trasporto di ossigeno e anidride
carbonica. Studi di fisiopatologia eritroide hanno permesso di riconoscere 4 compartimenti
fondamentali: la membrana, il citoscheletro, gli enzimi citosolici e l’emoglobina. Alterazioni
a carico di uno di questi compartimenti sono responsabili di profonde anomalie
nell’organizzazione funzionale degli eritrociti, che si traducono clinicamente in anemie
ereditarie o acquisite.
Le anemie ereditarie sono sostenute da mutazioni monogeniche e la loro diffusione e’
legata alla selezione positiva indotta dalla malaria. Tra i disordini ereditari dei globuli rossi,
l’organizzazione mondiale della sanita’ (OMS) ha identificato le emoglobinopatie e in
particolare le β-talassemie come malattie emergenti in tutte le aree geografiche del
mondo.
L’enorme differenza tra il genotipo e il fenotipo clinico dell’emoglobinopatie suggerisce che
eventi post-traslazionali possano essere giocare un ruolo importante nelle interazioni
proteina-proteina coinvolte nelle diverse funzioni cellulari, influenzando in ultima analisi le
manifestazioni cliniche di queste malattie.
Tra le modificazioni post-traslazionali a carico delle proteine gli eventi di
fosforilazione/defosforilazione sostenuti da chinasi/fosfatasi costituiscono uno degli
elementi chiave nella trasduzione del segnale coinvolti nell’omeostasi cellulare.
Gli scopi del presente progetto di ricerca sono stati quelli di caratterizzare vie di segnale
intracellulare in risposta a stress in globuli rossi normali e patologici.
Nella prima parte della ricerca abbiamo analizzato l’espressione e la localizzazione di
perossiredossina-2 (Prx2) in globuli rossi di 2 modelli murini di β-talassemia caratterizzati
da diversa gravita’ del fenotipo ematologico (Hbbth/th e Hbbth3/+). Nei globuli rossi β-
talassemici abbiamo descritto (paper submitted to Blood, 2009) un’aumentata espressione
di Prx2 ma una riduzione nella quantità di Prx2 legata alla membrana a fronte di un grave
danno ossidativo. Utilizzando un’analisi di proteomica integrata abbiamo dimostrato che
una parte di Prx2 legata alla membrana e’ fosforilata e che questa modificazione posttraslazionale
influenza la funzione di Prx2 e la sua fisiologica risposta al danno ossidativo.
Nella seconda parte del progetto sono stati analizzati gli effetti della deossigenazione sul
proteoma di membrana dei globuli rossi di topi geneticamente deficienti di Fgr, Hck e Lyn,
chinasi della famiglia del Src (fgr-/-hck-/-; fgr-/-hck-/-lyn-/-). Sulla base di studi preliminari
in proteomica classica, abbiamo condotto un’analisi comparativa del fosfoproteoma della
membrana dei globuli rossi dei 3 ceppi murini esposti a deossigenazione. Questi dati ci
hanno permesso di individuare il nuovo ed importante ruolo di chinasi della famiglia del
Src e di Syk nella trasduzione del segnale in risposta all’ipossia nei globuli rossi.
Lo sviluppo di queste metodologie e l’acquisizione di dati scientifici originali su nuove vie
di trasduzione del segnale in globuli rossi normali e patologici ha permesso di contribuire
allo studio della modulazione delle heat shock protein (HSP27; HSP70) e della Prx2 in
globuli rossi di pazienti affetti da anemia falciforme (Proteomics Clin. Appl. 2008, 2, 706-
719) e allo studio della modulazione degli eventi di fosforilazione della banda 3 da parte di
Syk in globuli rossi normali e di pazienti affetti da deficit di Glucosio-6-fosfato-deidrogenasi
(Biochem J. 2009, 418, 359-367).Peroxiredoxin 2 (Prx2) is the third most abundant cytoplasmic protein in red blood cells
(RBCs) and is involved at least in part in defence against oxidative stress. Here, we
examined the expression and localization of Prx2 in RBCs from two murine models of β
thalassemia (Hbbth3/+, Hbbth/th) and in normal RBCs treated with phenylhydrazine (PHZ) as
β thalassemic-like RBCs. Prx2 expression was higher in β thalassemic mouse models than
in normal RBCs without effects of cell density/age. Dimeric Prx2 was only detectable in β
thalassemic RBC lysates and related with the severity of the hematological phenotype.
Although β thalassemic RBC membrane is characterized by a severe oxidative damage,
we found Prx2 translocated from the membrane to the cytosol, without detectable dimers
as also observed in β thalassemic-like RBCs. We generated 2D maps of the phosphoenriched
RBC membrane proteins, and in the area where Prx2 was expected to migrate,
anti-phosphotyrosine staining was observed, which was further identified as Prx2 by both
mass-spectrometric and immunoblot-analysis. These data demonstrate that a population
of Prx2 associated with the membrane is tyrosine-phosphorylated and that tyrosine
phosphorylation might regulate both the oligomeric state and membrane association of
Prx2, regardless of the oxidation state of the cell
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
Performance of a novel sieving matrix of Poly(vinyl alcohol)ACRYLAMIDE copolymer in elecrophoretic separations of high molecular weight proteins from red cell membrane.
Full text linkThe analysis of high molecular weight (HMW) proteins from complex mixtures is still a
challenge in proteomics. This work introduces a novel hydrogel obtained by the copolymerization
of an allyl-PVA derivative with acrylamide and bisacrylamide and applies this
matrix to the electrophoretic separation of HMW proteins. By inducing gelation of polyacrylamide
in the presence of variable amounts of allyl-PVA, it is possible to control and
vary the average gel porosity. This gel is easy to produce and handle and offers the advantage
of being highly mechanically resistant and macroporous. The new matrix was
tested in mono-dimensional separations of complex protein mixtures extracted from red
cell membranes with different detergents. The improved performance of this macroporous
matrix allowed to identify new proteins by MS and immunoblot analysis using specific
antibodies. In particular, the resolution of proteins ranging in size between 97 and
279 kDa was greatly improved here compared to standard polyacrylamide gels, suggesting
that this matrix can be a useful tool in routine analysis of HMW proteins in cell biology
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
Pharmacological Inhibition of Calpain-1 Prevents Red Cell Dehydration and Reduces Gardos Channel Activity in a Mouse Model of Sickle Cell Disease. Identification of Druggable Protease Target
No full text[no abstract available
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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