1,721,216 research outputs found
Ultrastructural changes in a7 integrin-/- mouse muscular tissues
No full textSubsequent to generation of null allele of α7 gene (itga7) in mouse germline by homologous recombination in embryonic stem cells (Mayer U et al., Nat Genet 17:318,1997), skeletal muscle was found to correlate with some alterations and specific damage of the myotendinous junctions. Besides detailed assessment of the distribution of this protein in (i) a series of different skeletal muscles (SSM), including mimic ones, (ii) myocardium (CSM), and (iii) smooth muscular tissues (SM) in wild type, further ultrastructural information was here added on cell-matrix interface in−/− type. Concerning SSM, myodermal junctions showed the most severe alterations including myofilament disarrangement, mitochondrium damages, and drastic increase of sarcolemmal indentations. Tissue suffering was found to affect CSM according to variable extents in different animals as well as specific heart areas in the same animal. The most severe alterations affected the junctions between papillary muscles and "chordae tendineae" including overgrowth of connective tissue, abnormous increase in the interdigitations at the myotendinous junctions and topical detachments between degenerating cardiomyocytes. Concerning SM, more prominent sarcolemmal indentations for vessel SM than visceral SM and higher α3-integrin-chain expression for visceral SM were appearent as alternative, compensatory features versus the α7-integrin-chain deficiency
Integrin and laminin chain expression in alpha 7 deficient smooth muscular tissue
No full textIn muscular tissues, alpha7beta1 is the major integrin receptor for laminins, which are represented by isoforms laminin 2 and 4 (basal laminae of skeletal and cardiac muscle cells) 8 and 10 (smooth muscle cell basal laminae). The absence of alpha7 integrin chain leads to the onset of skeletal muscular dystrophies (Mayer U et al, Nature Genet 1997, 17 ,318), and cardiac hypertrophy (Ortolani et al, in press). In alpha 7 integrin chain deficient mice, we previously observed different degrees of ultrastructural alteration between viscera wall smooth muscle cells of those in vascular walls. Since moderate up-regulation of alpha 5 integrin chain was described for alpha 7 deficient skeletal muscle ( Nawrotzki R et al, Hum Mol Genet. 2013,12,483), here compensatory overexpression was investigated of other alpha integrin chains and laminins in alpha 7 deficient mice, concerning smooth muscle cells of muscularis externa of oesophagus, stomach, ileus, colon, bladder, uterus as well as those in tunica media of vessels of the heart, different skeletal muscles, and viscera walls as above. No differences appeared for alpha 5 and alpha 6 integrin chain distribution pattern in both control and K.O. mice, whereas remarkable increase in alpha 3 integrin chain was apparent in K.O. smooth muscle cells versus control ones, more evident in viscera walls than in vascular ones, consistently with the weaker damage observed. Concerning the distribution of laminin chains, no differences was detected by comparing w/t and K.O. mice
Alpha 7 beta 1 integrin receptor in vascular and visceral smooth muscle cells. Ultrastrucural alterations in alpha 7 deficient mice and compensatory overexpression of alpha 3 chain
No full textIntroduction Alpha 7 beta 1 is major integrin receptor for laminin in muscular tissue. The absence of this integrin correlates wtih skeletal muscular distrophy (Mayer U. et al, Nature Genet,1997,17,318-23). Severe tissue alterations have been also found in deficient mouse myocardium (Ortolani F. et al, in press). To date, little attention has been focussed on smooth muscle cells, in spite of the strong expression of alpha 7 integrin chain in these cells. Material Specimens were excised from the muscularis externa of the walls of oesophagus, stomach, ileus, colon, bladder and uterus of normal and alpha 7 deficient mice. In addition, comparison between wilde type and knock-out animals was carried out for smooth muscle cells forming the tunica media of vessels irrorating myocardium, different skeletal muscles and the walls of the above mentioned viscera Antibodies rabbit polyclonal R242 antibody against murine alpha7 integrin chain, rabbit anti-integrin alpha3 chain polyclonal antibody (Chemicon International-Prodotti Gianni, Milan); rabbit anti-integrin alpha5 chain polyclonal antibody (Chemicon International-Prodotti Gianni, Milan); rat anti-integrin alpha6 chain (GoH3) monoclonal antibody (Chemicon International-Prodotti Gianni, Milan). Results Specific alterations were observed in deficient smooth muscle cells, including (i) enlargement of plasma membranes, which showed a lot of indentations particularly marked at the interface with the extracellular matrix, (ii) prominent arising of caveolae and intracytoplasmatic vesicles, and (iii) significant increasing in the distribution of organules and subsarcolemmal/sarcomeric dense bodies. These alterations were more marked in vascular walls than in visceral ones. Immunofluorescence and immunogold labelling revealed no differences to exist concerning the expression of integrins alpha 5 and alpha 6 in mutant tissues versus normal ones. Conversely, increase in alpha 3 integrin chain expression was detected in deficient smooth muscle cells, which was more evident in visceral walls than in vascular ones. Conclusions These results confirm the important role of alpha 7 beta 1 integrin in ensuring muscle tissue structural integrity , especially there where mechanical stress is stronger. The most severe alterations exhibited by vascular smooth muscle cells might correlate with the uninterrupted stress exerted by the hemodynamical flow on vessel walls and with the less efficient compensatory effect of alpha 3 integrin chain, since alpha 3 seems to undergo weaker up-regulation for mutant muscle cells in vessels than for those in viscera
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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