1,720,963 research outputs found
Differential effects of gonadectomy on thymic stromal cells in promoting T cell differentiation in mice.
No full textTwenty-six week-old BDF1 mice were gonadectomized and grafted with thymus from irradiated (8.5 Gy) newborn, 6-week-old, or 26-week-old mice. One month later, grafted thymuses were recovered and examined in terms of thymocyte numbers, subpopulations and proliferative responses to Concananavlin A (Con A). The growth of the irradiated thymus was significantly higher in gonadectomized (Gx) than in sham-operated (Sham) mice and the magnitude of thymic growth was apparently age-dependent, as it was greater for newborns than for older mice. Con A response of thymocytes was also significantly higher in Gx mice than in Sham mice, and the magnitude of the response declined with advancing age of the thymus donors. Flow cytometric analysis revealed that a significant increase in the percentage of CD4+CD8- was observed in thymus grafts showing high Con A responses. However, this effect of Gx on the thymus graft was dependent on age of the thymus donor. Namely, newborn thymus grafts could grow equally well in both Gx and Sham recipients, whereas thymus grafts from 6- and 26-week-old mice could grow well only in Gx, but not in Sham recipients. The number of thymocytes was comparable in thymus grafts from 6- and 26-week-old mice, but the proliferative response to Con A was higher in the former than in the latter graft. Collectively, Gx appeared to promote immigration of thymocyte precursors into the thymus and to enhance proliferation and differentiation of thymocytes towards CD4+CD8- T cells, in an age-related manner
Long-term effects of lonidamine on mouse testes
No full textLonidamine (LND) [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid] is a well-known antispermatogenic drug. The aim of this study was to identify its possible long-term sequelae on the reproductive system of mice as compared with rats, where most data have been obtained until now. Sexually mature CD1 male mice were administered a single dose of LND (200 mg/kg bw by gavage) and killed 24 and 48 h, 6 days and 2, 4 and 8 weeks after the treatment. Testes were collected, weighed and (1) fixed in Bouin's solution for histological analysis or (2) reduced to monocellular suspensions and ethanol fixed to undergo flow cytometry (FCM) DNA content analysis. No effect on body weight and/or food consumption was observed in the treated group in comparison with the control group. Testicular weight was significantly reduced 24 h after the treatment. Reduced seminiferous epithelium with a progressive lack of intercellular cohesion and marked depletion of spermatids, infiltration of granulocytes, desquamation into the tubular lumen and increased intertubular spaces were present by 24 h after the treatment and persisted to a marked degree at 48 h, 6 days and 2 and 4 weeks up to a marked degeneration of tubular structures with absence of spermatogenesis. The same effects, albeit with a moderate severity, were still present 8 weeks after the treatment. As also detected by FCM, primary spermatocytes appeared to be the main cellular target. Sertoli and Leydig cells were remarkably spared. The histological findings are consistent with those previously observed in rats and point out that testicular damage may persist for several weeks after a single-dose administration. Findings are discussed in comparison with testicular toxicity elicited by other xenobiotics
Lonidamine transiently affects spermatogenesis in pubertal CD1 mice
No full textLonidamine (LND) [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid], a well-known antispermatogenic drug, was studied for the first time in pubertal mice to assess its possible effects on spermatogenesis. Male CD1 mice were orally treated on Postnatal Day (PND) 28 with a single dose of LND (100 mg/kg body weight) and sacrificed on PND30, PND42, PND74 and PND123. On PND30 (48 h after dosing), severe testicular effects were evidenced in the treated animals: (a) reduction of the testicular sperm head concentration (approximately 50% of the control value); (b) changes in the spermatogenic cell type distribution (mild decrease of the elongated spermatids and S-phase cells fractions); and (c) morphological alterations of the Sertoli cell cytoplasm and germ cell exfoliation. These changes were recovered in adulthood, on PND74 and PND123. However, no effect on sperm chromatin structure was detected on the epididymal sperm of mature mice by sperm chromatin structure assay, suggesting that LND did not interfere with the process of chromatin reorganization and DNA packaging
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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