1,720,964 research outputs found
Eye drop propranolol administration promotes the recovery of oxygen-induced retinopathy in mice
No full textThe mouse model of oxygen-induced retinopathy (OIR) is a well-established model of retinopathy of prematurity (ROP), characterized by the abnormal formation of new blood vessels, which is similar to ROP. In this model, we have recently shown that subcutaneous (sc) administration of the non-selective beta-adrenergic receptor (β-AR) blocker propranolol ameliorates angiogenic processes in the retina when its effects are evaluated at postnatal day (PD) 17. In the present study, we investigated whether propranolol application as collyrium can promote the recovery of OIR. After propranolol administration on the eye, mice were first tested for retinal concentrations of propranolol as compared with those measured after sc or per os administration. Subsequently, we determined the effects of propranolol ophthalmic solutions, at the optimal dose for delivery, on VEGF, IGF-1, hypoxia-inducible factor (HIF)-1α, signal transducer and activator of transcription 3 (STAT3) and retinal neovascularization as assessed in both the superficial and the deep vascular plexuses. The results showed that 2% topical propranolol has an efficiency (in terms of final propranolol concentration in the retina) comparable to that of 20 mg/kg propranolol sc or per os and significantly higher than those observed with doses and administration routes that are currently used with children. Propranolol ophthalmic solutions reduced VEGF and IGF-1 up-regulation in response to hypoxia and drastically inhibited HIF-1α accumulation and STAT3 phosphorylation. As a result of its inhibitory effects on hypoxia-induced proangiogenic factors, propranolol significantly reduced retinal neovascularization in the superficial but not in the deep vascular plexus. An evaluation of retinal neovascularization at PD21 showed that propranolol was still effective in inhibiting OIR. These findings strengthen the hypothesis that β-AR blockade can efficiently counteract OIR and suggest that topical eye application of propranolol can represent an alternative delivery route to systemic administration thus avoiding the risk of associated complications and side effects that could make this drug unsafe in the ROP treatment
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
GC-MS analysis of the volatile constituents of the essential oil and aromatic waters of Artemisia annua L. at different developmental stages
No full textArtemisia annua L. (Asteraceae) still represents the only source of artemisinin, considered as one of the most important drugs for the treatment of malaria and which, more recently, has been shown to be effective against numerous types of tumors. The foliage and inflorescence of A. annua also yield an essential oil upon hydrodistillation. This oil has been evaluated at different development stages (pre-flowering and flowering) by GC/MS. The volatile oil from plants at full blooming showed numerous constituents, with germacrene D (21.2%), camphor (17.6%), β-farnesene (10.2%), β-caryophyllene (9%), and bicyclogermacrene (4.2%) among the main ones. Aromatic waters, after extraction with n-hexane, showed the presence, among others, of camphor (27.7%), 1,8-cineole (14%), artemisia ketone (10.1%), α-terpineol (6.1%), trans-pinocarveol (5.4%), and artemisia alcohol (2%). From plants at the pre-flowering stage, aromatic waters were obtained with camphor (30.7%), 1,8-cineole (12.8%), artemisia alcohol (11.4%), artemisia ketone (9.5%), alpha-terpineol (5.8%), and trans-pinocarveol (3.0%) as the main constituents. The qualitative and quantitative profiles of the two aromatic waters were similar. These results permitted the conclusion to be made that A. annua could be harvested a long time before the onset of flowering to obtain higher yields of artemisinin or could be allowed to attain maturity to obtain valuable yields of volatile
GC/MS analysis of the volatile constituents of Artemisia annua L. at different development stages
No full text
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
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