1,720,958 research outputs found
PROTECTIVE EFFECTS IN VIVO OF DEXAMETHASONE AGAINST CISPLATIN-INDUCED TOXICITY
No full textIn mammals, inner hair cells have lost their regenerative abilities. Thus, when they are damaged, acoustic signal transduction from hair cells to the spiral ganglion is irreversibly compromised and profound sensorineural hearing loss occurs. Ototoxicity and inner hair cell damage are relevant side effects of cisplatin, a widely employed chemotherapeutic drug. The aim of this study is to evaluate the in vivo otoprotective effects of dexamethasone, an anti-inflammatory drug, administered before intraperitoneal treatment with cisplatin in Wistar rats. Dexamethasone and cisplatin treatment were tested either alone or in combination. Both cochleas and kidneys were explanted from each group after dexamethasone, cisplatin or dexamethasone-cisplatin treatments, and processed for histological analyses. The preliminary morphological analysis by haematoxylin-eosin staining on cochlea and kidney tissues showed some protective effects of dexamethasone against cisplatin toxicity. For each group, one cochlea per animal was processed for scanning electron microscopy (SEM) to visualize hair cell morphology in the organ of Corti. As expected, cisplatin treatment induced hair cell loss and marked disorganization of the stereocilia, while pre-treatment by dexamethasone before cisplatin administration significantly reduced the ototoxic effects: hair cell structure was mostly maintained. However, the treatment by dexamethasone alone had some morphological effects on stereocilia, which appeared shorter in comparison to untreated animals. Based on these results, preliminary immunofluorescence experiments were performed with myosin 7A, anti-glucocorticoid receptor antibodies and apoptotic markers (cytochrome c and p53). The overall results supported the protective effects of dexamethasone against cisplatin-induced ototoxicity
Is threshold shift after implantation and local corticosteroid treatment correlated with tissue growth in the cochlea? An electrophysiological and histological evaluation
No full textPreservation of residual hearing during cochlear implantation has become increasingly important. Aside from improvement of implant devices and surgical techniques that minimise the mechanical trauma, treatment with corticosteroids is also deemed to reduce hearing loss due to suppression of inflammatory processes and reduction of growth of connective or bone tissue at the implantation site.
In the present study two different corticosteroids were administered directly into the cochleae of guinea pigs in order to analyse their effects on hearing preservation after cochlea implantation. The extent of tissue growth was investigated histologically and correlated with the treatment.
Three groups of guinea pigs were implanted with guinea pig electrodes (supplied by MED EL). Either triamcinolone, dexamethasone or artificial perilymph (AP) was infused with a micro-syringe directly through a cochleostomy prior to implantation. The respective other ears were treated likewise omitting implantation and served as additional pharmacological controls. Click-evoked and frequency-specific compound action potential (CAP) audiograms were recorded via round window electrodes and hearing thresholds were measured before and after drug/AP application during the following 3 months. Threshold shifts were determined with respect to the pre-surgery CAP-thresholds for each individual ear. Three months after surgery paraffin-embedded cochlea sections were cut longitudinally (7m) and Azan-stained. For each section the area of tissue filling the Scala tympani at the implantation site was measured in relation to the area left free.
Hearing loss was most pronounced in implanted ears treated with AP. CAP-audiograms revealed lower threshold shifts at all frequency ranges for steroid-treated animals. No correlation between mean threshold shift and extent of tissue growth was found regardless of the treatment. Furthermore, acute corticosteroid treatment did not suppress long-term tissue growth within the scala tympani. The results indicate that the two steroids reduced implantation-induced hearing loss even after an acute application. They did not however suppress tissue growth significantly compared to AP-treatment
Cisplatin-induced apoptosis in human promyelocytic leukemia cells
No full textCis-diamminedichloroplatinum (II) cisplatin (CDDP) is an
organometallic compound frequently used in anti-cancer therapy, in
particular ovarian, testicular, and head and neck tumors. We found
cisplatin was effective against human promyelocytic leukemia cell
line HL-60, inhibiting cell cycle progression and inducing time- and
concentration- dependent cell death. Presence of nuclear
fragmentation, caspase-3 cleavage and annexin V positivity suggests
cell death occurred by apoptosis, although DNA internucleosomal
fragmentation was not detected. In addition, analysis of
malondialdehyde (MDA) production and protein carbonylation indicated
that cisplatin increased lipid peroxidation and oxidation of cell
proteins. This occurrence was prevented by antioxidants such as
N-acetylcysteine (N-aC) and glutathione (GSH), which, consistently,
were also able to prevent CDDP-induced cell death. Collectively,
these findings indicate that, besides growth inhibition, an increase
of oxygen radicals and lipid degradation can account for a
significant part of CDDP-induced apoptosis
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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