1,721,001 research outputs found
Nitric oxide in the injured spinal cord: Synthases cross-talk, oxidative stress and inflammation
No full textNitric oxide (NO) is a unique informational molecule involved in a variety of physiological
processes in the central nervous system (CNS). It has been demonstrated that it can exert
both protective and detrimental effects in several disease states of the CNS, including spinal
cord injury (SCI).
The effects of NO on the spinal cord depend on several factors such as: concentration of
produced NO, activity of different synthase isoforms, cellular source of production and time
of release. Basically, it has been shown that low NO concentrations may play a role in
physiologic processes, whereas large amounts of NO may be detrimental by increasing
oxidative stress. However, this does not explain all the discrepancies evidenced studying the
effects of NO in SCI models. The analysis of the different synthase isoforms, of their
temporal profile of activation and cellular source has shed light on this topic. Two postinjury
time intervals can be defined with reference to the NO production: immediately after
injury and several hours-to-days later. The initial immediate peak of NO production after
injury is due to the up-regulation of the neuronal NO synthase (nNOS) in resident spinal cord
cells. The late peak is due primarily to the activity of inducible NOS (iNOS) produced by
inflammatory infiltrating cells. High NO levels produced by up-regulated nNOS and iNOS are
neurotoxic; the down-regulation of nNOS corresponds temporally to the expression of iNOS.
On the bases of those evidence, therapeutic approaches should be aimed: (1) to reduce the
NO-elicited damage by inhibition of specific synthases according to the temporal profile of
activation; (2) by maintaining physiologic amount of NO to keep the induction of iNO
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
Cerebral venous sinus thrombosis due to spontaneous, progressive, and retrograde jugular vein thrombosis causing sudden death in a young woman
No full textCerebral venous sinus thrombosis (CVST) is a rare cerebrovascular condition that affects approximately 5 per 1 million people annually, and develops in 0.5 % of all stroke patients. Herein we report a case involving a 31-year-old woman with CVST. She initially presented with a 2-month history of intermittent headaches at the nape of her neck with cervical pain. Other than these symptoms, she was in apparently good health and was a nonsmoker. She had no children and did not take contraceptives. She became comatose with unequal pupil size and CVST was diagnosed. An autopsy revealed CVST that extended from the confluence of the sinuses to the transverse sinuses and tip of the superior sagittal sinus, as well as a thrombus that obstructed the right internal jugular vein. A correct and early diagnosis of CVST combined with heparin-based therapy and/or interventional endovascular strategies may be of benefit by preventing intracerebral extension of jugular venous thrombosis and subsequent serious or even fatal neurological sequelae
Spinal cordectomy for the management of thoracic malignant intraspinal tumors in paraplegic or irreversibly, severely paraparetic patients. A technical remark
No full textBackground: Malignant Intramedullary Spinal Cord Tumor are a relatively uncommon entity affecting patients whose prognosis is quickly and relentlessly dismal. Since the ‘50s Spinal Cordectomy’ has been advocated for the surgical management of these conditions, but to date, no standard operative protocol has been reported yet. Objective: Although apparently “easy”, burdened by virtually no further risk for the neurological function in paraplegic or severely paraparetic patients, SCt conceals notable pitfalls and surgical problems that are to date not yet completely discussed. The objective of the present paper is therefore to report a detailed stepwise description of the surgical technique. Methods and results: SCt addresses the problem of reaching a surgical radicality in patients whom neurological preoperative conditions have already irreversibly declined to a deep nonfunctional motor impairment and whose preoperative Brain MRI scan rules out intracranial seeding. The dural sac along with the radicular pouches must be considered as possible seeding and recurrence locations therefore such structure should be “en-bloc” removed. The cranial medullary end of the resection should be identified on the ground of the preoperative MRI and intraoperatively confirmed with fresh histological examinations ruling out the presence of tumor cells above the cordectomy. Due to the topographic and functional medullary arterial anatomy, no SCt should be performed above T3. The risk of postoperative sagittal imbalance is high and therefore a concurrent posterior vertebral stabilization is required. Conclusion: Spinal Cordectomy is a safe and feasible “last chance” treatment to prolong survival in paraplegic or severely paraparetic patients
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