1,720,967 research outputs found
Neuroprotective effects of intravenous anesthetics: A new critical perspective
No full textPerioperative cerebral damage can result in various clinical sequela ranging from minor
neurocognitive deficits to catastrophic neurological morbidity with permanent impairment and
death. The goal of neuroprotective treatments is to reduce the clinical effects of cerebral damage
through two major mechanisms: increased tolerance of neurological tissue to ischemia and
changes in intra-cellular responses to energy supply deprivation. In this review, we present the
clinical evidence of intravenous anesthetics on perioperative neuroprotection, and we also provide
a critical perspective for future studies. The neuroprotective efficacy of the intravenous anesthetics
thiopental, propofol and etomidate is unproven. Lidocaine may be neuroprotective in non-diabetic
patients who have undergoing cardiac surgery with cardiopulmonary bypass (CBP) or with a 48
hour infusion, but conclusive data are lacking. There are several limitations of clinical studies that
evaluate postoperative cognitive dysfunction (POCD), including difficulties in identifying patients
at high-risk and a lack of consensus for defining the “gold-standard” neuropsychological testing.
Although a battery of neurocognitive tests remains the primary method for diagnosing POCD,
recent evidence suggests a role for novel biomarkers and neuroimaging to preemptively identify
patients more susceptible to cognitive decline in the perioperative period. Current evidence, while
inconclusive, suggest that intravenous anesthetics may be both neuroprotective and neurotoxic in
the perioperative period. A critical analysis on data recorded from randomized control trials
(RCTs) is essential in identifying patients who may benefit or be harmed by a particular
anesthetic. RCTs will also contribute to defining methodologies for future studies on the
neuroprotective effects of intravenous anesthetic
Cardiac output changes after osmotic therapy in neurosurgical and neurocritical care patients: a systematic review of the clinical literature
No full textAIM
Osmotherapy constitutes a first-line intervention for intracranial hypertension management. However, hyperosmolar solutes
exert various systematic effects, among which their impact on systemic haemodynamics is poorly clarified. This review aims to
appraise the clinical evidence of the effect of mannitol and hypertonic saline (HTS) on cardiac performance in neurosurgical and
neurocritical care patients.
METHOD
A database search was conducted to identify randomized clinical trials and observational studies reporting HTS or mannitol use in
acute brain injury setting. The primary end-points were alterations of cardiac output (CO) and other haemodynamic variables,
while the impact of osmotic agents on intracranial pressure, brain relaxation, plasma osmolality, electrolyte levels and urinary
output constituted secondary outcomes.
RESULTS
Eight studies, enrolling 182 patients in total, were included. HTS exerted a more profound cardiac output augmentation than
mannitol, but no distinct difference between groups occurred. Central venous pressure, stroke volume and stroke volume
variation were favourably affected by both osmotic agents, whilst the reported changes in blood pressure were inconclusive. HTS
infusion yielded a larger intracranial pressure reduction than mannitol but had an equivalent effect on brain relaxation. Mannitol
presented a more potent diuretic effect than HTS. Effect on serum osmolality was alike in both osmotic agents, but contrary to
HTS-promoted hypernatraemia, mannitol use induced transient hyponatraemia.
CONCLUSIONS
Mannitol or HTS administration seems to induce an enhancement of cardiac performance; being more prominent after HTS
infusion. This effect combined with mannitol-induced enhancement of diuresis and HTS-promoted increase of plasma sodium
concentration could partially explain the effects of osmotherapy on cerebral haemodynamics
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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