1,720,977 research outputs found
The Role of Methemoglobin and Carboxyhemoglobin in COVID-19: A Review
Full text linkFollowing the outbreak of a novel coronavirus (SARS-CoV-2) associated with pneumonia in China (Corona Virus Disease 2019, COVID-19) at the end of 2019, the world is currently facing a global pandemic of infections with SARS-CoV-2 and cases of COVID-19. Since severely ill patients often show elevated methemoglobin (MetHb) and carboxyhemoglobin (COHb) concentrations in their blood as a marker of disease severity, we aimed to summarize the currently available published study results (case reports and cross-sectional studies) on MetHb and COHb concentrations in the blood of COVID-19 patients. To this end, a systematic literature research was performed. For the case of MetHb, seven publications were identified (five case reports and two cross-sectional studies), and for the case of COHb, three studies were found (two cross-sectional studies and one case report). The findings reported in the publications show that an increase in MetHb and COHb can happen in COVID-19 patients, especially in critically ill ones, and that MetHb and COHb can increase to dangerously high levels during the course of the disease in some patients. The medications given to the patient and the patient’s glucose-6-phospate dehydrogenase (G6PD) status seem to be important factors determining the severity of the methemoglobinemia and carboxyhemoglobinemia. Therefore, G6PD status should be determined before medications such as hydroxychloroquine are administered. In conclusion, MetHb and COHb can be elevated in COVID-19 patients and should be checked routinely in order to provide adequate medical treatment as well as to avoid misinterpretation of fingertip pulse oximetry readings, which can be inaccurate and unreliable in case of elevated MetHb and COHb levels in the blood
Meningeal lymphatic vessels in the human head: Examples of in vivo visualization with high-resolution 3T MRI
Full text linkIn 2015, meningeal lymphatic vessels (mLVs) were (re)discovered in mice and human dura specimens. Two years later, the first report was published showing that mLVs can be detected in humans in vivo by high-resolution 3 Tesla magnetic resonance imaging (MRI). In 2017 and 2018, two further studies reported the successful MRI-based detection of mLVs in vivo in humans. The aim of our study was to provide further evidence of the possibility to detect mLVs in vivo with MRI in humans. To this end, MR images already available from one subject (the first author) were analyzed. We detected mLVs in the coronal plane at the bilateral superior lateral corners of the superior sagittal sinus (SSS) as well as below the SSS, in agreement with the two other published reports about the in vivo detection of mLVS in humans with MRI. Our report is thus, to the best of our knowledge, the fourth published report about in vivo MR imaging of human mLVs
Impairment of the Blood-Brain-Barrier: Evaluation of Pharmacological Postconditioning with Sevoflurane
No full textThe blood-brain barrier (BBB) strictly limits the flux from the blood to the brain. The BBB thereby protects the brain against harmful blood-derived substances and simultaneously allows the supply with essential nutrients. The disruption of the BBB accompanies many neurological disease conditions, such as those induced by trauma, hypoxia, metabolic abnormalities or inflammation. The grade of brain edema formation, which is one clinical representation of BBB impairment, has been shown to be an independent predictor of unfavorable patient outcome.
Treatment options for BBB protection are still rare, partially due to the fact that only few substances can sufficiently cross this barrier. Promising drugs are lipophilic molecules such as volatile anesthetics which have been shown to be beneficial in cases of hypoxia reoxygenation injury (H/R) in the heart, liver, lung and kidney. Whether and how such compounds change intracranial pressure is still a matter of debate. Although of high clinical relevance, only few data are available concerning the action of volatile anesthetics on the BBB.
In order to tackle this problem, this dissertation aimed to elucidate whether and how volatile anesthetics impact the BBB through two specific projects addressing the following questions:
1. Does sevoflurane impact brain endothelial cells after H/R injury? And which signaling pathways are involved?
2. Does brain inflammation change in response to sevoflurane treatment in an animal model of sepsis? And which signaling pathways are involved and modified?
Immortalized rat brain endothelial cells (RBE4) were used to assess the effect of sevoflurane treatment after H/R injury, in a so called postconditioning setup, where cells are exposed to sevoflurane after initiation of injury. For this reason, permeability as well as tight and adherens junctions’ architecture were further analyzed. In order to detect potential mediators of the response, reactive oxygen species (ROS), inflammatory mediators (IL-6, TNF alpha, MMP9), protein kinase C (PKC) and vascular endothelial growth factor (VEGF) were quantified in the cells’ supernatant. Using this approach, we demonstrated that sevoflurane changes the permeability pattern in rat brain endothelial cells and modifies the architecture of the junctional components ZO-1 and β-catenin. ROS, PKC and VEGF were shown to be downregulated in response to sevoflurane treatment. Interestingly, RBE4 cells did not show any inflammatory response after H/R alone. In experiments in a rat animal model of sepsis, neuroinflammation with and without sevoflurane post-conditioning was assessed in more detail by our team. Inflammatory body response was significantly decreased due to sevoflurane treatment, but neuroinflammation was not affected.
Taking those studies together, we conclude that sevoflurane reduces barrier leakage of rat brain endothelial cells, modifies the cytoskeleton and junctional components and reduces important mediators of H/R injury such as ROS, PKC and VEGF. In contrast to its systemic action, sevoflurane does not alleviate early inflammatory response in the brain. Nevertheless, it is tempting to further elucidate the effects of sevoflurane postconditioning in patients
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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