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Intensified mitochondrial hydrogen peroxide release occurs in all brain regions, affects male as well as female Rett mice, and constitutes a life-long burden
No full textRetraction notice to “Intensified mitochondrial hydrogen peroxide release occurs in all brain regions, affects male as well as female Rett mice, and constitutes a life-long burden” [Arch. Biochem. Biophys. 696 (15 December 2020) 10866]
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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
Therapeutic benefit of mitochondrial catalase expression in a mouse model of Rett syndrome
No full textDas Rett-Syndrom ist eine schwer verlaufende, neurologische Entwicklungsstörung die hauptsächlich Mädchen mit einer Prävalenz von 1:10.000 bis 1:15.000 betrifft. Das klinische Erscheinungsbild ist komplex und manifestiert sich durch kognitive Beeinträchtigungen, unregelmäßige Atmung, motorische Koordinationsprobleme und Epilepsie. Im Rett-Syndrom lassen sich sowohl mitochondriale Veränderungen als auch der durch oxidativen Stress entstandene Hirnschaden bereits einige Wochen vor dem Auftreten klinischer Symptome beobachten, sodass die Vermutung besteht, dass die mitochondriale Beeinträchtigung für die Progression der Krankheit von größerer Bedeutung ist. Therapeutische Ansätze, die das Redox-Gleichgewicht in den Mausmodellen des Rett-Syndroms stabilisieren oder die mitochondriale Funktion verbessern, können daher möglicherweise das Auftreten von Symptomen verzögern oder den Schweregrad des Krankheitsverlaufes mildern. In der aktuellen Literatur wurde hauptsächlich der Effekt nicht enzymatischer Antioxidantien auf die Redox-Imbalance im Rett-Syndrom untersucht. In wie weit sich jedoch eine erhöhte Expression antioxidativ wirkender Enzyme auswirkt stand bis dato noch aus. Ziel dieser Arbeit war es demnach, die Redox-Imbalance im Rett-Syndrom hirnregionen-, entwicklungsstadien- und geschlechtsspezifisch zu untersuchen, sowie den therapeutischen Nutzen einer mitochondrialen Katalase-Expression auf die erhöhte H2O2-Freisetzung im Mausmodell des Rett-Syndroms zu evaluieren. Ergänzend sollten auch mögliche Verbesserungen des allgemeinen phänotypischen Erscheinungsbildes der Tiere bewertet werden, indem Größe, Gewicht, Blutglukosespiegel und Hämatokrit untersucht wurden.
Im Zuge der Datenerhebung wurden Mitochondrien der Hirnregionen Kortex,
Hippocampus, Kleinhirn, Mittelhirn und Hirnstamm isoliert und in fluoreszenzspektrometrischen Messungen deren H2O2-Freisetzung quantifiziert. Die Reinheit der genutzten, angereicherten Mitochondriensuspension wurde mit Hilfe von Western-Blots beurteilt. Es wurde bewiesen, dass die mitochondriale H2O2-Freisetzung im Rett-Syndrom in allen Hirnregionen und allen Altersstufen unabhängig vom Geschlecht signifikant erhöht ist. Außerdem wurde gezeigt, dass durch die Expression der mitochondrialen Katalase die H2O2-Freisetzung im Rett-Syndrom sowohl bei den P50-Männchen als auch bei den P50- und P200-Weibchen signifikant gesenkt werden kann. Bei den P400-Weibchen ist dieser Effekt hingegen nicht mehr zu beobachten. Körpergröße und Körpergewicht sind im Rett-Syndrom bei den P50-Weibchen und Männchen signifikant reduziert, wobei die Expression der mitochondrialen Katalase jedoch keinen positiven Einfluss auf die phänotypischen allgemeinen Parameter wie Größe, Gewicht, Blutglukose und Hämatokrit der Tiere vermittelte.
Zusammenfassend kann die mitochondriale Katalase-Expression im Rett-Syndrom als möglicher Therapieansatz in Betracht gezogen werden, um einen positiven Einfluss auf die zelluläre Redox-Imbalance der Erkrankung zu nehmen.Rett syndrome is a severe neurodevelopmental disorder that mainly affects girls with a prevalence of 1: 10,000 to 1: 15,000. The clinical symptoms are complex and are characterized by cognitive impairment, irregular breathing, motor dysfunction, and epilepsy. The pathogenesis includes, among others, mitochondrial impairment, redox imbalance, and oxidative tissue damage. In Rett syndrome, both mitochondrial changes and the tissue damage caused by oxidative stress occur already a few weeks earlier than the typical clinical symptoms, suggesting that the mitochondrial impairment may be of potential importance for the progression of the disease. Therapeutic approaches that improve the redox homeostasis in mouse models of Rett syndrome can therefore be assumed to stabilize also mitochondrial function, which may then delay the onset of symptoms or reduce the disease severity. In the recent literature mainly the effect of non-enzymatic antioxidants on the redox imbalance in Rett syndrome has been reported. However, to what extent an increased expression of antioxidant enzymes is mediating a positive impact on cellular redox-homeostasis has not been studied yet. Therefore, the aim of this thesis was to assess the redox imbalance in Rett syndrome in different mouse brain regions, stages of development and both genders, by using sophisticated multi-sample spectrofluorimetry. H2O2 release by isolated mitochondria was quantified in a coupled reaction of Amplex UltraRed and horseradish peroxidase. Furthermore, the therapeutic benefit of a mitochondrial catalase expression on the exaggerated H2O2 release in a mouse model of Rett syndrome was evaluated. Possible improvements in the general phenotypic appearance of the animals were assessed by measuring body length, body weight, blood glucose levels, and hematocrit.
In detail, mitochondria of the brain regions cortex, hippocampus, cerebellum, midbrain and brain stem were isolated and analyzed in fluorometric measurements. The purity of the enriched mitochondrial suspensions was determined by Western blots. Mitochondrial H2O2 release in Rett syndrome was significantly increased in all brain regions and at all ages regardless of gender. It also became evident that by expression of a mitochondrial catalase, the H2O2 release in Rett syndrome in P50 males as well as P50 and P200 females can be reduced significantly. In the P400 females this effect was no longer detectable though. Body length and body weight are significantly reduced in P50 female and male Rett mice. However, expression of the mitochondrial catalase did not noticeably ameliorate these phenotypic general parameters. In summary, mitochondrial catalase expression in Rett syndrome can be considered as a possible therapeutic approach, which is clearly capable of counteracting the the cellular redox imbalance in this disorder.2021-10-2
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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