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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
Bioverfügbarkeit des Flavonols Quercetin beim Hund
Full text link6 Zusammenfassung
Marianne Reinboth
Bioverfügbarkeit des Flavonols Quercetin beim Hund
Veterinär-Physiologisches Institut der Veterinärmedizinischen Fakultät der Universität Leipzig
Eingereicht im Juni 2010
79 Seiten, 20 Abbildungen, 6 Tabellen, 211 Literaturangaben, 1 Anhang
Schlüsselwörter: Quercetin, Bioverfügbarkeit, Hund, absolute Bioverfügbarkeit, Isoquercitrin, Rutin, Flavonole
Für das pflanzliche Flavonol Quercetin werden vielfältige gesundheitsfördernde Wirkungen postuliert, so auch bei Hunden. Über die Bioverfügbarkeit des Flavonols bei dieser Spezies liegen bislang jedoch keinerlei Daten vor. Daher hatte diese Arbeit das Ziel, Bioverfügbarkeit und pharmakokinetische Parameter von Quercetin und wichtigen Quercetinglycosiden bei Hunden nach deren Verabreichung mit einer Testmahlzeit in einer praxisrelevanten Dosierung von 10 mg/kg Körpermasse zu untersuchen.
Dazu erhielten 9 adulte Beagles beiderlei Geschlechts das zuckerfreie \"Aglycon\" Quercetin bzw. seine Glycoside Isoquercitrin (Quercetin-3-O-Glucosid) und Rutin (Quercetin-3-O-Glucorhamnosid) in jeweils äquimolarer Dosierung in einer Testmahlzeit verabreicht. Anschließend wurden Blutproben über einen Zeitraum von bis zu 72 Stunden entnommen und mittels HPLC die Konzentrations-Zeitverläufe der Metaboliten im Blutplasma, die Bioverfügbarkeit sowie weitere pharmakokinetische Parameter bestimmt. Weiterhin wurde die absolute Bioverfügbarkeit von Quercetin aus dem Vergleich einer oralen mit einer intravenösen Applikation bestimmt.
Der weitaus größte Teil der Plasmametaboliten von Quercetin sowie seiner beiden Glycoside bestand aus glucuronidierten bzw. sulfatierten Quercetinkonjugaten. Nicht konjugiertes Quercetin-Aglycon kam nur in einem Anteil von etwa 20 % vor. Neben Quercetin machten seine Metaboliten Isorhamnetin und Kämpferol weniger als 10 % aller im Plasma zirkulierenden Flavonole aus. Die absolute Bioverfügbarkeit von Quercetin betrug nur etwa 4 %.
Die relative Bioverfügbarkeit aus dem 3-O-Glucosid Isoquercitrin war mehr als doppelt so hoch wie aus dem Aglycon, die maximalen Plasmaspiegel lagen aber auch hier unter 1 µmol/l. Sowohl nach Aufnahme von Quercetin als auch nach Isoquercitrin kam es zu einer relativ schnellen Absorption aus dem Dünndarm mit einem ersten Plasmapeak ungefähr eine Stunde nach der Ingestion. Vier Stunden nach Aufnahme der beiden Flavonole trat ein zweiter Plasmapeak auf, der in der Regel höher als der erste ausfiel. Dies deutet auf einen enterohepatischen Kreislauf der über die Galle ausgeschiedenen Metaboliten hin.
Nach Aufnahme von Rutin kam es zu einer verzögerten Absorption, da eine Deglycosylierung durch bakterielle Glycosidasen im Dickdarm Voraussetzung für die Absorption des Flavonols ist. Maximale Plasmakonzentrationen wurden im Mittel erst 11 Stunden nach Ingestion dieses Glycosids erreicht. Die maximalen Plasmakonzentra-tionen nach Rutin waren geringer als nach Quercetin oder Isoquercitrin, jedoch war die mittlere Verweildauer der Plasmametaboliten mit 18 Stunden auch wesentlich länger. Im Unterschied zu anderen Spezies war die relative Bioverfügbarkeit von Rutin gegenüber Quercetin nicht verringert.
Obwohl Rutin eine relativ gute Quercetinquelle für Hunde zu sein scheint, muss bei der Einschätzung möglicher In-vivo-Wirkungen die relativ geringe Bioverfügbarkeit sowie die intensive Metabolisierung seines Aglycons Quercetin berücksichtigt werden.:1 Einleitung 1
2 Literaturübersicht 3
2.1 Funktionen von Flavonoiden in Pflanzen 3
2.2 Biosynthese und Struktur von Flavonoiden 4
2.3 Flavonoidwirkungen im menschlichen und tierischen Organismus 7
2.3.1 Antioxidative Eigenschaften 10
2.3.2 Wirkungen auf Enzyme und Transportproteine des Arzneistoffwechsels 12
2.4 Bioverfügbarkeit und Stoffwechsel des Flavonols Quercetin 13
2.4.1 Bioverfügbarkeit von Quercetin 13
2.4.2 Einfluss des Futters 15
2.4.3 Einfluss des Glycosylierungsmusters 16
2.4.4 Intestinale Absorption und Metabolismus 18
2.4.5 Einfluss der intestinalen Mikroflora 21
2.4.6 Bindung an Plasmaproteine 22
2.4.7 Gewebeverteilung 23
2.4.8 Exkretion 24
2.5 Zielsetzung 25
3 Tiere, Material und Methoden 26
3.1 Versuchstiere und Haltungsbedingungen 26
3.2 Verwendete Flavonole 27
3.3 Durchführung des Tierversuchs 28
3.3.1 Allgemeine Durchführung der Versuche 28
3.3.2 Bioverfügbarkeit von Quercetin und Rutin (je 30 mg/kg KM) 29
3.3.3 Absolute Bioverfügbarkeit von Quercetin 30
3.3.4 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 31
3.4 Probenaufarbeitung 31
3.5 HPLC 33
3.5.1 Methodenvalidierung und -kalibrierung 34
3.5.2 Berechnung der pharmakokinetischen Parameter 40
3.5.3 Statistische Auswertung 41
4 Ergebnisse 42
4.1 Bioverfügbarkeit von Quercetin und Rutin (je 30 mg/kg KM) 42
4.1.1 Quercetin-Aglycon 42
4.1.2 Rutin 46
4.2 Absolute Bioverfügbarkeit Quercetin 48
4.3 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 52
4.3.1 Quercetin-Aglycon 53
4.3.2 Rutin 56
4.3.3 Isoquercitrin 57
5 Diskussion 62
5.1 Zielsetzung der Studie 62
5.2 Methodische Aspekte 62
5.2.1 Auswahl der Versuchstiere und Versuchsanordnung 62
5.2.2 Wahl der Testmahlzeit 63
5.2.3 Einfluss der Zeitpunkte für die Probennahme auf die Berechnung der Verfügbarkeit 64
5.2.4 Analysemethode 65
5.3 Plasmametaboliten von Quercetin 66
5.4 Absolute Bioverfügbarkeit von Quercetin 69
5.5 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 70
5.5.1 Isoquercitrin 70
5.5.2 Rutin 71
5.6 Bezug der pharmakokinetischen Daten zu potentiellen In-vivo-Wirkungen 73
5.7 Schlussfolgerungen 75
6 Zusammenfassung 76
7 Summary 78
8 Literaturverzeichnis 80
9 Anhang 102
9.1 HPLC-Chemikaien 102
9.2 Validierung der HPLC-Methode 103
Danksagung 1097 Summary
Marianne Reinboth
Bioavailability of the Flavonol Quercetin in Dogs
Institute of Physiology of the Faculty of Veterinary Medicine, University of Leipzig
Submitted in June 2010
79 pages, 20 figures, 6 tables, 211 references, 1 appendix
Keywords: quercetin, bioavailability, dog, absolute bioavailability, isoquercitrin,
rutin, flavonols
The plant flavonol quercetin is supposed to exert multiple health-related effects in dogs. To date no information on its bioavailability in this particular species is avai-lable. This study intended to investigate bioavailability and pharmacokinetics of quercetin and certain quercetin glycosides in dogs after ingestion of a test meal sup-plemented with a quercetin dose equivalent to 10 mg/kg body weight.
Nine adult beagle dogs of both sexes received the aglycon quercetin (sugarfree) or its glycosides isoquercitrin (quercetin-3-O-glucoside) and rutin (quercetin-3-O-glucorhamnoside) in equimolar amounts together with a test meal. Blood samples were taken over a period of up to 72 hours; bioavailability and pharmacokinetics were calculated from the HPLC-derived plasmaconcentration-time-curves. Absolute bioavailability was calculated by comparing an oral to an intravenous administration of quercetin.
The majority of analysed plasma metabolites were glucuronidated and sulfated con-jugates of quercetin. Non-conjugated quercetin aglycon comprised only 20 %. Be-sides quercetin, its metabolites isorhamnetin and kaempferol made up less than 10 % of all circulating metabolites. The absolute bioavailability of quercetin was only 4 %.
The relative bioavailability of quercetin from isoquercitrin was more than twice as high than from the aglycon, but even there maximal plasma concentrations were generally less than 1 μmol/l. Absorption from the small intestine was rather fast with a first plasma peak after 1 hour after ingestion of quercetin or isoquercitrin. A second, generally higher plasma peak occurred 4 hours after ingestion. This suggests an in-tensive enterohepatic recycling of biliary secreted metabolites.
Absorption was significantly delayed after ingestion of rutin due to the necessity of bacterial deglycosilation in the large intestine. Plasma concentrations peaked only after 11 hours. Plasma concentrations after rutin were lower than after quercetin or isoquercitrin, but mean residence time of plasma metabolites was as long as 18 hours after rutin ingestion. Consequently, a once daily feeding of dogs with rutin might lead to relatively constant plasma metabolite concentrations. In contrast to other species, bioavailability from rutin was not smaller than that from quercetin.
Although rutin seems to be a relative good quercetin source for dogs, estimations about potential in-vivo-effects of quercetin have to take into consideration its low bioavailabilty and intensive metabolism.:1 Einleitung 1
2 Literaturübersicht 3
2.1 Funktionen von Flavonoiden in Pflanzen 3
2.2 Biosynthese und Struktur von Flavonoiden 4
2.3 Flavonoidwirkungen im menschlichen und tierischen Organismus 7
2.3.1 Antioxidative Eigenschaften 10
2.3.2 Wirkungen auf Enzyme und Transportproteine des Arzneistoffwechsels 12
2.4 Bioverfügbarkeit und Stoffwechsel des Flavonols Quercetin 13
2.4.1 Bioverfügbarkeit von Quercetin 13
2.4.2 Einfluss des Futters 15
2.4.3 Einfluss des Glycosylierungsmusters 16
2.4.4 Intestinale Absorption und Metabolismus 18
2.4.5 Einfluss der intestinalen Mikroflora 21
2.4.6 Bindung an Plasmaproteine 22
2.4.7 Gewebeverteilung 23
2.4.8 Exkretion 24
2.5 Zielsetzung 25
3 Tiere, Material und Methoden 26
3.1 Versuchstiere und Haltungsbedingungen 26
3.2 Verwendete Flavonole 27
3.3 Durchführung des Tierversuchs 28
3.3.1 Allgemeine Durchführung der Versuche 28
3.3.2 Bioverfügbarkeit von Quercetin und Rutin (je 30 mg/kg KM) 29
3.3.3 Absolute Bioverfügbarkeit von Quercetin 30
3.3.4 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 31
3.4 Probenaufarbeitung 31
3.5 HPLC 33
3.5.1 Methodenvalidierung und -kalibrierung 34
3.5.2 Berechnung der pharmakokinetischen Parameter 40
3.5.3 Statistische Auswertung 41
4 Ergebnisse 42
4.1 Bioverfügbarkeit von Quercetin und Rutin (je 30 mg/kg KM) 42
4.1.1 Quercetin-Aglycon 42
4.1.2 Rutin 46
4.2 Absolute Bioverfügbarkeit Quercetin 48
4.3 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 52
4.3.1 Quercetin-Aglycon 53
4.3.2 Rutin 56
4.3.3 Isoquercitrin 57
5 Diskussion 62
5.1 Zielsetzung der Studie 62
5.2 Methodische Aspekte 62
5.2.1 Auswahl der Versuchstiere und Versuchsanordnung 62
5.2.2 Wahl der Testmahlzeit 63
5.2.3 Einfluss der Zeitpunkte für die Probennahme auf die Berechnung der Verfügbarkeit 64
5.2.4 Analysemethode 65
5.3 Plasmametaboliten von Quercetin 66
5.4 Absolute Bioverfügbarkeit von Quercetin 69
5.5 Relative Bioverfügbarkeit verschiedener Quercetinglycoside 70
5.5.1 Isoquercitrin 70
5.5.2 Rutin 71
5.6 Bezug der pharmakokinetischen Daten zu potentiellen In-vivo-Wirkungen 73
5.7 Schlussfolgerungen 75
6 Zusammenfassung 76
7 Summary 78
8 Literaturverzeichnis 80
9 Anhang 102
9.1 HPLC-Chemikaien 102
9.2 Validierung der HPLC-Methode 103
Danksagung 10
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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