1,720,953 research outputs found
Optimization of a method for determination of bleomycin in biological samples
No full textBleomicin je zmes glikopeptidnih antibiotikov izoliranih iz Streptomyces verticillus, ki so učinkoviti pri zdravljenju številnih vrst raka. Ker ima tudi bleomicin neželene učinke, zlasti toksično delovanje na pljuča, je med terapijo pomembno spremljanje njegove koncentracije v krvi. Zaradi kompleksnosti njegove strukture, polarnosti in sposobnosti keliranja kovin pa je metodo za določanje bleomicina v bioloških vzorcih izjemno zahtevno razviti. V magistrski nalogi smo skušali optimizirati metodo, ki so jo razvili Kosjek s sodelavci, in sicer predvsem s ciljem prenosa ekstrakcije na trdnem nosilcu iz vakuumskega sistema s kolonami na nadtlačni sistem z mikrotitrskimi ploščami, ki je primernejši za ekstrakcijo večjega števila bioloških vzorcev. Na ta način smo želeli poenostaviti pripravo vzorca, skrajšati čas priprave in izboljšati izkoristek ekstrakcije bleomicina iz vzorcev. Izkazalo se je, da je izkoristek ekstrakcije BLM po prenosu metode na mikrotitrske plošče sicer malenkost nižji, ampak ta razlika ni pomembna, če upoštevamo poenostavitev metode. Na mikrotitrskih ploščah smo optimizirali tudi sestavo elucijskega topila. Nadalje smo poskušali postopek skrajšati tako, da smo plazemske oz. serumske vzorce injicirali direktno po denaturaciji in centrifugiranju, torej brez ekstrakcije na SPE ploščah. Rezultati so bili obetavni zgolj pri serumskih vzorcih, pri čemer je bil izkoristek boljši pri nižjem volumnu seruma kot pri višjem. Matriks vzorca namreč inhibira signal našega analita v masnem spektrometru, kar je intenzivneje pri večjem volumnu seruma. Inhibicija je pri plazmi še izrazitejša, zato smo odločili, da ta metoda ni primerna za direktno injiciranje.
Metodo za ekstrakcijo BLM iz seruma in tumorskih tkiv smo optimizirali ter ovrednotili vpliv mase tkiva oziroma volumna biološkega vzorca na odziv masnega detektorja. Pri validaciji metode smo sledili smernicam Ameriškega urada za hrano in zdravila (FDA), kjer je bilo to smiselno in mogoče. Zaradi odkrite slabše robustnosti kromatografije internega standarda epirubicina smo se odločili, da ni primeren za to nalogo. Uporabno območje razvite metode za serum je od 100 do 5000 ng/mL, za tumorsko tkivo pa od 50 do 2500 ng/g.Bleomycin is a mixture of cytotoxic glycopeptide antibiotics isolated from a strain of Streptomyces verticillus. It is efficient in treatment of many neoplastic tissues. Nevertheless, bleomycin has side effects, mostly on pulmonary tissue. Consequently, bleomycin blood level should be monitored. Because of structure complexity, polarity and ability to chelate metals it is very difficult to set sensitive and selective analytical method for its determination in biological tissues.
In our work, we tried to optimize the method which was developed in following research Kosjek et al. Mostly with goal to transfer solid phase extraction from cartridge where we used low pressure to microplates under high pressure, which are more appropriate for extraction of multiple biological samples.
The goal was to simplify sample preparation, reduce time and increase efficiency of extraction of bleomycin from samples. The method was successfully transferred although efficiency of bleomycin extraction on microplate was lower. Within microplate we optimized composition of the elution solvent. Additionally, we tried to shorten the process with direct injection of blood samples after denaturation and centrifugation without the extraction using SPE microplates step. Results were relevant only for serum samples. Better results were with lower volume samples than higher volume samples. In mass spectrometer bleomycin detection is suppressed by matrix, especially in higher volume serum samples. Suppression is even greater in plasma samples, which is why we decided that it is not appropriate for direct injection.
We optimised the method for extraction of bleomycin from serum and tumor tissue and evaluated how mass of tissue and volume of biological sample influence to the mass detector response. In validation process we followed U.S Food and drug administration guidelines where this was reasonable and possible. Due to the poor robustness of internal standard in chromatography we decided that it is not suitable for this task. The working range of analytical method for serum is from 100 ng/mL to 5000 ng/mL and for tumor tissue from 50 to 2500 ng/g
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
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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