1,720,956 research outputs found
BIOCHEMICAL STUDIES OF GENETIC VARIANTS OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE IN NIGERIA
No full textA THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF THE UNIVERSITY OF IBADAN, NIGERIA.Comparative biochemical studies have been carried out on five genetic variants of human erythrocyte glucose-6-phosphate dehydrogenase in Nigeria. These variants A, A-, B, Ijebu-Ode and Ita-Bale in order of decreasing electrophoretic mobility, are found with different frequencies in Nigeria. The first three variants are common (A- is associated with deficiency) while the latter two are rare (below polymorphic frequency) and have been characterised for the first time.
(2) Partially purified preparations of the five enzyme types, have been used in a number of kinetic studies. All the variants have approximately the same affinity for glucose-6-phosphate but when the substrate analogue 2-deoxy glucose-6-phosphate is used, Ijebu-Ode emerges as the variant with the lowest affinity for it. The effect of pH on the activities of the two rare variants (carried out according to WHO recommendation) indicate that both of them have a slightly biphasic pattern. The rate of inactivation of the two rare variants as compared with the B variant show that Ita-Bale had a minimally increased thermolability while the thermolability of Ijebu-Ode was markedly increased.
(3) A detailed analysis of how pH affects two main kinetic parameters of enzyme reactions, namely Vmax and Km, for glucose 6-phosphate has been carried out for all the variants. For all pH (using tris-borate-citrate, tris-borate, tris-borate-buffers) over the entire range explored from pH 5.5 to 9.5. In addition, A, Ijebu-Ode and Ita-Bale have a plateau in the pH region between 7.5 and 8.2, whereas A and B have a ‘peak and trough’ in the same region. Characteristic patterns were obtained for each variant on plotting log
Vmax, log Km and log Vmax / Km versus pH. From the waves in the plots, the pKs corresponding to ionised imidazolium and thiol residues in free enzymes and enzyme-substrate complexes were obtained. The data also indicate the absence of thiol residue in or near the active centre of Ijebu-Ode. The Km data obtained for type A- have not been always consistent and a possible explanation is presented.
(4) The dependence of enzyme activity on NADP and NADPH concentration was examined for the five variants. Sigmoidal saturation kinetics of A, B and Ita-Bale variants for NADP clearly differentiate them from the near-hyperbolic kinetics of A and Ijebu-Ode enzyme types. Two dissociation constants (Ks₁ and Ks2 ), corresponding to states of low and high affinity for NADP, have been, obtained for each variant. An explanation about the mechanism of such interactions is also presented. The complex kinetics of interaction of the enzyme variants with NADPH has implicated this metabolite as both an activator and inhibitor, but A- type emerges as the least activated and inhibited. The sum total of the interactions of G6PD with NADP and its metabolite, NADPH, has led to the suggestion that G6PD is a regulatory (allosteric) protein.
(5) The five genetic variants exhibit differential interactions with some potent inhibitors which bind to the sulphydryl groups, like N-ethylmaleimide and p-chloromercuribenzoate. Of all the variants, Ijebu-Ode is strickingly resistant to PCMB and totally resistant to NEM. An explanation for the resistance of Ijebu-Ode to these inhibitors is suggested.
(6) Enzyme inactivation as a function of temperature exhibits distinctive profiles for all the variants and Ijebu-Ode particularly displayed a unique picture. The implication of the differences observed in this thermal inactivation profile studies are also discussed.
(7) Finally, it is suggested that differences observed in the catalytic and kinetic properties among the five variants of G6PD are a reflection of the structural differences among them which also implies different mutational changes in the structural locus for red cell glucose-6-phosphate dehydrogenase
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
