1,721,020 research outputs found
Biochemistry of non-protein nitrogenous compounds in fish including the use of amino acids for anaerobic energy production
No full textWhiplash, real or not real? A review and new concept
No full textWhiplash-associated disorder (WAD) describes a heterogeneous group of symptoms, which develops frequently after an unexpected rear-end car collision. In some of these patients, the symptoms persist for years. There is an ongoing scientific debate about the existence of tissue injury to support this disorder, due to the lack of findings with current diagnostic techniques and the prevalence of emotional traits as risk factors. The purpose of this chapter is to (1) overview the scientific data regarding the presence of an injury mechanism as a consequence of the whiplash trauma, (2) remark the unexpectedness of the accident as essential, and (3) present a new concept according to which WAD symptoms are the result of a mismatch between aberrant information from the cervical spinal cord and the information from the vestibular and visual systems, all of which are integrated in the mesencephalic periaqueductal gray and adjoining regions
Pharmacokinetic Modeling of [ 18 F]MC225 for Quantification of the P-Glycoprotein Function at the Blood-Brain Barrier in Non-Human Primates with PET
Full text link[18F]MC225 has been developed as a weak substrate of P-glycoprotein (P-gp) aimed to measure changes in the P-gp function at the blood–brain barrier with positron emission tomography. This study evaluates [18F]MC225 kinetics in non-human primates and investigates the effect of both scan duration and P-gp inhibition. Three rhesus monkeys underwent two 91-min dynamic scans with blood sampling at baseline and after P-gp inhibition (8 mg/kg tariquidar). Data were analyzed using the 1-tissue compartment model (1-TCM) and 2-tissue compartment model (2-TCM) fits using metabolite-corrected plasma as the input function and for various scan durations (10, 20, 30, 60, and 91 min). The preferred model was chosen according to the Akaike information criterion and the standard errors (%) of the estimated parameters. For the 91-min scan duration, the influx constant K1 increased by 40.7% and the volume of distribution (VT) by 30.4% after P-gp inhibition, while the efflux constant k2 did not change significantly. Similar changes were found for all evaluated scan durations. K1 did not depend on scan duration (10 min—K1 = 0.2191 vs 91 min—K1 = 0.2258), while VT and k2 did. A scan duration of 10 min seems sufficient to properly evaluate the P-gp function using K1 obtained with 1-TCM. For the 91-min scan, VT and K1 can be estimated with a 2-TCM, and both parameters can be used to assess P-gp function
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
Rapid, transient methylation of four proteins in aggregative amoebae of Dictyostelium discoideum as a response to stimulation with cyclic AMP
No full textAbstractIn Dictyostelium discoideum, extracellular cAMP induces chemotaxis and cell aggregation. Suspensions of cAMP-sensitive cells are shown to respond to a 10−6M cAMP-pulse with increased methylation of 4 proteins with app. Mr 110000, 46000, 28000 and 16000. The Mr 110000 and 28000 proteins show a triphasic response with maxima 15, 60 and 150–180s after stimulation. The responses of the Mr 46000 and 16000 proteins are monophasic, maxima being reached 3 and 15s after stimulation, respectively. Optimal responses of methylation are observed over 10−7−10−6M cAMP. The methylation reaction may be involved in the processing of the chemotactic signal
Cyclic AMP, folic acid and pterin-mediated protein carboxymethylation in cellular slime molds
No full textAbstractIn aggregative cells of Dictyostelium discoideum, extracellular cAMP induces transient methylation of a Mr 46 000 protein. Starvation induces a 10–100-fold increase in the number of cAMP-receptors, but no change in the amount of the methyl accepting protein. In vegetative amoebae, a temporal increase of methylation of the protein is induced by stimulation with folic acid. Aggregative amoebae of Dictyostelium lacteum also contain a Mr 46 000 protein, which is methylated after addition of the attractant monapterin. Therefore, protein carboxymethylation seems to be a general phenomenon during chemotaxis of the cellular slime molds
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
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