1,721,052 research outputs found
First clinical evidence that trimethylsulfonium can serve as a biomarker for the production of the signaling molecule hydrogen sulfide
Full text linkBackground: Hydrogen sulfide (H2S) is established as the third gaseous signaling molecule and is known to be overproduced in down syndrome (DS) due to the extra copy of the CBS gene on chromosome 21, which has been suggested to contribute to the clinical manifestation of this condition. We recently discovered trimethylsulfonium (TMS) in human urine and highlighted its potential as a selective methylation metabolite of endogenously produced H2S, but the clinical utility of this novel metabolite has not been previously investigated. We hypothesize that the elevation of H2S production in DS would be reflected by an elevation in the methylation product TMS.
Methods: To test this hypothesis, a case-control study was performed and the urinary levels of TMS were found to be higher in the DS group (geo. mean 4.5 nM, 95 % CI 2.4-3.9) than in the control (N) group (3.1 nM, 3.5-6.0), p-value 0.01, whereas the commonly used biomarker of hydrogen sulfide, thiosulfate, failed to reflect this alteration in H2S production (15 μM (N) vs. 13 μM (DS), p-value 0.24.
Results: The observed association is in line with the proposed hypothesis and provides first clinical evidence of the utility of TMS as a novel and more sensitive biomarker for the endogenous production of the third gaseous signaling molecule than the conventionally used biomarker thiosulfate, which is heavily dependent on bacterial hydrogen sulfide production.
Conclusion: This work shows that TMS must be explored in clinical conditions where altered metabolism of hydrogen sulfide is implicated.
Keywords: Down syndrome (DS); Hydrogen sulfide; Thiosulfate; Third gaseous signaling molecule; Trimethylsulfonium
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
Utjecaj termičke obrade na specijaciju arsena u jestivim gljivama - analiza HPLC-ICP-MS metodom
No full textThe purpose of this research was the investigation of the total arsenic concentration in Sarcosphaera Coronaria and Chantarelle mushrooms and the arsenic speciation analysis of their extracts with HPLC-ICPMS. Additionally, I was studying the influence of typical cooking processes such as frying and boiling in water on the arsenic speciation in these two mushrooms, because this is the normal way of consumption. The influence of vinegar on the arsenic speciation was also studied in Sarcosphaera Coronaria mushrooms because in 1920 people in Switzerland died after consumption of these mushrooms prepared with vinegar. Also, the purpose was learning the use of high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICPMS), process of preparing samples and performing quality control during scientific research. The results are shown that boiling with vinegar (10 %) does not significantly increase the formation of the toxic As species MA(III) but keeps it steady as opposed to boiling in pure water, causing MA(III) to disappear completely from the mushroom. Probably, MA(III) goes into some other form of arsenic, which is interesting for some future research. Additionally, we investigated the behaviour of other elements during the cooking process in the common edible mushrooms Chantarelle and we confirmed the lose of minerals (Na, Ca, Mg, and Zn), other essential trace elements (Se and Fe) and also toxic elements (As, Pb, and Sr) during typical cooking process. The separation of analytes was performed by high performance liquid chromatography and separated analytes were detected by inductively coupled plasma mass spectrometry. The results of the research have shown that HPLC - ICPMS method is acceptable and satisfactory for this kind of research. The formation of a new compound during frying needs some further investigations, also it can be interesting to examine the behaviour of arsenic, arsenic species and other element during the thermic process of other edible mushrooms.Cilj ovoga istraživanja bio je odrediti koncentraciju ukupnog arsena u gljivama Sarcosphaera coronaria i Chantarelle te specijaciju arsena iz njihovog ekstrakta HPLC-ICPMS metodom. Također, važan dio ovog rada bio je istražiti utjecaj termičke obrade – tipičnih procesa poput prženja ili kuhanja – na arsen i specijacije arsena, posebice u jestivim gljivama, Chantarellama. Nadalje, cilj je bio ispitati utjecaj vinskog octa na specijacije arsena u gljivama Sarcosphaera coronaria, zbog smrtnog slučaja koji se dogodio u Švicarskoj, 1920. godine, nakon što je ih grupa ljudi konzumirala u pripremi s octom. Točan uzrok njihove smrti do danas nije poznat. Osobna svrha istraživanja bila je učiti o tekućinskoj kromatografiji visoke djelotvornosti (HPLC) povezanoj s induktivno spregnutom plazmom – spektormetrijom masa (ICPMS), postupcima pripreme uzoraka te pravilnom provođenju kontrole kvalitete tijekom znanstvenog istraživanja. Rezultati ovog istraživanja pokazali su da kuhanjem gljiva uz 10 % octa ne uzrokuje formaciju toksične vrste arsena MA(III), ali on ostaje prisutan u gljivi Sarcosphaera Coronaria i nakon kuhanja. Nasuprot tome, kuhanjem u vodi bez octa, uočeno je da toksična vrsta MA(III) potpuno nestaje iz gljive. Ispitivanjem vode nakon kuhanja potvrđeno je da ne dolazi do ekstrakcije MA(III) iz gljive u vodu pa zaključujemo da MA(III) kuhanjem iz gljive prelazi u neki drugi oblik arsena što ostavlja prostor za daljnja istraživanja. Nadalje, praćena je promjena koncentracija ostalih važnih elemenata u gljivama Chantarelle prije i nakon termičke obrade. Potvrđeno je da termičkom obradom dolazi do gubitka minerala (Na, Ca, Mg i Zn), elementa u tragovima (Se i Fe) i toksičnih elemenata (As, Pb i Sr) tijekom tipičnih procesa obrade. Za separaciju analita korištena je tekućinska kromatografija visoke djelotvornosti a za njihovu detekciju induktivno spregnuta plazma – spektormetrija masa. Rezultati su pokazali da je metoda HPLC-ICPMS prihvatljiva i zadovoljavajuća za ovakvu vrstu istraživanja. Analizom rezultata uočeno je nastajanje novih komponenata tijekom procesa prženja što treba dodatno istražiti u budućim istraživanjima
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
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