1,720,970 research outputs found
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
Recombinant CXCR4/CCR5 hybrid receptors as tools for studies of HIV-1 receptor usage
Get PDFThe chemokine receptors CCR5 and CXCR4 are required, together with CD4, for the entry of HIV-1 into target cells. CCR5 using HIV-1 dominates during transmission and the asymptomatic phase of infection. During progression, virus phenotypes with the ability to use CXCR4 emerge in about 50% of infected individuals. Individuals continuously harbouring CCR5-restricted isolates still progress to AIDS. Differences among CCR5 using isolates, has been found and an evolution towards an altered mode of CCR5 coreceptor use and a reduced sensitivity to inhibition by natural CCR5 ligands has also been described. With the aim to study interactions of natural ligands and HIV-1 isolates with these chemokine receptors, a set of hybrid CXCR4/CCR5 receptors were constructed. Signalling response to their respective natural ligands, SDF-1 and RANTES were studied and prototypic R5 and X4 isolates (HIV-1BaL and HIV-1IIIB) were tested for their ability to use these chimeric receptors. The results showed that ligands and virus use different receptor epitopes which, in turn, vary between the two receptors. Further, the evolution of primary HIV-1 isolates was studied. A total of 246 sequential primary HIV-1 isolates were studied. Using our chimeric CXCR4/CCR5 receptors, we showed that R5 isolates from immunosuppressed individuals are distinct from those isolated from individuals with higher CD4+ T-cell counts, with regards to coreceptor usage. The analysis also showed that the ability to utilize chimeric receptors correlated inversely with the sensitivity to RANTES inhibition of infection. The R5 isolates used receptor chimeras to various degrees. Based on these results, the R5 viruses could be subdivided into two groups: the R5narrow phenotype and the R5broad phenotype. The R5narrow phenotype is defined as viruses that use wt CCR5 but no chimeric receptors, whereas viruses using at least one chimeric receptor in addition to CCR5, are designated R5broad viruses. The mode of coreceptor use by paired plasma and CSF isolates from HIV-1 infected individuals with varying degree of immunodeficiency and neuropathology were studied. The R5 viral phenotypes predominated both in plasma and in CSF. We were able to identify discordant plasma/CSF wt coreceptor use but also, varying R5 viral phenotypes in the paired isolates within individual patients. There were no characteristic patterns of receptor use that could distinguish CSF from plasma isolates. R5 virus use of chimera FC-2 correlated highly with immunosuppression. Efficient chimeric receptor use also correlated, with an increased resistance to inhibition by the CCR5 antagonist TAK-779. In conclusion, our findings propose that alterations in the mode of CCR5 use may be a key event in R5 virus pathogenesis. We believe that R5 virus ability to utilize these CXCR4/CCR5 chimeric receptors reflects a more flexible and more efficient CCR5 usage, which may include a reduced dependency upon interactions with the N-terminal of the receptor for infection. The findings are important, not only with regards to R5-virus pathogenesis and optimization of emerging treatment with CCR5 antagonists, but also for HIV-infection within the CNS
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
Recombinant CXCR4/CCR5 hybrid receptors as tools for studies of HIV-1 receptor usage [Elektronisk resurs]
No full textPopular Abstract in Swedish Människan är uppbyggd av ett stort antal celler. För att kroppens olika organ ska kunna samverka och för att kroppen ska kunna fungera som en helhet, måste de olika cellerna kommunicera med varandra. Cellernas kommunikationssystem är uppbyggt av mottagare, s.k. receptorer, på de olika cellernas yta och signaler som skickas runt mellan cellerna. Receptorerna och signalerna fungerar som nyckel och lås, d.v.s. när rätt signal når rätt receptor så får just den cellen information från andra celler och omgivningen. På det sättet når en viss information bara de celler som behöver just den upplysningen. Olika delar av kroppen dirigeras för att fungera på ett visst sätt, vid ett tillfälle. Signalerna kan exempelvis bestå av luktsignaler, hormoner, ljus som lyser in i ögat eller ämnen som påverkar kroppens immunsystem. De flesta receptorer tillhör en familj som heter GPCR. Man har uppskattat att det finns ungefär 800 olika GPCR-receptorer i vår kropp varav ungefär hälften bearbetar luktsignaler som kommer in via näsan. Ett flertal andra signaler och receptorer gör att vårt immunförsvar samarbetar. Immunförsvaret får signaler om främmande ämnen som kommit in i kroppen, eller från en skada som skett i något av kroppens organ. Med hjälp av olika signaler kan sedan immunsystemet agera för att ta bort ämnet eller för att reparera skadan i kroppen. År 1981 började man lägga märke till att ett flertal människor i världen drabbades av en ny okänd sjukdom som bröt ner immunförsvaret. Dessa tidigare friska människors immunsystem fungerade inte längre och de blev sjuka och dog av olika infektionssjukdomar och cancersjukdomar. År 1983 fann man att viruset HIV (Human immunodeficiency virus) orsakade denna nya sjukdom, AIDS (Acquired immunodeficiency syndrome). Sedan dess har många människor i världen blivit infekterade och avlidit i AIDS. Detta arbete handlar om två GPCR-receptorer, CCR5 och CXCR4, som normalt fungerar i kroppens immunförsvar. 1996 visade det sig att dessa två receptorer utnyttjas av HIV när det tar sig in och infekterar olika celler i kroppen. Utan dessa receptorer på cellytan kan cellerna inte infekteras. Denna nya kunskap ledde till att intresset för hur HIV använder sig av och kommer in i cellerna via dessa receptorer, blev mycket stort. När en person blir infekterad använder HIV nästan alltid den ena receptorn CCR5. Hos personer som är svårt sjuka i AIDS har man kunnat visa att de virus som de har i kroppen då, ofta använder den andra receptorn, CXCR4. Det verkar alltså som att HIV förändras under den tid det tar från att man smittats, tills man är svårt sjuk i AIDS, något som ofta tar många år. I det här arbetet har vi tagit reda på mer om hur det går till när HIV tar sig in i cellerna genom att använda dessa receptorer. För att kunna göra detta tillverkade jag blandreceptorer (hybrider), som består av delar från både CCR5 och den andra receptorn CXCR4. I ett första arbete visade vi att HIV använder receptorerna på andra sätt än immunförsvarets naturliga signalämnen. Resultatet visade att man kan utveckla HIV-läkemedel som blockerar användandet av dessa receptorer utan att störa de naturliga signalerna som överförs via receptorerna. Genom samarbeten med Lunds universitetssjukhus och Sahlgrenska universitets-sjukhuset i Göteborg har vi kunnat ta fram HIV från ett flertal patienter. HIV från smittade, fortfarande relativt friska personer, samt från patienter som är svårt sjuka i AIDS, har isolerats. Med hjälp av de konstgjorda hybridreceptorerna har vi sedan kunnat visa att dessa olika HIV-isolat använder receptorerna på olika sätt för att ta sig in i cellerna. Det sker alltså en utveckling av viruset under sjukdomsprocessen. Viruset förändrar sitt sätt att använda receptorn, CCR5, när personen blir sjukare och det blir också svårare att blockera infektionen med vissa typer av HIV-läkemedel. Vi har dessutom isolerat HIV från hjärnan för att jämföra med HIV som finns i kroppens blodbanor utanför hjärnan. Även här har vi kunnat se skillnader i hur viruset använder CCR5 och att viruset i hjärnan ibland skiljer sig från viruset i blodbanan, hos en och samma person. Detta ökar förståelsen för den speciella AIDS-demens som patienter kan drabbas av. Även i denna studie hittade vi virus med olika känslighet för blockering med läkemedel. Hybridreceptorerna som har använts i de tre studier som avhandlingen bygger på, har visat sig vara mycket bra verktyg för att förstå infektionen och sjukdomsprocessen. Genom att lära sig mer om hur HIV fungerar och tar sig in i den infekterade personens olika celler i kroppen, kan man öka kunskapen om sjukdomen, optimera behandlingen, samt lättare utveckla nya läkemedel mot HIV och sjukdomen AIDS.The chemokine receptors CCR5 and CXCR4 are required, together with CD4, for the entry of HIV-1 into target cells. CCR5 using HIV-1 dominates during transmission and the asymptomatic phase of infection. During progression, virus phenotypes with the ability to use CXCR4 emerge in about 50% of infected individuals. Individuals continuously harbouring CCR5-restricted isolates still progress to AIDS. Differences among CCR5 using isolates, has been found and an evolution towards an altered mode of CCR5 coreceptor use and a reduced sensitivity to inhibition by natural CCR5 ligands has also been described. With the aim to study interactions of natural ligands and HIV-1 isolates with these chemokine receptors, a set of hybrid CXCR4/CCR5 receptors were constructed. Signalling response to their respective natural ligands, SDF-1 and RANTES were studied and prototypic R5 and X4 isolates (HIV-1BaL and HIV-1IIIB) were tested for their ability to use these chimeric receptors. The results showed that ligands and virus use different receptor epitopes which, in turn, vary between the two receptors. Further, the evolution of primary HIV-1 isolates was studied. A total of 246 sequential primary HIV-1 isolates were studied. Using our chimeric CXCR4/CCR5 receptors, we showed that R5 isolates from immunosuppressed individuals are distinct from those isolated from individuals with higher CD4+ T-cell counts, with regards to coreceptor usage. The analysis also showed that the ability to utilize chimeric receptors correlated inversely with the sensitivity to RANTES inhibition of infection. The R5 isolates used receptor chimeras to various degrees. Based on these results, the R5 viruses could be subdivided into two groups: the R5narrow phenotype and the R5broad phenotype. The R5narrow phenotype is defined as viruses that use wt CCR5 but no chimeric receptors, whereas viruses using at least one chimeric receptor in addition to CCR5, are designated R5broad viruses. The mode of coreceptor use by paired plasma and CSF isolates from HIV-1 infected individuals with varying degree of immunodeficiency and neuropathology were studied. The R5 viral phenotypes predominated both in plasma and in CSF. We were able to identify discordant plasma/CSF wt coreceptor use but also, varying R5 viral phenotypes in the paired isolates within individual patients. There were no characteristic patterns of receptor use that could distinguish CSF from plasma isolates. R5 virus use of chimera FC-2 correlated highly with immunosuppression. Efficient chimeric receptor use also correlated, with an increased resistance to inhibition by the CCR5 antagonist TAK-779. In conclusion, our findings propose that alterations in the mode of CCR5 use may be a key event in R5 virus pathogenesis. We believe that R5 virus ability to utilize these CXCR4/CCR5 chimeric receptors reflects a more flexible and more efficient CCR5 usage, which may include a reduced dependency upon interactions with the N-terminal of the receptor for infection. The findings are important, not only with regards to R5-virus pathogenesis and optimization of emerging treatment with CCR5 antagonists, but also for HIV-infection within the CNS
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
