1,720,964 research outputs found
Quantitative PCR for human herpesviruses 6 and 7
No full textA quantitative PCR assay for the detection of human herpesvirus 6 (HHV-6) (variants A and B) and HHV-7 DNAs in clinical samples was developed. The assay uses a nonhomologous internal standard (IS) for each virus that is coamplified with the wild-type target sequence in the same vial and with the same pair of primers. This method allows for a correction of the variability of efficiency of the PCR technique. A standard curve is constructed for each experiment by coamplification of known quantities of the cloned HHV-6 or HHV-7 target templates with the respective IS. Absolute quantitation of the test samples is then achieved by determining the viral target/IS ratio of the hybridization signals of the amplification products and plotting this value against the standard curve. Using this assay, we quantitated the amount of HHV-6 or HHV-7 DNA in infected cell cultures and demonstrated an inhibitory effect of phosphonoformic acid on the replication of HHV-6 and HHV-7 in vitro. As the first clinical application of this procedure, we performed preliminary measurements of the loads of HHV-6 and HHV-7 in lymph nodes from patients with Hodgkin's disease and AIDS. Application of this quantitative PCR method should be helpful for elucidating the pathogenic roles of HHV-6 and HHV-7
Infection of gamma/delta T lymphocytes by human herpesvirus 6: transcriptional induction of CD4 and susceptibility to HIV infection.
No full textInterference between human herpesvirus 7 and HIV-1 in mononuclear phagocytes
No full textHuman herpesvirus 7 (HHV-7) uses CD4 as a cellular membrane receptor and thereby interferes with infection of CD4+ T cells by HIV-1. We studied the interactions between HHV-7 and a macrophage-tropic HIV-1 isolate (HIV-1BaL) in terminally differentiated human peripheral blood monocyte-derived macrophages, another critical target for infection by HIV-1 in vivo. Exposure of macrophages to HHV-7 alone yielded no signs of virus replication or cytopathic effects. Nevertheless, when macrophages were pre-exposed to either live or UV-inactivated HHV-7 and subsequently infected with HIV-1BaL, a significant dose-dependent inhibition of HIV-1 replication was documented. At day 7 postinfection, the average level of HIV-1 p24 Ag in cultures from five different donors was reduced by 91.7 +/- 8.3% by pretreatment with live HHV-7 and by 91.8 +/- 8.2% by pretreatment with UV-inactivated HHV-7. Moreover, the synthesis of HIV-1 proviral DNA in macrophages pretreated with HHV-7 was completely inhibited during the early stages after infection, suggesting that HHV-7 blocks HIV-1 at the level of interaction with the CD4 receptor. Consistent with this concept, both macrophage and CD4+ T cell cultures with pre-established HIV-1 infection were not susceptible to inhibitory effects of HHV-7. The proliferative response of PBMC to mitogens was only marginally inhibited by exposure to HHV-7 before mitogen stimulation, indicating that the inhibition of HIV-1 infection was not due to a negative effect on cell proliferation. These data demonstrate that HHV-7 is a powerful inhibitor of HIV-1 infection in cells of the mononuclear phagocytic lineage, despite its inability to replicate actively in such cells
CD4 is a critical component of the receptor for human herpesvirus 7: interference with human immunodeficiency virus.
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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
Human herpesvirus 6A accelerates AIDS progression in macaques
No full textAlthough HIV is the necessary and sufficient causative agent of AIDS, genetic and environmental factors markedly influence the pace of disease progression. Clinical and experimental evidence suggests that human herpesvirus 6A (HHV-6A), a cytopathic T-lymphotropic DNA virus, fosters the progression to AIDS in synergy with HIV-1. In this study, we investigated the effect of coinfection with HHV-6A on the progression of simian immunodeficiency virus (SIV) disease in pig-tailed macaques (Macalcal nemestrina). Inoculation of HHV-6A resulted in a rapid appearance of plasma viremia associated with transient clinical manifestations and followed by antibody seroconversion, indicating that this primate species is susceptible to HHV-6A infection. Whereas animals infected with HHV-6A alone did not show any long-term clinical and immunological sequelae, a progressive loss of CD4(+) T cells was observed in all of the macaques inoculated with SIV. However, progression to full-blown AIDS was dramatically accelerated by coinfection with HHV-6A. Rapid disease development in dually infected animals was heralded by an early depletion of both CD4(+) and CD8(+) T cells. These results provide in vivo evidence that HHV-6A may act as a promoting factor in AIDS progression
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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