1,720,968 research outputs found
Development of molecular assays on Plasmodium falciparum gametocytes for functional analysis and novel diagnostics on malaria parasite transmission
Get PDFTransmission of P. falciparum malaria parasite from human host to mosquito is mediated by gametocytes in human peripheral blood. Both male and female gametocytes are required for the development of the parasite inside a female Anopheles mosquito. This work aims first to develop a molecular method for detecting gametocyte sex ratios as a parameter to predict parasite infectiousness to mosquito and then to investigate the effects of antimalarial compounds on gametocytes from natural infections. The results were compared with Direct Membrane Feeding Assay (DMFA) on mosquito data.
Two multiplex RTqPCR assays, targeting sex-specific transcripts (pfCCp4 and pfs25 for females, pfMGET for males), were developed for simultaneous assessment of male and female gametocytes. These assays were applied to three laboratory lines to measure their sex ratio by using two analytical approaches: the DCt and the TSEX RATIO. The results were compared with morphological sex ratios obtained by immunofluorescence assays (IFA). A linear relation exists between molecular parameters obtained in RTqPCT and the sex ratios determined by IFA analysis only in the lines NF54 and HB3 sel 4 lines but not in the case of the transgenic line pfDynGFP/P47mCherry. TSEX RATIO parameter represents a novel approach to track the copy number of sex-specific transcripts in a gametocyte population offering indirect insights into how the proportion of male and female gametocytes evolves over time and under various experimental conditions.
The above RTqPCR assays were used on gametocytes from infected individuals treated with gametocytocidal compounds to evaluate their effect on sex specific transcripts. The data of these assays were analyzed with ΔΔCt method. Molecular analysis performed after 24 hours of treatment did not align with DMFA outcomes. However, compound effects on transcript abundance became evident after an extended cultivation period of 48 hours following the 24 hours of treatment in NF54 gametocyte
Aedes albopictus 34k2. Salivary protein as epidemiological tool for the assesment of human exposure to the tiger mosquito
Get PDFArthropod-borne viruses (arboviruses) such as dengue, chikungunya and Zika have nowadays a large impact on the human population worldwide. Their public health relevance significantly increased in recent decades, both due to their re-emergence in tropical areas and to their appearance in more temperate regions. These arboviruses are transmitted between humans by the bite of infected Aedes mosquitoes, mainly Aedes aegypti and Aedes albopictus. Their rapid worldwide spreading, especially of the tiger mosquito Ae. albopictus, is expanding the risk of arboviral transmission also to temperate areas and emphasize the need for improved monitoring and control. Evaluating human- vector contact is essential to assess the risk of transmission of Aedes mosquito-borne diseases and to guide planning and implementation of vector control. This is currently achieved by classical entomological measurements (ovitraps, larval/pupal indices, adult traps, human landing catches), although they provide only an indirect evaluation and have their drawbacks and limitations. However, transcriptome studies on blood feeding insects salivary glands highlighted the existence of mosquito genus-specific salivary proteins, which may be ideal candidates for the development of novel tools to evaluate human exposure to vector bites. In fact, while feeding on their hosts, blood sucking arthropods inject a cocktail of salivary proteins with anti-hemostatic and anti-inflammatory activities. These salivary proteins whose also evokes in humans specific antibody responses, whose measurement can provide a direct evaluation of host exposure to disease vectors.
The culicine-specific 34k2 salivary protein from Ae. albopictus (al34k2) and its ortholog from Ae. aegypti (ae34k2) were here evaluated as novel specific biomarkers of human exposure to Aedes mosquitoes. Evidence of al34k2 and ae34k2 immunogenicity was first obtained in a murine model, and preliminary indications of immunogenicity to humans acquired through the use of a single human serum hyperimmune to Ae. albopictus saliva. The al34k2 antigen was then validated measuring by ELISA the anti-al34k2 IgG responses in sera collected from healthy individuals naturally exposed to the tiger mosquito in two areas of Northeast Italy (Padova and Belluno), during two different time periods (at the end of the low- and shortly after the high-density mosquito seasons). IgG responses to al34k2 appeared suitable to evaluate spatial and temporal variation of human exposure to Ae. albopictus. Analysis of IgG1 and IgG4 subclasses suggested that the al34k2 protein evokes in naturally exposed individuals an IgG1-dominated antibody response that may be indicative of a Th1-type polarization. A tendency of the anti-al34k2 IgG response to decrease with age was also found. This trend was evident in individuals from Padova but only hardly detectable in those from Belluno, possibly because of the different history of colonization of the study areas. Finally, to get further insights into the species-specificity of IgG responses to 34k2 salivary proteins and to validate them in epidemiological settings with ongoing arboviral transmission, the IgG responses to the al34k2 and the ae34k2 salivary antigens were measured in cohorts of individuals from the Réunion Island (only exposed to Ae. albopictus) and from Bolivia (only exposed to Ae. aegypti). Individuals from Réunion Island showed significantly higher IgG responses to al34k2 than to ae34k2 validating this antigen as a good and specific marker in an endemic area where Ae. albopictus is present. On the contrary, ae34k2 IgG responses showed in both areas a low specificity and a relatively high background, perhaps due to cross-reactivity with some unknown antigen.
The results reported in this thesis emphasize the potential use of the IgG antibody responses to the al34k2 salivary protein as a specific biomarker of human exposure to Ae. albopictus. Serological assays as the one described here have the advantage of providing a direct measure of human vector contact and may be useful to assess the efficacy of vector control interventions. Such a complementary tool can also be employed for epidemiological studies and possibly for estimation of transmission risk
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
- …
