1,721,240 research outputs found
Plasmodium vivax: polymerase chain reaction amplification artifacts limit the suitability of pvgam1 as a genetic marker.
No full textImwong, M., Pukrittakayamee, S., Looareesuwan, S., Poirriez, J., Pasvol, G., White, N. J., and Snounou, G. 2001. Plasmodium vivax: Polymerase chain reaction amplification artifacts limit the suitability of pvgam1 as a genetic marker. Experimental Parasitology 99, 175-179. © 2001 Elsevier Science (USA)
Knowlesi malaria in Vietnam
Full text linkThe simian malaria parasite Plasmodium knowlesi is transmitted in the forests of Southeast Asia. Symptomatic zoonotic knowlesi malaria in humans is widespread in the region and is associated with a history of spending time in the jungle. However, there are many settings where knowlesi transmission to humans would be expected but is not found. A recent report on the Ra-glai population of southern central Vietnam is taken as an example to help explain why this may be so
Quantifying low birth weight, preterm birth and small-for-gestational-age effects of malaria in pregnancy: a population cohort study
Full text linkBACKGROUND: The association between malaria during pregnancy and low birth weight (LBW) is well described. This manuscript aims to quantify the relative contribution of malaria to small-for-gestational-age (SGA) infants and preterm birth (PTB) in pregnancies accurately dated by ultrasound on the Thai-Myanmar border at the Shoklo Malaria Research Unit. METHODS AND FINDINGS: From 2001 to 2010 in a population cohort of prospectively followed pregnancies, we analyzed all singleton newborns who were live born, normal, weighed in the first hour of life and with a gestational age (GA) between 28+0 and 41+6 weeks. Fractional polynomial regression was used to determine the mean birthweight and standard deviation as functions of GA. Risk differences and factors of LBW and SGA were studied across the range of GA for malaria and non-malaria pregnancies. From 10,264 newborns records, population centiles were created. Women were screened for malaria by microscopy a median of 22 [range 1-38] times and it was detected and treated in 12.6% (1,292) of pregnancies. Malaria was associated with LBW, PTB, and SGA compared to those without malaria. Nearly two-thirds of PTB were classified as LBW (68% (539/789)), most of which 83% (447/539) were not SGA. After GA 39 weeks, 5% (298/5,966) of non-LBW births were identified as SGA. Low body mass index, primigravida, hypertension, smoking and female sex of the newborn were also significantly and independently associated with LBW and SGA consistent with previous publications. CONCLUSIONS: Treated malaria in pregnancy was associated with an increased risk for LBW, PTB, and SGA, of which the latter are most important for infant survival. Using LBW as an endpoint without adjusting for GA incorrectly estimated the effects of malaria in pregnancy. Ultrasound should be used for dating pregnancies and birth weights should be expressed as a function (or adjusted for GA) of GA in future malaria in pregnancy studies
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
Using an improved phagocytosis assay to evaluate the effect of HIV on specific antibodies to pregnancy-associated malaria
Full text linkBackground: Pregnant women residing in malaria endemic areas are highly susceptible to Plasmodium falciparum malaria, particularly during their first pregnancy, resulting in low birth weight babies and maternal anaemia. This susceptibility is associated with placental sequestration of parasitised red blood cells expressing pregnancy-specific variant surface antigens. Acquisition of antibodies against these variant surface antigens may protect women and their offspring. Functions of such antibodies may include prevention of placental sequestration or opsonisation of parasitised cells for phagocytic clearance. Methodology/Findings: Here we report the development and optimisation of a new high-throughput flow cytometry-based phagocytosis assay using undifferentiated Thp-1 cells to quantitate the amount of opsonizing antibody in patient sera, and apply this assay to measure the impact of HIV on the levels of antibodies to a pregnancy malaria-associated parasite line in a cohort of Malawian primigravid women. The assay showed high reproducibility, with inter-experimental correlation of r2 = 0.99. In primigravid women, concurrent malaria infection was associated with significantly increased antibodies, whereas HIV decreased the ability to acquire opsonising antibodies (Mann-Whitney ranksum: p = 0.013). This decrease was correlated with HIV-induced immunosuppression, with women with less than 350×106 CD4+ T- cells/L having less opsonising antibodies (coef: −11.95,P = 0.002). Levels of antibodies were not associated with protection from low birth weight or anaemia. Conclusions/Significance: This flow cytometry-based phagocytosis assay proved to be efficient and accurate for the measurement of Fc-receptor mediated phagocytosis-inducing antibodies in large cohorts. HIV was found to affect mainly the acquisition of antibodies to pregnancy-specific malaria in primigravidae. Further studies of the relationship between opsonising antibodies to malaria in pregnancy and HIV are indicated.Ricardo Ataíde, Wina Hasang, Danny W. Wilson, James G. Beeson, Victor Mwapasa, Malcolm E. Molyneux, Steven R. Meshnick, Stephen J. Rogerso
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
Molecular methods for accurate diagnosis and epidemiological picture of imported malaria.
No full textObjectives: Malaria is the most frequent imported infection in Italy,
related to the increasing number of travellers and migratory flows from
endemic countries.
Microscopic examination has poor sensitivity and may give problems
in the differentiation of Plasmodium falciparum (Pf), P. malariae (Pm),
P. ovale (Po), and P. vivax (Pv), especially in cases of low parasitaemia or
mixed infections: to circumvent these limitations molecular assays based
on 18S-rDNA were developed by several research groups, including us.
Our study aimed to accurately and promptly diagnose cases of malaria
and to describe their occurrence in our area comparing the results of
microscopy and molecular assays, in order to assess the usefulness of
these assays in the diagnostic practice.
Methods: Blood samples from 701 patients presenting to the University
Hospital of Parma from 2000 to 2007 with clinical suspicion of
malaria were subjected to microscopic examination and to 6 different
PCR protocols targeting plasmodial 18S-rDNA alternatively used during
2000−07, including nested- and Real-time PCR assays.
Results: By microscopy 153 cases of malaria were diagnosed [129 Pf
(84.3%), 7 Po (4.6%), 10 Pv (6.5%), 5 P. spp. (3.3%), 1 Pf/P. spp.
(0.65%), 1 mixed infection (0.65%)], whilst 159 were diagnosed by PCRs
[129 Pf (81.1%), 14 Po (8.8%), 6 Pv (3.8%), 3 Pm (1.9%), 7 mixed
infections (4.4%)].
Conclusion: Despite microscopy remains the reference diagnostic
method (rapid and inexpensive), in some cases molecular assays are
the only ones allowing a correct diagnosis of malaria, particularly to
detect infections by species other than Pf and mixed infections.
However, in our study only one PCR assay developed by us showed the
higher accuracy in Po detection due to specific primer design done to
recognise all the variants in Po 18S-rRNA gene.
PCR proved to be more sensitive and specific than microscopy and
changed the picture of malaria epidemiology in our area detecting 5
single and 1 mixed infections missed by microscopy, revealing 5 single
and 2 mixed infections incorrectly diagnosed by microscopy and giving
speciation in 6 cases in which microscopy had limited the result to genus
identification.
The most prevalent malaria cases in our area as well as in Italy were
imported from Africa and due to Pf, followed by Po and Pv.
In our experience a rapid and accurate diagnosis of malaria allowed to
administer a prompt and targeted therapy with positive impact on the
clinical management of the patients
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
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