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Compte rendu de: Alain Rodrigue 2011. La Seguia el Hamra. Contribution à l'étude de la Préhistoire du Sahara Occidental. Paris : L'Harmattan, 119 p.
No full textInternational audienceCompte rendu de: Alain Rodrigue 2011. La Seguia el Hamra. Contribution à l'étude de la Préhistoire du Sahara Occidental. Paris : L'Harmattan, 119 p
Compte rendu de: Alain Rodrigue 2011. La Seguia el Hamra. Contribution à l'étude de la Préhistoire du Sahara Occidental. Paris : L'Harmattan, 119 p.
No full textInternational audienceCompte rendu de: Alain Rodrigue 2011. La Seguia el Hamra. Contribution à l'étude de la Préhistoire du Sahara Occidental. Paris : L'Harmattan, 119 p
Identification and pre-clinical characterization of medicinal plants used to prevent and cure malaria in pregnant women in Cameroon.
Get PDFIn the midst of transient victories by way of insecticides against mosquitoes
or drugs against the parasitic disease, the most serious form of malaria,
caused by Plasmodium falciparum, continues to be a major public health
problem. Malaria in pregnancy compromises the health of both the mother
and child and can be fatal for both. Particularly, malaria during pregnancy
constitutes the major cause of low birth-weight and stillbirth in endemics
countries. In Cameroon malaria is one of the major public health problems.
The absence of an effective vaccine makes the parasitic disease very difficult
to be eliminated and impossible to be eradicated. Treatment and prevention
of malaria during pregnancy is currently a challenge for maternal health
responsibles, due to the emergence of multi-drug resistant malaria parasites
(e.g. to sulfadoxine-pyrimethamine used for IPT). However, there is, yet,
very little and conflicting evidence on the safety of artemisinin-based
combination treatments (ACTs) in particular during first term pregnancy.
Traditional medicines have been employed to treat malaria for thousands of
years. With the problems of increasing levels of drug resistance and
difficulties in poor areas of effective antimalarial drugs being affordable and
accessible, traditional medicines remains an important, sustainable source of
treatment. Moreover, the development of evidence based safe and effective
standardized herbal formulations for pregnant women with curative and
transmission-blocking properties would be a major breakthrough to decrease
malaria burden in women and their newborns.
This Ph.D thesis aimed to a) identify medicinal plants used to prevent and
cure malaria during pregnancy in Menoua West Cameroon; b) assess the
activity of extracts from identified plants in-vitro against Plasmodium
falciparum asexual blood-stages and gametocytes and against sporogonic
stages of Plasmodium berghei in-vitro and in-vivo; c) estimate their
cytotoxicity in vitro and d) design an evidenced based (safe and effective)
plant combination (herbal remedy) with multistage effects on Plasmodium,
suitable for women in pregnancy.
Results show that 19 antimalarial plants are known to be employed in the
study area to manage malaria during pregnancy and of these 11 were cited as
commonly used. Of the latter 10 plants were possible to be collected (11 plant
part materials) and 22 extracts were prepared (water and methanol). Seven,
namely methanol and water extracts of D. edulis stem bark, methanol and
water extracts of E. globulus leaves, P. americana stem bark and V. africana
leaves methanol extracts, and methanol extract of C. citratus leaves were
found to reduce by 50% in vitro asexual blood stage development at
concentrations < 20μg/ml, on both P. falciparum parasite strains used.
These results are in line with the one found in the literature. The stem bark
methanol extract of P. americana was able to reduce the viability of mature
gametocytes by 94% at the primary screening concentration of 100μg/ml. Its
IC50 value was estimated to be 34.7 μg/ml. Comparing the anti-plasmodial
activity of methanol and aqueous extracts of the tested plants, consistently
higher activity was found in the former. Similarly, the methanol plant
extracts were more active in vitro on the development of the sexual stages
(early sporogonic development) that evolve in the mosquito vector. Two
extracts, namely the stem bark methanol extract of P. americana and D.
edulis, exhibited promising inhibitory effects against the insect transmissible
stages of the parasite showing IC50 values in the range of 6 to 13 μg/mL in
vitro and in vivo a reduction of oocyst numbers by more than 70%, after
feeding on gametocytemic mice treated with 150 mg/kg. The results on
transmission-blocking are promising since they are similar to the one obtain
with the standardized herbal NeemAzal. Moreover, none of the 22 plant
extract was found to have cytotoxic effects on normal human cell lines (NHF-
A12-human dermal fibroblast and EA.hy926-endothelial). Interestingly,
almost all the 22 extracts displayed some anti-tumor effects, reducing cell
viability of melanoma and/or human breast cancer cells. Furthermore, the
methanol stem bark extract of P. americana and D. edulis were found to
possess some mosquitocidal potential when tested on the Sf9 insect cell line,
but not as evident as NeemAzal® a azadirachtin A rich product used as
reference.
The findings of this doctoral research put in evidence antiplasmodial activity
in about one-half of the tested medicinal plants against one or different life
cycle stages of the parasite. Thus, based on this parasitological evidence,
herbal remedies can be suggested to be used as a tool for the management of
malaria in pregnant women. Further ethnobotanical studies including more
villages and larger variety of respondents in the community will allow to
identify additional medicinal plants uses, since our study was limited to a
limited number of easy accessible villages. Moreover, our findings allow the
design of rational combination formulations with antiplasmodial multi-stage
activity. Preclinical studies will allow to assess efficacy and safety of such
plant combinations, validating the concept of curative and preventive
transmission-blocking herbal remedies
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
Angeloylated Germacranolides from Daucus virgatus and Their Plasmodium Transmission Blocking Activity
No full textPhytochemical investigation of the aerial parts of the Tunisian plant Daucus virgatus led to the isolation of eight new germacranolides named daucovirgolides A-H (1-8). The stereostructures of these sesquiterpene lactones, decorated by either one or two angeloyl groups, have been determined by a combination of MS, NMR spectroscopy, chemical derivatization, and comparison of experimental electronic circular dichroism curves with TDDFT-predicted data. Daucovirgolide G (7) proved to be the single member of this family to possess a marked inhibitory activity (92% at 50 μg/mL) on the development of Plasmodium early sporogonic stages, the nonpathogenic transmissible stages of malaria parasites, devoid of general cytotoxicity. The selective activity of daucovirgolide G points to the existence of strict structural requirements for this transmission-blocking activity and therefore of a well-defined, although yet unidentified, biological target
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