Etude de l’activité antifalcémiante d’extraits de racines de Leptadenia hastata Decne. (Asclepiadacae)

L’objectif de cette étude est d’évaluer l’activité antifalcémiante d’extraits de racines de Leptadenia hastata sur des hémoglobines falciformes et d’identifier les principes actifs à l’origine de cette activité. La méthode employée étudie la réversibilité des drépanocytes, en fonction du temps d’incubation des extraits par rapport aux témoins (eau physiologique, phénylalanine et arginine) sur des échantillons de sang de patients drépanocytaires homozygotes. Des concentrations de 0,05; 0,5; 5 et 10 mg/ml de quatre extraits (méthanol, hexane, acétate d’éthyle et méthanol résiduel) ont été mises en contact avec des drépanocytes de type SS après avoir provoqué leur falciformation avec une solution à 2% de métabisulfite de sodium. L’évaluation a été effectuée toutes les 30 minutes pendant 120 minutes. Les différents extraits ont montré une activité dosedépendante sur la réversibilité de la falciformation des globules rouges avec plus de 80% d’inversion en 120 minutes pour l’extrait méthanolique, le plus actif. Un screening phytochimique a permis de faire une corrélation entre les flavonoïdes et l’activité antifalcémiante des extraits de Leptadenia hastata.Mots clés : Drépanocytose, hémoglobine, activité antifalcémiante, Leptadenia hastata, flavonoïdes

Sensitivity of IFN-γ Release Assay to Detect Latent Tuberculosis Infection Is Retained in HIV-Infected Patients but Dependent on HIV/AIDS Progression

BACKGROUND: Detection and treatment of latent TB infection (LTBI) in HIV infected individuals is strongly recommended to decrease morbidity and mortality in countries with high levels of HIV. OBJECTIVE: To assess the validity of a newly developed in-house ELISPOT interferon-gamma release assay (IGRA) for the detection of LTBI amongst HIV infected individuals, in comparison with the Tuberculin Skin Test (TST). METHODOLOGY/PRINCIPAL FINDINGS: ESAT6/CFP10 (EC) ELISPOT assays were performed, together with a TST, in 285 HIV infected individuals recruited in HIV clinics in Dakar, Senegal, who had no signs of active TB at time of enrolment. Thirty eight of the subjects (13.3%) failed to respond to PHA stimulation and were excluded from the analysis. In the 247 remaining patients, response to PHA did not vary according to CD4 cell count categories (p = 0.51). EC ELISPOT was positive in 125 (50.6%) subjects, while 53 (21.5%) had a positive TST. Concordance between EC ELISPOT and TST was observed in 151 patients (61.1%) (kappa = 0.23). The proportion of subjects with a positive response to the EC ELISPOT assay decreased with declining CD4 counts (p trend = 0.001), but were consistently higher than the proportion of TST responders. In multivariate analysis, the risk of being EC-ELISPOT positive in HIV infected individuals was associated with age, CD4 count and HIV-1 strain. CONCLUSION: Our study indicates that IGRAs using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals, but may be impaired by T-cell anergy in severely immuno-suppressed individuals

Computed CD4 percentage as a low-cost method for determining pediatric antiretroviral treatment eligibility

<p>Abstract</p> <p>Background</p> <p>The performance of the WHO recommendations for pediatric antiretroviral treatment (ART) in resource poor settings is insufficiently documented in routine care.</p> <p>Methods</p> <p>We compared clinical and immunological criteria in 366 children aged 0 to 12 years in Kinshasa and evaluated a simple computation to estimate CD4 percent, based on CD4 count, total white blood cell count and percentage lymphocytes. Kappa (κ) statistic was used to evaluate eligibility criteria and linear regression to determine trends of CD4 percent, count and total lymphocyte count (TLC).</p> <p>Results</p> <p>Agreement between clinical and immunological eligibility criteria was poor (κ = 0.26). One third of children clinically eligible for ART were ineligible using immunological criteria; one third of children immunologically eligible were ineligible using clinical criteria. Among children presenting in WHO stage I or II, 54 (32%) were eligible according to immunological criteria. Agreement with CD4 percent was poor for TLC (κ = 0.04), fair for total CD4 count (κ = 0.39) and substantial for CD4 percent computational estimate (κ = 0.71). Among 5 to 12 years old children, total CD4 count was higher in younger age groups (-32 cells/mm³per year older), CD4 percent was similar across age groups.</p> <p>Conclusion</p> <p>Age-specific thresholds for CD4 percent optimally determine pediatric ART eligibility. The use of CD4 percent computational estimate may increase ART access in settings with limited access to CD4 percent assays.</p

Affordable flow cytometry for enumeration of absolute CD4(+ )T-lymphocytes to identify subtype C HIV-1 infected adults requiring antiretroviral therapy (ART) and monitoring response to ART in a resource-limited setting

BACKGROUND: The World Health Organization (WHO)'s "3 × 5 program" has spurred efforts to place 3 million people on combination antiretroviral therapy (ART) for treatment of AIDS in resource-limited countries. Paradoxically, the cost of CD4(+ )T-lymphocyte count essential for decision-making to commence HIV positive adults on ART as well as for monitoring responses to ART remains unaffordable in most resource-limited countries. Thus, low-cost methods for enumerating CD4(+ )T-lymphocyte are urgently needed. OBJECTIVE: To evaluate Cyflow cytometry (Cyflow SL, Partec, Munster, Germany) for enumeration of absolute CD4(+ )T-lymphocyte in subtype C HIV-1 seropositive subjects using FACSCount (Becton and Dickinson, Immunocytometry Systems, San Jose, CA, USA) as the "predicate method". METHODS: A total of 150 HIV-1 seropositive subjects were included in the evaluation exercise. Fifty-eight specimens were collected from pregnant HIV-1 seropositive women (subtype C drug resistance study). Twenty-seven specimens were collected from women and their spouses with AIDS followed in a Duke ART study to assess the immunologic and virologic responses to generic ART, comprising Stavudine, Lamivudine and Nevirapine (Stalanev, Varichem Labs, Harare, Zimbabwe). Sixty-five specimens were collected from AIDS patients enrolled in an ongoing Kaposi Sarcoma (KS) study to investigate impact of ART on KS progression. Enumeration of CD4(+ )T-lymphocytes using FACSCount is routinely conducted for all the three studies. The Medical Research Council of Zimbabwe and Medicines Control Authority of Zimbabwe approved the studies. Whole blood was collected in EDTA vacutainer tubes and aliquoted into two tubes (200 μL in each). CD4(+ )T-lymphocyte counts were enumerated using a Cyflow counter, in the Department of Immunology and a FACSCount in the Department of Obstetrics and Gynaecology within 6 hours of phlebotomy following manufacturers' instructions. RESULTS: Using linear regression analysis, there was a very strong correlation (R = 0.991) between the overall CD4(+ )T-lymphocyte counts obtained by FACSCount and those obtained by Cyflow. When data analysis was stratified by study groups, there was a strong correlation between the FACSCount and Cyflow CD4(+ )T-lymphocyte counts from subjects in the three independent studies; Subtype C resistance (R(2 )= 0.987), Duke ART (R(2 )= 0.980) and KS (R(2 )= 0.994), Table 1. Using Bland-Altman plots, the overall, absolute CD4(+ )T lymphocytes obtained by the two methods were in excellent agreement (mean difference 1.21, 95% Confidence Interval {CI): -2.1 to 3.3). For the 0–250 CD4(+ )T-lymphocytes range, the CD4 counts obtained using FACSCount were also in good agreement with those obtained using Cyflow counter (mean difference = 2.6 cells/μL, 95% CI: -1.1 to 6.3). Similarly, in the 251–500 (mean difference 1.0, cells/μL, 95% CI: -3.7 to 5.6) and the 501–1200 (mean difference = 0.29 cells/μL, 95% CI: -8.1 to 8.7) CD4 T-lymphocytes range, good agreement was observed. CONCLUSION: The Cyflow counter is as accurate as the FACSCount in enumerating absolute CD4(+ )T-lymphocytes in the range 1–1200 cells/μL. Cyflow cytometry is relatively affordable, easy to use technology that is useful not only in identifying HIV seropositive individuals who require ART but also for monitoring immunologic responses to ART

Genetic Determination and Linkage Mapping of Plasmodium falciparum Malaria Related Traits in Senegal

Plasmodium falciparum malaria episodes may vary considerably in their severity and clinical manifestations. There is good evidence that host genetic factors contribute to this variability. To date, most genetic studies aiming at the identification of these genes have used a case/control study design for severe malaria, exploring specific candidate genes. Here, we performed a family-based genetic study of falciparum malaria related phenotypes in two independent longitudinal survey cohorts, as a first step towards the identification of genes and mechanisms involved in the outcome of infection. We studied two Senegalese villages, Dielmo and Ndiop that differ in ethnicity, malaria transmission and endemicity. We performed genome-scan linkage analysis of several malaria-related phenotypes both during clinical attacks and asymptomatic infection. We show evidence for a strong genetic contribution to both the number of clinical falciparum malaria attacks and the asymptomatic parasite density. The asymptomatic parasite density showed linkage to chromosome 5q31 (LOD = 2.26, empirical p = 0.0014, Dielmo), confirming previous findings in other studies. Suggestive linkage values were also obtained at three additional chromosome regions: the number of clinical malaria attacks on chromosome 5p15 (LOD = 2.57, empirical p = 0.001, Dielmo) and 13q13 (LOD = 2.37, empirical p = 0.0014 Dielmo), and the maximum parasite density during asymptomatic infection on chromosome 12q21 (LOD = 3.1, empirical p<10−4, Ndiop). While regions of linkage show little overlap with genes known to be involved in severe malaria, the four regions appear to overlap with regions linked to asthma or atopy related traits, suggesting that common immune related pathways may be involved

Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

The size, structure and distribution of host populations are key determinants of the genetic composition of parasite populations. Despite the evolutionary and epidemiological merits, there has been little consideration of how host heterogeneities affect the evolutionary trajectories of parasite populations. We assessed the genetic composition of natural populations of the parasite Schistosoma mansoni in northern Senegal. A total of 1346 parasites were collected from 14 snail and 57 human hosts within three villages and individually genotyped using nine microsatellite markers. Human host demographic parameters (age, gender and village of residence) and co-infection with Schistosoma haematobium were documented, and S. mansoni infection intensities were quantified. F-statistics and clustering analyses revealed a random distribution (panmixia) of parasite genetic variation among villages and hosts, confirming the concept of human hosts as 'genetic mixing bowls' for schistosomes. Host gender and village of residence did not show any association with parasite genetics. Host age, however, was significantly correlated with parasite inbreeding and heterozygosity, with children being more infected by related parasites than adults. The patterns may be explained by (1) genotype-dependent 'concomitant immunity' that leads to selective recruitment of genetically unrelated worms with host age, and/or (2) the 'genetic mixing bowl' hypothesis, where older hosts have been exposed to a wider variety of parasite strains than children. The present study suggests that host-specific factors may shape the genetic composition of schistosome populations, revealing important insights into host-parasite interactions within a natural system.Heredity advance online publication, 12 March 2014; doi:10.1038/hdy.2014.13.status: publishe

Avaliação da adsorção de tetraciclina em adsorvente convencional e modificado com cloreto de ferro, sulfato de cobre e peróxido de hidrogênio : análise regenerativa e aplicação em matriz aquosa real

A tetraciclina (TC) é uma droga lícita amplamente utilizada no âmbito farmacêutico. Considerada um indicador de contaminação antropogênica, é de grande interesse o estudo de técnicas eficazes para sua remoção. O processo de adsorção pode ser considerado um tratamento complementar ao tratamento convencional de água e efluentes. Nesse contexto, o presente trabalho tem como objetivo determinar as condições operacionais ótimas e o mecanismo de adsorção para a remoção de TC, utilizando sólido adsorvente convencional (CA) e modificado por cloreto de ferro (CAFe), sulfato de cobre (CA-Cu) e peróxido de hidrogênio (CA-H2O2), além de avaliar suas aplicações em matriz aquosa sintética e real e diferentes técnicas de regeneração. Na adsorção em batelada foram avaliadas as influências do pH (2 – 10), concentração de adsorvente (5 – 80 g.L-1) e tempo de contato (5 – 300 min). Foi realizada a investigação da cinética, do equilíbrio e da termodinâmica de adsorção. Analisaram-se a influência da temperatura, o tipo de solvente e o tempo de sonificação, respectivamente, para os três métodos regenerantes do sólido adsorvente – térmico, químico e ultrassônico. Para avaliar o tratamento com matriz aquosa real, a caracterização da carga poluidora e detecção de tetraciclina foram realizadas antes e após o processo de adsorção. Por fim, para confirmar suas propriedades, os materiais adsorventes foram caracterizados com análises de pHPCZ, MEV, DRX, FTIR e isotermas de adsorção/dessorção de N2. Os resultados mostraram que as condições ótimas de adsorção de TC para o sólido convencional são pH 4,0, tempo de retenção de 120 minutos e dosagem de adsorvente de 30 g.L-1. Os sólidos modificados se destacam, uma vez que não foi necessária a realização do ajuste de pH, apresentaram uma cinética inicial mais rápida e proporcionaram uma redução de no mínimo 50% de massa de adsorvente (15, 10 e 5 g.L-1 para CA-H2O2, CA-Fe e CA-Cu, respectivamente) necessária para a adsorção da tetraciclina, comparado com o sólido sem tratamento. Além disso, apresentaram uma maior área superficial e volume de mesoporos e não comprometeram a estrutura do material após a modificação. O modelo de pseudossegunda ordem foi o que melhor representou a cinética de adsorção do fármaco estudado. A isoterma de Redlich-Peterson descreveu o equilíbrio da TC nas três temperaturas, para todos os sólidos adsorventes. O estudo termodinâmico indicou que a adsorção foi espontânea, favorável e endotérmica. O tratamento com matriz aquosa real confirmou que a etapa de coagulação/floculação não consegue remover por completo a tetraciclina. Por fim, na etapa regenerativa, a eficiência de regeneração alcançou valores acima de 85%. Entre as três técnicas empregadas, o tratamento térmico a 200 °C foi selecionado como o agente regenerativo ótimo para o estudo, apresentando uma capacidade regenerativa de 90% até o sexto ciclo. De forma geral, este trabalho apresenta grande potencial em termos de remoção do micropoluente emergente tetraciclina, tanto em matriz aquosa sintética como real além uma possibilidade eficaz de regeneração e reutilização do sólido adsorvente saturado, minimizando resíduos e custos de tratamento.Tetracycline (TC) is a licit drug widely used in the pharmaceutical field. Considered an indicator of anthropogenic contamination, it is of great interest to study effective techniques for its removal. The adsorption process can be considered as a complementary treatment to conventional water and wastewater treatment. In this context, the present work aims to determine the optimal operating conditions and the adsorption mechanism for the removal of tetracycline drug (TC) using conventional adsorbent solid (CA) and modified by iron chloride (CA-Fe), copper sulfate (CA-Cu) and hydrogen peroxide (CA-H2O2), besides evaluating their applications in real aqueous matrix and different regeneration techniques. In batch adsorption the influences of pH (2 - 10), concentration of adsorbent (5 - 80 g.L-1) and contact time (5 - 300 min) were evaluated. The kinetics, equilibrium and adsorption thermodynamics were investigated. The influence of temperature, type of solvent and sonification time, respectively, were analyzed for the three regenerative methods of the adsorbent solid - thermal, chemical and ultrasonic. To evaluate the treatment with real aqueous matrix, the characterization of the pollutant charge and tetracycline detection were performed before and after the adsorption process. Finally, to confirm their properties, the adsorbent materials were characterized with pHPCZ, SEM, XRD, FTIR and N2 adsorption/desorption isotherms. The results showed that the optimum TC adsorption conditions for the conventional solid are at pH 4.0, retention time of 120 minutes and adsorbent dosage of 30 g.L-1. The modified solids stand out as no pH adjustment was required, had a faster initial kinetics and provided a minimum of 50% reduction in adsorbent mass (15, 10 and 5 gL-1 for CA-H2O2, CA-Fe and CA-Cu, respectively) for tetracycline adsorption compared to the untreated solid. Moreover, they presented a larger surface area and volume of mesoporous and did not compromise the material structure after modification. The pseudo-second order model best represented the adsorption kinetics of the studied drug. The Redlich-Peterson isotherm described the equilibrium of TC at all three temperatures for all adsorbent solids. The thermodynamic study indicated that the adsorption was spontaneous and favorable, besides increasing with the temperature increase. The actual aqueous matrix treatment confirmed that the coagulation/flocculation step cannot completely remove tetracycline. Finally, in the regenerative stage, the regeneration efficiency reached values above 85%. Among the three techniques employed, heat treatment at 200 ° C was selected as the optimal regenerative agent for the study, with a regenerative capacity of 90% until the sixth cycle. In general, this work has great potential in terms of removal of the emerging micro-pollutant tetracycline, both in synthetic and real aqueous matrix and an effective possibility of regeneration and reuse of saturated adsorbent solid, minimizing waste/treatment costs