Typologie Des Gîtes Larvaires Et Résistance Des Vecteurs Du Paludisme A La Deltaméthrine Dans les Milieux Urbain Et Rural Du Département De l’Atlantique Au Sud Du Bénin: Données Préliminaires

La lutte antilarvaire récemment recommandée par l’OMS, requiert une connaissance approfondie de la distribution et de la typologie des gîtes larvaires des vecteurs du paludisme. L’objectif de cette étude est d’identifier les différents gîtes larvaires des anophèles et leur mécanisme de résistance à la deltaméthrine. Des prospections larvaires ont été effectuées en 2017 durant les saisons pluvieuses et sèches dans trois communes au sud du Bénin. Les moustiques issus de l’émergence des larves ont été soumis à la deltaméthrine et au bendiocarb selon le protocole de l’OMS. L’identification moléculaire des anophèles et le génotypage de la mutation Kdr ont été réalisés par PCR et l’expression des oxydases, des estérases α et β, et des GST ont été mesurées. Les prospections larvaires ont permis de répertorier 37 gîtes larvaires regroupés en 13 types. La majorité des gîtes étaient anthropiques. La densité larvaire variait d’un type de gîtes à l’autre. An. coluzzii et An. gambiae étaient les deux vecteurs du paludisme vivant en sympatrie dans lestroissites d’étude. Ils sont fortement résistants à la deltaméthrine avec la présence de la mutation kdr à des fréquences très élevées et une augmentation des activités des estérases dans les populations d’anophèles collectés à Zè et des GST à Abomey-Calavi et Allada. La prolifération des vecteurs du paludisme serait imputable à l’insalubrité de l’environnement immédiat et aux activités anthropiques qui créent et assurent le maintien des gîtes larvaires. Ces données pourraient servir au renforcement des stratégies de lutte contre le paludisme déjà en cours. Anopheles larval control, recently recommended by WHO, requires a deep knowledge of the distribution and typology of larval breeding sites. The objective of this study is to identify the different larval habitats colonized by Anopheles and their insecticide resistance mechanism. Larval surveys were carried out in three Districts in south of Benin in 2017, during the rainy and dry seasons. Mosquitoes breeding sites have been characterized and mapped. Mosquitoes from the emergence of larvae were tested to deltamethrin and bendiocarb according to the WHO protocol. The molecular identification of anopheles and the genotyping of the kdr mutation were performed by PCR and the expression of oxidases, esterases, and GSTs was measured. Larval surveys have identified 37 breeding sites categorized into 13 types. Most of the larval habitats were anthropogenics. An. coluzzii and An. gambiae were the two malaria vectors found in sympatric in the three study sites. These two vectors were highly resistant to deltamethrin with the presence of the kdr L1014F mutation at very high frequencies and an increase in esterase activities in anopheline populations collected in Zè and GST in Abomey-Calavi and Allada. The proliferation of malaria vectors is attributable to the unhealthy environment and human activities that create and maintain mosquito breeding. This study highlighted diversity in the type of breeding site of An. gambiae s.s in the Atlantic Department, suggesting the adaptation of this species in its environment. These results could be used to develop an antilarval control strategy in Abomey-Calavi, Zè and in Allada

Organophosphate and carbamate susceptibility profiling of Anopheles gambiae sl. across different ecosystems in southern Benin

Background To overcome the spread of high pyrethroid resistance in the main malaria vectors and malaria disease persistence, it is crucial to look for effective and better resistance management strategies. Understanding the phenotypic profile of Anopheles gambiae sl. against alternatives insecticides like organophosphates and carbamates is crucial. Methods Anopheles larvae and pupae were collected from the breeding sites in rice fields, pineapple crop areas, and peri-urban areas. WHO susceptibility tests were conducted on unfed female mosquitoes aged 3–5 days old. Mosquitoes were exposed to malathion 5%, pirimiphos-methyl 0.25%, and bendiocarb 0.1% using the standard WHO protocol. Polymerase chain reaction (PCR) techniques were used to detect species, kdr and Ace-1 mutations. Results Anopheles gambiae sl. from Sèdjè-Dénou rice field population was resistant to bendiocarb (0.1%) with a mortality rate of 72.2% whereas Anopheles gambiae sl. populations from Zinvié-Dokomey (rice field), Zè-Tozounmè (pineapple field), and Adjagbo (peri-urban area) were suspected to be resistant with mortality rates of 90%, 93.5%, 95.4% respectively. However, all of them were susceptible to organophosphates (malathion and pirimiphos-methyl) with a mortality rate of 100%. PCR assay revealed that 100% of the mosquitoes tested were Anopheles coluzzii. The frequencies of Ace-1R mutation in all Anopheles coluzzii populations tested were low (3–27%). Conclusions Organophosphates (malathion and pirimiphos-methyl) have maintained their efficacy against Anopheles coluzzii populations from Sèdjè-Dénou (rice field), Zè Tozounmè (pineapple field), Zinvié Dokomey (rice field), or Adjagbo (peri-urban area). The good efficacy of these organophosphates against Anopheles coluzzii populations from the southern part of Benin are observed in the current study. The use of pirimiphos-methyl for IRS in this part of the country would be a successful alternative for malaria control in this area

A preliminary analysis on the effect of copper on Anopheles coluzzii insecticide resistance in vegetable farms in Benin.

The use of agrochemicals in vegetable production could influence the selection for insecticide resistance in malaria vectors. Unfortunately, there is a dearth of information on the potential contribution of agrochemicals to insecticide resistance in Anopheles mosquitoes breeding on vegetable farms in southern Benin. A Knowledge, Attitudes and Practices study was conducted with 75 vegetable farmers from Houeyiho and Seme to determine the main agrochemicals used in vegetable production, and the concentration and frequency of application, among other details. Mosquitoes and breeding water were sampled from the farms for analysis. Bioassays were conducted on mosquitoes, while breeding water was screened for heavy metal and pesticide residue contamination. Lambda-cyhalothrin was the main insecticide (97.5%) used by farmers, and Anopheles coluzzii was the main mosquito identified. This mosquito species was resistant (30-63% mortality rate) to λ-cyhalothrin. It was also observed that 16.7% of the examined breeding sites were contaminated with λ-cyhalothrin residues. Furthermore, copper contamination detected in mosquito breeding sites showed a positive correlation (r = 0.81; P = 0.0017) with mosquito resistance to λ-cyhalothrin. The presence of copper in λ-cyhalothrin-free breeding sites, where mosquitoes have developed resistance to λ-cyhalothrin, suggests the involvement of copper in the insecticide resistance of malaria vectors; this, however, needs further investigation

Approche multiparamétrique de l étude des propriétés de populations cellulaires par vidéomicrofluorimétrie quantitative (application à l étude de l effet de xénobiotiques)

En utilisant la vidéomicrofluorimétrie et l analyse multiparamétrique (typologie et analyse factorielle discriminante) de paramètres cellulaires obtenus de l analyse d image et permettant la distribution des cellules dans les phase du cycle cellulaire, nous avons étudié la cytotoxicité et le mode d action de cyclopeptides, les Laxaphycine A (laxa A) et Laxaphycine B (laxa B) sur des cellules lymphoblastiques humaines (CCRF-CEM) sensibles (CEM-WT), MDR classique (CEM-VLB) et MDR atypique (CEM-VM1) soumises au triple marquage de Hoechst 33342 (ADN nucléaire), Rhodamine 123 (mitochondries) et Rouge Nil (membrane plasmique). Les résultats indiquent un indice de résistance de valeur 2 pour les CEM-VLB, une synergie d effet entre laxa B et laxa A (inactive seule) et suivant les traitements, une modification du nombre de cellules polyploïdes suggérant un mode d action différent pour laxa B et pour laxa A + laxa B. Les CCRF-CEM ont été classées en cinq groupes : trois liés au cycle cellulaire (G0-G1, S, G2+M) et deux de cellules polyploïdes appelés Gn1 et Gn2. La meilleure classification est obtenue par typologie directe suivie de successives analyses factorielles discriminantes jusqu à avoir la plus faible valeur du lambda de Wilks et la valeur du rapport quantité d ADN G2+M/G0-G1 proche de 2. Les Laxaphycines provoquent l arrêt du cycle cellulaire en G2+M avec accumulation de cellules polyploïdes induisant l inhibition de la prolifération cellulaire. L effet cytotoxique pourrait être impliqué dans les changements d interaction avec la membrane plasmique suggérant que les Laxaphycines soient actives au niveau membranaire. La Laxaphycine A pourrait moduler l activité de la P-gpUsing videomicrofluorometry and multiparametric analysis (typology and discriminant factorial analysis) of cell parameters obtained from image analysis and which allows cell distribution in the phases of cell cycle, we have studied the cytotoxicity and the mode of action of the peptides cyclic Laxaphycin A (laxa A) and Laxaphycin B (laxa B) in human lymphoblastic (CCRF-CEM) cells, sensitive (CEM-WT), classic MDR (CEM-VLB) and atypical MDR (CEM-VM1). The cells were submitted to a triple labelling with Hoechst 33342 (nuclear DNA), Rhodamine 123 (mitochondria) and Nile red (plasma membrane). The results indicate a resistance index of 2 for CEM-VLB cells, a synergistic effect between laxa B and laxa A, which is inactive by itself and following the treatments, a modification of the number of polyploid cells suggesting a different mode of action for laxa B and laxa A + laxa B. The CCRF-CEM cells were classified into five groups: three related to the cell cycle phases (G0-G1, S, G2+M) and two for polyploid cells called Gn1 and Gn2. The best classification results were obtained by direct initial typology followed by successive discriminant factorial analysis until reaching the lowest value of lambda of Wilks and a ratio G2+M/G0-G1 for DNA content close to two. Laxaphycins induce cell cycle arrest at G2+M phase with accumulation of polyploid cells that results in inhibition of cell proliferation. The cytotoxic effects might be involved in interaction change with plasma membrane suggesting that Laxaphycins might be membrane active agents. Laxaphycin A could induce modulations of P-gp activityPERPIGNAN-BU Sciences (661362101) / SudocSudocFranceF

Beneficial Effects of Omega-3 Polyunsaturated Fatty Acids in Gestational Diabetes: Consequences in Macrosomia and Adulthood Obesity

Omega-3 polyunsaturated fatty acids (PUFAs) are increasingly being used to prevent cardiovascular diseases, including diabetes and obesity. In this paper, we report data on the observed effects of omega-3 PUFA on major metabolic disorders and immune system disruption during gestational diabetes and their consequences on macrosomia. While controversies still exist about omega-3 PUFA effects on antioxidant status regarding the level of omega-3 PUFA in diet supplementation, their lipid-lowering effects are unanimously recognized by researchers. Animal studies have shown that omega-3 PUFA contributes to the maintenance of the immune defense system by promoting the differentiation of T helper (Th) cell to a Th2 phenotype in diabetic pregnancy and by shifting the Th1/Th2 ratio from a deleterious proinflammatory Th1 phenotype to a protective anti-inflammatory Th2 phenotype in macrosomia and in adulthood obesity that results from macrosomia at birth. Based on the available evidence, international nutritional and food agencies recommend administration of omega-3 PUFA as triglyceride-lowering agents, for the prevention of cardiovascular disease risk and during human pregnancy and lactation. Furthermore, studies targeting humans are still required to explore application of the fatty acids as supplement in the management of gestational diabetes and inflammatory and immune diseases

Ascorbic acid alters cell fate commitment of human neural progenitors in a WNT/β-catenin/ROS signaling dependent manner

Abstract Background Improving the neuronal yield from in vitro cultivated neural progenitor cells (NPCs) is an essential challenge in transplantation therapy in neurological disorders. In this regard, Ascorbic acid (AA) is widely used to expand neurogenesis from NPCs in cultures although the mechanisms of its action remain unclear. Neurogenesis from NPCs is regulated by the redox-sensitive WNT/β-catenin signaling pathway. We therefore aimed to investigate how AA interacts with this pathway and potentiates neurogenesis. Methods Effects of 200 μM AA were compared with the pro-neurogenic reagent and WNT/β-catenin signaling agonist lithium chloride (LiCl), and molecules with antioxidant activities i.e. N-acetyl-L-cysteine (NAC) and ruthenium red (RuR), in differentiating neural progenitor ReNcell VM cells. Cells were supplemented with reagents for two periods of treatment: a full period encompassing the whole differentiation process versus an early short period that is restricted to the cell fate commitment stage. Intracellular redox balance and reactive oxygen species (ROS) metabolism were examined by flow cytometry using redox and ROS sensors. Confocal microscopy was performed to assess cell viability, neuronal yield, and levels of two proteins: Nucleoredoxin (NXN) and the WNT/β-catenin signaling component Dishevelled 2 (DVL2). TUBB3 and MYC gene responses were evaluated by quantitative real-time PCR. DVL2-NXN complex dissociation was measured by fluorescence resonance energy transfer (FRET). Results In contrast to NAC which predictably exhibited an antioxidant effect, AA treatment enhanced ROS metabolism with no cytotoxic induction. Both drugs altered ROS levels only at the early stage of the differentiation as no changes were held beyond the neuronal fate commitment stage. FRET studies showed that AA treatment accelerated the redox-dependent release of the initial pool of DVL2 from its sequestration by NXN, while RuR treatment hampered the dissociation of the two proteins. Accordingly, AA increased WNT/β-catenin signaling output i.e. MYC mRNA level, whereas RuR attenuated it. Moreover, AA improved neurogenesis as much as LiCl as both TUBB3-positive cell yield and TUBB3 mRNA level increased, while NAC or RuR attenuated neurogenesis. Markedly, the neurogenesis outputs between the short and the full treatment with either NAC or AA were found unchanged, supporting our model that neuronal yield is altered by events taking place at the early phase of differentiation. Conclusions Our findings demonstrate that AA treatment elevates ROS metabolism in a non-lethal manner prior to the NPCs commitment to their neuronal fate. Such effect stimulates the redox-sensitive DVL2 activation and WNT/β-catenin signaling response that would enhance the ensuing neuronal cell differentiation

Some pathophysiological insights into ovarian infestation by Myxobolus sp. (Myxozoa: Myxosporea) in Clarias gariepinus (Clariids: Silurids) from Bénin (West Africa)

International audienceMature female specimens of the catfish Clarias gariepinus originating from Ouémé River (Benin) were investigated into ovarian myxozoan parasites. Spores of Myxobolus sp. (Myxozoa: Myxosporea) were found encrusted in the whitish color oocytes which present fat dot aspect in the gonads. The pathological investigation by electron microscopy revealed that maturation and multiplication of spores induced lytic action, deformation and dysfunction of the oocyte internal structures. No host inflammatory reaction was observed, while yolk, lipid, mitochondria, and other oocyte components were degenerated inducing empty area in the oocyte and could lead to castration in case of wide infestation. The mean prevalence was 19.79 %. No significant difference was observed within seasonal prevalence (χ2 = 1.771; df = 3; p > 0.05). Though the host length classes ranging from 35 to 39 cm and 40 to 45 cm were more infected, difference was not significant (χ2 = 2.273; df = 4; p > 0.05) within them. The spores are ovoid in shape with two polar capsules which are equal in size, pyriform, and converging in anterior part of spore with four to five polar filament turns. Spore body are (11.47 ± 0.67) × (8.19 ± 0.52) μm length by width while polar capsule size are (4.24 ± 0.25) × (3.07 ± 0.28) μm and located in the first third portion of the spore. The molecular approaches are still running for accurate identification of this parasite

A 90-Day Oral Toxicity Study of an Ethanolic Root Extract of Caesalpinia bonduc (L.) Roxb. in Wistar Rats

Background. Plant medicine is the oldest form of health care known to mankind; hence, studies on their safety for use are essential for the control of adverse drug effects. In Benin, Caesalpinia bonduc is one of many medicinal plants used as aphrodisiac, and for treatment of various ailments including prostatic hyperplasia. Despite its numerous ethnomedicinal benefits, toxicological information associated with its chronic use is currently limited. Objective. The present study therefore assessed the toxicity of an ethanolic root extract of Caesalpinia bonduc in Wistar rats. Methods. Caesalpinia bonduc root extract was administered by oral gavage at doses of 31.25, 125, and 500 mg/kg/day for 90 days to male Wistar rats, after which body weight changes, food consumption, urinary parameters, hematological and blood biochemical parameters, organ weights changes, gross pathology, and histopathology of vital organs were assessed. Results. There were no death or abnormal clinical signs, no significant changes in body weight gain or urinary parameters, and no changes in necropsy and histopathology findings of vital organs associated with extract treatment. However, some indices such as erythrocytes, total cholesterol, and aspartate amino transferase increased in rats treated with high doses of the extract, as well as relative weight of testes, followed by a decrease in food intake and prostate relative weight. Conclusion. The results indicate that an ethanolic root extract of Caesalpinia bonduc does not cause significant adverse effects and suggest its tolerability up to 500 mg/kg for daily administration of 90 days

Oxidative stress does not play a primary role in the toxicity induced with clinical doses of doxorubicin in myocardial H9c2 cells

International audienceThe implication of oxidative stress as primary mechanism inducing doxorubicin (DOX) cardiotoxicity is still questionable as many in vitro studies implied supra-clinical drug doses or unreliable methodologies for reactive oxygen species (ROS) detection. The aim of this study was to clarify whether oxidative stress is involved in compliance with the conditions of clinical use of DOX, and using reliable tools for ROS detection. We examined the cytotoxic mechanisms of 2 μM DOX 1 day after the beginning of the treatment in differentiated H9c2 rat embryonic cardiac cells. Cells were exposed for 2 or 24 h with DOX to mimic a single chronic dosage or to favor accumulation, respectively. We found that apoptosis was prevalent in cells exposed for a short period with DOX: cells showed typical hallmarks as loss of anchorage ability, mitochondrial hyperpolarization followed by the collapse of mitochondrial activity, and nuclear condensation. Increasing the exposure period favored a shift to necrosis as the cells preferentially exhibited early DNA impairment and nuclear swelling. In either case, measuring the fluorescence lifetime of 1-pyrenebutyric acid or the intensities of dihydroethidium or amplex red showed a consistent pattern in ROS production which was a slight increased level far from representative of an oxidative stress. Moreover, pre-treatment with dexrazoxane provided a cytoprotective effect although it failed to detoxify ROS. Our data support that oxidative stress is unlikely to be the primary mechanism of DOX cardiac toxicity in vitro