Statistical Properties of Parasite Density Estimators in Malaria

Malaria is a global health problem responsible for nearly one million deaths every year around 85% of which concern children younger than five years old in Sub-Saharan Africa. In addition, around million clinical cases are declared every year. The level of infection, expressed as parasite density, is classically defined as the number of asexual parasites relative to a microliter of blood. Microscopy of Giemsa-stained thick blood films is the gold standard for parasite enumeration. Parasite density estimation methods usually involve threshold values; either the number of white blood cells counted or the number of high power fields read. However, the statistical properties of parasite density estimators generated by these methods have largely been overlooked. Here, we studied the statistical properties (mean error, coefficient of variation, false negative rates) of parasite density estimators of commonly used threshold-based counting techniques depending on variable threshold values. We also assessed the influence of the thresholds on the cost-effectiveness of parasite density estimation methods. In addition, we gave more insights on the behavior of measurement errors according to varying threshold values, and on what should be the optimal threshold values that minimize this variability.     

Viral and Atypical Bacterial Etiology of Acute Respiratory Infections in Children under 5 Years Old Living in a Rural Tropical Area of Madagascar

Background

In Madagascar, very little is known about the etiology and prevalence of acute respiratory infections (ARIs) in a rural tropical area. Recent data are needed to determine the viral and atypical bacterial etiologies in children with defined clinical manifestations of ARIs.

Methods

During one year, we conducted a prospective study on ARIs in children between 2 to 59 months in the community hospital of Ampasimanjeva, located in the south-east of Madagascar. Respiratory samples were analyzed by multiplex real-time RT-PCR, including 18 viruses and 2 atypical bacteria. The various episodes of ARI were grouped into four clinical manifestations with well-documented diagnosis: “Community Acquired Pneumonia”(CAP, group I), “Other acute lower respiratory infections (Other ALRIs, group II)”, “Upper respiratory tract infections with cough (URTIs with cough, group III)”and “Upper respiratory tract infections without cough (URTIs without cough, group IV)”.

Results

295 children were included in the study between February 2010 and February 2011. Viruses and/or atypical bacteria respiratory pathogens were detected in 74.6% of samples, the rate of co-infection was 27.3%. Human rhinovirus (HRV; 20.5%), metapneumovirus (HMPV A/B, 13.8%), coronaviruses (HCoV, 12.5%), parainfluenza virus (HPIV, 11.8%) and respiratory syncytial virus A and B (RSV A/B, 11.8%) were the most detected. HRV was predominantly single detected (23.8%) in all the clinical groups while HMPV A/B (23.9%) was mainly related to CAP (group I), HPIV (17.3%) to the “Other ALRIs” (group II), RSV A/B (19.5%) predominated in the group “URTIs with cough” (group III) and Adenovirus (HAdV, 17.8%) was mainly detected in the “without cough” (group IV).

Interpretation

This study describes for the first time the etiology of respiratory infections in febrile children under 5 years in a malaria rural area of Madagascar and highlights the role of respiratory viruses in a well clinically defined population of ARIs.     

Genetic Diversity of Food-Isolated Salmonella Strains through Pulsed Field Gel Electrophoresis (PFGE) and Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR)

All over the world, the incidence of Salmonella spp contamination on different food sources like broilers, clams and cow milk has increased rapidly in recent years. The multifaceted properties of Salomnella serovars allow the microorganism to grow and multiply in various food matrices, even under adverse conditions. Therefore, methods are needed to detect and trace this pathogen along the entire food supply network. In the present work, PFGE and ERIC-PCR were used to subtype 45 Salmonella isolates belonging to different serovars and derived from different food origins. Among these isolates, S. Enteritidis and S. Kentucky were found to be the most predominant serovars. The Discrimination Index obtained by ERIC-PCR (0.85) was slightly below the acceptable confidence value. The best discriminatory ability was observed when PFGE typing method was used alone (DI = 0.94) or combined with ERIC-PCR (DI = 0.93). A wide variety of profiles was observed between the different serovars using PFGE or/and ERIC-PCR. This diversity is particularly important when the sample origins are varied and even within the same sampling origin.     

A Mineral and Antioxidant-Rich Extract from the Red Marine Algae Alsidium corallinum Exhibits Cytoprotective Effects Against Potassium Bromate-Induced Erythrocyte Oxidative Damages in Mice

The present study was carried out to investigate potassium bromate toxicity in mice and the corrective effects of marine algae Alsidium corallinum. The red algae demonstrated its rich composition in phenols, triterpenes, flavonoids, alkaloids, tropolones, sodium, potassium, calcium, magnesium, iron, copper, and zinc. To confirm its antioxidant potential, an in vivo study was performed on adult mice. The animals were divided into four groups: group I were used as controls, group II received potassium bromate (0.5 g/L) via drinking water, group III received potassium bromate (0.5 g/L) by the same route as group II and 7 % of A. corallinum ethanolic extract via their diet, and group IV received only 7 % of algae. The potassium bromate-treated group showed a significant decrease in erythrocyte, platelet, hemoglobin, and hematocrit values and a significant increase in total white blood cells, compared to those of controls. While, superoxide dismutase, catalase, glutathione, and vitamin C values were decreased by potassium bromate treatment, lipid peroxidation (as malondialdehyde) and erythrocyte osmotic fragility values were increased. Interestingly, potassium bromate treatment showed significant genotoxic effects, as demonstrated by DNA degradation. These changes were confirmed by blood smears histopathological observations which were marked by a necrosis and a decrease of erythrocytes number. A. corallinum extract appeared to be effective against hematotoxic and genotoxic changes induced by potassium bromate, as evidenced by the improvement of the parameters cited above.     

Mutations in BCAP31 Cause a Severe X-Linked Phenotype with Deafness,Dystonia, and Central Hypomyelination and Disorganize the Golgi Apparatus

BAP31 is one of the most abundant endoplasmic reticulum (ER) membrane proteins. It is a chaperone protein involved in several pathways, including ER-associated degradation, export of ER proteins to the Golgi apparatus, and programmed cell death. BAP31 is encoded by BCAP31, located in human Xq28 and highly expressed in neurons. We identified loss-of-function mutations in BCAP31 in seven individuals from three families. These persons suffered from motor and intellectual disabilities, dystonia, sensorineural deafness, and white-matter changes, which together define an X-linked syndrome. In the primary fibroblasts of affected individuals, we found that BCAP31 deficiency altered ER morphology and caused a disorganization of the Golgi apparatus in a significant proportion of cells. Contrary to what has been described with transient-RNA-interference experiments, we demonstrate that constitutive BCAP31 deficiency does not activate the unfolded protein response or cell-death effectors. Rather, our data demonstrate that the lack of BAP31 disturbs ER metabolism and impacts the Golgi apparatus, highlighting an important role for BAP31 in ER-to-Golgi crosstalk. These findings provide a molecular basis for a Mendelian syndrome and link intracellular protein trafficking to severe congenital brain dysfunction and deafness.     

Parasitoid foraging decisions mediated by artificial vibrations

In any host-parasitoid interaction, the detection of the host in its microhabitat is a crucial step in the interaction that has a major influence on the parasitoid's fitness. We used bioassays to investigate whether the parasitoid Sympiesis sericeicornis (Hymenoptera: Eulophidae) uses the vibrations of its host Phyllonorycter sp. gr. blancardella (Lepidoptera: Gracillariidae) to detect it in the leaf mine. From the large variety of signals produced by the host, we identified a unitary signal that could be reproduced artificially. We then sent this signal into emptied mines to analyse the reaction of the parasitoid. The wasps reacted by increasing both the time spent foraging on the mine and the number of insertions of the ovipositor to detect the ‘virtual’ host. This study is the first to show that parasitoids detect host vibrations.     

Multiple host‐cell recombination pathways act in Agrobacterium‐mediated transformation of plant cells

Using floral‐dip, tumorigenesis and root callus transformation assays of both germline and somatic cells, we present here results implicating the four major non‐homologous and homologous recombination pathways in Agrobacterium‐mediated transformation of Arabidopsis thaliana. All four single mutant lines showed similar mild reductions in transformability, but knocking out three of four pathways severely compromised Agrobacterium‐mediated transformation. Although integration of T–DNA into the plant genome is severely compromised in the absence of known DNA double‐strand break repair pathways, it does still occur, suggesting the existence of other pathways involved in T–DNA integration. Our results highlight the functional redundancy of the four major plant recombination pathways in transformation, and provide an explanation for the lack of strong effects observed in previous studies on the roles of plant recombination functions in transformation.