Selection of antimalarial drug resistance after intermittent preventive treatment of infants and children (IPTi/c) in Senegal

Senegal has since 2003 used sulphadoxine-pyrimethamine (SP) for Intermittent Preventive Treatment (IPT) of malaria in risk groups. However, the large-scale IPT strategy may result in increasing drug resistance. Our study investigated the possible impact of SP-IPT given to infants and children on the prevalence of SP-resistant haplotypes in the Plasmodium falciparum genes Pfdhfr and Pfdhps, comparing sites with and without IPTi/c. P. falciparum positives samples (n = 352) were collected from children under 5 years of age during two cross-sectional surveys in 2010 and 2011 in three health districts (two on IPTi/c and one without IPTi/c intervention) located in the southern part of Senegal. The prevalence of SP-resistance-related haplotypes in Pfdhfr and Pfdhps was determined by nested PCR followed by sequence-specific oligonucleotide probe (SSOP)–ELISA. The prevalence of the Pfdhfr double mutant haplotypes (CNRN and CICN) was stable between years at < 10% in the control group (P = 0.69), while it rose significantly in the IPTi/c group from 2% in 2010 to 20% in 2011 (P = 0.008). The prevalence of the Pfdhfr triple mutant haplotype (CIRN) increased in both groups, but only significantly in the IPTi/c group from 41% to 65% in 2011 (P = 0.005). Conversely, the Pfdhps 437G mutation decreased in both groups from 44.6% to 28.6% (P = 0.07) and from 66.7% to 47.5% (P = 0.02) between 2010 and 2011 in the control and the IPTi/c groups, respectively. Combined with Pfdhfr, there was a weak trend for decreasing prevalence of quadruple mutants (triple Pfdhfr + Pfdhps 437G) in both groups (P = 0.15 and P = 0.34). During the two cross-sectional surveys, some significant changes were observed in the SP-resistance-related genes. However, since these changes were observed in the two groups, the IPTi/c strategy does only seem to have limited impact on resistance development and other factors as well. However, continuous monitoring will be needed, due to the up-scaling of the IPTi/c strategy in Senegal according to WHO recommendations.     

The Interaction of Drugs with DNA Gyrase: A Model for the Molecular Basis of Quinolone Action

Abstract

DNA gyrase supercoils DNA in bacteria. The fact that it is essential in all bacteria and absent from eukaryotes makes it an ideal drug target. We discuss the action of coumarin and quinolone drugs on gyrase. In the case of coumarins, the drugs are known to be competitive inhibitors of the gyrase ATPase reaction. From a combination of structural and biochemical studies, the molecular details of the gyrase-coumarin complex are well established. In the case of quinolones, the drugs are thought to act by stabilising a cleavage complex between gyrase and DNA that arrests polymerases in vivo. The exact nature of the gyrase-quinolone-DNA complex is not known; we propose a model for this complex based on structural and biochemical data.     

Corticospinal Tract Tracing in the Marmoset with a Clinical Whole-Body 3T Scanner Using Manganese-Enhanced MRI

Manganese-enhanced MRI (MEMRI) has been described as a powerful tool to depict the architecture of neuronal circuits. In this study we investigated the potential use of in vivo MRI detection of manganese for tracing neuronal projections from the primary motor cortex (M1) in healthy marmosets (Callithrix Jacchus). We determined the optimal dose of manganese chloride (MnCl₂) among 800, 400, 40 and 8nmol that led to manganese-induced hyperintensity furthest from the injection site, as specific to the corticospinal tract as possible, and that would not induce motor deficit. A commonly available 3T human clinical MRI scanner and human knee coil were used to follow hyperintensity in the corticospinal tract 24h after injection. A statistical parametric map of seven marmosets injected with the chosen dose, 8 nmol, showed the corticospinal tract and M1 connectivity with the basal ganglia, substantia nigra and thalamus. Safety was determined for the lowest dose that did not induce dexterity and grip strength deficit, and no behavioral effects could be seen in marmosets who received multiple injections of manganese one month apart. In conclusion, our study shows for the first time in marmosets, a reliable and reproducible way to perform longitudinal ME-MRI experiments to observe the integrity of the marmoset corticospinal tract on a clinical 3T MRI scanner.     

Epidemiology and Genetic Characterization of Measles Strains in Senegal, 2004-2013

BackgroundIn Senegal, with the variable routine vaccination coverage, the risk for illness and death from measles still exists as evidenced by the measles epidemic episode in 2009. Since 2002 a laboratory-based surveillance system of measles was established by the Ministry of Health and the Institut Pasteur de Dakar. The present study analysed the data collected over the 10 years inclusive between 2004-2013 in order to define a measles epidemiological profile in Senegal, and we carried out a phylogenetic analysis of measles virus circulating in Senegal over the period 2009-2012.ConclusionImprovements in the measles surveillance in Senegal are required and the introduction of oral fluid and FTA cards as an alternative to transportation of sera should be investigated to improve surveillance. The introduction of a national vaccine database including number of doses of measles-containing vaccine will greatly improve efforts to interrupt and ultimately eliminate measles virus transmission in Senegal.     

The First Draft of the Endostatin Interaction Network

Endostatin is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It binds to heparin/heparan sulfate and to a number of proteins, but its molecular mechanisms of action are not fully elucidated. We have used surface plasmon resonance (SPR) arrays to identify new partners of endostatin, and to give further insights on its molecular mechanism of action. New partners of endostatin include glycosaminoglycans (chondroitin and dermatan sulfate), matricellular proteins (thrombospondin-1 and SPARC), collagens (I, IV, and VI), the amyloid peptide Aβ-(1–42), and transglutaminase-2. The biological functions of the endostatin network involve a number of extracellular proteins containing epidermal growth factor and epidermal growth factor-like domains, and able to bind calcium. Depending on the trigger event, and on the availability of its members in a given tissue at a given time, the endostatin network might be involved either in the control of angiogenesis, and tumor growth, or in neurogenesis and neurodegenerative diseases.Endostatin is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It inhibits angiogenesis and tumor growth (1–3). The effect of endostatin depends on its concentration (4, 5), on the length of exposure (6), on the type of endothelial cells (7), and on the growth factor inducing cell proliferation (fibroblast growth factor 2 or VEGF)³ (8, 9).Endostatin binds to several membrane proteins including α5β1 and αvβ3 integrins (10, 11), heparan sulfate proteoglycans (glypican-1 and -4) (12), and KDR/Flk1/VEGFR2 (13). We have previously characterized the binding of endostatin to heparan sulfate chains (9), and of endostatin to integrins (11). Furthermore, we have shown that α5β1, αvβ3, and αvβ5 integrins bind to heparin/heparan sulfate (11).The broad molecular targets of endostatin suggest that multiple signaling systems are involved in mediation of its antiangiogenic action. Endostatin is a broad spectrum angiogenesis inhibitor that suppresses angiogenesis by blocking general mechanisms that govern endothelial cell growth (14), and initiates a complex network of signaling at the gene level (15). However, its molecular mechanism of action is still a matter of debate.An integrative view of the endostatin interaction network, including interactions between endostatin partners, is necessary to provide a clear understanding of how all these molecules work together to regulate angiogenesis, and tumor growth. This global approach places individual proteins into a functional context, and takes into account the fact that a single molecule such as endostatin can affect a wide range of other cell components. Indeed, most proteins and other components carry out their functions within a complex network of interactions and this approach based on protein-protein interaction networks has been developed for several years to give new clues on biological processes (16).This study was thus designed to identify additional extracellular partners of endostatin in an attempt to obtain new insights into its mechanisms of action, and the biological processes in which it participates. For this purpose, we have developed protein and glycosaminoglycan arrays using an automated surface plasmon resonance (SPR) platform. Proteins and glycosaminoglycans selected for SPR analysis were present in the same tissues or structures, such as basement membranes (17), brain (18), cartilage (19), or they were involved in the same physio-pathological processes (angiogenesis, neuro-degenerative diseases) as endostatin, and they were available as full-length molecules. Collagens I and VI, for example, have been selected because the α1 and α2 chains of collagen VI were determined to be potential pan-endothelial markers as was the α1 chain of collagen XVIII containing endostatin (20), and because the genes coding for the α1 and α2 chains of collagen I, and the α3 chain of collagen VI are up-regulated in angiogenic vessels and elevated in tumor endothelium (20). Some proteins and glycosaminoglycans were also included to serve as positive controls for well known interactions with the potential partners of endostatin. We report that endostatin binds to other endogenous angiogenesis inhibitor, the matricellular proteins thrombospondin-1 and SPARC, and to several collagens (I, IV, and VI). Other interacting partners of endostatin are transglutaminase-2, the amyloid peptide Aβ-(1–42), chondroitin, and dermatan sulfate.     

Solid-phase synthesis and structure-activity relationships of novel biarylethers as melanin-concentrating hormone receptor-1 antagonists

Melanin-concentrating hormone (MCH) is a cyclic 19 amino acid orexigenic neuropeptide. The action of MCH on feeding is thought to involve the activation of its respective G protein-coupled receptor MCH-R1. Consequently, antagonists that block MCH regulated MCH-R1 activity may provide a viable approach to the treatment of diet-induced obesity. This communication reports the discovery of a novel MCH-R1 receptor antagonist, the biarylether 7, identified through high throughput screening. The solid-phase synthesis and structure-activity relationship of related analogs is described.     

Preferential Transfer of Certain Plasma Membrane Proteins onto T and B Cells by Trogocytosis

T and B cells capture antigens via membrane fragments of antigen presenting cells (APC) in a process termed trogocytosis. Whether (and how) a preferential transfer of some APC components occurs during trogocytosis is still largely unknown. We analyzed the transfer onto murine T and B cells of a large panel of fluorescent proteins with different intra-cellular localizations in the APC or various types of anchors in the plasma membrane (PM). Only the latter were transferred by trogocytosis, albeit with different efficiencies. Unexpectedly, proteins anchored to the PM''s cytoplasmic face, or recruited to it via interaction with phosphinositides, were more efficiently transferred than those facing the outside of the cell. For proteins spanning the PM''s whole width, transfer efficiency was found to vary quite substantially, with tetraspanins, CD4 and FcRγ found among the most efficiently transferred proteins. We exploited our findings to set immunodiagnostic assays based on the capture of preferentially transferred components onto T or B cells. The preferential transfer documented here should prove useful in deciphering the cellular structures involved in trogocytosis.