Co-infection with Onchocerca volvulus and Loa loa microfilariae in central Cameroon: are these two species interacting?

Ivermectin treatment may induce severe adverse reactions in some individuals heavily infected with Loa loa. This hampers the implementation of mass ivermectin treatment against onchocerciasis in areas where Onchocerca volvulus and L. loa are co-endemic. In order to identify factors, including co-infections, which may explain the presence of high L. loa microfilaraemia in some individuals, we analysed data collected in 19 villages of central Cameroon. Two standardized skin snips and 30 mul of blood were obtained from each of 3190 participants and the microfilarial (mf) loads of both O. volvulus and L. loa were quantified. The data were analysed using multivariate hierarchical models. Individual-level variables were: age, sex, mf presence, and mf load; village-related variables included the endemicity levels for each infection. The two species show a certain degree of ecological separation in the study area. However, for a given individual host, the presence of microfilariae of one species was positively associated with the presence of microfilariae of the other (OR=1.79, 95% CI [1.43-2.24]). Among individuals harbouring Loa microfilariae, there was a slight positive relationship between the L. loa and O. volvulus mf loads which corresponded to an 11% increase in L. loa mf load per 100 O. volvulus microfilariae. Co-infection with O. volvulus is not sufficient to explain the very high L. loa mf loads harboured by some individuals

Effets secondaires sévères chez les sujets atteints de loase après traitement par ivermectine

Au cours de traitements à large échelle par ivermectine contre l'onchocercose, nous avons observé des effets secondaires sévères chez des sujets porteurs de fortes charges de #Loa loa. Quelques jours après la prise d'ivermectine, les patients deviennent fébriles, présentent des troubles neurologiques graves avec obnubilation ou coma associés à une anurie. Nous avons mené une étude visant à préciser la liaison entre ces effets secondaires et l'infection par #Loa loa, leur gravité, leur fréquence et les précautions à prendre lors de campagne de traitements à large échelle par l'ivermectine contre l'onchocercose dans les zones où la loase est endémique, c'est-à-dire dans le bloc forestier d'Afrique centrale. L'étude comprend deux parties distinctes. La première a été conduite en milieu hospitalier où nous avons traité 112 patients présentant une microfilarémie supérieure à 3000 microfilaires par millilitre de sang. La seconde a consisté en une étude rétrospective de tous les sujets ayant présenté des effets secondaires à la suite d'un traitement par ivermectine administré au cours d'une campagne de lutte contre l'onchocercose dans les départements du Cameroun où la loase est endémique. L'étude menée en milieu hospitalier confirme la relation entre la charge microfilarémique et la sévérité des effets secondaires observés. Il a été noté un passage des microfilaires dans le liquide céphalorachidien et les urines proportionnel à la charge initiale, trois jours en moyenne après la prise d'ivermectine. En outre, l'un des patients a présenté un coma et une anurie. Par ailleurs, nous avons reconstitué les dossiers clinique et biologique de 28 patients ayant présenté des troubles cliniques sévères dans les jours qui suivirent un traitement par ivermectine. Pour 12 d'entre eux, parmi lesquels on comptait deux décès, il a été retrouvé, outre la prise d'ivermectine, la présence d'une loase avec une forte charge initiale ou résiduelle après traitement, un délai inférieur à quatre jours entre le traitement et l'apparition des effets secondaires et un tableau clinique très évocateur. Sans remettre en cause les traitements à large échelle par l'ivermectine contre l'onchocercose, il devient indispensable de prendre certaines précautions lors des campagnes de traitement par l'ivermectine. Il nous semble en particulier nécessaire de revoir les critères de choix des populations à traiter contre l'onchocercose, d'informer les populations afin de les inciter à signaler l'apparition de troubles survenant après la prise d'ivermectine, d'augmenter la durée de la surveillance post-thérapeutique et de mettre en place un réseau de pharmacovigilance. (Résumé d'auteur

Photocatalytic activity of nanostructured anatase coatings obtained by cold gas spray

This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS)supported on titanium sub-oxide (TiO22x) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO2 particles fragmented when impacting onto the hard surface of the APS TiO22x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO2 coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25 photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide

Structural changes of hexamethylenetetramine and undecanedioic acid co-crystal (HMT-C11) as a function of the temperature

HMT-C11 belongs to the family of adducts formed by the cocrystallization of N-4(CH2)(6) molecules ( hexamethylenetetramine or HMT) and aliphatic dicarboxylic acids HOOC(CH2)(n-2)COOH with 5 less than or equal to n less than or equal to 13 (Cn). The adducts exhibit a layered structure in which the packing between HMT and Cn is determined by strong hydrogen bonds. The compounds in this family studied so far present thermotropic structural phase transitions and, depending on the chain length, disordered, twinned and modulated phases. The structure refinement of HMT-C11 based on X-ray diffraction experiments indicates three distinct phases from the melting point down to liquid nitrogen temperature: phase I is not crystalline; phase II is disordered ( stacking fault) and its average structure is described in space group Bmmb; phase III is partially disordered and its symmetry is P2(1)/c. The systematic study of the structure evolution of phase III upon cooling revealed that the disorder has a dynamic character (anharmonicity). The main structural change observed from 293 K down to 93 K is the increase of the tilting angle of the C11 chains relative to the layer plane and the rotation of the HMT molecules. Both HMT and C11 behave like rigid bodies in the temperature range investigated. The quality of the refinements leads to a conclusive model for the O-H...N hydrogen bonds linking HMT and C11

Structural phases of hexamethylenetetramine-pimelic acid (1/1): a unified description based on a stacking model

The thermotropic phase diagram of 1:1 co-crystals of hexamethylenetetramine and pimelic acid (heptanedioic acid) is investigated. Three crystalline phases are identified at ambient pressure. Phase I is disordered, as revealed by diffuse rods in its diffraction pattern. When the temperature is lowered the diffuse streaks disappear in Phase II, but superstructure reflections emerge indicating an ordering process of the structure through a non-ferroic, or at least non-ferroelastic, phase transition. Phase II is mainly characterized by an unusual distribution of its reflection intensities. Phase III is reached through a ferroelastic phase transition that induces twinned domains. A model based on the stacking of an elementary layer is proposed with the aim of describing the structures in a unified framework. Depending on the value of the unique stacking parameter eta, each of the different structures observed can be reproduced by this model. Its validity is then tested by a series of simulations reproducing the main features of the diffraction patterns such as the diffuse scattering streaks, the occurrence of superstructure peaks at lower temperature and twinning

The alpha(2)-polymorph of salicylideneaniline

N-Salicylideneaniline (SA), C13H11NO, belongs to the large family of aromatic Schiff bases. It is of particular importance owing to its reversible photoreactivity. SA forms two photochromic polymorphs, both with two non-coplanar benzene rings. In addition, we have recently discovered a planar polymorph, named the β-polymorph, which will be discussed in a subsequent paper. We report here the structure of the α(2)-polymorph in the orthorhombic crystal system. This compound exhibits a strong intramolecular O-H••• N hydrogen bond and the dihedral angle between the two rings varies with temperature

The lock-in phase in the urotropine-sebacic acid system

The 1,10-decanedioic acid-1,3,5,7-tetraazatricyclo[3.3.1.1(3,7)]decane (1/1) system, C10H18O4.C6H12N4, was studied at 215 (2) K. Its analysis provides important information with regard to the long-standing acid-carboxylate controversy in the urotropine-alkanedioic acid system. In the present structure, all the chain end-groups display a clear acid character. The asymmetric unit of this commensurate modulated phase contains two molecules of diacid as well as two molecules of urotropine. Furthermore, the chain packing suggests a possible order parameter for the lock-in transition

Enhancing the bioactivity of polymeric implants by means of cold gas spray coatings

Nanostructured anatase coatings were built-up on biocompatible polyetheretherketone (PEEK) by means of cold gas spray (CGS). Titanium layer was previously desposited, which acted as bond coat between PEEK and metal oxide. Semicrystalline polymer was not degraded during the spraying process and starting composition of titanium dioxide was not affected. TiO2 was homogeneously obtained onto CGS Ti layer and completely covered the piece. Primary human osteoblasts were seeded onto biomaterials and in vitro cell experiments provided evidence to confirm that nanostructured anatase coatings deposited by cold gas spray improve the performance of PEEK implants

Hydrogen production during the irradiation of gaseous organic compounds: advantage of an extracted beam

ACE, Accélérateur, NIMBInternational audienceThis paper presents a fundamental study of the radiolysis of gaseous organic molecules induced by proton beam. For that purpose, a specific extracted beam line associated with a gas irradiation cell was set up on the 4 MV facility of the Institut de Physique Nucléaire of Lyon. The first experiments have been performed with gaseous alkanes and alkenes. The gaseous species formed during irradiation are analysed by an on-line gas chromatography instrument equipped with two detectors. In order to test our experimental faiclity, we have studied the influence of irradiation parameters (duration, beam intensity, pressure) on the production of hydrogen. In the case of propane, the radiolytic yield value of hydrogen G(H$_2$) is equal to 3.7 for total does in the range of 0.4 to 2.3 MGy at atmospheric pressure