History and sensitivity comparison of two standard whole-sediment toxicity tests with crustaceans : the amphipod Hyalella azteca and the ostracod Heterocypris incongruens microbiotest

The review first details the development of the test procedures with Hyalella azteca which historically emerged as one of the recommended test species for whole-sediment assays and its gradual standardization and endorsement by national and international organizations. The sensitivity and precision of the H. azteca test for application on chemicals and on real world sediments is discussed. The review subsequently addresses the development of the whole sediment microbiotest with the ostracod crustacean Heterocypris incongruens with larvae of this test species hatched from dormant eggs (cysts), rendering this assay stock culture/maintenance free. The application of the 6-day ostracod microbiotest on sediments in Canada and in Belgium is discussed, as well as its endorsement by the ISO subsequent to an extensive international inter-laboratory ring test. The sensitivity of the amphipod and ostracod tests is compared by data from studies in which both assays were applied in parallel. A comparison of more than 1000 ostracod/amphipod data pairs of a 12-year river sediment monitoring study in Flanders/Belgium confirmed that both whole-sediment assays have a similar sensitivity and that the 6-day ostracod microbiotest is a valuable and cost-effective alternative to the 10-14 day amphipod test for evaluation of the toxic hazard of polluted sediments

Aerodynamic investigations of ventilated brake discs.

The heat dissipation and performance of a ventilated brake disc strongly depends on the aerodynamic characteristics of the flow through the rotor passages. The aim of this investigation was to provide an improved understanding of ventilated brake rotor flow phenomena, with a view to improving heat dissipation, as well as providing a measurement data set for validation of computational fluid dynamics methods. The flow fields at the exit of four different brake rotor geometries, rotated in free air, were measured using a five-hole pressure probe and a hot-wire anemometry system. The principal measurements were taken using two-component hot-wire techniques and were used to determine mean and unsteady flow characteristics at the exit of the brake rotors. Using phase-locked data processing, it was possible to reveal the spatial and temporal flow variation within individual rotor passages. The effects of disc geometry and rotational speed on the mean flow, passage turbulence intensity, and mass flow were determined. The rotor exit jet and wake flow were clearly observed as characterized by the passage geometry as well as definite regions of high and low turbulence. The aerodynamic flow characteristics were found to be reasonably independent of rotational speed but highly dependent upon rotor geometry

Innovative PCR without DNA extraction for African sickle cell disease diagnosis.

OBJECTIVES: Hemoglobin (Hb) disorders consist of thalassemia and Hb structural variants, of which the major forms are associated with severe anemia and/or vascular occlusion. Current diagnostic techniques are highly accurate and mostly based on isoelectric focusing, high-performance liquid chromatography or mass spectrometry, which often require advanced laboratory equipment. In sub-Saharan Africa, the Hb disorders are mainly associated to the pathological variants hemoglobin S (HbS) and HbC. Unfortunately, until now, it is not easy to get a diagnosis of these disorders in this area. In this study, we tested the performance of a new molecular diagnostic tests on qualified samples. METHODS: The Human Hb S/C Lamp assay is a new polymerase chain reaction test able to detect HbS, HbC and HbA alleles without DNA extraction, directly on fresh or frozen blood samples, or on dried blood spots (DBS). In this study, we compared the genotyping of 248 blood samples (56 whole blood and 192 DBS) with this LAMP assay to the routine diagnostic methods performed in the genetics lab at the university hospital of Liege. RESULTS: Our results show that the LAMP method can detect HbS and HbC with an accuracy of 100%. Moreover, this test can be used for the neonatal screening because we did not observe any interference with fetal Hb. DISCUSSION: To our knowledge, this method is the only molecular assay that can be performed directly on dried blood cards without DNA extraction, lowering handling, turnaround time and costs

Monitorage de la pression fontanellaire chez le nouveau-né et le nourrisson. Evaluation d'une nouvelle technique de mesure, détermination des valeurs normales et utilisation clinique.

The experience with 200 measurements of anterior fontanelle pressure with the Rotterdam Teletransducer in newborns and infants is reported. Statistical analysis of 25 comparative measurements between anterior fontanelle pressure and invasive cerebrospinal fluid pressure showed an excellent correlation (rs = 0.95). Measurements were reproducible and the plot quality allowed visualisation of pulse pressure and pressure waves. Normal values of the anterior fontanelle pressure, pulse pressure amplitude and pressure wave maximal amplitude were established in 15 prematures, 27 term newborns and 10 infants. Anterior fontanelle pressure monitoring was performed in 19 term newborns with post-asphyxial encephalopathy, 18 newborns and infants with hydrocephalus, 8 preterm and term newborns with respiratory distress and 19 patients with subdural haematomas, metabolic diseases, meningitis, subarachnoidal haemorrhage, head trauma, post cardiac arrest encephalopathy and abnormal head growth or bulging fontanelle. Abnormal patterns of anterior fontanelle pressure monitoring were found in moderate or severe neonatal post-asphyxial encephalopathy, evolutive hydrocephalus, subdural haematomas, metabolic diseases with hyperammoniemia and other clinical situations. In contrast, anterior fontanelle pressure monitoring yielded normal values in mild post-asphyxial encephalopathy, arrested hydrocephalus, well functioning ventriculo-peritoneal derivation, and in normal infants with rapid head growth or bulging fontanelle. The Rotterdam Teletransducer provides thus accurate and reproducible values of intracranial pressure. Anterior fontanelle pressure monitoring may be of value in many situations in clinical practice

Surface temperature measurement in the medium and long wavelength infrared range on MAST

19th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices (PSI), Univ Calif, Gen Atom, San Diego, CA, MAY 24-28, 2010International audienceExperiments and theoretical investigations of surface temperature measurement in the medium and long wavelength infrared range carried out on MAST show that a nonhomogenous surface temperature distribution due to the surface state (micro-metric hot-spots and/or surface roughness) can lead to a significant difference (up to similar to 40%) between both wavelengths. The over-estimation of the bulk temperature decreases with wavelength and the discrepancy observed on MAST can be reproduced using a hot-spot simulation model, by varying the dust size and the dust coverage such that a coverage of 0.2 parts per thousand with 1 mu m dust size which is consistent with the observations. The over-estimation of the bulk temperature is assessed at medium and long wavelength as a function of dust contribution (coverage/size). The effect is also assessed in different conditions (temperature of the bulk as well as the incident power flux). (C) 2010 Elsevier B.V. All rights reserved

Analysis of Xanthomonas oryzae pv. oryzicola Population in Mali and Burkina Faso Reveals a High Level of Genetic and Pathogenic Diversity

International audienceBacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola was first reported in Africa in the 1980s. Recently, a substantial reemergence of this disease was observed in West Africa. Samples were collected at various sites in five and three different rice-growing regions of Burkina Faso and Mali, respectively. Sixty-seven X. oryzae pv. oryzicola strains were isolated from cultivated and wild rice varieties and from weeds showing BLS symptoms. X. oryzae pv. oryzicola strains were evaluated for virulence on rice and showed high variation in lesion length on a susceptible cultivar. X. oryzae pv. oryzicola strains were further characterized by multilocus sequence analysis (MLSA) using six housekeeping genes. Inferred dendrograms clearly indicated different groups among X. oryzae pv. oryzicola strains. Restriction fragment length polymorphism analysis using the transcriptional activator like effector avrXa7 as probe resulted in the identification of 18 haplotypes. Polymerase chain reaction-based analyses of two conserved type III effector (T3E) genes (xopAJ and xopW) differentiated the strains into distinct groups, with xopAJ not detected in most African X. oryzae pv. oryzicola strains. XopAJ functionality was confirmed by leaf infiltration on ‘Kitaake’ rice Rxo1 lines. Sequence analysis of xopW revealed four groups among X. oryzae pv. oryzicola strains. Distribution of 43 T3E genes shows variation in a subset of X. oryzae pv. oryzicola strains. Together, our results show that African X. oryzae pv. oryzicola strains are diverse and rapidly evolving, with a group endemic to Africa and another one that may have evolved from an Asian strain

Analysis of Bordetella pertussis clinical isolates circulating in European countries during the period 1998-2012

Contains fulltext : 154133.pdf (publisher's version ) (Open Access)Despite more than 50 years of vaccination, pertussis is still an endemic disease, with regular epidemic outbreaks. With the exception of Poland, European countries have replaced whole-cell vaccines (WCVs) by acellular vaccines (ACVs) in the 1990s. Worldwide, antigenic divergence in vaccine antigens has been found between vaccine strains and circulating strains. In this work, 466 Bordetella pertussis isolates collected in the period 1998-2012 from 13 European countries were characterised by multi-locus antigen sequence typing (MAST) of the pertussis toxin promoter (ptxP) and of the genes coding for proteins used in the ACVs: pertussis toxin (Ptx), pertactin (Prn), type 2 fimbriae (Fim2) and type 3 fimbriae (Fim3). Isolates were further characterised by fimbrial serotyping, multi-locus variable-number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). The results showed a very similar B. pertussis population for 12 countries using ACVs, while Poland, which uses a WCV, was quite distinct, suggesting that ACVs and WCVs select for different B. pertussis populations. This study forms a baseline for future studies on the effect of vaccination programmes on B. pertussis populations