Cryptosporidium spp. , Giardia duodenalis and Toxoplasma gondii detection in fresh vegetables consumed in Marrakech, Morocco

Background: Protozoan parasites such as Toxoplasma gondii, Giardia duodenalis, and Cryptosporidium spp., can be transmitted to humans via accidental consumption of contaminated water, fresh produce and foodstuffs. There is a lack of epidemiological data about these pathogens in Morocco. Hence the aim of this study, which is the determination of their prevalence in some leafy greens and root vegetables sold in Marrakech. Methods: A total of 132 vegetable samples including carrot, coriander, lettuce, parsley and radish were purchased monthly from three different markets in Marrakech from March 2017 to January 2018, pre-treated and subjected to microscopic and molecular analyses. Results: Of the 132 samples of vegetables analyzed by qPCR, the overall rate of protozoan was 21.21% (28/132); 22 samples were found to be contaminated with T. gondii, 6 with G. duodenalis, and none was positive for C. parvum / hominis . Whereas, modified Ziehl-Neelsen staining allowed the detection of Cryptosporidium spp. in 3% (4/132) of examined samples. Conclusion: This survey on the presence of protozoan parasites in fresh vegetables revealed that vegetables sold in Marrakech are contaminated by these protozoan parasites, as it showed that leafy green vegetables were more susceptible for parasitic contamination than root ones

Anatomical distribution of Toxoplasma gondii in naturally and experimentally infected lambs

Consumption of raw or undercooked meat containing Toxoplasma gondii tissue cysts is one of the main sources of infection for humans worldwide. Among the various species intended for human consumption, sheep appear to be a high risk for human infection. The present study focused on the detailed anatomical distribution of Toxoplasma gondii in naturally and experimentally infected lambs using fresh and frozen samples of various pieces of meat, from a public health perspective. The first objective was to rank the edible parts intended for human consumption according to the detectable parasite burden by real-time PCR targeting the 529-bp repeated element. The second objective was to evaluate the impact of freezing by comparing the detection efficiency of the quantitative PCR between fresh and frozen tissues, as imports of lamb carcasses/cuts may arrive frozen or chilled. The highest estimated parasite loads were observed in skeletal muscles, and more particularly in edible portions such as quadriceps femoris muscle, intercostal muscles, deltoid muscle and diaphragm, with a significant difference in detectable parasite burden between fresh and frozen samples (p < 0.0001) or natural and experimental infection (p < 0.0001). Thoracic and pelvic limbs (3278–1048 parasites/g muscle) were ranked at the top of the list. Toxoplasma gondii DNA was detected in all the edible parts of lamb studied. These results suggest that lamb meat represents a risk for consumers. Further investigations are needed in order to confirm these differences in larger numbers of animals and in different breeds

Relation of exaggerated cytokine responses of CF airway epithelial cells to PAO1 adherence

In many model systems, cystic fibrosis (CF) phenotype airway epithelial cells in culture respond to P. aeruginosa with greater interleukin (IL)-8 and IL-6 secretion than matched controls. In order to test whether this excess inflammatory response results from the reported increased adherence of P. aeruginosa to the CF cells, we compared the inflammatory response of matched pairs of CF and non CF airway epithelial cell lines to the binding of GFP-PAO1, a strain of pseudomonas labeled with green fluorescent protein. There was no clear relation between GFP-PAO1 binding and cytokine production in response to PAO1. Treatment with exogenous aGM1 resulted in greater GFP-PAO1 binding to the normal phenotype compared to CF phenotype cells, but cytokine production remained greater from the CF cell lines. When cells were treated with neuraminidase, PAO1 adherence was equalized between CF and nonCF phenotype cell lines, but IL-8 production in response to inflammatory stimuli was still greater in CF phenotype cells. The polarized cell lines 16HBEo-Sense (normal phenotype) and Antisense (CF phenotype) cells were used to test the effect of disrupting tight junctions, which allows access of PAO1 to basolateral binding sites in both cell lines. IL-8 production increased from CF, but not normal, cells. These data indicate that increased bacterial binding to CF phenotype cells cannot by itself account for excess cytokine production in CF airway epithelial cells, encourage investigation of alternative hypotheses, and signal caution for therapeutic strategies proposed for CF that include disruption of tight junctions in the face of pseudomonas infection

Staphylococcus aureus enterotoxins induce IL-8 secretion by human nasal epithelial cells

BACKGROUND: Staphylococcus aureus produces a set of proteins which act both as superantigens and toxins. Although their mode of action as superantigens is well understood, little is known about their effects on airway epithelial cells. METHODS: To investigate this problem, primary nasal epithelial cells derived from normal and asthmatic subjects were stimulated with staphylococcal enterotoxin A and B (SEA and SEB) and secreted (supernatants) and cell-associated (cell lysates) IL-8, TNF-α, RANTES and eotaxin were determined by specific ELISAs. RESULTS: Non-toxic concentrations of SEA and SEB (0.01 μg/ml and 1.0 μg/ml) induced IL-8 secretion after 24 h of culture. Pre-treatment of the cells with IFN-γ (50 IU/ml) resulted in a further increase of IL-8 secretion. In cells from healthy donors pretreated with IFN-γ, SEA at 1.0 μg/ml induced release of 1009 pg/ml IL-8 (733.0–1216 pg/ml, median (range)) while in cells from asthmatic donors the same treatment induced significantly higher IL-8 secretion – 1550 pg/ml (1168.0–2000.0 pg/ml p = 0.04). Normal cells pre-treated with IFN-γ and then cultured with SEB at 1.0 μg/ml released 904.6 pg/ml IL-8 (666.5–1169.0 pg/ml). Cells from asthmatics treated in the same way produced significantly higher amounts of IL-8 – 1665.0 pg/ml (1168.0–2000.0 pg/ml, p = 0.01). Blocking antibodies to MHC class II molecules added to cultures stimulated with SEA and SEB, reduced IL-8 secretion by about 40% in IFN-γ unstimulated cultures and 75% in IFN-γ stimulated cultures. No secretion of TNF-α, RANTES and eotaxin was noted. CONCLUSION: Staphylococcal enterotoxins may have a role in the pathogenesis of asthma

Mechanisms of the noxious inflammatory cycle in cystic fibrosis

Multiple evidences indicate that inflammation is an event occurring prior to infection in patients with cystic fibrosis. The self-perpetuating inflammatory cycle may play a pathogenic part in this disease. The role of the NF-κB pathway in enhanced production of inflammatory mediators is well documented. The pathophysiologic mechanisms through which the intrinsic inflammatory response develops remain unclear. The unfolded mutated protein cystic fibrosis transmembrane conductance regulator (CFTRΔF508), accounting for this pathology, is retained in the endoplasmic reticulum (ER), induces a stress, and modifies calcium homeostasis. Furthermore, CFTR is implicated in the transport of glutathione, the major antioxidant element in cells. CFTR mutations can alter redox homeostasis and induce an oxidative stress. The disturbance of the redox balance may evoke NF-κB activation and, in addition, promote apoptosis. In this review, we examine the hypotheses of the integrated pathogenic processes leading to the intrinsic inflammatory response in cystic fibrosis

Ka-band Coplanar Low-Noise Amplifier Design with Power PHEMTs

The design of a coplanar low-noise amplifier (LNA)is presented in this paper.Pseudomorphic high electron mobility transistors (PHEMTs),optimized for power applications,are used in order to evaluate the potentiality of this technology for mixed-mode applications. The three stages amplifier noise figure is lower than 2.6 dB on the 27 -31 GHz frequency band with a 20 dB power gain

Small-signal model extraction technique dedicated to noise behaviour of microwave HBTs

A complete on-wafer heterojunction bipolar transistors (HBTs) equivalent circuit parameters extraction technique is presented. It is based on the successive extraction of extrinsic and intrinsic elements. An improved method for parasitic inductance values determination is proposed. It results in a more accurate modelling of HBTs which is shown to be very useful especially for high frequency noise parameter modelling

Charges froides actives pour le calibrage des radiomètres micro-ondes utilisés pour l’observation de la Terre

Nous présentons dans ce papier une synthèse concernant la réalisation de charges froides actives à partir d’un transistor micro onde. Le but de celle-ci est de fournir une source de référence pour les radiomètres qui présentent une faible température de bruit tout en fonctionnant à température ambiante. Une présentation des différentes topologies des circuits et des technologies employées est effectuée. Les techniques de caractérisation sont présentées et notamment celles que l’on rencontre pour mesurer la stabilité de ces sources. Les architectures des radiomètres utilisés et les outils d’analyse sont abordés. L’état de l’art effectué montre qu’il est possible d’obtenir des températures de bruit inférieures à 100 K jusqu’à une vingtaine de GHz avec ce type de charge. La sensibilité aux variations de la température ambiante est comprise entre 0.3 et 0.4 K/°C et la stabilité sur le long terme est inférieure à 2 K/an.Mots clés : Charge froide active – Radiométrie micro onde – Calibrage – Radiomètres – Température de brui

Application of the TRL calibration technique for HEMT's microwave characterization at temperatures down to 77 K.

For the possible application to the cryogenically cooled low noise HEMT amplifier, this paper presents scattering parameter measurements of a HEMT chip at room and liquid nitrogen temperatures and in the 1-20 GHz frequency range. The measurement method which uses the well known TRL calibration technique will be fully discussed. S parameters and noise parameters measured at room temperature by means of this technique have been used to design a single stage low noise amplifier for the K band. Without any tuning this amplifier has an overall noise figure value of 1.6 dB with a 7 dB associated gain at 18 GHz which is in good agreements with predictions

Nouveau modele electrique de transistor a effet de champ millimetrique : application a la conception d'amplificateurs bas niveau 18-40 GHz

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc