Removal of heavy metals from wastewater using magnetic nanocomposites: Analysis of the experimental conditions

This contribution provides insight on the elimination of heavy metals from water resources using magnetic separation. Nanocomposites based on magnetite and chitosan were prepared. An exhaustive characterization of the magnetic adsorbents was developed. Adsorption assays were performed in batch using Cu, Zn, Cd, and Cr as model heavy metals. The efficiency of magnetic adsorbents followed the order: Cu > Cd > Zn > Cr, with maximum values of 188, 159, 72, and 46 mg of Me/g of nanocomposite, respectively. Kinetics and mechanistic issues were studied. The magnetic materials were efficient for five to eight cycles using Cu(II),Cd(II), and Cr(VI).     

Measurements of the behavioral effects of albino mutation in mice (Mus musculus): Comparisons of coisogenic inbred and hybrid lines.

The effects of the albino gene on mouse behavior were examined, particularly its possible interactions with nonallelic genes (epistasis). More generally, the possible effects of genetic background (inbreeding depression or hybrid vigor) on the effects of the mutation were also considered. Tasks requiring either predominantly motor or predominantly cognitive capacity were studied for coisogenic albino and pigmented mice from either an inbred strain (C57BL/6 c/c vs C57BL/6 +/c) or an F? heterozygous generation (F? c/c vs F? +/c) from a BALB/c?×?C57BL/6 +/c cross. Results show a clear albino gene effect in the 2 lines and provide further evidence that the gene is the effective factor. There was no significant interaction between the mutation and the genotypic group (C57BL/6 or F?), which indicates that the effects of the mutation act approximately in an additive fashion between loci in these groups. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implication of scavenger receptors in the interactions between diesel exhaust particles and immature or mature dendritic cells

Background  

The exposure to pollutants such as diesel exhaust particles (DEP) is associated with an increased incidence of respiratory diseases. However, the mechanisms by which DEP have an effect on human health are not completely understood. In addition to their action on macrophages and airway epithelial cells, DEP also modulate the functions of dendritic cells (DC). These professional antigen-presenting cells are able to discriminate unmodified self from non-self thanks to pattern recognition receptors such as the Toll like Receptors (TLR) and Scavenger Receptors (SR). SR were originally identified by their ability to bind and internalize modified lipoproteins and microorganisms but also particles and TLR agonists. In this study, we assessed the implication of SR in the effects of DEP associated or not with TLR agonists on monocyte-derived DC (MDDC). For this, we studied the regulation of CD36, CXCL16, LOX-1, SR-A1 and SR-B1 expression on MDDC treated with DEP associated or not with TLR2, 3 and 4 ligands. Then, the capacity of SR ligands (dextran sulfate and maleylated-ovalbumin) to block the effects of DEP on the function of lipopolysaccharide (LPS)-activated DC has been evaluated.     

Inhibitory activity of loratadine and descarboxyethoxyloratadine on histamine-induced activation of endothelial cells

BACKGROUND: The allergic inflammatory reaction is characterized by leucocyte adherence and infiltration processes which are controlled by the expression of adhesion molecules on the surface of vascular endothelium. One of the main mediators implicated in allergic reactions is represented by histamine. Histamine is a potent activator of endothelial cells (EC): it induces the expression of P-selectin on the surface of endothelium and the secretion of IL-6 and IL-8. OBJECTIVES: Loratadine (L), a histamine H1-antagonist, and one of its active metabolites, descarboxyethoxyloratadine (DCL), were studied at different concentrations for their ability to reduce the histamine-induced activation of human umbilical vein EC (HUVEC). METHODS: HUVEC were stimulated in the presence of histamine at 10(-6) M, 10(-5) M and 10(-4) M. We assessed by ELISA the expression of P-selectin on EC surface, as well as cytokine production in EC supernatants of 24 h culture. RESULTS: Our results showed that for a 10(-4) M-histamine stimulation, L and DCL have a similar inhibitory effect on P-selectin expression (IC50 = 13 x 10[-9] M and 23 x 10[-9] M, respectively). L and DCL inhibited significantly IL-6 and IL-8 secretion induced by histamine with a more powerful efficiency of the active metabolite. For the dose of 10(-4) M histamine, a 50% inhibition of IL-6 secretion was obtained for a dose of DCL equal to 2.6 x 10(-12) M whereas the same magnitude of effects were only reached for a higher concentration of L (0.3 x 10[-6] M). Similar results were obtained for IL-8 (IC50 = 0.2 x 10[-6] M for L and 10[-9] M for DCL). Analysis of IL-8 mRNA expression by RT-PCR was in accordance with these data. CONCLUSION: These results demonstrate that both L and DCL are active to reduce the histamine-induced activation of EC. Interestingly, DCL seems to be effective at lesser concentrations especially to inhibit cytokine secretion.     

Unfolding of the tetrameric loop deletion mutant of ROP protein is a second-order reaction

Comprehensive kinetic studies were carried out on the unfolding properties of RM6 as a function of GdnHCl concentration and temperature. This protein is a mutant resulting from the dimeric wild-type CoLE1-ROP protein by deletion of 5 amino acids (Asp 30, Ala 31, Asp 32, Glu 33, Gln 34) in the loop of each monomer. The deletion has dramatic consequences. The dimeric 4-alpha-helix structure characteristic of the wild-type protein is completely reorganized and the RM6 structure can be described as a tetrameric alpha helix of extended monomers without loops. These extraordinary structural changes are accompanied by an enormous increase in transition temperature from 71 to 101 degreesC. These features have been discussed in a separate publication (1). The remarkable change in thermal stability of RM6 should be reflected in significant changes in the folding rate constants. This was observed in the present unfolding studies. Decay of tetrameric RM6 was monitored by circular dichroism (CD) and fluorescence to probe for changes in both secondary and tertiary structure, respectively. The identity of the kinetic parameters obtained from the two techniques supports the view that secondary and tertiary structure break down simultaneously. However, the most intriguing result is the finding that unfolding of tetrameric RM6 can be described very well by a second-order reaction. The magnitude of the second-order rate constant k2 varies dramatically with both temperature and denaturant concentration. At 25 degreesC and 6.5 M GdnHCl concentration k2 is 4200 L.(mol of dimer)-1.s-1, whereas at 4.4 M GdnHCl a value of k2 = 0.9 L.(mol of dimer)-1.s-1 is observed. Correspondingly, apparent activation enthalpies show a strong increase from DeltaH# = 29.1 kJ.mol-1 at 6. 5 M GdnHCl to Delta H# = 79.7 kJ.mol-1 at 4.4 M GdnHCl. A mechanism involving a dimeric intermediate is suggested which permits a consistent interpretation of the findings.     

Circulating Monocyte Subsets and Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR), as an alternative to open heart surgery, has revolutionized the treatment of severe aortic valve stenosis (AVS), the most common valvular disorder in the elderly. AVS is now considered a form of atherosclerosis and, like the latter, partly of inflammatory origin. Patients with high-grade AVS have a highly disturbed blood flow associated with high levels of shear stress. The immediate reopening of the valve during TAVR leads to a sudden restoration of a normal blood flow hemodynamic. Despite its good prognosis for patients, TAVR remains associated with bleeding or thrombotic postprocedural complications, involving mechanisms that are still poorly understood. Many studies report the close link between blood coagulation and inflammation, termed thromboinflammation, including monocytes as a major actor. The TAVR procedure represents a unique opportunity to study the influence of shear stress on human monocytes, key mediators of inflammation and hemostasis processes. The purpose of this study was to conduct a review of the literature to provide a comprehensive overview of the impact of TAVR on monocyte phenotype and subset repartition and the association of these parameters with the clinical outcomes of patients with severe AVS who underwent TAVR.     

PD-L1 Expression in 65 Conjunctival Melanomas and Its Association with Clinical Outcome

Conjunctival melanoma (CM) iss a rare and aggressive tumour that is increasing in frequency. The prognostic value of PD-L1 expression, alone or in combination with CD8 and PD-1 expression and the BRAF and NRAS status, has not been determined in CM to date. We evaluated the expression of PD-L1, CD8, PD-1 in CM and investigated whether there was an association between the expression of these markers and the BRAF and NRAS molecular profile as well as some clinico-pathological criteria. A total of sixty-five CM were assessed for PD-L1, PD-1, and CD8 expression by immunohistochemistry (IHC) and for BRAF and NRAS genomic alterations using molecular biology techniques and anti-BRAF and anti-NRAS antibodies. PD-L1 expression in tumour cells (TC) was very low or absent but detected in tumour-infiltrating immune cells (IC). A correlation was observed between the expression of PD-L1, CD8, and PD-1 in IC. No correlation between PD-L1 expression (in tumour and/or immune cells) and BRAF or NRAS mutations was observed. PD-L1 expression in IC correlated with a higher pTNM stage and PD-L1 expression in TC with worse disease-specific survival. PD-L1 expression is a potential prognostic biomarker that correlates with poor prognosis in CM patients.     

Ségrégation externe des bétons frais: Modèle expérimental et influence des principaus facteurs

Résumé Un modéle expérimental de ségrégation externe a sété mis au point; il consiste à faire suivre à un seul granulat noyé dans une pate de ciment un trajet rectiligne à vitesse constante. On mesure simultanément la force nécessaire pour produire ce mouvement, en particulier au moment où le granulat s’extrait de la pate. Pour des pates à concentration en ciment usuelles (γ>0,530) l’extraction du granulat s’effectue par création d’une colonne de pate adhérente à ce dernier, la rupture intervenant toujours par traction dans la colonne elle-même. La force nécessaire pour extraire un granulat de la pate (force d’extraction ΔF_ex) s’exprime simplement par la relation: ΔF_ex = mSσ_t, avec: S: aire de la section diamétrale du granulat: σ_t: résistance à la traction de la pate de ciment fraiche: m: coefficient de conraction indépendant de la concentration en solide de la pate et de la dimension du granulat.

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Summary An experimental model of external segregation has been devised. It consists of making a single aggregate grain embedded in cement paste follow a rectilinear path at constant rate. Simultaneous measurement is taken of the force necessary to produce this movement, particularly at the moment when the grain energy emerges from the paste. For paste with normal cement content (ψ>0.530) the extraction of the grain is activated by the formation of a column of paste bonded to the grain, rupture always being caused by tension in the column itself. The force necessary to extract a grain from the paste (extraction force ΔF_ex) is simply expressed by the equation: ΔF_ex = mSσ_t, with: S: area of the diametral section of the grain; σ_t: tensile strength of fresh cement paste; m: contraction coefficient independent of the solid concentration of the paste and of the grain size.

     

Lectins binding on human sperm surface increase membrane permeability and stimulate acrosomal exocytosis

Cross-linked complexes formed between certain lectins and their specific multivalent carbohydrates and glycoconjugates on the sperm surface were studied for their ability to modify sperm membrane permeability and to induce the acrosome reaction. Wheat germ agglutinin (WGA), concanavalin A (Con A) and peanut agglutinin (PNA) increased the proportions of human spermatozoa permeable to the impermeable propidium iodide (31.9 compared with 13.8%, 38.4 compared with 18.4% and 72.7 compared with 18.9% respectively). Removal of sperm surface sialic acid by neuraminidase treatment was a prerequisite for Con A and PNA binding to the sperm surface. The percentage of permeable and acrosome-reacted spermatozoa was not affected by sperm treatment with 500 mIU/ml Arthrobacter ureafaciens neuraminidase. WGA did not induce the acrosome reaction, whereas PNA induced the acrosome reaction regardless of the sperm capacitation status, allowing the proportion of acrosome-reacted spermatozoa to reach 27.7% of capacitated spermatozoa. However, the ability of Con A to induce the acrosome reaction was limited to uncapacitated spermatozoa. To test the physiological relevance of this study, uncapacitated human spermatozoa were incubated with human zonae pellucidae and the permeability of spermatozoa bound to the zona surface was analysed according to the time post-insemination. Two-thirds of spermatozoa bound to zona pellucida became permeable to propidium iodide in the first 30 min post-insemination and almost all bound spermatozoa became permeable to the impermeable dye after 60 min. Our results show that molecular interactions between human zona pellucida and sperm surface increase the permeability of sperm membranes; the cross-linked complexes formed by PNA lectin and its specific multivalent carbohydrates and glycoconjugates on the sperm surface were also able to increase sperm membrane permeability and to induce the acrosome reaction. These results suggest a role for the saccharide moieties of sperm surface glycoconjugates in the induction of the acrosome reaction.     

COmmunication and WORKload analyses to study the COllective WORK of fighter pilots: the COWORK2 method

Cognition, Technology & Work - This paper presents the COWORK2 method, designed to classify the collective tasks of a fighter jet patrol according to two classification criteria: mental...