90 research outputs found

    Numerical Ways to Characterize the Deterioration of Nanofiltration Membranes

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    In this study, a transport model is used to characterize structural and physico-chemical changes in a nanofiltration membrane during the filtration of ionic mixtures. The membrane state is analyzed by a set of four model parameters identified from glucose and salts filtration: the membrane water permeability (Lp), the mean pore radius (rp), the membrane charge density (Xd), and the dielectric constant of the solution inside pores (ep). The study of these structural and physico-chemical properties allows us to determine if deterioration or fouling occurred during filtration. Two distinct identification procedures from filtration of synthetic solutions are investigated in this paper. One is based on the filtration of single salt solutions, whereas the other lies in parameters identification from mixtures containing at least three ions. These methods are applied here to characterize influence of fouling deposit formation and membrane cleaning

    A Cross-Sectional Study of Treatments for Behavioral Disorders Following Traumatic Brain Injury: Comparison With French Recommendations

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    OBJECTIVE: To give a cross-sectional overview of ongoing management of behavioral disorders following traumatic brain injury (TBI) in a region of France, to compare this with recent recommendations from the French Society of Physical Medicine and Rehabilitation (SOFMER), and to evaluate associations between treatments and participant characteristics. SETTING: Outpatients referred to medical or community-based facilities in a region of France. PARTICIPANTS: One hundred twenty-nine adults with moderate to severe TBI, in the postacute period (over 3 months postinjury). DESIGN: Cross-sectional cohort study. MAIN MEASURES: Sociodemographic data, ongoing interventions including psychotherapy and medication, behavioral disorders assessed by the Behavioral Dysexecutive Syndrome Inventory (BDSI). RESULTS: Thirty-three percent of participants received ongoing psychotherapy and 43% were on medication. The most prescribed medications were antidepressants (21%), neuroleptics (18%), anxiolytics (16%), and mood stabilizers (14%). Eighty-five participants (71%) presented a current Behavioral Dysexecutive Syndrome (BDS) according to the BDSI. These participants more frequently received treatment (P = .004), psychotherapy (P = .048), medications (often 2 or more) (P = .007), and particularly antiepileptic mood stabilizers (P = .037) compared with those without BDS. CONCLUSION: Although recommended as first-line treatment, few participants with BDS received psychotherapy. Medications were overused, especially neuroleptics in view of their potential adverse effects. In contrast, recommended medications, such as mood stabilizers and β-blockers, did not appear to be highly prescribed whatever the evolution. Compliance with recommendations seemed insufficient

    The Importance of the Stem Cell Marker Prominin-1/CD133 in the Uptake of Transferrin and in Iron Metabolism in Human Colon Cancer Caco-2 Cells

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    As the pentaspan stem cell marker CD133 was shown to bind cholesterol and to localize in plasma membrane protrusions, we investigated a possible function for CD133 in endocytosis. Using the CD133 siRNA knockdown strategy and non-differentiated human colon cancer Caco-2 cells that constitutively over-expressed CD133, we provide for the first time direct evidence for a role of CD133 in the intracellular accumulation of fluorescently labeled extracellular compounds. Assessed using AC133 monoclonal antibody, CD133 knockdown was shown to improve Alexa488-transferrin (Tf) uptake in Caco-2 cells but had no impact on FITC-dextran or FITC-cholera-toxin. Absence of effect of the CD133 knockdown on Tf recycling established a role for CD133 in inhibiting Tf endocytosis rather than in stimulating Tf exocytosis. Use of previously identified inhibitors of known endocytic pathways and the positive impact of CD133 knockdown on cellular uptake of clathrin-endocytosed synthetic lipid nanocapsules supported that CD133 impact on endocytosis was primarily ascribed to the clathrin pathway. Also, cholesterol extraction with methyl-β-cyclodextrine up regulated Tf uptake at greater intensity in the CD133high situation than in the CD133low situation, thus suggesting a role for cholesterol in the inhibitory effect of CD133 on endocytosis. Interestingly, cell treatment with the AC133 antibody down regulated Tf uptake, thus demonstrating that direct extracellular binding to CD133 could affect endocytosis. Moreover, flow cytometry and confocal microscopy established that down regulation of CD133 improved the accessibility to the TfR from the extracellular space, providing a mechanism by which CD133 inhibited Tf uptake. As Tf is involved in supplying iron to the cell, effects of iron supplementation and deprivation on CD133/AC133 expression were investigated. Both demonstrated a dose-dependent down regulation here discussed to the light of transcriptional and post-transciptional effects. Taken together, these data extend our knowledge of the function of CD133 and underline the interest of further exploring the CD133-Tf-iron network

    Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties

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    BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classesbeingfoundinseveral fractions. Peptides containing Pro, Hyp, Aspand Gluwere concentrated in the UF and NFretentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin-likepeptideswerepresent in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene-related peptide (CGRP)-like peptides demonstrated an increase in CGRP-like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin-converting enzyme (ACE)-1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut-off adapted to the peptide composition, may provide an effective means to concentrate CGRP-like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut-off of the membrane only, as is currently done in the literature. © 2010 Society of Chemical Industry.Peer Reviewe
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