Electrochemical preparation of peroxodisulfuric acid using boron doped diamond thin film electrodes

We have investigated the electrochemical oxidation of sulfuric acid on boron-doped synthetic diamond electrodes (BDD) obtained by HF CVD on p-Si. The results have shown that high current efficiency for sulfuric acid oxidation to peroxodisulfuric acid can be achieved in concentrated H2SO4 (>2 M) at moderate temperatures (8–10 °C). The main side reaction is oxygen evolution. Small amounts of peroxomonosulfuric acid (Caro's acid) have also been detected. A reaction mechanism involving hydroxyl radicals, HSO4− and undissociated H2SO4 has been proposed. According to this mechanism electrogenerated hydroxyl radicals at the BDD anode react with HSO4− and H2SO4 giving peroxodisulfate

Synthesis, metal complexation and biological evaluation of a novel semi-rigid bifunctional chelating agent for 99mTc labelling

A novel bifunctional chelating agent bearing an aromatic ring has been synthesised and characterised. This ligand formed well-defined oxorhenium complexes. The analogous 99mTcO-complex was obtained in an excellent yield with high radiochemical purity (>95%). The biodistribution of the 99mTo-complex after intravenous injection studied in normal rats showed that the activity was excreted mainly via renal-urinary pathway indicating its use for labelling peptides with 99mTc

Correlations between electrochemical behaviors and DNA photooxidative properties of non-steroïdal anti-inflammatory drugs and their photoproducts

Alkali-labile lesion to DNA photosensitized, via an electron transfer mechanism, by three non-steroidalanti-inflammatorydrugs (NSAIDs), ketoprofen, tiaprofenic acid and naproxen and their photoproducts during drug photolysis, was investigated using 32P-end labelled synthetic oligonucleotide. These photooxidative damages were correlated with the photophysical and electrochemicalproperties of drugs, appearing as the photosensitizer PS. Photophysical studies provided the excited state energies of the photosensitizer while their redox potentials and the relative stabilities of the PSradical dot− radical-anions were determined by cyclic voltammetry. On the basis of these data, we have calculated the Gibbs energy of photoinduced electron-transfer and evaluated the exergonicity of the oxidative photodamage. Moreover, kinetic control may be invoked according to the stabilities of PSradical dot−. Applied to this NSAIDs family, the photoxidative damages through electron transfer mechanism were analyzed and a good correlation with photoredox and photobiological properties was established

Comparison of the Transmembrane Mucins MUC1 and MUC16 in Epithelial Barrier Function

Membrane-anchored mucins are present in the apical surface glycocalyx of mucosal epithelial cells, each mucosal epithelium having at least two of the mucins. The mucins have been ascribed barrier functions, but direct comparisons of their functions within the same epithelium have not been done. In an epithelial cell line that expresses the membrane-anchored mucins, MUC1 and MUC16, the mucins were independently and stably knocked down using shRNA. Barrier functions tested included dye penetrance, bacterial adherence and invasion, transepithelial resistance, tight junction formation, and apical surface size. Knockdown of MUC16 decreased all barrier functions tested, causing increased dye penetrance and bacterial invasion, decreased transepithelial resistance, surprisingly, disruption of tight junctions, and greater apical surface cell area. Knockdown of MUC1 did not decrease barrier function, in fact, barrier to dye penetrance and bacterial invasion increased significantly. These data suggest that barrier functions of membrane-anchored mucins vary in the context of other membrane mucins, and MUC16 provides a major barrier when present

F.A.R.O.G. FORUM, Vol. 2 No. 1

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F.A.R.O.G. FORUM, Vol. 2 No. 4

https://digitalcommons.library.umaine.edu/francoamericain_forum/1003/thumbnail.jp

GW182-Free microRNA Silencing Complex Controls Post-transcriptional Gene Expression during Caenorhabditis elegans Embryogenesis

MicroRNAs and Argonaute form the microRNA induced silencing complex or miRISC that recruits GW182, causing mRNA degradation and/or translational repression. Despite the clear conservation and molecular significance, it is unknown if miRISC-GW182 interaction is essential for gene silencing during animal development. Using Caenorhabditis elegans to explore this question, we examined the relationship and effect on gene silencing between the GW182 orthologs, AIN-1 and AIN-2, and the microRNA-specific Argonaute, ALG-1. Homology modeling based on human Argonaute structures indicated that ALG-1 possesses conserved Tryptophan-binding Pockets required for GW182 binding. We show in vitro and in vivo that their mutations severely altered the association with AIN-1 and AIN-2. ALG-1 tryptophan-binding pockets mutant animals retained microRNA-binding and processing ability, but were deficient in reporter silencing activity. Interestingly, the ALG-1 tryptophan-binding pockets mutant phenocopied the loss of alg-1 in worms during larval stages, yet was sufficient to rescue embryonic lethality, indicating the dispensability of AINs association with the miRISC at this developmental stage. The dispensability of AINs in miRNA regulation is further demonstrated by the capacity of ALG-1 tryptophan-binding pockets mutant to regulate a target of the embryonic mir-35 microRNA family. Thus, our results demonstrate that the microRNA pathway can act independently of GW182 proteins during C. elegans embryogenesis

Release of Membrane-Associated Mucins from Ocular Surface Epithelia

PURPOSE. Three membrane-associated mucins (MAMs)-MUC1, MUC4, and MUC16 -are expressed at the ocular surface epithelium. Soluble forms of MAMs are detected in human tears, but the mechanisms of their release from the apical cells are unknown. The purpose of this study was to identify physiologic agents that induce ocular surface MAM release. METHODS. An immortalized human corneal-limbal epithelial cell line (HCLE) expressing the same MAMs as native tissue was used. An antibody specific to the MUC16 cytoplasmic tail was developed to confirm that only the extracellular domain is released into the tear fluid or culture media. Effects of agents that have been shown to be present in tears or are implicated in the release or shedding of MAMs in other epithelia (neutrophil elastase, tumor necrosis factor [TNF]), TNF-␣-converting enzyme, and matrix metalloproteinase-7 and -9) were assessed on HCLE cells. HCLE cell surface proteins were biotinylated to measure the efficiency of induced MAM release and surface restoration. Effects of induced release on surface barrier function were measured by rose bengal dye penetrance. RESULTS. MUC16 in tears and in HCLE-conditioned medium lacked the cytoplasmic tail. TNF induced the release of MUC1, MUC4, and MUC16 from the HCLE surface. Matrix metalloproteinase-7 and neutrophil elastase induced the release of MUC16 but not of MUC1 or MUC4. Neutrophil elastase removed 68% of MUC16, 78% of which was restored to the HCLE cell surface 24 hours after release. Neutrophil elastase-treated HCLE cells showed significantly reduced rose bengal dye exclusion. CONCLUSIONS. Results suggest that the extracellular domains of MUC1, MUC4, and MUC16 can be released from the ocular surface by agents in tears. Neutrophil elastase and TNF, present in higher amounts in the tears of patients with dry eye, may cause MAM release, allowing rose bengal staining. (Invest Ophthalmol Vis Sci

F.A.R.O.G. FORUM Vol. 2, No. 2

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Suppression of Toll-like Receptor-Mediated Innate Immune Responses at the Ocular Surface by the Membrane-associated Mucins MUC1 and MUC16

Membrane-associated mucins (MAMs) expressed on the ocular surface epithelium form a dense glycocalyx, which is hypothesized to protect the cornea and conjunctiva from external insult. In this study, the hypothesis that the MAMs MUC1 and MUC16, expressed on the apical surface of the corneal epithelium, suppress Toll-like receptor (TLR)-mediated innate immune responses was tested. Using an in vitro model of corneal epithelial cells that are cultured to express MAMs, we show that reduced expression of either MUC1 or MUC16 correlates with increased message and secreted protein levels of the proinflammatory cytokines IL-6, IL-8, and TNF-α following exposure of cells to the TLR2 and TLR5 agonists, heat killed Listeria monocytogenes and flagellin, respectively. Since mice express MUC1 (but not MUC16) in the corneal epithelium, a Muc1-/- mouse model was used to extend in vitro findings. Indeed, IL-6 and TNF-α message levels were increased in the corneal epithelium of Muc1-/- mice, in comparison to wild type mice, following exposure of enucleated eyes to the TLR2 and TLR5 agonists. Our results suggest that the MAMs MUC1 and MUC16 contribute to the maintenance of immune homeostasis at the ocular surface by limiting TLR-mediated innate immune responses