Role of ascorbate in lung cellular toxicity mediated by light-exposed parenteral nutrition solution

Neonatal lung injury has been induced experimentally by infusion of multivitamin-containing light-exposed parenteral nutrition (PN) solutions. The objective was to explore the role of ascorbate in toxic effects of light-exposed PN on primary cultured foetal rat lung epithelial cells. Hydroperoxides were measured in 3% amino acid solutions at baseline, immediately after addition of either multivitamins or ascorbate alone (400 μg/mL) and again after a 24-h period of exposure to (or protection from) ambient light. Cellular toxicity was assessed by [C(14)]adenine release. Multivitamins or ascorbate alone increased hydroperoxides in PN, which was attenuated by light protection. Light-exposed PN containing multivitamins was more toxic to cells than baseline or light-protected PN. Exposure to ascorbate at concentrations both lower (< 5 μg/mL) and higher (> 1000 μg/mL) than normally contained in PN-induced oxidant-mediated cell death, as indicated by protective effects of hydroperoxide and hydroxyl radical scavengers. This study concludes that ascorbate generates toxic amounts of peroxide in PN solutions. The types and physiological importance of hydroperoxides induced by pro-oxidant effects of ascorbate require further evaluation in vivo.     

Melting temperature of surface-tethered DNA

A method for the accurate determination of the melting temperature (T_m) of surface-immobilized DNA duplexes that exploits the fluorescence-quenching properties of gold is reported. A thiolated single-stranded DNA probe is chemisorbed onto a gold surface and then hybridized to a fluorophore-labeled complementary sequence. On formation of the duplex, the fluorescence of the label is effectively quenched by the gold surface. As the temperature is increased and the duplex denatures, the fluorophore label moves away from the gold surface and the fluorescence signal is again observed. The increase in fluorescence is measured as the temperature is ramped, and using first-derivative plots, the T_m is determined. To demonstrate the approach, the T_m of the cystic fibrosis DF508 mutation was determined in three different phases: in solution, in suspension immobilized on gold nanoparticles, and immobilized on gold film-coated substrate. The technique was further applied to optimize conditions for differentiation between a surface-immobilized DF508 mutant probe and a mutant/wild-type target exploiting increasing stringency in varying salt and formamide concentrations. The approach has application in optimization of assay conditions for biosensors that use gold substrates as well as in melting curve analysis.     

Extracts of Feijoa Inhibit Toll-Like Receptor 2 Signaling and Activate Autophagy Implicating a Role in Dietary Control of IBD

Background

Inflammatory bowel disease (IBD) is a heterogeneous chronic inflammatory disease affecting the gut with limited treatment success for its sufferers. This suggests the need for better understanding of the different subtypes of the disease as well as nutritional interventions to compliment current treatments. In this study we assess the ability of a hydrophilic feijoa fraction (F3) to modulate autophagy a process known to regulate inflammation, via TLR2 using IBD cell lines.

Method

Mouse embryonic fibroblasts (MEF) deleted for ATG5, and two intestinal epithelial cells HCT15 and HCT116, were used to test the anti-inflammatory effect of F3 after stimulating the cells with a TLR2 specific ligand PAM3CSK4.

Results

F3 was able to reduce TLR2 specific inflammation and stimulate autophagy in MEFs and HCT15 cells but not in HCT116 cells. The anti-inflammatory effect was reduced in the MEF cells deleted for ATG5. In addition, the activation of autophagy by F3 was enhanced by PAM3CSK4.

Conclusion

F3 of feijoa can interact with cells via a TLR2 specific mechanism and reduce Nuclear factor kappa B (NF-κB) activation in part due to stimulation of autophagy. These results suggest that there is potential benefit in using feijoa extracts as part of dietary interventions to manage IBD in patients.     

Leukemia inhibitory factor: Role in human mesenchymal stem cells mediated immunosuppression

The interactions between mesenchymal stem cells (MSCs) and immune system are currently being explored. Leukemia inhibitory factor (LIF) is linked to regulatory transplantation tolerance. Our aim was to study the expression of LIF on human MSCs at both gene and protein level in mixed lymphocyte reaction (MSC/MLR), and its implication in MSC immunosuppressive effect. There was a 7-fold increase (611pg/ml) in LIF in MSC/MLR as compared to MSCs alone. Using LIF neutralizing antibody, a significant restoration of up to 91% of CD3+ lymphocyte proliferation in MSC/MLR was observed (p=0.021). LIF was implicated in the generation of regulatory lymphocytes, as demonstrated by decrease of Foxp3+ regulatory cells after using LIF neutralizing antibody in MSC/MLR (p=0.06) by flow cytometry. A positive correlation between LIF and human leukocyte antigen (HLA-G) gene expression by MSCs was found (R(2)=0.74). Our findings provide evidence supporting the immunomodulatory effect of MSCs.     

Antibiofilm activity of a lytic Salmonella phage on different Salmonella enterica serovars isolated from broiler farms

International Microbiology - Bacteriophages have been mainly used in treating infections caused by planktonic bacterial cells in the veterinary sector. However, their...     

Synthesis,Cytotoxicity Evaluation,and Molecular Docking Studies of Novel Pyrrole Derivatives of Khellin and Visnagin via One-Pot Condensation Reaction with Curcumin

Russian Journal of Bioorganic Chemistry - Novel pyrrole derivatives were synthesized by one-pot four components condensation reaction of khellin and/or visnagin carbaldehyde; amine derivatives;...     

Shared requirements for key residues in the antibiotic resistance enzymes ErmC and ErmE suggest a common mode of RNA recognition

Erythromycin-resistance methyltransferases are SAM dependent Rossmann fold methyltransferases that convert A2058 of 23S rRNA to m⁶ ₂A2058. This modification sterically blocks binding of several classes of antibiotics to 23S rRNA, resulting in a multidrug-resistant phenotype in bacteria expressing the enzyme. ErmC is an erythromycin resistance methyltransferase found in many Gram-positive pathogens, whereas ErmE is found in the soil bacterium that biosynthesizes erythromycin. Whether ErmC and ErmE, which possess only 24% sequence identity, use similar structural elements for rRNA substrate recognition and positioning is not known. To investigate this question, we used structural data from related proteins to guide site-saturation mutagenesis of key residues and characterized selected variants by antibiotic susceptibility testing, single turnover kinetics, and RNA affinity–binding assays. We demonstrate that residues in α4, α5, and the α5-α6 linker are essential for methyltransferase function, including an aromatic residue on α4 that likely forms stacking interactions with the substrate adenosine and basic residues in α5 and the α5-α6 linker that likely mediate conformational rearrangements in the protein and cognate rRNA upon interaction. The functional studies led us to a new structural model for the ErmC or ErmE-rRNA complex.