Bacterial Indole as a Multifunctional Regulator of Klebsiella oxytoca Complex Enterotoxicity.

Gastrointestinal microbes respond to biochemical metabolites that coordinate their behaviors. Here, we demonstrate that bacterial indole functions as a multifactorial mitigator of Klebsiella grimontii and Klebsiella oxytoca pathogenicity. These closely related microbes produce the enterotoxins tilimycin and tilivalline; cytotoxin-producing strains are the causative agent of antibiotic-associated hemorrhagic colitis and have been associated with necrotizing enterocolitis of premature infants. We demonstrate that carbohydrates induce cytotoxin synthesis while concurrently repressing indole biosynthesis. Conversely, indole represses cytotoxin production. In both cases, the alterations stemmed from differ- ential transcription of npsA and npsB, key genes involved in tilimycin biosynthesis. Indole also enhances conversion of tilimycin to tilivalline, an indole analog with reduced cytotox- icity. In this context, we established that tilivalline, but not tilimycin, is a strong agonist of pregnane X receptor (PXR), a master regulator of xenobiotic detoxification and intestinal inflammation. Tilivalline binding upregulated PXR-responsive detoxifying genes and inhib- ited tubulin-directed toxicity. Bacterial indole, therefore, acts in a multifunctional manner to mitigate cytotoxicity by Klebsiella spp.: suppression of toxin production, enhanced con- version of tilimycin to tilivalline, and activation of PXR

Light induced photochemical transformations: A green alternative in organic synthesis and chemical waste treatment

The term “green” chemistry refers to the use of alternative chemical pathways in environmental pollution prevention. The strategy behind “green” chemistry includes the reformulation of synthetic routes so that less toxic reagents are used and/or byproducts are produced. By reducing or eliminating the use or generation of hazardous substances associated with a particular synthesis or process, chemists can effectively reduce the risk to human health and the environment. ^ Organic photochemistry is playing an increasingly important role in organic synthesis and as such the use of photochemistry can lead to alternative “greener” synthetic pathways. An inherent advantage of light is that it causes chemical transformation to occur under mild conditions without the use of strong bases, acids, oxidants or reductants. ^ A protecting group is often introduced into a molecule during a multistep synthesis to prevent a certain functional group from reacting or to direct that a chemical reaction proceeds selectively at another site of the molecule. For example, a central problem in organic synthesis is to ensure that a specific hydroxyl function in a multifunctional molecule is protected from unwanted reactions altogether or until such time as its intrinsic reactivity is required. The “green” photochemical removal of a benzyl-protecting group for alcohols was investigated under different reaction variables. In order to increase the rate of cleavage an interesting family of quinoline ethers was synthesized. ^ Epoxides are an interesting class of compounds, which are widely used in organic synthesis. Regioselective epoxidation followed by regioselective epoxide cleavage provides a powerful entry into specifically functionalized molecules. In this study the focus was to develop an efficient, environmentally benign, mild method for the photocleavage of epoxides. Light induced regioselective cleavage of epoxides was also investigated. ^ Acetonitrile is frequently used in many industrial and research operations. Its occurrence in chemical wastes presents a major environmental and ecological hazard, as this compound is toxic. Waste treatment with visible light (or sunlight) can offer advantages to chemical treatment. Research requiring a dye catalyzed photochemical stimulated conversion of acetonitrile to less harmful products was investigated.

Comprehensive Determination of 28 PFAS Compounds in Oyster Tissue: A QuEChERS Sample Preparation Coupled with UPLC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are known to bioaccumulate in aquatic organisms, such as shellfish, and have been linked to adverse human health outcomes. Increasing attention has been focused on method development for the detection of PFAS in various media; however, these methods are typically tedious, require high solvent volumes, and are time consuming. The present method used a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction approach and analysis by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) to detect 28 PFAS in Eastern oyster (Crassostrea virginica) tissue. This method was validated using limit of detection, limit of quantitation, and precision and accuracy studies. Limits of detection ranged from 0.2 to 5.8 ng g−1, limits of quantitation ranged from 0.66 to 19.2 ng g−1, and recoveries spanned 52.1–105.9% at the 100 ng mL−1 analyte level. Analysis of 12 unknown oyster composite samples revealed the detection of PFHxA, PFPeS, PFOA, PFHpA and PFOS and at least two compounds were detected in each oyster sample. This validated method proved to be an efficient and environmentally friendly sample preparation method for PFAS analysis in complex tissue media, such as oysters.</p

Recent progress in L-H transition studies at JET: Tritium, Helium, Hydrogen and Deuterium

We present an overview of results from a series of L-II transition experiments undertaken at JET since the installation of the ITER-like-wall (JET-ILW), with beryllium wall tiles and a tungsten divertor. Tritium, helium and deuterium plasmas have been investigated. Initial results in tritium show ohmic L-H transitions at low density and the power threshold for the L-H transition (P-LH) is lower in tritium plasmas than in deuterium ones at low densities, while we still lack contrasted data to provide a scaling at high densities. In helium plasmas there is a notable shift of the density at which the power threshold is minimum ((n) over bar (e,min)) to higher values relative to deuterium and hydrogen references. Above (n) over bar (e,min) (He) the L-H power threshold at high densities is similar for D and He plasmas. Transport modelling in slab geometry shows that in helium neoclassical transport competes with interchange-driven transport, unlike in hydrogen isotopes. Measurements of the radial electric field in deuterium plasmas show that E-r shear is not a good indicator of proximity to the L-H transition. Transport analysis of ion heat flux in deuterium plasmas show a non-linearity as density is decreased below (n) over bar (e,min). Lastly, a regression of the JET-ILW deuterium data is compared to the 2008 ITPA scaling law