Nitrite oxidation in ion chromatography-electrospray ionization-tandem mass spectrometry (IC-ESI-MS/MS).

Nitrite anions are formed in the human body and in the natural environment as intermediate chemical compounds during the reduction of nitrate, a ubiquitous anthropogenic contaminant introduced into the environment primarily through fertilizer use. Multiple reaction monitoring (MRM) in ion chromatography-electrospray ionization-tandem mass spectrometry (IC-ESI-MS/MS) is a promising new technique for quantifying and confirming the identity of anions in complex aqueous mixtures. In this article, we present the results of a short investigation devised to: (1) compare the signal generated by the MRM transitions for nitrite with those for nitrate, (2) isolate the source of the signal from these MRM transitions occurring within the IC-ESI-MS/MS instrument and (3) assess the relationship between the observed MRM signals for nitrite.

Identification of residues important for cleavage of the extracellular signaling peptide CSF of Bacillus subtilis from its precursor protein.

Extracellular Phr pentapeptides produced by gram-positive, spore-forming bacteria regulate processes during the transition from exponential- to stationary-phase growth. Phr pentapeptides are produced by cleavage of their precursor proteins. We determined the residues that direct this cleavage for the Bacillus subtilis Phr peptide, CSF, which is derived from the C terminus of PhrC.

Identification of subtilisin, Epr and Vpr as enzymes that produce CSF, an extracellular signalling peptide of Bacillus subtilis.

Cell-cell communication regulates many important processes in bacteria. Gram-positive bacteria use peptide signals for communication, such as the Phr pentapeptides of Bacillus subtilis. The Phr pentapeptides are secreted with a pro domain that is cleaved to produce an active signalling peptide.

Multistep synthesis of a radiolabeled imaging probe using integrated microfluidics.

Microreactor technology has shown potential for optimizing synthetic efficiency, particularly in preparing sensitive compounds. We achieved the synthesis of an [(18)F]fluoride-radiolabeled molecular imaging probe, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), in an integrated microfluidic device. Five sequential processes-[18F]fluoride concentration, water evaporation, radiofluorination, solvent exchange, and hydrolytic deprotection-proceeded with high radio-chemical yield and purity and with shorter synthesis time relative to conventional automated synthesis.

Role for sterol regulatory element-binding protein in activation of endothelial cells by phospholipid oxidation products.

Oxidized phospholipids, including oxidation products of palmitoyl-arachidonyl-phosphatidyl choline (PAPC), are mediators of inflammation in endothelial cells (ECs) and known to induce several chemokines, including interleukin-8 (IL-8). In this study, we show that oxidized PAPC (OxPAPC), which accumulates in atherosclerotic lesions, paradoxically depletes endothelial cholesterol, causing caveolin-1 internalization from the plasma membrane to the endoplasmic reticulum and Golgi, and activates sterol regulatory element-binding protein (SREBP). Cholesterol loading reversed these effects.

Tear lipocalin: potential for selective delivery of rifampin.

The potential of ligand binding proteins as drug carriers and delivery systems has recently sparked great interest. We investigated the potential of tear lipocalin (TL) to bind the antibiotic, rifampin, and the environmental conditions for controlled release. To determine if TL binds rifampin, gel filtration was used to isolate protein fractions of tears.

Hydroxy alkenal phospholipids regulate inflammatory functions of endothelial cells.

Monocyte recruitment into the vessel wall plays an important role in atherogenesis. Polar lipid components of minimally modified/oxidized LDL were shown to activate endothelial cells to increase the synthesis of monocyte chemotactic factors and surface expression of adhesion molecules. We previously reported regulation of endothelial cell inflammatory functions by oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (Ox-PAPC) and three component oxidized phospholipids, containing oxovaleroyl (POVPC), glutaroyl (PGPC) and epoxyisoprostane (PEIPC) groups at the sn-2 position of oxidized phospholipids.