Quantitative Profiling

BACKGROUND:

Because cerebrospinal fluid (CSF) is in close contact with diseased areas in neurological disorders, it is an important source of material in the search for molecular biomarkers. However, sample handling for CSF collected from patients in a clinical setting might not always be adequate for use in proteomics and metabolomics studies.

Upon exposure to platinum analogs, mesenchymal stem cells were recently found to excrete minute amounts of specific lipid mediators that induce chemotherapy resistance. One of these lipids is hexadeca-4,7,10,13-tetraenoic acid (FA(16:4)n-3). Importantly, FA(16:4)n-3 is present in high concentrations in certain fish oils and algae and oral intake of these products also potently induced chemotherapy resistance. These findings suggested that certain foods could negatively affect clinical chemotherapy treatment.

Oxidative damage is thought to be a major cause in development of pathologies and aging. However, quantification of oxidative damage is methodologically difficult. Here, we present a robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach for accurate, sensitive, and linear in vivo quantification of endogenous oxidative damage in the nematode Caenorhabditis elegans, based on F3-isoprostanes. F3-isoprostanes are prostaglandin-like markers of oxidative damage derived from lipid peroxidation by Reactive Oxygen Species (ROS).

A hydrophilic interaction liquid chromatography (HILIC) - ion trap mass spectrometry method was developed for separation of a wide range of phospholipids. A diol column which is often used with normal phase chromatography was adapted to separate different phospholipid classes in HILIC mode using a mobile phase system consisting of acetonitrile, water, ammonium formate and formic acid.

This article presents nano-slit electrospray emitters fabricated by a micro- to nanofluidic via technology. The main advantage of the technology is the ability

Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier.

In this work, we demonstrate the applicability of electroextraction (EE) to urine metabolites. To investigate which urine metabolite classes are susceptible to EE, off-line EE experiments were carried out with a prototype device, in which urine metabolites were electroextracted from ethyl acetate into water. The obtained extracts were examined with direct infusion MS and the results demonstrated that several compound classes could be extracted, amongst which amino acids and acylcarnitines.