Use of microextraction by packed sorbents and gas chromatography-mass spectrometry for the determination of polyamines and related compounds in urine

AMD1 is required for the maintenance of leukemic stem cells and promotes chronic myeloid leukemic growth

Polyamines are critical elements in mammals, but it remains unknown whether adenosyl methionine decarboxylase (AMD1), a rate-limiting enzyme in polyamine synthesis, is required for myeloid leukemia. Here, we found that leukemic stem cells (LSCs) were highly differentiated, and leukemia progression was severely impaired in the absence of AMD1 in vivo. AMD1 was highly upregulated as chronic myeloid leukemia (CML) progressed from the chronic phase to the blast crisis phase, and was associated with the poor prognosis of CML patients. In addition, the pharmacological inhibition of AMD1 by AO476 treatment resulted in a robust reduction of the progression of leukemic cells both in vitro and in vivo. Mechanistically, AMD1 depletion induced loss of mitochondrial membrane potential and accumulation of reactive oxygen species (ROS), resulting in the differentiation of LSCs via oxidative stress and aberrant activation of unfolded protein response (UPR) pathway, which was partially rescued by the addition of polyamine. These results indicate that AMD1 is an essential element in the progression of myeloid leukemia and could be an attractive target for the treatment of the disease.

ESI-Q-TOF-MS determination of polyamines and related enzyme activity for elucidating cellular polyamine metabolism

We developed a new procedure for the comprehensive analysis of metabolites and enzymes involved in polyamine metabolism pathways. The procedure utilizes stable isotope-labeled polyamines and directly and precisely determines labeled products from enzymatic reactions by ESI-Q-TOF-MS. The activity of different enzymes could be determined in essentially the same manner by suitably adjusting the reaction conditions for each individual enzyme. We applied the procedure to extracts of regenerating rat liver and analyzed the changes in polyamine-metabolizing enzymes and polyamine contents during recovery from partial hepatectomy. A general outline of polyamine metabolism and information of polyamine dynamics were obtained. This kind of comprehensive information would be valuable in unifying detailed but fragmentary information obtained through conventional analyses focusing on one or a few enzymes and on a limited aspect of polyamine metabolic pathway.

Current trends on microextraction by packed sorbent – fundamentals, application fields, innovative improvements and future applications

MEPS, the acronym of microextraction by packed sorbent, is a simple, fast and user- and environmentally-friendly miniaturization of the popular solid-phase extraction technique (SPE).

Off-line microextraction by packed sorbent combined with on solid support derivatization and GC-MS: Application for the analysis of five pyrethroid metabolites in urine samples

A novel, fast and eco-friendly analytical method using microextraction by packed sorbent coupled to large volume injection-gas chromatography-mass spectrometry (MEPS-LVI-GC-MS) was developed for the determination of five pyrethroid metabolites (cis-2,2-dimethyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-cyclopropanecarboxylic acid, cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids, cis-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid and 3-phenoxybenzoic acid) in human urine. MEPS was performed off-line using a manually-operated semiautomatic syringe (eVol), and several parameters including the sample pH, extraction sorbent, washing solvent, volume and type of elution solvent and number of draw-eject cycles were optimized. Analytes were extracted from enzymatically hydrolyzed urine using a C18 solid phase with subsequent simultaneous derivatization and elution with a mixture of 1,1,1,3,3,3-hexafluoroisopropanol and diisopropylcarbodiimide in n-hexane (on-line derivatization). The optimized method was validated, with linearity established from 0.05 to 25ngmL^-1 and R values > 0.99. Obtained quantification limits were in the range of 0.06-0.08ngmL^-1, and the precision expressed as relative standard deviation (RSD) was below 14% for all of the analytes. The method was cross-validated with a reference approach based on liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) by analyzing 21 urine samples.