Enantiomeric separation of baclofen by capillary electrophoresis tandem mass spectrometry with sulfobutylether-beta-cyclodextrin as chiral selector in partial filling mode

Capillary electrophoresis (CE) coupled to tandem mass spectrometry was applied to the chiral separation of baclofen using sulfobutylether-beta-cyclodextrin chiral selector in partial filling counter current mode. On-line UV detection was simultaneously used. Method optimization was performed by studying the effect of cyclodextrin and BGE concentration as well as sheath liquid composition on analyte migration time and enantiomeric resolution. The cyclodextrin showed stereoselective complexation towards baclofen enantiomers, allowing chiral resolution at low concentration. The CE capillary protrusion from the ESI needle relevantly affected the chiral resolution and the analyte migration time. Complete enantiomeric separation was obtained by using 0.25 M formic acid BGE containing 1.75 mM of chiral selector and water/methanol (30:70, v/v) 3% formic acid as sheath liquid. The method exhibited a LOD of 0.1 microg/mL (racemic concentration) in MS3 product ion scan mode of detection and was applied to the analysis of racemic baclofen in pharmaceutical formulations.     

The HUPO Brain Proteome project wish list--summary of the 9(th) HUPO BPP Workshop 9-10 January 2008, Barbados

The Human Brain Proteome Project (HUPO BPP) aims at advancing knowledge and the understanding of neurodiseases and aging with the purpose of identifying prognostic and diagnostic biomarkers, as well as to push new diagnostic approaches and medications. The participating groups meet in semi-annual workshops to discuss the progress, as well as the needs, within the field of proteomics. The 9(th) HUPO BPP workshop took place in Barbados from 9-10 January, 2008. Discussing the future HUPO BPP Roadmap, the attendees drafted the so called HUPO BPP wish list containing timelines, suggestions and missions. This wish list will be updated regularly and will serve as a guideline for the next phase.     

Detection and characterization of CD133+ cancer stem cells in human solid tumours

Background

Osteosarcoma is the most common primary tumour of bone. Solid tumours are made of heterogeneous cell populations, which display different goals and roles in tumour economy. A rather small cell subset can hold or acquire stem potentials, gaining aggressiveness and increasing expectancy of recurrence. The CD133 antigen is a pentaspan membrane glycoprotein, which has been proposed as a cancer stem cell marker, since it has been previously demonstrated to be capable of identifying a cancer initiating subpopulation in brain, colon, melanoma and other solid tumours. Therefore, our aim was to observe the possible presence of cells expressing the CD133 antigen within solid tumour cell lines of osteosarcoma and, then, understand their biological characteristics and performances.

Methodology and Principal Findings

In this study, using SAOS2, MG63 and U2OS, three human sarcoma cell lines isolated from young Caucasian subjects, we were able to identify and characterize, among them, CD133⁺ cells showing the following features: high proliferation rate, cell cycle detection in a G2\M phase, positivity for Ki-67, and expression of ABCG2 transporters. In addition, at the FACS, we were able to observe the CD133⁺ cell fraction showing side population profile and forming sphere-clusters in serum-free medium with a high clonogenic efficiency.

Conclusions

Taken together, our findings lead to the thought that we can assume that we have identified, for the first time, CD133⁺ cells within osteosarcoma cell lines, showing many features of cancer stem cells. This can be of rather interest in order to design new therapies against the bone cancer.     

Direct quantitative analysis of lysophosphatidic acid molecular species by stable isotope dilution electrospray ionization liquid chromatography-mass spectrometry

In order to better understand the role of lysophosphatidic acid (LPA) in physiology and pathophysiology, it is necessary to accurately determine the molecular species and amounts of LPA in biological samples. We have developed a stable-isotope dilution, liquid chromatography-mass spectrometry assay for the direct quantitative analysis of 1-acyl-LPA. This method utilizes a deuterium-labeled internal standard, LPA (18:0-d(35)), and a single liquid-liquid extraction with acidic butanol that allows >95% recovery of LPA, followed by online normal-phase liquid chromatography-mass spectrometry. This protocol allows for the accurate, sensitive, and reproducible analysis of the individual 1-acyl-LPA species present in biological samples. The utility of the assay is demonstrated through the analysis of LPA species in plasma and serum from human volunteers. Total LPA in EDTA plasma was 0.61 +/- 0.14 microM in males and 0.74 +/- 0.17 microM in females, which increased to 0.91 +/- 0.23 and 0.99 +/- 0.38 microM after incubation for 24 h at 25 degrees C. Total LPA in serum was 0.85 +/- 0.22 microM in males and 1.57 +/- 0.56 microM in females, which increased to 4.78 +/- 0.89 and 5.57 +/- 0.73 microM after incubation for 24 h at 25 degrees C.     

A reference map of a human pituitary adenoma proteome

In order to compare the proteomes from different cell types of pituitary adenomas for our long-term goal to clarify the molecular mechanisms that participate in the formation of pituitary adenoma, and to detect any tumor-related marker for an "early-stage" diagnosis, the two-dimensional gel electrophoresis (2-DE) reference map of a pituitary adenoma tissue proteome is described here. A vertical, two-dimensional (2-D) polyacrylamide gel electrophoresis system and PDQuest image analysis software have been used to provide a high level of between-gel reproducibility and to accurately array each protein expressed in a pituitary adenoma tissue. Mass spectrometry (matrix-assisted laser desorption/ionization-time of flight MALDI-TOF and liquid chromatography-electrospray ionization-quadrupole-ion trap LC-ESI-Q-IT) and protein databases were used to characterize each protein in the 2-D gel. The results demonstrate that a good reproducibility of the 2-D gel pattern was attained. The position deviation of matched spots among four 2-D gels was 1.95 +/- 0.45 mm in the isoelectric focusing direction, and 1.70 +/- 0.53 mm in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis direction. A total of ca. 1000 protein spots were separated by 2-DE, and 135 protein spots that represent 111 proteins were characterized with mass spectrometry (96 spots for MALDI-TOF, 39 spots for LC-ESI-Q-IT). The characterized proteins include pituitary hormones, cellular signals, enzymes, cellular-defense proteins, cell-structure proteins, transport proteins, etc. Those proteins were located in the cytoplasmic, cellular membrane, mitochondrial, endoplasmic reticulum, nuclear, ribonucleosome, extracellular fractions, or were secreted in plasma, etc. Those identified proteins contribute to a functional profile of the pituitary adenoma proteome. These data will be used to expand the proteome database of the human pituitary, which can be accessed in the website http://www.utmem.edu /proteomics.     

Identification and characterization of phosphorylated proteins in the human pituitary

Post-translational modifications of proteins from the human pituitary gland play an important role in the regulation of different body functions. We report on the application of a liquid chromatography-tandem mass spectrometry (MS/MS) based approach to detect and characterize phosphorylated proteins in a whole human pituitary digest. By combining an immobilized metal affinity column-based enrichment method with MS/MS conditions that favor the neutral loss of phosphoric acid from a phosphorylated precursor ion, we identified several previously undescribed phosphorylated peptides. The identified peptides were matched to the sequences of six pituitary proteins: the human growth hormone, chromogranin A, secretogranin I, 60S ribosomal protein P1 and/or P2, DnaJ homolog subfamily C member 5, and galanin. The phosphorylation sites of these important regulatory proteins were determined by MS/MS and MS(3) analysis.