Hierarchical Cluster and Region of Interest Analyses Based on Mass Spectrometry Imaging of Human Brain Tumours.

Imaging mass spectrometry (IMS) has been rarely used to examine specimens of human brain tumours. In the current study, high quality brain tumour samples were selected by tissue observation. Further, IMS analysis was combined with a new hierarchical cluster analysis (IMS-HCA) and region of interest analysis (IMS-ROI). IMS-HCA was successful in creating groups consisting of similar signal distribution images of glial fibrillary acidic protein (GFAP) and related multiple proteins in primary brain tumours. This clustering data suggested the relation of GFAP and these identified proteins in the brain tumorigenesis. Also, high levels of histone proteins, haemoglobin subunit α, tubulins, and GFAP were identified in a metastatic brain tumour using IMS-ROI. Our results show that IMS-HCA and IMS-ROI are promising techniques for identifying biomarkers using brain tumour samples.

Investigation of 5-(3-Trifluoromethylbenzylidene)thiazolidine-2,4-dione as a Matrix for Analyses of Biogenic Monoamine Transmitters Using MALDI-MS.

In order to discover new matrices suitable for the analyses of low molecular-weight compounds using positive-ion mode matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (MS), 5-(3-trifluoromethylbenzylidene)thiazolidine-2,4-dione (3-CF3-BTD) was synthesized, and its effectiveness was compared with that when commercially available α-cyano-4-hydroxycinnamic acid was used. 3-CF3-BTD was sufficiently sensitive to analyze neurotransmitters, i.e., dopamine, serotonin, histamine, and epinephrine, in amounts of several picomoles. Similar to vacuum MALDI experiments, atmospheric-pressure MALDI-MS measurements using 3-CF3-BTD as a matrix also detected dopamine.

Identification of inflammation-related proteins in a murine colitis model by 2D fluorescence difference gel electrophoresis and mass spectrometry.

BACKGROUND AND AIMS: The aim of this study was to identify new intestinal proteins potentially associated with acute inflammation using proteomic profiling of an in vivo mice model of ulcerative colitis. METHODS: 2D fluorescence difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight spectrometer (MALDI-TOF) peptide mass fingerprinting were used to determine differentially expressed proteins between normal and inflamed intestinal mucosa. Acute colitis was induced by 8.0% dextran sodium sulfate (DSS) given p.o. for 7 days. RESULTS: Among a total of seven protein spots showing differential expression, we identified five different proteins, of which two were upregulated and three downregulated in colitis in comparison to normal mucosa, using the MASCOT search engine. 3-Hydroxy-3-methylglutaryl-coenzyme A synthase 2 and serpin b1a were upregulated proteins, and protein disulfide-isomerase A3, peroxiredoxin-6 and vimentin were identified as downregulated proteins. CONCLUSION: These identified proteins may be responsible for the development of the intestinal inflammation. 2D-DIGE and MALDI-TOF mass spectrometry are useful in the search for the differentially expressed proteins.

Potential implications for monitoring serum bile acid profiles in circulation with serum proteome for carbon tetrachloride-induced liver injury/regeneration model in mice.

Bile acids have recently emerged as versatile signaling molecules, and their signaling pathway is a promising target for the treatment of metabolic diseases. Here, we developed a highly sensitive and high-throughput quantification method for six taurine- and glycine-conjugated bile acids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry after solid-phase extraction (SPE-MALDI-TOF MS). In a carbon tetrachloride (CCl4)-induced liver injury/regeneration model in mice, serum bile acid profiles were monitored, and the same samples were separated by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), and protein spots that significantly changed in quantity in a serial time points were identified by MALDI-TOF MS. Serum taurocholic acid (TCA) concentration was significantly elevated earlier than the increase of serum aspartate aminotransferase (AST)/alanine aminotransferase (ALT) activity, a potentially sensitive marker for minimal hepatic damage. Furthermore, TCA peaked at 20 h after treatment when massive serum proteins appeared in circulation. It should be noted that direct MALDI-imaging mass spectrometry (IMS) has succeeded in showing a hepatic lobular distribution change of TCA, predominantly seen in zone 1 area whereas necrotic changes were dominant in zone 3 area. The in-depth analysis of bile acid profiles in circulation with hepatic lobular distribution is a strong basis to understand the serum proteome in CCl4-induced liver injury model.