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Aim/Objective: This study was designed to find via a highfat (HF) diet induced insulin resistant (IR) and/or type-2 diabetes (T2DM) C57Bl/6 mouse model potential novel biomarkers. Major aiming is to find following this lipidomics based approach novel safe biomarkers applicable for humans with IR/T2DM that can be used in the assessment of diagnosis, intensive treatment, clinical use and new drug development. In addition, the biomarker has to be found in blood-plasma simultaneously while is not a component of the HF-diet. Methods: Reversed phase liquid chromatography coupled to mass spectrometry (LC-MS) were used to quantify and qualify the rearrangement and repartitioning of fat stores in the heart-, hind limb-, carcass-muscle, liver, brain, and blood plasma of this mice model following a systems biology lipidomics based approach. Results: Two potential biomarkers were found for this HFdiet mouse model. The first biomarker was a 20:3 cholesteryl-ester (20:3-ChE) which significantly increased (P ≤ 0.016) in the fatty heart with 1317% while it rose very significantly (P ≤ 0.00001) in blood plasma with 1013% in the HF diet group in comparison to the control-group. (Co). The second biomarker was a 36:1 phosphatidylcholine (36:1-PC), which rose significantly (P ≤ 0.025) mainly in heart muscle with 400% while concentrations increased significantly strongly (P ≤ 0.002) in blood plasma with 1493% in the high-fat diet vs. Co. As an earlier defined prerequisite, both compounds were not found in the food. Conclusion: The 20:3-ChE biomarker (dihomo-γ-linolenic; 20:3 n-6) has been classified as a potential type 2 diabetes biomarker (T2DM) biomarker in a human cohort of the uppsala longitudinal study of adult men (ULSAM). In addition, we give a biochemical explanation for the 36:1- PC as hypoxic biomarker for cardiovascular diseases (CVD) diagnosis and therapy. Both biomarkers are interesting candidates for further validation in human cohorts.

A novel strategy combining peptide fingerprinting of single neurons by matrix-assisted laser desorption ionization mass spectrometry, molecular cloning, peptide chemistry, and electrospray ionization mass spectrometry was used to study the intricate processing pattern of a preprohormone expressed in identified neurons, the neuroendocrine light yellow cells (LYCs) of the gastropod mollusc, Lymnaea stagnalis. The cDNA encoding the precursor, named prepro-LYCP (LYCPs, light yellow cell peptides), predicts a straightforward processing into three peptides, LYCP I, II, and III, at conventional dibasic processing sites flanking the peptide domains on the precursor. However, matrix-assisted laser desorption ionization mass spectrometry of single LYCs revealed trimmed variant peptides derived from LYCP I and II. The variants were much more abundant than the intact peptides, indicating that LYCP I and II serve as intermediates in a peptide-processing sequence. Using the molecular masses of the peptides as markers to guide their isolation by well established purification methods, the structural identities of the peptides could be confirmed by amino acid sequencing. Furthermore, matrix-assisted laser desorption ionization mass spectrometry could detect colocalization of a novel peptide with the LYCPs.

Neuropeptides were directly detected in single identified neurons and the neurohemal area of peptidergic (neuroendocrine) systems in the Lymnaea brain by using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The samples were placed in matrix solution and ruptured to allow mixing of cell contents with the matrix solution. After formation of matrix crystals, the analytes were analyzed by MALDI-MS. It was surprising that clean mass spectra were produced, displaying extreme sensitivity of detection. In one of the neuroendocrine systems studied, we could demonstrate for the first time, by comparing the peptide patterns of soma and of neurohemal axon terminals, that processing of the complex prohormone expressed in this system occurs entirely in the soma. In the other system studied, novel peptides could be detected in addition to peptides previously identified by conventional molecular biological and peptide chemical methods. Thus, complex peptide processing and expression patterns could be predicted that were not detected in earlier studies using conventional methods. As the first MALDI-MS study of direct peptide fingerprinting in the single neuron, these experiments demonstrate that MALDI-MS forms a new and valuable approach to the study of the synthesis and expression of bioactive peptides, with potential application to single-cell studies in vertebrates, including humans.