Differentiation of human kidney stones induced by melamine and uric acid using surface desorption atmospheric pressure chemical ionization mass spectrometry

Melamine induces reproductive dysfunction via down-regulated the phosphorylation of p38 and downstream transcription factors Max and Sap1a in mice testes

Melamine poisoning incidents and potential health risks raise global attention. Recent studies imply that melamine exposure is related to male reproductive dysfunction, however, the underlying mechanisms are unclear. In this study, 32 male Kunming mice were administered with 0, 12.5, 25, and 50 mg/L melamine via drinking water for 13 weeks, respectively. Sperm quality, testicular morphology, and the mRNA expression levels of MAPK family members p38, ERK5, ERK1/2, JNK1/2/3 and their downstream transcription factors GADD153, MAX, MEF2C, CREB, c-Myc, JunD, c-JUN, Sap1a, p53, ATF-2, Elk1, and Nur77 in testes were investigated. The results revealed that low-dose melamine exposure reduced sperm quality, altered the testicular histological structure, and reduced the mRNA expression levels of p38, ERK1/2, MAX and Sap1a in the testes. The p38 and phosphorylated-p38 expressions analysis further suggested that the down-regulated phosphorylation of p38 and downstream transcription factors MAX and Sap1a play key roles in male reproductive dysfunction caused by melamine. Altogether, our study provides a new insight to elucidate the underlying mechanisms by which melamine induces male reproductive toxicity, and to evaluate the health risks of melamine.

Rapid Determination of the Freshness of Lotus Seeds Using Surface Desorption Atmospheric Pressure Chemical Ionization-Mass Spectrometry with Multivariate Analyses

In order to explore a new method to detect the freshness of lotus seeds, the lotus seeds stored for 0, 1, 2, and 3 years, respectively, were used as experimental materials and analyzed by DAPCI-MS (desorption atmospheric pressure chemical ionization-mass spectrometry). The obtained data were processed by principal component analysis (PCA) and backpropagation artificial neural networks (BP-ANNs). The result showed that DAPCI-MS could obtain abundant chemical material information from the slice surface of lotus seeds. The BP-ANNs model could be applied not only to distinguish fresh and aged lotus seeds with the testing set accuracies of 95.0% and 91.7%, respectively, but also to classify lotus seeds with different storage times with the testing set accuracies of 90.0%, 85.0%, 85.0%, and 90.0%, respectively. The paper developed a fast, convenient, and accurate method for the freshness detection of lotus seed and would provide reliable reference value for rapid authentication of food freshness by the rapid mass spectrometry technique.

Rapid Scotch Whisky Analysis and Authentication using Desorption Atmospheric Pressure Chemical Ionisation Mass Spectrometry

Whisky, as a high value product, is often adulterated, with adverse economic effects for both producers and consumers as well as potential public health impacts. Here we report the use of DAPCI-MS to analyse and chemically profile both genuine and counterfeit whisky samples employing a novel 'direct from the bottle' methodology with zero sample pre-treatment, zero solvent requirement and almost no sample usage. 25 samples have been analysed from a collection of blended Scotch whisky (n = 15) and known counterfeit whisky products (n = 10). Principal component analysis has been applied to dimensionally reduce the data and discriminate between sample groups. Additional chemometric modelling, a partial least squares regression, has correctly classified samples with 92% success rate. DAPCI-MS shows promise for simple, fast and accurate counterfeit detection with potential for generic aroma profiling and process quality monitoring applications.

Melamine Impairs Renal and Vascular Function in Rats

Melamine incident, linked to nephrotoxicity and kidney stone in infants previously exposed to melamine-contaminated milk products, was unprecedentedly grave in China in 2008 as little was known about the mechanistic process leading to renal dysfunction in affected children. This study investigates whether neonatal ingestion of melamine leads to renal and vascular dysfunction in adulthood; and whether ingestion of melamine in pregnant rats leads to renal dysfunction in their offspring. A combination of approaches employed includes functional studies in rat renal arteries, renal blood flow measurement by functional magnetic resonance imaging, assay for pro-inflammatory and fibrotic biomarkers, immunohistochemistry, and detection of plasma and renal melamine. We provide mechanistic evidence showing for the first time that melamine reduces renal blood flow and impairs renal and vascular function associated with overexpression of inflammatory markers, transforming growth factor-β1, bone morphogenic protein 4 and cyclooxygenase-2 in kidney and renal vasculature. Melamine also induces renal inflammation and fibrosis. More importantly, melamine causes nephropathies in offsprings from pregnant rat exposed to melamine during pregnancy, as well as in neonatal rat exposed to melamine afterbirth, thus supporting the clinical observations of kidney stone and acute renal failure in infants consuming melamine-contaminated milk products.

Plasma-based ambient ionization mass spectrometry in bioanalytical sciences

Plasma-based ambient ionization mass spectrometry techniques are gaining growing interest due to their specific features, such as the need for little or no sample preparation, its high analysis speed, and the ambient experimental conditions. Samples can be analyzed in gas, liquid, or solid forms. These techniques allow for a wide range of applications, like warfare agent detection, chemical reaction control, mass spectrometry imaging, polymer identification, and food safety monitoring, as well as applications in biomedical science, e.g., drug and pharmaceutical analysis, medical diagnostics, biochemical analysis, etc. Until now, the main drawback of plasma-based techniques is their quantitative aspect, but a lot of efforts have been done to improve this obstacle.

Direct assessment of phytochemicals inherent in plant tissues using extractive electrospray ionization mass spectrometry

An ambient pressure ionization mass spectrometric strategy called internal extractive electrospray ionization mass spectrometry (iEESI-MS) has been developed and applied for direct profiling of labile phytochemicals inherent in various native plant tissues, including leaves, roots, and fruits. By passing the electrospray solvent through the plant tissue, a variety of phytochemicals, such as amino acids, sugars (e.g., glucose, sucrose, polysaccharides, etc.), and alkaloids, were continuously extracted from the sample interior, driven toward the natural/cut electro-spraying tip, and vaporized into gaseous ions for mass spectrometric interrogation. Phytochemical patterns obtained by iEESI-MS permit a rapid differentiation between various species of ginkgo plant and strawberry maturity stages, as well as characterization of physiological/pathologic conditions of chlorophytum comosum. Our experimental results further demonstrate that the established iEESI-MS approach is potentially useful for direct phytochemomics studies with minimal biodegradation, allowing elucidation of plant metabolism with high speed, specificity, and simplicity of analysis.

Document authentication at molecular levels using desorption atmospheric pressure chemical ionization mass spectrometry imaging

Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS), which was operated in either a gasless, solvent-free or methanol vapor-assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI-MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI-MS imaging differentiated a 10-min old from two 4 h old samples. Non-destructive forensic analysis of forged signatures either handwritten or computer-assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI-MS. The experimental results show that DAPCI-MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications.