Dba-free" Palladium Intermediates Of The Heck-matsuda Reaction."

The dba-free Heck-Matsuda reaction was investigated via direct ESI-MS(/MS) monitoring. Palladium species involved in the reduction of Pd(II) during a Wacker type reaction and several dba-free arylpalladium transient complexes were detected and characterized. Based on these findings, a more comprehensible catalytic cycle for this pivotal reaction is suggested.113277-8

Desorption Electrospray Ionization Mass Spectrometry Reveals Lipid Metabolism of Individual Oocytes and Embryos.

Alteration of maternal lipid metabolism early in development has been shown to trigger obesity, insulin resistance, type 2 diabetes and cardiovascular diseases later in life in humans and animal models. Here, we set out to determine (i) lipid composition dynamics in single oocytes and preimplantation embryos by high mass resolution desorption electrospray ionization mass spectrometry (DESI-MS), using the bovine species as biological model, (ii) the metabolically most relevant lipid compounds by multivariate data analysis and (iii) lipid upstream metabolism by quantitative real-time PCR (qRT-PCR) analysis of several target genes (ACAT1, CPT 1b, FASN, SREBP1 and SCAP). Bovine oocytes and blastocysts were individually analyzed by DESI-MS in both positive and negative ion modes, without lipid extraction and under ambient conditions, and were profiled for free fatty acids (FFA), phospholipids (PL), cholesterol-related molecules, and triacylglycerols (TAG). Principal component analysis (PCA) and linear discriminant analysis (LDA), performed for the first time on DESI-MS fused data, allowed unequivocal discrimination between oocytes and blastocysts based on specific lipid profiles. This analytical approach resulted in broad and detailed lipid annotation of single oocytes and blastocysts. Results of DESI-MS and transcript regulation analysis demonstrate that blastocysts produced in vitro and their in vivo counterparts differed significantly in the homeostasis of cholesterol and FFA metabolism. These results should assist in the production of viable and healthy embryos by elucidating in vivo embryonic lipid metabolism

Pancreatic Cancer Surgical Resection Margins: Molecular Assessment by Mass Spectrometry Imaging

International audienceBackgroundSurgical resection with microscopically negative margins remains the main curative option for pancreatic cancer; however, in practice intraoperative delineation of resection margins is challenging. Ambient mass spectrometry imaging has emerged as a powerful technique for chemical imaging and real-time diagnosis of tissue samples. We applied an approach combining desorption electrospray ionization mass spectrometry imaging (DESI-MSI) with the least absolute shrinkage and selection operator (Lasso) statistical method to diagnose pancreatic tissue sections and prospectively evaluate surgical resection margins from pancreatic cancer surgery.Methods and FindingsOur methodology was developed and tested using 63 banked pancreatic cancer samples and 65 samples (tumor and specimen margins) collected prospectively during 32 pancreatectomies from February 27, 2013, to January 16, 2015. In total, mass spectra for 254,235 individual pixels were evaluated. When cross-validation was employed in the training set of samples, 98.1% agreement with histopathology was obtained. Using an independent set of samples, 98.6% agreement was achieved. We used a statistical approach to evaluate 177,727 mass spectra from samples with complex, mixed histology, achieving an agreement of 81%. The developed method showed agreement with frozen section evaluation of specimen margins in 24 of 32 surgical cases prospectively evaluated. In the remaining eight patients, margins were found to be positive by DESI-MSI/Lasso, but negative by frozen section analysis. The median overall survival after resection was only 10 mo for these eight patients as opposed to 26 mo for patients with negative margins by both techniques. This observation suggests that our method (as opposed to the standard method to date) was able to detect tumor involvement at the margin in patients who developed early recurrence. Nonetheless, a larger cohort of samples is needed to validate the findings described in this study. Careful evaluation of the long-term benefits to patients of the use of DESI-MSI for surgical margin evaluation is also needed to determine its value in clinical practice.ConclusionsOur findings provide evidence that the molecular information obtained by DESI-MSI/Lasso from pancreatic tissue samples has the potential to transform the evaluation of surgical specimens. With further development, we believe the described methodology could be routinely used for intraoperative surgical margin assessment of pancreatic cancer

Absence of the caspases 1/11 modulates liver global lipid profile and gut microbiota in high-fat-diet-induced obese mice

Obesity is a chronic disease with rising worldwide prevalence and largely associated with several other comorbidities, such as cancer, non-alcoholic fatty liver disease (NAFLD), and metabolic syndrome. Hepatic steatosis, a hallmark of NAFLD, is strongly correlated with obesity and has been correlated with changes in the gut microbiota, which can promote its development through the production of short-chain fatty acids (SCFAs) that regulate insulin resistance, bile acid, choline metabolism, and inflammation. Recent studies have suggested a controversial role for the inflammasome/caspase-1 in the development of obesity and non-alcoholic steatohepatitis (NASH). Here, we evaluated the role of inflammasome NLRP3 and caspases 1/11 in the establishment of obesity and hepatic steatosis in diet-induced obese mice, correlating them with the global lipid profile of the liver and gut microbiota diversity. After feeding wild-type, caspases 1/11, and NLRP3 knockout mice with a standard fat diet (SFD) or a high-fat diet (HFD), we found that the caspases 1/11 knockout mice, but not NLRP3 knockout mice, were more susceptible to HFD-induced obesity, and developed enhanced hepatic steatosis even under SFD conditions. Lipidomics analysis of the liver, assessed by MALDI-MS analysis, revealed that the HFD triggered a significant change in global lipid profile in the liver of WT mice compared to those fed an SFD, and this profile was modified by the lack of caspases 1/11 and NLRP3. The absence of caspases 1/11 was also correlated with an increased presence of triacylglycerol in the liver. Gut microbial diversity analysis, using 16S rRNA gene sequencing, showed that there was also an increase of Proteobacteria and a higher Firmicutes/Bacteroidetes ratio in the gut of caspases 1/11 knockout mice fed an HFD. Overall, mice without caspases 1/11 harbored gut bacterial phyla involved with weight gain, obesity, and hepatic steatosis. Taken together, our data suggest an important role for caspases 1/11 in the lipid composition of the liver and in the modulation of the gut microbial community composition. Our results further suggest that HFD-induced obesity and the absence of caspases 1/11 may regulate both lipid metabolism and gut microbial diversity, and therefore may be associated with NAFLD and obesity10CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP312359/2016-02016/22577-6This research was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq -#312359/2016-0). CM was funded by the Canada Research Chair Program, the Canadian Foundation for Innovation, McGill University, and the Canadian Institutes for Health Research (PJT-149098). ME was funded by the São Paulo Research Foundation (FAPESP) (2016/22577-6)

Developments in ambient mass spectrometry imaging and its applications in biomedical research and cancer diagnosis

My dissertation research has focused on developing and applying innovative mass spectrometry methods to the biomedical field, specifically in the area of cancer detection and intraoperative surgical-guidance. We used desorption electrospray ionization (DESI-MS) imaging to chemically characterize different types of cancers. The characterization was performed using particular chemical compounds found to be markers of disease through chemical imaging of human biopsy tissue. In particular, we have focused on investigating human genitourinary cancers, such as prostate, bladder and kidney, as well as human brain cancers. Our goal now is to translate this technology as validated in the laboratory to clinical and surgical settings, offering chemical information on disease state that could increase patient survival and improve disease management. We believe that this methodology can assist clinicians by offering analytical tools and molecular information that can provide improved intraoperative diagnosis of tumors and their margins, augmenting but not interfering with established surgical workflow. We have successfully shown that DESI-MS enables fast, accurate diagnosis and grading of human cancers based on lipid profiles, and have developed statistical classifiers based on molecular data. DESI-MS also provides valuable information on tumor cell concentration in tissue and on tumor margin position, especially in the case of human brain cancers. In addition to diagnostic capabilities, we have been able to contribute new knowledge on lipid expression in human cancers. Many of the studies included in this dissertation involved identification and structural characterization of various lipids by tandem MS analysis. For example, we detected cholesterol sulfate (CS) as a potential biomarker for prostate cancer. These studies have evolved and in collaboration with scientists in the Purdue Cancer Center we have now identified the enzyme cholesterol sulfotransferase 2B1b as a novel regulator of a malignant phenotype in prostate cancer. We are now also investigating the possibility of detecting CS and other lipid markers in urine samples as a non-invasive method for prostate cancer diagnosis. In human brain cancers, we have detected distinctive variations in lipid profiles related to malignancy, such as higher abundance of lipid phosphatidylserine (40:4) in high grade oligodendroglioma subtype, information which is potentially important for better understanding the biochemical processes related to cancer development. It is remarkable how the changes in lipid profiles observed in DESI-MS data provide reliable and accurate information on tumor subtype and grade. We are currently revising and expanding the classifier to include other types of brain tumors, such as meningiomas and metastatic brain tumors, and normal brain tissue with the goal of further improving diagnostic capabilities. We have also recently identified the oncometabolite 2-hydroxygluterate (2HG) directly from tissue by negative ion mode DESI-MS imaging in human gliomas; overproduction and accumulation of 2HG has been recently associated with a genetic mutation of the isocitrate dehydrogenase 1 (IDH1) enzyme, an indicator of increased survival rates for glioma patients. The exceptional ability to rapidly detect 2HG from tissue by DESI will add to the diagnostic capabilities of the technology by providing valuable prognostic information to surgeon and patient, as well as additional information on tumor margins. The development of novel methodologies and capabilities for tissue analysis by DESI-MS has also been pursued. The capability for full 3D molecular image construction using DESI-MS imaging was developed, allowing direct correlation and easy visualization of endogenous compounds in substructures of an entire organ, as demonstrated for a mouse brain. More recently, new solvent systems were developed which allow for a new capability for DESI-MS imaging - non-destructive tissue analysis. Sequential analysis, using for example immunohistochemistry or MALDI, can now be performed on the same tissue section previously imaged by DESI-MS. This allows lipid and metabolite information obtained by DESI-MS to be unambiguously correlated to protein and morphological information. This progress has greatly expanded the applications of DESI technology, especially in the biological field, and provides means for better understanding the molecular information derived from tissue. Moreover, this development also allows DESI-MS imaging to be now fully integrated into the pathological procedures, in clinical and surgical practice. (Abstract shortened by UMI.

Forensic Chemistry And Ambient Mass Spectrometry: A Perfect Couple Destined For A Happy Marriage?

Ambient mass spectrometry has been demonstrated, via various proof-of-concept studies, to offer a powerful, rather universal, simple, fast, nondestructive, and robust tool in forensic chemistry, producing reliable evidence at the molecular level. Its nearly nondestructive nature also preserves the sample for further inquiries. This feature article demonstrates the applicability of ambient mass spectrometry in forensic chemistry and explains the challenges that need to be overcome for this technique to make the ultimate step from the academic world into forensic institutes worldwide. We anticipate that the many beneficial and matching figures of merit will bring forensic chemistry and ambient mass spectrometry to a long-term relationship, which is likely to get strongly consolidated over the years.8

Interactive hyperspectral approach for exploring and interpreting DESI-MS images of cancerous and normal tissue sections

Desorption electrospray ionization (DESI) is an ambient mass spectrometry (MS) technique that can be operated in an imaging mode. It is known to provide valuable information on disease state and grade based on lipid profiles in tissue sections. Comprehensive exploration of the spatial and chemical information contained in 2D MS images requires further development of methods for data treatment and interpretation in conjunction with multivariate analysis. In this study, we employ an interactive hyperspectral approach and principal component analysis (PCA) to interpret the chemical and spatial information obtained from MS imaging of human bladder, kidney, germ cell and prostate cancer and adjacent normal tissues. This multivariate strategy facilitated distinction between tumor and normal tissue by correlating the lipid information with pathological evaluation of the same samples. Some common lipid ions, such as those of m/z 885.5 and m/z 788.5, nominally PI(18:0/20:4) and PS(18:0/18:1), as well as ions of free fatty acids and their dimers, appeared to be highly discriminating across different types of human cancers, while other ions, such as those of m/z 465.5 (cholesterol sulfate) for prostate cancer tissue and m/z 795.5 (seminolipid 16:0/16:0) for germ tissue, appeared to be extremely selective for the type of tissue analyzed. These data confirm that lipid profiles can reflect not only the disease/health state of tissue but also are characteristic of tissue type. The manual interactive strategy presented here is particularly useful to visualize the information contained in hyperspectral images by automatically connecting regions of PCA score space to pixels of the 2D physical object. The procedures developed in the study consider all the spectral variables and their inter-correlations, and guide subsequent investigations of the mass spectra and single ion images to allow one to maximize characterization between different regions of any DESI-MS image