scholarly journals Ultrahigh-Throughput Direct Sampling MS: Sampling at 22 Hz by Infrared Matrix-Assisted Desorption Electrospray Ionization Mass Spectrometry

2021 ◽  
Author(s):  
Andrew J Radosevich ◽  
Fan Pu ◽  
David Chang-Yen ◽  
James W Sawicki ◽  
Nari N Talaty ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Large Scale ◽  
Desorption Electrospray Ionization ◽  
Ionization Mass ◽  
Label Free ◽  
Isocitrate Dehydrogenase 1 ◽  
Compound Libraries ◽  
Direct Sampling ◽  
Relative Standard

Infrared Matrix-Assisted Desorption Electrospray Ionization (IR-MALDESI) mass spectrometry is an ambient-direct sampling method being developed for high-throughput, label-free, biochemical screening of large-scale compound libraries. Here, we report the development of an ultrahigh-throughput continuous motion IR-MALDESI sampling approach capable of acquiring data at rates up to 22.7 samples per second in a 384-well microtiter plate. At top speed, less than 1% analyte carryover is observed from well-to-well and intensity relative standard deviations (RSD) of 11.5% and 20.9% for 3 micromolar 1-hydroxymidazolam and 12 micromolar dextrorphan, respectively, are achieved. The ability to perform parallel kinetics studies on 384 samples with ~30s time resolution using an isocitrate dehydrogenase 1 (IDH1) enzyme assay is shown. Taken together, these results demonstrate the use of IR-MALDESI at sample acquisition rates that surpass other currently reported direct sampling mass spectrometry approaches.

scholarly journals Mass Spectrometry Imaging of Diclofenac and Its Metabolites in Tissues Using Nanospray Desorption Electrospray Ionization.

2020 ◽  
Author(s):  
Hilary Brown ◽  
Daniela Mesa Sanchez ◽  
ruichuan yin ◽  
Bingming Chen ◽  
Marissa Vavrek ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Mass Spectrometry Imaging ◽  
Desorption Electrospray Ionization ◽  
Ionization Mass ◽  
Toxic Metabolite ◽  
Label Free ◽  
Bulk Analysis ◽  
Selected Ion Monitoring ◽  
Acyl Glucuronide

<p>Glucuronidation is a common phase II metabolic process for drugs and xenobiotics which increases their solubility for excretion. Acyl glucuronides (glucuronides of carboxylic acids) present concerns of toxicity as they have been implicated in gastrointestinal toxicity and hepatic failure. Despite the substantial success in the bulk analysis of these species, little is known about their localization in tissues. Herein, we used nanospray desorption electrospray ionization mass spectrometry imaging (nano-DESI-MSI) to examine the localization of diclofenac, a widely used nonsteroidal anti-inflammatory drug, and its metabolites in mouse kidney and liver tissues. Nano-DESI allows for label-free imaging with high spatial resolution and sensitivity without special sample pretreatment. Using nano-DESI-MSI, ion images for diclofenac and its major metabolites were produced. MSI data acquired over a broad <i>m/z</i> range showed fairly low signals of the drug and its metabolites. At least an order of magnitude improvement in the signals was obtained using selected ion monitoring (SIM), with <i>m/z</i> windows centered around the low-abundance ions of interest. Using nano-DESI MSI in SIM mode, we observed that diclofenac acyl glucuronide is localized to the inner medulla and hydroxydiclofenac to the cortex of the kidney. The distributions observed for both metabolites closely match the previously reported localization of enzymes that process diclofenac into its respective metabolites. The localization of diclofenac acyl glucuronide to medulla likely indicates that the toxic metabolite is being excreted from the tissue. In contrast, a uniform distribution of diclofenac, hydroxydiclofenac and the diclofenac acyl glucuronide metabolite was observed in the liver tissue. Semiquantitative analysis found the metabolite to diclofenac ratios calculated from nano-DESI in agreement to those calculated from liquid chromatography tandem mass spectrometry (LC-MS/MS) experiments. Collectively, our results demonstrate nano-DESI-MSI can be successfully used to image diclofenac and its primary metabolites in dosed liver and kidney tissues from mice and derive semi-quantitative data from localized tissue regions. </p>

scholarly journals Mass Spectrometry Imaging of Diclofenac and Its Metabolites in Tissues Using Nanospray Desorption Electrospray Ionization.

2020 ◽  
Author(s):  
Hilary Brown ◽  
Daniela Mesa Sanchez ◽  
ruichuan yin ◽  
Bingming Chen ◽  
Marissa Vavrek ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Mass Spectrometry Imaging ◽  
Desorption Electrospray Ionization ◽  
Ionization Mass ◽  
Toxic Metabolite ◽  
Label Free ◽  
Bulk Analysis ◽  
Selected Ion Monitoring ◽  
Acyl Glucuronide

<p>Glucuronidation is a common phase II metabolic process for drugs and xenobiotics which increases their solubility for excretion. Acyl glucuronides (glucuronides of carboxylic acids) present concerns of toxicity as they have been implicated in gastrointestinal toxicity and hepatic failure. Despite the substantial success in the bulk analysis of these species, little is known about their localization in tissues. Herein, we used nanospray desorption electrospray ionization mass spectrometry imaging (nano-DESI-MSI) to examine the localization of diclofenac, a widely used nonsteroidal anti-inflammatory drug, and its metabolites in mouse kidney and liver tissues. Nano-DESI allows for label-free imaging with high spatial resolution and sensitivity without special sample pretreatment. Using nano-DESI-MSI, ion images for diclofenac and its major metabolites were produced. MSI data acquired over a broad <i>m/z</i> range showed fairly low signals of the drug and its metabolites. At least an order of magnitude improvement in the signals was obtained using selected ion monitoring (SIM), with <i>m/z</i> windows centered around the low-abundance ions of interest. Using nano-DESI MSI in SIM mode, we observed that diclofenac acyl glucuronide is localized to the inner medulla and hydroxydiclofenac to the cortex of the kidney. The distributions observed for both metabolites closely match the previously reported localization of enzymes that process diclofenac into its respective metabolites. The localization of diclofenac acyl glucuronide to medulla likely indicates that the toxic metabolite is being excreted from the tissue. In contrast, a uniform distribution of diclofenac, hydroxydiclofenac and the diclofenac acyl glucuronide metabolite was observed in the liver tissue. Semiquantitative analysis found the metabolite to diclofenac ratios calculated from nano-DESI in agreement to those calculated from liquid chromatography tandem mass spectrometry (LC-MS/MS) experiments. Collectively, our results demonstrate nano-DESI-MSI can be successfully used to image diclofenac and its primary metabolites in dosed liver and kidney tissues from mice and derive semi-quantitative data from localized tissue regions. </p>

Intraoperative assessment of isocitrate dehydrogenase mutation status in human gliomas using desorption electrospray ionization–mass spectrometry

2020 ◽  
Vol 132 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Clint M. Alfaro ◽  
Valentina Pirro ◽  
Michael F. Keating ◽  
Eyas M. Hattab ◽  
R. Graham Cooks ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Isocitrate Dehydrogenase ◽  
Tumor Resection ◽  
Desorption Electrospray Ionization ◽  
Extent Of Resection ◽  
Ionization Mass ◽  
Idh Mutation ◽  
Mutation Status ◽  
Desi Ms

OBJECTIVEThe authors describe a rapid intraoperative ambient ionization mass spectrometry (MS) method for determining isocitrate dehydrogenase (IDH) mutation status from glioma tissue biopsies. This method offers new glioma management options and may impact extent of resection goals. Assessment of the IDH mutation is key for accurate glioma diagnosis, particularly for differentiating diffuse glioma from other neoplastic and reactive inflammatory conditions, a challenge for the standard intraoperative diagnostic consultation that relies solely on morphology.METHODSBanked glioma specimens (n = 37) were analyzed by desorption electrospray ionization–MS (DESI-MS) to develop a diagnostic method to detect the known altered oncometabolite in IDH-mutant gliomas, 2-hydroxyglutarate (2HG). The method was used intraoperatively to analyze tissue smears obtained from glioma patients undergoing resection and to rapidly diagnose IDH mutation status (< 5 minutes). Fifty-one tumor core biopsies from 25 patients (14 wild type [WT] and 11 mutant) were examined and data were analyzed using analysis of variance and receiver operating characteristic curve analysis.RESULTSThe optimized DESI-MS method discriminated between IDH-WT and IDH-mutant gliomas, with an average sensitivity and specificity of 100%. The average normalized DESI-MS 2HG signal was an order of magnitude higher in IDH-mutant glioma than in IDH-WT glioma. The DESI 2HG signal intensities correlated with independently measured 2HG concentrations (R2 = 0.98). In 1 case, an IDH1 R132H–mutant glioma was misdiagnosed as a demyelinating condition by frozen section histology during the intraoperative consultation, and no resection was performed pending the final pathology report. A second craniotomy and tumor resection was performed after the final pathology provided a diagnosis most consistent with an IDH-mutant glioblastoma. During the second craniotomy, high levels of 2HG in the tumor core biopsies were detected.CONCLUSIONSThis study demonstrates the capability to differentiate rapidly between IDH-mutant gliomas and IDH-WT conditions by DESI-MS during tumor resection. DESI-MS analysis of tissue smears is simple and can be easily integrated into the standard intraoperative pathology consultation. This approach may aid in solving differential diagnosis problems associated with low-grade gliomas and could influence intraoperative decisions regarding extent of resection, ultimately improving patient outcome. Research is ongoing to expand the patient cohort, systematically validate the DESI-MS method, and investigate the relationships between 2HG and tumor heterogeneity.

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