Comparison of Cu, Ag, and Au Ions as Ionization Agents of Volatile Organic Compounds at Subatmospheric Pressure.

Ionization of volatile organic compounds (VOCs) by coinage metal ions (Cu, Ag, and Au) generated by laser desorption and ionization (LDI) of a metal nanolayer in subatmospheric conditions is explored. The study was performed in a commercial subatmospheric dual MALDI/ESI ion source. Five compounds representing different VOC classes were chosen for a detailed study of the metal ionization mechanism: ethanol, acetone, acetic acid, xylene, and cyclohexane.

Detection of Single Ag Nanoparticles Using Laser Desorption/Ionization Mass Spectrometry.

The detection of a single entity (molecule, cell, particle, etc.) was always a challenging subject. Here we demonstrate the detection of single Ag nanoparticles (NPs) using subatmospheric pressure laser desorption/ionization mass spectrometry (LDI MS).

A core outcome set for trials in miscarriage management and prevention: An international consensus development study.

Objective: To develop core outcome sets (COS) for miscarriage management and prevention.

Design: Modified Delphi survey combined with a consensus development meeting.

Setting: International.

Fate of Gold Nanoparticles in Laser Desorption/Ionization Mass Spectrometry: Toward the Imaging of Individual Nanoparticles.

This study focuses on mapping the spatial distribution of Au nanoparticles (NPs) by laser desorption/ionization mass spectrometry imaging (LDI MSI). Laser interaction with NPs and associated phenomena, such as change of shape, melting, migration, and release of Au ions, are explored at the single particle level. Arrays of dried droplets containing low numbers of spatially segregated NPs were reproducibly prepared by automated drop-on-demand piezo-dispensing and analyzed by LDI MSI using an ultrahigh resolution orbital trapping instrument.

Infrared Laser Desorption of Intact Nanoparticles for Digital Tissue Imaging.

We report a new technique for the digital mapping of biomarkers in tissues based on desorption and counting intact gold nanoparticle (Au NP) tags using infrared laser ablation single-particle inductively coupled plasma mass spectrometry (IR LA SP ICP MS). In contrast to conventional UV laser ablation, Au NPs are not disintegrated during the desorption process due to their low absorption at 2940 nm. A mass spectrometer detects up to 83% of Au NPs.

Disulfiram increases the efficacy of 5-fluorouracil in organotypic cultures of colorectal carcinoma.

Drug efficacy determined in preclinical research is difficult to transfer to clinical practice. This is mainly due to the use of oversimplified models omitting the effect of the tumor microenvironment and the presence of various cell types participating in the formation of tumors in vivo. In this study, we used robust three-dimensional models including spheroids grown from colon cancer cell lines and organotypic cultures prepared from the colorectal carcinoma tissue to test novel therapeutic strategies.

Metal Oxide Laser Ionization Mass Spectrometry Imaging of Fatty Acids and Their Double Bond Positional Isomers.

We present a novel combination of a metal oxide laser ionization mass spectrometry imaging (MOLI MSI) technique with off-line lipid derivatization by ozone for the detection of fatty acids (FA) and their carbon-carbon double bond (C═C) positional isomers in biological tissues. MOLI MSI experiments were realized with CeO and TiO nanopowders using a vacuum matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometer in the negative mode. The catalytic properties of these metal oxides allow FA cleavage from phospholipids under UV laser irradiation.

Mass Spectrometry Imaging Techniques Enabling Visualization of Lipid Isomers in Biological Tissues.

This Feature focuses on a review of recent developments in mass spectrometry imaging (MSI) of lipid isomers in biological tissues. The tandem MS techniques utilizing online and offline chemical derivatization procedures, ion activation techniques such as ozone-induced dissociation (OzID), ultraviolet photodissociation (UVPD), or electron-induced dissociation (EID), and other techniques such as coupling of ion mobility with MSI are discussed. The importance of resolving lipid isomers in diseases is highlighted.

Experiences and well-being of healthcare professionals working in the field of ultrasound in obstetrics and gynaecology as the SARS-CoV-2 pandemic were evolving: a cross-sectional survey study.

Objective: Assess experience of healthcare professionals (HCPs) working with ultrasound in obstetrics and gynaecology during the evolving SARS-CoV-2 pandemic, given the new and unprecedented challenges involving viral exposure, personal protective equipment (PPE) and well-being.

Design: Prospective cross-sectional survey study.

Setting: Online international survey.

Metal Ionization in Sub-atmospheric Pressure MALDI Interface: A New Tool for Mass Spectrometry of Volatile Organic Compounds.

A novel approach for the analysis of volatile organic compounds (VOCs) based on chemical ionization by Au ions has been proposed. The ionization is carried out in a commercially available dual sub-atmospheric pressure MALDI/ESI interface without any modifications. The Au ions are generated by laser ablation of a gold nanolayer with the MALDI laser, and VOCs are infused via the ESI capillary.

Fanniidae (Diptera): new species, new records and first description of the male of Fannia latifrontalis Hennig.

Fannia bohemica sp. nov. (Czech Republic, Slovakia) is described and illustrated.

Lactic Acidosis Interferes With Toxicity of Perifosine to Colorectal Cancer Spheroids: Multimodal Imaging Analysis.

Colorectal cancer (CRC) is a disease with constantly increasing incidence and high mortality. The treatment efficacy could be curtailed by drug resistance resulting from poor drug penetration into tumor tissue and the tumor-specific microenvironment, such as hypoxia and acidosis. Furthermore, CRC tumors can be exposed to different pH depending on the position in the intestinal tract.

Ozonization of Tissue Sections for MALDI MS Imaging of Carbon-Carbon Double Bond Positional Isomers of Phospholipids.

Visualizing the differential distribution of carbon-carbon double bond (C═C db) positional isomers of unsaturated phospholipids (PL) in tissue sections by use of refined matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) technologies offers a high promise to deeper understand PL metabolism and isomer-specific functions in health and disease. Here we introduce an on-tissue ozonization protocol that enables a particular straightforward derivatization of unsaturated lipids in tissue sections. Collision-induced dissociation (CID) of MALDI-generated ozonide ions (with yields in the several ten percent range) produced the Criegee fragment ion pairs, which are indicative of C═C db position(s).

Drug Penetration Analysis in 3D Cell Cultures Using Fiducial-Based Semiautomatic Coregistration of MALDI MSI and Immunofluorescence Images.

In this paper, we present an easy-to-follow procedure for the analysis of tissue sections from 3D cell cultures (spheroids) by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) and laser scanning confocal microscopy (LSCM). MALDI MSI was chosen to detect the distribution of the drug of interest, while fluorescence immunohistochemistry (IHC) followed by LSCM was used to localize the cells featuring specific markers of viability, proliferation, apoptosis and metastasis. The overlay of the mass spectrometry (MS) and IHC spheroid images, typically without any morphological features, required fiducial-based coregistration.

Quantitative Assessment of Anti-Cancer Drug Efficacy From Coregistered Mass Spectrometry and Fluorescence Microscopy Images of Multicellular Tumor Spheroids.

Spheroids-three-dimensional aggregates of cells grown from a cancer cell line-represent a model of living tissue for chemotherapy investigation. Distribution of chemotherapeutics in spheroid sections was determined using the matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI). Proliferating or apoptotic cells were immunohistochemically labeled and visualized by laser scanning confocal fluorescence microscopy (LSCM).

MALDI MS Imaging at Acquisition Rates Exceeding 100 Pixels per Second.

The practicality of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) applied to molecular imaging of biological tissues is limited by the analysis speed. Typically, a relatively low speed of stop-and-go micromotion of XY stages is considered as a factor substantially reducing the rate with which fresh sample material can be supplied to the laser spot. The sample scan rate in our laboratory-built high-throughput imaging TOF mass spectrometer was significantly improved through the use of a galvanometer-based optical scanner performing fast laser spot repositioning on a target plate.

Anti-cancer effects of wedelolactone: interactions with copper and subcellular localization.

Wedelactone (WL), a plant polyphenolic derivative of coumestan, represents a promising anti-cancer agent. The underlying mechanisms of its action are not fully understood and appear to involve interplay with copper ions. Herein, we examined coordination and redox interactions of WL with Cu in phosphate buffer (pH 7), and in two breast cancer cell lines.

A label-free MALDI TOF MS-based method for studying the kinetics and inhibitor screening of the Alzheimer's disease drug target β-secretase.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) is a well-established method with a unique set of qualities including sensitivity, minute sample consumption, and label-free detection, all of which are highly desired in enzyme assays. On the other hand, the application of MALDI TOF MS is usually limited by high concentrations of MS-incompatible compounds in the reaction mixture such as salts or organic solvents. Here, we introduce kinetic and inhibition studies of β-secretase (BACE1), a key enzyme of the progression of Alzheimer's disease.

Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry for the determination of selenomethionine and selenocysteine in algae and yeast.

In this work we present a simple and cost-effective approach for the determination of selenium species in algae and yeast biomass, based on a combination of thin-layer chromatography (TLC) with diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). Extraction of freeze-dried biomass was performed in 4M methanesulphonic acid and the selenium species were vaporized from cellulose TLC plates employing a continuous-wave infrared diode laser with power up to 4 W using a simple laboratory-built apparatus. Selenomethionine and selenocysteine were quantified with limits of detection 3 μg L in a Se-enriched microalgae Chlorella vulgaris and yeast certified reference material SELM-1.

LC coupled to ESI, MALDI and ICP MS - A multiple hyphenation for metalloproteomic studies.

A new multiple detection arrangement for liquid chromatography (LC) that supplements conventional electrospray ionization (ESI) mass spectrometry (MS) detection with two complementary detection techniques, matrix-assisted laser desorption/ionization (MALDI) MS and substrate-assisted laser desorption inductively coupled plasma (SALD ICP) MS has been developed. The combination of the molecular and elemental detectors in a single separation run is accomplished by utilizing a commercial MALDI target made of conductive plastic. The proposed platform provides a number of benefits in today's metalloproteomic applications, which are demonstrated by analysis of a metallothionein mixture.

Wedelolactone Acts as Proteasome Inhibitor in Breast Cancer Cells.

Wedelolactone is a multi-target natural plant coumestan exhibiting cytotoxicity towards cancer cells. Although several molecular targets of wedelolactone have been recognized, the molecular mechanism of its cytotoxicity has not yet been elucidated. In this study, we show that wedelolactone acts as an inhibitor of chymotrypsin-like, trypsin-like, and caspase-like activities of proteasome in breast cancer cells.

Fanniidae (Diptera): new synonym, new records and an updated key to males of European species of Fannia.

Based on revision of large recent collections of the authors, the following five species are first recorded from the Czech Republic: Fannia collini d'Assis-Fonseca, 1966 (simultaneously first record in Central Europe), Fannia lugubrina (Zetterstedt, 1838), Fannia melania (Dufour, 1839), Fannia slovaca Gregor & Rozkošný, 2005, and Fannia brinae Albuquerque, 1951 (simultaneously first record from low altitudes). Another species, Fannia alpina Pont, 1970, is first recorded from Slovak Republic, and Fannia cothurnata (Loew, 1873) is first recorded from Kazakhstan. An updated key to males of European species of Fannia is presented.

Direct Analysis of Gold Nanoparticles from Dried Droplets Using Substrate-Assisted Laser Desorption Single Particle-ICPMS.

Single particle inductively coupled plasma mass spectrometry (SP-ICPMS) has been generally accepted as a powerful tool in the field of nanoanalysis. The method has usually been restricted to direct nanoparticle (NP) introduction using nebulization or microdroplet generation systems. In this work, AuNPs are introduced into ICPMS by substrate-assisted laser desorption (SALD) directly from a suitable absorbing plastic surface using a commercial ablation cell for the first time.

Differential Isotope Labeling of Glycopeptides for Accurate Determination of Differences in Site-Specific Glycosylation.

We introduce a stable isotope labeling approach for glycopeptides that allows a specific glycosylation site in a protein to be quantitatively evaluated using mass spectrometry. Succinic anhydride is used to specifically label primary amino groups of the peptide portion of the glycopeptides. The heavy form (D4(13)C4) provides an 8 Da mass increment over the light natural form (H4(12)C4), allowing simultaneous analysis and direct comparison of two glycopeptide profiles in a single MS scan.