Nowadays, the research of exhaled breath condensate (EBC) analysis is widely discussed in the scientific community. The growing interest in EBC analysis results is related to the ample advantages of non-invasive techniques in healthcare and related fields. In particular, EBC analysis can be used to diagnose respiratory diseases, monitor the disease’s course during therapy, and monitor drug intake and metabolism. This review aims to systematize the accumulated knowledge on EBC collection, concentration, storage, and analysis methods and compare them with similar procedures for exhaled breath (EB). We proposed a generalized chemical classification of EBC compounds that are biomarkers for various diseases. The potential transformation of substances during EB condensation was considered, and EBC analysis methods were systematically categorized based on this classification. Methods for EBC analysis using chromatographic separation with mass spectrometric detection (hyphenated methods) were separately discussed as the most promising methods for future research applications.

Primenenie metodov pryamoj mass-spektrometrii yavlyaetsya odnim iz perspektivnyh podhodov k uluchsheniyu polnoty rezekcii glial'nyh opuholej za schet ispol'zovaniya dopolnitel'nogo sposoba povysheniya tochnosti opredeleniya granic opuholi neposredstvenno v hode nejrohirurgicheskogo vmeshatel'stva. Massivy dannyh, nakaplivaemye v hode aprobacii podobnyh tekhnologij, mogut byt' ispol'zovany i dlya provedeniya fundamental'nyh issledovanij s cel'yu vyyavleniya metabolicheskih izmenenij, soprovozhdayushchih rost opuholi. Cel'yu raboty bylo provesti analiz izmenenij v lipidnom sostave kletochnyh membran diffuznyh i anaplasticheskih astrocitom na osnove dannyh, sobrannyh v hode pryamogo mass-spektrometricheskogo profilirovaniya tkanej, issechennyh v hode planovogo nejrohirurgicheskogo vmeshatel'stva. Lipidnye profili, poluchennye v hode issledovaniya obrazcov opuholevyh tkanej (n = 43) metodom protochnoj mikroekstrakcii v kartridzhe, analizirovali s ispol'zovaniem linejnogo diskriminantnogo analiza so szhatiem, chto pozvolilo vydelit' nabor lipidov, soderzhanie kotoryh izmenyaetsya pri uvelichenii stepeni zlokachestvennosti opuholi. Raznoobrazie lipidov snizhaetsya po mere povysheniya stepeni zlokachestvennosti, tak, soderzhanie 13 fosfolipidov, prinadlezhashchih k 6 razlichnym podklassam, okazyvaetsya snizhennym v anaplasticheskih opuholyah po sravneniyu s diffuznymi. S rostom zlokachestvennosti opuholi umen'shayutsya kak srednij razmer zhirnokislotnyh ostatkov polyarnyh lipidov, tak i stepen' ih nenasyshchennosti. Poluchennye rezul'taty horosho soglasuyutsya s dannymi, poluchennymi ranee v ramkah issledovaniya vysokozlokachestvennyh glial'nyh opuholej, i podtverzhdayut biohimicheskie predstavleniya o pereprogrammirovanii metabolizma v hode malignizacii nejroglii.

Radikal'noe udalenie opuholi do sih por ostaetsya naibolee effektivnym metodom lecheniya onkologicheskih zabolevanij golovnogo mozga. Zadachi intraoperacionnogo monitoringa na segodnyashnij den' reshayut s pomoshch'yu pozitronno-emissionnoj tomografii, magnitno-rezonansnoj tomografii i gistohimicheskogo analiza, odnako oni trebuyut primeneniya dorogostoyashchego oborudovaniya vysokokvalificirovannym personalom, poetomu do sih por ne poluchili shirokogo rasprostraneniya. V kachestve al'ternativy vozmozhno primenenie metodov mass-spektrometrii bez probopodgotovki s posleduyushchim analizom mass-spektrometricheskih dannyh metodami mashinnogo obucheniya. Tak kak dlya mass-spektrometrii bez probopodgotovki harakterny bolee bogatye i raznoobraznye po kolichestvu pikov spektry, ee primenenie trebuet special'noj predvaritel'noj obrabotki eksperimental'nyh dannyh. Cel'yu issledovaniya bylo razrabotat' metody opredeleniya optimal'nyh znachenij parametrov predvaritel'noj obrabotki dannyh mass-spektrometrii bez probopodgotovki. V rabote predstavleny dva takih metoda, a takzhe privedeny konkretnye znacheniya parametrov dlya dannyh, poluchennyh s pomoshch'yu mass-spektrometra Thermo LTQ XL Orbitrap ETD.

Rapid and reliable methods for detecting tumor margins are crucial for neuro-oncology. Several mass spectrometry-based methods have been recently proposed to address this problem. Inline Cartridge Extraction (ICE) demonstrates the potential for clinical application, based on ex-vivo analysis of dissected tissues, but requires timeconsuming steps to avoid cross-contamination. In this work, a method of incorporating a disposable electrospray emitter into the ICE cartridge by PEEK sleeves melting is developed. It reduces total analysis time and improves throughput. The proposed setup also improves the robustness of the ICE molecular profiling as demonstrated with human glial tumor samples in that stability and reproducibility of the spectra were increased.

The automatic processing of high-dimensional mass spectrometry data is required for the clinical implementation of ambient ionization molecular profiling methods. However, complex algorithms required for the analysis of peak-rich spectra are sensitive to the quality of the input data. Therefore, an objective and quantitative indicator, insensitive to the conditions of the experiment, is currently in high demand for the automated treatment of mass spectrometric data. In this work, we demonstrate the utility of the Shapley value as an indicator of the quality of the individual mass spectrum in the classification task for human brain tumor tissue discrimination. The Shapley values are calculated on the training set of glioblastoma and nontumor pathological tissues spectra and used as feedback to create a random forest regression model to estimate the contributions for all spectra of each specimen. As a result, it is shown that the implementation of Shapley values significantly accelerates the data analysis of negative mode mass spectrometry data alongside simultaneous improving the regression models' accuracy.

Mass spectrometry fingerprinting combined with multidimensional data analysis has been proposed in surgery to determine if a biopsy sample is a tumor. In the specific case of brain tumors, it is complicated to obtain control samples, leading to model overfitting due to unbalanced sample cohorts. Usually, classifiers are trained using a single measurement regime, most notably single ion polarity, but mass range and spectral resolution could also be varied. It is known that lipid groups differ significantly in their ability to produce positive or negative ions; hence, using only one polarity significantly restricts the chemical space available for sample discrimination purposes. In this work, we have developed an approach employing mass spectrometry data obtained by eight different regimes of measurement simultaneously. Regime-specific classifiers are trained, then a mixture of experts techniques based on voting or mean probability is used to aggregate predictions of all trained classifiers and assign a class to the whole sample. The aggregated classifiers have shown a much better performance than any of the single-regime classifiers and help significantly reduce the effect of an unbalanced dataset without any augmentation.

Mass spectrometry imaging is a promising tool complement to the histology study for evaluation of presence of different tissue types in the sample. To make this method faster, more accurate and precise we have presented earlier the cosine similarity measure maps (CSMM). The method provides the spatial distribution of cosine similarity measure metrics between chosen MSI pixel and the rest of the image. In cases when samples under test are heterogeneous and not guaranteed to have clear clusters with distinct borders, it is interesting to analyze the heterogeneity, area borders and their sensitivity to reference CSMM pixel selection. Here we present the software for interactive building of CSMM for different parameters, their visual analysis and saving such CSMM in publication-ready quality without additional programming. Source code, example datasets, binaries, and other information are available at https://github.com/EvgenyZhvansky/Interactive_CSMM.

Ambient ionization mass spectrometry has become one of the most promising approaches for rapid and high-throughput screening of small molecules in complex biological matrices for emergency medicine, forensics, and food and agriculture applications. The simple procedures for sample collection and ionization without additional pretreatment are vital in these fields. Many efforts have been devoted to modifying various ambient ionization techniques to simplify the procedures and improve the robustness and sensitivity of the methods. Here, we demonstrate the implementation of rigid spherical sampler probes to improve the robustness of touch spray ionization mass spectrometry. The sphericity of the probes increases the stability of the cone-jet mode of electrospray, reduces the requirements for fine positioning of a sampler in the ion source, and decreases the possibility of corona discharge occurrence. The utilization of spherical sampler probes allows fast, non-invasive sampling, followed by rapid analysis for various drugs of different chemical classes in complex biological matrices, such as the whole blood or sebum collected from the skin surface. The linearity of the analytical signal response from drug concentration confirms the possibility of creating a simple semiquantitative method for small molecules monitoring using spherical sampler probes.

Alterations in cell metabolism, including changes in lipid composition occurring during malignancy, are well characterized for various tumor types. However, a significant part of studies that deal with brain tumors have been performed using cell cultures and animal models. Here, we present a dataset of 124 high-resolution negative ionization mode lipid profiles of human brain tumors resected during neurosurgery. The dataset is supplemented with 38 non-tumor pathological brain tissue samples resected during elective surgery. The change in lipid composition alterations of brain tumors enables the possibility of discriminating between malignant and healthy tissues with the implementation of ambient mass spectrometry. On the other hand, the collection of clinical samples allows the comparison of the metabolism alteration patterns in animal models or in vitro models with natural tumor samples ex vivo. The presented dataset is intended to be a data sample for bioinformaticians to test various data analysis techniques with ambient mass spectrometry profiles, or to be a source of clinically relevant data for lipidomic research in oncology.

The analysis of data obtained using ambient mass spectrometric profiling of clinical samples of primary and secondary human glioblastomas ex vivo, revealed changes in the lipid composition of tissues accompanying the development of grade IV glial tumors (according to the WHO classification). It has been shown that both primary and secondary (developed from astrocytoma) tumors are enriched with mono- and di-unsaturated phosphatidylcholines (PC 26:1, 30:2, 32:1, 32:2, 34:1, 34:2). At the same time, the content of saturated and polyunsaturated phosphatidylcholines and phosphatidylethanolamines decreases. These changes are associated both with altered availability of polyunsaturated fatty acids and activation of de novo synthesis and beta-oxidation of fatty acids under conditions of oxygen starvation in the tumor body.

The paper presents a method for rapid multi-omics investigation of biological samples using polypropylene bulk porous samplers. The use of porous samplers makes it easy to collect samples from the surface of the skin, mucous membranes, and biological fluids even in a field, and the surfaces of wounds and injuries. Collected samples do not require special storage conditions, and the samplers are lightweight and very compact. They can be used to monitor the condition of cosmonauts before, during, and after the spaceflight with the same sample collection method. The analysis of biomaterial applied to the sampler is performed using direct mass spectrometry methods, similar to the dried blood spot technique that is already used in clinical practice. However, bulk porous samplers allow expanding the range of analytes ionization conditions, which increases the stability and reliability of the ionization process, which expands the variety of analyzed molecules. The proposed method can be used to study compounds of various classes, including proteins, lipids, and metabolites, to systematically monitor the status of people in extreme conditions (athletes, astronauts), or to study the condition of patients in the clinic.

Recently, mass-spectrometry methods show its utility in tumor boundary location. The effect of differences between research and clinical protocols such as low- and high-resolution measurements and sample storage have to be understood and taken into account to transfer methods from bench to bedside. In this study, we demonstrate a simple way to compare mass spectra obtained by different experimental protocols, assess its quality, and check for the presence of outliers and batch effect in the dataset. We compare the mass spectra of both fresh and frozen-thawed astrocytic brain tumor samples obtained with the inline cartridge extraction prior to electrospray ionization. Our results reveal the importance of both positive and negative ion mode mass spectrometry for getting reliable information about sample diversity. We show that positive mode highlights the difference between protocols of mass spectra measurement, such as fresh and frozen-thawed samples, whereas negative mode better characterizes the histological difference between samples. We also show how the use of similarity spectrum matrix helps to identify the proper choice of the measurement parameters, so data collection would be kept reliable, and analysis would be correct and meaningful.

It is known that aspartic acid isomerization process plays a role in aging processes and may be used as a marker for aging of natural materials. As for Alzheimer's disease, the most abundant modification in the peptide profile is the aspartate isomerization of amyloid-β. Liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry-based approaches with Collision Induced Dissociation (CID) or Electron Capture Dissociation (ECD) fragmentation provide a good and precise method for the relative quantitation of iso- to normal amyloid-β peptides but require additional time consuming steps. In this study, MALDI-TOF/TOF-matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MS) method was developed as a high-throughput approach for the relative quantitation of the isomerized form of the amyloid-β peptide.

Complexes of peptide fragment 1-16 of beta-amyloid with transition metals play an important role in the development of a broad class of neurodegenerative diseases, which determines the interest in investigating the structures of these complexes. In this work, we have applied the method of the deuterium/hydrogen exchange in combination with ultra-high-resolution mass spectrometry to study conformational changes in (1-16) beta-amyloid peptide induced by binding of zinc(II) atoms. The efficiency of the deuterium/hydrogen exchange depended on the number of zinc atoms bound to the peptide and on the temperature of the ionization source region. Deuterium/hydrogen exchange reactions have been performed directly in the ionization source. The number of exchanges decreased considerably with an increasing numbers of zinc atoms. The relationship has been described with a damped exponential curve, which indicated that the binding of zinc atoms altered the conformation of the peptide ion by making it less open, which limits the access to inner areas of the molecule.

Rapid and reliable tumor tissue identification during surgical operations is a challenging problem especially in neurosurgery, where the tissue is formless, and precision of tumor/normal tissue border determination is vital. Recently we presented a tissue profiling method based on a combination of electrospray ionization and liquid extraction of phospholipids directly from tumor tissue, which allowed obtaining a mass spectrometric profile in less than a minute [1]. For rapid tumor type identification, we proposed a method based on a search through a reference database containing mass spectra of samples characterized by histopathological methods. To validate the results of tissue profiling we identified the features that forming the molecular profiles of meningioma samples by high-resolution mass spectrometry, which differs them from healthy brain tissue. Tumor samples were collected from dissected tissues (brain tumors) during neurosurgical operations in the N. N. Burdenko Scientific Research Neurosurgery Institute. Unmodified brain tissue samples were collected in the N. N. Burdenko Scientific Research Neurosurgery Institute during surgery of patients with drug-resistant epilepsy. New special spray-from-tissue ambient ion source [1] was used for tumor samples profiling. In this source, liquid extraction is immediately followed by ionization. For classification of tumor samples by lipid profiles a database filled with the results of the investigation from more than 100 brain tissue samples was created. High-resolution mass spectrometry data were obtained using Thermo LTQ FT Ultra mass spectrometer. For identification of potential biomarkers of meningioma molecular profiles of 28 meningioma samples was compared with profiles of nine unmodified brain samples. A number of features that differ tumor from healthy brain samples were identified and compared to the literature. The study was supported by Russian Scientific Foundation grant #16-15-10431.

Методом время-разрешенной микроволновой фотопроводимости в диапазоне 36 ГГц в интервале температур 200-300 K изучена кинетика гибели носителей тока в порошках Cu-Zn-Sn-Se, полученных ампульным твердофазным методом синтеза. Время жизни избыточных электронов при комнатной температуре оказалось меньше 5 нс. Энергия активации для процесса рекомбинации составила Ea~0.054 эВ. DOI: 10.21883/FTP.2017.01.8274