Egg vs. Oil in the Cookbook of Plasters: Differentiation of Lipid Binders in Wall Paintings Using Gas Chromatography-Mass Spectrometry and Principal Component Analysis.

Wall paintings are integral to cultural heritage and offer rich insights into historical and religious beliefs. There exist various wall painting techniques that pose challenges in binder and pigment identification, especially in the case of egg/oil-based binders. GC-MS identification of lipidic binders relies routinely on parameters like the ratios of fatty acids within the plaster. However, the reliability of these ratios for binder identification is severely limited, as demonstrated in this manuscript. Therefore, a more reliable tool for effective differentiation between egg and oil binders based on a combination of diagnostic values, specific markers (cholesterol oxidation products), and PCA is presented in this study. Reference samples of wall paintings with egg and linseed oil binders with six different pigments were subjected to modern artificial ageing methods and subsequently analysed using two GC-MS instruments. A statistically significant difference (at a 95% confidence level) between the egg and oil binders and between the results from two GC-MS instruments was observed. These discrepancies between the results from the two GC-MS instruments are likely attributed to the heterogeneity of the samples with egg and oil binders. This study highlights the complexities in identifying wall painting binders and the need for innovative and revised analytical methods in conservation efforts.

A pathological lesion or a postmortem artefact? An interdisciplinary approach to deal with an interesting early medieval case.

OBJECTIVE: This study evaluates a case of pseudopathology and the effects that postmortem taphonomic changes and environmental influences can have on bone. MATERIAL: A skeleton of a young male from the early medieval site Staré Mesto, dated to the 9th-10th century CE. METHODS: The skeletal remains were subjected to detailed macroscopic and X-ray examination, and then a CT scan and XRF analysis were performed. RESULTS: X-ray examination of the mandible revealed unusually dense structures, whose appearance was not consistent with any known pathology. Based on the results of CT scanning, it was hypothesized that these were cavities filled with alluvial sediment. X-ray fluorescence spectrometry (XRF), focusing on the determination of the silica content, revealed a high intensity of silica in the samples of the affected area of the bone. CONCLUSION: The hypothesis that the inclusions were composed of waterborne sediment was supported. SIGNIFICANCE: Although it is well known that soil can infiltrate bones buried in the ground, its appearance on plain radiographs is not that commonly known. The case illustrates the usefulness of differentiating true pathologies from postmortem alterations to avoid inappropriate interpretations. LIMITATIONS: No similar cases have been described. SUGGESTION FOR FURTHER RESEARCH: In palaeopathological evaluation, the use of multiple imaging and evaluative techniques should be implemented to differentiate pathological lesions from pseudopathology.

Spatial Analysis of Nucleotide Metabolism: From CRISPR Knockout Cancer Cells to MALDI Imaging of Tumors.

Cancer cells depend on nucleotides for proliferation. Inhibition of nucleotide metabolism by antimetabolites is a well-established anticancer therapy. However, resistance and toxicity to antimetabolite treatments reduce their effectiveness. Here, we focus on the pyrimidine de novo synthesis pathway, which is crucial for cancer cell proliferation, yet its pharmacological targeting in cancer has been without much clinical success so far. Hence, it is important to understand how cancer cells cope with the insufficiency of this pathway. Here, we describe a procedure to prepare subcutaneous tumor model deficient in de novo pyrimidine synthesis. For examination of metabolic responses to de novo synthesis blockade in tumors, we propose application of MALDI imaging that allows spatially resolved examination of metabolic responses to de novo synthesis blockade in tumors.

Secret Recipe Revealed: Chemical Evaluation of Raw Colouring Mixtures from Early 19th Century Moravia.

An archaeological excavation in Prostejov (Czech Republic) revealed a workshop of a local potter with colourless, pink, and blue powders presumably used to produce faience/surface decoration. A comprehensive analytical study, which combined elemental and molecular analysis techniques, was performed to shed light on the chemical composition of these unique findings. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM EDX), inductively coupled-plasma mass spectrometry (ICP MS), flow injection analysis (FIA) with electrospray ionisation mass spectrometry (ESI MS), laser desorption ionisation mass spectrometry (LDI MS), and Raman spectroscopy were applied to reveal the elemental composition of the powders and identify the colouring agents in the pink and blue powders. The colouring agents in the pink powder were probably iron and the agent in the blue powder is Prussian blue. On top of that, it was also possible to determine the organic additives in these powders through pyrolysis gas chromatography with mass spectrometric detection (Py GC/MS), atmospheric solids analysis probe ion mobility mass spectrometry (ASAP IM MS), and LDI MS. The organic constituents were identified as plant resin, beeswax, and fats. These results point to the preparation of faience/pigment mixtures as oil paint.

A mixture of innate cryoprotectants is key for freeze tolerance and cryopreservation of a drosophilid fly larva.

Insects that naturally tolerate internal freezing produce complex mixtures of multiple cryoprotectants (CPs). Better knowledge on composition of these mixtures, and on the mechanisms of individual CP interactions, could inspire development of laboratory CP formulations optimized for cryopreservation of cells and other biological material. Here, we identify and quantify (using high resolution mass spectrometry) a range of putative CPs in larval tissues of a subarctic fly, Chymomyza costata, which survives long-term cryopreservation in liquid nitrogen. The CPs proline, trehalose, glutamine, asparagine, glycine betaine, glycerophosphoethanolamine, glycerophosphocholine and sarcosine accumulate in hemolymph in a ratio of 313:108:55:26:6:4:2.9:0.5 mmol l-1. Using calorimetry, we show that artificial mixtures, mimicking the concentrations of major CPs in hemolymph of freeze-tolerant larvae, suppress the melting point of water and significantly reduce the ice fraction. We demonstrate in a bioassay that mixtures of CPs administered through the diet act synergistically rather than additively to enable cryopreservation of otherwise freeze-sensitive larvae. Using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), we show that during slow extracellular freezing trehalose becomes concentrated in partially dehydrated hemolymph where it stimulates transition to the amorphous glass phase. In contrast, proline moves to the boundary between extracellular ice and dehydrated hemolymph and tissues where it probably forms a layer of dense viscoelastic liquid. We propose that amorphous glass and viscoelastic liquids may protect macromolecules and cells from thermomechanical shocks associated with freezing and transfer into and out of liquid nitrogen.

Dual-polarity MALDI mass spectrometry and imaging of oil binders and fatty acids in artworks using cyanographene as a single matrix.

Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and imaging mass spectrometry (IMS) are being increasingly recognized for the detection and visualization of various organic species including lipids and fatty acids. Nevertheless, most MALDI matrices perform optimally in one ionization mode. This study investigates the performance of cyano derivative of graphene (G-CN) as a matrix in two polarities of MALDI MS and IMS for the detection of oil binders and fatty acids in artworks, and compares it with classical MALDI matrices (2,5-dihydroxybenzoic acid, 9-aminoacridine). Results revealed the ability of G-CN to provide high quality positive and negative mass spectra of oils and fatty acids, respectively, with lowest matrix-induced interferences among tested matrices and minimal effects of the presence of inorganic pigments. The newly developed approach makes both oil and fatty acid identifiable in a single spot simply by covering the sample surface with one matrix and switching the polarity in MALDI without any sample manipulation. G-CN offers effective matrix to analyte energy transfer, ability to detect components in less than 100 ng of oil at a MALDI spot and lesser analyte fragmentation than the compared conventional matrices. Furthermore, it enables direct mapping of specific m/z features corresponding to triacylglycerol (TAG), products of TAG oxidation and deprotonated acids using one nanoparticle matrix in MALDI IMS. This research shows potential for technical innovations in the study of art micro-environments and degradation phenomena of historical artworks.

Activation of the integrated stress response confers vulnerability to mitoribosome-targeting antibiotics in melanoma.

The ability to adapt to environmental stress, including therapeutic insult, contributes to tumor evolution and drug resistance. In suboptimal conditions, the integrated stress response (ISR) promotes survival by dampening cytosolic translation. We show that ISR-dependent survival also relies on a concomitant up-regulation of mitochondrial protein synthesis, a vulnerability that can be exploited using mitoribosome-targeting antibiotics. Accordingly, such agents sensitized to MAPK inhibition, thus preventing the development of resistance in BRAFV600E melanoma models. Additionally, this treatment compromised the growth of melanomas that exhibited elevated ISR activity and resistance to both immunotherapy and targeted therapy. In keeping with this, pharmacological inactivation of ISR, or silencing of ATF4, rescued the antitumoral response to the tetracyclines. Moreover, a melanoma patient exposed to doxycycline experienced complete and long-lasting response of a treatment-resistant lesion. Our study indicates that the repurposing of mitoribosome-targeting antibiotics offers a rational salvage strategy for targeted therapy in BRAF mutant melanoma and a therapeutic option for NRAS-driven and immunotherapy-resistant tumors.

First Evidence of "Earth Wax" Inside the Casting Molds from the Roman Era.

This research was focused on the analysis of material composition and organic residues present in three molds found in the Moravian region (Czech Republic) belonging to the Roman era. X-ray fluorescence spectroscopy pointed out the possible remelting of Roman objects in Barbarian territory. The analysis of organic residues retrieved from the internal part of mold #2 by pyrolysis-gas chromatography/mass spectrometry proved the presence of ozokerite wax ("earth wax"). Consequent analysis of this organic residue by Atmospheric Solids Analysis Probe-ion mobility spectrometry-high-resolution mass spectrometry (ASAP-IMS-HRMS) confirmed the presence of ceresin, the main component of ozokerite. Ceresin was also detected in a sample of the organic residue from mold #1. Note that this is the first application of ASAP-IMS-HRMS in archaeological research. The remains of earth wax in molds suggest the production of wax models as an intermediate stage for the production of lost-wax ceramic casting molds.

What about Dinner? Chemical and Microresidue Analysis Reveals the Function of Late Neolithic Ceramic Pans.

The Late Neolithic palafitte site, Ustie na Drim, in the northern part of Lake Ohrid (North Macedonia), excavated in 1962, offered ceramic fragments of large, flat, elongated pans. These artifacts could be dated by relative chronology to roughly around 5200-5000 BC. According to their shape and technological traits, the ceramic pans were probably used for baking. The attached materials on the surface of studied pan fragments were sampled for consequent chemical and microscopical analyses (i.e., analyses of starch, phytoliths, and microscopic animal remains). An immunological method revealed the presence of pork proteins in samples. The presence of organic residues of animal origin was, moreover, confirmed by the detection of cholesterol using gas chromatography coupled to mass spectrometry. Analysis of detected microscopic botanical objects revealed starch grains of several plants (i.e., oak, cattail, and grasses). An interesting find was the hair of a beetle larva, which could be interpreted contextually as the khapra beetle, a pest of grain and flour. Based on our data, we suppose that the ceramic pans from Ustie na Drim were used for the preparation of meals containing meat from common livestock in combination with cereals and wild plants.

Study of Tetrahydroxylated Anthraquinones-Potential Tool to Assess Degradation of Anthocyanins Rich Food.

Degradation of anthocyanins involves scission of the flavonoid skeleton yielding 2,4,6-trihydroxybenzaldehyde (phloroglucinaldehyde, PGA) and a phenolic acid. However, the process is not finished with the formation of PGA, as the consequent condensation of two PGA molecules providing colored hydroxylated anthraquinones was observed for the first time. This process was studied using a combination of preparative column chromatography, nuclear magnetic resonance, liquid chromatography/high resolution tandem mass spectrometry (LC/HRMS2), and quantum calculations using density functional theory. 1,3,5,7-tetrahydroxyanthraquinone (anthrachrysone) and its isomers were found to rise during heating (95 °C) in a buffered PGA model solution (phosphate buffer, pH 7). These compounds were detected in heated red wine after an increase of its pH value. The concentration of the identified anthrachrysone in the red wine reached 0.01 mg·L-1. Presence of those compounds could therefore indicate involvement of certain steps in the processing of plant materials rich in anthocyanins (e.g., utilization of a higher temperature and/or reduction of acidity) or long-term transformation of anthocyanins (potentially, for instance, in archaeological findings such as wine or fruit residues). Additionally, measurement of wine-soil suspensions proved an increase of their pH to the values suitable for anthocyanin cleavage (neutral to slightly alkaline; reached using soil from archaeologically well-known Bull Rock Cave). Although not found in artificially prepared samples (imitations) or authentic materials so far, according to our results the above mentioned conditions are suitable for the formation of tetrahydroxylated anthraquinone derivatives and their monitoring would be beneficial.

Biphasic calcium phosphate scaffolds with controlled pore size distribution prepared by in-situ foaming.

In this study, a reproducible method of fabricating hierarchically 3D porous scaffolds with high porosity and pore interconnectivity is reported. The method is based on in-situ foaming of a dispersion of diisocyanate, polyol, water and hydroxyapatite (HA) to form a hard foamed HA/polyurethane composite which after heat treatment provided a bi-phase calcium phosphate scaffold. This technique, combining the advantages of polymer sponge and direct foaming methods, provides a better control over the macrostructure of the scaffold. A modification of the multi-scaled porous macrostructure of scaffolds produced by changing the ratio of input reactants and by sintering temperature was studied. The pore morphology, size, and distribution were characterized using a scanning electron microscope and mercury porosimetry. The pores were open and interconnected with multi-scale (from several nanometres to millimetres) sizes convenient for using in tissue engineering applications. The bioactivity was confirmed by growing an apatite layer on the surfaces after immersion in simulated body fluid. The material was biocompatible, as shown by using normal human adipose tissue-derived stem cells (ASC). When seeded onto the scaffolds, the ASC adhered and remained healthy while maintaining their typical morphology.

Determination of Milk Products in Ceramic Vessels of Corded Ware Culture from a Late Eneolithic Burial.

In this study, a soil from two ceramic vessels belonging to Corded Ware culture, 2707⁻2571 B.C., found in a cremation grave discovered in Central Moravia, Czech Republic, was analyzed using matrix-assisted laser desorption/ionization⁻mass spectrometry (MALDI⁻MS) combined with advanced statistical treatment (principal component analysis, PCA, and orthogonal projection to latent structures discriminant analysis, OPLS-DA) and by enzyme-linked immunosorbent assay (ELISA). MALDI⁻MS revealed the presence of triacylglycerols in both vessels. This analytical technique was used for the analysis of the soil content from archaeological ceramic vessels for the first time. Targeted ELISA experiments consequently proved the presence of milk proteins in both ceramic vessels. These results represent the first direct evidence of the use of milk or dairy products in the Eneolithic period in Moravian Corded Ware Culture and help to better understand the diet habits and living conditions of Eneolithic populations in Central Europe.

Intact Cell Mass Spectrometry as a Quality Control Tool for Revealing Minute Phenotypic Changes of Cultured Human Embryonic Stem Cells.

The stability of in vitro cell cultures is an important issue for any clinical, bio-industrial, or pharmacological use. Embryonic stem cells are pluripotent; consequently, they possess the ability to differentiate into all three germ layers and are inherently prone to respond to differentiation stimuli. However, long-term culture inevitably yields clones that are best adapted to the culture conditions, passaging regimes, or differentiation sensitivity. This cellular plasticity is a major obstacle in the development of bio-industrial or clinical-grade cultures. At present, the quality control of cell cultures is limited by the lack of reliable (epi)genetic or molecular markers or by the focus on a particular type of instability such as karyotype abnormalities or adverse phenotypic traits. Therefore, there is an ongoing need for robust, feasible, and sensitive methods of determining or confirming cell status and for revealing potential divergences from the optimal state. We modeled both intrinsic and extrinsic changes in human embryonic stem cell (hESC) states using different experimental strategies and addressed the changes in cell status by intact cell mass spectrometry fingerprinting. The analysis of spectral fingerprints by methods routinely used in analytical chemistry clearly distinguished the morphologically and biochemically similar populations of hESCs and provided a biomarker-independent tool for the quality control of cell culture. Stem Cells Translational Medicine 2018;7:109-114.

Semisynthesis and spectral characterization of 5-methylpyranopelargonidin and 4-methylfuropelargonidin and their separation and detection in strawberry fruit wine.

Condensation of anthocyanins and their aglycons with small organic molecules yields more stable natural dyes, e.g. pyranoanthocyanins arising spontaneously in various food products. Reaction of pelargonidin with acetone produces two isomeric anthocyanidin dyes - 5-methylpyranopelargonidin and 4-methylfuropelargonidin. A robust semipreparative liquid chromatographic method was developed to isolate both derivatives from a simple aged solution of pelargonidin in methanol: acetone: 37% aqueous hydrochloric acid (1:1:0.008, v/v/v). Detailed interpretation of mass and nuclear magnetic resonance spectra allowed to assign structures of both dyes in isolated fractions. A fast UHPLC-MS method was optimized for the control of their production in the reaction mixture. Use of reversed stationary phase and acidic mobile phases in gradient mode allowed separation of both isomers in less than one minute. Fragmentation of both dyes after collision activated dissociation in collision cell was studied comprehensively and the observed processes were compared with data from quantum calculations (computational chemistry utilizing DFT methods). When comparing both isomers, retro-Diels-Alder fragmentation appears preferred in furo-derivative, while small losses (i.e. methane and water molecules) were more pronounced in pyrano-derivative. Both studied isomeric dyes were found in laboratory prepared strawberry fruit wine and their content was compared with major present anthocyanins and their derivatives.

Clusters of Monoisotopic Elements for Calibration in (TOF) Mass Spectrometry.

Precise calibration in TOF MS requires suitable and reliable standards, which are not always available for high masses. We evaluated inorganic clusters of the monoisotopic elements gold and phosphorus (Au n+/Au n- and P n+/P n-) as an alternative to peptides or proteins for the external and internal calibration of mass spectra in various experimental and instrumental scenarios. Monoisotopic gold or phosphorus clusters can be easily generated in situ from suitable precursors by laser desorption/ionization (LDI) or matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Their use offers numerous advantages, including simplicity of preparation, biological inertness, and exact mass determination even at lower mass resolution. We used citrate-stabilized gold nanoparticles to generate gold calibration clusters, and red phosphorus powder to generate phosphorus clusters. Both elements can be added to samples to perform internal calibration up to mass-to-charge (m/z) 10-15,000 without significantly interfering with the analyte. We demonstrated the use of the gold and phosphorous clusters in the MS analysis of complex biological samples, including microbial standards and total extracts of mouse embryonic fibroblasts. We believe that clusters of monoisotopic elements could be used as generally applicable calibrants for complex biological samples. Graphical Abstract ᅟ.

Liquid chromatography/high resolution tandem mass spectrometry - Tool for the study of polyphenol profile changes during micro-scale biogas digestion of grape marcs.

A microscale discontinuous fermenter was used for anaerobic digestion of wine waste - a hardly gasifiable feedstock material. Efficiency of biogas production, i.e. changes in content of nitrogen, oxygen, carbon dioxide and methane in gas phase, was monitored by gas chromatography/mass spectrometry. Liquid chromatography/high resolution tandem mass spectrometry in combination with principal component analysis and orthogonal projection to latent structures was used to reveal main chemical differences of gasified wine waste mixture from commonly used ones in agricultural biogas plants. Compounds with particular polyphenolic structures appeared among the most distinctive markers. Analysis of samples collected during acidogenic phase and unstabilized methanogenesis indicates formation of certain dihydro-flavonoids in early stages of the process and their consequent degradation. Due to formerly described higher toxicity of some dihydroflavonoids (e.g. taxifolin) compared to their more common counterparts (e.g. quercetin, malvidin etc.), unstabilized digestate would represent a potential environmental risk when used as a fertilizer deserving a proper control.

Analytical and semipreparative chiral separation of cis-itraconazole on cellulose stationary phases by high-performance liquid chromatography.

cis-Itraconazole is a chiral antifungal drug administered as a racemate. The knowledge of properties of individual cis-itraconazole stereoisomers is vital information for medicine and biosciences as different stereoisomers of cis-itraconazole may possess different affinity to certain biological pathways in the human body. For this purpose, either chiral synthesis of enantiomers or chiral separation of racemate can be used. This paper presents a two-step high-performance liquid chromatography approach for the semipreparative isolation of four stereoisomers (two enantiomeric pairs) of itraconazole using polysaccharide stationary phases and volatile organic mobile phases without additives in isocratic mode. The approach used involves the separation of the racemate into three fractions (i.e. two pure stereoisomers and one mixed fraction containing the remaining two stereoisomers) in the first run and consequent separation of the collected mixed fraction in the second one. For this purpose, combination of cellulose tris-(4-methylbenzoate) and cellulose tris-(3,5-dimehylphenylcarbamate) columns with complementary selectivity for cis-itraconazole provided full separation of all four stereoisomers (with purity of each isomer > 97%). The stereoisomers were collected, their optical rotation determined and their identity confirmed based on the results of a previously published study. Pure separated stereoisomers are subjected to further biological studies.

Multivariate Calibration Approach for Quantitative Determination of Cell-Line Cross Contamination by Intact Cell Mass Spectrometry and Artificial Neural Networks.

Cross-contamination of eukaryotic cell lines used in biomedical research represents a highly relevant problem. Analysis of repetitive DNA sequences, such as Short Tandem Repeats (STR), or Simple Sequence Repeats (SSR), is a widely accepted, simple, and commercially available technique to authenticate cell lines. However, it provides only qualitative information that depends on the extent of reference databases for interpretation. In this work, we developed and validated a rapid and routinely applicable method for evaluation of cell culture cross-contamination levels based on mass spectrometric fingerprints of intact mammalian cells coupled with artificial neural networks (ANNs). We used human embryonic stem cells (hESCs) contaminated by either mouse embryonic stem cells (mESCs) or mouse embryonic fibroblasts (MEFs) as a model. We determined the contamination level using a mass spectra database of known calibration mixtures that served as training input for an ANN. The ANN was then capable of correct quantification of the level of contamination of hESCs by mESCs or MEFs. We demonstrate that MS analysis, when linked to proper mathematical instruments, is a tangible tool for unraveling and quantifying heterogeneity in cell cultures. The analysis is applicable in routine scenarios for cell authentication and/or cell phenotyping in general.

Study of composition of espresso coffee prepared from various roast degrees of Coffea arabica L. coffee beans.

Espresso coffee samples prepared at various roasting degrees defined according to its basic conventional classification (light, medium, medium-dark and dark roasted) were analyzed by ultra-performance liquid chromatography/tandem mass spectrometry. Obtained raw data were processed using multivariate statistical analysis (Principal Component Analysis, PCA) to evaluate chemical differences between each roasting degrees (untargeted part of study). All four roasting degrees were resolved in appropriate Score plot. Orthogonal Projections to Latent Structures provided signals of significant markers describing the differences among particular roasting degrees. Detailed interpretation of those signals by targeted LC/MS(2) analysis revealed four groups of compounds. The first two groups involve chlorogenic acids and related lactones. The signals of other two sets of markers were ascribed to some specific atractylosides and particular melanoidins. Ratios of contents of selected representatives of each group to the sum of all identified markers were proposed as definite parameters for determination of roasting degree of Brazilian coffee Arabica.

Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3µm, core-shell particles Kinetex C18, dp=2.6µm (100µm i.d.) and monolithic column Chromolith CapRod (100µm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3µm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace.