Microscope-Assisted Coronary Artery Bypass Grafting: Technique and Results

The microscope-assisted coronary artery bypass grafting (CABG) is a special technique of direct myocardial revascularization by the operating microscope using special equipment and atraumatic sutures. This method allows to complete elimination of technical errors during the performance of distal anastomoses and can be used to improve the outcomes and quality of conventional technique of operations. This article focuses on a detailed description of the technique for performing a distal anastomosis using a microsurgical technique and an operating microscope. Immediate results of operations are also reported. The data obtained suggest that microscope-assisted CABG is a safe, effective and reproducible procedure.

Correlated Time-0 and Hot-Carrier Stress Induced FinFET Parameter Variabilities: Modeling Approach

We identify correlation between the drain currents in pristine n-channel FinFET transistors and changes in time-0 currents induced by hot-carrier stress. To achieve this goal, we employ our statistical simulation model for hot-carrier degradation (HCD), which considers the effect of random dopants (RDs) on HCD. For this analysis we generate a set of 200 device instantiations where each of them has its own unique configuration of RDs. For all “samples” in this ensemble we calculate time-0 currents (i.e., currents in undamaged FinFETs) and then degradation characteristics such as changes in the linear drain current and device lifetimes. The robust correlation analysis allows us to identify correlation between transistor lifetimes and drain currents in unstressed devices, which implies that FinFETs with initially higher currents degrade faster, i.e., have more prominent linear drain current changes and shorter lifetimes. Another important result is that although at stress conditions the distribution of drain currents becomes wider with stress time, in the operating regime drain current variability diminishes. Finally, we show that if random traps are also taken into account, all the obtained trends remain the same.

FEATURES OF PHYSICAL ADAPTATION OF FIRST-YЕAR UNIVERSITY STUDENTS TO AN URBANIZЕD ЕNVIRONMЕNT

Aim. The article is aimed at evaluating physiological adaptation (physical development, physical fitness and sickness rate) in first-year female university students not involved in sports to the urban conditions of the Kirov region. Materials and methods. Five hundred and thirty first-year female students not involved in sports (Vyatka State University, Kirov) participated in the study. Their physical development was estimated with the help of five anthropometric and eight physiometric parameters used for calculating 24 indices. To assess physical fitness, five types of tests were performed measuring general stamina, quickness, strength and other parameters. To evaluate the influence of urban environment, the participants were divided into three groups depending on the population of their home cities: “big city”, “small town”, “village”. Results. First-year female students, who used to live in a big city before entering the university, have smaller chest circumference at rest and at maximum inhalation/exhalation than the girls of the same height and weight, who used to live in small towns or villages. Urban environment influences physical fitness, which results in generally low stamina and strength typical for females living in Kirov. Conclusion. The results obtained show that the increase in urbanization puts pressure on the mechanisms of physiological adaptation in first-year female students who used to live in small towns and villages before entering the university.

A Compact Quadrupole-Orbitrap Mass Spectrometer with FAIMS Interface Improves Proteome Coverage in Short LC Gradients

State-of-the-art proteomics-grade mass spectrometers can measure peptide precursors and their fragments with ppm mass accuracy at sequencing speeds of tens of peptides per second with attomolar sensitivity. Here we describe a compact and robust quadrupole-orbitrap mass spectrometer equipped with a front-end High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) Interface. The performance of the Orbitrap Exploris 480 mass spectrometer is evaluated in data-dependent acquisition (DDA) and data-independent acquisition (DIA) modes in combination with FAIMS. We demonstrate that different compensation voltages (CVs) for FAIMS are optimal for DDA and DIA, respectively. Combining DIA with FAIMS using single CVs, the instrument surpasses 2500 peptides identified per minute. This enables quantification of >5000 proteins with short online LC gradients delivered by the Evosep One LC system allowing acquisition of 60 samples per day. The raw sensitivity of the instrument is evaluated by analyzing 5 ng of a HeLa digest from which >1000 proteins were reproducibly identified with 5 min LC gradients using DIA-FAIMS. To demonstrate the versatility of the instrument, we recorded an organ-wide map of proteome expression across 12 rat tissues quantified by tandem mass tags and label-free quantification using DIA with FAIMS to a depth of >10,000 proteins.

Ion traps in modern mass spectrometry

This review is devoted to trapping mass spectrometry wherein ions are confined by electromagnetic fields for prolonged periods of time within limited volume, with mass measurement taking place within the same volume. Three major types of trapping mass spectrometers are discussed, specifically radiofrequency ion trap, Fourier transform ion cyclotron resonance and Orbitrap. While these three branches are intricately interwoven with each other over their recent history, they also differ greatly in their fundamentals, roots and historical origin. This diversity is reflected also in the difference of viewpoints from which each of these directions is addressed in this review. Following the theme of the issue, we focus on developments mainly associated with the country of Germany but, at the same time, we use this review as an illustration of the rapidly increasing globalization of science and expanding multi-national collaborations.

An Orbitrap-based laser desorption/ablation mass spectrometer designed for spaceflight

RATIONALE

The investigation of cryogenic planetary environments as potential harbors for extant life and/or contemporary sites of organic synthesis represents an emerging focal point in planetary exploration. Next generation instruments need to be capable of unambiguously determining elemental and/or molecular stoichiometry via highly accurate mass measurements and the separation of isobaric interferences.

METHODS

An Orbitrap™ analyzer adapted for spaceflight (referred to as the CosmOrbitrap), coupled with a commercial pulsed UV laser source (266 nm), was used to successfully characterize a variety of planetary analog samples via ultrahigh resolution laser desorption/ablation mass spectrometry. The materials analyzed in this study include: jarosite (a hydrous sulfate detected on Mars); magnesium sulfate (a potential component of the subsurface ocean on Europa); uracil (a nucleobase of RNA); and a variety of amino acids.

RESULTS

The instrument configuration tested here enables: measurement of major elements and organic molecules with ultrahigh mass resolution (m/Δm ≥ 120,000, FWHM); quantification of isotopic abundances with <1.0% (2σ) precision; and identification of highly accurate masses within 3.2 ppm of absolute values. The analysis of a residue of a dilute solution of amino acids demonstrates the capacity to detect twelve amino acids in positive ion mode at concentrations as low as ≤1 pmol/mm² while maintaining mass resolution and accuracy requirements.

CONCLUSIONS

The CosmOrbitrap mass analyzer is highly sensitive and delivers mass resolution/accuracy unmatched by any instrument sent into orbit or launched into deep space. This prototype instrument, which maps to a spaceflight implementation, represents a mission-enabling technology capable of advancing planetary exploration for decades to come.

Sequencing Grade Tandem Mass Spectrometry for Top-Down Proteomics Using Hybrid Electron Capture Dissociation Methods in a Benchtop Orbitrap Mass Spectrometer

Compared to traditional collision induced dissociation methods, electron capture dissociation (ECD) provides more comprehensive characterization of large peptides and proteins as well as preserves labile post-translational modifications. However, ECD experiments are generally restricted to the high magnetic fields of FTICR-MS that enable the reaction of large polycations and electrons. Here, we demonstrate the use of an electromagnetostatic ECD cell to perform ECD and hybrid ECD methods utilizing 193 nm photons (ECuvPD) or collisional activation (EChcD) in a benchtop quadrupole-Orbitrap mass spectrometer. The electromagnetostatic ECD cell was designed to replace the transfer octapole between the quadrupole and C-trap. This implementation enabled facile installation of the ECD cell, and ions could be independently subjected to ECD, UVPD, HCD, or any combination. Initial benchmarking and characterization of fragmentation propensities for ECD, ECuvPD, and EChcD were performed using ubiquitin (8.6 kDa). ECD yielded extensive sequence coverage for low charge states of ubiquitin as well as for the larger protein carbonic anhydrase II (29 kDa), indicating pseudo-activated ion conditions. Additionally, relatively high numbers of d- and w-ions enable differentiation of isobaric isoleucine and leucine residues and suggest a distribution of electron energies yield hot-ECD type fragmentation. We report the most comprehensive characterization to date for model proteins up to 29 kDa and a monoclonal antibody at the subunit level. ECD, ECuvPD, and EChcD yielded 93, 95, and 91% sequence coverage, respectively, for carbonic anhydrase II (29 kDa), and targeted online analyses of monoclonal antibody subunits yielded 86% overall antibody sequence coverage.

Dissecting ribosomal particles throughout the kingdoms of life using advanced hybrid mass spectrometry methods

Biomolecular mass spectrometry has matured strongly over the past decades and has now reached a stage where it can provide deep insights into the structure and composition of large cellular assemblies. Here, we describe a three-tiered hybrid mass spectrometry approach that enables the dissection of macromolecular complexes in order to complement structural studies. To demonstrate the capabilities of the approach, we investigate ribosomes, large ribonucleoprotein particles consisting of a multitude of protein and RNA subunits. We identify sites of sequence processing, protein post-translational modifications, and the assembly and stoichiometry of individual ribosomal proteins in four distinct ribosomal particles of bacterial, plant and human origin. Amongst others, we report extensive cysteine methylation in the zinc finger domain of the human S27 protein, the heptameric stoichiometry of the chloroplastic stalk complex, the heterogeneous composition of human 40S ribosomal subunits and their association to the CrPV, and HCV internal ribosome entry site RNAs.

Patterns of sensitization to inhalant and food allergens among pediatric patients from the Moscow region (Russian Federation)

The immunological profiles of human specific IgE (sIgE) and specific IgG4 (sIgG4) vary by genetic predisposition, living conditions in different geographical locations and patient’s age. The aim of our study was to analyze sIgE and sIgG4 patterns and their age-dependent changes in patients from the Moscow region. For identifying sIgE and sIgG4 profiles the blood samples from 513 patients aged 6 months to 17 years who were showing symptoms of allergic diseases were analyzed using microarrays containing 31 allergens. The highest sIgE prevalence was observed for birch pollen (32%) among pollen allergens, cat dander (24%) among indoor allergens, and egg whites (21%) among food allergens. The most common sIgG4 response was developed toward egg whites (80% of patients). Age-related elevation was identified for patients with increased sIgE to pollen allergens and indoor allergens (cat or dog dander and house dust mites). For each allergen, the proportion of cases with significant levels of sIgG4 appeared to increase with patients’ age. The data on allergen-specific sIgE and sIgG4 prevalence show both general trends and some local special aspects that are indicative for the Moscow region. This information should be useful in terms of epidemiology of allergic diseases.

Petroleomics via Orbitrap mass spectrometry with resolving power above 1 000 000 at m/z 200

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches. Pertinent parameters that underpin the main figures of merit, that is, signal to noise ratios, dynamic range, spectral error, scan speed, mass accuracy and mass resolving power = R_p, and provide subsidies to develop these analyzers were tested. Comparisons are made with data obtained using the most common petroleomics instrument, which is a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), that has been used in the last decade in our laboratory for crude oil analysis providing R_p of 340 000 at m/z 400 with transients of 3 s duration, and has been extensively demonstrated to fulfill all major requirements for precise petroleomics investigations. The high-field compact MegaOrbitrap mass analyzer, when operated at an R_p = 840 000 at m/z 400 (R_p > 1 000 000 at m/z 200) with a detection time of 3 s, was found to be well suited for adequate characterization of crude oil. Accurate class classification and mass accuracy below 1 ppm was obtained leading to proper, comprehensive petroleomics characterization.

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches.

Engineering Nanodisc Scaffold Proteins for Native Mass Spectrometry

Lipoprotein nanodiscs are ideally suited for native mass spectrometry because they provide a relatively monodisperse nanoscale lipid bilayer environment for delivering membrane proteins into the gas phase. However, native mass spectrometry of nanodiscs produces complex spectra that can be challenging to assign unambiguously. To simplify interpretation of nanodisc spectra, we engineered a series of mutant membrane scaffold proteins (MSP) that do not affect nanodisc formation but shift the masses of nanodiscs in a controllable way, eliminating isobaric interference from the lipids. Moreover, by mixing two different belts before assembly, the stoichiometry of MSP is encoded in the peak shape, which allows the stoichiometry to be assigned unambiguously from a single spectrum. Finally, we demonstrate the use of mixed belt nanodiscs with embedded membrane proteins to confirm the dissociation of MSP prior to desolvation.

Top-down analysis of immunoglobulin G isotypes 1 and 2 with electron transfer dissociation on a high-field Orbitrap mass spectrometer

The increasing importance of immunoglobulins G (IgGs) as biotherapeutics calls for improved structural characterization methods designed for these large (~150kDa) macromolecules. Analysis workflows have to be rapid, robust, and require minimal sample preparation. In a previous work we showed the potential of Orbitrap Fourier transform mass spectrometry (FTMS) combined with electron transfer dissociation (ETD) for the top-down investigation of an intact IgG1, resulting in ~30% sequence coverage. Here, we describe a top-down analysis of two IgGs1 (adalimumab and trastuzumab) and one IgG2 (panitumumab) performed with ETD on a mass spectrometer equipped with a high-field Orbitrap mass analyzer. For the IgGs1, sequence coverage comparable to the previous results was achieved in a two-fold reduced number of summed transients, which corresponds, taken together with the significantly increased spectra acquisition rate, to ~six-fold improvement in analysis time. Furthermore, we studied the influence of ion-ion interaction times on ETD product ions for IgGs1, and the differences in fragmentation behavior between IgGs1 and IgG2, which present structural differences. Overall, these results reinforce the hypothesis that gas phase dissociation using both energy threshold-based and radical-driven ion activations is directed to specific regions of the polypeptide chains mostly by the location of disulfide bonds.

SIGNIFICANCE OF THE STUDY

Compared with our previous report, the results presented herein demonstrate the power of technological advances of the next generation Orbitrap™ platform, including the use of a high-field compact (i.e., D20) Orbitrap mass analyzer, and a dedicated manipulation strategy for large protein ions (via their trapping in the HCD collision cell along with reduction of the pressure in the cell). Notably, these important developments became recently commercially available in the top-end Orbitrap platforms under the name of "Protein Mode". Furthermore, we continued exploring the advantages offered by the summation (averaging) of transients (time-domain data) for improving the signal-to-noise ratio of top-down mass spectra. Finally, for the first time we report the application of the hybrid ion activation technique that combines electron transfer dissociation and higher energy collisional dissociation, known as EThcD, on intact monoclonal antibodies. Under these specific instrumental parameters, EThcD produces a partially complementary fragmentation pattern compared to ETD, increasing the overall sequence coverage especially at the protein termini.