Dissociation of Biomolecules by an Intense Low-Energy Electron Beam in a High Sensitivity Time-of-Flight Mass Spectrometer.

We report the progress on an electron-activated dissociation (EAD) device coupled to a quadrupole TOF mass spectrometer (QqTOF MS) developed in our group. This device features a new electron beam optics design allowing up to 100 times stronger electron currents in the reaction cell. The electron beam current reached the space-charge limit of 0.

[Biophysical mechanisms of dehydration of nasal cavity secretion in inflammatory diseases of the upper respiratory tract].

The purpose of the study is an experimental-theoretical study of the mechanisms of structuring the secretion of the nasal cavity, in the process of its dehydration in inflammatory diseases of the upper respiratory tract. The work shows the general patterns of dehydration of natural biological fluids and their model solutions. Simulation of dehydration of the secret allowed us to identify the most informative parameters of changes in its composition in pathology and to develop criteria for diagnosing the inflammatory process of the VDP using the wedge-shaped dehydration method.

[The question about the topical antibiotic therapy of acute rhinosinusitis].

Presented the results of the clinical study of 30 patients with moderate rhinosinusitis (13 (43.3%) men, 17 (56.7%) women, age from 18 to 68 years).

[Single-stage open tympanoplasty in the form of tympanosclerosis with fixation of the stapes].

We used several variants of one-stage tympanoplasty, including our own method, according to which, in the absence of an anvil and malleus after mobilisation of the stapes, ossiculoplasty with partial or complete ossicular prosthesis and myringoplasty simultaneously preventively created a support (neo-malleus) in the thickness of the neotympanic membrane. To assess the effectiveness of different variants of single-stage tympanoplasty, the long-term functional results were compared in terms of 6 to 12 months after the intervention with preoperative indicators. Standard methods of statistical estimation with calculation of descriptive statistics and methods of statistical hypothesis testing based on nonparametric Wilcoxon criterion for related samples were used.

[Skull base defects multilayer plasty in patients with spontaneous cerebrospinal fluid leak: our experience].

Spontaneous cerebrospinal fluid (CSF) leak is one of the types of non-traumatic CSF leaks in which the etiologic factor is unknown. Skull base defects transnasal endoscopic plasty is the initial method of surgical repair of spontaneous cerebrospinal fluid leaks. METHODS: Forty-five patients with spontaneous CSF leaks were managed using multilayer transplant technique.

A W-Geometry Ortho-TOF MS with High Resolution and Up to 100% Duty Cycle for MS/MS.

Orthogonal injection time-of-flight (orthoTOF) mass spectrometry (MS) is the most prevalent form of TOFMS, owing to its greater control over incoming ion energy, the ability to correct for aberrations in incoming ion velocity and position, and its ability to provide an entire mass spectrum within a single scan. However, the duty cycle of orthoTOFMS is low compared with scanning analyzers, which can have 100% duty cycle when measuring a single type of ion. Typical duty cycles for orthoTOFMS range from 1% to 30%, depending on instrument geometry.

Differential Mobility Spectrometry-Hydrogen Deuterium Exchange (DMS-HDX) as a Probe of Protein Conformation in Solution.

Differential mobility spectrometry (DMS) is an ion mobility technique that has been adopted chiefly as a pre-filter for small- to medium-sized analytes (<1 000 Da). With the exception of a handful of studies that employ an analogue of DMS-field asymmetric waveform ion mobility spectroscopy (FAIMS)-the application of DMS to intact biomacromolecules remains largely unexplored. In this work, we employ DMS combined with gas-phase hydrogen deuterium exchange (DMS-HDX) to probe the gas-phase conformations generated from proteins that were initially folded, partially-folded, and unfolded in solution.

[The intraoperative monitoring of the gas pressure in the middle ear].

The objective of the present work was to elucidate the patterns and mechanisms underlying the changes of gas pressure in the middle ear during the operation of stapedoplasty with a view to the application of the data obtained for objective recording of the stapedial reflex at the time of surgical intervention. Ten subjects with the unaffected hearing function were recruited for the study. Tympanometry was carried out at one-minute intervals starting from the onset of feeding nitrogen monooxide till the completion of septoplasty.

A novel ion trap that enables high duty cycle and wide m/z range on an orthogonal injection TOF mass spectrometer.

Although TOF analyzers with orthogonal ion injection provide the whole spectrum without scanning, their duty cycle is low compared with scanning analyzers in single ion monitoring mode. Typical duty cycle is in the range of 5% to 30% depending on the instrument geometry and ion m/z value. We present here a novel trapping/releasing setup, which offers the duty cycle near 100% over a wide range.

[Use of autotransplants and implants in ossiculoplasty].

The paper presents a comparative analysis of efficacy of ossiculoplasty (OP) using different transplants. A total of 202 operations were performed. Prostheses made of the fragments of the auditory ossicles, or a cortical layer of the temporal bone (n=81), of nail plate (n=56), titanium implants (n=65) were applied.

Electrospray ionization mass spectrometry and ion mobility analysis of the 20S proteasome complex.

Mass spectrometry and gas phase ion mobility [gas phase electrophoretic macromolecule analyzer (GEMMA)] with electrospray ionization were used to characterize the structure of the noncovalent 28-subunit 20S proteasome from Methanosarcina thermophila and rabbit. ESI-MS measurements with a quadrupole time-of-flight analyzer of the 192 kDa alpha7-ring and the intact 690 kDa alpha7beta7beta7alpha7 are consistent with their expected stoichiometries. Collisionally activated dissociation of the 20S gas phase complex yields loss of individual alpha-subunits only, and it is generally consistent with the known alpha7beta7beta7alpha7 architecture.

Nanospray 'taxation' and how to avoid it.

In mass spectrometric analysis with nanospray ionization, some analytes were found to appear in spectra with a delay of tens of minutes, while a few others could not be detected at all. The effect was found to be related to cation-exchange chromatography with negative charge on the glass surface, and with the most affected peptide or protein ions having strong localization of positive charge in blocks of two or more adjacent basic amino acid residues (e.g.

Collisional cooling of large ions in electrospray mass spectrometry.

Collisional cooling of ions in the rf-only multipole guides has become a method of choice for coupling electrospray sources to various mass analyzers. Normally parameters of such ion guides (length, pressure) provide enough thermalization and focusing for ions in a wide mass range. Noncovalent complexes, however, have more compact conformations than denatured biomolecules of similar mass and, therefore may not be transmitted efficiently through standard ion guides, as demonstrated by theoretical analysis, simulations, and experiments.

A high-performance matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometer with collisional cooling.

A high-performance orthogonal time-of-flight (TOF) mass spectrometer was developed specifically for use in combination with a matrix-assisted laser desorption/ionization (MALDI) source. The MALDI source features an ionization region containing a buffer gas with variable pressure. The source is interfaced to the TOF section via a collisional focusing ion guide.

Charge state separation for protein applications using a quadrupole time-of-flight mass spectrometer.

A novel method for separating ions according to their charge state using a quadrupole time-of-flight mass spectrometer is presented. The benefits of charge state separation are particularly apparent in protein identification applications at low femtomole concentration levels, where in conventional TOF MS spectra peptide ions are often lost in a sea of chemical noise. When doubly and triply charged tryptic peptide ions need to be filtered from singly charged background ions, the latter are suppressed by two to three orders of magnitude, while from 10-50% of multiply charged ions remain.

Quantitative profiling of phospholipids by multiple precursor ion scanning on a hybrid quadrupole time-of-flight mass spectrometer.

A hybrid quadrupole time-of-flight mass spectrometer featured with ion trapping capabilities was employed for quantitative profiling of total extracts of endogenous phospholipids. Simultaneous acquisition of precursor ion spectra of multiple fragment ions allowed detection of major classes of phospholipids in a single experiment. Relative changes in their concentration were monitored using a mixture of isotopically labeled endogenous lipids as a comprehensive internal standard.

An introduction to quadrupole-time-of-flight mass spectrometry.

A brief introduction is presented to the basic principles and application of a quadrupole-time-of-flight (TOF) tandem mass spectrometer. The main features of reflecting TOF instruments with orthogonal injection of ions are discussed. Their operation and performance are compared with those of triple quadrupoles with electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) TOF mass spectrometers.

Determination of the complete amino acid sequence for the coat protein of brome mosaic virus by time-of-flight mass spectrometry. Evidence for mutations associated with change of propagation host.

Time-of-flight mass spectrometry (TOFMS) has been applied to determine the complete coat protein amino acid sequences of a number of distinct brome mosaic virus (BMV) isolates. Ionization was carried out by both electrospray ionization and matrix-assisted laser desorption/ionization (MALDI). After determining overall coat protein masses, the proteins were digested with trypsin or Lys-C proteinases, and the digestion products were analyzed in a MALDI QqTOF mass spectrometer.

Total chemical synthesis and chemotactic activity of human S100A12 (EN-RAGE).

Human S100A12 (extracellular newly identified RAGE (receptor for advanced glycosylation end products)-binding protein), a new member of the S100 family of EF-hand calcium-binding proteins, was chemically synthesised using highly optimised 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate/tert-butoxycarbonyl in situ neutralisation solid-phase chemistry. Circular dichroism studies indicated that CaCl(2) decreased the helical content by 27% whereas helicity was marginally increased by ZnCl(2). The propensity of S100A12 to dimerise was examined by electrospray ionisation time-of-flight mass spectrometry which clearly demonstrated the prevalence of the non-covalent homodimer (20890 Da).

[Effect of recombinant interleukin-1 beta on microbial flora of the middle ear in patients with chronic purulent otitis media].

Betaleukin was given to 60 patients with various forms of otitis media purulenta chronica (OMPC). Symptoms of the purulent exacerbation were relieved in 43.3% of the patients, the clinical course improved in 18.

Separation and identification of peptides from gel-isolated membrane proteins using a microfabricated device for combined capillary electrophoresis/nanoelectrospray mass spectrometry.

The coupling of microfabricated devices to nanoelectrospray mass spectrometers using both a triple quadrupole and a quadrupole time-of-flight mass spectrometer (QqTOF MS) is presented for the analysis of trace-level membrane proteins. Short disposable nanoelectrospray emitters were directly coupled to the chip device via a low dead volume connection. The analytical performance of this integrated device in terms of sensitivity and reproducibility was evaluated for standard peptide mixtures.

SCF ubiquitin protein ligases and phosphorylation-dependent proteolysis.

Many key activators and inhibitors of cell division are targeted for degradation by a recently described family of E3 ubiquitin protein ligases termed Skp1-Cdc53-F-box protein (SCF) complexes. SCF complexes physically link substrate proteins to the E2 ubiquitin-conjugating enzyme Cdc34, which catalyses substrate ubiquitination, leading to subsequent degradation by the 26S proteasome. SCF complexes contain a variable subunit called an F-box protein that confers substrate specificity on an invariant core complex composed of the subunits Cdc34, Skp1 and Cdc53.

Natural Infection of Sorghum by Foxtail Mosaic Virus in Kansas.

Sorghum (Sorghum bicolor) was infected by a mechanically transmissible, flexuous, rod-shaped virus. Antiserum made against the purified virus reacted specifically in enzyme-linked immunosorbent assay to the virus and to the potexvirus foxtail mosaic virus (FoMV), indicating that the sorghum virus was an isolate of FoMV. Comparison of the sorghum isolate (H93) to FoMV PV 139 showed that H93 differed biologically by causing severe symptoms in sorghum, not readily infecting certain barley lines, and causing only faint symptoms in barley.