The Influence of Hearing Aids on Balance Control: A Systematic Review.

AIM: To assess the current opinion on the effects of hearing loss treatment by hearing aids (HAs) and the benefits of HA use on imbalance. METHODS: PRISMA-compliant systematic review was done, including observational studies in patients affected by mild to severe sensorineural hearing loss with HAs, investigating the benefits of HAs on balance. Electronic searches were performed through Medline, Cochrane, Embase, Web of Science, and Scopus. RESULTS: A total of 200 patients in 8 studies were included in this systematic review. Four studies were cross-sectional, 3 cross-sectional controlled and 1 prospective nonrandomized study. Static and dynamic balance in the aided condition improved in patients assessed using clinical investigations including Romberg test and Functional Ambulation Performance/mini-BESTest, respectively. Variable outcomes were found measuring static and dynamic balance during the aided condition with objective tests (computerized posturography, Mobility Lab device). Improved quality of life outcomes and self-confidence were noted, while subjective measurements of balance had conflicting results. CONCLUSION: Although an improvement in balance in patients with HAs has been shown in certain conditions, the overall benefit is still unclear and it is only possible to speculate that HAs may also improve static, dynamic, or subjective perception of balance function in adults affected by hearing loss.

2D FT-ICR MS of Calmodulin: A Top-Down and Bottom-Up Approach.

Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry (2D FT-ICR MS) allows data-independent fragmentation of all ions in a sample and correlation of fragment ions to their precursors through the modulation of precursor ion cyclotron radii prior to fragmentation. Previous results show that implementation of 2D FT-ICR MS with infrared multi-photon dissociation (IRMPD) and electron capture dissociation (ECD) has turned this method into a useful analytical tool. In this work, IRMPD tandem mass spectrometry of calmodulin (CaM) has been performed both in one-dimensional and two-dimensional FT-ICR MS using a top-down and bottom-up approach. 2D IRMPD FT-ICR MS is used to achieve extensive inter-residue bond cleavage and assignment for CaM, using its unique features for fragment identification in a less time- and sample-consuming experiment than doing the same thing using sequential MS/MS experiments. Graphical Abstract ᅟ.

Does deamidation cause protein unfolding? A top-down tandem mass spectrometry study.

Deamidation is a nonenzymatic post-translational modification of asparagine to aspartic acid or glutamine to glutamic acid, converting an uncharged amino acid to a negatively charged residue. It is plausible that deamidation of asparagine and glutamine residues would result in disruption of a proteins' hydrogen bonding network and thus lead to protein unfolding. To test this hypothesis Calmodulin and B2M were deamidated and analyzed using tandem mass spectrometry on a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS). The gas phase hydrogen bonding networks of deamidated and nondeamidated protein isoforms were probed by varying the infra-red multi-photon dissociation laser power in a linear fashion and plotting the resulting electron capture dissociation fragment intensities as a melting curve at each amino acid residue. Analysis of the unfolding maps highlighted increased fragmentation at lower laser powers localized around heavily deamidated regions of the proteins. In addition fragment intensities were decreased across the rest of the proteins which we propose is because of the formation of salt-bridges strengthening the intramolecular interactions of the central regions. These results were supported by a computational flexibility analysis of the mutant and unmodified proteins, which would suggest that deamidation can affect the global structure of a protein via modification of the hydrogen bonding network near the deamidation site and that top down FTICR-MS is an appropriate technique for studying protein folding.

Improved optimization of the Fourier transform ion cyclotron resonance mass spectrometry phase correction function using a genetic algorithm.

RATIONALE: Fourier Transform Ion Cyclotron Resonance mass spectra exhibit improved resolving power, mass accuracy and signal-to-noise ratio when presented in absorption mode; a process which requires calculation of a phase correction function. Mass spectrometric images can contain many thousands of pixels; hence methods of decreasing the time required to solve for a phase correction function will result in significant improvements in this application. METHODS: A genetic algorithm approach for optimizing the phase correction function has been developed and compared with a previously described convergent iteration technique. RESULTS: The genetic algorithm method has been shown to offer a five-fold improvement in processing speed compared with the previous iterative approach used in the Autophaser algorithm, while maintaining the levels of accuracy. This translates to an 11 hour improvement in processing for a 20 000 pixel mass spectrometric image. CONCLUSIONS: The genetic algorithm method described in this manuscript offers significant processing speed advantages over the previously described convergent iteration technique. This improvement is key to allowing the future routine use of absorption mode mass spectrometric images.