Validation of a Multi-Sensor-Based Kiosk for Short Physical Performance Battery.

Objectives: We aimed to validate a multi-sensor-based kiosk (automatically measured Short Physical Performance Battery [eSPPB] kiosk) that can perform automated measurement of the SPPB.

Design: Prospective, cross-sectional study.

Setting: Rehabilitation clinic of a tertiary-care hospital.

Degree of ionization in MALDI of peptides: thermal explanation for the gas-phase ion formation.

Degree of ionization (DI) in matrix-assisted laser desorption ionization (MALDI) was measured for five peptides using α-cyano-4-hydroxycinnanmic acid (CHCA) as the matrix. DIs were low 10(-4) for peptides and 10(-7) for CHCA. Total number of ions (i.

Ion yields for some salts in MALDI: mechanism for the gas-phase ion formation from preformed ions.

Preformed ion emission is the main assumption in one of the prevailing theories for peptide and protein ion formation in matrix-assisted laser desorption ionization (MALDI). Since salts are in preformed ion forms in the matrix-analyte mixture, they are ideal systems to study the characteristics of preformed ion emission. In this work, a reliable method to measure the ion yield (IY) in MALDI was developed and used for a solid salt benzyltriphenylphosphonium chloride and two room-temperature ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate.

Selective screening of tyrosine-nitrated peptides in tryptic mixtures by in-source photodissociation at 355 nm in matrix-assisted laser desorption ionization.

Nitration of tyrosine residues in proteins is an important post-translational modification related to various diseases such as Alzheimer's. In this work, efficient and selective photodissociation (PD) at 355 nm was observed for [M + H](+), [M + H - 16](+), and [M + H - 32](+) generated by matrix-assisted ultraviolet laser desorption ionization (UV-MALDI) of tyrosine-nitrated peptides (nitropeptides). Product ion spectra obtained by post-source PD at this wavelength contained useful information on the amino acid sequence.

Observation of phosphorylation site-specific dissociation of singly protonated phosphopeptides.

In ultraviolet photodissociation of phosphopeptide ions with a basic residue (arginine, lysine, or histidine) at the N-terminus, intense a(n) - 97 peaks were observed. These ions were formed by cleavage at phosphorylated residues only. For multiply phosphorylated peptides, this site-specific cleavage occurred at every phosphorylated residue.

Construction and performance test of a multiplexed multistage (MS(n)) time-of-flight mass spectrometer.

A time-of-flight mass spectrometer equipped with two reflectrons was constructed for multiplexed photodissociation tandem mass spectrometry of peptide ions generated by matrix-assisted laser desorption ionization. A linear reflectron was used for high-resolution selection of a precursor ion while a quadratic reflectron was used for product ion analysis. With the photoexcitation of a precursor ion inside a cell floated at high voltage, information (MS(3)) on intermediate ions generating a particular product ion was obtained.

Photodissociation at 193 nm of some singly protonated peptides and proteins with m/z 2000-9000 using a tandem time-of-flight mass spectrometer equipped with a second source for delayed extraction/post-acceleration of product ions.

A tandem time-of-flight mass spectrometer was built for photodissociation (PD) of singly protonated peptides and small proteins generated by matrix-assisted laser desorption/ionization. PD was performed in a second source after deceleration of precursor ions. The delayed extraction/post-acceleration scheme was used for the product ions.