Y.C. Chen

The study of interferences for diagnosing albuminuria by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry

BACKGROUNDnMatrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometric analysis of albumin (ALB) biomarkers is an alternative approach toward the rapid diagnosis of proteinuria for screening a large number of samples. The aim of this study is to reveal if interfering factors in urinary dipstick approach would affect the results of diagnosing albuminuria by MALDI-TOF MS.nnnMETHODSnThe effects of various interfering chemicals on the diagnosis of albumin in urine were examined using both MALDI-TOF mass spectrometric and dipstick approaches. Semi-quantification of albumin was performed by using MALDI-TOF MS.nnnRESULTSnInterferences from various drugs, detergents, vitamins and their metabolites, alkaline, and blood, which often cause false-positive and false-negative results in conventional urinary dipstick analysis, are avoided when using this MALDI-TOF MS approach. It was found that the intensity of +1 and +2 albumin ions varies with the albumin concentration. A log/log plot of the intensity ratio vs. albumin concentration is then used as a calibration curve for semi-quantifying the albumin in urines.nnnCONCLUSIONSnMALDI-TOF MS is an effective approach toward avoiding interferences caused by various chemical compounds during the rapid diagnosis of albumin in urine. Semi-quantification of albuminuria is also achieved by this MALDI-TOF MS approach.

Differentiation of virulence of Helicobacter pylori by matrix-assisted laser desorption/ionization mass spectrometry and multivariate analyses

BACKGROUNDnThe ability to determine the virulence of a Helicobacter pylori strain would be helpful for predicting the development of gastrointestinal disease and suggesting medical treatment.nnnMETHODSnA protocol based on matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS) was established for the efficient detection of peptides and proteins in extracts of H. pylori cells. Two multivariate statistical methods-principal component analysis (PCA) and hierarchical clustering analysis-were used to analyze the resulting MALDI mass spectra of reference strains and clinical isolated/inoculated strains.nnnRESULTSnBased on differences in their peptide and protein profiles, H. pylori strains having similar virulence genotypes were grouped together on the PCA score plot. Hierarchical cluster analysis revealed high conformity between the protein profiles and the respective virulence genotypes. The inoculated H. pylori strain, which was clustered in the same group with the high-virulence reference strains, also resulted in severe histopathological lesions in gerbils.nnnCONCLUSIONSnMALDI-TOF MS combined with multivariate analyses shows the ability to rapidly differentiate H. pylori strains in terms of their virulence.

Designing a Piezoelectric Vibration-Energy Harvester Used for a Rapid IgE Allergy Sensing System Platform

This investigation examines a novel means of integrating high-performance AlN piezoelectric thin films with a flexible stainless steel substrate (SUS304) to fabricate a double-sided piezoelectric transducer for wind-power generators. The double-sided piezoelectric transducer is constructed by depositing AlN piezoelectric thin films on both the front and the back sides of SUS304 substrate. The titanium (Ti) and platinum (Pt) layers were deposited using a dual-gun DC sputtering system between the AlN piezoelectric thin film and the back side of the SUS304 substrate. Scanning electron microscopy and X-ray diffraction of AlN piezoelectric films reveal a rigid surface structure and highly c-axis-preferred orientation. To fabricate a transducer with a resonant frequency of about 90 Hz, a cantilever length of 1 cm and a vibration area of 1 cm2 are designed, based on the cantilever vibration theory. The maximum open circuit voltage of the power transducer is approximately 14.6 V.