Browsing by Author "Chen, Tai-Hung"

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Forensic applications of direct analysis in real time (DART) coupled to Q-orbitrap tandem mass spectrometry for the in situ analysis of pigments from paint evidence
(2017-08-01)
Chen, Tai-Hung
;
Wu, Shu-Pao
;
應用化學系
;
Department of Applied Chemistry
The accurate examination of paint fragments obtained from an accident, such as those obtained from vehicles involved in a hit-and-run case, is often critical in forensic investigations. However, organic pigments are typically minor components of automotive coatings, which makes discrimination difficult. In this study, direct analysis in real time coupled to Q-orbitrap tandem mass spectrometry (DART-MS) was employed to detect a wide range of common organic pigments in vehicle paints. Twelve common organic pigments used in vehicle paints, such as red, yellow, orange, and purple, were tested, and a database was constructed for future examinations of vehicle paint. Two hit-and-run vehicle accident cases, which occurred in New Taipei City, were investigated by Fourier transform infrared (FTIR) spectroscopy and DART-MS. First, FTIR spectroscopy was employed to study the paint samples as a preliminary screening step. Most of the observed IR peaks were attributed to binder and extenders present in paints. The IR peaks corresponding to the organic pigments were found to be weak and overlapped with those corresponding to resins. On the other hand, DART-MS successfully characterized the organic pigments. DART-MS was found to be excellent for rapidly determining the presence of organic pigments in paint samples without the need for a complicated pre-treatment process or lengthy analysis time. (C) 2017 Elsevier B.V. All rights reserved.
Suppressed humoral immunity is associated with dengue nonstructural protein NS1-elicited anti-death receptor antibody fractions in mice
(2020-04-14)
Tsai, Chung-Lin
;
Sun, Der-Shan
;
Su, Mei-Tzu
;
Lien, Te-Sheng
;
Chen, Yen-Hsu
Dengue virus (DENV) infections may cause life-threatening dengue hemorrhagic fever (DHF). Suppressed protective immunity was shown in these patients. Although several hypotheses have been formulated, the mechanism of DENV-induced immunosuppression remains unclear. Previously, we found that cross-reactive antibodies against tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 1 (death receptor 4 [DR4]) were elicited in DHF patients, and that anti-DR4 autoantibody fractions were elicited by nonstructural protein 1 (NS1) immunizations in experimental mice. In this study, we found that anti-DR4 antibodies could suppress B lymphocyte function in vitro and in vivo. Treatment with the anti-DR4 immunoglobulin (Ig) induced caspase-dependent cell death in immortalized B lymphocyte Raji cells in vitro. Anti-DR4 Igs elicited by NS1 and DR4 immunizations markedly suppressed mouse spleen transitional T2 B (IgM(+)IgD(+)), bone marrow pre-pro-B (B220(+)CD43(+)), pre-B (B220(+)CD43(-)), and mature B cell (B220(+)IgD(+)) subsets in mice. Furthermore, functional analysis revealed that the pre-elicitation of anti-NS1 and anti-DR4 Ig titers suppressed subsequently neutralizing antibody production by immunization with DENV envelop protein. Our data suggest that the elicitation of anti-DR4 titers through DENV NS1 immunization plays a suppressive role in humoral immunity in mice.
The detection of multiple illicit street drugs in liquid samples by direct analysis in real time (DART) coupled to Q-orbitrap tandem mass spectrometry
(2016-10)
Chen, Tai-Hung
;
Hsu, Hsin-Yun
;
Wu, Shu-Pao
;
應用化學系
;
Department of Applied Chemistry
Direct analysis in real time coupled to Q-orbitrap tandem mass spectrometry (DART-MS) without requiring preparatory procedures was used to directly detect trace amounts of illegal street drugs, namely p-chloroamphetamine, p-fluoromethamphetamine, gamma-hydroxybutyrate, ketamine, methamphetamine, 3,4-methylenedioxypyrovalerone, p-methylethcathinone, methylone, and nimetazepam, in solution and also in real drug samples. Exact mass determination of the drug samples was completed in less than 1 min. With the ability to rapidly identify drugs, this technique shows great potential as a useful analytical tool in the analysis of illicit street drugs, and has the significant advantages of simplicity and sensitivity without the sample preparation needed by other methods. (C) 2016 Elsevier Ireland Ltd. All rights reserved.