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Kang J.-H.,Japan National Cardiovascular Center Research Institute | Mori T.,Center for Future Chemistry | Niidome T.,Center for Future Chemistry | Takayama K.,Research Institute for Diseases of the Chest | And 4 more authors.
Anticancer Research | Year: 2013

Background: Recently, we reported on the existence of activated protein kinase Cα (PKCα) in blood and the possibility for its use in cancer diagnosis. Materials and Methods: In the present study, serum samples collected from patients with different lung cancer types (small-cell cancer, adenocarcinoma, and anaplastic cancer) were phosphorylated with a PKCα-specific peptide substrate and the phosphorylation ratio was detected by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Results: When 13 patient serum samples were phosphorylated with peptide substrates, phosphorylated peaks were obtained in eight samples. However, no peak associated with the phosphorylated peptide was observed using serum samples obtained from 10 healthy persons. Moreover, broadly used cancer biomarkers (progastrin-releasing peptide, carcinoembryonic antigen, and cytokeratin-19 fragment) were identified in eight samples among the 13 samples studied. Conclusion: These results suggest that serum activated PKCα is a reliable biomarker, applicable to lung cancer diagnosis. © 2013 Anticancer Research. Source


Tang Y.,Kyushu University | Imasaka T.,Kyushu University | Yamamoto S.,Fukuoka Institute of Health Environmental | Imasaka T.,Center for Future Chemistry
Chemosphere | Year: 2016

Multiphoton ionization processes of parent-polycyclic aromatic hydrocarbons (PPAHs), nitro-PAHs (NPAHs), and amino-PAHs (APAHs) were examined by gas chromatography combined with time-of-flight mass spectrometry using a femtosecond Ti:sapphire laser as the ionization source. The efficiency of multiphoton ionization was examined using lasers emitting in the far-ultraviolet (200 nm), deep-ultraviolet (267 nm), and near-ultraviolet (345 nm) regions. The largest signal intensities were obtained when the far-ultraviolet laser was employed. This favorable result can be attributed to the fact that these compounds have the largest molar absorptivities in the far-ultraviolet region. On the other hand, APAHs were ionized more efficiently than NPAHs in the near-ultraviolet region because of their low ionization energies. A sample extracted from a real particulate matter 2.5 (PM2.5) sample was measured, and numerous signal peaks arising from PAH and its analogs were observed at 200 nm. On the other hand, only a limited number of signed peaks were observed at 345 nm, some of which were signed to PPAHs, NPAHs, and APAHs. Thus, multiphoton ionization mass spectrometry has potential for the use in comprehensive analysis of toxic environmental pollutants. © 2016 Elsevier Ltd. Source


Tang Y.,Kyushu University | Imasaka T.,Kyushu University | Yamamoto S.,Fukuoka Institute of Health Environmental | Imasaka T.,Center for Future Chemistry
Talanta | Year: 2015

Abstract In order to suppress the fragmentation and improve the sensitivity for determination of nitrated polycyclic aromatic hydrocarbons (NPAHs), the mechanism of multiphoton ionization was studied for the following representative NPAHs, 9-nitroanthracene, 3-nitrofluoranthene, and 1-nitropyrene. The analytes were extracted from the PM2.5 on the sampling filter ultrasonically, and were measured using gas chromatography/multiphoton ionization/time-of-flight mass spectrometry with a femtosecond tunable laser in the range from 267 to 405 nm. As a result, a molecular ion was observed as the major ion and fragmentation was suppressed at wavelengths longer than 345 nm. Furthermore, the detection limit measured at 345 nm was measured to be the subpicogram level. The organic compounds were extracted from a 2.19 mg sample of particulate matter 2.5 (PM2.5), and the extract was subjected to multiphoton ionization mass spectrometry after gas chromatograph separation. The background signals were drastically suppressed at 345 nm, and the target NPAHs, including 9-nitroanthracene and 1-nitropyrene, were detected, and their concentrations were determined to be 5 and 3 pg/m3, respectively. © 2015 Elsevier B.V. All rights reserved. Source


Uchimura T.,Center for Future Chemistry | Imasaka T.,Center for Future Chemistry
Analytical Chemistry | Year: 2010

A novel sample introduction technique, based on online concentration by analyte adsorption/laser desorption, was applied to resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). Signal enhancement and optical selectivity, based on supersonic jet spectrometry, were examined by measuring the REMPI spectra. This sample introduction technique was applied at the interface of a gas chromatograph (GC) and a mass spectrometer (MS). The signal intensity was enhanced ca. 80-fold, compared with that of a conventional technique based on continuous sample introduction. The analyte molecule was selectively measured using a tunable laser emitting at a wavelength of the 0-0 transition. With the use of a desorption laser, a linear calibration curve was extended over 4 orders of magnitude. The sensitivity, selectivity, and dynamic range were all superior for this sample introduction system, as were the inherent characteristics, e.g., a near-zero dead volume and thermal durability. This system would provide a useful means for practical trace analysis of aromatic hydrocarbons by GC/REMPI-TOFMS. © 2010 American Chemical Society. Source

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