Identification of oligosaccharides from histopathological sections by MALDI imaging mass spectrometry |
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Authors: | Masanori?Yamada Email author" target="_blank">Ikuko?YaoEmail author Takahiro?Hayasaka Masaru?Ushijima Masaaki?Matsuura Hideho?Takada Nobuaki?Shikata Mitsutoshi?Setou A-Hon?Kwon Seiji?Ito |
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Institution: | (1) Department of Surgery, Kansai Medical University, 2-3-1 Shin-machi, Hirakata Osaka, 573-1191, Japan;(2) Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi Osaka, 570-8506, Japan;(3) Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 7 Goban-cho, Chiyoda-ku Tokyo, 102-0076, Japan;(4) Department of Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu Shizuoka, 431-3192, Japan;(5) Bioinformatics Group, Genome Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku Tokyo, 135-8550, Japan;(6) Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku Tokyo, 135-8550, Japan;(7) Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi Osaka, 570-8506, Japan; |
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Abstract: | Direct tissue analysis using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) provides the means
for in situ molecular analysis of a wide variety of biomolecules. This technology—known as imaging mass spectrometry (IMS)—allows
the measurement of biomolecules in their native biological environments without the need for target-specific reagents such
as antibodies. In this study, we applied the IMS technique to formalin-fixed paraffin-embedded samples to identify a substance(s)
responsible for the intestinal obstruction caused by an unidentified foreign body. In advance of IMS analysis, some pretreatments
were applied. After the deparaffinization of sections, samples were subjected to enzyme digestion. The sections co-crystallized
with matrix were desorbed and ionized by a laser pulse with scanning. A combination of α-amylase digestion and the 2,5-dihydroxybenzoic
acid matrix gave the best mass spectrum. With the IMS Convolution software which we developed, we could automatically extract
meaningful signals from the IMS datasets. The representative peak values were m/z 1,013, 1,175, 1,337, 1,499, 1,661, 1,823, and 1,985. Thus, it was revealed that the material was polymer with a 162-Da unit
size, calculated from the even intervals. In comparison with the mass spectra of the histopathological specimen and authentic
materials, the main component coincided with amylopectin rather than amylose. Tandem MS analysis proved that the main components
were oligosaccharides. Finally, we confirmed the identification of amylopectin by staining with periodic acid-Schiff and iodine.
These results for the first time show the advantages of MALDI-IMS in combination with enzyme digestion for the direct analysis
of oligosaccharides as a major component of histopathological samples. |
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