Paper

• Chromatographic separation of dihydroxylated vitamin D3 and accurate quantification of 1α,25(OH)2D3 in human serum.
  Koji Takahashi, Masaki Takiwaki, Rino Tsutsumi, Ryota Sakamoto, Kazuo Nagasawa, Yutaka Kuroda, Seketsu Fukuzawa.
  Journal of Pharmaceutical and Biomedical Analysis., 2025, Refereed
• Association between serum vitamin D metabolite levels and cognitive function in community-dwelling older adults: A cross-sectional study.
  Cai Yu , Minae Ide , Taiki Sugimoto , Rei Otsuka , Koji Takahashi , Masaki Takiwaki , Kiyoshi Tanaka , Hiroaki Kanouchi , Shigeo Takenaka , Takashi Sakurai , Shumpei Niida , Akiko Kuwabara.
  Clinical Nutrition ESPEN., 69, 785-793, 2025, Refereed
• Effects of consuming fish on vitamin D status and use of urinary vitamin D metabolite as a noninvasive biomarker.
  Xiangna Zheng , Yuka Kawakami-Shinoda , Masaki Takiwaki , Kentaro Abe , Hidekazu Arai.
  The journal of medical investigation., 72(3.4), 308-315, 2025, Refereed
• A combined health promotion program of exercise with protein and vitamin D-enriched menu enhances skeletal muscle mass and strength in Japanese elderly men.
  Ge Li, Yuka Kawakami-Shinoda, Alima, Masaki Takiwaki, Kentaro Abe, Toshio Hosaka, Toshinao Goda, Hidekazu Arai.
  The journal of medical investigation., 72(1.2), 76-84, 2025, Refereed
• Development of an accurate and sensitive assay for 2-methoxyestradiol using derivatization and liquid chromatography-tandem mass spectrometry
  Koji Takahashi, Masaki Takiwaki, Seketsu Fukuzawa, Yoshikuni Kikutani, Kentaro Abe, Tatsuya Higashi, Hironori Kobayashi.
  Practical Laboratory Medicine., 9:44:e00447., 2025, Refereed
  Corresponding
• A method for measuring serum levels of melanin-associated indole metabolites using LC-MS/MS and its application to malignant melanoma
  Clin Chim Acta., 2024
  Lead
• Development of free 25-hydroxyvitamin D3 assay method using liquid chromatography-tandem mass spectrometry
  Nau Ishimine, Shixing Wu, Ryusei Ota, Koji Takahashi, Masaki Takiwaki, Mitsutoshi Sugano, Minoru Tozuka, Takeshi Uehara
  Biosci Rep, 2022, Refereed
• Synthesis of Deuterium-Labeled Vitamin D Metabolites as Internal Standards for LC-MS Analysis
  Akiko Nagata, Kazuto Iijima, Ryota Sakamoto, Yuka Mizumoto, Miho Iwaki, Masaki Takiwaki, Yoshikuni Kikutani, Seketsu Fukuzawa, Minami Odagi, Masayuki Tera, Kazuo Nagasawa
  MOLECULES, 2022, Refereed
• Development of a sensitive liquid chromatography-tandem mass spectrometry method for quantification of human plasma arginine vasopressin
  Masaki Takiwaki, Fumio Nomura, Mamoru Satoh, Sachio Tsuchida, Kazuo Otake, Junko Takagi
  Journal of Chromatography B, 2021, Refereed
  Lead