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On 24 October 2020, our community lost Toshitsugu Sugimoto, MD, PhD. His professional career spanned over 40 years, and during these years he made tremendous contributions to the field of bone and mineral research. This year has been a peculiar one. Most scientific and business meetings became virtual which substantially decreased the opportunity to meet people in person. He had struggled with illness for several months, but his disease was known only to a limited number of people. He continued to do his work even when he was admitted to a hospital.

Prof. Sugimoto was born in Sumoto City, Hyogo Prefecture in 1953. After graduating Keio University in 1979, he joined the Third Division, Department of Medicine, Kobe University headed by Prof. Takuo Fujita. He started his research career there by investigating the effects of parathyroid hormone (PTH) on bone and the mode of actions of PTH. From 1986, he spent about two years as a research associate in a laboratory headed by Prof. Eduardo Slatopolsky of Washington University in St. Louise, USA. During these days, he obtained important findings concerning the regulatory mechanisms of PTH secretion by glucocorticoid, 1,25-dihydroxyvitamin d and glucose. After returning to Kobe University, he conducted many basic and clinical studies concerning such as parathyroid cell proliferation, anabolic actions of PTH, effects of growth hormone—insulin-like growth factor I on bone, racial difference in bone mineral density, primary and secondary hyperparathyroidism, glucocorticoid-induced osteoporosis and so on. He became a professor at Shimane University in 2004 and continued basic and clinical research. Especially, he clarified the actions of advanced glycation end products and adiponectin on bone, and showed the bone fragility in patients with lifestyle diseases. He retired from Shimane University in 2019 to become an honorary hospital director of Eikokai Ono Hospital in Ono City, Hyogo Prefecture. Based on these basic and clinical expertise, he was involved as a major contributor in the development of many clinical guidelines including Guideline for the Prevention and Treatment of Osteoporosis, Clinical Practice Guide on Fracture Risk in Lifestyle Diseases, Position Paper for Antiresorptive Agent-Related Osteonecrosis of the Jaw, Assessment Criteria for Vitamin D Deficiency/Insufficiency in Japan, Management Manual for Cancer Treatment-Induced Bone Loss (CTIBL), and Pathogenesis and Diagnostic Criteria for Rickets and Osteomalacia. He served as a board member of several scientific meetings such as the Japanese Society for Bone and Mineral Research (JSBMR), Japan Osteoporosis Society (JOS), and the Japan Endocrine Society (JES). He also held many important scientific meetings as a president including the Annual Meeting of JOS in 2011, the Annual Meeting of JSBMR in 2014, and the JES Clinical Update on Endocrinology and Metabolism in 2017.

During his career, he educated many younger scientists such as Drs. Toru Yamaguchi, Hiroshi Kaji, Shozo Yano, Mika Yamauchi, Masahiro Yamamoto, Ippei Kanazawa in our field. In addition, 18 doctors completed their degrees at Shimane University under the supervision of Prof. Sugimoto.

We mourn his loss. We miss his warm and friendly personality, enthusiasm about research, education, and clinical practice, and sincerely thank for the contribution to our society by this physician-scientist.