1Department of Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
2Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
3Department of Surgical Pathology, Hyogo College of Medicine, Hyogo, Japan
4Department of Neurosurgery, Brain Research Institute, Niigata University, Niigata, Japan
5Department of Internal Medicine, Osaka University Graduate School of Medicine, Osaka, Japan