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Dive into the research topics where Tetsuji Ohyama is active.

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Featured researches published by Tetsuji Ohyama.


Journal of Hepato-biliary-pancreatic Sciences | 2017

The “right” way is not always popular: comparison of surgeons’ perceptions during laparoscopic cholecystectomy for acute cholecystitis among experts from Japan, Korea and Taiwan

Taizo Hibi; Yukio Iwashita; Tetsuji Ohyama; Goro Honda; Masahiro Yoshida; Tadahiro Takada; Ho Seong Han; Tsann Long Hwang; Satoshi Shinya; Kenji Suzuki; Akiko Umezawa; Yoo Seok Yoon; In Seok Choi; Wayne Shih Wei Huang; Kuo Hsin Chen; Fumihiko Miura; Manabu Watanabe; Yuta Abe; Takeyuki Misawa; Yuichi Nagakawa; Dong Sup Yoon; Jin Young Jang; Hee Chul Yu; Keun Soo Ahn; Song Cheol Kim; In Sang Song; Ji Hoon Kim; Sung Su Yun; Seong Ho Choi; Yi Yin Jan

Generally, surgeons’ perceptions of surgical safety are based on experience and institutional policy. Our recent pilot survey demonstrated that the acceptable duration of surgery and criteria for open conversion during laparoscopic cholecystectomy (LC) vary among workplaces.


Journal of Hepato-biliary-pancreatic Sciences | 2016

What are the appropriate indicators of surgical difficulty during laparoscopic cholecystectomy? Results from a Japan‐Korea‐Taiwan multinational survey

Yukio Iwashita; Tetsuji Ohyama; Goro Honda; Taizo Hibi; Masahiro Yoshida; Fumihiko Miura; Tadahiro Takada; Ho Seong Han; Tsann Long Hwang; Satoshi Shinya; Kenji Suzuki; Akiko Umezawa; Yoo Seok Yoon; In Seok Choi; Wayne Shih Wei Huang; Kuo Hsin Chen; Manabu Watanabe; Yuta Abe; Takeyuki Misawa; Yuichi Nagakawa; Dong Sup Yoon; Jin Young Jang; Hee Chul Yu; Keun Soo Ahn; Song Cheol Kim; In Sang Song; Ji Hoon Kim; Sung Su Yun; Seong Ho Choi; Yi Yin Jan

Serious complications continue to occur in laparoscopic cholecystectomy (LC). The commonly used indicators of surgical difficulty such as the duration of surgery are insufficient because they are surgeon and institution dependent. We aimed to identify appropriate indicators of surgical difficulty during LC.


Journal of Hepato-biliary-pancreatic Sciences | 2017

An opportunity in difficulty: Japan–Korea–Taiwan expert Delphi consensus on surgical difficulty during laparoscopic cholecystectomy

Yukio Iwashita; Taizo Hibi; Tetsuji Ohyama; Goro Honda; Masahiro Yoshida; Fumihiko Miura; Tadahiro Takada; Ho Seong Han; Tsann Long Hwang; Satoshi Shinya; Kenji Suzuki; Akiko Umezawa; Yoo Seok Yoon; In Seok Choi; Wayne Shih Wei Huang; Kuo Hsin Chen; Manabu Watanabe; Yuta Abe; Takeyuki Misawa; Yuichi Nagakawa; Dong Sup Yoon; Jin Young Jang; Hee Chul Yu; Keun Soo Ahn; Song Cheol Kim; In Sang Song; Ji Hoon Kim; Sung Su Yun; Seong Ho Choi; Yi Yin Jan

We previously identified 25 intraoperative findings during laparoscopic cholecystectomy (LC) as potential indicators of surgical difficulty per nominal group technique. This study aimed to build a consensus among expert LC surgeons on the impact of each item on surgical difficulty.


Endocrine Journal | 2015

Expression of anti-Müllerian hormone and its type II receptor in germ cells of maturing rat testis

Kenji Ohyama; Masanori Ohta; Yoshinao Z. Hosaka; Yoshiko Tanabe; Tetsuji Ohyama; Yoshiaki Yamano

This work aimed to clarify the expression and roles of anti-Müllerian hormone (AMH) and its type 2 receptor (AMHR2) in seminiferous tubules of maturing rat testes. By quantitative RT-PCR, we determined the relative expressions of Amh, Amhr2, Scp1, Rsbn1, Ngfr, and Rhox5 in rat testes aged 5-49 days (d), and in germ cells and Sertoli cells isolated from 21d testes. Smad 1,5 and 8 expressions were also determined in 21d testes and isolated germ cells. Moreover, we performed in situ hybridization (ISH) of Amh and Amhr2 in 21d testes, and immunohistochemical staining (IHCS) in 10, 15 and 21d testes using antibodies of AMH and AMHR2. In 21d testes, expression of the spermatocyte specific gene, Scp1, increased but that of the round spermatid specific gene, Rsbn1, was faint. By ISH and IHCS, expressions of AMH and AMHR2 were strongly observed in spermatocytes of 21d testes, but not in spermatogonia. In 21d testes, expressions of immature Sertoli cell specific gene, Ngfr, and mature Sertoli cell specific gene, Rhox5, were observed. IHCS confirmed the presence of AMH and AMHR2 in Sertoli cells. Smad 1, 5 and 8 were highly expressed in 21d testes and isolated germ cells. These results indicate that not only immature Sertoli cells but also spermatocytes express AMH and AMHR2 in maturing testes. In this study, we first clarified that spermatocytes coexpressed AMH and AMHR2 in rats. We speculated that AMH produced by spermatocytes and Sertoli cells binds AMHR2 of spermatocytes and acts through SMADs.


Clinical and Translational Science | 2016

The Pharmacokinetic Exposure to Fexofenadine is Volume‐Dependently Reduced in Healthy Subjects Following Oral Administration With Apple Juice

J Luo; Hiromitsu Imai; Tetsuji Ohyama; S Hashimoto; T Hasunuma; Y Inoue; Tsutomu Kotegawa; Kyoichi Ohashi; Naoto Uemura

Pharmacokinetic exposures to fexofenadine (FEX) are reduced by apple juice (AJ); however, the relationship between the AJ volume and the degree of AJ‐FEX interaction has not been understood. In this crossover study, 10 healthy subjects received single doses of FEX 60 mg with different volumes (150, 300, and 600 mL) of AJ or water (control). To identify an AJ volume lacking clinically meaningful interaction, we tested a hypothesis that the 90% confidence interval (CI) for geometric mean ratio (GMR) of FEX AUCAJ/AUCwater is contained within a biocomparability bound of 0.5–2.0, with at least one tested volume of AJ. GMR (90% CI) of AUCAJ 150mL/AUCwater, AUCAJ 300mL/AUCwater, and AUCAJ 600mL/AUCwater were 0.903 (0.752–1.085), 0.593 (0.494–0.712), and 0.385 (0.321–0.462), respectively. While a moderate to large AJ‐FEX interaction is caused by a larger volumes of AJ (e.g., 300 to 600 mL), the effect of a small volume (e.g., 150 mL) appears to be not meaningful.


Journal of Steroids & Hormonal Science | 2017

Dwarfs and Giants of Parathyroid Adenomas - No Difference in Outcome after Parathyroidectomy

Kenji Ohyama; Masanori Ohta; Yoshinao Z. Hosaka; Tetsuji Ohyama; Yoshiaki Yamano

Although anti-Müllerian hormone (AMH) is present in seminiferous tubules, its physiological roles in testis remain unclear. We defined expression patterns of AMH and its type II receptor (AMHR2) in germ cells during spermatogenic cycles. To this end, we performed in situ hybridization of Amh and Amhr2, and immunohistochemical staining using antibodies against AMH and AMHR2 in testes from rats aged 10, 15, 21, 35, and 49 days (d). In addition, quantitative RT-PCR analyses were performed to determine relative expression levels of Amh, Amhr2, synaptonemal complex protein 1 (Scp1) and round spermatid basic protein 1 (Rsbn1), and Smads 1, 5, and 8 in germ cells isolated from 49d testes. In 49d testes, synthesis of AMH and AMHR2 corresponded with spermatocyte expression of Amh and Amhr2. Spermatocytes of stages VII-XIV synthesized AMH, and AMH staining was decreased in round spermatids and was not detectable in elongated spermatids. Spermatocytes of stages VII-XIV synthesized AMHR2, and round and elongated spermatids continued expressing AMHR2. The strongest staining of AMH was observed in spermatocytes at stage VIII, and that of AMHR2 was observed in round spermatids at the same stage. When isolated germ cells were cultured with anti-AMH antibody, expression levels of Amh and Amhr2 were significantly increased, those of Smads 1, 5 and Scp1 increased simultaneously, and that of Rsbn1 decreased. We speculate that the AMH-SMADs axis is associated with morphological change from round to elongated spermatids at stage VIII.Although anti-Mullerian hormone (AMH) is present in seminiferous tubules, its physiological roles in testis remain unclear. We defined expression patterns of AMH and its type II receptor (AMHR2) in germ cells during spermatogenic cycles. To this end, we performed in situ hybridization of Amh and Amhr2, and immunohistochemical staining using antibodies against AMH and AMHR2 in testes from rats aged 10, 15, 21, 35, and 49 days (d). In addition, quantitative RT-PCR analyses were performed to determine relative expression levels of Amh, Amhr2, synaptonemal complex protein 1 (Scp1) and round spermatid basic protein 1 (Rsbn1), and Smads 1, 5, and 8 in germ cells isolated from 49d testes. In 49d testes, synthesis of AMH and AMHR2 corresponded with spermatocyte expression of Amh and Amhr2. Spermatocytes of stages VII-XIV synthesized AMH, and AMH staining was decreased in round spermatids and was not detectable in elongated spermatids. Spermatocytes of stages VII-XIV synthesized AMHR2, and round and elongated spermatids continued expressing AMHR2. The strongest staining of AMH was observed in spermatocytes at stage VIII, and that of AMHR2 was observed in round spermatids at the same stage. When isolated germ cells were cultured with anti-AMH antibody, expression levels of Amh and Amhr2 were significantly increased, those of Smads 1, 5 and Scp1 increased simultaneously, and that of Rsbn1 decreased. We speculate that the AMH-SMADs axis is associated with morphological change from round to elongated spermatids at stage VIII.


Pharmacogenetics and Genomics | 2011

The effects of the SLCO2B1 c.1457C > T polymorphism and apple juice on the pharmacokinetics of fexofenadine and midazolam in humans.

Junko Imanaga; Tsutomu Kotegawa; Hiromitsu Imai; Kimiko Tsutsumi; Tsuneaki Yoshizato; Tetsuji Ohyama; Yoshiyuki Shirasaka; Ikumi Tamai; Tomonori Tateishi; Kyoichi Ohashi


World Journal of Surgery | 2015

A Multi-institutional, Prospective, Phase II Feasibility Study of Laparoscopy-Assisted Distal Gastrectomy with D2 Lymph Node Dissection for Locally Advanced Gastric Cancer (JLSSG0901)

Noriyuki Inaki; Tsuyoshi Etoh; Tetsuji Ohyama; Kazuhisa Uchiyama; Natsuya Katada; Keisuke Koeda; Kazuhiro Yoshida; Akinori Takagane; Kazuyuki Kojima; Shinichi Sakuramoto; Norio Shiraishi; Seigo Kitano


European Journal of Clinical Pharmacology | 2013

The effect of carboxylesterase 1 (CES1) polymorphisms on the pharmacokinetics of oseltamivir in humans

Yuki Suzaki; Naoto Uemura; Makoto Takada; Tetsuji Ohyama; Akiko Itohda; Takuya Morimoto; Hiromitsu Imai; Hajime Hamasaki; Akihiro Inano; Masakiyo Hosokawa; Masato Tateishi; Kyoichi Ohashi


European Journal of Clinical Pharmacology | 2012

Itraconazole and domperidone: a placebo-controlled drug interaction study

Tsuneaki Yoshizato; Tsutomu Kotegawa; Hiromitsu Imai; Kimiko Tsutsumi; Junko Imanaga; Tetsuji Ohyama; Kyoichi Ohashi

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Masahiro Yoshida

International University of Health and Welfare

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