Shunsuke Oyamada

Dr. Shunsuke Oyamada


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 May 2022 in Clinical and Translational Gastroenterology
Verified
Journal Article
Open access
YKYuki Kasai
Yuki Kasai
TKTakaomi Kessoku
Takaomi Kessoku
KTKosuke Tanaka
Kosuke Tanaka
AYAtsushi Yamamoto
Atsushi Yamamoto
KTKota Takahashi
Kota Takahashi
Atsushi  NakajimaAtsushi Nakajima
Atsushi Nakajima
INTRODUCTION: No reports on both blood and fecal bile acids (BAs) in patients with nonalcoholic fatty liver disease (NAFLD) exist. We simultaneously assessed the serum and fecal BA patterns in healthy participants and those with NAFLD. METHODS: We collected stool samples from 287 participants from 5 hospitals in Japan (healthy control [HC]: n = 88; mild fibrosis: n = 104; and advanced fibrosis group: n = 95). Blood samples were collected and analyzed for serum BAs and 7α-hydroxy-4-cholesten-3-one (C4)—a surrogate marker for BA synthesis ability—from 141 patients. Concentrations of BAs, including cholic acid (CA), deoxycholic acid (DCA), chenodeoxycholic acid, ursodeoxycholic acid, and lithocholic acid (LCA), were measured using liquid chromatography-mass spectrometry. RESULTS: The total fecal BA concentration was significantly higher in the NAFLD group with worsening of fibrosis than in the HC group. Most of the fecal BAs were secondary and unconjugated. In the fecal BA fraction, CA, DCA, chenodeoxycholic acid, ursodeoxycholic acid, and LCA were significantly higher in the NAFLD than in the HC group. The total serum BA concentration was higher in the NAFLD group with worsening of fibrosis than in the HC group. In the serum BA fraction, CA, LCA, and C4 concentrations were significantly higher in the NAFLD than in the HC group. DISCUSSION: Fecal and serum BA and C4 concentrations were high in patients with NAFLD with worsening of fibrosis, suggesting involvement of abnormal BA metabolism in NAFLD with fibrosis progression. Abnormalities in BA metabolism may be a therapeutic target in NAFLD with fibrosis.


22 October 2024 in Annals of Surgery
Verified
Journal Article
Open access
MNMasakatsu Numata
Masakatsu Numata
TYTomohiro Yamaguchi
Tomohiro Yamaguchi
ASAkio Shiomi
Akio Shiomi
RIRyo Inada
Ryo Inada
MSManabu Shiozawa
Manabu Shiozawa
LSLANDMARC Collaborative Study Group of the Japan Society of Laparoscopic Colorectal Surgery
LANDMARC Collaborative Study Group of the Japan Society of Laparoscopic Colorectal Surgery
Objective: To investigate the incidence of male sexual dysfunction including erectile dysfunction (ErD) and ejaculatory dysfunction (EjD) after minimally invasive rectal cancer surgery. Background: Male sexual dysfunction significantly affects after rectal cancer surgery quality of life. Current assessments using the International Index of Erectile Function-5 are unsuitable for patients with reduced postoperative sexual activity because it assume sexual intercourse. This study addresses this gap using the Erection Hardness Score and custom ejaculatory questionnaires. Methods: This prospective multicenter open-label phase 2 trial enrolled 399 patients who underwent laparoscopic (Lap), robotic (Ro), or transanal (Ta) rectal cancer surgery. Erection Hardness Score and custom ejaculatory questionnaires assessed ErD, EjD, and potency impairment at 3, 6, and 12 months postoperatively. The rates were assessed in the full analysis set and compared between the Lap and Ro groups after propensity score matching. Results: At 12 months, the overall incidences of ErD and EjD were 34.7% and 29.8%, respectively. The Ro group showed a significantly lower EjD rate (25.0%) than the Lap group (40.9%), with no significant difference in ErD. Potency impairment was lower in the Ro group at 6 months (32.7% vs 22.3%) and 12 months (29.0% vs 17.8%) postoperatively. The Ta group showed relatively high ErD and EjD at 3 months, with some recovery at 12 months. Conclusions: Minimally invasive rectal cancer surgery commonly results in ErD, EjD, and potency impairment. Ro surgery provides lower EjD rates and less potency impairment. Comprehensive sexual function assessments are essential to inform patients and improve quality of life outcomes.


26 April 2022 in BMC Medical Research Methodology
Verified
Journal Article
Open access
PDF file
SOShunsuke Oyamada
Shunsuke Oyamada
SCShih-Wei Chiu
Shih-Wei Chiu
TYTakuhiro Yamaguchi
Takuhiro Yamaguchi
Background: There are currently no methodological studies on the performance of the statistical models for estimating intervention effects based on the time-to-recurrent-event (TTRE) in stepped wedge cluster randomised trial (SWCRT) using an open cohort design. This study aims to address this by evaluating the performance of these statistical models using an open cohort design with the Monte Carlo simulation in various settings and their application using an actual example.Methods: Using Monte Carlo simulations, we evaluated the performance of the existing extended Cox proportional hazard models, i.e., the Andersen-Gill (AG), Prentice-Williams-Peterson Total-Time (PWP-TT), and Prentice-Williams-Peterson Gap-time (PWP-GT) models, using the settings of several event generation models and true intervention effects, with and without stratification by clusters. Unidirectional switching in SWCRT was represented using time-dependent covariates.Results: Using Monte Carlo simulations with the various described settings, in situations where inter-individual variability do not exist, the PWP-GT model with stratification by clusters showed the best performance in most settings and reasonable performance in the others. The only situation in which the performance of the PWP-TT model with stratification by clusters was not inferior to that of the PWP-GT model with stratification by clusters was when there was a certain amount of follow-up period, and the timing of the trial entry was random within the trial period, including the follow-up period. In situations where inter-individual variability existed, the PWP-GT model consistently underperformed compared to the PWP-TT model. The AG model performed well only in a specific setting. By analysing actual examples, it was found that almost all the statistical models suggested that the risk of events during the intervention condition may be somewhat higher than in the control, although the difference was not statistically significant.Conclusions: When estimating the TTRE-based intervention effects of SWCRT in various settings using an open cohort design, the PWP-GT model with stratification by clusters performed most reasonably in situations where inter-individual variability was not present. However, if inter-individual variability was present, the PWP-TT model with stratification by clusters performed best.

20 January 2023 in Supportive Care in Cancer
Verified
Journal Article
Closed access
PDF file
SKSaori Koshimoto
Saori Koshimoto
KAKoji Amano
Koji Amano
NMNaoharu Mori
Naoharu Mori
SOShunsuke Oyamada
Shunsuke Oyamada
SASayaka Arakawa
Sayaka Arakawa
TTTakashi Takeuchi
Takashi Takeuchi