Yohei Yamada

Dr. Yohei Yamada


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

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

Representative Publications

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7 August 2025 in JCI Insight
Verified
Journal Article
Open access
PDF file
YKYumi Kudo
Yumi Kudo
KMKentaro Miyamoto
Kentaro Miyamoto
SSShohei Suzuki
Shohei Suzuki
ACAkihiko Chida
Akihiko Chida
ATAnna Tojo
Anna Tojo
TSTomohisa Sujino
Tomohisa Sujino
BACKGROUND: Glucagon-like peptide-2 (GLP-2) analogs are used clinically to enhance nutrient absorption in patients with short bowel syndrome (SBS); however, the precise mechanism remains unclear. To address this, the study aimed to clarify the dynamics of intestinal epithelial cells and immune cells in patients with SBS treated with GLP-2 analogs. METHODS: Five male patients diagnosed with SBS, all of whom received treatment with the GLP-2 analog teduglutide, were included in the study. We conducted longitudinal single-cell RNA sequencing (scRNA-Seq) analysis of intestinal tissue from patients with SBS over a year, integrating microbiome composition analysis. RESULTS: After treatment, the α-diversity of the gut microbiome increased, indicating a more varied microbial environment. ScRNA-Seq analysis revealed a reduction of T helper 2 cells and an increase in regulatory T cells, suggesting a shift toward an immunoregulatory intestinal environment. Additionally, nutrient-absorbing enterocyte-Top2 and middle clusters expanded, enhancing the absorption capacity, whereas major histocompatibility complex class I/II–expressing enterocyte-Top1 cells declined, potentially modulating immune responses. CONCLUSION: The study findings indicate that GLP-2 analogs reshape intestinal immunity and microbiota, fostering a less inflammatory environment while promoting nutrient uptake efficiency. These insights offer a deeper understanding of the role of GLP-2 analogs in gut adaptation and provide a foundation for refining clinical strategies for SBS treatment. FUNDING: This work was supported by Sakaguchi Memorial Foundation, Grants-in-Aid from the Japanese Society for the Promotion of Science (JSPS) (21K18272, 23H03665, 23H02899, 23K27590, 25K22627, 23K08037), JST FOREST(21457195), and the Takeda Japan Medical Office Funded Research Grant 2022.

23 October 2023 in Biomolecules
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Journal Article
Open access
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YYYohei Yamada
Yohei Yamada
TMTeizaburo Mori
Teizaburo Mori
NTNobuhiro Takahashi
Nobuhiro Takahashi
TFTakumi Fujimura
Takumi Fujimura
MKMotohiro Kano
Motohiro Kano
AFAkihiro Fujino
Akihiro Fujino
No standard diagnostic method or surgical treatment for congenital isolated hypoganglionosis (CIHG) has been established. This study aimed to analyze the clinical outcomes of patients with CIHG and identify the best surgical interventions provided thus far. Data on surgical interventions in 19 patients were collected between 1992 and 2020, including the type of enterostomy, type of revision, and length of the intestines. Ganglion cells in the myenteric plexus were enumerated using Hu C/D staining. The ratio of the length of the small intestine to its height was defined as the intestinal ratio (IR). The outcomes were assessed using the stoma output, growth parameters including the body mass index (BMI), and parenteral nutrition (PN) dependency. All patients required a diverting enterostomy. The IR ranged from 0.51 to 1.75 after multiple non-transplant surgeries. The stoma types were tube-stoma, end-stoma, Santulli-type, and Bishop–Koop (BK)-type. Patients with Santulli- or BK-type stomas had better BMIs and less PN dependency in terms of volume than those with end-stomas or tube-stomas. Two patients with BK-type stomas were off PN, and three who underwent an intestinal transplantation (Itx) achieved enteral autonomy. The management of CIHG involves a precise diagnosis using Hu C/D staining, neonatal enterostomy, and stoma revision using the adjusted IR and Itx if other treatments do not enable enteral autonomy.

31 August 2021 in Journal of Clinical Medicine
Verified
Journal Article
Open access
PDF file
NTNobuhiro Takahashi
Nobuhiro Takahashi
DODaigo Ochiai
Daigo Ochiai
YYYohei Yamada
Yohei Yamada
MTMasumi Tamagawa
Masumi Tamagawa
HKHiroki Kanamori
Hiroki Kanamori
MTMamoru Tanaka
Mamoru Tanaka
Considering that some biliary atresia (BA) survivors with native liver have reached reproductive age and face long-lasting complications, specific attention needs to be paid to pregnant cases. This study aimed to investigate the relationship between liver function, perinatal outcomes, and prognosis. A database review was conducted to identify pregnant BA cases with native liver and perinatal data, and clinical information on BA-related complications was analyzed. Perinatal serum cholinesterase (ChE) levels, model for end-stage liver-disease (MELD) score, and platelet trends were analyzed, and the association between these indicators and perinatal outcomes was investigated. Patients were categorized into three groups according to the perinatal clinical outcomes: favorable (term babies with or without several episodes of cholangitis; n = 3), borderline (term baby and following liver dysfunction; n = 1), and unfavorable (premature delivery with subsequent liver failure; n = 1). Lower serum ChE levels, lower platelet counts, and higher MELD scores were observed in the unfavorable category. Borderline and unfavorable patients displayed a continuous increase in MELD score, with one eventually needing a liver transplantation. Pregnancy in patients with BA requires special attention. Serum ChE levels, platelet counts, and MELD scores are all important markers for predicting perinatal prognosis.

6 July 2021 in World Journal of Clinical Cases
Verified
Journal Article
Open access
TFTakumi Fujimura
Takumi Fujimura
YYYohei Yamada
Yohei Yamada
TUTomoshige Umeyama
Tomoshige Umeyama
YKYumi Kudo
Yumi Kudo
HKHiroki Kanamori
Hiroki Kanamori
TKTatsuo Kuroda
Tatsuo Kuroda
Evidence has been published on the successful applications of the anti-tumor necrosis factor alpha antibody infliximab, such as induction therapy, salvage treatment for acute cellular rejection, and treatment for chronic ulcerative inflammation, in intestinal transplant recipients. However, the optimal protocol for the effective use of infliximab remains largely undetermined due to scarcity of available clinical data. We report a continuative application of infliximab as maintenance therapy for recurrent chronic ulcerative ileitis in a recipient of isolated intestinal transplantation (ITx). The patient was a 11-year-old boy with intestinal motility disorder classified as a hypogenic type of intestinal dysganglionosis. The patient underwent living-donor related intestinal transplant. His immunosuppression regimen consisted of daclizumab, tacrolimus, and steroids. Although he did not show rejection while on tacrolimus monotherapy, routine screening endoscopy showed several ulcerative lesions in the distal end of the graft 2 years after the intestinal transplant. Endoscopic work up to evaluate the progression of anemia revealed stenosis with ulcerative inflammatory changes and multiple longitudinal ulcers in the graft. Since the endoscopic findings suggested ulcerative lesions in Crohn’s disease, infliximab treatment was considered. Treatment with infliximab and a small dose of oral prednisolone afforded successful withdrawal of total parenteral nutrition and maintenance of a well-functioning graft without infectious complications for 5 years since the administration of the first dose of infliximab. Infliximab is effective as maintenance therapy for recurrent chronic ulcerative ileitis in an isolated ITx patient.