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Dive into the research topics where Yasuhiko Hamada is active.

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Featured researches published by Yasuhiko Hamada.


Journal of Gastroenterology and Hepatology | 2009

Ease of early gastric cancer demarcation recognition: A comparison of four magnifying endoscopy methods

Shigenori Kadowaki; Kyosuke Tanaka; Hideki Toyoda; Ryo Kosaka; Ichiro Imoto; Yasuhiko Hamada; Masaki Katsurahara; Hiroyuki Inoue; Masatoshi Aoki; Tomohiro Noda; Tomomi Yamada; Yoshiyuki Takei; Naoyuki Katayama

Background and Aim:  Various techniques using magnifying endoscopy (ME) have been developed to enhance images of early gastric cancer (EGC) demarcations, which are often obscure. We investigated four ME methods to determine which is most effective in enhancing the recognition of EGC demarcations: conventional ME (CME), ME with narrow band imaging (NBI‐ME), enhanced‐magnification endoscopy with acetic acid (EME), and ME with NBI and acetic acid (NBI‐EME).


Gastrointestinal Endoscopy | 2008

Surface pattern classification by enhanced-magnification endoscopy for identifying early gastric cancers

Kyosuke Tanaka; Hideki Toyoda; Shigenori Kadowaki; Yasuhiko Hamada; Ryo Kosaka; Shinpei Matsuzaki; Taizo Shiraishi; Ichiro Imoto; Yoshiyuki Takei

BACKGROUND The correlation between fine surface patterns of gastric mucosal lesions and early gastric cancer is not sufficiently clear. OBJECTIVE To evaluate the efficacy of surface pattern classification by enhanced-magnification endoscopy (EME) for identifying early gastric cancers. DESIGN Observational study. SETTING All procedures were performed at Mie University Hospital. PATIENTS A total of 380 consecutive patients who underwent EGD by using magnification endoscopy. Among these subjects were found 250 newly detected lesions suspected of being gastric cancer. METHODS Conventional magnification endoscopy (CME), magnification chromoendoscopy (MCE), and EME were performed, and surface patterns of lesions were classified into 5 types: type I, small round pits of uniform size and shape; type II, slit-like pits; type III, gyrus and villous patterns; type IV, irregular arrangement and size; and type V, destructive pattern. Biopsy specimens were obtained from all lesions. MAIN OUTCOME MEASUREMENTS Correlation between surface pattern classification by EME and histopathologic findings of early gastric cancer. RESULTS Surface patterns were evident by CME/MCE in only 66.4% (166/250) of lesions but in 100% (250/250) of lesions by EME. Classification by EME was as follows: type I, 52 lesions; type II, 12; type III, 146; type IV, 32; and type V, 8. By histopathologic examination, 16 early gastric cancers were detected between type IV or V lesions. Thus, classification of types IV-V strongly correlated with the presence of gastric cancer (sensitivity 100%, specificity 89.7%). LIMITATIONS Single-center study. CONCLUSIONS Surface pattern classification by EME may be useful for identifying early gastric cancers.


International Journal of Cancer | 2007

Protein C inhibitor inhibits breast cancer cell growth, metastasis and angiogenesis independently of its protease inhibitory activity

Kunihiro Asanuma; Tomoaki Yoshikawa; Tatsuya Hayashi; Nobuyuki Akita; Norimi Nakagawa; Yasuhiko Hamada; Junji Nishioka; Haruhiko Kamada; Esteban C. Gabazza; Masaru Ido; Atsumasa Uchida; Koji Suzuki

Protein C inhibitor (PCI) regulates the anticoagulant protein C pathway and also inhibits urinary plasminogen activator (uPA), a mediator of tumor cell invasion. In the present study, we evaluated the effect of human PCI and its inactive derivatives on tumor growth and metastasis of human breast cancer (MDA‐231) cells, and on angiogenesis in vivo. The invasiveness of MDA‐231 cells was inhibited by recombinant intact PCI, but not by reactive site‐modified PCI (R354APCI) or by the N‐terminal fragment of protease‐cleaved PCI (NTPCI). The in vitro invasiveness of MDA‐231 cells expressing intact PCI (MDA‐PCI) was significantly decreased as compared to MDA‐231 cells expressing R354APCI (MDA‐R354APCI) or NTPCI (MDA‐NTPCI). Further, in vivo growth and metastatic potential of MDA‐PCI, MDA‐R354APCI and MDA‐NTPCI cells in severe combined immunodeficient (SCID) mice were significantly decreased as compared to MDA‐Mock cells. Angiogenesis was also significantly decreased in Matrigel implant containing MDA‐PCI, MDA‐R354APCI or MDA‐NTPCI cells as compared to that containing MDA‐Mock cells. In vivo angiogenesis in rat cornea and in vitro tube formation were also inhibited by recombinant intact PCI, R354APCI and NTPCI. Furthermore, the anti‐angiogenic activity of PCI was strong as cleaved antithrombin (AT), and slightly stronger than that of plasminogen activator inhibitor (PAI)‐1 and pigment epithelium‐derived factor (PEDF). Overall, this study showed that, in addition to a reactive site‐dependent mechanism, PCI may also regulate tumor growth and metastasis independently of its protease inhibitory activity by inhibiting angiogenesis.


Pancreas | 2016

Human Equilibrative Nucleoside Transporter 1 Expression in Endoscopic Ultrasonography-Guided Fine-Needle Aspiration Biopsy Samples Is a Strong Predictor of Clinical Response and Survival in the Patients With Pancreatic Ductal Adenocarcinoma Undergoing Gemcitabine-Based Chemoradiotherapy.

Reiko Yamada; Shugo Mizuno; Katsunori Uchida; Misao Yoneda; Kazuki Kanayama; Hiroyuki Inoue; Yasuhiro Murata; Naohisa Kuriyama; Masashi Kishiwada; Masanobu Usui; Noriko; Junya Tsuboi; Shunsuke Tano; Yasuhiko Hamada; Kyosuke Tanaka; Noriyuki Horiki; Toru Ogura; Taizo Shiraishi; Yoshiyuki Takei; Naoyuki Katayama; Shuji Isaji

ObjectivesThis study aimed to clarify whether pretreatment human equilibrative nucleoside transporter (hENT1) expressions in endoscopic ultrasonography-guided fine-needle aspiration biopsy (EUS-FNAB) specimens obtained from resectable, borderline resectable, and locally advanced unresectable pancreatic ductal adenocarcinoma (PDAC) are concordant with those in the resected specimen after gemcitabine-based chemoradiotherapy (Gem-CRT) and to validate the utility of hENT1 expression using EUS-FNAB samples as a prognostic marker. MethodsWe evaluated the relationship between hENT1 expressions assessed by immunohistochemical staining and clinical outcomes in 51 of 76 patients with PDAC who were diagnosed by EUS-FNAB and received preoperative Gem-CRT. ResultsThe concordance rate of hENT1 expressions was 89.2% (K = 0.681). Median survival time (month) in the 51 whole patients and 37 patients with resection was significantly longer in hENT1 positive than in hENT1 negative: 25.0 and 30.0 versus 9.0 and 9.0, respectively. A multivariate analysis confirmed that hENT1 expression was an independent prognostic factor in both whole patients and those with resection. Regardless of T3 and T4, hENT1-positive patients with resection had significantly better prognosis than hENT1-negative patients, whose prognosis was similar to those without resection. ConclusionsThe assessment of hENT1 expression using EUS-FNAB samples before Gem-CRT provides important information on patients with PDAC who can benefit from curative-intent resection.


Digestive Endoscopy | 2006

MAGNIFICATION ENDOSCOPIC VIEW OF AN EARLY GASTRIC CANCER USING ACETIC ACID AND NARROW-BAND IMAGING SYSTEM

Hideki Toyoda; Kyosuke Tanaka; Yasuhiko Hamada; Ryo Kosaka; Ichiro Imoto

A 62‐year‐old woman was referred to Mie University Hospital, Tsu, Japan, for examination of upper gastrointestinal tract. The conventional endoscopy showed a slightly depressed lesion on the greater curvature at the gastric body. The surface of surrounding non‐neoplastic mucosa using magnification endoscopy with acetic acid was gyrus‐villous pattern whereas the surface of the lesion was rough. Furthermore, magnification endoscopy using acetic acid and narrow‐band imaging system visualized clearer fine surface pattern of carcinoma. The lesion had a rough mucosa with irregularly arranged small pits. The lesion was resected completely by endoscopic mucosal resection with insulated‐tip electrosurgical knife. Narrow‐band imaging system with acetic acid may be able to visualize not only the capillary pattern but also the fine surface pattern of gastric carcinoma.


Medicine | 2015

Second and Third-look Endoscopy for the Prevention of Post-ESD Bleeding

Shunsuke Tano; Noriyuki Horiki; Fumio Omata; Kyosuke Tanaka; Yasuhiko Hamada; Masaki Katsurahara; K. Ninomiya; Kenichiro Nishikawa; Keiichiro Nojiri; Reiko Yamada; Hiroyuki Inoue; Esteban C. Gabazza; Naoyuki Katayama; Yoshiyuki Takei

AbstractThe efficacy of 2nd-look esophagogastroduodenoscopy (EGD) with endoscopic hemostatic therapy (EHT) for the prevention of postendoscopic submucosal dissection (ESD) clinical bleeding remains controversial. The aim of this study was to estimate post-ESD bleeding rate using 2nd and 3rd-look strategy, and to determine risk factors for clinical bleeding, and for EHT at 2nd and 3rd-look EGDs.Three hundred forty-four consecutive patients with early gastric cancer or adenoma underwent ESD from January 2006 through March 2012. Second and 3rd-look EGDs were performed on day 1 (D1) and day 7 (D7), respectively, with EHT as needed.Post-ESD clinical bleeding rate was 2.6% (95% confidence interval [CI] 1.2%–4.9%). For clinical bleeding, adjusted odds ratios (ORs) for age <65 years and antithrombotic drug uses were 4.40 (95% CI 1.07–19.93) and 7.34 (95% CI 1.80–32.48), respectively. For D1 EHT, adjusted ORs of tumor location in the lower part of the stomach and maximum tumor diameter ≥60 mm were 2.16 (95% CI 1.35–3.51) and 2.20 (95% CI 1.05–4.98), respectively. For D7 EHT, adjusted OR of D1 EHT was 4.65 (95% CI 1.56–20.0).Post-ESD clinical bleeding rate was relatively low using 2nd and 3rd-look strategy. Age <65 years and antithrombotic drug use are significant risk factors for clinical bleeding. Regarding EHT, tumor location in the lower part of the stomach and maximum diameter of resected specimen ≥60 mm are significant predictors for D1 EHT. D1 EHT in turn is a significant risk factor for D7 EHT. The efficacy of sequential strategy for preventing post-ESD bleeding is promising.


European Journal of Gastroenterology & Hepatology | 2012

Usefulness of endoscopic submucosal dissection for the treatment of rectal carcinoid tumors.

Yasuhiko Hamada; Kyosuke Tanaka; Shunsuke Tano; Masaki Katsurahara; Ryo Kosaka; Tomohiro Noda; Masatoshi Aoki; Hideki Toyoda; Yoshiyuki Takei; Naoyuki Katayama

Background and aim Various techniques of endoscopy have been developed to treat rectal carcinoids. This retrospective study aimed to evaluate the feasibility and efficacy of endoscopic submucosal dissection for the treatment of rectal carcinoids smaller than 10 mm in diameter. Patients and methods A total of 18 consecutive patients were enrolled with 20 carcinoid tumors that had the following characteristics: the diagnosis of a rectal carcinoid smaller than 10 mm, no endoscopic evidence of muscularis propria invasion, and no evidence of lymph node or distant metastasis (11 men and seven women; median age, 69 years; median tumor size, 4 mm). Tumors were resected by endoscopic submucosal dissection with a needle knife and a hook knife. After marking, a one-third to one-half circumferential mucosal incision was made, and subsequently, the submucosa under the lesion was exfoliated. After the submucosa under the tumor was exfoliated, the residual mucosa was incised and the tumor was removed. Complete resection, complication rates, and operation time were evaluated. Results Complete resection was achieved in all cases (100%) without complications. The mean operation time was 34.2 min, which was acceptable in clinical practice. Conclusion Endoscopic submucosal dissection with the strategy described above is feasible and efficacious for selected patients with a rectal carcin-oid smaller than 10 mm.


Digestive Endoscopy | 2008

ENDOSCOPIC SUBMUCOSAL DISSECTION FOR EARLY GASTRIC CANCER USING MAGNIFYING ENDOSCOPY WITH A COMBINATION OF NARROW BAND IMAGING AND ACETIC ACID INSTILLATION

Kyosuke Tanaka; Hideki Toyoda; Yasuhiko Hamada; Masatoshi Aoki; Ryo Kosaka; Tomohiro Noda; Masaki Katsurahara; Hiroyuki Inoue; Ichiro Imoto; Yoshiyuki Takei

Demarcation of early gastric cancers is sometimes unclear. Enhanced‐magnification endoscopy with acetic acid instillation and magnifying endoscopy with a narrow band imaging (NBI) system have been useful for recognition of demarcation of early gastric cancers. We report a patient with early gastric cancer who underwent a successful endoscopic submucosal dissection (ESD) by magnifying endoscopy with the combined use of NBI and acetic acid instillation. A 72‐year‐old man with early gastric cancer underwent ESD. Demarcation of the lesion was not clear, but magnifying endoscopy using the combination of NBI and acetic acid clearly revealed the demarcation. ESD was carried out after spots were marked circumferentially. We identified the positional relation between the demarcation and all markings. Resection of the lesion was on the outside of the markings. Histopathologically, the lesion was diagnosed as a well‐differentiated adenocarcinoma limited to the mucosa. The margins were carcinoma free. Magnifying endoscopy combining the use of NBI with acetic acid instillation is simple and helpful for identifying the demarcation of early gastric cancer. This method may be useful in increasing the rate of complete resection by ESD for early gastric cancer.


Journal of Infection and Chemotherapy | 2015

Endoscopic findings and lesion distribution in amebic colitis

Noriyuki Horiki; Keiichi Furukawa; Takashi Kitade; Takashi Sakuno; Masaki Katsurahara; Tetsuro Harada; Shunsuke Tano; Reiko Yamada; Yasuhiko Hamada; Hiroyuki Inoue; Kyosuke Tanaka; Esteban C. Gabazza; Naoki Ishii; Katsuyuki Fukuda; Fumio Omata; Yoshiyuki Fujita; Hiroshi Tachibana; Yoshiyuki Takei

A retrospective cohort study was conducted in 55 symptomatic patients with amebic colitis that visited at St. Lukes International Hospital and Mie University Hospital from 1994 through 2013. To diagnose amebic colitis, 40 patients underwent total colonoscopy within 1 week after hospital visiting and before receiving any treatment. The percentage of characteristic endoscopic findings of amebic colitis including discrete ulcers or erosions with white or yellow exudates were 0% in terminal ileum, 93% in cecum, 28% in ascending, 25% in transverse, 15% in descending, 20% in sigmoid colon and 45% in rectum. The rectal lesions in 55% of patients with amebic colitis were nonspecific. The trophozoite identification rate by direct smear of intestinal tract washings performed during colonoscopy was 88%. The protozoan identification rate was 70% in biopsy specimens taken from the periphery of the characteristic discrete ulcers. Total colonoscopy should be considered for the diagnosis of amebic colitis.


Internal Medicine | 2015

Usefulness of Small Intestinal Endoscopy in a Case of Adult-onset Familial Mediterranean Fever Associated with Jejunoileitis

Takashi Kitade; Noriyuki Horiki; Masaki Katsurahara; Toshiaki Totoki; Tetsuro Harada; Shunsuke Tano; Reiko Yamada; Yasuhiko Hamada; Hiroyuki Inoue; Kyosuke Tanaka; Esteban C. Gabazza; Hiroyuki Hayashi; Masanori Tanaka; Yoshiyuki Takei

A 66-year-old Japanese man consulted our institution due to paroxysmal and repetitive bouts of fever and abdominal pain that had persisted for more than one week. Capsule and double-balloon endoscopy (DBE) showed petal-shaped mucosal redness with white hemming in the jejunum and ileum, and histopathology of the biopsy specimens revealed villous atrophy and cryptitis with extensive severe neutrophil infiltration. A genetic examination disclosed compound heterozygous MEFV mutations (E84K, P369S), and familial Mediterranean fever was diagnosed. Treatment with colchicine and infliximab was very effective in inducing the complete disappearance of symptoms and normalization of the endoscopic findings. To the best of our knowledge, this is the first report to describe the findings of small intestinal endoscopic images obtained using capsule and DBE.

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