Kohei Funasaka

ARHGAP18, a GTPase activating protein for RhoA, controls cell shape, spreading and motility

Using a library of siRNAs, we found that ARHGAP18 was essential for the organization of actin stress fibers and focal adhesion. ARHGAP18 is one of the crucial factors for the regulation of RhoA in order to control cell motility and spreading.

Characterization of bacterial biota in the distal esophagus of Japanese patients with reflux esophagitis and Barrett’s esophagus

BackgroundThe distal esophagus harbors a complex bacterial population. We hypothesized that a better understanding of bacterial communities in the esophagus would facilitate understanding of the role of bacteria in esophageal disease. Here, we investigated bacterial composition in the distal esophagus in subjects with a normal esophagus, reflux esophagitis, and Barrett’s esophagus.MethodsTwo biopsy specimens were obtained from the distal esophagus at 1 cm above the gastroesophageal junction under endoscopic examination in 18 patients (6 each with normal esophagus, reflux esophagitis, and Barrett’s esophagus) and used for histological examination and DNA extraction. Fragments of 16S rDNA genes were amplified by PCR using general bacterial primers, and bacterial populations were examined. A third biopsy specimen was taken from the patients with Barrett’s esophagus to histologically confirm the replacement of squamous epithelium with columnar epithelium in the distal esophagus.ResultsEndoscopic diagnoses of normal esophagus, esophagitis, and Barrett’s esophagus were confirmed by histological findings. The total amount of bacterial DNA detected did not significantly differ among groups (p > 0.1). On average, each of the 18 subjects yielded about 350 clones, of which 40 were randomly picked and sequenced. Analysis of 147 16S rDNA sequences from 240 clones of 6 subjects with normal esophagus yielded four phyla, Proteobacteria (49%), Firmicutes (40%), Bacteroidetes (8%), and Actinobacteria (3%). Similar analysis of 139 16S rDNA sequences from 240 clones of 6 patients with reflux esophagitis yielded 6 phyla, Proteobacteria (43%), Firmicutes (33%), Bacteroidetes (10%), Fusobacteria (10%), Actinobacteria (2%), and TM7 (2%). while that of 138 16S rDNA sequences from 240 clones of 6 cases of Barrett’s esophagus yielded 5 phyla, Firmicutes (55%), Proteobacteria (20%), Bacteroidetes (14%), Fusobacteria (9%), and Actinobacteria (2%). Thus, microbial communities differed among patients with a normal esophagus, reflux esophagitis and Barrett’s esophagus.ConclusionsEsophageal bacterial composition differs under conditions of normal esophagus, reflux esophagitis, and Barrett’s esophagus. Diverse bacterial communities may be associated with esophageal disease.

Dipeptidyl peptidase-4 inhibitor anagliptin facilitates restoration of dextran sulfate sodium-induced colitis

Abstract Objective. Inflammatory bowel disease (IBD) is a chronic debilitating disease associated with severe damage to the intestinal mucosa. Glucagon-like peptide-2 (GLP-2) is a potent and specific gastrointestinal growth factor. GLP-2 released from enteroendocrine cells is inactivated by dipeptidyl peptidase-4 (DPP-4). The aim of this study was to examine whether the DPP-4 inhibitor anagliptin improves experimental murine colitis. Material and methods. Male C57BL/6 mice aged 8 weeks were exposed to 1.5% dextran sulfate sodium (DSS) in drinking water for 7 days to induce experimental colitis. Anagliptin (0.1% in diet) was administrated from 2 days before the beginning of DSS to 7 days after the end of DSS. Changes in body weight and disease activity index were evaluated daily. Histological colitis severity, cellular proliferation and gene expression were determined in colonic tissues. Results. Treatment with anagliptin clearly improved body weight loss and disease activity index in the recovery phase. Histological score in the DSS + anagliptin group at day 14 was significantly lower than that in the DSS alone group. Treatment with anagliptin increased the Ki67-positive rate at days 10 and 14, and tended to increase insulin-like growth factor-1 mRNA expression in the DSS + anagliptin group. Conclusion. In this model of experimental colitis, the DPP-4 inhibitor anagliptin facilitated the restoration of mucosal damage, thereby resulting in the acceleration of healing. These findings suggest a new and novel therapeutic approach for the treatment of IBD.

Risk factors of symptomatic NSAID-induced small intestinal injury and diaphragm disease

The aetiology for nonsteroidal anti‐inflammatory drug (NSAID)‐induced small intestinal injuries has not been well characterised.

Cas utilizes Nck2 to activate Cdc42 and regulate cell polarization during cell migration in response to wound healing.

Integrin‐mediated activation of Cdc42 is essential for cell polarization, whereas the integrin adaptor protein Cas is required for cell migration during wound healing. After phosphorylation on tyrosine residues, Cas recruits the adaptor proteins Crk and Nck to execute integrin‐mediated signals. However, the mechanisms leading to Cdc42 activation and its relationship with Cas, Crk and Nck have not been elucidated clearly. In the present study, we demonstrate that Cas utilizes Nck2 to activate Cdc42 and induce cell polarization in response to wounding. By contrast, Cas recruits CrkII to activate Rac1 and promote the extension of cell protrusions needed for cell motility. These results indicate that Cas utilizes Nck2 and CrkII in a coordinated set of distinct pathways leading to cell migration.

Forward-viewing versus oblique-viewing echoendoscopes in the diagnosis of upper GI subepithelial lesions with EUS-guided FNA: a prospective, randomized, crossover study.

BACKGROUND The role of the forward-viewing echoendoscope compared with the oblique-viewing echoendoscope for EUS-guided FNA (EUS-FNA) of upper GI subepithelial lesions has not been defined. OBJECTIVE To compare the diagnostic yield and clinical efficacy of EUS-FNA by using the 2 echoendoscopes in the same upper GI subepithelial lesion. DESIGN Prospective, randomized, crossover study. SETTING Tertiary-care medical center. PATIENTS Forty-one patients with an upper GI subepithelial lesion. INTERVENTIONS All patients first underwent EUS-FNA with a 19-gauge needle by using both echoendoscopes, based on random selection. When required, 22-gauge or 25-gauge needles were used additionally. MAIN OUTCOME MEASUREMENTS Comparison of diagnostic yield, tissue sample area, puncture success rates, procedure time, and adverse events. RESULTS Forty-one patients (median lesion size 22 mm, range 15-63 mm) were enrolled. Rates of histologic diagnosis were 80.5% (33/41) and 73.2% (30/41) (P=.453) by using forward-viewing and oblique-viewing echoendoscopes, respectively. Median tissue sample area in GI stromal tumors (n=22) obtained with the forward-viewing echoendoscope was larger than with the oblique-viewing echoendoscope (2.46 mm2 vs 1.00 mm2; P=.046). Puncture success rates were 39 of 41 (95.1%) and 35 of 41 (85.4%; P=.289) with forward-viewing and oblique-viewing echoendoscopes, respectively. Median procedure time was 21 minutes with the forward-viewing echoendoscope and 27 minutes with the oblique-viewing echoendoscope (P=.009). An infectious adverse event occurred in a patient and was treated with antibiotics. LIMITATIONS Small sample size. CONCLUSION Diagnostic yield did not differ between the 2 echoendoscopes. However, tissue sample area and procedure time were superior with the forward-viewing echoendoscope.

Simplified magnetic anchor-guided endoscopic submucosal dissection in dogs (with videos)

BACKGROUND Magnetic anchor-guided endoscopic submucosal dissection (MAG-ESD) was developed to reduce adverse events such as bleeding and perforation and to facilitate ESD. However, the external electromagnet required miniaturization to make it suitable for daily clinical practice. OBJECTIVE To evaluate the feasibility of simplified MAG-ESD using permanent magnets. DESIGN Case series. SETTING Nagoya University Hospital. SUBJECTS Beagle dogs. INTERVENTIONS The simplified MAG-ESD was performed on 10 representative areas of the stomachs of beagle dogs. The magnetic anchor consisted of an internal magnet attached to a hemoclip. The external and internal magnets were made from the rare earth neodymium. MAIN OUTCOME MEASUREMENTS The feasibility of countertraction with good visualization using simplified MAG-ESD. The rate of perforation, the time required for preparation, and attaching the magnetic anchor were also evaluated. RESULTS All lesions were successfully resected without perforation. The magnetic anchor could be controlled easily, and direct visualization was maintained by adequate counter traction. Preparing the magnetic anchor and grasping the mucosal edge using the hemoclip was easy and required a median of only 4 minutes (range, 2-7 minutes). LIMITATIONS Animal experiment, low number and lesion size. CONCLUSIONS This simplified MAG-ESD is feasible and allowed excellent visualization in the dog stomach. The feasibility of this system should be assessed in humans.

Silencing of STRN4 suppresses the malignant characteristics of cancer cells

The striatin family of proteins, comprising STRN, STRN3 and STRN4, are multidomain‐containing proteins that associate with additional proteins to form a large protein complex. We previously reported that STRN4 directly associated with protein kinases, such as MINK1, TNIK and MAP4K4, which are associated with tumor suppression or tumor progression. However, it remains unclear whether STRN4 is associated with tumor progression. In this report, we examined the role that STRN4 plays in cancer malignancy. We show that depletion of STRN4 suppresses proliferation, migration, invasion and the anchorage‐independent growth of cancer cells. In addition, STRN4 knockdown increases the sensitivity of pancreatic cancer cells to gemcitabine. Finally, we show that STRN4 knockdown suppresses the proliferation and metastasis of cancer cells in mice. Our results demonstrate a possible role of STRN4 in tumor progression.

Narrow-band imaging and white-light endoscopy with optical magnification in the diagnosis of dysplasia in Barrett’s esophagus: results of the Asia-Pacific Barrett’s Consortium

Objective: The advent and utility of new endoscopic imaging modalities for predicting the histology of Barrett’s esophagus (BE) in real time with high accuracy appear promising and could potentially obviate the need to perform random biopsies where guidelines are poorly adhered to. We embarked on evaluating the performance characteristics of white-light endoscopy with magnification (WLE-z), narrow-band imaging with magnification (NBI-z) and a combination of both modalities. Design: This was a prospective online study with 28 endoscopists from 11 countries (Asia-Pacific region) participating as assessors. In total, 35 patients with BE were assessed using 150 slides from WLE-z and NBI-z randomly arranged using a simple classification with corresponding histology. The overall Accuracy (Acc), Sensitivity (Sn), Specificity (Sp), Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of WLE-z, NBI-z and a combination of both were calculated. Results: The overall Acc for WLE-z and NBI-z images was 87.1 % and 88.7 %, respectively. When images from the two modalities were placed side by side, the Acc increased to 90.3 %. The Sn, Sp, PPV, and NPV of WLE-z were 48 %, 92 %, 45 %, and 93 % while with NBI-z, these improved to 89 %, 89 %, 56 %, and 98 %, respectively. When both imaging modalities were viewed together, they improved further to 93 %, 90 %, 61 %, and 99 %. Conclusion: The high NPV (99 %) when both WLE-z and NBI-z were used simultaneously indicates that areas with regular appearance that are diagnosed with confidence can effectively be left alone and not biopsied when performed at a skilled resourced center. This approach could potentially lead to a paradigm shift of how patients with BE are assessed.

Usefulness and safety of endoscopic retrograde cholangiopancreatography in children with pancreaticobiliary maljunction.

BACKGROUND To assess the diagnostic ability and safety of endoscopic retrograde cholangiopancreatography (ERCP) in in-depth preoperative examination of children patients with pancreaticobiliary maljunction (PBM). METHODS In 63 patients with a definite diagnosis of PBM, the ability to visualize the bile and main pancreatic ducts was compared between ERCP, which was performed in 63 patients with a definite diagnosis of PBM, and magnetic resonance cholangiopancreatography (MRCP), which was performed before ERCP in 29 patients. For ERCP, its complications were also evaluated. RESULTS The intrahepatic bile ducts could be visualized using ERCP in 44 patients (69.8%) and using MRCP in 18 (62.1%). The extrahepatic bile ducts could be visualized using ERCP in 59 patients (93.7%) and using MRCP in 29 (100%). The rates of the visualization of the main pancreatic duct and pancreaticobiliary ductal union were significantly higher in using ERCP than in using MRCP (96.8 vs. 41.4% and 90.5 vs. 37.9%, respectively; P<0.0001). As complications, hyperamylasemia developed in 12 patients (19%), but no other severe complications such as pancreatitis were observed. CONCLUSIONS ERCP as part of an in-depth preoperative examination of children with PBM is useful and safe.