Seismic Performance Evaluation of Improved Jet Grouted Grid Form with Horizontal Slab in Liquefaction Mitigation

A chain event of the 2016 Kumamoto earthquakes caused considerable geotechnical damage related to liquefaction in many places around Kumamoto plain. Many low-rise houses and traditional Japanese style houses, which were constructed on shallow foundation, suffered differential settlement and tilting due to liquefaction. To mitigate the building damages due to the liquefaction, a new countermeasure method of jet grout grid form with a horizontal slab is introduced in this study. The effectiveness of the proposed technique was evaluated through physical modelling and numerical modelling. As a part of the physical modelling, a set of 1 g shaking table tests for unimproved case and improved case were performed, in which the mitigation effects of the grid form with a horizontal reinforcing slab were examined based on the acceleration, excess pore water pressure ratio as well as ground settlement. Numerical simulation was also performed for assessing the effect of improved method on soil-structure interaction and building settlement during the earthquake. The physical and numerical results confirmed that the grid form with horizontal slab reinforced method is effective in settlement control and offers favorable contribution in liquefaction mitigation.

Postoperative bleeding in patients on antithrombotic therapy after gastric endoscopic submucosal dissection

AIM To investigated the relationship between postoperative bleeding following gastric endoscopic submucosal dissection(ESD) and individual antithrombotic agents.METHODS A total of 2488 gastric neoplasms in 2148 consecutive patients treated between May 2001 and June 2016 were studied. The antithrombotic agents were categorized into antiplatelet agents, anticoagulants, and other antithrombotic agents, and we included combination therapies [e.g., dual antiplatelet therapy(DAPT)]. The risk factors associated with post-ESD bleeding, namely, antithrombotic agents overall, individual antithrombotic agents, withdrawal or continuation of antithrombotic agents, and bleeding onset period(during the first six days or thereafter), were analyzed using univariate and multivariate analyses.RESULTS The en bloc resection and complete curative resection rates were 99.2% and 91.9%, respectively. Postoperative bleeding occurred in 5.1% cases. Bleeding occurred in 10.3% of the patients administered antithrombotic agents. Being male(P = 0.007), specimen size(P < 0.001), and antithrombotic agent used(P < 0.001) were independent risk factors for postoperative bleeding. Heparin bridging therapy(HBT)(P = 0.002) and DAPT/multidrug combinations(P < 0.001) were independent risk factors associated with postoperative bleeding. The bleeding rate of the antithrombotic agent continuation group was significantly higher than that of the withdrawal group(P < 0.01). Bleeding within postoperative day(POD) 6 was significantly higher in warfarin(P = 0.015), and bleeding after POD 7 was significantly higher in DAPT/multidrug combinations(P = 0.007). No thromboembolic events were reported.CONCLUSION We must closely monitor patients administered HBT and DAPT/multidrug combinations after gastric ESD, particularly those administered multidrug combinations after discharge.

Clinicopathological features of early gastric cancers arising in Helicobacter pylori uninfected patients

BACKGROUND Persistent Helicobacter pylori(H.pylori)infection causes chronic inflammation,atrophy of the gastric mucosa,and a high risk of developing gastric cancer.In recent years,awareness of eradication therapy has increased in Japan.As H.pylori infections decrease,the proportion of gastric cancers arising from H.pylori uninfected gastric mucosa will increase.The emergence of gastric cancer arising in H.pylori uninfected patients though rarely reported,is a concern to be addressed and needs elucidation of its clinicopathological features.AIM To evaluate the clinicopathological features of early gastric cancer in H.pyloriuninfected patients.METHODS A total of 2462 patients with 3375 instances of early gastric cancers that were treated by endoscopic submucosal dissection were enrolled in our study between May 2000 and September 2019.Of these,30 lesions in 30 patients were diagnosed as H.pylori-uninfected gastric cancer(Hp UIGC).We defined a patient as H.pylori-uninfected using the following three criteria:(1)The patient did not receive treatment for H.pylori,which was determined by investigating medical recordsand conducting patient interviews;(2)Lack of endoscopic atrophy;and(3)The patient was negative for H.pylori after being tested at least twice using various diagnostic methods,including serum anti-H.pylori-Ig G antibody,urease breath test,rapid urease test,and microscopic examination.RESULTS The frequency of Hp UIGC was 1.2%(30/2462)for the patients in our study.The study included 19 males and 11 females with a mean age of 59 years.The location of the stomach lesions was divided into three sections;upper third(U),middle third(M),lower third(L).Of the 30 lesions,15 were U,1 was M,and 14 were L.Morphologically,17 lesions were protruded and flat elevated type(0-I,0-IIa,0-IIa+IIc),and 13 lesions were flat and depressed type(0-IIb,0-IIc).The median tumor diameter was 8 mm(range 2-98 mm).Histological analysis revealed that22 lesions(73.3%)were differentiated type.The Hp UIGC lesions were classified into fundic gland type adenocarcinoma(7 cases),foveolar type welldifferentiated adenocarcinoma(8 cases),intestinal phenotype adenocarcinoma(7 cases),and pure signet-ring cell carcinoma(8 cases).Among 30 Hp UIGCs,24 lesions(80%)were limited to the mucosa;wherein,the remaining 6 lesions showed submucosal invasion.One of the submucosal invasive lesions showed more than 500μm invasion.The mucin phenotype analysis identified 7 Hp UIGC with intestinal phenotype and 23 with gastric phenotype.CONCLUSION We elucidated the clinicopathological characteristics of Hp UIGC,revealing recognition not only undifferentiated-type but also differentiated-type.In addition,intestinal phenotype tumors were also observed and could be an important tip.

Coagulation syndrome: Delayed perforation after colorectal endoscopic treatments

Various procedure-related adverse events related to colonoscopic treatment have been reported. Previous studies on the complications of colonoscopic treatment have focused primarily on perforation or bleeding. Coagulation syndrome(CS), which is synonymous with transmural burn syndrome following endoscopic treatment, is another typical adverse event. CS is the result of electrocoagulation injury to the bowel wall that induces a transmural burn and localized peritonitis resulting in serosal inflammation. CS occurs after polypectomy, endoscopic mucosal resection(EMR), and even endoscopic submucosal dissection(ESD). The occurrence of CS after polypectomy or EMR varies according previous reports; most report an occurrence rate around 1%. However, artificial ulcers after ESD are largely theoretical, and CS following ESD was reported in about 9% of cases, which is higher than that for CS after polypectomy or EMR. Most cases of post-polypectomy syndrome(PPS) have an excellent prognosis, and they are managed conservatively with medical therapy. PPS rarely develops into delayed perforation. Delayed perforation is a severe adverse event that often requires emergency surgery. Since few studies have reported on CS and delayed perforation associated with CS, we focused on CS after colonoscopic treatments in this review. Clinicians should consider delayed perforation in CS patients.

Case of a tumor comprising gastric cancer and duodenal neuroendocrine tumor

The present report describes a rare case of a tumor composed of early gastric cancer and a duodenal neuroendocrine tumor(NET). A 78-year-old woman underwent esophagogastroduodenoscopy at a local institution for screening of the upper gastrointestinal tract which revealed a protruded tumor through the pyloric ring from the pyloric antrum. The tumor was too large to treat at the facility; consequently, she was referred to our hospital for further management. Esophagogastroduodenoscopy with tumor biopsy of the lesion revealed the diagnosis of early gastric cancer. Endoscopic submucosal dissection was performed with sufficient free margins in both vertical and horizontal directions. Histopathological findings showed NET confined to the submucosal layer and covered by welldifferentiated adenocarcinoma. Immunohistochemical stainings showed that the two lesions existed continuously. While the possibility of a collision cancer was considered, it was suggested that the two lesions existed continuously. Finally, the tumor was diagnosed as gastric cancer composed of duodenal NET G1, with a lymphatic invasion of NET component.