Timing of pyloric stenosis and effectiveness of endoscopic balloon dilation after pyloric endoscopic submucosal dissection.

BACKGROUND AND AIM: There have been studies on risk factors for stenosis after pyloric endoscopic submucosal dissection (ESD). However, the most appropriate strategies for the management of cases with these risk factors have not been established. This study aimed to investigate post-ESD management by evaluating the timing of stenosis and the effectiveness of endoscopic balloon dilation (EBD) after pyloric ESD. METHODS: We retrospectively reviewed cases of pyloric ESD. We first reassessed risk factors for stenosis in multivariate analysis and receiver operating characteristic curve and defined patients with the identified risk factors as the risk group. The primary outcome was the timing of stenosis in the risk group assessed by the Kaplan-Meier method. RESULTS: We reviewed 159 cases with pyloric ESD and observed pyloric stenosis in 25 cases. Cases with circumferential mucosal defect ≥ 76% were identified as the risk group. The stenosis-free probability in the risk group was 97% (95% confidence interval [CI]: 79-100%), 94% (95% CI: 76-98%), and 85% (95% CI: 66-93%) on days 7, 14, and 21, respectively. It decreased every week thereafter and did not significantly change after day 56. Twenty-three stenosis cases, except for conservative improvement, including six whole circumferential pyloric ESD cases, were improved by EBD without complications. CONCLUSIONS: Post-ESD stenosis often developed from the third to the eighth week. In all pyloric ESD cases, including whole circumferential pyloric ESD cases, pyloric stenosis was improved following EBD without complications.

Detection of Novel Amino Acid Polymorphisms in the East Asian CagA of Helicobacter Pylori with Full Sequencing Data.

Cytotoxin-associated gene A (CagA) is generally accepted to be the most important virulence factor of Helicobacter pylori and increases the risk of developing gastric cancer. East Asian CagA, which includes the EPIYA-D segment at the C-terminal region, has a significantly higher gastric carcinogenic rate than Western CagA including the EPIYA-C segment. Although the amino acid polymorphism surrounding the EPIYA motif in the C-terminal region has been examined in detail, limited information is currently available on the amino acid polymorphism of the N-terminal region of East Asian CagA. In the present study, we analyzed the sequencing data of East Asian CagA that we obtained previously to detect amino acid changes (AACs) in the N-terminal region of East Asian CagA. Four highly frequent AACs in the N-terminal region of East Asian CagA were detected in our datasets, two of which (V356A, Y677F) exhibited reproducible specificity using a validation dataset from the NCBI database, which are candidate AACs related to the pathogenic function of CagA. We examined whether these AACs affect the functions of CagA in silico model. The computational docking simulation model showed that binding affinity between CagA and phosphatidylserine remained unchanged in the model of mutant CagA reflecting both AAC, whereas that between CagA and α5ß1 integrin significantly increased. Based on whole genome sequencing data we herein identified novel specific AACs in the N-terminal regions of EPIYA-D that have the potential to change the function of CagA.

Effects of Helicobacter pylori on the glutathione-related pathway in gastric epithelial cells.

Virulence factors of Helicobacter pylori (H. pylori) are diverse, so various biological responses happen in a host infected with H. pylori. The aim of this study is to conduct the metabolomics-based evaluation on H. pylori infection. AGS human gastric carcinoma cells were infected with H. pylori strain 26695, and then the altered metabolite pathways in the infected AGS cells were analyzed by metabolomics. Metabolites related to the glutathione (GSH) cycle were downregulated by H. pylori infection. Next, we evaluated the effects of H. pylori on the GSH-related pathway in AGS cells infected with H. pylori isolated from patients with atrophic gastritis (AG), duodenal ulcer (DU) and gastric cancer (GC). We found that the declined degree of GSH levels and oxidative stress were greater in AGS cells infected with GC strains than DU and AG-derived strains. There were no significant differences in almost mRNA expressions of GSH-related factors among different clinical strains, but the protein expression of glutathione synthetase was lower in AGS cells infected with GC-derived strains than DU and AG-derived strains. Our data demonstrates that GC-derived H. pylori-induced oxidative stress in a host is stronger and GC-derived strains may have suppressive influences on the host's GSH-related defense systems.

Differences in edge artifacts between 68Ga- and 18F-PET images reconstructed using point spread function correction.

OBJECTIVE: Edge artifacts have been reported on in relation to F-PET using point spread function correction algorithms. The positron range of Ga is longer than F, and this difference is thought to result in different edge artifacts. The purpose of this study is to clarify the difference in edge artifacts in PET images using point spread function correction in Ga- and F-PET. METHODS: We used a National Electrical Manufacturers Association International Electrotechnical Commission body phantom. The phantom was filled severally with Ga and F solution. The PET data were obtained over a 90 minutes period using a True Point Biograph 16 scanner. The images were then reconstructed with the ordered subset expectation maximization with point spread function correction. The phantom image analyses were performed by a visual assessment of the PET images and profiles, and an absolute recovery coefficient, which was the ratio of the maximum radioactivity of any given hot sphere to its true radioactivity. RESULTS: The ring-like edge artifacts of Ga-PET were less prominent than those in F-PET. The relative radioactivity profiles of Ga-PET showed low overshoots of the maximum radioactivity although high overshoots did appear in F-PET. The absolute recovery coefficients of Ga-PET were smaller than those of F-PET. CONCLUSION: The edge artifacts of Ga-PET were less prominent than those of F-PET, and their overshoots were smaller. The difference in the positron range between Ga and F may possibly result in the difference in edge artifacts of images reconstructed using the point spread function correction algorithm.

Influence of region-of-interest determination on measurement of signal-to-noise ratio in liver on PET images.

OBJECTIVE: On 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET), signal-to-noise ratio in the liver (SNRliver) is used as a metric to assess image quality. However, some regions-of-interest (ROIs) are used when measuring the SNRliver. The purpose of this study is to examine the different ROIs and volumes of interest (VOIs) to obtain a reproducible SNRliver. METHODS: This study included 108 patients who underwent 18F-FDG-PET/CT scans for the purpose of cancer screening. We examined four different ROIs and VOIs; a 3-cm-diameter and a 4-cm-diameter circular ROI and a 3-cm-diameter and a 4-cm-diameter spherical VOI on the right lobe of the patients' livers. The average of SUV (SUVmean), standard deviation (SD) of SUV (SUVSD), SNRliver and SD of the SNRliver obtained using ROIs and VOIs were then compared. RESULTS: Although the SUVmean was not different among the ROIs and VOIs, the SUVSD was small with a 3-cm-diameter ROI. The largest SUVSD was obtained with a 4-cm-diameter spherical VOI. The SNRliver and the SD of the SNRliver with a 4-cm-diameter spherical VOI were the smallest, while those with a 3-cm-diameter circular ROI were the largest. These results suggest that a small ROI may be placed on a relatively homogeneous region not representing whole liver unintentionally. CONCLUSION: The SNRliver varied according to the shape and size of ROIs or VOIs. A 4-cm-diameter spherical VOI is recommended to obtain stable and reproducible SNRliver.