Factors Predicting Difficult Biliary Cannulation during Endoscopic Retrograde Cholangiopancreatography for Common Bile Duct Stones

Background/Aims Difficult biliary cannulation is an important risk factor for post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). Therefore, this study aimed to identify the factors that predict difficult cannulation for common bile duct stones (CBDS) to reduce the risk for PEP. Methods This multicenter retrospective study included 1,406 consecutive patients with native papillae who underwent ERCP for CBDS. Factors predicting difficult cannulation for CBDS were identified using univariate and multivariate analyses. Results Univariate analysis showed that six factors significantly predicted difficult cannulation: ERCP performed by non-expert endoscopists, low-volume center, absence of acute cholangitis, normal serum bilirubin, intradiverticular papilla, and type of major duodenal papilla. Multivariate analysis identified ERCP performed by non-expert endoscopists (odds ratio [OR], 2.5; p<0.001), low-volume center (OR, 1.6; p<0.001), intradiverticular papilla (OR, 1.3; p=0.007), normal serum bilirubin (OR, 1.3; p=0.038), and absence of acute cholangitis (OR, 1.3; p=0.049) as factors significantly predicting difficult cannulation for CBDS. Conclusions Initial cannulation by an experienced endoscopist, early rescue cannulation, or early takeover by an experienced endoscopist should be considered when performing ERCP for CBDS in the presence of factors predicting difficult cannulation

Unusual Fracture Behavior of Slide-Ring Gels with Movable Cross-Links

In this study, the quasi-static fracture behavior of slide-ring gels (SR gels), in which movable cross-links can slide on polymer chains, is for the first time investigated and compared to that of conventional polymer gels with fixed cross-links (FC gels). For the usual FC gels, there is a trade-off relation between toughness (fracture energy Γ) and stiffness (Young’s modulus <i>E</i>): with increasing cross-linking density, the Young’s modulus <i>E</i> increases, while fracture energy Γ decreases. However, SR gels show an unusual fracture behavior that contradicts this trade-off relation. The fracture energy of SR gels is independent of the Young’s modulus, in other words, the cross-linking density; moreover, it rises with increasing slidable range of movable cross-links on polymer chains. A new molecular model is proposed by attributing the unusual fracture properties of SR gels to the relative sliding movement between polymer chains and cross-links. Utilizing this concept, simultaneous fulfillment of high stiffness and high toughness in polymer gels can be realized

Progression patterns and site‐specific responses in advanced gastric cancer patients treated with nivolumab

Abstract Background While the efficacy of immune checkpoint inhibitors (ICIs) reportedly varies among metastatic sites and progression patterns (classified as systemic progression [SP] or mixed progression [MP]), the clinical efficacy of ICIs against gastric cancer remains unclear. The response to nivolumab depending on metastatic site and clinical outcomes according to progression pattern in patients with advanced gastric cancer was investigated retrospectively. Methods Seventy‐four advanced gastric cancer patients with measurable lesions who received nivolumab monotherapy between 2015 and 2020 were enrolled. Progression‐free survival (PFS), overall survival, response at each metastatic site, and clinical outcomes according to progression pattern were analyzed retrospectively. SP and MP were defined as progression in more than half of the lesions and progression in half or fewer of the lesions, respectively, in cases evaluated as progressive disease. Results Thirty‐five (47%) and 27 (36%) patients had SP and MP, respectively, and 12 (16%) patients experienced no progression. The progression rates of target lesions in the lung (44%) and liver (57%) were significantly higher than that in the lymph nodes (18%) (lung vs. lymph node, p < 0.001; liver vs. lymph node, p = 0.03). Patients with MP had superior PFS to those with SP (median, 2.6 vs. 1.5 months; HR, 0.42; 95% CI, 0.23–0.76; p = 0.004). In MP group, patients with treatment beyond progression (TBP) with nivolumab had a trend of longer post‐progression survival than those without TBP (median, 8.0 vs. 4.0 months; HR, 0.55; 95% CI, 0.23–1.29; p = 0.161). Conclusion Patients with MP had a longer PFS than those with SP. Lung and liver metastases had a poorer response to an ICI than lymph node metastases