High-energy-resolution angle-resolved inverse-photoelectron spectroscopy apparatus for damage-free measurements of conduction band structures of functional materials.

The energy band structure of the conduction band (energy-momentum relation of electrons) is crucial to understanding the electron transport of crystalline materials. In this paper, we describe an angle-resolved low-energy inverse photoelectron spectroscopy (AR-LEIPS) apparatus that examines the conduction band structures of materials sensitive to the electron beam, such as organic semiconductors and organic-inorganic hybrid perovskites. The principle of this apparatus is based on AR inverse photoelectron spectroscopy. To minimize radiation damage and improve energy resolution, we employed our previous approach used in LEIPS [H. Yoshida, Chem. Phys. Lett. 539-540, 180 (2012)]. We obtained an overall energy resolution of 0.23 eV with a momentum resolution of 0.9 nm-1 at the electron kinetic energy of 2 eV or higher.

Self-expandable metal stents have longer patency and less cholangitis than inside stents in malignant perihilar biliary obstruction.

Background and Aim: Outcomes of an inside stent (IS, a plastic stent placed above the sphincter of Oddi) versusa self-expandable metal stent (SEMS) for the drainage of malignant perihilar biliary obstruction has not been fully studied. The drainage strategy for perihilar biliary obstruction is difficult and should be clarified. Methods: Clinical data of patients who underwent biliary drainage for malignant perihilar biliary obstruction with IS or SEMS between April 2016 and September 2021 at our institution were retrospectively examined. Outcomes, including the time to recurrent biliary obstruction (TRBO), survival, and incidence of recurrent biliary obstruction with concomitant cholangitis (RBOC), were retrospectively evaluated. Results: Median TRBO was 280 (95% confidence interval [CI], 110-not available) days in the SEMS group (n = 24) and 113 (95% CI, 74-192) days in the IS group (n = 25) (P = 0.043). Among the patients with perihilar cholangiocarcinoma, the median survival of the two groups was comparable, namely 330 days in the SEMS group and 359 days in the IS group (P = 0.46). The incidence of RBOC at re-intervention was significantly higher in patients with ISs (83.9%) than in those with SEMSs (0%) (P = 0.00004). Conclusions: TRBO was significantly longer in the SEMS group. Regardless of whether SEMSs or ISs were placed during the first intervention, patient survival was similar. Using easily removable ISs first might be a reasonable option because TRBO with SEMSs was shorter than patient survival. Cholangitis is a problem associated with the placement of IS.

Neutrophil Infiltration and Acinar-ductal Metaplasia Are the Main Pathological Findings in Pembrolizumab-induced Pancreatitis.

The histopathological findings of immune checkpoint inhibitor (ICI)-induced pancreatitis have rarely been reported. A 56-year-old man with squamous cell carcinoma of the lung with bone metastasis was being treated with pembrolizumab, an anti-programmed cell death protein-1 antibody. After 13 doses, he was referred to our department due to pancreatitis. Despite characteristic symptoms of acute pancreatitis, imaging findings were similar to those of autoimmune pancreatitis. However, a histological examination showed neutrophil-based inflammatory cell infiltration and acinar-ductal metaplasia. Immunostaining showed CD8-positive T lymphocyte infiltration. This case revealed the characteristic histopathology of pembrolizumab-induced pancreatitis, which was previously poorly understood.

Nasopancreatic Drainage for 4 Patients during the Early Phase of Acute Pancreatitis.

We encountered 4 patients with acute pancreatitis (AP) of various etiologies and coexisting acute cholangitis who underwent endoscopic biliary stenting (EBS) and nasopancreatic drainage (NPD) via endoscopic retrograde cholangiopancreatography (ERCP) during the early phase of AP. ERCP is performed to treat acute cholangitis even in the context of AP. However, in difficult cases, accidental contrast media injection or guidewire insertion into the pancreatic duct can happen during ERCP for the purpose of EBS. It is concerned that cannulation injury and increased pancreatic duct pressure can exacerbate existing AP. Because pancreatic guidewire-associated techniques were required for all of them due to difficult biliary cannulation, we performed a NPD catheter placement using the pancreatic guidewire to decompress the pancreatic duct to prevent further exacerbating AP. Surprisingly, all patients dramatically improved without systemic or local complications. NPD could be performed without any adverse events and did not worsen the course of AP. Early decompression of a pancreatic duct using NPD may rather improve AP that had already developed. Further prospective research is needed to confirm our observations.

Presymptomatic Crohn's Disease in a Young Patient Diagnosed Just After the Onset of Idiopathic Acute Pancreatitis.

Acute pancreatitis is an extraintestinal manifestation of inflammatory bowel disease. There have been few reports describing acute pancreatitis preceding a diagnosis of inflammatory bowel disease. We herein report a rare case of a 16-year-old boy with presymptomatic Crohn's disease that was newly diagnosed just after the onset of idiopathic acute pancreatitis. Crohn's disease of any stage, much less in the presymptomatic stage, is rarely diagnosed just after the development of acute pancreatitis. The present case suggests that acute pancreatitis without an apparent cause in young or pediatric population can precede a diagnosis of presymptomatic Crohn's disease.

A case of jejunal solitary Peutz-Jeghers polyp with intussusception identified by double-balloon enteroscopy.

Solitary Peutz-Jeghers polyp is a rare hamartomatous polyp that has similar histologic characteristics with those of polyps in Peutz-Jeghers syndrome, without associated mucocutaneous hyperpigmentation and a family history. Previous reports indicated that solitary Peutz-Jeghers polyp is rarely found in the small intestine. We experienced a rare case of jejunal solitary Peutz-Jeghers polyp. A 29-year-old man was admitted to our hospital with a 6-month history of upper abdominal pain. He had no hyperpigmentation or a family history of Peutz-Jeghers syndrome. Abdominal computed tomography showed a 3-cm tumor-like structure at the tip of a mildly intussuscepted jejunum. Per oral double-balloon enteroscopy revealed a 3-cm pedunculated polyp in the jejunum. The patient underwent partial jejunal resection under laparotomy. Macroscopically, the surgical specimen showed a pedunculated polyp, measuring 30 × 15 × 10 mm in size, with lobulated head. Histopathologic examination revealed irregular aggregation of hyperplastic crypts with branching muscular bundles originating from the muscularis mucosae. Based on these histologic findings, we finally diagnosed the patient as a solitary Peutz-Jeghers polyp in the jejunum. The present case indicated that solitary Peutz-Jeghers polyp should be considered in a patient with solitary hamartomatous polyp in the gastrointestinal tract.