BACKGROUND: We previously demonstrated that continuous exposure to nitrous acid gas (HONO) for 4 weeks, at a concentration of 3.6 parts per million (ppm), induced pulmonary emphysema-like alterations in guinea pigs. In addition, we found that HONO affected asthma symptoms, based on the measurement of respiratory function in rats exposed to 5.8 ppm HONO. This study aimed to investigate the dose-response effects of HONO exposure on the histopathological alterations in the respiratory tract of guinea pigs to determine the lowest observed adverse effect level (LOAEL) of HONO. METHODS: We continuously exposed male Hartley guinea pigs (n = 5) to four different concentrations of HONO (0.0, 0.1, 0.4, and 1.7 ppm) for 4 weeks (24 h/day). We performed histopathological analysis by observing lung tissue samples. We examined samples from three guinea pigs in each group under a light microscope and measured the alveolar mean linear intercept (Lm) and the thickness of the bronchial smooth muscle layer. We further examined samples from two guinea pigs in each group under a scanning electron microscope (SEM) and a transmission electron microscope (TEM). RESULTS: We observed the following dose-dependent changes: pulmonary emphysema-like alterations in the centriacinar regions of alveolar ducts, significant increase in Lm in the 1.7 ppm HONO-exposure group, tendency for hyperplasia and pseudostratification of bronchial epithelial cells, and extension of the bronchial epithelial cells and smooth muscle cells in the alveolar duct regions. CONCLUSIONS These histopathological findings suggest that the LOAEL of HONO is < 0.1 ppm.
Alveolar Epithelial Cells ; drug effects ; Animals ; Bronchi ; drug effects ; Dose-Response Relationship, Drug ; Emphysema ; chemically induced ; Epithelial Cells ; drug effects ; Guinea Pigs ; Hyperplasia ; chemically induced ; Inhalation Exposure ; adverse effects ; Lung ; drug effects ; pathology ; ultrastructure ; Male ; Microscopy, Electron, Scanning ; Microscopy, Electron, Transmission ; Myocytes, Smooth Muscle ; drug effects ; Nitrous Acid ; toxicity

Objective: To describe the case of a patient with intraperitoneal bleeding from the gastroepiploic artery by endoscopic ultrasound who was successfully treated with transcatheter arterial coil embolization.Patient and Methods: An 87-year-old man was referred to our hospital for examination of a gallbladder tumor. Endoscopic ultrasonography was performed using an oblique-view echoendoscope. After the endoscopic ultrasound, the patient went into shock. Computed tomography revealed a huge intraperitoneal hematoma and an aneurysm in the right gastroepiploic artery that were not seen on previous computed tomography images. Thus, urgent catheter angiography was performed, which showed a pseudoaneurysm of the right gastroepiploic artery and extravasation of the contrast medium from the pseudoaneurysm.Results: Transcatheter arterial coil embolization was subsequently performed, and the bleeding stopped. Thereafter, his hemodynamics stabilized and his general condition improved. The patient was discharged 22 days post-treatment with an uneventful course.Conclusion: Observation-only endoscopic ultrasound without invasive procedures can cause intraperitoneal bleeding due to a ruptured splanchnic artery. Thus, endoscopic ultrasonography should be performed more carefully in elderly patients.

Objective: Retrieval is challenging once prophylactic pancreatic stents migrate deep into the pancreatic duct. Herein, we describe a case of successful endoscopic retrieval of a migrated prophylactic pancreatic stent using a basket catheter through a biliary plastic stent pusher tube.Patient: A 71 year-old man was referred to our hospital for removal of a straight-shaped migrated 5-Fr 3-cm prophylactic pancreatic stent with a flap on the duodenal side. There were no subjective symptoms at the time of the hospital visit.Results: During endoscopic retrograde cholangiopancreatography, we inserted an 8.5-Fr plastic biliary stent pusher tube in front of the migrated pancreatic stent. The stent was then grasped using a basket catheter for peroral cholangioscopy through the biliary stent pusher tube. The stent was pulled into the pusher tube and was successfully retrieved from the pancreatic duct. No complications were associated with endoscopic retrograde cholangiopancreatography.Conclusion: Although rare, prophylactic pancreatic duct stent migration after pancreatic duct guidewire placement should be noted. In our case, endoscopic retrieval of a migrated prophylactic pancreatic stent using a basket catheter for peroral cholangioscopy through the biliary plastic stent pusher tube was successful.