Various social behaviours in mice are regulated by chemical signals called pheromones that act through the vomeronasal system. Exocrine gland-secreting peptide 1 (ESP1) is a 7-kDa peptide that is released into male tear fluids and stimulates vomeronasal sensory neurons in female mice. Here, we describe the molecular and neural mechanisms that are involved in the decoding of ESP1 signals in the vomeronasal system, which leads to behavioural output in female mice. ESP1 is recognized by a specific vomeronasal receptor, V2Rp5, and the ligand-receptor interaction results in sex-specific signal transmission to the amygdaloid and hypothalamic nuclei via the accessory olfactory bulb. Consequently, ESP1 enhances female sexual receptive behaviour upon male mounting (lordosis), allowing successful copulation. In V2Rp5-deficient mice, ESP1 induces neither neural activation nor sexual behaviour. These findings show that ESP1 is a crucial male pheromone that regulates female reproductive behaviour through a specific receptor in the mouse vomeronasal system.

Hepatitis C virus (HCV) infection remains the main cause of liver disease and can lead to chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV may also develop extrahepatic manifestations in the skin, eyes, joints, kidneys, nervous system, and immune system. In fact, several studies reported that up to 70% of HCV patients experienced extrahepatic manifestations. Lichen planus (LP), which is an immune system disorder that is triggered by viral infections, allergens, and stress, can affect the skin, mouth, nails, and scalp. The association of LP with HCV has been reported, but the effect of HCV treatment on LP remission is controversial. We encountered a 53-year-old man with HCV genotype 2a and LP that were successfully treated with sofosbuvir and ribavirin for 12 weeks. After treatment, he achieved sustained virological response against HCV and remission of erosive LP lesions on the lip. In the era of interferon (IFN)-based treatment for HCV, exacerbation of autoimmune diseases is a common adverse event. Therefore, use of an IFN-free regimen of direct-acting antivirals for HCV might prevent the extrahepatic manifestation of an immune disorder.

To date, no cases of vonoprazan-associated gastric mucosal redness have been reported, and its endoscopic and pathological features remain largely unclear. We report four cases of vonoprazan-associated gastric mucosal redness. In all cases, esophagogastroduodenoscopy (EGD) demonstrated linear or spotty redness that newly appeared in the greater curvature of the middle gastric body after the initiation of vonoprazan, which disappeared after its discontinuation. A tissue biopsy taken from the gastric mucosa with redness revealed inflammatory cell infiltration, parietal cell protrusions (PCPs), and oxyntic gland dilatation. To our knowledge, this is the first report describing the endoscopic and pathological features of vonoprazan-associated gastric mucosal redness.

Acute liver failure (ALF) associated with malignant infiltration of the liver is rare and its pathological and radiologic features remain poorly described. An 87-year-old man was admitted to our hospital for anorexia for several days, high-grade fever from the previous day, and liver dysfunction but suddenly died on day 3 of hospitalization due to ventricular fibrillation. The patient was diagnosed at autopsy with malignant diffuse large B-cell lymphoma. To the best of our knowledge, this report represents a valuable addition to the ALF literature describing a case of ALF associated with diffuse large B-cell lymphoma diagnosed at autopsy.

Eosinophilic gastroenteritis (EGE)-associated duodenal ulcer is rare and its endoscopic and pathological features remain poorly described. A 15-year-old boy was referred to our hospital for further examination and treatment of duodenal ulcer. Esophagogastroduodenoscopy (EGD) revealed two A2-stage duodenal ulcers on the duodenal bulb. A biopsy revealed marked infiltration of eosinophils, suggestive of EGE-associated duodenal ulcers. Thus, treatment with crushed budesonide (9 mg/day) was started. EGD revealed healing of the duodenal ulcers seven months after treatment. To our knowledge, this is the first report describing EGE-associated duodenal ulcer successfully treated with crushed budesonide.

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Enterolithiasis associated with blind pouch syndrome secondary to functional end-to-end anastomosis is rare, and its endoscopic and radiological features remain poorly described. A 72-year-old woman was admitted to our hospital for abdominal pain and difficulty defecating. Colonoscopy (CS) with Gastrografin revealed a 10 × 8 cm calculus, an anastomotic ulcer, a blind pouch, and an end-to-end anastomosis in the transverse colon. The calculus was successfully crushed and removed with snares and alligator forceps through CS during the ensuing 4-day period. To our knowledge, this is the first report describing the endoscopic and radiological features of blind pouch syndrome-associated enterolithiasis successfully treated with CS.