A 48-year-old man has noticed increasing abdominal girth and a yellowish color to his skin over the past 5 months. On physical examination, he has scleral icterus and generalized jaundice. His abdomen is distended, and a fluid wave is present. Laboratory studies include total serum bilirubin of 5.2 mg/dL, direct bilirubin of 4.2 mg/dL, AST of 380 U/L, ALT of 158 U/L, alkaline phosphatase of 95 U/L, total protein of 6.4 g/dL, and albumin of 2.2 /dL. The prothrombin time is 18 seconds, and the partial thromboplastin time is 30 seconds. The blood ammonia level is 105 mmol/L. What is the most likely cause of these findings?