A 65-year-old man is brought to the emergency room in a disoriented state. The patient has an odor of alcohol on his breath. Physical examination reveals palmar erythema, diffuse spider angiomata on the upper trunk and face, and gynecomastia. A liver biopsy shows micronodular cirrhosis, massive steatosis, and Mallory hyaline. Serum levels of ammonia are elevated. Which of the following is the most likely underlying cause of gynecomastia in this patient?