複選題59. Consider the symptoms associated with bile duct obstruction due to gallstones: patients often present with upper abdominal pain, fever, and potential inflammation. Some individuals may experience gencralized abdominal discomfort without clear localization. Based on physiological characteristics and possible biochemical mechanisms, which statements accurately explain these observations? (A) Bile acids form covalent bonds with glycine through an amide linkage, raising their pKa value and augmenting their emulsifying properties. (B) Cholesterol can undergo metabolism to produce 7α-hydroxycholesterol catalyzed by cholesterol 7α-hydroxylase, a process that is expedited by elevated levels of bile acids. (C) Cholcstyranine is not a resorption resin binding to bile acid to enhance elimination. However, cholestyramine may bind to vit. A, D, E, K and inhibit their absorption. (D) Bile salts are metabolized by bacteria in the small intestine to form secondary bile acids. Oral administration of ursodeoxycholic acid, a secondary bile acid, can aid in dissolving cholesterol in bile, thereby dissolving gallstones ranging from small to medium in size.