Biliary tree

Alkaline phosphatase levels and GGT are elevated in plasma with obstructive disorders that disrupt the flow of bile from hepatocytes to the bile ducts or from the biliary tree to the intestines in condition such as primary biliary cirrhosis, sclerosing cholangitis, drug-induced cholestasis, gallstone disease, and autoimmune cholestatic liver disease. 

Curtis LR. 1984. Impaired biliary excretion of tauorcholate associated with increased biliary tree permeability in mirex or chlordecone treated rats. Proc West Pharmacol Soc 27 475. 

Davidson MD, Fujimoto JM. 1987. Increased permeability of the rat biliary tree by 2,3,7,8-tetrachlorodibenzo-p-dioxin TCDD treatment and protection by hepatoactive agents. Toxicol Appl Pharmacol 87(1) 57-66. 

Figure 2.2 Secretion of bile acids and biliary components. Bile acids (BA) cross the hepatocyte bound to 3a-hydroxysteroid dehydrogenase and are exported into the canaliculus by the bile-salt export protein (BSEP). Phosphatidylcholine (PC) from the inner leaflet of the apical membrane is flipped to the outer layer and interacts with bile acids secreted by BSEP. BA, PC, together with cholesterol from the membrane form mixed micelles that are not toxic to epithelial membranes of the biliary tree. Aquaporins (AQP) secrete water into bile.

Opiates can effect serum levels of enzymes and other substances whose homeostatic control depends on clearance through the liver (F8, G12, M15, N4, S19). In one reported case, the aspartate aminotransferase was within normal limits before the administration of codeine, but within 2 hours after the drug, the enzyme activity had risen to two times the normal value by 8 hours to eight times the normal activity, and within 24 hours it had returned to normal (F8). Increases in transaminase to levels 5-85 times the control value have been reported in 6 of 16 patients with disease of the biliary tree following the administration of codeine phosphate (2 grains) (B7, F8). Gross has shown that morphine, codeine, or mepheridine administration produce elevations of serum amylase or lipase (G12). These elevations have been attributed to constriction of the sphincter of Oddi and increased intraductal pressure on the pancreatic duct (G12, N4). 

Dragovich T, Ramanathan, Remick S, et al. Phase II trial of a weekly 150-minute gemcitabine infusion in patients with biliary tree carcinomas. ProcAm Soc Clin Oncol 2000 19 296a. 

The rate of resectability is only 15-20% for proximal bile duct carcinomas but up to 70% for distal lesions. In addition, there is little benefit to preoperative decompression of the biliary tree in patients having obstructive jaundice (65,66). However, this procedure is frequently practiced. For proximal cancers, local excision is often possible. In particular, hepatic resection is indicated for upper bile duct cancers with quadrate lobe invasion or unilateral intrahepatic ductal or vascular involvement, and distal and midductal lesions may require pancreatoduodenectomy. Also, biliary-enteric continuity... 

Outside the liver the common hepatic duct is joined by the cystic duct of the gallbladder and becomes the common bile duct (CBD). The extrahepatic and intrahepatic ducts are supplied with blood by a fine network of tiny arterial branches that originate from the hepatic and gastroduodenal arteries. As it has no other blood supply, the biliary tree is particularly susceptible to ischaemic injury, such as hepatic artery thrombosis or injury to the biliary plexus during laparoscopic surgery. This can result in extrahepatic and complex hilar and perihilar ischaemic strictures of the biliary tree. 

Contrast medium is injected into the bile ducts via an endoscopic tube. X-rays are then used to visualise the pancreas and biliary tree. Gallstones can be removed during ERCP and stents can be inserted to widen narrowed bile ducts, which may be the cause of jaundice. 

PTC is a technique where contrast medium is injected into the common bile duct via a needle inserted through the skin in the right upper quadrant. X-ray images are used to identify strictures or obstructions in the biliary tree. 

A HIDA scan assesses the patency and function of the biliary tree. A radiolabelled isotope, technetium-99m ( Tc), is injected intravenously... 

Steiner, J.W., Carruthers, J.S. Studies on the fine structure of the terminal branches of the biliary tree. I. The morphology of normal bile canaliculi, bile pre-ductules (Ducts of Hering) and bile ductules. Amer. J. Path. 1961 38 640-649... 

Practical classification of the branching types of the biliary tree an analysis of 1,094 consecutive direct cholangiograms. X Amer. Coll. Surg. 

Edelman, K. Multiple pyogenic hver abscesses communicating with the biliary tree treatment by endoscopic stenting and stone removal. Amer. J. Gastroenterol. 1994 89 2070-2072... 

The response of the liver to any form of biliary tree obstruction induces the synthesis of ALP by hepatocytes. Some of the newly formed enzyme enters the circulation to increase the enzyme activity in serum. The elevation tends to be more notable (greater than threefold) in extrahepatic obstruction (e.g., by stone or by cancer of the head of the pancreas) than in intrahepatic obstruction and is greater the more complete the obstruction. Serum enzyme activities may reach 10 to 12 times the upper reference limit and usually return to normal on surgical removal of the obstruction. A similar increase is seen in patients with advanced primary liver cancer or widespread secondary hepatic metas-tases. Liver diseases that principally affect parenchymal cells, such as infectious hepatitis, typically show only moderately (less than threefold) increased or even normal serum ALP activities (Table 21-3). Increases may also be seen as a consequence of a reaction to drug therapy. Intestinal ALP... 

There are four major bile acids (see Figures 47-5 to 47-7). Cholic acid and chenodeoxycholic acid, the primary bile acids, are synthesized in the liver. Bacteria metabolize these primary bile acids to the secondary bile acids—deoxy-cholic acid and lithocholic acid, respectively. Bile acids are conjugated in the liver with the amino acids glycine or taurine. This decreases passive absorption in the biliary tree and proximal small intestine, but permits conservation through active transport in the terminal ileum. This combi-... 

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