Bile Duct Cancer
Dongyou Liu in Tumors and Cancers, 2017
The bile ducts are thin tubes of 10-12.5 cm in length that connect the liver, gallbladder, and small intestine. The bile ducts are divided into two sections: intrahepatic and extrahepatic. The intrahepatic bile ducts are small ducts located within the liver. The extrahepatic bile ducts include part of the right and left hepatic ducts outside the liver. The main function of the bile ducts is to collect bile produced in the liver and to carry the bile via the cystic duct to the gallbladder for storage and via the distal extrahepatic bile duct and through the pancreas to the small intestine. Tumors of the intrahepatic bile ducts arise from the biliary epithelium of small intrahepatic ductules or large intrahepatic ducts near the bifurcation of the right and left hepatic ducts. Tumors of the extrahepatic bile ducts occur in the common bile duct located between the point where the cystic duct joins the common hepatic duct and the ampulla of Vater.
Biliary Tract Cancer
Pat Price, Karol Sikora in Treatment of Cancer, 2020
Tumors of the biliary tract can be divided into those of the intra-hepatic bile ducts, peri-hilar bile ducts and distal bile duct, and gall bladder. A modified version of preoperative T staging for tumors of the biliary confluence has been proposed which takes into account the degree of tumor extension to second-order biliary radicles and ipsilateral or contralateral portal venous involvement as well as hepatic atrophy. Biliary intra-epithelial neoplasia, intraductal papillary neoplasia of the bile duct, and the rarer intraductal tubulopapillary neoplasms of the bile duct are considered precursor lesions in the multistep progression to invasive cholangiocarcinoma. A high index of suspicion and a multidisciplinary investigative approach are required, especially in patients with primary sclerosing cholangitis who already have dominant biliary strictures and deranged liver function with secondary biliary cirrhosis. The type and extent of surgery depend on the location of the cancer within the liver or the biliary tract.
The Nature and Cause of Cancer: Historical Overview
Jeremy R. Jass in Understanding Pathology, 2020
The word cancer originates from the writings of Hippocrates, who observed distended vessels radiating from a central lump in the breast like the legs of a crab. Galen believed that cancer was the result of an excess of black bile, the same humour responsible for the state of melancholy (this word literally means black bile). The nature of blood, yellow bile and phlegm is now widely understood, but black bile is a much more mysterious substance. In the sixteenth and seventeenth centuries, chemical ideas were being applied to the practice of medicine. The demise of the humoral and chemical theories came in the eighteenth and nineteenth centuries when the structure of the body was conceived as a set of different tissues. Theories on the cause of cancer have ranged from external agents in the form of infectious organisms, environmental chemicals and physical factors (notably radiation), to constitutional factors such as genetic mutations.
Diversification of host bile acids by members of the gut microbiota
Published in Gut Microbes, 2020
Jenessa A. Winston, Casey M. Theriot
Bile acid biotransformation is a collaborative effort by the host and the gut microbiome. Host hepatocytes synthesize primary bile acids from cholesterol. Once these host-derived primary bile acids enter the gastrointestinal tract, the gut microbiota chemically modify them into secondary bile acids. Interest into the gut-bile acid-host axis is expanding in diverse fields including gastroenterology, endocrinology, oncology, and infectious disease. This review aims to 1) describe the physiologic aspects of collaborative bile acid metabolism by the host and gut microbiota; 2) to evaluate how gut microbes influence bile acid pools, and in turn how bile acid pools modulate the gut microbial community structure; 3) to compare species differences in bile acid pools; and lastly, 4) discuss the effects of ursodeoxycholic acid (UDCA) administration, a common therapeutic bile acid, on the gut microbiota-bile acid-host axis.
Is bile acid a determinant of the gut microbiota on a high-fat diet?
Published in Gut Microbes, 2012
Atsushi Yokota, Satoru Fukiya, K.B.M. Saiful Islam, Tadasuke Ooka, Yoshitoshi Ogura, Tetsuya Hayashi, Masahito Hagio, Satoshi Ishizuka
Recently, we discovered that bile acid, a main component of bile, is a host factor that regulates the composition of the cecal microbiota in rats. Because bile secretion increases on a high-fat diet and bile acids generally have strong antimicrobial activity, we speculated that bile acids would be a determinant of the gut microbiota in response to a high-fat diet. The observed changes in the rat cecal microbiota triggered by cholic acid (the most abundant bile acid in human biliary bile) administration resemble those found in animals fed high-fat diets. Here, we discuss the rationale for this hypothesis by evaluating reported diet-induced gut microbiota alterations based on the postulate that bile acids worked as an underlying determinant. The identification of host factors determining the gut microbiota greatly contributes to understanding the causal relationships between changes in the gut microbiota and disease development, which remain to be elucidated.
Further evidence for a continuous flux of bile acids into the brain: trapping of bile acids in subdural hematomas
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2020
Emanuele Porru, Erik Edström, Ahmed A. Saeed, Gösta Eggertsen, Anita Lövgren-Sandblom, Aldo Roda, Ingemar Björkhem
Bile acids are known to pass the blood–brain barrier and are present at low concentrations in the brain. In a previous work, it was shown that subdural hematomas are enriched with bile acids and that the levels in such hematomas are higher than in the peripheral circulation. The mechanism behind this enrichment was never elucidated. Bile acids have a high affinity to albumin, and subdural hematomas contain almost as high albumin levels as the peripheral circulation. A subdural hematoma is encapsulated by fibrin which may allow passage of small molecules like bile acids. We hypothesized that bile acids originating from the circulation may be ‘trapped’ in the albumin in subdural hematomas. In the present work, we measured the conjugated and unconjugated primary bile acids cholic acid and chenodeoxycholic acid in subdural hematomas and in peripheral circulation of 24 patients. In most patients, the levels of both conjugated and free bile acids were higher in the hematomas than in the circulation, but the enrichment of unconjugated bile acids was markedly higher than that of conjugated bile acids. In patients with a known time interval between the primary bleeding and the operation, there was a correlation between this time period and the accumulation of bile acids. This relation was most obvious for unconjugated bile acids. The results are consistent with a continuous flux of bile acids, in particular unconjugated bile acids, across the blood–brain barrier. We discuss the possible physiological importance of bile acid accumulation in subdural hematomas.