A method is described by which bile canalicular membranes (BCM) can be prepared, together with canaliculus-free plasma membrane (PM), both essentially free of contamination. The recovery of both fractions together was estimated to be 46%. The concentrations of total lipid, total phospholipid and cholesterol were substantially greater in the BCM, and polyacrylamide gel electrophoresis revealed differences in protein composition. The differences in lipid and protein composition of these two plasma membrane fractions are presumably related to their very different physiological functions.
The purpose of the present investigation was to describe ultrastructural characteristics of hepatic bile ducts and the gall bladder in larvae of the sea lamprey, Petromyzon marinus, using freeze--fracture replicas as well as ultrathin sections. Comparison of these structures with those of other vertebrates was necessary to provide a basis in future studies for characterization of biliary degeneration during metamorphosis. The bile ducts were composed of a simple cuboidal to columnar epithelium with the cells separated by wide lateral intercellular spaces and containing a prominent brush border. Vacuole-like intracytoplasmic cisternae formed a peripheral network within the cells and were confluent with intercellular spaces at the site of numerous pores in the lateral plasma membranes. The cells were joined apically by well developed zonulae occludentes surmounting zonulae adhaerentes. The zonulae occludentes, as observed in freeze--fracture replicas, appeared as a honeycomb-like meshwork. Frequent gaps in P-face ridges suggested a 'leaky' epithelium. The cytoplasm of bile duct cells contained few organelles except for large numbers of mitochondria; many microfilaments were present. The ultrastructural features of those cells reflected an epithelium specialized for absorption and transport and they were similar to cells of the bile ducts in other vertebrates. The general organization of epithelium in the gall bladder resembled that of bile ducts, but intercellular spaces were narrower, peripheral pores and cisternae were absent laterally, and the brush border was less extensively developed at the apical surface. The cytoplasm also contained large pools of glycogen and numerous microfilaments were situated in the apical ectoplasm. The overall appearance of the gall bladder of lampreys suggested that the epithelium was less specialized compared to the water transporting organs of other vertebrate species.
The Sunnybrook Medical Centre Gallstone Study is a randomized, controlled, double-blind study of chenodeoxycholic acid for dissolution of radiolucent gallstones. Of the first 22 patients whose stones were apparently totally dissolved on oral cholecystography, seven were found to have residual small stone fragments on ultrasound examination of the gallbladder. Continuing chenotherapy was unsuccessful in dissolving these fragments. The possibility that the residual stones represent insoluble nuclei of the original calculi must be considered. Responses to choleitholytic therapy and subsequent stone recurrences need to be reevaluated using ultrasound.
The pathogenesis of cholesterol cholelithiasis in humans has been studied by means of three techniques. The cholesterol-solubilizing capacity of bile may be determined by estimation of the relative composition of the three major lipid constituents of bile. Consistent reduction in the cholesterol-carrying capacity of gallbladder bile of persons with gallstones when compared with normal subjects has not been shown. Normal subjects frequently have supersaturated bile. Secretion rates of biliary lipids have been estimated by two methods; with the method that appears to be more physiologic no change in lipid secretion rates was found in gallstone patients. Bile acid pool size has been measured by isotope dilution techniques; it is reduced in patients with gallstones. It is not clear whether this reduction is important in the pathogenesis of cholesterol cholelithiasis, for the bile acid secretion rate is normal because of an increased rate of cycling of the pool through the enterohepatic circulation. The role of the gallbladder in the genesis of cholesterol cholelithiasis may be more important than has been realized.
The authors discuss a rarely diagnosed, common clinical entity, not discussed in the English medical literature. Anusitis causes anal pain and bleeding more often than hemorrhoids. Many patients with anusitis are wrongly diagnosed as having hemorrhoids, and some even have a hemorrhoidectomy with poor results. Anusitis is defined and described. A new treatment method is presented. It is important to consider anusitis as a distinct entity and to differentiate it from hemorrhoids, proctitis, and pruritus ani.
