Effects of selective bile duct ligation on liver parenchyma in young animals: histologic and molecular evaluations

Background/Purpose: The mechanisms of increased collagen production and liver parenchyma fibrosis are poorly understood. These phenomena are observed mainly in children with biliary obstruction (BO), and in a great number of patients, the evolution to biliary cirrhosis and hepatic failure leads to the need for liver transplantation before adolescence. However, pediatric liver transplantation presents with biliary complications in 20% to 30% of cases in the postoperative period. Intra-or extrahepatic stenosis of bile ducts is frequent and may lead to secondary biliary cirrhosis and the need for retransplantation. It is unknown whether biliary stenosis involving isolated segments or lobes may affect the adjacent nonobstructed lobes by paracrine or endocrine means, leading to fibrosis in this parenchyma. Therefore, the present study aimed to create an experimental model of selective biliary duct ligation in young animals with a subsequent evaluation of the histologic and molecular alterations in liver parenchyma of the obstructed and nonobstructed lobes. Methods: After a pilot study to standardize the surgical procedures, weaning rats underwent ligation of the bile ducts of the median, left lateral, and caudate liver lobes. The bile duct of the right lateral lobe was kept intact. To avoid intrahepatic biliary duct collaterals neoformation, the parenchymal connection between the right lateral and median lobes was clamped. The animals were divided into groups according to the time of death: 1, 2, 3, 4, and 8 weeks after surgical procedure. After death, the median and left lateral lobes (with BO) and the right lateral lobe (without BO [NBO]) were harvested separately. A group of 8 healthy nonoperated on animals served as controls. Liver tissues were subjected to histologic evaluation and quantification of the ductular proliferation and of the portal fibrosis. The expressions of smooth muscle alpha-actin (alpha-SMA), desmin, and transforming growth factor beta 1 genes were studied by molecular analyses (semiquantitative reverse transcriptase-polymerase chain reaction and real-time polymerase chain reaction, a quantitative method). Results: Histologic analyses revealed the occurrence of ductular proliferation and collagen formation in the portal spaces of both BO and NBO lobes. These phenomena were observed later in NBO than BO. Bile duct density significantly increased 1 week after duct ligation; it decreased after 2 and 3 weeks and then increased again after 4 and 8 weeks in both BO and NBO lobes. The portal space collagen area increased after 2 weeks in both BO and NBO lobes. After 3 weeks, collagen deposition in BO was even higher, and in NBO, the collagen area started decreasing after 2 weeks. Molecular analyses revealed increased expression of the alpha-SMA gene in both BO and NBO lobes. The semiquantitative and quantitative methods showed concordant results. Conclusions: The ligation of a duct responsible for biliary drainage of the liver lobe promoted alterations in the parenchyma and in the adjacent nonobstructed parenchyma by paracrine and/or endocrine means. This was supported by histologic findings and increased expression of alpha-SMA, a protein related to hepatic fibrogenesis. (C) 2012 Elsevier Inc. All rights reserved.

Review of experimental models for inducing hepatic cirrhosis by bile duct ligation and carbon tetrachloride injection

PURPOSE: To present a review about a comparative study of bile duct ligation versus carbon tetrachloride Injection for inducing experimental liver cirrhosis. METHODS: This research was made through Medline/PubMed and SciELO web sites looking for papers on the content "induction of liver cirrhosis in rats". We have found 107 articles but only 30 were selected from 2004 to 2011. RESULTS: The most common methods used for inducing liver cirrhosis in the rat were administration of carbon tetrachloride (CCl4) and bile duct ligation (BDL). CCl4 has induced cirrhosis from 36 hours to 18 weeks after injection and BDL from seven days to four weeks after surgery. CONCLUSION: For a safer inducing cirrhosis method BDL is better than CCl4 because of the absence of toxicity for researches and shorter time for achieving it.

Atorvastatin attenuates hepatic fibrosis in rats after bile duct ligation via decreased turnover of hepatic stellate cells

Activation of hepatic stellate cells (HSC) and transdifferentiation to myofibroblasts following liver injury is the main culprit for hepatic fibrosis. Myofibroblasts show increased proliferation, migration, contraction, and production of extracellular matrix (ECM). In vitro, HMG-CoA reductase inhibitors (statins) inhibit proliferation and induce apoptosis of myofibroblastic HSC. To investigate the antifibrotic effects of atorvastatin in vivo we used bile duct ligated rats (BDL).

AST-120 (spherical carbon adsorbent) lowers ammonia levels and attenuates brain edema in bile duct-ligated rats

The pathogenesis of hepatic encephalopathy is multifactorial, involving gut-derived toxins such as ammonia, which has been demonstrated to induce oxidative stress. Therefore, a primary hepatic encephalopathy treatment target is reducing ammonia production in the gastrointestinal tract. AST-120, an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600 m(2) /g, acts as a sink for neurotoxins and hepatotoxins present in the gut. We evaluated the capacity of AST-120 to adsorb ammonia in vitro and to lower blood ammonia, oxidative stress and brain edema in cirrhotic rats. Cirrhosis was induced in rats by bile duct ligation for 6 weeks. AST-120 was administered by gavage preventively for 6 weeks (0.1, 1, and 4 g/kg/day). In addition, AST-120 was evaluated as a short-term treatment for 2 weeks and 3 days (1 g/kg/day) and as a sink to adsorb intravenously infused ammonium acetate. In vitro, AST-120 efficiently adsorbed ammonia. Ammonia levels significantly decreased in a dose-dependent manner for all AST-120-treated bile duct-ligated rats (nontreated: 177.3 ± 30.8 μM; AST-120, 0.1 g/kg/day: 121.9 ± 13.8 μM; AST-120, 1 g/kg/day: 80.9 ± 30.0 μM; AST-120, 4 g/kg/day: 48.8 ± 19.6 μM) and significantly correlated with doses of AST-120 (r = -0.6603). Brain water content and locomotor activity normalized after AST-120 treatments, whereas arterial reactive oxygen species levels remained unchanged. Furthermore, AST-120 significantly attenuated a rise in arterial ammonia after ammonium acetate administration (intravenously). Conclusion:AST-120 treatment decreased arterial ammonia levels, normalized brain water content and locomotor activity but did not demonstrate an effect on systemic oxidative stress. Also, AST-120 acts as an ammonia sink, efficiently removing blood-derived ammonia. Additional studies are warranted to evaluate the effects of AST-120 on hepatic encephalopathy in patients with advanced liver disease. (HEPATOLOGY 2011;).

Proposal of a new technique for bile duct reconstruction after iatrogenic injury. Study in dogs and review of the literature

Purpose: Interposition of a jejunal tube between the common bile duct and duodenum. Methods: Five adult mongrel dogs of both sexes, weighing on average 22.3 kg (18 to 26.5 kg), were used. Obstructive jaundice was induced by ligation of the distal common bile duct. After one week, a 2.5-cm long jejunal tube was fabricated from a segment of the loop removed 15 cm from the Treitz angle and interposed between the common bile duct and duodenum. Results: The animals presented good clinical evolution and no complications were observed. After 6 weeks, complete integration was noted between the bile duct mucosa, tube and duodenum and a significant reduction in total bilirubin and alkaline phosphatase was observed when compared to the values obtained one week after ligation of the common bile duct. Conclusion: The jejunal tube interposed between the dilated bile duct and duodenum showed good anatomic integration and reduced total bilirubin and alkaline phosphatase levels in the animals studied.

Endothelial nitric oxide synthase is not essential for the development of fibrosis and portal hypertension in bile duct ligated mice

BACKGROUND/AIMS: It is postulated that nitric oxide (NO) is responsible for the hyperdynamic circulation of portal hypertension. Therefore, we investigated induction of fibrosis and hyperdynamic circulation in endothelial NO synthase knock-out (KO) mice. METHODS: Fibrosis was induced by bile duct ligation. Hemodynamic studies were performed after portal vein ligation. All studies were performed in wild-type (WT) and KO mice. RESULTS: Three to 4 weeks after bile duct ligation (BDL), both WT and KO groups had similar degrees of portal hypertension, 12 (9-14) and 11(8-15) mmHg, median (range), and liver function. Fibrosis increased from 0.0% in sham operated to 1.0 and 1.1% in WT and KO mice, respectively. Cardiac output was similar after portal vein ligation (20 and 17 ml/min in WT and KO mice, respectively). There was no difference in liver of mRNA for endothelin 1, inducible NO synthase (iNOS) and hem-oxygenase 1 (HO1); proteins of iNOS, HO1 and HO2; nor in endothelin A and B (EtA and EtB) receptor density between WT and KO mice after BDL. CONCLUSIONS: These results suggest that endothelial NO synthase is neither essential for the development of fibrosis and portal hypertension in bile duct ligated mice, nor for the hyperdynamic circulation associated with portal hypertension in the portal vein ligated mice.

Feasibility of biodegradable PLGA common bile duct stents: An in vitro and in vivo study

The current study investigates the feasibility of using a biodegradable polymeric stent in common bile duct (CBD) repair and reconstruction. Here, poly(l-lactide-co-glycolide) (PLGA, molar ratio LA/GA = 80/20) was processed into a circular tube- and dumbbell-shaped specimens to determine the in vitro degradation behavior in bile. The morphology, weight loss, and molecular weight changes were then investigated in conjunction with evaluations of the mechanical properties of the specimen. Circular tube-shaped PLGA stents with X-ray opacity were subsequently used in common bile duct exploration (CBDE) and primary suturing in canine models. Next, X-ray images of CBD stents in vivo were compared and levels of serum liver enzymes and a histological analysis were conducted after stent transplantation. The results showed that the PLGA stents exhibited the required biomedical properties and spontaneously disappeared from CBDs in 4-5 weeks. The degradation period and function match the requirements in repair and reconstruction of CBDs to support the duct, guide bile drainage, and reduce T-tube-related complications.

Diagnosis of common bile duct stones by intravenous cholangiography:prediction by ultrasound and liver function tests compared with endoscopic retrograde cholangiography

Routine intravenous cholangiography using the safer contrast medium, meglumine iotroxate, may be a useful investigation prior to laparoscopic cholecystectomy for the detection of suspected common bile duct stones. We compared this with endoscopic cholangiography.

Common bile duct obstruction associated with platinosoma concinum in cat

Extrahepatic obstruction in cat,can be caused by cholelithiasis, inspissated bile, pancreatic inflammation or fibrosis, duodenal inflammation, bile duct carcinoma or liver fluke infection (Amphimerus pseudofelineus e Platynosomurn concinum). A three-year-old, female neutered siames cat was present with a two-month history of progressive letargy, anorexia and emaciation. She had severe icterus of the mucous membranes, skin, and sclerae. A diagnosis of extrahepataic biliary obstruction was made based on the increased levels of conjugated bilirubin in the serum and the ultrasonography. Hepatic fluke eggs were not diagnosed in the feces because the fibrotic bile ducts were occluded and no eggs were shed into the intestine. Cholecystoduodenostomy was done to relieve posthepatic-biliary obstruction.

Common bile duct stones: analysis of the videolaparoscopic surgical treatment

CONTEXT: About 9% of the Brazilian population has gallstones and the incidence increases significantly with aging. The choledocholithiasis is found around 15% of these patients, and a third to half of these cases presented as asymptomatic. Once the lithiasis in the common bile duct is characterized through intraoperative cholangiography, the laparoscopic surgical exploration can be done through the transcystic way or directly through choledochotomy. OBJECTIVE: To evaluate the results and outcomes of the laparoscopic treatment of common bile duct lithiasis. METHODS: Seventy consecutive patients were evaluated. They prospectively underwent the treatment of the lithiasis in the common bile duct and the exploration ways were compared according to the following parameters: criteria on their indication, success in the clearance, surgical complications. It was verified that about ½ of the choledocholithiasis carriers did not show any expression of predictive factors (clinical antecedents of jaundice and/or acute pancreatitis, compatible sonographic data and the pertaining lab tests). The laparoscopic exploration through the transcystic way is favored when there are no criteria for the practice of primary choledochotomy, which are: lithiasis in the proximal bile duct, large (over 8 mm) or numerous calculi (multiple calculosis). RESULTS: The transcystic way was employed in about 50% of the casuistic and the choledochotomy in about 30%. A high success rate (around 80%) was achieved in the clearance of the common bile duct stones through laparoscopic exploration. The transcystic way, performed without fluoroscopy or choledochoscopy, attained a low rate of success (around 45%), being 10% of those by transpapilar pushing of calculi less than 3 mm. The exploration through choledochotomy, either primary or secondary, if the latter was performed after the transcystic route failure, showed high success rate (around 95%). When the indication to choledochotomy was primary, the necessity for choledochoscopy through choledochotomy to help in the removal of the calculi was 55%. However, when choledochotomy was performed secondarily, in situations where the common bile duct diameter was larger than 6 mm, the use of choledochoscopy with the same purpose involved about 20% of the cases. There was no mortality in this series. CONCLUSION: The laparoscopic exploration of the common bile duct was related to a low rate of morbidity. Therefore, the use of laparoscopy for the treatment of the lithiasis in the common bile duct depends on the criteria for the choice of the best access, making it a safe procedure with very good results.