Effects of sphincter of Oddi motility on the formation of cholesterol gallstones

AIM: To investigate the mechanisms and effects of sphincter of Oddi (SO) motility on cholesterol gallbladder stone formation in guinea pigs.

METHODS: Thirty-four adult male Hartley guinea pigs were divided randomly into two groups, the control group (n = 10) and the cholesterol gallstone group (n = 24), which was sequentially divided into four subgroups with six guinea pigs each according to time of sacrifice. The guinea pigs in the cholesterol gallstone group were fed a cholesterol lithogenic diet and sacrificed after 3, 6, 9, and 12 wk. SO manometry and recording of myoelectric activity were obtained by a multifunctional physiograph at each stage. Cholecystokinin-A receptor (CCKAR) expression levels in SO smooth muscle were detected by quantitative real-time PCR (qRT-PCR) and serum vasoactive intestinal peptide (VIP), gastrin, and cholecystokinin octapeptide (CCK-8) were detected by enzyme-linked immunosorbent assay at each stage in the process of cholesterol gallstone formation.

RESULTS: The gallstone formation rate was 0%, 0%, 16.7%, and 83.3% in the 3, 6, 9, and 12 wk groups, respectively. The frequency of myoelectric activity in the 9 wk group, the amplitude of myoelectric activity in the 9 and 12 wk groups, and the amplitude and the frequency of SO in the 9 wk group were all significantly decreased compared to the control group. The SO basal pressure and common bile duct pressure increased markedly in the 12 wk group, and the CCKAR expression levels increased in the 6 and 12 wk groups compared to the control group. Serum VIP was elevated significantly in the 9 and 12 wk groups and gastrin decreased significantly in the 3 and 9 wk groups. There was no difference in serum CCK-8 between the groups.

CONCLUSION: A cholesterol gallstone-causing diet can induce SO dysfunction. The increasing tension of the SO along with its decreasing activity may play an important role in cholesterol gallstone formation. Expression changes of CCKAR in SO smooth muscle and serum VIP and CCK-8 may be important causes of SO dysfunction.

Vascular endothelial growth factor levels in bile distinguishes pancreatic cancer from other etiologies of biliary stricture: a pilot study

BACKGROUND

Determining the benign or malignant nature of biliary strictures can be challenging. Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis.

OBJECTIVE

The purpose of this study was to investigate whether VEGF levels in bile aspirated during endoscopic retrograde cholangiography (ERCP) can distinguish pancreatic cancer from other causes of biliary stricture.

METHODS

Bile was directly aspirated in 53 consecutive patients from March 2012 to October 2012 during ERCP from the common bile duct including 15 with pancreatic cancer, 18 with primary sclerosing cholangitis (PSC), nine with cholangiocarcinoma (CCA), and 11 with benign biliary conditions (sphincter of Oddi and choledocholihiasis). Levels of VEGF in bile were measured. The diagnostic performance was then validated in a second, independent validation cohort of 18 patients (pancreatic cancer n = 10, benign n = 8).

RESULTS

A total of 53 consecutive patients were recruited. The median bile VEGF levels were significantly elevated in patients with pancreatic cancer (1.9 ng/ml (interquartile range [IQR] 0.7, 2.2) compared to those with benign biliary conditions (0.3 ng/ml [IQR 0.2, 0.6]; p < 0.001), PSC (0.7 ng/ml [IQR 0.5, 0.9]; p = 0.02) or CCA (0.4 ng/ml [IQR 0.1, 0.5]; p < 0.001). A VEGF cut-off value of 0.5 ng/ml distinguished pancreatic cancer from CCA with a sensitivity and specificity of 93.3 and 88.9 %, respectively, and area under curve (AUC) of 0.93, and from benign conditions with a sensitivity and specificity of 93.3 and 72.7 %, respectively, with AUC of 0.89. The diagnostic accuracy of biliary VEGF was confirmed in the second independent validation cohort.

CONCLUSIONS

This study suggests that measurement of biliary VEGF-1 levels distinguishes patients with pancreatic cancer from other etiologies of biliary stricture. This may be particularly relevant in approaching patients with indeterminate biliary stricture.

Bile-reflux into the pancreatic ducts is associated with the development of intraductal papillary carcinoma in hamsters

BACKGROUND

Reflux of pancreatic juice into the biliary tract is a well-known risk factor for the development of biliary carcinoma. In this study, we investigated the significance of bile-reflux into the pancreatic ducts in pancreatic carcinogenesis, especially in the development of carcinoma in the main pancreatic duct in hamsters.

MATERIALS AND METHODS

Syrian hamsters were subjected to three different surgical procedures: cholecystoduodenostomy with dissection of the extrahepatic bile duct on the distal end of the common duct (Model A); cholecystoduodenostomy along with a dissection of the common bile duct (Model B); or simple laparotomy (Model C). The animals then received weekly subcutaneous injections of N-nitrosobis(2-oxopropyl)amine (BOP), for 9 weeks, and were killed for pathological investigation at 16 weeks after the initial BOP administration.

RESULTS

Pancreas carcinomas developed in 95, 88, and 90% of the Model A hamsters (n = 22), B (n = 24), and C (n = 21), respectively. The induced pancreatic tumors were histologically classified into four types: papillary; tubular; cystic adenocarcinoma; or intraductal carcinoma of the main pancreatic duct consisting of intraductal papillary carcinoma (IPC) and intraductal tubular carcinoma (ITC). The number and the incidence of IPCs induced in Model A hamsters were 24 lesions and 77% and were statistically higher than those in Model B (7 lesions and 29%) and C hamsters (7 lesions and 33%) (P < 0.01). Bile-reflux into the pancreatic ducts was clearly demonstrated in only hamsters of Model A by means of Indocyanine green injection via the portal vein. Proliferative cell nuclear antigen labeling indices of the epithelial cells in the main pancreatic duct in hamsters, with no BOP treatment, were 3.8, 0.8, and 1.1% in Models A (n = 10), B (n = 10), and C (n = 10), respectively, and the difference was statistically significant (P < 0.01).

CONCLUSIONS

Our findings suggest that bile-reflux into the pancreatic ducts is a significant factor predisposing to the development of IPC of the pancreas through an acceleration of epithelial cell kinetics of the main pancreatic duct.