Loci from a genome-wide analysis of bilirubin levels are associated with gallstone risk and composition

BACKGROUND & AIMS

Genome-wide association studies have mapped loci that are associated with serum levels of bilirubin. Bilirubin is a major component of gallstones so we investigated whether these variants predict gallstone bilirubin content and overall risk for gallstones.

METHODS

Loci that were identified in a meta-analysis to attain a genome-wide significance level of a P value less than 1.0×10(-7) (UGT1A1, SLCO1B1, LST-3TM12, SLCO1A2) were analyzed in 1018 individuals with known gallstone composition. Gallstone risk was analyzed in 2606 German choleystecomized individuals and 1121 controls and was replicated in 210 cases and 496 controls from South America.

RESULTS

By using the presence of bilirubin as a phenotype, variants rs6742078 (UGT1A1; P = .003), rs4149056 (SLCO1B1; P = .003), and rs4149000 (SLCO1A2; P = .015) were associated with gallstone composition. In regression analyses, only UGT1A1 and SLCO1B1 were independently retained in the model. UGT1A1 (rs6742078; P = .018) was associated with overall gallstone risk. In a sex-stratified analysis, only male carriers of rs6742078 had an increased risk for gallstone disease (P = 2.1×10(-7); odds ratio(recessive), 2.34; P(women) = .47). The sex-specific association of rs6742078 was confirmed in samples from South America (P(men) = .046; odds ratio(recessive), 2.19; P(women) = .96).

CONCLUSIONS

The UGT1A1 Gilbert syndrome variant rs6742078 is associated with gallstone disease in men; further studies are required regarding the sex-specific physiology of bilirubin and bile acid metabolism. Variants of ABCG8 and UGT1A1 are the 2 major risk factors for overall gallstone disease, they contribute a population attributable risk of 21.2% among men.

Chronic portal vein thrombosis: transcapsular hepatic collateral vessels and communicating ectopic varices

PURPOSE

To assess patients with chronic portal vein thrombosis (PVT) with respect to transcapsular collateral veins, the communication between these veins and ectopic varices, and the cause of PVT.

MATERIALS AND METHODS

This study was approved by the institutional review committees, and written informed consent was obtained. From November 2003 to March 2008, 145 consecutive patients with chronic PVT due to a variety of causes were assessed for transcapsular collaterals and ectopic varices with ultrasonography (US). Analysis of contingency tables was performed with the Fisher exact test.

RESULTS

Transcapsular collaterals were detected in 15 (10.3%) of 145 patients with chronic PVT. They were restricted to patients with a history of hepatobilary surgery, severe pancreatitis, or abdominal surgery (n = 21) and were not detected in patients with liver cirrhosis, systemic coagulopathy, extrahepatic malignancy, idiopathic PVT, chronic pancreatitis, or infectious or inflammatory diseases (n = 124) (P < .001). Ectopic varices were infrequent in 70 patients with liver cirrhosis (n = 2, 3%) but were common in 14 patients with PVT after hepatobiliary surgery (n = 9, 64%) (P < .001, odds ratio = 21.4). Direct communication between transcapsular collaterals and ectopic varices was visible in all nine patients in this cohort. In eight of these patients, ectopic varices were found to be the bleeding source in gastrointestinal hemorrhage.

CONCLUSION

Transcapsular collaterals frequently occur in patients with chronic PVT due to hepatobilary surgery or necrotizing pancreatitis. They are associated with ectopic varices; therefore, awareness of transcapsular collaterals in this patient subgroup will help to localize ectopic varices as potential bleeding source.

Chances and risks in living donor liver transplantation

INTRODUCTION

Liver transplantation is the first-line therapy in treatment of end-stage liver diseases. Due to the mismatch of available donor organs and growing waiting lists in Germany, live donation is of great interest.

METHODS

Selective literature review.

RESULTS AND DISCUSSION

Pediatric living donor liver transplantation almost eliminated waiting list mortality in children and achieved excellent short and long term survival. The situation in adult-to-adult living donor liver transplantation is different, due to the need for extensive donor resection and smaller graft volume for the recipient. Careful donor evaluation and defined selection criteria are essential to minimize the donor's risk and to achieve results comparable to whole organ transplantation. Living donor liver transplantation offers the recipient certain advantages such as superior graft quality, but the procedure should be reserved for selected patients. Donor safety is the highest priority in this procedure. Living donor transplantation should remain in the hands of experienced centers.

Recipient levels and function of von Willebrand factor prior to liver transplantation and its consumption in the course of grafting correlate with hepatocellular damage and outcome*

Von Willebrand factor (vWF) is a major platelet adhesion molecule at sites of vascular injury, such as observed in ischemia/reperfusion injury following orthotopic liver transplantation (OLT). Thirty-three OLT patients were divided into groups with elevated or low markers of hepatocellular damage (high and low-HD). Whole-blood aggregometry was performed to evaluate platelet function. Multimeric analysis was utilized to evaluate functional vWF levels in the course of OLT. Donor and recipient demographics were comparable among groups. Low-HD patients demonstrated better preserved coagulation parameters on POD 1-6 if contrasted to high-HD patients. One year graft survival for the high-HD group was lower than low-HD patients (P = 0.037). Preoperative vWF-dependent platelet aggregation and functional vWF plasma levels correlated directly with alanine transaminase levels early after OLT as did the decrease of functional vWF to reperfusion. In summary, these data suggest that vWF may serve as a significant mediator of platelet recruitment and hepatocellular injury in the graft following reperfusion.

Differential expression of somatostatin receptor subtypes in hepatocellular carcinomas

BACKGROUND/AIMS

Somatostatin analogues inhibit cell proliferation by stimulation of distinct somatostatin receptor (SSTR) subtypes. In recent years, these compounds have been introduced into the therapy of advanced hepatocellular carcinoma (HCC). The efficacy of this treatment is under debate due to the controversial results of clinical trials. Despite the widespread clinical use of somatostatin analogues in HCC, little is known about the expression of each of the five SSTRs in these tumors.

METHODS

We analyzed the expression of SSTR subtypes in 56 HCCs by immunohistochemistry using subtype-specific antibodies. Six of the samples were also investigated by RT-PCR using subtype-specific oligonucleotide primers.

RESULTS

HCCs display differential, individual expression patterns as well as variable expression levels for SSTRs. The overall expression rate of SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5 is 46, 41, 64, 0, and 75%, respectively. No significant correlation was observed between SSTR expression and tumor stage, differentiation, histological tumor type, or underlying liver disease.

CONCLUSIONS

Individual patterns and levels of SSTR expression might determine the response to treatment with somatostatin analogues in HCC. Selective treatment of these tumors based on the analysis of SSTR subtype expression might lead to an increase in response rates.

Aktueller Stand der Radiofrequenzablation von Lebertumoren

INTRODUCTION

Radio frequency ablation (RFA) represents a new technique for local destruction of liver tumors. Indication and procedure are poorly validated at present.

METHOD

To record the actual nationwide RFA application in Germany, a survey of 2026 hospitals with standardized questionnaires was conducted.

RESULTS

With a respond rate of 17.5%, results from 58 hospitals covering 1700 ablated patients were analyzed. In 25.9% of them, RFA is already used in potentially curative resectable tumors, in 22.4% even when incomplete ablation for tumor mass reduction is expected. Of the 58 hospitals, 75% combine resection and RFA to reach a so-called R-0 situation. The maximal tumor sizes they quoted for achieving complete ablation ranged from <3 cm to 11 cm. In contraindications for RFA, the tumor size, number of tumors, critical localization of the tumor, and disorders of liver function were mentioned the most.

CONCLUSION

This survey documents significant discrepancies in indication, application, procedure, and results in RFA for liver tumors. The lack of general standards and an overestimation of the method may lead to uncritical application, neglect of standard therapy, or unsatisfying results.

[Formation of portal venous collaterals after ligation of the portal vein for induction of liver regeneration]

PURPOSE

Unilateral occlusion of the portal vein induces contralateral lobar hypertrophy - in contrast to complete portal vein occlusion which will result in a cavernous transformation. The impact of the formation of collaterals in partial portal vein occlusion is not sufficiently known. The lobar-hypertrophy- phenomenon is in clinical use for several years to induce iatrogenic liver growth to enable extended resections. After portal vein ligation in patients prior to extended hepatic resections, we noticed a perfusion of the formerly occluded side on CT. Using the well-established mini pig model, we were interested whether portal collaterals are formed as cause of the reperfusion. Ex-situ angiograms of the liver were used for the depiction of collaterals.

MATERIALS AND METHODS

Using a median laparotomy as access for preparation of the hepatoduodenal ligament, a proximal left portal vein ligation was performed in eight mini pigs under general anesthesia. The total arrest of the portal blood flow (except in segments VI and VII) was documented by duplex ultrasound. After 4 weeks, all pigs were sacrificed and the weight of the ligated liver segments and non-ligated liver segments was measured and compared to a sham group (n = 5). After insertion of a guiding sheath, an ex-situ DSA of the portal vein was acquired.

RESULTS

Compared with the sham group, the liver weight increased by 60 % (23 - 99 %, std. dev. 30 %) in segments VI and VII. Atrophy of the ligated segments was signified by a weight loss of 10 % (standard deviation 15 %). The ex-situ angiograms revealed a uniform pattern of collaterals with subsequent complete total recanalization of the formerly occluded portal vein distal from the ligation. The collaterals reduced the portal venous flow rate.

CONCLUSION

After portal vein ligation, uniform collateralization results in recanalization of the occluded portal vein. The extent of the collaterals exceeds the known cavernous transformation. The increase in liver volume is not restrained by the formation of collaterals.