Mild hepatic steatosis is not a major risk factor for hepatectomy and regenerative power is not impaired

Vibration Controlled Transient Elastography to Evaluate Steatosis in Candidate Living Donors for Liver Transplantation

BACKGROUND

The ability of vibration controlled transient elastography (VCTE) to reliably exclude significant steatosis in living donor candidates could obviate the need for invasive liver biopsies, expedite the donor approval process, and reduce recipient wait time. We therefore aimed to determine whether VCTE controlled attenuation parameter (CAP) could be used to detect steatosis in potential living donors.

METHODS

Living donor candidates who presented for evaluation between 2016 and 2019 underwent standard donor workup, VCTE, and liver biopsy if indicated. CAP scores were compared with MRI-Fat Fraction and, when available, histologic fat fraction from liver biopsy. Receiver operating characteristic curves were used to identify cutoffs with appropriate sensitivity and specificity for screening. Statistical analysis was conducted using R (version 3.6.0).

RESULTS

Seventy-nine candidate living donors presented during the study period, of whom 71 were included in the final analysis and of whom 20 underwent liver biopsy. There was a positive correlation between MRI-Fat Fraction and CAP scores with an observed Spearman correlation coefficient of 0.424 ( P < 0.01). A CAP score of 271.5 dB/m or less was determined to have 89.8% sensitivity and 75% specificity for detecting <5% steatosis on MRI. The correlation between CAP and steatosis of available histologic samples had a Pearson correlation coefficient of 0.603 ( P = 0.005). A CAP cutoff of 276.0 dB/m demonstrated 66.7% sensitivity and 85.7% specificity for detecting <15% histopathologic steatosis and positive and negative predictive values of 71.5% and 82.7%, respectively.

CONCLUSIONS

VCTE can be integrated into living donor evaluation to accurately screen for hepatic steatosis.

Outcomes after curative therapy for hepatocellular carcinoma in patients with non-alcoholic fatty liver disease: a meta-analysis and review of current literature

BACKGROUND

This systematic review and meta-analysis aimed to compare the outcomes of curative therapy (resection, transplantation, ablation) for hepatocellular carcinoma (HCC) arising from non-alcoholic fatty liver disease (NAFLD) and non-NAFLD etiologies.

METHODS

A systematic search of PubMed, EMBASE and Cochrane Library was conducted for studies comparing survival, peri- and post-operative outcomes. Quality assessment was performed using the Newcastle-Ottawa scale.

RESULTS

Findings for 5579 patients were pooled across 9 studies and examined. Analysis demonstrated improved disease-free survival (DFS; HR 0.85, 95% CI 0.74-0.98, p = 0.03) and overall survival (OS; HR 0.87; 95% CI 0.81-0.93; p < 0.0001) in NAFLD-HCC patients undergoing liver resection as compared to non-NAFLD HCC patients. NAFLD-HCC patients undergoing all forms of curative therapy were similarly associated with improved OS (HR 0.96; 95% CI 0.86-1.06; p = 0.40) and DFS (HR 0.85; 95% CI 0.74-0.98; p = 0.03), albeit results being significant only for DFS. Only 2 studies reported higher rates of peri- and post-operative complications in patients with NAFLD-HCC. Significant inter-study heterogeneity precluded further analysis.

CONCLUSION

NAFLD-HCC patients can enjoy long-term survival benefit with aggressive curative therapy. Peri- and post-operative morbidity should be mitigated with pre-operative optimization of comorbidities, and deliberately close post-operative monitoring.

Clinical Outcome of Residual Liver Volume and Hepatic Steatosis After Right-Lobe Living-Donor Hepatectomy

Background

We examine how residual liver volume (RLV) and hepatic steatosis (HS) of living liver donors affect the regeneration process and clinical outcomes.

Material/Methods

We longitudinally studied 58 donors who underwent right-lobe hepatectomy during the period February 2014 to February 2015 at a single medical institution. The patients were classified based on RLV (30–35%, 35–40%, 40–50%) subgroups and HS (<10%, 10–30%, 30–50%) subgroups. Clinical parameters such as clinical outcome, liver volumetric recovery (LVR,%) rate and remnant left-liver (RLL,%) growth rate were collected for analysis.

Results

The clinical features of postoperative peak total bilirubin (p=.024) were significant in the 3 RLV subgroups. Body mass index (p=.017), preoperative alanine transaminase (p<.001), and pleural effusion (p=.038) were significant in the 3 HS subgroups. The LVR rate and RLL growth rate equations showed significant variation in regeneration among the 3 RLV subgroups. The LVR rate and RLL growth rate equations did not show significant variation in regeneration among the 3 HS subgroups.

Conclusions

Hyperbilirubinemia was a risk factor in the small-RLV group, and a large amount of pleural effusion was a risk factor in the steatosis 30–50% group. Hepatic steatosis subgroups did not show significantly different degrees of regeneration. The safety of living donors was a major concern while we compiled the extended living-donor criteria presented in this paper.

Pre-hepatic and pre-pancreatic transplant donor evaluation

Innovations in surgical techniques coupled with advances in medical and pharmacological management in the past few decades have enabled organ transplantation to become integral to the management of end stage organ failure. In this review article, we will review the role of the radiologist in the work up of liver and pancreas donors during evaluation of their donor candidacy. The critical role of imaging in assessing the parenchymal, biliary and vascular anatomy in liver donor candidates will be reviewed, as well as highlighting the anatomical findings that may pose a contraindication to transplantation. The limited role of imaging in pancreas donor evaluation is also covered, as well as a brief overview of the surgical techniques available and how the radiologist's findings influence operative technique selection.

The impact of steatosis on liver regeneration

Alcoholic and non-alcoholic fatty liver diseases are the leading causes of cirrhosis in Western countries. These chronic liver diseases share common pathological features ranging from steatosis to steatohepatitis. Fatty liver is associated with primary liver graft dysfunction, a higher incidence of complications/mortality after surgery, in correlation with impaired liver regeneration. Liver regeneration is a multistep process including a priming phase under the control of cytokines followed by a growth factor receptor activation phase leading to hepatocyte proliferation. This process ends when the initial liver mass is restored. Deficiency in epidermal growth factor receptor (EGFR) liver expression, reduced expression of Wee1 and Myt1 kinases, oxidative stress and alteration in hepatocyte macroautophagy have been identified as mechanisms involved in the defective regeneration of fatty livers. Besides the mechanisms, we will also discuss in this review various treatments that have been investigated in the reversal of the regeneration defect, for example, omega-3 fatty acids, pioglitazone, fibroblast growth factor (FGF)19-based chimeric molecule or growth hormone (GH). Since dysbiosis impedes liver regeneration, targeting microbiota could also be an interesting therapeutic approach.

A predictive scoring system for insufficient liver hypertrophy after preoperative portal vein embolization

BACKGROUND

The factors which affect hypertrophy of the future liver remnant after portal vein embolization remain unclear. The aim of this study was to clarify the clinical factors affecting the hypertrophy rate after portal vein embolization and to develop a scoring system predicting insufficient liver hypertrophy.

METHODS

The cases of a total of 152 patients who underwent portal vein embolization of the right portal branch between 2006 and 2016 were reviewed retrospectively. The score to predict insufficient (<25%) hypertrophy was established based on logistic regression analyses of the clinical parameters before portal vein embolization.

RESULTS

After portal vein embolization, the future liver remnant volume, expressed as the median (range), significantly increased from 364 (151-801) mL, 33% (18%-54%), to 451 (242-866) mL, 42% (26%-65%). The median hypertrophy rate was 24% (-5% to 96%). A preoperative predictive scoring system for insufficient liver hypertrophy was constructed using the following 3 factors: an initial future liver remnant volume ≥35% (2 points), alkaline phosphatase ≥450 IU/dL (1 point), and cholinesterase <220 mg/dL (1 point). The constructed scoring system indicated the proportion of patients with insufficient liver hypertrophy (<25%) to be 6 out of 42 (14%) in the low-score group (0 points), 44 out of 77 (57%) in the medium-score group (1-2 points), and 30 out of 33 (91%) in the high-score group (3-4 points). The hypertrophy rate of future liver remnant was different among the 3 groups (low-score group, 38.9% [-2.4% to 81.4%]; medium-score group, 22.7% [-5.1% to 95.5%]; high-score group, 18.2% [2.4%-30.7%]) (P < .001).

CONCLUSION

The constructed scoring system was able to stratify patients before portal vein embolization according to the possibility of developing insufficient liver hypertrophy.

Assessing the Non-tumorous Liver: Implications for Patient Management and Surgical Therapy

INTRODUCTION

Hepatic resection is performed for various benign and malignant liver tumors. Over the last several decades, there have been improvements in the surgical technique and postoperative care of patients undergoing liver surgery. Despite this, liver failure following an extended hepatic resection remains a critical potential postoperative complication. Patients with underlying parenchymal liver diseases are at particular risk of liver failure due to impaired liver regeneration with an associated mortality risk as high as 60 to 90%. In addition, live donor liver transplantation requires a thorough presurgical assessment of the donor liver to minimize the risk of postoperative complications.

RESULTS AND CONCLUSION

Recently, cross-sectional imaging assessment of diffuse liver diseases has gained momentum due to its ability to provide both anatomical and functional assessments of normal and abnormal tissues. Various imaging techniques are being employed to assess diffuse liver diseases including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound (US). MRI has the ability to detect abnormal intracellular and molecular processes and tissue architecture. CT has a high spatial resolution, while US provides real-time imaging, is inexpensive, and readily available. We herein review current state-of-the-art techniques to assess the underlying non-tumorous liver. Specifically, we summarize current approaches to evaluating diffuse liver diseases including fatty liver alcoholic or non-alcoholic (NAFLD, AFLD), hepatic fibrosis (HF), and iron deposition (ID) with a focus on advanced imaging techniques for non-invasive assessment along with their implications for patient management. In addition, the role of and techniques to assess hepatic volume in hepatic surgery are discussed.

Association of Remnant Liver Ischemia With Early Recurrence and Poor Survival After Liver Resection in Patients With Hepatocellular Carcinoma

Importance

The remnant liver after hepatectomy may have inadequate blood supply, especially following nonanatomical resection or vascular damage.

Objective

To evaluate whether remnant liver ischemia (RLI) may have an adverse effect on long-term survival and morbidity after liver resection in patients with hepatocellular carcinoma.

Design, Setting, and Participants

This study was a retrospective analysis at Seoul National University Bundang Hospital. Remnant liver ischemia was graded on postoperative computed tomographic scans in 328 patients who underwent hepatectomy for hepatocellular carcinoma between January 1, 2004, and December 31, 2013.

Main Outcomes and Measures

Remnant liver ischemia was defined as reduced or absent contrast enhancement during the venous phase. Remnant liver ischemia was classified as minimal (none or marginal) or severe (partial, segmental, or necrotic).

Results

Among 328 patients (252 male and 76 female; age range, 26-83 years [mean age, 58.2 years]), radiologic signs of severe RLI were found in 98 patients (29.9%), of whom 63, 16, and 19 had partial, segmental, or necrotic RLI, respectively. These patients experienced more complications and longer hospital stay than patients with minimal RLI. Preoperative history of transarterial embolization (odds ratio [OR], 1.77; 95% CI, 1.02-3.03; P = .04), use of the Pringle maneuver (OR, 1.96; 95% CI, 1.08-3.58; P = .03), and longer operative time (OR, 1.003; 95% CI, 1.002-1.005; P < .001) were independent risk factors for severe RLI. Early recurrence rates within 6 (60.2% vs 9.6%) or 12 (79.6% vs 18.7%) months after hepatectomy were higher in patients with severe RLI than in patients without RLI (P < .001). Severe remnant liver ischemia was an independent risk factor for overall survival (OR, 6.98; 95% CI, 4.27-11.43; P < .001) and disease-free survival (OR, 5.15; 95% CI, 3.62-7.35; P < .001).

Conclusions and Relevance

Preventive management and technical refinements in hepatectomy are important to decrease the risk of RLI and to improve survival of patients with hepatocellular carcinoma.

Does Simple Steatosis Affect Liver Regeneration after Partial Hepatectomy in Rats?

Aim: The aim of our study was to assess whether simple steatosis impairs liver regeneration after partial hepatectomy (PHx) in rats. Methods: Male Sprague–Dawley rats were fed a standard diet (ST-1, 10% kcal fat) and high-fat diet (HFD, 71% kcal fat) for 6 weeks. Then the rats were submitted to 2/3 PHx and animals were sacrificed 24, 48 or 72 h after PHx. Serum biochemistry, respiration of mitochondria in liver homogenate, hepatic oxidative stress markers, selected cytokines and DNA content were measured, and histopathological samples were prepared. Liver regeneration was evaluated by incorporation of bromodeoxyuridine (BrdU) to hepatocyte DNA. Results: HFD induced simple microvesicular liver steatosis. PHx caused elevation of serum markers of liver injury in both groups; however, an increase in these parameters was delayed in HFD group. Hepatic content of reduced glutathione was significantly increased in both groups after PHx. There were no significant changes in activities of respiratory complexes I and II (state 3). Relative and absolute liver weights, total DNA content, and DNA synthesis exerted very similar changes in both ST-1 and HFD groups after PHx. Conclusion: PHx-induced regeneration of the rat liver with simple steatosis was not significantly affected when compared to the lean liver.

Future remnant liver function estimated by combining liver volumetry on magnetic resonance imaging with total liver function on (99m)Tc-mebrofenin hepatobiliary scintigraphy: can this tool predict post-hepatectomy liver failure?

INTRODUCTION

Posthepatectomy liver failure (PHLF) is a major complication after hepatectomy with a high mortality rate and is likely to happen in insufficient liver remnant. We hypothesize that assessment of the estimated future liver remnant function (eFLRF), combining future remnant liver volume (FLRV) with total liver function (TLF), is an accurate formula for prediction of PHLF.

METHODS

88 patients undergoing hepatectomy were included. The ratio of the future liver remnant volume (FLRV%) was measured on MRI. TLF was estimated by liver clearance of (99m)Technetium (Tc)-mebrofenin on hepatobiliary scintigraphy (HBS). eFLRF was calculated by multiplying FLRV% by TLF. Cut-off values of FLRV% and eFLRF predicting PHLF, were defined by receiver-operating-characteristic (ROC) analysis.

RESULTS

PHLF occurred in 12 patients (13%). Perioperative mortality was 5/12 (41%). Multivariate analysis showed that FLRV% cut off at 40% was not an independent predictive factor. eFLRF cut off at 2.3%/min/m(2) was the only independent predictive factor for PHLF. For FLRV% vs. eFLRF, positive predictive value was 41% vs. 92% and Odds Ratio 26 vs. 836.

CONCLUSION

FRLF measured by combining FLRV% and TLF is a more valuable tool to predict PHLF than FLRV% alone. The cutoff of eFLRF can be used in clinical decision making.

Donor Hepatic Steatosis Induce Exacerbated Ischemia-Reperfusion Injury Through Activation of Innate Immune Response Molecular Pathways

BACKGROUND

Severe liver steatosis is a known risk factor for increased ischemia-reperfusion injury (IRI) and poor outcomes after liver transplantation (LT). This study aimed to identify steatosis-related molecular mechanisms associated with IRI exacerbation after LT.

METHODS

Paired graft biopsies (n = 60) were collected before implantation (L1) and 90 minutes after reperfusion (L2). The LT recipients (n = 30) were classified by graft macrosteatosis: without steatosis (WS) of 5% or less (n = 13) and with steatosis (S) of 25% or greater (n = 17). Plasma samples were collected at L1, L2, and 1 day after LT (postoperative [POD]1) for cytokines evaluation. Tissue RNA was isolated for gene expression microarrays. Probeset summaries were obtained using robust multiarray average algorithm. Pairwise comparisons were fit using 2-sample t test. P values 0.01 or less were significant (false discovery rate <5%). Molecular pathway analyses were conducted using Ingenuity Pathway Analysis tool.

RESULTS

Significantly differentially expressed genes were identified for WS and S grafts after reperfusion. Comprehensive comparison analysis of molecular profiles revealed significant association of S grafts molecular profile with innate immune response activation, macrophage production of nitric oxide and reactive oxygen species, IL-6, IL-8, IL-10 signaling activation, recruitment of granulocytes, and accumulation of myeloid cells. Postreperfusion histological patterns of S grafts revealed neutrophilic infiltration surrounding fat accumulation. Circulating proinflammatory cytokines after reperfusion and 24 hours after LT concurred with intragraft-deregulated molecular pathways. All tested cytokines were significantly increased in plasma of S grafts recipients after reperfusion when compared with WS group at same time.

CONCLUSIONS

Increases of graft steatosis exacerbate IRI by exacerbation of innate immune response after LT. Preemptive strategies should consider it for safety usage of steatotic livers.

Outcomes of Simultaneous Major Liver Resection and Colorectal Surgery for Colorectal Liver Metastases

BACKGROUND

The optimal surgical strategy for treating colorectal cancer liver metastases (CRLM) in patients requiring major liver resection (MLR) is controversial, especially in rectal cancer patients.

METHOD

Between March 2004 and January 2015, 103 patients underwent MLR for CRLM and underwent MLR simultaneously with colorectal surgery (simultaneous group; n = 55) or MLR after colorectal surgery (liver-only group; n = 48).

RESULTS

There were no significant differences in sex, age, ASA score, BMI, size and number of liver metastases, liver resection margin, surgical outcomes, and estimated blood loss. The rates of postoperative complications (simultaneous group vs. liver-only group; 76.4 % vs. 62.5 %; P = 0.126) and major complications (29.0 % vs. 25.0 %; P = 0.513) were also similar in both groups. The time to starting a soft diet was longer in the simultaneous group (6.0 days vs. 3.4 days; P < 0.001), but the length of hospital stay was similar (14.9 days vs. 13.3 days; P = 0.345). There were no perioperative deaths, anastomotic leakage, or septic complications. Among patients who underwent rectal surgery, the frequency of complications was greater in the simultaneous group (87.0 % vs. 56.2 %; P = 0.031), but there was no difference in major complications (34.7 % vs. 25.0 %; P = 0.822). The postoperative morbidity index was 0.204 and 0.180 in the simultaneous and liver-only groups, respectively, in all patients, and was 0.227 and 0.136, respectively, in the rectal surgery subgroup.

CONCLUSION

Simultaneous MLR is feasible and safe in synchronous CRLM patients, including rectal cancer patients.

Effect of branched-chain amino acid supplementation on functional liver regeneration in patients undergoing portal vein embolization and sequential hepatectomy: a randomized controlled trial

BACKGROUND

Portal vein embolization (PVE) can decrease the resection ratio for major hepatectomy. (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy is useful for evaluating quantitative functional liver volume. Branched chain amino acids (BCAAs) modulate liver function and regeneration. We analyzed the effects of BCAAs, in terms of liver function and regeneration after PVE, in combination with major hepatectomy.

METHODS

This randomized controlled trial was conducted for patients receiving PVE through to complete hepatectomy from September, 2011 to June, 2013. BCAA granules were added two times a day to a conventional diet in the BCAA administration group (BCAA group). The primary end point was functional liver regeneration of the future remnant liver after PVE followed by hepatic resection. Functional liver regeneration was assessed by the liver uptake value obtained from (99m)Tc-GSA scintigraphy single-photon-emission computed tomography/computed tomography fusion images. The secondary end points were volumetric liver regeneration and changes in liver function and laboratory data.

RESULTS

A BCAA group (n = 13) and a non-BCAA group (control group; n = 15) were included. The primary end point was partially met: the liver uptake value significantly increased in the BCAA group compared with the control group 6 months after hepatic resection (266.7% vs 77.6%, P = 0.04) and marginally increased after PVE (43.8% vs 17.4%, P = 0.079). Following PVE, the increment of the uptake ratio of the liver to the liver plus heart at 15 min was significantly less in the BCAA group than in the control group (0.0 and 0.01, P = 0.023).

CONCLUSIONS

BCAA supplementation improved functional liver regeneration and function in patients undergoing PVE followed by major hepatic resection.

Vitamin E Attenuates the Progression of Non-Alcoholic Fatty Liver Disease Caused by Partial Hepatectomy in Mice

Background and Aim

The progression of non-alcoholic fatty liver disease (NAFLD) likely involves a ‘multiple hit’ mechanism. We hypothesized that partial hepatectomy, a procedure performed frequently in patients with NAFLD, would accelerate the progression of disease.

Methods

C57BL/6JolaHsd mice were fed a choline-deficient L-amino acid-defined diet (CD-AA) or a choline-sufficient L-amino acid-defined control diet (CS-AA). Part of the mice in the CD-AA group received a diet enriched in vitamin E (~20 mg /day). Two weeks after the start of the diet, mice underwent a partial hepatectomy or a sham operation.

Results

In the CD-AA group, NAFLD activity scores were significantly higher at 7 days after partial hepatectomy compared to the sham operated mice (3.7 ± 1.3 vs. 1.8 ± 0.7; P<0.05). In addition, TBARS, a measure for oxidative stress, in liver tissue of the CD-AA group were significantly higher at day 1, 3 and 7 after partial hepatectomy compared to the sham operated mice (P<0.05). Vitamin E therapy significantly reduced TBARS level at day 7 after partial hepatectomy compared to the CD-AA diet group (P< 0.05). Vitamin E suppletion reduced NAFLD activity score at day 7 after partial hepatectomy compared to the CD-AA group (2.3 ± 0.8 vs. 3.8 ± 1.0; P<0.05).

Conclusion

Partial hepatectomy accelerates the progression of NAFLD. Disease progression induced by partial hepatectomy is substantially attenuated by vitamin E.

Ischemia–reperfusion injury in patients with fatty liver and the clinical impact of steatotic liver on hepatic surgery

Hepatic steatosis is one of the most common hepatic disorders in developed countries. The epidemic of obesity in developed countries has increased with its attendant complications, including metabolic syndrome and non-alcoholic fatty liver disease. Steatotic livers are particularly vulnerable to ischemia/reperfusion injury, resulting in an increased risk of postoperative morbidity and mortality after liver surgery, including liver transplantation. There is growing understanding of the molecular and cellular mechanisms and therapeutic approaches for treating ischemia/reperfusion injury in patients with steatotic livers. This review discusses the mechanisms underlying the susceptibility of steatotic livers to ischemia/reperfusion injuries, such as mitochondrial dysfunction and signal transduction alterations, and summarizes the clinical impact of steatotic livers in the setting of hepatic resection and liver transplantation. This review also describes potential therapeutic approaches, such as ischemic and pharmacological preconditioning, to prevent ischemia/reperfusion injury in patients with steatotic livers. Other approaches, including machine perfusion, are also under clinical investigation; however, many pharmacological approaches developed through basic research are not yet suitable for clinical application.

Recent advancements in and views on the donor operation in living donor liver transplantation: a single-center study of 886 patients over 13 years

Donor safety remains an important concern in living donor liver transplantation (LDLT). In the present study, we assessed recent advancements in the donor operation for LDLT through our experience with this procedure. A total of 886 donor hepatectomies performed between January 1999 and December 2012 were analyzed. Three chronological periods were investigated: the initial period (1999-2004, n = 239), the period in which the right liver with middle hepatic vein reconstruction was primarily used (2005-2010, n = 422), and the period in which the right liver with a standardized protocol, including a preoperative donor diet program, an evaluation of steatosis with magnetic resonance spectroscopy, no systemic heparin administration or central venous pressure monitoring, exact midplane dissection, and incremental application of minimal incisions, was exclusively used (2011-2012, n = 225). The proportion of patients > 50 years old increased (2.5% versus 4.7% versus 8.9%), whereas the proportion of patients with a remnant liver volume ≤ 30% (6.5% versus 13.9% versus 6.3%) and with macrosteatosis ≥ 10% (7.9% versus 11.1% versus 4.4%) decreased throughout the periods. The operative time (292.7 versus 290.0 versus 272.8 minutes), hospital stay (12.4 versus 11.2 versus 8.5 days), and overall morbidity rate (26.4% versus 13.3% versus 5.8%), including major complications (>grade 3; 1.7% versus 1.9% versus 0.9%) and biliary complications (7.9% versus 5.0% versus 0.9%), were markedly reduced in the most recent period. No intraoperative transfusion was required. No cases of irreversible disability or mortality were noted. In conclusion, the quality of the donor operation has recently been standardized through a large volume of experience, and the operation has been proven to have minimal risk. However, a constant evaluation of our experience is critical for remaining prepared for any unavoidable crisis.

Complications following hepatectomy

As the number of liver resections in the United States has increased, operations are more commonly performed on older patients with multiple comorbidities. The advent of effective chemotherapy and techniques such as portal vein embolization, have compounded the number of increasingly complex resections taking up to 75% of healthy livers. Four potentially devastating complications of liver resection include postoperative hemorrhage, venous thromboembolism, bile leak, and post-hepatectomy liver failure. The risk factors and management of these complications are herein explored, stressing the importance of identifying preoperative factors that can decrease the risk for these potentially fatal complications.

Postoperative complications influence prognosis and recurrence patterns in periampullary cancer

BACKGROUND

The present study was performed to elucidate the influence of postoperative complications on the prognosis and recurrence patterns of periampullary cancer after pancreaticoduodenectomy (PD).

METHODS

Clinical data were reviewed from 200 consecutive patients who had periampullary cancer and underwent PD between October 2003 and July 2010, and survival outcomes and recurrence patterns were analyzed. Postoperative complications were classified according to a modification of Clavien's classification.

RESULTS

Overall, 86 major complications of grade II or higher occurred in 71 patients. The patients were classified into two groups according to the presence of postoperative complications of grade II or higher: group Cx-, absence of complications (n = 129); and group Cx+, presence of complications (n = 71). There were no differences in gender, mean age, tumor node metastasis stage, biliary drainage, type of resection, and radicality between the two groups (P > 0.05). The 3-year overall and disease-free survival rates of the group Cx+ patients (31.0 and 22.3 %, respectively) were significantly lower than those of the group Cx- patients (49.0 and 40.0 %; P = 0.003 and 0.002, respectively). The multivariate analysis showed that postoperative complications (P = 0.001; RR = 1.887; 95 % confidence interval [CI] 1.278-2.785), a T stage of T3 or T4 (P = 0.001; RR = 2.503; 95 % CI 1.441-4.346), positive node metastasis (P = 0.001; RR = 2.093; 95 % CI, 1.378-3.179), R1 or R2 resection (P = 0.023; RR = 1.863; 95 % CI 1.090-3.187), and angiolymphatic invasion (P = 0.013; RR = 1.676; 95 % CI 1.117-2.513) were independent prognostic factors for disease-free survival. Regarding recurrence patterns, group Cx+ patients exhibited more distant recurrences than did group Cx- patients (P = 0.025).

CONCLUSIONS

Postoperative complications affect prognosis and recurrence patterns in patients with periampullary cancer after PD.

Drug-induced steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease in the United States. The term NALFD was first used by Ludwig in 1980 to describe the presence of hepatic steatosis and steatohepatitis in a series of patients with no identifiable cause. Since then, our insight into the pathogenesis of NAFLD has expanded significantly. We now know that NAFLD is closely related to metabolic syndrome and chronic low-grade inflammation. In the following review, the authors summarize the current evidence about drugs that lead to hepatic steatosis and steatohepatitis and pathogenic mechanisms thereof.

Safe use of highly steatotic livers by utilizing a donor/recipient clinical algorithm

The aim of this study was to assess the long-term safety and clinical outcomes associated with the utilization of highly steatotic donor livers utilizing a specific donor/recipient matching algorithm. This was a prospective, observational, single-center, 10-yr follow-up study. Highly steatotic livers were utilized according to a donor/recipient algorithm that guided the surgeon to use highly steatotic donor organs judiciously in low-risk recipients. This study initially compared fat assessment based on frozen-section Ehrlich's hematoxylin and eosin (H&E) to reperfusion biopsy fat assessment and demonstrated that H&E is an insensitive analysis to determine degree of steatosis. Patients were divided into three groups based on donor steatosis (group 1: <30% steatosis, group 2: 30-60% steatosis, group 3: >60% steatosis), and clinical outcomes were assessed. One hundred and sixteen patients were included in the analysis. Patients that received severely steatotic livers (>60% fat) showed increased reperfusion liver injury and delayed return of liver function in the early postoperative period, demonstrated by biochemical markers. However, there were no differences in primary non-function, postoperative complications, length of stay, and patient and graft survival. Using rigorous donor/recipient matching through a detailed algorithm, these data demonstrate that normal liver allograft outcomes are not superior to those in highly steatotic grafts.

Steatosis among living liver donors without evidence of fatty liver on ultrasonography: potential implications for preoperative liver biopsy

BACKGROUND

The degree of steatosis is an important factor that determines the graft function in the recipient and the recovery of the remnant liver in the living donor. To date, there is no consensus regarding how to assess steatosis among potential living liver donors. We evaluate the prevalence and risk factors for steatosis in living liver donors with normal serum aminotransferase levels and without fatty liver on ultrasonography (US-negative).

METHODS

The degree of steatosis was assessed for a total of 492 US-negative living liver donors with normal aminotransferase levels (age 30.1±9.9; male 301 [61.2%]). Total steatosis was defined by adding the degree of macrosteatosis and microsteatosis.

RESULTS

No liver donor had a severe degree (≥60%) of macrosteatosis or microsteatosis. A moderate degree (30-59%) of macrosteatosis and microsteatosis was seen in 4 (0.8%) and 26 (5.3%) subjects, respectively. Severe and moderate degrees of total steatosis were seen in 3 (0.6%) and 53 (10.8%) subjects, respectively. Body mass index and serum triglyceride levels were independent factors associated with the moderate or greater degree of total steatosis.

CONCLUSIONS

Noninvasive preoperative assessment for liver steatosis (US-negative with normal aminotransferase level) was sufficient to exclude severe macrosteatosis or microsteatosis and moderate macrosteatosis but not sufficient to exclude moderate microsteatosis or total steatosis in living liver donors.

Influence of Kupffer cells and platelets on ischemia-reperfusion injury in mild steatotic liver

AIM: To investigate the effect of mild steatotic liver on ischemia-reperfusion injury by focusing on Kupffer cells (KCs) and platelets.

METHODS: Wistar rats were divided into a normal liver group (N group) and a mild steatotic liver group (S group) induced by feeding a choline-deficient diet for 2 wk. Both groups were subjected to 20 min of warm ischemia followed by 120 min of reperfusion. The number of labeled KCs and platelets in sinusoids and the blood perfusion in sinusoids were observed by intravital microscopy (IVM), which was performed at 30, 60 and 120 min after reperfusion. To evaluate serum alanine aminotransferase as a marker of liver deterioration, blood samples were taken at the same time as IVM.

RESULTS: In the S group, the number of platelets adhering to KCs decreased significantly compared with the N group (120 after reperfusion; 2.9 ± 1.1 cells/acinus vs 4.8 ± 1.2 cells/acinus, P < 0.01). The number of KCs in sinusoids was significantly less in the S group than in the N group throughout the observation periods (before ischemia, 19.6 ± 3.3 cells/acinus vs 28.2 ± 4.1 cells/acinus, P < 0.01 and 120 min after reperfusion, 29.0 ± 4.3 cells/acinus vs 40.2 ± 3.3 cells/acinus, P < 0.01). The blood perfusion of sinusoids 120 min after reperfusion was maintained in the S group more than in the N group. Furthermore, elevation of serum alanine aminotransferase was lower in the S group than in the N group 120 min after reperfusion (99.7 ± 19.8 IU/L vs 166.3 ± 61.1 IU/L, P = 0.041), and histological impairment of hepatocyte structure was prevented in the S group.

CONCLUSION: Ischemia-reperfusion injury in mild steatotic liver was attenuated compared with normal liver due to the decreased number of KCs and the reduction of the KC-platelet interaction.

The impact of hepatic steatosis on liver regeneration after partial hepatectomy

BACKGROUND & AIM

Experimental studies in animals have suggested that liver regeneration is impaired in steatotic livers. However, few studies have focused on the impact of steatosis in patients undergoing partial hepatectomy (PH). This study aims to determine the role of steatosis on liver regeneration in humans following PH.

METHODS

Eighty-eight patients undergoing PH were included in this study. All patients underwent CT-scanning of the liver preoperatively and 7 days after surgery. Additional CT-scans were performed 6 months post-operatively. Preoperative and post-operative volumes of the total liver (TLV), future liver remnant (FLR) and liver remnant (LR) were measured on CT-scans. Regeneration indices (RI) were calculated at 7 days and 6 months using the formula: (Volume LR-Volume FLR)/Volume FLR × 100%. Based on histological examination of the resected part of the liver, patients were classified into three groups: (1) no steatosis, (2) mild steatosis (1-29%) and (3) moderate-to-severe steatosis (≥30%).

RESULTS

The early RI (at day 7) was 40%, 24% and 20% for patients in group 1, 2 and 3 respectively. Late RI (at 6 months) was 81% for group 1, 44% for group 2 and 22% for group 3 (P = 0.019). At 7 days, the LR represented 79%, 80% and 79% of the TLV for groups 1-3. At 6 months, this was 93%, 92% and 79% respectively.

CONCLUSION

Although early RI after PH did not differ in patients with or without steatosis, the late RI in patients with moderate-to-severe steatosis was lower, suggesting that late liver regeneration is impaired in these patients.

Steatosis does not impair liver regeneration after partial hepatectomy

Hepatic steatosis is a key feature of non-alcoholic fatty liver disease (NAFLD). While storage of lipid droplet-bound triglycerides in simple steatosis is physiologically inert, non-alcoholic steatohepatitis (NASH) is associated with hepatocyte damage and apoptosis. Mitochondrial oxidation of free fatty acids (FFA), derived from lipid droplets and hepatocellular uptake, is a rapid and effective way of energy supply for proliferating cells and FFA esterification provides substrates for lipid synthesis and cell proliferation. Thus, we investigated whether simple steatosis induced by western diet (WD) improves liver regeneration after partial hepatectomy (PHx). WD feeding for 6 weeks caused simple steatosis with hepatic lipid droplet and triglyceride accumulation accompanied by induction of fatty acid transport proteins (FATP), death receptors (DR), pro- and anti-apoptotic genes, hepatocyte growth factor (Hgf) as well as increased serum leptin levels in a mouse model. After PHx, liver cell proliferation was higher in WD-fed mice and associated with FATP and Hgf induction. In addition, Erk1/2 (extracellular-related MAP kinase 1/2) dephosphorylation observed in standard diet (SD) mice was reduced in WD animals. PHx in steatotic livers did not affect hepatocyte apoptosis, despite DR upregulation. WD-induced steatosis enhances liver cell proliferation, which is accompanied by increased Hgf and leptin signaling as well as Erk1/2 phosphorylation. Induction of mild steatosis may therefore be beneficial for surgical outcome of hepatectomies.

Underlying steatohepatitis, but not simple hepatic steatosis, increases morbidity after liver resection: a case-control study

Despite the high prevalence of fatty liver disease, the safety of liver resection in settings of steatohepatitis (SH) or hepatic steatosis is poorly understood. The aim of this study was to determine whether underlying SH or simple hepatic steatosis increases morbidity after liver resection. We compared patients undergoing liver resection with underlying SH or greater than 33% simple hepatic steatosis to controls selected for similar demographics, diagnoses, comorbidities, preoperative chemotherapy treatments, and extent of partial hepatectomy. Primary endpoints included postoperative overall and hepatic-related morbidity. One hundred and two patients with SH and 72 with greater than 33% simple hepatic steatosis who underwent liver resection from 2000 to 2011 were compared to corresponding controls. There were no differences in extent or approach of liver resection, malignant indications, preoperative chemotherapy treatment, elements of metabolic syndrome, alcohol use history, American Society of Anesthesiologists score, age, or gender between patients with SH or simple steatosis and corresponding controls. Ninety-day postoperative overall morbidity (56.9% versus 37.3%; P = 0.008), any hepatic-related morbidity (28.4% versus 15.7%; P = 0.043), surgical hepatic complications (19.6% versus 8.8%; P = 0.046), and hepatic decompensation (16.7% versus 6.9%; P = 0.049) were greater among SH patients, compared to corresponding controls. In contrast, there were no differences in postoperative overall morbidity (34.7% versus 44.4%; P = 0.310), any hepatic-related morbidity (19.4% versus 19.4%; P = 1.000), surgical hepatic complications (13.9% versus 9.7%; P = 0.606), or hepatic decompensation (8.3% versus 9.7%; P = 0.778) between simple hepatic steatosis patients and corresponding controls. Using multivariable logistic regression, SH was independently associated with postoperative overall (odds ratio [OR], 2.316; 95% confidence interval [95% CI]: 1.267-4.241; P = 0.007) and any hepatic-related (OR, 2.722; 95% CI: 1.201-6.168; P = 0.016) morbidity.

CONCLUSION

Underlying SH, but not simple hepatic steatosis, increases overall and hepatic-related morbidity after liver resection.

Safety and feasibility of diet-treated donors with steatotic livers at the initial consultation for living-donor liver transplantation

BACKGROUND

The purpose of this study was to evaluate both safety of diet-treated donors and the feasibility of their use for living-donor liver transplantation (LDLT).

METHODS

A total of 128 living donors were enrolled in this study between April 2003 and March 2010. Of them, 41 were diagnosed with hepatic steatosis at the initial consultation. Donor selection was based on the findings of liver biopsy accompanied with normalization of liver function tests after diet treatment consisting of an 800 to 1400 kcal/day diet and a 100 to 400 kcal/day exercise without drug treatment, targeting body mass index of 22 kg/m².

RESULTS

Body mass index of diet-treated donors was significantly reduced with diet from 23.3 ± 0.6 to 21.9 ± 0.4 kg/m² (P<0.0001). Liver function tests associated with fatty liver, including alanine aminotransferase, gamma-glutamyl transpeptidase, and total cholesterol levels, also improved with diet (P=0.0128, 0.0016, and 0.0004, respectively). The liver biopsy results of most of these donors showed stage 0/1 fibrosis and minimal/mild steatosis after the diet therapy. Surgical outcomes, including postoperative liver function tests, perioperative complications, and liver regeneration rates, did not significantly differ between nondiet-treated and diet-treated donors. Surgical outcomes and the overall survival did not significantly differ between recipients of grafts from nondiet-treated and diet-treated donors.

CONCLUSION

The use of diet-treated donors for living-donor liver transplantation is feasible with respect to donor safety and the outcome of the recipient when strict selection criteria are used.

Quantification of hepatic macrosteatosis in living, related liver donors using T1-independent, T2*-corrected chemical shift MRI

PURPOSE

To evaluate the diagnostic implications of the iterative decomposition of water and fat using echo-asymmetry and the least-squares estimation (IDEAL) technique to detect hepatic steatosis (HS) in potential liver donors using histopathology as the reference standard.

MATERIALS AND METHODS

Forty-nine potential liver donors (32 male, 17 female; mean age, 31.7 years) were included. All patients were imaged using the in- and out-of-phase (IOP) gradient-echo (GRE) and IDEAL techniques on a 1.5 T MR scanner. To estimate the hepatic fat fraction (FF), two reviewers performed regions-of-interest measurement in 15 areas of the liver seen on the IOP images and on the IDEAL-FF images. The magnetic resonance imaging (MRI) and pathology values of macrosteatosis were correlated using the Pearson correlation coefficient. We analyzed the diagnostic performance of IOP imaging and IDEAL for detecting HS.

RESULTS

The results of the hepatic-FF estimated on IDEAL were well correlated with the histologic degree of macrosteatosis (γ = 0.902, P < 0.001). IDEAL showed 100% sensitivity and 91% specificity for detecting HS, and IOP imaging showed 87.5% sensitivity and 97% specificity, respectively.

CONCLUSION

IDEAL is a useful tool for the preoperative diagnosis of HS in potential living liver donors; it can also help to avoid unnecessary biopsies in these patients.

Functional Relationships between Lipid Metabolism and Liver Regeneration

The regenerative capacity of the liver is well known, and the mechanisms that regulate this process have been extensively studied using experimental model systems including surgical resection and hepatotoxin exposure. The response to primary mitogens has also been used to investigate the regulation of hepatocellular proliferation. Such analyses have identified many specific cytokines and growth factors, intracellular signaling events, and transcription factors that are regulated during and necessary for normal liver regeneration. Nevertheless, the nature and identities of the most proximal events that initiate hepatic regeneration as well as those distal signals that terminate this process remain unknown. Here, we review the data implicating acute alterations in lipid metabolism as important determinants of experimental liver regeneration and propose a novel metabolic model of regeneration based on these data. We also discuss the association between chronic hepatic steatosis and impaired regeneration in animal models and humans and consider important areas for future research.

Evaluation outcomes of donors in living donor liver transplantation: a single-center analysis of 132 donors

BACKGROUND

Donor safety has always been a major concern, and potential risk to the donor must be balanced against recipient benefit. However, lack of a standardized and uniform evaluation of perioperative complications is a serious limitation of the evaluation of donor morbidity. This study was designed to evaluate the outcomes of donors in adult living donor liver transplantation (LDLT) using the newer Clavien classification system in a single center in China.

METHODS

We prospectively analyzed the outcomes of 132 consecutive living liver donors from 2005 to 2008 using the newer Clavien classification system. The preoperative, intraoperative and postoperative data of the donors were collected and analyzed. Ordinal regression was used to analyze the ordered grades of complications.

RESULTS

Ninety-four (71.2%) of the donors developed postoperative complications of grade I (n=45, 34.1%), grade II (n=39, 29.5%) and grade III (n=10, 7.6%). There was no death or grade IV morbidity. Hepatic functional impairment and pleural effusion were the most frequent morbidities for living donors. Fifty-three donors (40.1%) developed hepatic functional impairment of grade I (n=40, 31.1%) and grade II (n=13, 10.0%). The ICU stay (7.8+/-1.8 days) and length of hospital stay (17.7+/-4.6 days) were significantly longer in donors with grade III than others. Furthermore, ordinal logistic regression revealed that donor's older age (>40 years) and right hepatectomy were associated with morbidity. In addition, only preoperative total bilirubin (within the normal range) and postoperative nadir serum phosphorus were independently associated with hepatic functional impairment. The receiver operator characteristic curve revealed that preoperative total bilirubin >18.0 μmol/L and postoperative nadir of serum phosphorus <1 mg/dL may lead to more severe hepatic functional impairment.

CONCLUSIONS

Despite the fact that donors are relatively safe to undergo hepatectomy, many living donors still experience postoperative morbidity. Meticulous technical and preoperative donor evaluation and treatment are sure to reduce the incidence of complications.

Post-hepatectomy haemorrhage: a definition and grading by the International Study Group of Liver Surgery (ISGLS)

BACKGROUND

A standardized definition of post-hepatectomy haemorrhage (PHH) has not yet been established.

METHODS

An international study group of hepatobiliary surgeons from high-volume centres was convened and a definition of PHH was developed together with a grading of severity considering the impact on patients' clinical management.

RESULTS

The definition of PHH varies strongly within the hepatic surgery literature. PHH is defined as a drop in haemoglobin level > 3 g/dl post-operatively compared with the post-operative baseline level and/or any post-operative transfusion of packed red blood cells (PRBC) for a falling haemoglobin and/or the need for radiological intervention (such as embolization) and/or re-laparotomy to stop bleeding. Evidence of intra-abdominal bleeding should be obtained by imaging or blood loss via the abdominal drains if present. Transfusion of up to two units of PRBC is considered as being Grade A PHH. Grade B PHH requires transfusion of more than two units of PRBC, whereas the need for invasive re-intervention such as embolization and/ or re-laparotomy defines Grade C PHH.

CONCLUSION

The proposed definition and grading of severity of PHH enables valid comparisons of results from different studies. It is easily applicable in clinical routine and should be applied in future trials to standardize reporting of complications.

Usefulness of Tc-99m-GSA scintigraphy for liver surgery

Postoperative mortality remains high after hepatectomy compared with other types of surgery in patients who have cirrhosis or chronic hepatitis. Although there are several useful perioperative indicators of liver dysfunction, no standard markers are available to predict postoperative liver failure in patients with hepatocellular carcinoma (HCC) undergoing hepatectomy. The best preoperative method for evaluating the hepatic functional reserve of patients with HCC remains unclear, but technetium-99m diethylenetriamine pentaacetic acid galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy is a candidate. (99m)Tc-GSA is a liver scintigraphy agent that binds to the asialoglycoprotein receptor, and can be used to assess the functional hepatocyte mass and thus determine the hepatic functional reserve in various physiological and pathological states. The maximum removal rate of (99m) Tc-GSA (GSA-Rmax) calculated by using a radiopharmacokinetic model is correlated with the severity of liver disease. There is also a significant difference of GSA-Rmax between patients with chronic hepatitis and persons with normal liver function. Regeneration of the remnant liver and recurrence of hepatitis C virus infection in the donor organ after living donor liver transplantation have also been investigated by (99m)Tc-GSA scintigraphy. This review discusses the usefulness of (99m)Tc-GSA scintigraphy for liver surgery.

Liver transplantation using fatty livers: always feasible?

Steatotic liver grafts represent the most common type of "extended criteria" organs that have been introduced during the last two decades due to the disparity between liver transplant candidates and the number available organs. A precise definition and reliable and reproducible method for steatosis quantification is currently lacking and the potential influence of the chemical composition of hepatic lipids has not been addressed. In our view, these shortcomings appear to contribute significantly to the inconsistent results of studies reporting on graft steatosis and the outcome of liver transplantation. In this review, various definitions, prevalence and methods of quantification of liver steatosis will be covered. Ischemia/reperfusion injury of the steatotic liver and its consequences on post-transplant outcome will be discussed. Selection criteria for organ allocation and a number of emerging protective strategies are suggested.

Hepatocyte proliferation during liver regeneration is impaired in mice with methionine diet-induced hyperhomocysteinemia

Elevated homocysteine levels are defined as hyperhomocysteinemia (HHcy), a disorder that is associated with cardiovascular and neurodegenerative diseases as well as with hepatic fibrosis. Recent studies have shown that HHcy promotes hepatic injury by increasing oxidative stress. Although homocysteine induces cell cycle arrest in a variety of different cell types, it is not known whether HHcy has a definitive role in hepatocyte proliferation during liver regeneration. In this report, we investigated the effect of homocysteine on liver regeneration. Our results demonstrated that mice with HHcy exhibited an impairment in liver regeneration after partial hepatectomy, as measured by immunohistochemical staining of proliferation cell nuclear antigen and bromodeoxyuridine incorporation. Impaired proliferation was also correlated with reduced cyclin D1 induction and elevated expression levels of both p53 and p21Cip1. In addition, the phosphorylation of Akt, which plays an essential role in normal regeneration responses, was attenuated during the early phases of liver regeneration in HHcy mice. Our results also indicated that the cAMP/protein kinase A pathway mediated the inhibitory effect of homocysteine on liver regeneration. These findings provide evidence that impairment of liver regeneration by HHcy may result in delayed recovery from liver injury induced by homocysteine itself.

Systematic review and meta-analysis of steatosis as a risk factor in major hepatic resection

Background

The risk of major hepatic resection in patients with hepatic steatosis remains controversial. A meta-analysis was performed to establish the best estimate of the impact of steatosis on patient outcome following major hepatic surgery.

Methods

A systematic search was performed following Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Risk ratios (RRs) for complication and mortality rates were calculated for patients with no, less than 30 per cent and at least 30 per cent steatosis, and a meta-analysis was carried out.

Results

Of six observational studies identified, four including a total of 1000 patients were subjected to meta-analysis; two others were tabulated separately. Compared with patients without steatosis, those with less than 30 per cent and at least 30 per cent steatosis had a significantly increased risk of postoperative complications, with a RR of 1·53 (95 per cent confidence interval (c.i.) 1·27 to 1·85) and 2·01 (1·66 to 2·44) respectively. Patients with at least 30 per cent steatosis had an increased risk of postoperative death (RR 2·79, 95 per cent c.i. 1·19 to 6·51).

Conclusion

Patients with steatosis had an up to twofold increased risk of postoperative complications, and those with excessive steatosis had an almost threefold increased risk of death.

Propranolol impairs liver regeneration after partial hepatectomy in C57Bl/6-mice by transient attenuation of hepatic lipid accumulation and increased apoptosis

OBJECTIVE

Acute hepatic fat accumulation appears to be crucial for liver regeneration after partial hepatectomy. Since fatty acids in the liver are provided by catecholamine-induced lipolysis in the adipose tissue, we investigated whether beta-adrenergic blockade of lipolysis might affect liver regeneration.

MATERIAL AND METHODS

Mice were treated with propranolol prior to partial hepatectomy. Subsequently, liver regeneration was evaluated histologically, by determination of the relative liver weight and the mitotic index at different time points after surgery.

RESULTS

Liver mass restoration was delayed by propranolol, which was associated with a lower hepatic triglyceride content. Ki-67 labelling indicated that liver regeneration was attenuated by propranolol through inhibition of mitosis. Hepatocytes were arrested in the G1 phase of the cell cycle, as shown by the expression of G1-related proteins such as proliferating cell nuclear antigen, cyclin D1 and cyclin-dependent kinase-2, and underwent apoptosis as indicated by detection of poly(adenosine diphosphate-ribose) polymerase fragments. beta-adrenergic blockade of the host animal did not provide transplanted hepatocytes with a growth advantage over host cells.

CONCLUSION

Impairment of liver regeneration by propranolol is related to the inhibition of acute hepatic fat accumulation and to a predisposition of hepatocytes to apoptosis.

MR spectroscopy of the liver: principles and clinical applications

Magnetic resonance (MR) spectroscopy allows the demonstration of relative tissue metabolite concentrations along a two- or three-dimensional spectrum based on the chemical shift phenomenon. An MR spectrum is a plot of the signal intensity and frequency of a chemical or metabolite within a given voxel. At proton MR spectroscopy, the frequency at which a chemical or compound occurs depends on the configuration of the protons within the structure of that chemical. At in vivo proton MR spectroscopy, the frequency location of water is used as the standard of reference to identify a chemical. The frequency shift or location of chemicals relative to that of water allows generation of qualitative and quantitative information about the chemicals that occur within tissues, forming the basis of tissue characterization by MR spectroscopy. MR spectroscopy also may be used to quantify liver fat by measuring lipid peaks and to diagnose malignancy, usually by measuring the choline peak. Interpretation of MR spectroscopic data requires specialized postprocessing software and is subject to technical limitations including low signal-to-noise ratio, masking of metabolite peaks by dominant water and lipid peaks, partial-volume averaging from other tissue within the voxel, and phase and frequency shifts from motion. MR spectroscopy of the liver is an evolving technology with potential for improving the diagnostic accuracy of tissue characterization when spectra are interpreted in conjunction with MR images.

Expansion of hepatic progenitor cell in fatty liver graft after living donor liver transplantation

Although it is known that steatotic livers have a reduced ability to regenerate, most individuals with steatosis show generally benign prognosis. We hypothesized that a proliferative blockade in steatotic hepatocytes results in the compensatory expansion of hepatic progenitor cells (HPC) during fatty liver regeneration. Fifty-four cases of living donor liver transplantation (LDLT) with a liver biopsy performed at the postoperative 10th day were examined. HPC were counted by immunofluorescence histochemical dual-staining technique using cytokeratin 7 and Ki-67, and the replicative arrest of hepatocytes was assessed by p21 immunohistochemistry. The degree of ductular proliferation during regeneration 10 days after LDLT correlated both with the degree of steatosis and the number of HPC (P < 0.001). There was no difference in the average number of HPC and the replicative arrest index between donors with or without steatosis before LDLT (P = 0.111 and P = 0.062). However, degree of steatosis correlated with both the expansion of HPC and the replicative arrest index during liver regeneration 10 days after LDLT (P < 0.001 and P < 0.001, respectively). Moreover, increased replicative arrest was strongly associated with HPC expansion (P < 0.001). In conclusion, the compensatory expansion of HPC as a result of impaired hepatocyte replication occurred during steatotic liver regeneration after LDLT.

Imaging-based quantification of hepatic fat: methods and clinical applications

Fatty liver disease comprises a spectrum of conditions (simple hepatic steatosis, steatohepatitis with inflammatory changes, and end-stage liver disease with fibrosis and cirrhosis). Hepatic steatosis is often associated with diabetes and obesity and may be secondary to alcohol and drug use, toxins, viral infections, and metabolic diseases. Detection and quantification of liver fat have many clinical applications, and early recognition is crucial to institute appropriate management and prevent progression. Histopathologic analysis is the reference standard to detect and quantify fat in the liver, but results are vulnerable to sampling error. Moreover, it can cause morbidity and complications and cannot be repeated often enough to monitor treatment response. Imaging can be repeated regularly and allows assessment of the entire liver, thus avoiding sampling error. Selection of appropriate imaging methods demands understanding of their advantages and limitations and the suitable clinical setting. Ultrasonography is effective for detecting moderate or severe fatty infiltration but is limited by lack of interobserver reliability and intraobserver reproducibility. Computed tomography allows quantitative and qualitative evaluation and is generally highly accurate and reliable; however, the results may be confounded by hepatic parenchymal changes due to cirrhosis or depositional diseases. Magnetic resonance (MR) imaging with appropriate sequences (eg, chemical shift techniques) has similarly high sensitivity, and MR spectroscopy provides unique advantages for some applications. However, both are expensive and too complex to be used to monitor steatosis.

Mild hepatic macrovesicular steatosis may be a risk factor for hyperbilirubinaemia in living liver donors following right hepatectomy

Background

The aim of this study was to evaluate the effects of mild macrovesicular steatosis on the outcome of living liver donors following right hepatectomy.

Methods

The medical records of 46 living liver donors who underwent right hepatectomy were studied. Ten donors had mild macrovesicular steatosis (5–10 per cent in seven and 11–20 per cent in three patients). Five donors with other liver pathology were excluded. Outcome in these ten donors (group 1) was compared with that in the remaining 31 donors with normal liver histology (group 2).

Results

The median duration until normalization of total bilirubin levels was 14 and 5 days in groups 1 and 2 respectively (P = 0·028). The peak total bilirubin level was significantly higher in group 1 than in group 2 (80·4 versus 49·6 µmol/l; P = 0·033). Multivariable analysis showed mild macrovesicular steatosis to be an independent risk factor for hyperbilirubinaemia (odds ratio 7·94 (95 per cent confidence interval 1·17 to 54·03); P = 0·034).

Conclusion

Mild macrovesicular steatosis may be related to adverse outcome in living liver donors who undergo right hepatectomy and, in terms of donor safety, is of potential concern in donor selection.

Proprotein convertase subtilisin/kexin type 9 (PCSK9): hepatocyte-specific low-density lipoprotein receptor degradation and critical role in mouse liver regeneration

The gene encoding the proprotein convertase subtilisin/kexin type 9 (PCSK9) is linked to familial hypercholesterolemia, as are those of the low-density lipoprotein receptor (LDLR) and apolipoprotein B. PCSK9 enhances LDLR degradation, resulting in low-density lipoprotein accumulation in plasma. To analyze the role of hepatic PCSK9, total and hepatocyte-specific knockout mice were generated. They exhibit 42% and 27% less circulating cholesterol, respectively, showing that liver PCSK9 was responsible for two thirds of the phenotype. We also demonstrated that, in liver, PCSK9 is exclusively expressed in hepatocytes, representing the main source of circulating PCSK9. The data suggest that local but not circulating PCSK9 regulates cholesterol levels. Although transgenic mice overexpressing high levels of liver and circulating PCSK9 led to the almost complete disappearance of the hepatic LDLR, they did not recapitulate the plasma cholesterol levels observed in LDLR-deficient mice. Single LDLR or double LDLR/PCSK9 knockout mice exhibited similar cholesterol profiles, indicating that PCSK9 regulates cholesterol homeostasis exclusively through the LDLR. Finally, the regenerating liver of PCSK9-deficient mice exhibited necrotic lesions, which were prevented by a high-cholesterol diet. However, lipid accumulation in hepatocytes of these mice was markedly reduced under both chow and high-cholesterol diets, revealing that PCSK9 deficiency confers resistance to liver steatosis.

CONCLUSION

Although PCSK9 is a target for controlling hypercholesterolemia, our data indicate that upon hepatic damage, patients lacking PCSK9 could be at risk.

Liver regeneration in donors evaluated by Tc-99m-GSA scintigraphy after living donor liver transplantation

The impact of hepatic steatosis on regeneration of the remnant liver after living donor liver transplantation is unclear. We evaluated the impact of steatosis on regeneration and function of the remnant liver by using technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin scintigraphy. Twelve living donors were classified into groups with or without mild hepatic steatosis according to the liver-to-spleen attenuation ratio on computed tomography: 6 donors had a ratio >or= 1.20 (control group) and 6 donors had a ratio < 1.20 (fatty liver group). Scintigraphy was performed to determine the hepatic uptake ratio of the tracer (corrected for disappearance from the blood) and the maximum removal rate of the tracer by hepatocytes as parameters of the hepatic functional reserve. The fatty liver group had a significantly lower corrected hepatic uptake ratio and removal rate compared with the control group at 6 and 12 months after partial hepatectomy. These parameters were decreased at 1 month after surgery in both groups. However, both parameters returned more rapidly to prehepatectomy levels in the control group. The regenerated liver volume estimated by scintigraphy did not differ significantly between the two groups at any time. Liver scintigraphy may be useful for evaluating the regeneration of functioning hepatocytes. Because donors with mild hepatic steatosis showed impaired liver regeneration at 1 year after partial hepatectomy, management of these donors requires more care.

An artificial vascular graft is a useful interpositional material for drainage of the right anterior section in living donor liver transplantation

Congestion in the anterior section in a right liver (RL) without a middle hepatic vein (MHV) may lead to graft dysfunction. To solve this problem, an RL draining MHV branches with autologous or cryopreserved vessels can be introduced. However, these vessels are often unavailable, and their preparation is time-consuming. An expanded polytetrafluoroethylene (ePTFE) graft may be used for anterior section drainage. Between February and November 2005, 26 recipients underwent RL liver transplantation draining MHV branches with an ePTFE graft (group P). Twenty-six ePTFE grafts (6 or 7 mm in internal diameter) drained 35 MHV branches on the back table to the graft right hepatic vein or to the recipient's inferior vena cava. The patency of the ePTFE graft was checked with computed tomography scans of the liver. The outcome of group P was compared with those of an RL group with MHV (group M, n=17) and an RL group without reconstruction of MHV or its tributaries (group R, n=85). The 1-month and 4-month patency rates (PRs) of the ePTFE grafts were 80.8% (21/26) and 38.5% (10/26). All showing early obstruction of the ePTFE graft had congestion in the anterior section, but all showing late obstruction were asymptomatic. The 1-month PRs of group P were comparable to, but the 4-month PRs were lower than, those of group M (both 94.1%; P<0.05). However, 1-year patient and graft survival rates of group P (both 100%) were comparable to those of group M (94.1% and 100%) and better than those of group R (83.5% and 88.2%; P<0.05). In conclusion, the early PR of group P was good, and late obstruction of the ePTFE graft had no impact on congestion in the anterior section or patient survival. Therefore, an ePTFE graft may be a useful interposition material for anterior section drainage in RL transplantation without serious complications.