Pharmacological Activation of Nrf2 Enhances Functional Liver Regeneration.

BACKGROUND AND AIMS: The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) regulates an array of cytoprotective genes, yet studies in transgenic mice have led to conflicting reports on its role in liver regeneration. We aimed to test the hypothesis that pharmacological activation of Nrf2 would enhance liver regeneration. APPROACH AND RESULTS: Wild-type and Nrf2 null mice were administered bardoxolone methyl (CDDO-Me), a potent activator of Nrf2 that has entered clinical development, and then subjected to two-thirds partial hepatectomy. Using translational noninvasive imaging techniques, CDDO-Me was shown to enhance the rate of restoration of liver volume (MRI) and improve liver function (multispectral optoacoustic imaging of indocyanine green clearance) in wild-type, but not Nrf2 null, mice following partial hepatectomy. Using immunofluorescence imaging and whole transcriptome analysis, these effects were found to be associated with an increase in hepatocyte hypertrophy and proliferation, the suppression of immune and inflammatory signals, and metabolic adaptation in the remnant liver tissue. Similar processes were modulated following exposure of primary human hepatocytes to CDDO-Me, highlighting the potential relevance of our findings to patients. CONCLUSIONS: Our results indicate that pharmacological activation of Nrf2 is a promising strategy for enhancing functional liver regeneration. Such an approach could therefore aid the recovery of patients undergoing liver surgery and support the treatment of acute and chronic liver disease.

Primary Tumor Resection is Associated with Improved Disease-Specific Mortality in Patients with Stage IV Small Intestinal Neuroendocrine Tumors (NETs): A Comparison of Upfront Surgical Resection Versus a Watch and Wait Strategy in Two Specialist NET Centers.

INTRODUCTION: Small intestinal neuroendocrine tumors (SI-NETs) often present with metastatic disease. An ongoing debate exists on whether to perform primary tumor resection (PTR) in patients with stage IV SI-NETs, without symptoms of the primary tumor and inoperable metastatic disease. OBJECTIVE: The aim of this study was to compare a treatment strategy of upfront surgical resection versus a surveillance strategy of watch and wait. METHODS: This was a retrospective cohort study of patients with stage IV SI-NETs at diagnosis, between 2000 and 2018, from two tertiary referral centers (Netherlands Cancer Institute [NKI] and Aintree University Hospital [AUH]) who had adopted contrasting treatment approaches: upfront surgical resection and watch and wait, respectively. Patients without symptoms related to the primary tumor were included. Multivariable intention-to-treat (ITT), per-protocol (PP), and instrumental variable (IV) analyses using 'institute' as an IV were performed to assess the influence of PTR on disease-specific mortality (DSM). RESULTS: A total of 557 patients were identified, with 145 patients remaining after exclusion of stage I-III disease or symptoms of the primary tumor (93 from the NKI and 52 from AUH). The cohorts differed in performance status (PS; p = 0.006) and tumor grade (p < 0.001). PTR was independently associated with reduced DSM irrespective of statistical methods employed: ITT hazard ratio [HR] 0.60, p = 0.005; PP HR 0.58, p < 0.001; and IV HR 0.07, p = 0.019. Other factors associated with DSM were age, PS, high chromogranin A, and somatostatin analog treatment. CONCLUSION: Taking advantage of contrasting institutional treatment strategies, this study identified PTR as an independent predictor of DSM. Future prospective studies should aim to validate these results.

Surgical management of suspected gallbladder cancer: The role of intraoperative frozen section for diagnostic confirmation.

BACKGROUND: Preoperative diagnosis for suspected gallbladder cancers is challenging, with a risk of overtreating benign disease, for example, xanthogranulomatous cholecystitis, with radical cholecystectomies. We retrospectively evaluated the surgeon's intraoperative assessment alone, and with the addition of intraoperative frozen sections, for suspected gallbladder cancers from a tertiary hepatobiliary multidisciplinary team (MDT). METHODS: MDT patients with complex gallbladder disease were included. Collated data included demographics, MDT discussion, operative details, and patient outcomes. RESULTS: A total of 454 patients with complex gallbladder disease were reviewed, 48 (10.6%) were offered radical surgery for suspected cancer. Twenty-five underwent frozen section that led to radical surgery in 6 (25%). All frozen sections were congruent with final histopathology but doubled the operating time (p < 0.0001). Both the surgeon's subjective and additional frozen section's objective assessment, allowed for de-escalation of unnecessary radical surgery, comparing favourably to a 13.0% cancer diagnosis among radical surgery historically. CONCLUSIONS: The MDT process was highly sensitive in identifying gallbladder cancers but lacked specificity. The surgeon's intraoperative assessment is paramount in suspected cancers, and deescalated unnecessary radical surgery. Intraoperative frozen section was a safe and viable adjunct at a cost of resources and operative time.

Prognosis and Circumferential Margin in Patients with Resected Hilar Cholangiocarcinoma.

BACKGROUND: Resection margin status is a known prognosticator in patients who undergo resection for hilar cholangiocarcinoma. However, the influence of an isolated positive circumferential margin on clinical outcome is unclear. METHODS: Patients with resected de novo hilar cholangiocarcinoma from two European hepatobiliary centres (Medical University of Vienna and Aintree University Hospital, 2006-2016) were classified according to resection margin status (negative, surgically positive, isolated circumferentially positive) and investigated with respect to overall survival (OS), recurrence-free survival (RFS) and recurrence pattern. RESULTS: Eighty-three (48 male/35 female) patients were enrolled. The median age was 64 years (range 33-80). The median follow-up was 21.7 months (range 0.3-92.4). Forty (48%) patients had negative resection margins, 25 (30%) had an isolated positive circumferential margin and 18 (22%) had a positive surgical margin. The 5-year OS rates in patients with negative, isolated positive circumferential and positive surgical resection margins were 47%, 33% and 0%, respectively. Median OS was 45.6, 32.7 and 14.5 months, respectively (log rank, P = 0.011). Upon multivariable Cox regression analysis, resection margin status and lymph node status remained statistically significant (P < 0.05). No difference with respect to RFS and recurrence pattern was found between the groups (P > 0.05). CONCLUSION: Our data show that these three resection margin types were associated with different clinical outcomes. Circumferential margin status may therefore serve as a novel prognostic biomarker.

Preoperative Leucocyte-Based Inflammatory Scores in Patients with Colorectal Liver Metastases: Can We Count on Them?

BACKGROUND: Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and lymphocyte-to-monocyte ratio (LMR) have been identified as potential prognostic factors for overall survival (OS) in primary colorectal cancer, and there is a growing interest in their use in colorectal liver metastases (CLMs). However, optimal cut-off values for these ratios have not been defined by making comparison between series difficult. This study aimed to confirm the prognostic value of inflammatory scores in patients undergoing resection for CLM. METHODS: We retrospectively analysed data from 376 consecutive patients who underwent liver surgery for CLM between June 2010 and August 2015. We assessed the reproducibility of previously published ratios and determined new cut-off values using the Cut-off Finder web-based tool. Relations between cut-off values and OS were analysed with Kaplan-Meier log-rank survival analysis and multivariate Cox models. RESULTS: Three hundred and forty-three patients had full preoperative blood tests for calculation of NLR, PLR and LMR. The number of cut-off values which showed a significant discrimination for OS was 49/249 (19.7%) for NLR, 28/316 (8.9%) for PLR and 22/214 (10.3%) for LMR, all with a scattered nonlinear distribution. CONCLUSIONS: This study showed that inflammatory scores expressed as ratios do not seem to be consistently reliable prognostic markers in patients with resectable CLM.

Characterisation of the NRF2 transcriptional network and its response to chemical insult in primary human hepatocytes: implications for prediction of drug-induced liver injury.

The transcription factor NRF2, governed by its repressor KEAP1, protects cells against oxidative stress. There is interest in modelling the NRF2 response to improve the prediction of clinical toxicities such as drug-induced liver injury (DILI). However, very little is known about the makeup of the NRF2 transcriptional network and its response to chemical perturbation in primary human hepatocytes (PHH), which are often used as a translational model for investigating DILI. Here, microarray analysis identified 108 transcripts (including several putative novel NRF2-regulated genes) that were both downregulated by siRNA targeting NRF2 and upregulated by siRNA targeting KEAP1 in PHH. Applying weighted gene co-expression network analysis (WGCNA) to transcriptomic data from the Open TG-GATES toxicogenomics repository (representing PHH exposed to 158 compounds) revealed four co-expressed gene sets or 'modules' enriched for these and other NRF2-associated genes. By classifying the 158 TG-GATES compounds based on published evidence, and employing the four modules as network perturbation metrics, we found that the activation of NRF2 is a very good indicator of the intrinsic biochemical reactivity of a compound (i.e. its propensity to cause direct chemical stress), with relatively high sensitivity, specificity, accuracy and positive/negative predictive values. We also found that NRF2 activation has lower sensitivity for the prediction of clinical DILI risk, although relatively high specificity and positive predictive values indicate that false positive detection rates are likely to be low in this setting. Underpinned by our comprehensive analysis, activation of the NRF2 network is one of several mechanism-based components that can be incorporated into holistic systems toxicology models to improve mechanistic understanding and preclinical prediction of DILI in man.

Critical research gaps and recommendations to inform research prioritisation for more effective prevention and improved outcomes in colorectal cancer.

OBJECTIVE: Colorectal cancer (CRC) leads to significant morbidity/mortality worldwide. Defining critical research gaps (RG), their prioritisation and resolution, could improve patient outcomes. DESIGN: RG analysis was conducted by a multidisciplinary panel of patients, clinicians and researchers (n=71). Eight working groups (WG) were constituted: discovery science; risk; prevention; early diagnosis and screening; pathology; curative treatment; stage IV disease; and living with and beyond CRC. A series of discussions led to development of draft papers by each WG, which were evaluated by a 20-strong patient panel. A final list of RGs and research recommendations (RR) was endorsed by all participants. RESULTS: Fifteen critical RGs are summarised below: RG1: Lack of realistic models that recapitulate tumour/tumour micro/macroenvironment; RG2: Insufficient evidence on precise contributions of genetic/environmental/lifestyle factors to CRC risk; RG3: Pressing need for prevention trials; RG4: Lack of integration of different prevention approaches; RG5: Lack of optimal strategies for CRC screening; RG6: Lack of effective triage systems for invasive investigations; RG7: Imprecise pathological assessment of CRC; RG8: Lack of qualified personnel in genomics, data sciences and digital pathology; RG9: Inadequate assessment/communication of risk, benefit and uncertainty of treatment choices; RG10: Need for novel technologies/interventions to improve curative outcomes; RG11: Lack of approaches that recognise molecular interplay between metastasising tumours and their microenvironment; RG12: Lack of reliable biomarkers to guide stage IV treatment; RG13: Need to increase understanding of health related quality of life (HRQOL) and promote residual symptom resolution; RG14: Lack of coordination of CRC research/funding; RG15: Lack of effective communication between relevant stakeholders. CONCLUSION: Prioritising research activity and funding could have a significant impact on reducing CRC disease burden over the next 5 years.

Validation of clinical prognostic scores for patients treated with curative-intent for recurrent colorectal liver metastases.

BACKGROUND: Scoring systems were developed to stratify patients with colorectal liver metastases considered for liver resection into different risk groups. Such scores have never been evaluated in recurrent liver metastases. The aim of this study was to evaluate whether these scores are applicable to patients with recurrent colorectal liver metastases and treated with curative intent. METHODS: We retrospectively analyzed data from 375 consecutive patients who underwent liver surgery for colorectal liver metastases between June 2010 and August 2015. Seventy-three patients developed liver-limited recurrence treated with curative intent. The predictive value of 6 scores (Fong, Sofocleous, Nagashima, Nordlinger, Konopke, and the Basingstoke index) was assessed in this set of patients. RESULTS: Median follow-up was 36.2 months. Overall survival and progression-free survival were 33.6 and 5.6 months, respectively. When scores were applied for OS, none showed a significant stratification between patients, although Nagashima's score showed a significant difference in overall survival between patients from the low-risk group and those from the intermediate- and high-risk groups (40.8 vs 30.5 months, P = 0.039). For PFS, only Fong's score showed a statistically significant stratification (6.6 vs 4.7 months, P = 0.027). CONCLUSION: Scoring systems are of limited-value in stratifying patients operated on for recurrent colorectal liver metastases.

Phenotypic and functional analyses show stem cell-derived hepatocyte-like cells better mimic fetal rather than adult hepatocytes.

BACKGROUND & AIMS: Hepatocyte-like cells (HLCs), differentiated from pluripotent stem cells by the use of soluble factors, can model human liver function and toxicity. However, at present HLC maturity and whether any deficit represents a true fetal state or aberrant differentiation is unclear and compounded by comparison to potentially deteriorated adult hepatocytes. Therefore, we generated HLCs from multiple lineages, using two different protocols, for direct comparison with fresh fetal and adult hepatocytes. METHODS: Protocols were developed for robust differentiation. Multiple transcript, protein and functional analyses compared HLCs to fresh human fetal and adult hepatocytes. RESULTS: HLCs were comparable to those of other laboratories by multiple parameters. Transcriptional changes during differentiation mimicked human embryogenesis and showed more similarity to pericentral than periportal hepatocytes. Unbiased proteomics demonstrated greater proximity to liver than 30 other human organs or tissues. However, by comparison to fresh material, HLC maturity was proven by transcript, protein and function to be fetal-like and short of the adult phenotype. The expression of 81% phase 1 enzymes in HLCs was significantly upregulated and half were statistically not different from fetal hepatocytes. HLCs secreted albumin and metabolized testosterone (CYP3A) and dextrorphan (CYP2D6) like fetal hepatocytes. In seven bespoke tests, devised by principal components analysis to distinguish fetal from adult hepatocytes, HLCs from two different source laboratories consistently demonstrated fetal characteristics. CONCLUSIONS: HLCs from different sources are broadly comparable with unbiased proteomic evidence for faithful differentiation down the liver lineage. This current phenotype mimics human fetal rather than adult hepatocytes.

Evolution of surgical microwave ablation for the treatment of colorectal cancer liver metastasis: review of the literature and a single centre experience.

Surgical resection is the gold standard treatment for colorectal liver metastasis, with reported five-year survival rates of 40 %. Unfortunately, despite progress in systemic therapies and surgical techniques, only 20-30 % of patients can be offered this potentially curative treatment modality. Ablative therapies have recently been suggested to treat unresectable lesions or to extend the margins of resectability. Additionally, cases of local recurrence after hepatic surgery might require alternative strategies and options for re-intervention. Microwave ablation (MWA) has recently become a matter of particular interest for such indications. We, herein, present a review of the literature published between January 1999 and June 2013 from a database search with the following keywords: microwave, ablation, liver metastases, colorectal neoplasm, resection, hepatectomy, colonic neoplasm, cancer. Furthermore, we provide insight based on our own data for 28 consecutive patients who underwent hepatic resection combined with MWA from 2005 to 2012 in a single centre.

Cardiopulmonary exercise testing before liver surgery.

BACKGROUND: Cardiopulmonary exercise testing (CPET) assessed "poorer" fitness correlates with poorer outcomes in blinded studies. Whether this correlation will persist when CPET is utilized to stratify care as part of a multi-modal enhanced recovery after surgery (ERAS) program is unclear. This study examined whether CPET variables were associated with postoperative morbidity in patients undergoing hepatectomy within an ERAS program. OBJECTIVES AND METHODS: Data were prospectively collected on patients undergoing elective hepatectomy between October 2009 and April 2011. The relationships between CPET derived variables; postoperative complications and length of stay were investigated. RESULTS: Of 267 patients undergoing surgery, 197 had undergone standard cycle ergometer CPET. The relative oxygen uptake [VO2 (ml kg(-1) min(-1))] and ventilatory equivalent of CO2 (VE/VCO2) at the anaerobic threshold (AT) were not associated with complications or length of stay. Greater absolute oxygen uptake at AT [VO2 at AT (L min(-1) )] was associated with early hospital discharge [OR 2.16 (95% CI 1.18-3.96), P = 0.013] on multivariable analysis. CONCLUSIONS: When CPET is used to delineate perioperative management a low relative oxygen uptake [VO2 (ml kg(-1) min(-1) )] at the AT does not place patients at significantly higher risk of postoperative complications. This suggests CPET assessed "poor" fitness should not be used as a barrier to surgical intervention.

Enhanced recovery in the resection of colorectal liver metastases.

BACKGROUND: There is limited evidence for the use of enhanced recovery after surgery (ERAS) in patients undergoing hepatectomy, and the impact of the evolution of ERAS over time has not been examined. This study sought to evaluate the effect of an evolving ERAS program in patients undergoing hepatectomy for colorectal liver metastases (CRLM). METHODS: A multimodal ERAS program was introduced in 2/2008. Consecutive patients undergoing hepatectomy for CRLM between 2/2008 and 9/2012 were included in the study. Data were collected prospectively. Retrospective analysis compared an early ERAS cohort (2/2008-4/2010) with a later cohort with a matured ERAS program (5/2010-8/2012). RESULTS: Length of stay reduced as experience of ERAS increased (Log-rank χ(2) = 10.43, P = 0.001). Although median length of stay remained unchanged (6 days), the probability of hospitalization beyond 10 days was 25% in the early cohort compared with 7% in the later cohort. Critical care utilization reduced over time (75.5% vs. 54.7%, P < 0.0001). Complications occurred in 38.2%, with no difference in between cohorts. One postoperative death occurred in the early cohort (<0.3%). CONCLUSIONS: This study suggests that as experience of ERAS evolves, there is a progressive reduction in hospitalization and critical care admission. This is without any increase in morbidity and mortality.

Liver resection with concomitant inferior vena cava resection: experiences without veno-venous bypass.

PURPOSE: Liver resection offers the chance of a cure for liver cancer. However, when extended hepatectomies were performed in combination with resection of the inferior vena cava (IVC), the procedures were reported to have a surgical mortality rate in excess of 5 %. While most of these operations were performed with the use of veno-venous bypass, this study presents our experience performing the procedure without the bypass. METHODS: Data were collected from a prospectively maintained database. A retrospective evaluation of a consecutive series of concomitant IVC and liver resections was performed. RESULTS: Five hundred and seventy-five liver resections were performed between June 2008 and November 2011. Eleven patients (1.9 %) underwent concomitant IVC and liver resections. One patient required segmental IVC replacement, and four IVC defects were closed using a bovine pericardial patch without bypass. Only one patient had histologically confirmed IVC invasion. There was no postoperative mortality. Nine postoperative complications occurred in five patients. No complications in terms of IVC patency were seen. Five patients had disease recurrence, one of whom died within 12 months of surgery. CONCLUSION: Concomitant liver and IVC resection is safe without using a bypass procedure, with acceptable short-term results. Meticulous technique, careful patient selection and a specialized anesthetic team are key to obtaining low postoperative morbidity and mortality rates and an acceptable oncological outcome.

Management of incidental and suspicious gallbladder cancer: focus on early referral to a tertiary centre.

OBJECTIVES: This study was conducted to assess the management of incidental gallbladder cancer and indeterminate gallbladder lesions. Its secondary aim referred to the devising of a management pathway for these patients. METHODS: Patients referred with incidental gallbladder cancer and indeterminate gallbladder lesions during 2002-2011 were identified from a prospectively maintained database. Collated data included operative findings, histopathological data and survival outcomes. RESULTS: The study included a total of 104 patients, 40 of whom had incidental gallbladder cancer following cholecystectomy. In this group, the index cholecystectomy was considered curative (T-is/T1a stage) in three patients; 11 patients underwent further resection, and 26 patients were inoperable. One-, 3- and 5-year overall survival rates were 91.1%, 91.0% and 60.7%, respectively, in patients who underwent re-resection. Of the 64 patients with indeterminate gallbladder lesions, 54 patients underwent modified radical cholecystectomy. Seven patients were found to have gallbladder cancer. One-, 3- and 5-year overall survival rates were 85.9%, 43.1% and 42.8%, respectively. Five-year overall survival in patients treated with surgery for gallbladder cancer was 59.9%. CONCLUSIONS: The majority of patients with incidental gallbladder cancer were not amenable to further potentially curative resection. The radiological suspicion of gallbladder cancer should lead to prompt referral to a tertiary hepatobiliary unit for further management.

Stage IV colorectal cancer: outcomes following the liver-first approach.

BACKGROUND: To date, there is limited data on the liver-first approach in the management of colorectal liver metastases (CRLM). The aim of the study was to assess the outcomes of the liver-first approach for patients with synchronous CRLM in two tertiary referral centers. METHODS: Patients with stage IV colorectal cancer selected for the liver-first approach from January 2009 to December 2012 in two tertiary referral centers were included. Data collated included demographics, chemotherapy, operative findings, histo-pathological features, and survival. RESULTS: Thirty-seven patients with synchronous CRLM were considered for the liver-first approach. Twenty-five patients had rectal cancer. All patients underwent induction chemotherapy. Thirty patients underwent hepatic resections with no post-operative deaths. Following liver resection, five patients failed to proceed to colorectal resection and one patient had complete response to chemo-radiotherapy. Of the 25 patients that completed the liver-first approach, 13 patients had recurrent disease, of which 12 patients died. The overall 1- and 3-year survival rates were 65.9% and 30.4%, respectively. CONCLUSION: The liver-first approach is a feasible strategy for patients with synchronous CRLM and may improve survival in selected patients. The selection of patients should be incorporated in a multidisciplinary approach to achieve the best possible outcomes.

Metal stents: a bridge to surgery in hilar cholangiocarcinoma.

BACKGROUND: Obstructive jaundice in patients with hilar cholangiocarcinoma is a known risk factor for hepatic failure after liver resection. Plastic stents are most widely used for preoperative drainage. However, plastic stents are known to have limited patency time and therefore, in palliative settings, the self-expanding metal stent (SEMS) is used. This type of stent has been shown to be superior because it allows for rapid biliary decompression and a reduced complication rate after insertion. This study explores the use of the SEMS for biliary decompression in patients with operable hilar cholangiocarcinoma. METHODS: A retrospective evaluation of a prospectively maintained database at a tertiary hepatobiliary referral centre was carried out. All patients with resectable cholangiocarcinoma were recorded. RESULTS: Of 260 patients referred to this unit with cholangiocarcinoma between January 2008 and April 2012, 50 patients presented with operable cholangiocarcinoma and 27 of these had obstructive jaundice requiring stenting. Ten patients were initially treated with SEMSs; no stent failure occurred in these patients. Seventeen patients initially received plastic stents, seven of which failed in the interval between stent placement and laparotomy. These stents were replaced by SEMSs in four patients and by plastic stents in three patients. Median time to laparotomy was 45 days and 68 days in patients with SEMSs and plastic stents, respectively. CONCLUSIONS: Self-expanding metal stents provide adequate and rapid biliary drainage in patients with obstruction caused by hilar cholangiocarcinoma. No re-interventions were required. This probably reflects the relatively short interval between stent placement and laparotomy.

Segmental and lobar administration of drug-eluting beads delivering irinotecan leads to tumour destruction: a case-control series.

BACKGROUND: Irinotecan-loaded drug-eluting beads represent a novel drug delivery method that allows for the locoregional delivery of irinotecan to colorectal liver metastases (CRLM). The method has shown impressive response rates. However, the pathological response to this treatment has not previously been demonstrated. METHODS: Patients with easily resectable CRLM were treated with drug-eluting beads delivering irinotecan (DEBIRI) 4 weeks prior to resection. Pathological tumour response was graded using a validated system. The intraoperative detection of previously unidentified disease allowed for the assessment of pathological responses directly attributable to bead treatment. RESULTS: In Patient 1, segmental embolization of the target lesion in segment VIII resulted in 100% necrosis (0% viability). An untreated lesion in segment IV was found to be 30% viable. In Patient 2, subsegmental embolization of the target lesion in segment VI resulted in 60% necrosis and 40% fibrosis (0% viability). An untreated lesion in segment VI remained 60% viable. In Patient 3, lobar embolization of the target lesion in segment II resulted in 0% viability. Two further lesions within the treated hemiliver, both with 0% viability, and one lesion in the untreated hemiliver with 45% viability were discovered at laparotomy. CONCLUSIONS: This series demonstrates the effectiveness of DEBIRI in the treatment of CRLM. High rates of tumour destruction are possible, even with the proximal lobar administration of DEBIRI. Lobar administration appears to be an appropriate method of delivery for integration into future therapeutic regimens.

A systems approach reveals species differences in hepatic stress response capacity.

To minimize the occurrence of unexpected toxicities in early phase preclinical studies of new drugs, it is vital to understand fundamental similarities and differences between preclinical species and humans. Species differences in sensitivity to acetaminophen (APAP) liver injury have been related to differences in the fraction of the drug that is bioactivated to the reactive metabolite N-acetyl-p-benzoquinoneimine (NAPQI). We have used physiologically based pharmacokinetic modeling to identify oral doses of APAP (300 and 1000 mg/kg in mice and rats, respectively) yielding similar hepatic burdens of NAPQI to enable the comparison of temporal liver tissue responses under conditions of equivalent chemical insult. Despite pharmacokinetic and biochemical verification of the equivalent NAPQI insult, serum biomarker and tissue histopathology analyses revealed that mice still exhibited a greater degree of liver injury than rats. Transcriptomic and proteomic analyses highlighted the stronger activation of stress response pathways (including the Nrf2 oxidative stress response and autophagy) in the livers of rats, indicative of a more robust transcriptional adaptation to the equivalent insult. Components of these pathways were also found to be expressed at a higher basal level in the livers of rats compared with both mice and humans. Our findings exemplify a systems approach to understanding differential species sensitivity to hepatotoxicity. Multiomics analysis indicated that rats possess a greater basal and adaptive capacity for hepatic stress responses than mice and humans, with important implications for species selection and human translation in the safety testing of new drug candidates associated with reactive metabolite formation.

Microwave ablation of ex vivo human liver and colorectal liver metastases with a novel 14.5 GHz generator.

PURPOSE: This study assessed the relationship between time, power and ablation size using a novel high-frequency 14.5 GHz microwave applicator in ex vivo human hepatic parenchyma and colorectal liver metastases. Previous examination has demonstrated structurally normal but non-viable cells within the ablation zone. This study aimed to further investigate how ablation affects these cells, and to confirm non-viability. MATERIALS AND METHODS: Ablations were performed in ex vivo human hepatic parenchyma and tumour for a variety of time (10-180 s) and power (10-50 W) settings. Histological examination was performed to assess cellular anatomy, whilst enzyme histochemistry was used to confirm cellular non-viability. Transmission electron microscopy was used to investigate the subcellular structural effects of ablation within these fixed cells. Preliminary proteomic analysis was also performed to explore the mechanism of microwave cell death. RESULTS: Increasing time and power settings led to a predictable and reproducible increase in size of ablation. At 50 W and 180 s application, a maximum ablation diameter of 38.8 mm (±1.3) was produced. Ablations were produced rapidly, and at all time and power settings ablations remained spherical (longest:shortest diameter <1.2). Routine histological analysis using haematoxylin-eosin (H&E) confirmed well preserved cellular anatomy despite ablation. Transmission electron microscopy demonstrated marked subcellular damage. Enzyme histochemistry showed complete absence of viability in ablated tissue. CONCLUSIONS: Large spherical ablation zones can be rapidly and reproducibly achieved in ex vivo human hepatic parenchyma and colorectal liver metastases using a 14.5 GHz microwave generator. Despite well preserved cellular appearance, ablated tissue is non-viable.