Study of liver ischaemia-reperfusion injury and its modulation by N-acetylcysteine.

Liver ischaemia-reperfusion (I/R) injury occurs in a number of clinical settings, including liver surgery, transplantation and haemorrhagic shock with subsequent fluid resuscitation. It is well recognised as a significant cause of morbidity and mortality and characterised by oxidative stress accompanied with depletion of antioxidants. Its pathophysiology is complex. This thesis investigates the effect of lobar liver I/R injury on liver microcirculation, hepatic oxygenation, cellular energetics and nitric oxide (NO) metabolism. It evaluates also the hypothesis that the antioxidant N-acetylcysteine (NAC) ameliorates liver I/R injury. Initially an experimental rabbit model was established where both phases (early and late) of liver I/R injury could be studied. New Zealand white rabbits underwent 60 min of lobar ischaemia followed by 7 h of reperfusion. It was found that cannulation of the femoral artery, for monitoring of the arterial blood pressure, induced remote liver injury, which could be avoided by use of the ear artery. Lobar liver I/R caused significant decrease in hepatic microcirculation, liver tissue oxygenation and cellular energetics. It also caused significant alterations in NO metabolism during the late phase (increase in plasma nitrites and plasma S-nitrosothiols, decrease in liver tissue nitrotyrosine) and significant oxidative stress. Intravenous administration of NAC (150 mg/Kg/h over the 15 min before reperfusion and maintenance at 10 mg /Kg/h during the 7 h reperfusion period) had a clear protective effect during the late phase of reperfusion injury in rabbits with normal and steatotic liver. This effect was associated with improved cellular energy metabolism (maintenance of cytochrome oxidase activity, increased acetates and decreased lactates in bile) and altered NO metabolism (reduced plasma nitrites, S-nitrosothiols and reactive nitrogen species). In conclusion, this thesis has shown that lobar hepatic I/R induces significant alterations on cellular energetics and NO metabolism. It provides also significant new information about the timing and the possible mechanism of the protective effect of NAC. It could form the basis for the performance of large scale prospective randomised clinical trials where the effect of thiols in clinical settings of liver I/R injury will be investigated

Surgical Therapy of Hepatocellular Carcinoma: State of the Art Liver Resection

Hepatocellular carcinoma (HCC) represents the third most common cause of cancer-related death, showing incremental growth rates throughout the last decades. HCC requires multidisciplinary approach in a group of patients suffering from underlying chronic liver disease, usually in the setting of cirrhosis. The mainstay of treatment in resectable cases is surgery, with anatomic and non-anatomic liver resections widely implemented, as well as liver transplantation in well-selected individuals. Nowadays, there is a variety of liver parenchyma transection devices used by hepatobiliary surgeons in specialized centers, which has significantly improved postoperative outcomes in HCC patients. Therefore, hepatectomy is considered safe and feasible and should be the main therapeutic option for HCC patients, candidates for resection. Liver resection utilizing cavitron ultrasonic aspirator in combination with bipolar radiofrequency ablation is safe and effective for the treatment of HCC with favorable clinical and oncological outcomes

Metabolomic Determinants of Metabolic Risk in Mexican Adolescents

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138425/1/oby21926.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138425/2/oby21926_am.pd

Nitrosative and Oxidative Stresses Contribute to Post-Ischemic Liver Injury Following Severe Hemorrhagic Shock: The Role of Hypoxemic Resuscitation

Purpose: Hemorrhagic shock and resuscitation is frequently associated with liver ischemia-reperfusion injury. The aim of the study was to investigate whether hypoxemic resuscitation attenuates liver injury. Methods: Anesthetized, mechanically ventilated New Zealand white rabbits were exsanguinated to a mean arterial pressure of 30 mmHg for 60 minutes. Resuscitation under normoxemia (Normox-Res group, n = 16, PaO2 = 95–105 mmHg) or hypoxemia (Hypox-Res group, n = 15, PaO 2 = 35–40 mmHg) followed, modifying the FiO 2. Animals not subjected to shock constituted the sham group (n = 11, PaO 2 = 95–105 mmHg). Indices of the inflammatory, oxidative and nitrosative response were measured and histopathological and immunohistochemical studies of the liver were performed. Results: Normox-Res group animals exhibited increased serum alanine aminotransferase, tumor necrosis factor- alpha, interleukin (IL)-1b and IL-6 levels compared with Hypox-Res and sham groups. Reactive oxygen species generation, malondialdehyde formation and myeloperoxidase activity were all elevated in Normox-Res rabbits compared with Hypox-Res and sham groups. Similarly, endothelial NO synthase and inducible NO synthase mRNA expression was up-regulated and nitrotyrosine immunostaining increased in animals resuscitated normoxemically, indicating a more intense nitrosative stress. Hypox-Res animals demonstrated a less prominent histopathologic injury which was similar to sham animals. Conclusions: Hypoxemic resuscitation prevents liver reperfusion injury through attenuation of the inflammatory respons

High plasma uric acid concentration: causes and consequences

High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with the de novo synthesis of purine, accelerating UA production. The role played by diet on hyperuricemia has not yet been fully clarified, but high intake of fructose-rich industrialized food and high alcohol intake (particularly beer) seem to influence uricemia. It is not known whether UA would be a causal factor or an antioxidant protective response. Most authors do not consider the UA as a risk factor, but presenting antioxidant function. UA contributes to > 50% of the antioxidant capacity of the blood. There is still no consensus if UA is a protective or a risk factor, however, it seems that acute elevation is a protective factor, whereas chronic elevation a risk for disease

A20 Modulates Lipid Metabolism and Energy Production to Promote Liver Regeneration

Background: Liver Regeneration is clinically of major importance in the setting of liver injury, resection or transplantation. We have demonstrated that the NF-$\kappa$B inhibitory protein A20 significantly improves recovery of liver function and mass following extended liver resection (LR) in mice. In this study, we explored the Systems Biology modulated by A20 following extended LR in mice. Methodology and Principal Findings: We performed transcriptional profiling using Affymetrix-Mouse 430.2 arrays on liver mRNA retrieved from recombinant adenovirus A20 (rAd.A20) and rAd.$\beta$galactosidase treated livers, before and 24 hours after 78% LR. A20 overexpression impacted 1595 genes that were enriched for biological processes related to inflammatory and immune responses, cellular proliferation, energy production, oxidoreductase activity, and lipid and fatty acid metabolism. These pathways were modulated by A20 in a manner that favored decreased inflammation, heightened proliferation, and optimized metabolic control and energy production. Promoter analysis identified several transcriptional factors that implemented the effects of A20, including NF-$\kappa$B, CEBPA, OCT-1, OCT-4 and EGR1. Interactive scale-free network analysis captured the key genes that delivered the specific functions of A20. Most of these genes were affected at basal level and after resection. We validated a number of A20's target genes by real-time PCR, including p21, the mitochondrial solute carriers SLC25a10 and SLC25a13, and the fatty acid metabolism regulator, peroxisome proliferator activated receptor alpha. This resulted in greater energy production in A20-expressing livers following LR, as demonstrated by increased enzymatic activity of cytochrome c oxidase, or mitochondrial complex IV. Conclusion: This Systems Biology-based analysis unravels novel mechanisms supporting the pro-regenerative function of A20 in the liver, by optimizing energy production through improved lipid/fatty acid metabolism, and down-regulated inflammation. These findings support pursuit of A20-based therapies to improve patients' outcomes in the context of extreme liver injury and extensive LR for tumor treatment or donation

Validation of an automated assay for the measurement of cupric reducing antioxidant capacity in serum of dogs

BACKGROUND: The objective of the present study was to optimize and validate an automated method to assess the total antioxidant capacity (TAC) in serum of dogs using the cupric reducing antioxidant capacity (CUPRAC) methodology (TAC(c)) with bathocuproinedisulfonic acid disodium salt as chelating agent, evaluating also possible variations due to the use of two different automated analyzers. The method is based on the reduction of Cu(2+) into Cu(1+) by the action of the non-enzymatic antioxidants that are present in the sample. RESULTS: Imprecision was low in both apparatus utilized, and the results were linear across serial Trolox and canine serum samples dilutions. Lipids did not interfere with the assay; however, hemolysis increased the TAC(c) concentrations. When TAC(c) concentrations were determined in ten healthy (control) dogs and in twelve dogs with inflammatory bowel disease (IBD), dogs with IBD had lower TAC(c) concentrations when compared with the healthy dogs. CONCLUSIONS: The method validated in this paper is precise, simple, and fast and can be easily adapted to automated analyzers

Development and internal validation of a clinical prediction model for serious complications after emergency laparotomy

Purpose Emergency laparotomy (EL) is a common operation with high risk for postoperative complications, thereby requiring accurate risk stratification to manage vulnerable patients optimally. We developed and internally validated a predictive model of serious complications after EL. Methods Data for eleven carefully selected candidate predictors of 30-day postoperative complications (Clavien-Dindo grade >  = 3) were extracted from the HELAS cohort of EL patients in 11 centres in Greece and Cyprus. Logistic regression with Least Absolute Shrinkage and Selection Operator (LASSO) was applied for model development. Discrimination and calibration measures were estimated and clinical utility was explored with decision curve analysis (DCA). Reproducibility and heterogeneity were examined with Bootstrap-based internal validation and Internal–External Cross-Validation. The American College of Surgeons National Surgical Quality Improvement Program’s (ACS-NSQIP) model was applied to the same cohort to establish a benchmark for the new model. Results From data on 633 eligible patients (175 complication events), the SErious complications After Laparotomy (SEAL) model was developed with 6 predictors (preoperative albumin, blood urea nitrogen, American Society of Anaesthesiology score, sepsis or septic shock, dependent functional status, and ascites). SEAL had good discriminative ability (optimism-corrected c-statistic: 0.80, 95% confidence interval [CI] 0.79–0.81), calibration (optimism-corrected calibration slope: 1.01, 95% CI 0.99–1.03) and overall fit (scaled Brier score: 25.1%, 95% CI 24.1–26.1%). SEAL compared favourably with ACS-NSQIP in all metrics, including DCA across multiple risk thresholds. Conclusion SEAL is a simple and promising model for individualized risk predictions of serious complications after EL. Future external validations should appraise SEAL’s transportability across diverse settings

The Hellenic emergency laparotomy study (HELAS): a prospective multicentre study on the outcomes of emergency laparotomy in Greece

Background Emergency laparotomy (EL) is accompanied by high post-operative morbidity and mortality which varies significantly between countries and populations. The aim of this study is to report outcomes of emergency laparotomy in Greece and to compare them with the results of the National Emergency Laparotomy Audit (NELA). Methods This is a multicentre prospective cohort study undertaken between 01.2019 and 05.2020 including consecutive patients subjected to EL in 11 Greek hospitals. EL was defined according to NELA criteria. Demographics, clinical variables, and post-operative outcomes were prospectively registered in an online database. Multivariable logistic regression analysis was used to identify independent predictors of post-operative mortality. Results There were 633 patients, 53.9% males, ASA class III/IV 43.6%, older than 65 years 58.6%. The most common operations were small bowel resection (20.5%), peptic ulcer repair (12.0%), adhesiolysis (11.8%) and Hartmann’s procedure (11.5%). 30-day post-operative mortality reached 16.3% and serious complications occurred in 10.9%. Factors associated with post-operative mortality were increasing age and ASA class, dependent functional status, ascites, severe sepsis, septic shock, and diabetes. HELAS cohort showed similarities with NELA patients in terms of demographics and preoperative risk. Post-operative utilisation of ICU was significantly lower in the Greek cohort (25.8% vs 56.8%) whereas 30-day post-operative mortality was significantly higher (16.3% vs 8.7%). Conclusion In this study, Greek patients experienced markedly worse mortality after emergency laparotomy compared with their British counterparts. This can be at least partly explained by underutilisation of critical care by surgical patients who are at high risk for death