Oxidative stress: a systemic factor implicated in the pathogenesis of hepatic encephalopathy

Anti-inflammatory Effect of Mesenchymal Stromal Cell Transplantation and Quercetin Treatment in a Rat Model of Experimental Cerebral Ischemia

Here, we have investigated the synergistic effect of quercetin administration and transplantation of human umbilical cord mesenchymal stromal cells (HUMSCs) following middle cerebral artery occlusion in rat. Combining quercetin treatment with delayed transplantation of HUMSCs after local cerebral ischemia significantly (i) improved neurological functional recovery; (ii) reduced proinflammatory cytokines (interleukin(IL)-1β and IL-6), increased anti-inflammatory cytokines (IL-4, IL-10, and transforming growth factor-β1), and reduced ED-1 positive areas; (iii) inhibited cell apoptosis (caspase-3 expression); and (iv) improved the survival rate of HUMSCs in the injury site. Altogether, our results demonstrate that combined HUMSC transplantation and quercetin treatment is a potential strategy for reducing secondary damage and promoting functional recovery following cerebral ischemia.

The role of antioxidants and zinc in minimal hepatic encephalopathy: a randomized trial

BACKGROUND

Minimal hepatic encephalopathy (MHE) has a far-reaching impact on quality and function ability in daily life and may progress to overt hepatic encephalopathy. There is a synergistic effect between systemic oxidative stress and ammonia that is implicated in the pathogenesis of hepatic encephalopathy. The aim of this study is to investigate the effectiveness of oral supplementation of antioxidants and zinc gluconate on MHE versus lactulose.

METHODS

Our study included 58 patients with cirrhosis diagnosed as having MHE by neuropsychometric tests, including number connection test part A (NCT-A), digit symbol test (DST) and block design tests (BDTs). Patients were randomized to receive 175 mg zinc gluconate, 50,000 IU vitamin A, 500 mg vitamin C and 100 mg vitamin E once daily plus lactulose, dose 30-60 ml/day for 3 months [group A (n = 31)] or initiated and maintained on lactulose dose 30-60 ml/day for 3 months [group B (n = 27)]. Neuropsychometric tests and laboratory investigations were repeated after 3 months of therapy.

RESULTS

Compared with the baseline neuropsychometric tests, a significant improvement was reported in patients with MHE after 3 months of antioxidant and zinc therapy (group A) versus patients with lactulose therapy (group B) (NCT-A, p <0.001; DST, p = 0.006; BDT, p < 0.001). Antioxidant and zinc supplementation significantly decreased arterial ammonia level, alanine aminotransferase (ALT), aspartate aminotransferase (AST) (p < 0.001) and improved Child-Pugh score in MHE after 3 months of therapy (p= 0.024).

CONCLUSION

Antioxidant and zinc supplementation can improve MHE in patients with liver cirrhosis.

Alcohol Use and Breast Cancer: A Critical Review

The objective of this study was to outline the biological pathways of alcohol-attributable breast cancer, the epidemiological risk relationship between alcohol consumption and breast cancer, and the global burden of breast cancer incidence and mortality attributable to alcohol consumption, with a focus on light drinking. First, the literature regarding the biological mechanisms of how alcohol affects the risk of breast cancer was reviewed and summarized. Second, a search of meta-analyses that evaluated the risk relationship between alcohol consumption and breast cancer was conducted. Last, the burden of alcohol-attributable breast cancer incidence and mortality was estimated by means of a Population-Attributable Fraction methodology. Data on alcohol consumption were obtained from the Global Information System on Alcohol and Health, and data on cancer incidence and mortality were obtained from the GLOBOCAN database. Alcohol consumption affects breast cancer risk through the alteration in hormone levels and the associated biological pathways, the metabolism of ethanol resulting in carcinogens, and the inhibition of the one carbon metabolism pathway. The systematic review found 15 meta-analyses on the risk relationship between alcohol consumption (also light consumption) and the risk of breast cancer. All but 2 of these analyses showed a dose-response relationship between alcohol consumption and the risk of breast cancer. An estimated 144,000 (95% confidence interval [CI]: 88,000 to 200,000) breast cancer cases and 38,000 (95% CI: 2,400 to 53,000) breast cancer deaths globally in 2012 were attributable to alcohol, with 18.8% of these cases and 17.5% of these deaths affecting women who were light alcohol consumers. All levels of evidence showed a risk relationship between alcohol consumption and the risk of breast cancer, even at low levels of consumption. Due to this strong relationship, and to the amount of alcohol consumed globally, the incidence of and mortality from alcohol-attributable breast cancer is large.

Serum level of taurine would be associated with the amelioration of minimal hepatic encephalopathy in cirrhotic patients

AIM

A variety of treatment modalities including L-carnitine have been tried for cirrhotic patients with minimal hepatic encephalopathy (MHE), which improved MHE for some patients, but were not effective for the other patients. We aimed to identify pre-therapeutic independent factors to predict the amelioration of MHE after L-carnitine treatment.

METHODS

We performed a prospective cohort study on a total of 64 consecutive outpatients of cirrhotic patients who underwent blood biochemical examinations and neuropsychiatric (NP) test at Kobe University Hospital. MHE patients diagnosed by the NP test were p.o. administrated L-carnitine for 3 months. The patients with and without MHE amelioration were compared, and the independent factors were statistically examined. Predictive scoring systems of the amelioration of MHE were established using multivariate logistic regression.

RESULTS

The amelioration of MHE was found in 45.8% of MHE patients. Serum taurine before the treatment was the best predictive factor of the amelioration of MHE (P = 0.046). The predictive model using serum taurine discriminated well between patients with and without the amelioration of MHE (area under the receiver-operator curve, 0.748; 95% confidence interval, 0.531-0.901). The predictive scores of the amelioration of MHE enable the patient-specific probability to be easily looked up.

CONCLUSION

Serum taurine before L-carnitine treatment was shown to be an independent factor associated with the amelioration of MHE 3 months after the treatment. The easy pre-therapeutic prediction of MHE amelioration after L-carnitine treatment would help in improving awareness of the selection of MHE patients with good response to L-carnitine, thus being beneficial from a financial perspective.

Altered metal metabolism in patients with HCV-related cirrhosis and hepatic encephalopathy

Dysfunctional metal homeostasis contributes to oxidative stress and neuronal damage. These have been implicated in hepatic encephalopathy pathogenesis. To investigate whether altered metal metabolism is associated with hepatic encephalopathy. Twenty-one controls and 34 HCV-cirrhotic patients (ENC/NEC patients according to presence/absence of previous overt episodes of hepatic encephalopathy) and a control group were studied. Serum iron, copper, ceruloplasmin, ceruloplasmin activity, transferrin, and ceruloplasmin/transferrin ratio were determined. Neuropsychological tests were performed by the repeatable battery of neuropsychological status. Magnetic resonance assessed basal ganglia volumes and metal deposition (pallidal index and T2*). Cirrhotic patients performed worse than controls at cognitive tests, especially ENC patients,. At biochemical analysis copper concentrations, ceruloplasmin activity and transferrin levels were lower in ENC than in NEC patients and controls (p < 0.05 and p < 0.01, respectively). Ceruloplasmin/transferrin ratio was higher in ENC compared to NEC patients (p < 0.05), and controls (p < 0.01). By brain magnetic resonance, ENC patients showed reduced caudate and globus pallidus volumes compared to controls (p < 0.05), and ENC and NEC patients an increased pallidal index compared to controls (p < 0.01). In ENC patients, ceruloplasmin activity correlated with caudate volume and pallidal index (ρ = 0.773 and ρ = -0.683, p < 0.05). Altered metal metabolism likely contributes to cirrhotic hepatic encephalopathy.

The andrologist's contribution to a better life for ageing men: part 2

The long-term intake of a judiciously composed nutriceutical containing low-dose vitamins, antioxidants, minerals and particular herbal preparations seems justified for older persons who take medication, or who consume an unbalanced diet, or who are exposed to environmental toxins. Recent reports suggest these nutriceuticals may delay age-related diseases and the occurrence of cancer, and reduce mortality in apparently healthy ageing men. Food supplementation with a nutriceutical that was formulated particularly for ageing men should result in an increase of at least one quality-adjusted life year and may lower the financial and social burden of disease in elderly people.

Management options in decompensated cirrhosis

Chronic injury to the liver from a variety of different sources can result in irreversible scarring of the liver, known as cirrhosis. Cirrhosis is a major cause of morbidity and mortality in the USA, and according to the Centers for Disease Control and Prevention was responsible for 31,903 deaths in 2010 alone. It is thus of the utmost importance to appropriately manage these patients in the inpatient and outpatient setting to improve morbidity and mortality. In this review, we address four major areas of cirrhosis management: outpatient management of portal hypertension with decompensation, hepatic encephalopathy, hepatorenal syndrome, and bleeding/coagulation issues. Outpatient management covers recommendations for health care maintenance and screening. Hepatic encephalopathy encompasses a brief review of pathophysiology, treatment in the acute setting, and long-term prevention. Hepatorenal syndrome is discussed in regards to pathophysiology and treatment in the hospital setting. Finally, a discussion of the assessment of coagulation profiles in cirrhosis and recommendations for bleeding and thrombosis complications is included. These topics are not all encompassing with regard to this complicated population, but rather an overview of a few medical problems that are commonly encountered in their care.

Dexmedetomidine attenuates oxidative stress induced lung alveolar epithelial cell apoptosis in vitro

Background. Oxidative stress plays a pivotal role in the lung injuries of critical ill patients. This study investigates the protection conferred by α₂ adrenoceptor agonist dexmedetomidine (Dex) from lung alveolar epithelial cell injury induced by hydrogen peroxide (H₂O₂) and the underlying mechanisms. Methods. The lung alveolar epithelial cell line, A549, was cultured and then treated with 500 μM H₂O₂ with or without Dex (1 nM) or Dex in combination with atipamezole (10 nM), an antagonist of α₂ receptors. Their effect on mitochondrial membrane potential (Δψ_m), reactive oxygen species (ROS), and the cell cycle was assessed by flow cytometry. Cleaved-caspases 3 and 9, BAX, Bcl-2, phospho-mTOR (p-mTOR), ERK1/2, and E-cadherin expression were also determined with immunocytochemistry. Results. Upregulation of cleaved-caspases 3 and 9 and BAX and downregulation of Bcl-2, p-mTOR, and E-cadherin were found following H₂O₂ treatment, and all of these were reversed by Dex. Dex also prevented the ROS generation, cytochrome C release, and cell cycle arrest induced by H₂O₂. The effects of Dex were partially reversed by atipamezole. Conclusion. Our study demonstrated that Dex protected lung alveolar epithelial cells from apoptotic injury, cell cycle arrest, and loss of cell adhesion induced by H₂O₂ through enhancing the cell survival and proliferation.

Hepatic encephalopathy in patients with acute decompensation of cirrhosis and acute-on-chronic liver failure

Hepatic encephalopathy in a hospitalized cirrhotic patient is associated with a high mortality rate and its presence adds further to the mortality of patients with acute-on-chronic liver failure (ACLF). The exact pathophysiological mechanisms of HE in this group of patients are unclear but hyperammonemia, systemic inflammation (including sepsis, bacterial translocation, and insulin resistance) and oxidative stress, modulated by glutaminase gene alteration, remain as key factors. Moreover, alcohol misuse, hyponatremia, renal insufficiency, and microbiota are actively explored. HE diagnosis requires exclusion of other causes of neurological, metabolic and psychiatric dysfunction. Hospitalization in the ICU should be considered in every patient with overt HE, but particularly if this is associated with ACLF. Precipitating factors should be identified and treated as required. Evidence-based specific management options are limited to bowel cleansing and non-absorbable antibiotics. Ammonia lowering drugs, such as glycerol phenylbutyrate and ornithine phenylacetate show promise but are still in clinical trials. Albumin dialysis may be useful in refractory cases. Antibiotics, prebiotics, and treatment of diabetes reduce systemic inflammation. Where possible and not contraindicated, large portal-systemic shunts may be embolized but liver transplantation is the most definitive step in the management of HE in this setting. HE in patients with ACLF appears to be clinically and pathophysiologically distinct from that of acute decompensation and requires further studies and characterization.

Cerebral effects of ammonia in liver disease: current hypotheses

Hyperammonemia is necessary for development of the cerebral complications to liver disease including hepatic encephalopathy and cerebral edema but the mechanisms are unclear. Ammonia is taken up by the brain in proportion to its arterial concentration. The flux into the brain is most likely by both diffusion of NH3 and mediated transport of NH4 (+) . Astrocytic detoxification of ammonia involves formation of glutamine at concentrations high enough to produce cellular edema, but compensatory mechanisms reduce this effect. Glutamine can be taken up by astrocytic mitochondria and initiate the mitochondrial permeability transition but the clinical relevance is uncertain. Elevated astrocytic glutamine interferes with neurotransmission. Thus, animal studies show enhanced glutamatergic neurotransmission via the NMDA receptor which may be related to the acute cerebral complications to liver failure, while impairment of the NMDA activated glutamate-NO-cGMP pathway could relate to the behavioural changes seen in hepatic encephalopathy. Elevated glutamine also increases GABA-ergic tone, an effect which is aggravated by mitochondrial production of neurosteroids; this may relate to decreased neurotransmission and precipitation of encephalopathy by GABA targeting drugs. Hyperammonemia may compromise cerebral energy metabolism as elevated cerebral lactate is generally reported. Hypoxia is unlikely since cerebral oxygen:glucose utilisation and lactate:pyruvate ratio are both normal in clinical studies. Ammonia inhibits α-ketoglutaratedehydrogenase in isolated mitochondria, but the clinical relevance is dubious due to the observed normal cerebral oxygen:glucose utilization. Recent studies suggest that ammonia stimulates glycolysis in excess of TCA cycle activity, a hypothesis that may warrant further testing, in being in accordance with the limited clinical observations.

Pharmacotherapy for hyperammonemia

INTRODUCTION

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that is seen in patients with liver failure. The pathogenesis of HE is not entirely understood, but several hypotheses have emerged and persisted during the years. Despite the many prevalent hypotheses, most of the existing evidence point to ammonia as the main culprit behind primary and secondary symptoms making it the center of potential therapeutic options for the treatment of HE. Most treatments of hyperammonemia target the organs and metabolic processes involved in ammonia detoxification.

AREAS COVERED

This article provides a review of the current targets of therapy as well as the drugs used for hyperammonemia treatment.

EXPERT OPINION

Lactulose and rifaximin have a proven role as measures to use for secondary prophylaxis and are the mainstay of current therapy. The use of molecular adsorbent recirculating system in patients with severe HE has been proven to be efficacious, but through mechanisms that appear to be independent of ammonia. The main challenge that faces the further development of treatments for HE is finding appropriate end points, and the next step would be to provide evidence of the effectiveness of established treatments and define the role of emerging new treatments.

Induction of systemic oxidative stress leads to brain oedema in portacaval shunted rats

BACKGROUND & AIMS

The pathogenesis of hepatic encephalopathy (HE) is multifactorial and often associated with the development of brain oedema. In addition to ammonia playing a central role, systemic oxidative stress is believed to aggravate the neuropsychological effects of ammonia in patients with chronic liver disease (CLD). The aim of this study was to (i) induce systemic oxidative stress in hyperammonaemic portacaval anastomosed (PCA) rats by inhibiting the antioxidant glutathione using Dimethyl maleate (DEM) and (ii) investigate whether a synergistic relationship between ammonia and oxidative stress contributes to the pathogenesis of brain oedema in CLD.

METHODS

Four-week PCA and sham-operated rats received DEM (0.4-4 mg/kg/day) for the last 10 days before sacrifice when oxidative stress markers [reactive oxygen species (ROS) and malondialdehyde (MDA)] were assessed in blood and frontal cortex. Brain water content was measured using a specific gravimetric technique.

RESULTS

Dimethyl maleate induced an increase in ROS and MDA in the blood, but not in the brain, of the PCA rats, compared with non-treated PCA rats. This was accompanied with an increase in brain water content (PCA+DEM: 78.45 ± 0.13% vs. PCA: 77.38 ± 0.11%, P < 0.001). Higher doses of DEM induced systemic oxidative stress in sham-operated controls, but brain oedema did not develop.

CONCLUSIONS

Dimethyl maleate provoked systemic, not central, oxidative stress in PCA rats, resulting in the development of brain oedema. Independently, hyperammonaemia and systemic oxidative stress do not precipitate brain oedema; therefore, our findings sustain that a synergistic effect between hyperammonaemia and systemic oxidative stress is responsible for the development of brain oedema in HE.

Oxidative stress as a crucial factor in liver diseases

Redox state constitutes an important background of numerous liver disorders. The redox state participates in the course of inflammatory, metabolic and proliferative liver diseases. Reactive oxygen species (ROS) are primarily produced in the mitochondria and in the endoplasmic reticulum of hepatocytes via the cytochrome P450 enzymes. Under the proper conditions, cells are equipped with special molecular strategies that control the level of oxidative stress and maintain a balance between oxidant and antioxidant particles. Oxidative stress represents an imbalance between oxidant and antioxidant agents. Hepatocytic proteins, lipids and DNA are among the cellular structures that are primarily affected by ROS and reactive nitrogen species. The process results in structural and functional abnormalities in the liver. Thus, the phenomenon of oxidative stress should be investigated for several reasons. First, it may explain the pathogenesis of various liver disorders. Moreover, monitoring oxidative markers among hepatocytes offers the potential to diagnose the degree of liver damage and ultimately to observe the response to pharmacological therapies. The present report focuses on the role of oxidative stress in selected liver diseases.

Ammonium activates ouabain-activated signalling pathway in astrocytes: therapeutic potential of ouabain antagonist

The causal role of ammonium in hepatic encephalopathy was identified in 1930s. Astroglial cells are primary cellular elements of hepatic encephalopathy which conceptually, can be considered a toxic astrogliopathology. Previously we have reported that acute exposure to ammonium activated ouabain/Na,K-ATPase signalling pathway, which includes Src, EGF receptor, Raf, Ras, MEK and ERK1/2. Chronic incubation of astrocytes with ammonium increased production of endogenous ouabain-like compound. Ouabain antagonist canrenone abolished effects of ammonium on astrocytic swelling, ROS production, and upregulation of gene expression and function of TRPC1 and Cav1.2. However, ammonium induces multiple pathological modifications in astrocytes, and some of them may be not related to this signalling pathway. In this review, we focus on the effect of ammonium on ouabain/Na,K-ATPase signalling pathway and its involvement in ammonium-induced ROS production, cell swelling and aberration of Ca(2+) signals in astrocytes. We also briefly discuss Na,K-ATPase, EGF receptor, endogenous ouabain and ouabain antagonist.

Properties and expression of Na+/K+-ATPase α-subunit isoforms in the brain of the swamp eel, Monopterus albus, which has unusually high brain ammonia tolerance

The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l(-1)) and accumulate ammonia to high concentrations in its brain (4.5 µmol g(-1)). Na(+)/K(+)-ATPase (Nka) is an essential transporter in brain cells, and since NH4(+) can substitute for K(+) to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka α-subunits, some of which might have high K(+) specificity. Thus, this study aimed to clone and sequence the nka α-subunits from the brain of M. albus, and to determine the effects of ammonia exposure on their mRNA expression and overall protein abundance. The effectiveness of NH4(+) to activate brain Nka from M. albus and Mus musculus was also examined by comparing their Na(+)/K(+)-ATPase and Na(+)/NH4(+)-ATPase activities over a range of K(+)/NH4(+) concentrations. The full length cDNA coding sequences of three nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 expression was undetectable. Exposure to 50 mmol l(-1) NH4Cl for 1 day or 6 days resulted in significant decreases in the mRNA expression of nkaα1, nkaα3a and nkaα3b. The overall Nka protein abundance also decreased significantly after 6 days of ammonia exposure. For M. albus, brain Na(+)/NH4(+)-ATPase activities were significantly lower than the Na(+)/K(+)-ATPase activities assayed at various NH4(+)/K(+) concentrations. Furthermore, the effectiveness of NH4(+) to activate Nka from the brain of M. albus was significantly lower than that from the brain of M. musculus, which is ammonia-sensitive. Hence, the (1) lack of nkaα2 expression, (2) high K(+) specificity of K(+) binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα isoforms and the overall Nka protein abundance in response to ammonia exposure might be some of the contributing factors to the high brain ammonia tolerance in M. albus.