Liver cell necrosis: cellular mechanisms and clinical implications

Hyperoxia fully protects mitochondria of explanted livers

Liver ischemia-reperfusion injury is still an open problem in many clinical circumstances, including surgery and transplantation. This study investigates how mitochondrial structure, mass and oxidative phosphorylation change and may be preserved during a brief period of ischemia followed by a long period of reperfusion, an experimental model that mimics the condition to which a liver is exposed during transplantation. Livers were explanted from rats and exposed for 24 h to three different oxygen availability conditions at 4 °C. Mitochondrial mass, respiration, oxidative phosphorylation (OXPHOS), and levels of OXPHOS complexes were all significantly altered in livers stored under the currently used preservation condition of normoxia. Remarkably, liver perfusion with hyperoxic solutions fully preserved mitochondrial morphology and function, suggesting that perfusion of the graft with hyperoxic solution should be considered in human transplantation.

Dual endothelin-converting enzyme/neutral endopeptidase blockade in rats with D-galactosamine-induced liver failure

Secondary activation of the endothelin system is thought to be involved in toxic liver injury. This study tested the hypothesis that dual endothelin-converting enzyme / neutral endopeptidase blockade might be able to attenuate acute toxic liver injury.

Male Sprague-Dawley rats were implanted with subcutaneous minipumps to deliver the novel compound SLV338 (10 mg/kg*d) or vehicle. Four days later they received two intraperitoneal injections of D-galactosamine (1.3 g/kg each) or vehicle at an interval of 12 hours. The animals were sacrificed 48 hours after the first injection.

Injection of D-galactosamine resulted in very severe liver injury, reflected by strongly elevated plasma liver enzymes, hepatic necrosis and inflammation, and a mortality rate of 42.9 %. SLV338 treatment did not show any significant effect on the extent of acute liver injury as judged from plasma parameters, hepatic histology and mortality. Plasma measurements of SLV338 confirmed adequate drug delivery. Plasma concentrations of big endothelin-1 and endothelin-1 were significantly elevated in animals with liver injury (5-fold and 62-fold, respectively). Plasma endothelin-1 was significantly correlated with several markers of liver injury. SLV338 completely prevented the rise of plasma big endothelin-1 (p < 0.05) and markedly attenuated the rise of endothelin-1 (p = 0.055).

In conclusion, dual endothelin-converting enzyme / neutral endopeptidase blockade by SLV338 did not significantly attenuate D-galactosamine-induced acute liver injury, although it largely prevented the activation of the endothelin system. An evaluation of SLV338 in a less severe model of liver injury would be of interest, since very severe intoxication might not be relevantly amenable to pharmacological interventions.

Effect of a Diet Supplemented with alpha-Tocopherol and beta-Carotene on ATP and Antioxidant Levels after Hepatic Ischemia-Reperfusion

Ischemia-reperfusion injury associated with liver transplantation remains a serious complication in clinical practice. In the present study the effect of intake of α-tocopherol or β-carotene to limit liver injury by oxidative stress in ischemia and reperfusion was explored. Wistar rats were fed with diets enriched with α-tocopherol (20 mg/day) or β-carotene (3 mg/day) for 21 days. After 21 days, their livers were subjected to 15 and 30 min of ischemia and afterwards were reperfused for 60 min. The recovery of levels of ATP during reperfusion was better in the group of rats whose diets were supplemented with α-tocopherol or β-carotene than in the group control. The supplementation of the diet induced changes in the profile of enzymatic antioxidants. The supplementation with α-tocopherol and β-carotene resulted in a decreased of superoxide dismutase during the ischemia and a recovery was observed after reperfusion. Not changes were observed for the enzymes catalase and glutathione peroxidase and glutathione but their values were higher to those of the group control. In conclusion, the supplementation with α-tocopherol and β-carotene improve the antioxidant and energetic state of liver after ischemia and reperfusion injury.

Improvement of the cold storage of isolated human hepatocytes

Increasing amounts of human hepatocytes are needed for clinical applications and different fields of research, such as cell transplantation, bioartificial liver support, and pharmacological testing. This demand calls for adequate storage options for isolated human liver cells. As cryopreservation results in severe cryoinjury, short-term storage is currently performed at 2-8°C in preservation solutions developed for the storage of solid organs. However, besides slowing down cell metabolism, cold also induces cell injury, which is, in many cell types, iron dependent and not counteracted by current storage solutions. In this study, we aimed to characterize storage injury to human hepatocytes and develop a customized solution for cold storage of these cells. Human hepatocytes were isolated from material obtained from partial liver resections, seeded in monolayer cultures, and, after a preculture period, stored in the cold in classical and new solutions followed by rewarming in cell culture medium. Human hepatocytes displayed cold-induced injury, resulting in >80% cell death (LDH release) after 1 week of cold storage in University of Wisconsin solution or cell culture medium and 3 h of rewarming. Cold-induced injury could be significantly reduced by the addition of the iron chelators deferoxamine and LK 614. Experiments with modified solutions based on the new organ preservation solution Custodiol-N showed that ion-rich variants were better than ion-poor variants, chloride-rich solutions better than chloride-poor solutions, potassium as main cation superior to sodium, and pH 7.0 superior to pH 7.4. LDH release after 2 weeks of cold storage in the thus optimized solution was below 20%, greatly improving cold storage of human hepatocytes. The results were confirmed by the assessment of hepatocellular mitochondrial membrane potential and functional parameters (resazurin reduction, glucagon-stimulated glucose liberation) and thus suggest the use of a customized hepatocyte storage solution for the cold storage of these cells.

Assessment of a chloride-poor versus a chloride-containing version of a modified histidine-tryptophan-ketoglutarate solution in a rat liver transplantation model

Recent in vitro studies of cold-induced cell injury have revealed the detrimental effects of extracellular chloride on cold-stored isolated rat hepatocytes; however, its influence on endothelial cells is beneficial. To determine which of these effects is predominant in vivo, we tested both a chloride-poor variant of a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution and a chloride-containing variant in a rat liver transplantation model. The study, which was carried out in a blinded fashion with 7 or 8 rats per group, was divided into 2 parts: (1) a comparison of survival in 3 series under different conditions [different microsurgeons, rat strains, cold ischemia times (3, 12, and 24 hours), and warm ischemia times] and (2) an assessment of the microcirculation (30-90 minutes after reperfusion), laboratory data, bile production, and histology. In each of the survival experiments, a (strong) tendency toward prolonged survival was observed with the new chloride-containing solution (50% versus 12.5%, 75% versus 37.5%, and 100% versus 71.4% [chloride-containing vs. chloride-poor], overall P < 0.05). Additionally, the sinusoidal perfusion rates (83.9% ± 4.0% versus 69.2% ± 10.8%, P < 0.01) and the red blood cell velocities in sinusoids (147.7 ± 26.7 versus 115.5 ± 26.0 μm/second, P < 0.05) and in postsinusoidal venules (332.4 ± 87.3 versus 205.5 ± 53.5 μm/second, P < 0.01) were clearly higher with chloride. Moreover, the serum activities of liver enzymes were slightly reduced (not significantly), and bile production was significantly increased. These results suggest an overall beneficial effect of chloride in HTK-based liver preservation solutions.

The role of liver biopsy in detection of hepatic oxidative stress

The goal of the current paper is to explore the role of liver biopsy as a tool in detection of hepatic oxidative stress, with brief notes on different types of free radicals, antioxidants, hepatic and blood oxidative stress, and lipid peroxidation. Hepatic oxidative stress was investigated for many years in human and animals, but most of the studies performed in animals were concerned with studying oxidative status in the liver tissues after slaughtering or euthanasia. However, in human medicine, a large number of studies were implemented to investigate the status of antioxidants in liver biopsy specimens. Similar studies are required in animals, as the changes in hepatic antioxidants and formation of lipid peroxide give a good idea about the condition of the liver. On the other hand, hepatic disease may present without significant effect on blood oxidative status, and, consequently, the best way to detect the status of hepatic oxidants and antioxidants is through measuring in liver biopsy. Measuring antioxidants status directly in the liver tissues gives an accurate estimation about the condition of the liver, permits the diagnosis of hepatic dysfunction, and helps to determine the degree of deterioration in the hepatic cells.

Oxidative stress after living related liver transplantation subsides with time in pediatric patients

BACKGROUND

Oxidative stress has been suspected to influence graft survival and prognosis in pediatric recipients of living related liver transplantation (LRLT).

PURPOSE

We determined the oxidative status of pediatric LRLT recipients during their regular outpatient follow-up visits, and looked for a relationship between oxidative status and post-liver transplantation (post-LTx) duration.

PATIENTS

The study included 43 patients (20 males and 23 females) between the ages of 1.6 and 25.1 years (median 10.7 years) who had undergone LRLT from 5 months to 17.5 years (median 7 years) prior to the study, between the ages of 1.2 and 14.4 years (median 3.5 years).

METHODS

Serum glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), gamma-glutamyl transpeptidase (γ-GTP), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), direct bilirubin and choline-esterase were measured as part of the patients' regular follow-up visits. Serum total hydroperoxide (TH) and biological antioxidative potential (BAP) were measured using the free radical analytic system which requires 20 μl of serum and 10 min of processing time for each sample. Oxidative stress index (OSI) was calculated as the ratio of TH to BAP.

RESULTS

Serum OSI correlated positively with serum levels of GOT, GPT, LDH, ALP, γ-GTP and direct bilirubin. Serum OSI, TH, LDH, ALP and GOT correlated negatively with post-LTx duration. Serum BAP correlated positively with post-LTx duration. Serum TH correlated positively with serum GOT and γ-GTP, but negatively with serum BAP.

CONCLUSIONS

(1) The OSI, which can be calculated based on data acquired through a simple outpatient procedure, can serve as an index of our patients' laboratory results and oxidative status. (2) The LRLT recipients in our study were at risk for oxidative stress early in the post-operative period, but this risk subsided with time.

Reactive oxygen species mediate human hepatocyte injury during hypoxia/reoxygenation

Increasing evidence shows that reactive oxygen species (ROS) may be critical mediators of liver damage during the relative hypoxia of ischemia/reperfusion injury (IRI) associated with transplant surgery or of the tissue microenvironment created as a result of chronic hepatic inflammation or infection. Much work has been focused on Kupffer cells or liver resident macrophages with respect to the generation of ROS during IRI. However, little is known about the contribution of endogenous hepatocyte ROS production or its potential impact on the parenchymal cell death associated with IRI and chronic hepatic inflammation. For the first time, we show that human hepatocytes isolated from nondiseased liver tissue and human hepatocytes isolated from diseased liver tissue exhibit marked differences in ROS production in response to hypoxia/reoxygenation (H-R). Furthermore, several different antioxidants are able to abrogate hepatocyte ROS-induced cell death during hypoxia and H-R. These data provide clear evidence that endogenous ROS production by mitochondria and nicotinamide adenine dinucleotide phosphate oxidase drives human hepatocyte apoptosis and necrosis during hypoxia and H-R and may therefore play an important role in any hepatic diseases characterized by a relatively hypoxic liver microenvironment. In conclusion, these data strongly suggest that hepatocytes and hepatocyte-derived ROS are active participants driving hepatic inflammation. These novel findings highlight important functional/metabolic differences between hepatocytes isolated from normal donor livers, hepatocytes isolated from normal resected tissue obtained during surgery for malignant neoplasms, and hepatocytes isolated from livers with end-stage disease. Furthermore, the targeting of hepatocyte ROS generation with antioxidants may offer therapeutic potential for the adjunctive treatment of IRI and chronic inflammatory liver diseases.

Pathological axes of wound repair: gastrulation revisited

Post-traumatic inflammation is formed by molecular and cellular complex mechanisms whose final goal seems to be injured tissue regeneration.

In the skin -an exterior organ of the body- mechanical or thermal injury induces the expression of different inflammatory phenotypes that resemble similar phenotypes expressed during embryo development. Particularly, molecular and cellular mechanisms involved in gastrulation return. This is a developmental phase that delineates the three embryonic germ layers: ectoderm, endoderm and mesoderm. Consequently, in the post-natal wounded skin, primitive functions related with the embryonic mesoderm, i.e. amniotic and yolk sac-derived, are expressed. Neurogenesis and hematogenesis stand out among the primitive function mechanisms involved.

Interestingly, in these phases of the inflammatory response, whose molecular and cellular mechanisms are considered as traces of the early phases of the embryonic development, the mast cell, a cell that is supposedly inflammatory, plays a key role.

The correlation that can be established between the embryonic and the inflammatory events suggests that the results obtained from the research regarding both great fields of knowledge must be interchangeable to obtain the maximum advantage.

Analysis of the liver effluent as a marker of preservation injury and early graft performance

In liver transplantation, the effluent solution, which represents the washout of residual preservation solution, can be collected before reperfusion to determine the release of the markers of endothelial cell injury and damage to the liver. The enzyme activities detected in the washout solution may allow the development of an index that could be clinically valuable for the prediction of early posttransplant graft function. In the present study, we collected liver effluents from 47 livers at the time of graft rinsing to measure liver enzymes (aminotransferases and lactate dehydrogenase) as well as the serum enzyme levels of the recipients for correlation with early postoperative graft viability (1-month survival). The patients were divided into two groups: death (D) and survival (S). Nonparametric statistical analysis was used with the level of significance set at P < .05. Aminotransferases and lactate dehydrogenase levels higher among the D group (P < .05 for all measurements), leading us to conclude that the effluent represents a good marker of preservation injury and early graft performance.

The anti-necrosis role of hypoxic preconditioning after acute anoxia is mediated by aldose reductase and sorbitol pathway in PC12 cells

It has been demonstrated that hypoxic preconditioning (HP) enhances the survival ability of the organism against the subsequent acute anoxia (AA). However, it is not yet clear whether necrosis induced by AA can be prevented by HP, and what are the underlying mechanisms. In this study, we examined the effect of HP (10% O(2), 48 h) on necrosis induced by AA (0% O(2), 24 h) in PC12 cells. We found that HP delayed the regulatory volume decrease and reduced cell swelling after 24 h of exposure to AA. Since aldose reductase (AR) is involved in cell volume regulation, we detected AR mRNA expression with reverse transcription-polymerase chain reaction (RT-PCR) techniques. The AR mRNA level was dramatically elevated by HP. Furthermore, an HP-induced decrease in cell injury was reversed by berberine chloride (BB), the inhibitor of AR. In addition, sorbitol synthesized from glucose catalyzed by AR is directly related to cell volume regulation. Subsequently, we tested sorbitol content in the cytoplasm. HP clearly elevated sorbitol content, while BB inhibited the elevation induced by HP. Further study showed that a strong inhibitor of sorbitol permease, quinidine, completely reversed the protection induced by HP after AA. These data provide evidence that HP prevents necrosis induced by AA and is mediated by AR and sorbitol pathway.

Lack of therapeutic effects of gabexate mesilate on the hepatic encephalopathy in rats with acute and chronic hepatic failure

BACKGROUND AND AIM

Inflammation plays a pivotal role in liver injury. Gabexate mesilate (GM, a protease inhibitor) inhibits inflammation by blocking various serine proteases. This study examined the effects of GM on hepatic encephalopathy in rats with acute and chronic liver failure.

METHODS

Acute and chronic liver failure (cirrhosis) were induced by intraperitoneal TAA administration (350 mg/kg/day for 3 days) and common bile duct ligation, respectively, in male Sprague-Dawley rats. Rats were randomized to receive either GM (50 mg/10 mL/kg) or saline intraperitoneally for 5 days. Severity of encephalopathy was assessed by the Opto-Varimex animal activity meter and hemodynamic parameters, mean arterial pressure and portal pressure, were measured (only in chronic liver failure rats). Plasma levels of liver biochemistry, ammonia, nitrate/nitrite, interleukins (IL) and tumor necrosis factor (TNF)-alpha were determined.

RESULTS

In rats with acute liver failure, GM treatment significantly decreased the plasma levels of alanine aminotransferase (P = 0.02), but no significant difference of motor activity, plasma levels of ammonia, IL-1beta, IL-6, IL-10 and TNF-alpha or survival was found. In chronic liver failure rats, GM significantly lowered the plasma TNF-alpha levels (P = 0.04). However, there was no significant difference of motor activity, other biochemical tests or survival found. GM-treated chronic liver failure rats had higher portal pressure (P = 0.04) but similar mean arterial pressure in comparison with saline-treated rats.

CONCLUSIONS

Chronic GM treatment does not have a major effect on hepatic encephalopathy in rats with TAA-induced acute liver failure and rats with chronic liver failure induced by common bile duct ligation.

The antioxidant effect of green tea catechin ameliorates experimental liver injury

PURPOSE

Several studies have reported green tea catechin to have both antifibrotic and anti-oxidative effects. The goal of this study was to evaluate the effect of green tea cathechin therapy in hepatic tissue injury using cholestatic rats with bile duct ligation.

MATERIALS AND METHODS

We performed bile duct ligation on cholestatic seven-week-old male Wistar rats and classified them into three groups according to the method of treatment. The groups comprised the SHAM group, the NT-group (no-treatment-group), and the T-group (treatment-group). The rats were orally administered green tea catechin at a dose of 50mg/kg/day and were sacrificed on the 17th postoperative day. We subsequently investigated the levels of fibrosis and antioxidant activity associated with various clinical markers. We evaluated the serum AST and ALT levels and performed immunohistochemical analyses for 4-hydroxynonenal (4-HNE), 8-oxo-2'deoxyguanosine (8-OHdG) and transforming growth factor-beta1 (TGF-beta1). We also evaluated the levels of activator protein-1 m-RNA (AP-1 m-RNA) and tissue inhibitor metalloproteinase-1 m-RNA (TIMP-1 m-RNA) by Real Time PCR. Finally, we performed Azan staining and immunohistochemical staining of alpha-smooth muscle actin (alpha-SMA) to evaluate the degree of fibrosis.

RESULTS

The values of serum AST, serum ALT, AP-1 m-RNA, alpha-SMA, TGF-beta1, 4-HNE, and 8-OHdG in the T-Group were significantly lower than those in NT-Group. Therefore, the administration of green tea catechin might have suppressed the oxidative stress, controlled the stellate cell activation and consequently reduced the fibrosis.

CONCLUSION

Green tea catechin may reduce hepatic fibrosis by suppressing oxidative stress and controlling the transcription factor expression involved in stellate cell activation.

Conversion of the synthetic catalase mimic precursor TAA-1 into the active catalase mimic in isolated hepatocytes

In previous studies we reported on the catalase-like activity and antioxidative properties of a non-heme Fe(III)-tetraaza[14]annulene complex, 5,4-didehydro-5,9,14,18-tetraaza-di(2,2-dimethyl-[5,6]benzo[1,3]dioxolo)[a,h]cyclotetradecene--Fe(III) chloride (TAA-1/Fe). We proposed that intracellular application of the parent, iron-free tetraaza[14]annulene ligand, TAA-1, as precursor would allow antioxidative defense along two lines, i.e. by chelation of potentially toxic cellular iron ions and, subsequently, by catalase-mimic activity. We here set out to establish whether the active catalase mimic is indeed formed intracellularly when cells are loaded with the ligand. When isolated rat hepatocytes were preloaded with TAA-1, they were protected against iron-induced cell injury and oxidative stress elicited by exposure to the membrane-permeable iron complex Fe(III)/8-hydroxyquinoline. After lysis of the cells, followed by ultrafiltration to remove endogenous catalase, the lysate exhibited catalase-like activity, while lysates of control cells not treated with TAA-1 showed no catalase-like activity. By comparison with authentic TAA-1/Fe, an intracellular formation of 2.0 +/- 0.3 microm of the active catalase mimic in native hepatocytes exposed to TAA-1 and of 6.5 +/- 1.0 microm in hepatocytes exposed to both TAA-1 and iron ions was estimated. The intracellular formation of the active catalase mimic thus renders TAA-1 an attractive compound for protection against iron- and/or hydrogen peroxide-dependent cell injuries.

Vitamin E deficiency induces liver nuclear factor-κB DNA-binding activity and changes in related genes

The biological functions of vitamin E have been classically attributed to its property as a potent inhibitor of lipid peroxidation in cellular membranes. However, in 1991, Azzi's group first described that alpha-tocopherol inhibits smooth muscle cell proliferation in a protein kinase C (PKC)-dependent way, demonstrating a non-antioxidant cell signalling function for vitamin E. More recently, the capacity of alpha-tocopherol to modulate gene expression with the implication of different transcription factors, beyond its antioxidant properties, has also been established. This study was to determine the effect of vitamin E-deficiency on liver nuclear factor-kappa B (NF-kappaB) DNA-binding activity and the response of target antioxidant-defense genes and cell cycle modulators. Rats were fed either control diet or vitamin-E free diet until 60 or 90 days after birth. Vitamin E-deficiency enhanced liver DNA-binding activity of NF-kappaB [electrophoretic mobility-shift assay, (EMSA)] and up-regulated transcription of gamma-glutamylcysteine synthetase (gamma-GCSM; gamma-GCSC), cyclin D1 and cyclin E. We also showed down-regulation of p21(Waf1/Cip1) transcription. Western-blot analysis demonstrated that gamma-glutamylcysteine synthetase catalytic subunit (gamma-GCSC) and cyclin D1 showed a similar pattern to that found in the RT-PCR analysis. Moreover, chromatin immunoprecipitation (ChIP) assay demonstrated that NF-kappaB directly regulates transcription of gamma-GCS (both subunits) and cyclin D1 through the binding of NF-kappaB to the corresponding gene promoters, which was enhanced in vitamin E-deficiency. These findings show that vitamin E-deficiency induces significant molecular regulatory properties in liver cells with an altered expression of both antioxidant-defense genes and genes that control the cell cycle and demonstrate that liver NF-kappaB activation is involved in this response. Our results emphasize the importance of maintaining an adequate vitamin E consumption not only to prevent liver oxidative damage but also in modulating signal transduction.

Surgical inflammation: a pathophysiological rainbow

Tetrapyrrole molecules are distributed in virtually all living organisms on Earth. In mammals, tetrapyrrole end products are closely linked to oxygen metabolism. Since increasingly complex trophic functional systems for using oxygen are considered in the post-traumatic inflammatory response, it can be suggested that tetrapyrrole molecules and, particularly their derived pigments, play a key role in modulating inflammation.

In this way, the diverse colorfulness that the inflammatory response triggers during its evolution would reflect the major pathophysiological importance of these pigments in each one of its phases. Therefore, the need of exploiting this color resource could be considered for both the diagnosis and treatment of the inflammation.

Potential role of lycopene in the treatment of hepatitis C and prevention of hepatocellular carcinoma

Hepatitis C virus (HCV) infection and hepatocellular carcinoma (HCC) are growing health problems around the world. Oxidative stress plays a significant role in the initiation and progression of hepatocellular damage and possibly in the development of HCC in HCV infected patients. In vitro, animal and clinical studies suggest that lycopene, a nonprovitamin A carotenoid and a potent antioxidant, may attenuate the liver injury and possibly prevent the development of HCC. In this article, we discuss the relationship between HCV infection and oxidative stress and review the potential role of lycopene in the treatment of HCV and prevention of HCC.

Hydrogen peroxide mobilizes Ca2+ through two distinct mechanisms in rat hepatocytes

AIM

Hydrogen peroxide (H2O2) is produced during liver transplantation. Ischemia/reperfusion induces oxidation and causes intracellular Ca2+ overload, which harms liver cells. Our goal was to determine the precise mechanisms of these processes.

METHODS

Hepatocytes were extracted from rats. Intracellular Ca2+ concentrations ([Ca2+](i)), inner mitochondrial membrane potentials and NAD(P)H levels were measured using fluorescence imaging. Phospholipase C (PLC) activity was detected using exogenous PIP2. ATP concentrations were measured using the luciferin-luciferase method. Patch-clamp recordings were performed to evaluate membrane currents.

RESULTS

H2O2 increased intracellular Ca2+ concentrations ([Ca2+](i)) across two kinetic phases. A low concentration (400 micromol/L) of H2O2 induced a sustained elevation of [Ca2+](i) that was reversed by removing extracellular Ca2+. H2O2 increased membrane currents consistent with intracellular ATP concentrations. The non-selective ATP-sensitive cation channel blocker amiloride inhibited H2O2-induced membrane current increases and [Ca2+](i) elevation. A high concentration (1 mmol/L)of H2O2 induced an additional transient elevation of [Ca2+](i), which was abolished by the specific PLC blocker U73122 but was not eliminated by removal of extracellular Ca2+. PLC activity was increased by 1 mmol/L H2O2 but not by 400 micromol/L H2O2.

CONCLUSIONS

H2O2 mobilizes Ca2+ through two distinct mechanisms. In one, 400 micromol/L H2O2-induced sustained [Ca2+](i) elevation is mediated via a Ca2+ influx mechanism, under which H2O2 impairs mitochondrial function via oxidative stress,reduces intracellular ATP production, and in turn opens ATP-sensitive, non-specific cation channels, leading to Ca2+ influx.In contrast, 1 mmol/L H2O2-induced transient elevation of [Ca2+](i) is mediated via activation of the PLC signaling pathway and subsequently, by mobilization of Ca2+ from intracellular Ca2+ stores.

Oxidative stress profile in the post-operative patients with biliary atresia

BACKGROUND AND PURPOSE

Many post-operative patients with biliary atresia (BA) suffer from liver dysfunction, such as chronic inflammation even without jaundice after a Kasai's hepatic portoenterostomy.

METHODS

The presence and degree of oxidative stress were evaluated in the post-operative patients with BA. Twelve outpatients who underwent a Kasai's hepatic portoenterostomy were evaluated. The active oxygen products, the rate of bioantioxidant, the markers of oxidative stress, and the degree of hepatic oxidative stress were examined by immunohistochemical staining of biopsied specimens.

RESULTS

All of the oxidative stress markers in the post-operative patients with BA increased in comparison to those in the controls. Moreover, 8-OHdG immunohistochemical staining was positive in 84+/-4.8% in hepatic cells in the portal area in the post-operative patients with BA.

CONCLUSION

The post-operative patients with BA were under increased oxidative stress, even if their liver dysfunction was mild without jaundice. Antioxidant therapy might be necessary to decrease of oxidative stress in the post-operative patients with BA.

Highly passage of Spodoptera litura cell line causes its permissiveness to baculovirus infection

It is well known that the characteristics of cell lines possibly alter when cell lines are at high-passage number because of the environmental selection. We do not know whether non-permissive or low-permissive cell lines could become permissive or more permissive to virus infection after over-high passage. In the present studies, the alteration of the permissiveness of Spodoptera litura cell line Sl-zsu-1 to three baculovirus infection was investigated after over-high passage, and the possible mechanisms are also investigated. Vigorous apoptosis in Sl-zsu-1 cells was induced by both the recombinant Autographa californica multiple nucleopolyhedrovirus AcMNPV-GFP-actin and the celery looper Anagrapha falcifera multiple nucleopolyhedrovirus AfMNPV, suggesting the replication of the two viruses was blocked by apoptosis. However, the cells infected by S. litura multicapsid nucleopolyhedrovirus SpltMNPV did not undergo apoptosis, but the SpltMNPV titre of the supernatant was not detectable, suggesting this cell line was low-permissive for this virus infection and other factor(s) involved in blockage of the virus replication except apoptosis. However, when Sl-zsu-1 cells had been subcultured continuously for more than 4 years (high-passage cell), which was named as Sl-HP cell line afterwards, no significant apoptosis was induced by the three baculovirus in Sl-HP cells, and many replicated virions or nucleocapsids were observed in the cells. But the permissiveness of Sl-HP cells to the three viruses was very different according to the titre of viruses in the cell cultures. Interestingly, the DNA extracted from SpltMNPV could induce vigorous apoptosis of Sl-HP cells. Altogether, Sl-zsu-1 cell line becomes more permissive to baculovirus infection after over-high passage and multiple paths can block the baculovirus infectivity.

Protective effect of prednisolone on ischemia-induced liver injury in rats

AIM: To investigate the effects of prednisolone on cell membrane bleb formation, calpain &mgr; activation and talin degradation during hepatic ischemia-reperfusion injury in rats.

METHODS: The hilar area of the left lateral and median lobes of rat liver (68%) was clamped for 60 min and followed by 120 min reperfusion. Prednisolone was administered at 1.0, 3.0, or 10 mg/kg at 30 min before ischemia. In addition to biochemical and microscopic analyses, activation of calpain &mgr; was determined using specific antibodies against the intermediate (activated) form of calpain &mgr;. Degradation of talin was also studied by Western blotting.

RESULTS: In the control and prednisolone (1.0 mg/kg) groups, serum aspartate transaminase (AST) and alanine transaminase (ALT) level were elevated, and cell membrane bleb formation was observed after 120 min of reperfusion. Moreover, calpain &mgr; activation and talin degradation were detected. Infusion of prednisolone at 3.0 or 10 mg/kg significantly suppressed serum AST and ALT, and prevented cell membrane bleb formation. At 10 mg/kg, prednisolone markedly suppressed calpain &mgr; activation and talin degradation.

CONCLUSION: Prednisolone can suppress ischemia-reperfusion injury of the rat liver. Its cytoprotective effect is closely associated with the suppression of calpain &mgr; activation and talin degradation.

Cytotoxic effects of 3,4-methylenedioxy-N-alkylamphetamines, MDMA and its analogues, on isolated rat hepatocytes

The amphetamine-derived designer drugs have been illegally used worldwide as recreational drugs, some of which are known to be hepatotoxic in humans. To compare their cytotoxic effects, 3,4-methylenedioxy-N-methamphetamine (MDMA) and its related analogues, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB), 3,4-(methylenedioxyphenyl)-2-butanamine (BDB) and 2-methylamino-1-(3,4-methylenedioxyphenyl)-propane-1-one (methylone) were studied in freshly isolated rat hepatocytes. MBDB caused not only concentration (0-4.0 mM)- and time (0-2 h)-dependent cell death accompanied by the formation of cell blebs, and the loss of cellular ATP and adenine nucleotide pools, and reduced glutathione levels, but also the accumulation of oxidized glutathione. Of the other analogues examined, the cytotoxicity of MBDB and BDB was greater than that of MDMA and methylone, suggesting that hepatotoxicity is generally induced by these drugs. In addition, DNA damage and the induction of reactive oxygen species were greater after the incubation of hepatocytes with MBDB (2 and 4 mM) than after that with MDMA. In isolated liver mitochondria, MBDB/BDB resulted in a greater increase in the rate of state 4 oxygen consumption than did MDMA/methylone, indicating an uncoupling effect and a decrease in the rate of state 3 oxygen consumption in a concentration dependent manner. Furthermore, MBDB resulted in mitochondrial swelling dependent on the mitochondrial permeability transition (MPT); the effect of MDMA was less than that of MBDB. Taken collectively, these results suggest that (1) the onset of cytotoxicity caused by designer drugs such as MBDB and MDMA is linked to mitochondrial failure dependent upon the induction of the MPT accompanied by mitochondrial depolarization and depletion of ATP through uncoupling of oxidative phosphorylation in rat hepatocytes, and (2) MBDB and MDMA elicit DNA damage, suggesting that nuclei as well as mitochondria are target sites of these compounds.

The impact of postreperfusion syndrome on short-term patient and liver allograft outcome in patients undergoing orthotopic liver transplantation

The greatest part of liver allograft injury occurs during reperfusion, not during the cold ischemia phase. The aim of this study, therefore, was to investigate how the severity of postreperfusion syndrome (PRS) influences short-term outcome for the patient and for the liver allograft. Over a 2-year period, 338 consecutive patients who presented for orthotopic liver transplantation (OLT) were included in this retrospective study. They were divided into 2 groups according to the severity of the PRS they experienced. The first group comprised 152 patients with mild or no PRS; the second group comprised 186 patients with significant PRS. Perioperative hemodynamic parameters, coagulation profiles, blood product requirements, incidence of infection, incidence of rejection and outcome data for both groups were collected and analyzed. There was no demographic difference between the groups except for age; group 2 had older patients than group 1 (54.94 +/- 9.07 versus 51.52 +/- 9.91, P = 0.001). Compared to group 1, group 2 patients required more red blood cell transfusions (11.31 +/- 10.90 versus 8.08 +/- 7.89 units, P = 0.002), more fresh frozen plasma transfusions (10.25 +/- 10.96 versus 7.03 +/- 7.64 units, P = 0.002), more cryoprecipitate (1.88 +/- 4.72 units versus 0.61 +/- 1.80 units, P = 0.001), and were more likely to suffer from fibrinolysis (52.7% versus 41.4%, P = 0.041). Interestingly, group 2 had a shorter average warm ischemia time than group 1 (33.19 +/- 8.55 versus 36.21 +/- 11.83 minutes, P = 0.01). Group 2 also required longer, on average, mechanical ventilation (14.95 +/- 29.79 versus 8.55 +/- 17.79 days, P = 0.015), remained in the intensive care unit longer (17.65 +/- 31.00 versus 11.49 +/- 18.67 days, P = 0.025), and had a longer hospital stay (27.29 +/- 32.35 versus 20.85 +/- 21.08 days, P = 0.029). Group 2 was more likely to require retransplantation (8.6% versus 3.3%, P = 0.044). In conclusion, the severity of PRS during OLT appears to be related to the outcome of patient and liver allograft.

Combined effects of vitamin C, vitamin E, and sodium selenate supplementation on absolute ethanol-induced injury in various organs of rats

In this study, the effect of combination of vitamin C (ascorbic acid), vitamin E (alpha -tocopherol), and selenium (sodium selenate) on ethanol-induced liver and intestine injury in rats was investigated. The ethanol-induced injury was produced by the administration of 1 ml of absolute ethanol to each rats. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg), and sodium selenate (Se) (0.5 mg/kg) for 3 days; 1 h after the final antioxidant administration, they were sacrificed. Lipid peroxidation and glutathione levels, catalase (CAT), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and glutathione peroxidase (GP(x)) activities were determined in liver and intestine tissues. Myeloperoxidase (MPO), aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT) were determined in liver tissue. Also, CAT activity, urea, creatinine, uric acid, and total lipid levels were determined in serum samples. In the ethanol group, serum urea, creatinine, uric acid, and total lipid levels; liver and intestine LDH; liver MPO, AST, ALP, ALT, and GGT activities; and liver and intestine LPO levels increased, whereas serum CAT activity, liver and intestine GSH levels, and CAT, SOD, and GP(x) activities decreased. On the other hand, treatment with vitamin C, vitamin E, and Se reversed these effects. As a result of these findings, we can say that the combination of vitamin C, vitamin E, and selenium has a protective effect on ethanol-induced changes in lipid peroxidation, glutathione levels, and antioxidant enzyme activities in liver and intestine tissues, and in some serum parameters of rats.

Biomarkers of tissue injury

Biomarkers of tissue injury have evolved empirically over the last 50–100 years. With the advent of immunoassays and discovery tools such as RNA expression and proteomics, more systematic approaches to the discovery of biomarkers can be expected in the future. This review discusses the evolution of biomarkers of muscle, liver, heart and brain injury and illustrates that a modern discovery tool, such as mRNA profiling, would have predicted the biomarkers for cardiac injury (heart attacks) that actually evolved over 50 years by empiric approaches. We also discuss how novel biomarkers for brain injury were identified using RNA expression approaches. It is our prediction that there will be a growth in the number of valuable biomarkers for identifying cell and organ injury in the next 5–10 years.

Modification of the hepatic mitochondrial proteome in response to ischemic preconditioning following ischemia-reperfusion injury of the rat liver

BACKGROUND/AIM

Ischemic preconditioning (IPC) may reduce hepatic ischemia-reperfusion (IR) injury, but efficacy of IPC on mitochondrial proteome is not demonstrated. We investigated how IPC modifies the mitochondrial proteome after IR injury.

METHODS

Rats were subjected to 25 min of portal triad crossclamping (IR group, n = 8). In the IPC group (n = 8), 10 min of temporal portal triad clamping was performed before 25 min of portal clamping. Samples were obtained after 24 h. The mitochondrial inner-membrane potential was measured by the uptake of a lipophilic cationic carbocyanine probe and mitochondrial proteome was also investigated using 2-dimensional differential in-gel electrophoresis and liquid chromatography-tandem mass spectrometry.

RESULTS

Mitochondrial inner-membrane potential and glutathione were lower and serum transaminase was higher in the IPC group than in the IR group. The mitochondrial precursor of aldehyde dehydrogenase 2 and alpha-methylacyl-CoA-racemase were upregulated in the IPC group in comparison to the IR group. In contrast, protein disulfide-isomerase A3 precursor, 60S acid ribosomal protein P0, carbonic anhydrase 3 and superoxide dismutase were significantly more downregulated in the IPC group than in the IR group.

CONCLUSIONS

A hepatoprotective effect by IPC was not shown; however, IPC caused significant up- or downregulation of several mitochondrial proteins.

Heat shock induced apoptosis in normal and tumor human umbilical vein cells (HUVECs)

Human endothelial cell injury may play an important role tumor damage hyperthermia in vivo. In this study, human umbilical vein cells were heat shocked in vitro at different temperatures (41-55 degrees C). Cells were observed 0, 12, 24, 36, 48, 60 and 72 hours after heat shock. By incrementally increasing the heat load from 41-55 degrees C, we observed a gradually increase in apoptosis with a significant change from apoptotic to necrotic death at temperature beyond 45 degrees C. Further, an in vitro human breast tumor endothelial cell model was established to compare the heat shock response between normal and tumor endothelial cells.

Metformin promotes isolated rat liver mitochondria impairment

Metformin, a drug widely used in the treatment of type 2 diabetes, has recently received attention due to the new and contrasting findings regarding its effects on mitochondrial function. In the present study, we evaluated the effect of metformin in isolated rat liver mitochondria status. We observed that metformin concentrations > or =8 mM induce an impairment of the respiratory chain characterized by a decrease in RCR and state 3 respiration. However, only metformin concentrations > or =10 mM affect the oxidative phosphorylation system by decreasing the mitochondrial transmembrane potential and increasing the repolarization lag phase. Moreover, our results show that metformin does not prevent H(2)O(2) production, neither protects against lipid peroxidation induced by the pro-oxidant pair ADP/Fe(2+). In addition, we observed that metformin exacerbates Ca(2+)-induced permeability transition pore opening by decreasing the capacity of mitochondria to accumulate Ca(2+ )and increasing the oxidation of thiol groups. Taken together, our results show that metformin can promote liver mitochondria injury predisposing to cell death.

Inflammatory cytokines induce MAdCAM-1 in murine hepatic endothelial cells and mediate alpha-4 beta-7 integrin dependent lymphocyte endothelial adhesion in vitro

Background

MAdCAM-1 plays a central role in T-lymphocyte homing to the gut, but its role in chronic liver inflammation remains unknown. Therefore, this study measured MAdCAM-1 expression, regulation, and function in cultured murine hepatic endothelial cells.

Methods

Cultures of hepatic endothelial cells (HEC) were prepared from mice expressing a temperature-sensitive SV40 large T antigen (H-2K^b-tsA58) under the control of an IFN-γ promoter. Time and dose dependent expression of MAdCAM-1 in response to TNF-α, IL-1β and IFN-γ was studied by immunoblotting. Lymphocyte adhesion was studied using α₄β₇integrin expressing lymphocytes (TK-1) +/- anti-MAdCAM-1 mAb.

Results

TNF-α induced MAdCAM-1 dose-and time-dependently with maximum expression at 20 ng/ml and at 48 hours. IL-1β also induced MAdCAM-1 to a lesser extent compared to TNF-α; IFN-γ did not induce MAdCAM-1. TNF-α significantly increased lymphocyte-endothelial adhesion (P < 0.01), which was reversed by anti-MAdCAM-1 antibody. MAdCAM-1 expression was also reduced by N-acetylcysteine and by two NO donors (SperNO, DETANO) suggesting that hepatic endothelial MAdCAM-1 is oxidant and NO regulated.

Conclusion

MAdCAM-1 is a major determinant of leukocyte recruitment in chronic inflammation and is expressed by HEC in response to IL-1β and TNF-α. This system may provide a useful model for studying inflammatory mechanisms in liver disease and help determine if controlled MAdCAM-1 expression might influence inflammation in liver disease.

Does l-carnitine have any effect on cold preservation injury of non-fatty liver in the University of Wisconsin solution?

AIM

To evaluate the protective effect of l-carnitine on liver tissue preserved in University of Wisconsin (UW) solution.

METHODS

Twenty Wistar Albino rats were divided into two groups, a control (UW) group and a UW plus l-carnitine group. Retrieved liver grafts were preserved in UW and UW plus l-carnitine solutions at +4 degrees C. Preservation solution samples were assessed at 2, 24, 36, and 48 h to measure alanine aminotransferase and acid phosphatase activity. Tissue injury was scored on paraffin sections.

RESULTS

No micro or macrovacuolar fat droplets were observed in the tissue slices. l-Carnitine effectively decreased enzyme release when added to UW solution (P < 0.05).

CONCLUSION

In addition to fatty liver, l-carnitine might be a metabolic adjunct in preservation solutions for non-fatty liver within UW solution.

The response of the hepatocyte to ischemia

BACKGROUND

Ischemia-reperfusion (I/R) injury associated with hepatic resections and liver transplantation remains a serious complication in clinical practice, in spite of several attempts to solve the problem.

AIMS

To evaluate the response of the hepatocyte to ischemia

METHODS

Published data are thus revised.

RESULTS

The response of the hepatocyte to ischemia is based on the sensitivity of hepatocytes to different types of ischemia, the kind of cell death of the hepatocyte when it is subjected to ischemia, and on the response of the hepatocyte to the different times and extents of ischemia. Clinical factors including starvation, graft, age, and hepatic steatosis, all of which contribute to enhancing liver susceptibility to ischemia/reperfusion injury.

CONCLUSION

Ischemic preconditioning, based on the induction of a brief ischemia to the liver prior to a prolonged ischemia, has been applied in tumor hepatic resections for reducing hepatic I/R injury and recent clinical studies suggest that this surgical strategy could be appropriate for liver transplantation.

Steatosis as a risk factor in liver surgery

OBJECTIVE

To review present knowledge of the influence of hepatic steatosis in liver surgery as derived from experimental and clinical studies.

SUMMARY BACKGROUND DATA

Hepatic steatosis is the most common chronic liver disease in the Western world, and it is associated with obesity, diabetes, and metabolic syndrome. Fatty accumulation affects hepatocyte homeostasis and potentially impairs recovery of steatotic livers after resection. This is reflected clinically in increased mortality and morbidity after liver resection in patients with any grade of steatosis. Because of the epidemic increase of obesity, hepatic steatosis will play an even more significant role in liver surgery.

METHODS

A literature review was performed using MEDLINE and key words related to experimental and clinical studies concerning steatosis.

RESULTS

Experimental studies show the increased vulnerability of steatotic livers to various insults, attributed to underlying metabolic and pathologic derangements induced by fatty accumulation. In clinical studies, the severity of steatosis has an important impact on patient outcome and mortality. Even the mildest form of steatosis increases the risk of postoperative complications.

CONCLUSIONS

Hepatic steatosis is a major factor determining patient outcome after surgery. Further research is needed to clarify the clinical relevance of all forms and severity grades of steatosis for patient outcome. Standardized grading and diagnostic methods need to be used in future clinical trials to be able to compare outcomes of different studies.

Intralipid minimizes hepatocytes injury after anoxia-reoxygenation in an ex vivo rat liver model

OBJECTIVE

Ischemia-reperfusion injury is a determinant in liver injury occurring during surgical procedures, ischemic states, and multiple organ failure. The pre-existing nutritional status of the liver, i.e., fasting, might contribute to the extent of tissue injury. This study investigated whether Intralipid, a solution containing soybean oil, egg phospholipids, and glycerol, could protect ex vivo perfused livers of fasting rats from anoxia-reoxygenation injury.

METHODS

The portal vein was cannulated, and the liver was removed and perfused in a closed ex vivo system. Isolated livers were perfused with glucose 5.5 and 15 mM, and two different concentrations of Intralipid, i.e., 0.5:100 and 1:100 (v/v) Intralipid 10%:medium (n = 5 in each group). The experiment consisted of perfusion for 15 min, warm anoxia for 60 min, and reoxygenation during 60 min. Hepatic enzymes, potassium, glucose, lactate, bilirubin, dienes, trienes, and cytochrome-c were analyzed in perfusate samples. The proportion of glycogen in hepatocytes was determined in biopsies.

RESULTS

Intralipid attenuated transaminases, lactate dehydrogenase, potassium, diene, and triene release in the perfusate (dose-dependant) during the reoxygenation phase when compared with glucose-treated groups. The concentration of cytochrome-c in the medium was the highest in the 5.5-mM glucose group. The glycogen content was low in all livers at the start of the experiment.

CONCLUSION

Intralipid presents, under the present experimental conditions, a better protective effect than glucose in anoxia-reoxygenation injury of the rat liver.

Necrotic death without mitochondrial dysfunction-delayed death of cardiac myocytes following oxidative stress

Oxidative stress has been implicated in cell death in range of disease states including ischemia/reperfusion injury of the heart and heart failure. Here we have investigated the mechanisms of cell death following chronic exposure of cardiac myocytes to oxidative stress initiated by hydrogen peroxide. This exposure induced a delayed form of cell death with ultrastructural changes typical of necrosis, and that was accompanied by the release of lactate dehydrogenase and increased lipid peroxidation. However, this delayed death was not accompanied by the loss of mitochondrial membrane potential or caspase-3 activation. Furthermore, we could demonstrate that this delayed necrosis was at least partially prevented by pre-treatment with the hypertrophic stimuli endothelin-1 or leukemic inhibitory factor. Our results suggest that this delayed form necrosis may also comprise an ordered series of events involving pathways amenable to therapeutic modulation.

El preacondicionamiento isquémico del hígado: de las bases moleculares a la aplicación clínica

Ischemia-reperfusion injury is produced when an organ is deprived of blood flow (ischemia), which is then restored (reperfusion). In certain circumstances, this injury leads to irreversible organ damage. Several therapeutic strategies have been used to reduce the severity of this injury. One of these strategies is the application of brief and repetitive episodes of ischemia-reperfusion before prolonged ischemia-reperfusion (ischemic preconditioning). In the present article we review the molecular mechanisms through which ischemic preconditioning confers protection against ischemia-reperfusion injury. The application of ischemic preconditioning during liver surgery is discussed, both in normothermic situations such as liver resection and in situations of low temperature such as liver transplantation.

Lack of a Protective Effect of Insulin on Three Reperfusion-Liver Injury Models in Rats and Mice

Our objective was to investigate the potential protective effects of insulin on the liver injury induced in three ischemia and reperfusion (I/R) models.

METHODS

Three I/R models were used: (1) I/R of the liver was produced in isolated, perfused rat livers; (2) in in situ I/R of the liver in rats, ischemia was induced by clamping off the hepatic artery and portal vein for 40 minutes, the flow then restored, and the liver reperfused for 90 minutes; (3) in in situ I/R of the liver in mice, ischemia was induced by clamping off the hepatic artery for 15 minutes, the flow then restored, and the liver reperfused for 45 minutes. In all three cases, blood samples collected before ischemia and after reperfusion were analyzed for sGOT. Plasma nitrate/nitrite, hydroxyl radicals, and tumor necrosis factor were also measured. In each model, a dose of insulin sufficient to induce euglycemia was administered to assess its protective effect on liver injury and inflammation.

RESULTS

These I/R protocols resulted in a significant increase in sGOT and in three inflammatory parameters; nitric oxide, hydroxyl radicals, and tumor necrosis factor. Pretreatment with insulin did not attenuate the liver injury in any of the three I/R models.

CONCLUSIONS

Although insulin has been reported to provide anti-inflammatory benefits by reducing oxidative and nitrosative stress and cytokine release, none of these protective effects was seen in the three I/R-induced liver injury models we tested.

[Ischemia-reperfusion syndrome associated with liver transplantation: an update]

Ischemia-reperfusion (I/R) injury is the main cause of both initial graft dysfunction and primary failure in liver transplantation. The search for therapeutic strategies to prevent I/R injury has led to research into promising drugs, although most have not been used clinically. Gene therapy requires better transfection techniques, avoiding vector toxicity, and ethical debate before being used clinically. Ischemic preconditioning is the first therapeutic strategy used in clinical practice to reduce I/R injury in hepatectomies for tumors. Future research will provide data on the effectiveness of ischemic preconditioning in reducing I/R injury associated with liver transplantation, and in reducing the vulnerability of steatotic grafts to I/R syndrome so that they can be used in transplantation, thus relieving the organ shortage.

Mechanisms of interleukin-6 protection against ischemia-reperfusion injury in rat liver

Numerous animal studies simulating liver injury have demonstrated that interleukin-6 (IL-6) exerts a protective effect. This study was designed to further analyze the molecular mechanisms underlying the protective role of IL-6 in a rat model of liver ischemia/reperfusion injury. We show that IL-6: (i) at high doses reduces cell damage which occurs in ischemic-reperfused liver, while at low doses displays only a limited protective capacity, (ii) anticipates and enhances hepatocyte compensatory proliferation seen in ischemic-reperfused liver also at a low, more pharmacologically acceptable dose, (iii) sustains the acute phase response which is dampened in ischemic-reperfused liver, (iv) strengthens the heat shock-stress response shown by ischemic-reperfused liver and (v) overcomes the dysfunctions of the unfolding protein response found in ischemic-reperfused liver. We also show that IL-6-enhanced STAT3 activation probably plays a crucial role in the potentiation of the different protective pathways activated in ischemic-reperfused liver. Our data confirm that IL-6 is a potential therapeutic in liver injury of different etiologies and reveal novel mechanisms by which IL-6 sustains liver function after ischemia/reperfusion injury.

Sodium as the major mediator of NO-induced cell death in cultured hepatocytes

NO has been shown to induce cellular injury via inhibition of the mitochondrial respiratory chain and/or oxidative/nitrosative stress. Here, we studied which mechanism and downstream mediator is responsible for NO toxicity to hepatocytes. When cultured rat hepatocytes were incubated with spermineNONOate (0.01-2 mM) at 2, 5, 21 and 95% O(2) in Krebs-Henseleit buffer (37 degrees C), spermineNONOate caused concentration-dependent hepatocyte death (lactate dehydrogenase release, propidium iodide uptake) with morphological features of both apoptosis and necrosis. Increasing O(2) concentrations protected hepatocytes from NO-induced injury. Steady-state NO concentrations were lower at higher O(2) concentrations, suggesting formation of reactive nitrogen oxide species. Despite this, the scavenger ascorbic acid was hardly protective. In contrast, at equal NO concentrations loss of viability was higher at lower O(2) concentrations and inhibitors of hypoxic injury, fructose and glycine (10 mM), strongly decreased NO-induced injury. Upon addition of spermineNONOate, the cytosolic Na(+) concentration rapidly increased. The increase in sodium depended on the NO/O(2) ratio and was paralleled by hepatocyte death. Sodium-free Krebs-Henseleit buffer strongly protected from NO-induced injury. SpermineNONOate also increased cytosolic calcium levels but the Ca(2+) chelator quin-2-AM did not diminish cell injury. These results show that - in analogy to hypoxic injury - a sodium influx largely mediates the NO-induced death of cultured hepatocytes. Oxidative stress and disturbances in calcium homeostasis appear to be of minor importance for NO toxicity to hepatocytes.

The Protective Effect of α-Tocopherol and GdCl3 Against Hepatic Ischemia/Reperfusion Injury

PURPOSE

To evaluate the combined effect of alpha-tocopherol and gadolinium chloride (GdCl3) in reducing lipid peroxidation after severe hepatic ischemia/reperfusion (IR) injury.

METHODS

Sixty male Wistar rats, 200-250 g, were randomly divided into six equal groups. There were two sham operation (SHAM) groups, two untreated IR groups, and two IR groups treated with GdCl3 and alpha-tocopherol (IRGT). After 60 min of total hepatic ischemia and 120 min reperfusion, one of each group was killed, liver samples were taken for malondialdehyde (MDA) and myeloperoxidase (MPO) analysis and light microscopy examination, and blood samples were analyzed for aspartate (AST) and alanine (ALT) transaminase, lactate dehydrogenase (LDH), and alpha-tocopherol content. The remaining groups were monitored for survival rate determination.

RESULTS

The mean MDA and MPO values in the SHAM, IR, and IRGT groups, respectively, were 1.117, 1.476, and 0.978 nmol/g wet tissue and 1.49, 6.26, and 1.78 (U/g). The mean alpha-tocopherol values in the SHAM, IR, and IRGT groups, respectively, were 10.4, 1.9, and 12 micromol/l. The mean serum AST, ALT, and LDH values were significantly higher in the IR group than in the SHAM group (P < 0.001), and significantly lower in the IRGT group than in the IR group (P < 0.001). Light microscopy examination revealed more severe congestion and vacuolization in the IR group than in the SHAM group, and minimal congestion and vacuolization in the IRGT group. Survival was significantly higher in the IRGT group than in the IR group.

CONCLUSION

The administration of GdCl3 and alpha-tocopherol is likely to protect the liver against lipid peroxidation by suppressing Kupffer cell and polymorphonuclear leukocyte activation and enhancing endogenous antioxidant activity.

Histochemical analyses of living mouse liver under different hemodynamic conditions by "in vivo cryotechnique"

Although the morphology and molecular distribution in animal liver tissues have been examined using conventional preparation methods, the findings are always affected by the technical artifacts caused by perfusion-fixation and tissue-resection. Using "in vivo cryotechnique" (IVCT), we have examined living mouse livers with histochemical, immunohistochemical and ultrastructural analyses. In samples prepared by IVCT, widely open sinusoids with many flowing erythrocytes were observed under normal blood circulation, and their collapse or blood congestion was seen in ischemic or heart-arrested mice. In contrast, the sinusoidal cavities were artificially dilated by perfusion-fixation, and collapsed by immersion-fixation and quick-freezing (QF) methods of resected tissues. The immunoreactivity of serum albumin and immunoglobulin G and intensity of periodic acid-Schiff-staining in hepatocytes were well preserved with the QF method and IVCT. Furthermore, following tissue resection, serum proteins were rapidly translocated into hepatocytes as demonstrated by immunoreactions on QF tissues frozen 1 or 5 min after resection. Translocation was not observed in IVCT samples, indicating that IVCT could be useful to examine cell membrane permeability of hepatocytes under different pathological conditions. Both dynamic morphology and immunodistribution of soluble components in living mouse livers, reflecting their physiological and pathological states, can be precisely examined by IVCT with higher time-resolution.

Effect of hyperbaric oxygen on cold storage of the liver in rats

BACKGROUND

The depletion of biochemical energy stores during prolonged cold storage is one of the most critical events of cold ischemia-reperfusion (CI/R) injury. The aim of this study was to evaluate the effect of hyperbaric oxygen (HBO) treatment on CI/R injury.

METHODS

Livers were harvested from male Wistar rats and stored for 24 h at 4 degrees C in University of Wisconsin solution (Group 1). Others were additionally treated with HBO during the preservation period (Group 2). At the end of the 24 h cold preservation, the concentrations of hepatic enzymes and lipid peroxidation (LPO) in the effluent and the hepatic adenosine triphosphate (ATP) levels were measured. After preservation, the livers were reperfused for 90 min with an oxygenated Krebs-Henseleit bicarbonate buffer. Perfusate samples were obtained serially, and portal flow rates were also recorded.

RESULTS

In group 2, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and LPO into the effluent at the end of preservation were decreased and the depletion of ATP was prevented (P<0.05). After reperfusion, the portal flow was significantly improved in group 2 (P<0.05). The time-dependent increase of alanine aminotransferase levels (ALT) observed in group 1 was suppressed significantly in group 2, and total bile production during 90 min of reperfusion was significantly greater in group 2 (P<0.05). The structure of the livers in group 2 was significantly well maintained, and the liver weight change ratio was significantly greater in group 1 (P<0.05).

CONCLUSIONS

HBO treatment during cold storage seems to prevent hepatic ischemic injury and have protective effects against CI/R injury by attenuating the depletion of energy stores.

Protective effect of volatile oil, alcoholic and aqueous extracts of Origanum majorana on lead acetate toxicity in mice

Natural dietary antioxidants are extensively studied for their ability to protect cells from miscellaneous damages. Origanum majorana L., Lamiaceae, is a potent antioxidant. The effect of administration of O. majorana (volatile oil, alcoholic and aqueous extracts) on oral administration of lead acetate in the diet of mice at concentration 0.5% (W/W) for one month were studied by measuring serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), urea and creatinine, histopathological changes of the liver and kidney and genotoxicity including, rate of micronucleus and chromosomal aberrations in bone marrow cells. Mice were treated with the 3 different forms of O. majorana, one month before and maintained with lead acetate administration. The 3 forms of O. majorana induced a significant decrease in serum activities of transaminases (AST & ALT), ALP, urea and creatinine and improved the liver and kidney histology in comparison with lead acetate treated group. Alcoholic extracts of O. majorana significantly reduced the rate of micronucleus, number of aberrant cells and different kinds of chromosomal aberrations. Volatile oil extract significantly reduced the rate of micronucleus and chromosomal fragments. Aqueous extract and volatile oil also of O. majorana significantly reduced number of gaps, ring chromosome and stickiness. It could be concluded that O. majorana plays an important role in ameliorating liver and kidney functions and genotoxicity induced by lead toxicity.