Hypoxia inducible factor-1α accumulation in steatotic liver preservation: Role of nitric oxide

Open-Acces journal.-- et al.[Aim]: To examine the relevance of hypoxia inducible factor (HIF-1) and nitric oxide (NO) on the preservation of fatty liver against cold ischemia-reperfusion injury (IRI). Methods]: We used an isolated perfused rat liver model and we evaluated HIF-1α in steatotic and non-steatotic livers preserved for 24 h at 4°C in University of Wisconsin and IGL-1 solutions, and then subjected to 2 h of normothermic reperfusion. After normoxic reperfusion, liver enzymes, bile production, bromosulfophthalein clearance, as well as HIF-1α and NO [endothelial NO synthase (eNOS) activity and nitrites/nitrates] were also measured. Other factors associated with the higher susceptibility of steatotic livers to IRI, such as mitochondrial damage and vascular resistance were evaluated. [Results]: A significant increase in HIF-1α was found in steatotic and non-steatotic livers preserved in IGL-1 after cold storage. Livers preserved in IGL-1 showed a significant attenuation of liver injury and improvement in liver function parameters. These benefits were enhanced by the addition of trimetazidine (an antiischemic drug), which induces NO and eNOS activation, to IGL-1 solution. In normoxic reperfusion, the presence of NO favors HIF-1α accumulation, promoting also the activation of other cytoprotective genes, such as hemeoxygenase- 1. [Concluison]: We found evidence for the role of the HIF-1α/NO system in fatty liver preservation, especially when IGL-1 solution is used. © 2010 Baishideng.Supported by The Ministerio de de Sanidad y Consumo (PI 081988), CIBER-EHD, Instituto Carlos III, Madrid and Ministerio de Asuntos Exteriores y de Cooperación Internacionales (A/020255/08 and A/02987/09), MadridPeer Reviewe

Does Processing or Formation of Water Ice Mantles Affect the Capacity of Nanosilicates to Be the Source of Anomalous Microwave Emission?

Anomalous microwave emission (AME) is detected in many astrophysical environments as a foreground feature typically peaking between 20-30 GHz and extending over a 10-60 GHz range. One of the leading candidates for the source of AME is small spinning dust grains. Such grains should be very small (approx. ≤1 nm diameter) in order for the rotational emission to fall within the observed frequency range. In addition, these nanosized grains should possess a significant dipole moment to account for the observed emissivities. These constraints have been shown to be compatible with spinning bare nanosilicate clusters, assuming that ∼1% of the total Si mass budget is held in these ultrasmall grains. Silicate dust can be hydroxylated by processing in the interstellar medium and is generally known to provide seeds for molecular water ice nucleation in denser regions. Herein, we use quantum chemical calculations to investigate how the dipole moment of Mg-rich pyroxenic (MgSiO3) nanoclusters is affected by both accretion of molecular water and dissociative hydration. Our work thus provides an indication of how the formation of water ice mantles is likely to affect the capacity of nanosilicates to generate AME

Protective Effect of Intravenous High Molecular Weight Polyethylene Glycol on Fatty Liver Preservation

Ischemia reperfusion injury (IRI) leads to significant tissue damage in liver surgery. Polyethylene glycols (PEGs) are water soluble nontoxic polymers that have proved their effectiveness against IRI. The objective of our study was to investigate the potential protective effects of intravenous administration of a high molecular weight PEG of 35 kDa (PEG 35) in steatotic livers subjected to cold ischemia reperfusion. In this study, we used isolated perfused rat liver model to assess the effects of PEG 35 intravenous administration after prolonged cold ischemia (24 h, 4°C) and after reperfusion (2 h, 37°C). Liver injury was measured by transaminases levels and mitochondrial damage was determined by confocal microscopy assessing mitochondrial polarization (after cold storage) and by measuring glutamate dehydrogenase activity (after reperfusion). Also, cell signaling pathways involved in the physiopathology of IRI were assessed by western blot technique. Our results show that intravenous administration of PEG 35 at 10 mg/kg ameliorated liver injury and protected the mitochondria. Moreover, PEG 35 administration induced a significant phosphorylation of prosurvival protein kinase B (Akt) and activation of cytoprotective factors e-NOS and AMPK. In conclusion, intravenous PEG 35 efficiently protects steatotic livers exposed to cold IRI.Eirini Pantazi thanks the fellowship from AGAUR (2012FI_B00382), Generalitat de Catalunya, Barcelona, Catalonia, Spain. The authors would like to thank the Fondo de Investigaciones Sanitarias FIS PI12/00519; FIS PI15/00110 for the economic support.Peer Reviewe

Does previous abdominal surgery alter the outcome of pediatric patients subjected to orthotopic liver transplantation?

The medical, anesthesia, and surgical records of 89 consecutive pediatric patients who underwent an orthotopic hepatic transplantation procedure at the University of Pittsburgh from February 1981 to May 1984 were reviewed to evaluate the effect of prior abdominal surgery upon the morbidity and mortality of orthotopic liver transplantation in children. Fifty-seven children (group 1) had had prior abdominal surgery, whereas 32 (group 2) had not. The group 1 subjects were younger (p < 0.001), had better prothrombin times (p < 0.01), and better platelet counts (p < 0.02) than did those in group 2. No difference in the duration of anesthesia or intraoperative use of fresh frozen plasma or platelets was evident between the two groups. However, group 1 patients were given more red blood cells intraoperatively than were the group 2 patients (p < 0.01). The group 1 patients had more total postoperative infections (p < 0.05), which was due solely to a greater number of abdominal infections (p < 0.05), but similar total hospital and intensive care unit stays as did the group 2 patients. When those in group 1 were divided into those having a previous Kasai procedure versus those who did not, no differences between the two groups were apparent except for age. Based upon these data, we conclude that prior abdominal surgery does not affect mortality, the duration of hospital or intensive care unit stay, plasma or platelet requirements, and total anesthesia time required for orthotopic liver transplantation, but does enhance the number of red blood cell transfusions and infections, particularly abdominal infections, in children undergoing this procedure. © 1986

Endoplasmic reticulum stress inhibition protects steatotic and non-steatotic livers in partial hepatectomy under ischemia-reperfusion

During partial hepatectomy, ischemia-reperfusion (I/R) is commonly applied in clinical practice to reduce blood flow. Steatotic livers show impaired regenerative response and reduced tolerance to hepatic injury. We examined the effects of tauroursodeoxycholic acid (TUDCA) and 4-phenyl butyric acid (PBA) in steatotic and non-steatotic livers during partial hepatectomy under I/R (PH + I/R). Their effects on the induction of unfolded protein response (UPR) and endoplasmic reticulum (ER) stress were also evaluated. We report that PBA, and especially TUDCA, reduced inflammation, apoptosis and necrosis, and improved liver regeneration in both liver types. Both compounds, especially TUDCA, protected both liver types against ER damage, as they reduced the activation of two of the three pathways of UPR (namely inositol-requiring enzyme and PKR-like ER kinase) and their target molecules caspase 12, c-Jun N-terminal kinase and C/EBP homologous protein-10. Only TUDCA, possibly mediated by extracellular signal-regulated kinase upregulation, inactivated glycogen synthase kinase-3β. This is turn, inactivated mitochondrial voltage-dependent anion channel, reduced cytochrome c release from the mitochondria and caspase 9 activation and protected both liver types against mitochondrial damage. These findings indicate that chemical chaperones, especially TUDCA, could protect steatotic and non-steatotic livers against injury and regeneration failure after PH + I/R. © 2010 Macmillan Publishers Limited.This work was supported by the Ministerio de Educación y Ciencia (project grant SAF 2005-00385; project grant manager BFU2009-07410) (Madrid, Spain) and the Ministerio de Sanidad y Consumo (project grant PIO60021) (Madrid, Spain). Centro de Investigaciones Biomédicas Esther Koplowitz, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas is supported by the Instituto de Salud Carlos III (Spain).Peer Reviewe

Targeting cholesterol at different levels in the mevalonate pathway protects fatty liver against ischemia-reperfusion injury

El pdf del artículo es la versión post-print.Background & Aims: Liver steatosis enhances ischemia/reperfusion (I/R) injury and is considered a primary factor in graft failure after liver transplantation. Although previous reports have shown a role for qualitative steatosis (macrovesicular vs. microvesicular) in hepatic I/R injury, no studies have compared side by side the specific contribution of individual lipids accumulating in fatty liver to I/R damage. Methods: We used nutritional and genetic models of micro and macrovesicular fatty livers exhibiting specific lipid profiles to assess their susceptibility to normothermic I/R injury. Results: Unlike choline-deficient (CD) diet-fed mice, characterized by predominant liver triglycerides/free fatty acids (TG/FFA) accumulation, mice fed a cholesterol-enriched (HC) diet, which exhibited enhanced hepatic cholesterol loading in mitochondria, were highly sensitive to I/R-induced liver injury. In vivo two-photon confocal imaging revealed enhanced mitochondrial depolarization and generation of reactive oxygen species following hepatic I/R in HC-fed but not in CD-fed mice, consistent with decreased mitochondrial GSH (mGSH) observed in HC-fed mice. Moreover, ob/ob mice, characterized by increased hepatic TG, FFA, and cholesterol levels, were as sensitive to I/R-mediated liver injury as mice fed the HC diet. Livers from ob/ob mice displayed increased StAR expression and mitochondrial cholesterol accumulation, resulting in mGSH depletion. Interestingly, atorvastatin therapy or squalene synthase inhibition in vivo attenuated StAR overexpression, mitochondrial cholesterol loading, and mGSH depletion, protecting ob/ob mice from I/R-mediated liver injury. Conclusions: Cholesterol accumulation, particularly in mitochondria, sensitizes to hepatic I/R injury, and thus represents a novel target to prevent the enhanced damage of steatotic livers to I/R-mediated damage. © 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.The work was supported by grants SAF2006-06780, SAF2008-02199, SAF2008-04974 and SAF2009-11417 (Plan Nacional de I+D), PI070193 and PI09/00056 (Institut de Salud Carlos III), by CIBEREHD from the Institut Carlos III, the Fundación Mutua Madrileña and the center grant P50-AA-11999 Research Center for Liver and Pancreatic Diseases, US National Institute on Alcohol Abuse and Alcoholism, USA.Peer Reviewe

Document de consens per a la coinfecció pel Virus de la Immunodeficiència Humana i els Virus de les Hepatitis a Catalunya

VIH; Virus de les Hepatitis; CoinfeccióVIH; Virus de las Hepatitis; CoinfecciónHIV; Hepatitis virus; CoinfectionAquest manual ha estat preparat amb la intenció d'abordar els problemes que planteja el maneig de les persones malaltes amb coinfecció pel virus de la sida i els virus de l'hepatitis. A més, facilita als metges i metgesses assistencials els recursos necessaris per al diagnòstic i la presa de decisions terapèutiques, així com els criteris per ampliar la prevenció en tots aquells grups de població exposats a contraure aquestes infeccions.Este manual ha sido preparado con la intención de abordar los problemas que plantea el manejo de las personas enfermas con coinfección por el virus del sida y los virus de la hepatitis. Además, facilita a los médicos asistenciales los recursos necesarios para el diagnóstico y la toma de decisiones terapéuticas, así como los criterios para ampliar la prevención en todos aquellos grupos de población expuestos a contraer estas infecciones

Retinol binding protein 4 and retinol in steatotic and nonsteatotic rat livers in the setting of partial hepatectomy under ischemia/reperfusion

Steatotic livers show increased hepatic damage and impaired regeneration after partial hepatectomy (PH) under ischemia/reperfusion (I/R), which is commonly applied in clinical practice to reduce bleeding. The known function of retinol-binding protein 4 (RBP4) is to transport retinol in the circulation. We examined whether modulating RBP4 and/or retinol could protect steatotic and nonsteatotic livers in the setting of PH under I/R. Steatotic and nonsteatotic livers from Zucker rats were subjected to PH (70%) with 60 minutes of ischemia. RBP4 and retinol levels were measured and altered pharmacologically, and their effects on hepatic damage and regeneration were studied after reperfusion. Decreased RBP4 levels were observed in both liver types, whereas retinol levels were reduced only in steatotic livers. RBP4 administration exacerbated the negative consequences of liver surgery with respect to damage and liver regeneration in both liver types. RBP4 affected the mobilization of retinol from steatotic livers, and this revealed actions of RBP4 independent of simple retinol transport. The injurious effects of RBP4 were not due to changes in retinol levels. Treatment with retinol was effective only for steatotic livers. Indeed, retinol increased hepatic injury and impaired liver regeneration in nonsteatotic livers. In steatotic livers, retinol reduced damage and improved regeneration after surgery. These benefits of retinol were associated with a reduced accumulation of hepatocellular fat. Thus, strategies based on modulating RBP4 could be ineffective and possibly even harmful in both liver types in the setting of PH under I/R. In terms of clinical applications, a retinol pretreatment might open new avenues for liver surgery that specifically benefit the steatotic liver. Liver Transpl 18:1198-1208, 2012. (c) 2012 AASLD.Spanish Ministry of Science and Innovation [BFU2009-07410]Agency for the Innovation and Internationalization of Catalan Enterprise [VALTEC08-2-0033]Agency for the Support and Evaluation of Graduate Education (Brazilian Ministry of Education)Spanish Society for Liver Transplantation Foundatio

How Institut Georges Lopez preservation solution protects nonsteatotic and steatotic livers against ischemia-reperfusion injury

El pdf es la versión post-print.The Institut Georges Lopez preservation solution (IGL-1) is a serum-free organ preservative that has been shown to protect steatotic livers against hepatic ischemia-reperfusion injury. Although several hypotheses have been proposed to explain the graft protection mechanisms induced by IGL-1 solution, they have not been fully investigated. This review assessed possible IGL-1 mechanisms responsible for the increased liver tolerance of ischemia-reperfusion injury with special emphasis on vasodilatator mediators such as nitric oxide, on oxidative stress prevention, on protection against mitochondrial damage, and finally on induction of cytoprotective factors.This study was supported by the Ministerio de de Sanidad y Consumo (PI 081988), CIBER-ehd, Instituto Carlos III, Madrid and Ministerio de Asuntos Exteriores y de Cooperación Internacionales (A/02987/09 and A/031197/10), Madrid. M.A.Z. is fellowship holder from the Societat Catalana de Trasplantament.Peer Reviewe

Immunosuppression minimization vs. complete drug withdrawal in liver transplantation

SummaryDespite the increase in long-term survival, liver transplant recipients still exhibit higher morbidity and mortality than the general population. This is in part attributed to the lifelong administration of immunosuppression and its associated side effects. Several studies reported in the last decades have evaluated the impact of immunosuppression minimization in liver transplant recipients, but results have been inconsistent due to the heterogeneity of study designs and insufficient sample sizes. On the other hand, complete immunosuppression withdrawal has proven to be feasible in approximately 20% of carefully selected liver transplant recipients, especially in older patients and those with longer duration after transplantation. The long-term risks and clinical benefits of this strategy, however, also need to be clarified. As a consequence, and despite the general perception that a large proportion of liver recipients are over-immunosuppressed, it is currently not possible to derive evidence-based guidelines on how to manage long-term immunosuppression to improve clinical outcomes. Large clinical trials of drug minimization and/or withdrawal focused on clinically-relevant long-term outcomes are required. Development of personalized medicine tools and a deeper understanding of the pathogenesis of idiopathic inflammatory graft lesions will be pre-requisites to achieve these goals