New technologies - new insights into the pathogenesis of hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome which frequently accompanies acute or chronic liver disease. It is characterized by a variety of symptoms of different severity such as cognitive deficits and impaired motor functions. Currently, HE is seen as a consequence of a low grade cerebral oedema associated with the formation of cerebral oxidative stress and deranged cerebral oscillatory networks. However, the pathogenesis of HE is still incompletely understood as liver dysfunction triggers exceptionally complex metabolic derangements in the body which need to be investigated by appropriate technologies. This review summarizes technological approaches presented at the ISHEN conference 2014 in London which may help to gain new insights into the pathogenesis of HE. Dynamic in vivo13C nuclear magnetic resonance spectroscopy was performed to analyse effects of chronic liver failure in rats on brain energy metabolism. By using a genomics approach, microRNA expression changes were identified in plasma of animals with acute liver failure which may be involved in interorgan interactions and which may serve as organ-specific biomarkers for tissue damage during acute liver failure. Genomics were also applied to analyse glutaminase gene polymorphisms in patients with liver cirrhosis indicating that haplotype-dependent glutaminase activity is an important pathogenic factor in HE. Metabonomics represents a promising approach to better understand HE, by capturing the systems level metabolic changes associated with disease in individuals, and enabling monitoring of metabolic phenotypes in real time, over a time course and in response to treatment, to better inform clinical decision making. Targeted fluxomics allow the determination of metabolic reaction rates thereby discriminating metabolite level changes in HE in terms of production, consumption and clearance

On the Refractive Index of Ageing Dispersions of Laponite

Aqueous dispersion of Laponite at low ionic concentration is of interest since it undergoes structural evolution with respect to time, which is usually termed as ageing. In this work we study the refractive index behavior as a function of ageing time, concentration and temperature. We observed that the extended Lorenz-Lorentz equation fitted the refractive index dependence on concentration and temperature very well. The refractive index did not show any dependence on ageing time. However, the dependence of refractive index on concentration showed a marked change as the system underwent transition from an isotropic to a biphasic state. The slope of the refractive index-density data is remarkably close to that of water at all Laponite concentrations. In the context of transport phenomena, optical measurements such as interferometry can exploit the water-like behavior of Laponite dispersions.Comment: 13 pages, 3 figures, to appear in Applied Clay Scienc

Ammonia produces pathological changes in human hepatic stellate cells and is a target for therapy of portal hypertension

BACKGROUND AND AIMS: Hepatic stellate cells (HSCs) are vital to hepatocellular function and the liver response to injury. They share a phenotypic homology with astrocytes that are central in the pathogenesis of hepatic encephalopathy, a condition in which hyperammonemia plays a pathogenic role. This study tested the hypothesis that ammonia modulates human HSC activation in vitro and in vivo, and evaluated whether ammonia lowering, by using l-ornithine phenylacetate (OP), modifies HSC activation in vivo and reduces portal pressure in a bile duct ligation (BDL) model. METHODS: Primary human HSCs were isolated and cultured. Proliferation (BrdU), metabolic activity (MTS), morphology (transmission electron, light and immunofluorescence microscopy), HSC activation markers, ability to contract, changes in oxidative status (ROS) and endoplasmic reticulum (ER) were evaluated to identify effects of ammonia challenge (50 μM, 100 μM, 300 μM) over 24–72 h. Changes in plasma ammonia levels, markers of HSC activation, portal pressure and hepatic eNOS activity were quantified in hyperammonemic BDL animals, and after OP treatment. RESULTS: Pathophysiological ammonia concentrations caused significant and reversible changes in cell proliferation, metabolic activity and activation markers of hHSC in vitro. Ammonia also induced significant alterations in cellular morphology, characterised by cytoplasmic vacuolisation, ER enlargement, ROS production, hHSC contraction and changes in pro-inflammatory gene expression together with HSC-related activation markers such as α-SMA, myosin IIa, IIb, and PDGF-Rβ. Treatment with OP significantly reduced plasma ammonia (BDL 199.1 μmol/L ± 43.65 vs. BDL + OP 149.27 μmol/L ± 51.1, p <0.05) and portal pressure (BDL 14 ± 0.6 vs. BDL + OP 11 ± 0.3 mmHg, p <0.01), which was associated with increased eNOS activity and abrogation of HSC activation markers. CONCLUSIONS: The results show for the first time that ammonia produces deleterious morphological and functional effects on HSCs in vitro. Targeting ammonia with the ammonia lowering drug OP reduces portal pressure and deactivates hHSC in vivo, highlighting the opportunity for evaluating ammonia lowering as a potential therapy in cirrhotic patients with portal hypertension

Identification of potential serum peptide biomarkers of biliary tract cancer using MALDI MS profiling.

The aim of this discovery study was the identification of peptide serum biomarkers for detecting biliary tract cancer (BTC) using samples from healthy volunteers and benign cases of biliary disease as control groups. This work was based on the hypothesis that cancer-specific exopeptidase activities in serum can generate cancer-predictive peptide fragments from circulating proteins during coagulation

Reactive gamma-ketoaldehydes as novel activators of hepatic stellate cells in vitro

Aims: Products of lipid oxidation, such as 4-hydroxynonenal (4-HNE), are key activators of hepatic stellate cells (HSC) to a pro-fibrogenic phenotype. Isolevuglandins (IsoLG) are a family of acyclic γ-ketoaldehydes formed through oxidation of arachidonic acid or as by-products of the cyclooxygenase pathway. IsoLGs are highly reactive aldehydes which are efficient at forming protein adducts and cross-links at concentrations 100-fold lower than 4-hydroxynonenal. Since the contribution of IsoLGs to liver injury has not been studied, we synthesized 15-E2-IsoLG and used it to investigate whether IsoLG could induce activation of HSC. / Results: Primary human HSC were exposed to 15-E2-IsoLG for up to 48 hours. Exposure to 5 μM 15-E2-IsoLG in HSCs promoted cytotoxicity and apoptosis. At non-cytotoxic doses (50 pM-500 nM) 15-E2-IsoLG promoted HSC activation, indicated by increased expression of α-SMA, sustained activation of ERK and JNK signaling pathways, and increased mRNA and/or protein expression of cytokines and chemokines, which was blocked by inhibitors of JNK and NF-kB. In addition, IsoLG promoted formation of reactive oxygen species, and induced an early activation of ER stress, followed by autophagy. Inhibition of autophagy partially reduced the pro-inflammatory effects of IsoLG, suggesting that it might serve as a cytoprotective response. / Innovation: This study is the first to describe the biological effects of IsoLG in primary HSC, the main drivers of hepatic fibrosis. / Conclusions: IsoLGs represent a newly identified class of activators of HSC in vitro, which are biologically active at concentrations as low as 500 pM, and are particularly effective at promoting a pro-inflammatory response and autophagy

Circulating microRNAs Reveal Time Course of Organ Injury in a Porcine Model of Acetaminophen-Induced Acute Liver Failure

Acute liver failure is a rare but catastrophic condition which can progress rapidly to multi-organ failure. Studies investigating the onset of individual organ injury such as the liver, kidneys and brain during the evolution of acute liver failure, are lacking. MicroRNAs are short, non-coding strands of RNA that are released into the circulation following tissue injury. In this study, we have characterised the release of both global microRNA and specific microRNA species into the plasma using a porcine model of acetaminophen-induced acute liver failure. Pigs were induced to acute liver failure with oral acetaminophen over 19h±2h and death occurred 13h±3h thereafter. Global microRNA concentrations increased 4h prior to acute liver failure in plasma (P<0.0001) but not in isolated exosomes, and were associated with increasing plasma levels of the damage-associated molecular pattern molecule, genomic DNA (P<0.0001). MiR122 increased around the time of onset of acute liver failure (P<0.0001) and was associated with increasing international normalised ratio (P<0.0001). MiR192 increased 8h after acute liver failure (P<0.0001) and was associated with increasing creatinine (P<0.0001). The increase in miR124-1 occurred concurrent with the pre-terminal increase in intracranial pressure (P<0.0001) and was associated with decreasing cerebral perfusion pressure (P<0.002)

Apolipoprotein A-I: the dual face of a protein

Conformational plasticity and flexibility are key structural features of ApoAI in lipid metabolism. Amyloidogenic single point mutations, associated with incurable familial amyloidosis with fibril deposition in peripheral organs, may have a dramatic impact on the structural and functional features of ApoAI. Here, the consistent body of data on ApoAI variants has been reviewed, with the aim of highlighting the hallmarks of the pathology. In accordance with our observations, as well as that of others, we propose a model that accounts for the alteration of the delicate balance between lipid-free/lipid-bound dynamic states which is based on monomer-to-dimer interconversion via domain swapping

Procalcitonin as a Marker of Serious Bacterial Infections in Febrile Children Younger Than 3 Years Old

Objectives There is no perfectly sensitive or specific test for identifying young, febrile infants and children with occult serious bacterial infections ( SBI s). Studies of procalcitonin ( PCT ), a 116‐amino‐acid precursor of the hormone calcitonin, have demonstrated its potential as an acute‐phase biomarker for SBI . The objective of this study was to compare performance of serum PCT with traditional screening tests for detecting SBI s in young febrile infants and children. Methods This was a prospective, multicenter study on a convenience sample from May 2004 to December 2005. The study was conducted in four emergency departments ( ED s): one pediatric ED and three ED s with pediatric units, all with academic faculty on staff. A total of 226 febrile children 36 months old or younger who presented to the four participating ED s and were evaluated for SBI by blood, urine, and/or cerebral spinal fluid ( CSF ) cultures were included. Results The test characteristics (with 95% confidence intervals [CIs]) of the white blood cell (WBC) counts including neutrophil and band counts were compared with PCT for identifying SBI. Thirty children had SBIs (13.3%, 95% CI = 8.85 to 17.70). Four (13.3%) had bacteremia (including one with meningitis), 18 (60.0%) had urinary tract infections (UTIs), and eight (26.6%) had pneumonia. Children with SBIs had higher WBC counts (18.6 × 10 9  ± 8.6 × 10 9 cells/L vs. 11.5 × 10 9  ± 5.3 × 10 9 cells/L, p < 0.001), higher absolute neutrophil counts (ANCs; 10.6 × 10 9  ± 6.7 × 10 9 cells/L vs. 5.6 × 10 9  ± 3.8 × 10 9 cells/L, p = 0.009), higher absolute band counts (0.90 × 10 9  ± 1.1 × 10 9 cells/L vs. 0.35 × 10 9  ± 0.6 × 10 9 cells/L, p = 0.009), and higher PCT levels (2.9 ± 5.6 ng/ mL vs. 0.4 ± 0.8 ng/ mL , p = 0.021) than those without SBIs. In a multivariable logistic regression analysis, the absolute band count and PCT were the two screening tests independently associated with SBI, although the area under the receiver operating characteristic (ROC) curve for PCT was the largest (0.80, 95% CI = 0.71 to 0.89). Conclusions Procalcitonin is a more accurate biomarker than traditional screening tests for identifying young febrile infants and children with serious SBI s. Further study on a larger cohort of young febrile children is required to definitively determine the benefit of PCT over traditional laboratory screening tests for SBI s. Resumen Objetivos No existe un test con la sensibilidad o especificidad ideal es para identificar las infecciones bacterianas graves ( IBG ) ocultas en los niños durante su primera infancia con fiebre. Los estudios de procalcitonina ( PCT ), un precursor de 116‐aminoácidos de la hormona calcitonina, han demostrado su potencial como biomarcador de fase aguda para las IBG . El objetivo de este estudio es comparar el rendimiento de la PCT en plasma con las pruebas de despistaje tradicionales para la detección de IBG en los niños durante la primera infancia con fiebre. Metodología Estudio prospectivo multicéntrico en una muestra de conveniencia realizado de mayo de 2004 a diciembre realizado de 2005. Este estudio se llevó a cabo en cuatro servicios de urgencias ( SU ): un SU pediátrico y tres SU con unidades pediátricas, todos ellos con docentes universitarios en la plantilla. Se incluyeron 226 niños de 0 a 36 meses de edad con fiebre que acudieron a los cuatro SU participantes y se les evaluó para IBG mediante cultivos de sangre, orina y/o líquido cefalorraquídeo. Resultados Los resultados (con los intervalos de confianza [IC] al 95%) del número de leucocitos, incluyendo número neutrófilos y blastos, y de la PCT se compararon para identificar las IBG. Treinta niños tuvieron IBG (13,3%, IC 95% = 8,85 a 17,70). Cuatro (13,3%) tuvieron bacteremia (incluyendo uno con meningitis), 18 (60,0%) infección del tracto urinario y 8 (26,6%) neumonía. Los niños con IBG tuvieron mayor número de leucocitos (18.600 ± 8.600 cel/mm 3 vs. 11.500 ± 5.300 cel/mm 3 , p< 0,001), número absoluto de neutrófilos (NAN) (10.600 ± 6.700 cel/mm 3 vs. 5.600 ± 3.800 cel/mm 3 , p = 0,009), número absoluto de blastos (900 ± 1.100 cel/mm 3 vs. 350 ± 600 cel/mm 3 , p = 0,009) y valores de PCT (2,9 ng/ mL  ± 5,6 ng/ mL vs. 0,4 ng/ mL  ± 0,8 ng/ mL , p = 0,021), que aquéllos sin IBG. En un análisis multivariable de regresión logística, el número absoluto de blastos y la PCT fueron los dos test de despistaje que se asociaron de forma independiente con IBG, aunque el área bajo la curva de rendimiento diagnóstico para la PCT fue la mayor de los test de despistaje (0,80, IC 95% = 0,71 a 0,89). Conclusiones La PCT es un biomarcador más preciso que las pruebas de despistaje tradicionales para identificar a los niños durante la primera infancia con IBG . Se requieren futuros estudios en una mayor cohorte de niños durante la primera infancia con fiebre para determinar de forma definitiva el beneficio de la PCT sobre las pruebas de despistaje de laboratorio tradicionales para identificar las IBG .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106122/1/acem12316.pd

Effectiveness of the repair of unstabilised rammed earth with injection of mud grouts

The presence of cracks debilitates the structural performance of rammed earth. Grout injection is a repair solution put forward recently, where compatibility issues demand using mud grouts. Little is known on this topic, whereby an experimental program on the mechanical effectiveness of grout injection for repairing cracks in rammed earth was performed. Specimens tested under bending and diagonal compression were retested after repair with injection of mud grouts. Mud grouts incorporating the original soil of the rammed earth are shown to perform better and their injection achieves satisfactory shear strength recovery, but is less effective in recovering initial shear stiffness.This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of projects POCI-01-0145-FEDER-007633 and POCI-01-0145-FEDER-016737 (PTDC/ECM-EST/2777/2014). The first author would also like to acknowledge FCT for the Post-doc grant SFRH/BPD/97082/2013