Hepatitis B virus surface proteins accelerate cholestatic injury and tumor progression in Abcb4-knockout mice

Understanding of the pathophysiology of cholestasis associated carcinogenesis could challenge the development of new personalized therapeutic approaches and thus improve prognosis. Simultaneous damage might aggravate hepatic injury, induce chronic liver disease and even promote carcinogenesis. We aimed to study the effect of Hepatitis B virus surface protein (HBsAg) on cholestatic liver disease and associated carcinogenesis in a mouse model combining both impairments. Hybrids of Abcb4-/- and HBsAg transgenic mice were bred on fibrosis susceptible background BALB/c. Liver injury, serum bile acid concentration, hepatic fibrosis, and carcinogenesis were enhanced by the combination of simultaneous damage in line with activation of c-Jun N-terminal kinase (JNK), proto-oncogene c-Jun, and Signal transducer and activator of transcription 3 (STAT3). Activation of Protein Kinase RNA-like Endoplasmic Reticulum Kinase (PERK) and Eukaryotic translation initiation factor 2A (eIF2a) indicated unfolded protein response (UPR) in HBsAg-expressing mice and even in Abcb4-/- without HBsAg-expression. CONCLUSION: Cholestasis-induced STAT3- and JNK-pathways may predispose HBsAg-associated tumorigenesis. Since STAT3- and JNK-activation are well characterized critical regulators for tumor promotion, the potentiation of their activation in hybrids suggests an additive mechanism enhancing tumor incidence

Inter-laboratory analytical improvement of succinylacetone and nitisinone quantification from dried blood spot samples

Background: Nitisinone is used to treat hereditary tyrosinemia type 1 (HT-1) by preventing accumulation of toxic metabolites, including succinylacetone (SA). Accurate quantification of SA during newborn screening is essential, as is quantification of both SA and nitisinone for disease monitoring and optimization of treatment. Analysis of dried blood spots (DBS) rather than plasma samples is a convenient method, but interlaboratory differences and comparability of DBS to serum/plasma may be issues to consider. Methods: Eight laboratories with experience in newborn screening and/or monitoring of patients with HT-1 across Europe participated in this study to assess variability and improve SA and nitisinone concentration measurements from DBS by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Quantification of nitisinone from both DBS and plasma was performed to assess sample comparability. In addition, efforts to harmonize laboratoryprocedures of SA and nitisinone quantifications during 5 rounds of analysis are described. Results: Nitisinone levels measured from DBS and plasma strongly correlated (R2 = 0.93). Due to partitioning of nitisinone to the plasma, levels were higher in plasma by a factor of 2.34. In the initial assessment of laboratory performance, all had linear calibrations of SA and nitisinone although there was large inter-laboratory variability in actual concentration measurements. Subsequent analytical rounds demonstrated markedly improved spread and precision over previous rounds, an outcome confirmed in a final re-test round. Conclusion: The study provides guidance for the determination of nitisinone and SA from DBS and the interpretation of results in the clinic. Interlaboratory analytical harmonization was demonstrated through calibration improvements.SCOPUS: ar.kinfo:eu-repo/semantics/publishe

Cardiometabolic risk factor clustering in patients with deficient branched‐chain amino acid catabolism: A case‐control study

AbstractClassical organic acidemias (OAs) result from defective mitochondrial catabolism of branched‐chain amino acids (BCAAs). Abnormal mitochondrial function relates to oxidative stress, ectopic lipids and insulin resistance (IR). We investigated whether genetically impaired function of mitochondrial BCAA catabolism associates with cardiometabolic risk factors, altered liver and muscle energy metabolism, and IR. In this case‐control study, 31 children and young adults with propionic acidemia (PA), methylmalonic acidemia (MMA) or isovaleric acidemia (IVA) were compared with 30 healthy young humans using comprehensive metabolic phenotyping including in vivo 31P/1H magnetic resonance spectroscopy of liver and skeletal muscle. Among all OAs, patients with PA exhibited abdominal adiposity, IR, fasting hyperglycaemia and hypertriglyceridemia as well as increased liver fat accumulation, despite dietary energy intake within recommendations for age and sex. In contrast, patients with MMA more frequently featured higher energy intake than recommended and had a different phenotype including hepatomegaly and mildly lower skeletal muscle ATP content. In skeletal muscle of patients with PA, slightly lower inorganic phosphate levels were found. However, hepatic ATP and inorganic phosphate concentrations were not different between all OA patients and controls. In patients with IVA, no abnormalities were detected. Impaired BCAA catabolism in PA, but not in MMA or IVA, was associated with a previously unrecognised, metabolic syndrome‐like phenotype with abdominal adiposity potentially resulting from ectopic lipid storage. These findings suggest the need for early cardiometabolic risk factor screening in PA

A Novel Tandem Mass Spectrometry Method for Rapid Confirmation of Medium- and Very Long-Chain acyl-CoA Dehydrogenase Deficiency in Newborns

BACKGROUND:Newborn screening for medium- and very long-chain acyl-CoA dehydrogenase (MCAD and VLCAD, respectively) deficiency, using acylcarnitine profiling with tandem mass spectrometry, has increased the number of patients with fatty acid oxidation disorders due to the identification of additional milder, and so far silent, phenotypes. However, especially for VLCADD, the acylcarnitine profile can not constitute the sole parameter in order to reliably confirm disease. Therefore, we developed a new liquid chromatography tandem mass spectrometry (LC-MS/MS) method to rapidly determine both MCAD- and/or VLCAD-activity in human lymphocytes in order to confirm diagnosis. METHODOLOGY:LC-MS/MS was used to measure MCAD- or VLCAD-catalyzed production of enoyl-CoA and hydroxyacyl-CoA, in human lymphocytes. PRINCIPAL FINDINGS:VLCAD activity in controls was 6.95+/-0.42 mU/mg (range 1.95 to 11.91 mU/mg). Residual VLCAD activity of 4 patients with confirmed VLCAD-deficiency was between 0.3 and 1.1%. Heterozygous ACADVL mutation carriers showed residual VLCAD activities of 23.7 to 54.2%. MCAD activity in controls was 2.38+/-0.18 mU/mg. In total, 28 patients with suspected MCAD-deficiency were assayed. Nearly all patients with residual MCAD activities below 2.5% were homozygous 985A>G carriers. MCAD-deficient patients with one other than the 985A>G mutation had higher MCAD residual activities, ranging from 5.7 to 13.9%. All patients with the 199T>C mutation had residual activities above 10%. CONCLUSIONS:Our newly developed LC-MS/MS method is able to provide ample sensitivity to correctly and rapidly determine MCAD and VLCAD residual activity in human lymphocytes. Importantly, based on measured MCAD residual activities in correlation with genotype, new insights were obtained on the expected clinical phenotype

Fragile X mental retardation protein protects against tumour necrosis factor-mediated cell death and liver injury.

peer reviewed[en] OBJECTIVE: The Fragile X mental retardation (FMR) syndrome is a frequently inherited intellectual disability caused by decreased or absent expression of the FMR protein (FMRP). Lack of FMRP is associated with neuronal degradation and cognitive dysfunction but its role outside the central nervous system is insufficiently studied. Here, we identify a role of FMRP in liver disease. DESIGN: Mice lacking Fmr1 gene expression were used to study the role of FMRP during tumour necrosis factor (TNF)-induced liver damage in disease model systems. Liver damage and mechanistic studies were performed using real-time PCR, Western Blot, staining of tissue sections and clinical chemistry. RESULTS: Fmr1null mice exhibited increased liver damage during virus-mediated hepatitis following infection with the lymphocytic choriomeningitis virus. Exposure to TNF resulted in severe liver damage due to increased hepatocyte cell death. Consistently, we found increased caspase-8 and caspase-3 activation following TNF stimulation. Furthermore, we demonstrate FMRP to be critically important for regulating key molecules in TNF receptor 1 (TNFR1)-dependent apoptosis and necroptosis including CYLD, c-FLIPS and JNK, which contribute to prolonged RIPK1 expression. Accordingly, the RIPK1 inhibitor Necrostatin-1s could reduce liver cell death and alleviate liver damage in Fmr1null mice following TNF exposure. Consistently, FMRP-deficient mice developed increased pathology during acute cholestasis following bile duct ligation, which coincided with increased hepatic expression of RIPK1, RIPK3 and phosphorylation of MLKL. CONCLUSIONS: We show that FMRP plays a central role in the inhibition of TNF-mediated cell death during infection and liver disease

Analysis and interpretation of metal-radical coupling in a series of square planar nickel complexes: Correlated ab initio and density functional investigation of [Ni(LISQ)2] (LISQ=3,5-di-tert-butyl-o-diiminobenzosemiquinonate(1-))

This paper reports a detailed theoretical study of the interaction between a central low-spin d8 nickel ion and two N,N-coordinating diiminobenzosemiquinonate(1-) ligands in a square planar arrangement. Such complexes have recently attracted much attention due to their unusual bonding patterns, structures, optical, and magnetic properties. Geometry optimizations using various levels of density functional theory (DFT) result in excellent agreement with the experimentally determined structure and in particular reproduce the quinoidal distortions in the aromatic rings well. A detailed analysis of the orbital structure reveals that the complex features essentially two strongly interacting ligand radicals which interact with each other via an efficient superexchange mechanism that is mediated by a back-bonding interaction to the central metal. An analysis of the broken symmetry DFT wave function is presented and a new index for the diradical character is proposed which shows that [Ni(LISQ)2] has a diradical character of ∼77%. These results are in full agreement with elaborate multireference post-Hartree−Fock ab initio calculations for [Ni(LISQ)2] using the difference dedicated configuration interaction (DDCI) method as well as second-order multireference Möller−Plesset (MR-MP2) theory, which give diradical characters of 65−80%. On the basis of these calculations our best estimate for the singlet−triplet gap in this system is 3096 cm-1. This very large value results from an efficient mixing of the ionic configurations into the mainly singlet diradical ground state which is feasible because the semiquinonate SOMOs are delocalized and, therefore, have moderate on-site Coulomb repulsion parameters. As pointed out in the discussion, this represents an interesting difference to the case of magnetically interacting transition metal ions which typically show much smaller magnetic exchange couplings

Molecular and electronic structures of bis-(o-diiminobenzosemiquinonato)metal(II) complexes (Ni, Pd, Pt), their monocations and -anions, and of dimeric dications containing weak metal-metal bonds

Two series of square planar, diamagnetic, neutral complexes of nickel(II), palladium(II), and platinum(II) containing two N,N-coordinated o-diiminobenzosemiquinonate(1-) π radical ligands have been synthesized and characterized by UV−vis and 1H NMR spectroscopy:  [MII(2LISQ)2], M = Ni (1), Pd (2), Pt (3), and [MII(3LISQ)2] M = Ni (4), Pd (5), Pt (6). H2[2LPDI] represents 3,5-di-tert-butyl-o-phenylenediamine and H2[3LPDI] is N-phenyl-o-phenylenediamine; (LISQ)1- is the o-diiminobenzosemiquinonate π radical anion, and (LIBQ)0 is the o-diiminobenzoquinone form of these ligands. The structures of complexes 1, 4, 5, and 6 have been (re)determined by X-ray crystallography at 100 K. Cyclic voltammetry established that the complete electron-transfer series consisting of a dianion, monoanion, neutral complex, a mono- and a dication exists:  [M(L)2]zz = −2, −1, 0, 1+, 2+. Each species has been electrochemically generated in solution and their X-band EPR and UV−vis spectra have been recorded. The oxidations and reductions are invariably ligand centered. Two o-diiminobenzoquinones(0) and two fully reduced o-diiminocatecholate(2-) ligands are present in the dication and dianion, respectively, whereas the monocations and monoanions are delocalized mixed valent class III species [MII(LISQ)(LIBQ)]+ and [MII(LISQ)(LPDI)]-, respectively. One-electron oxidations of 1 and trans-6 yield the diamagnetic dications {cis-[NiII(2LISQ)(2LIBQ)]2}Cl2 (7) and {trans-[PtII(3LISQ)(3LIBQ)]2}(CF3SO3)2 (8), respectively, which have been characterized by X-ray crystallography; both complexes possess a weak M···M bond and the ligands adopt an eclipsed configuration due to weak bonding interactions via π stacking