PNPLA3 genetic variation in alcoholic steatosis and liver disease progression

Alcoholic liver disease (ALD) accounts for the majority of chronic liver diseases in Western countries, and alcoholic cirrhosis is among the premier causes of liver failure, hepatocellular carcinoma (HCC) and liver-related mortality causes. Studies in different genders and ethnic groups, as well as in twins provide strong evidence for a significant contribution of host genetic factors to liver disease development in drinkers. The intense quest for genetic modifiers of alcohol-induced fibrosis progression have identified and repeatedly confirmed a genetic polymorphism in the gene coding for patatin-like phospholipase domain-containing 3 (PNPLA3; adiponutrin; rs738409 C/G, M148I) as a risk factor for alcoholic cirrhosis and its related complication, HCC, in different populations. Although carriership of one or both mutated PNPLA3 alleles does not explain the entire liver phenotypic variability in drinkers, it clearly represents one of the strongest single genetic modulators in a complex trait such as ALD. As more genetic data supporting its important role aggregates, novel insight as to PNPLA3’s function and that of its genetic variation in liver injury is unveiled pointing to an important novel pathway in alcohol-mediated hepatic lipid turnover with strong implications on inflammation, extra cellular matrix remodelling, and hepatocarcinogenesis. Future study shall decipher whether the gathered knowledge can be translated into therapeutic benefits of patients.     

A pilot wastewater‐based epidemiology assessment of anabolic steroid use in Queensland,Australia

Anabolic‐androgenic steroids are synthetic compounds prohibited due to their performance‐enhancing characteristics. The use of these substances is known to cause health‐related issues, which highlights the importance of being able to evaluate the scale of consumption by the general population. However, most available research on the analysis of anabolic steroids is focused on animals and athletes in connection with doping. The potential of wastewater‐based epidemiology as an intelligence tool for the assessment of community level use of anabolic steroids is presented herein. A liquid chromatography tandem mass spectrometry method was developed for the analysis of 10 anabolic‐androgenic steroids and 14 endogenous hormones in influent wastewater. The validated method was applied to sixteen 24‐hour composite wastewater influent samples that were collected over a period of five years from two wastewater treatment plants in Queensland, Australia. Nine investigated compounds were found to be present at concentrations between 14 and 611 ng L^?1 which translated into 3–104 mg excreted per 1000 individuals per day. It was concluded that the developed analytical method is suitable for the analysis of AAS in wastewater matrix. Additionally, both the inclusion of metabolites and further investigation into deconjugation by enzymatic hydrolysis would aid in understanding and evaluating community anabolic steroid use. For the first time, this study presents the application of wastewater‐based epidemiology on anabolic‐androgenic steroids in Australia.     

Autoimmunity, intestinal lymphoid hyperplasia, and defects in mucosal B-cell homeostasis in patients with PTEN hamartoma tumor syndrome

The Phosphatase And Tensin Homolog Deleted On Chromosome 10 (PTEN) regulates the phosphoinositol-3-kinase (PI3K)-AKT signaling pathway. In a series of 34 patients with PTEN mutations, we described gastrointestinal lymphoid hyperplasia, extensive hyperplastic tonsils, thymus hyperplasia, autoimmune lymphocytic thyroiditis, autoimmune hemolytic anemia, and colitis. Functional analysis of the gastrointestinal mucosa-associated lymphoid tissue revealed increased signaling via the PI3K-AKT pathway, including phosphorylation of S6 and increased cell proliferation, but also reduced apoptosis of CD20(+)CD10(+) B cells. Reduced activity of PTEN therefore affects homeostasis of human germinal center B cells by increasing PI3K-AKT signaling via mammalian target of rapamycin as well as antiapoptotic signals.     

Time-course of the electrophysiological maturation and integration of transplanted cardiomyocytes

Electrophysiological maturation and integration of transplanted cardiomyocytes are essential to enhance safety and efficiency of cell replacement therapy. Yet, little is known about these important processes. The aim of our study was to perform a detailed analysis of electrophysiological maturation and integration of transplanted cardiomyocytes. Fetal cardiomyocytes expressing enhanced green fluorescent protein were transplanted into cryoinjured mouse hearts. At 6, 9 and 12days after transplantation, viable slices of recipient hearts were prepared and action potentials of transplanted and host cardiomyocytes within the slices were recorded by microelectrodes. In transplanted cells embedded in healthy host myocardium, action potential duration at 50% repolarization (APD50) decreased from 32.2±3.3ms at day 6 to 27.9±2.6ms at day 9 and 19.6±1.6ms at day 12. The latter value matched the APD50 of host cells (20.5±3.2ms, P=0.78). Integration improved in the course of time: 26% of cells at day 6 and 53% at day 12 revealed no conduction blocks up to a stimulation frequency of 10Hz. APD50 was inversely correlated to the quality of electrical integration. In transplanted cells embedded into the cryoinjury, which showed no electrical integration, APD50 was 49.2±4.3ms at day 12. Fetal cardiomyocytes transplanted into healthy myocardium integrate electrically and mature after transplantation, their action potential properties after 12days are comparable to those of host cardiomyocytes. Quality of electrical integration improves over time, but conduction blocks still occur at day 12 after transplantation. The pace of maturation correlates with the quality of electrical integration. Transplanted cells embedded in cryoinjured tissue still possess immature electrophysiological properties after 12days.     

Mechanistic insight into the blocking of CO diffusion in [NiFe]-hydrogenase mutants through multiscale simulation

[NiFe]-hydrogenases are fascinating biological catalysts with potential application in biofuel cells. However, a severe problem in practical application is the strong sensitivity of hydrogenase to gaseous inhibitor molecules such as CO and O(2). Recently, a number of successful protein engineering studies have been reported that aimed at lowering the access of diatomic inhibitors to the active site pocket, but the molecular mechanism conferring increased resistance remained unclear. Here we use a multiscale simulation approach combining molecular dynamics with a master equation formalism to explain the steady drop in CO diffusion rate observed for the mutants V74M L122A, V74M L122M, and V74M of Desulfovibrio fructosovorans [NiFe]-hydrogenase. We find that diffusion in these variants is controlled by two gates, one between residues 74 and 476 and the other between residues 74 and 122. The existence of two control points in different locations explains why the reduction in the experimental diffusion rate does not simply correlate with the width of the main gas channel. We also find that in the more effective mutation (V74M) CO molecules are still able to reach the active site through transitions that are gated by the microsecond dihedral motions of the side chain of R476 and the thermal fluctuations of the width of the gas channel defined by M74 and L122. Reflecting on the molecular information gained from simulation, we discuss future mutation experiments that could further lower the diffusion rates of small ligands inhibiting [NiFe]-hydrogenase.