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The Agency for Healthcare Research and Quality Inpatient Quality Indicator #11 overall mortality rate does not accurately assess mortality risk after abdominal aortic aneurysm repair

Fri, 10/03/2014 - 10:29am

OBJECTIVE: The Agency for Healthcare Research and Quality (AHRQ) Inpatient Quality Indicator (IQI) #11, abdominal aortic aneurysm (AAA) repair mortality rate, is a measure of hospital quality that is publically reported but has not been externally validated. Because the IQI #11 overall mortality rate includes both intact and ruptured aneurysms and open and endovascular repair, we hypothesized that IQI #11 overall mortality rate does not provide accurate assessment of mortality risk after AAA repair and that AAA mortality cannot be accurately assessed by a single quality measure.

METHODS: Using AHRQ IQI software version 4.2, we calculated observed (O) and expected (E) mortality rates for IQI #11 for all hospitals performing more than 10 AAA repairs per year in the Nationwide Inpatient Sample for the years 2007 to 2011. We used Spearman correlation coefficient to compare expected rates as determined by IQI #11 overall mortality rate risk adjustment methodology and observed rates for all AAA repairs in four cohorts stratified by aneurysm stability (ruptured vs intact) and method of repair (open vs endovascular).

RESULTS: Among 187,773 AAA repairs performed at 1268 U.S. hospitals, hospitals' IQI #11 overall expected rates correlated poorly with their observed rates (E: 5.0% ± 4.4% vs O: 6.0% ± 9.8%; r = .49). For ruptured AAAs, IQI #11 overall mortality rate methodology underestimated the mortality risk of open repair (E: 34% ± 7.2% vs O: 40.1% ± 38.2%; r = 0.20) and endovascular repair (E: 24.8% ± 9% vs O: 27.3% ± 37.9%; r = 0.08). For intact AAA repair, IQI #11 overall mortality rate methodology underestimated the mortality risk of open repair (E: 4.3% ± 2.4% vs O: 6.3% ± 16.1%; r = .24) but overestimated the mortality risk of endovascular repair (E: 1.3% ± 0.8% vs O: 1.1% ± 3.7%; r = 0.25). Hospitals' observed mortality rates after intact AAA repair were not correlated with their mortality rates after ruptured AAA repair (r = 0.03).

CONCLUSIONS: IQI #11 overall mortality rate fails to provide accurate assessment of inpatient mortality risk after AAA repair. Thus, it is inappropriate to use IQI #11 overall mortality rate for quality reporting. The accuracy of separate quality measures that assess mortality risk after repair of ruptured and intact AAAs, stratified by the use of open or endovascular repair, should be examined.

High-grade atrioventricular block in acute coronary syndromes: insights from the Global Registry of Acute Coronary Events

Fri, 10/03/2014 - 10:14am

BACKGROUND: While prior work has suggested that a high-grade atrioventricular block (HAVB) in the setting of an acute coronary syndrome (ACS) is associated with in-hospital death, limited information is available on the incidence of, and death associated with, HAVB in ACS patients receiving contemporary management.

METHODS AND RESULTS: The incidence of HAVB was determined within The Global Registry of Acute Coronary Events (GRACE). The clinical characteristics, in-hospital therapies, and outcomes were compared between patients with and without HAVB. Factors associated with death in patients with HAVB were determined. A total of 59 229 patients with ACS between 1999 and 2007 were identified; 2.9% of patients had HAVB at any point during the index hospitalization; 22.7% of whom died in hospital [adjusted odds ratio (OR) = 4.2, 95% confidence interval (CI), 3.6-4.9, P < 0.001]. The association between HAVB and in-hospital death varied with type of ACS [OR: ST-segment elevation myocardial infarction (STEMI) = 3.0; non-STEMI = 6.4; unstable angina = 8.2, P for interaction < 0.001]. High-grade atrioventricular block present at the time of presentation to hospital (vs. occurring in-hospital) and early (12 h or no intervention) were associated with improved in-hospital survival, whereas temporary pacemaker insertion was not. Patients with HAVB surviving to discharge had similar adjusted survival at 6 months compared with those without HAVB. A reduction in the rate of, but not in-hospital mortality associated with, HAVB was noted over the study period.

CONCLUSION: Although the incidence of HAVB is low and decreasing, this complication continues to have a high risk of in-hospital death.

Inductive asymmetric cell division: The WRM leads the way

Wed, 10/01/2014 - 10:24am

C. elegans, with its invariant cell lineage, provides a powerful model system in which to study signaling-dependent asymmetric cell division. The C. elegans β-catenin-related protein, WRM-1, specifies endoderm at the 4-cell stage during the first cell signaling-induced asymmetric cell division of embryogenesis. During this interaction, Wnt signaling and the cell cycle regulator CDK-1 act together to induce the asymmetric cortical release of WRM-1 at prophase of the EMS cell cycle. Genetic studies suggest that release of WRM-1 unmasks a cortical site that drives EMS spindle rotation onto the polarized axis of the cell, simultaneously making WRM-1 available for nuclear translocation, and downstream signaling to specify endoderm. These studies suggest a general paradigm for how cortical factors like WRM-1 can function at the cell cortex to mask potentially confounding polarity cues, and when released with appropriate cell cycle timing, can also function downstream to define cell fate.

Food, pathogen, signal: The multifaceted nature of a bacterial diet

Wed, 10/01/2014 - 9:16am

C. elegans, both in the wild and in the lab, live on a diet of live bacteria. The bacterial diet provides nutrients for C. elegans, but can also play a number of other roles in C. elegans physiology. Recently, we compared the effects of different bacterial diets on life history traits and gene expression. Here, we discuss our recent findings in the context of other dietary studies and highlight challenges in understanding dietary effects. For instance, since bacteria can be pathogenic it can be difficult to disentangle pathogenic from dietary effects. Here we summarize different bacterial diets used for C. elegans and how they affect the animal.

Worms, bacteria, and micronutrients: an elegant model of our diet

Wed, 10/01/2014 - 9:16am

Micronutrients are required in small proportions in a diet to carry out key metabolic roles for biomass and energy production. Humans receive micronutrients either directly from their diet or from gut microbiota that metabolize other nutrients. The nematode Caenorhabditis elegans and its bacterial diet provide a relatively simple and genetically tractable model to study both direct and microbe-mediated effects of micronutrients. Recently, this model has been used to gain insight into the relationship between micronutrients, physiology, and metabolism. In particular, two B-type vitamins, vitamin B12 and folate, have been studied in detail. Here we review how C. elegans and its bacterial diet provide a powerful interspecies systems biology model that facilitates the precise delineation of micronutrient effects and the mechanisms involved.

Determination and inference of eukaryotic transcription factor sequence specificity

Wed, 10/01/2014 - 9:16am

Transcription factor (TF) DNA sequence preferences direct their regulatory activity, but are currently known for only approximately 1% of eukaryotic TFs. Broadly sampling DNA-binding domain (DBD) types from multiple eukaryotic clades, we determined DNA sequence preferences for >1,000 TFs encompassing 54 different DBD classes from 131 diverse eukaryotes. We find that closely related DBDs almost always have very similar DNA sequence preferences, enabling inference of motifs for approximately 34% of the approximately 170,000 known or predicted eukaryotic TFs. Sequences matching both measured and inferred motifs are enriched in chromatin immunoprecipitation sequencing (ChIP-seq) peaks and upstream of transcription start sites in diverse eukaryotic lineages. SNPs defining expression quantitative trait loci in Arabidopsis promoters are also enriched for predicted TF binding sites. Importantly, our motif "library" can be used to identify specific TFs whose binding may be altered by human disease risk alleles. These data present a powerful resource for mapping transcriptional networks across eukaryotes.

Introduction to Cancer Concepts: A Guidebook for the Non-Oncologist

Fri, 09/26/2014 - 10:35am

This chapter in Cancer Concepts: A Guidebook for the Non-Oncologist presents an introduction to the Guidebook, which developed from the Cancer Concepts course at the University of Massachusetts Medical School.

Chronic alcohol-induced microRNA-155 contributes to neuroinflammation in a TLR4-dependent manner in mice

Thu, 09/25/2014 - 10:52am

INTRODUCTION: Alcohol-induced neuroinflammation is mediated by pro-inflammatory cytokines and chemokines including tumor necrosis factor-alpha (TNFalpha), monocyte chemotactic protein-1 (MCP1) and interleukin-1-beta (IL-1beta). Toll-like receptor-4 (TLR4) pathway induced nuclear factor-kappaB (NF-kappaB) activation is involved in the pathogenesis of alcohol-induced neuroinflammation. Inflammation is a highly regulated process. Recent studies suggest that microRNAs (miRNAs) play crucial role in fine tuning gene expression and miR-155 is a major regulator of inflammation in immune cells after TLR stimulation.

AIM: To evaluate the role of miR-155 in the pathogenesis of alcohol-induced neuroinflammation.

METHODS: Wild type (WT), miR-155- and TLR4-knockout (KO) mice received 5% ethanol-containing or isocaloric control diet for 5 weeks. Microglia markers were measured by q-RTPCR; inflammasome activation was measured by enzyme activity; TNFalpha, MCP1, IL-1beta mRNA and protein were measured by q-RTPCR and ELISA; phospho-p65 protein and NF-kappaB were measured by Western-blotting and EMSA; miRNAs were measured by q-PCR in the cerebellum. MiR-155 was measured in immortalized and primary mouse microglia after lipopolysaccharide and ethanol stimulation.

RESULTS: Chronic ethanol feeding up-regulated miR-155 and miR-132 expression in mouse cerebellum. Deficiency in miR-155 protected mice from alcohol-induced increase in inflammatory cytokines; TNFalpha, MCP1 protein and TNFalpha, MCP1, pro-IL-1beta and pro-caspase-1 mRNA levels were reduced in miR-155 KO alcohol-fed mice. NF-kappaB was activated in WT but not in miR-155 KO alcohol-fed mice. However increases in cerebellar caspase-1 activity and IL-1beta levels were similar in alcohol-fed miR-155-KO and WT mice. Alcohol-fed TLR4-KO mice were protected from the induction of miR-155. NF-kappaB activation measured by phosphorylation of p65 and neuroinflammation were reduced in alcohol-fed TLR4-KO compared to control mice. TLR4 stimulation with lipopolysaccharide in primary or immortalized mouse microglia resulted in increased miR-155.

CONCLUSION: Chronic alcohol induces miR-155 in the cerebellum in a TLR4-dependent manner. Alcohol-induced miR-155 regulates TNFalpha and MCP1 expression but not caspase-dependent IL-1beta increase in neuroinflammation.

Toll-like receptors in liver disease

Thu, 09/25/2014 - 10:52am

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Recent studies demonstrated that Toll-like receptors, the sensors of microbial and endogenous danger signals, are expressed and activated in innate immune cells as well as in parenchymal cells in the liver and thereby contribute to ALD and NASH. In this review, we emphasize the importance of gut-derived endotoxin and its recognition by TLR4 in the liver. The significance of TLR-induced intracellular signaling pathways and cytokine production as well as the contribution of individual cell types to the inflammation is evaluated. The contribution of TLR signaling to the induction of liver fibrosis and to the progression of liver pathology mediated by viral pathogens is reviewed in the context of ALD and NASH.

Human type 2 myeloid dendritic cells produce interferon-lambda and amplify interferon-alpha in response to hepatitis C virus infection

Thu, 09/25/2014 - 10:52am

BACKGROUND and AIMS: The type III interferons (IFN-lambdas: interleukin [IL]-28a, IL-28b, and IL-29) have important roles in hepatitis C virus (HCV) infection, but little is understood about what cells produce these cytokines or how production is activated. We investigated whether human immune cells recognize HCV-infected cells and respond by producing IFN-lambda.

METHODS: We cultured healthy human peripheral blood mononuclear cells (PBMCs) with different populations of immune cells and Japanese fulminant hepatitis-1 (JFH-1) HCV-infected Huh7.5 (cell culture-derived HCV particles [HCVcc]/Huh7.5) cells. RESULTS: Human PBMCs recognized HCVcc/Huh7.5 cells and responded by producing IFN-alpha, IFN-gamma, and IFN-lambda. A rare subset of myeloid dendritic cells (mDCs), which are blood DC antigen (BDCA)+ (also called mDC2 cells), were the major source of IL-28 and IL-29 production in response to HCVcc/Huh7.5 cells. Plasmacytoid DCs produced IFN-alpha, whereas natural killer and natural killer T cells were the main source of IFN-gamma production in co-culture experiments. Of the endosomal Toll-like receptors (TLRs)3, 7, 8, and 9, only TLR3 or double-stranded HCV RNA induced production of IL-28 and IL-29 by mDC2s; endosomal maturation was required. Production of IFN-alpha and IFN-lambda were linked-IFN-lambda increased production of IFN-alpha by plasmacytoid DCs and IFN-alpha significantly increased production of IFN-lambda.

CONCLUSIONS: mDC2s are a major source of IFN-lambda production by PBMCs in response to HCVcc/Huh7.5 cells. mDC2s are activated through the TLR3 pathway, indicating that human DCs efficiently can initiate an immune response against HCV infection. IFN-lambda therefore has an important role in HCV infection.

Binge ethanol and liver: new molecular developments

Thu, 09/25/2014 - 10:52am

Binge consumption of alcohol is an alarming global health problem. Binge (acute) ethanol (EtOH) is implicated in the pathophysiology of alcoholic liver disease (ALD). New studies from experimental animals and from humans indicate that binge EtOH has profound effects on immunological, signaling, and epigenetic parameters of the liver. This is in addition to the known metabolic effects of acute EtOH. Binge EtOH alters the levels of several cellular components and dramatically amplifies liver injury in chronically EtOH exposed liver. These studies highlight the importance of molecular investigations into binge effects of EtOH for a better understanding of ALD and also to develop therapeutic strategies to control it. This review summarizes these recent developments.

Differences in innate immune signaling between alcoholic and non-alcoholic steatohepatitis

Thu, 09/25/2014 - 10:52am

The similar histopathological characteristics of alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH), and the crucial role of the innate immune response in both conditions may lead to the assumption that ASH and NASH represent the same pathophysiological entities caused by different risk factors. In this review paper, we elaborate on the pathophysiological differences between these two entities and highlight the disease-specific involvement of signaling molecules downstream of the Toll-like receptor 4, and the differential mechanism by which the inflammasome contributes to ASH versus NASH. Our findings emphasize that ASH and NASH have disease-specific mechanisms and therefore represent distinct biological entities. Further studies are needed to dissect the emerging differences in pathogenesis of these two conditions. Publishing Asia Pty Ltd.

STING-IRF3 pathway links endoplasmic reticulum stress with hepatocyte apoptosis in early alcoholic liver disease

Thu, 09/25/2014 - 10:52am

Emerging evidence suggests that innate immunity drives alcoholic liver disease (ALD) and that the interferon regulatory factor 3 (IRF3),a transcription factor regulating innate immune responses, is indispensable for the development of ALD. Here we report that IRF3 mediates ALD via linking endoplasmic reticulum (ER) stress with apoptotic signaling in hepatocytes. We found that ethanol induced ER stress and triggered the association of IRF3 with the ER adaptor, stimulator of interferon genes (STING), as well as subsequent phosphorylation of IRF3. Activated IRF3 associated with the proapoptotic molecule Bax [B-cell lymphoma 2 (Bcl2)-associated X protein] and contributed to hepatocyte apoptosis. Deficiency of STING prevented IRF3 phosphorylation by ethanol or ER stress, and absence of IRF3 prevented hepatocyte apoptosis. The pathogenic role of IRF3 in ALD was independent of inflammation or Type-I interferons. Thus, STING and IRF3 are key determinants of ALD, linking ER stress signaling with the mitochondrial pathway of hepatocyte apoptosis.

Human ezrin-moesin-radixin proteins modulate hepatitis C virus infection

Thu, 09/25/2014 - 10:52am

Host cytoskeletal proteins of the ezrin-moesin-radixin (EMR) family have been shown to modulate single-stranded RNA virus infection through regulating stable microtubule formation. Antibody engagement of CD81, a key receptor for hepatitis C virus (HCV) entry, induces ezrin phosphorylation. Here we tested the role of EMR proteins in regulating HCV infection and explored potential therapeutic targets. We show that HCV E2 protein induces rapid ezrin phosphorylation and its cellular redistribution with F-actin by way of spleen tyrosine kinase (SYK). Therapeutically blocking the functional roles of SYK or F-actin reorganization significantly reduced Huh7.5 cell susceptibility to HCV J6/JFH-1 infection. Using gene regulation, real-time quantitative polymerase chain reaction, western blot, and fluorescent microscopy analysis, we found that proteins of the EMR family differentially regulate HCV infection in the J6/JFH-1/Huh7.5 cell system. Moesin and radixin, but not ezrin, expression were significantly decreased in chronic HCV J6/JFH-1-infected Huh7.5 cells and HCV-infected patient liver biopsies compared to controls. The decreases in moesin and radixin in HCV J6/JFH-1-infected Huh7.5 cells were associated with a significant increase in stable microtubules. Ezrin knockdown inhibited immediate postentry events in HCV infection. Overexpression of moesin or radixin significantly reduced HCV protein expression. In contrast, transient knockdown of moesin or radixin augmented HCV infection. Making use of the Con1 HCV replicon system, we tested the effect of EMR proteins on HCV replication. We found that transient knockdown of moesin increased HCV RNA expression while overexpression of EMR showed no significant effect on HCV replication.

CONCLUSION: Our findings demonstrate the important role of EMR proteins during HCV infection at the postentry level and highlight possible novel targets for HCV treatment.

Immune and inflammatory pathways in NASH

Thu, 09/25/2014 - 10:52am

Immune and inflammatory pathways have a central role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Both the innate and adaptive immune systems contribute to the development of NAFLD. Pathogen-associated molecular patterns and danger-associated molecular patterns are known to activate a variety of pattern-recognition receptors that result in inflammation. The key features of the immune system and inflammatory pathways in the development of NAFLD are discussed in this review.

Acute binge drinking increases serum endotoxin and bacterial DNA levels in healthy individuals

Thu, 09/25/2014 - 10:52am

Binge drinking, the most common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its biological consequences are poorly defined. Previous studies demonstrated that chronic alcohol use results in increased gut permeability and increased serum endotoxin levels that contribute to many of the biological effects of chronic alcohol, including alcoholic liver disease. In this study, we evaluated the effects of acute binge drinking in healthy adults on serum endotoxin levels. We found that acute alcohol binge resulted in a rapid increase in serum endotoxin and 16S rDNA, a marker of bacterial translocation from the gut. Compared to men, women had higher blood alcohol and circulating endotoxin levels. In addition, alcohol binge caused a prolonged increase in acute phase protein levels in the systemic circulation. The biological significance of the in vivo endotoxin elevation was underscored by increased levels of inflammatory cytokines, TNFalpha and IL-6, and chemokine, MCP-1, measured in total blood after in vitro lipopolysaccharide stimulation. Our findings indicate that even a single alcohol binge results in increased serum endotoxin levels likely due to translocation of gut bacterial products and disturbs innate immune responses that can contribute to the deleterious effects of binge drinking.

Converging actions of alcohol on liver and brain immune signaling

Thu, 09/25/2014 - 10:52am

Chronic excessive alcohol consumption results in inflammation in multiple organs, including the brain. While the contribution of neuroinflammation to alcohol-related cognitive dysfunction and behavioral alterations is established, the mechanisms by which alcohol triggers inflammation in the brain are only partially understood. There are acute and long-term alterations in brain function due to intercellular and intracellular changes of different cell types as a result of alcohol consumption. This review focuses on the alcohol-induced proinflammatory cellular and molecular changes in the central nervous system. Alcohol passes through the blood-brain barrier and alters neurotransmission. Alcohol use activates microglia and astrocyte, contributing to neurodegeneration and impaired regeneration. Alcohol-induced cell injury in the brain results in release of damage-associated molecular patterns, such as high mobility group box 1, that trigger inflammatory changes through activation of pattern recognition receptors. In addition, alcohol consumption increases intestinal permeability and results in increased levels of pathogen-associated molecular pattern such as endotoxin in the systemic circulation that triggers PRRs and inflammation. The Toll-like receptor-4 pathway that activates nuclear factor-kappaB and secretion of proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1-beta, and chemokines, including monocyte chemotactic protein-1, has been suggested to contribute to alcohol-induced neuroinflammation. Alcohol-induced IL-1beta secretion also requires Nod-like receptor-mediated inflammasome and caspase-1 activation, and, consistent with this, disruption of IL-1/IL-1-receptor signaling prevents alcohol-induced neuroinflammation. Delicate regulators of inflammatory gene expressions are micro-RNAs (miRs) that have recently been identified in alcohol-related neuroinflammation. Alcohol induces miR155, a regulator of inflammation in the brain, and deficiency in miR-155 in mice was protective from neuroinflammatory changes. These observations suggest that manipulation of miR pathways and cytokine induction may reduce alcohol-induced proinflammatory processes.

Both bone marrow-derived and non-bone marrow-derived cells contribute to AIM2 and NLRP3 inflammasome activation in a MyD88-dependent manner in dietary steatohepatitis

Thu, 09/25/2014 - 10:52am

BACKGROUND and AIMS: Inflammation promotes the progression of non-alcoholic steatohepatitis (NASH). Toll-like receptor 4 (TLR4) and TLR9 activation through myeloid differentiation primary response gene 88 (MyD88) and production of mature interleukin-1beta (IL-1beta) via inflammasome activation contribute to steatohepatitis. Here, we investigated the inter-relationship between TLR signalling and inflammasome activation in dietary steatohepatitis.

METHODS: Wild type (WT), TLR4- and MyD88-deficient (KO) mice received methionine-choline-deficient (MCD) or -supplemented (MCS) diets for 5 weeks and a subset was challenged with TLR9 ligand CpG-DNA.

RESULTS: TLR4, TLR9, AIM2 (absent in melanoma 2) and NLRP3 (NLR family pyrin domain containing 3) inflammasome mRNA, and mature IL-1beta protein levels were increased in MCD diet-induced steatohepatitis compared to MCS controls. TLR9 stimulation resulted in greater up-regulation of the DNA-sensing AIM2 expression and IL-1beta production in livers of MCD compared to MCS diet-fed mice. High mobility group box 1 (HMGB1), a TLR9-activating danger molecule and phospho-HMGB1 protein levels were also increased in livers of MCD diet-fed mice. MyD88- but not TLR4-deficiency prevented up-regulation of AIM2, NLRP3 mRNA and IL-1beta protein production in dietary steatohepatitis. Selective MyD88 deficiency either in bone marrow (BM)-derived or non-BM-derived cells attenuated hepatic up-regulation of inflammasome mRNA, caspase-1 activation and IL-1beta protein production, but only BM-derived cell-specific MyD88-deficiency attenuated liver injury.

CONCLUSIONS: Our data demonstrate that both bone marrow-derived and non-BM-derived cells contribute to inflammasome activation in a MyD88-dependent manner in dietary steatohepatitis. We show that AIM2 inflammasome expression and activation are further augmented by TLR9 ligands in dietary steatohepatitis.

Exosome-mediated delivery of functionally active miRNA-155 inhibitor to macrophages

Thu, 09/25/2014 - 10:52am

Exosomes, membranous nanovesicles, naturally carry bio-macromolecules and play pivotal roles in both physiological intercellular crosstalk and disease pathogenesis. Here, we showed that B cell-derived exosomes can function as vehicles to deliver exogenous miRNA-155 mimic or inhibitor into hepatocytes or macrophages, respectively. Stimulation of B cells significantly increased exosome production. Unlike in parental cells, baseline level of miRNA-155 was very low in exosomes derived from stimulated B cells. Exosomes loaded with a miRNA-155 mimic significantly increased miRNA-155 levels in primary mouse hepatocytes and the liver of miRNA-155 knockout mice. Treatment of RAW macrophages with miRNA-155 inhibitor loaded exosomes resulted in statistically significant reduction in LPS-induced TNFalpha production and partially prevented LPS-induced decrease in SOCS1 mRNA levels. Furthermore, exosome-mediated miRNA-155 inhibitor delivery resulted in functionally more efficient inhibition and less cellular toxicity compared to conventional transfection methods. Similar approaches could be useful in modification of target biomolecules in vitro and in vivo.