Gut Pathology and Responses to the Microsporidium Nosema ceranae in the Honey Bee Apis mellifera

The microsporidium Nosema ceranae is a newly prevalent parasite of the European honey bee (Apis mellifera). Although this parasite is presently spreading across the world into its novel host, the mechanisms by it which affects the bees and how bees respond are not well understood. We therefore performed an extensive characterization of the parasite effects at the molecular level by using genetic and biochemical tools. The transcriptome modifications at the midgut level were characterized seven days post-infection with tiling microarrays. Then we tested the bee midgut response to infection by measuring activity of antioxidant and detoxification enzymes (superoxide dismutases, glutathione peroxidases, glutathione reductase, and glutathione-S-transferase). At the gene-expression level, the bee midgut responded to N. ceranae infection by an increase in oxidative stress concurrent with the generation of antioxidant enzymes, defense and protective response specifically observed in the gut of mammals and insects. However, at the enzymatic level, the protective response was not confirmed, with only glutathione-S-transferase exhibiting a higher activity in infected bees. The oxidative stress was associated with a higher transcription of sugar transporter in the gut. Finally, a dramatic effect of the microsporidia infection was the inhibition of genes involved in the homeostasis and renewal of intestinal tissues (Wnt signaling pathway), a phenomenon that was confirmed at the histological level. This tissue degeneration and prevention of gut epithelium renewal may explain early bee death. In conclusion, our integrated approach not only gives new insights into the pathological effects of N. ceranae and the bee gut response, but also demonstrate that the honey bee gut is an interesting model system for studying host defense responses

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Regulation of cytochrome P450 genes in drosophila melanogaster by the chemical environment

Cytochrome P450 monooxygenases (P450s) play an important role in the adaptive response of insects and other animals to chemicals in the environment. P450s are heme-dependent enzymes that catalyze the addition of oxygen to a substrate in the presence of an electron donor, such as NADPH. In insects, some P450s are phase I detoxificaiton enzymes, representing the first line of defense against lipophilic xenobiotics, while other P450s are involved in the biosynthesis of ecydsone, juvenile hormone and pheromones. P450s are tightly regulated throughout development, and P450s involved in detoxification have been shown to be substrate-inducible, instead of indiscriminately, constitutively expressed. Understanding constitutive and inducible expression requires knowledge about the regulatory pathways that control insect P450 expression, which is still lacking for most identified insect P450s. Drosophila melanogaster, because of its longstanding use as a genetic model organism, is a powerful tool for identifying possible regulatory mechanisms and for following expression through to function. The aim of this work is to examine the evolution of cytochrome P450 genes in D. melanogaster in response to xenobiotic compounds. First, I explore the role of constitutive and inducible expression of P450s in cross-tolerance of a methoprene-tolerant D. melanogaster strain to the fungal toxin, aflatoxin B1, a natural constituent in the diet. Next, I investigate the duplication of a xenobiotic-responsive P450 in D. melanogaster and across 11 Drosophila species and examine the changes incurred in a strain selected for DDT resistance. Finally, I address the function of a brain-specific P450 that is highly conserved across Drosophila species, by using a GAL4/UAS RNAi system to study the reproductive effects of knocking down the gene Cyp4g15. Using molecular modeling of the Cyp4g15 protein, I propose a potential substrate for this enzyme, the pheromone cis-vaccenyl acetate

A reassessment of the interaction between complement C3d and complement receptor CD21 SCR1-2

Biophysical characterisation of protein – ligand interactions can provide vital information to dissect complex biochemical binding mechanisms. C3d has been shown to interact with a number of different protein ligands, namely CD21 SCR1-2, S. aureus Efb-C, S. aureus Ehp, S. aureus Sbi and complement regulatory protein factor H. Although much is known about the relationship of C3d and CD21 in the induction of humoral immunity, the structural aspects of this interaction remained controversial until very recently. The aim of this thesis was to gain a detailed understanding of the C3d/CD21 SCR1-2 interaction using different biophysical methods and to identify potential low molecular weight inhibitors of the interaction. A crystal structure of the C3d/CD21 complex solved by Szakonyi et al. in 2001 indicated the C3d binding site on CD21 was in the SCR2 domain. It did not agree with mutagenesis studies and recent NMR titration experiments show that only residues from the SCR1 domain of CD21 appear to mediate binding under physiologically relevant ionic strength. In the current work, NMR was employed to monitor ligand binding to C3d and to provide residue specific information that reflects a physiologically relevant binding mode to complement the crystallographic model solved by van den Elsen and Isenman in 2011. Microcalorimetric analysis on the site-directed mutagenesis studies also supported a model of hydrophobically- and electrostatically-driven protein-protein interaction for C3d and CD21 SCR1-2. Complement C3d forms a non-specific thioester linkage with antigen, which then binds to CD21 SCR1-2 and coligates with membrane immunoglobulin of the B cell receptor. While the interactions triggers B cell activation and hence the production of antibody under normal circumstances, it has been demonstrated that the interactions also lead to undue B cell activation and auto-antibody production. There is a well established collagen-induced arthritis (CIA) mouse model to support the significance of C3d and CD21 in disease susceptibility. To this end, a high-throughput SPR-based screening platform was set up to screen a fragment library against C3d, so as to identify low molecular weight compounds that could serve as a starting point for drug development programme. Unfortunately, the work did not yield C3d-binding inhibitors and future work could include screening large fragment libraries that are designed to target protein-protein interfaces.EThOS - Electronic Theses Online ServiceGBUnited Kingdo