Aim
To review the clinical course, outcome and incidence of infantile salt wasting associated with urinary tract infection (UTI) and/or urinary tract malformation (UTM) over a two‐year surveillance ...period on the island of Ireland.
Methods
A two‐year (2013‐14) prospective surveillance undertaken via the Irish and Ulster Paediatric Surveillance Units. Monthly prepaid postcards were circulated to consultant paediatricians (n = 260) at all paediatric units on the island of Ireland. Infants under one year of age presenting for the first time with hyponatraemia (Na < 130 mmol/L) and/or hyperkalaemia (K > 5.0 mmol/L) associated with urosepsis/UTM were reported.
Results
All 7 reported patients (6 male) had culture‐proven UTI, and 5 (71%) also had an underlying UTM (one diagnosed antenatally). Four (57%) patients had a documented elevated serum aldosterone supporting secondary pseudohypoaldosteronism (PHA) as the underlying diagnosis. Data on aldosterone were not reported in the other 3 patients, but clinical features were suggestive of secondary PHA. The estimated incidence for the Irish population of transient PHA is 1 per 13,200 total live births per year.
Conclusions
Salt wasting is a rare complication of UTI, especially if associated with underlying UTM. Boys appear to be at particular risk.
Contact!Unload, a research-based theatre production, portrays veterans experiencing mental health challenges and overcoming them through therapeutic enactment. It was performed eight times by veteran ...performers in 2017 for audiences in two Canadian cities comprised of civilians and military-connected personnel and their families (n = 525).
Drawing upon qualitative and quantitative data sources, this paper evaluates the immediate and longer-term impacts of Contact!Unload as a knowledge translation intervention for audience members.
Our findings suggest that the performance: 1) improved knowledge of mental health concerns and symptoms that some veterans experience when transitioning to civilian life, 2) increased knowledge of the need for mental health supports and care for veterans, 3) sustained impacts on awareness and knowledge six months after the play and 4) sparked dialogue and actions after the show for some audience members. Moreover, theatre was seen as a powerful medium to engage audience members both cognitively and affectively in the topic.
Research-based theatre has significant potential as a knowledge translation intervention for mental health topics. The work also points to the untapped potential of using RbT to engage audience members in a mental health literacy intervention. Future work is needed to study how to effectively combine research-based theatre with intervention design frameworks and other mental health literacy interventions.
•Research-based theatre (RbT) is an effective method for knowledge translation.•The embodied experience of theatre bolsters empathy and receptivity to learning.•Short and longer-term cognitive and affective impacts for audiences were achieved.•RbT can also shift social responses to and professional practices in mental health.•RbT holds untapped potential as a mental health literacy intervention.
Pore-forming proteins containing the structurally conserved membrane attack complex/perforin fold play an important role in immunity and host-pathogen interactions. Intermedilysin (ILY) is an ...archetypal member of a cholesterol-dependent cytolysin subclass that hijacks the complement receptor CD59 to make cytotoxic pores in human cells. ILY directly competes for the membrane attack complex binding site on CD59, rendering cells susceptible to complement lysis. To understand how these bacterial pores form in lipid bilayers and the role CD59 plays in complement regulation, we determined the crystal structure of human CD59 bound to ILY. Here, we show the ILY-CD59 complex at 3.5 Å resolution and identify two interfaces mediating this host-pathogen interaction. An ILY-derived peptide based on the binding site inhibits pore formation in a CD59-containing liposome model system. These data provide insight into how CD59 coordinates ILY monomers, nucleating an early prepore state, and suggest a potential mechanism of inhibition for the complement terminal pathway.
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•Crystal structure of the ILY-CD59 complex defines two interfaces•Our two binding interfaces are supported by previous mutagenesis studies•An ILY-derived peptide competes for binding in a liposome model system•Our model provides a structural basis for CD59 nucleation of an ILY early prepore
The crystal structure of human CD59 in complex with the bacterial toxin intermedilysin (ILY) is now presented by Bubeck and colleagues. These results suggest that CD59 positions the cholesterol-binding motif of ILY in proximity to the membrane and nucleates oligomerization of ILY monomers through two binding faces. This model for CD59 function gives insight into the mechanism of cholesterol-dependent cytolysin pore formation and provides a framework for future investigation probing regulation of the complement terminal pathway.
The PhoD family of extra-cytoplasmic phosphodiesterases are among the most commonly occurring bacterial phosphatases. The exemplars for this family are the PhoD protein of Bacillus subtilis and the ...phospholipase D of Streptomyces chromofuscus. We present the crystal structure of B. subtilis PhoD. PhoD is most closely related to purple acid phosphatases (PAPs) with both types of enzyme containing a tyrosinate-ligated Fe3+ ion. However, the PhoD active site diverges from that found in PAPs and uses two Ca2+ ions instead of the single extra Fe2+, Mn2+, or Zn2+ ion present in PAPs. The PhoD crystals contain a phosphate molecule that coordinates all three active site metal ions and that is proposed to represent a product complex. A C-terminal helix lies over the active site and controls access to the catalytic center. The structure of PhoD defines a new phosphatase active site architecture based on Fe3+ and Ca2+ ions.
Natural transformation is the widespread biological process by which "competent" bacteria take up free DNA, incorporate it into their genomes, and become genetically altered or "transformed". To curb ...often deleterious transformation by foreign DNA, several competent species preferentially take up their own DNA that contains specific DUS (DNA uptake sequence) watermarks. Our recent finding that ComP is the long sought DUS receptor in Neisseria species paves the way for the functional analysis of the DUS-ComP interdependence which is reported here. By abolishing/modulating ComP levels in Neisseria meningitidis, we show that the enhancement of transformation seen in the presence of DUS is entirely dependent on ComP, which also controls transformation in the absence of DUS. While peripheral bases in the DUS were found to be less important, inner bases are essential since single base mutations led to dramatically impaired interaction with ComP and transformation. Strikingly, naturally occurring DUS variants in the genomes of human Neisseria commensals differing from DUS by only one or two bases were found to be similarly impaired for transformation of N. meningitidis. By showing that ComPsub from the N. subflava commensal specifically binds its cognate DUS variant and mediates DUS-enhanced transformation when expressed in a comP mutant of N. meningitidis, we confirm that a similar mechanism is used by all Neisseria species to promote transformation by their own, or closely related DNA. Together, these findings shed new light on the molecular events involved in the earliest step in natural transformation, and reveal an elegant mechanism for modulating horizontal gene transfer between competent species sharing the same niche.
Folates (also known as vitamin B9) have a critical role in cellular metabolism as the starting point in the synthesis of nucleic acids, amino acids and the universal methylating agent ...S-adenylsmethionine
. Folate deficiency is associated with a number of developmental, immune and neurological disorders
. Mammals cannot synthesize folates de novo; several systems have therefore evolved to take up folates from the diet and distribute them within the body
. The proton-coupled folate transporter (PCFT) (also known as SLC46A1) mediates folate uptake across the intestinal brush border membrane and the choroid plexus
, and is an important route for the delivery of antifolate drugs in cancer chemotherapy
. How PCFT recognizes folates or antifolate agents is currently unclear. Here we present cryo-electron microscopy structures of PCFT in a substrate-free state and in complex with a new-generation antifolate drug (pemetrexed). Our results provide a structural basis for understanding antifolate recognition and provide insights into the pH-regulated mechanism of folate transport mediated by PCFT.
Alkaline phosphatases play a crucial role in phosphate acquisition by microorganisms. To expand our understanding of catalysis by this class of enzymes, we have determined the structure of the widely ...occurring microbial alkaline phosphatase PhoX. The enzyme contains a complex active-site cofactor comprising two antiferromagnetically coupled ferric iron ions (Fe3+), three calcium ions (Ca2+), and an oxo group bridging three of the metal ions. Notably, the main part of the cofactor resembles synthetic oxide-centered triangular metal complexes. Structures of PhoX-ligand complexes reveal how the active-site metal ions bind substrate and implicate the cofactor oxo group in the catalytic mechanism. The presence of iron in PhoX raises the possibility that iron bioavailability limits microbial phosphate acquisition.
Mapping of epitopes recognized by functional monoclonal antibodies (mAbs) is essential for understanding the nature of immune responses and designing improved vaccines, therapeutics, and diagnostics. ...In recent years, identification of B-cell epitopes targeted by neutralizing antibodies has facilitated the design of peptide-based vaccines against highly variable pathogens like HIV, respiratory syncytial virus, and Helicobacter pylori ; however, none of these products has yet progressed into clinical stages. Linear epitopes identified by conventional mapping techniques only partially reflect the immunogenic properties of the epitope in its natural conformation, thus limiting the success of this approach. To investigate antigen–antibody interactions and assess the potential of the most common epitope mapping techniques, we generated a series of mAbs against factor H binding protein (fHbp), a key virulence factor and vaccine antigen of Neisseria meningitidis . The interaction of fHbp with the bactericidal mAb 12C1 was studied by various epitope mapping methods. Although a 12-residue epitope in the C terminus of fHbp was identified by both Peptide Scanning and Phage Display Library screening, other approaches, such as hydrogen/deuterium exchange mass spectrometry (MS) and X-ray crystallography, showed that mAb 12C1 occupies an area of ∼1,000 Å ² on fHbp, including >20 fHbp residues distributed on both N- and C-terminal domains. Collectively, these data show that linear epitope mapping techniques provide useful but incomplete descriptions of B-cell epitopes, indicating that increased efforts to fully characterize antigen–antibody interfaces are required to understand and design effective immunogens.
CD6 is a transmembrane protein with an extracellular region containing three scavenger receptor cysteine rich (SRCR) domains. The membrane proximal domain of CD6 binds the N-terminal immunoglobulin ...superfamily (IgSF) domain of another cell surface receptor, CD166, which also engages in homophilic interactions. CD6 expression is mainly restricted to T cells, and the interaction between CD6 and CD166 regulates T-cell activation. We have solved the X-ray crystal structures of the three SRCR domains of CD6 and two N-terminal domains of CD166. This first structure of consecutive SRCR domains reveals a nonlinear organization. We characterized the binding sites on CD6 and CD166 and showed that a SNP in CD6 causes glycosylation that hinders the CD6/CD166 interaction. Native mass spectrometry analysis showed that there is competition between the heterophilic and homophilic interactions. These data give insight into how interactions of consecutive SRCR domains are perturbed by SNPs and potential therapeutic reagents.
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•First structure of consecutive scavenger receptor cysteine rich domains in CD6•Structure of the two N-terminal domains of CD166 which is the ligand for CD6•Mapping binding sites on CD6 and CD166•Insight into how CD6 and its interactions are perturbed by polymorphisms and mAbs
Chappell et al. present structures of the T-cell surface receptor, CD6, the first of consecutive scavenger receptor cysteine rich domains and its ligand, CD166. The structures give insight into how CD6 and its interactions are perturbed by competition between homophilic and heterophilic interactions, SNPs, and mAbs.
The complement system is a crucial part of innate immune defenses against invading pathogens. The blood-meal of the tick Rhipicephalus pulchellus lasts for days, and the tick must therefore rely on ...inhibitors to counter complement activation. We have identified a class of inhibitors from tick saliva, the CirpT family, and generated detailed structural data revealing their mechanism of action. We show direct binding of a CirpT to complement C5 and have determined the structure of the C5–CirpT complex by cryoelectron microscopy. This reveals an interaction with the peripheral macro globulin domain 4 (C5_MG4) of C5. To achieve higher resolution detail, the structure of the C5_MG4–CirpT complex was solved by X-ray crystallography (at 2.7 Å). We thus present the fold of the CirpT protein family, and provide detailed mechanistic insights into its inhibitory function. Analysis of the binding interface reveals a mechanism of C5 inhibition, and provides information to expand our biological understanding of the activation of C5, and thus the terminal complement pathway.
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