Enhancement of microphase ordering and mechanical properties of supramolecular hydrogen-bonded polyurethane networks

The improvement of the mechanical properties of supramolecular polymer networks is currently receiving significant interest both within academic and industrial circles in order to enable the application of these desirable stimuli-responsive materials in real world situations. In this study, structural units within phase separated supramolecular polyurethane (SPU) networks have been changed to assess the role of the hard segment composition on the mechanical characteristics of the resultant materials. Notably, increasing the degrees of conformational freedom within the hard segment component of a SPU was found to improve the phase separation and as a consequence also increase the storage modulus of the polymer network. Specifically, replacing 4,4′-methylene diphenyl diisocyanate with 4,4’-dibenzyl diisocyanate within a SPU improved the packing efficiency of the isocyanate derived hard segments and improved the physical properties of the supramolecular polymer network. This study utilised a combination of SAXS, WAXS and AFM analysis to assess the degree of crystallinity within the hard segment component of the polymer network whilst rheological analysis was used to establish the mechanical characteristics of the polymers

The effect of chiral end groups on the assembly of supramolecular polyurethanes

The ability to influence the physical properties of supramolecular polymers has been the subject of numerous synthetic studies in recent years. Tuning properties by adjustment of the polymer composition to modify the degree of phase separation of polar (hard) and apolar (soft) segments in addition to variation of the capability of the polar end groups to self-assemble efficiently via non-covalent interactions (such as hydrogen bonding, aromatic - stacking or metal-ligand binding) has yielded materials with attractive thermo-reversible characteristics. Previously, we have studied supramolecular polyurethanes (SPUs) to understand in more detail the interplay and importance of phase separation and the binding affinity of the polar end group on the physical properties of these interesting thermo-responsive materials. In this paper, we report the positive effect that chirality has upon the self-assembly and physical properties of SPUs. The synthesis of a series of novel SPUs that feature chiral polar end-groups is described in addition to how these chiral moieties improve the order of the relatively weak hydrogen bonding units in this type of supramolecular polymer. The introduction of chiral moieties in the polymer end group induces cooperative arrangements of the components of the hard segments (urethane, urea and aromatic units), leading to SPUs with increased ordered and stronger supramolecular hard segments. The supramolecular interactions of the chiral hard segments were first evaluated by CD and FTIR spectroscopies. In addition, the thermo-responsive nano-segregated structure formed by the columnar aggregates of the SPUs generated was probed by variable temperature CD and FTIR spectroscopies in addition to simultaneous SAXS/WAXS analysis. These studies confirmed the microphase separation morphology also revealed by AFM analysis. Additionally, rheological analysis of the chiral SPUs highlighted the enhancement of the rubbery plateau of chiral SPUs derivatives in comparison to analogous racemic SPUs as a result of the chiral self-assembly motifs. Finally, to explore the mechanical properties of the afforded polymers, electrospinning experiments were undertaken which revealed that defined microfibers were formed at lower concentrations in the case of the homochiral SPUs (ca. 15%) when compared to the racemic analogue, thus confirming the improvement in the supramolecular interactions afforded by the chiral groups

Evaluating remote facilitation intensity for multi-national translation of nurse-initiated stroke protocols (QASC Australasia) : A protocol for a cluster randomised controlled trial

Background Facilitated implementation of nurse-initiated protocols to manage fever, hyperglycaemia (sugar) and swallowing difficulties (FeSS Protocols) in 19 Australian stroke units resulted in reduced death and dependency for stroke patients. However, a significant gap remains in translating this evidence-based care bundle protocol into standard practice in Australia and New Zealand. Facilitation is a key component for increasing implementation. However, its contribution to evidence translation initiatives requires further investigation. We aim to evaluate two levels of intensity of external remote facilitation as part of a multifaceted intervention to improve FeSS Protocol uptake and quality of care for patients with stroke in Australian and New Zealand acute care hospitals. Methods A three-arm cluster randomised controlled trial with a process evaluation and economic evaluation. Australian and New Zealand hospitals with a stroke unit or service will be recruited and randomised in blocks of five to one of the three study arms—high- or low-intensity external remote facilitation or a no facilitation control group—in a 2:2:1 ratio. The multicomponent implementation strategy will incorporate implementation science frameworks (Theoretical Domains Framework, Capability, Opportunity, Motivation – Behaviour Model and the Consolidated Framework for Implementation Research) and include an online education package, audit and feedback reports, local clinical champions, barrier and enabler assessments, action plans, reminders and external remote facilitation. The primary outcome is implementation effectiveness using a composite measure comprising six monitoring and treatment elements of the FeSS Protocols. Secondary outcome measures are as follows: composite outcome of adherence to each of the combined monitoring and treatment elements for (i) fever (n=5); (ii) hyperglycaemia (n=6); and (iii) swallowing protocols (n=7); adherence to the individual elements that make up each of these protocols; comparison for composite outcomes between (i) metropolitan and rural/remote hospitals; and (ii) stroke units and stroke services. A process evaluation will examine contextual factors influencing intervention uptake. An economic evaluation will describe cost differences relative to each intervention and study outcomes. Discussion We will generate new evidence on the most effective facilitation intensity to support implementation of nurse-initiated stroke protocols nationwide, reducing geographical barriers for those in rural and remote areas. Trial registration ACTRN12622000028707. Registered 14 January, 2022

Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke

Genetic factors have been implicated in stroke risk but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) in ischemic stroke and its subtypes in 3,548 cases and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 cases and 6,281 controls. We replicated reported associations between variants close to PITX2 and ZFHX3 with cardioembolic stroke, and a 9p21 locus with large vessel stroke. We identified a novel association for a SNP within the histone deacetylase 9(HDAC9) gene on chromosome 7p21.1 which was associated with large vessel stroke including additional replication in a further 735 cases and 28583 controls (rs11984041, combined P = 1.87×10−11, OR=1.42 (95% CI) 1.28-1.57). All four loci exhibit evidence for heterogeneity of effect across the stroke subtypes, with some, and possibly all, affecting risk for only one subtype. This suggests differing genetic architectures for different stroke subtypes

Bio-Repository of DNA in stroke (BRAINS): A study protocol

<p>Abstract</p> <p>Background</p> <p>Stroke is one of the commonest causes of mortality in the world and anticipated to be an increasing burden to the developing world. Stroke has a genetic basis and identifying those genes may not only help us define the mechanisms that cause stroke but also identify novel therapeutic targets. However, large scale highly phenotyped DNA repositories are required in order for this to be achieved.</p> <p>Methods</p> <p>The proposed Bio-Repository of DNA in Stroke (BRAINS) will recruit all subtypes of stroke as well as controls from two different continents, Europe and Asia. Subjects recruited from the UK will include stroke patients of European ancestry as well as British South Asians. Stroke subjects from South Asia will be recruited from India and Sri Lanka. South Asian cases will also have control subjects recruited.</p> <p>Discussion</p> <p>We describe a study protocol to establish a large and highly characterized stroke biobank in those of European and South Asian descent. With different ethnic populations being recruited, BRAINS has the ability to compare and contrast genetic risk factors between those of differing ancestral descent as well as those who migrate into different environments.</p

Silent brain infarction in the presence of systemic vascular disease

Objective To determine the prevalence of asymptomatic brain ischaemic in the presence of vascular disease in other arterial territories. Design Studies up to January 2011 were identified through comprehensive search strategies. Arcsine transformation for metaanalysis was used to calculate the standardized mean difference (SMD) and 95% confidence intervals (CI). Setting A systematic review and meta-analysis were performed. Participants For each study, the proportion of patients positive for SBI in the presence of other systemic vascular disease was extracted and analyzed. Main outcome measures Using a random-effects model, a pooled effect estimate interpreted as a percentage prevalence of disease was calculated. Results SBI in the presence of acute ischaemic stroke was found in 23% (SMD 0.99; P < 0.001; 95% CI 0.88-1.10); a 35% prevalence was found in patients with coronary artery disease (SMD 1.26; P < 0.001; 95% CI 0.95-1.58); and a 14% prevalence in patients with peripheral artery disease (SMD 0.48; P< 0.002; 95% CI 0.42-0.54), although the data-set in the latter is smaller. Conclusions Patients with systemic vascular disease are at an increased risk of silent brain infarction

Best practice in clinical simulation education - are we there yet? A cross-sectional survey of simulation in Australian and New Zealand undergraduate nursing education

© 2017 Australian College of Nursing Ltd. Background: Simulation is potentially a means of increasing clinical education capacity. Significant investments have been made in simulation but the extent to which this has improved uptake, quality and diversity of simulation use is unclear. Aim: To describe the current use of simulation in tertiary nursing education programs leading to nurse registration Australia and New Zealand, and determine whether investments in simulation have improved uptake, quality and diversity of simulation experiences. Methods: A cross sectional electronic survey distributed to lead nursing academics in programs leading to nurse registration in Australia and New Zealand. Findings: 51.6% of institutions responded and reported wide variation in allocation of program hours to clinical and simulation learning. Simulation was embedded in curricula and positively valued as an adjunct or substitute for clinical placement. While simulation environments were adequate, staff time, training and resource development were barriers to increasing the quality, amount and range of simulation experiences. Quality assurance and robust evaluation were weak. Discussion: Simulation program hours are inconsistently reported and underutilized in terms of potential contribution to clinical learning. Benefits of capital investment in simulation physical resources have been realised, but barriers persist for increasing high quality simulation in nursing programs. Conclusion: Transitioning components of clinical education from the clinical to tertiary sectors has resource implications. Establishment of sustainable, high quality simulation experiences requires staff training, shared resources, best practice and robust evaluation of simulation experiences in nursing curricula