Engineering Planar Gram-Negative Outer Membrane Mimics Using Bacterial Outer Membrane Vesicles.

Antibiotic resistance is a major challenge in modern medicine. The unique double membrane structure of gram-negative bacteria limits the efficacy of many existing antibiotics and adds complexity to antibiotic development by limiting transport of antibiotics to the bacterial cytosol. New methods to mimic this barrier would enable high-throughput studies for antibiotic development. In this study, we introduce an innovative approach to modify outer membrane vesicles (OMVs) from Aggregatibacter actinomycetemcomitans, to generate planar supported lipid bilayer membranes. Our method first involves the incorporation of synthetic lipids into OMVs using a rapid freeze-thaw technique to form outer membrane hybrid vesicles (OM-Hybrids). Subsequently, these OM-Hybrids can spontaneously rupture when in contact with SiO2 surfaces to form a planar outer membrane supported bilayer (OM-SB). We assessed the formation of OM-Hybrids using dynamic light scattering and a fluorescence quenching assay. To analyze the formation of OM-SBs from OM-Hybrids we used quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence recovery after photobleaching (FRAP). Additionally, we conducted assays to detect surface-associated DNA and proteins on OM-SBs. The interaction of an antimicrobial peptide, polymyxin B, with the OM-SBs was also assessed. These findings emphasize the capability of our platform to produce planar surfaces of bacterial outer membranes, which in turn, could function as a valuable tool for streamlining the development of antibiotics.

Ischaemic events in hypertrophic cardiomyopathy patients with and without atrial fibrillation: a systematic review and meta-analysis.

Hypertrophic cardiomyopathy predisposes to acute cerebrovascular events including ischaemic stroke, transient ischaemic attack and systemic thromboembolism. Atrial fibrillation confers even higher risk. We aim to report the incidence of these complications and to investigate the impact of atrial fibrillation on the ischaemic risk in patients with hypertrophic cardiomyopathy. A literature search was performed on PubMed, Scopus, Embase/Ovid and Cochrane library from inception to 20th March 2021. We compared the incidence of ischaemic strokes, transient ischaemic attack, non-specified thromboembolism events and systemic thromboembolism in hypertrophic cardiomyopathy patients with or without atrial fibrillation. Non-specified thromboembolism events in our paper referred to thromboembolic events whereby types were not specified in the studies. Meta-analysis was performed using StataSE 16 software, and heterogeneity was assessed using I2 test. A total of 713 studies were identified. Thirty-five articles with 42,570 patients were included. The pooled incidence of stroke/ transient ischaemic attack was 7.45% (95% confidence interval [CI] 5.80-9.52, p < 0.001) across 24 studies with a total of 37,643 hypertrophic cardiomyopathy patients. Atrial fibrillation significantly increased the risk of total stroke/ transient ischaemic attack (Risk Ratio 3.26, 95% CI 1.75-6.08, p < 0.001, I2 = 76.0). The incidence of stroke/ transient ischaemic attack was 9.30% (95% CI 6.64-12.87, p = 0.316) in the apical hypertrophic cardiomyopathy subgroup. Concomitant atrial fibrillation in hypertrophic cardiomyopathy increases the risk of thromboembolic events including ischaemic stroke and transient ischaemic attack. The apical subgroup shows a similar risk of acute cerebrovascular events as the overall hypertrophic cardiomyopathy population.

Incidence of acute cerebrovascular events in patients with rheumatic or calcific mitral stenosis: A systematic review and meta-analysis.

BACKGROUND: Patients with mitral stenosis (MS) may be predisposed to acute cerebrovascular events (ACE) and peripheral thromboembolic events (TEE). Concomitant atrial fibrillation (AF), mitral annular calcification (MAC) and rheumatic heart disease (RHD) are independent risk factors. Our aim was to evaluate the incidence of ACEs in MS patients and the implications of AF, MAC and RHD on thromboembolic risks. METHODS: This systematic review was registered on PROSPERO (CRD42021291316). Six databases were searched from inception to 19th December 2021. The clinical outcomes were composite ACE, ischaemic stroke/transient ischaemic attack (TIA) and peripheral TEE. RESULTS: We included 16 and 9 papers, respectively, in our qualitative and quantitative analyses. The MS cohort with AF had the highest incidence of composite ACE (31.55%; 95% CI 3.60-85.03; I2 = 99%), followed by the MAC (14.85%; 95% CI 7.21-28.11; I2 = 98%), overall MS (8.30%; 95% CI 3.45-18.63; I2 = 96%) and rheumatic MS population (4.92%; 95% CI 3.53-6.83; I2 = 38%). Stroke/TIA were reported in 29.62% of the concomitant AF subgroup (95% CI 2.91-85.51; I2 = 99%) and in 7.11% of the overall MS patients (95% CI 1.91-23.16; I2 = 97%). However, the heterogeneity of the pooled incidence of clinical outcomes in all groups, except the rheumatic MS group, was substantial and significant. The logit-transformed proportion of composite ACE increased by 0.0141 (95% CI 0.0111-0.0171; p < 0.01) per year of follow-up. CONCLUSION: In the MS population, MAC and concomitant AF are risk factors for the development of ACE. The scarcity of data in our systematic review reflects the need for further studies to explore thromboembolic risks in all MS subtypes.

Surgical outcomes of congenital arachnoid cysts and their association with neurodevelopmental disorders.

BACKGROUND: To evaluate the surgical outcomes of arachnoid cyst decompression in patients less than 16 years of age with an associated neurodevelopmental disorder (NDD). METHODS: A retrospective analysis of surgically treated congenital arachnoid cyst within South Wales between 2010-2019. Surgical outcomes are measured according to clinical (COG; clinical outcome score) and radiological (NOG; neuroimaging outcome score) outcomes and the complication profiles are described. The association between arachnoid cysts and NDD both in South Wales and the literature review cohort is also discussed. RESULTS: The prevalence of congenital arachnoid cysts in South Wales is 0.02% and their association with neurodevelopmental disorders among patients with a congenital arachnoid cyst is high (estimated prevalence 19%). 18 (51%) in total were surgically treated in our unit; 7 with an associated NDD. All surgical modalities showed improved clinical and radiological outcomes in those with an associated neurodevelopmental disorder. 4 (15%) patients who had endoscopic treatment, and 2 (7%) of those who underwent craniotomy had complications. No complications following cystoperitoneal shunt were seen. 4 (21%) surgically treated patients were ultimately shunted following initial treatment by endoscopy or craniotomy. CONCLUSIONS: In a cohort of patients diagnosed with a congenital arachnoid cyst in association with a neurodevelopmental disorder, all surgical treatments show improved clinical and radiological outcomes. Cystoperitoneal shunting appears to have a favourable complication profile.