Synthetic biology: advancing biological frontiers by building synthetic systems

Advances in synthetic biology are contributing to diverse research areas, from basic biology to biomanufacturing and disease therapy. We discuss the theoretical foundation, applications, and potential of this emerging field

The Cauchy problem on a characteristic cone for the Einstein equations in arbitrary dimensions

We derive explicit formulae for a set of constraints for the Einstein equations on a null hypersurface, in arbitrary dimensions. We solve these constraints and show that they provide necessary and sufficient conditions so that a spacetime solution of the Cauchy problem on a characteristic cone for the hyperbolic system of the reduced Einstein equations in wave-map gauge also satisfies the full Einstein equations. We prove a geometric uniqueness theorem for this Cauchy problem in the vacuum case.Comment: 83 pages, 1 figur

The sound of silence:Transgene silencing in mammalian cell engineering

To elucidate principles operating in native biological systems and to develop novel biotechnologies, synthetic biology aims to build and integrate synthetic gene circuits within native transcriptional networks. The utility of synthetic gene circuits for cell engineering relies on the ability to control the expression of all constituent transgene components. Transgene silencing, defined as the loss of expression over time, persists as an obstacle for engineering primary cells and stem cells with transgenic cargos. In this review, we highlight the challenge that transgene silencing poses to the robust engineering of mammalian cells, outline potential molecular mechanisms of silencing, and present approaches for preventing transgene silencing. We conclude with a perspective identifying future research directions for improving the performance of synthetic gene circuits.ISSN:2405-472

Treatments and outcomes among patients with Sydenham chorea

Importance: Sydenham chorea is the most common acquired chorea of childhood worldwide; however, treatment is limited by a lack of high-quality evidence. Objectives: To evaluate historical changes in the clinical characteristics of Sydenham chorea and identify clinical and treatment factors at disease onset associated with chorea duration, relapsing disease course, and functional outcome. Data Sources: The systematic search for this meta-analysis was conducted in PubMed, Embase, CINAHL, Cochrane Library, and LILACS databases and registers of clinical trials from inception to November 1, 2022 (search terms: [Sydenham OR Sydenham’s OR rheumatic OR minor] AND chorea). Study Selection: Published articles that included patients with a final diagnosis of Sydenham chorea (in selected languages). Data Extraction and Synthesis: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Individual patient data on clinical characteristics, treatments, chorea duration, relapse, and final outcome were extracted. Data from patients in the modern era (1945 through 2022) were entered into multivariable models and stratified by corticosteroid duration for survival analysis of chorea duration. Main Outcomes and Measures: The planned study outcomes were chorea duration at onset, monophasic course (absence of relapse after ≥24 months), and functional outcome (poor: modified Rankin Scale score 2-6 or persisting chorea, psychiatric, or behavioral symptoms at final follow-up after ≥6 months; good: modified Rankin Scale score 0-1 and no chorea, psychiatric, or behavioral symptoms at final follow-up). Results: In total, 1479 patients were included (from 307 articles), 1325 since 1945 (median [IQR] age at onset, 10 [8-13] years; 875 of 1272 female [68.8%]). Immunotherapy was associated with shorter chorea duration (hazard ratio for chorea resolution, 1.51 [95% CI, 1.05-2.19]; P = .03). The median chorea duration in patients receiving 1 or more months of corticosteroids was 1.2 months (95% CI, 1.2-2.0) vs 2.8 months (95% CI, 2.0-3.0) for patients receiving none (P = .004). Treatment factors associated with monophasic disease course were antibiotics (odds ratio [OR] for relapse, 0.28 [95% CI, 0.09-0.85]; P = .02), corticosteroids (OR, 0.32 [95% CI, 0.15-0.67]; P = .003), and sodium valproate (OR, 0.33 [95% CI, 0.15-0.71]; P = .004). Patients receiving at least 1 month of corticosteroids had significantly lower odds of relapsing course (OR, 0.10 [95% CI, 0.04-0.25]; P < .001). No treatment factor was associated with good functional outcome. Conclusions and Relevance: In this meta-analysis of treatments and outcomes in patients with Sydenham chorea, immunotherapy, in particular corticosteroid treatment, was associated with faster resolution of chorea. Antibiotics, corticosteroids and sodium valproate were associated with a monophasic disease course. This synthesis of retrospective data should support the development of evidence-based treatment guidelines for patients with Sydenham chorea

Basic science232. Certolizumab pegol prevents pro-inflammatory alterations in endothelial cell function

Background: Cardiovascular disease is a major comorbidity of rheumatoid arthritis (RA) and a leading cause of death. Chronic systemic inflammation involving tumour necrosis factor alpha (TNF) could contribute to endothelial activation and atherogenesis. A number of anti-TNF therapies are in current use for the treatment of RA, including certolizumab pegol (CZP), (Cimzia ®; UCB, Belgium). Anti-TNF therapy has been associated with reduced clinical cardiovascular disease risk and ameliorated vascular function in RA patients. However, the specific effects of TNF inhibitors on endothelial cell function are largely unknown. Our aim was to investigate the mechanisms underpinning CZP effects on TNF-activated human endothelial cells. Methods: Human aortic endothelial cells (HAoECs) were cultured in vitro and exposed to a) TNF alone, b) TNF plus CZP, or c) neither agent. Microarray analysis was used to examine the transcriptional profile of cells treated for 6 hrs and quantitative polymerase chain reaction (qPCR) analysed gene expression at 1, 3, 6 and 24 hrs. NF-κB localization and IκB degradation were investigated using immunocytochemistry, high content analysis and western blotting. Flow cytometry was conducted to detect microparticle release from HAoECs. Results: Transcriptional profiling revealed that while TNF alone had strong effects on endothelial gene expression, TNF and CZP in combination produced a global gene expression pattern similar to untreated control. The two most highly up-regulated genes in response to TNF treatment were adhesion molecules E-selectin and VCAM-1 (q 0.2 compared to control; p > 0.05 compared to TNF alone). The NF-κB pathway was confirmed as a downstream target of TNF-induced HAoEC activation, via nuclear translocation of NF-κB and degradation of IκB, effects which were abolished by treatment with CZP. In addition, flow cytometry detected an increased production of endothelial microparticles in TNF-activated HAoECs, which was prevented by treatment with CZP. Conclusions: We have found at a cellular level that a clinically available TNF inhibitor, CZP reduces the expression of adhesion molecule expression, and prevents TNF-induced activation of the NF-κB pathway. Furthermore, CZP prevents the production of microparticles by activated endothelial cells. This could be central to the prevention of inflammatory environments underlying these conditions and measurement of microparticles has potential as a novel prognostic marker for future cardiovascular events in this patient group. Disclosure statement: Y.A. received a research grant from UCB. I.B. received a research grant from UCB. S.H. received a research grant from UCB. All other authors have declared no conflicts of interes

Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Staphylococcus aureus bacteraemia is a common cause of severe community-acquired and hospital-acquired infection worldwide. We tested the hypothesis that adjunctive rifampicin would reduce bacteriologically confirmed treatment failure or disease recurrence, or death, by enhancing early S aureus killing, sterilising infected foci and blood faster, and reducing risks of dissemination and metastatic infection. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, adults (≥18 years) with S aureus bacteraemia who had received ≤96 h of active antibiotic therapy were recruited from 29 UK hospitals. Patients were randomly assigned (1:1) via a computer-generated sequential randomisation list to receive 2 weeks of adjunctive rifampicin (600 mg or 900 mg per day according to weight, oral or intravenous) versus identical placebo, together with standard antibiotic therapy. Randomisation was stratified by centre. Patients, investigators, and those caring for the patients were masked to group allocation. The primary outcome was time to bacteriologically confirmed treatment failure or disease recurrence, or death (all-cause), from randomisation to 12 weeks, adjudicated by an independent review committee masked to the treatment. Analysis was intention to treat. This trial was registered, number ISRCTN37666216, and is closed to new participants. FINDINGS: Between Dec 10, 2012, and Oct 25, 2016, 758 eligible participants were randomly assigned: 370 to rifampicin and 388 to placebo. 485 (64%) participants had community-acquired S aureus infections, and 132 (17%) had nosocomial S aureus infections. 47 (6%) had meticillin-resistant infections. 301 (40%) participants had an initial deep infection focus. Standard antibiotics were given for 29 (IQR 18-45) days; 619 (82%) participants received flucloxacillin. By week 12, 62 (17%) of participants who received rifampicin versus 71 (18%) who received placebo experienced treatment failure or disease recurrence, or died (absolute risk difference -1·4%, 95% CI -7·0 to 4·3; hazard ratio 0·96, 0·68-1·35, p=0·81). From randomisation to 12 weeks, no evidence of differences in serious (p=0·17) or grade 3-4 (p=0·36) adverse events were observed; however, 63 (17%) participants in the rifampicin group versus 39 (10%) in the placebo group had antibiotic or trial drug-modifying adverse events (p=0·004), and 24 (6%) versus six (2%) had drug interactions (p=0·0005). INTERPRETATION: Adjunctive rifampicin provided no overall benefit over standard antibiotic therapy in adults with S aureus bacteraemia. FUNDING: UK National Institute for Health Research Health Technology Assessment

Global Landscape Review of Serotype-Specific Invasive Pneumococcal Disease Surveillance among Countries Using PCV10/13: The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) Project.

Serotype-specific surveillance for invasive pneumococcal disease (IPD) is essential for assessing the impact of 10- and 13-valent pneumococcal conjugate vaccines (PCV10/13). The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project aimed to evaluate the global evidence to estimate the impact of PCV10/13 by age, product, schedule, and syndrome. Here we systematically characterize and summarize the global landscape of routine serotype-specific IPD surveillance in PCV10/13-using countries and describe the subset that are included in PSERENADE. Of 138 countries using PCV10/13 as of 2018, we identified 109 with IPD surveillance systems, 76 of which met PSERENADE data collection eligibility criteria. PSERENADE received data from most (n = 63, 82.9%), yielding 240,639 post-PCV10/13 introduction IPD cases. Pediatric and adult surveillance was represented from all geographic regions but was limited from lower income and high-burden countries. In PSERENADE, 18 sites evaluated PCV10, 42 PCV13, and 17 both; 17 sites used a 3 + 0 schedule, 38 used 2 + 1, 13 used 3 + 1, and 9 used mixed schedules. With such a sizeable and generally representative dataset, PSERENADE will be able to conduct robust analyses to estimate PCV impact and inform policy at national and global levels regarding adult immunization, schedule, and product choice, including for higher valency PCVs on the horizon

Designing a learning dashboard to facilitate project development and teamwork in a CBL physics course

There have been, and still are, considerable efforts to stimulate interdisciplinary research to tackle interesting research questions and address some of the complex societal challenges we are facing in the 21st century. Therefore, the current STEM education needs to provide opportunities for students to develop an interdisciplinary mindset and to actively engage them in solving societal issues early on during their degree. With these goals in mind, we designed a set of three interdisciplinary courses focused on the physics of social systems, or Sociophysics, using Challenge-Based Learning (CBL) as an instructional approach. Our aim was to offer students the freedom to define their projects while supporting them with a robust framework capable of helping them rapidly define their challenge (via CBL) and efficiently work on it (via Scrum). Since CBL is a new educational framework for most students and it relies on the students-driven initiative, we designed a learning dashboard specifically aimed at providing efficient feedback and supporting the development of students’ research and teamwork skills. We found our dashboard to be highly effective in providing both qualitative and quantitative support for students' progress in their self-defined projects, allowing scaling-up of CBL-based educational settings