International Guillain-Barré Syndrome Outcome Study (IGOS): protocol of a prospective observational cohort study on clinical and biological predictors of disease course and outcome in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy with a highly variable clinical presentation, course, and outcome. The factors that determine the clinical variation of GBS are poorly understood which complicates the care and treatment of individual patients. The protocol of the ongoing International GBS Outcome Study (IGOS), a prospective, observational, multi-centre cohort study that aims to identify the clinical and biological determinants and predictors of disease onset, subtype, course and outcome of GBS is presented here. Patients fulfilling the diagnostic criteria for GBS, regardless of age, disease severity, variant forms, or treatment, can participate if included within two weeks after onset of weakness. Information about demography, preceding infections, clinical features, diagnostic findings, treatment, course and outcome is collected. In addition, cerebrospinal fluid and serial blood samples for serum and DNA is collected at standard time points. The original aim was to include at least 1000 patients with a follow-up of 1-3 years. Data are collected via a web-based data entry system and stored anonymously. IGOS started in May 2012 and by January 2017 included more than 1400 participants from 143 active centres in 19 countries across 5 continents. The IGOS data/biobank is available for research projects conducted by expertise groups focusing on specific topics including epidemiology, diagnostic criteria, clinimetrics, electrophysiology, antecedent events, antibodies, genetics, prognostic modelling, treatment effects and long-term outcome of GBS. The IGOS will help to standardize the international collection of data and biosamples for future research of GBS. ClinicalTrials.gov Identifier: NCT01582763

Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates – An In Vitro Study

Introduction International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP. Methods Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH2O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH2O were studied. A second test was conducted with settings of PIP 40cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+). Results Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH2O when set to 5cmH2O and 6.1(4.9–7.1)cmH2O when set to 10cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH2O and 4.3(3.2–4.8)cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH2O and 5.0(3.5–6.2)cmH2O for both PEEP settings. Conclusion Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates

Responses of Ileal and Fecal Microbiota to Withdrawal of Pancreatic Enzyme Replacement Therapy in a Porcine Model of Exocrine Pancreatic Insufficiency

Little is known regarding the interplay between microbiota and pancreas functions in humans as investigations are usually limited to distal sites, namely the analyses of fecal samples. The aim of this study was to investigate both ileal and fecal microbiota in response to pancreatic enzyme replacement therapy (PERT) in a porcine model of exocrine pancreatic insufficiency (EPI). PERT was stopped for ten days in ileo-cecal fistulated minipigs with experimentally induced EPI (n = 8) and ileal digesta as well as fecal samples were obtained before withdrawal, during withdrawal and after the reintroduction of PERT. Profound community changes occurred three days after enzyme omission and were maintained throughout the withdrawal phase. A reduction in α-diversity together with relative abundance changes in several taxa, in particular increases in Bifidobacteria (at both sites) and Lactobacilli (only feces) were observed. Overall, dysbiosis events from the ileum had accumulating effects in distal parts of the gastrointestinal tract with additional alterations occurring only in the colon. Changes were reversible after continuing PERT, and one week later, bacterial communities resembled those at baseline. Our study demonstrates the rapid and profound impacts of enzyme withdrawal in bacterial communities, contributing to our understanding of the interplay between pancreas function and microbiot

Risk Factor Analysis of Bird Beak Occurrence after Thoracic Endovascular Aortic Repair

ObjectivesThe aim was to analyze the role played by anatomy and stent graft in the incidence of incomplete apposition to aortic arch.MethodsBetween 2007 and 2014 data including available and suitable computed tomographic angiography (CTA) imaging of patients who had undergone thoracic endovascular aortic repair were reviewed. The study included 80 patients (65 men, 54 ± 21 years) treated for traumatic aortic rupture (n = 27), thoracic aortic aneurysm (n = 15), type B aortic dissection (n = 24), penetrating aortic ulcer (n = 5), intramural hematoma (n = 2), aorto-oesophageal fistula (n = 2), and aortic mural thrombus (n = 5). Pre- and post-operative CTA images were analyzed to characterize bird beak in terms of length and angle, and to calculate aortic angulation within a 30 mm range at the proximal deployment zone.ResultsBird beak configuration was detected in 46 patients (57%): mean stent protrusion length was 16 mm (range: 8–29 mm) and mean bird beak angle was 20° (range: 7–40°). The bird beak effect was significantly more frequent after traumatic aortic rupture treatment (p = .05) and in landing zone 2 (p = .01). No influence of either stent graft type or generation, or degree of oversizing was observed (p = .29, p = .28, p = .81 respectively). However, the mean aortic angle of patients with bird beak was higher in the Pro-form group than that in the Zenith TX2 group (62° vs. 48°, p = .13). Multivariate analysis identified the aortic angle of the deployment zone as the unique independent risk factor of malapposition (HR = 1.05, 95% CI 1–1.10, p = .005). The cutoff value of 51° was found to be predictive of bird beak occurrence with a sensitivity of 58% and a specificity of 85%.ConclusionsAssessment of proximal landing zone morphology to avoid deployment zones generating an aortic angle of over 50° can be recommended to improve aortic curvature apposition with the current available devices

Manifestation of the bulk phase transition in the edge energy spectrum in a two dimensional bilayer electron system

We use a quasi-Corbino sample geometry with independent contacts to different edge states in the quantum Hall effect regime to investigate the edge energy spectrum of a bilayer electron system at total filling factor $\nu=2$. By analyzing non-linear $I-V$ curves in normal and tilted magnetic fields we conclude that the edge energy spectrum is in a close connection with the bulk one. At the bulk phase transition spin-singlet - canted antiferromagnetic phase $I-V$ curve becomes to be linear, indicating the disappearance or strong narrowing of the $\nu=1$ incompressible strip at the edge of the sample.Comment: 5 pages, 5 figure

Avoiding the sign-problem in lattice field theory

In lattice field theory, the interactions of elementary particles can be computed via high-dimensional integrals. Markov-chain Monte Carlo (MCMC) methods based on importance sampling are normally efficient to solve most of these integrals. But these methods give large errors for oscillatory integrands, exhibiting the so-called sign-problem. We developed new quadrature rules using the symmetry of the considered systems to avoid the sign-problem in physical one-dimensional models for the resulting high-dimensional integrals. This article gives a short introduction to integrals used in lattice QCD where the interactions of gluon and quark elementary particles are investigated, explains the alternative integration methods we developed and shows results of applying them to models with one physical dimension. The new quadrature rules avoid the sign-problem and can therefore be used to perform simulations at until now not reachable regions in parameter space, where the MCMC errors are too big for affordable sample sizes. However, it is still a challenge to develop these techniques further for applications with physical higher-dimensional systems

A Robust Adaptive Solution Strategy for High-Order Implicit CFD Solvers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90694/1/AIAA-2011-3696-676.pd