Design and numerical simulation for the development of an expandable paediatric heart valve

Objectives: Early implant failure in paediatrics with congenital heart valve lesions can be caused by patient-prosthesis mismatch which leads to obstructive blood flow, inflammatory tissue growth and early calcification. There is a clinical need for an expandable prosthetic heart valve that is mimetic to somatic growth to reduce the risk of implant failure and ultimately reduce the need for revision surgeries in paediatrics. Methods: The aortic valve has well established parameters ratios including leaflet and coaptation height, commissure length and free edge angle, which will be used as the basis for designing an expandable valve. Using software package Ansys Mechanical APDL, a polymeric paediatric aortic valve was modelled in the closed position having a taut free edge that angles variably in relation to diameter, whilst maintaining valve parameter ratios. Results: Finite element analysis and computational fluid dynamics were carried using ANSYS 19R2 across a full systemic cardiac cycle to determine valve competence and identify haemodynamic stresses. Blood was modelled during a systolic cardiac cycle as pulsatile and the K-epsilon turbulent and Carraeu models applied for non-Newtonian blood flow. The leaflets have a thickness of 200 µm and were assigned silicone anisotropic material properties. Discussions: Varying the leaflet free edge angle with diameter enables the valve to remain taut whilst closed and prevent leaflet buckling when compressed into a smaller diameter. Early results from the computational fluid dynamic studies have shown reasonably low transvalvular pressure gradients at the smallest diameter (12 mm) and low localised regions of stress. Conclusions: Parametric design modelling can be successfully used to design a novel heart valve with leaflet positions that vary with diameter whilst respecting established valve parameter ratios. Work is ongoing to optimise the design of these leaflets for the growing paediatric environment

A feasibility study on 3D modelling of cardiac implants in children to improve outcomes in surgery

Objectives: It is both cost effective and practical to computationally model and simulate cardiac implants in a non-invasive environment to identify failure modes and optimise design. This will ultimately improve surgical outcomes faced by children from early implant failure. Methods: The geometries of 3 cardiac implants with increasingly complex features were captured using Agisoft Metashape, a photogrammetric processing software and converted to a 3D model. Anatomical geometries were segmented from a heart DICOM file using Mimics 22.0 and models generated to house the implants. Results: Preliminary surface capturing and modelling was carried out with a 33 mm mitral annuloplasty Dacron ring. Point clouds were successfully generated with high precision and tessellated to generate a 3D model. This was housed in an anatomical model of the mitral annulus and left ventricular outflow tract and computational fluid dynamics carried out using ANSYS 19R2. Blood was modelled during a systolic cardiac cycle as pulsatile and K-epsilon turbulent and Carreau models applied for non-Newtonian blood flow. Discussions: Through high resolution image capturing of the annuloplasty ring, surface features such as ribbing were possible to model. Work is ongoing to assess the feasibility of geometry capturing and computational analysis with a tilting disc and transcatheter aortic valve. Success in the use of these methods in this study will ensure transferability when modelling explanted cardiac implants to determine failure modes. Conclusions: The application of photogammetry to medical devices provides a cost effective and non-invasive method of analysing critical failure modes of implants that can be missed in patient scans. This will lead to device optimisation and will improve outcomes in paediatric cardiac surgery. Acknowledgements: This research was awarded funding through the Glasgow Children’s Hospital Charity Research Fund

Report for passive data acquired in the 1998-1999 Los Angeles Region Seismic Experiment II: a transect from Santa Monica Bay to the Westernmost Mojave Desert

Between October, 1998 and April, 1999, 83 seismic stations were installed in the greater western Los Angeles, California area to record teleseismic, regional, and local earthquakes. The near-linear 93-km long array extended between Santa Monica Bay and the western Mojave Desert, through the epicentral region of the Northridge earthquake. The goals of the experiment were to determine crustal thickness below the western Transverse Ranges, San Fernando Valley basin, and western Mojave Desert, measure anistropy along the line with special emphasis on the San Andreas fault region, evaluate the potential for future strong ground shaking at sites in the basins, and determine the kinematic relationship between crustal and uppermost mantle deformation by three-dimensional tomographic inversion using regional network data combined with the array data. The stations consisted of three-component, broadband and short-period seismometers, and timing was controlled by Global Positioning System (GPS) receivers. The array recorded 165 Gb of raw waveform data in continuous (25 sps) and triggered (50 sps) streams. Approximately 144 teleseismic earthquakes with magnitudes ≥ 5.5, and 2025 local earthquakes with magnitude ≥ 2.0 were recorded. Preliminary results from three-dimensional teleseismic traveltime inversion tomography indicate that uppermost mantle seismic anomalies strongly correlate with thickened crust in the Transverse Ranges suggesting that the width of the compressional region and convergence rate control the location of deformation more than the San Andreas shear zone does

Evolution by leaps : gene duplication in bacteria

© 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biology Direct 4 (2009): 46, doi:10.1186/1745-6150-4-46.Sequence related families of genes and proteins are common in bacterial genomes. In Escherichia coli they constitute over half of the genome. The presence of families and superfamilies of proteins suggest a history of gene duplication and divergence during evolution. Genome encoded protein families, their size and functional composition, reflect metabolic potentials of the organisms they are found in. Comparing protein families of different organisms give insight into functional differences and similarities. Equivalent enzyme families with metabolic functions were selected from the genomes of four experimentally characterized bacteria belonging to separate genera. Both similarities and differences were detected in the protein family memberships, with more similarities being detected among the more closely related organisms. Protein family memberships reflected known metabolic characteristics of the organisms. Differences in divergence of functionally characterized enzyme family members accounted for characteristics of taxa known to differ in those biochemical properties and capabilities. While some members of the gene families will have been acquired by lateral exchange and other former family members will have been lost over time, duplication and divergence of genes and functions appear to have been a significant contributor to the functional diversity of today’s microbes. Protein families seem likely to have arisen during evolution by gene duplication and divergence where the gene copies that have been retained are the variants that have led to distinct bacterial physiologies and taxa. Thus divergence of the duplicate enzymes has been a major process in the generation of different kinds of bacteria.This research was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-08ER64511

Implementing public involvement standards in cerebral palsy register research

BACKGROUND: In 2018, the National Institute for Health Research launched Draft Standards for Public Involvement in Research. The Northern Ireland Cerebral Palsy Register (NICPR) was competitively selected as a “test-bed” project to pilot the Draft Standards over a one-year period. AIM: This perspective paper aims to describe the NICPR's experience of piloting the Draft Standards for Public Involvement in Research, highlighting successes and challenges. METHOD: Three of the six Draft Standards were piloted from April 2018 to April 2019: Standard 2 “working together”, Standard 4 “communications” and Standard 5, “impact”. RESULTS: Implementation of Standard 2 resulted in formation of a dedicated Public Involvement Group. Standard 4 was implemented by revision of the NICPR's Privacy Notice and development of the NICPR website. Standard 5 was not implemented during the test-bed pilot period. DISCUSSION: Benefits of use of the Draft Standards in cerebral palsy register research included development of relationships, improving quality, accessibility and relevance of NICPR materials, increasing skills and confidence, networking opportunities, advocating for others and feeling empowered to shape cerebral palsy research. Challenges included administrative issues, absence of dedicated and sustained funding, limitations in the availability and applicability of public involvement training and the time required for meaningful public involvement. CONCLUSIONS: Standards for Public Involvement provide a useful framework for structuring and embedding meaningful public involvement. Sustained, authentic public involvement in cerebral palsy register research ensures that people affected by the condition are empowered to engage, inform, develop and lead research that meets their needs

Pre-treatment clinical features in central retinal vein occlusion that predict visual outcome following intravitreal ranibizumab

Background: Predicting how patients with central retinal vein occlusion (CRVO) will respond to intravitreal anti-VEGF is challenging. The purpose of this study was to identify pre-treatment clinical features in CRVO that predict visual acuity (VA) following intravitreal ranibizumab. Methods: Medical records, fundus images and optical coherence tomography (OCT) scans of treatment naïve patients with CRVO receiving PRN intravitreal ranibizumab were retrospectively reviewed. Early Treatment Diabetic Retinopathy Study (ETDRS) VA and central retinal thickness (CRT) were recorded at baseline, 3 and 12 months after starting therapy. Regression analysis was used to determine independent predictors of VA at 3 and 12 months follow-up. Possible predictors included baseline VA, age, presence of cotton wool spots (CWS), haemorrhages (few scattered or multiple deep), foveal detachment, CRT, time from presentation to treatment, number of injections given, presence of RAPD, and cause of CRVO. Results: Data from 52 eyes of 50 patients receiving intravitreal ranibizumab treatment for CRVO were analyzed. The mean pre-treatment VA was 43.3 (SD 22.5) letters, which improved to 52.0 (SD 24.3) letters at 3 months, then dropped to 42.0 (SD 30.26) at 12 months. Baseline CRT reduced from 616.7 μm (SD 272.4) to 346.0 μm (SD 205.2) at 3 months and 304.0 μm (SD 168.3) at 12 months. The following features were predictive of poorer VA after starting intravitreal ranibizumab: Poorer pretreatment VA (3-months, P = 0.010; 12-months, P = 0.006), increasing age (3-months, P = < 0.001; 12-months, P = 0.006), and presence of CWS (3-months, P < 0.001; 12-months, P = 0.045). Conclusion: Pre-treatment VA, older age, and presence of CWS are easily identifiable clinical features in the hospital setting which help predict visual outcome in patients with CRVO receiving intravitreal ranibizumab

The 1997 Los Angeles Basin Passive Seismic Experiment – a dense, urban seismic array to investigate basin lithospheric structures

In 1997, 18 seismic stations were installed in the Los Angeles basin to record teleseismic, regional, and local earthquakes. The goals of the experiment were to quantify amplification of ground motion due to variations in sedimentary environments and subsurface structures, and to examine the tectonic extensional and compressional history of the Los Angeles basin and San Gabriel Mountains by tomograhic imaging. The linear array spanned the entire basin between Seal Beach to the south and Azusa to the north. The stations consisted of three-component, short-period seismometers and timing was controlled by GPS receivers. Most locations were homeowner backyards with continuous A/C power sources and battery backup. The stations operated between March and November, 1997. The long experiment time was needed to record as many large teleseisms as possible at the seismically and culturally noisy Los Angeles basin sites. Data were recorded continuously at 25 sps and triggered at 50 sps. The total array length was 50 km with an average station spacing of 3-4 km. This was a much denser seismic array than any other in the region, and the close spacing of seismometers is providing high-resolution information about the geometry of structures several kilometers below the surface. The high density of stations is making it possible to observe amplitude variations on length scales of a few kilometers and to obtain travel times in seismically and culturally noisy regions by cross-correlation with quiet stations using the highly coherent waveforms. This array location was chosen because it spans the entire Los Angeles basin, and it covers an area known for its high seismic hazard, unique geology and active plate motion. It was also the site of one leg of the 1994 Los Angeles Region Seismic Experiment in which onshore and offshore explosions were recorded along essentially the same line for very detailed structure in the upper 20 km of the Earth's crust

PtdIns(4,5)P2 Functions at the Cleavage Furrow during Cytokinesis

SummaryPhosphoinositides play important roles in regulating the cytoskeleton and vesicle trafficking, potentially important processes at the cleavage furrow. However, it remains unclear which, if any, of the phosphoinositides play a role during cytokinesis. A systematic analysis to determine if any of the phosphoinositides might be present or of functional importance at the cleavage furrow has not been published. Several studies hint at a possible role for one or more phosphoinositides at the cleavage furrow. The best of these are genetic data identifying mutations in phosphoinositide-modifying enzymes (a PtdIns(4)P-5-kinase in S. pombe [1, 2] and a PI-4-kinase in D. melanogaster [3]) that interfere with cytokinesis. The genetic nature of these experiments leaves questions as to how direct may be their contribution to cytokinesis. Here we show that a single phosphoinositide, PtdIns(4,5)P2, specifically accumulates at the furrow. Interference with PtdIns(4,5)P2 interferes with adhesion of the plasma membrane to the contractile ring at the furrow. Finally, four distinct interventions to specifically interfere with PtdIns(4,5)P2 each impair cytokinesis. We conclude that PtdIns(4,5)P2 is present at the cleavage furrow and is required for normal cytokinesis at least in part because of a role in adhesion between the contractile ring and the plasma membrane

The Vehicle, Fall 1988

Table of Contents Cover LetterBob Zordanipage 3 Letter to Harrington StreetBob Zordanipage 4 The Only TruthBob Zordanipage 5 They\u27d Gone to a MovieMatt Mansfieldpage 6 The LocketMonica Grothpage 6 The Sleep of BabesMonica Grothpage 7 Techni-Color Characters in a Black and White TownMonica Grothpage 8 The HorseRodger Patiencepage 9 ValaciaRobyn Kerrpage 10 Gatsby\u27s LightJim Reedpage 11 Millions of MeJim Reedpage 12 View from the StreetsSteven M. Beamerpage 13 When Headlights on the HighwayMichael Salempage 23 Concrete AffairsMichael Salempage 24 The Middle of the StreetMichael Salempage 25 Scent of a StormMichael Salempage 26 The FishermanAngie Geraldpage 27 OrgansPatrick Peterspage 33 CarpentryPatrick Peterspage 34 FishingPatrick Peterspage 35 Autumn Poem for a Friend In a Printing PlantPatrick Peterspage 36https://thekeep.eiu.edu/vehicle/1051/thumbnail.jp

The Vehicle, Fall 1988

Table of Contents Cover LetterBob Zordanipage 3 Letter to Harrington StreetBob Zordanipage 4 The Only TruthBob Zordanipage 5 They\u27d Gone to a MovieMatt Mansfieldpage 6 The LocketMonica Grothpage 6 The Sleep of BabesMonica Grothpage 7 Techni-Color Characters in a Black and White TownMonica Grothpage 8 The HorseRodger Patiencepage 9 ValaciaRobyn Kerrpage 10 Gatsby\u27s LightJim Reedpage 11 Millions of MeJim Reedpage 12 View from the StreetsSteven M. Beamerpage 13 When Headlights on the HighwayMichael Salempage 23 Concrete AffairsMichael Salempage 24 The Middle of the StreetMichael Salempage 25 Scent of a StormMichael Salempage 26 The FishermanAngie Geraldpage 27 OrgansPatrick Peterspage 33 CarpentryPatrick Peterspage 34 FishingPatrick Peterspage 35 Autumn Poem for a Friend In a Printing PlantPatrick Peterspage 36https://thekeep.eiu.edu/vehicle/1051/thumbnail.jp