The aim of this study was to further investigate the role of pro-inflammatory cytokines in the pathogenesis of fetal cererbral white matter injury associated with chorioamnionitis by charaterizing the time course of the cytokine response in the pregnant guinea pig following a maternal inflammatory insult. Chorioamnionitis increases the risk for fetal brain injury. In the guinea pig, a threshold maternal inflammatory response must be reached for significant fetal brain injury to occur. However, a previous study demonstrated that, by seven days after an acute maternal inflammatory insult, cytokine levels in both maternal and fetal compartments are not different from controls. The purpose of this study, therefore, was to test the hypothesis that a significant cytokine response occurs within the first seven days following an acute maternal inflammatory response. Pregnant guinea pigs (n=34) were injected intraperitoneally with 100µg/kg lipopolysaccharide (LPS) at 70% gestation and euthanized at 24 hours, 48 hours or 5 days following endotoxin exposure. Control animals were euthanized at 70% gestation without exposure. Concentrations of interleukin-6, interleukin 1-β and tumour necrosis factor-α (IL-6, IL-1β, TNF-α) were quantified in the maternal serum and amniotic fluid by enzyme-linked immunosorbent assay. IL-6 and IL-1β concentrations were elevated in the maternal serum at 24 hours and returned to control levels by five days. In the amniotic fluid, IL-6 peaked at 48 hours and IL-1β at 24 hours. TNF-α levels were not significantly increased. A single maternal LPS injection produces transient increases in cytokine concentrations in the maternal serum and amniotic fluid. This further implicates the cytokines as potential mediators of fetal white matter damage. Although this response might not be sufficient to produce the brain injury itself, it may initiate harmful pro-inflammatory cytokine cascades, which could even continue to harm the fetus following delivery. A human diagnostic protocol was developed to assess the use of serial serum biomarkers, including IL-6 and TNF-α, in the prediction of histological chorioamnionitis. Preliminary analysis of the pilot study suggests that certain biomarkers might be worthy of further investigation in a larger-scale study. / Thesis (Master, Anatomy & Cell Biology) -- Queen's University, 2007-11-28 08:23:04.327

Considering that the nature of the input is one of the most important variables in determining how the brain will process information, findings from tachistoscopic studies aimed at assessing hemispheric specializations are examined in terms of the characteristics of the incoming information either available or required for processing. The basic features of the tachistoscopic technique are analyzed, and a framework for further investigation is suggested along with a reinterpretation of existing evidence. In a subsequent series of four experiments, several assumptions and interpretations made earlier are empirically tested. In a second series of three experiments, hemispheric asymmetries are examined with respect to the properties of the visual system and its capacity to extract information in terms of the spatial-frequency spectral components of a stimulus. Methodological and theoretical implications of the results are discussed, and an account of cerebral specialization suggesting a hemispheric sensitivity to different aspects of the same information is proposed.

The Circle of Willis (CoW) is a ring-like arterial structure forming the major anastomotic connection between arterial supply systems in the brain, and is responsible for the distribution of oxygenated blood throughout the cerebral mass. Among the general population, only approximately 50% have a complete CoW, where absent or hypoplastic vessels are common among a multitude of possible anatomical variations, reducing the degree to which blood may be rerouted. While an individual with one of these variations may under normal circumstances suffer no ill effects, there are certain pathological conditions which can present a risk to the person's health and increase the possibility of suffering an ischaemic stroke when compounded with an anatomical variation. This body of work presents techniques for generating 3D models of the cerebral vasculature using magnetic resonance imaging (MRI) and performing computational fluid dynamics (CFD) simulations in order to simulate the flow patterns throughout a circle of Willis. Incorporated with the simulations is a mathematical model of the cerebral autoregulation mechanism, simulating the ability of the smaller arteries and arterioles in the brain to either constrict or dilate in response to alterations in cerebral blood flow, thereby altering the cerebrovascular resistance of each major brain territory and regulating the amount of blood flow within a physiological range of cerebral perfusion pressure. The CFD simulations have the ability to predict the amount of collateral flow rerouted via the communicating arteries in response to a stenosis or occlusion, and the major objective of this study has been the investigation of how anatomical variations of the circle of Willis affect the capacity to provide this collateral flow. Initial work began with the development of three idealized models of common anatomical variations, created using computer aided design software (CAD) and based on the results of MRI scans. The research then shifted to developing a technique whereby patient specific models of the circle of Willis could be directly segmented from the MRI data. As a result of this shift, an interactive GUI-based tool was developed for the processing of the MRI datasets, allowing for rapid data enhancement and creation of a surface topology representing the arterial wall of the circle of Willis, suitable for a CFD simulation. The results of both sets of simulations illustrate that there exist a number of variables associated with a patients circle of Willis geometry, such as cerebral blood flow and combinations and degrees of stenosis, implying that the initial goal of drawing generalized conclusions was perhaps flawed. Instead, a crucial outcome of this body of work is that the future research should be directed toward extending the physiological complexity of both the geometry and the autoregulation model, with the intention of a patient specific application rather than producing large datasets with which to make broad generalizations.

Altered cerebral hemodynamics contributes to mechanisms of unexplained syncope. Wecompared dynamic interaction between respiration and cerebral autoregulation in two groups ofsubjects from 28 healthy adults. Based on development of tilt-induced presyncope, subjects wereclassified as Non-Presyncopals (n=23) and Presyncopals (n=5). Airflow, CO2, Doppler cerebralblood flow velocity (CBF), ECG and blood pressure (BP) were recorded. To determine whetherinfluences of mean BP (MBP) and systolic BP (SBP) on CBF were altered in Presyncopals, thecoherencies and transfer functions between these variables and mean and peak CBF (CBFm andCBFp) were estimated. To determine influence of end-tidal CO2 (ETCO2) on CBF, relative CO2reactivity was calculated. The two primary findings were, during tilt in Presyncopals: (1) Inrespiratory frequency region, coherence between SBP and CBFp (p=0.02) and transfer functiongain between BP and CBFm was higher (MBP, p=0.01, and SBP, p=0.01) than in Non-Presyncopals. (2) In the last 3 minutes prior to presyncope, Presyncopals had a reduced relativeCO2 reactivity (p=0.005). Thus the relationship of CBF with systemic BP was more pronouncedor cerebral autoregulation was less effective preceding presyncope. This decreasedautoregulation, secondary to decreased ETCO2, may contribute in the cascade of events leadingto unexplained syncope.

An adjustable chair was developed for children with cerebral palsy in Uganda. The chairs these children use today are custom made which means that they cannot be used when a child outgrows a chair. Sometimes the chair is used by other children and does not give the support that the child needs. The project was executed in the capitol, Kampala, by the two design engineer students Faith Auma and Emma Lingehed in collaboration with Makerere University, Kampala school for the physically handicapped and Katalemwa Cheshire home. The goal of the project was to help pupils with cerebral palsy from a young age develop adequate sitting behaviour and become more physically independent. The chair should be able to be manufactured and assembled in Uganda and the material should be able to be found in the country. The project started by clarifying the problem, information was collected through literature studies, study visits and interviews. The gathered information was used to create a product specification focusing on safety, environment, manufacturing and ergonomics. All background information was used throughout the idea generation. A number of ideas were generated and evaluated until a final concept was found. The final concept, called Billy, was chosen through a concept scoring where it was evaluated against three other concepts. Billy was considered the easiest concept to manufacture in Uganda and had the simplest construction. Billy was developed further and became the final concept Entebbe. Entebbe is a chair that is adjustable and gives the support a child with cerebral palsy needs. A prototype was made at Katalemwa Cheshire home.  Entebbe can be manufactured in Uganda and since it is module-based it can easily be repaired and resized by simply changing the concerned parts. This also means that parts can be reused to build other chairs. Entebbe can be adjusted in five different ways and requires no tools to assemble. / En justerbar stol utvecklades för barn med cerebral pares i Uganda. Stolarna dessa barn använder idag är specialdesignade vilket innebär att de inte kan användas när barnet växer ur stolen. Ibland används då stolen av andra barn och ger därmed inte det stöd som barnet behöver. Projektet genomfördes i huvudstaden, Kampala, av de två designingenjörsstudenter Faith Auma och Emma Lingehed i samarbete med Makerere University, Kampala school for the physically handicapped och Katalemwa Cheshire home. Målet med projektet var att hjälpa elever med cerebral pares redan från unga år att utveckla ett korrekt sittbeteende och bli mer fysiskt oberoende. Stolen ska kunna tillverkas och monteras i Uganda och materialet ska finnas i landet. Projektet började med att studera och klargöra problemet, information samlades in genom litteraturstudier, studiebesök och intervjuer. Den insamlade informationen användes för att skapa en kravspecifikation med fokus på säkerhet, miljö, tillverkning och ergonomi. Bakgrundsinformationen användes under idégenereringen. Ett antal idéer genererades och utvärderades tills ett slutgiltigt koncept hittades. Det slutgiltiga konceptet, Billy, valdes genom en concept scoring där det utvärderades mot tre andra koncept. Billy ansågs vara det koncept som var enklast att tillverka i Uganda och hade den enklaste konstruktionen. Billy vidareutvecklades och blev det slutliga konceptet Entebbe. Entebbe är en stol som är justerbar och ger det stöd ett barn med cerebral pares behöver. En prototyp tillverkades vid Katalemwa Cheshire home. Entebbe kan tillverkas i Uganda och eftersom den är modulbaserad är den lätt att reparera och ändra storlek på genom att enkelt byta ut de berörda delarna. Detta innebär att delarna även kan återanvändas för att bygga andra stolar. Entebbe kan justeras på fem olika sätt och inga verktyg krävs för att montera ihop stolen.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 119-147) Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 119-147) Also available online.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--University of Oregon, 2004. / Includes bibliographical references (leaves 56-58). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.