953 resultados para Circulation hyperdynamique


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The continuous production of blood cells, a process termed hematopoiesis, is sustained throughout the lifetime of an individual by a relatively small population of cells known as hematopoietic stem cells (HSCs). HSCs are unique cells characterized by their ability to self-renew and give rise to all types of mature blood cells. Given their high proliferative potential, HSCs need to be tightly regulated on the cellular and molecular levels or could otherwise turn malignant. On the other hand, the tight regulatory control of HSC function also translates into difficulties in culturing and expanding HSCs in vitro. In fact, it is currently not possible to maintain or expand HSCs ex vivo without rapid loss of self-renewal. Increased knowledge of the unique features of important HSC niches and of key transcriptional regulatory programs that govern HSC behavior is thus needed. Additional insight in the mechanisms of stem cell formation could enable us to recapitulate the processes of HSC formation and self-renewal/expansion ex vivo with the ultimate goal of creating an unlimited supply of HSCs from e.g. human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPS) to be used in therapy. We thus asked: How are hematopoietic stem cells formed and in what cellular niches does this happen (Papers I, II)? What are the molecular mechanisms that govern hematopoietic stem cell development and differentiation (Papers III, IV)? Importantly, we could show that placenta is a major fetal hematopoietic niche that harbors a large number of HSCs during midgestation (Paper I)(Gekas et al., 2005). In order to address whether the HSCs found in placenta were formed there we utilized the Runx1-LacZ knock-in and Ncx1 knockout mouse models (Paper II). Importantly, we could show that HSCs emerge de novo in the placental vasculature in the absence of circulation (Rhodes et al., 2008). Furthermore, we could identify defined microenvironmental niches within the placenta with distinct roles in hematopoiesis: the large vessels of the chorioallantoic mesenchyme serve as sites of HSC generation whereas the placental labyrinth is a niche supporting HSC expansion (Rhodes et al., 2008). Overall, these studies illustrate the importance of distinct milieus in the emergence and subsequent maturation of HSCs. To ensure proper function of HSCs several regulatory mechanisms are in place. The microenvironment in which HSCs reside provides soluble factors and cell-cell interactions. In the cell-nucleus, these cell-extrinsic cues are interpreted in the context of cell-intrinsic developmental programs which are governed by transcription factors. An essential transcription factor for initiation of hematopoiesis is Scl/Tal1 (stem cell leukemia gene/T-cell acute leukemia gene 1). Loss of Scl results in early embryonic death and total lack of all blood cells, yet deactivation of Scl in the adult does not affect HSC function (Mikkola et al., 2003b. In order to define the temporal window of Scl requirement during fetal hematopoietic development, we deactivated Scl in all hematopoietic lineages shortly after hematopoietic specification in the embryo . Interestingly, maturation, expansion and function of fetal HSCs was unaffected, and, as in the adult, red blood cell and platelet differentiation was impaired (Paper III)(Schlaeger et al., 2005). These findings highlight that, once specified, the hematopoietic fate is stable even in the absence of Scl and is maintained through mechanisms that are distinct from those required for the initial fate choice. As the critical downstream targets of Scl remain unknown, we sought to identify and characterize target genes of Scl (Paper IV). We could identify transcription factor Mef2C (myocyte enhancer factor 2 C) as a novel direct target gene of Scl specifically in the megakaryocyte lineage which largely explains the megakaryocyte defect observed in Scl deficient mice. In addition, we observed an Scl-independent requirement of Mef2C in the B-cell compartment, as loss of Mef2C leads to accelerated B-cell aging (Gekas et al. Submitted). Taken together, these studies identify key extracellular microenvironments and intracellular transcriptional regulators that dictate different stages of HSC development, from emergence to lineage choice to aging.

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Stroke is the second leading cause of death and the leading cause of disability worldwide. Of all strokes, up to 80% to 85% are ischemic, and of these, less than 10% occur in young individuals. Stroke in young adults—most often defined as stroke occurring under the age of 45 or 50—can be particularly devastating due to long expected life-span ahead and marked socio-economic consequences. Current basic knowledge on ischemic stroke in this age group originates mostly from rather small and imprecise patient series. Regarding emergency treatment, systematic data on use of intravenous thrombolysis are absent. For this Thesis project, we collected detailed clinical and radiological data on all consecutive patients aged 15 to 49 with first-ever ischemic stroke between 1994 and 2007 treated at the Helsinki University Central Hospital. The aims of the study were to define demographic characteristics, risk factors, imaging features, etiology, and long-term mortality and its predictors in this patient population. We additionally sought to investigate, whether intravenous thrombolysis is safe and beneficial for the treatment of acute ischemic stroke in the young. Of our 1008 patients, most were males (ratio 1.7:1), who clearly outnumbered females after the age of 44, but females were preponderant among those aged <30. Occurrence increased exponentially. The most frequent risk factors were dyslipidemia (60%), smoking (44%), and hypertension (39%). Risk factors accumulated in males and along aging. Cardioembolism (20%) and cervicocerebral artery dissection (15%) were the most frequent etiologic subgroups, followed by small-vessel disease (14%), and large-artery atherosclerosis (8%). A total of 33% had undetermined etiology. Left hemisphere strokes were more common in general. Posterior circulation infarcts were more common among those aged <45. Multiple brain infarcts were present in 23% of our patients, 13% had silent infarcts, and 5% had leukoaraiosis. Of those with silent brain infarcts, majority (54%) had only a single lesion, and most of the silent strokes were located in basal ganglia (39%) and subcortical regions (21%). In a logistic regression analysis, type 1 diabetes mellitus in particular predicted the presence of both silent brain infarcts (odds ratio 5.78, 95% confidence interval 2.37-14.10) and leukoaraiosis (9.75; 3.39-28.04). We identified 48 young patients with hemispheric ischemic stroke treated with intravenous tissue plasminogen activator, alteplase. For comparisons, we searched 96 untreated control patients matched by age, gender, and admission stroke severity, as well as 96 alteplase-treated older controls aged 50 to 79 matched by gender and stroke severity. Alteplase-treated young patients recovered more often completely (27% versus 10%, P=0.010) or had only mild residual symptoms (40% versus 22%, P=0.025) compared to age-matched controls. None of the alteplase-treated young patients had symptomatic intracerebral hemorrhage or died within 3-month follow-up. Overall long-term mortality was low in our patient population. Cumulative mortality risks were 2.7% (95% confidence interval 1.5-3.9%) at 1 month, 4.7% (3.1-6.3%) at 1 year, and 10.7% (9.9-11.5%) at 5 years. Among the 30-day survivors who died during the 5-year follow-up, more than half died due to vascular causes. Malignancy, heart failure, heavy drinking, preceding infection, type 1 diabetes, increasing age, and large-artery atherosclerosis causing the index stroke independently predicted 5-year mortality when adjusted for age, gender, relevant risk factors, stroke severity, and etiologic subtype. In sum, young adults with ischemic stroke have distinct demographic patterns and they frequently harbor traditional vascular risk factors. Etiology in the young is extremely diverse, but in as many as one-third the exact cause remains unknown. Silent brain infarcts and leukoaraiosis are not uncommon brain imaging findings in these patients and should not be overlooked due to their potential prognostic relevance. Outcomes in young adults with hemispheric ischemic stroke can safely be improved with intravenous thrombolysis. Furthermore, despite their overall low risk of death after ischemic stroke, several easily recognizable factors—of which most are modifiable—predict higher mortality in the long term in young adults.

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Background and aims. Type 1 diabetes (T1D), an autoimmune disease in which the insulin producing beta cells are gradually destroyed, is preceded by a prodromal phase characterized by appearance of diabetes-associated autoantibodies in circulation. Both the timing of the appearance of autoantibodies and their quality have been used in the prediction of T1D among first-degree relatives of diabetic patients (FDRs). So far, no general strategies for identifying individuals at increased disease risk in the general population have been established, although the majority of new cases originate in this population. The current work aimed at assessing the predictive role of diabetes-associated immunologic and metabolic risk factors in the general population, and comparing these factors with data obtained from studies on FDRs. Subjects and methods. Study subjects in the current work were subcohorts of participants of the Childhood Diabetes in Finland Study (DiMe; n=755), the Cardiovascular Risk in Young Finns Study (LASERI; n=3475), and the Finnish Type 1 Diabetes Prediction and Prevention Study (DIPP) Study subjects (n=7410). These children were observed for signs of beta-cell autoimmunity and progression to T1D, and the results obtained were compared between the FDRs and the general population cohorts. --- Results and conclusions. By combining HLA and autoantibody screening, T1D risks similar to those reported for autoantibody-positive FDRs are observed in the pediatric general population. Progression rate to T1D is high in genetically susceptible children with persistent multipositivity. Measurement of IAA affinity failed in stratifying the risk assessment in young IAA-positive children with HLA-conferred disease susceptibility, among whom affinity of IAA did not increase during the prediabetic period. Young age at seroconversion, increased weight-for-height, decreased early insulin response, and increased IAA and IA-2A levels predict T1D in young children with genetic disease susceptibility and signs of advanced beta-cell autoimmunity. Since the incidence of T1D continues to increase, efforts aimed at preventing T1D are important, and reliable disease prediction is needed both for intervention trials and for effective and safe preventive therapies in the future. Our observations confirmed that combined HLA-based screening and regular autoantibody measurements reveal similar disease risks in pediatric general population as those seen in prediabetic FDRs, and that risk assessment can be stratified further by studying glucose metabolism of prediabetic subjects. As these screening efforts are feasible in practice, the knowledge now obtained can be exploited while designing intervention trials aimed at secondary prevention of T1D.

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Congenital nephrotic syndrome of the Finnish type (NPHS1, CNF) is an autosomal recessive disease, enriched in the Finnish population. NPHS1 is caused by a mutation in the NPHS1 gene. This gene encodes for nephrin, which is a major structural component of the slit diaphragm connecting podocyte foot processes in the glomerular capillary wall. In NPHS1, the genetic defect in nephrin leads to heavy proteinuria already in the newborn period. Finnish NPHS1 patients are nephrectomized at infancy, and after a short period of dialysis the patients receive a kidney transplant, which is the only curative therapy for the disease. In this thesis, we examined the cellular and molecular mechanisms leading to the progression of glomerulosclerosis and tubulointerstitial fibrosis in NPHS1 kidneys. Progressive mesangial expansion in NPHS1 kidneys is caused by mesangial cell hyperplasia and the accumulation of extracellular matrix proteins. Expansion of the extracellular matrix was caused by the normal mesangial cell component, collagen IV. However, no significant changes in mesangial cell phenotype or extracellular matrix component composition were observed. Endotheliosis was the main ultrastructural lesion observed in the endothelium of NPHS1 glomeruli. The abundant expression of vascular endothelial growth factor and its transcription factor hypoxia inducible factor-1 alpha were in accordance with the preserved structure of the endothelium in NPHS1 kidneys. Hypoperfusion of peritubular capillaries and tubulointerstitial hypoxia were evident in NPHS1 kidneys, indicating that these may play an important role in the rapid progression of fibrosis in the kidneys of NPHS1 patients. Upregulation of Angiotensin II was obvious, emphasizing its role in the pathophysiology of NPHS1. Excessive oxidative stress was evident in NPHS1 kidneys, manifested as an increase expression of p22phox, superoxide production, lipid oxide peroxidation and reduced antioxidant activity. In conclusion, our data indicate that mesangial cell proliferation and the accumulation of extracellular matrix accumulation are associated with the obliteration of glomerular capillaries, causing the reduction of circulation in peritubular capillaries. The injury and rarefaction of peritubular capillaries result in impairment of oxygen and nutrient delivery to the tubuli and interstitial cells, which correlates with the fibrosis, tubular atrophy and oxidative stress observed in NPHS1 kidneys.

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Government policies in Australia and in many other parts of the world, are calling for degree-qualified teachers to work in prior to formal school settings (center-based care, preschool). Yet, many preservice early childhood teachers assume they will end up teaching in primary schools. This paper examines the professional identities preservice early childhood teachers take up and speak into action while participating in classes focused on teaching in child care. Employing poststructural social theory, data drawn from focus groups with preservice early childhood teachers was examined through a Foucauldian-informed discourse analysis. Particular ways in which the preservice teachers talked about images of children and quality in early childhood are scrutinized for how discourses work to constitute the professional identities of preservice early childhood teachers. It was found that the participants drew on a range of competing discourses available to them, through their degree, and from elsewhere to describe the work of teaching young children and teaching in child care. These competing and colliding discourses, it is argued produce an identity of preservice teachers as ‘heroic victims.’ The paper raises questions about the discourses in circulation in preservice early childhood teacher education, and considers the implications this has for professional identities and career pathways—particularly work in child care.

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The sea level pressure (SLP) variability in 30-60 day intraseasonal timescales is investigated using 25 years of reanalysis data addressing two issues. The first concerns the non-zero zonal mean component of SLP near the equator and its meridional connections, and the second concerns the fast eastward propagation (EP) speed of SLP compared to that of zonal wind. It is shown that the entire globe resonates with high amplitude wave activity during some periods which may last for few to several months, followed by lull periods of varying duration. SLP variations in the tropical belt are highly coherent from 25A degrees S to 25A degrees N, uncorrelated with variations in mid latitudes and again significantly correlated but with opposite phase around 60A degrees S and 65A degrees N. Near the equator (8A degrees S-8A degrees N), the zonal mean contributes significantly to the total variance in SLP, and after its removal, SLP shows a dominant zonal wavenumber one structure having a periodicity of 40 days and EP speeds comparable to that of zonal winds in the Indian Ocean. SLP from many of the atmospheric and coupled general circulation models show similar behaviour in the meridional direction although their propagation characteristics in the tropical belt differ widely.

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[1] The equatorial Indian Ocean (EIO) exhibited anomalous conditions characteristic of an Indian Ocean dipole (IOD) during 2006. The eastern EIO had cold sea surface temperature anomalies (SSTA), lower sea level, shallow thermocline and higher chlorophyll than normal. The anomalies in the east, restricted to the south of the equator, were highest off Sumatra. The western pole of the IOD was marked by warm SSTA and deeper thermocline with maxima on either side of the equator. An ocean general circulation model of the Indian Ocean forced by QuikSCAT winds reproduces the IOD of 2006 remarkably well. The switch over to cooling in the east and warming in the west happened during May and July respectively. In the east, airsea heat flux initiated cold SSTA in the model which were sustained later by oceanic processes. In the west, surface heat fluxes and horizontal advection caused warm SSTA and contribution by the latter decreased after August. Citation: Vinayachandran, P. N., J. Kurian, and C. P. Neema (2007), Indian Ocean response to anomalous conditions in 2006, Geophys. Res. Lett., 34, L15602, doi:10.1029/2007GL030194.

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How blood was able to reach the heads of the long-necked sauropod dinosaurs has long been a matter of debate and several hypotheses have been presented. For example, it has been proposed that sauropods had exceptionally large hearts, multiple ‘normal’ sized hearts spaced at regular intervals up the neck or held their necks horizontal, or that the siphon effect was in operation. By means of an experimental model, we demonstrate that the siphon principle is able to explain how blood was able to adequately perfuse the sauropod brain. The return venous circulation may have been protected from complete collapse by a structure akin to the vertebral venous plexus. We derive an equation relating neck height and mean arterial pressure, which indicates that with a mean arterial pressure similar to that of the giraffe, the maximum safe vertical distance between heart and head would have been about 12 m. A hypothesis is presented that the maximum neck length in the fossil record is due to the siphon height limit. The equation indicates that to migrate over high ground, sauropods would have had to either significantly increase their mean arterial pressure or keep their necks below a certain height dependent on altitude.

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The equatorial Indian Ocean (EIO) exhibited anomalous conditions characteristic of an Indian Ocean dipole (IOD) during 2006. The eastern EIO had cold sea surface temperature anomalies (SSTA), lower sea level, shallow thermocline and higher chlorophyll than normal. The anomalies in the east, restricted to the south of the equator, were highest off Sumatra. The western pole of the IOD was marked by warm SSTA and deeper thermocline with maxima on either side of the equator. An ocean general circulation model of the Indian Ocean forced by QuikSCAT winds reproduces the IOD of 2006 remarkably well. The switch over to cooling in the east and warming in the west happened during May and July respectively. In the east, air-sea heat flux initiated cold SSTA in the model which were sustained later by oceanic processes. In the west, surface heat fluxes and horizontal advection caused warm SSTA and contribution by the latter decreased after August.

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Hydrographic observations were taken along two coastal sections and one open ocean section in the Bay of Bengal during the 1999 southwest monsoon, as a part of the Bay of Bengal Monsoon Experiment (BOBMEX). The coastal section in the northwestern Bay of Bengal, which was occupied twice, captured a freshwater plume in its two stages: first when the plume was restricted to the coastal region although separated from the coast, and then when the plume spread offshore. Below the freshwater layer there were indications of an undercurrent. The coastal section in the southern Bay of Bengal was marked by intense coastal upwelling in a 50 km wide band. In regions under the influence of the freshwater plume, the mixed layer was considerably thinner and occasionally led to the formation of a temperature inversion. The mixed layer and isothermal layer were of similar depth for most of the profiles within and outside the freshwater plume and temperature below the mixed layer decreased rapidly till the top of seasonal thermocline. There was no barrier layer even in regions well under the influence of the freshwater plume. The freshwater plume in the open Bay of Bengal does not advect to the south of 16 degrees N during the southwest monsoon. A model of the Indian Ocean, forced by heat, momentum and freshwater fluxes for the year 1999, reproduces the freshwater plume in the Bay of Bengal reasonably well. Model currents as well as the surface circulation calculated as the sum of geostrophic and Ekman drift show a southeastward North Bay Monsoon Current (NBMC) across the Bay, which forms the southern arm of a cyclonic gyre. The NBMC separates the very low salinity waters of the northern Bay from the higher salinities in the south and thus plays an important role in the regulation of near surface stratification. (c) 2007 Elsevier Ltd. All rights reserved.

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Hydrographic observations were taken along two coastal sections and one open ocean section in the Bay of Bengal during the 1999 southwest monsoon, as a part of the Bay of Bengal Monsoon Experiment (BOBMEX). The coastal section in the northwestern Bay of Bengal, which was occupied twice, captured a freshwater plume in its two stages: first when the plume was restricted to the coastal region although separated from the coast, and then when the plume spread offshore. Below the freshwater layer there were indications of an undercurrent. The coastal section in the southern Bay of Bengal was marked by intense coastal upwelling in a 50 km wide band. In regions under the influence of the freshwater plume, the mixed layer was considerably thinner and occasionally led to the formation of a temperature inversion. The mixed layer and isothermal layer were of similar depth for most of the profiles within and outside the freshwater plume and temperature below the mixed layer decreased rapidly till the top of seasonal thermocline. There was no barrier layer even in regions well under the influence of the freshwater plume. The freshwater plume in the open Bay of Bengal does not advect to the south of 16 degrees N during the southwest monsoon. A model of the Indian Ocean, forced by heat, momentum and freshwater fluxes for the year 1999, reproduces the freshwater plume in the Bay of Bengal reasonably well. Model currents as well as the surface circulation calculated as the sum of geostrophic and Ekman drift show a southeastward North Bay Monsoon Current (NBMC) across the Bay, which forms the southern arm of a cyclonic gyre. The NBMC separates the very low salinity waters of the northern Bay from the higher salinities in the south and thus plays an important role in the regulation of near surface stratification. (c) 2007 Elsevier Ltd. All rights reserved.

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In atherosclerosis, cholesterol accumulates in the vessel wall, mainly in the form of modified low-density lipoprotein (LDL). Macrophages of the vessel wall scavenge cholesterol, which leads to formation of lipid-laden foam cells. High plasma levels of high-density lipoprotein (HDL) protect against atherosclerosis, as HDL particles can remove peripheral cholesterol and transport it to the liver for excretion in a process called reverse cholesterol transport (RCT). Phospholipid transfer protein (PLTP) remodels HDL particles in the circulation, generating prebeta-HDL and large fused HDL particles. In addition, PLTP maintains plasma HDL levels by facilitating the transfer of post-lipolytic surface remnants of triglyceride-rich lipoproteins to HDL. Most of the cholesteryl ester transfer protein (CETP) in plasma is bound to HDL particles and CETP is also involved in the remodeling of HDL particles. CETP enhances the heteroexchange of cholesteryl esters in HDL particles for triglycerides in LDL and very low-density lipoprotein (VLDL). The aim of this thesis project was to study the importance of endogenous PLTP in the removal of cholesterol from macrophage foam cells by using macrophages derived from PLTP-deficient mice, determine the effect of macrophage-derived PLTP on the development of atherosclerosis by using bone marrow transplantation, and clarify the role of the two forms of PLTP, active and inactive, in the removal of cholesterol from the foam cells. In addition, the ability of CETP to protect HDL against the action of chymase was studied. Finally, cholesterol efflux potential of sera obtained from the study subjects was compared. The absence of PLTP in macrophages derived from PLTP-deficient mice decreased cholesterol efflux mediated by ATP-binding cassette transporter A1. The bone marrow transplantation studies showed that selective deficiency of PLTP in macrophages decreased the size of atherosclerotic lesions and caused major changes in serum lipoprotein levels. It was further demonstrated that the active form of PLTP can enhance cholesterol efflux from macrophage foam cells through generation of prebeta-HDL and large fused HDL particles enriched with apoE and phospholipids. Also CETP may enhance the RCT process, as association of CETP with reconstituted HDL particles prevented chymase-dependent proteolysis of these particles and preserved their cholesterol efflux potential. Finally, serum from high-HDL subjects promoted more efficient cholesterol efflux than did serum derived from low-HDL subjects which was most probably due to differences in the distribution of HDL subpopulations in low-HDL and high-HDL subjects. These studies described in this thesis contribute to the understanding of the PLTP/CETP-associated mechanisms underlying RCT.

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This paper offers a mediation on disaster, recovery, resilience, and restoration of balance, in both a material and a metaphorical sense, when ‘disaster’ befalls not the body politic of the nation but the body personal. In the past few decades, of course, artists, activists and scholars have deliberately tried to avoid describing personal, physical and phenomenological experiences of the disabled body in terms of difficulty and disaster. This has been part of a political move, from a medical model, in which disability, disease and illness are positioned as personal catastrophes, to a social model, in which disability is positioned as a social construct that comes from systems, institutions and infrastructure designed to exclude different bodies. It is a move that is responsible for a certain discomfort people with disabilities, and artists with disabilities, today feel towards performances that deploy disability as a metaphor for disaster, from Hijikata, to Theatre Hora. In the past five years, though, this particular discourse has begun rising again, particularly as people with disabilities fact their own anything but natural disasters as a result of the austerity measures now widespread across the US, UK, Europe and elsewhere. Measures that threaten people’s ability to live, and take part in social and institutional life, in any meaningful way. Measures that, as artist Katherine Araniello notes, also bring additional difficulty, danger, and potential for disaster as they ripple outwards across the tides of familial ties, threatening family, friends, and careers who become bound up in the struggle to do more with less. In this paper, I consider how people with disabilities use performance, particularly public space interventionalist performance, to reengage, renact and reenvisage the discourse of national, economic, environmental or other forms of disaster, the need for austerity, the need to avoid providing people with support for desires and interests as well as basic daily needs, particularly when fraud and corruption is so right, and other such ideas that have become an all too unpleasant reality for many people. Performances, for instance, like Liz Crow’s Bedding Out, where she invited people into her bed – for people with disabilities a symbolic space, which necessarily becomes more a public living room restaurant, office and so forth than a private space when poor mobility means they spend much time it in – to talk about their lives, their difficulties, and dealing with austerity. Or, for instance, like the Bolshy Divas, who mimic public and political policy, reports and advertising paranoia to undermine their discourses about austerity. I examine the effects, politics and ethics of such interventions, including examination of the comparative effect of highly bodied interventions (like Crow’s) and highly disembodied interventions (like the Bolshy Diva’s) in discourses of difficulty, disaster and austerity on a range of target spectator communities.

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Though there is much interest in mobilities and performing mobilities as a characteristic of modern, urban, social life today, this is not always matched by attention to immobilities, as the flipside of mobility in modern life. In this paper, I investigate public space performances designed to draw attention to precisely this counterpoint to current discourses of mobilities – performances about the socially produced immobilities many people with disabilities find a more fundamental feature of day-to-day life, the fight for mobility, and the freedom found when accommodations for alternative mobilities are made available. Although public policy is increasingly aligned with a social model of disability, which sees disability as socially constructed through systems, institutions and infrastructure deliberately designed to exclude specific bodies – stairs, curbs, queues and so forth – and although governments in the US, UK, and to a lesser degree Australia, New Zealand and other Commonwealth nations aim to address these inequalities, the experience of immobility is still every-present for many people. This often comes not just from pain, or from impairment, or event from lack of accommodations for alternative mobilities, but from fellow social performers’ antipathy to, appropriation of, or destruction of accommodations designed to facilitate access for a range of different bodies in public space, and thus the public sphere. The archetypal instance of this tension between the mobile, and those needing accommodations to allow mobility, is, of course, the antipathy many able bodied people feel towards the provision of disabled parking spaces. A cursory search online shows thousands of accounts of antagonism, vitriol, and even violence prompted by disputes which began when a disabled person asked an able person to exit a designated disabled parking space. For many, it seems, expecting them to pass by such parks so others can experience the mobility they take for granted is too much. In this paper, I examine a number of protest performances in public space in which activist present actions – for example, placing wheelchairs in every regular parking space in a precinct – to give bystanders, passersby and spectators, as well as antagonistic fellow social performers, a sense of what socially produced immobility feels like. I examine responses to such protest performances, and what they say about the potential social, political and ethical impacts of such protests, in terms of their potential to produce new attitudes to mobility, alternative mobility, and access to alternative modes of mobility.

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A score investigating issues of mobility, accessing mobility, and alternative mobility.