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Ischemia-Reperfusion Dynamics in Acute Myocardial Infarction Experimental Swine Model: New Insights from Quantitative CMR
No full textInternational audienceAims To reveal the pattern and dynamics of myocardial edema induced by myocardial infarction (MI) during ischemia and subsequent reperfusion, that remain largely unknown, as are the factors that contribute to reperfusion injury. To propose a time-resolved dynamic myocardial tissue characterization by quantitative CMR, with T1&T2 mapping and Pixel-wise standardized analysis to circumvent inter-animal differences and subjective ROI positioning. Methods and Results We measured T1&T2 relaxation times at baseline, during a 40-minutes transient coronary occlusion, and after reperfusion in an open-chest swine MI model (n=20; 2 shams) using MRI. Myocardial function, early and late gadolinium enhancement were also assessed. Pixel-wise standardized analysis was used to compare the image contents at each pixel across individuals and time points. A significant increase in cardiac T1&T2 times in the ischemic regions occurred during ischemia compared to baseline (mean ΔT1=118.8ms i.e. +11.1%, ΔT2=5.6ms i.e. +11.3%; p<0.05). A global significant and marked increase in T1&T2 times further appeared immediately after reperfusion (mean ΔT1=256.8ms i.e. +23.3% mean ΔT2=11.9ms i.e. +23.6%, p<0.001). This increase was associated with myocardial wall thickness changes, with regional and global dysfunction in the ischemic myocardium. Three different reperfusion patterns were differentiated by the pixel-wise T1 signal analysis: effective reperfusion with microvascular obstruction (MVO), effective reperfusion without MVO and absence of effective reperfusion. We found no correlations between baseline, per-ischemia, and post-reperfusion native T1&T2 times when effective reperfusion occurred. Conclusions Objective quantification of tissue response by pixel-wise analysis demonstrated rapid and significant changes in myocardial water content status post-reperfusion, with three different early-reperfusion patterns observed, suggesting distinct reperfusion mechanisms. The water content after reperfusion does not reflect its state before and it does not provide insight into the final tissue status observed within 3 hours after recanalization
A Colonial Lens on the High Ground: Imperial Vantage Points in British India and French Indochinese Hill Stations
No full textInternational audienceThis paper focusses on the photographic production within South Asian and Southeast Asian hill stations, established by the British and the French empires in India and in Vietnam, throughout the 19th century. In both countries, hill stations stem from early colonial developments. These remote colonial enclaves were used for a variety of purposes that evolved through time: sanitary, political, military, leisure and commercial (Kennedy 1996). They can be looked at as spatial and symbolic manifestations of imperialism, designed to expand colonial domination to all the corners of the Empire (Mitchell 2002).In order to settle in the hills, the landscape itself had to be domesticated through urban planning, architecture, roads, institutions catering for the new occupants (Sacareau 2007). Soon enough, photography started to be used as a means to document the places, account for their changes, and promote a certain image of the hill stations to a broader audience. Today, vast collections of photographs taken in the hills are kept in colonial archives, be it at the British Library (UK) for India or at the Archives Nationales d’Outre-Mer (France) for Vietnam.Based on a sample of photographs taken between the 1840’s and the 1940’s, this paper will explore the imperial gaze – and visual discourse – on these hill stations. It will interrogate the aesthetics and meanings of these photographs and address the issue of their circulation within and beyond the empires, in order to understand the ways in which photography was used to imprint its gaze and legitimize to the colonisers’ presence.We will examine the tools used to construct this visuality through the photographs that were taken by the colonial settlers on site, for personal and/or propaganda purposes. These photographs were instrumental in defining new aesthetical and scenic functions for these mountains, whose beauty is closely linked to their domination (Zytnicki and Hazdaghli, 2009). The construction of viewpoints, panoramas and hiking trails, and later cable cars, can be explained as panoptic devices serving the construction of a heterotopia (Foucault, 1984). These high angled photographs exploit a symbolic vantage point and enact the domination of these peripheral mountain spaces (Mirzoeff, 2011). They allow contemplating both nature and its colonial reordering, embracing a vast space appropriated to serve racial recreation (Jennings, 2011). Thus, tourism was a consensual and enduring way to not only in the construct, but also in to glorify and promote the imperial gaze
Multi-serotype nested immuno-epidemiological model for dengue hemorrhagic fever involving backward bifurcation and serotype invasion
No full textInternational audienceReinfection with the same dengue serotype is generally benign, as individuals develop protective immunity. On the other hand, in the case of reinfection with a different serotype, pre-existing antibodies can increase the risk of developing Dengue Hemorrhagic Fever (DHF), by inducing Antibody-Dependent Enhancement (ADE). To model this dynamic, we introduce a multi-scale immuno-epidemiological system. The immunological part is described by a system of ODEs representing the interaction between two antibodies (from previous and current infection) and the virus. The epidemiological part is represented by an infection-age structured SIRS system (for both the {\color{red} primary and secondary} infections) and a recovery-age structured equation (for the first infection). A detailed mathematical analysis of the equilibrium points of the multi-scale reinfection model, including disease-free, mono-endemic and bi-endemic states, is performed. We establish necessary and sufficient conditions for the existence of backward bifurcations and derive an expression for the invasion reproduction number, which shows that the second serotype can invade the population after a mono-endemic first serotype. We also investigate the dependence of the basic and invasion reproduction numbers on the immunological parameters of the first and second infections. This gives us a better understanding of the relationship between DHF and ADE during secondary infection
Austérité sanitaire Face à l’érosion de l’économie fondamentale dans les espaces délaissés
No full textInternational audienceSmall and medium-sized cities have long been sidelined in urban research. However,they have recently come to the forefront of media, political and academic debate. Thenotion of “left-behind places” questions the rise of territorial inequalities that lead tothe marginalisation of territories previously integrated into national dynamics, but alsothe political and social consequences of these developments.The article presents two cities that can be considered as left-behind: Roanne, amedium-sized city of 34,000 inhabitants, and La Grand-Combe, a small town of5,000 inhabitants. In a French context where the withdrawal of the state is perceptiblein a number of spheres of public action, the article is based on the analysis of a keysector of the “fundamental economy”: healthcare. The study of the evolution of thissector allows us to refine the analysis of the austerity policies implemented in France.These policies are characterised less by spectacular cuts in funding than by a slowerosion of the workforce, an unequal distribution of resources and a concentration ofsupply that affects access to care.Longtemps restées à la marge de la recherche urbaine, les villes petites et moyennesse sont récemment imposées dans les débats médiatiques, politiques et académiques.La notion d’« espaces délaissés » permet d’interroger la montée des inégalitésterritoriales qui conduisent à la marginalisation de territoires auparavant intégrés dansles dynamiques nationales, mais aussi les conséquences politiques et sociales de cesévolutions.L’article présente deux villes en déclin : Roanne, une ville moyenne de 34 000 habitantset La Grand-Combe, une petite ville de moins de 5 000 habitants. Dans un contextefrançais où le retrait de l’État est perceptible dans un ensemble de sphères de l’actionpublique, ce texte s’appuie sur l’analyse d’un secteur clé de l’« économiefondamentale » : la santé. L’étude des évolutions de ce secteur permet d’affiner celledes politiques d’austérité mises en oeuvre en France. Celles-ci se caractérisent moinspar des coupes spectaculaires dans les dotations que par une lente érosion deseffectifs, une inégale répartition des ressources, et une concentration de l’offre quiaffecte l’accès aux soins
On the validity of the Moes iso-viscous - Rigid film thickness prediction, the influence of domain starvation and the parabolic geometry approximation
No full textThe validity of the Isoviscous Rigid film thickness prediction by Moes is analysed as well as the validity of the parabolic geometry approximating the spherical geometry
Within‐Host Environmental Heterogeneity Is Associated With Phenotypic but Not Genomic Diversity in Wolbachia Endosymbionts
No full textInternational audienceHosts represent complex environments where different tissues may act as distinct ecological niches, imposing different constraints that may shape parasite ecology and evolution. Such within‐host heterogeneity can generate phenotypic diversity with consequences for virulence and transmission. Our aim was to determine whether the constraints associated with infecting different host tissues lead to the coexistence of multiple parasite sub‐populations with distinct phenotypes. We tested this hypothesis using the widespread bacterial endosymbiont Wolbachia . We injected bacteria isolated from three tissues of the common pill‐bug into uninfected individuals and tracked temporal changes in Wolbachia load in the recipient host tissues, as well as the virulence associated with each bacterial source. Our results show that colonisation success depends on the tissue of origin of the injected Wolbachia . Genome resequencing did not detect any genetic variation associated with variation in bacterial replication rate, which thus likely results from phenotypic plasticity. Indeed, no recurrent tissue‐specific variants were detected, and our conservative filtering pipeline retained only one substitution and one gene conversion event. These findings highlight the genomic stability of Wolbachia across host environments while demonstrating that within‐host diversification can occur without genetic divergence. More broadly, they underscore how microenvironmental variation within hosts can shape parasite ecology
The calf holobiont under challenge: longitudinal microbiome-pathogen dynamics and respiratory health
No full textThe Bovine Respiratory Disease Complex (BRDC) is a major health and welfare challenge driven by multifactorial interactions among pathogenic viruses and bacteria, host and environmental factors, and the respiratory and gut microbiomes. Many implicated bacterial pathogens are also commensals of the respiratory tract, complicating diagnosis and prevention. Growing evidence indicates the roles of the respiratory and gut microbiomes in BRDC, yet their combined effects remain poorly understood. In this study, we dynamically followed the microbiome, pathogen load, and host response in 30 calves over 147 days under commercial rearing conditions. Nearly half developed BRDC, with elevated fever, cough, and lung sound scores, and peak symptoms at day 58 after feedlot arrival. Pathogen detection in nasal cavities revealed distinct patterns: Mycoplasma bovis and BCoV peaked during the first two weeks, IDV and Histophilus somni after one month, Mannheimia haemolytica after two, while Pasteurella multocida peaked after one month and persisted. Importantly, M. haemolytica and Pasteurella multocida loads correlated with higher BRDC scores, whereas BCoV and Mycoplasma bovis were associated with diarrhea, suggesting systemic effects. Nasal beta-diversity diverged between groups at the symptomatic window, and healthy animals exhibited higher fecal diversity and evenness early in life. The respiratory pathobionts Pasteurella and Corynebacterium were enriched in diseased calves, whereas potentially protective families (Lachnospiraceae, Oscillospiraceae) were more abundant in healthy ones. Multivariate analyses confirmed that antibiotic treatments and short-chain fatty acids, especially isovalerate and isobutyrate, further modulated both fecal and nasal microbiomes, with consistently stronger impacts in diseased animals. Together, these findings demonstrate that BRDC outcomes are shaped not by pathogen burden alone, but by the interplay among respiratory and digestive microbiotas, pathogens, environment, and host factors. Our study highlights the importance of a holobiont perspective that integrates both gut and respiratory microbiotas to better elucidate the complexity of BRDC. Such an inclusive framework may provide new insights into disease mechanisms and inform the development of innovative therapeutic strategies
Numerical modeling of dust particle motion in a corona discharge-based ionic wind cleaning system for solar panels
No full textInternational audienceThis study explores innovative solutions to reduce efficiency losses in solar panels caused by dust accumulation, using corona discharge as a mitigation method. Ions produced by the positive or negative corona discharge transfer momentum to neutral air molecules through collisions, resulting in an airflow (ionic wind) that can help to eliminate dust accumulation. The cleaning system whose operation is numerically modeled consists of a corona blower device that moves along the panel, conveying the dust in a linear direction and providing a non-contact cleaning method. Dust particles are affected by different forces, such as Coulomb force, gravitational force, aerodynamic drag force, and van der Waals adhesion. Poisson's equation, the continuity equation for charged particles and the Navier-Stokes equations are solved to evaluate the Coulomb and drag force. Emphasis is placed on understanding how forces affect particle trajectories, and which forces are most relevant to the operation of the cleaning system
Vascular dysfunctions during radiation retinopathy
No full textInternational audienceOptic tissue toxicity remains a major limitation of radiation therapy for ocular, brain, skull base, and head and neck tumors. Among the most frequent complications, radiation retinopathy (RR) occurs in 6% of patients treated for extraocular tumors and in more than 40% of those with ocular tumors. After an initial asymptomatic stage characterized by vascular remodeling and chronic retinal ischemia, RR may progress to irreversible vision loss and significantly impaired quality of life. Advances in non-invasive, high-resolution imaging have improved our understanding of the molecular and cellular mechanisms underlying RR in both preclinical and clinical models. In particular, multimodal imaging-and especially optical coherence tomography angiography (OCTA)-has enabled earlier detection of RR in humans. Animal studies have highlighted vascular obstruction and rarefaction, together with early neurovascular dysfunction, as central features of the clinical phase. Beyond preventive measures such as dose constraints, biological and imaging biomarkers may help guide targeted interventions. In this review, we summarize current evidence on the sequential endothelial and neuronal alterations that drive RR and discuss molecular and cellular pathways that could inform the development of potential therapeutic strategies