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Effect of PHF-1 hyperphosphorylation on the seeding activity of C-terminal Tau fragments
No full textInternational audienceTau proteins as neurofibrillary tangles are one of the molecular hallmarks of Alzheimer’s disease (AD) and play a central role in tauopathies, a group of age-related neurodegenerative disorders. The filament cores from diverse tauopathies share a common region of tau consisting of the R3-R4 microtubule-binding repeats and part of the C-terminal domain, but present a structural polymorphism. Unlike the fibril structure, the PTM signature of tau found in neuronal inclusions, more particularly hyperphosphorylation, is variable between individuals with the same tauopathy, giving rise to diverse strains with different seeding properties that could modulate the aggressiveness of tau pathology. Here, we investigate the conformation, function and seeding activity of two tau fragments and their GSK3β-phosphorylated variants. The R2Ct and R3Ct fragments encompass the aggregation-prone region of tau starting at the R2 and R3 repeats, respectively, and the full C-terminal domain including the PHF-1 epitope (S396, S400, S404), which undergoes a triple phosphorylation upon GSK3β activity. We found that the R3Ct fragment shows both a greater loss of function and pathological activity in seeding of aggregation than the R2Ct fragment which imposes a cross-seeding barrier. PHF-1 hyperphosphorylation induces a local conformational change with a propensity to adopt a β-sheet conformation in the region spanning residues 392-402, and exacerbates the seeding ability of fragments to induce aggregation by overcoming a cross-seeding barrier between tau variants
Advances in intravascular lithotripsy: mechanisms, devices, and clinical applications
No full textInternational audiencePeripheral arterial disease (PAD) complicates endovascular interventions due to vascular calcifications, which compromise procedural success and long-term outcomes. Intravascular lithotripsy (IVL) represents a promising innovation to modify calcified lesions with shockwaves, addressing unmet clinical needs. This review explores the mechanisms, devices, and clinical applications of IVL in PAD treatment. It highlights the limitations of conventional approaches (high-pressure balloons, specialty balloons, atherectomy), which often result in suboptimal lesion preparation and procedural complications. Particular emphasis is placed on the combination of atherectomy and IVL, as well as the various IVL devices available and in development, beyond those from Shockwave Medical. Additionally, we discuss future perspectives, including drug penetration enhancement and the issue of post-IVL recoil. Additionally, the literature review methodology, encompassing searches in PubMed and Embase, from January 2008 to December 2023, is briefly outlined. IVL offers a safe, effective, and innovative approach to treating calcified lesions while preserving surrounding tissues. However, the current evidence, mainly derived from industry-funded studies, is limited by heterogeneous calcification classifications and a lack of long-term outcome data. Independent research is essential to define IVL's role in PAD treatment algorithms, especially regarding its cost-effectiveness and long-term primary patency outcomes
A pictorial identification key for Mediterranean and Middle Eastern Phlebotomus sand flies
No full textInternational audienceGiven the significance of leishmaniasis as a neglected parasitic disease—ranking second in mortality and fourth in morbidity among vector-borne diseases—and the prominence of the Mediterranean and Middle East regions as key areas for leishmaniasis incidence, the study and precise morphological identification of sand flies, the proven vectors of the disease, is crucial. Unfortunately, despite this importance, there are few reliable references or identification keys for the morphological identification of sand flies in the Middle East and Mediterranean regions. Some are outdated and no longer valid or remain local (restricted to a country). To date, no comprehensive study has been conducted on the sand fly fauna and their morphological characterization across these regions. In response to this gap, we present a comprehensive pictorial identification key for male and female Phlebotomus species of Middle East and Mediterranean areas. The key includes 720 selected photos and illustrations demonstrating discriminative morphological features out of 2,000 collected. Furthermore, a collection including descriptive morphological criteria of sand flies, first description of Phlebotomus species, a comprehensive checklist of Phlebotomus species accompanied by their distribution map across Middle Eastern and Mediterranean countries, as well as extensive information on their morphometry, ecology, medical relevance, synonymy, atypical forms and morphology of female Adlerius species are given. Finally, we provide an online pictorial dichotomous key to facilitate field application
Genetic relatedness of Staphylococcus aureus isolates within food outbreaks by single nucleotide polymorphisms
No full textInternational audienceInvestigation of bacterial food outbreaks by whole genome sequencing can rely on the inspection of the genetic relatedness between isolates through the application of single nucleotide polymorphism (SNP) thresholds. However, there is no consensus for Staphylococcus aureus in the context of food outbreaks. In this study, we propose a SNP cut-off by taking into account the mutation rate and the evolution time of this pathogen in food. Through in vitro microevolution, we determined the mutation rate of three S. aureus strains grown under mimicked food stressing conditions. From the mutation rate, we set a cut-off of 28 SNPs considering 30 days as evolution time based on the average shelf-life of foods contaminated by S. aureus and the timeline for identifying this pathogen in outbreaks. The SNP threshold was applied to retrospectively study ten staphylococcal food outbreaks to assess whether isolates from food and/or of human origin from the same outbreak were epidemiologically related. To interpret SNP distances, phylogenetic tree topologies and bootstraps were integrated and showed that isolates differing by up to 28 SNPs were monophyletic. Our suggested cut-off can be used in outbreak management to identify closely related S. aureus strains
Emoquine-1: A Hybrid Molecule Efficient against Multidrug-Resistant Plasmodium Parasites, Including the Artemisinin-Resistant Quiescent Stage, and Also Active In Vivo
No full textInternational audienceTo challenge the multidrug resistance of Plasmodium falciparum malaria parasites, new hybrid compounds were synthesized and evaluated against laboratory strains and multidrug-resistant clinical isolates. Among these hybrids, emoquine-1 was the most active on proliferative P. falciparum, with IC50 values in the range of 20–55 nM and a high selectivity index with respect to mammalian cells. This drug retained its activity on several multiresistant field isolates from Cambodia and Guiana, exhibited no cross-resistance to artemisinin, and is also very active against the quiescent stage of the artemisinin-resistant parasites, three features that constitute the gold standard for new antimalarial drugs. In vivo, emoquine-1 is active against Plasmodium vinckei petteri at 25 mg/kg/d per os and by the intraperitoneal route at 1–5 mg/kg/d, with total cure at 10 mg/kg/d, making emoquine-1 an ideal candidate to fight Plasmodium parasites resistant to artemisinin-based combination therapies (ACTs) with a capacity to eliminate persistent parasites
Allocation and prognosis of temporary mechanical circulatory support in unselected cardiogenic shock: Insights from the FRENSHOCK registry
No full textInternational audienceBackground: Patients in cardiogenic shock (CS) can benefit from temporary mechanical circulatory support (tMCS) but data in heterogeneous populations with diverse CS aetiologies are rare.Aims: To compare baseline characteristics, management and independent correlates of 30-day and 1-year mortalities between patients managed with and without tMCS for CS.Methods: The FRENSHOCK registry (NCT02703038) included 772 unselected patients with CS admitted in 49 French critical care units between April and October 2016.Results: Among 770 patients with CS and available data, 135 (17.5%) received tMCS (63 extracorporeal life support, 35 intra-aortic balloon pump, 13 micro-axial flow pump and 24 combination), of whom 69.0% were implanted during the first 24hours. Patients with tMCS were less likely to present with histories of cardiac or peripheral artery diseases or chronic renal failure. An ischaemic or mechanical complication trigger for CS tripled the probability of receiving tMCS, while increased lactate doubled the probability. Thirty-day mortality was higher among patients with versus without tMCS (34.1% vs. 24.3%; P<0.001), but after adjustment for age and CS severity (LVEF and arterial lactates at admission, noradrenaline and invasive mechanical ventilation use), the difference was no longer significant (hazard ratio: 1.37, 95% confidence interval: 0.93-2.01). Among 30-day survivors, mortality was similar regardless of initial receipt of tMCS (P=0.312).Conclusion: In real-life practice, tMCS may not be associated with improvements in 30-day or 1-year mortality in an all-comers cohort of patients with CS. However, it should be noted that there were substantial differences in patient characteristics and management between patients who received tMCS and those who did not. Additional targeted studies should help to determine more precise algorithms for granting assistance within the complex and heterogeneous population of patients with CS
Rapport final du projet METDEP: La biosorption comme outil de dépollution des effluents chargés en éléments traces métalliques.
No full textCertaines espèces végétales vivent et se développent dans des environnements particulièrement hostiles et peu propices à la vie. Pour faire face aux stress environnementaux auxquels elles sontexposées, ces espèces végétales ont développé des stratégies adaptatives particulièrement efficaces, ainsi que des interactions (symbiotiques ou non) avec des microorganismes bénéfiques, eux-mêmesadaptés à ces contraintes environnementales. Parmi ces espèces végétales, on trouve notamment les plantes halophiles, fortement exposées à des concentrations salines élevées. En Nouvelle-Calédonie, ces espèces sont également parfois simultanément exposées à des concentrations en Eléments Traces Métalliques (ETM) importantes, résultant de l’érosion et de contaminations environnementales directes.Nous avons fait l’hypothèse que certaines espèces végétales des écosystèmes côtiers de Nouvelle-Calédonie (tannes), exposées à des stress salins et métalliques, pourraient représenter un réservoirpotentiel de microorganismes résistants aux ETM et au sel, et bénéfiques à la croissance des plantes. Nous avons entrepris la caractérisation complète de ces microorganismes par des approches debiologie moléculaire, puis nous avons réalisé leur isolement et leur caractérisation phénotypique, en testant notamment leurs résistances salines et métalliques, ainsi que leurs effets promoteurs de lacroissance des plantes (PGP) afin, in fine, de pouvoir en tirer des applications dans le domaine de la restauration écologique ou de la décontamination des eaux
Développement d’une chambre de périfusion pour l’analyse des sécrétions hormonales et l’évaluation du métabolisme des îlots de langerhans
No full textPancreatic Human islet of Langerhans (IL) transplantation is a promising clinical approach for the treatment of severe type 1 diabetes. However, the restoration of endogenous insulin secretion remains subject to many uncertainties (donor history, pancreas harvesting, cell islet processing, etc.), and the prediction of transplant success depends primarily on the quality of the insulin-secreting cells; hence the importance of being able to accurately evaluate a cell preparation before it is released to the transplant surgeon.Among the various assessment techniques, the glucose-stimulated insulin secretion (GSIS) test remains the gold standard for evaluating beta cell function. However, the static or dynamic (perifusion) GSIS used have limitations in terms of information, as they focus exclusively on insulin stimulation. Increasing experimental throughput to facilitate parallel studies is a crucial aspect in refining perifusion systems for more efficient and comparative GSIS analysis.Furthermore, due to the cellular heterogeneity of IL and inter-individual variability, it appears essential to combine other indicators for the evaluation of isolated IL.This thesis establishes several advances: (1) to study the beta cell heterogeneity in human donors of islet Perifusions (2) by developing CAD (Computer Aided Design) modeled prototype, (3) by developing Stereolithography-based 3D-fabricated perifusion mono chambers, (4) assembling a 4-stream perifusion system with associated components to access parallel perifusion studies and (5) to adopt a measurement of oxygen consumption during the perifusion process.The results of a single-center study of insulin secretion assessed by perifusion on a large number of IL preparations (n = 168) identified that donor physiological parameters, such as Body Mass Index (BMI), Body Surface Area (BSA) and HbA1c, influenced insulin secretion, particularly at low glucose concentrations, independently of sex. This study confirmed the importance of fasting insulin secretion as an indicator of the functional quality of isolated IL.In collaboration with IMT Nord Europe, we used CAD (SolidWorks) to model perifusion chambers and developed fluid flow analysis to ensure uniform perifusion that does not stress the IL during carbohydrate stimulation.We therefore manufactured perifusion chambers (mono chambers) using 3D printing technology based on stereolithography (SLA). These chambers confirmed the uniformity of flow and stability during assembly.Furthermore, an optical probe system was integrated post-chamber to monitor glucose-stimulated oxygen consumption rates (OCR). Our preliminary results confirmed measurable and reproducible metabolic responses in human islets within a single perifusion framework, and established a foundation for future studies.This thesis has demonstrated the high intra- and inter-individual heterogeneity of insulin secretion by isolated human islets of Langerhans and have led to the development of a tool for evaluating the in vitro metabolic functionality of isolated IL used in clinical practice or in scientific studies. This tool should contribute to the development of standardised platforms for future research on IL hormone secretion and provide a better understanding of the physiology of insulin secretion.La transplantation d'îlots pancréatiques humains de Langerhans (IL) est une approche clinique prometteuse pour le traitement du diabète de type 1 sévère. Cependant, la restauration de la sécrétion endogène d'insuline reste soumise à de nombreuses incertitudes (antécédents du donneur, prélèvement du pancréas, traitement des îlots cellulaires, etc.) et la prédiction du succès de la transplantation dépend principalement de la qualité des cellules sécrétrices d'insuline, d'où l'importance de pouvoir évaluer avec précision une préparation cellulaire avant qu'elle ne soit remise au chirurgien transplanteur. Parmi les différentes techniques d'évaluation, le test de sécrétion d'insuline stimulée par le glucose (GSIS) reste la référence pour évaluer la fonction des cellules bêta. Cependant, les tests GSIS statiques ou dynamiques (périfusion) utilisés présentent des limites en termes d'informations, car ils se concentrent exclusivement sur la sécrétion insulinique. De plus, du fait de l'hétérogénéité cellulaire des IL et de la variabilité interindividuelle, il semble essentiel de combiner d'autres indicateurs pour l'évaluation des IL isolées. Aussi perfectionner les analyses par périfusion semble crucial pour l’évaluation des cellules endocrines utilisées en clinique ou lors de protocoles expérimentaux.Au cours de ce travail de thèse, nous avons pu : (1) étudier, à l'aide de la technique de périfusion, l'impact de l'hétérogénéité des IL humains sur la sécrétion d'insuline ; (2) développer et fabriquer, à l'aide de l'impression 3D, des chambres de réactionnelles adaptées à la physiologie fine de l'IL ; (3) développer un système de périfusion permettant plusieurs analyses en parallèle et (4) adapter une mesure de la consommation d'oxygène continue pendant le processus de périfusion.Les résultats d'une étude monocentrique sur la sécrétion d'insuline évaluée par perfusion sur un grand nombre de préparations d'IL (n = 168) ont montré que les paramètres physiologiques des donneurs, tels que l’Indice de Masse Corporelle (IMC), la Surface Corporelle (SC) et l'HbA1c, influençaient la sécrétion d'insuline, en particulier à de faibles concentrations de glucose, indépendamment du sexe. Cette étude a confirmé l'importance de la sécrétion d'insuline à jeun comme indicateur de la qualité fonctionnelle de l'IL isolée.En collaboration avec l’IMT Nord Europe, nous avons utilisé la CAO (SolidWorks) pour modéliser des chambres de périfusion et développé une analyse des flux des fluides périfusés afin de garantir une périfusion uniforme qui ne stresse pas l'IL pendant la stimulation glucidique.Nous avons fabriqué des chambres de périfusion individuelle (mono-chambre) à l'aide d'une technologie d'impression 3D basée sur la stéréolithographie (SLA). Ces chambres étaient chargées par le bas, et des tests itératifs ont confirmé l'uniformité du flux et la stabilité opérationnelle pendant la stimulation cellulaire. Un système de sonde optique a été intégré en aval de la chambre de perfusion afin de mesurer les taux de consommation d'oxygène (OCR) pendant la stimulation au glucose.Cette thèse a démontré la grande hétérogénéité intra- et interindividuelle de la sécrétion d'insuline par les îlots de Langerhans humains isolés et a conduit au développement d'un outil permettant d'évaluer la fonctionnalité métabolique in vitro des IL isolés utilisés dans la pratique clinique ou dans les études scientifiques. Cet outil devrait contribuer au développement de plateformes standardisées pour les futures recherches sur la sécrétion d'hormones IL et permettre une meilleure compréhension de la physiologie de la sécrétion d'insuline
Altérations mitochondriales et musculaires à distance du sepsis : implication du Receptor for Advanced Glycation Endproducts (RAGE)
No full textSepsis is defined as a potentially life-threatening organ dysfunction caused by a dysregulated host response to infection. The majority of patients develop muscle weakness at the end of their ICU stay, which persists for several years and is associated with an increased risk of mortality. Skeletal muscle is a major determinant of overall health; its impairment degrades patients’quality of life and reduces physical capacities and autonomy. However, long-term muscular sequelae remain insufficiently studied at the cellular and molecular levels. In the acute phase, two major axes of alteration predominate: mitochondrial dysfunction (bioenergetic defects,alterations in quality-control pathways) and inflammation (notably through activation of the inflammasome and inflammatory cytokines). It remains to be determined whether, and how,these disturbances persist and evolve in the long term after sepsis. Moreover, in sepsis survivors, activation of the Receptor for Advanced Glycation End-products (RAGE) has been observed; this receptor is implicated in aging-related inflammation (inflammaging) and mitochondrial dysfunction. We therefore hypothesize that sepsis may induce, in the long term, an accelerated aging process that depends on chronic activation of RAGE. In a murine sepsis model, mice surviving 3 months after sepsis exhibit muscle weakness associated with decreased fatigue resistance, without apparent atrophy of oxidative fibers. This alteration is associated with mitochondrial dysfunction independent of mitochondrial biomass and rather linked to the persistence of oxidative and nitrosative damage within the muscle. In parallel, increased levels of the mitochondrial chaperone protein Hsp60 are observed, indicating mitochondrial stress. Its role as a DAMP could establish a direct link between mitochondrial dysfunction and inflammation. Moreover, in sepsis-surviving mice, activation of two inflammatory pathways has been demonstrated: the NLRP3/caspase-1 axis and the RAGE pathway. RAGE inhibition in mice subjected to the same sepsis protocol partially prevents the development of the previously observed long-term alterations. In conclusion, long-term post-sepsis alterations appear to follow the same pattern as in the acute phase, involving mitochondrial dysfunction and inflammation, which are associated with the maintenance of muscle weakness. The implication of RAGE and the effects of its inhibition appear promising for preventing these muscular disturbances. To confirm this hypothesis, it will be necessary to analyze in detail the link between mitochondrial dysfunction and inflammation in order to establish an appropriate therapeutic strategy.Le sepsis se traduit par une dysfonction d’organe potentiellement mortelle qui est induite par une réponse dysrégulée de l’hôte à une infection. La majorité des patients développent une faiblesse musculaire à l’issue du séjour en réanimation et persiste plusieurs années en étant associée à un risque de mortalité augmenté. Le muscle squelettique est un déterminant majeur dans la santé globale, son altération dégrade la qualité de vie des patients, réduit les capacités physiques et l’autonomie. Cependant, les séquelles musculaires à long terme demeurent encore insuffisamment étudiées sur le plan cellulaire et moléculaire. A la phase aiguë, deux axes majeurs d’altération dominent : la dysfonction mitochondriale (défauts bioénergétiques,altérations des voies de contrôle qualité) et l’inflammation (notamment via l’activation de l’inflammasome et de cytokines inflammatoires). Il reste à déterminer si, et de quelle manière,ces perturbations persistent et évoluent à long terme après le sepsis. Par ailleurs, chez les survivants du sepsis, il est observé une activation du Receptor for Advanced Glycation Endproducts (RAGE), un récepteur impliqué dans l’inflammation lié au vieillissement (inflammaging) et à la dysfonction mitochondriale. Nous émettons dès lors l’hypothèse que le sepsis puisse induire à long terme, un vieillissement accéléré, dépendant de l’activation chronique du RAGE.Dans un modèle de sepsis murin, les souris survivantes 3 mois après le sepsis présentent une faiblesse musculaire qui se traduit par une diminution de la résistance à la fatigue, sans atrophie apparente des fibres oxydatives. Cette altération est associée à une dysfonction mitochondriale indépendante de la biomasse mitochondriale et liée à la persistance de dommages oxydatifs et nitrosatifs au sein du muscle. Parallèlement, l’augmentation d’une protéine chaperonne mitochondriale, Hsp60, est augmentée, indiquant un stress mitochondrial. Son rôle comme Damaged Associated Molecular Pattern (DAMP) pourrait établir un lien direct entre la dysfonction mitochondriale et l’inflammation. D’autant, que chez les souris survivantes du sepsis, il a été mis en évidence l’activation de deux voies inflammatoires, la voieNLRP3/Caspase-1 et la voie RAGE. L’inhibition du RAGE chez des souris soumis au même protocole de sepsis prévient partiellement le développement des altérations à long terme précédemment observées. En conclusion, les altérations à long terme après le sepsis semblent suivre le même schéma qu’à la phase aigüe en impliquant la dysfonction mitochondriale et l’inflammation, qui sont associées au maintien de la faiblesse musculaire. L’implication et les effets de l’inhibition du RAGE semblent prometteurs pour prévenir ces perturbations du muscle. Pour confirmer cette hypothèse, il sera nécessaire d’analyser en détail le lien entre la dysfonction mitochondriale et l’inflammation pour établir une stratégie thérapeutique adaptée
Place des méthodes biologiques dans le diagnostic néonatal de la toxoplasmose congénitale en Tunisie
No full textInternational audienceIntroduction : At birth, the biological diagnosis of congenital toxoplasmosis (CT) is essentially serological.Aim : To report the results of biological techniques used in the neonatal diagnosis of CT.Methods: This was a descriptive study including newborns (NB) suspected of having CT who were referred to the Parasitology-Mycology laboratory of the Institut Pasteur of Tunis over a 17-year period. Newborns whose mothers had toxoplasmic infection during pregnancy, with either a negative or unperformed antenatal diagnosis, were included. The search for IgG and IgM antibodies was conducted using ELISA and western blot techniques.Results: Among the 224 newborns included, the first sample was taken between days 1 and 3 of life in 58% of cases. In 181 newborns from our series, the disappearance of IgG was observed at an average age of 4.8 ± 1.6 months. IgM was positive after day 10 of life in 11 cases. A comparative mother-newborn western blot was performed for 216 newborns (96.4%). The diagnosis of CT was confirmed in 43 newborns (19.2%): either based on a positive western blot in 30 cases (69.8%), the presence of IgM by ELISA after day 10 of life in 11 cases (25.6%), or the persistence of IgG after 12 months of follow-up in two cases (4.6%).Conclusion: Our study confirms the undeniable contribution of the comparative western blot in the diagnosis of CT at birth.Introduction:A la naissance, le diagnostic biologique de la toxoplasmose congénitale (TC) est essentiellement sérologique. Objectif: Rapporter les résultats des techniques biologiques utilisées dans le diagnostic néonatal de la TC. Méthodes: Il s'agissait d'une étude descriptive incluant les nouveau-nés (NN) suspects de TC adressés au laboratoire de Parasitologie-Mycologie de l'Institut Pasteur de Tunis durant 17 ans. Les NN dont les mères ont présenté une infection toxoplasmique au cours de la grossesse et pour lesquelles, un diagnostic anténatal était soit négatif soit non réalisé, ont été colligés. La recherche des anticorps IgG et IgM a été faite par les techniques ELISA et western blot. Résultats: Parmi les 224 NN inclus, le premier prélèvement a été effectué entre J1 et J3 de vie dans 58% des cas. Pour 181 NN de notre série, la disparition des IgG a été observée en moyenne à l'âge de 4,8 mois ± 1,6. Les IgM étaient positives au-delà de J10 de vie dans 11 cas. Un western blot comparatif mère-NN a été réalisé pour 216 NN (96,4%). Le diagnostic de TC a été retenu chez 43 NN (19,2%), soit devant un western blot positif dans 30 cas (69,8%), soit devant la présence d'IgM par ELISA au-delà de J10 de vie dans 11 cas (25,6%), soit devant le non-infléchissement des IgG au bout de 12 mois de suivi dans deux cas (4,6%). Conclusion: Notre travail confirme l'apport indéniable du western blot comparatif dans le diagnostic de la TC à la naissance.</div