77 research outputs found
Moses Matet
Get PDFabstract: Moses was five years old when bombs hit his village. After fleeing his village he lived in a refugee camp with 30-40,000 people.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age: 25Region: Upper NileThis picture and bio was donated to the "Lost Boys Found" oral history project from The Arizona Lost Boys Cente
IMAGING AND BIOLOGICAL MARKERS IN RETINAL DISORDERS TO ASSESS GENE THERAPY SAFETY AND INVESTIGATE VASCULAR DISEASE MECHANISMS
No full textThe retina is the neurosensory tissue responsible for the acquisition of visual stimuli. It is biologically separated from the systemic circulation by blood-retinal barriers, limiting the possibility for circulating markers to reflect retinal changes due to disease or therapeutic intervention. However, due to the transparency of ocular media, the retina is highly accessible to high-resolution imaging, and image processing provides access to physiological parameters quantitatively. In addition, the analysis of ocular media sampled during surgical procedures provides access to biological data regarding disease processes. In this work, imaging and biological markers were developed for several experimental and clinical situations: a gene therapy preclinical safety study (Project 1); the analysis of disease mechanisms in the choroical choroidal vascular disorder central serous chorioretinopathy (CSCR) (Project 2), and a similar translational approach in retinal vascular telangiectatic disorders (Project 3). Specific image processing algorithms were designed.
In Project 1, the preclinical safety of a lentiviral subretinal gene therapy for RPE65 replacement in Leber congenital amaurosis, LV-RPE65, was assessed on healthy non-human primates by conventional methods (in vivo electrophysiology, ex vivo immunohistochemistry, systemic biodistribution study) combined to in vivo analysis of the retinal structure by optical coherence tomography (OCT) at different timepoints, including early follow-up within 7 days. Imaging techniques revealed a transient and pronounced inflammatory process linked to LV-RPE65 injection that delayed retinal reattachment. Partial and transient photoreceptor loss was observed in the macular region, that was to a lesser extent also observed in control eyes injected with the vehicle. This work highlights the need to improve the surgical procedure for subretinal gene therapy delivery, and to consider using anti-inflammatory agents to prevent damaging processes occurring rapidly after subretinal injection.
In Project 2, mechanisms of CSCR, a retinal disease caused by choroidal vessel dilation leading to subretinal fluid accumulation, were explored. We analyzed predictive multimodal imaging factors of episode duration (2a) and recurrence (2b), evidencing in particular choroidal thickness as prognosis factor. Non-invasive OCT angiography images of the choriocapillaris, the innermost layer of the choroid beneath the retinal pigment epithelium, were processed to detect flow voids and investigate their distribution (2c). Finally, the molecular composition of subretinal fluid from a unique case of CSCR requiring subretinal surgery, was explored using a multi-omics approach (2d).
In Project 3, mechanisms of retinal vasculopathy were investigated in two pure phenotypes represented by telangiectatic disorders: type 1 macular telangiectasia (Mactel 1) (3a and 3b), and radiation maculopathy (3c). For the investigation of Mactel 1, image processing tools were used to compute global and local capillary density on OCT angiography images, showing that non-perfusion is a critical feature in Mactel 1, related to visual outcome and telangiectasia formation. This approach was combined to the biological investigation of aqueous humor from Mactel 1 cases. Intraocular levels of angiogenic factors demonstrated the involvement of placental growth factor in the pathophysiology of MacTel 1, that was correlated with multimodal imaging findings (3b). Finally, an image processing algorithm was designed and applied to radiation maculopathy, to compute automatically the fractal dimension of OCT angiography images. This parameter was relevant in assessing capillary network disruption, and demonstrated that alterations of the deep plexus influence independently visual function.
The strategies developed throughout these three projects demonstrate the interest of quantitative image analysis for the investigation of retinal disorders, and the possibility of coupling imaging and biological data. This approach contributed to identify potential imaging or biological markers for diagnosis, prognosis, therapeutic response and toxicity in several biomedical situations.
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La rétine est un tissu neurosensoriel responsable de l'acquisition des signaux visuels. Elle se trouve biologiquement séparée de la circulation systémique par les barrières hémato-rétiniennes, limitant la possibilité pour des marqueurs circulants de refléter des altérations du tissu rétinien, dus à des maladies ou secondaires à des interventions thérapeutiques. Cependant, en raison de la transparence des milieux oculaires, la rétine est accessible à l'imagerie haute résolution, et l’analyse d'images permet d’extraire des paramètres physiologiques quantitatifs. En outre, l'analyse des milieux oculaires prélevés au cours d’interventions chirurgicales permet d'accéder à des données biologiques concernant les processus physiopathologiques. Dans ce travail, des marqueurs biologiques et d'imagerie ont été développés pour plusieurs situations expérimentales et cliniques : une étude de sécurité préclinique en thérapie génique (Projet 1), l'analyse de mécanismes pathologiques dans la choriorétinopathie séreuse centrale (CRSC) (Projet 2), et dans les pathologies télangiectatiques vasculaires rétiniennes (Projet 3). Des algorithmes de traitement d'image spécifiques ont été conçus.
Dans le Projet 1, la tolérance préclinique d'une thérapie génique sous-rétinienne lentivirale pour remplacement du gène RPE65 dans l'amaurose congénitale de Leber, LV-RPE65, a été évaluée sur des primates non humains sains par des méthodes conventionnelles (électrophysiologie in vivo, immunohistochimie ex vivo, étude de biodistribution systémique), et par analyse in vivo de la structure rétinienne par tomographie par cohérence optique (OCT) à différents points, y compris un suivi précoce dans les 7 jours. Les techniques d'imagerie ont révélé un processus inflammatoire transitoire lié à l'injection de LV-RPE65 qui a retardé le réattachement rétinien. Une perte partielle et transitoire des photorécepteurs a été observée dans la région maculaire, détécté également, et dans une moindre mesure dans les yeux témoins, injectés avec la solution véhicule. Ce travail souligne la nécessité d'améliorer la procédure chirurgicale pour l’administration de thérapies géniques sous- rétiniennes, et d'envisager l’usage d’agents anti-inflammatoires pour limiter ces altérations.
Dans le projet 2, les mécanismes de la CRSC, une maladie rétinienne causée par la dilatation des vaisseaux choroïdiens menant à l'accumulation de liquide sous-rétinien, ont été explorés. Nous avons analysé les facteurs d'imagerie multimodaux prédictifs de la durée des épisodes (2a) et de récurrence (2b), mettant en évidence notamment l'épaisseur choroïdienne comme facteur pronostic. Des images en OCT angiographie, non invasive, de la choriocapillaire, la couche la plus interne de la choroïde sous l'épithélium pigmentaire rétinien, ont été traitées pour détecter des lacunes dans le flux sanguin, et étudier leur distribution (2c). Enfin, la composition moléculaire du liquide sous-rétinien d'un cas rare de CRSC nécessitant une chirurgie sous-rétinienne, a été explorée en utilisant une approche multi- omique collaborative (2d).
Dans le projet 3, les mécanismes de vasculopathie rétinienne ont été étudiés dans deux phénotypes purs représentés par les troubles télangiectasiques : télangiectasie maculaire de type 1 (Mactel 1) (3a et 3b), et maculopathie radique (3c). Pour l'étude de Mactel 1, des outils de traitement d'images ont été utilisés pour calculer la densité capillaire globale et locale sur des images d’OCT angiographie, montrant que la non-perfusion est un paramètre critique dans les Mactel 1, corrélé à la fonction visuelle et à la formation des télangiectasies. Cette approche a été combinée à l'étude biologique de l'humeur aqueuse dans des cas de Mactel 1. Des niveaux intraoculaires de facteurs angiogéniques ont démontré l'implication du facteur de croissance placentaire dans la physiopathologie de MacTel1. De plus, ce facteur était corrélé avec la densité capillaire en OCT angiographie (3b). Enfin, un algorithme de traitement d'images a été conçu et appliqué à la maculopathie radique pour calculer automatiquement la dimension fractale des images d’OCT angiographie. Ce paramètre était pertinent dans l'évaluation de la perturbation du réseau capillaire, et a démontré que les altérations du plexus profond influencent indépendamment la fonction visuelle.
Les stratégies développées dans ce travail démontrent l'intérêt de l'analyse d'image quantitative pour l'étude des pathologies rétiniennes, et la possibilité de coupler l'imagerie et les données biologiques. Cette approche a permis d'identifier des marqueurs biologiques ou d'imagerie potentiels pour le diagnostic, le pronostic, la réponse thérapeutique et la toxicité dans les différentes situations étudiées
Resolution of foveal detachment in dome-shaped macula after treatment by spironolactone: report of two cases and mini-review of the literature
No full textAli Dirani,1 Alexandre Matet,1 Talal Beydoun,2 Irmela Mantel,1 Francine Behar-Cohen1–3 1Department of Ophthalmology, University of Lausanne, Jules Gonin Eye Hospital, Lausanne, Switzerland; 2Department of Ophthalmology, Hôtel-Dieu de Paris Hospital, Assistance Publique – Hôpitaux de Paris, Paris, France; 3Inserm UMRS872, Physiopathology of Ocular Diseases: Therapeutic Innovations, Centre de Recherche des Cordeliers, Paris, France Abstract: Dome-shaped macula (DSM) was recently described in myopic patients as a convex protrusion of the macula within a posterior pole staphyloma. The pathogenesis of DSM and the development of associated serous foveal detachment (SFD) remain unclear. The obstruction of choroidal outflow and compressive changes of choroidal capillaries have been proposed as causative factors. In this paper, we report two cases of patients with chronic SFD associated with DSM treated with oral spironolactone. After treatment, there was a complete resolution of SFD in both patients. To the best of our knowledge, this is the first report of successful treatment of SFD in DSM by a mineralocorticoid receptor antagonist. Keywords: serous foveal detachment, mineralocorticoid receptor antagonist, dome-shaped macula, treatmen
Retinal ischemia in radiation retinopathies: radiobiological concepts and clinical spectrum
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Argus II retinal prosthesis implantation with scleral flap and autogenous temporalis fascia as alternative patch graft material: a 4-year follow-up
No full textAlexandre Matet,1,2 Nawel Amar,1,2 Saddek Mohand-Said,1–4 José-Alain Sahel,1–7 Pierre-Olivier Barale1,2 1INSERM and DHOS, CHNO des Quinze-Vingts, 2Sorbonne Universités, UPMC Univ Paris 6, Institut de la Vision, 3INSERM, 4CNRS, Paris, France; 5Institute of Ophthalmology, University College London, London, UK; 6Fondation Ophtalmologique Adolphe de Rothschild, 7Académie des Sciences, Institut de France, Paris, France Introduction: The Argus II retinal prosthesis is composed of an epiretinal electrode array positioned over the macula and connected to an extrascleral electronics case via a silicone cable, running through a sclerotomy. During implantation, the manufacturer recommends to cover the sclerotomy site with a patch of processed human pericardium to prevent postoperative hypotony and conjunctival erosion by the underlying electronics case. Due to biomedical regulations prohibiting the use of this material in France, we developed an alternative technique combining a scleral flap protecting the sclerotomy and an autogenous graft of superior temporalis fascia overlying the electronics case. Methods: The purpose of this study is to describe the 4-year outcomes of this modified procedure in three subjects who underwent Argus II Retinal Prosthesis System implantation. Clinical data consisting of intraocular pressure measurements and tolerance in terms of conjunctival erosion or inflammation were retrospectively assessed over a 4-year postoperative follow-up. Results: None of the three patients implanted with the modified technique developed ocular hypotony over 4 years. A normal, transient conjunctival inflammation occurred during the first postoperative month but conjunctival erosion was not observed in any of the three patients over 4 years. Four years after implantation, the autogenous temporalis fascia graft remained well tolerated and the retinal prosthesis was functional in all three patients. Conclusion: The combination of an autograft of superficial temporalis fascia and a scleral flap efficiently prevented leakage through the sclerotomy site, ocular hypotony, and conjunctival erosion by the extrascleral electronics case. This modified technique is suitable for the implantation of existing and forthcoming retinal prostheses. Superficial temporalis fascia may also be used as alternative to commercial tectonic tissues for scleral wound repair in clinical settings where they are not available. Keywords: visual prosthesis, retinitis pigmentosa, surgical procedure, conjunctiva, intraocular pressur
Emerg Infect Dis
No full textCataract and uveitis are rare in newborns but potentially blinding. Three newborns with cataract and severe anterior uveitis underwent cataract surgery. Spiroplasma ixodetis was detected in lens aspirates using bacterial 16S-rRNA PCR and transmission electron microscopy. These findings, which suggest maternal-fetal infection, are consistent with previous experimental Spiroplasma-induced cataract and uveitis
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