Le psoriasis : évolution et révolution

Conséquence d’un renouvellement accéléré de l’épiderme entretenu par une inflammation chronique, le psoriasis associe, sur un terrain génétique particulier, une hyperréactivité variable de plusieurs gènes. La maladie se présente comme une réaction exagérée de la peau aux agressions de la vie quotidienne, qu’elles soient exogènes ou endogènes, ces agressions entraînant une libération excessive de cytokines pro-inflammatoires aboutissant au déclenchement d’un processus inflammatoire qui rend la maladie chronique. En fonction des modes successives, l’attention des chercheurs s’est portée sur les anomalies de la peau ou sur les anomalies des cellules inflammatoires caractéristiques de l’inflammation psoriasique. En fait, il semble maintenant nécessaire d’étudier les anomalies génétiques et les anomalies des voies de signalisation qui aboutissent à une sécrétion excessive de cytokines pro-inflammatoires, mais aussi de mieux comprendre les interactions entre cellules cutanées et cellules inflammatoires. Les progrès thérapeutiques récents, dans le traitement du psoriasis, reposent avant tout sur la mise en place de techniques permettant un meilleur ajustement des outils thérapeutiques aux besoins des patients. De fait, si le psoriasis met rarement la vie en danger, il atteint souvent gravement la qualité de la vie : l’objectif est donc d’élaborer une stratégie thérapeutique qui améliore cette qualité de vie, que seul le patient peut évaluer. Cette stratégie, permettant d’ajuster les possibilités thérapeutiques à chaque patient, repose sur quatre phases successives : le questionnement, qui permet d’évaluer la gravité de la maladie, les explications, qui permettent au malade de comprendre comment il peut agir sur sa maladie, la négociation, qui devient l’acte médical principal, et doit aboutir à une décision thérapeutique partagée. Il s’agit là d’une révolution, au sens propre, dans la relation entre le médecin et le malade : l’éducation du patient se situe au coeur de la démarche thérapeutique. C’est dans ce contexte que sont apparus de nouveaux médicaments, très intéressants sur le plan scientifique et apportant l’espoir d’une efficacité raisonnable, associée à une bonne tolérance. Ces médicaments sont toutefois très coûteux, ouvrant en cela le débat des possibilités et des limites de la solidarité.Psoriasis is a model disease in dermatology. It is a common disease that affects at least 2 to 3 % of the population. It is an illness characterized by an excessive reaction of the skin, in term of proinflammatory cytokines release, to no specific attacks: these attacks can be immunological, mechanical, metabolic, drug-induced or psychological. This excessive reaction is characterized by epidermal proliferation combined with incomplete terminal differentiation, as well as an inflammatory response responsible for the chronic nature of the lesions. The way to understand psoriasis is therefore to reach a better appreciation of the messages that enable the skin cells to initiate an inflammatory response, and by better understanding the way in which the inflammatory cells responsible for innate and acquired immune responses are capable of bringing about proliferation and abnormal epidermal differentiation. Taking an interest in psoriasis is therefore taking an interest in all facets of skin physiology and in all the ways the skin reacts to attacks from the environment. Every year for more than thirty years, more than 300 publications have endeavoured to explore one aspect or another of psoriasis from a clinical, epidemiological, physiopathological or therapeutic point of view. There is no new technique for observing the skin that has not been immediately applied to the study of psoriasis - which is privileged to enjoy the reflected progress made in dermatology. Nor has psoriasis remained untouched by whims of fashion, all manner of scenarios having been suggested to explain it, right from a scarring disease to an autoimmune illness through a genetic or psychosomatic disorder. Psoriasis is at the origin of a medical revolution mounted to supplement and enhance the effectiveness of evidence-based medicine ; it is the “patient-centred medicine”. Psoriasis only exceptionally jeopardizes life. Conversely, it is a disease that does affect quality of life. The patient alone must be the judge of his or her quality of life, and it is therefore up to the patient, not the doctor, to gauge the severity of psoriasis and hence decide on reasonable therapeutic indications. Psoriasis, then, cannot be treated without placing the patient, not the illness, at the centre of therapeutic negotiations. The 20th century has seen the disease targeted by boundless efforts ; the 21st century will see the development of medical techniques that allow the patient, in all its complexity, to be positioned at the centre of therapeutic efforts. This revolution began in dermatology, centring around psoriasis, and is spreading progressively to all chronic disorders and all disciplines. New quite interesting therapeutic weapons are available from a few months making possible to better adjust the therapeutic strategies of psoriasis to the patients needs but they are expensive opening again the debates on the limit of the social solidarity

Big data in health and other sectors : ethical questions

Summary and Recommendations on Big Data of the Ethics Commission of the Academy of Technologies of France. Originally published in French:Synthèse et recommendations, in Académie des Technologies, Big Data: Questions éthiques, Oct 2019, 9-20, available from:https://www.academie-technologies.fr/publications/big-data-questions-ethiques. Translation by the editors

Surface spin magnetism controls the polarized exciton emission from CdSe nanoplatelets

The surface of nominally diamagnetic colloidal CdSe nanoplatelets can demonstrate paramagnetism owing to the uncompensated spins of dangling bonds (DBSs). We reveal that by optical spectroscopy in high magnetic fields up to 15 Tesla using the exciton spin as probe of the surface magnetism. The strongly nonlinear magnetic field dependence of the circular polarization of the exciton emission is determined by the DBS and exciton spin polarization as well as by the spin-dependent recombination of dark excitons. The sign of the exciton-DBS exchange interaction can be adjusted by the nanoplatelet growth conditions

Molecular characterization of a human tyrosinase-related-protein-2 cDNA. Patterns of expression in melanocytic cells

Pigmentation in mammals is under complex genetic control. Amongst the genes involved in this process, those encoding tyrosinase and the tyrosinase‐related‐proteins 1 and 2 have been well characterized and share a number of features. Recently, the murine tyosinase‐related‐protein‐2 gene was shown to encode dopachrome‐tautomerase activity and was mapped to the slaty locus. Human tyrosinase and tyrosinase‐related‐protein‐1 genes have been isolated and demonstrate a high degree of similarity with their murine counterparts. However, there has been limited data regarding the existence of a human homologue for tyrosinase‐related‐protein‐2 and its relationship to the other tyrosinase‐related proteins. In this study, we report the molecular isolation of a cDNA encoding a human homologue of the murine tyrosinase‐related‐protein‐2/dopachrome tautomerase. We have characterized its expression in human melanocytic cells and have analyzed the relationship between dopachrome tautomerase and tyrosinase activities with the level of visible pigmentation in these cells. TYRP2 has been mapped to the chromosomal region 13q32, thus extending a region of synteny with mouse‐chromosome 14. Copyright © 1994, Wiley Blackwell. All rights reservedSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Electron and hole g-factors and spin dynamics of negatively charged excitons in CdSe/CdS colloidal nanoplatelets with thick shells

We address spin properties and spin dynamics of carriers and charged excitons in CdSe/CdS colloidal nanoplatelets with thick shells. Magneto-optical studies are performed by time-resolved and polarization-resolved photoluminescence, spin-flip Raman scattering and picosecond pump-probe Faraday rotation in magnetic fields up to 30 T. We show that at low temperatures the nanoplatelets are negatively charged so that their photoluminescence is dominated by radiative recombination of negatively charged excitons (trions). Electron g-factor of 1.68 is measured and heavy-hole g-factor varying with increasing magnetic field from -0.4 to -0.7 is evaluated. Hole g-factors for two-dimensional structures are calculated for various hole confining potentials for cubic- and wurtzite lattice in CdSe core. These calculations are extended for various quantum dots and nanoplatelets based on II-VI semiconductors. We developed a magneto-optical technique for the quantitative evaluation of the nanoplatelets orientation in ensemble

Addressing the exciton fine structure in colloidal nanocrystals: the case of CdSe nanoplatelets

We study the band-edge exciton fine structure and in particular its bright-dark splitting in colloidal semiconductor nanocrystals by four different optical methods based on fluorescence line narrowing and time-resolved measurements at various temperatures down to 2 K. We demonstrate that all these methods provide consistent splitting values and discuss their advances and limitations. Colloidal CdSe nanoplatelets with thicknesses of 3, 4 and 5 monolayers are chosen for experimental demonstrations. The bright-dark splitting of excitons varies from 3.2 to 6.0 meV and is inversely proportional to the nanoplatelet thickness. Good agreement between experimental and theoretically calculated size dependence of the bright-dark exciton slitting is achieved. The recombination rates of the bright and dark excitons and the bright to dark relaxation rate are measured by time-resolved techniques

Investigating the n- and p-Type Electrolytic Charging of Colloidal Nanoplatelets

We investigate the ion gel gating of 2D colloidal nanoplatelets. We propose a simple, versatile, and air-operable strategy to build electrolyte-gated transistors. We provide evidence that the charges are injected in the quantum states of the nanocrystals. The gating is made possible by the presence of large voids into the NPL films and is sensitive to the availability of the nanocrystals surface