La drépanocytose, ou anémie falciforme, présente une variabilité interindividuelle considérable, conditionnée par de multiples facteurs, dynamiques et interactifs, depuis le niveau moléculaire jusqu’au niveau du patient. L’hémoglobine drépanocytaire, ou hémoglobine S (HbS, tétramère a2bS 2), est un mutant de l’hémoglobine A (a2b2) : elle possède à sa surface une valine (hydrophobe) substituant un acide glutamique natif (négativement chargé). Cette mutation entraîne l’agrégation de l’HbS désoxygénée en polymères, ainsi que l’altération des propriétés de l’érythrocyte -dont sa rhéologie et ses interactions avec les différentes cellules vasculaires. C’est pourquoi la polymérisation de l’HbS constitue un facteur étiologique clef, sinon le primum movens, de la drépanocytose, et une hypothèse thérapeutique (étayée par l’observation) postule que la réduction des fibres intra-érythrocytaires de HbS pourrait améliorer le statut clinique des patients en abaissant la fréquence et la sévérité des crises vasoocclusives. Dans l’optique de mieux comprendre et de mieux gérer la variabilité individuelle drépanocytaire, il apparaît donc indispensable de disposer, en premier lieu, d’une description réaliste de la polymérisation de l’HbS. L’objectif de ce travail de thèse est la mise en place et la validation d’un modèle mathématique de la polymérisation de l’HbS désoxygénée, en tant que processus cinétiquethermodynamique, sous l’influence de la concentration et de la température –les deux facteurs modulateurs les plus importants. A partir d’un modèle existant, mais linéaire et incomplet (Ferrone et al., 1985), nous avons procédé à son implémentation, à sa correction et à sa mise à jour, ainsi qu’à l’évaluation quantitative de ses performances dynamiques, par intégration complète et simulation numérique (Simulink©). Ceci nous a permis de réaliser un diagnostic et d’effectuer un certain nombre de raffinements, concernant en particulier (i) la voie de nucléation hétérogène (formation de néo-fibres sur les fibres préexistantes), (ii) la non-idéalité de la solution protéique de HbS, induite par le volume exclus des fibres polymères (coefficients d’activité calculé à partir de la « théorie des particules convexes »), ainsi que (iii) la structuration spatiale des polymères en domaines. Le modèle développé dans ce travail servira de base pour une description (i) de l’influence dynamique de l’oxygénation et des hémoglobines non-polymérisantes sur la polymérisation de HbS, puis (ii) des polymères de HbS sur les propriétés membranaires et rhéologiques de l’érythrocyte drépanocytaire. / Sickle cell disease pathology exhibits a strong interindividual variability, which depends upon multiple, dynamic and interacting factors, from the molecular to the patient level. Sickle hemoglobin, hemoglobin S (HbS, a2bS 2 tetramer), is a mutant of HbA (a2b2), with a surface valine (hydrophobic) substituting a native glutamic acid (negatively charged). Such a mutation endows deoxygenated HbS with the propensity to agregate into polymers, altering erythrocyte properties –including its rheology and its interactions with vascular and circulatory cells. Thus HbS polymerization is a key etiological factor of sickle cell disease, if not the primum movens. Indeed, one therapeutical hypothesis (supported by observation) postulates that the reduction of intra-erythrocytic HbS fibers could improve patients clinical status by lowering the frequency and the severity of vasooclusive crisis. In order to better understand and manage sickle cell disease variability, it is essential to have a realistic description of HbS polymerization. This work aims at developing and validating a mathematical model of deoxygenated HbS polymerization, as a kinetic and thermodynamic process under the influence of concentration and temperature –the two most important modulators. Building on an existing, but linearized and uncomplete (Ferrone et al., 1985) model, we have implemented, corrected and updated, and quantitatively evaluated its dynamical performances: this was done by full numerical integration using Simulink©. This allowed us to make several improvements, related in particular to : (i) the heterogeneous nucleation pathway (seeding and formation of new fibers from pre-existing ones), (ii) the non-ideality of the HbS protein solution, caused by polymer fibers excluded volume (activity coefficients were calculated with the CPT, Convex Particle Theory), and (iii) the spatial organization of polymers into domains. The model developped in this work will ground the description of the dynamic influence (i) oxygenation and non-polymerizing hemoglobins, (ii) HbS polymers interactions with membrane and consequences upon rheological properties of sickle cell erythrocyte.

As doenças falciformes (DF) constituem um grupo de doenças hereditárias monogênicas. São doenças extremamente relevantes no contexto de saúde pública no Brasil, portanto diferentes estratégias terapêuticas devem ser avaliadas. As oclusões vasculares afetam praticamente todos os órgãos, inclusive o baço e a medula óssea, porém não existem dados na literatura se estas comprometem também o tecido tímico. Os pacientes apresentam maior suscetibilidade às infecções cujas causas não são ainda totalmente esclarecidas Embora as infecções observadas nos pacientes sejam atribuídas à disfunção esplênica, o quadro inflamatório crônico e possíveis alterações no timo e na medula óssea, também poderiam causar uma disfunção imunológica. O objetivo deste trabalho foi avaliar a neogênese de células T e B e a diversidade do repertório de células T periféricas em pacientes com anemia falciforme (AF) sem tratamento (N = 15), tratados com hidroxiuréia (N = 20) ou transfusão crônica (N = 21) e em pacientes com DF tratados com transplante de células-tronco hematopoéticas (TCTH) alogênico (N = 29). Pacientes sem tratamento apresentaram menores níveis de sjTREC e ?-TREC, e menor taxa de divisão celular intratímica, demonstrando alterações importantes na neogênese das células T. A produção tímica de novas células T naïve foi reestabelecida em um ano pós-transplante, com normalização dos níveis de sjTREC e ?-TREC. O desenvolvimento de doença do enxerto contra o hospedeiro (DECHa) e reativação de citomegalovírus comprometeu a timopoiese nos primeiros seis meses pós-transplante, com diminuição significativa dos níveis de sjTRECs e ?-TRECs. Análises do repertório da cadeia V? dos receptores de células T (TCRs), pelo método TCRBV CDR3 spectratyping, indicaram que os pacientes com AF apresentaram um repertório menos diverso, composto predominantemente de famílias V? com padrão skewed e picos de CDR3 monoclonais, sendo a família V?3 mais frequente. A composição do repertório de células T foi alterada após o transplante, adquirindo um perfil mais policlonal dos picos de CDR3 ao longo do tempo. A família V?22 foi a mais expressa no período pré-transplante e em todos os seguimentos pós-transplante. Os pacientes com DF apresentaram aumento de linfócitos B naive, demonstrado pelos altos níveis de sjKRECs e pela taxa de proliferação homeostática. As análises multivariadas demonstraram que as alterações esplênicas influenciam diretamente os níveis de sjKREC, indicando que a baixa função esplênica leva ao aumento da produção de células B naive pela medula óssea, sugerindo um mecanismo compensatório. Os resultados desse trabalho demonstraram a existência de um desequilíbrio na neogênese de células T e B e consequentemente nesses compartimentos celulares periféricos, que pode conferir aos pacientes com DF uma maior susceptibilidade a infecções. Entre as diferentes modalidades terapêuticas, o TCTH alogênico sobressaiu-se em relação aos tratamentos convencionais, melhorando a neogênese de células T e B a longo prazo. / Sickle Cell Disease (SCD) are a group of monogenic hereditary diseases. These are extremely relevant diseases in the context of public health in Brazil, thus, different therapeutic strategies must be studied. Vascular occlusions affect practically all organs, including the spleen and bone marrow. However, there are no literature data about the impact of vaso-occlusions on the thymic tissue. Patients are more susceptible to infections whose causes are not fully elucidated. Although the infections observed in these patients are assigned to splenic dysfunction, the chronic inflammatory state and possible alterations of the thymus and bone marrow could also lead to immune dysfunction. The goal of this work was to evaluate the neogenesis of T and B cells and the diversity of peripheral T cell repertoire in patients with sickle cell anemia (SCA) without treatment (N = 15), treated with hydroxyurea (N = 20) or chronic transfusions (N = 21) and in patients with SCD treated with hematopoietic stem cell transplantation (N = 29) allogeneic. Patients without treatment had lower levels of sjTREC and ?-TREC, and lower rate of intrathymic cell division, demonstrating important alterations in the neogenesis of T cells. The thymic production of new naïve T cells was reestablished at one-year post transplantation, with normalization of sjTREC and ?-TREC levels. The development of graft-versus-host disease (aGVHD) and cytomegalovirus activation compromised thymopoiesis in the first six months post transplantation, with a significant decrease of sjTRECs and ?-TRECs levels. Analysis of the TCR V? chain repertoire by TCRBV CDR3 spectratyping indicate that patients with SCA showed a less diverse repertoire, mainly composed by V? families with a skewed pattern and monoclonal CDR3 peaks, being the V?3 family the most frequent one. The composition of the T-cell repertoire was altered after transplantation, changing over time to more polyclonal profile of the CDR3 peaks. The V?22 family was the more expressed at pre-transplantation and at all follow-up periods. Patients with SCD presented increased numbers of naive B cells, demonstrated by higher levels of sjKRECs and homeostatic proliferation. Multivariate analysis demonstrated that splenic function directly influenced sjKREC levels, indicating that compromised splenic function leads to increase of naive B cell output by the bone marrow, suggesting a compensatory mechanism. The results of this study showed the existence of an imbalanced T and B cell neogenesis and, consequently on these peripheral cell compartments, which may confer to patients with SCD an increased susceptibility to infections. Among different therapeutic modalities, allogeneic HSCT stood out in relation to the conventional treatments, improving long-term T and B cell neogenesis.

Medicina da Universidade de São Paulo. Objetivo: Esse estudo foi desenvolvido para avaliar o impacto dos poluentes do ar na morbidade nas crianças e adolescentes portadoras de anemia falciforme. Métodos: Foram utilizadas as associações entre as concentrações diárias entre as concentrações dos poluentes do ar (PM10, SO2, NO2, CO, e O3) e os atendimentos no Pronto Socorro de anemia falciforme (CID 10 - D57) no período de setembro de 1999 até dezembro de 2004. Foi utilizado o desenho de case - crossover com dias de exposição de referencia escolhidos utilizando-se uma abordagem estratificada por tempo onde as exposições no dia índice foram comparadas a exposições com dias do mesmo mês com o mesmo valor de temperatura como o caso índice, controlando-se para o dia da semana. Estação do ano, clima e covariantes variáveis lentas foram controladas por pareamento. Também foram adotados modelos onde as exposições do caso índice foram comparadas às exposições para o mesmo dia da semana ou a cada três dias. Os efeitos estimados também foram estratificados para as duas causas principais de atendimento no pronto socorro de pacientes falciformes, dor e infecção respiratória. Resultados: As variações de interquartile aumentaram nas médias móveis de PM10 (25.9 mg/m3), NO2 (64.8 mg/m3), SO2 (8.1 mg/m3), CO (1.2 ppm), e O3 (57.23 mg/m3) foram associadas com aumento de 19.2% (95% CI: 11.2 - 27.8), 15.6% (95% CI: 6.3 - 25.8), 14.5% (95% CI: 6.6 - 23.0), 15,1% (95% CI: 7.7 -23.1), e 10% (95% CI: 1,3 - 18,6) nos atendimentos totais dos pacientes falciformes no pronto socorro, respectivamente. Na análise estratificada para dor, que é a manifestação cardinal dos processos de vaso-oclusão, os aumentos nos atendimentos dos pacientes falciformes com dor (23.1%, 95%CI: 11.0 - 36.5) devido a um aumento na variação interquartile da média móvel de 3 dias do PM10 foi 43% maior que nos pacientes falciformes sem dor. Conclusão: esse estudo mostra que o efeito da poluição do ar na saúde da população pediátrica não se restringe às doenças respiratórias. Também , entre os pacientes falciformes a manifestação principal dos efeitos adversos foi associada com o processo inflamatório dos vasos, reproduzindo resultados já observados entre pacientes adultos e idosos saudáveis e não saudáveis. Finalmente, esse estudo mostrou que os efeitos da poluição do ar na saúde ainda não esta definitivamente estimados e outros resultados serão observados em mais investigações. / Objective: This study was developed to assess the impact of air pollutants on sickle cell morbidity in children and adolescents. Methods we examined the associations between daily air pollutants concentrations (PM10, SO2, NO2, CO, and O3) and sickle cell (ICD10th revision: D57) emergency room visits, from September 1999 to December 2004. We applied a case-crossover design with referent exposure days chosen using the time-stratified approach such that exposures on the case day were compared to exposures on days of the same month with the same value of temperature as the case day, controlling for day of the week. Season, weather, and slowly varying covariates were controlled for by matching. We also adopted models where exposures on the case day were compared to exposures on the same day of the week or on every third day. Effects estimates were also stratified by the two main causes of sickle cell emergency room visits, pain and respiratory infections. Results: interquartile range increases of the 3-day moving averages of PM10 (25.9 mg/m3), NO2 (64.8 mg/m3), SO2 (8.1 mg/m3), CO (1.2 ppm), and O3 (57.23 mg/m3) were associated with increases of 19.2% (95% CI: 11.2 - 27.8), 15.6% (95% CI: 6.3 - 25.8), 14.5% (95% CI: 6.6 - 23.0), 15,1% (95% CI: 7.7 - 23.1), and 10% (95% CI: 1,3 - 18,6) in total sickle cell emergency room visits, respectively. When the analyses were stratified by pain, the main clinical manifestation of vase-occlusion process, increases in visits of sickle cell patients with pain (23.1%, 95%CI:11.0 -36.5) due to an interquartile range increase of the 3-day moving averages of PM10 were 43% higher than in sickle cell patients without pain. Conclusions: this study found that the effects of air pollutants on children\'s health are not limited to respiratory diseases. Also, among sickle cell patients, the main manifestation of adverse effect was associated with inflammatory process of vases, reproducing results already observed among healthy and non-healthy adults and elderly people. Finally, this study showed that the burden of air pollution on health has not been definitively estimated and other outcomes deserve further investigation.

La drépanocytose est une hémoglobinopathie génétique ayant pour conséquences une anémie hémolytique chronique et sévère et des crises vaso-occlusives itératives. Cette pathologie s’accompagne également d’une intolérance à l’effort et d’altérations de la fonction et du tissu musculaire. Récemment, nous avons pu montrer, par une étude contrôlée et randomisée, l’innocuité et les bénéfices fonctionnels d’un programme d’entrainement en endurance, d’intensité modérée, chez des patients drépanocytaires. L’objectif de ce travail doctoral a été d’évaluer les effets de ce programme d’entrainement sur les caractéristiques musculaires de quarante patients drépanocytaires homozygotes. L’analyse des biopsies musculaires rapporte des adaptations tissulaires chez les patients entrainés, illustrées par une augmentation de la surface des myocytes, une amélioration de leur capacité oxydative, une augmentation du nombre de microvaisseaux sans modification de leur tortuosité, laissant supposer une meilleure oxygénation musculaire. L’excellente tolérance de ce mode d’entrainement semble reposer sur une plus faible mobilisation des voies anaérobies comme en témoigne la stabilité des activités enzymatiques associées à la glycolyse lactique et l’absence de modification du contenu musculaire des protéines impliquées dans la régulation du pH. Par ailleurs, cet entrainement n’a pas engendré de dégradation tissulaire notable. Ainsi, cet entrainement a non seulement apporté des bénéfices fonctionnels, mais également réduit les dysfonctionnements tissulaires musculaires. Cette thérapie par l’exercice peut donc être considéré comme une stratégie adjuvante prometteuse pour les patients drépanocytaires. / Sickle cell disease is a genetic hemoglobinopathy resulting in chronic and severe hemolytic anemia and iterative vaso-occlusive crisis. This pathology is also accompanied by exercise intolerance and alterations in muscle function and tissue. Recently, we demonstrated, through a randomized controlled study, the safety and functional benefits of a moderate-intensity endurance exercise training program in sickle cell disease patients. The objective of this doctoral work was to evaluate the effects of this training program on the muscle characteristics of forty homozygous sickle cell disease patients. The analysis of muscle biopsies reported tissue adaptations in trained patients, illustrated by an increase in the surface area of myocytes, an improvement in their oxidative capacity, an increase in the number of microvessels without modification of their tortuosity, suggesting a better muscle oxygenation. The excellent tolerance of this training mode seems to be based on a lower mobilization of the anaerobic pathways, as shown by the stability of the enzymatic activities associated with lactic glycolysis and the lack of any modification of the muscle protein content involved in pH regulation. Moreover, this training did not result in any significant tissue degradation. Thus, this training provided functional benefits, but also reduced muscle tissue dysfunctions. This exercise therapy can therefore be considered a promising adjuvant strategy for sickle cell disease patients.

Medicina da Universidade de São Paulo. Objetivo: Esse estudo foi desenvolvido para avaliar o impacto dos poluentes do ar na morbidade nas crianças e adolescentes portadoras de anemia falciforme. Métodos: Foram utilizadas as associações entre as concentrações diárias entre as concentrações dos poluentes do ar (PM10, SO2, NO2, CO, e O3) e os atendimentos no Pronto Socorro de anemia falciforme (CID 10 - D57) no período de setembro de 1999 até dezembro de 2004. Foi utilizado o desenho de case - crossover com dias de exposição de referencia escolhidos utilizando-se uma abordagem estratificada por tempo onde as exposições no dia índice foram comparadas a exposições com dias do mesmo mês com o mesmo valor de temperatura como o caso índice, controlando-se para o dia da semana. Estação do ano, clima e covariantes variáveis lentas foram controladas por pareamento. Também foram adotados modelos onde as exposições do caso índice foram comparadas às exposições para o mesmo dia da semana ou a cada três dias. Os efeitos estimados também foram estratificados para as duas causas principais de atendimento no pronto socorro de pacientes falciformes, dor e infecção respiratória. Resultados: As variações de interquartile aumentaram nas médias móveis de PM10 (25.9 mg/m3), NO2 (64.8 mg/m3), SO2 (8.1 mg/m3), CO (1.2 ppm), e O3 (57.23 mg/m3) foram associadas com aumento de 19.2% (95% CI: 11.2 - 27.8), 15.6% (95% CI: 6.3 - 25.8), 14.5% (95% CI: 6.6 - 23.0), 15,1% (95% CI: 7.7 -23.1), e 10% (95% CI: 1,3 - 18,6) nos atendimentos totais dos pacientes falciformes no pronto socorro, respectivamente. Na análise estratificada para dor, que é a manifestação cardinal dos processos de vaso-oclusão, os aumentos nos atendimentos dos pacientes falciformes com dor (23.1%, 95%CI: 11.0 - 36.5) devido a um aumento na variação interquartile da média móvel de 3 dias do PM10 foi 43% maior que nos pacientes falciformes sem dor. Conclusão: esse estudo mostra que o efeito da poluição do ar na saúde da população pediátrica não se restringe às doenças respiratórias. Também , entre os pacientes falciformes a manifestação principal dos efeitos adversos foi associada com o processo inflamatório dos vasos, reproduzindo resultados já observados entre pacientes adultos e idosos saudáveis e não saudáveis. Finalmente, esse estudo mostrou que os efeitos da poluição do ar na saúde ainda não esta definitivamente estimados e outros resultados serão observados em mais investigações. / Objective: This study was developed to assess the impact of air pollutants on sickle cell morbidity in children and adolescents. Methods we examined the associations between daily air pollutants concentrations (PM10, SO2, NO2, CO, and O3) and sickle cell (ICD10th revision: D57) emergency room visits, from September 1999 to December 2004. We applied a case-crossover design with referent exposure days chosen using the time-stratified approach such that exposures on the case day were compared to exposures on days of the same month with the same value of temperature as the case day, controlling for day of the week. Season, weather, and slowly varying covariates were controlled for by matching. We also adopted models where exposures on the case day were compared to exposures on the same day of the week or on every third day. Effects estimates were also stratified by the two main causes of sickle cell emergency room visits, pain and respiratory infections. Results: interquartile range increases of the 3-day moving averages of PM10 (25.9 mg/m3), NO2 (64.8 mg/m3), SO2 (8.1 mg/m3), CO (1.2 ppm), and O3 (57.23 mg/m3) were associated with increases of 19.2% (95% CI: 11.2 - 27.8), 15.6% (95% CI: 6.3 - 25.8), 14.5% (95% CI: 6.6 - 23.0), 15,1% (95% CI: 7.7 - 23.1), and 10% (95% CI: 1,3 - 18,6) in total sickle cell emergency room visits, respectively. When the analyses were stratified by pain, the main clinical manifestation of vase-occlusion process, increases in visits of sickle cell patients with pain (23.1%, 95%CI:11.0 -36.5) due to an interquartile range increase of the 3-day moving averages of PM10 were 43% higher than in sickle cell patients without pain. Conclusions: this study found that the effects of air pollutants on children\'s health are not limited to respiratory diseases. Also, among sickle cell patients, the main manifestation of adverse effect was associated with inflammatory process of vases, reproducing results already observed among healthy and non-healthy adults and elderly people. Finally, this study showed that the burden of air pollution on health has not been definitively estimated and other outcomes deserve further investigation.

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Made available in DSpace on 2011-05-04T12:36:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2009 / A Política Nacional de Atenção Integral às Pessoas com Doença Falciforme e outras Hemoglobinopatias afirmou o compromisso público para a proteção àsaúde aos portadores destas doenças e a garantia dos direitos sociais dos pacientes a todos os níveis de assistência existentes no sistema público de saúde do Brasil, o Sistema Único de Saúde (SUS): níveis primário, secundário e terciário. No Estado do Rio de Janeiro propôs-se uma rede assistencial descentralizada para os municípios estruturada em unidades de atenção básica, que devem acompanhar e tratar os pacientes avaliados como de baixa complexidade e inseri-los nas atividades deste nível de atenção, que abrangem a promoção, proteção e manutenção da saúde, a prevenção deagravos, o diagnóstico, o tratamento e a reabilitação, através de ações nas esferas individual e coletiva. Procuramos avaliar a Política de Atenção Integral à Pessoa com Doença Falciforme no Estado do Rio de Janeiro com foco na descentralização dos pacientes diagnosticados pela triagem neonatal. Analisamos documentos disponíveis, como cadastros, portarias e resoluções do SUS referentes à doença falciforme e aplicamos questionário de avaliação em 27 médicos participantes da implementação da política. As fragilidades encontradas nos ambulatórios de doença falciforme e no sistema de saúde fazem com que neles se reproduza o modelo médico hegemônico, centrado na consulta médica. As dificuldades de articulação das unidades básicas com os níveis intermediários de atenção e o marcante papel desempenhado pelo Hemorio (hemocentro do Estado do Rio de Janeiro) como coordenador da Hemorrede e prestador de assistência na alta complexidade faz com que se invertam os papéis e que uma unidade terciária seja o nível onde se estabeleçaa linha de cuidado de pacientes com doença falciforme. / The Brazilian National Policy for Comprehensive Care of Persons with Sickle Cell Disease and Other Hemoglobinopathies is committed to providing the population afflicted with these diseases with medical assistence in different levels according to their needs. The State of Rio de Janeiro has established a decentralized network for such population based on municipal units of health care that are responsible for the identification, the basic treatment and the follow-up of patients classified in "low complexity" category. These units are also responsible for providing the patients and/or their families with the health education necessary at this level. This study attempts at evaluating the aforementioned policy in the State of Rio de Janeiro focusing on the health care, in these basic units, of patients diagnosed by neonatal screening according to what has been established in the documents of the Brazilian Unified Health System (Sistema Único de Saúde - SUS). A questionnary was developed and applied to 27 doctors who are implementing this policy at the local level, and the results indicate that structural problems in these units and in the health system make them tend to reproduce the traditional health care model based almost exclusively on medical care. Furthermore, there is poor articulation between the basic and the intermediary levels. The Hemorio, as coordinator of the network of hematology, and responsible for high complexity assistance of patients with such diseases is overwhelmed with work that should be done at the basic level.

La drépanocytose est la maladie moléculaire et héréditaire (transmission mendélienne récessive et autosomique) la plus répandue au monde. Elle est un problème de santé publique par sa gravité et ses implications socio-économiques dans de nombreux pays. Seuls les sujets homozygotes (SS) ou hétérozygotes composites (SC) sont malades, les hétérozygotes (AS) ne sont que des transmetteurs du gène S. Elle est la première cause d’OstéoNécrose de la Tête Fémorale (ONTF), douloureuse évoluant vers l’arthrose, en l’absence de traitement chez un patient jeune.<p>La Guadeloupe compte 450.000 habitants, dont 12% sont porteurs de l’hémoglobine S. Le nombre des drépanocytaires est estimé à 1.200 dont les 3/4 sont suivis au Centre Caribéen de la Drépanocytose (CCD), créé en 1990. Le centre assure la prise en charge médicale des enfants dès leur naissance et des adultes malades. Nos activités au CHU de Pointe-à-Pitre, au CCD et à l’Unité INSERM-UMR S458 depuis juillet 1992 nous ont permis d’étudier:<p>- le diagnostic de l’ONTF;<p>- l’évaluation de l’hyperpression osseuse dans l’ONTF et l’évaluation du traitement par forage simple;<p>- l’étude de l’impact de la prise en charge orthopédique précoce sur la survenue et l’évolution de l’ONTF.<p>Notre étude concerne les patients drépanocytaires adultes homozygotes (SS) et double hétérozygotes (SC):<p>- une série rétrospective de 1993-1994 [E-1994] portant sur 115 patients (58 SS, 57 SC) identifiés en 1984,<p>sans suivi médical ni orthopédique;<p>- une série prospective de 1995 à 2008 [E-2008] portant sur 215 patients (94 SS, 121 SC) avec prise en<p>charge médicale et orthopédique.<p>L’IRM est l’examen de référence pour le diagnostic de l’ONTF comme dans la nécrose idiopathique. En absence d’imagerie moderne, la radiographie traditionnelle réalisée de façon complète (profil et, surtout, faux profil), permet le diagnostic avant toute déformation. Seules les lésions cliniquement symptomatiques et évolutives (examen clinique itératif, contrôle radiologique, tomographie, TDM ou IRM) ont une indication opératoire.<p>L’hyperpression intra osseuse, dans l’ONTF drépanocytaire, est significativement liée à la douleur (que les patients soient homozygotes ou hétérozygotes). Sa diminution a un effet antalgique objectif, observée après forage. Elle permet de confirmer le diagnostic d’ostéonécrose au stade précoce, dans les régions où l’IRM est inexistante.<p>Un forage réalisé aux stades précoces de l’ONTF permet un arrêt rapide de l’évolution des lésions vers une arthrose, avec une efficacité certaine pour les stades I et II. Il garde une efficacité limitée pour le stade III. En plus de l’indolence apportée par la décompression, le bénéfice du forage se manifeste par l’allongement du délai avant arthroplastie (de 7,4 ± 2,7 ans). La technique est réalisable dans les régions sous équipées, où la drépanocytose est fréquente.<p>La description histologique aux différents stades radiologiques de l’ONTF montre toujours des lésions de nécrose médullaire et osseuse. A l’inverse des lésions idiopathiques, les lésions drépanocytaires sont caractérisées par la présence d’une inflammation, en dehors de tout processus infectieux.<p>Dans la littérature, la fréquente de l’ONTF drépanocytaire chez l’adulte est voisine de 40%, proche de celle observée dans [E-1994], notre population non suivie (36,5%). En comparant les études [E-1994] et [E-2008], la fréquence de l’ONTF passe de 36,5% à 14,4%. L’officialisation en 1992 d’une prise en charge médicale et d’un suivi orthopédique régulier au CCD et au CHU de Pointe-à-Pitre, a permis la réduction de la fréquence de l’ONTF et d’autres morbidités.<p>Le rappel sur la drépanocytose révèle la complexité de la maladie, la variabilité de son expression clinique et de ses complications. L’amélioration de vie des patients nécessite une prévention primaire, secondaire et tertiaire, en l’absence d’un traitement spécifique de la maladie.<p>La prise en charge médicale, complétée par une prévention et un traitement précoce (orthopédique ou chirurgical) telle que réalisés au CCD en Guadeloupe, a permis une réduction significative de la survenue de la nécrose de hanche et de ses complications. Pour une prévention tertiaire des complications ostéo-articulaires, nous suggérons:<p>- une prise en charge médicale régulière des enfants et des adultes afin de réduire les crises vaso-occlusives;<p>- une éducation des patients à la recherche de signes d’appel de l'ONTF et, aussi, d’autres articulations;<p>- un examen clinique ostéo-articulaire lors des bilans annuels et après toute crise vaso-occlusive;<p>- une attention particulière à l’adolescence (passage enfant-adulte), après une grossesse;<p>- une prise en charge précoce, orthopédique ou chirurgicale conservatrice (forage ou ostéotomie) face à une<p>nécrose, afin de réduire les complications invalidantes de l’ONTF.<p><p>Sickle-cell anemia is the most widespread hereditary (autosomal recessive Mendelian transmission) molecular pathology in the world. It is a public health issue in many countries, due to its severity and socio-economic impact. Only homozygous (SS) and double heterozygous (SC) subjects are affected, heterozygous (AS) subjects merely transmitting the gene S. Sickle-cell anemia is the most frequent cause of osteonecrosis of the femoral head (ONFH), a painful condition which evolves towards osteoarthritis if not treated at an early age.<p>Guadeloupe has a population of 450,000, 12% of whom are carriers of hemoglobin S. There are estimated to be 1,200 sickle-cell anemia sufferers, three-quarters of whom are followed in the Caribbean Sickle-Cell Center (Centre Caribéen de la Drépanocytose: CCD), which was set up in 1990. The Center provides medical care for adult patients and for children as of birth. Work has been ongoing since July 1992, in the Pointe-à-Pitre University Hospital, the CCD and the INSERM-UMR S458 research unit, focusing on:<p>- diagnosis of ONFH;<p>- bone hyperpressure measurement in ONFH and assessment of simple drilling treatment;<p>- the impact of early orthopedic treatment on the onset and evolution of ONFH.<p>The present study involved homozygous (SS) and double heterozygous (SC) adult sickle-cell anemia patients:<p>- a retrospective series, from 1993 to 1994 [S-1994], including 115 patients (58 SS, 57 SC) identified in 1984,<p>who had no medical or orthopedic care;<p>- a prospective series, from 1995 to 2008 [S-2008], including 215 patients (94 SS, 121 SC), with medical and orthopedic care.<p>MRI is the diagnostic gold-standard in ONFH, as in idiopathic necrosis. Where such modern imaging is not available, complete standard X-ray (lateral and especially false lateral) enables diagnosis to be made before deformity sets in. Surgery is indicated only for clinically symptomatic evolutive lesions on iterative clinical check-up, X-ray control, tomography, CT or MRI.<p>Intraosseous hyperpressure in sickle-cell ONFH shows a significant correlation with pain, in both homozygous and heterozygous patients. Pressure reduction is objectively pain-relieving, as seen after drilling, and can confirm diagnosis of ONFH at an early stage, in places where MRI is not available.<p>Drilling performed in the early stages of ONFH quickly arrests evolution towards osteoarthritis, with proven efficacy in grades I and II, and a certain degree of effectiveness in grade III. Over and above the pain-relief provided by decompression, drilling also enables hip replacement to be postponed, by 7.4±2.7 years. Moreover, the technique is feasible in those under-equipped regions in which sickle-cell disease is widespread.<p>Histologic description of radiologic ONFH stages consistently finds medullary and bone necrosis. In contrast to idiopathic lesions, sickle-cell related lesions show inflammation without any associated infection.<p>In the literature, the frequency of adult sickle-cell ONFH is reported to be nearly 40%, close to the 36.5% found in the S-1994 study of a non-treated population. In the S-2008 study of a population with medical and orthopedic care, ONFH frequency fell to 14.4%. The official provision of medical care and regular orthopedic follow-up in the CCD and Pointe-à-Pitre Hospital has reduced the frequency of ONFH and other morbidities.<p>A review of sickle-cell disease reveals its complexity: the variability of its clinical expression and associated complications. Improving patients’ quality of life requires primary, secondary and tertiary prevention, in the absence of specific treatment.<p>Medical care, supplemented by early prevention and treatment (orthopedic or surgical), as practiced in the Guadeloupe CCD, has significantly reduced the rates of ONFH and associated complications. We recommend the following CCD protocol for tertiary prevention of osteoarticular complications:<p>- regular medical care for children and adults, to reduce the incidence of vaso-occlusive crises;<p>- patient education in alarm signs of osteonecrosis of the femoral head and of other joints;<p>- systematic osteoarticular assessment at yearly check-up and after all vaso-occlusive crises;<p>- special focus on adolescence (child-to-adult transition) and following pregnancy;<p>- early care, both orthopedic and by conservative surgery (drilling or osteotomy), in case of necrosis, to reduce the rate of disabling complications of ONFH / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

L'atteinte vasculaire cérébrale est une complication grave et fréquente chez les enfants drépanocytaires, car elle impacte leur pronostic, en termes de morbidité (handicap) et de mortalité. L’accélération des vitesses mesurées par le doppler transcrânien (DTC) est prédictive du risque d'infarctus cérébral et implique une modification de la prise en charge thérapeutique. Chez l’enfant drépanocytaire, l'infarctus cérébral est d'origine multifactorielle, lié à la vasculopathie cérébrale sténotique ainsi qu'à une hypercoagulabilité et une activation cellulaire. Nous avons étudié de manière prospective l'association de marqueurs biologiques au DTC chez 108 enfants porteurs de syndrome drépanocytaire majeur et recherché des éléments prédictifs d'événement vasculaire périphérique ou cérébral. Nous avons ainsi réalisé une analyse approfondie de la fonction endothéliale, de l’activation de l’hémostase primaire et de la coagulation, de l'activation cellulaire et de la mécanique artérielle. L’atteinte vasculaire cérébrale a été estimée en considérant les données du DTC comme une variable continue plutôt que catégorielle. Le principal résultat est le rôle prédictif du nombre des cellules souches hématopoïétiques CD34+ pour la survenue d'événements cliniques vasculaires. Nous avons également mis en évidence un profil particulier de coagulation chez les enfants drépanocytaires présentant des céphalées récurrentes ou des accès migraineux. Ceci supporte l'hypothèse que les céphalées chez l'enfant drépanocytaire, et notamment celles répondant aux critères de la migraine, peuvent être le reflet d'événements ischémiques cérébraux ultra-transitoires. Elles représentent donc peut-être un indicateur indirect de risque ischémique cérébral. Nous avons par ailleurs montré que le risque hémorragique cérébral chez les enfants drépanocytaires restait proportionnellement stable par rapport au risque ischémique, malgré l'utilisation en routine de stratégies de prévention du risque ischémique. L'observation de lésions sténotiques et d'anévrismes permet de supposer que ces atteintes vasculaires cérébrales procèdent de mécanismes physiopathologiques communs. L'amélioration de la compréhension des mécanismes physiopathologiques des complications neurovasculaires et la mise en évidence de facteurs prédictifs d'événements cliniques est un pas supplémentaire vers l'amélioration de la sensibilité diagnostique de la vasculopathie cérébrale drépanocytaire, de la compréhension des mécanismes des accidents vasculaires cérébraux de ces enfants et probablement de leur pronostic neurologique en permettant une prise en charge thérapeutique adaptée plus précoce. / Cerbrovascular involvement is frequent in children with sickle-cell disease (SCD). It is severe in terms of morbidity (handicap) and mortality. Accelerated intracranial arterial blood flow velocity measured by transcranial doppler (TCD) is predictive for stroke occurrence and leads to therapeutic modifications. In SCD children, ischemic stroke results from stenotic cerebral vasculopathy associated with hypercoagulability, and cell activation. We prospectively addressed associations between biological markers and TCD velocity in 108 children with sickle-cell anemia (HbSS or HbSβ°) and looked for predictive factors for vascular peripheral or cerebral events. We performed extensive work-up of endothelial function, coagulation activation, cell activation, and arterial wall mechanics. Cerebral vasculopathy was defined using TCD velocity (continuous data) rather than the classical category classification. The main result is the demonstration of the role of hematopoietic stem cell CD34+ for the prediction of clinical vascular event occurrence. We also demonstrated an imbalanced coagulation profile in SCD children with recurrent cephalalgia or migraine. This finding supports the hypothesis that recurrent cephalalgia, especially migraine, could be a symptom of ultra-transient ischemic cerebrovascular events in SCD children. Therefore, this symptom may also indicate increased cerebrovascular ischemic risk. We demonstrated that the ratio cerebral hemorrhagic risk / cerebral ischemic risk in SCD children remains stable, despite the routine use of strategies aiming at reducing ischemic stroke risk. The concurrent observation of intracranial arterial stenotic lesions and aneurysm suggests common pathophyiological mechanisms. Improving pathophysiological understanding of cerebrovascular complications and demonstrating predictive risk factors for clinical events may help clinicians to improve early diagnosis of SCD-associated cerebral vasculopathy, to better understand stroke mechanism in this population, and probably to improve neurological outcome with earlier and more adapted management