Nous avons étudié les marqueurs hémorhéologiques, hématologiques et biochimiques chez des sujets drépanocytaires homozygotes SS (HbS/HbS) et hétérozygotes composites SC (HbS/HbC) dans deux cohortes, pédiatriques et adultes, de patients drépanocytaires, et ce, à travers 7 complications récurrentes de la drépanocytose : 2 appartenant au profil hémolytique (l’ulcère de jambes et la glomérulopathie) et 5 appartenant au phénotype visqueux/vaso-occlusif (l’hypertension artérielle, le syndrome thoracique aigu (STA), la crise vaso-occlusive (CVO), la rétinopathie et l’ostéonécrose). Nous avons montré que : 1) une viscosité sanguine et une déformabilité érythrocytaire élevées sont des facteurs de risques de CVO chez les enfants homozygotes ; 2) Une viscosité sanguine élevée est associée à une hypertension artérielle systémique relative chez des adultes SS ; 3) les enfants SC présente une fonction vasculaire mieux préservée que les enfants SS pour faire face à une augmentation de la viscosité sanguine ; 4) les patients adultes SS avec une ostéonécrose présentent une déformabilité érythrocytaire plus élevée que les patients sans ostéonécrose ; 5) une viscosité sanguine élevée est associée à la présence d’une rétinopathie chez les adultes SC mais pas chez les SS ; 6) les patients adultes SS présentant une glomérulopathie ont un taux d’hémolyse élevé, une déformabilité érythrocytaire réduite et des agrégats érythrocytaires très robustes ; 7) les patients adultes SS avec des ulcères de jambes récurrents ont un taux d’hémolyse accru et une déformabilité érythrocytaire réduite. De plus, nos travaux confirment que l’-thalassémie module les propriétés de déformabilité érythrocytaire, mais montrent pour la première fois qu’elle module aussi les propriétés d’agrégation érythrocytaire, et notamment la force des agrégats érythrocytaires. En conclusion, ces travaux permettent de préciser le rôle de la rhéologie sanguine dans un certain nombre de complications de la drépanocytose et d’enrichir le modèle préexistant divisant les complications de la drépanocytose selon 2 phénotypes : hémolytique versus visqueux/vaso-occlusif. Nous montrons pour la première fois que le phénotype hémolytique est caractérisé aussi par des anomalies de la rhéologie du globule rouge : rigidité accrue et agrégats érythrocytaire robustes. / Hemorheological, hemathological, and biochemical marquers of patients with sickle cell anemia (SS) and patients with sickle cell SC disease (SC) were studied in 2 cohorts: children and adults. We focused on 7 recurrent complications: 5 belonging to the viscosity/vaso-occlusion phenotype (systemic hypertension, acute chest syndrome (ACS), vaso-occlusive crisis (VOC), retinopathy and osteonecrosis) and 2 belonging to the hemolytic phenotype (leg ulcer and glomerulopathy). Our results show that 1) high viscosity is associated with increased risk for VOC in SS children; 2) blood viscosity is increased in SS adults with systemic relative hypertension; 3) SC children have preserved vascular function compared to SS children; 4) SS adults with osteonecrosis are characterized by higher red blood cell (RBC) deformability than SS adults without osteonecrosis; 5) high blood viscosity is associated with retinopathy in SC adults but not in SS adults; 6) SS adults affected by glomerulopathy have high hemolytic rate, low RBC deformability and increased RBC aggregates strenght; 7) SS adults with recurrent leg ulcers have high hemolytic rate and reduced RBC deformability. Moreover, our studies shows that alpha-thalassemia modulate RBC deformability and RBC aggregation properties. In conclusion, this work shows for the first time that the hemolytic phenotype is characterized by an abnormal RBC rheology which may play a role in several sickle cell complications.

Cette thèse cherche à optimiser l’utilisation du génotypage et des scores de gravité dans la drépanocytose. L’aspect diagnostic génétique ne nous semblait pas poser problème jusqu’à ce que nous rencontrions un cas très atypique d’hétérozygotie A/S avec délétion en mosaïque du gène β-globine qui nous a conduits à réfléchir sur une nouvelle forme génétique potentielle de syndrome drépanocytaire majeur. Pour ce qui est des gènes modificateurs de drépanocytose, nous avons voulu faciliter leur l’accès en proposant, pour deux d’entre eux (haplotypes β-globine et G6PD), une méthode de génotypage rapide par HRM et/ou FRET. Notre travail a consisté ensuite en la validation d’un score de sévérité pédiatrique décrit initialement par Van den Tweel. De façon inattendue, les résultats nous ont amenés à nous interroger sur le rôle exact du génotype α-globine dans la drépanocytose avec un possible effet âge-dépendant. Enfin, nous avons étudié les fréquences alléliques des principaux polymorphismes influant sur l’activité des opiacés: une résistance pharmacologique (gènes OPRM1 et COMT) est apparue peu probable mais une proportion non négligeable de drépanocytaires pourrait avoir des génotypes ABCB1 et UGT2B7 défavorables à la biodisponibilité des opiacés / This work is submitted for a PhD thesis in the field of red cell haematology. Sickle cell disease (SCD) is a monogenic disorder under polygenic and environmental control. The aim of this work was to integrate genotyping results from patients' DNA into the determination of the disease severity scores. Through a large population of SCD patients, we have discovered an atypical case of βA / βS heterozygosity namely, a mosaicism deletion of the beta-globin gene. This represents a new SCD complex situation for molecular diagnosis. Further investigations have led to set up a new genotyping method by using HRM and/or FRET for the determination of two SCD modifiers (beta-globin haplotypes and G6PD deficiency). By using a paediatric severity score of the disease proposed by Van den Tweel, our results show that there is a possible age-dependent effect of the alpha-globin gene in the severity of SCD. Finally, we studied the allelic frequencies of the main opiate-related polymorphisms: a pharmacological resistance (OPRM1 and COMT genes) seemed unlikely but a quite important proportion of patients could have both an ABCB1 and a UGT2B7 genotype unfavorable for opiates bioavailability

La drépanocytose est une hémoglobinopathie essentiellement connue pour ses répercussions hématologiques, hémodynamiques et vasculaires chez les patients homozygotes (SCA). Bien que ces sujets présentent une intolérance à l'effort, la littérature est très pauvre concernant les répercussions musculaires de la maladie. Ce travail doctoral nous a permis de caractériser pour la première fois les répercussions structurales, énergétiques et microvasculaires du muscle d’hommes (étude 1) et de femmes (étude 2) drépanocytaires par rapport à des sujets SCT et contrôles (CON). Nos analyses histologiques et biochimiques ont mis en évidence chez les sujets SCA masculins une amyotrophie qui explique au moins en partie la diminution de l’IMC des SCA au dépend de la masse maigre. Nous avons également observé l’altération de plusieurs indices du métabolisme oxydatif (CS, β-HAD et COx) qui pourrait relever de la restriction d’approvisionnement et d’utilisation tissulaire en O2 et expliquer en partie l’intolérance à l’effort. Enfin, un remodelage microvasculaire caractérisé par une raréfaction, une moindre tortuosité et une fragilisation des microvaisseaux a également été démontré. Ce remodelage microvasculaire pourrait contribuer à limiter le risque d’enclavement des hématies falciformées et ainsi réduire les risques de vaso-occlusions. La recherche de ces différents stigmates dans le muscle de la population féminine homologue a rapporté un remodelage musculaire similaire à celui observé chez les hommes SCA, mais ce dernier semble atténué, suggérant un effet genre / Sickle cell anemia (SCA) is a hemoglobinopathy particularly known for its hematologic, hemodynamics and vascular repercussions. Although SCA patients are exercise intolerant, no studies have looked at muscle repercussions. We assessed repercussions of sickle cell anemia on skeletal muscle and its microvasculature in men (study 1) and women (study 2) for the first time. Our results showed that men with SCA displayed an amyotrophy which can at least partly explain the decrease of BMI at the expense of lean muscle mass. We also pointed out a decrease in muscle oxidative capacities (CS, β-HAD and COx) which could result from O2 supply and utilization disorders and partly explain their exercise intolerance. Finally, a microvascular remodeling characterized by a rarefaction, a decrease in microvessel tortuosity and a microvessel weakening was also highlighted. This remodeling could contribute to maintain local blood flow and reduce risks of entrapment of sickle red blood cells in the microvasculature, hence reducing vaso-occlusive risks. Muscle repercussions on a similar female population testified of the same muscle remodeling as the one observed in men with SCA, but this latter seemed to happen at a lesser extent in women with SCA, suggesting a gender effect

Hemoglobinopathies are genetic alterations of high population frequency. Neonatal screening identified both homozygous cases (patients) and heterozygotes (sound carriers). This study aims to identify the spatial distribution of the HbS carriers (SCT) in Sergipe from universal newborn screening and evaluate knowledge about hemoglobinopathies in heterozygous families for genetic counseling performed in the delivery of the results of neonatal screening. The sample consisted of all individuals born in Sergipe, from October 2011 to October 2012, that have been submitted to neonatal screening by the National Health System. Tests were carried out in basic health units and forwarded to the University Hospital Lab where they were analyzed. The relatives of patients with SCT were called to attend the meeting where the delivery of the examination was made, and answered the questionnaire on knowledge of sickle cell disease and trait, before and after orientation. Analysis of the spatial distribution of individuals heterozygous for hemoglobinopathies was performed using spatial autocorrelation (Moran index). To evaluate the number of total hits questionnaire before and after we used the Wilcoxon test and each question was performed McNemar test. Among the 32,906 examinations, 1,202 showed abnormalities standard hemoglobin. There was a positive correlation with the percentage of blacks and mulattos county and the incidence of SCT and a negative correlation with the percentage of blacks in the cities. In heterozygous distribution analysis of the state of Sergipe conducted by autocorrelation were identifying three regions in the state more frequently to HbS. Of the 1,202 individuals identified with SCT only 290 families attended the genetic counseling. The knowledge of the study population regarding hemoglobinopathies are limited. Even though the need for neonatal screening, the majority of respondents is unaware of what the diseases surveyed by examination. However, they managed to assimilate information with the strategy used. / As hemoglobinopatias são alterações genéticas de alta frequência populacional. Com a triagem neonatal identificamos tanto os casos homozigotos (doentes), quanto os heterozigotos (portador sadio). O presente estudo tem como objetivo identificar a distribuição espacial da presença do portador de Hemoglobina S (HbS) em Sergipe a partir da triagem neonatal universal e avaliar o conhecimento a respeito das hemoglobinopatias, nos familiares dos lactentes heterozigotos identificados na triagem neonatal durante orientação genética realizada na entrega dos resultados do exame. A amostra estudada constituiu-se de todos os indivíduos nascidos em Sergipe, de outubro de 2011 a outubro de 2012, e que tenham sido submetidos à triagem neonatal pelo Sistema Único de Saúde. A coleta dos exames foi realizada nas unidades básicas de saúde e encaminhadas ao Laboratório do Hospital Universitário onde foram analisadas. Os familiares de pacientes com traço falciforme (TF) eram convocados a participar de uma reunião, onde foi realizada a entrega do exame, e aplicado questionário sobre o conhecimento da doença e TF antes e após a orientação. A análise da distribuição espacial dos indivíduos heterozigotos para HbS foi realizada através autocorrelação espacial (Índice de Moran). Para avaliação do conhecimento sobre as hemoglobinopatias, o número de acertos total do questionário antes e após foi utilizado o teste de Wilcoxon e cada questão foi realizado o teste de Mc Nemar. Dentre os 32.906 exames realizados, 1.202 apresentaram alguma alteração do padrão da hemoglobina. Observou-se correlação positiva entre o percentual de negros e pardos dos municípios e a incidência de TF, mas correlação negativa quando apenas o percentual de negros era considerado. Na análise da distribuição de heterozigotos no estado de Sergipe, realizada pela autocorrelação foram identificadas 3 regiões no estado com maior frequência da HbS. Dos 1.202 indivíduos identificados com TF apenas 290 familiares compareceram à orientação genética. O conhecimento da população estudada a respeito das hemoglobinopatias foi limitado. Mesmo sabendo da necessidade de realização da triagem neonatal, grande parte dos entrevistados desconhece quais são as doenças pesquisadas pelo exame. Entretanto, conseguiram assimilar informações com a estratégia utilizada.

As Anemias Hemolíticas compreendem um grupo de doenças em que há redução acentuada na sobrevivência dos glóbulos vermelhos circulantes e a medula óssea não é capaz de compensação, mesmo aumentando sua produção, o que causa anemia desde os primeiros anos da vida da pessoa. Dentre as doenças deste grupo, a Anemia Falciforme (SCA) e a Esferocitose Hereditária (HS) destacam-se por se tratarem de enfermidades com defeitos genéticos intrínsecos das células vermelhas (RBCs) que geram complicações multissistêmicas agudas e crônicas em seus portadores. Por vias patofisiológicas distintas, reticulócitos e respectivas hemácias defeituosas de tais doenças, falciformes e esferócitos, são continuamente aprisionados e fagocitados no baço, importante órgão de destruição de células velhas e/ou defeituosas via hemólise extravascular, o que leva progressivamente à disfunção e eventual perda da função esplênica. O objetivo desse trabalho é avaliar o papel do baço em relação à habilidade e ao fenótipo adesivos de reticulócitos (ret) e eritrócitos (erit) em pacientes com SCA e HS, com e sem função esplênica preservada. Amostras de sangue de 37 pacientes (22 SCA and 15 HS) com função esplênica e 19 pacientes (13 SCA e 6 HS) sem ela foram avaliadas. Ainda, sangue de 22 crianças com SCA foi coletado em estudo longitudinal dos 6 e 29 meses de vida. Todas as amostras de sangue foram analisadas quanto à função esplênica (Contagem de células PIT e de corpúsculos de Howell-Jolly - HJB), quanto ao perfil imunofenotípico celular (em % e em média de intensidade de fluorescência - MFI) e quanto à habilidade de adesão das células vermelhas à laminina e à linhagem celular endotelial HMEC-1. A análise da transição da perda de função esplênica demonstrou que a mesma se intensificou a partir dos 3 anos de idade (PIT: r=0,8; p<0,0001; HJB: r=0,7; p<0.0001). Quanto à imunofenotipagem celular, a contagem PIT se correlacionou positivamente, principalmente com os marcadores CD147 (%ret: r=0,6; p<0,0001; MFIret: r=0,6; p<0,0001; %erit: r=0,7; p<0,0001; MFIerit: r=0,6; p<0,0001), LuBCAM (%ret: r=0,5; p=0,004; MFIret: r=0,6; p<0,0001; %erit: r=0,6; p<0,0003; MFIerit: r=0,4; p<0,004) and CD58 (%ret: r=0,4; p=0,006; MFIret: r=0,5; p<0,0013; %erit: r=0,4; p<0,009; MFIerit: r=0,6; p<0,0001). Na comparação entre ausência ou presença do baço, a perda de sua função exerceu influência no aumento da expressão de adesão de RBCs em SCA, principalmente CD147 (%ret: p=0,002; MFIret: p=0,003; %erit: p<0,0001; MFIerit: p=0,005), LuBCAM (%ret: p=0,0001; MFIret: p<0,0001; %erit: p<0,0001; MFIerit: p<0,0001) e CD58 (%ret: p=0,007; MFIret: p=0,006; %erit: p=0,003; MFIerit: p=0,0004), embora a adesão celular tenha diminuído em pacientes HS esplenectomizados. Na comparação entre as doenças, pacientes HS com o baço apresentaram maior freqüência de adesão celular em relação aos SCA, notavelmente em relação ao LuBCAM (%ret: p=0,0008; MFIret: p=0,03; %erit: p<0,0001; MFIerit: p=0,0002), CD58 (%ret: p=0,0009; %erit: p=0,003) e CD44 (%ret: p=0,009; %erit: p<0,003). No entanto, as amostras SCA sem função esplênica tiveram maior expressão de adesão celular para CD147 (%ret: p=0,006; MFIret: p=0,02; %erit: p=0,02), LuBCAM (%ret: p=0,004; MFIret: p<0,0001), CD36 (%ret: p=0,0002; MFIret: p=0,01), CD242 (%ret: p=0,0008; %erit: p=0,05) e CD49d (%ret: p=0,04). Em relação ao Ensaio de Adesão in vitro, na ausência de baço, os RBCs SCA apresentaram maior adesividade à laminina do que os RBCs SCA com função esplênica preservadaem todas as taxas de fluxo de tensão de cisalhamento empregadas (0,5 dyne/cm2: p=0,01; 1 dyne/cm2: p=0,02; 2 dynes/cm2: p=0,03; 3 dynes/cm2: p=0,03; 5 dynes/cm2: p=0,04 e 7 dynes/cm2: p=0,03). Especialmente, reticulócitos de pacientes sem baço apresentaram maior adesividade à HMEC-1 em baixas tensões de cisalhamento (1 dyne/cm2) em ambas as doenças (SCA: p=0,03; HS: p=0,03). Por fim, reticulócitos apresentaram maior habilidade adesiva à células endoteliais em indivíduos SCA do que em pacientes HS, com (0,5 dyne/cm2: p=0,04; 1 dyne/cm2: p=0,03) ou sem baço (0,5 dyne/cm2: p=0,02; 2 dynes/cm2: p=0,01; 3 dynes/cm2: p=0,03; 5 dynes/cm2: p=0,02 e 7 dynes/cm2: p=0,03). Nossos resultados indicam que embora pertençam ao grupo de Anemias Hemolíticas, as patofisiologias e evoluções clínicas distintas de SCA e de HS levam a padrões imunofenotípicos diferentes de expressão da adesão celular. Na SCA, a ausência de função esplênica teria direta relação com o aumento do fenótipo pró-adesivo e com a adesividade de RBCs SCA, o que traz sérias consequências clínicas aos pacientes, enquanto na HS sem baço, de maneira geral, os eventos de adesão celular são minimizados, embora ainda apresentem reticulócitos e eritrócitos adesivos circulantes após a esplenectomia. / Hemolytic Anemias comprise a group of diseases in which there is marked reduction in the survival of circulating erythrocytes and the bone marrow is not capable of compensation, even by increasing its production, which causes anemia from the first years of the person\'s life on. Among the diseases of this group, Sickle Cell Anemia (SCA) and Hereditary Spherocytosis (HS) stand out for being diseases with intrinsic genetic defects of red blood cells (RBCs) that generate acute and chronic multisystemic complications in their patients. By distinct pathophysiological pathways, reticulocytes and these disease\'s respective defective erythrocytes, sickle and spheroid ones, are continuously trapped and phagocytosed in the spleen, important organ of destruction of old and/or defective cells via extravascular hemolysis, which progressively leads to dysfunction and eventual loss of splenic function. The objective of this study was to evaluate the role of the spleen in relation to the reticulocyte (ret) and erythrocyte (eryt) adhesive ability and adhesion phenotype in patients with SCA and HS, with and without preserved splenic function. Blood samples from 37 patients (22 SCA and 15 HS) with splenic function and 19 patients (13 SCA and 6 HS) without it were evaluated. Still, blood from 22 children with SCA was collected in a longitudinal study from 6 to 29 months of age. All blood samples were analyzed for splenic function [pitted cells (PIT) and Howell-Jolly bodies (HJB) counting], for the cellular immunophenotypic profile (in % and in mean fluorescence intensity - MFI) and for the adhesive ability of RBCs to laminin and to endothelial cell line HMEC-1. Analysis of the splenic function loss transition showed that it intensified from 3 years of age on (PIT: r=0.8, p<0.0001; HJB: r=0.7, p<0.0001). Regarding the cellular immunophenotyping, PIT count correlated positively, mainly with CD147 markers (%ret: r=0.6, p<0.0001; MFIret: r=0.6, p<0.0001; %eryt: r=0.7, p<0.0001; MFIeryt: r=0.6, p<0.0001), LuBCAM (%ret: r=0.5, p=0.004; MFIret: r=0.6, p<0.0001; %eryt: r=0.6, p<0.0003; MFIeryt: r=0.4, p<0.004) and CD58 (%ret: r=0.4, p=0.006; MFIret: r=0.5, p<0.0013; %eryt: r=0.4, p<0.009; MFIeryt: r=0.6, p<0.0001). In the comparison between spleen absence or presence, the loss of its function exerted influence on the increase of RBCs adhesion expression in SCA, mainly on CD147 (%ret: p=0.002; MFIret: p=0.003; %eryt: p<0.0001; MFIeryt: p=0.005), LuBCAM (%ret: p=0.0001; MFIret: p<0.0001; %eryt: p<0.0001; MFIeryt: p<0.0001) e CD58 (%ret: p=0.007; MFIret: p=0.006; %eryt: p=0.003; MFIeryt: p=0.0004), although cell adhesion has been decreased in splenectomized HS patients. In the comparison between diseases, HS patients with spleen showed higher cell adhesion frequency compared to SCA, notably in relation to LuBCAM (%ret: p=0.0008; MFIret: p=0.03; %eryt: p<0.0001; MFIeryt: p=0.0002), CD58 (%ret: p=0.0009; %eryt: p=0.003) and CD44 (%ret: p=0.009; %eryt: p<0.003). However, SCA samples without splenic function had higher cell adhesion expression for CD147 (%ret: p=0.006; MFIret: p=0.02; %eryt: p=0.02), LuBCAM (%ret: p=0.004; MFIret: p<0.0001), CD36 (%ret: p=0.0002; MFIret: p=0.01), CD242 (%ret: p=0.0008; %eryt: p=0.05) and CD49d (%ret: p=0.04). Concerning the in vitro Adhesion Assay, in the spleen absence, SCA RBCs showed greater adhesiveness to laminin than SCA RBCs with preserved splenic function did at all shear stress flow rates applied (0.5 dyne/cm2: p=0.01, 1 dyne/cm2: p=0.02, 2 dynes/cm2: p=0.03, 3 dynes/cm2: p=0.03, 5 dynes/cm2: p=0.04 and 7 dynes/cm2:p=0.03). Especially, reticulocytes from patients without spleen showed higher adhesiveness to HMEC-1 at low shear stresses (1 dyne/cm2) in both diseases (SCA: p=0.03; HS: p=0.03). Finally, reticulocytes showed greater adhesion ability to endothelial cells in SCA subjects than in HS patients, with (0.5 dyne/cm2: p=0.04 and 1 dyne/cm2: p=0.03) or without spleen (0.5 dyne/cm2: p=0.02, 2 dynes/cm2: p=0.01, 3 dynes/cm2: p=0.03, 5 dynes/cm2: p=0.02 and 7 dynes/cm2: p=0.03). Our results indicate that although both diseases belong to the Hemolytic Anemias group, SCA and HS distinct pathophysiologies and clinical evolution lead to different immunophenotypic patterns of cell adhesion expression. In SCA, the absence of splenic function may have a direct relation with the increase of SCA RBCs proadhesive phenotype and adhesiveness, which brings serious clinical consequences to the patients, whereas in HS without spleen, in general, cellular adhesion events are minimized, although they still present adhesive circulating reticulocytes and erythrocytes after splenectomy.

Introduction : La majorité des enfants ayant l’anémie falciforme (AF) sont déficients en vitamine D. Cette déficience causerait ou exacerberait possiblement les complications de l’AF telles que les crises de douleur et les complications osseuses. Nous avons récemment publié que près de 70% des enfants suivis à notre clinique d’AF étaient déficients en vitamine D (<50 nmol/L), que ceux-ci avaient de faibles apports alimentaires en vitamine D et prenaient peu de suppléments. Cliniquement, les enfants déficients en vitamine D avaient un moins bon profil hématologique que les enfants suffisants en vitamine D. Ces résultats nous ont amené à proposer une intervention pour résoudre ces problèmes. Objectifs : Primaires : Évaluer la faisabilité, l’acceptabilité et la sécurité d’un bolus oral de 300 000 UI de vitamine D3, chez les enfants ayant l’AF, combiné à une supplémentation quotidienne de 1 000 UI de vitamine D3 pour 3 mois. Secondaires : Évaluer le changement des taux sériques de 25(OH)D après 3 mois ainsi que les impacts cliniques d’une telle supplémentation. Méthode : Des enfants avec AF (5 à 17 ans, tous les génotypes) ont été randomisés à un bolus oral de vitamine D3 (300 000 UI) ou à un placebo. Tous les enfants ont également reçu une prescription pour des comprimés de 1 000 UI vitamine D3 à prendre quotidiennement. La 25(OH)D sérique a été mesurée au début de l’étude et 3 mois post-bolus (efficacité de l’intervention). Les autres paramètres mesurés lors de l’étude étaient le ratio calcium/créatinine urinaire et le calcium sérique (sécurité), la douleur musculosquelettique, la qualité de vie, l’hématologie et les marqueurs osseux (paramètres cliniques exploratoires). Résultats : Trente-huit enfants ont participé à l’étude (âge moyen de 10,1 +/- 3,6 ans; 63% HbSS, 29% HbSC et 8% S/β thal+) : 18 ont reçu le bolus de vitamine D et 20 le placebo. Au début de l’étude, les niveaux moyens de 25(OH)D étaient de 75 +/- 27 nmol/L et 50% des enfants étaient insuffisants en vitamine D (<75 nmol/L). Chez les enfants ayant pris le bolus, les taux de 25(OH)D se sont élevés à 94 nmol/L après 3 mois et le taux d’insuffisance en vitamine D est descendu à 17%, alors que pour le placebo, les taux de 25(OH)D post 3 mois étaient de 74 +/- 19 nmol/L et le taux d’insuffisance en vitamine D était de 45% (p=0,001). Aucun épisode d’hypercalcémie, d’hypercalciurie ou d’hypervitaminose D (>250 nmol/L) n’a eu lieu durant l’étude, mais les enfants du groupe bolus ont expérimenté plus de symptômes gastro-intestinaux dans le premier mois suivant l’ingestion du bolus, comparativement au groupe placebo. Le décompte de réticulocytes était plus faible à la fin de l’étude pour les enfants du groupe bolus. Aucun autre effet clinique de l’intervention n’a été observé. Conclusion : L’utilisation d’un bolus de vitamine D à haute dose combiné à une supplémentation quotidienne en vitamine D chez des enfants ayant l’AF était plus efficace à élever les taux de 25(OH)D à des taux supérieurs à 75 nmol/L que la supplémentation quotidienne seule. Des études multicentriques à plus grande échelle et de plus longue durée sont nécessaires afin d’évaluer les effets cliniques d’une telle supplémentation. / Background: Most children with sickle cell disease (SCD) are vitamin D deficient. This deficiency could possibly cause or exacerbate SCD complications such as pain crisis and bone complications. We previously showed that nearly 70% of children followed in our SCD Clinic were vitamin D deficient (<50 nmol/L) with low vitamin intake and poor use of supplements. Clinically, worse hematological profile was seen in vitamin D-deficient children compared to vitamin D-sufficient children. This study was designed to overcome these issues. Objectives: Primary objectives were to assess feasibility, acceptability, and safety of a single oral bolus of 300,000 IU of vitamin D3 combined to daily 1,000 IU vitamin D3 for 3 months in children with SCD. Secondary objectives were to asses the mean change in serum 25(OH)D from baseline to 3 months post-bolus and its clinical impact. Procedure: A randomized controlled trial was carried out in children with SCD (5-17 years, all genotypes). Children were randomized to a single bolus of vitamin D3 (300,000 IU) or placebo and also received prescription for daily 1,000 IU vitamin D3. Serum 25OHD (efficacity outcome) was measured at baseline and 3 months post-bolus. Other outcomes measured were urinary calcium/creatinine ratio and serum calcium (safety), musculoskeletal pain, quality of life as well as hematology and bone markers (exploratory outcomes). Results: Thirty-eight children were randomized to received the vitamin D bolus (n=18) or the placebo (n=20) (mean age 10.1 +/- 3.6 years; 63% HbSS, 29% HbSC and 8% S/β thal+). At baseline, 50% of the children were vitamin D insufficient (<75 nmol/L) and mean serum 25(OH)D levels were 75 +/- 27 nmol/L. In the vitamin D bolus group, insufficiency dropped to 17% post 3 months and mean 25(OH)D levels raised to 94 nmol/L. In children who took the placebo, rates of vitamin D insufficiency were 45% and mean 25(OH)D levels were 74 +/-19 nmol/L post 3 months (p=0.001). The vitamin D bolus caused no hypercalcemia, hypercalciuria nor hypervitaminosis D (>250 nmol/L). However compared to the placebo group, more children in the bolus group experienced gastro-intestinal symptoms within the first month following the vitamin D bolus. As for the hematology parameters, only a slight difference in reticulocytes counts was observed with lower reticulocytes count the end of the study in children from the bolus group. No other clinical effects of the intervention were observed. Conclusions: High-dose vitamin D bolus combined to daily supplementation in children with SCD is more efficient than daily supplementation alone to raise 25(OH)D levels ≥75 nmol/L. Large-scale multicenter studies of longer duration are needed to assess whether this intervention can improve clinical outcomes of children with SCD.

Purpose: The purpose of this study was to determine the usefulness of SBAR-cued web-based communication skills training and address study participants' perceptions of the training. Specific Aims: Evaluate the usefulness and accuracy of participants to answer prompts of SBAR-cued communication responses. Describe individuals' perspectives of the acceptability of using SBAR patient-HCP communication simulation to better prepare for ED visits during a SCC. Framework: This study was guided by The Theory of Self-Care Management for Sickle Cell Disease (SCMSCD). Design: A secondary analysis was conducted using a qualitative descriptive approach. Inter-rater reliability (IRR) of qualitative data was used to evaluate the usefulness and accuracy of participants to answer prompts of SBAR-cued communication responses. Content analysis was also utilized to describe individuals' perspectives of the acceptability of using SBAR patient-HCP communication simulation to better prepare for ED visits during a SCC. Results: IRR between raters ranged from 64%-94% with predominant themes of (1) Patient-Provider Communication and Interaction, (2) Patients want to be Heard and Believed, (3) Accuracy of the ED Experience and Incorporating the Uniqueness of each Patient and (4) Overall Usefulness of the Video Trainer emerging. Conclusions: This secondary analysis supported how SBAR can be effectively used to assist patients in a SCC to communicate with their HCP. Participants' responses indicated the training module facilitated communication between patients and HCPs.

Sickle cell disease is a disabling chronic autosomal recessive blood disease characterized by abnormal hemoglobin, pain crises, and frequent emergency department visits. Adherence to hydroxyurea therapy has been shown to improve these patient outcomes. Guided by the theory of comfort, the purpose of this project was to determine if an educational intervention would increase adherence to hydroxyurea therapy in pediatric patients between 2 and 17 years of age recruited from an urban university hospital hematology clinic. The RE-AIM model was used to support the translation of evidence and the change process. An educational video produced by AFLAC was viewed by patients' parents 4 weeks after enrollment into this pretest/posttest design project. A total of 22 African-American parent participants completed the 8-item Morisky Medication Adherence Scale at baseline and again at 8 weeks to assess hydroxyurea adherence. The Short Test of Functional Health Literacy in Adults tool was used to assess parents' health learning needs; all parents met the adequate literacy level at baseline. Using t test statistics, no statistically significant differences were found pretest to posttest on the Morisky Medication Adherence Scale scores, mean corpuscular hemoglobin, and fetal hemoglobin percentages. Wilcoxon Signed Rank tests showed no significant differences in emergency room visits nor number of pain crisis. Although no significant changes emerged in short-term hematologic findings, emergency room visits, and pain crises, social change in the health care setting was promoted by confirming parents were able to understand education and a high level of hydroxyurea adherence was maintained; literature indicated that long-term adherence to hydroxyurea limits severe attacks.

No description available.

No description available.