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It is now well established that children with sickle cell disease (SCD) demonstrate cognitive deficits even in the absence of clinical stroke, but studies in children who have not experienced a stroke or other neurological event are lacking. Systemic processes that occur in SCD, like chronic inflammation and hypoxia, have been associated with hippocampal damage and episodic memory deficits in a range of clinical populations and animal models. However, studies examining episodic memory performance in children with SCD and in relation to systemic processes are largely absent. The present study addressed these gaps in young children with SCD (Mage = 7.37 years, SD = 1.51) who had not experienced a clinical stroke. Participants (N = 31) completed various memory measures as part of a larger neuropsychological protocol and participated in routine clinical blood draws. Latent class analysis (LCA) was used to empirically define SCD groups based on measures of specific visual memory processes, and results revealed two distinct visual memory groups, characterized by (1) visual memory deficits, specifically in delayed recognition abilities, and (2) intact visual memory. Follow-up analyses revealed that the two classes did not significantly differ on verbal memory performance. The relation between memory processes and both biomarkers of inflammation and adaptive functioning also were examined with variable-centered analyses. Results showed only one significant relation between C-reactive protein (CRP) and a measure of verbal delayed recognition. In sum, young children with SCD demonstrate variable episodic memory performance, with most notable deficits in visual delayed recognition. Higher levels of CRP, a biomarker of inflammation, were associated with poorer verbal delayed recognition. The results indicate that young children with SCD experience deficits in memory, even in the absence of a neurological event, and specific memory processes should be assessed in these children to guide targeted interventions. / Psychology

A continuous need for blood products, specifically for those who require frequent transfusions, such as individuals with sickle cell disease, warrants the need for targeted interventions to increase blood donations from underrepresented populations. One population in particular, African Americans, only account for 1% of blood donors in the United States. Literature indicates numerous reasons why this population is underrepresented amongst donors, including fear, lack of knowledge about the blood donation, and specific to this population, lack of trust in the medical community. This study involves the development, implementation, and assessment of a targeted educational approach, incorporating the Theory of Planned Behavior and various teaching methods, to motivate African Americans non-donors to attempt to donate blood. Participants attended a 1-hour educational session where they completed two surveys, one before the session and one directly after. A third survey was completed 2 months after the session. Of the 155 individuals enrolled in the study, 142 subjects were included in the data analysis. Sixteen percent of the study participants presented to donate as a result of attending the educational session. This resulted in a statistically significantly higher proportion of African Americans presenting to donate than the current proportion in Virginia. Analysis of results from the first two surveys indicated that subjective norm and attitude were significant predictors of one’s intent to donate blood, while perceived behavioral control was not a factor. The educational session increased survey scores related to intent to donate in comparison to scores obtained prior to the session. While this study resulted in a significant proportion of new donors, there is still a need for interventions that will focus specifically on changing attitudes toward blood donation and a need for methods to motivate African Americans to educate individuals in the community on the importance of becoming blood donors.

Introduction. 5-HMF and novel INN-compounds are left-shifting AEH, shown to have anti-sickling action by forming transiently covalent Schiff-base adducts with hemoglobin (Hb), thereby increasing the Hb O2-affinity. They are hypothesized to be substrates for aldehyde dehydrogenase (ALDH) in the liver and red blood cells (RBC). Methods. Biopharmaceutical assessments were made for AEH, using calculated physicochemical properties. Their in-vitro hepatic metabolism (mediated by ALDH) was characterized using hepatic cytosol, and in-vitro-in-vivo extrapolations (IVIVE) were made. Inter-species differences in hepatic cytosolic ALDH activity were investigated using acetaldehyde as a model substrate in different mammalian species. Time- and concentration-dependent in-vitro disposition of 5-HMF in human whole blood was fully characterized and quantitatively modeled. In-vitro time- and concentration-dependent pharmacodynamic (PD) profiling of AEH (0.5 – 5 mM) was carried out in normal whole blood. 5-HMF binding to (normal) HbA and (sickle) HbS was studied in systematic time- and concentration-dependency studies using isolated Hb solutions. Quantitative PK/PD models were developed to fit the experimental data by nonlinear regression (Scientist®). Results. 5-HMF and the two INN-compounds were classified as BCS-I and BCS-II, respectively. All AEH were substrates for hepatic ALDH, with predicted low/intermediate hepatic extraction. Intrinsic ALDH activity varied significantly between mammalian species. In whole blood, 5-HMF plasma concentrations declined rapidly (t1/2 of 0.8 – 4 hrs), with nonlinear kinetics, due to saturable Hb-binding. AEH showed a time-dependent, biphasic PD effect in whole blood, suggesting transiently covalent Hb binding, with slow recovery to the baseline, corresponding to dissociation from Hb and subsequent metabolism by RBC-ALDH. Binding studies with HbA and HbS demonstrated slight differences in binding affinity, but sustained adduct formation - with slow dissociation t1/2. A novel semi-mechanistic target-site drug disposition (TSDD)/PD model was developed, integrating the information, for simultaneous modeling of 5-HMF concentrations in plasma, and its effect in whole blood. Conclusions. This translational research investigated in detail the in-vitro PK/PD of AEH, and systematically compared findings with older generation compounds. A (generic) novel TSDD/PD model was developed for disposition of AEH, identifying k-1 (dissociation constant of AEH from Hb) and kmet (RBC-ALDH metabolism rate constant) as key properties for the time course of PD effect.

Red blood cell hemolysis in sickle cell disease (SCD) releases free hemoglobin. Extracellular hemoglobin and its degradation products, free heme and iron, are highly toxic due to oxidative stress induction and decrease in nitric oxide availability. We propose an approach that helps to eliminate extracellular hemoglobin toxicity in SCD by employing a bacterial protein system that evolved to extract heme from extracellular hemoglobin. NEAr heme Transporter (NEAT) domains from iron-regulated surface determinant proteins from Staphylococcus aureus specifically bind free heme as well as facilitate its extraction from hemoglobin. We demonstrate that a purified NEAT domain fused with human haptoglobin beta-chain is able to remove heme from hemoglobin and reduce heme content and peroxidase activity of hemoglobin. We further use molecular dynamics (MD) simulations to resolve molecular pathway of heme transfer from hemoglobin to NEAT, and to elucidate molecular mechanism of such heme transferring process. Our study is the first of its kind, in which simulations are employed to characterize the process of heme leaving hemoglobin and subsequent rebinding with a NEAT domain. Our MD results highlight important amino acid residues that facilitate heme transfer and will guide further studies for the selection of best NEAT candidate to attenuate free hemoglobin toxicity.

<p>Background: Sickle Cell Disease (SCD) is a genetic hematological disorder that affects more than 7 million people globally (NHLBI, 2009). It is estimated that 50% of adults with SCD experience pain on most days, with 1/3 experiencing chronic pain daily (Smith et al., 2008). Persons with SCD also experience higher levels of pain catastrophizing (feelings of helplessness, pain rumination and magnification) than other chronic pain conditions, which is associated with increases in pain intensity, pain behavior, analgesic consumption, frequency and duration of hospital visits, and with reduced daily activities (Sullivan, Bishop, & Pivik, 1995; Keefe et al., 2000; Gil et al., 1992 & 1993). Therefore effective interventions are needed that can successfully be used manage pain and pain-related outcomes (e.g., pain catastrophizing) in persons with SCD. A review of the literature demonstrated limited information regarding the feasibility and efficacy of non-pharmacological approaches for pain in persons with SCD, finding an average effect size of .33 on pain reduction across measurable non-pharmacological studies. Second, a prospective study on persons with SCD that received care for a vaso-occlusive crisis (VOC; N = 95) found: (1) high levels of patient reported depression (29%) and anxiety (34%), and (2) that unemployment was significantly associated with increased frequency of acute care encounters and hospital admissions per person. Research suggests that one promising category of non-pharmacological interventions for managing both physical and affective components of pain are Mindfulness-based Interventions (MBIs; Thompson et al., 2010; Cox et al., 2013). The primary goal of this dissertation was thus to develop and test the feasibility, acceptability, and efficacy of a telephonic MBI for pain catastrophizing in persons with SCD and chronic pain. </p><p>Methods: First, a telephonic MBI was developed through an informal process that involved iterative feedback from patients, clinical experts in SCD and pain management, social workers, psychologists, and mindfulness clinicians. Through this process, relevant topics and skills were selected to adapt in each MBI session. Second, a pilot randomized controlled trial was conducted to test the feasibility, acceptability, and efficacy of the telephonic MBI for pain catastrophizing in persons with SCD and chronic pain. Acceptability and feasibility were determined by assessment of recruitment, attrition, dropout, and refusal rates (including refusal reasons), along with semi-structured interviews with nine randomly selected patients at the end of study. Participants completed assessments at baseline, Week 1, 3, and 6 to assess efficacy of the intervention on decreasing pain catastrophizing and other pain-related outcomes. </p><p>Results: A telephonic MBI is feasible and acceptable for persons with SCD and chronic pain. Seventy-eight patients with SCD and chronic pain were approached, and 76% (N = 60) were enrolled and randomized. The MBI attendance rate, approximately 57% of participants completing at least four mindfulness sessions, was deemed acceptable, and participants that received the telephonic MBI described it as acceptable, easy to access, and consume in post-intervention interviews. The amount of missing data was undesirable (MBI condition, 40%; control condition, 25%), but fell within the range of expected missing outcome data for a RCT with multiple follow-up assessments. Efficacy of the MBI on pain catastrophizing could not be determined due to small sample size and degree of missing data, but trajectory analyses conducted for the MBI condition only trended in the right direction and pain catastrophizing approached statistically significance. </p><p>Conclusion: Overall results showed that at telephonic group-based MBI is acceptable and feasible for persons with SCD and chronic pain. Though the study was not able to determine treatment efficacy nor powered to detect a statistically significant difference between conditions, participants (1) described the intervention as acceptable, and (2) the observed effect sizes for the MBI condition demonstrated large effects of the MBI on pain catastrophizing, mental health, and physical health. Replication of this MBI study with a larger sample size, active control group, and additional assessments at the end of each week (e.g., Week 1 through Week 6) is needed to determine treatment efficacy. Many lessons were learned that will guide the development of future studies including which MBI strategies were most helpful, methods to encourage continued participation, and how to improve data capture.</p> / Dissertation

Segundo estimativas da Organização Mundial de Saúde (OMS) no Brasil nascem 3.500 crianças com anemia falciforme a cada ano e 20% delas não conseguem atingir os cinco anos de idade devido às complicações diretas causadas pela doença. A anemia falciforme é uma doença do grupo das hemoglobinopatias extremamente comum e é causada por uma alteração molecular no cromossoma 11, quando ocorre a substituição do ácido glutâmico pelo aminoácido valina, na posição 6 da cadeia da &beta;- globina. No Brasil acredita-se que a anemia falciforme seja a doença hereditária que mais prevalece, sendo assim, ela é considerada um problema de saúde pública. Alguns estudos apontaram a existência de uma prevalência de aproximadamente 4 a 5% em recém-nascidos portadores da doença e sua maior incidência ocorre no norte e nordeste, regiões brasileiras mais pobres e com maior miscigenação das populações. É urgente a necessidade do desenvolvimento de um diagnóstico viável e acessível a tais áreas, pois existe o reconhecimento pela própria OMS de tal prioridade e que levou o Brasil a criar uma Portaria em 2005 e um Decreto em 2008 que instituem atenção integral aos portadores da doença falciforme. Portanto, foi desenvolvido neste trabalho um método de triagem para a detecção de anemia falciforme, que usou uma tecnologia atual conhecida como point-of-care. Para isso foi utilizado uma gota de sangue em meio tamponado com detergente comercial Limpol® para lisar as hemácias e o hidrossulfito de sódio para reduzir a hemoglobina S e esta foi detectada em papel de cromatografia. O método foi desenvolvido com eficácia, pois foi proposta a substituição da saponina (reagente caro) por detergente comercial Limpol® e do hidrossulfito de sódio (reagente caro) por tiossulfato de sódio, tornando o custo do kit desenvolvido muito baixo. Portanto, sob quaisquer condições adversas e em qualquer região que necessite da triagem diagnóstica populacional, principalmente nas comunidades carentes e de difícil acesso, será possível levar uma solução simples a campo para a execução de um diagnóstico rápido e sem aumento do ônus para o sistema de saúde público brasileiro, consolidando os direitos adquiridos dos indivíduos, mas que não abrangem àqueles que mais necessitam. / According to estimates from the World Health Organization (WHO), every year are born around 3.500 children with sickle cell anemia (SCA) in Brazil and 20% of them wont reach five years old because of complications directly related to the disease. The SCA is a disease of the hemoglobinopathies group extremely common and is caused by a molecular alteration in the chromosome 11, when occurs the replacement from the acid glutamic acid by amino acid valine in the chain of position 6 of the &beta;- globin. In Brazil is believed that the SCA is the hereditary disease that prevails more being considered as a public health problem. Some studies have indicated that exist prevalence in approximately 4-5% of this disease in newborns and the greatest incidence there is mainly in north and northeast, regions with bigger miscegenation from population. Is urgent the necessity in to develop viable accessible diagnostic for those areas whereas it was recognized as a priority by the WHO leading Brazil to create an Ordinance in 2005 and a Decree in 2008 establishing total care to the people with sickle cell disease. Therefore, was developed in this work a screening method to detect the sickle cell anemia, which used a technology known as point-of-care. Was created an alternative method to substitute one international kit which has high cost for the adequation according with of economic Public Health conditions from Brazil. For this a drop of blood in buffered medium with liquid detergent Limpol®, to lyse RBC and the (tiossulfato de sódio) to reduce the RBC S which was detected in simple celulose paper. The method was developed with efficiency, on this account the substitution of saponina (expensive reagent) by liquid detergent Limpol® and (hidrossulfitob de sodio) (expensive reagent) by (tiossulfato de sódio) was successful making the cost of developed kit cheaper. Therefore in any population with adverse conditions or region where there are needs, mainly in poor communities with difficult acces, will be possible to lead a simple solution at field to execution by a quickly diagnostic without increasing of charges to health public brazilian system, consolidating acquired rights to individuals that not are reached by those needs yet.

Sickle cell disease is an inherited blood cell disorder that affects about 100,000 people in the US and results in high cost of medical care exceeding $1.1 billion annually. Sickle cell patients suffer from unpredictable, painful vaso-occlusive crises. Portable, costeffective approaches for diagnosis and monitoring sickle blood activities are important for a better management of the disease and reducing the medical cost. In this research, a mobile application controlled, impedance-based flow cytometer is developed for the diagnosis of sickle cell disease. Calibration of the portable device is performed using a component of known impedance value. The preliminary test results are then compared to those obtained by a commercial benchtop impedance analyzer for further validation. With the developed portable flow cytometer, experiments are performed on two sickle cell samples and a healthy cell sample. The acquired results are subsequently analyzed with MATLAB scripts to extract single-cell level impedance information as well as statistics of different cell conditions. Significant differences in cell impedance signals are observed between sickle cells and normal cells, as well as between sickle cells under hypoxia and normoxia conditions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Le premier objectif de cette thèse était d’améliorer l’utilisation et la compréhension des outils de mesure de la déformabilité du globule rouge (GR) dans la drépanocytose (Etudes 1 et 2). L’étude 1 a montré l’importance de la standardisation des mesures de déformabilité par ektacytométrie chez les enfants drépanocytaires. Au cours de l’étude 2, les propriétés des GR ont été modifiées et la variation des courbes de déformabilité érythrocytaire « classique » (index d’élongation en fonction de la contrainte de cisaillement en milieu isotonique) a été comparée aux résultats d’osmoscan (mesure de la déformabilité érythrocytaire en gradient osmolaire à contrainte de cisaillement fixe), méthode de référence pour étudier les anomalies de la membrane du GR. Ainsi, les variations de déformabilité érythrocytaire au-delà de 3 Pa sont affectées à la fois par la viscosité interne du GR et par des modifications de la surface cellulaire (rapport surface/volume) alors que les modifications de l’élasticité membranaire affectent la déformabilité érythrocytaire quelles que soient les forces de cisaillements utilisées (faibles, modérées ou hautes). Le deuxième objectif de cette thèse était d’apporter des éléments supplémentaires sur l’implication des facteurs génétiques, des paramètres hémorhéologiques et du niveau de stress oxydant sur la survenue des complications vaso-occlusives chez les patients atteints de syndrome drépanocytaire majeur (Etudes 3 à 6). La mise en commun des résultats d’hémorhéologie obtenus sur 165 patients de notre cohorte lyonnaise et 240 patients de la cohorte guadeloupéenne a permis de montrer que la rhéologie du GR chez les patients drépanocytaires était dépendante de l’âge. Ainsi, la viscosité sanguine augmente avec l’âge pour atteindre un plateau vers 30 ans alors que la déformabilité érythrocytaire diminue avec l’âge (Etude 3). Ces modifications participent vraisemblablement à l’apparition de complications chroniques chez l'adulte drépanocytaire. Les études 4 et 5 ont été réalisées sur la cohorte pédiatrique lyonnaise. Au cours de ces 2 études, nous avons étudié l’influence sur la rhéologie du sang et la survenue de crises vaso-occlusives (CVO) des facteurs génétiques (alpha-thalassémie, déficit en Glucose-6-Phosphate Déshydrogénase (G6PD) et haplotypes S) d’une part (Etude 4) et du niveau de stress oxydant et nitrosatif d’autre part (Etude 5). L’alpha-thalassémie augmente la déformabilité des GR et l’agrégation érythrocytaire. Ces 2 phénomènes pourraient participer à augmenter le risque de CVO. De plus, l’alpha-thalassémie, en diminuant l’hémolyse, diminuerait le niveau de stress oxydant, élément majeur impliqué dans la physiopathologie de la drépanocytose. Enfin, l’étude 6 a montré que la rhéologie sanguine des patients Sbêta+ était quasi-identique à celle des sujets sains AA mais que les patients les plus sévères pourraient avoir un déficit en monoxyde d’azote circulant. En conclusion, mon travail de thèse contribue à une meilleure compréhension de la physiopathologie de la drépanocytose / The first goal of this thesis (Study 1 and 2) was to improve the use and the comprehension of tools for red blood cell (RBC) deformability measurements in sickle cell disease (SCD). The first study showed the importance of standardization of RBC deformability measurements by ektacytometry in SCD children. In the study 2, the RBC proprieties was modified and the variation of « classic » RBC deformability curve (elongation index as a function of the shear stress in isotonic medium) was compared to osmoscan results (elongation index in hyperosmolar gradient and constant shear stress), the gold standard for RBC membrane defect studies. Thus, the modifications of RBC deformability curve above 3 Pa were affected by RBC internal viscosity and cellular surface modification (and thus surface/volume ratio) while membran elasticity modifications affected RBC deformability whatever the shear stress (low, moderate or high). The second goal of this thesis was to study the effects of genetic modifiers, hemorheological parameters and oxidative stress level on vaso-occlusive complications (VOC) in SCD (Study 3 to 6). Hemorheological parameters were measured on 165 patients from Lyon and 240 patients from Gwada and the results showed that blood viscosity increased until the age of 30 and RBC deformability decreased with age (Study 3). This modifications probably play role in the chronic complications of SCD adult patients. The studies 4 and 5 were conducted on SCD children. We studied the effects of genetic modifiers (alpha-thalassemia, glucose-6-phospho-deshydrogenase deficiency and S haplotypes ; study 3) and nitro-oxidative stress level (study 5). Alpha-thalassemia increase RBC deformability and RBC aggregation. This phenomenon could contribute to increase VOC. Moreover, alpha-thalassemia decreased hemolysis and thus oxidative stress, a major component of SCD physiopathology. Then the study 6 showed that Sbeta+ patient hemorheology was quite the same of AA ubjects but the more severe patients could have a defect in circulating nitric oxide. To conclude, my thesis contribute to a better understanding of SCD physiopathology