Orientador: Nicola Amanda Conran Zorzetto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T04:12:18Z (GMT). No. of bitstreams: 1 Almeida_CamilaBononide_M.pdf: 1751160 bytes, checksum: 34725ba06e7511a0cd3632322e61fd59 (MD5) Previous issue date: 2006 / Resumo: A anemia falciforme é um distúrbio genético causado por uma mutação de ponto (Ácido Glutâmico-Valina) que produz uma hemoglobina S. Esta, quando desoxigenada, polimeriza causando deformação dos eritrócitos que se agregam às paredes da micro circulação culminando em crises vaso-oclusivas. Existem algumas moléculas de adesão que colaboram no bloqueio da circulação aderindo eritrócitos, células brancas e plaquetas à parede dos túbulos sanguíneos. A hidroxiuréia (HU) vem sendo utilizada no tratamento da doença devido à sua habilidade em aumentar a produção de hemoglobina fetal (HbF). No entanto, nem todos os pacientes respondem positivamente ao tratamento com HU. Estudos mostram que a HU quando degradada, produz óxido nítrico (NO), o qual ativa a enzima guanilato ciclase solúvel (GCs). Esta, por sua vez, transforma GTP em GMPc que atua como segundo mensageiro ativando provavelmente a transcrição do gene ?-globina aumentando assim, a concentração de HbF e melhorando o quadro clínico dos pacientes com essa doença. Por isso, o NO tornou-se fonte de grandes estudos, uma vez que é um importante vasodilatador. O objetivo desse trabalho foi elucidar qual família de fosfodiesterase (PDE) atua na degradação do GMPc das células de linhagem eritróide e se as drogas inibidoras dessas PDEs seriam capazes de aumentar a produção de ?-globina e conseqüentemente HbF em células eritróides de cultura. Para isso foram realizadas culturas de células K562 tratadas com diferentes drogas inibidoras de PDE (vinpocetina, sildenafil, dipiridamol e zaprinast) e com estimulador de guanilato ciclase, BAY41-2272. Observamos que os níveis de GMPc aumentaram principalmente nas células tratadas com 10µg/ml de dipiridamol e em alguns pontos de coletas com 10 e 50µM de vinpocetina. O mesmo não foi observado nas células tratadas com sildenafil e zaprinast. No entanto, todas as células tratadas com as diferentes concentrações de BAY41-2272 apresentaram aumento na concentração de GMPc. Com relação à expressão gênica relativa de ?-globina, observamos que as drogas dipiridamol, vinpocetina, sildenafil e zaprinast não foram capazes de provocar um aumento da expressão. Diferentemente, BAY41-2272 estimulou um aumento da expressão de ?-globina nas células K562 tratadas com 60 e 300nM após 48 horas de cultura. Além disso, estudamos a expressão das PDEs 1, 5 e 9 em células hematopoéticas e diferentes tecidos. Observamos que PDE9 é significativamente mais expressa em células K562, reticulócitos e neutrófilos. Além disso, observamos também que a expressão dessa PDE é significativamente maior nos reticulócitos e neutrófilos de paciente com anemia falciforme. Já naqueles que se encontravam sob terapia com HU, a expressão da PDE9 nos reticulócitos reverteu aos níveis do controle diferentemente dos neutrófilos, cuja expressão de PDE9 não se alterou entre os pacientes com ou sem terapia com HU. A expressão da PDE9 em outros tecidos (T98G, cólon, ovário, mama, fígado, pele, baço, testículo, útero e linfonodo) é significativamente menor do que nestas células hematopoéticas. Assim sendo, como aumento nos níveis celulares de GMPc pode ser importante tanto para a produção de HbF em células eritróides como para inibir a adesão de leucócitos, bloquear a ação da PDE9 pode representar uma nova estratégica célula-especifica para o tratamento da anemia falciforme / Abstract: Sickle cell disease (SCD) is a systemic disease with a multifaceted pathophysiology; the polymerisation of the sickle haemoglobin molecule (HbS), when deoxygenated, has many consequences that include haemolysis, inflammation, dysregulated nitric oxide (NO) homeostasis and oxidative abnormalities. Agents, such as hydroxyurea (HU), that increase levels of fetal hemoglobin (HbF), with consequent inhibition of HbS polymerization, and that may counteract other aspects of the disease's pathophysiology characterize important therapies for the disorder. Whilst HU therapy successfully augments HbF levels in many patients, not all patients respond to treatment. Studies demonstrate that HU, when degraded, produces nitric oxide (NO), in turn activating the enzyme, soluble guanylate cyclase (GC) in erythroid lineage cells. GC converts GTP to cGMP, which acts as a second messenger for NO, possibly activating the transcription of the ?-globin gene and, consequently, increasing the concentration of HbF. Due to evidence that NO bioavailability may be decreased in SCD individuals, recent research into SCD has focused on the role of NO in the disease, particularly since this gas is an important vasodilator. The objective of this study was to investigate which family(ies) of phosphodiesterases (PDE) may mediate the degradation of cGMP in erythroid lineage cells and whether drugs that inhibit these PDEs are capable of augmenting the production of ?-globin and, consequently, HbF in erythroid cells in culture. For this, cultures of K562 erythroleukemic cells were treated with different PDE inhibitors; vinpocetine, sildenafil citrate, dipyridamole and zaprinast. In addition, cultures were also treated with the guanylate cyclase stimulator, BAY41-2272. Increased levels of cGMP were observed principally in cells treated with 10µg/ml dipyridamole and at some time-points in the presence of 10 and 50µM vinpocetine. No changes in cGMP levels were observed in cells treated with sildenafil nor with zaprinast. However, cells treated with BAY 41-2272 demonstrated augmented cGMP levels at all concentrations used. With regard to relative ?-globin gene expression, dipyridamole, vinpocetine, sildenafil and zaprinast did not increase ?-globin gene expression; in contrast, BAY 41-2272 (60 and 300nM) stimulated increased ?-globin expression after 48h of culture. The gene expressions of PDEs 1, 5 and 9 were also studied in different hematopoietic cell types and other tissues. PDE9 is expressed, at significantly higher levels, in K562 cells (erythroleukemic cells), reticulocytes and neutrophils than in numerous other cell types tested (T98G, colon, mammary, ovary, testicle, liver, skin, spleen, uterus, limphonode). Furthermore, the expression of this PDE was even higher in the reticulocytes and neutrophils of patients with SCD. In patients on HU therapy, the expression of PDE9 in reticulocytes was reversed back to levels similar to those seen in controls. In contrast, PDE9 expression in neutrophils was similar in patients on or of HU therapy. Thus, since the increase in intracellular levels of cGMP may be important for the production of HbF in erythroid cells and also to inhibit leukocyte adhesion, the inhibition of the action of PDE9 may represent a novel drug target for cell-specific treatment of SCD / Mestrado / Ciencias Basicas / Mestre em Clinica Medica

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The majority of Sickle Cell Disease (SCD) prevalence is found in Sub-Saharan Africa, where 80% of the world’s population who suffer from this disease are born. Due to a lack of diagnosis and early treatments, 50-90% of these children will die before they reach the age of five. Current methods used for diagnosing SCD are based on hemoglobin analysis such as capillary electrophoresis, ion-exchange high-performance liquid chromatography, and isoelectric focusing. They require expensive laboratory equipment and are not feasible in these low-resource countries. It is, therefore, imperative to develop an alternative and cost-effective method for diagnosing and monitoring of SCD. This thesis aims to address the development and evaluation of a smartphone-based optical setup for the detection of SCD. This innovative technique can potentially be applied for low cost and accurate diagnosis of SCD and improve disease management in resource-limited settings where the disease exhibits a high prevalence. This Point-of-Care (POC) based device offers the potential to improve SCD diagnosis and patient care by providing a portable and cost effective device that requires minimal training to operate and analyze. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Acute and chronic pain is a common hallmark of sickle cell disease (SCD) in children and adolescents, which can have a profound effect on their quality of life (QOL). However, this relationship is not well quantified. The purpose of this quantitative study was to examine the relationship between SCD pain burden and QOL among Black children ages 8-17 in Mississippi with SCD. The secondary aim was to compare children and caregiver reports of SCD pain burden and QOL with SCD. The social ecological model was used to identify personal factors that influence SCD pain burden and QOL of children with SCD. Eighty-five children and caregiver pairs completed paper surveys on demographics, pain burden, and QOL. Hierarchical linear regression results indicated that increased child SCD pain burden was statistically associated with decreased child's QOL (P

Sickle cell disease (SCD) is one of the most difficult and stressful chronic diseases for parents of afflicted children to manage. Managing SCD can be traumatic for parents particularly if they have no specific coping strategies for managing the disease or ensuring the child visits the doctor as scheduled. The use of certain coping strategies may affect the parents' and patients' perceptions of the illness and influence their decisions regarding treatment, which can have a lasting impact on their lives. Effective parental strategies such as positive thinking can aid in disease management, but there is limited research on the coping strategies used by parents of children with SCD specifically. The purpose of this phenomenological study, which was guided by Thompson and Gustafson's transactional stress and coping model, was to describe parents' coping strategies in managing their young child's SCD as it relates to use of health services. Data collection included one-to-one, open-ended interviews with 10 parents of children with SCD. Colaizzi's method of phenomenological data analysis was used to identify themes. Five themes emerged from data analysis and they are: parental methods of coping with SCD, participants' understanding of SCD, SCD family and support, managing SCD with hydration and medication, and experience accessing healthcare. These results indicated the participants' coping strategies varied according to their individual situations. Insight from this study could lead to positive social change by helping to identify specific coping strategies parents can use to better manage their child's disease and effectively access available health services.

The carrier frequency for sickle cell anemia among Nigerians, who account for a high percentage of African immigrants in the United States, is high, according to the World Health Organization. Even though sickle cell disease contributes $2.4 billion annually to U.S. health care expenditures, ascertaining the number of affected individuals in the U.S. is difficult because sickle cell is not a reportable genetic disease. However, according to the Census Bureau, the number of African immigrants continues to grow at a steady pace among the foreign-born immigrant population in the U.S. There is a lack of research on the contribution of the immigrant population to the sickle cell incidence and mortality rates in the U.S. The purpose of this study was to examine the level of awareness and attitude of young Nigerian immigrants in the United States to sickle cell screening and premarital genetic testing. The health belief model constituted the study's theoretical foundation. It was assumed that the level of awareness of sickle cell disease and the romantic choices among young Nigerian college and graduate students in the United States would have a direct relationship. A sample of undergraduate and graduate students of Nigerian origin completed an online survey developed for the study. The results from SPSS analyses indicated that even though this population sample has a high knowledge and awareness of sickle cell disease, they are non-committal about adapting and implementing such knowledge when making romantic choices. In order to continue to reduce the burden of sickle cell disease on healthcare delivery in the United States, public health education programs that address the adaptation and implementation of knowledge about sickle cell disease are needed.

Sickle cell disease (SCD) is a genetic disorder that affects millions of people worldwide. According to the Centers for Disease Control and Prevention, over 100,000 Americans have SCD, and more than 2 million Americans have a sickle cell trait (SCT). People with SCD are more likely than others to suffer premature mortality. Genetic screening is an important step in improving quality of life and increasing longevity for those with SCD. Early detection may lead to effective management of the disease and reduction of complicating factors. The purpose of this quasi-experimental study was to determine whether health education about SCD would impact college students' knowledge, attitudes, perceived risk, and intention to seek genetic screening and counseling in relation to the disease. The theoretical foundation for this study was the health belief model (HBM). This study involved 80 college students selected from a North Texas college. These students completed pre and post versions of an SCD questionnaire. Independent samples t tests were used to determine if there were significant differences in pre- and posttest scores of participants in both groups, and a MANOVA was used to determine differences among the scores of participants in the experimental group when grouped by age, gender, race, religiosity, and socioeconomic status. The results of this study showed that SCD health education improved the knowledge of and attitudes towards participants. Future research could explore barriers to seeking SCD screening and genetic counseling. Results of this study may further social change by encouraging the development of college-based health education efforts to increase awareness about SCD.

Sickle cell disease (SCD) is a genetic disorder that affects millions of people worldwide. According to the Centers for Disease Control and Prevention, over 100,000 Americans have SCD, and more than 2 million Americans have a sickle cell trait (SCT). People with SCD are more likely than others to suffer premature mortality. Genetic screening is an important step in improving quality of life and increasing longevity for those with SCD. Early detection may lead to effective management of the disease and reduction of complicating factors. The purpose of this quasi-experimental study was to determine whether health education about SCD would impact college students' knowledge, attitudes, perceived risk, and intention to seek genetic screening and counseling in relation to the disease. The theoretical foundation for this study was the health belief model (HBM). This study involved 80 college students selected from a North Texas college. These students completed pre and post versions of an SCD questionnaire. Independent samples t tests were used to determine if there were significant differences in pre- and posttest scores of participants in both groups, and a MANOVA was used to determine differences among the scores of participants in the experimental group when grouped by age, gender, race, religiosity, and socioeconomic status. The results of this study showed that SCD health education improved the knowledge of and attitudes towards participants. Future research could explore barriers to seeking SCD screening and genetic counseling. Results of this study may further social change by encouraging the development of college-based health education efforts to increase awareness about SCD.

Sickle cell trait (SCT) is a very prevalent disorder in the United States, especially among African Americans or people of African descent. However, even with the prevalence of the disorder, there are no standardized guidelines for providing patients with information about SCT and the implications of the disorder at physicals and well-check visits. The purpose of this evidence-based project was to increase awareness for African American patients 18-44 years old in the practice setting about SCT and to provide options for testing and genetic counseling. Kotter's contemporary change theory was used as a guide to implement the new practice approach. A quasi-experimental, single-group, pretest-posttest-only design was used to explore the relationship between providing consistent SCT education and the impact on the rate of SCT screening and genetic counseling. A total of 71 patients participated in the program. The analysis showed a significant (p < 0.001) mean difference of 18.16 points from the preintervention SCT and genetics test mean, which indicated that the intervention was successful in raising SCT and genetics knowledge scores among the target population. The results demonstrated that the implementation of SCT education in the practice setting can enhance social implications related to SCT awareness and opportunities for SCT testing and genetic counseling. The implementation of SCT clinical guidelines can help to increase awareness about SCT and improve the overall population health and reduce the financial burden affiliated with care of those with sickle cell disease and SCT complications.

Sickle cell disease is a hereditary blood disorder caused by a point mutation in the gene encoding hemoglobin. This mutation causes hemoglobin molecules to polymerize during de-oxygenation of erythrocytes producing rod-shaped polymers that bend and distort the red blood cell membrane, making it more rigid and “sickled”. This sickling causes red blood cells to lose their flexibility and ability to navigate small capillaries and also enhances the production of pro-inflammatory membrane-derived microparticles, leading to chronic inflammation and many complications such as peripheral artery disease, stroke, myocardial infarction, vasculitis and even death. Sphingolipids are a class of lipids containing a backbone of sphingoid bases and are integral components of erythrocyte and microparticle membranes. Many of these lipids are known to mediate biological processes, but their expression, distribution and orientation in erythrocytes during sickle cell disease has never been explored. Sphingomyelin, the most abundant sphingolipid in the red blood cell membrane is hydrolyzed by sphingomyelinase to produce ceramide, which has been shown to alter membrane dynamics and enhance microvessel formation. Additionally, ceramide can be further metabolized to form sphingosine and sphingosine 1-phosphate, which is a bioactive ligand for 5 known G-protein coupled receptors present on most blood and vascular cells that modulates cell motility, proliferation, migration and phenotype. Prior to this work, it was not understood how sphingolipid metabolism contributes to vascular inflammation in sickle cell disease. Together, this body of work has elucidated key enzymatic and lipidomic alterations in sphingolipid metabolism (i.e. the activation of acid sphingomyelinase on red blood cells) that result in the production of sphingolipid-rich erythrocyte-derived microparticles, which enhance inflammatory cell activation. Our work has elucidated novel pharmacological targets to reduce microparticle generation and subsequent vascular inflammation in sickle cell disease.