Introdução: As transfusões de sangue e as Reações transfusionais (RT) têm tido grande destaque nas discussões e estudos da hemoterapia atual, devido a necessidade e relevância para a prática transfusional e na busca em qualificar as transfusões e refinar a classificação das RT. As reações transfusionais febris não hemolíticas (RTFNH) apresentam um crescente no número de notificações e despertam a necessidade de mais estudos. Durante a estocagem dos hemocomponentes, ocorrem uma série de alterações morfológicas, aumento de potássio (K+) extracelular, hemólise e aumento de hemoglobina (Hb) sobrenadante. Analisar a qualidade e viabilidade do hemocomponente pode nos levar a verificar os fatores preditores de uma RT, procurando minimizar os riscos e selecionar um hemocomponente de melhor qualidade ao paciente. Objetivos: Avaliar potenciais fatores etiológicos na precipitação das RTFNH por meio da mensuração na concentração de sódio (Na+) e K+ no sobrenadante, a contagem leucocitária por mcL, o cultural e o Hematócrito (Ht) e Hb da bolsa de concentrado de hemácias (CH) envolvidas, comparando estes parâmetros em relação a um grupo controle de bolsas de CH. Analisar e comparar o perfil dos pacientes envolvidos com a RTFNH e do grupo controle e, estimar a frequência de culturais coletados positivos e os germes envolvidos. Metodologia: Estudo de caso-controle com seleção de amostras a partir de notificações de suspeita de RTFNH ao Serviço de Hemoterapia de um Hospital Universitário de Porto Alegre - RS, no período de setembro de 2015 a setembro de 2016. O grupo controle foi selecionado a partir da mesma população de bolsas, sendo pareadas por tipagem sanguínea e data de vencimento do hemocomponente, numa proporção de 1:2,1. Resultados: o total incluído foi de 124 bolsas, sendo 39(30,5%) do grupo RT e 85(69,5%) do grupo controle, onde uma série de variáveis foram avaliadas. A média de dias de estocagem das bolsas foi de 10,7(DP=6,7) dias, sendo que no grupo RT 12,1(DP=8,1), foi significativamente maior que no grupo controle 10(DP=5,8) com (P=0,037). Também quando avaliamos as dosagens de Ht as médias verificadas foram de 68,3(DP=7,27), sendo no grupo RT 71(DP=81) e 67(DP=6,5) no grupo controle e, na comparação dos grupos, observamos um P<0,001. Dessa forma, a cada dia a mais de estocagem e, a cada ponto a mais no HT da bolsa, há um aumento na chance de aparecimento de RTFNH. Conclusões: a lesão de estocagem é uma temática importante no momento da oferta de hemocomponentes ao paciente, principalmente aos pacientes em tratamento oncológico de tumores sólidos. A avaliação do HT e do tempo de estocagem da bolsa demonstraram ter relevância estatística e clínica na predição de aparecimento de RTFNH. O manejo de estoque adequado para poder haver essa oferta se faz necessário. Novos estudos serão necessários para verificarmos os mecanismos desencadeantes da RTFNH comparado com o Ht da bolsa e, também estudos relacionados à utilização de pré medicação nas transfusões. / Introduction: Blood transfusions and the transfusion reactions (TR) have had great emphasis in current hemotherapy discussions and studies, due to its importance in transfusion practice and with the aim of qualifying the transfusions and refining TR classifications. The non-hemolytic febrile transfusion reaction (NHFTR) show an increasing number of notifications and arouse the necessity for further studies. During the storage of blood products a series of morphologic alterations occur, such as extracellular potassium (K+) increase, hemolysis and supernatant Hemoglobin (Hb) increase. Analyzing the blood product quality and availability may lead us to verifying predictive factors of a TR, seeking to minimize the risks and select a blood product of a superior quality for the patient. Objective: Evaluate potential etiological factors in the NHFTR precipitation through sodium (Na+) concentration measurement and K+ in the supernatant, the leukocyte count by mcL, the cultural and the Hematocrit (Ht),and Hb of erythrocyte concentrate bag (EC) involved, comparing those parameters in relation to a control group of EC blood bags. Analyze and compare the profile of the patients involved with a NHFTR to the control group and estimate the frequency of positive cultures collected and the germs involved. Methodology: Case-control study with sampling selections from a notification of NHFTR suspicion at a Hemotherapy Service in a College Hospital in Porto Alegre, RS, during the period from September 2015 to September 2016, where the control-group was selected from the same blood bag population, being grouped by blood type and blood product expiry date, in proportion 1:2.1. Results: Were studied 124 blood bags, being 39(39,5%) from the TR group and 85(69,5%) from the control group, where a series of invariables were evaluated. The mean of blood bag storage was 8.5 days, 10,7(PD=6,7) in the TR group and 10(DP=5,8) in the control group, and when compared they showed a P=0.037. Moreover, when we analyzed the Ht dosage, it was verified an mean of 68,3(DP=7,27), in the TR group and 71(DP=81), 67(DP=6,5) in the control group and, comparing both groups, we observed a P=<0.001. Therefore, with each additional storage day and, with each additional point in the Ht bool bag, the chance of NHFTR appearance increases. Conclusions: Storage injury is an important topic at the moment of the offer of blood components to the patient, especially to the ones with ongoing oncological treatments for solid tumors. The HT evaluation and the storage time of the blood bag demonstrate clinical and statistical relevance in the prediction of NHFTR appearance. The management of adequate storage is fundamental for the offer’s availability. Further studies are needed to verify the triggering mechanisms of NHFTR compared to the Ht of the bag, as well as studies associated with the use of premedication in transfusions.

Les vésicules sont gouttes de rayon de quelques dizaines de micromètres, limitées par une membrane lipidique imperméable d'environ 4 nm d'épaisseur, et immergées dans un fluide visqueux externe. Les propriétés spécifiques de la membrane de la vésicule rendent le système très déformable et très contraint dans le même temps. Les vésicules représentent également un modèle simplifié intéressant pour les globules rouges, car ils partagent aussi certains comportements mécaniques similaires.Ce manuscrit s’intéresse à la modélisation d'une vésicule soumise à des contraintes externes d'origine hydrodynamique, dans le régime Stokes et dans des domaines confinés. À partir d'un modèle BEM déjà existant pour des fluides infinis, des méthodes numériques originales sont développés pour faire face au calcul des interactions entre la membrane de la vésicule et les frontières solides. Une attention particulière est accordée à la situation d'une vésicule qui sédimente vers un mur horizontal et une vésicule soumise à un écoulement de Poiseuille dans un capillaire étroit. / Vesicles are drops of radius of a few tens micrometers, bounded by an impermeable lipid membrane of approximately 4 nm thickness, and embedded in an external viscous fluid. The specific properties of the vesicle membrane make the system very deformable and very constrained at the same time. Vesicles represent also an interesting simplified model for red blood cells, since they also share some similar mechanical behaviours.This manuscript deals with the modeling of a vesicle subjected to external stresses of hydrodynamical origin, in the Stokes regime and in confined domains. Starting from an existing BEM model for free space flows, original numerical methods are developed to deal with the computation of interactions between the vesicle membrane and solid boundaries. A particular attention is paid to the situation of a vesicle sedimenting towards a planar wall and a vesicle submitted to a Poiseuille flow in a narrow capillary.

<p>Despite previously accepted dogma, several recently published studies in humans and mice have shown that mature red blood cells (RBCs) contain a pool of microRNAs. Their role is currently uncertain; however, it has been suggested that microRNAs may play a role in cellular communications as they can be transferred from the RBC to endothelial cells or other cells. This thesis investigated the set of differentially abundant microRNAs found in mature RBCs of felines with oxidative stress, using diabetes mellitus as an oxidant stressor. We postulated that individual microRNAs identified in this study, might be valuable targets for future studies, investigating the role specific microRNAs play in the development or progression of diabetes and in the oxidative damage inflicted on the red cell and other cells by this disease.</p><p>The first specific objective of this thesis was to document oxidative stress in diabetic cats. In the absence of validated assays to document the presence of oxidative protein damage in felines, we first evaluated the performance of a commonly used colorimetric assay for measurement of protein carbonyls (PC) in serum and plasma. Although within run variation was acceptable and performed well over a wide range of PC content values, there were severe limitations related to excessive between run-variation, hemoglobin interference, and difficulty of assay performance. Therefore, we developed and validated a new method, using a fluorescent probe. This new assay had good within and between-run variations, a broad analytical range, and was easy and rapid to run. Hemoglobin and triglyceride only affected the results when present at moderate to higher levels. To further evaluate their redox status, free-radical production and oxidative stress were measured in diabetic and healthy, control cats. The presence of oxidative stress was assessed by measurement of the resulting damage to biomolecules, and detection of antioxidant levels. Our data indicated the presence of protein and membrane lipid oxidation in diabetic individuals and suggest that the redox status of the mature RBC was shifted toward an oxidation state.</p><p>In the final chapter of this thesis, we document the presence of an abundant and diverse set of microRNAs in the mature erythrocytes of healthy and diabetic cats. While their function in the mature erythrocyte remains unknown, a difference was found in the microRNA expression patterns of diabetic and healthy cats. Our data uncovered severe bias in the microRNA sequencing such that the expression levels of some microRNAs appeared to be artificially increased and other diminished. The library construction kit used, appeared to be the cause of this bias. Among the 899 erythrocyte microRNAs sequenced, 12 differentially abundant microRNAs were identified in diabetic cats, however only 6 were differentially abundant by RT-qPCR. Let-7b, miR-1692, miR-339, miR-486 and a feline specific microRNA were increased in mature RBCs of diabetic cats, while miR-451 was decreased.</p><p><a></a><a></a>In conclusion, we have shown that diabetic cats have evidence of significant systemic protein and lipid oxidation as well as erythrocytic oxidative stress. The new, fluorescent PC content assay developed and validated herein could serve as useful tool to better understand the role and consequence of oxidative stress in feline diabetes or other diseases and to monitor antioxidant treatment. Further, this test could be readily adapted for use in other domestic species. Additionally, we have shown that a set of erythrocytic microRNAs are differently abundant in diabetic in comparison to healthy cats. The significance of such changes is currently uncertain. It could represent adaptation of erythroid precursors to changes in their environment during erythropoiesis and as such, these microRNAs may be useful biomarkers for altered hematopoiesis. If microRNAs play a role in communication between circulating mature RBCs and cells in their surroundings such as endothelial cells, the possibility that changes in their expression in this host cells may result in pathology is an intriguing possibility that need to be further explored.</p>

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Introdução: O objetivo deste estudo foi avaliar o efeito de uma estratégia restritiva de transfusão de hemácias comparada a uma estratégia liberal na evolução clínica de pacientes submetidos à cirurgia cardíaca com circulação extracorpórea. Métodos: Estudo prospectivo, randomizado, e controlado. Foram randomizados 512 pacientes para uma estratégia liberal de transfusão (hematócrito 30%) ou restritiva (hematócrito 24%). Resultados: Os pacientes apresentaram idade média de 60,7 ± 12,5 anos no grupo liberal e 58,6 ± 12,5 anos no grupo restritivo. Em ambos, houve predomínio de pacientes com fração de ejeção normal, mas 13% dos pacientes do grupo liberal e 15% do grupo restritivo apresentavam fração de ejeção abaixo de 40%. A mortalidade ou a morbidade grave em 30 dias foi semelhante nos dois grupos (10% na estratégia liberal e 11% na estratégia restritiva, P=0,518). Não houve diferença entre os grupos em relação às taxas de complicações secundárias. A média da concentração de hemoglobina foi 10,5 0,9 g/dL no grupo liberal e 9,1 1,2 gdL no grupo restritivo (P<0,001). No grupo liberal, 198 pacientes (78%) receberam transfusão de hemácias, e no grupo restritivo 118 pacientes (47%). Independente da estratégia utilizada, o número de transfusão de hemácias foi fator preditor independente para a ocorrência de complicações clínicas graves ou morte em 30 dias (OR=1,21; IC 95%=1,1-1,4, P= 0,002). Conclusão: A estratégia restritiva de transfusão foi tão segura quanto à estratégia liberal em pacientes submetidos à cirurgia cardíaca com circulação extracorpórea. Cada unidade de concentrado de hemácias administrada foi associada a aumento de 1,2 vezes no risco de mortalidade em 30 dias / Introduction: The aim of this study was to evaluate whether a restrictive strategy of red blood cells transfusion is as safe as a liberal one with respect to clinical outcomes. Methods: In this prospective, randomized, controlled clinical trial we randomly assigned 512 patients after cardiac surgery to a liberal strategy of transfusion (to maintain a hematocrit at least at 30%) or to a restrictive one (to maintain a hematocrit at least at 24%). Results: The mean age of patients was 60.7 ± 12.5 year-old in liberal group vs. 58.6 ± 12.5 year-old in restrictive group. In both groups, most patients had normal left ventricular function, but 13% of patients in the liberal group and 15% in the restrictive one presented ejection fraction of less than 40%. The primary end-point - a composite endpoint of 30 day all cause mortality or severe morbidity was similar between groups (10% in the liberal-strategy group vs. 11% in the restrictive-strategy group) (P=0.518). Also, there were no differences between groups with respect to the rates of other complications. Hemoglobin concentrations were maintained at a level of 10.5 ± 0.9 g/dL in the liberal group and 9.1 ± 1.2 g/dL in the restrictive group (P<0.001). A total of 198 patients (78%) in the liberal group and 118 patients (47%) in the restrictive group received a blood transfusion (P<0.001). Independently of the strategy group, the number of transfused RBC units was an independent risk factor for the occurrence of several clinical complications or death at 30 days (HR = 1.21; CI 95%=1.1-1.4, P=0.002). Conclusions: A restrictive transfusion strategy was as safe as a liberal strategy in patients undergoing cardiac surgery. For each RBC unit transfused, transfusion was independently associated with a 1.2-fold higher risk of death at 30 days