Influência de índices hematimétricos e bioquímicos de pacientes submetidas à cirurgia bariátrica sobre a estabilidade de membrana de eritrócitos

Abstract

CHAPTER II: The stability of the erythrocyte membrane, which is essential for maintenance of cell functions, occurs in a critical region of fluidity, which depends largely on its composition and the composition and characteristics of the medium. As the composition of the erythrocyte membrane is influenced by several blood variables, the stability of the erythrocyte membrane must have relations with them. The present study aimed to evaluate, by bivariate and multivariate statistical analyses, the correlations and causal relationships between hematological and biochemical variables and the stability of the erythrocyte membrane against the chaotropic action of ethanol. The validity of this type of analysis depends on the homogeneity of the population and on the variability of the studied parameters, conditions that can be filled by patients who undergo bariatric surgery by the technique of Roux-en-Y gastric bypass, since they will suffer feeding restrictions that have great impact on their blood composition. Pathway analysis revealed that an increase in hemoglobin leads to decreased stability of the cell, probably through a process mediated by an increase in MCV. Furthermore, an increase in the MCH leads to an increase in the erythrocyte membrane stability, probably because higher values of MCH are associated to smaller quantities of RBC and larger contact area between the cell membrane and ethanol present in the medium. CHAPTER III: The need to treat obesity, a growing worldwide public health problem, has led to an increase in performing bariatric surgery, particularly the Roux-en-Y gastric bypass. The sudden change in eating habits, resulting from this type of surgery, leads to abrupt changes in the body. This study analyzed the correlation between the osmotic stability of erythrocytes and various biochemical and hematological indices in a population consisting of 24 female volunteers, before and at four different times after surgery, distributed along eight weeks, what allowed the generation of 120 sampling points. The osmotic stability of erythrocytes proved to be of great importance for understanding the meaning of the redcell distribution width (RDW), because the stability variables (1/H50 and dX) were positively correlated with this hematological index. However, the stability variables and RDW seem to suffer different influences from other variables, as the LDL-cholesterol (LDL-C), because only RDW has increased throughout time. Indeed, the stability of variable 1/H50 showed positive correlation with the blood levels of LDL-C, which declined throughout time. Path analysis showed that the body mass index (BMI) has an indirect effect, mediated by RDW, on the osmotic stability of erythrocytes. The correlations that the osmotic stability variables presented with RDW may help to understand the origin of the predictive ability of this hematological index in relation to various pathological conditions.