Impairment of erythrocytes incubated in glucose medium: a wavelet-information theory analysis.

This study investigates the effects produced by an increased concentration of glucose in a suspending medium on the erythrocytes Information Theory quantifiers. Erythrocytes, which were obtained from eight healthy volunteers, were washed and incubated in vitro with glucose solutions at different concentrations. The measured Wavelet-based Information Theory quantifiers include the Relative Wavelet Energy (RWE), the Normalized Total Wavelet Shannon Entropy (NTWS), MPR-Statistical Complexity Measure (SCM) and entropy-complexity plane. The results show that the increase in glucose concentration does not produce significant changes on the RWE, while significant ones on the NTSE, which combined with SCM values allow to identify different behaviour for all the different populations in the entropy-complexity plane. Modification in the hemorheological properties of cells could be clearly detected with these Wavelet-based Information Theory quantifiers.

Alterations to complex viscoelasticity of erythrocytes during storage.

Rheological alterations produced during the storage of human erythrocytes were studied by means of in vitro viscoelastic parameters. Weekly aliquots of packed red blood cells (PRBC) and whole blood (WB) stored in CPD-adenine were studied for 35 days. Samples were analyzed in Erythrodeformeter both in stationary and oscillating regime. We found that erythrocyte deformability index and all complex viscoelastic parameters are modified by storage. Plasma viscosity and blood viscosity were measured in a cone/plate Viscometer. Blood viscosity at high shear rates shows variations related to conservation time, which are in correlation with the variations observed in the erythrocyte deformability index. Blood viscosity at low shear rate decreases during storage. Rheological tests would demonstrate some alterations in the structural properties of erythrocyte stored as PRBC. These alterations are less than those found in WB. We conclude that plasmatic proteins play a predominant role in the alteration of rheological behavior of erythrocytes during their storage. Consequently, it is important to evaluate not only cellular components but also plasma.

Complex viscoelasticity of normal and lectin treated erythrocytes using laser diffractometry.

A new method to find directly complex viscoelastic parameters (CVP) of red blood cells (RBC) is presented in this paper. Experimental determinations were carried out in an Erythrodeformeter (Rasia et al., 1986) operating in oscillating mode (0.5 to 3.5 Hz). The Erythrodeformeter performs direct determination of CVP of erythrocytes undergoing sinusoidal shear stresses by laser diffractometry. The measurements lead to the determination of mean values of the four components of erythrocyte complex viscoelasticity. The influence of the alterations induced on erythrocyte membrane by vegetable lactins (Ulex europaeus, wheat germ agglutinin and Enterolobium contorticilicum seeds) was analyzed to verify the sensitivity of this method. Differences observed between the CVP parameters of treated cells and the ones corresponding to control samples (non treated cells) are analyzed. Results obtained from cells treated with wheat germ agglutinin agree with observations published by Smith and Hochmuth (1982). Determinations of RBC complex viscoelasticity carried out by laser diffractometry could become an important tool to understand the influence of the factors associated with alterations of the rheologic properties of RBC membrane, which can affect the in vivo blood flow.