Methods: A new protocol for in vitro red blood cell glycation.

During diabetes, the characteristic hyperglycemia can induce red blood cell glycation. Several researchers have proposed different protocols to perform an in vitro model to study this phenomenon. In this article, some of the most important in vitro glycation protocols available in the bibliography were compared to each other. The incubation parameters as the suspension medium, glucose concentration, red blood cell concentration, time, and temperature were analyzed. Also, several assays were carried out in our laboratory, and glycated hemoglobin, erythrocyte aggregation and viscoelasticity were determined for the protocol validation. Based on the bibliographic analysis and our experimental results, an optimal protocol for in vitro glycation of red blood cells is presented.

In vitro alteration on erythrocytes mechanical properties by propofol, remifentanil and vecuronium.

Several studies report flow disturbance and microcirculation disorders upon anesthesia treatment. These alterations are often related to blood rheology changes. In this work, it was attempted to make a detailed description of the alterations in erythrocyte mechanical properties by the action of propofol, remifentanil, and vecuronium. For this, an in vitro study was performed on red blood cell samples from healthy donors incubated with solutions of propofol (4 µg/mL whole blood), remifentanil (10 ng/mL plasma), and vecuronium (0.15 µg/mL plasma). Erythrocyte viscoelastic parameters were determined by octuplicate using a Reómetro Eritrocitario. Also, a Wilcoxon signed rank-test with Yates correction for continuity was performed to analyze the overall alteration in the mechanical properties of erythrocytes. Statistical analysis showed that the three studied anesthetics changed the erythrocyte mechanical properties at different parts of the membrane. These results would imply an interaction of these anesthetics with the erythrocyte membrane. Finally, this could conduce to alterations in microcirculation.

Descriptive parameters of the erythrocyte aggregation phenomenon using a laser transmission optical chip.

The study of red blood cell (RBC) aggregation is of great interest because of its implications for human health. Altered RBC aggregation can lead to microcirculatory problems as in vascular pathologies, such as hypertension and diabetes, due to a decrease in the erythrocyte surface electric charge and an increase in the ligands present in plasma. The process of erythrocyte aggregation was studied in stasis situation (free shear stresses), using an optical chip based on the laser transmission technique. Kinetic curves of erythrocyte aggregation under different conditions were obtained, allowing evaluation and characterization of this process. Two main characteristics of blood that influence erythrocyte aggregation were analyzed: the erythrocyte surface anionic charge (EAC) after digestion with the enzyme trypsin and plasmatic protein concentration in suspension medium using plasma dissolutions in physiological saline with human albumin. A theoretical approach was evaluated to obtain aggregation and disaggregation ratios by syllectograms data fitting. Sensible parameters ( Amp 100 , t 1 \ 2 ) regarding a reduced erythrocyte EAC were determined, and other parameters (AI, M-Index) resulted that are representative of a variation in the plasmatic protein content of the suspension medium. These results are very useful for further applications in biomedicine.

Hemorheological in vitro action of propofol on erythrocytes from healthy donors and diabetic patients.

Drugs used during anesthesia might induce disturbance on microcirculation due to their systemic cardiovascular actions and to direct hemorheological effects. A comparative investigation of the hemorheological alterations related to in vitro propofol treatment of red blood cells (RBCs) from healthy and diabetic volunteers is presented here. Viscoelasticity and aggregation of RBCs from type 2 diabetic patients (DBT) and healthy donors (HD) were studied from RBCs incubated with propofol near steady-state concentration. 'S parameter', which measures the aggregation degree, was obtained using digital analysis of microscopic images. Erythrocyte viscoelasticity parameters were determined using an Erythrocyte Rheometer. Results obtained from DBT samples showed an increase of 10% or more in aggregation due to the propofol action. The phase shift between erythrocyte response and oscillating shear stress applied at 1 Hz was altered by propofol treatment of erythrocyte from HD and DBT. Propofol could produce slight alterations in the rheological behavior of erythrocyte from HD and DBT, at concentrations near those of steady state. Moreover, this anesthetic could induce an adverse effect in DBT, particularly on erythrocyte aggregation. The observed hemorheologic alteration would increase the possibility of microcapillary obstruction. Hence, this type of study [0] would prove relevant to avoid possible postoperative complications.