Effect of inositol hexaphosphate-loaded red blood cells (RBCs) on the rheology of sickle RBCs.

Background: The recent in vitro demonstration that inositol hexaphosphate-loaded red blood cells (IHP-RBCs) may reduce the risks of sickling of sickle RBCs (SS RBCs) exposed to hypoxia make these modified RBCs potentially useful in transfused sickle cell anemia (SCA) patients.

Study Design And Methods: Hemorheologic properties of IHP-RBCs, normal RBCs (AA RBCs), SS RBCs, SS RBCs plus AA RBCs, and SS RBCs plus IHP-RBCs were compared under normoxia and/or after hypoxic challenges.

Results: Although IHP-RBCs have reduced deformability compared with SS RBCs or AA RBCs, IHP-RBCs exhibited lower aggregability than AA RBCs and SS RBCs and, when mixed with SS RBCs, the aggregation level was below the one of SS RBCs alone or SS RBCs plus AA RBCs.

Improved viscosity modeling in patients with type 2 diabetes mellitus by accounting for enhanced red blood cell aggregation tendency.

Aims: Distorted wall shear stress (WSS) in patients with type 2 diabetes mellitus (T2DM) may be partly explained by an altered red blood cell aggregation tendency (RAT) on viscosity at low shear rate (SR). The present study evaluates viscosity modeling by implementation of hematocrit and RAT in patients with and without T2DM (non-T2DM).

Methods: A Couette viscometer and LORCA aggregometer provided viscosity and RAT on 6 shear rates in 55 patients (46-78 yrs, 66% male, T2DM: n = 28), following informed consent.

Parameterization of red blood cell elongation index--shear stress curves obtained by ektacytometry.

Measurement of red blood cell (RBC) deformability by ektacytometry yields a set of elongation indexes (EI) measured at various shear stresses (SS) presented as SS-EI curves, or tabulated data. These are useful for detailed analysis, but may not be appropriate when a simple comparison of a global parameter between groups is required. Based on the characteristic shape of SS-EI curves, two approaches have been proposed to calculate the maximal RBC elongation index (EI(max)) and the shear stress required for one-half of this maximal deformation (SS(1/2)): (i) linear Lineweaver-Burke (LB) model; (ii) Streekstra-Bronkhorst (SB) model.

Test 1 analyser for determination of ESR. 1. Practical evaluation and comparison with the Westergren technique.

Background: various modifications of the Erythrocyte Sedimentation Rate (ESR) determination have been suggested since the original Westergren procedure that has been adopted as the gold standard by the International Council for Standardization in Haematology (ICSH). Recently, an automated method, (Alifax Test 1), based on a technique completely different from Westergren, has been introduced.

Material And Methods: In this comparative study, ESR of blood from 680 patients with various rheumatic diseases was determined on both Test 1 and the StaRRsed automated ESR analyser which performs measurements in accordance with ICSH specifications.

Test 1 analyser for determination of ESR. 2. Experimental evaluation and comparison with RBC aggregometry.

Background: Test 1 is a recently introduced technique claiming to determine Erythrocyte Sedimentation Rate (ESR) in 20 s. In contrast to the original Westergren procedure this new technique uses undiluted blood and operates at 37 degrees C. It is hypothesized that Test 1 is in fact an erythrocyte aggregometer and does not measure any sedimentation.

Photometric measurements of red blood cell aggregation: light transmission versus light reflectance.

Red blood cell (RBC) aggregation is the reversible and regular clumping in the presence of certain macromolecules. This is a clinically important phenomenon, being significantly enhanced in the presence of acute phase reactants (e.g.

Red blood cell rheology in patients with chronic venous disease (CVD).

Rheological studies concerning aggregation and elongation of erythrocytes were carried out in 21 patients (mean age 56 years) with chronic venous disease (CVD) and 10 (mean age 45 years) healthy control subjects, with the use of a LORCA device. Higher values of parameters characterizing both erythrocyte elongation (EI) and aggregation (gammathr) in non-control patients than in the control group were found. These values differed significantly ranging from 1.

Small artery remodeling and erythrocyte deformability in L-NAME-induced hypertension: role of transglutaminases.

Background: Hypertension is associated with inward remodeling of small arteries and decreased erythrocyte deformability, both impairing proper tissue perfusion. We hypothesized that these alterations depend on transglutaminases, cross-linking enzymes present in the vascular wall, monocytes/macrophages and erythrocytes.

Methods And Results: Wild-type (WT) mice and tissue-type transglutaminase (tTG) knockout (KO) mice received the nitric oxide inhibitor Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME) to induce hypertension.

Strain hardening of red blood cells by accumulated cyclic supraphysiological stress.

The effect of elevated shear stress upon cellular trauma has been studied for many years, but the effect of long-term cyclic stress trauma on hemorheology has never been explored systematically. This study investigated sublytic trauma of red blood cells (RBCs) caused by repeated exposure to shear stress. A suspension of bovine blood was throttled through a capillary tube (inner diameter 1 mm and length 70 mm) connected to a recirculating flow loop.

HDL cholesterol levels are an important factor for determining the lifespan of erythrocytes.

Objective: Scavenger receptor class B, type I (SR-BI) is a multifunctional receptor that promotes the selective uptake of cholesteryl esters from high-density lipoprotein (HDL). Disruption of SR-BI in mice results in a dramatic increase in HDL cholesterol. Interestingly, mice lacking SR-BI also develop anemia, as evidenced by accumulation of reticulocytes in the circulation.

Laser-assisted optical rotational cell analyzer measurements reveal early changes in human RBC deformability induced by photodynamic treatment.

Background: The ability to deform is important for circulating RBCs in vivo, and earlier studies showed that this property can objectively be measured in vitro by the LORCA. In this study it was investigated whether photodynamic treatment of human RBCs (meant to inactivate contaminating pathogens) affects deformability.

Study Design And Methods: WBC-reduced RBC suspensions (30% Hct) were treated with 1,9-dimethylmethylene blue (DMMB) and red light.