Surface properties of crosslinked erythrocytes as studied by counter-current distribution in aqueous polymer two-phase systems (original) (raw)
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Electrochemical interactions between erythrocyte surfaces
Thrombosis Research, 1976
The mechanism of aggregation of human red blood cells (RBCs) by neutral macromolecules was investigated with the use of suspensions of normal and neuraminidase-treated RBCs in dextran with a molecular weight of 74,000. Aggregation (reflectometry) of normal RBCs reached a maximum at dextran concentration of 4 g% and decreased to zero at 9 g%, while the surface adsorption of dextran continued to increase. Aggregation of neuraminidase-treated RBCs increased with dextran concentrations up to 20 g%, and the surface adsorption of dextran showed a similar concentration dependence. In the normal RBCs, high dextran concentrations caused an increase in surface potential, similar to the effect of decreasing the ionic strength. The electrostatic repulsive force (Fe) between adjacent RBC surfaces in the rouleaux was calculated and used to estimate the force of RBC aggregation due to macromolecular bridging. Mechanical shearing affected RBC aggregation in two ways: moderate shearing facilitates aggregation by increasing cell encounter, whereas high shears cause dispersion of the aggregates. The balance of forces at the cell surfaces is such that RBC aggregation occurs when the macromolecular bridging force exceeds the disaggregating forces due to electrostatic repulsion and mechanical shearing.
Role of Surface Electric Charge in Red Blood Cell Interactions
The Journal of General Physiology, 1973
The role of the surface charge of human red blood cells (RBC's) in affecting RBC aggregation by macromolecules was studied by comparing the behavior of normal RBC's with that of RBC's treated with neuraminidase, which removes the sialic acids from the cell membrane and reduces the zeta potential. RBC aggregation in dextrans with different molecular weights (Dx 20, Dx 40, and Dx 80) was quantified by microscopic observation, measurement of erythrocyte sedimentation rate, and determination of low-shear viscosity. Dx 20 did not cause aggregation of normal RBC's, but caused considerable aggregation of neuraminidase-treated RBC's. Neuraminidase-treated RBC's also showed stronger aggregation than normal RBC's in Dx 40 and 80. Together with the electron microscopic findings that the intercellular distance in the RBC rouleaux varies with the molecular size of dextrans used, the present study indicates that the surface charge of RBC's inhibits their aggregatio...
Human red blood cell aging: correlative changes in surface charge and cell properties
Journal of Cellular and Molecular Medicine, 2011
and other biomaterials thereby altering cell structures, some properties and functions. Such cell damage very likely underlies the serious adverse effects of blood transfusion. However, a controversy has remained since 1961-1977 as to whether with aging, the RBCs, suffering loss of NANA, do have a decreased charge density. Any correlation between the changes in the cell properties with cell aging is also not clear. Therefore, to remove the ambiguity and uncertainty, we carried out multiparameteric studies on Percoll fractions of blood of 38 volunteers (lightestyoung-Y-RBCs, densest-old-O-RBCs, two middle fractions).We found that there were striking differences between the properties of Y-RBCs and O-RBCs. The -potential of Y-RBCs decreased gradually with aging. Studies in parallel on RBC fractions incubated with both positively charged quantum dots and Sambucus Nigra-fluorescein isothiocyanate (FITC) along with their -potentials provide for the first time direct visual evidence about the lesser amount of charge density and NANA on O-RBCs, and a collinear decrease in their respective -potentials. Close correlation was found between the surface charge on an aging RBC and its structure and functions, from the cell morphology, the membrane deformability to the intracellular Hb structure and oxidation ability. This quantitative approach not only clarifies the picture but also has implications in biology and medicine.
Journal of Chromatography B: Biomedical Sciences and Applications, 1996
Carrier rat erythrocytes loaded with exogenous substances ([~25I]carbonic anhydrase) by hypotonic-isotonic dialysis become heterogeneous cell populations that can be fractionated using the counter-current distribution (CCD) technique. Two well-defined low-and high-partition ratio, G, subpopulations are obtained in charge-sensitive dextran-polyethylene glycol two-phase systems. The low-G subpopulation, which contains the most fragile and surface-altered cells, as deduced from their osmotic fragility curves and partition behaviour, respectively, presents a high amount of exogenous substance incorporated (134.6 cpm/106 cells). The high-G subpopulation, that contains cells similar to the control or isotonically dialyzed cells presents a lower amount of exogenous substance incorporated (69.8 cpm/106 cells). Cells in this high-G subpopulation seem to be fractionated, like the controls, according to ageing as suggested by the decline of the pyruvate kinase specific activity from the left-to the right-hand side of the CCD profile.
Electrical properties of the red blood cell membrane and immunohematological investigation
Revista Brasileira de Hematologia e Hemoterapia, 2011
Hemagglutination is widely used in transfusion medicine and depends on several factors including antigens, antibodies, electrical properties of red blood cells and the environment of the reaction. Intermolecular forces are involved in agglutination with cell clumping occurring when the aggregation force is greater than the force of repulsion. Repulsive force is generated by negative charges on the red blood cell surface that occur due to the presence of the carboxyl group of sialic acids in the cell membrane; these charges create a repulsive electric zeta potential between cells. In transfusion services, specific solutions are used to improve hemagglutination, including enzymes that reduce the negative charge of red blood cells, LISS which improves the binding of antibodies to antigens and macromolecules that decrease the distance between erythrocytes. The specificity and sensitivity of immunohematological reactions depend directly on the appropriate use of these solutions. Knowledge of the electrical properties of red blood cells and of the action of enhancement solutions can contribute to the immunohematology practice in transfusion services.
Cytosol-Membrane Interface of Human Erythrocytes
Biophysical Journal, 1983
The resonance energy transfer from donors embedded in the membrane of erythrocytes to the cytosol hemoglobin has been measured by comparing the donors' fluorescence decay in ghosts and in intact cells. A series of n -(9-anthroyloxy) stearic acids (n-AS) (n = 2, 6, 9, 12) and similar probes were used as donors, and their locations within the outer leaflet of the phospholipid bilayer were determined from their average efficiency of energy transfer, ( T ). The energy transfer data for several membrane probes were analyzed according to a simple semiempirical model, in which the heme acceptors are assumed to form a semiinfinite continuum beyond a plane, whose normal distance (d) from particular donors may be determined if the heme density in the cytosol boundary layer is known. The hemoglobin concentration in the erythrocytes was varied by suspending the cells in buffers of different ionic strengths. This made it possible to study the ionic strength dependence of the heme concentration averaged over the cell (hc), as well as that in the boundary layer (hb). Both level off above approximately 600 mosM, as does the ratio hb/hC. By using the maximum heme concentration that can be obtained in osmotically shrunken cells as a limiting value, hb is estimated to be 17 mM or less, under physiological conditions; and from the measured (T ) for various probes, the distance d was found to range from 40 A for 2-AS to 31 A for 12-AS and 26 A for 9-vinyl anthracene (9-VA). It is concluded that the hydrophobic probe 9-VA is located near the center of the phospholipid bilayer and that the cytosol hemoglobin is in contact with the inner membrane surface, or nearly so. This conclusion is valid for oxy-and deoxy-hemoglobin, and is shown to be independent of several systematic errors that might arise from the simple assumptions of the model used. The steady-state fluorescence anisotropy of the probes was found to decrease as they approach the bilayer's central plane. The methodology developed here may be used to extend studies of cytosol membrane interactions in ghost systems to intact cells, and is useful in the investigation of the morphology of normal and pathological intact erythrocytes.
Electrophoresis, 2000
Covalent binding of polyethylene glycol to the surface of red blood cells as detected and followed up by cell electrophoresis and rheological methods Cyanuric chloride activated polyethylene glycol (PEG)-5000 was covalently coupled to murine and human red blood cells (pegylated RBC). Our purpose was to camouflage RBC receptors, which is necessary for parasite invasion, a process essential to sustain parasitemia. Cell electrophoretic mobility analysis (CEM) of pegylated RBC distinguished a new population of cells bearing characteristic CEM. Pegylation of RBC also modified their rheological properties, which were documented by evaluation of cell deformability (based on cell transit time through calibrated micropores) and cell aggregation (as measured by ultrasonic interferometry). Homologous transfusion of pegylated RBC into murine malaria-infected mice had no significant effect on the cerebral malaria death rate in Plasmodium berghei-infected mice, but it reduced the peripheral blood parasitemia by a factor 2 while in Plasmodium yoelii infected mice, the parasitemia was dramatically reduced by a factor of 4. These experiments demonstrate that transfusion of pegylated RBC may inhibit peripheral parasitemia. Cell electrophoresis appears to be a useful tool to allow in vivo detection and to investigate the fate of transfused pegylated RBC.
The Loading of Human Erythrocytes With Small Molecules by Electroporation
2005
The technology for loading the cell with membrane-impermeable substances by means of electroporation consists of the following three stages: (i) the creation of pores permeable for the desired substance; (ii) the introduction of a substance into the cell cytosol; and (iii) the restoration of the membrane barrier function. In this paper, the experimental data on the loading of human erythrocytes
Structural alteration of erythrocyte membrane during storage: a combined electrical …
ZEITSCHRIFT FUR …, 2001
Erythrocytes, Dielectric Measurements, Flow-Cytometric M easurem ents Alterations in the electrical passive param eters of red blood cell mem branes occurring during storage have been investigated by means of two different experimental approaches, i.e., ra diowave dielectric spectroscopy measurem ents and flow-cytometric measurements. We ob served a correlation between the appearance of phosphatidylserine molecules in the outer leaflet of the cell membrane and the occurrence of a change in the electrical passive mem brane parameters. The electrical reorganization of the membrane, resulting in an increase of its conductivity and permittivity after 5-7 days from blood storage, can be considered as a precursory event for the loss of asymmetry in the lipid distribution across red blood cell membrane.