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PubMed1985

Studies on the "labile-bound" glucose compartment in erythrocytes: studies on Psammomys obesus (sand rat) and preliminary studies on human erythrocytes.

Enzymatic (glucose oxidase) measurement of glucose concentration in the fluid compartment of Psammomys erythrocytes (Gfe) and of its concentration in the fluid compartment of blood plasma (Gfp) gives the ratio (mean +/- SD): Gfe/Gfp = 1.50 +/- 0.43 (n = 12, 23 degrees C). However, when we added 3H-labeled glucose (G*) in vitro to the whole blood, the ratio after 2 min was G*fe/G*fp = 0.90 (SD 0.11) and after 5 min G*fe/G*fp = 0.97 (SD 0.12). These calculations were based on previous determination of the fractional volumes of the fluid and non-fluid compartments in Psammomys blood. The results suggest that there is more than one compartment of measurable glucose in Psammomys erythrocytes. Glucose undergoes a fast free transfer between the plasma and the erythrocyte fluids, and a much slower transmission to another measurable compartment in the erythrocyte, where it is loosely bound to other molecules. This loosely bound glucose does not participate in the fast kinetic transmission across the erythrocyte membrane, but it is measurable by the glucose-oxidase-based method. Preliminary studies on human erythrocytes lead to similar conclusions.

Animals↗
PubMed1984

Human erythrocyte antigens: II. The In(Lu) gene regulates expression of an antigen on an 80-kilodalton protein of human erythrocytes.

We have previously shown that a murine monoclonal antibody (A3D8) identifies a human erythrocyte protein antigen whose expression is regulated by the Lutheran inhibitor [In(Lu)] gene. In the present study, we demonstrated by immunoprecipitation and Western blot techniques that the antigen defined by A3D8 was on an 80-kD erythrocyte membrane protein. A second 170-kD protein was coprecipitated with the 80-kD protein but failed to show antigen activity by Western blot analysis. The 170-kD protein, when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in two dimensions, was composed of 50- and 30-kD disulfide-linked subunits. In(Lu) Lu[a-b-) erythrocytes differed from Lu(a+b+) or Lu(a-b+) erythrocytes in that In(Lu) deoxycholate erythrocyte membrane extracts contained trace amounts of immunoprecipitable 80-kD protein compared with detergent-solubilized erythrocyte membrane extracts prepared from Lu(a+b+) or Lu(a-b+) subjects.

Animals↗
PubMed1985

A comparison of the pyrimethamine and cycloguanil sensitivities of the pre-erythrocytic and erythrocytic stages of drug-sensitive and -resistant strains of Plasmodium yoelii.

The cycloguanil and pyrimethamine sensitivities of the pre-erythrocytic and erythrocytic stages of a drug-sensitive and drug-resistant strain of Plasmodium yoelii have been compared. With both compounds, and in both parasite strains, the pre-erythrocytic stages were more sensitive to inhibition than were the erythrocytic stages. In the resistant strain the increase in the level of drug tolerance in the erythrocytic stages was paralleled by a corresponding loss of sensitivity in the pre-erythrocytic stages.

Animals↗
PubMed1990

Inhibition of the phosphate self-exchange flux in human erythrocytes and erythrocyte ghosts.

The phosphate self-exchange flux in resealed erythrocyte ghosts and in amphotericin B (5.5 microM) permeabilized erythrocytes has been studied. The phosphate self-exchange flux exhibits an S-shaped concentration dependence and a self-inhibition in permeabilized red cells while in erythrocyte ghosts no self-inhibition of the phosphate flux has been observed. The apparent half-saturation constants and the apparent Hill coefficients were assessed by the double reciprocal Hill plots of 1/JP versus 1/[P]n. The phosphate half-saturation constants amount to approx. 125 mM in ghosts and to about 75 mM in permeabilized cells while the apparent Hill coefficients amount to 1.15 and to 1.65 (pH 7.2, 25 degrees C), respectively. Both chloride and sulfate elicit a mixed-type inhibition of the phosphate self-exchange flux. In permeabilized cells, chloride and sulfate shift the flux optimum towards higher phosphate concentrations and reduce the apparent Hill coefficients. In erythrocyte ghosts, the apparent Hill coefficients are insensitive to these anions. The double reciprocal Hill plots indicate a mixed-type inhibition of the phosphate self-exchange flux by DNDS, salicylate and dipyridamole and a noncompetitive inhibition of the phosphate self-exchange flux by phlorhizin. By contrast, the Hill-Dixon plots for chloride and sulfate indicate a competitive inhibition of the phosphate self-exchange flux in erythrocyte ghosts and a mixed-type inhibition in permeabilized cells and provide Hill coefficients of greater than unity for chloride and sulfate. The Dixon plots for DNDS, salicylate, phlorhizin and dipyridamole show a noncompetitive inhibition of the phosphate flux and provide apparent Hill coefficients of 0.95-1.0 for inhibitor binding. Using the Debye-Hückel theory, the effects of ionic strength upon phosphate transport and inhibitor binding can be eliminated. The results of our studies provide strong evidence for the assumption that electrostatic forces are involved in phosphate transport and in inhibitor binding.

Adult↗
PubMed1985

Strong interactions between a spin-labeled cholesterol analog and erythrocyte proteins in the human erythrocyte membrane.

We have used a spin label analog of cholesterol bearing a nitroxide on the alkyl chain (26-nor-25-doxylcholestanol) to study cholesterol-protein interactions in the human erythrocyte membrane. As judged from the ESR spectrum, the spin label is readily incorporated into the membrane when added from a concentrated ethanolic solution to a cell or ghost suspension. With intact erythrocytes or white ghosts in isotonic buffer, the ESR spectrum is a superposition of a mobile component and a strongly immobilized component (outer hyperfine splitting 61-63 G). The latter corresponds to approx. 45% of the signal, a percentage which is barely affected by varying the temperature between 5 and 37 degrees C. Removal of the cytoskeletal proteins spectrin and actin by low ionic strength treatment or of all extrinsic proteins by alkali treatment of ghosts reduces the immobilized fraction to approx. 25%. The effect of controlled proteolysis of intrinsic proteins was also tested. Pre-treatment of cells with chymotrypsin or pre-treatment of unsealed ghosts with trypsin has no effect on the ESR spectrum obtained with alkali-treated membranes. On the other hand, after chymotrypsin treatment of unsealed ghost, which reduces the band 3 protein to a 17.5 kDa membrane fragment, the strongly immobilized component is no longer observable. These data show that the cholesterol analog 26-nor-25-doxylcholestanol interacts strongly with one or several proteins of the erythrocyte membrane. That the intrinsic protein band 3 is involved is suggested by the disappearance of the immobilized fraction occurring upon chymotrypsin digestion of this protein. Our results are thus consistent with the proposal of a selective cholesterol-band 3 interaction in the erythrocyte membrane (Schubert, D. and Boss, K. (1982) FEBS Lett. 150, 4-8). Our data also suggest that this interaction is influenced by cytoskeletal proteins, an effect which can be explained considering the known linking of band 3 to the erythrocyte cytoskeleton via ankyrin. Experiments have also been carried out with 3-doxylandrostanol, a more commonly used cholesterol spin-label analog. With this spin label, at all temperatures investigated, we found it impossible to demonstrate unambiguously the existence of two spectral components. It is suggested that 26-nor-25-doxylcholestanol is a better reporter of cholesterol behavior in membranes.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1995

Conductometric study of erythrocytes during centrifugation. I. Size distribution of erythrocytes.

Sedimentation of hardened erythrocytes in a centrifugal field was studied by time recording of the current chamber in the longitudinal and the transversal directions relative to the cells' movement. The results clearly indicate the existence of an erythrocyte concentration profile during centrifugation. The rates of both longitudinal and transversal current alteration increase with centripetal acceleration and with falling cell concentration. The pellet formed from hardened cells represents virtually incompressible body. It is shown that erythrocyte shape affects the pellet conductivity. Analysis of the data using the modified Stokes' law enables calculation of the cell size distribution. The modal size of macrocytes, normal erythrocytes and two samples of microcytes thus measured was 3.40, 3.01, 2.63 and 2.83 microns, respectively. These data demonstrate that conductometric analysis is useful for investigating abnormalities in erythrocyte size.

Blood Sedimentation↗
PubMed1995

Changes of erythrocyte ouabain maximum binding after birth in neonates--in relation to erythrocyte sodium and potassium concentrations.

Erythrocyte ouabain maximum binding (Vmax level) represents the number of molecules of Na-K ATPase on the erythrocyte membrane. Erythrocyte Vmax levels and sodium potassium concentrations were studied in 38 mature and 57 premature infants, including 40 very low birth weight infants, 41 children and 16 adults, in order to clarify the development of erythrocyte Na-K ATPase related to mineral balance and thermogenesis. Vmax levels were the highest (22.9 +/- 8.9 nmol/l cells) for premature infants; correlated negatively with gestational age (r = -0.77, P < 0.01). Vmax levels correlated positively with the ratio of erythrocyte potassium to sodium concentration (IC-K/Na) at < 20 nmol/l cells of Vmax levels (r = 0.72, P < 0.01), but not at > or = 20 nmol/l cells (r = 0.23). Vmax levels in very low birth weight infants, especially < 28 weeks postconception, decreased gradually with postnatal days. Ln(Vmax) levels correlated negatively with postconceptional age (r = -0.75, P < 0.01). Under 28 weeks postconception, Vmax levels were high, but not correlated with IC-K/Na. It is probable that individual Na-K ATPase molecules may be less active, and the large numbers of Na-K ATPase molecules may compensate for the individual lower activity.

Adolescent↗
PubMedDate not supplied

Disruption of erythrocyte rosettes and agglutination of erythrocytes infected with Plasmodium falciparum by the sera of Papua New Guineans.

People living in areas endemic for Plasmodium falciparum develop humoral responses which may contribute to protection against clinical disease but the specificity of such protective antibody responses remains to be defined. Antibodies disrupting erythrocyte rosettes have been associated with protection against cerebral malaria, and antibodies agglutinating infected erythrocytes with reduced episodes of clinical disease. We have studied the capacity of serum from Papua New Guinean adults and children with a spectrum of malaria exposure, including children and adults at the time of clinical disease, to disrupt erythrocyte rosettes and cause agglutination of infected erythrocytes. Using a single parasite isolate, almost all sera from adults from highly endemic areas agglutinated infected erythrocytes, and the majority disrupted rosettes, in some cases at greater titres than hitherto described. There was a correlation between rosette disruption and agglutination in highly exposed adults. Rosette disrupting antibodies were equally frequent in children with cerebral and uncomplicated malaria. Antibodies causing rosette disruption were frequent only in adults with a long history of malarial exposure. Rosette disrupting antibodies do not appear to protect Papua New Guinean children or adults against cerebral malaria.

Adult↗
PubMed1980

Utilization of membranous lipid substrates by membranous enzymes. Hydrolysis of sphingomyelin in erythrocyte 'ghosts' and liposomes by the membranous sphingomyelinase of chicken erythrocyte 'ghosts'.

Incubation at 37 degrees C of haemolysed chicken erythrocytes ('chicken erythrocyte ghosts') resulted in hydrolysis of the membrane sphingomyelin, suggesting an activation of a latent sphingomyelinase during the haemolysis procedure. When this incubation was continued for several hours, the entire sphingomyelin of the erythrocyte 'ghosts' was hydrolysed and membranes were obtained that were devoid of sphingomyelin, but had an active sphingomyelinase. Mixing the latter membranes with human erythrocyte 'ghosts' or positively charged liposomes led to hydrolysis of the sphingomyelin in these two membranes. This suggested that, after haemolysis, the activated sphingomyelinase in the membrane of the chicken erythrocyte 'ghosts' could hydrolyse sphingomyelin in its own membrane ('intramembrane utilization') or adjacent membranes ('intermembrane utilization').

Animals↗
PubMed1977

Role of sialic acid in survival of erythrocytes in the circulation: interaction of neuraminidase-treated and untreated erythrocytes with spleen and liver at the cellular level.

Sialidase (neuraminidase; acylneuraminyl hydrolase; EC 3.2.1.18)-treated erythrocytes obtained from different species are susceptible to rapid elimination from the circulation and are sequestered in the liver and spleen. The present studies were concerned with the mechanism of this clearance and how it may relate to the normal physiological process of removing senescent erythrocytes from the circulation. The results obtained indicate a preferential recognition of sialidase-treated as compared to normal erythrocytes by mono-nuclear spleen cells and Kupffer cells of the liver. This recognition manifests itself in both autologous and homologous systems by adhesion of the complementary cells in the form of rosettes, and as such could explain the removal of enzyme-treated erythrocytes from the circulation with their accumulation in liver and spleen. This phenomenon may represent a normal physiological mechanism for removal of senescent erythrocytes containing decreased sialic acid.

Animals↗
PubMed1990

Distribution of disulfiram and its chief metabolites over erythrocyte cell membranes and inactivation of erythrocyte aldehyde dehydrogenase activity.

The distribution of disulfiram (Antabuse over erythrocyte cell membranes and the inhibitory action of the parent drug and its metabolites on a disulfiram sensitive erythrocyte isozyme of aldehyde dehydrogenase (ALDH) was investigated in intact and haemolyzed human erythrocytes. These studies showed that not only disulfiram but also its bis(diethyldithiocarbamato) copper complex (Cu(DDC)2) were distributed over the erythrocyte cell membranes. In addition, disulfiram was the only substance examined that inactivaed erythrocyte ALDH, a reaction which was dependent on the concentration of disulfiram added.

Acetaldehyde↗
PubMed2003

Regulation of K-Cl cotransport during reticulocyte maturation and erythrocyte aging in normal and sickle erythrocytes.

The age/density-dependent decrease in K-Cl cotransport (KCC), PP1 and PP2A activities in normal and sickle human erythrocytes, and the effect of urea, a known KCC activator, were studied using discontinuous, isotonic gradients. In normal erythrocytes, the densest fraction (d approximately 33.4 g/dl) has only about approximately 5% of the KCC and 4% of the membrane (mb)-PP1 activities of the least-dense fraction (d approximately 24.7 g/dl). In sickle and normal erythrocytes, density-dependent decreases for mb-PP1 activity were similar (d50% 28.1 +/- 0.4 vs. 27.2 +/- 0.2 g/dl, respectively), whereas those for KCC activity were not (d50% 31.4 +/- 0.9 vs. 26.8 +/- 0.3 g/dl, respectively, P = 0.004). Excluding the 10% least-dense cells, a very tight correlation exists between KCC and mb-PP1 activities in normal (r2 = 0.995) and sickle erythrocytes (r2 = 0.93), but at comparable mb-PP1 activities, KCC activity is higher in sickle erythrocytes, suggesting a defective, mb-PP1-independent KCC regulation. In normal, least-dense but not in densest cells, urea stimulates KCC (two- to fourfold) and moderately increases mb-PP1 (20-40%). Thus mb-PP1 appears to mediate part of urea-stimulated KCC activity.

Adult↗
PubMed1985

Sialic acid content of erythrocytes in uremic patients. Correlation with the age distribution of erythrocytes as assessed by glutamic oxaloacetic transaminase determination.

In a previous study we suggested that an enrichment in young red blood cells (RBC) should occur in the erythrocyte population of uremic-anemic patients. This change in RBC age distribution together with the fact that young cells were reported to be richer in sialic acid would provide an explanation for the observed lack of difference in sialic acid content between patients' and controls' whole erythrocyte populations in spite of an increased neuraminidase activity found to be present in patients' serum. To verify this assumption glutamic oxaloacetic transaminase (GOT) activity, which is an erythrocyte age index, and sialic acid were determined in low and high density fractions separated by centrifugation of packed cells representing young and old RBC, respectively, from two groups of 8 individuals with chronic renal failure and two groups of controls. GOT was determined also in whole erythrocyte populations. Mean GOT activity was significantly higher in the young fractions compared to the old of both patients' and control RBC (14.9 vs. 7.8 and 12.4 vs. 7.5 IU/g Hb). Activity of the whole RBC population was significantly higher in uremics as compared to controls (11.7 vs. 5.6 IU/g Hb) which is compatible with a lower median erythrocyte age. Mean sialic acid was higher in the young fractions as compared to the old (42.7 vs. 35.3 nmol/10(9) cells in controls and 48.9 vs. 43.0 nmol/10(9) cells in patients). These differences together with an enrichment in young cells would compensate for the eventual loss of sialic acid in the whole population resulting from an increased neuraminidase-like activity in patients' serum.

Aspartate Aminotransferases↗
PubMed1979

Regulation of the interaction of purified human erythrocyte AMP deaminase and the human erythrocyte membrane.

The binding of purified human erythrocyte AMP deaminase to human erythrocyte membranes and the effect of binding on enzyme catalytic activity was investigated. AMP deaminase binds preferentially and specifically to the cytoplasmic surface of the erythrocyte membrane. The binding is saturable, reversible, and responsive to alterations of pH, of ionic strength, and of ATP and AMP concentrations. A limited number (approximately equal to 2.2 X 10(4) per erythrocyte) of apparently homogeneous high affinity (Ka approximately equal to 2.6 X 10(7) M-1) binding sites is present. The stability of purified and endogenously bound AMP deaminase is markedly improved by the interaction with the membrane, whereas the catalytic activity of AMP deaminase is sharply reduced. AMP deaminase displaces membrane bound glyceraldehyde 3-phosphate dehydrogenase in roughly a dose-response manner. No evidence for binding of AMP deaminase to spectrin or band 3 (the G3PD binding protein) was found in sucrose gradients, however. The interaction of AMP deaminase with the erythrocyte membrane may play an important role in the regulation of cellular adenine nucleotide metabolism.

AMP Deaminase↗
PubMed1999

Involvement of erythrocyte aggregation and erythrocyte resistance to flow in acute coronary syndromes.

The objective of the study was to identify the relative importance of erythrocyte flow resistance and aggregation in acute and chronic coronary syndromes. 117 subjects in five groups were studied: (1) 34 patients shortly after acute myocardial infarction (AMI) before reperfusion therapy; (2) 27 patients with unstable and (3) 21 with stable angina pectoris (AP); (4) 14 age-matched control patients and (5) 21 healthy volunteers. Single erythrocyte transit times were measured using the Cell Transit Analyser. Shear dependent elongation and aggregation was measured by a modified computerized Myrenne aggregometer. Leukocyte count was increased in coronary artery disease (CAD), especially in acute syndromes (mean +/- SD for groups 1-5): 12.2 +/- 4.5; 10.0 +/- 5.4; 8.0 +/- 2.0; 8.0 +/- 3.7; 7.0 +/- 2.0 (pl(-1))). Platelets, hematocrit, fibrinogen, alpha2-macroglobulin did not differ between the groups. Plasma viscosity (mPas) was elevated in AMI and stable AP: 1.34 +/- 0.10; 1.30 +/- 0.09; 1.32 +/- 0.08; 1.27 +/- 0.07; 1.27 +/- 0.05. Erythrocyte filtrability was not different as was the shear dependent deformation. Aggregation parameters such as gammaTmin were elevated in CAD: 180 +/- 70; 159 +/- 60; 166 +/- 59; 115 +/- 43; 113 +/- 51 (s(-1)). Erythrocyte deformability, measured with two independent methods, does not appear to contribute to the pathophysiology of acute coronary syndromes. Erythrocyte aggregation and plasma viscosity were again found increased both in unstable and stable coronary disease. It is unlikely that increased red cell aggregation contributes to emergence of AMI.

Acute Disease↗
PubMed2001

Erythrocyte deformability and erythrocyte aggregation in preeclampsia.

One of the features of preeclampsia is impaired blood rheology due to altered erythrocyte aggregation and erythrocyte deformability. We investigated these two parameters which affect the viscosity of blood, along with serum and intraerythrocytic magnesium concentrations, immunoglobulin titres and fibrinogen concentration in 12 preeclamptic women. Eighteen (18) other non-preeclamptic, gestation-matched women acted as controls. Erythrocyte deformability, expressed as elongation index (EI), and erythrocyte aggregation expressed as aggregation half-time (t 1/2) were measured with the Laser-assisted Optical Rotational Cell Analyser (LORCA). Serum and intraerythrocytic magnesium concentrations were analysed by atomic absorption spectrometry, immunoglobulin titres by radial immunodiffusion and fibrinogen concentration by a clot weight technique. There was no statistically significant difference in these parameters between preeclamptics and controls suggesting that erythrocyte deformability and aggregation as well as serum and intraerythrocytic concentrations, fibrinogen levels and immunoglobulin titres are not altered in preeclampsia. Further investigations are required in severe preeclampsia and in preeclamptic women taking magnesium sulphate supplement.

Adolescent↗
PubMed1992

The association between erythrocyte internal viscosity, protein non-enzymatic glycosylation and erythrocyte membrane dynamic properties in juvenile diabetes mellitus.

The association of intracellular viscosity of red blood cells and the dynamic properties of erythrocyte membranes in children suffering from diabetes has been investigated by means of ESR spectroscopy. It has been revealed that the slight decrease in the ratio hw/hs of maleimide bound to membrane protein-SH groups of erythrocytes in diabetes may ensue from the enhanced membrane protein immobilization in the plane of lipid bilayer. These alterations were accompanied by a corresponding increase in the relative rotational correlation time (tau c) of iodoacetamide spin label, thus suggesting that the conformational changes in membrane proteins may occur at both the intrinsic and more exposed thiol groups. The membranes of diabetic red blood cells were more glycosylated than those of relevant controls, and the extent of glycosylation was found to correlate significantly with h + 1/h0 and tau c (r = -0.652, P < 0.01 and r = 0.609, P < 0.01). Further, the conformational alterations in erythrocyte membranes from diabetic subjects were accompanied by a significant increase in the mobility parameter (h + 1/h0) of haemoglobin molecules in diabetic erythrocytes. The latter changes correlated well with the enhanced intracellular viscosity of diabetic red blood cells and the level of glycosylated haemoglobin. We conclude that the alterations in membrane lipid-protein interactions together with the increased glycosylation-derived internal viscosity may consequently imply altered viscoelastic properties of erythrocyte membranes and, underlying the impaired deformability of red blood cells in the diabetic state, contribute to the development of late diabetic sequelae.

Adolescent↗
PubMed1989

[Erythrocyte volume distribution curves: a parameter for evaluating erythrocyte preparations].

The volume distribution of erythrocytes in ACD-AG blood and in human erythrocyte concentrations was investigated by means of computer-assisted techniques of hematological analysis. The storage-dependent distribution was described by the content of discrete class areas. Erythrocytes with a volume below 72 fl are only slightly capable of changing their volume. Their condition predisposes them to selection in the receiver's organism. Their percentage amount correlates with the share of cells ineffective of transfusion. The concentration of cells with a volume above 72 fl is discussed with ACD-AG blood (78% on the 42nd day), with CDS-AG erythrocyte concentrate (66% on the 20th day) and with SAG-M erythrocyte concentrate (74% on the 35th day) together with findings about the transfusional survival rate.

Blood Preservation↗