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PubMed2000

[Morphometric analysis of erythrocyte aggregates in vitro: pharmacological application with buflomedil].

Erythrocyte aggregation is usually evaluated through indirect measurements such as the sedimentation rate and rheometric measurements of aggregation and disaggregation thresholds. The aim of this study was a preliminary evaluation of a morphometric approach of aggregates in vitro. A sample of blood (on EDTA) was examined under the microscope, and a picture with magnification X 640 was obtained after stabilization of the cellular structure. The digital image was analyzed with a home made dedicated software that allows the measurement of the cellular density and the evaluation of several shape parameters. Ten samples obtained from different donors were analysed within one hour after blood withdrawal and 24 hours later (preservation temperature: 4 degrees C), with and without adjunction of Buflomedil (4 microg/ml). Results showed an important anti-aggregant effect of Buflomedil administrated in these conditions, both on fresh and preserved blood (p<10(-3)). These results illustrate the potential interest of a morphometric approach to erythrocyte aggregation. They show new pharmacological properties of Buflomedil administered in vitro, which have to be confirmed with a therapeutic administration of the compound.

Densitometry↗
PubMed1993

Ticlopidine improves the enhanced erythrocyte aggregability in patients with cerebral infarction.

BACKGROUND AND PURPOSE: We examined the effect of ticlopidine hydrochloride on the enhanced erythrocyte aggregability in 14 patients with cerebral infarction during the chronic phase (over 1 month after onset). SUMMARY OF REPORT: Ticlopidine (100 mg BID) was administered for 8 weeks. We measured the rate of erythrocyte aggregation (aggregability), using the whole-blood erythrocyte aggregometer that we developed, before and at 4 and 8 weeks after the initiation of ticlopidine administration. Concomitant measurements were made of such blood factors as the hematocrit, albumin-globulin ratio, and fibrinogen concentration. The erythrocyte aggregation rates before and at 4 and 8 weeks after were 0.147 +/- 0.017/s, 0.138 +/- 0.019/s, and 0.133 +/- 0.017/s, respectively. The erythrocyte aggregation rates at 4 and 8 weeks were significantly lower (P < .05 by Bonferroni's modified t test) than those before ticlopidine administration. At 4 and 8 weeks after the initiation of ticlopidine treatment, the hematocrit value and concentration of fibrinogen were also significantly (P < .05) reduced. CONCLUSIONS: Our results suggest that ticlopidine can improve the enhanced erythrocyte aggregability in patients with cerebral infarction during the chronic phase.

Adult↗
PubMed1999

Determination of erythrocyte aggregation.

One of the most common health criteria--erythrocyte sedimentation rate (ESR)--is considered in the paper. It is shown that the simple model presented, based on the generalized Stokes formula, the blood volume conservation law, and the Smoluchowski theory of particles coagulation, makes it possible, on the basis of experimentally recorded sedimentation curves, to identify quantitatively the values of the essential physical parameters of the coupled processes of erythrocyte aggregation and sedimentation. The analytical solution of Smoluchowski equation is used to evaluate the sedimentation and aggregation rate constants. The problem of determining the erythrocyte aggregation rate (EAR) is transformed to a minimization task in which only the experimental results for ESR are needed. Experimentally ESR is measured accurately enough by using an equipment set up just for the purpose. This method of identification could be used as a diagnostic test in hematological laboratories.

Blood Sedimentation↗
PubMed1996

Influence of acute-phase proteins on erythrocyte aggregation.

With the exception of fibrinogen, immunoglobulins, and albumin, little information is available on the effect of acute-phase proteins on erythrocyte aggregation. The objective of this study was to investigate the effects of haptoglobin (Hp), C-reactive protein (CRP), ceruloplasmin (Cp), alpha 1-acid glycoprotein (alpha 1-AGP), and alpha 1-antitrypsin (alpha 1-AT) on the aggregation kinetics and shear resistance of erythrocyte aggregates. The plasma concentration of these proteins was measured in 20 healthy individuals and kept unchanged while the concentration of the protein tested was increased. Adding Hp to concentrations between 2.78 and 4.99 g/l resulted in a significant progressive increase in aggregation kinetics compared with controls. An elevation of the shear resistance of the aggregates was found for CRP at a concentration of 0.438 g/l. By an increase in the concentration of Cp from 4.40 to 9.39 g/l, the aggregation kinetics and the adhesive forces between erythrocytes were significantly increased: No effect on erythrocyte aggregation was observed for alpha 1-AGP, alpha 1-AT, and Cp at concentrations of 2.85, 3.97, and 2.43 g/l, respectively. The molecular mass of the acute-phase proteins, their configuration, and the presence of specific receptors on the erythrocyte membrane are postulated as possible factors influencing erythrocyte aggregation.

Acute-Phase Proteins↗
PubMedDate not supplied

Comparison and simulation of different levels of erythrocyte aggregation with pig, horse, sheep, calf, and normal human blood.

Erythrocyte aggregation levels in pig, horse, sheep, and calf blood samples were investigated and compared to that of normal human blood. The aggregation kinetics and adhesive forces between red cells, and an index of structure of the aggregates were determined with an erythroaggregameter (Regulest, France) at constant hematocrit (0.40 l/l) and temperature (37 degrees C). The adhesive forces and the index of structure in pig blood were close to those of normal human blood. The results for horse blood showed a very high level of aggregation kinetics and adhesive forces between red cells. For sheep and calf blood, little erythrocyte aggregation was found. To simulate different levels of red cell hyperaggregation in humans, a volume of horse plasma was replaced by isotonic NaCl in different proportions (5 to 40% V/V). The kinetics of rouleaux formation and especially the adhesive forces between erythrocytes were systematically decreased, while the index of structure was raised with increasing concentrations of isotonic NaCl. By replacing the porcine plasma with isotonic NaCl, normal and hypoaggregating levels of human red cells were simulated. The aggregation kinetics and the adhesive forces were reduced and the index of structure was raised when the concentration of isotonic NaCl was increased. In summary, large differences in the aggregation parameters were found between mammals. This study also showed that different human erythrocyte aggregation levels can be simulated by diluting the concentration of plasma proteins in equine and porcine bloods.

Animals↗
PubMed1991

Erythrocyte aggregation: bridging by macromolecules and electrostatic repulsion by sialic acid.

Relation between aggregating force (of fibrinogen and IgG) and disaggregating force (due to electrostatic repulsion among erythrocytes) in erythrocyte aggregation was investigated with a rheoscope combining a video camera, an image analyzer and a computer. (i) Erythrocyte aggregation was augmented with the increase of molecular weight of bridging macromolecules as far as examined for fibrinogen and the degradation products and IgG and the related macromolecules, and the augmentation seemed to be dependent on the molecular length of macromolecules. In accelerating the erythrocyte aggregation, fibrinogen was more effective than IgG, and some interaction between fibrinogen and IgG in their coexistence was suggested. (ii) The decrease of sialic acid content on the erythrocyte surface accelerated IgG-induced erythrocyte aggregation much greater than fibrinogen-induced one. (iii) Counteraction between aggregating force and disaggregating force in leading to erythrocyte aggregation was discussed relating to molecular length of bridging macromolecule and electrostatic repulsive force by sialic acid.

Adult↗
PubMed1990

Erythrocyte aggregation: the roles of cell deformability and geometry.

The sedimentation rate of erythrocyte under controlled conditions was used to study the influence of cell deformability and geometry on erythrocyte aggregation. The cell deformability, which is determined by the viscoelastic properties of the membrane, the cell geometry, and the cellular viscosity, was systematically altered. The viscoelasticity of the membrane was gradually decreased with increasing concentrations of glutaraldehyde (0.01-1.0%) or heat treatment at 47.5 degrees C for increasing time intervals (0-80 min), which led to an increase at low concentrations and short incubation and then to a progressive decrease of erythrocyte aggregation. Changes of the osmolality were used to simultaneously alter the cell geometry and cellular viscosity in opposing directions. When the haematocrit level was held constant, the sedimentation rate decreased with increasing osmolality. With a constant erythrocyte number per volume, but changing haematocrit level, the highest sedimentation rate was observed at isotonicity. These results indicate that cell deformability and geometry play an important role in erythrocyte aggregation and sedimentation and may have implications on other cell-cell interactions as well.

Blood Sedimentation↗
PubMed1988

Erythrocyte aggregation as a determinant of blood flow: effect of pH, temperature and osmotic pressure.

The effect of pH, temperature and osmotic pressure on velocity of erythrocyte aggregation was quantitatively examined with a rheoscope combined with a video-camera, an image analyzer and a computer, (a) in an artificial medium containing fibrinogen and albumin and (b) in diluted autologous plasma. (1) With increasing pH of the medium, the velocity of erythrocyte aggregation increased. (2) The velocity of erythrocyte aggregation in the artificial medium increased as the temperature rose. However, in 70% autologous plasma the velocity was minimum at 15-18 degrees C, increasing both above and below this temperature (above 30 degrees C, the velocity saturated). (3) The velocity of erythrocyte aggregation decreased in hypotonic medium, while it increased in hypertonic medium (at osmotic pressures higher than 400 mOsm, the velocity decreased). The mechanism of erythrocyte aggregation is discussed with special reference to the morphological changes produced by pH, temperature and osmotic pressure, and the implications of the phenomena for oxygen transport to tissues in (patho)physiological situations are considered.

Adult↗
PubMed1991

Monoclonal antibody against platelet thrombospondin decreases erythrocyte aggregation rate.

The effect of thrombospondin, a major glycoprotein in the platelet alpha-granule, on the erythrocyte aggregation rate was investigated. Venous blood was sampled from 8 healthy male volunteers and anticogulated with 1.1 mg/ml EDTA(K2). The erythrocyte aggregation rate of each blood sample was measured with a whole-blood erythrocyte aggregometer before and after incubation with murine monoclonal antibody against human platelet thrombospondin. After 15 min incubation, the erythrocyte aggregation rate exhibited a significant decrease to 0.055 +/- 0.022/s, representing 71.9 +/- 8.7% of the control value (0.075 +/- 0.028/s) (p less than 0.0005). The results obtained suggest that thrombospondin may participate in the control of erythrocyte aggregability in the circulating blood.

Antibodies, Monoclonal↗
PubMed1993

[Effect of alcian blue effect on erythrocyte aggregation].

Changes were found in the charged erythrocyte surface with higher quantities of the membrane-bound dye alcian blue (AB). There was a drastic rise of AB-dependent erythrocyte aggregation rate with the low ionic strength of a medium. It is concluded that the AB-dependent aggregation rate depends on the age of cells and the levels of cholesterol in erythrocyte membranes.

Alcian Blue↗
PubMed1994

[Functional capacity of fibrinogen and erythrocyte aggregation in the diabetic].

The aim of this work is to study the possible influence of a qualitative modification of fibrinogen on its capacity of erythrocyte aggregation. Fibrinogens were isolated and then purified from blood sample of 15 insulin-dependent diabetics and of 7 healthy subjects. The erythrocyte aggregative effect of the purified fibrinogens was measured for various concentrations (0 g/1-5 g/l). The erythrocyte aggregation was determined by the ECHO CELL whose functioning principle is based upon ultrasonic interferometry. Results allow one to distinguish three kinds of fibrinogen: the first kind inducing a similar erythrocyte aggregation as that obtained by the fibrinogens from healthy subjects, the second kind inducing an erythrocyte hyperaggregation, the third kind inducing an erythrocyte hypoaggregation. Thus the possibility of a qualitative abnormality of fibrinogen, affecting its erythrocyte aggregative capacity in diabetic patients, could be suggested. This qualitative abnormality of fibrinogen might be due to a modification of its molecular structure because of an abnormal elevated glycation during diabetes.

Adult↗
PubMed1993

[In vitro effects of ionic and non-ionic contrast media on erythrocyte aggregation].

An in vitro model was designed to examine the effect of three contrast media (CM): two non ionic (Iohexol, Iopamidol) and one ionic (Ioxaglate) molecules on erythrocyte aggregation. Red blood cells were suspended in a chemically defined medium (Albumin: 10 g/l), Immunoglobulins: 12 g/l, Fibrinogen: 1.5 g/l) supplemented with various proportions of CM (10-25% V/V). Control samples contained NaCl or Saccharose solutions with a nearly similar osmolality. Erythrocyte aggregation at constant hematocrit (HT = 40%) was determined by the analysis of the light backscattered by blood suspension during the aggregation process. As compared to control samples, non ionic CM induced a weak decrease in erythrocyte aggregation, when the ionic molecule caused a marked increase in the aggregation, which was related to CM concentration. A different interaction of ionic and non ionic CM with erythrocyte membranes has been shown by fluorescence studies. After addition of CM, it was noted a fluorescence quenching of lipophilic probes (TMA-DPH and DPH) embedded in erythrocyte membranes. This quenching probably due to benzene ring and iodine atoms of contrast media markedly varied according to the used fluorescent probe and the CM. In the presence of ionic CM, the fluorescence quenching is more important than that induced by non ionic CM. Thus, besides osmolality and viscosity of CM which play a role in erythrocyte aggregation, some intrinsic properties of CM such as the ionic or non ionic nature could influence erythrocyte membrane-contrast medium interactions and consequently erythrocyte aggregation.

Diphenylhexatriene↗
PubMed1983

[Effect of gestational diabetes on erythrocyte aggregation].

In order to elucidate the tendency to erythrocyte aggregation in gestational diabetes, blood viscosity at a standard hematocrit of 45% (corrected viscosity) was measured at low shear rates in the third trimester of normal pregnancy and pregnancy with gestational diabetes. The mean values (+/- S.D.) for corrected viscosity of 20 gestational diabetic patients were 69.2 +/- 16.6cp at shear rate of 0.11 sec-1, 34.9 +/- 5.3cp at 0.54sec-1 and 27.9 +/- 5.0cp at 0.99sec-1. They were significantly higher than those of 40 normal pregnant patients (55.2 +/- 11.4cp at 0.11sec-1, 29.0 +/- 2.6cp at 0.54sec-1 and 24.4 +/- 2.4cp at 0.99sec-1). The mean value of fibrinogen of gestational diabetic patients was 408.8 +/- 106.7 mg/dl and significantly higher than that of normal patients (313.3 +/- 65.1 mg/dl). The increased tendency to erythrocyte aggregation observed in the diabetic patients was due to increased fibrinogen and would induce microcirculatory disturbance and mild hypoxia in the placental tissue. The cytotrophoblastic cell proliferation which is a characteristic morphological finding of diabetic placenta would be induced as a result of the reaction of placental tissue to the hypoxia thus produced.

Alpha-Globulins↗
PubMedDate not supplied

A study on the erythrocyte aggregating properties of polybrene and protamine sulphate.

By observing the aggregation of erythrocytes in protamine sulphate or Polybrene it is possible to predict MN phenotypes with 97 per cent accuracy. It is probable that one factor influencing aggregation is the relative site density of a receptor common to both M and N antigen structures although other nondiscriminating receptor sites on a lower layer of sialic acid are possible also involved.

Acetylation↗
PubMed1994

Erythrocyte aggregation--determination of normal values. Influence of age, sex, hormonal state, oestroprogestative treatment, haematological parameters and cigarette smoking.

Erythrocyte aggregation is a physiological phenomenon and constitutes one of the most important factors accounting for the non-Newtonian properties of normal human blood. Pathological aspects have also been described and therapy aimed at reducing hyperaggregability has been proposed. The object of this study was to establish normal values of erythrocyte aggregation parameters as measured by laser light backscattering and to study the influence of various physiological factors. Normal values were determined from a reference population. Sex and age induce variations in erythrocyte aggregation which are neither fibrinogen nor haematocrit dependent and there is a general trend towards stronger aggregation in women, although neither hormonal state nor oestroprogestative treatment appear to influence the female aggregation parameters. In elderly people stronger aggregation is also observed but this effect is of lower magnitude. In vivo, the plasma fibrinogen level is the most important factor influencing erythrocyte aggregation, while variations in haematocrit play a lesser role and mean corpuscular volume, red cell distribution width and white blood cell and platelet counts have no effect. Finally, no difference is noted in cigarette smokers.

Adolescent↗
PubMedDate not supplied

Acute isovolemic hemodilution triggers proinflammatory and procoagulatory endothelial activation in vital organs: role of erythrocyte aggregation.

OBJECTIVES: The essential role of erythrocytes as oxygen carriers is historically well established, but their function to aggregate and the consequences on the microcirculation is under debate. The pathogenic potential of low erythrocyte aggregation could be important for patients undergoing on-pump cardipopulmonary bypass. These patients are severely hemodiluted due to preoperative isovolemic hemodilution (IHD), circuit priming, and large fluid infusions perioperatively. Considering the vascular endothelium sensitivity to variations in blood rheology, the authors hypothesize that low erythrocyte aggregation will be responsible for activation of vascular endothelium during acute IHD. METHODS: Acute IHD (30 mL/kg exchange transfusion with colloid solutions) was induced in an "aggregating species"(pigs, n = 15). The hypoxic oxidative stress (plasma malondialdehyde, ex vivo oxygen radicals production in heart, lung, kidney, liver, and ileum tissue biopsies), erythrocyte aggregation (LORCA), and endothelial activation (real-time quantitative RT-PCR on von Willebrand factor (vWF), E- and P-selectins, endothelial nitric oxide synthase gene-expression in tissue biopsies) were investigated. RESULTS: The production of superoxide and hydroxyl radicals, measured as H2O2 generation, was similar at all times in sham-operated and hemodiluted animals, proving a maintained oxygen delivery to tissues. Acute IHD was followed by a dramatic drop in erythrocyte aggregation and immediate prothrombotic (significant vWF mRNA upregulation in heart, lungs, kidney, liver, ileum) and proinflammatory (significant E- and P-selectins mRNA upregulation in lungs and ileum) endothelial activation. Low erythrocyte aggregation was significantly correlated with increased mRNA-expression of vWF (heart, liver, ileum) and P-selectin (lungs, ileum, and heart). CONCLUSIONS: These results suggest that low erythrocyte aggregation might trigger endothelium-dependent thrombogenic and proinflammatory response during acute isovolemic hemodilution.

Animals↗
PubMed2005

Does antioxidant supplementation alter the effects of acute exercise on erythrocyte aggregation, deformability and endothelium adhesion in untrained rats?

This study aimed to determine whether high-dose antioxidant supplementation had an impact on the acute exercise effects related to erythrocyte membrane mechanics. Experimental animals (n=32) were divided into four groups as control, exercised, supplemented, and supplemented + exercise. Four-week antioxidant supplementation (vitamin C, vitamin E, and zinc) was applied to experimental animals. Following acute exercise on a motor-driven rodent treadmill, erythrocyte aggregation and deformability, erythrocyte adhesion to endothelial cells, superoxide dismutase (SOD), and glutathione peroxidase activities of the erythrocytes were analyzed. In both supplemented and non-supplemented exercised groups, there was a significant decrease in SOD activities and erythrocyte aggregation, and an increase in adhesion to endothelial cell although there was no change on erythrocyte deformability. There were no differences in the responses to the exercise of supplemented and nonsupplemented rats. The data suggested that high-dose antioxidant supplementation did not alter the effects of acute exercise on erythrocyte membrane mechanics.

Animals↗