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PubMed1996

Role of albumin glycation on the erythrocyte aggregation: an in vitro study.

The increased erythrocyte aggregation observed in diabetes mellitus is mainly due to changes in the balance between aggregating factors and anti-aggregating ones, like albumin. Since chronic hyperglycaemia results in protein glycation, we examined the effect of in vitro glycation of albumin on its anti-aggregating role with blood from 29 Type 1 diabetic patients and 29 healthy controls. After the addition of glycated and unglycated albumin, samples had a glycation level of 24% for healthy controls and 28% for diabetic patients. Erythrocyte aggregation was determined by the analysis of the light backscattered by a blood suspension. Erythrocytes from healthy controls suspended in glycated albumin had significantly higher rates of rouleaux formation (p < 0.01) than in unglycated albumin and increased cohesion of rouleaux (p < 0.05). The erythrocyte aggregation in diabetic patients underwent similar changes (p < 0.01). The time-resolved fluorescence of the single tryptophan residue was monitored to describe the changes in the conformational equilibrium of albumin. The lifetime data showed that the increases in the two lifetime components and in the relative proportion of the major lifetime are in agreement with a conformational change in albumin after glycation. Thus, the changes in albumin conformation could be responsible for the smaller hypoaggregating effect of glycated albumin.

Adult↗
PubMed1988

Effect of pH on the velocity of erythrocyte aggregation.

The effect of pH on the velocity of aggregation of human erythrocytes was quantitatively examined with a rheoscope combined with a video-camera, an image analyzer and a computer, in relation to the morphological changes of erythrocytes and their aggregates. (i) With increasing pH of the medium, the velocity of erythrocyte aggregation increased. (ii) The rouleaux formed at high pH were longer in shape and more stable against the increase of shear rate than those formed at low pH. (iii) With increasing pH, the diameter of erythrocyte increased, the (maximum) thickness decreased, and the cell volume decreased. The pH dependency of erythrocyte aggregation may be mainly due to the morphological change of erythrocytes, and partly due to the changes of erythrocyte deformability and of interaction with macromolecules.

Erythrocyte Aggregation↗
PubMed1989

Analysis of erythrocyte aggregation mechanism in presence of dextran and magnetic field by ultrasound scattering in blood.

Aggregation of erythrocytes is studied as function of time during their sedimentation process under the gravitational field. The method is based on ultrasonic scattering from the various blood samples in presence and absence of inhomogeneous magnetic field (IMF) and dextran 70 (10%). The experimental arrangement is consisting of ultrasonic transmitter and receiver probes placed in mutually perpendicular direction intersecting at the sampling volume of blood located at the centre of the blood column. The temporal kinetic process is represented in terms of histograms of amplitudes and number of scattering fluctuations related to the size and motion of aggregates. The results show that the application of IMF influences the aggregation and sedimentation of erythrocytes. The aggregates thus formed sediment faster than that of control sample. The aggregate formation and their movements in presence of dextran 70 are slower than that of normal blood which may be attributed to the enhanced suspending medium viscosity and their interaction with erythrocytes.

Dextrans↗
PubMed1990

[Erythrocyte aggregation and vascular pathology].

The aggregation of erythrocytes plays an essential part in vascular diseases involving both the veins and the arteries. In the veins, where the lowest blood flow rates are observed, the conditions of flow foster the aggregation of the erythrocytes, which accounts for blood hyperviscosity that may reinforce the effects of the stasis. In arterial diseases, hyperaggregation of the erythrocytes resulting from risk factors such as smoking, high BP, diabetes, disorders of lipemia, etc. contributes to the formation of stenosis, which has severe consequences for the patient. The prospects of the treatment aimed at correcting the hemorheological disorders caused by hyperaggregation of the platelets are ruled by Poiseuille's formula and based on hemodilution processes and the use of agents lowering fibrinogenemia or molecules improving the forming properties of the red blood cells.

Erythrocyte Aggregation↗
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↗
PubMed1995

Quantification of erythrocyte aggregation by blood echogenicity: a preliminary study.

Many techniques were proposed to assess erythrocyte aggregation in clinical and experimental investigations in view of in vitro determination. However no methodology until now is available to measure erythrocyte aggregation in flowing blood in vivo. High resolution ultrasonography provides an original way to quantify erythrocyte aggregation using the echogenicity of blood. We have developed and A-mode ultrasound scanner coupled with an oscilloscope and a computer allowing the analysis of ultrasonic signals produced by erythrocytes. A closed measurement chamber connected to a calibrated roller-type blood pump where blood was perfused was used. The echogenicity of blood was determined at different shear rates. Dextran, fibrinogen and other high molecular weight substances were added to increase erythrocyte aggregation. Changes in red blood concentration was also tested. An increase in blood echogenicity rate was observed at low shear. At a given shear rate blood echogenicity increased when fibrinogen or dextran were added. Such determination of the echogenicity of flowing blood in vitro will provide an approach to the quantification of erythrocyte aggregation in vivo circulation, especially in the veins where low shear rates are observed.

Biomechanical Phenomena↗
PubMed1989

Enhanced erythrocyte aggregability in occlusive cerebrovascular disease.

We measured the rate of erythrocyte aggregation using our whole-blood aggregometer in 80 patients with occlusive cerebrovascular disease during the acute and chronic phases. We compared the data with values for 38 age-matched healthy controls. Mean +/- SD erythrocyte aggregability of the patients during both the acute phase (0.145 +/- 0.21/sec, n = 35) and the chronic phase (0.139 +/- 0.21/sec, n = 45) was higher than that in the controls (0.123 +/- 0.21/sec, n = 38; p less than 0.01). Erythrocyte aggregability was positively correlated with the plasma concentration of globulin and fibrinogen and inversely correlated with the albumin:globulin ratio. However, these correlations did not necessarily exclude the possibility that some unknown substance(s) released from ischemic tissue might enhance erythrocyte aggregability.

Acute Disease↗
PubMed1986

[Role of heparin in erythrocyte aggregation].

The effect of two heparin fractions containing 3 (HP-3) and 4 (HP-4) residues of sulfuric acid per dimer of polymers on the capacity of hyaluronate potassium (HUP) and protein-chondroitin-keratan-sulfate potassium (PCHKSP) to aggregate rabbit erythrocytes suspended in 0.15 M NaCl was studied. HP-3 (0.3-5.0 mg X ml-1) and HP-4 (0.3-5.0 mg X ml-1) was inhibited the aggregating action on the erythrocytes of HUP. Fraction HP-3 (0.3-5.0 mg X ml-1) was activated the aggregating action on the erythrocytes of PCHKSP. Fraction HP-4 when the concentration of their biopolymer were 0.3 mg X ml-1 so activated the aggregating action of PCHKSP, but when the concentration HP-4 0.6-5.0 mg X ml-1 was inhibited the aggregating action PCHKSP. The mixture of HP-3 (1.2 mg X ml-1) and HP-4 (1.2 mg X ml-1) was not influenced on aggregating action of PCHKSP.

Animals↗
PubMed2005

Influence of hemodilution of plasma proteins on erythrocyte aggregability: an in vivo study in patients undergoing cardiopulmonary bypass.

Erythrocyte aggregation is known to be affected by a number of factors including the concentration of various plasma proteins. This study was performed to examine the in vivo effect of hemodilution of plasma proteins on erythrocyte aggregation in patients undergoing cardiopulmonary bypass (CPB) surgery. Blood samples were taken before, during, and after operation from 40 coronary artery bypass grafting patients who were operated with CPB and concomitant hemodilution (CPB, n=20) and who without (nonCPB, n=20). Erythrocyte aggregation was determined with a LORCA aggregometer, during which all samples were standardized to a hematocrit level of 40%. Results showed that in the CPB patients the aggregation index (AI) dropped to 44% of its preoperative baseline level 5 minutes after the start of hemodilution (from 47.7+/-10.1 to 26.6+/-11.4, p<0.01). Meanwhile, plasma concentration of fibrinogen (Fb) dropped to 55%, haptoglobin to 85%, ceruloplasmin to 55%, and albumin to 67%. In the nonCPB patients, however, there was only a slight drop in AI and the concentrations of plasma proteins during the similar period of time. On postoperative day 1, AI was rebounded to 37.1+/-12.4 in CPB patients compared with 44.3+/-11.7 in nonCPB patients. At baseline, AI was correlated only with Fb. During CPB and hemodilution, AI was correlated not only with Fb but also with haptoglobin and ceruloplasmin. Postoperatively, significant correlationship was found between AI and Fb, CRP, haptoglobin, ceruloplasmin, as well as albumin. These results indicate that hemodilution of plasma proteins significantly reduces the aggregability of erythrocytes in patients undergoing CPB. Besides Fb, other plasma proteins also contribute to AI during the early postoperative period when patients are recovering from CPB surgery.

Acute-Phase Proteins↗
PubMed1996

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

We examined the effect of aspirin on the enhanced erythrocyte aggregability in 19 patients with cerebral infarction during the chronic phase. Aspirin (81 mg/day) was administered for 8 weeks. The rate of erythrocyte aggregation (aggregability) was measured using the whole-blood erythrocyte aggregometer developed by us (Am. J. Physiol. 251, H1205-H1210, 1986) before, and at 4 and 8 weeks after initiation of the aspirin administration. Concomitant measurements were made of certain blood factors such as the hematocrit, albumin-globulin (A/G) ratio and fibrinogen concentration. The erythrocyte aggregation rates before, and at 4 and 8 weeks were 0.154 +/- 0.019/s, 0.144 +/- 0.020/s, and 0.143 +/- 0.020/s, respectively. The erythrocyte aggregation rates at 4 and 8 weeks were significantly (P < 0.05, Bonferroni's modified t-test) lower than that before aspirin administration. Although the hematocrit value and A/G ratio were not changed at 4 and 8 weeks after the initiation of aspirin, the concentration of fibrinogen were significantly (P < 0.05) reduced at 4 weeks. The above results suggest that aspirin can improve the enhanced erythrocyte aggregability in patients with cerebral infarction during the chronic phase.

Adult↗
PubMed1991

[Erythrocyte aggregation in patients with monoclonal gammopathies: effect of plasma exchange treatment].

Analyses of erythrocyte aggregation have been carried out in 15 patients with multiple myeloma or Waldenström's macroglobulinemia before and after plasma exchange. The volume of exchanged plasma was about 1.2-1.5 plasmatic mass. It was replaced by the same volume of a 4% solution of human albumin. Each treatment included at least 3 plasma exchanges at 48 hours intervals. The kinetic (aggregation times) and rheological (dissociation threshold) parameters of erythrocyte aggregation were determined before and immediately after each plasma exchange using a device based on the analysis of the backscattered light by a blood suspension. Before the first plasma exchange, erythrocyte aggregation measurements revealed a pronounced reduction in time aggregation and high values of dissociation thresholds indicating an hyperaggregation of red cells. The successive plasma exchanges produced very different changes in erythrocyte aggregation. For some patients, the aggregation parameters presented normal values from the first plasma exchange when similar changes were only noted after the second plasma exchange in other patients. Finally, in some cases, an hyperaggregation state was maintained after a series of three plasma exchanges. The influence of the nature and the concentration of monoclonal immunoglobulin as well as plasmatic fibrinogen are discussed.

Blood Viscosity↗
PubMed2005

Influence of fibrinogen levels on erythrocyte aggregation determined with the Myrenne aggregometer and the Sefam erythro-aggregometer.

Fibrinogen is one of the plasmatic proteins which has a major influence on erythrocyte aggregation. The level of fibrinogen at which erythrocyte aggregation does not further increase is not well established. Therefore we aim to determine erythrocyte aggregation with two devices: Myrenne aggregometer (M0 and M1) and Sefam erythro-aggregometer (Ta, AI10 and gammaD) in relation with fibrinogen levels, in patients with several diseases with fibrinogen levels ranging between 200-1100 mg/dl. With the Myrenne aggregometer a plateau can be observed for fibrinogen levels higher than 400 mg/dl, while with the Sefam erythro-aggregometer, aggregation increases proportionally with fibrinogen levels higher than 400 mg/dl. In addition, for fibrinogen values higher than 400 mg/dl, only statististically significant correlations could be observed between fibrinogen and erythrocyte aggregation parameters with the Sefam erythro-aggregometer: r(Ta)=-0.463; r(AI10)=0.624, r(gammaD)=0.817, p<0.01, but not with the Myrenne: r(M0)=0.01, r(M1)=0.02, ns. Although the Sefam erythro-aggregometer is a better tool for determining erythrocyte aggregation both at low and high fibrinogen levels, the Myrenne aggregometer may be useful for assessing the erythrocyte aggregation as an indicator of cardiovascular risk, as in such circumstances fibrinogen levels do not usually exceed values higher than 400 mg/dl.

Adolescent↗
PubMed1987

The apparent viscosity of aggregating and non-aggregating erythrocyte suspensions in the isolated perfused liver.

Vasodilated guinea pig livers were perfused with normal erythrocytes and echinocytes suspended in isoviscous high- and low-molecular-weight dextran solutions. The relative flow resistance of these suspensions and the oxygen uptake of the livers were then determined. The relative flow resistance of the echinocytes that were suspended in high-molecular-weight dextran, however, was significantly higher than that of any other red cell suspension. The oxygen uptake was independent of the perfusion media. It is proposed that high-molecular-weight dextran induces echinocytes to attach to one another, and that this clumping together, and shape-transformation of red cells, hinders their flow in the vasodilated liver.

Animals↗
PubMed2006

The impact of different antimigraine compounds on platelet and erythrocyte aggregation.

Clinical and experimental data suggest that ergotamine compounds and triptans may contribute to vascular events such as myocardial infarction and stroke. The role of blood cell aggregation in this context is, however, not clarified. We aimed to evaluate the impact of different acute antimigraine compounds on platelet and erythrocyte aggregation in a human ex vivo experimental design. In 20 healthy subjects without migraine and in 20 healthy subjects with migraine without aura, platelet and erythrocyte aggregation were measured before and after intake of placebo, acetylsalicylic acid, ergotamine tartrate, zolmitriptan and sumatriptan. Platelet aggregation was measured by the so-called platelet reactivity index. Erythrocyte aggregation was measured by photometric assessment in an aggregometer. Ergotamine tartrate induced a significant increase of platelet aggregation, whereas acetylsalicylic acid induced a significant decrease in both subject groups. After placebo, after sumatriptan and after zolmitriptan, no significant changes of platelet aggregation were noted. Erythrocyte aggregation was affected by neither compound. We can conclude that platelet aggregation, but not erythrocyte aggregation, is increased after intake of ergotamine tartrate. This may in part contribute to vascular side-effects of this compound. Acetylsalicylic acid and the triptans appeared to be safe with respect to platelet and erythrocyte aggregation.

Adult↗
PubMed2005

Enhanced erythrocyte aggregation in clinically diagnosed pelvic inflammatory disease.

OBJECTIVE: Enhanced erythrocyte aggregation, revealed using a simple bedside test, has been found recently in several inflammatory conditions. The diagnosis of pelvic inflammatory disease (PID) is at times difficult because of the vague symptoms and signs, but is crucial because even mild PID can have future reproductive consequences. Our objective was to determine the degree of erythrocyte aggregation in PID. The demonstration of an increase in aggregation could be of additive value in cases in which the diagnosis is difficult. STUDY DESIGN: A prospective case-control study was conducted. Fifteen consecutive women diagnosed clinically as having PID based on Centers for Disease Control and Prevention criteria, and 15 matched controls were enrolled. Blood samples were drawn for hematologic indices, C-reactive protein, fibrinogen levels, and red cell aggregation. We studied the degree of red cell aggregation using a simple slide test and image analysis. The variable measured was the erythrocyte percent (EP), equivalent to the slide area covered by erythrocytes. RESULTS: Erythrocyte percent was 59.6 +/- 4.2 and 80.0 +/- 3.6 for the study group and controls, respectively (P <0.001). A significant difference was noted also for the other hematologic and biochemical markers of inflammation between patients and the controls. CONCLUSIONS: We conclude that the degree of erythrocyte aggregation is increased in PID. Its simplicity, rapidity, and low cost should be further evaluated as a diagnostic tool in the context of this frequent disease.

Adult↗
PubMed2003

Erythrocyte aggregability and disaggregability in thalassemia trait carriers analyzed by a laser backscattering technique.

Erythrocyte aggregability was determined by a laser backscattering light technique in 23 beta minor thalassemia carriers and in 36 age and sex matched controls. The aggregation time (Ta) was statistically higher in cases than in controls (2.8 +/- 1.0 vs 2.3 +/- 0.4, p < 0.05) and the aggregation index at 10 sec (AI10) was statistically lower (25.1 +/- 5.7 vs 28.2 +/- 3.8, p < 0.05), suggesting both parameters a statistically lower erythrocyte aggregability tendency. However, the total disaggregation threshold (gammaD) was statistically higher in cases than in controls (134.4 +/- 34.1 vs 105.1 +/- 33.1, p < 0.05), indicating that once aggregates are formed a higher shear rate is needed to break them up. No differences were observed in plasmatic factors, i.e., fibrinogen, total cholesterol and triglycerides, that could have influenced erythrocyte aggregation. A negative statistically significant correlation was found between erythrocyte indexes and the total disaggregation threshold. The lower erythrocyte aggregation found in minor thalassemia carriers could be attributed in part to the morphological alterations, although others mechanisms such as modifications in the membrane structure of the RBC can not be ruled out.

Adolescent↗
PubMed1991

Increased plasma viscosity and erythrocyte aggregation: indicators of an unfavourable clinical outcome in patients with unstable angina pectoris.

OBJECTIVE: To determine the prognostic significance of altered plasma viscosity and erythrocyte aggregation in unstable angina. DESIGN: A prospective study of 96 consecutive patients with unstable angina allocated to one of two groups according to predefined threshold values for plasma viscosity and erythrocyte aggregation at study entry. The patients received a standardised treatment and were followed up for six months or until angioplasty or bypass surgery. MAIN OUTCOME MEASURE: Frequency of myocardial infarction. RESULTS: Myocardial infarctions occurred in 7/26 patients with a plasma viscosity greater than or equal to 1.38 mPa s and in 8/35 with a rate constant of erythrocyte aggregate formation greater than or equal to 0.5 mPa (corrected for plasma viscosity) but in only 4/70 with a plasma viscosity less than 1.38 mPa s and in 3/61 with an erythrocyte aggregation less than 0.5 mPa (odds ratios: 6.1 (95% confidence interval 1.3 to 31), p = 0.008, and 5.7 (95% CI 1.2 to 35), p = 0.016). Plasma viscosity and erythrocyte aggregation were more predictive of myocardial infarction than age, male gender, fibrinogen concentration, ST segment abnormalities, or coronary score. Furthermore, Holter monitoring with ST segment analysis showed that ischaemic episodes were more common in patients in whom the rate constant of erythrocyte aggregate formation was greater than 0.5 mPa (15/27 v 17/50, p = 0.029). Cardiac troponin T release was increased in patients with a plasma viscosity of greater than 1.38 mPa s (10/26 v 9/70, p = 0.010). CONCLUSIONS: In patients with unstable angina a considerable increase in plasma viscosity and erythrocyte aggregation identified a subgroup of patients at a high risk of acute myocardial infarction in whom medical treatment was likely to be unsuccessful.

Aged↗