Parameters Erythrocyte Aggregation Research Articles

Investigation of erythrocyte aggregation parameters of blood with low levels of fibrinogen by syllectometry

Investigation of erythrocyte aggregation parameters of blood with low levels of fibrinogen by syllectometry

A rapid and accurate method for estimating the erythrocyte sedimentation rate using a hematocrit-corrected optical aggregation index.

Although both the erythrocyte sedimentation rate (ESR) and optically measured erythrocyte aggregation parameters are affected by the hematocrit, this interaction is not considered by the method used to estimate ESR that considers aggregation parameters. In this study, we investigated the relationship between the ESR obtained by the Westergren method and that obtained with an aggregation parameter, namely, the aggregation index (AI) of multiple hematocrit values and fibrinogen-spiked samples with an analysis time of 5–60 s, and attempted to develop a rapid and accurate ESR estimation method. The AIs obtained from 5- and 10-s optical measurements with a fixed hematocrit were highly correlated with the erythrocyte sedimentation velocity. Furthermore, the rate of the AI increase with an increasing hematocrit was not significantly affected by the fibrinogen concentration at these measurement times. On the basis of these results, we defined the hematocrit-corrected aggregation index (HAI). The exponential function of the HAI obtained from the 5-s measurement agreed well with the sedimentation velocity calculated to eliminate the effect of hindered settling, and the HAI and hematocrit could be used to calculate the time constant of the sedimentation curve with a linear regression equation. The ESR value at 1 h was calculated based on the modified Stokes’ law and the HAI obtained from the 5-s measurement and showed an excellent correlation (R = 0.966) with the ESR value obtained by the Westergren method over a wide range of hematocrit and fibrinogen concentrations.

Microrheology, microcirculation and structural compensatory mechanisms of a chronic kidney disease rat model. A preliminary study.

Chronic kidney disease (CKD) models are known to study pathophysiology and various treatment methods. Renal dysfunction could influence erythrocytes through several pathways. However, hemorheological and microcirculatory relation of CKD models are not completely studied yet. To evaluate erythrocyte micro-rheology, microcirculatory and structural compensatory mechanisms in a rat model of CKD. Female Sprague-Dawley rats were subjected to nephrectomy group (NG, n = 6) or sham-operated group (SG, n = 6). NG rats were subjected to 5/6 nephrectomy in two stages. In SG no intervention was made on kidneys. Hemorheological and hematological measurements were carried out after each stage, and 5 weeks after the last operation. Histological and microcirculatory studies were done on the remaining kidney and compared with sham rats. Serum creatinine increased in NG (p = 0.008), accompanied with decrease of red blood cell count (p = 0.028) and hemoglobin (p = 0.015). Erythrocyte aggregation parameters slightly increased in NG, while the elongation index didn't show significant changes. Microcirculation was intact in the remnant kidney of NG. However, in comparison with SG, the diameter of glomeruli increased significantly (p < 0.01). Erythrocyte mass was influenced more than micro-rheological properties in this model. The main compensation mechanism was rather structural than at microcirculatory level.

Changes of red blood cell aggregation parameters in a long-term follow-up of splenectomy, spleen-autotransplantation and partial or subtotal spleen resections in a canine model.

Decrease or loss in splenic filtration function may influence the hemorheological state. To follow-up the long-term effects of splenectomy, spleen autotransplantation and spleen resections on red blood cell aggregation in a canine model. Beagle dogs were subjected to control (n = 6), splenectomy (SE, n = 4), spleen autotransplantation (AU, Furka's spleen-chip method, n = 8) or partial and subtotal spleen resection (n = 4/each) groups, and followed-up for 18 postoperative (p.o.) months. Erythrocyte aggregation was determined in parallel by light-transmittance aggregometry (Myrenne MA-1 aggregometer) and syllectometry (LoRRca). Erythrocyte aggregation decreased three months after splenectomy, with lower aggregation index and elongated aggregation time. It was more or less associated with relatively lower hematocrit and fibrinogen concentration. However, in autotransplantated animals a relatively higher fibrinogen did not increase the aggregation markedly. Spleen resection resulted in the most controversial red blood cell aggregation findings, and it seems, that the degree of the resection is an influencing factor. Splenectomy alters erythrocyte aggregation, spleen autotransplantation can be useful to preserve filtration function. However, the degree of restoration shows individual differences with a kind of 'functional periodicity'. Spleen resection controversially influences erythrocyte aggregation parameters. The subtotal resection is supposed to be worse than spleen autotransplantation.

The effect of centrifugation at various g force levels on rheological properties of rat, dog, pig and human red blood cells.

Laboratory investigations often require centrifugation of blood samples for various erythrocyte tests. Although there is a lack of data about the effect of centrifugation at various g force levels on erythrocyte rheological properties. We aimed to investigate the effect of a 10-minute centrifugation at 500, 1000 or 1500 g at 15°C of rat, dog, pig and human venous (K3-EDTA, 1.5 mg/ml) blood samples. Hematological parameters, erythrocyte deformability, cell membrane stability, osmotic gradient ektacytometry (osmoscan) and erythrocyte aggregation were determined. Hematological and erythrocyte deformability parameters showed interspecies differences, centrifugation caused no significant alterations. Cell membrane stability for human erythrocytes centrifuged at higher g level showed less decrease in deformability. Osmoscan O min parameter showed slight elevation in dog centrifuged aliquots. Erythrocyte aggregation parameters changed unexpectedly. Rat and dog erythrocyte aggregation indices significantly dropped in centrifuged aliquots. Pig erythrocyte aggregation indices increased significantly after centrifugation. Human erythrocyte aggregation was the most stable one among the investigated species. The used centrifugation protocols caused the largest alterations in erythrocyte aggregation in a controversial way among the investigated species. On the other hand, erythrocyte deformability parameters were stable, cell membrane stability and osmoscan data show minor shifts.

The association of dyslipidemia with erythrocyte aggregation

Aim: The present study aims to associate erythrocyte aggregation with plasma lipid concentration. Materials and Methods: Ninety-nine participants were divided into two groups: normolipidemic and dyslipidemic. Lipid parameters were measured from serum and erythrocyte aggregation parameters: critical stress and critical time were measured from whole blood. Data were analyzed using IBS SPSS statistics software. Results: Erythrocyte aggregation was higher in the dyslipidemic group when compared with the normolipidemic group. Erythrocyte aggregation was associated with the abnormalities in lipid parameters, with the association of HDL-cholesterol and triglyceride being stronger than that of LDL-cholesterol and total cholesterol. Conclusion: The strong association of triglyceride and HDL-cholesterol with erythrocyte aggregation emphasizes the role of these lipids in the cardiovascular system.

Altitude training induced alterations in erythrocyte rheological properties: A controlled comparison study in rats

Altitude training is frequently used by athletes to improve sea-level performance. However, the objective benefits of altitude training are controversial. This study aimed to investigate the possible alterations in hemorheological parameters in response to altitude training. Sprague Dawley rats, were divided into 6 groups: live low-train low (LLTL), live high-train high (LHTH), live high-train low (LHTL) and their controls live high and low (LHALC), live high (LHC), live low (LLC). LHC and LHTH groups were exposed to hypoxia (15% O2, altitudes of 3000 m), 4 weeks. LHALC and LHTL were exposed to 12 hours hypoxia/normoxia per day, 4 weeks. Hypoxia was maintained by a hypoxic tent. The training protocol corresponded to 60-70% of maximal exercise capacity. Rats of training groups ran on treadmill for 20-30 min/day, 4 days/week, 4 weeks. Erythrocyte deformability of LHC group was increased compared to LHALC and LLC. Deformability of LHTH group was higher than LHALC and LLTL groups. No statistically significant alteration in erythrocyte aggregation parameters was observed. There were no significant relationships between RBC deformability and exercise performance. The results of this study show that, living (LHC) and training at altitude (LHTH) seems more advantageous in hemorheological point of view.

Rheological blood behaviour is not related to gender in morbidly obese subjects

To the Editor. We have read with interest the recently published article by Wiewiora et al. [7] regarding hemorheological differences related to gender in morbidly obese subjects. In this study authors found several hemorheological differences between male and female. In this sense, males showed higher blood viscosity and higher erythrocyte deformability than females and native blood viscosity correlated with several erythrocyte aggregation parameters evaluated with the Laser-Assisted Optical Rotational Cell Analyser (LORCA) [3]. In studies with small sample sizes (18 men and 20 women) there is always the risk that differences in certain variables may appear by chance or by imbalances in the groups. Moreover, it was not discussed why the erythrocyte deformability should be higher in males. Therefore we aimed to evaluate the rheological profile in a larger sample of morbidly obese subjects selected for bariatric surgery, to ascertain whether there are rheological differences in morbidly obese related to gender. Before statistical testing, all continuous variables were checked for normal distribution. Those who were markedly skewed, were log transformed to improve normality. Analytical tests were performed according to previous studies of our group [4, 5] and in accordance with the ethical guidelines for Clinical Hemorheology and Microcirculation [1]. Results are expressed in Tables 1 and 2 as mean ± sd. P values <0.05 were considered as statistically significant. All analyses were performed using the Statistical Package of Social Sciences (SPSS, version 11.0) for Windows. The results of the present study revealed no differences in erythrocyte deformability, at any of the shear stresses tested when males and females were compared, in line with the homogeneity of erythrocyte indices in both groups. In this sense, Wiewiora’s study did not include any information on erythrocyte indices [7], although these indices are of paramount importance when evaluating erythrocyte deformability [2, 6].

Rheological blood properties in psoriatic arthritis: relationship with inflammation and cardiovascular risk

Objective. To study possibility of using blood rheological parameters as markers of inflammation and cardiovascular risk (CVR) in pts with psoriatic arthritis (PA). Material and methods. 130 pts (51 male and 79 female) with PA aged from 39 to 48 years (mean age 43 years) without clinical signs of coronary heart disease (CHD) and stroke were included. Duration of PA varied from 2 months to 42 years (mean 7 years), duration of psoriasis (PS) – from 5,5 to 26 years (mean 15 years). Main measures of erythrocyte aggregation (EA) including Kt (c-1) – total speed of erythrocytes aggregates formation, T (c) – time of linear erythrocytes aggregates formation, I2,5 [%] – parameter characterizing durability of most large erythrocytes aggregates, β (c-1) – hydrodynamic durability of erythrocytes aggregates were evaluated in erythroaggregometer by registration of intensity of inverse light scattering from blood sample. PA activity was measured with DAS4. CHD development risk score was determined considering traditional CVR factors – age, total cholesterol (TCH) and high density lipoproteins (HDLP) level, systolic blood pressure (SBP), presence of diabetes, smoking. Serum C-reactive protein (CRP) and fibrinogen concentration was measured with standard methods. Correlation analysis was performed with Spearman range correlation coefficient (R), Mann-Whitney (U) test was used for groups comparison and p<0,05 was considered as statistically significant level. Results. EA disturbances corresponding to 2nd stage of severity were present in all pts with PA. Significant correlation between EA parameters (T , Kt, I2,5, β) and DAS4 (R=-0,32/0,32/0,33/0,25, p<0,001) as well as significant correlation of all EA parameters (T , Kt, I2,5, β) with laboratory inflammation markers: CRP (R=-0,37/0,41/0,46/0,32), ESR (R=-0,34/0,35/0,42/0,26) and most strong – with fibrinogen (R=-0,55/0,55/0,49/0,32) were revealed. Significant correlations of all EA parameters and fibrinogen with CVR level was found in all pts (R=-0,31/0,35/0,23/0,22, p<0,001). In women relationship between EA parameters, fibrinogen and CVR level was stronger (R=-0,42/0,41/0,40/0,27). In men correlation between EA parameters, fibrinogen and CVR was not found. Conclusion. EA parameters in PA are biomarkers of inflammation and CVR.

Influence of low molecular weight hydroxyethyl starch (HES 40/0.5-0.55) on hemostasis and hemorheology.

Hydroxyethyl starch (HES) with a high or medium molecular weight (MW) and a high degree of substitution is difficult to degrade and leads to an accumulation of large molecules. These molecules have a negative effect on hemostasiological parameters. In 10 patients with cerebrovascular diseases, a hemodilution therapy was carried out with low MW HES for 10 days. Due to the low MW of the HES used (56-61 kD), the rheological parameters erythrocyte aggregation and plasma viscosity were significantly lowered (p < 0.01). No coagulation parameters studied were affected beyond the dilution effect, which was measured using the decline in hematocrit. Low MW starch is a volume substitute that is well-suited for repeated infusion or hemodilution therapy, particularly for patients with increased hemorrhagic diathesis, because it does not affect hemostasis. The disadvantage of a relatively short volume effect can be compensated through a continuous infusion of a larger volume.

Simultaneous determination of hematocrit, aggregate size and sedimentation velocity by He-Ne laser scattering.

A method has been developed to study erythrocyte aggregation parameters based on He-Ne laser light scattering. Laser light is passed through a well mixed sample of blood and the forward scattered light intensity is recorded continuously. The orientation of erythrocytes, formation of aggregates and their sedimentation under the gravitational field produces a variation in scattered light intensity. The amplitude and frequency of light signal fluctuations depend on the size of aggregates and their sedimentation velocity. From the recorded light signal, the different erythrocyte aggregation parameters of interest are simultaneously obtained.