Effect of Erythrocyte Density on Blood Clot Properties in Healthy Individuals and in Patients with Hemophilia A.

We measured specific volume and hematocrit of blood clots prepared from the whole blood of patients with hemophilia A and healthy male volunteers. It was shown that in the hematocrit range of 43.5-52.5%, specific volume of the blood clot in hemophilia patients with low level of factor VIII (1-4%) was higher than in volunteers. After injection of factor VIII, specific volume of blood clots in hemophilia patients decreased. Hematocrit of the blood clots derived from the whole blood linearly depended on the mean erythrocyte density in both volunteers (r=-0.74, p=0.01) and patients with factor VIII level of 1-4% (r=-0.95, p<0.0001). The increase in the mean erythrocyte density led to a decrease in blood clot hematocrit. The curve describing blood clot hematocrit as a function of the mean erythrocyte density in hemophilia patients was lower than in healthy volunteers. The increase in factor VIII level was associated with an increase in blood clot hematocrit. The results showed that blood clot hematocrit depends on the mean erythrocyte density, and therefore, hematocrit of the blood clot can be changed by modulating the properties of erythrocyte population.

Prediction of Intraoperative Blood Loss during Total Knee Arthroplasty in HCV+ and HCV- Patients with Hemophilia A.

We examined HCV+ and HCV- hemophilia A patients with knee arthropathy and hematocrit above 38.5%. The mean density of erythrocytes was studied by the phthalate method, intraoperative blood loss was assessed gravimetrically. The volume of blood loss in HCV+ patients with manifest adhesive process and chronic synovitis varied from 300 to 1900 ml, in patients with moderate adhesive process from 400 to 1500 ml. The volume of blood loss in HCV- patients was 300-800 ml. A positive correlation between the blood loss volume and mean density of erythrocytes was detected. Blood loss >1000 ml during total knee arthroplasty can be expected in patients with hemophilia A with HCV and high mean density of erythrocytes. Blood loss >1000 ml is unlikely in HCV- and HCV+ patients with the mean density of erythrocytes not surpassing the normal values.

Effect of Hematocrit and Erythrocyte Density on Intraoperative Blood Loss in Hemophilia A Patients During Total Knee Arthroplasty.

Intraoperative blood loss during total knee arthroplasty in patients with hemophilia varies over a wide range (from 300 to 3000 ml). The reasons have not been clarified yet. We studied the dependence of intraoperative blood loss during total knee arthroplasty in patients with hemophilia A on hematocrit and mean erythrocyte density. Intraoperational blood loss ≥1000 ml was observed in patients with hematocrit <38.5%. In patients with hematocrit >38.5% this parameter depended on the mean erythrocyte density: in patients with increased erythrocyte density, the risk of intraoperational blood loss ≥1000 ml was higher. The increase in erythrocyte density can serve as an indicator of pathological processes, including the processes modulating hemostasis. It can also be assumed that erythrocytes with higher density change blood flow, which affects platelet adhesion to the damaged endothelium. Hematocrit below the threshold level and mean density of erythrocytes above the normal level can be regarded as risk factor for increased intraoperational blood loss.

Filtration method for studies of the kinetics of hypo-osmotic pore closure in erythrocyte.

Filterability of erythrocytes through small (3 µ) pores decreases with decreasing osmolarity of suspension medium because of hypo-osmotic swelling of cells. After appearance of lytic pores, erythrocyte filterability increases for some time, while after recovery of membrane integrity it decreases again. We suggest filtration method for studies of the kinetics of hypo-osmotic lytic pores closure. The dynamics of changes in erythrocyte filterability was studied in 2 patients with paroxysmal nocturnal hemoglobinuria and 6 donors (Ht 0.01%, Na phosphate buffer 5 mM, pH 7.4, 35 mOsm, 24°C). The method can be used for studies of erythrocyte membrane characteristics in various diseases and for evaluation of the membranotropic effects of drugs, infusion media, hemolysins, ethanol, etc.

[Density-specific distribution of erythrocytes in different types of anemia].

AIM: To study density-specific distribution of erythrocytes (DSDE) in different types of anemia. MATERIAL AND METHODS: DSDE was determined in anemic patients by fractionation of the whole blood in hematocritic capillaries in the presence of mixtures of dimethyl- and dibutylphthalates with known density. RESULTS: Parameters are proposed which characterize DSDE changes typical for each type of anemia: mean erythrocyte density (MED)--mean density of total erythrocytic population; DSDE width (W)--a characteristic of erythrocytic population heterogeneity; light fraction of erythrocytes (LEF)--% of the cells with density less than 1.086 g/ml (hypochromic cells and reticulocytes); dense fraction of erythrocytes (DEF)--% of cells with density over 1.112 g/ml (hyperchromic cells forming as a result of erythrocyte dehydration). DSDE parameters for different types of anemia differed: reduced MED was typical for iron deficiency anemia (IDA) and paroxysmal nocturnal hemoglobinuria (PNH), increased DEF was seen in microspherocytic anemia (MSA), autoimmune hemolytic anemia (AHA), deficiency of glucose-6-phosphate dehydrogenase, increased LEF was observed in reticulocytosis in all anemia types except MSA, DSDE W was larger in MSA, AHA, PNA. CONCLUSION: DSDE is determined by proportion of erythropoiesis and sequestration of erythrocytes as well as pathological impacts leading to impairment of membrane permeability for cations and erythrocytic metabolism. Informative value of DSDE parameters makes them effective for diagnostic screening of anemias and control over course of different diseases.

Detection of stages of autoimmune hemolytic anemia by evaluating erythrocyte deformability and density.

Study of erythrocyte density and deformability in patients with hemolytic anemia, including long-term monitoring of 5 patients, helped us to characterize the pathological processes leading to changes in the erythrocyte population at different terms of the disease and to detect its main stages (agglutination, pathological dehydration, combination of pathological dehydration and microvesiculation, hemolytic crisis, and remission).

[Kinetics of decrease in erythrocyte filterability under the effect of ephazol]. / Kinetika snizheniia fil'truemosti éritrotsitov pod vliianiem éfazola.

The effect of palladium-containing complex Ephazol on the filtration rate of erythrocyte suspensions through nuclear filters was studied by the constant-pressure filtration method. It was shown that the filterability of red blood cells incubated with ephazol decreased. If the time necessary for a fixed volume of red blood cell suspension to pass through a filter was plotted against the time of incubation with Ephazol or against its initial concentration, the curves typical of autoaccelerated processes were obtained. From analysis of kinetic models, it was concluded that the effects observed are due to the nonlinear dependence of the filtration rate w on the rate at which an erythrocyte passes through a pore and the influence of Ephazol on the distribution of erythrocytes with respect to w. Several models describing changes in the distribution of erythrocytes with respect to w in the presence of Ephazol and possible mechanisms relating the filtration kinetics to the incubation parameters are discussed.

Distributions of rheological parameters in populations of human erythrocytes.

We have previously proposed the osmofiltration method based on a modified Hanss hemorheometer to analyze distributions of erythrocytes in their ability to pass through membrane filters with 3 microns pores. Upon decrease in medium osmolality (u) the erythrocyte volume increases. When cell volume becomes V = Vcr at u = ucr, such cell loses its ability to pass through a 3 microns pore. The flow rate of erythrocyte suspension containing cells with different ucr through a filter gradually decreases with decreasing medium osmolality. This rate becomes zero at some u = omega, when the number of non-filterable cells in the applied sample approaches the number of pores in filter. Experimental determination of the dependencies of the filtration rate on medium osmolality for various hematocrit values allows to obtain omega for each hematocrit and, thereby, to assess the distribution of erythrocytes in ucr. Here, we propose a simplified version of this method, which allows screening of the erythrocytes in heterogeneous suspensions for the distribution in ucr by measuring omega for only two hematocrit values, 0.1% and 1%. Applications of the proposed method are exemplified by analysing the erythrocyte populations of healthy donors, of patients with microspherocytosis, hemochromatosis and normal erythrocyte populations in an acidic environment.

A modification of the filtration method for studying the content of nonfilterable cells in erythrocyte suspension.

The results of filtration assays provide estimates of the deformability of erythrocytes averaged over the entire suspension. These assays do not distinguish whether the entire population or only its small fraction exhibits abnormal rheological properties. We developed a simple method using a filtrometer to determine the percentage of non-filterable (under given conditions) cells in the erythrocyte suspension. Membrane filters made of a polyethylene terphthalate film had the mean pore diameter of 3.1 microns and the length of cylindrical micropores of 7 microns. The buffer flow rate tb depends on the number of free pores in a filter. The plot of the number of pores clogged by non-filterable cells versus the total number of erythrocytes passed through the filter had a linear portion whose slope represents the relative content Z of non-filterable cells in the suspension. We determined Z for various medium osmolarities u. These data were used to derive the distribution of erythrocytes in ucr, the value of u at which an erythrocyte cannot pass through a pore of a given filter because of geometric limitations. The distribution maximum corresponded to 190-200 mOsm/kg for erythrocytes from the normal blood. This means that normal erythrocytes have the median values of their surface area and area-to-volume ratio of 155-151 microns2 and 1.72-1.68 microns-1, respectively. The half-width of the distribution was approximately 30 mOsm/kg. This finding suggests that the normal blood contains a certain fraction of erythrocytes with a decreased area-to-volume ratio. Our results showed that the distribution is altered in various forms of anemia and in ATP-depleted erythrocyte suspensions.

Determination of the content of nonfilterable cells in erythrocyte suspensions as a function of the medium osmolality.

The results of most filtration assays for deformability of erythrocytes do not distinguish whether the entire population or only its small fraction exhibits abnormal rheological properties. We developed a simple filtration method for determination of the percentage of nonfilterable cells in erythrocyte suspension using membrane filters with mean pore diameter of 3.1 microns. This method makes it possible to detect even minor abnormal subpopulations in erythrocyte suspensions. The flow rate of buffer depends on the number of free pores of a filter. The plot of the number of pores clogged by nonfilterable cells vs the total number of erythrocytes that were allowed to pass through the filter had a linear portion, with a slope representing the relative content, Z%, of nonfilterable cells in the suspension. We determined Z% for various medium osmolalities u and used the data to derive the distribution of erythrocytes in ucr (ucr is the maximum value of u at which an erythrocyte cannot pass through a pore of a given filter because of geometric limitations). The distribution of ucr in suspension of normal erythrocytes has a maximum of about 200 mOsm/kg and a half-width of about 20 mOsm/kg. The distributions of ucr are altered in normal erythrocyte suspensions at decreased pH values, in cryopreserved and ATP-depleted erythrocyte suspensions and in erythrocytes from a xerocytosis patient.