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Biomedical subjects

O K Baskurt

Publications and source records attributed to O K Baskurt.

27 records · Page 2Linked to original sources
PubMed1997

Red blood cell aggregation in experimental sepsis.

Red blood cell (RBC) aggregation was investigated in a rat model of sepsis with special emphasis on RBC-related factors. Sepsis was produced by cecal ligation/puncture, whereas another group had only laparotomy (sham operation); blood samples also were obtained from control, unoperated-on animals. RBC aggregation was measured in autologous plasma and in 3% dextran 70, 18 hours after the operations, by using a Myrenne Aggregometer system and the zeta sedimentation ratio (ZSR) method. RBC aggregation in autologous plasma was found to be enhanced in both sham-operated and septic animals and was consistent with their increased plasma fibrinogen levels. However, RBC aggregation in dextran was significantly higher than control only in the sepsis group. RBCs from septic animals also aggregated more in septic plasma compared with RBCs from control animals. In the sepsis group, RBC deformability was significantly decreased, whereas RBC lipid peroxidation was significantly increased. Our results thus confirm the known increase of RBC aggregation in septicemia and, in addition, demonstrate marked alterations of intrinsic RBC properties that further enhance red cell aggregation.

Animals↗
PubMed1997

Erythrocyte aggregation tendency and cellular properties in horse, human, and rat: a comparative study.

Horse blood has a higher tendency to form red blood cell (RBC) aggregates compared with human blood, with this enhanced aggregation previously attributed to differences in plasma factors. Our results confirm this observation and further indicate that washed horse RBC also have a significantly higher aggregation tendency in dextran 70 solutions (i.e., horse RBC have a higher "aggregability"). In contrast, the aggregation tendency of rat RBC, both in autologous plasma and in dextran 70, is significantly less compared with human and horse RBC. Other rheological findings for horse and rat RBC include smaller changes in RBC deformation indexes over the same shear stress range and a lower RBC shape recovery time constant. Rat RBC also had higher two-phase aqueous polymer partition coefficients, suggesting a higher surface charge. Membrane protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed marked differences: 1) band 4.2 protein was lacking in horse RBC membranes, and 2) carbohydrate groups have different distributions in human, rat, and horse RBC, as indicated by different patterns in periodic acid-Schiff-stained protein bands. Our results clearly indicate significant differences in RBC aggregability among the three species and indicate that cellular factors contribute importantly to these differences. Furthermore, they suggest that systematic studies of blood and RBC from different species should provide insight into the mechanism(s) of RBC aggregation.

Animals↗
PubMed1992

Effect of erythrocyte deformability on renal hemodynamics and plasma renin activity.

Increased blood viscosity has been previously noted in a subgroup of patients with essential hypertension with concomitant high plasma renin activity (PRA). It has been suggested that the cause of hyperviscosity in hypertensives is the presence of circulating red blood cells (RBCs) that were rendered less deformable by significant alterations in their cationic milieu, namely an increase in intracellular concentration of calcium and sodium. The relation between RBC deformability and PRA however is not clear. Our study was conducted to examine this issue. RBC deformability was reduced experimentally, and its effects on renal blood flow, renal artery resistance, glomerular filtration rate and PRA were investigated in experimental (n = 8) and control (n = 4) groups of dogs. Blood was collected from the animals before the experiments and incubated with 0.025% glutaraldehyde. These hardened RBCs were administered to the animals through exchange transfusions. Following the exchange transfusion with the hardened RBCs, there were no changes in renal blood flow, renal artery resistance, and the creatinine clearance. The only change observed was an increase in PRA. In the control group, all parameters that were determined remained unchanged. The data are consistent with the notion that the presence of circulating hardened RBCs may by itself increase PRA, and this effect can be important in some types of hypertension and some other disorders in which impaired deformability of RBCs have been reported.

Animals↗
PubMedDate not supplied

Deformability of red blood cells from different species studied by resistive pulse shape analysis technique.

The Cell Transit Analyzer (CTA) is now being used widely in clinical hemorheology. Most of the data obtained by CTA are limited to human blood, although the CTA has an important potential to be used in experimental studies on animal models. However, behavior of red blood cells (RBC) from various species might be different in CTA. Eight parameters reflecting different aspects of cell passage through pores with 5 microns diameter and 15 microns length were determined or human, guinea pig, dog, rabbit, rat, mouse and sheep RBC, together with instrument precision and biological variation. These parameters have a wide range when measured in different species and correlate with cell volume. Sensitivity of these parameters to the glutaraldehyde-induced alterations in RBC deformability was not same for different laboratory mammals. The main reason for this difference seems to be related to the cell size and thus sensitivity might be significantly limited if 5 microns pore-size filters are used to test the smaller RBC. The results of this study may help in designing experimental studies on laboratory mammals using the CTA.

Adult↗
PubMedDate not supplied

Cellular determinants of low-shear blood viscosity.

Low-shear viscometry is one of the methods commonly used to estimate the degree of red blood cell (RBC) aggregation in various bloods and RBC suspensions. However, it has been previously shown that alterations in RBC morphology and mechanical behavior can affect the low-shear apparent viscosity of RBC suspensions; RBC aggregation is also sensitive to these cellular factors. This study used heat treatment (48 degrees C, 5 min), glutaraldehyde (0.005-0.02%) and hydrogen peroxide (1 mM) to modify cell geometry and deformability. Red blood cell aggregation was assessed via a Myrenne Aggregometer ("M" and "MI" indexes), RBC suspension viscosity was measured using a Contraves LS-30 viscometer, and RBC shape response to fluid shear stresses (i.e., deformability) was determined by ektacytometry (LORCA system). Our results indicate that low-shear apparent viscosity and related indexes may not always reflect changes of RBC aggregation if cellular properties are altered: for situations where RBC aggregation has been only moderately affected, cellular mechanical factors may be the major determinant of low-shear viscosity. These findings thus imply that in situations which may be associated alterations of RBC geometry and/or deformability, low-shear viscometry should not be the sole measurement technique used to assess RBC aggregation.

Adult↗
PubMedDate not supplied

Determination of red blood cell shape recovery time constant in a Couette system by the analysis of light reflectance and ektacytometry.

Red blood cell (RBC) shape change under shear is generally reversible, with the time course of shape recovery a function of the elastic and viscous properties of the RBC membrane. RBC shape recovery can be investigated, using several different techniques, to provide information about the membrane material properties that are not directly accessible by frequently used methods to assess RBC deformability (e.g., micropore filtration). In the present study, RBC shape recovery was studied in a Couette system after abrupt cessation of shear, either by analyzing the time course of laser light reflection or by serial measurements of elongation indexes from laser diffraction patterns. The time course of shape recovery monitored with both techniques can be described with an exponential equation. Calculated time constants for normal human RBC were 119 +/- 17 msec and 97 +/- 15 msec as measured by light reflection and ektacytometry, respectively. Treatment of RBC with glutaraldehyde resulted in dose-dependent decreases in the shape recovery time constant. Heat treatment (48 degrees C, 20 min), which is known to increase mainly the shear elastic modulus of the membrane, decreased the time constant by 65%. In contrast, wheat germ agglutinin treatment increased the shape recovery time constant by 22%, presumably by increasing membrane surface viscosity. Our results indicate that the shape recovery time constant of RBC can be measured easily and accurately by computerized light reflection analysis.

Computers↗
PubMedDate not supplied

Acute hematologic and hemorheologic effects of sulfur dioxide inhalation.

Fifty male rats were exposed to 0.87 ppm sulfur dioxide (SO2) for 24 hr. Hematologic and hemorheologic parameters measured in this group were compared with the results of a control group of 51 male rats. Hematocrit values were found to be higher (p less than .005) in the SO2-treated group (43.55 +/- 0.41%, mean +/- standard error), when compared to the control group value (41.97 +/- 0.35%). Sulfhemoglobin values were also higher (p less than .0001) in the SO2-treated group (0.60 +/- 0.08%) than the control group (0.08 +/- 0.02%). Osmotic hemolysis ratio was slightly increased (p less than .05) in the 0.55% sodium chloride solution. However, whole blood and packed cell viscosities were lower in the SO2-treated animals, while there was no significant difference in the plasma viscosities. The mechanism of these effects could not be clarified completely, but structural and functional effects of SO2 inhalation on peripheral erythrocytes were discussed.

Air Pollutants↗
PubMedDate not supplied

Hematological and hemorheological effects of air pollution.

Selected hematological parameters and erythrocyte deformability indexes for 16 young male military students were compared before and after a period of exposure to heavy pollution. These students lived in Ankara, which has a serious air pollution problem. The mean sulfur dioxide levels measured at a station proximal to the campus where the students lived were 188 micrograms/m3 and 201 micrograms/m3 during first and second measurements, respectively. During the period between the two measurements, the mean sulfur dioxide level was 292 micrograms/m3. Significant erythropoiesis was indicated by increased erythrocyte counts and hemoglobin and hematocrit levels. Methemoglobin percentage was increased to 2.37 +/- 0.49% (mean +/- standard error) from 0.51 +/- 0.23%. Sulfhemoglobinemia was present in six subjects after the period of pollution, but it was not present in any student prior to this period. Significant increases in erythrocyte deformability indexes were observed after the period of pollution, i.e., from 1.13 +/- 0.01 to 1.21 +/0 0.02, implying that erythrocytes were less flexible, which might impair tissue perfusion.

Adult↗