Clinical Hemorheology and Microcirculation - Volume 14, issue 6

Authors: Potron, G. | Nguyên, P. | Pignon, B.

Article Type: Review Article

Abstract: Easily measured in large series of samples, fibrinogen has been extensively studied in the epidemiology of cardiovascular risk factors. Ten large studies have concluded that fibrinogen is a risk factor of equal or higher value than total cholesterol. In coronary diseases, fibrinogen is an independent risk factor and has a prognostic value. After stroke, high fibrinogen level is an index of severity. In peripheral arterial disease, it indicates the risk of reocclusion after surgery. The role of fibrinogen in arterial occlusion is multiple: composition of the atheroma plaque, thrombi formation, endothelial injury, hyperviscosity. Many parameters increase fibrinogen: inflammation, ageing, …smoking. Genetic control of fibrinogen is a promising field for future research in epidemiology. Many drugs decrease fibrinogen: fibrates, platelet inhibitor ticlopidin and should be used for this purpose. Lastly, physical exercise, if sustained enough, effectively reduces fibrinogen. Show more

DOI: 10.3233/CH-1994-14601

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 739-767, 1994

Authors: Streekstra, G.J. | Zwaginga, J.J. | Nijhof, E.J. | Sixma, J.J. | Heethaar, R.M.

Article Type: Research Article

Abstract: In order to obtain insight into the relation between blood viscosity and plasma viscosity, we measured these two parameters in 18 Nephrotic Syndrome patients (NS) and in 17 controls. We also measured red cell deformability (ektacytometry) and plasma protein concentrations. The plasma protein composition showed the abnormalities commonly observed in NS: reduced total protein (TP), reduced albumin (Alb) and increased fibrinogen levels. In NS we found significant correlations between plasma viscosity and fibrinogen and between plasma viscosity and the TP minus Alb fraction. In this study, there was no difference in the mean values for the hemorheological parameters between patients …and controls. However, the ranges in plasma viscosity and blood viscosity were considerably larger in NS than in the controls. These large ranges made this group of patients a suitable one in which to study the relation between blood viscosity and plasma viscosity. In NS we found that blood viscosity was not proportional to plasma viscosity, although this is normally assumed to be the case. An important consequence of this finding is that relative viscosity, which is assumed to reflect red cell deformability only, is also influenced by plasma viscosity. The dependence of relative viscosity on plasma viscosity means that this parameter needs to be reinterpreted. Show more

Keywords: blood viscosity, plasma viscosity, relative viscosity, Nephrotic Syndrome, plasma protein composition, red cell deformability

DOI: 10.3233/CH-1994-14602

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 769-778, 1994

Authors: Qin, Fu-Zhong | Zhao, Rong-Rui

Article Type: Research Article

Abstract: To evaluate the effects of reduced red cell deformability on coronary hemodynamics and cardiac function, the coronary artery was perfused with blood containing partially hardened red cells pretreated with glutaraldehyde (gblood) in dogs. During 30 min of gblood perfusion, the coronary flow (CF) decreased and the coronary vascular resistance (CVR) increased (p<0.01); the regional and global left ventricular function were impaired significantly with p<0.01 for all the measured variables; and the myocardial ultrastructural changes were characterized by a severe trapping of red cells in capillary and other moderate ischemic injuries. Pretreatment with aspirin could markedly attenuate the extent of the …above changes while a-adrenergic blockade with phentolamine did not alter these changes. In sharp contrast to the intracoronary infusion route, gblood infused through intravenous route showed no effects on CVR and cardiac function. All the changes initiated by intracoronary perfusion of gblood were similar in nature to those induced by ischemia. Thus, red cells with reduced deformability perfused into coronary artery, but not femoral vein, caused a significant decrease in CF and the resultant impairment of cardiac function. The reduction in CF was not due merely to plugging up the circulation by abnormal red cells, but may also be mediated through platelet aggregation or release of some vasoconstrictor substances from platelets. Show more

Keywords: erythrocyte deformability, coronary circulation, heart function, myocardial ultrastructure

DOI: 10.3233/CH-1994-14603

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 779-787, 1994

Authors: Wang, X. | Stoltz, J.F.

Article Type: Research Article

Abstract: The authors studied the global transport of red blood cells (RBC) in a cylindrical vessel. Human blood was considered as a homogeneous incompressible fluid. The level of transported RBC was approached with the use of different models of constitutive equation: i) a Newtonian model with apparent viscosity measured at a shear rate of 128 sec−1 ; ii) a viscosity relationship for hardened RBC suspension; iii) three non-Newtonian models (Casson equation, power law and Sisko type relationship). It was observed that the optimal hematocrit values obtained with the non-Newtonian models depended on flow conditions (vessel radius and pressure drop) and were …generally greater in high shear flow than in low shear flow. It was also found that the optimal hematocrit was particularly low for rigid RBC suspensions. These theoretical results require experimental verification and more theoretical investigations of mechanical transport of RBC (oxygen transport efficiency) under different flow conditions. Show more

Keywords: blood non-Newtonian behaviour, RBC transport, optimal hematocrit, blood flow

DOI: 10.3233/CH-1994-14604

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 789-796, 1994

Authors: Turchetti, V. | De Matteis, C. | Leoncini, F. | Picciolini, F. | Trabalzini, L. | Guerrini, M. | Forconi, S.

Article Type: Research Article

Abstract: Cytosolic calcium is an important parameter of cell functionality and its concentration is determined by homeostatic mechanisms which are ATP dependent. When an energetic depletion occurs, as in the case of ischaemia, uncontrolled accumulation of ion in the cytosol, with a reduction of membrane deformability, and the modification of the physiologic shape of erythrocyte can be noted. Pentoxifylline has a rheological effect acting on energetic metabolism of red cells. Our objective was to verify the action of pentoxifylline on calcium concentration and on the erythrocytic morphology of cell ageing. We used as ageing model the conservation of blood in vitro: …3 blood samples (from 6 taken by 8 normal subjects), have been incubated with pentoxifylline (1.4×10−4 M). We dosed cytosolic calcium and evaluated cell morphology in 2 samples (with and without pentoxifylline) in basal conditions, after 4 and after 8 hours of conservation at 37°C. Dosage of intraerythrocytic calcium was made with FURA2-AM (Calbiochem) according to the David-Dufilho method. Erythrocytic morphology was evaluated with an optical microscope following the Zipursky method. Results showed a reduction of the increase of cytosolic calcium and a major conservation of the erythrocytic physiologic morphology in samples incubated with pentoxifylline after 4 and 8 hours in comparison with control samples. These observations confirm that pentoxifylline delays uncontrolled accumulation of calcium which, in ageing, causes cell suffering and keeps its morphologic physiology for a longer time. Show more

Keywords: pentoxifylline, intraerythrocytic calcium, red cell morphology

DOI: 10.3233/CH-1994-14605

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 797-805, 1994

Authors: Brun, J.F. | Micallef, J.P. | Orsetti, A.

Article Type: Research Article

Abstract: Increases in blood viscosity during various kinds of strenuous exercise have been repeatedly described. In this study we investigated the rheologic effects of long duration low intensity exercise. Twelve volunteers (21–39 yr, 6 men and 6 women), after overnight fasting, performed a 60min exercise on cycloergometer at 55% of the theoretical maximal heart rate. After an early increase at the 10th minute (p<0.001), blood lactate decreases (p<0.02) and returns to normal. During exercise there is an increase in plasma viscosity (p<0.001) and hematocrit (p<0.05) at the 10th minute. Red cell rigidity index “Tk” increases at the 20th minute (p<0.05). Whole …blood viscosity (p<0.01) increases and hematocrit/viscosity ratio decreases (p<0.01). Thus, a light prolonged work load induces a transient hyperviscosity pattern very similar to that which is observed during strenuous exercise bouts. Show more

Keywords: Blood viscosity, hematocrit, exercise, hemorheology, erythrocyte deformability, blood lactate

DOI: 10.3233/CH-1994-14606

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 807-818, 1994

Authors: Navarro-Prigent, M.J. | Rabetafika, E. | Bournier, O. | Boivin, P. | Dhermy, D.

Article Type: Research Article

Abstract: The unique mechanical properties of mammalian red cell membranes are conferred by a specialized submembrane reticulum of proteins referred to as the membrane skeleton. Studies performed in vitro have suggested that the phosphorylation status of many skeletal proteins could be critical to the structure and function of the erythrocyte membrane. Systematic studies were performed to correlate skeletal protein phosphorylation status with membrane properties such as deformability and mechanical resistance to shear stress. Okadaic acid (OA), an inhibitor of serine-threonine phosphatases was used to obtain in situ hyperphosphorylation of all the major skeletal phosphoproteins. To analyse the cellular rheology of erythrocyte, …an ektacytometer was used to study the deformability of red cells and the mechanical stability of erythrocyte membranes. Using this technique, a dose response relationship was found between the increase in phosphorylation of the major skeletal proteins and the decrease in the mechanical stability of the erythrocyte membrane. In contrast, erythrocyte deformability was not affected, confirming that erythrocyte deformability and stability are two distinct membrane properties. Show more

Keywords: Erythrocyte membrane, ektacytometer, phosphorylation, okadaic acid

DOI: 10.3233/CH-1994-14607

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 819-830, 1994

Authors: Persson, Sylvi U. | Hedner, Pavo

Article Type: Research Article

Abstract: For transfusion purpose, red blood cells can be frozen with glycerol for a long time. After thawing the red cells are washed, the intracellular glycerol is exchanged with water, and then the cells can be transfused. Most of the red blood cells that have been frozen have a potential for normal longterm survival after transfusion, but some of them become altered during the preservation procedure and are removed from the recipient's circulation, one possible mechanism for this being trapping of red cells in the spleen due to reduced deformability. The aim of this study was to investigate the sensitivity of …the St George's filtrometer to detect possible deformability defects in frozen, thawed and deglycerolized red blood cells. The suspension of deglycerolized cells showed a significant reduction in filterability indicating the presence of cells with reduced deformability. IrFR was decreased (p<0.05), RCTT increased (p<0.05) and CP increased (p<0.001). We found a reduction of filterability in these cells roughly corresponding to the presence of 0.01–0.1% glutaraldehyde treated cells. When 10% of the erythrocytes in a blood sample were hemolyzed and thus in ghost form IrFR and RCTT were unaffected, while CP was significantly increased (p<0.05). A suitable sampling technique may, however, minimize the influence from ghosts in blood samples used for filtrometry after freezing. Thus, in evaluating different freezing techniques filtrometry with the St George's instrument seems to have a high capacity to detect and quantify preservation injuries leading to decreased deformability in the red blood cells. Show more

Keywords: Blood storage, erythrocyte deformability, erythrocyte membrane, glycerol, hemorheology, transfusion

DOI: 10.3233/CH-1994-14608

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 831-840, 1994

Authors: Lechner, H. | Schmidt, R. | Reinhart, B. | Grieshofer, P. | Koch, M. | Fazekas, F. | Niederkorn, K. | Horner, S. | Irmler, A. | Freidl, W.

Article Type: Research Article

Abstract: To determine the influence of various hemorheologic factors on carotid atherosclerois and white matter abnormalities in normals we studied 112 neurologically asymptomatic individuals aged 50 to 70 years by Doppler sonography and MRI. Atherosclerotic vessel wall changes and white matter foci were noted in 66 (58.9%) and 62 (55.4%) individuals, respectively. After correcting for group differences in age and mean arterial blood pressure by the use of an analysis of covariat test, subjects with carotid disease had higher plasma fibrinogen concentrations than those with a normal vessel wall status (327.1+/−72.7 mg/dl vs 296.3+/−67.1 mg/dl, p=0.03). A similar association was found …in the presence of MRI white matter abnormalities (330.1+/−76.7 mg/dl vs 295.1+/−60.4 mg/dl, p=0.04). Partial correlations revealed a positive relationship between fibrinogen level and the severity of both carotid (r=0.21, p=0.03) and white matter damage (r=0.24, p=0.009). Other rheologic variables including whole blood and plasma viscosity, hematocrit as well as red cell transit time were not related to evidence of abnormal imaging findings. Our data demonstrate a clear association between plasma fibrinogen with large and small vessel atherosclerosis. As to whether elevations of serum fibrinogen are only the epiphenomenon of atherosclerotic damage or represent a vascular risk factor per se can only be determined by prospective longitudinal studies. Show more

Keywords: Carotid atherosclerosis, MRI white matter disease, plasma fibrinogen, normal volunteers

DOI: 10.3233/CH-1994-14609

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 841-846, 1994

Article Type: Abstract

DOI: 10.3233/CH-1994-14610

Citation: Clinical Hemorheology and Microcirculation, vol. 14, no. 6, pp. 847-853, 1994