Clinical Hemorheology and Microcirculation - Volume 23, issue 1

Authors: Sun, R.J. | Muller, S. | Wang, X. | Zhuang, F.Y. | Stoltz, J.F.

Article Type: Research Article

Abstract: The effect of laminar flow on the regulation of von Willebrand Factor (vWF) of cultured human umbilical vein endothelial cells (HUVECs) was studied. Confluent endothelial monolayers were exposed to shear stresses (0.2 and 1.0 Pa) from 2 to 24 h. vWF was labelled with indirect immunofluorescence method and observed with 3D fluorescence microscopy. The distribution of vWF and the cytoskeleton organization were observed simultaneously by double fluorescence labelling. More actin stress fibers and an increased release of vWF appeared in the cells exposed to flow at the same time. The qualitative and quantitative results showed that there was not only …a shear‐dependent regulation but also a time‐dependent modification. For a short‐time shear stimulation, both 0.2 Pa and 1.0 Pa shear stresses induced a release of vWF from the endothelial cells. In contrast, after 24 h exposure to 1.0 Pa shear flow, vWFs were much more in the cells than that in the cells exposed to 0.2 Pa for 24 h (p<0.01) or that in the control cells (p<0.05). TNF‐α caused a decrease of vWF and Weibel–Palade bodies in the cells. Show more

Keywords: Shear stress, von Willebrand factor, endothelial cell, 3D fluorescence microscopy

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 1-11, 2000

Authors: Srour, M.A. | Bilto, Y.Y. | Juma, M. | Irhimeh, M.R.

Article Type: Research Article

Abstract: The effects of two oxygen radical generating systems (H2 O2 and ascorbate/Fe+2 ) on erythrocyte deformability, osmotic fragility, lipid peroxidation and protein degradation were studied. Incubation of erythrocytes with different concentrations of H2 O2 (5–20 mM) or ascorbate/Fe+2 (10/0.1–40/0.4 mM) caused a loss of deformability and increased osmotic fragility. The loss of deformability has occurred in a dose‐dependent fashion and was proportional to the extent of malonyldialdehyde (an indicator of lipid peroxidation) and alanine production (an indicator of protein degradation). Prior exposure of the erythrocytes to carbon monoxide (known to inhibit heme‐protein degradation) prevented almost completely the …loss in deformability caused by H2 O2 , indicating that the loss in deformability was due mainly to protein degradation rather than to lipid peroxidation. Erythrocytes incubated with either of the two systems have also shown morphologic changes characterized by a dose‐dependent increase in echinocyte formation. The results indicate the importance of oxidatively damaged proteins in compromising the rheologic behaviour of the erythrocytes, particularly when the free radicals are involved. Show more

Keywords: Erythrocyte deformability, oxygen radicals, malonyldialdehyde, protein degradation, hydrogen peroxide, ascorbate/iron, carbon monoxide

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 13-21, 2000

Authors: Srour, M.A. | Bilto, Y.Y. | Juma, M.

Article Type: Research Article

Abstract: Malonyldialdehyde (MDA), a secondary product of lipid peroxidation is widely used as an indicator of lipid peroxidation. Eight of the most frequently used methods for measuring MDA have been evaluated with regard to their sensitivity and reproducibility. The sensitivity of these methods for pure MDA solution was in the order: Satoh's > Stocks and Dormandy's >> Buege and Aust's > Dresel's >> Slater's > Yoshioka's et al. > Yagi's > Jain's method. Whereas the sensitivity of the first four methods for erythrocyte MDA was in the order: Stocks and Dormandy's >> Buege and Aust's > Satoh's > Dresel's method. The …reproducibility (expressed as coefficient of variation) of these four methods for erythrocyte MDA were: 3.5%, 17.9%, 31.5% and 16.1%, respectively. These results indicate that Stocks and Dormandy's method has the highest sensitivity and an excellent reproducibility for erythrocyte MDA. Also, it was found to be simple and many samples can be treated in a relatively short time. When standard MDA (0.1–15 nmol/ml) was incubated with erythrocytes, the percentage recovery of MDA (using Stocks and Dormandy's method) has ranged from 50–85%. This result indicates that a considerable amount of MDA formed in erythrocytes probably reacts with other cell components and becomes undetectable. Despite this, the determination of MDA level remains a useful indicator of lipid peroxidation and correlates well with the degree of oxidative stress. Show more

Keywords: Malonyldialdehyde, methods, lipid peroxidation, erythrocytes

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 23-30, 2000

Authors: Didelon, J. | Blondel, W.C.P.M. | Mazeron, P. | Muller, S. | Gigout, T. | Gentils, M. | Cauchois, G. | Stoltz, J.‐F.

Article Type: Research Article

Abstract: The aim of the present work was to validate a new technique for the measurement of resistance of the red blood cell membrane using an automated apparatus called a Fragilimeter. Its principle lies in the measurement of the extinction of a laser beam projected through a red blood cell suspension subjected, by diffusion, to a variation of salinity from an isotonic equilibrium (154 mM NaCl) to, a hypotonic one, 25 mM NaCl. The variation of osmotic pressure induces on the cells a progressive lysis and a modification of the extinction of the transmitted light. The validation of the method was …based on the comparison between results obtained with the Fragilimeter and those obtained using the reference DACIE technique. Analyses were based on blood samples from healthy donors. The determination of the initial, the 50% and the full haemolysis thresholds allowed observation of the fragility of the cell, through its membrane resistance. The physical phenomenon measured in these cells when subjected to various ionic strengths is discussed on the basis of observations realised by means of an optical microscope. Show more

Keywords: Red blood cells, osmotic resistance, fragility, haemolysis, deformability

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 31-42, 2000

Authors: Başkurt, Oguz K. | Mat, Funda

Article Type: Research Article

Abstract: It is well known that RBC rheological parameters are affected by temperature. Usually, the measurement temperature of these parameters is kept constant throughout a given study, however it can be seen that different temperatures are used by different groups, during the measurement of a given parameter. It is assumed that the data should not be qualitatively different when measured at different temperatures, although significant quantitative differences exist. This study revealed that the selected temperature for RBC elongation index measurements by ektacytometry is important in detecting a given impairment in RBC deformability induced by experimental sepsis. RBC elongation indexes were found …to be significantly different in septic and normal rats, only if measured at 37○ C. The differences in RBC aggregation parameters for septic and normal rats were also affected by the measurement temperature, however statistically significant differences were present in a wider range of temperatures between 25–37○ C. Therefore, it is strongly recommended that the measurement of RBC deformability and aggregation be performed using a controlled‐temperature device, set to 37○ C. Show more

Keywords: Temperature, erythrocyte deformability, erythrocyte aggregation, ektacytometry

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 43-49, 2000

Authors: Wen, Zongyao | Yao, Weijuan | Xie, Lide | Yan, Zong‐yi | Chen, Kai | Ka, Weibo | Sun, Dagong

Article Type: Research Article

Abstract: Surface charge was removed from RBC (erythrocyte) membrane to different degrees with biochemical methods, i.e., treatment of RBCs with neuraminidase, either using different doses for the same incubation time (1 hour) or using the same dose (75 milli‐unit) for different incubation time. Several rheological properties of the RBCs with surface charge removal were observed, including the deformation index DI (using traditional ektacytometry) orientation index (DI)or and small deformation index (DI)d (using new ektacytometry), the viscosity at low and high shear rates (using a cone‐plate rotating viscosimeter). In addition, photographs of RBCs aggregation under a microscope and the histograms …of RBC aggregate size after treatment with neuraminidase were obtained. It is found from these experiments that the decrease of the surface charge of RBCs leads to the decrease in the deformation and orientation indices as well as the increase in blood viscosity. Show more

Keywords: Erythrocytes, surface charge, neuraminidase, ektacytometry, deformation index

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 51-57, 2000

Authors: Monsuez, Jean‐Jacques | Dufaux, Jacques | Vittecoq, Daniel | Flaud, Patrice | Vicaut, Eric

Article Type: Research Article

Abstract: Although cardiac and vascular complications have been recognized among patients infected with the Human Immunodeficiency Virus‐1 (HIV‐1), their vascular biology and rheology have not been studied. Rheology of red blood cells (RBC) was assessed with an erythroaggregometer in 22 HIV‐1 infected asymptomatic patients (pts) and 17 healthy HIV negative controls (C). All participants were normotensive, nondiabetics, had normal lipid levels and had an hematocrit ranging from 37 to 44% and hemoglobin levels ≥12 g/100 ml. Patients had a shorter RBC aggregation characteristic time than controls (1.49±0.17 vs. 2.04±0.41 s, p=0.001) and an increased disaggregation shear rate (166±34.9 vs. 122±25.4 s−1 …, p=0.001). This hyperaggregation tendancy was associated with increased γ‐globulin (18.3±3.3 vs. 13.7±1.9 g/l, p=0.01) and fibrinogen (3.52±0.57 vs 3.03±0.48 g/l, p=0.003) levels and with an increased erythrocyte sedimentation rate (ESR) (25±14.3 vs. 12.3±7.5 mm, p=0.02). Even in patients with ESRs ranging within normal values (≤20 mm), the aggregation characteristic time was found lower in patients than in controls (p=0.004). There was no correlation between these rheological changes and the CD4+ T‐cell count. The 17 patients receiving an antiviral therapy had lower CD4+ T‐cell counts than their 5 untreated counterparts (244.7±167 vs. 410±106/mm3 , p=0.025), and a higher disaggregation shear rate (177.4±38.2 vs. 127±25.4, p=0.01). Thus, an impairment of rheological characteristics is observed in asymptomatic HIV‐1 infected patients in association with changes in plasma proteins. Show more

Keywords: AIDS, hemorheology, erythrocyte aggregation, vascular biology

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 59-66, 2000

Authors: Martínez, Marcial | Vayá, Amparo | López‐Camacho, Carolina | Coll‐Sangrona, Enriqueta | Mira, Yolanda | Aznar, Justo

Article Type: Research Article

Abstract: The usefulness of heparins as anticoagulants has been demonstrated, but their effects on hemorheological parameters, such as erythrocyte aggregability, are under discussion. If the heparins had adverse effect on erythrocyte aggregability, its use would be especially undesirable in patients with pathologies involving red blood cell hyperaggregability as is the case of cardiac disease. In the present study we examine the in vitro effect of unfractionated and fractionated heparins on red blood cell aggregability. The results show that heparins do not increase this rheological parameter but show a slight tendency to lower it.

Keywords: Unfractionated heparin, fractionated heparin, erythrocyte aggregability

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 67-70, 2000

Authors: Potron, Gérard | Nguyên, Philippe

Article Type: Other

Citation: Clinical Hemorheology and Microcirculation, vol. 23, no. 1, pp. 71-72, 2000