Clinical Hemorheology and Microcirculation - Volume 25, issue 1

Authors: Hardeman, M.R. | Dobbe, J.G.G. | Ince, C.

Article Type: Research Article

Abstract: The Laser‐assisted Optical Rotational Cell Analyzer (LORCA) is unique in its capacity to measure at least two important hemorheological parameters, i.e., deformability of red blood cells (RBC) as well as their aggregation behaviour. In this communication the main principles and characteristics of the aggregometer mode of this instrument are described. Via syllectometry (i.e., laser backscatter versus time), the method allows the measure of both static and kinetic parameters of the aggregation process, e.g., total extent of aggregation, aggregation half time and a combination of these, defined as aggregation index. When the syllectogram deviates from that representing normal rouleaux formation, e.g., …in the case of RBC clump formation, this is signalled by a fit error. Maximal flexibility is obtained by various options like an automated re‐iteration procedure (which enables to measure the aggregation tendency and/or the aggregate stability) and aggregation at low shear rate. Experiments dealing with reproducibility, stability and sensitivity of the instrument are described. The latter include a few “classic” methods for inducing subtle changes in RBC aggregation behaviour both regarding cellular factors (heat treatment) and changes in medium constituents (fibrinogen, dextrans). It can be concluded that the aggregometer mode of the LORCA considerably increases the feasibility of this instrument for hemorheological investigations. Show more

Keywords: LORCA, aggregometer, red blood cell, rouleaux formation, red cell aggregation

Citation: Clinical Hemorheology and Microcirculation, vol. 25, no. 1, pp. 1-11, 2001

Authors: Di Massimo, C. | Penco, M. | Serri, F. | Tozzi‐Ciancarelli, M.G.

Article Type: Research Article

Abstract: Fifteen long‐lived and fifteen young healthy subjects were enrolled in this study to verify the involvement of age‐associated oxidative challenge in the mechanisms that control platelet activation. Our results showed in old subjects an enhancement of ex vivo platelet responsiveness to ADP and collagen, measured both in whole blood and in platelet rich plasma, an increased cytosolic calcium content, a decreased membrane fluidity and a lower intraplatelet nitrate/nitrite (NOx ) amount. Additionally, an increased plasma content of peroxidative by‐products (TBARS) and a decreased antioxidant plasma capacity together with a reduced lag time for in vitro oxidation of low density lipoprotein …(LDL) and a diminished plasma NOx bioavailability were observed in aged subjects. Lag time for LDL oxidation was negatively correlated with plasma TBARS level, and positively correlated with intraplatelet NOx content. Findings of this study may support the speculation that advancing age increases the susceptibility of LDL to oxidative modifications and favors platelet activation by oxidized LDL‐induced decrease of nitric oxide bioactivity. Show more

Keywords: Elderly, platelet sensitivity, nitric oxide, ox‐LDL

Citation: Clinical Hemorheology and Microcirculation, vol. 25, no. 1, pp. 13-20, 2001

Authors: Jünger, Michael | Friedrich, Björn | Hahn, Jens | Klyscz, Thomas | Müller, Claudia A. | Schmid‐Schönbein, Geert W.

Article Type: Research Article

Abstract: In this study we analysed blood samples taken from the dorsalis pedis vein and a brachial vein of 11 healthy test persons and 8 patients with venous leg ulcer under experimental venous hypertension in order to examine changes in the expression of leukocyte adhesion molecules (LFA‐1 (CD11a), Mac‐1 (CD11b), p150,95 (CD11c), CD18, VLA‐4 (CD49d) and L‐selectin (CD62L)) which are involved in the adhesion steps of leukocytes to endothelial cells for transmigration into tissues. Under orthostatic stress, lymphocytes in controls collected at the foot level showed a significant reduction in the expression of L‐selectin (p=0.002), compared to those of patients. …This finding suggests that venous stasis negatively influences the expression of L‐selectin on leukocytes only in healthy volunteers. Patients with chronic venous insufficiency seem to suffer from a specific defect in the regulation of L‐selectin shedding under orthostatic stress. Show more

Keywords: Varicose‐ulcer pathophysiology, varicose‐ulcer immunology, venous leg ulcer, leukocyte‐adhesion‐molecules

Citation: Clinical Hemorheology and Microcirculation, vol. 25, no. 1, pp. 21-30, 2001

Authors: Ciuffetti, Giovanni | Lombardini, Rita | Pirro, Matteo | Lupattelli, Graziana | Mannarino, Elmo

Article Type: Research Article

Abstract: The usefulness of Clopidogrel as inhibitor of platelet aggregation has been demonstrated, but its effect on hemoreological parameters, such as whole blood viscosity at low and high shear rate, red cell aggregation and deformability indexes, filterability rate and and deformability of red blood cells has not been studied. This study revealed that, in subjects with impaired blood rheology and ultrasound evidence of atherosclerosis, 3‐weeks treatment with clopidogrel (75 mg daily) improved blood viscosity at high shear rate and other hemorheological parameters, including red cell filterability rates and dynamic red cell deformability index (p<0.01 for all), without any unwanted side effect. …Blood viscosity at low shear rate and red cell aggregation index improved after only 1‐week treatment, and the reductions were mantained after two and three weeks (p<0.01). These results indicate that, similarly to another thienopyridine such as ticlopidine, Clopidogrel may have a positive influence on several hemorheological parameters, thus exerting its protection not only through inhibition of platelet function, but also through changes in the hemorheological profile. Show more

Citation: Clinical Hemorheology and Microcirculation, vol. 25, no. 1, pp. 31-39, 2001