Clinical Hemorheology and Microcirculation - Volume 49, issue 1-4

Authors: Tikhomirova, Irina A. | Oslyakova, Anna O. | Mikhailova, Svetlana G.

Article Type: Research Article

Abstract: We estimated hemorheological parameters of vein blood samples and cutaneous microvascular blood flow in patients with acute ischemic stroke and in controls. The worsened blood rheological properties were registered in patients with stroke: the enhanced whole blood viscosity was due to the substantial increase of plasma viscosity and the impairment of microrheological blood properties: elevated erythrocyte aggregability and decreased deformability compared to the healthy group. The decrease of oxygen consumption fixed by rheological methods and by laser Doppler flowmetry led us to conclude that the tissue hypoxia took place in patients with stroke. The regulatory mechanisms aimed to maintain blood …supply to tissue were activated under cerebral infarction and the impact of unfavorably changed rheological blood properties was markedly enhanced. Revealed close interrelations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue. Show more

Keywords: Microcirculation, hemorheology, stroke, regulatory mechanisms

DOI: 10.3233/CH-2011-1480

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 295-305, 2011

Authors: Reinhart, W.H. | Geissmann-Ott, C. | Bogdanova, A.

Article Type: Research Article

Abstract: Purpose: Red blood cells (RBCs) express N-methyl D-aspartate (NMDA) receptors on their surface. We tested if NMDA receptor activation or inhibition had an influence on RBC deformability and aggregability. Methods: Heparinized blood was drawn from healthy volunteers and centrifuged. RBCs were washed twice and resuspended with a hematocrit of 30% in a same buffer solution containing 3% dextran 70. Aliquots were prepared: a) control; b) containing 100 μM homocysteic acid (NMDA receptor agonist); c) 100 μM memantine (NMDA receptor inhibitor) and 100 μM homocysteic acid. RBC suspension viscometry (Contraves LS-30) was done at 37°C with shear rates of 37.6 s−1 …and 0.1 s−1 . RBC aggregability was assessed with a Myrenne aggrometer and sedimentation rate. Results: Neither NMDA receptor activation nor inhibition had an influence on biophysical properties of RBCs. RBC suspension viscosity at a shear rate of 37.6 s−1 was 3.62 ± 0.16, 3.61 ± 0.13, and 3.62 ± 0.16 mPa.s for control, homocysteic acid, and memantine + homocysteic acid, respectively, indicating an unchanged RBC deformability. The RBC aggregability parameters (low shear viscosity, Myrenne aggregometry at stasis (M) and 3 s−1 (M1 ), and the sedimentation rate) showed no influence of either memantine and/or homocysteic acid. A large interindividual variability in RBC aggregability was observed. A good correlation was found between M, M1 and sedimentation values, but not with low shear viscosity values. Conclusions: An activation or inhibition of NMDA receptors on RBCs has no influence on their deformability and aggregability. RBC aggregability varies largely among individuals, which was consistently detected by the sedimentation rate and the Myrenne aggregometer, but not by low shear viscosity, which should not be used for this purpose. Show more

DOI: 10.3233/CH-2011-1481

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 307-313, 2011

Authors: Ruef, P. | Ehrhard, M. | Frommhold, D. | Koch, L. | Fritzsching, B. | Poeschl, J.

Article Type: Research Article

Abstract: There are several reports demonstrating an involvement of bacterial toxins in the rigidity of red blood cells (RBC). The present study investigates the influence of E. coli F-583-Rd lipid A on RBC deformability under mechanical shear stress. Verapamil (Ca2+ channel inhibitor), staurosporine (protein kinase inhibitor) and Y-27632 (rho-kinase inhibitor) were used to modify the effect of lipid A on RBC deformability. We also determined if E. coli F-583-Rd Lipid A could induce an increase of intracellular Ca2+ concentration. For the deformation measurements RBC (10 adult donors) were incubated with E. coli F-583-Rd lipid A (100μg/ml) and also co-incubated …with either verapamil (10−7 mol/l), staurosporine (10−7 mol/l) or Y-27632 (10−7 mol/l). The deformation of the RBC under different shear stresses (0.6–60 Pa) was measured by a shear stress diffractometer (Rheodyne SSD). Intracellular Ca2+ was determinded by flow cytometry in RBC incubated with Lipid A and labeled with fluorescent Fluo-4/AM which binds intracellular Ca2+ with high affinity resulting in enhanced green fluorescence intensity. At increasing shear stresses Lipid A induced a significantly lower elongation. Co-incubation of the erythrocytes with verapamil or staurosporine inhibited lipid A induced decrease in elongation while Y-27632 had no effect. Verapamil, Staurosporine and Y-27632 did not influence the elongation response of the cells under control conditions. Lipid A induced a marked increase in fluorescence Fluo-4/AM indicating increased intracellular Ca2+ . These results suggest that E. coli F-583-Rd lipid A is able to influence red blood cell rigidity by a rapid and significant increase of intracellular Ca2+ concentration. Verapamil and staurosporine abolished the decrease in deformability of Lipid A incubated RBC. Show more

Keywords: Red blood cell, sepsis, lipid A, Ca$^{2+}$, deformability, staurosporine, verapamil, rho-kinase-inhibitor

DOI: 10.3233/CH-2011-1482

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 315-322, 2011

Authors: Fornal, Maria | Korbut, Renata A. | Grodzicki, Tomasz

Article Type: Research Article

Abstract: Relationship between erythrocyte deformability and: a) soluble cell adhesion molecules concentration, b) glomerular filtration rate (eGFR) has been investigated in three study groups: a group of 20 patients with diagnosed arterial hypertension, a group of 20 individuals with exclusively hypercholesterolemia and a group of 22 healthy persons. The individuals with hypertension or hypercholesterolemia were free of any other cardiovascular disease risk factor and were not on any therapy prior to entering the study. Clinical and laboratory data included systolic and diastolic blood pressure (obtained by ABPM), lipids profile, eGFR, red blood cell (RBC) deformability (assessed by shear stress laser diffractometry) …and levels of circulating soluble vascular adhesion molecules-1 (sVCAM-1) as well as soluble intracellular adhesion molecules-1 (sICAM-1). In the group of hypertensives, RBC deformability and concentration of circulating soluble adhesion molecules showed statistically significant negative correlations: RBC deformability decreases with increasing level of: a) sVCAM-1, R = −0.61, p < 0.002, b) sIVCAM-1, R = −0.53, p < 0.009. In parallel, statistically significant increase of eGFR was observed with rising erythrocyte deformability, R = 0.60, p < 0.005. In the groups of healthy individuals and patients with hypercholesterolemia there was no sign of any correlations between the considered parameters. The observed correlations suggest that in patients diagnosed exclusively with hypertension, firstly, erythrocyte deformability may serve as a marker of endothelial dysfunction and, secondly, red blood cells may be mediators of adverse changes in kidneys. Show more

Keywords: Erythrocyte deformability, glomerular filtration rate, soluble cell adhesion molecules, hypertension

DOI: 10.3233/CH-2011-1483

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 323-329, 2011

Authors: Papp, J. | Toth, A. | Sandor, B. | Kiss, R. | Rabai, M. | Kenyeres, P. | Juricskay, I. | Kesmarky, G. | Szabados, S. | Toth, K.

Article Type: Research Article

Abstract: Conditions during coronary artery bypass grafting (CABG) performed on beating heart (off-pump) are more physiological than using extracorporeal perfusion (on-pump). The present study aims to examine the hemorheological aspects of the two techniques. Blood samples were taken from patients undergoing on-pump (n = 25) and off-pump (n = 22) CABG, upon arrival to the operating theatre, after 20 and 40 minutes during the operation, after closing the thorax, on the 1st and 2nd postoperative days, and during the 2nd and 6th month control check-ups. Hematocrit (Hct), plasma and whole blood viscosity (PV, WBV; Hevimet 40 capillary viscometer), red blood cell …(RBC) aggregation (Myrenne RBC aggregometer, LORCA) and deformability (LORCA, Carat FT-1 filtrometer), and platelet aggregation (Carat TX4 aggregometer) were determined. The morphology of red blood cells was investigated by scanning electron microscopy (SEM). Hct, PV, WBV and RBC aggregation decreased significantly during the early phase of the surgery, they started to recover during the postoperative period, and reached the baseline values by the 2nd and 6th month control check-ups. These parameters were significantly lower in samples taken after 20 and 40 minutes in the on-pump group. SEM showed rather damaged and malformed cells in case of on-pump surgery. Ektacytometry showed no significant difference, but RBC deformability was impaired during on-pump surgery when measured by filtrometry. The decrease in platelet aggregation was more pronounced by the end of surgery in case of on-pump technique. During CABG rheological parameters change less when using the off-pump method, and mechanical damage of RBCs are also smaller. The off-pump technique seems to be favorable from a hemorhelogical point of view. Show more

Keywords: Coronary artery bypass grafting, on-pump, off-pump, viscosity, erythrocyte aggregation, erythrocyte deformability, platelet aggregation, scanning electron microscopy

DOI: 10.3233/CH-2011-1484

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 331-346, 2011

Authors: Wischke, Christian | Lendlein, Andreas

Article Type: Research Article

Abstract: Polymer-based biomaterials are extensively used in all disciplines of clinical medicine and innovations in biomaterial science are building a product pipeline, e.g., of future cardiovascular implants. Still, cardiovascular applications demand a number of extensive requirements of properties and functions to be fulfilled by the polymer matrix. This report provides an overview on some of these issues and how they can be addressed by a tailored design of novel polymer-based biomaterials. Multifunctional shape-memory polymers are highlighted as a class of materials that combine biocompatibility and the capability for stimuli-induced active movements for anchoring of implants with a controlled degradation and drug …release profile to enable a functional regeneration of the tissue at the application site. Show more

Keywords: Degradable biomaterial, cardiovascular implants, shape-memory polymers, stents, vascular prosthesis

DOI: 10.3233/CH-2011-1485

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 347-355, 2011

Authors: Song, Y. | Feijen, J. | Grijpma, D.W. | Poot, A.A.

Article Type: Research Article

Abstract: For the treatment of cardiovascular disease, functional arterial blood vessel prostheses with an inner diameter less than 6 mm are needed. This article gives an overview of the preparation of such vascular grafts by means of tissue engineering.

Keywords: Vascular graft, tissue engineering

DOI: 10.3233/CH-2011-1486

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 357-374, 2011

Authors: Braune, S. | Hönow, A. | Mrowietz, C. | Cui, J. | Kratz, K. | Hellwig, J. | Üzüm, C. | Klitzing, R.V. | Lendlein, A. | Jung, F.

Article Type: Research Article

Abstract: Small calibre vascular prostheses (<6 mm) still lack medium and long term patency. Inelasticity of the prosthesis is one of the characteristics, which is involved in the mechanisms of failure (e.g. the development of neointimal hyperplasia at the distal anastomosis). Here we report about covalently crosslinked poly(n-butyl acrylate) networks (cPnBA) with adjustable elastic moduli, which can be tailored to values of human arteries (between 100 and 1000 kPa). Motivated by the potential application of such polymer networks as cardiovascular prosthesis, adhesion, activation and thrombus formation of human platelets on cPnBA networks were evaluated. All cPnBA-samples displayed a high thrombogenicity compared …to the control (silicone). Significantly less platelets adhered on the surface of the soft cPnBA04 than on cPnBA73. All cPnBA samples displayed a higher number of platelet aggregates and a lower number of inactivated platelets in comparison to the control. While the elastic modulus of cPnBA networks could be successfully adjusted to that of human arteries, the tested polymers did not show an optimal hemocompatibility. Future studies aim at improving the biofunctionality by surface modification of these polymer networks. Show more

Keywords: Haemocompatibility, platelets, polymer networks, elastic modulus, biomaterial

DOI: 10.3233/CH-2011-1487

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 375-390, 2011

Authors: Dreyer, Lutz | Krolitzki, Benjamin | Autschbach, Rüdiger | Vogt, Peter | Welte, Tobias | Ngezahayo, Anaclet | Glasmacher, Birgit

Article Type: Research Article

Abstract: Endothelial cells (ECs) are permanently exposed to the blood flow and the resulting shear stress, its magnitude varying with the EC site in the blood stream. Along with other mechanical stimuli like vessel wall stretching or hydrostatic blood pressure, this shear stress modulates the endothelial cell function, morphology and gene expression. Here, we describe our improved cone-and-plate reactor that applies up to 10 dyn/cm2 uniform wall shear stress on a defined, ring-shaped region on a culture dish. At the same time, a hydrostatic pressure of up to 195 mmHg can be applied by increasing the atmospheric pressure in the …incubator box. Gas composition can be controlled additionally, used for maintaining CO2 -homeostasis or inducing hypoxic conditions. For better comparability, six cone-and-plate systems can be used at the same time at different rotational velocities. The effects on cell morphology, cytoskeleton and cell alignment can be monitored during application using a laser scanning microscope. Flow conditions have been studied and a sufficient area of uniform wall shear stress could be shown. To exceed 10 dyn/cm2 , we suggest an increase in medium viscosity. Show more

Keywords: shear force, cone-and-plate rheometer, mechanotransduction, endothelial cells

DOI: 10.3233/CH-2011-1488

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 391-397, 2011

Authors: Wenzel, Folker | Gettmann, Thorben | Zimmermann, Norbert | Giers, Günther

Article Type: Research Article

Abstract: Introduction: The hormones erythropoietin (EPO) and thrombopoietin (TPO) are main regulators of erythro- and thrombopoiesis. Cell loss caused by operative procedures may alter serum levels of the hormones, resulting in well known phenomenons like reactice thrombocytosis. Material and methods: Blood samples from 10 patients (mean age 63 ± 9 years) were obtained before and at day 1, 5 and 10 after coronary artery bypass grafting (CABG). EPO and TPO levels were determined by commercially available ELISA-Kits (R&D Systems, Germany). In addition, platelet count (PC) and hemoglobin concentration (Hb) were determined. Results: Prior to CABG, EPO (13.2 ± 8.2 mU/mL), TPO …(189 ± 52 pg/mL), Hb (8.8 ± 1.1 mmol/L) and PC (254 ± 121/nL) were within a normal range. At day 1 after surgery, Hb and PC were significantly decreased to 6.6 ± 0.9 mmol/L and 138 ± 70/nL. In contrast, EPO and TPO were significantly elevated to 32 ± 18 mU/mL and 336 ± 96 pg/mL, respectively, in spite of hemodilution. In particular, TPO elevation was followed by a significant increase in PC (342 ± 144/nL) at day 10 after surgery compared to preoperative values. Conclusions: Appropriate to the decrease in hemoglobin concentration and platelet count, clear alterations of serum erythropoietin and thrombopoietin levels could postoperatively be observed. EPO levels showed an inverse correlation to hemoglobin concentrations, whereas a disturbed thrombopoietin feedback mechanism resulted in the phenomenon of reactive thrombocytosis. Show more

DOI: 10.3233/CH-2011-1489

Citation: Clinical Hemorheology and Microcirculation, vol. 49, no. 1-4, pp. 399-406, 2011