Clinical Hemorheology and Microcirculation - Volume 45, issue 2-4

Authors: Seda Artis, A. | Aydogan, Sami | Gokhan Sahin, M.

Article Type: Research Article

Abstract: Currently, with reappraisal of ozone therapy, it has been utilized worldwide in research and clinical field. Most of the studies investigating effects of ozone on blood parameters are conducted by directly ozonating the blood. Rectal insufflation is a simple, easy and inexpensive method of delivering ozone. Little is known how these gases affect some fundamental hemorheologic parameters when given by insufflation. We aimed to investigate the effects of colorectally insufflated oxygen-ozone on red blood cell rheology in rabbits. Rabbits were divided into Group 1 (control); Groups 2, 3 and 4 (oxygen rectally insufflated respectively for 15, 21 and 36 days); …Groups 5, 6 and 7 (ozone rectally insufflated respectively for 15, 21 and 36 days). Erythrocyte deformability, aggregation and osmotic fragility were determined from blood samples at the end of each treatment period. Our study showed an improvement in deformability, a decrease in aggregation and an increase in fragility following a 15 day ozone treatment. With longer ozone application the changes in aggregation and fragility returned back to control levels, however its effect on deformability sustained. Therefore, more than two weeks ozone insufflation may induce adaptation to changes induced by ozone suggesting its systemic effects. Show more

Keywords: Ozone, erythrocyte deformability, aggregation, osmotic fragility

DOI: 10.3233/CH-2010-1316

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 329-336, 2010

Authors: Muravyov, Alexei V. | Tikhomirova, Irina A. | Maimistova, Alla A. | Bulaeva, Svetlana V. | Zamishlayev, Andrey V. | Batalova, Ekaterina A.

Article Type: Research Article

Abstract: There are evidences that red blood cell (RBC) deformation and aggregation change under their incubation with catecholamines and it is connected with activation of intracellular signaling pathways. The present study was designed to explore the adenylyl cyclase signaling pathway and Ca2+ regulatory mechanism of RBCs together with their microrheological changes. The washed RBCs were resuspended in PBS. In each of the three research sessions RBC suspensions were divided into two aliquots: 1) control (without drug) and 2) with an appropriate drug. After cell incubation RBC deformability (RBCD) and aggregation (RBCA) were estimated. RBC incubation with catecholamines resulted in RBCD …changes by 18–30%. RBCs incubation with forskolin facilitated an increase of RBCD by 17% (p < 0.05). A significant deformability rise under dB-AMP incubation was found by 27% (p < 0.01). Ca2+ cell influx, stimulated by A23187, was accompanied by an increase of RBCA; whereas red cell deformability was changed only slightly. On the other hand, Ca2+ entry blocking into the cells by verapamil has led to significant RBCA decrease and RBCD rise. The obtained results make us believe that RBCD change was closely associated with Ca2+ control mechanisms. An effect of Ca2+ concentration increase on RBC microrheology was removed, if it was preliminary added to incubation medium EGTA as Ca2+ chelator. It was found that all four PDE inhibitors: IBMX, vinpocetine, rolipram, pentoxifylline decreased RBCA significantly and, quite the contrary, they increased red cell deformability. Our data have shown that Ca2+ entry increase was accompanied by red cell aggregation rise, while adenylyl cyclase-cAMP system stimulation led to red cell deformability increase and its aggregation lowered. The crosstalk between two intracellular signaling systems is probably connected with phosphodiesterase activity. Show more

Keywords: Adenylyl cyclase, cAMP, phosphodiesterase, red blood cell deformability and aggregation, intracellular signaling pathways, Ca2+-control mechanism

DOI: 10.3233/CH-2010-1317

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 337-345, 2010

Authors: Hiebl, B. | Jung, F. | Schossig, M. | Scharnagl, N. | Richau, K. | Niehues, S.

Article Type: Research Article

Abstract: This study shows first in vitro tests of a nitinol based vein cuff developed for external valvuloplasty. In contrary to currently existing vein cuffs the tested model enables minimal invasive implantation and also maintains its round pre-shaped profile at body temperature (37°C). The examination of the cuff surface structure by scanning electron microscopy, profilometry and X-ray photoelectron spectroscopy after sterilization with ethylene oxide and before cyto-compatibility testing revealed a nearly smooth surface (mean square roughness Rq 66 ± 33 nm) which was primarily composed of nickel, oxygen, titanium, carbon and silicon where nickel was the least fraction (Ni: 0.7%, Ti: …1.7%, Si: 15.8%, O: 29.5%, C: 52.3%) of the surface elements. Si and C are supposed to be contaminations caused by a final cuff polishing with silicon carbide at the end of the manufacturing process. To evaluate cyto-compatibility initial cell adherence and cell activity were assessed. The results showed good initial cell adherence of L929 fibroblast-like cells on the cuff surface already after 24 h. The results also revealed no inhibitory effects on the activity of these cells (MTS test) later on. The test setup developed to analyse functionality in a dynamic mode was shown to be suited at blood pressures up to 300 mmHg. The cuff successfully limited dilation of varicose veins (Vena saphena magna) at physiological blood pressures (< 120 mmHg) and also in cases of hypertonia (300 mmHg) to the diameter determined by the cuff (4.0 mm) over thecomplete testing period. This indicates that the clasp based cuff closure mechanism is suited to close the cuff under variable physiological and pathological blood pressure conditions. The cuff structure only allowed minimal adaptation on the inhomogenously dilating vein profile in the both peripheral cuff modules. Both peripheral modules followed the vessel dilation in correlation to the applied pressure. At pressures within the physiological range ≤ 120 mmHg) the variation of the lateral arch module diameter was only marginal, whereas at 300 mmHg pressure the peripheral modules followed vein dilation up to a diameter of 5.0 to 5.5 mm. The cuff also maintained the pre-shaped round profile in the central and peripheral modules during the pressure increase and the consecutive cuff expansion. The study showed that the first nitinol based vein cuff for external valvuloplasty was processed well enough by electropolishing and sterilization to allow culturing of L929 fibroblast-like cells on the cuff surface as a test of general biocompatibility. The cuff also proved to limit dilation of varicose veins at physiological and pathological blood pressures in vitro. Further tests with primary cells from the venous wall will follow to test the specific biocompatibility before tests in vivo can be envisaged. Show more

Keywords: Nitinol, vein cuff, nickel exposure, general biocompatibility, external valvuloplasty

DOI: 10.3233/CH-2010-1313

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 347-358, 2010

Authors: Lardi, E. | Ott, C. | Schulzki, T. | Kuhn, M. | Bonetti, P.O. | Reinhart, W.H.

Article Type: Research Article

Abstract: Passive smoking may increase cardiovascular events by yet insufficiently understood mechanisms. We, therefore, tested the hypothesis that passive smoking could affect platelet aggregation. Fourteen healthy non-smoking males were exposed to second-hand smoke during 60 min in a room with smokers, who maintained the CO-concentration between 4.5–7.0 ppm throughout that period. Citrated blood was drawn before and immediately after smoke exposure (which took place between 6 and 7 p.m.). The last 7 individuals had blood taken also at 9.00 a.m. before and the day after smoke exposure. Platelet aggregation was measured (a) in flowing whole blood using the platelet function analyser …PFA-100® , which determines the closure time (CT) of a collagen coated membrane pore by shear-induced platelet aggregation, and (b) with a Chrono-log 700 Aggregometer, assessing platelet aggregation either by the change of impedance in diluted whole blood or light transmission in platelet-rich plasma. After short term second-hand smoke exposure we did not observe an increase in platelet aggregation with any of the instruments. We conclude that acute exposure to second-hand smoke is unlikely to increase platelet aggregability. Other mechanisms must be involved in the increased risk of cardiovascular events associated with passive smoking. Show more

Keywords: Nicotine, platelet aggregation, smoking

DOI: 10.3233/CH-2010-1318

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 359-364, 2010

Authors: Lenasi, Helena | Štrucl, Martin

Article Type: Research Article

Abstract: Regular physical activity leads to increased endothelium-dependent vasodilatation. Postocclusive reactive hyperemia (PRH) is a transient increase of blood flow after the release of an arterial occlusion and has been used as a clinical tool to estimate endothelial function. The aim of our study was to assess the potential effect of regular physical training on PRH of skin microcirculation. Skin blood flux was estimated by laser-Doppler fluxmetry (LDF) in two groups of subjects: 12 highly trained athletes and 12 age-matched sedentary controls. LDF was measured on two specific skin sites: volar aspect of the forearm (nonglabrous area) and finger pulp of …the middle finger (glabrous area). After the release of a 3-min occlusion of the brachial artery, we determined the following indices of PRH: the time to peak (tpeak ), the maximal LDF (LDFpeak ), the recovery time (trec ), the area under the PRH curve (AUC). Baseline LDF did not differ between the trained and sedentary subjects in either site. On the forearm, we found no significant differences in either PRH parameter. On the contrary, on the finger pulp, there were statistically significant differences in the tpeak and the AUC (p ≤ 0.05). The results show an altered PRH response of skin microcirculation in the finger pulp in the trained subjects. We may speculate that this could be the result of an increased endothelial vasodilator capacity. Further, the potential adaptations of the endothelium differ between the glabrous and nonglabrous skin sites. Show more

Keywords: Skin microcirculation, laser–Doppler fluxmetry, postocclusive reactive hyperemia, endurance, endothelium

DOI: 10.3233/CH-2010-1320

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 365-374, 2010

Authors: Ott, C. | Lardi, E. | Schulzki, T. | Reinhart, W.H.

Article Type: Research Article

Abstract: Red blood cells (RBCs) affect platelet aggregation in flowing blood (primary hemostasis). We tested the hypothesis that RBC aggregation could influence platelet aggregation. RBC aggregation was altered in vitro by: (i) changing plasma aggregatory properties with 3.7 g% dextran 40 (D40), 3.0 g% dextran 70 (D70) or 1.55 g% dextran 500 (D500); (ii) changing RBC aggregatory properties by incubating RBCs in 50 mU/ml neuraminidase for 60min (reduction of the surface sialic acid content, thus reducing electrostatic repulsion) and subsequent RBC resuspension in platelet rich plasma (PRP) containing 1 g% dextran 70. RBC aggregation was assessed with the sedimentation rate (ESR). …Platelet aggregation was measured: (i) in flowing whole blood with a platelet function analyzer PFA-100® , which simulates in vivo conditions with RBCs flowing in the center and platelets along the wall, where they adhere to collagen and aggregate; and (ii) in a Chrono-log 700 Aggregometer, which measures changes of impedance by platelet aggregation in whole blood or changes in light transmission in PRP. We found that RBC aggregation increased with increasing molecular weight of dextran (ESR: 4 ± 3 mm/h, 34 ± 14 mm/h and 89 ± 23 mm/hfor D40, D70 and D500, respectively, p < 0.0001) and with neuraminidase-treated RBCs (76 ± 27 mm/h vs 27 ± 8 mm/h, respectively, p < 0.0001). Platelet aggregation measured in whole blood under flow conditions (PFA-100® ) and without flow (Chronolog Aggregometer) was not affected by RBC aggregation. Our data suggest that RBC aggregation does not affect platelet aggregation in vitro and plays no role in primary hemostasis. Show more

Keywords: Aggregation, dextran, erythrocyte, erythrocyte sedimentation rate, neuraminidase, platelet aggregation

DOI: 10.3233/CH-2010-1319

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 375-382, 2010

Authors: Schulzki, T. | Reinhart, W.H.

Article Type: Research Article

Abstract: Erythrocytes loose some functional qualities during storage, which may influence the outcome after transfusion. One of them is mechanical stability, which determines their in vivo survival in the circulation. We have analyzed different forms of mechanical stress and have developed a simple, reproducible test for mechanical stability. Specimens of outdated erythrocyte units stored under routine conditions were investigated. Mechanical stress was applied either by rolling blood-containing 5 ml tubes at 15 rpm (Mixer 820, Swelab, Sweden) or overhead rotation at 10 rpm (Intelli-Mixer RM-2S Elmi, Skyline, Axon Lab AG, Baden, Switzerland). Free hemoglobin (Hb) in the supernatant was used as …a parameter of membrane integrity. Stored erythrocyte units at the end of their “shelf-life” of 42 days had a median free Hb concentration of 1.8 g/l (25–75 percentiles: 1.8–2.6 g/l) corresponding to a spontaneous hemolysis rate of 0.31% (0.28–0.46%). In samples subjected to 24 h rolling, free Hb rose to 4.8 (4.0–7.0; p = 0.005). Overhead rotation for 24 h increased free Hb to 17.1 (12.2–27.9) g/l when 1.5 ml blood in 5 ml tubes were used, and to 38.0 (19.6–55.2) g/l when 4.5 ml in 5 ml tubes were used (p = 0.005 between the two groups), indicating that hemolysis during rotation depended on the blood volume. The type of tube also influenced the extent of hemolysis. A large variation was seen between different RBC units. The time course of hemolysis was an inverse exponential function; i.e. 2 h of rotation induced already 45% and 7 h 86% of the hemolysis measured after a 24 h rotation. We conclude that the rate of hemolysis after a standardized overhead rotation is a simple, useful laboratory test to determine the mechanical stability of stored erythrocytes. Large variations between different RBC units suggest that this may be valuable tool for the quality control of stored RBCs. Show more

Keywords: Erythrocyte, hemolysis, transfusion

DOI: 10.3233/CH-2010-1323

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 383-389, 2010

Authors: Ahmadizad, Sajad | El-Sayed, Mahmoud S. | MacLaren, Donald P.

Article Type: Research Article

Abstract: The present study was designed to ascertain the interaction between time of day and resistance exercise on platelet activation and function. Ten healthy male subjects (age, 29.3 ± 4.5 yr) undertook identical bouts of resistance exercise on two separate occasions. Tests were randomised and performed at two different time of day (08:00 and 20:00 h). Subjects performed 3 sets of 7 repetitions of six exercises at 80% of 1RM, which was followed by 30 min recovery. Beta-thromboglobulin (B-TG) and platelet indices were measured at rest, post-exercise and at the completion of recovery. Platelet aggregation was determined in platelet rich plasma …using collagen and three different concentrations of adenosine-5′-diphosphate. Platelet aggregations induced by different aggregating agents at rest were significantly higher in the morning (p < 0.05). Although platelet aggregations induced by collagen and ADP did not change in response to resistance exercise, significant differences between the results in the morning and evening trials were observed (p < 0.01). These differences emulated the differences observed at rest. A significant (P < 0.05) increase in B-TG was found following exercise with no difference between morning and evening trials. It was concluded that resistance exercise induces significant changes in platelet activation, irrespective of time of day, as assessed by beta-thromboglobulin. Show more

Keywords: Acute resistance exercise, time of day, platelet aggregation, B-TG, platelet indices

DOI: 10.3233/CH-2010-1321

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 391-399, 2010

Authors: Cui, J. | Trescher, K. | Kratz, K. | Jung, F. | Hiebl, B. | Lendlein, A.

Article Type: Research Article

Abstract: Acrylonitrile-based polymer systems (PAN) are comprehensively explored as versatile biomaterials having various potential biomedical applications, such as membranes for extra corporal devices or matrixes for guided skin reconstruction. The surface properties (e.g. hydrophilicity or charges) of such materials can be tailored over a wide range by variation of molecular parameters such as different co-monomers or their sequence structure. Some of these materials show interesting biofunctionalities such as capability for selective cell cultivation. So far, the majority of AN-based copolymers, which were investigated in physiological environments, were processed from the solution (e.g. membranes), as these materials are thermo-sensitive and might degrade …when heated. In this work we aimed at the synthesis of hydrophobic, melt-processable AN-based copolymers with adjustable elastic properties for preparation of model scaffolds with controlled pore geometry and size. For this purpose a series of copolymers from acrylonitrile and n-butyl acrylate (nBA) was synthesized via free radical copolymerisation technique. The content of nBA in the copolymer varied from 45 wt% to 70 wt%, which was confirmed by 1 H-NMR spectroscopy. The glass transition temperatures (Tg ) of the P(AN-co-nBA) copolymers determined by differential scanning calorimetry (DSC) decreased from 58°C to 20°C with increasing nBA-content, which was in excellent agreement with the prediction of the Gordon-Taylor equation based on the Tg s of the homopolymers. The Young’s modulus obtained in tensile tests was found to decrease significantly with rising nBA-content from 1062 MPa to 1.2 MPa. All copolymers could be successfully processed from the melt with processing temperatures ranging from 50°C to 170°C, whereby thermally induced decomposition was only observed at temperatures higher than 320°C in thermal gravimetric analysis (TGA). Finally, the melt processed P(AN-co-nBA) biomaterials were sterilized with ethylene oxide and tested for cytotoxicity in direct contact tests with L929 cells according to the EN DIN ISO standard 10993-5. All tested samples exhibited non-toxic effects on the functional integrity of the cell membrane and the mitochondrial activity. However, the morphology of the cells on the samples was different from that observed on polystyrene as control, indicating slightly cytotoxic effects according to the evaluation guide of the US Pharmacopeial Convention. Thus, the melt-processable, hydrophobic P(AN-co-nBA) copolymers with adjustable mechanical properties are promising candidates for in vitro investigations of tissue growth kinetics. Show more

Keywords: Biocompatibility, melt processability, acrylonitrile, butyl acrylate, copolymer

DOI: 10.3233/CH-2010-1322

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 401-411, 2010