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

Authors: Zvetkova, Elissaveta | Antonova, Nadia | Ivanov, Ivan | Savov, Yonko | Gluhcheva, Yordanka

Article Type: Research Article

Abstract: Hemorheological abnormalities such as elevated whole blood viscosity, plasma viscosity, erythrocyte deformability and platelet aggregation, hematocrit and fibrinogen levels, are frequently examined as diagnostic tool and prognostic relevance in socially important hemorheological disorders. Distinct biological – morphological and functional platelet alterations, have been described in different addictions (heroin-, cocaine-, nicotine-, alcohol-, etc.). Chronic addictions could cause biochemical and conformational changes in platelets and their membranes, thus modulating platelet receptor expression, morphology (anisocytosis, giant platelets) and activation (alpha-granule release), platelet aggregation and hemorheological properties. Some of these alterations in chronic addicts – documented at cellular- and molecular level, could be easily …used as a precise diagnostic tool with regard to thromboembolic complications and microcirulation injuries attributable to addictions. The present review focuses on some changes in platelet morphological, functional and rheological properties induced by chronic opiate/opioid abuse. Hypothesis is accumulated that free fatty acids (FFAs) and especially oleic acid (OA) could cause positive molecular and conformational changes in platelets of addicts with hemorheological disorders. Show more

Keywords: Addictions, platelets, hemorheology, platelet membrane fatty acids (PMFAs), oleic acid (OA)

DOI: 10.3233/CH-2010-1305

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 245-251, 2010

Authors: Antonova, N. | Riha, P. | Ivanov, I.

Article Type: Research Article

Abstract: Mechanical and electrical properties of red blood cells (RBC) suspensions in dextran 70 (Dx70), dextran 150 (Dx150), dextran 500 (Dx500) and polyethileneglycol (PEG) 35 000 with different concentrations were evaluated through apparent viscosity and conductivity measurements under steady and unsteady flow conditions. RBCs suspensions of the washed RBS in PBS (control) and Dx70, Dx150, Dx500 and PEG in PBS with different concentrations, adjusted to the same hematocrit of 40% were used for the experiments. Conductivity time and shear rate dependences in parallel with the rheological properties of the samples were studied under transient flow regimes at different local structure of …the uniform Couette flow. Their relationships on dextrans and PEG concentrations were evaluated too. Low shear viscosity increased and conductivity decreased of RBC suspensions, compared to non-aggregating suspensions, depending on dextrans and PEG concentrations. A time course of blood conductivity recorded under different flow conditions provides experimental description of RBC aggregation-disaggregation processes and other cell-cell interactions. The results show that the blood conductivity is strongly dependent on the considered blood factors and is influenced by flow, shear rates and concentration of dextran and PEG solutions. Show more

Keywords: Apparent viscosity, conductivity, unsteady flow, RBC suspensions, dextrans, PEG

DOI: 10.3233/CH-2010-1310

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 253-261, 2010

Authors: Nemeth, Norbert | Kiss, Ferenc | Furka, Istvan | Miko, Iren

Article Type: Research Article

Abstract: Although growing number of evidences supports the gender differences of hemorheological variables in human, little is known about this question in experimental animals. Investigating this question and giving laboratory-specific reference values, blood samples from healthy male and female CD rats and beagle dogs were tested for hematological parameters (microcell counter), blood and plasma viscosity (capillary viscometer), erythrocyte deformability (bulk filtrometry and ektacytometry), erythrocyte aggregation (light transmission aggregometer) and fibrinogen concentration (coagulometer). Besides the inter-species alterations we found hematological gender differences too regarding the red blood cell count and hematocrit. In rats the erythrocyte aggregation index was higher in females, …while in beagle dogs the males showed significantly higher aggregation index values. In rats the red blood cell deformability showed better values in females. In beagle dogs this was the opposite, the males had better elongation index (EI) values in the function of shear stress (SS). Besides this it was also experienced that the shape of the canine EI – SS curves differed from the rats’ values. Gender differences with inter-species alterations can be observed in laboratory animals (rats and dogs) that have to be taken under consideration during planning experiments and evaluating results. Show more

Keywords: Blood viscosity, plasma viscosity, red blood cell aggregation, red blood cell deformability, gender differences, laboratory animals

DOI: 10.3233/CH-2010-1303

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 263-272, 2010

Authors: Kiss, Ferenc | Nemeth, Norbert | Sajtos, Erika | Brath, Endre | Peto, Katalin | Baskurt, Oguz K. | Furka, Istvan | Miko, Iren

Article Type: Research Article

Abstract: Using “Furka’s spleen-chip” autotransplantation technique, in a follow-up study we investigated erythrocyte aggregation and its influencing factors regarding to asplenic-hyposplenic conditions. Healthy beagle dogs were equally divided into 4 groups: “Sham”- sham operated control, “SE”-splenectomy, “AU-5” and “AU-10”-autotransplantation with 5 or 10 spleen chips by Furka-method after splenectomy. Blood sampling for current investigation occurred on the 12th, 18th, 20th and 24th postoperative months, besides comprehensive structural and functional examinations. In this study we focused on the aggregation properties of erythrocytes in native samples and of density separated “young” versus “old” erythrocytes (Myrenne MA-1 aggregometer). Fibrinogen concentration (Sysmex CA-500 coagulometer) and …erythrocyte sedimentation rate (ESR) were also determined. SE group showed significantly elevated ratio of “old” and “young” erythrocyte aggregation index values on the 20th and 24th postoperative months (1.5 and 2.16, respectively) comparing to the AU (1.14 and 1.05) and Sham groups (1.2 and 1.27). In SE group fibrinogen concentration was mildly higher and ESR almost doubled versus control. The greater differences experienced between “young” and “old” erythrocytes may reflect decreased splenic filtration function. Consequently, the comparison of aggregation and deformability properties of “young” and “old” erythrocytes may give important information about the function of the spleen. Show more

Keywords: Splenic function, splenectomy, spleen autotransplantation, red blood cell aggregation, erythrocyte sedimentation rate

DOI: 10.3233/CH-2010-1304

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 273-280, 2010

Authors: Miko, Iren | Nemeth, Norbert | Sajtos, Erika | Brath, Endre | Peto, Katalin | Furka, Andrea | Szabo, Gyorgyi | Kiss, Ferenc | Imre, Sandor | Furka, Istvan

Article Type: Research Article

Abstract: Erythrocyte deformability could be a suitable parameter reflecting hyposplenic-asplenic conditions after splenectomy or spleen autotransplantation. The aim of this study was to analyze the efficacy of spleen autotransplantation using filtrometry and ektacytometry for testing erythrocyte deformability, besides complex structural, functional, hematological, hemostaseological and immunological examinations. Healthy beagle dogs were subjected to the study in the following experimental groups: “Sham”-sham operated control, “SE”-splenectomy, “AU-5” and “AU-10”-autotransplantation with 5 or 10 spleen chips using “Furka’s spleen chip” technique after splenectomy. Blood samples were taken before the operations and monthly afterwards for 1 year and bi-monthly till the end of the 2nd postoperative …year. Erythrocyte deformability was measured by bulk filtrometry (relative cell transit time, RCTT) and on the 20th–24th postoperative months by ektacytometry (elongation index, EI), too. RCTT was elevated in operated groups till the 12th month. On the 20th/24th months “SE”-group expressed the highest level, while the “AU”-groups were close to “Sham”-group. Using ektacytometer we found that on the 20th/24th month both EImax and SS1/2 showed the lowest values (because of unusual curve characteristic) in “SE”-group and “AU”-groups almost reached the “SH”-group. Spleen autotransplantation partially restored the normal rheological conditions. Both filtrometry and ektacytometry was suitable to investigate hyposplenic-asplenic conditions. Show more

Keywords: Splenectomy, spleen autotransplantation, Furka’s spleen chip technique, red blood cell deformability, sepsis

DOI: 10.3233/CH-2010-1307

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 281-288, 2010

Authors: Sajtos, Erika | Nemeth, Norbert | Kiss, Ferenc | Brath, Endre | Peto, Katalin | Hever, Timea | Matyas, Lili | Furka, Istvan | Miko, Iren

Article Type: Research Article

Abstract: Clinical studied showed leukocyte antisedimentation rate (LAR) changes in various conditions that modulate the immune system. There is a lack of LAR data in animal experiments concerning splenic function after splenectomy or spleen preserving operations, thus we aimed to include LAR in our ongoing inbred canine study on following-up spleen salvaging surgical techniques. Blood samples of healthy beagle dogs served as normal control. The experimental groups were: “SH”-sham operated, “SE”-splenectomy, “R1/3” and “R2/3”-one-third/two-third of the spleen resected, “AU-5” and “AU-10”-autotransplantation with 5/10 spleen chips using Furka’s techniques. On the 12th postoperative month Rabigen-Mono+Vanguard-Plus-5 vaccines were given to the animals, which …provoked immune response. Blood samples were taken before and one week after the vaccination. LAR was calculated by Bogar’s method. In normal control group LAR was 3.11, leukocyte count was 12.04 G/l. In the experimental groups LAR varied between 2.4–7.3 before vaccination. After vaccination LAR increased in all groups. Although “SE” group expressed the largest changes (LAR = 16.56; 135%), the leukocyte count increased only by 12%. In “AU” groups the increase was smaller, while “R” groups showed slight changes only. LAR can be applicable in animal experiments and may serve as a supplementary parameter in hemorheological investigations of hyposplenic-asplenic states. Show more

Keywords: Splenectomy, spleen autotransplantation, spleen resection, vaccination, leukocyte antisedimentation rate

DOI: 10.3233/CH-2010-1308

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 289-294, 2010

Authors: Helling, H. | Schenk, H.J. | Pindur, G. | Weinrich, M. | Wagner, B. | Stephan, B.

Article Type: Research Article

Abstract: Septic and haemorhagic shock carry the risk of high mortality. Failure of microcirculation secondary to alterations of haemostasis and fibrinolysis play a major role in the pathogenesis of shock. The aim of this study was to evaluate the clinical relevance of procoagulatory and fibrinolytic activities referring to survival. Therefore, 39 patients (23 to 80 yrs, 16 females, 23 males) suffering from haemorrhagic (n = 21) and septic shock (n = 18) were screened prospectively for plasmatic coagulation and fibrinolysis parameters. Thirteen patients (33.3%) developed lethal outcome. Concerning fibrinolysis, plasminogen was significantly lower in non-survivors by day 1 and plasmin–antiplasmin complex …significantly higher by day 4 compared to survivors. Consecutive increase of plasminogen over day 4 and 7 was significantly stronger in survivors. Concerning haemostasis activation, thrombin–antithrombin complex was higher and D-dimers or fibrinogen levels were lower, but not significantly different, in non-survivors compared to survivors. We conclude from these data, that procoagulant activities are increased, but not significantly predictive for the clinical outcome in septic and haemorrhagic shock. By contrast, fibrinolysis, as measured by enhanced capacity and responsiveness, is clearly predictive and plays a significant role for survival, possibly due to its clearing function in microcirculation. Show more

Keywords: Septicemia, haemorrhage, shock, coagulation, fibrinolysis

DOI: 10.3233/CH-2010-1309

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 295-300, 2010

Authors: Ruef, P. | Craciun, E. | Altfelder, F. | Simon, C. | Frommhold, D. | Koch, L. | Pöschl, J.

Article Type: Research Article

Abstract: Sequestration of activated PMN and enrichment in tissues play a key role in tissue damage during septicaemia and after ischemia/reperfusion. Since polymorphonuclear neutrophilic granulocytes (PMN) of term neonates show various functional differences compared to PMN in adults (decreased chemotaxis, decreased intracellular killing, decreased adhesion) we studied the influence of interleukin 8 (IL-8), tumor necrosis factor-α (TNF-α) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) on the reduction of deformability of PMN in neonates and adults. The following phosphodiesterase (PDE)-inhibitors were applied to ameliorate the reduction in deformability when the PMN were stimulated with fMLP or IL-8: Enoximone, Milrinone (PDE-III-inhibitors), Pentoxifylline (PTX) and Piclamilast (PDE-IV-inhibitors). The …micropipette technique and the cell transit analyzer (CTA) were used and compared. Aspiration times into micropipettes with an internal diameter of 5 μm, transit times through 8 μm filter pores and neutrophil elastase concentrations were determined. Despite of the functional differences of PMN in neonates compared to adults the significant decrease of deformability of PMN activated with cytokines compared to passive PMN was not different in both groups. The neutrophil elastase concentrations reflect the activation of the PMN: highest concentrations during activation, decreased concentrations due to PDE-inhibitors, and PMN in a passive state. The neutrophil elastase concentrations were not different from PMN of neonates and adults. These PDE-inhibitors significantly increased the deformability of activated PMN but significant differences between the deformability of PMN in neonates and adults were not found. Despite the functional differences of PMN in neonates PDE-III/IV-inhibitors lead to similar improvement of mechanical properties of activated PMN in neonates and adults. These drugs may ameliorate impaired microcirculation also in neonates during inflammation. Show more

Keywords: Neonates, PMN, CTA, enoximone, milrinone, PTX, piclamilast

DOI: 10.3233/CH-2010-1311

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 301-310, 2010

Authors: Leithäuser, Boris | Jung, Friedrich | Park, Jai-Wun

Article Type: Research Article

Abstract: Atrial fibrillation (AF), as the most common cardiac rhythm disturbance, gains in importance not only for the persons affected, but also for health care and social economy due to thromboembolic events, of which stroke is the most serious, disabling, and life threatening one. Cardiac embolism is due to thrombus formation mainly in the left atrial appendage (LAA). The pathophysiology leading to increased thrombogenicity is complex and requires a remodelling of the LAA structure, decreased LAA blood flow, activation of inflammatory processes, deviations of the hemostatic/fibrinolytic system, and activation/dysfunction of endothelial/endocardial cells. Altogether, a prothrombotic state proposed by Virchow more than …150 years ago. The presence of a LAA thrombus, therefore, is a result of a dynamic process of clot formation and lysis. A comprehensive understanding of this pathophysiology is helpful to optimize the management of patients at high risk of cardioembolic stroke. Especially those with contraindications for oral anticoagulation are in a need of an alternative approach that is not associated with a long-term risk of hemorrhage and other attendant circumstances. The reasonable alternative may be the exclusion of the LAA cavity from circulation by either surgical or percutaneous catheter-based procedures. Show more

Keywords: Atrial fibrillation, thromboembolism, stroke, anticoagulants, risk, prognosis, aged

DOI: 10.3233/CH-2010-1314

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 311-323, 2010

Authors: Perampaladas, Kumar | Parker, John D. | Gori, Tommaso

Article Type: Research Article

Abstract: Clinical studies have demonstrated that rosiglitazone can improve vascular function in patients with diabetes mellitus. It remains unclear whether this effect depends on a direct improvement in endothelial function or whether it is mediated by the drug’s effect on glycemic control. Yet, rosiglitazone has been linked to serious cardiovascular events. A number of studies recently investigated whether rosiglitazone affects endothelial function in healthy volunteers and patients with cardiovascular disease. Controversial observations have been reported; the observation that rosiglitazone might in certain cases impair endothelial function may suggest a mechanistic explanation for the observation of increased cardiovascular events in patients treated …with rosiglitazone who have underlying cardiovascular disease. These studies are summarized and discussed in the present paper. Show more

Keywords: Diabetes, endothelial function, myocardial infarction, organic nitrates

DOI: 10.3233/CH-2010-1315

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 325-328, 2010

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