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

Authors: Reinhart, Walter H.

Article Type: Other

DOI: 10.3233/CH-2010-1285

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 73-74, 2010

Authors: Rampling, Mike

Article Type: Other

DOI: 10.3233/CH-2010-1286

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 75-77, 2010

Authors: Jung, F.

Article Type: Research Article

DOI: 10.3233/CH-2010-1312

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 79-99, 2010

Authors: Baskurt, O.K. | Meiselman, H.J.

Article Type: Research Article

Abstract: The flow properties of blood and its components vary widely throughout the animal kingdom. Even if nucleated avian and reptile red blood cells (RBC) are excluded from the analysis, RBC exhibit different rheological behavior among mammalian species. Both RBC aggregation and cellular deformability have been reported to vary among species, including placental mammals, marsupials, terrestrial and aquatic mammals. Although the relationships between blood flow behavior and species-specific characteristics have not been systematically investigated, studies to date allow recognition of interesting patterns, especially for RBC properties. These properties do not correlate with simple cellular parameters (e.g. mean cell volume), but more …detailed analysis of RBC structure may reveal cellular aspects (e.g. surface charge density) that can be related to rheologic behavior. It has been postulated that the athletic capacity of mammalian species may predict the aggregation behavior of their RBC, but this hypothesis has not been supported by data from a wide range of athletic and sedentary species. Aquatic mammals also exhibit a very interesting diversity of hemorheological properties, which again are not yet easily related to specific circulatory adaptations. Data from current comparative studies suggest that a better understanding of the relations between specific hemorheological properties and specific hemodynamic adaptations in a variety of species should contribute to a better understanding of circulatory behavior; future studies are thus clearly indicated. Show more

Keywords: Mammalian species, comparative physiology, blood viscosity, erythrocyte deformability, erythrocyte aggregation

DOI: 10.3233/CH-2010-1287

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 101-108, 2010

Authors: Muxel, Selina | Fasola, Federica | Radmacher, Marie-Christine | Jabs, Alexander | Münzel, Thomas | Gori, Tommaso

Article Type: Research Article

Abstract: The vascular endothelium plays a pivotal role in modulating endothelial homeostasis. A number of methods have been developed to assess the function of this important tissue in humans in vivo, in the hope that such data may contribute to the early diagnosis and risk stratification of patients at risk for, or with, cardiovascular disease. Despite these efforts, a number of issues, both practical and theoretical, arise from the attempt of quantifying the elusive “endothelial function”, and from the attempt of defining what is “endothelial dysfunction”. The present paper, based on a lecture held at the conference of the European Society …of Hemorheology and Microcirculation, will try to deal with these issues. Show more

Keywords: Endothelium, coronary artery disease, flow-mediated dilation, low-flow-mediated constriction

DOI: 10.3233/CH-2010-1288

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 109-115, 2010

Authors: Hiebl, B. | Fuhrmann, R. | Jung, F. | Kratz, K. | Lendlein, A. | Franke, R.P.

Article Type: Research Article

Abstract: The degradation behavior and the effect on angiogenesis of multiblock copolymers based on poly(p-dioxanone)- and poly(ε-caprolactone)-segments (PDC) were studied in vivo. PDC is a multifunctional biomaterial combining degradability and shape-memory capabilities. The “in vivo” degradation of PDC is characterized by a fragmentation occurring at the material tissue interface. This observation is consistent with the enzyme supported degradation behaviour, which was determined “in vitro”. PDC revealed to induce the formation of blood micro-vessels nearby in the periimplantary tissues. Both might explain the good PDC integration into tissues in terms of a strong connection between the implant and the periimplantary tissue. Micro …blood-vessels might be involved in the clearance of the small particles, which appear in the periimplantary tissue when PDC degrades. Show more

Keywords: PDC, degradation, angiogenesis, biomaterial, immunhistochemistry

DOI: 10.3233/CH-2010-1289

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 117-122, 2010

Authors: Franke, R.-P. | Fuhrmann, R. | Mrowietz, C. | Rickert, D. | Hiebl, B. | Jung, F.

Article Type: Research Article

Abstract: Isoforms of the enzyme lactate dehydrogenase (LDH) were found in almost all cells of the organism and an elevated activity of LDH in the circulation is thought to be a clear indicator of elevated cell destruction coinciding with an increased release of components from the cellular cytoplasm, e.g. LDH. Here, we report on an in-vitro examination to test whether radiographic contrast media (RCM) could induce cell destruction followed by an increase in LDH release. The RCM were tested in non-flow cultures of human umbilical venous endothelial cells (HUVEC) of the fourth passage seeded on extracellular matrix and the results were …compared to those from control cultures not exposed to contrast media. The examination revealed that the addition of contrast media to the cell culture media supplemented with pooled human serum (HSP) as source of exogenous LDH was followed by a strong decrease in LDH activity both in the absence and presence of HUVEC. Within 1.5 min after the addition of contrast media to the culture medium supplemented with HSP (30% vol of the culture medium were replaced by either of two contrast media, Iodixanol or Iopromide) the LDH activity decreased about 80% compared to the initial values. In contrast, the LDH activity did not change in cell culture media not supplemented with RCM. The partial replacement of HSP supplemented cell culture medium by RCM will cause a dilution of cell culture medium constituents. The decrease of LDH activity, however, was much stronger than the decrease thought to be attributable to the effects of dilution of cell culture medium, so that the role of dilution seems to be a minor one in this case. It has to be assumed that the RCM could interact with the LDH available in the culture medium as well as with the substrates delivered with the measurement system for the assessment of LDH activity, so that both, the amount of LDH and the activities of enzymes involved might be influenced. In the presence of HUVEC a similar effect was observed. Here, a little less strong decrease of LDH activity occurred compared to the decrease in cell culture medium without HUVEC. This was unexpected because a considerable amount of HUVEC were detached after the addition of contrast media and many of these cells were damaged seriously so that a significant amount of endogenous LDH should have been released. These unexpected results make it necessary to re-evaluate those past time examinations focussed on cell damage/destruction in the presence of contrast media, where the measurement of LDH activity was used as indicator or cell vitality and where cell decease rates were correlated to questionable toxic influences. According to the results of the examination reported here it is difficult to uphold the interpretation of recently published findings that contrast media almost exclusively induce cellular apoptosis and not necrosis. Show more

Keywords: Radiographic contrast media, lactate dehydrogenase, endothelial cells

DOI: 10.3233/CH-2010-1290

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 123-130, 2010

Authors: Connes, Philippe | Frank, Suhr | Martin, Cyril | Shin, Sehyun | Aufradet, Emeline | Sunoo, Sub | Klara, Brixius | de Mauverger, Eric Raynaud | Romana, Marc | Messonnier, Laurent | Kang, Joonku | Varlet-Marie, Emmanuelle | Feasson, Leonard | Hardy-Dessources, Marie-Dominique | Wilhelm, Bloch | Brun, Jean-Frederic

Article Type: Research Article

Abstract: The present article summarizes recent data presented at the Exercise and Hemorheology symposium during the 15th Conference of the European Society for Clinical Hemorheology and Microcirculation (June 28–July 1, Pontresina, Switzerland, 2009). The review starts with several unresolved paradoxes in exercise hemorheology. Then, we focus on the potential hemorheological and immunological mechanisms involved in the adverse events sometimes reported in exercising sickle cell trait carriers, and the role of habitual physical activity. In a fourth part, new results on the effects of acute hypoxia on blood rheology are presented. Finally, we will discuss recent experimental evidences on the role of …exercise on the regulation of nitric oxide synthesizing mechanisms in red blood cell. Show more

Keywords: Exercise, red blood cell deformability, red blood cell NOS, sickle cell trait, hypoxia

DOI: 10.3233/CH-2010-1291

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 131-141, 2010

Authors: Grossin, Nicolas | Boulanger, Eric | Wautier, Marie-Paule | Wautier, Jean-Luc

Article Type: Research Article

Abstract: Elevated glucose concentration increases oxidation and Advanced Glycation End product (AGE) formation. The binding of circulatory AGEs or AGEs included in erythrocyte membrane to the receptor for AGEs (RAGE) generates in endothelial cells an oxidative stress and enhances the expression of inflammatory molecules. Engagement of RAGE by AGEs and subsequent signaling plays an important role in the development of diabetic complications. Soluble RAGE isoforms (sRAGE) neutralize the ligand-mediated damage by acting as a decoy. If the expression of RAGE is upregulated during the pathogenesis of inflammatory diseases, sRAGE mostly found decreased when complications ensue. By modulating RAGE isoform expression, it …could be possible to reduce the incidence of complications. This review focused on the capability of Angiotensin Receptor Blockers (ARBs), which are used to treat patients with hypertension and/or diabetes, to modulate RAGE isoform expression because some data reported the interference with RAGE downstream. In this regard, three ARBs – irbesartan, telmisartan, candesartan cilexetil – were tested and provided evidence for their ability to inhibit in human endothelial cells the expression of membrane-bound and soluble RAGE isoforms induced by the inflammatory factor Tumor Necrosis Factor-α (TNF-α), demonstrating the potential benefits of these molecules in RAGE-oriented therapies. Modulating RAGE isoforms expression by correcting endothelial dysfunction is achievable by drugs already used for hypertension or diabetes treatment such as ARBs. Show more

Keywords: Receptor for advanced glycation end products (RAGE), soluble RAGE (sRAGE), oxidative stress, angiotensin receptor blocker (ARB)

DOI: 10.3233/CH-2010-1292

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 143-153, 2010

Authors: Fornal, M. | Korbut, R.A. | Królczyk, J. | Grodzicki, T.

Article Type: Research Article

Abstract: The evolution of rheological properties of erythrocytes and geometrical parameters of left ventricle during therapies aimed at reducing cardiovascular disease (CVD) risk has been investigated. The study group consisted of 29 individuals who were diagnosed with the presence of at least one CVD risk factor at the time of entry to the study. Appropriate therapies were applied and the patients were followed for two years. Two groups of patients could be distinguished. The first group consisted of 12 individuals who were rigorously applying the therapy and for whom blood pressure, total cholesterol, LDL and glucose returned to normal levels. The …second group included 17 patients for whom the above mentioned parameters remained pathological in spite of the applied therapy. In the first group, erythrocyte deformability as well as LVMI improved: deformability increased on average by 17% (p < 0.025), whereas LVMI decreased by 8% but not in a statistically significant manner (p < 0.27). In the second group, the results indicate worsening of both hemorheological properties and left ventricular geometry: RBC deformability became lower by 15% (p < 0.00001) and LVMI increased by 18% although this change was not statistically significant (p < 0.19). The results indicate that blood rheology improves when the CVD risk is reduced by administered therapy and worsens when the risk increases. Similar behavior shows LVMI. It is very likely that left ventricular geometry is influenced by blood rheology. Show more

Keywords: Erythrocyte deformability, left ventricular geometry, CVD risk

DOI: 10.3233/CH-2010-1296

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 155-159, 2010

Authors: Liuni, Andrew | Luca, Mary Clare | Gori, Tommaso | Parker, John D.

Article Type: Research Article

Abstract: Animal studies have consistently demonstrated the ability of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors to limit the damage induced by ischemia-reperfusion (IR) in the cardiac, cerebral and mesenteric circulation through a mechanism dependent on the upregulation of cyclooxygenase-2 (COX-2). Our group performed studies aimed at investigating the mechanism of HMG-CoA reductase inhibitor-mediated endothelial protection from IR injury, in particular the role of COX-2, in a human in vivo model of IR-induced endothelial dysfunction. We demonstrated that HMG-CoA reductase inhibition protects against IR-induced endothelial damage, an effect that was lost upon COX-2 inhibition. These observations may suggest a mechanistic explanation for …the cardioprotection observed in clinical settings such as percutaneous coronary interventions and coronary artery bypass surgery and may also propose a mechanistic hypothesis for the reported cardiotoxic effects of cyclooxygenase-2 inhibitors observed in clinical studies. These studies are summarized and discussed in the present paper. Show more

Keywords: Endothelium, ischemia, reperfusion, ischemic preconditioning, statins

DOI: 10.3233/CH-2010-1294

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 161-167, 2010

Authors: Ulker, Pinar | Meiselman, Herbert J. | Baskurt, Oguz K.

Article Type: Research Article

Abstract: Previous reports have demonstrated that red blood cells (RBC) have an active nitric oxide (NO) synthesizing mechanism which has properties similar to endothelial nitric oxide synthase (eNOS). This red cell NOS activity contributes to the NO export from RBC. The present study explored the influence of shear stress applied to RBC on NO concentrations of cell suspensions. RBC were exposed to shear stress by filtration through 5µm diameter pores under 10cm H2 O pressure, generating a wall shear stress of ∼110Pa. NO concentration in the RBC suspensions were measured using electrochemical NO probes before and after filtration through the micropores. …NO concentration was found to be significantly increased after a single passage of RBC suspensions through the micropores. The increment in NO concentration depended on the presence of calcium, being 21.8±4.4 nM with 1 mM calcium and 13.7±2.7 nM without added calcium. Including the calcium chelator EDTA completely abolished this increase. The increment of NO was also affected by the level of oxygenation, being more pronounced under hypoxic conditions. These results confirm that RBC NO generating mechanisms can be stimulated by exposing red cells to shear stress and that calcium plays a role in this stimulation. Show more

Keywords: Nitric oxide, shear stress, erythrocyte, calcium, oxygenation

DOI: 10.3233/CH-2010-1293

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 169-175, 2010

Authors: Ahmadizad, Sajad | Bassami, Minoo

Article Type: Research Article

Abstract: The purpose of this study was to investigate the effects of time of day on responses of the main determinants of blood rheology to acute endurance exercise. Ten healthy male subjects (age, 26.9 ± 5.5 yr) performed two bouts of running at 65% of VO2peak for 45min on a motorised treadmill in the morning (08:00h) and evening (20:00h), which were followed by 30 min recovery. The two exercise trials were performed in two separate days with 7 days intervening. Haemorheological variables were measured before, immediately after exercise and after recovery. Haematocrit, haemoglobin and RBC count were increased significantly (p …< 0.01) after 45min running in both morning and evening trials and normalised following recovery, irrespective of time of day. Plasma viscosity increased significantly (F2,18 = 12.4, p < 0.01) following sub-maximal exercise in both trials and returned to pre-exercise level at the end of recovery. Baseline values (p < 0.05) but not responses of plasma viscosity to exercise were significantly affected by time of day. Neither a significant main effect of exercise nor a significant (p > 0.05) time-of-day effect was found for plasma proteins. It was concluded that sub-maximal running at 08:00 or 20:00 h does not induce different responses in the main determinant of blood rheology. Show more

Keywords: Endurance exercise, time of day, plasma viscosity, fibrinogen, haematocrit

DOI: 10.3233/CH-2010-1295

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 177-184, 2010

Authors: Jabs, Alexander | Fasola, Federica | Muxel, Selina | Münzel, Thomas | Gori, Tommaso

Article Type: Research Article

Abstract: Pathophysiological studies have clearly demonstrated that the relationship between endothelial [dys]function and tissue ischemia is bidirectional: while it is well accepted that endothelial dysfunction has a key role in the progression and destabilization of coronary atherosclerosis, it is also well known that the endothelium is particularly sensitive to ischemia and reperfusion injury, and that this damage critically determines the extent of tissue damage, e.g. myocardial infarct size. Therefore, protecting the endothelium from ischemia could potentially have important clinical implications. In this scenario, reactive oxygen species [ROS] play a particularly important role: these elusive mediators are involved in determining the endothelial …toxic effect of risk factors and are involved in reperfusion injury; however, most importantly, ROS are also key mediators of endothelial preconditioning, a protective process that is characterized by a reduced sensitivity to ischemia and reperfusion injury. We report considerations regarding these phenomena and their potential pharmacologic manipulation as discussed in a lecture at the recent Conference of the European Society of Clinical Hemorheology and Microcirculation held in Pontresina, Switzerland. Show more

Keywords: Oxygen free radicals, ischemia, reperfusion, endothelium, endothelial dysfunction, nitric oxide, ischemic preconditioning

DOI: 10.3233/CH-2010-1297

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 185-191, 2010

Authors: Zengel, P. | Siedek, V. | Berghaus, A. | Clevert, D.A.

Article Type: Research Article

Abstract: Purpose: Obstructive diseases of the salivary glands are often based on Sialolithiasis; however, conventional radiological imaging or ultrasound does not provide a diagnosis in 5–10% of all cases. It was the aim of our study to examine the effectiveness and viability of an intraductal applied contrast-enhanced ultrasound (IA-CEUS) to improve the visualization of obstructive diseases of the salivary glands in comparison to conventional ultrasound and clinical symptoms. Materials and methods: The study included fifteen patients with swelling of indeterminate cause and/or pain of one or more salivary glands. A high-end ultrasound machine (Siemens, ACUSON, S 2000, Germany) with a multi-frequency …linear 9MHz transducer was used to carry out contrast-enhanced ultrasound with SonoVue® . Results: All patients were examined using all diagnostic ultrasound tools of the study. The results show that the procedure is easy and convenient to perform, as well as efficient, but more significantly, that the intraductal contrast agent improved the diagnostic assessment capabilities of ultrasound for patients with obstructive salivary gland diseases, thereby helping to identify the best treatment. Conclusion: In comparison to conventional ultrasound, the use of an intraductal applied contract-enhanced ultrasound not only improved the visualization of the glandular duct system as a whole, but was less time-consuming as well as more reproducible. Thus, IA-CEUS with an intraductal applied contrast agent (IA-CEUS) is a promising tool that provides additional helpful information and an improvement for cases involving patients with unclear symptoms. Show more

Keywords: Intraductal, ultrasound, salivary gland, obstruction, classification

DOI: 10.3233/CH-2010-1298

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 193-205, 2010

Authors: Girlich, C. | Schacherer, D. | Lamby, P. | Scherer, M.N. | Schreyer, A.G. | Jung, E.M.

Article Type: Research Article

Abstract: The aim was to describe the perfusion pattern of the inflamed bowel wall and the surrounding tissue in inflammatory bowel disease and diverticulitis of the sigmoid colon applying a high resolution matrix transducer and the new hybrid technique. We performed contrast enhanced ultrasound (CEUS) using an updated version of the 1–5MHz (C1-5-D convex probe) and the 6–9MHz probe (9L-D linear probe) as well as a matrix 6–15MHz transducer (ML 6–15-D Matrix Array Linear Probe) and updated post-processing procedures to examine microvascularization of inflamed bowel wall in Crohn’s disease (11 patients), ulcerative colitis (1 patient) and diverticulitis of the sigmoid colon …(2 patients). Assessment of mural microvascularization was successful as well as identification of fistulas (2 patients) and covered perforation (1 patient). Moreover analysis of time intensity curves revealed increase of signal intensity up to 20dB. Summarizing, application of high resolution linear probes and use of updated post-processing methods substantially improve detection of inflammation-caused increased microcirculation of the bowel wall and the surrounding tissue as well as identification of complications as fistulas or covered perforations. Show more

DOI: 10.3233/CH-2010-1299

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 207-215, 2010

Authors: Thalhammer, Christoph | Ferriani, Viviana | Husmann, Marc | Rufibach, Kaspar | Meier, Thomas | Amann-Vesti, Beatrice R.

Article Type: Research Article

Abstract: Purpose: Factors predicting renal function and recurrent stenosis following percutaneous renal revascularization are poorly identified. The predictive value of hemodynamic duplex ultrasound (DUS) parameters was evaluated. Methods: In a prospective observational study patients undergoing stenting of renal artery stenosis (RAS) were included. Renal resistance index (RI) and peak systolic velocity (PSV) were measured at baseline, one day, and six months after intervention. Results: At 6-months follow-up 16 (16.8%) restenosis of 105 treated renal arteries were detected. Baseline RI was 0.69 ± 0.12 and increased significantly to 0.72 ± 0.09 after 6 months (p < 0.0001), however, RI did not predict …restenosis. PSV at baseline and age were independent predictors for increased RI at 6 months (p = 0.0078 and p = 0.0019). Diabetics had a significant higher RI before revascularization (0.74 ± 0.08) than non-diabetics (0.68 ± 0.12, p = 0.04). PSV after stenting was higher in patients with restenosis (1.4 ± 0.4 m/sec vs. 1.0 ± 0.3 m/sec, p = 0.002) and was an independent predictor for restenosis. Conclusions: Increased PSV within the stent one day after the procedure is predictive for restenosis. Patients with high grade RAS and older patients have a worse outcome. DUS is recommended to detect patients at risk for restenosis after percutaneous renal revascularization. Show more

Keywords: Renal artery stenosis, duplex ultrasound, percutaneous renal revascularization, intrarenal resistance index

DOI: 10.3233/CH-2010-1300

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 217-224, 2010

Authors: Stock, K. | Hann von Weyhern, C. | Slotta-Huspenina, J. | Burian, M. | Clevert, D.A. | Meining, A. | Prinz, C. | Pachmann, C. | Holzapfel, K. | Schmid, R.M. | Lersch, C.

Article Type: Research Article

Abstract: Objectives: The evaluation of subepithelial tumors of the stomach is normally the domain of gastroscopy and endoscopic ultrasound. We investigated these rare tumors using transabdominal B-mode ultrasound and performed perfusion analysis of these tumors with contrast enhanced ultrasound. Methods: Patients with gastrointestinal stromal tumors (GIST, n = 3), leiomyoma (n = 1) and schwannoma (n = 1) were routinely examined using conventional B-mode-ultrasound, colour Doppler ultrasound and contrast-enhanced ultrasound (contrast media: Sonovue® ; ultrasound device: Siemens Acuson Sequoia™ 512). Gastroscopy, endosonography with puncture of the subepithelial tumor and computed tomography were also performed in all patients. After surgery, the …resected stomach tumors were correlated with the preoperative imaging findings. Results: All calculated tumor sizes using any imaging modalities showed a good correlation with the macroscopic tumor sizes ex-vivo. Histologically increased tumor size of the GISTs was correlated with large, central avascular areas. The GISTs and the leiomyoma presented with mixed echogenicity in B-mode-ultrasound. Colour Doppler ultrasound was able to detect some vessels in the periphery of the tumor only. Using contrast-enhanced ultrasound the GISTs and the leiomyoma presented hypervascular. The contrast pattern of these lesions was from the periphery to the centre or diffuse or a progressive centrifugal fill in during the arterial phase. We also registered slowly progressive washout starting at the end of the arterial phase and increasing into the late phase. The contrast media behaviour in the schwannoma was different from that describt above within the GISTs: it was noted to have a diffuse intralesional pattern at the start of the arterial phase followed by an early, rapidly progressing washout-phenomenon. Conclusion: In our pilot study B-mode transabdominal ultrasound was able to visualise gastric subepithelial tumors larger than three centimetre. Contrast-enhanced ultrasound is a proven method in clinical practice for the perfusion analysis of gastric subepithelial tumors. It can also be used for the planning of ultrasound-guided biopsies to avoid punctures of necrotic tumor parts. Show more

Keywords: Ultrasonography, contrast-enhanced ultrasound, microperfusion, perfusion pattern, stomach, gastrointestinal stromal tumor, schwannoma, leiomyoma

DOI: 10.3233/CH-2010-1302

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 225-232, 2010

Authors: Velcheva, Irena | Antonova, Nadia | Damianov, Petar | Dimitrov, Nikolay

Article Type: Research Article

Abstract: The aim of the study was to investigate the changes of the common carotid local hemodynamic factors like wall shear stress and tensile forces in 16 patients with chronic unilateral cerebral infarctions (CUCI), 58 patients with risk factors (RF) for cerebrovascular disease (CVD) and 25 healthy control subjects. The blood flow velocities (BFV), the internal diameters (D) and the vessel wall intima-media thickness (IMT) in the common carotid arteries (CCA) were recorded with color duplex sonography. Systolic (SBP) and diastolic (DBP) blood pressure were measured and mean blood pressure (MBP) was calculated by the formula of Wiggers. Whole blood viscosity …(WBV) at the shear rate of 94.5 s−1 was measured on the day of the Doppler ultrasound examination with a rotational viscometer Contraves Low Shear 30. Wall shear stress (WSS), the circumferential wall tension (T) and the tensile stress τ were calculated. The main RF in the patients’ groups were hypertension and hyperlipidemia. The SBP, WBV and IMT were significantly increased in the patients with UCI and RF for CVD in comparison to controls. Lower systolic WSS and τ and higher T were established in the patients with UCI. The IMT correlated with WSS and τ. The study confirms the complex influence of the changes in WBV and blood pressure for the development of carotid atherosclerosis. Show more

Keywords: Cerebral infarctions, color duplex sonography, common carotid artery, wall shear stress, whole blood viscosity

DOI: 10.3233/CH-2010-1306

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 233-238, 2010

Authors: Velcheva, Irena | Titianova, Ekaterina | Antonova, Nadia

Article Type: Research Article

Abstract: The study aimed to follow the influence of some hemorheological parameters and mean blood pressure (MBP) on the carotid blood flow asymmetry in 20 patients with chronic unilateral cerebral infarctions (UCI) as compared to 30 patients with transient ischemic attacks (TIAs), 17 patients with risk factors (RF) for cerebrovascular disease (CVD) and 11 healthy controls. Hemorheological variables: hematocrit (HT), plasma (PV) and whole blood viscosity (WBV), serum lipids and echocardiographic parameters were investigated. Blood pressure (systolic, diastolic and mean) was registered and color duplex sonography of the carotid arteries was performed. The lumen diameter, the intima media thickness (IMT) and …the blood flow velocity (systolic, mean and diastolic) in the carotid arteries were examined and the velocity asymmetry ratio (AR) was calculated. Significant increase of HT in UCI, of mean blood pressure (MBP) in the patients with RF and TIAs and of IMT and velocity parameters in all patients was established. The correlation analysis revealed parallel influence of HT, MBP, cardiac function, IMT, lumen diameter and some of the modifiable RF on the carotid AR in patients with chronic UCI affecting mainly the collateral circulation. The complex investigation of these factors would enable us to individualize the therapeutic approach in the patients with cerebral ischemic events. Show more

Keywords: Asymmetry ratio, carotid blood flow velocity, hematocrit, mean blood pressure, color duplex sonography, echocardiography, unilateral cerebral infarctions

DOI: 10.3233/CH-2010-1301

Citation: Clinical Hemorheology and Microcirculation, vol. 45, no. 2-4, pp. 239-244, 2010

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