Clinical Hemorheology and Microcirculation - Volume 63, issue 1

Article Type: Other

DOI: 10.3233/CH-162058

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 1-2, 2016

Authors: Kuss, N. | Bauknecht, E. | Felbinger, C. | Gehm, J. | Gehm, L. | Pöschl, J. | Ruef, P.

Article Type: Research Article

Abstract: Determination of shear stresses at given shear rates allow approximation of flow curves by mathematical models and to calculate viscosities of non-Newtonian fluids. In term neonates, the mean arterial blood pressure (MAP) is markedly below that of adults, therefore rheological properties of blood play an important role in maintaining perfusion. Whole blood viscosity was measured in umbilical cord blood taken from 62 term neonates using the LS 300 viscometer. Individual parameters that influence the viscosity of whole blood were measured: red blood cell (RBC) aggregation, plasma viscosity, hematocrit, and RBC deformability. The flow curve of whole blood of neonates was …approximated by the method of Ostwald with the highest quality whereas in adults the best approximation was found by the method of Casson. With hematocrits of 0.40, the viscosity of whole blood in newborns approximated by Ostwald (9.84 ± 5.12 mPa·s) was significantly lower than that of adults (15.34 ± 3.01 mPa·s). The aggregation index of the blood of newborns was markedly lower (2.98 ± 2.12) than in adults (14.63 ± 3.50) whereas RBC deformability was higher in neonates. The viscosity of plasma determined by Ostwald revealed a lower exponent (n) in neonates (0.94 ± 022) compared to adults (1.01 ± 0.12) and the viscosity determined by Newton was lower in neonates (1.04 ± 0.16 mPa·s) than in adults (1.19 ± 0.07 mPa·s). The flow curve of neonatal blood which is best approximated by the model of Ostwald emphasizes its important viscous properties necessary for conditions with physiologically low blood pressure. Show more

Keywords: Ostwald, Casson, newborn, viscosity, flow curve, yield shear stress

DOI: 10.3233/CH-152008

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 3-14, 2016

Authors: Koutsiaris, Aristotle G.

Article Type: Research Article

Abstract: Wall shear stress (WSS) is a very important hemodynamic parameter implicated in many physiological and pathological phenomena. In order to study these phenomena, it is more convenient to use in vitro models before testing on animals and humans. Dynamic in vitro cerebrovascular models are considered capable of simulating the in vivo hemodynamic conditions, but only few of them seem to meet the criteria for this task. It is now clear that in the human eye microcirculation a significant pulsation exists at the pre-capillary arterioles with average WSS values more than twice those in the venular side, for …the same diameters. WSS heterogeneity is in support of segmental heterogeneity i.e. the endothelial phenotypic and functional difference among arterioles, capillaries and venules. In this review paper, the importance of WSS is described in detail and two more microvascular segments are proposed: a pre-capillary arteriolar and a post-capillary venular segment. The accurate hemodynamic simulation in all microvascular segments seems to be a prerequisite step in the development of dynamic in vitro blood brain barrier (BBB) models and microfluidic platforms on chip. Endothelial cells in the cardiovascular system seem to have sophisticated role acting like cardiovascular processing sensors (CPSs). Show more

Keywords: Wall shear stress, hemodynamics, human microcirculation in vivo, segmental heterogeneity, in vitro cerebrovascular models, blood-brain barrier, microfluidics

DOI: 10.3233/CH-151976

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 15-33, 2016

Authors: Laufer Perl, Michal | Havakuk, Ofer | Finkelstein, Ariel | Halkin, Amir | Revivo, Miri | Elbaz, Meital | Herz, Itzhak | Keren, Gad | Banai, Shmuel | Arbel, Yaron

Article Type: Research Article

Abstract: OBJECTIVES: High values of Red Blood Cell Distribution Width (RDW) have been associated with adverse outcome in various clinical settings. The mechanism behind this association is not clear. The Metabolic Syndrome (MetS) is a chronic inflammatory disorder that increases the risk for cardiovascular disease and death. The aim of our study was to evaluate the association between high RDW and the MetS in a relatively large cohort of patients. METHODS: A cohort of 3,529 consecutive patients undergoing coronary angiography was used to evaluate the association between RDW and the MetS. The association was assessed by using a …logistic regression. Cox’s regression analysis was used to evaluate the impact of RDW on long term mortality. RESULTS: The mean age was 65 years (range 24–97), with 27% women. Overall, 30% were diagnosed with metabolic syndrome. The prevalence of MetS was 29% in patients with RDW <14% and 34% in patients with RDW ≥14% (P  = 0.003). Using multivariate analysis, RDW values above 14% were independently associated with MetS (odds ratio 1.2 [95% CI 1.0–1.4], P  = 0.043). Among all the criteria of the metabolic syndrome, hypertension, elevated glucose levels and abdominal obesity were associated with high RDW, with hypertension being the strongest criteria, with an increased risk of 1.8 fold ([95% CI 1.5–2.1]; P  = 0.001). During follow up (1614 ± 709 days, 2–2763 days), long term mortality was 8% in the low RDW group and 28% in the high RDW group (p  < 0.001). CONCLUSION: RDW ≥14% is independently associated with higher rates of metabolic syndrome and long-term all-cause mortality. Show more

Keywords: RDW, Metabolic Syndrome, biomarkers, hs-crp, inflammation, obesity

DOI: 10.3233/CH-151978

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 35-43, 2016

Authors: Cho, Jung Rae | Lee, Chang Yeon | Lee, Jiyun | Seo, Hyang-Hee | Choi, Eunhyun | Chung, Namsik | Kim, Sung-Man | Hwang, Ki-Chul | Lee, Seahyoung

Article Type: Research Article

Abstract: Aberrant vascular smooth muscle cell (VSMC) proliferation and migration are a major pathological phenomenon in vascular disease characterized by intimal thickening. The important role of the mammalian target of rapamycin (mTOR) signaling in VSMC proliferation has been previously reported. Consequently, down-regulation of mTOR pathway may be an effective way of controlling excessive VSMC proliferation. Since microRNAs (miRNA) are newly emerging regulators of virtually all the biological processes including cellular proliferation, miRNAs targeting mTOR pathway may be utilized to suppress aberrant VSMC proliferation during pathologic conditions. Thus, in the present study, we screened miRNAs targeting mTOR, and we identified miR-761 as …a new mTOR targeting miRNA. Luciferase assay using luciferase vector containing 3’UTR of mTOR indicated that miR-761 directly targets mTOR mRNA leading to suppression of mTOR protein expression. Our data also indicate that miR-761 expression decreases during angiotensin II (AngII)-induced proliferation of VSMCs, and exogenous miR-761 delivery effectively inhibit the AngII-induced VSMC proliferation. Additionally, the results of migration tests demonstrate that down-regulation of mTOR using exogenous miR-761 suppresses AngII-induced migration of VSMCs as well. Taken together, the present study provided evidence that miR-761 can be a potent anti-proliferative agent for vascular diseases such as atherosclerosis and restenosis, and warrants further studies to validate the effectiveness of miR-761 in vivo . Show more

Keywords: Ang II, miR-761, mTOR, VSMC, proliferation

DOI: 10.3233/CH-151981

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 45-56, 2016

Authors: Cengiz, Melike | Ülker, Pinar | Üyüklü, Mehmet | Yaraş, Nazmi | Özen, Nur | Aslan, Mutay | Özyurt, Dilek | Basralı, Filiz

Article Type: Research Article

Abstract: This study investigated the effects of magnesium on blood rheological properties and blood pressure in nitric oxide synthase (NOS) inhibition-induced hypertension model. Hypertension was induced by oral administration of the nonselective NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME, 25 mg/kg/day) for 6 weeks and systolic blood pressure was measured by the tail-cuff method. The groups receiving magnesium supplementation were fed with rat chow containing 0.8% magnesium oxide during the experiment. At the end of experiment, blood samples were obtained from abdominal aorta, using ether anesthesia. Plasma and erythrocyte magnesium levels were determined by the atomic absorption spectrometer. RBC deformability and aggregation were …determined by rotational ektacytometry. Plasma fibrinogen concentration was evaluated by ELISA. Whole blood and plasma viscosities were determined by viscometer and intracellular free Ca++ level was measured by using spectroflurometric method. Blood pressure was elevated in hypertensive groups and suppressed by magnesium therapy. Plasma viscosity and RBC aggregation were found to be higher in hypertensive rats than control animals and these parameters significantly decreased in magnesium supplemented hypertensive animals. Other measurements were not different between experimental groups. These results confirm that blood pressure, plasma viscosity and RBC aggregation increased in NOS inhibition-induced hypertension model and oral magnesium supplementation improved these parameters. Show more

Keywords: Hypertension, magnesium supplementation, blood rheology

DOI: 10.3233/CH-152032

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 57-67, 2016

Authors: Michalska-Małecka, Katarzyna | Śpiewak, Dorota | Słowińska-Łożyńska, Ludmiła | Sierocka-Stępień, Justyna

Article Type: Research Article

Abstract: OBJECTIVE: The aim of this article was to present the influence of hemorheological factors on appearance of Retinal Vein Occlusion (RVO). Article explains which factors predispose to the occurrence of RVO. STUDY SELECTION: Data presented in the article were collected from both review articles and research articles as well as other sources concerning hemorheology, pharmacology and ophthalmology. RESULTS: Appearance of RVO is connected with blood viscosity and hemorheological parametres like aggregation of red blood cells, deformability of red blood cells, fibrinogen concentrations and haematocrit, and platelet activity. In the pathogenesis of retinal vein occlusion other …risk factors were also indicated: age, systemic diseases and smoking. Such correlation has been indicated in numerous researches which were conducted over the last years. RVO is usually accompanied by macular oedema. RVO may successfully be treated using intravitreal dexamethasone implant. CONCLUSION: Quick diagnosis and therapy create a possibility for successful treatment. Corticosteroid positive influence on visual acuity improvement has been indicted in two randomized, double-blind controlled studies – CRUISE and BRAVO. In both studies, the improvement of vision has been accompanied by a significant reduction of oedema in the vicinity of macula, reflected in the central retinal thickness. Show more

Keywords: Hemorheology, retinal vein occlusion, blood viscosity, thrombosis

DOI: 10.3233/CH-162056

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 69-76, 2016

Authors: Reimann, R. | Rübenthaler, J. | Hristova, P. | Staehler, M. | Reiser, M. | Clevert, D.A.

Article Type: Research Article

Abstract: Introduction: The aim of this study was to analyze the histological subtypes of clear cell renal cell carcinoma (RCC) examined by means of contrast-enhanced ultrasound (CEUS) and a second generation blood pool agent (SonoVue® , Bracco, Milan, Italy) during the pre-operative phase. Materials and Methods: 29 patients with histologically proven subtypes of clear cell RCC were examined. A total of three patients were diagnosed with highly differentiated clear cell RCC, 21 out of 29 cases with moderately differentiated clear cell RCC and five out of 29 patients had insufficiently differentiated clear cell RCC. An experienced radiologist examined …the patients with CEUS. The following parameters were analyzed: maximum signal intensity (PEAK), time elapsed until PEAK is reached (MTT), local blood flow (RBF), area under the time intensity curve (AUC) and the signal intensity (SI) during the course of time. For the groups all comparisons are made based on healthy renal parenchyma. Results: In the clear cell RCC significant differences (significance level p  < 0.05) between cancerous tissue and the healthy renal parenchyma were noticed in all four parameters. Therefore, the clear cell RCC stands out due to its reduced blood volume. However, it reached the PEAK reading relatively rapidly and its signal intensity was always lower than that of the healthy renal parenchyma. In the arterial phase retarded absorption of the contrast agent was observed, followed by fast washing out of the contrast agent bubbles. In all three histological subgroups no significant differences were noticed in PEAK and SI. However, the diagrams showed the possible bias, that the group of the insufficiently differentiated clear cell RCC had the highest PEAK-value and the highest signal intensity when compared with highly and moderately differentiated clear cell RCC. Conclusion: Our study suggests that CEUS may be an additional tool for non-invasive characterisation and differentiation of the three histological subtypes of clear cell RCC. Furthermore, it seems to have an additional diagnostic value in daily clinical. Show more

DOI: 10.3233/CH-152009

Citation: Clinical Hemorheology and Microcirculation, vol. 63, no. 1, pp. 77-87, 2016