Clinical Hemorheology and Microcirculation - Volume 53, issue 1-2

Authors: Jung, F. | Niimi, H. | Forconi, S. | Stoltz, J.F.

Article Type: Other

DOI: 10.3233/CH-2012-1570

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 1-2, 2013

Authors: Forconi, Sandro | Gori, Tommaso

Article Type: Research Article

Abstract: A number of factors are involved in the regulation and maintenance of vascular homeostasis. The role of the vascular endothelium has been identified almost three decades ago, and a number of lines of evidence provide solid support to the role of this tissue in modulating not only vascular tone, but also phenomena such as platelet, red blood cell aggregation and deformability. In turn, hemorheological characteristics have been proven to impact on the endothelial release of mediators and therefore on vascular tone. Both biochemical and physical stimuli are sensed by the endothelium as stimuli for the release of oxygen free radicals …and nitric oxide. In particular, changes in blood viscosity have a direct effect on shear stress, which is believed to be the physiological stimulus for endothelial activation. These considerations have lead us to formulate an alternative hypothesis for the meaning of hyperviscosity in the setting of ischemic syndromes. While this hypothesis is supported by animal data, the evidence of cross-sectional human studies is controversial. This evidence is discussed in the present review. Show more

Keywords: Endothelial function, viscosity, hematocrit, platelets

DOI: 10.3233/CH-2012-1571

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 3-10, 2013

Authors: Wautier, Jean-Luc | Wautier, Marie-Paule

Article Type: Research Article

Abstract: Red blood cell (RBC) adhesion to endothelium can be studied in static and flow conditions. Increased RBC adhesion was first described in sickle cell disease. Several molecules were shown to be involved in this phenomenon: VCAM-1, α4β1, Lu/BCAM, ICAM-4. In malaria, Plasmodium falciparum erythrocyte membrane protein1 binds to ICAM-1, PECAM-1 and facilitates the parasite dissemination. In diabetes mellitus augmented RBC adhesion is correlated to the severity of vascular complications. Glycated RBC band3 reacts with the endothelial Receptor for Advanced Glycation End products (RAGE). RAGE engagement induced endothelial cell dysfunction. In patients with Polycythemia Vera (PV), the most frequent myeloproliferative disorder, …constitutive phosphorylation of RBC Lu/BCAM is responsible for an increased adhesion to endothelial cell laminin. Retinal vein occlusion (RVO) is a common cause of permanent visual loss. Spontaneous growth of erythroid precursors was observed in more than 25% of patients. RBC adhesion was enhanced and correlated to phosphatidyl serine (PS) expression on RBC. Anti-PS receptor blocked RVO RBC adhesion indicating that the counterpart of RBC PS is PS endothelial cell receptor. Erythrocyte adhesion is mediated by different molecule abnormalities in different diseases but is associated to a higher risk of thrombosis and vascular complications. Show more

Keywords: Red blood cell, endothelial cell, adhesion molecules, sickle cell disease, diabetes, malaria, polycythemia vera, retinal vascular occlusion

DOI: 10.3233/CH-2012-1572

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 11-21, 2013

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

Article Type: Research Article

Abstract: Red blood cell (RBC) aggregate to form two- and three-dimensional structures when suspended in aqueous solutions containing large plasma proteins or polymers; this aggregation is reversible and shear dependent (i.e., dispersed at high shear and reformed at low or stasis). The extent of aggregation is the main determinant of low shear blood viscosity, thus predicting an inverse relationship between aggregation and in vivo blood flow. However, the effects of aggregation on hemodynamic mechanisms (e.g., plasma skimming, Fåhraeus Effect, microvascular hematocrit) may promote rather than impede vascular blood flow. The impact of enhanced RBC aggregation on endothelial function and hemostatic mechanisms …adds further complexity, thereby requiring specific attention to the nature, extent and time course of aggregation when considering its overall influence on tissue perfusion. A detailed understanding of aggregation effects is important from a clinical point of view since it may be enhanced during a variety of pathophysiological processes, including infections, circulatory and metabolic disorders, hematological pathologies and several other disease states. Altered RBC aggregation may be an indicator of disease as well as a factor affecting the course of the clinical condition; the prognostic value of RBC aggregation indices has been demonstrated in various diseases. Currently, RBC aggregation is an easily and accurately measurable parameter, and therefore may be expected to have broader clinical usage in the future. Show more

Keywords: Inflammation, aggregability, hemorheology, tissue perfusion

DOI: 10.3233/CH-2012-1573

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 23-37, 2013

Authors: Saldanha, Carlota

Article Type: Research Article

Abstract: A brief review of the fibrinogen molecule composition and structure is presented like as an introduction to the effects of this plasma protein on the red blood cell hemorheoplogical properties namely erythrocyte aggregation tendency and deformability ability. The protein membrane RBC target for fibrinogen is also highlight as well as the erythrocyte signal transduction pathway associated with nitric oxide mobilization resulting from its binding.

Keywords: Fibrinogen, nitric oxide, CD47, erythrocyte aggregation, erythrocte deformability

DOI: 10.3233/CH-2012-1574

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 39-44, 2013

Authors: Muravyov, Alexei V. | Tikhomirova, Irina A.

Article Type: Research Article

Abstract: This study was designed to investigate the dependency of the red blood cell deformability upon activation of extra- and intracellular signaling pathways. Exposures of red blood cells (RBCs) to catecholamines and to insulin led to positive change in the RBC deformability. When forskolin, a stimulator of adenylyl cyclase (AC), was added to RBC suspension, the RBC deformability was increased. Somewhat more significant deformability rise appeared after RBC incubation with dB-AMP. The inhibitors of phosphodiesterase (PDE) activity increased red cell deformability. These results revealed a considerable role of the AC-cAMP signaling system in the regulation of red blood cell deformability. The …rise of the red blood cell Ca2+ influx, stimulated by mechanical loading or A23187 was accompanied by a marked lowering of RBC deformability. At the same time blocking of Ca2+ entry into RBC by verapamil or Ca2+ chelating by EGTA led to significant deformability rise. The comparison of the effect of the different protein kinases on the red blood cell deformability showed that it was altered more considerable under PKA activation by forskolin or dB-cAMP than by other protein kinases. There was a lesser but quite statistically significant effect of tyrosine protein kinase (TPK) on RBC microrheology. Whereas the microrheological effect of PKC was not so considerable. The problem of the short-term regulation of red blood cell microrheology is examined. The latter includes: the modes of activation of extra- and intracellular molecular signaling pathways, ligand - receptor interaction, second messengers, membrane protein phosphorylation. On the whole the total data clearly show that the red cell deformability changes are connected with activation of different extra - and intracellular signaling pathways. It seems reasonable to suppose that red blood cell deformability changes were mainly associated with activation of the AC-cAMP-PKA pathway, and with decrease of Ca2+ entry into cells. Show more

Keywords: Red blood cell deformability catecholamines, insulin, acetylcholine, adenylyl cyclase, phosphodiesterase, membrane receptors, Ca$^{2+}$, protein kinases

DOI: 10.3233/CH-2012-1575

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 45-59, 2013

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

Article Type: Research Article

Abstract: Comparative data on blood composition and blood flow properties indicate different levels of interspecies variation for several parameters. Hematocrit and hemoglobin levels have relatively low variability among mammals, while mean cell volume and red blood cell (RBC) count are more variable. There is also a difference of variability between high and low shear rate blood viscosity in mammals, with low shear rate viscosity having a higher degree of interspecies variation. This observation parallels the diversity of RBC aggregation among mammalian species. Allometric relations for blood rheology parameters indicate highly significant correlations of low shear rate blood viscosity and RBC aggregation …with body weight, especially if species belonging to the order Artiodactyla are excluded. These allometric relations can be used to formulate various hypotheses about the evolutionary histories of circulatory functions, as well as hypotheses related to the role of RBC aggregation in the mammalian circulatory system. Such comparative studies and analytical reasoning based on comparative data may contribute to answering the “why” questions, and accordingly may improve our understanding of circulatory functions and hence may have possible clinical importance. During the last several decades, similar approaches to various medical concepts have yielded a new approach to medicine that is now known as Evolutionary Medicine. Show more

Keywords: Evolution, darwinian medicine, comparative physiology, blood rheology, hemodynamics

DOI: 10.3233/CH-2012-1576

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 61-70, 2013

Authors: Reinhart, W.H.

Article Type: Research Article

Abstract: Platelets play a key role in primary hemostasis and in the pathogenesis of atherosclerosis and atherothrombotic events such as stroke and myocardial infarction. When a plaque ruptures, platelets adhere to the underlying collagen matrix, become activated and aggregate, which may lead to vascular occlusions. Hemorheological aspects are intimately involved in this process. The assessment of this platelet function in vitro is difficult and has not reached the stage of routine use. Inhibition of platelet aggregation is the corner stone of any treatment of vascular disease. It is achieved mainly by to mechanisms, inhibition of thromboxane formation by acetylsalicylic acid, and …with ADP receptor antagonists such as clopidogrel. Newer agents are being developed with the difficult mission to inhibit platelet aggregation more efficiently, and simultaneously reduce the risk of bleeding. Show more

Keywords: Aggregation, atherosclerosis, erythrocytes, inflammation, platelets

DOI: 10.3233/CH-2012-1577

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 71-79, 2013

Authors: Papp, J. | Kenyeres, P. | Toth, K.

Article Type: Research Article

Abstract: Platelets play an important role both in normal hemostasis and in pathological thrombus formation. Several large-scale clinical studies have proved that the inhibition of platelet aggregation results in a significant decrease in mortality and morbidity of ischemic atherothrombotic events, thus antiplatelet therapy became a key pharmacological method in prevention and treatment of such cardiovascular, cerebrovascular and peripheral arterial diseases. The present paper aims to give a brief overview of the most important antiplatelet drugs, their mechanism of action and their recommended usage in cardiovascular diseases. We also discuss possible methods to monitor the effectiveness of therapy and possible causes of …therapeutic failure. Show more

Keywords: Antiplatelet drugs, inhibition of platelet aggregation, coronary heart disease, stroke, peripheral arterial disease, aspirin and clopidogrel resistance, platelet aggregometry

DOI: 10.3233/CH-2012-1578

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 81-96, 2013

Authors: Jung, F. | Braune, S. | Lendlein, A.

Article Type: Research Article

Abstract: Cardiovascular implants are increasingly important in regenerative medicine. To improve the safety and function of blood-contacting implants a major need exists for new polymer-based biomaterials that avoid adverse reactions, particularly thrombotic events. This review is aimed to summarize the multi-stepped and interlinked processes leading to a thrombus growth on body foreign surfaces: protein adsorption, platelet adhesion accompanied by activation and spreading and the release of substances of various organelles activating other neighboured platelets (and the plasmatic coagulation) leading to the formation of a plug of platelets and, finally, to a thrombus.

Keywords: Protein adsorption, platelet activation, platelet aggregation, foreign body

DOI: 10.3233/CH-2012-1579

Citation: Clinical Hemorheology and Microcirculation, vol. 53, no. 1-2, pp. 97-115, 2013