Clinical Hemorheology and Microcirculation - Volume 30, issue 3-4
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Clinical Hemorheology and Microcirculation, a peer-reviewed international scientific journal, serves as an aid to understanding the flow properties of blood and the relationship to normal and abnormal physiology. The rapidly expanding science of hemorheology concerns blood, its components and the blood vessels with which blood interacts. It includes perihemorheology, i.e., the rheology of fluid and structures in the perivascular and interstitial spaces as well as the lymphatic system. The clinical aspects include pathogenesis, symptomatology and diagnostic methods, and the fields of prophylaxis and therapy in all branches of medicine and surgery, pharmacology and drug research.
The endeavour of the Editors-in-Chief and publishers of
Clinical Hemorheology and Microcirculation is to bring together contributions from those working in various fields related to blood flow all over the world. The editors of
Clinical Hemorheology and Microcirculation are from those countries in Europe, Asia, Australia and America where appreciable work in clinical hemorheology and microcirculation is being carried out. Each editor takes responsibility to decide on the acceptance of a manuscript. He is required to have the manuscript appraised by two referees and may be one of them himself. The executive editorial office, to which the manuscripts have been submitted, is responsible for rapid handling of the reviewing process.
Clinical Hemorheology and Microcirculation accepts original papers, brief communications, mini-reports and letters to the Editors-in-Chief. Review articles, providing general views and new insights into related subjects, are regularly invited by the Editors-in-Chief. Proceedings of international and national conferences on clinical hemorheology (in original form or as abstracts) complete the range of editorial features.
The following professionals and institutions will benefit most from subscribing to
Clinical Hemorheology and Microcirculation: medical practitioners in all fields including hematology, cardiology, geriatrics, angiology, surgery, obstetrics and gynecology, ophthalmology, otology, and neurology. Pharmacologists, clinical laboratories, blood transfusion centres, manufacturing firms producing diagnostic instruments, and the pharmaceutical industry will also benefit.
Important new topics will increasingly claim more pages of
Clinical Hemorheology and Microcirculation: the role of hemorheological and microcirculatory disturbances for epidemiology and prognosis, in particular regarding cardiovascular disorders, as well as its significance in the field of geriatrics. Authors and readers are invited to contact the editors for specific information or to make suggestions.
Abstract: Blood rheology is a well‐known determinant of tissue perfusion and, according to the Poiseuille relation, hemodynamic resistance in a constant‐geometry vascular network is directly proportional to blood viscosity. However, this direct relationship cannot be observed in all in vivo studies. Further, there are several reports indicating marked differences between the in vivo and ex vivo flow properties of blood. These differences can be explained, in large part, by considering special hemorheological mechanisms (e.g., Fahraeus–Lindqvist effect, axial migration) that are of importance in the microcirculation. Additionally, the influence of altered rheological properties of blood and its components on vascular control mechanisms…requires consideration: (1) There is an indirect relation between blood rheology and microvascular tone that is mediated by tissue oxygenation, with a compensatory vasodilation occurring if tissue perfusion is impaired due to hemorheological deterioration; (2) Blood rheology may influence vascular tone through alterations of wall shear stress, which in turn determines endothelial generation of vasoactive substances (e.g., nitric oxide). This latter point is of particular relevance to the field of clinical hemorheology, since enhanced red blood cell aggregation has been shown to affect nitric oxide synthesis and thus control of vascular smooth muscle tone. Such multiple pathways by which hemorheological changes can affect vascular resistance help to explain the continuing difficulty of predicting correlations between in vivo and ex vivo hemorheological behavior; they also suggest the need for continued experimental studies in this area.
Keywords: Vascular resistance, viscosity, red blood cell, rheology
Abstract: Hemorheological properties and disorders are very specific in the microcirculation since blood is actually not a fluid in the capillaries and in the adjacent arterioles and venules. This is because almost half of the blood volume constitutes the red and white blood cells whose size is commensurable with the microvessels lumen. Based on perennial investigations we concluded that the advancement of blood in capillaries is primarily dependent on the “structure” of the flowing blood that determines the resistance to blood advancement in the microvessels rather than on the well‐known hydrodynamic relationships characteristic for the larger blood vessels. Basing on…the perennial research of the hemorheological disorders in the microvessels we succeeded to specify the principal factors determining the blood flow resistance in the microcirculation. These factors are as follows: the erythrocyte enhanced aggregability > their deformability > the local hematocrit > the blood plasma viscosity. Solution of these theoretical problems is very important for the theory and practical medicine, since the blood rheological disorders in the microcirculation play a significant role in development and outcome of such essential diseases as the cerebral and cardiac infarcts, the diabetus mellitus, arterial hypertension, tumor grow, and many others.
Keywords: Hemorheology in microcirculation, blood flow structure in narrow microvessels, hemorheological disturbances in various diseases
Abstract: Erythrocytes in normal conditions have weak interactions with other blood cells and endothelial cells while in pathological circumstances they can adhere to endothelium and aggregate or agglutinate to blood cells. Erythrocyte adhesion was found to be abnormal in sickle cell anemia and diabetes mellitus and correlated to the vascular complications. Further studies demonstrated that VLA‐4 adhesion molecule (α4β1) present on erythrocytes bound to vascular cell adhesion molecule (VCAM‐1) of the endothelium. In addition, the blood group Lutheran molecule (LU) overexpressed on sickle erythrocytes bind to laminin present on cells or in the intercellular space. In diabetes mellitus the formation of…advanced glycation end products (AGE) by reaction between carbohydrates and free aminogroups of lysine is responsible for red blood cell membrane glycation. AGEs present on RBCs bind to the receptor for AGE (RAGE) on endothelium, activating endothelial cells. A molecule related to blood group Rhesus was demonstrated to belong to the intercellular adhesion molecule (ICAM) family. ICAM‐4 binds to integrins present on leukocytes (CD11‐CD18) and on platelets (α2β4) offering a surface, which can be involved in thrombosis. The identification of erythrocytes adhesion molecules open a new way to understand thrombotic processes and vascular dysfunction.
Abstract: Almost all of the cells of the human body are subjected to mechanical stresses. In endothelial cells, mechanical stresses can vary from some milli‐Pascal (shear stress) to one ore more Pascal (hydrostatic pressure). Now it is know that mechanical stresses have a decisive part cellular physiology. However, if the main biological effects of mechanical stress are well related, the mechanisms allowed the relation between mechanical stress to physiological phenomenon remain nearly unknown (mechanotransduction phenomenon). In this work, through personal results and published works, the authors considers all the effects of mechanical stresses and the possible hypothesis.
Abstract: The metabolic syndrome is a major health problem in western countries, due to the deleterious metabolic consequences of sedentarity and rich diet in the large part of the population who exhibits the so‐called “thrifty phenotype”. This syndrome, which is at high risk for diabetes and atherothrombosis is associated with hemorheologic abnormalities. Initially, insulin resistance was considered as the core of the syndrome. However, it becomes clear that the syndrome is a cluster in which the combined effects of obesity, insulin resistance, and hyperinsulinemia can be inconstantly associated. Thus, we investigated in 157 nondiabetic subjects (53 males and 104 females, age…35.6±1.1 yr, mean BMI 29.2±0.6 kg/m2 ) the respective importance of each of these factors. Subjects were divided in 6 groups according to BMI (cut‐off point 25 kg/m2 ) and insulin sensitivity (SI) measured with the minimal model (lowest quartile SI<1.1 min−1 /(μU/ml)·10−4 , highest quartile SI>9.5, middle zone between 1.1 and 9.5). Results show that whole blood viscosity at high shear rate is higher in obese subjects (p<0.01). Plasma viscosity is also higher in obese subjects 1.41±0.02 vs 1.34±0.012 (p<0.01), and, in addition, in lean subjects, is lower when SI is in the upper quartile. RBC rigidity index “Tk” is higher in obese subjects. A worsening effect of insulin resistance (SI<1.1) on Tk is found only in obese subjects. The aggregability index “M1” is increased when SI<1.1 in both obese and nonobese subjects. No clear effect of either SI or obesity on hematocrit is observed. On the whole, obesity and insulin resistance both impair blood rheology by acting on red cell rigidity and plasma viscosity. Whole blood viscosity at high shear rate reflects rather obesity than insulin resistance. Myrenne “M1” aggregation is rather a marker of hyperinsulinemia. Thus, the hemorheologic picture of the metabolic syndrome is far to be only a reflect of insulin resistance alone.