Clinical Hemorheology and Microcirculation - Volume 9, issue 1
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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: Although red blood cell (RBC) aggregation remains an important issue in hemorheology, measurements of specific aggregation parameters are not usually performed routinely in many laboratories; this is primarily due to the present lack of appropriate instrumentation. We have thus developed an automated and interactive system, based on light transmission measurements using a modified Myrenne Aggregometer and a laboratory computer, which provides rapid and routine determination of seven RBC aggregation indices. The computerized system allows control of shear rate as well as recording and analysis of digitized light transmission data. Aggregation indices measured with this system include: 1) extent of aggregation…at stasis (AI, AMP); 2) kinetics of aggregate formation (T1/2 , TFAST , TSLOW ); 3) shear resistance of RBC aggregates (YTmin ); 4) aggregate formation induced by low shear (FSAR). Results obtained for RBC/plasma suspensions indicated appropriate reproducibility, several cross-correlations between the indices (except between AI versus TFAST or TSLOW ), that fibrinogen affected all indices, and that donor age markedly influences aggregation behavior. Dextran suspending media demonstrated the expected biphasic aggregation response of this polymer. RBC modified by heat treatment or by shape altering agents exhibited changes versus control, and age fractionated red cells demonstrated marked differences in aggregation behavior. In overview, the results indicate the necessity to determine more than one parameter to fully describe the aggregation process, and suggest the usefulness of this newly developed system for both routine clinical studies and basic research investigations.
Abstract: Red cell deformability is a widely accepted term to indicate a property of erythrocytes to adapt their shape to the forces acting in blood circulation. The concept of cell deformability is easy to understand, but it is very hard to evaluate in a numerical way. Several techniques have been proposed but, at present, none can express this biological property with absolute values. Important problems are not yet solvable. The studies in whole blood are influenced by the presence of leucocytes and platelets, and all the procedures which tend to isolate the erythrocytes transform the measurements into technical artifacts. The experience…we have had with some new sophysticated and expensive devices has suggested we should not abandon whole blood filtration which, with important but simple technical improvements, remains a method able to value “whole blood filterability’, which is a parameter only partly correlable to “red cell deformability” and not identifiable with it. So, while clinicians need new effected method from biorheologists, the only possible approach to red cell deformability in clinical hemorheology is by means of the interpretation of a pattern of different measurements (blood and plasma viscosity, whole blood filterability, hematocrit, fibrinogen concentration, leucocyte and platelet number and activity).
Keywords: Hemorheology, red cell deformability, whole blood filterability, washed red cell filterability
Abstract: On the basis of several thousands of parallel measurements of the viscosity of human blood plasma and the Erythrocyte Sedimentation Rate (ESR) as indices of the presence and severity of certain diseases it is concluded that there is no aspect, technical and clinical, in which the plasma viscosity test is not superior.
Abstract: A comparison has been made of the response of the Myrenne Erythrocyte Aggregometer (MEA) with fibrinogeo concentration, low shear rate viscometry and the ESR used as indices of red cell aggregating potential of samples of normal blood. A good linear correlation has been found between the response of the MEA and each of the other indices in these circumstances. It is concluded that because of this correlation, combined with its ease and speed of use, it is a valuable instrument for the quantitation of erythrocyte aggregation.
Abstract: Fluorescence polarization was used to investigate possible modifications of the fluidity and order in lymphocytes membranes from 19 patients treated with pentoxifylline (800 mg/day). We only studied patients with an atherosclerosis obliterans stage II (according Fontaines’ classification) having received the drug (pentoxifylline) for 10 days. Anisotropy fluorescence (AF) was measured before and after treatment for each patient using the classical fluorescence probe : 1,6- Diphenyl- 1,3,5- Hexatriene (DPH) and the TNBS-DPH quenching method for membrane resolution. Lymphocytes with high values of AF>1.95 (and hence high viscosity) were noticeably modified after the treatment. No similar modifications were observed in cells with…original values within the normal range. In these conditions pentoxifylline seems to act only on the perturbated lymphocyte membrane and do not modify the normal membrane. This could be of interest the modulation and restauration of some immunological properties of membrane properties under the lymphocyte membrane fluidity dependence.
Abstract: Although previous reports have indicated that catecholamines can produce changes in RBC flow behavior, RBC microrheologic studies with these agents appear to be limited. The present study was therefore designed to evaluate the effects of both an alpha-stimulator norepinephrine (NE) and a beta-stimulator isoprenaline (IP) on RBC deformation in defined shear fields as well as on RBC filterability under pathologic conditions. Various concentrations of NE and IP (10-4M - 10-9M) were added to fresh human RBC suspended in isotonic phosphate or HEPES buffered saline at physiologic pH and the cells incubated for 30 min at room temperature. RBC deformation measurements…were carried out in a counter-rotating rheoscope over a shear stress range of .25 – 50 Pa. RBC filterability (5 µm pores, 10% Hct) was investigated at physiologic pH and under pathologic conditions using the following stress models: a) pH = 7.0; b) increased external calcium concentration (pH = 7.4, 9 mM Ca); c) 9mM Ca plus ATP depletion via 2-deoxyglucose. In the rheoscope, RBC incubated with 10-5M NE showed a decrease in cell deformation at low shear stresses and a decrease over the entire shear stress range was found after incubation with 10-4 M NE. IP at 10-4 and 10-5 M did not alter cell deformation at pH = 7.4, whereas lower IP concentrations (10-7 M and 10-9 M) lead to an increase in cell deformation at the lowest shear stresses. Compared to the filterability of controls at pH 7.4, RBC filterability was decreased in all stress situations. Increasing NE concentrations significantly worsened the reduction in cell filterability in the stress models, while the effects of IP were more variable: with IP, either there was no change in filterability or small but significant increases. Our results suggest that NE, an alpha-receptor agonist, may negatively alter RBC flow properties in regions of high NE concentrations (i.e. local areas of infarcted myocardium), whereas beta-receptor-agonists, such as IP, could be beneficial to blood flow in low concentrations.
Abstract: Granulocyte rigidity was estimated from the pressure-time curves generated by constant flow through Hemafil filters. The curves were used to deduce β , a factor relating the flow resistance presented by a cell to that of suspending medium. The cells were prepared in two buffer systems, one which allowed partial stimulation as evidenced by pseudopod formation and one which did not. β for cells activated by buffer alone was twice that of resting (pseudopod-free) cells, while activation of resting cells by FMLP at 10 − 7 M raised β ten-fold. In 10 mM…pentoxifylline (PTX) β of buffer- or FMLP-activated cells fell to a level similar to that of resting cells, but PTX had no effect on resting cells. Cytochalasin B (CB) lowered β more than PTX. The effect of other methylxanthines (HWA 285 and HWA 448) was similar to PTX. β was found to be shear stress dependent, and differences between activated and PTX-treated cells were magnified at lower pressures. The behavior of granulocytes in this simple model system suggests that activation might lead to significant increases in the precapillary resistance, and that treatment with pharmacological agents might prevent this.
Abstract: Twelve patients with Familial Hypercholesterolemia (FH) have been treated by LDL-apheresis,a method for selective removal of apolipoprotein-B containing lipoproteins by adsorption on dextrane sulphate columns. Mean plasma cholesterol reduction after treatment was 57% (p<0.001),due to LDL decrease.High density lipoprotein (HDI.) cholesterol was decreased by 16%. Blood and plasma viscosity were assessed before and seven days after the treatment: blood viscosity was reduced by 26.8% (p<0.005) at shear rate 11.25 sec-1,as well as by 11.7% (p<0.005) at 450 sec-I. Hematocrit was 37.0 before and 35.9 seven days later. No statistically significant difference was observed for plasma viscosity. Relative blood viscosity (blood/…plasma viscosity ratio) was significantly (p<0.05) decreased at high shear rates, suggesting that removal of LDL improves red cell deformability.
Abstract: It is known that some authors found an impairment of hemorheological characteristics in essential hypertension, related to an increased relative apparent blood viscosity and to a decreased red blood cell filterability. This latter seems to be related to a defect of transmembranary ions transport systems so that erythrocyte membrane flexibility may be reduced. It is reported that the Na/K cotransport system is impaired in several tissues of essential hypertensive patients, such as red blood cells. The aim of this work was to study filterability of washed and resuspended red blood cells by means of an erythrocyte filtrometer MF4, before and…after furosemide challenge, this latter employed as a Na/K cotransport blocker. Basal filterability indices of hypertensive patients were impaired. in respect to normal controls, likely confirming a decreased red cells deformability. After furosemide addition, filterability indices of normal controls resulted impaired in respect to basal values, meanwhile parameters of hypertensives were unchanged. These findings seem to support the hypothesis of a genetically impaired Na/K cotransport system in essential hypertensive patients.