Clinical Hemorheology and Microcirculation - Volume 6, issue 5
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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: A macromodel (magnification 500x) was used to study the order of magnitude of the influence of wall-adhering white cells on the flow resistance in the microcirculation. Rigid spheres (diam. 4 mm), simulating white cells, were placed at different geometric combinations at the mid-section of a straight plexiglass tube (diam. 10 mm), which was perfused with fuel oil, 518 cP. Two vertical pipes on either side of the tube segment containing the spheres were used to record the pressure drop along the tube.Ten spheres in single file (7.5 em between the end spheres) increased the resistance by 70%, two rows (20…sph) by 130%,three rows (30 sph) by 180%, 20 spheres in 5 adjacent rings by 215% and four rows (40 sph ) by 430%. Translated to the microcirculation,these results indicate that wall-adhering white cells may significantly influence local blood flow and filtration equilibrium in inflammation and low flow states.
Keywords: white cells, wall adhesion, flow resistance
Abstract: The preparation of a leucocyte- and platelet-free red cell suspension produced by the use of high gradient magnetic separation (HGMS) is described. 0.5ml of whole blood is required for the production of 1.6 × 109 washed red cells and removal of 98.4% of leucocytes and 99.7% of platelets is achieved within 15 minutes. The technique also achieves a high degree of reproducibility. The red cells isolated are shown to be representative of the original population and show no preferential selection. High gradient magnetic separation represents an efficient, effective, yet simple method for the separation of erythrocytes from whole…blood.
Keywords: Rheology, Erythrocyte indices, Magnetic separation
Abstract: Sixteen patients with recent cerebral infarction have been studied. Ten of them under,’rent hemodilution by means of erythroapheresis and have shown an increase of cerebral blood flow (CBF) and of the arterial oxygen pressure (PaO2 ). The oxygen delivery capacity showed no significant variations. The hemorheological parameters have been improved without a significant correlation with CBF. Furthermore the treated patients have shown a better short term clinical outcome than the untreated patients. This finding seems to indicate that the rheology of the blood is an important factor in cerebral vascular disease and that its modifications may have a useful therapeutic…effect provided that all other determinants of CBF are not negatively modified.
Abstract: Filterability of whole blood and of washed erythrocytes has been studied in experimentally diabetic dogs, experimentally galactosemic dogs, and normal dogs. Whole blood from diabetic dogs kept in poor glycemic control was less filterable than that from normal dogs or dogs in good glycemic control. Whole blood from galactosemic dogs, in contrast, showed no abnormality in filterability, despite significantly higher erythrocyte polyol concentrations than found in diabetic or normal dogs. Washed erythrocytes were not abnormally filterable in any of the groups. Since experimentally galactosemic dogs, like diabetic dogs, develop a retinopathy that is morphologically comparable to that of diabetic patients,…these studies suggest that the retinopathy can develop in the absence of abnormal in vitro blood filterability.
Abstract: Whole blood apparent viscosity was measured at a shear rate of 135s−1 and 37°C, using a conicylindrical rotational viscometer. Multiparameter models were produced by multiple regression analysis of the relationship between measured viscosity and packed cell volume (PCV), plasma fibrinogen concentration and plasma viscosity. The best fit models included PCV and plasma viscosity but not fibrinogen concentration. The 95% confidence limits for the prediction of whole blood viscosity was c ± 21% for data having a wide range of PCV, (22%–77%), and was c ± 10% for data with a smaller PCV range (36% to 48.5%).
Abstract: A method of measuring the suspension stability of blood in vivo in large blood vessels of the limbs is described. The method is based on observation of the rate of increase of haematocrit resulting from settling of red cells under gravitational field in the vessels during temporary occlusion. The direction of settling may be centripetal from the microcirculation or centrifugal towards it, depending on the orientation of the limb. When centripetal, the rate of increase of haematocrit in an occluded large vessel of a limb provides a measure of the suspension stability of blood in that part of the microcirculation…in continuity with the vessel. The method was applied to measurement of centripetal settling from the microcirculation under differing flow velocities in it. The low settling velocity into a normal superficial vein of the forearm when the circulation in the limb was unrestricted was consistent with high suspension stability of blood in the microcirculation during normal flow. The high settling velocity into the vein and into the brachial artery during temporary arrest of the limb circulation was consistent with low suspension stability of blood in the microcirculation in stasis. When the method was applied to measurement of centripetal settling -into the varicose great saphenous vein in the thigh from the microcirculation in continuity with it, the circulation of the limb being unrestricted, a high settling velocity was observed. This finding was consistent with reduced suspension stability of blood in the microcirculation drained by varicose veins. Centrifugal settling in the unoccluded great saphenous vein in the leg and thigh during standing resulted in a small but statistically significant increase of haematocrit in it.
Abstract: This ICSH document proposes guidelines for rheological methods in clinical studies. These methods include the measurement of blood viscosity and erythrocyte deformability. The guidelines concern reference populations for clinical studies, standardization of the blood collection procedure, laboratory processing of blood samples, measurement of haematological indices on rheological samples, and the evaluation of rheological instruments and rheologically-active drugs. Adoption of these guidelines should improve comparability between rheological laboratories and increase the reliability of rheological tests.
Abstract: In the past there have been several meetings on white cell rheology. They were all centered on basic scientific problems and were mostly aimed at providing essential insights into the mechanical properties of white blood cells. However, knowledge has grown to a point where not only basic scientists but also clinicians have become interested. Hence the organizers felt that the time had come to sum up emerging clinical aspects of leukocyte rheology particularly in relation to microcirculatory ischaemia. The meeting was planned to stimulate discussion amongst scientists and clinicians involved in various fields of research, looking at white cells from…different points of view. Some of the basic facts that make leukocyte rheology a field of possible clinical importance are: – the internal viscosity of white cells is 2 orders of magnitude higher than that of red cells – consequently they deform much slower than red cells – even though outnumbered by red cells, they may be of equal or even greater importance for microcirculatory flow – they can be shown to block capillaries temporarily or permanently under certain conditions – they may be involved in so-called no-reflow phenomenon and play an important role in tissue ischemia – they apparently influence (exercise) hemodynamics in healthy subjects – epidemiological studies identify the white cell count as an independent primary cardiovascular risk factor – their mechanical behavior may be altered by drugs During the intense and fruitful discussions of the meeting a variety of problems were identified. To mention just a few: – What is the best method to isolate leukocytes from blood samples without interfering with their function? – Which tests are best suited to study their rheological behavior (filtration, aggregation, adhesion)? – In which clinical situation are the rheological characteristics of white cells abnormal? – What is the pathophysiological significance of this? – What are the influences of drugs? The multidisciplinary approach turned out to be helpful. There was a general consensus amongst the participants that much can be learnt from the juxtaposition of existing data from different fields. Clearly white cell rheology is a young field with many unanswered questions. At the same time is moving fast and of great potential importance for circulatory diseases. This is reflected in the following summaries of the meeting which we hope will be a stimulus to this most interesting new branch of hemorheology. the internal viscosity of white cells is 2 orders of magnitude higher than that of red cells consequently they deform much slower than red cells even though outnumbered by red cells, they may be of equal or even greater importance for microcirculatory flow they can be shown to block capillaries temporarily or permanently under certain conditions they may be involved in so-called no-reflow phenomenon and play an important role in tissue ischemia they apparently influence (exercise) hemodynamics in healthy subjects epidemiological studies identify the white cell count as an independent primary cardiovascular risk factor their mechanical behavior may be altered by drugs What is the best method to isolate leukocytes from blood samples without interfering with their function? Which tests are best suited to study their rheological behavior (filtration, aggregation, adhesion)? In which clinical situation are the rheological characteristics of white cells abnormal? What is the pathophysiological significance of this? What are the influences of drugs?
Keywords: White cell rheology, capillaries, hemodynamics