Clinical Hemorheology and Microcirculation - Volume 7, issue 2
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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: Red cell concentration is the main determinant of bulk blood viscosity. the evaluation of other determinants of blood rheology may require elimination of differences due to hematocrit alone. A simple and efficient procedure is described for calculating blood viscosity at a standard hematocrit, based on plasma viscosity, native sample hematocrit and whole blood viscosity at native hematocrit. The method considers individual variations of the viscosity – hematocrit relationship, as well as its dependence on shear rate.
Abstract: The investigation of erythrocyte deformability changes during cell ageing might give one insight on circulatory behaviour of young and old red blood cells. Erythrocytes of healthy subjects of both sexes had been separated into 3 fractions of increasing age on a Percoll discontinous density gradient and their different age has been tested by pyruvate kinase (PK) and glucose-6-phosphate dehydrogenase (G6PD) activities. Each fraction, free of leucocytes, suspended to 10% haematocrit, was filtered through Nuclepore filters 5 micron diameter; erythrocytes lying on filters were observed by Scanning Electron microscopy. Erythrocyte deformability has shown small decrease from middle aged cells…to old and youngest ones.
Abstract: The existence of changes in blood viscosity and filterability in some diseases supported several methods to wash red cells, hypothesizing that these modifications could be due mainly to red cells. In order to investigate these changes, washed red cells were studied in several diseases. Washed red cells were suspended to 10% haematocrit and filtered through Nucleopore filters 5 micron diameter; this study was meda in healthy subjects and in patients suffering from peripheral obliterative arterial disease, stroke, myocardial infarction and cancers; the same parameter was studied also in arterial and venous blood. The analysis of these data did not show…very significant differences between the healthy donors and each group of patients studied. On the basis of these results we could suppose that the various diseases really did not induce any change of the erythrocyte deformability and that the changes we see in whole blood filterability depends on other blood cells or components. On the contrary we can hypothesize that the washing technique by itself provokes a damage of the erythrocyte membrane; this damage may be so great as to inable us to detect a significant difference among the groups studied.
Abstract: Chronic occlusive arterial disease has been shown to be accompanied by blood hyperviscosity which is associated with increased plasma viscosity, red cell aggregation and red cell rigidity. There exists a linear correlation between fibrinogen and plasma viscosity and the flow behaviour of red cells meshed to each other by fibrinogen. Therapeutical decrease of the fibrinogen level aims at improving blood fluidity and increasing tissue perfusion by raising blood flow velocity in conjunction with an increase in red cell oxygen transport rate. Pharmacological approaches to realize this therapeutical principal are: fibrinolysis (streptokinase, urokinase, in myocardial infarction); defibrinogenation (ancrod, defibrase, in peripheral…vascular disease); anabolics (stanazol in Raynaud’s-Syndrome), lipid lowering drugs (clofibrate analogous in peripheral vascular disease), hemorheologically active drugs (pentoxifylline). Confirmed effects in respect of improvement of blood fluidity and tissue perfusion via fibrinogen reduction are at present only available for defibrinogenation by ancrod and by pentoxifylline.
Abstract: 25 patients with breast cancer after primary surgery and 10 patients with metastatic disease were investigated regarding hemorheological parameters such as erythrocyte aggregation, plasma viscosity, hematocrit and fibrinogen during chemotherapy with methotrexate, 5-fluorouracil and cyclophosphamide. Erythrocyte aggregation increased significantly during the first course of chemotherapy and remained elevated thereafter. There were no significant changes regarding the other parameters. The influence of tumor volume was much more important leading to significant differences between the two groups regarding erythrocyte aggregation, plasma viscosity and fibrinogen, while hematocrit and total protein concentration were not different.
Keywords: breast cancer, chemotherapy, hemorheology
Abstract: Particle migration induced by rheological mechanisms in a flowing suspension is studied. Most of this paper is devoted to calculate the migration force due to aggregation of the particles which form the bulk suspension. The last section deals with the effect of particles deformability on the margination phenomena. The mechanism of white blood cell margination and the following steps leading to emigration can be fully understood owing to our theoretical model. Theory is compared to experimental data obtained by P. GAEHTGENS and his group in blood perfused glass capillaries in which white blood cells adhesion does not occur.
Keywords: Suspension, particle migration, aggregation, white blood cells
Abstract: Deteriorated blood rheology has been demonstrated in obstetric diseases with decreased placental perfusion. Many of the patients investigated in these studies suffered from conditions associated with hemorheological abnormalities, such as diabetes or pre-eclampsy. Therefore it is difficult to establish the pathogenetic role of blood rheology in fetal growth retardation. In the present study placental perfusion and whole blood viscosity were measured in 26 pregnant women with intrauterine fetal growth retardation, without pre-eclampsy or other disease of the mother. These patients were compared to 20 controls with normal, uncomplicated pregnancy. Significantly higher whole blood viscosity accompanied with deteriorated placental perfusion was…found in the patient’s group. Results suggest a pathogenetic role of hyperviscostiy in cases of intrauterine growth retardation without pre-eclampsy.
Abstract: The technique of television microscopy has been applied to study human nailfold capillary blood flow in a variety of conditions that result in changes in blood rheological behaviour. The most striking changes were observed in leukaemia: in the presence of high total leucocyte counts stationary capillaries were frequently observed. A highly significant improvement in capillary flow velocity followed cytoreduction therapy. In contrast capillary flow velocity was normal at rest in patients with polycythaemia and was not altered following isovolaemic haemodilution. In patients with Waldenström’s macroglobulinaemia capillary flow tended to be lower than age matched control subjects but few stationary capillaries…were observed. Plasmapheresis in two subjects resulted in an improvement in capillary flow. These results emphasize the need to take into account the autoregulatory capacity of the microvasculature when extrapolating from the viscometer to the in vivo state.
Abstract: A new method of estimation of mechanical properties of erythrocytes is presented, based on the measurement of red cell susceptibility to centrifugal packing. Blood is spun in a microhematocrit centrifuge run at a voltage lowered to provide a rotation speed corresponding to 200 × g and apparent hematocrit is measured after 15-min centrifugation (Ha15 ). Then the centrifuge is run at a standard speed and the final hematocrit is read (Hk). The difference between these two values, denoted as Erythrocyte Packing Difference (EPD) is a measure of red cell susceptibility to centrifugal packing. EPD is independent of hematocrit in a…broad range of hematocrit values. A survey of a population of 489 healthy donors points to a significant sex difference in EPD which amounted to 10% ± 2% for males and 8.5% ± 2.5% for females. A decreased EPD was found in diabetes. EPD changes under conditions affecting red cell deformability. This simple and easily standarizable method of estimation of mechanical properties of unmanipulated erythrocytes is recommended for routine use.
Abstract: Hemoconcentration was induced by administration of oral Furosemide in a group of healthy athletes. Before and after this treatment a variety of hemorheological variables was measured. Simultaneously the time needed to reach the anaerobic threshold during a standardized ergometer test was recorded. The results show that the changes in blood rheology correlate with the changes in threshold – the more hemoconcentration, the more prolongation of the time to reach the threshold. This suggests that athletes may benefit in terms of performance by hemoconcentration. The findings support the hypothesis that the optimal hematocrit for oxygen transport rate is higher than normal…when average shear stress in the circulation is high such as in athletes. Conversely it may be lower than normal when shear stress is low like distal to a stenosis in occlusive arterial diseases.
Abstract: The effect of pentoxifylline (PTX) on red blood cell-endothelial cell adherence was studied for sickle and normal red blood cells (RBC). Human umbilical vein endothelial cells grown to confluence on glass slides formed the base of a parallel plate flow chamber into which RBC suspensions were perfused at a constant flow rate, producing a wall shear stress of 1 dyne/cm2 . RBC were incubated with PTX at 37°C for one hour at concentrations ranging from 0.1 to 10.0 mmol/L. Adhesion was monitored using video microscopy. The number of adherent RBC was determined at 10-minute intervals during a wash-out period which…followed a 10-minute perfusion of red cells. When compared with unincubated control RBC, the adherence of sickle RBC incubated with 0.1, 1.0 and 10.0 mmol/L of pentoxifylline was reduced to 65%, 53% and 39% of control values, respectively. There was no significant difference between the adherence of drug incubated and untreated normal RBC. These results indicate that pentoxifylline significantly affects the adhesion of sickle RBC to cultured human endothelial cells, but has no effect on the adherence of normal RBC.
Keywords: Pentoxifylline, sickle cells, endothelial cells, adherence, video microscopy
Abstract: The electrophoretic mobility of erythrocytes from patients with primary Raynaud’s phenomenon was measured in near physiological strength saline using laser Doppler microelectrophoresis and has been shown not to be significantly different from that of matched normal controls. It was found that washing the erythrocytes caused a significant, but small, increase in mobility of up to 3.5%. Two anticoagulation procedures, defibrination and heparinization, were compared and found not to affect measured mobility.