Clinical Hemorheology and Microcirculation - Volume 9, issue 6
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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: The Capillary-Rigidometer allows to obtain time-saving information about the distribution of a large number of single RBC within a cell population. The measuring principle consists in observing the entry process of a single RBC into a glass capillary (inner diameter: 3.5 – 4.0 μ m) by recording the conductivity changes of the micropipette and analysing with a microcomputer the time dependence of the conductivity change of the micropipette. The influence of methodical parameters (like geometry of the glass capillary, sucking pressure) as well as results concerning experimentally altered RBC by heat treatment are briefly described and give evidence that the…parameters entry time te , passage time tp and amplitude A, derived from impulse-like changes of conductivity describe the deformability of an individual erythrocyte. Compared with parameters of RBC of healthy persons, those of patients with cIHD are significantly changed. Blood samples taken from the coronary sinus and from the left heart ventricle differ significantly in their values of amplitude. There are also differences of the obtained deformability parameters between cIHD with and without an increase of the left heart ventricular mass.
Abstract: Erythrocyte deformability (filterability) as measured by the Cell Transit Analyser was studied in the presence and absence of contaminating leucocytes and platelets. The effects of two anticoagulants (lithium heparin and K2 EDTA), no anticoagulant (defibrinated blood) and two buffers (HEPES and phosphate) were also evaluated. Erythrocyte transit time was unaffected by contaminating leucocytes (range 0–78.6 × 109 /l) but was influenced slightly by the presence of platelets. False rapid transit times were obtained using EDTA anticoagulant and/or phosphate buffer which may in part be a consequence of calcium removal from the erythrocyte membrane. The combination of lithium heparin anticoagulant…and HEPES buffered saline gave optimal transit times for human erythrocytes.
Abstract: The cell-age associated acceleration of erythrocyte aggregation at low shear rate was proved with a rheoscope (composed of a cone-plate viscometer and an inverted microscope), combined with a video camera, an image analyzer and a computer. Human erythrocytes were fractionated by density gradient centrifugation with Percoll. Compared with the low-density erythrocytes (4.0–6.6 % of total erythrocytes, presumably rich in young erythrocytes), the high-density erythrocytes (5.0–6.7 %, rich in aged erythrocytes) were characterized by (1) high velocity of erythrocyte aggregation at low shear rate (7.5 s−1 ) in diluted plasma and in medium containing fibrinogen and albumin, (2) decrease of…cellular deformability at high shear stress (10–98 dyn/cm2 ) (3) small cell volume, and (4) low content of sialic acid with no alteration of electrophoretic mobility. The mechanism and the physiological meaning of increased erythrocyte aggregation of aged erythrocytes are discussed.
Keywords: Human erythrocytes, Erythrocyte aggregation, Aging, Fibrinogen
Abstract: Several rheological variables were examined in 15 patients with stable or unstable angina pectoris and a prior history of myocardial infarction (MI); the mean time since MI was 42.1 ± 70.9 months (range = 2–263 months, median = 10.2 months). Rheologic parameters measured included: hematocrit, whole blood viscosity (750 and 1500 s−1 ), plasma viscosity, degree of RBC aggregation (ZSR), extent and rate of RBC aggregation following stasis (Myrenne Aggregometer). Compared to normal control donors, the pooled patient data indicated: 1) no significant difference in hematocrit; 2) a significant increase of plasma viscosity (13%); 3) significant increases in blood viscosity…at both shear rates (13% and 17%, respectively); 4) significant increases in the degree (23%), the extent (27%) and the rate (33% faster time constant) of RBC aggregation; 5) significant elevations of gamma globulin (51%), fibrinogen (46%) and alpha-2 (25%) concentrations which correlated with the enhanced RBC aggregation; 6) no significant correlations between either the rheologic or hematologic parameters and the time since MI. Rheologic abnormalities were evident when patients with stable or unstable angina were compared with controls, but only plasma viscosity and RBC aggregation time constant differed between the subgroups. Post-MI patients with angina pectoris thus exhibit marked rheological abnormalities which are compatible with altered blood flow dynamics and which represent potential risk factors for further circulatory complications.
Abstract: RBC aggregation indices and blood viscoelasticity, at a hematocrit of 40%, were determined in 40 poorly controlled, hyperglycemic (serum glucose ≥ 21 mmol/l) Type 2 (NIDDM) diabetic patients and in 40 age-matched control subjects. Aggregation parameters were measured by a Myrenne Aggregometer and by the Zeta Sedimentation Ratio, and viscoelasticity via an OCRD viscometer. Compared to the control subjects, the patient data indicated: 1) a faster rate of RBC aggregation at stasis (33%, p<0.001); 2) higher shear rates (45%, p<0.001) and shear stresses (77%, p<0.001) for dispersion of RBC aggregates; 3) enhanced RBC aggregation at 10 s−1 (9%, p<0.001);…4) an elevated Zeta Sedimentation Ratio (19%, p<0.001); 5) higher viscous and elastic components of the complex viscosity (at 10 s−1 , 7% for viscous and 30% for elastic, p<0.005). Plasma fibrinogen levels (N=16) were significantly greater than control (46%, p<0.005) and correlated with the Zeta Sedimentation Ratio (p<) and the rate of aggregation (p<0.01). However, neither serum glucose, percent HbA1 for a 12 patient subgroup, nor duration of the disease were found to significantly (p>0.2) influence either any of the aggregation indices or the two viscoelastic components. Correlations between blood viscoelasticity and the aggregation parameters could be demonstrated and the specific measures of RBC aggregation also exhibited cross correlations. Our results show that both RBC aggregation and blood viscoelasticity are markedly abnormal in hyperglycemic Type 2 diabetics and suggest that altered in vivo blood flow dynamics should be present in these individuals.
Abstract: 18 healthy untrained children (13 boys, 5 girls) performed a 15 min submaximal incremental exercise on cycloergometer rising heart rate (HR) up to a final step (5min) at 90% of theoretical maximal heart rate. Whole blood viscosity (at high shear rate), plasma viscosity and hematocrit increased after exercise (p < 0.01). The index of fitness Ẇ 170 was negatively correlated with blood viscosity at rest (r = 0.752, p < 0.001). Plasma viscosity and hematocrit were also correlated with Ẇ 170 while relative blood viscosity at corrected hematocrit 45% did not show such a correlation. Therefore (a) exercising children undergo…the same hemorheologic modification as adults; (b) Ẇ 170, a very classical index of fitness, is strongly related to blood fluidity; (c) the viscosity of blood at very high shear rate (i.e. reflecting the newtonian behavior of blood) is correlated with fitness; (c) the factors of blood viscosity involved in this relationship appear to be plasma viscosity and hematocrit rather than red cell flexibility.
Keywords: blood viscosity, hematocrit, fitness, exercise, hemorheology, children
Abstract: A double-blind trial was conducted among 41 diabetics with peripheral occlusive angiopathy to evaluate the effectiveness of Chinoin on blood rheology abnormalities. A significant improvement in whole blood filterability was obtained in a hypercholesterolaemic subgroup of these patients following 6 months of Chinoin treatment. These changes were probably due to the drug induced reduction in serum cholesterol and protein levels. The leucocyte counts in this subgroup did not undergo significant changes. The results obtained indicate that Chinoin may at least in part reduce blood rheology abnormalities in vasculopathy of diabetics.
Abstract: The effect of BMY-20014 and pentoxifylline on the filtration characteristics of a suspension of washed human neutrophils and red blood cells was determined. A mixture of red cells (10 % hematocrit) and neutrophils (300/µl) was pumped through 3 µ Nuclepore filters at a rate of 1 ml/min and the filtration pressure monitored. Neither compound affected the initial filtration pressure, indicating that they did not affect red cell deformability. In contrast, both drugs significantly reduced the pressure reached after 1 min of filtration, pentoxifylline at 100 µg/ml and BMY-20014 at 0.1 µg/ml, suggesting a deformability-increasing effect on the neutrophils. Because vascular…plugging by neutrophils is now considered to be an integral part of the etiology of ischemic tissue damage, such activity should be beneficial in the treatment of ischemic diseases.
Abstract: Obesity has been shown to be associated with disturbed hemorheological parameters. We investigated whether these abnormalities could be reversed by weight reduction. Therefore we evaluated blood viscosity parameters of 20 obese women before and after weight loss, achieved after 6 months of a hypocaloric diet (1000 kcal/day). Before dieting the obese women showed an increase of whole blood, plasma and erythrocyte viscosity and plasma fibrinogen when compared with controls. After 6 months of diet whole blood and erythrocyte viscosity values were decreased compared to the starting levels. There was no effect of weight reduction on haematocrit and plasma fibrinogen. After…weight loss most hemorheological parameters were improved in the obese women. Only low shear whole blood viscosity, reflecting erythrocyte aggregation, remained abnormal, due to persistingly increased fibrinogen levels.
Abstract: Blood from patients with diabetes has been found in many studies to offer more resistance to flow at low shear rate than blood from healthy subjects. Such shear-thinning has been proposed to decrease the stability of high Reynold’s non-Newtonian fluid flow. Flow destabilization could affect arterial flow patterns. Because of this possibility, diabetic and nondiabetic blood were compared for flow stability. When the inner cylinder of a Couette system (viscometer) is rotated rapidly, pairs of counter-rotating toroidal vortices develop at a critical rotation rate, as shown by Taylor. Newtonian fluid Taylor-Couette instability is very regular in onset compared to turbulence…in pipe flow, making it convenient for evaluating the flow stability of non-Newtonian fluids. The critical Taylor number (Tc ) of blood was determined in our Couette viscometer following shear-thinning assessment. Tc of blood from 88 diabetic and 100 nondiabetic subjects was measured using a computer-automated determination of torque inflection. Blood’s steady flow viscosity was measured at 25 rotation rates from .03 to 360 sec−1 . Low shear rate viscosity elevation in diabetes was again demonstrated, but Tc and the ratio in rotation rate to Tc at which wavy vortices first formed were highly comparable, Tc differing by 0.3% between the groups. A previously published technique for adjusting for variation in hematocrit was examined and found more useful for healthy than diabetic blood. Diabetes has no effect on blood’s essentially normal flow stability even though it alters its shear-thinning and viscoelastic behavior.
Abstract: The focus of this paper is mainly directed on the role that the structural and functional perturbations of the erythrocyte membranes could have in the incidence of abnormal microcirculation which occur with the elderly. Rheological parameters of whole blood and the activity of some enzymes involved in erythrocyte metabolism and permeability are studied.
Abstract: The KCl-cotransport pathway in the membrane of normal human red cells was activated by incubation with the SH-group reagent N-ethylmaleimide. Activation of the pathway caused progressive efflux of cell K+ over 120 min with significant loss of red cell filterability through pores of 5 µm diameter. When the pathway was activated in sickle cells, by incubation at pH 6.8 for 30 min, there was again a significant loss of filterability in excess of that caused by enhanced polymerization of sickle haemoglobin at low pH. Activation of the KCl-cotransport pathway in vivo is therefore a potentially important cause of…dehydration and rheological impairment of sickle cells. Its activation in vitro is a useful new method for investigating the rheological effects of putative anti-sickling compounds, including specific inhibitors of the KCl-cotransporter.
Abstract: A recently recommended method supposedly estimating the mechanical properties of unmanipulated erythrocytes, was tested in our laboratory in various groups of subjects. Blood was spun for 15 minutes at 200×G (Ha15) and for 5 minutes at 12000×G (Ht). The difference between the obtained hematocrit values Ha15 and Ht, the “erythrocyte packing difference” (EPD), was expressed as a percentage of the hematocrit Ht (%EPD=[(Ha15–Ht)/Ht]× 100). Fifty-two healthy volunteers (N), thirty-seven diabetics (DM) and thirty-five patients with intermittent claudication (IC) were tested. No differences in EPD could be found between N and DM (N: %EPD=23.7±3.1%, DM: %EPD=22.9±3.1%, mean ± SD). In…the IC-group EPD was significantly lower compared to both other groups (IC: %EPD=16.2±2.6%, p < 0.01 vs N and vs DM). The EPD and %EPD in the IC-group correlated inversely with plasma fibrinogen concentration (r = −0.710, p < 0.001 and r = −.0784, p < 0.001, respectively) and with plasma viscosity (r = −.0694, p < 0.001 and r = −0.781, p < 0.001, respectively). We therefore suggest that the EPD is not a method which can be recommended for routine use as a measure for mechanical properties of erythrocytes. Plasma properties (plasma viscosity and plasma fibrinogen concentration) do appear to play a major role in the EPD. Thus, it might be possible that the EPD is more a measure of alterations in plasma viscosity c.q. fibrinogen concentration than of changes in intrinsic erythrocyte deformability.
Abstract: The following five Abstracts were obtained by H. Landgraf, Secretary-Treasurer of the Organizing Committee, too late for inclusion in the issue of the Conference Abstracts, Volume 9, Number 3 of CLINICAL HEMORHEOLOGY. They, therefore, are included in this issue.