Clinical Hemorheology and Microcirculation - Volume 6, 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: Erythrocyte deformability was studied by filtration through silver membranes (nominal 5 µm diameter channels) and by laser diffractometry (Ektacytometer) in 30 non-dialysed patients with chronic renal failure (CRF) compared with 30 matched healthy controls. Patients with CRF showed impaired erythrocyte filterability, which correlated with the degree of renal failure, and a left shift of the Ektacytometer osmotic deformability profile in favour of lower osmolality. Subsequent analysis of 20 patients undergoing regular haemodialysis and 23 patients undergoing continuous ambulatory peritoneal dialysis showed, compared with matched controls, a complete or partial correction of the rheological abnormality. Impaired deformability may contribute to the…shortened erythrocyte survival of patients with CRF.
Abstract: The effect of some plasma expanders (dextran 40, polygeline, succinyl-gelatin) currently used for normovolernic hemodilution (NHD) and of isotonic saline on erythrocyte deformability was tested by a whole blood filtration technique in vitro and ex vivo after NHD. Dextran 40 resulted able to improve erythrocyte filtrability ex vivo but not in vitro . Gelatine derivatives did not change ex vivo and worsened in vitro erythrocyte filtration rate. Hyperosmolarity was a major determinant of the negative influence exerted by plasma expanders on erythrocyte flexibility in vitro .
Abstract: A comparison has been made between the new laser diffraction technique and the well known method of erythrocyte filterability for the determination of erythrocyte deformability. A hyperbolic correlation has been found between deformation index and filtration time. This correlation becomes linear by inversing the deformation index. Our results demonstrate that filterability (filtration time method) selects the more deformable cells from the whole population. In this way, statistic tests have demonstrated that filtered cells are more deformable than cells retained above the filter at 95% confidence level.
Abstract: Decreased perfusion of the microcirculation underlies the pathophysiology of cryoglobulinemia. Reduced temperature initiates cryoaggregate assembly. Perfusion of the microcirculation is diminished with increasing size of the cryoaggregate. Flow properties of both cryoglobulinemic plasma and solutions of highly purified cryoglobulin derived from a patient with Waldenstrom’s macroglobulinemia are highly dependent on both temperature and shear rate. At low temperature, cryoaggregates can be disrupted by low shear. However, at low temperature and shear rates above 200 sec−1 , shear dependent increases in viscosity occurs. Both fibrinogen and D-penicillamine inhibit cryoaggregate formation. The role of cryoaggregation in microcirculation ischemia is presented.
Abstract: A method has been developed for studying blood viscosity at shear rates from 4·10−2 to 7·102 sec−1 i.e., in the shear range in which the influence of shear rate on viscosity is greatest. Blood viscosity is expressed by the two regression coefficients of a power regression, according to the equation: η = a · D b in which η is viscosity, D is the shear rate, a and b are the two regression coefficients, which are independent of the shear rate.…We found that the power regression gives a good fit of the experimental data over a wide range of hematocrit. We also found significant correlations between the two regression coefficients and hematocrit and plasma viscosity, thus making it possible to correct the two regression coefficients for standard hematocrit and standard plasma viscosity. This method is simple, highly reproducible, and can easily be automatically performed by using a computer.
Abstract: To test the hypothesis that lowering the haemoglobin concentration pre-operatively improves wound healing 52 Wistar rats were randomly allocated into two groups: group ‘A’ were haemodiluted pre-operatively by ten per cent of their blood volume; group ‘B’ were untreated controls. All rats were subject to laparotomy and one leg rendered ischaemic. Two 2 centimetre long full thickness skin incisions were made in each leg and sutured. At seven days the wound strengths were measured by tensometry and quantitative wound collagen content was performed. A second experiment was performed employing 28 rats allocated into two similar groups. In this experiment the…study group were repeatedly diluted on alternate post-operative days whereas controls were sham diluted. The experiments were otherwise identical. Compared with controls, haemodilution did not improve wound strength in non-ischaemic limbs but did improve wound strenth in ischaemic limbs in experiment two (p ⩽ 0.001).
Abstract: Eleven patients suffering from pressure sores were compared to eleven matched controls, free of this complication. Blood rheology was quantified by means of blood viscosity, plasma viscosity, hematocrit, total white blood cell count, blood cell filterability and red cell aggregation. Results show that native blood viscosity is reduced in pressure sore patients due to significantly lower hematocrit levels. The total white cell count is significantly elevated in this group. Other rheological parameters reveal no significant difference compared to controls. It is concluded that bulk blood viscosity seems not to contribute to the malfunction of the skin microcirculation in pressure sores.…However, white cells might play an unrecognized role, which merits further investigation.
Abstract: Haemorheologic investigations were performed on 25 essential and 8 secondary hypertensive patients as well as in 8 normotensive subjects with positive family history for essential hypertension. 20 normal subjects also entered this study as control group. Whole blood viscosity was increased in all hypertensive patients both at low and high shear rates. The increase of erythrocyte aggregation was more significant in essential than in secondary hypertensives in respect to normal subjects. On the contrary, blood filterability was reduced in all hypertensive patients. After challenge with furosemide, employed as a blocker of red cell membrane Na/K cotransport system, filterability index appeared…to be reduced in secondary hypertensives and not significantly decreased in essential hypertensive patients. Normotensive subjects with positive family history for essential hypertension showed a decreased blood filterability, poorly influenced by challenge with furosemide. These findings support the hypothesis that Na/K cotransport system is genetically impaired in essential hypertensive patients and in normotensives with positive family history for essential hypertension.
Keywords: filterability, red blood cell, cation fluxes, hypertension
Abstract: A new instrument (Radial Spreading Rheometer) has been deve loped to measure the radial spreading time of a concentrated washed erythrocyte suspension through a horizontally suspended filter paper. A calibration time (CT) for radial spreading of buffer was used to calibrate individual filter papers. The radial spreading time (RST) for washed erythrocytes was then expressed as the ratio RST/CT and adjusted to a standard packed cell volume of 0.50 (50%). The ratio RST/CT was independent of (a) temperature within the range 20–35°C, (b) leucocyte count up to 5.0 × 109 /l, and (c) platelet count up to 76 × 109…/l. The ratio RST/CT correlated significantly (r = 0.418, P < 0.05) with erythrocyte mean cell haemoglobin concentration but not with mean cell volume. Radial spreading rheometry is a low-cost technique for measuring erythrocyte deformability by bulk flow of a concentrated cell suspension through the wide channels of paper filters.
Abstract: Four rheological instruments for measuring erythrocyte deformability have been compared. Erythrocyte filterability was measured by a Hemorheometre and a St. George’s Filtrometer, erythrocyte viscosity by a Contraves LS 30 rotational viscometer, and erythrocyte radial spreading in filter paper by a Radial Spreading Rheometer. Each instrument showed adequate reproducibility, giving coefficients of variation for 10 replicate samples of < 5.5%. As in the case of other filtration instruments, the St. George’s Filtrometer was sensitive to leucocyte contamination of the erythrocyte suspension. When leucocyte-depleted erythrocytes were manipulated in vitro to give an incremental loss of deformability ranging from < 10% to >…100%, the St. George’s Filtrometer was found to be the most sensitive of the four instruments in six of eight test models. The different relative sensitivities of these instruments should now be evaluated in clinical studies.
Abstract: A viscometric study of blood from insulin-treated diabetics separated into three clini.cal groups (without retinopathy, with minimal retinopathy and with moderate or severe retinopathy) has been carried on. Among the studied viscometric parameters, three of them, relative to red blood cells (RBC) aggregation, have been found to be more modified in patients with retinopathy than in those without. The results involve (i) a more difficult break off of the blood structure, (ii) a more rigid network structure, (iii) a strong trouble of the rouleaux disaggregation process. These modifications are found closely linked to plasmatic disorders. Furthermore, the deformability of diabetic…RBC, evaluated by viscometry is found decreased.
Abstract: This paper reports on a new microscopic method for measuring the deformability of erythrocytes. A 0.3 ml specimen of capillary blood was washed and a portion of the erythrocyte suspension was placed on a microscope slide. After sedimentation the erythrocytes adhered to the glass surface as a monolayer. The slide was placed in a flow chamber and the adhered erythrocytes were deformed due to the shear force caused by the introduction of a transverse flow. During deformation transmission of monochromatic light and length to width ratio of the deformed cells were measured. There was a positive relationship between light transmission…and erythrocyte shape change. This new method was tested by measuring the effect of changes in shear stress, pH and osmotic pressure on erythrocyte deformability. It was concluded that this method is adequately sensitive to measure the influence of low shear stresses and variation of pH and osmotic pressure on the deformability of erythrocytes and was not influenced by the presence of white cells or platelets.