[Hemorheology and hemodilution].
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Arterial Occlusive Diseases↗
Biomedical subjects
J F Stoltz
Publications and source records attributed to J F Stoltz.
[Diluted albumin-dextran 40 combination in treating arteriopathy of the lower extremities by normovolemic hemodilution. The rheological effects].
16 arteritic patients at stages II, III or IV according to Fontaine's ranking system were treated by normovolemic hemodilution (HDN). The procedure consisted of the daily withdrawal of 500 ml of blood, which was replaced by 250 ml of a 4% solution of human albumin and 250 ml of Dextran 40. The procedure was applied, on average, for three days in succession until the patient's hematocrit reached 0.30. The therapy was carried out over a total of 8 weeks in order to maintain hematocrit levels at between 0.30 and 0.35. Improvement was observed in clinical factors: a 100% increase in walking perimeter in stage II patients, disappearance of decubitus pain in stage III patients, wound healings in stage IV patients. The following rheological and platelet parameters were studied: plasma and blood viscosity with hematocrit level 0.40 and for seven speed of scissoring, red blood cell aggregation index, platelet aggregation, MDA platelet levels, plasma BTG. Clinical results revealed that by the 56th day of treatment, 8 patients had improved and 8 remained stationary (the condition of 3 of the "stationary" patients in fact worsened having evolved according to the normal development of arteritic disease). The improvements observed persist several months after normovolemic hemodilution has been discontinued, with the results for the longest studied patient going back as far as 15 months. With regard to the hemorheological parameters (which, on Day 0, are always disturbed), they tend to improve during the hospitalization period and stabilize at levels lying between the values measured on Day 0 and normal values.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Hemorrheological changes in 50 monoclonal dysglobulinemias treated by plasma exchange].
Rheological examinations were performed before and after plasma exchanges in 50 patients with monoclonal dysglobulinaemia. The parameters investigated were blood and plasma viscosity, erythrocyte filtrability, erythrocyte aggregation and kinetics of agglutination. The results showed reduction of blood and plasma viscosity and improvement in agglutination kinetics under plasma exchanges. Rheological examinations therefore seem to be useful to follow up blood disorders, notably the hyperviscosity syndrome. They can be performed prophylactically, leading to early plasma exchanges to prevent clinical deterioration.
Blood Viscosity↗
Effects of ketanserin on platelet function and red cell filterability in hypertension and peripheral vascular disease.
Serotonin is a vasoactive substance that acts on blood vessels and platelets but whose primary action lies in its role as an amplifier for other agents. The aim of this work was to study the effects on blood platelets and erythrocytes of the S2-serotonergic receptor antagonist ketanserin. Twenty-seven patients with untreated hypertension and/or intermittent claudication received a bolus intravenous (i.v.) injection of 10 mg ketanserin followed by 2 mg/h during 3 h i.v. infusion. Platelet function and erythrocyte filterability were studied before and 30 min, 3 h, and 24 h after the bolus injection. The results showed decreases of plasma beta-thromboglobulin and platelet factor 4 levels (p less than 0.001) and platelet aggregation induced by epinephrine plus serotonin (p less than 0.001), whereas ADP-induced aggregation remained unchanged 30 min and 3 h after ketanserin administration. Red cell filterability was decreased (p less than 0.01). There was a tendency toward lower mean arterial blood pressure but heart rate remained unchanged. The dual effect of ketanserin on platelet function and erythrocyte filterability might be of great clinical value in hypertension and peripheral vascular disease in which microcirculatory flow is altered.
Adult↗
Fluorescence polarization applied to cellular microrheology.
The fluorescence polarization of probe molecules gives information on the "fluidity" of probe environment. Although the data cannot be related with absolute values of microviscosity, the method is largely used for probing the "fluidity" of lipid regions of biological membranes. Therefore, fluorescence polarization is of interest in clinical research, for membrane alterations are associated with either pathological processes of red cells, platelets, leukocytes or important cell functions.
Blood Platelets↗
Comparative study on fluorescent probes distributed in human erythrocytes and platelets.
Important cellular functions, such as rheological properties of cells are presumably related to the membrane lipid fluidity which may be approached by the use of fluorescence polarization method. However, biological membranes represent very heterogeneous media and the knowledge of the fluidity of membrane compartments requires the use of different probes. Two fluorescent probes, DPH and its cationic derivative, TMA-DPH, have been employed to probe the lipid fluidity of human platelets and red cell membranes. The results show that the informations given by DPH and TMA-DPH can present important differences, suggesting that DPH and TMA-DPH are localized in different regions of cell membranes. In an attempt to investigate relations between lipid fluidity and rheological properties of red cells, the behavior of probes was studied in a "Couette" viscometer with a device for studying the emissive properties of probes when red cell membranes are under shear conditions.
Blood Platelets↗
Experimental investigation of the rheological activation of blood platelets.
In order to define various aspects of platelet rheological activation, samples of whole blood and platelet-rich plasma (PRP) from the same donors were subjected for 5 min to shear rates increasing from 10 to 10000 sec-1 (shear stresses from 10(-2) to 30 Pa approximatively) in a Couette type viscometer. The following parameters were measured: erythrocyte hemolysis; lactic dehydrogenase activity; plasma B-Thromboglobulin (B-TG); adenine nucleotides, and platelet photometric aggregation. The experimental results reveal that: In whole blood, hemolysis only reached at maximum 2% of the total hemolysis. Plasma LDH activity increased regularly beyond 500 sec-1, in close correlation with B-TG plasma concentration. In contrast, ADP and ATP levels remained stable up to 1000 sec-1 then increased slowly. In PRP, the LDH, ADP and ATP levels remain practically stable up to shear rates around 5000 sec-1. In contrast, B-TG appeared to be released in plasma at shear rate values of 3000 sec-1 and its progression is only correlated with the other parameters, when the platelet lysis occurred. Finally, a rapid and complete inhibition of platelet aggregation to ADP was observed from 5000 sec-1.
Adenosine Diphosphate↗
[Fundamental data in hemorheology. I. Parameters controlling the fundamental processes in hemorheology].
When attempting to apply rheological concepts to the problem of the circulation of blood, researches have often come up against the difficulties inherent in the fluid's specific properties and in the characteristics of blood flow. The concepts that have been fully proven in conventional fluid mechanics have often been applied too hastily to hemodynamics, without even ascertaining the validity of the original hypotheses. The following factors must be taken into account: the specific nature of the fluid (a concentrated cell suspension with complex rheological characteristic such as membrane viscoelasticity, large deformations and liable to undergo high interactions); the characteristics of the blood vessels deformability; the type of flow (essentially non-stationary).
Biomechanical Phenomena↗
[Fundamental data in hemorheology. II. Hyperviscosity syndromes].
Whole blood behaves like a deformable colloidal particle suspension in a macromolecular medium. Pathological variations in the rheological properties of blood and the clinical symptoms they produce form the "hyperviscosity syndromes". The term "hyperviscosity" was originally used for characterising the plasma hyperviscosity observed during macroglobulinemia and it is only recently that the chapter covering hyperviscosity syndromes has been enlarged to describe the syndromes as a state in which the increased blood viscosity and increase in flow resistance must be considered as the result of the rheological behaviour of blood taken as a whole (plasma and blood cells). The etiology of hyperviscosity syndromes can be: an increase in total plasma protein levels, or the appearance of a monoclonal protein, the increase in the number of blood cells, the increase in the erythrocyte's internal viscosity, the changes in the erythrocyte's viscoelastic properties, the excessive aggregating tendency of the erythrocytes and perhaps that of the platelets.
Arteriosclerosis↗
[Hemorheologic disorders in the threatened myocardial infarct syndrome].
Haemorrheological disturbances have already been described in ischaemic heart disease. However, it has not been established whether these changes are secondary to the ischaemia and/or myocardial infarction or whether they play a role in initiating or sustaining the haemodynamic abnormalities which cause infarction. We report our results observed in 14 patients aged 48 to 75 years admitted to the coronary care unit with a diagnosis of acute coronary insufficiency defined as typical persistent anginal pain resistant to glyceryl trinitrate associated with specific ECG changes (without pathological Q waves or increased serum CPK concentrations). Blood samples were obtained on admission for determination of: haematocrit, total blood viscosities at different levels of shear with the patients hematocrit and with corrected hematocrits, total blood filtrability, plasma viscosity and plasma albumin fraction. All patients received 800 mg lidocaine, 40 mg chlorezepate, adequate anticoagulant doses of heparin and a specific antianginal drug: amiodarone, nifedipine or diltiazem. Six patients had a favourable outcome and were discharged from the Coronary Care Unit without myocardial infarction (Group I); the remaining 8 patients (Group II) developed documented changes of myocardial infarction between the 12th and 4th day after admission (see the Table in the text). The haemorrheological parameters on admission of the two patients groups were compared. The abnormalities observed were significantly more severe in the group developing myocardial infarction. This suggests that these changes may play a major role in initiating conditions leading to myocardial necrosis. These observations confirm the results of other workers who have also shown a relationship between the severity of infarction and the incidence of haemodynamic complications and changes in blood viscosity and filtrability.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
[Deformability and aggregability of erythrocytes: significance in clinical biology].
In order to understand blood circulation, knowledge of the rheological properties of blood is required. However the characteristic parameters which must be considered differ according to the circulatory region investigated. A distinction must therefore be made between macrorheological parameters (viscosity, viscoelasticity) and the microrheological parameters (red blood cell deformability and aggregability). In this paper the main determinants of R.B.C. deformability and aggregability are discussed as well as the applications in clinical biology.
Arteriosclerosis↗
Hemorheological parameters in some vascular diseases.
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Blood Proteins↗
[Problems posed by the preparation of specific anti-cytomegalovirus immunoglobulins].
The authors describe the preparation of a first batch of intravenous cytomegalovirus (CMV) immune globulin at the Nancy Regional blood transfusion centre. Immune plasmas were selected from 3 640 healthy volunteer blood donors on the basis of CF antibody titers to CMV (Kolmer's method modified) of, at least, 1:8; plasmas from approximately 10% of the donors were therefore selected. The 68 liters of pooled immune plasma had à CF antibody titer of 1:16 (CMV antibody titers of 1: 10 000 and 1: 640 when tested in the ELISA assay and passive hemagglutination assay respectively). Intravenous immune globulin was produced from pooled plasma by Cohn fractionation and treatment with pepsin at pH 4; 4.8 liters of immune globulin were prepared and divided in 96 doses of 50 ml each. The final product was found to have a CMV antibody titer of 1: 32 (CF) 1: 50 000 (ELISA) or 1: 2 560 (passive hemagglutination). Recent reports on the preparation of CMV immune globulin are briefly reviewed.
Cytomegalovirus↗
Transient hemorheology in an air-bearing viscosimeter.
Blood suspensions have been studied by using an air-bearing viscosimeter which is driven by a rotating magnetic induction. Each transient motion (rise, relaxation with zero or intermittent field) can be considered as a quasi-static motion, from which the curve viscosity-shear gradient can be obtained. Combining several transient motions allows an easier determination of the parameters describing a non newtonian fluid like blood.
Blood Physiological Phenomena↗
Conception and realization of a new viscometer using a magnetic fluid for measuring biological fluids.
The viscometer described in this paper comprises a vertical cylinder containing the fluid to be tested and an inner, hollow cylinder floating in the fluid and filled with magnetic liquid. The magnetic liquid and inner cylinder are set in motion by applying a rotating magnetic field. Torque is balanced by the stresses in the fluid and the inertia of the rotating cylinder. The main characteristics of this new apparatus are: - possibility of applying various torques to the rotor. Measurements of angular velocity are made on the inner cylinder (in general, conventional viscometers are built on the opposite principle), - study in transient flow. Various measurements on Newtonian fluids (water, plasma, oils, etc.) and on blood suspensions have made it possible to improve the accuracy of the method.
Blood Viscosity↗
Some mathematical and numerical methods for determination of behaviour law of blood.
The determination of a constitutive law of a fluid, the red blood can be obtained by fitting the parameters of a theorical law with experimental results. For an experience, several expressions can be agreed, each of them explain a particular property. The aim of my purpose is to describe some mathematical and numerical methods, in relation with two experiences, able to give the value of an unknown quantity by computation and to fit it with measured quantity. The first method use finite element to modelize a couette nonlineer flow. It can be approach by a very simple model using only the computation of a nonlinear differential equation. The second use the perturbation method and the expansion in power serie.
Blood Physiological Phenomena↗
Experimental approach to rouleau formation. Comparison of three methods.
From a clinical point of view, the approach to erythrocyte aggregate or rouleau formation and cohesion is undeniably of great interest. A large number of methods have been suggested for studying this parameter such as: back-scattering of light, nephelometry, ultrasound, etc... In this paper the authors have compared three methods to approach rouleau formation: direct observation of rouleau formation (rheoscope); 'erythrocyte aggregometer': with this technique, the light transmitted by the sample is integrated over a period of time and provides an index (IA); laser reflectometer based on studying the light that is back-scattered by the blood sheared in the gap of a viscometer. The results show that the indexes measured by both reflexion and transmission vary according to hematocrit and reach a maximum value at hematocrit levels of between 30 and 40%. In contrast, observation using the rheoscope did not provide qualitative evidence of this phenomenon.
Blood Viscosity↗
Erythrometer: a new device for measuring erythrocyte filterability and plasma viscosity.
The Erythrometer is a new device capable of determining both red blood cell filterability and plasma viscosity. In the case of filterability measurements, a suspension of washed red blood cells is filtered at a steady flow rate through a 3 or 5 microns pore-diameter membrane. Pressure drop across the membrane is recorded and a red blood cell filterability index can be calculated according to the change in pressure. The authors describe the instrument's operating principle and performance and present some of the results obtained.
Blood Viscosity↗