Biorheology - Volume 23, issue s1

Authors: Lorente, Paco | Azancot, Isaac | Masquet, Christiane | Adda, Jean-Luc | Saumont, Rémi | Slama, Robert

Article Type: Research Article

Abstract: Regional wall motion of the left ventricle (LV) has been analyzed from contrast ventriculograms by using 4 methods based on different geometrical frameworks. Two of them utilize moving internal reference systems, the center of mass (CMM) and the long axis (LAM) methods; the two other ones use fixed external reference systems, the area-based (ABM) and the Palo Alto (PAM) methods. The techniques were applied on a set of 81 patients: 42 were normal and composed the group I; 22 had a single vessel obstruction >75% of the left anterior descending coronary artery (group II) with old necrosis or active ischemia …of the LV anterior wall; 17 had a single vessel obstruction >75% of the right coronary artery (group III) with old necrosis or active ischemia of the LV inferior wall. ABM and PAM showed the highest specificities and sensitivities on the studied sample. Therefore, we believe these two methods, of the techniques tested, are the best to quantitate wall motion from cineangiograms. Show more

Keywords: Left ventricular wall motion, cineangiography, computer-based analysis methods

DOI: 10.3233/BIR-1984-23S131

Citation: Biorheology, vol. 23, no. s1, pp. 175-182, 1984

Authors: Geiger, D. | Trevisan, D. | Bercovy, M. | Oddou, C.

Article Type: Research Article

Abstract: Up to now, not so much attention has been paid concerning the dynamic rheological behaviour of soft tissues although non linear viscoelastic effects have often been reported when mechanical properties of biomaterials are concerned. In order to characterize such properties different rheological tests have been proposed, the two principal being the study of the sample stresses responses to applied strains which are either harmonic with time or of step function type. Two different apparatus have been designed in our laboratory which allow specific rheological tests on biological materials under controlled environmental conditions. With one of them, harmonic uniaxial extension …tests are performed in a large domain of frequencies (.001 Hz to 100 Hz) and forces (up to 20 daN); with the other, the samples are submitted to relaxation tests in uniaxial elongation up to 5 cm deformation within time duration of the order of 20 ms. The principal characteristics, limitations and performances of such apparatus are presented and few examples of data thus obtained are given. On the basis of quasi linear viscoelasticity models, it can be shown that both two types of tests with their proper limitations are leading to the same rheological parameters. Show more

Keywords: Mechanical properties, Viscoelasticity, Biomaterials, Ligaments

DOI: 10.3233/BIR-1984-23S133

Citation: Biorheology, vol. 23, no. s1, pp. 193-200, 1984

Authors: Ehrly, Albrecht M.

Article Type: Research Article

Keywords: tissue oxygen tension, intermittent claudication, hemorheologic drugs

DOI: 10.3233/BIR-1984-23S134

Citation: Biorheology, vol. 23, no. s1, pp. 201-207, 1984

Authors: Mihailova, A.P. | Petrov, N.K.

Article Type: Research Article

Abstract: A system of equations, describing the excitation-contraction coupling in cardiac muscle is obtained on the basis of a physiological model and of a thermodynamical one of a system with external control, the latter model being proposed by the authors. A single isometric contraction is modelled for latent, activation and relaxation periods. The obtained theoretical results coincide qualitatively with the experimental data.

Keywords: thermodynamic model, cardiac muscle tissue, excitation-contraction coupling

DOI: 10.3233/BIR-1984-23S135

Citation: Biorheology, vol. 23, no. s1, pp. 209-212, 1984

Authors: Kiesewetter, H. | Mrowietz, C. | Lazar, H. | Jung, F.

Article Type: Research Article

Abstract: We have developed a device for the determination of the minimum shear force necessary to maintain complete disaggregation of erythrocytes and to simultaneously determine the hematocrit of blood samples (red cells in autologous plasma). A functional relationship between this shear force and the hematocrit was determined. The first derivative of the (measured) γ Tmin as a function of the hematocrit was found to be identical (within limits) for all normal blood samples tested.

DOI: 10.3233/BIR-1984-23S136

Citation: Biorheology, vol. 23, no. s1, pp. 213-215, 1984

Authors: Ernst, E. | Magyarosy, I. | Roloff, Ch. | Drexel, H.

Article Type: Research Article

Abstract: A viscometric technique is outlined for the measurement of red cell aggregation (RCA). Samples are submitted to a constant shear rate of 2,4 s−1 . The resulting time dependent torque signal reaches a peak soon after starting the rotation and falls within seconds to a constant baseline, thereby describing an area “F” with the baseline. The shear history of the sample being strictly controlled, “F” is reproducible and shows a direct, positive correlation with RCA as determined for instance in the “aggregometer”.

Keywords: hemorheology, red cell aggregation, viscometry

DOI: 10.3233/BIR-1984-23S137

Citation: Biorheology, vol. 23, no. s1, pp. 217-219, 1984

Authors: Stoltz, J.F. | Gaillard, S. | Paulus, F. | Henri, O. | Dixneuf, P.

Article Type: Research Article

Abstract: 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. Show more

DOI: 10.3233/BIR-1984-23S138

Citation: Biorheology, vol. 23, no. s1, pp. 221-226, 1984

Authors: Braasch, A.

Article Type: Research Article

Abstract: Flow resistance of EDTA or defibrinized blood was measured in a vertical capillary viscometer. (Capillary I.D. = 0.3 mm, l = 475 mm, τ W = 0.27 to 0.036 Pa). With decreasing shear forces the apparent viscosity increased from 12 to 16 mPa·s, i.e. by about 30%. There was no significant difference in flow resistance between red cells suspended in plasma or serum. The apparent viscosity of the same blood sample increased from 14 to 45 mPa·s for RBC in plasma i.e. by about 320% if measured with a rotational viscometer. The attempt is made to explain this …difference in flow resistance with the different effect of shear resistant RBC-aggregates upon a parabolic streaming profile in a capillary, or upon the quasi linear profile within the annular Gap of a rotational viscometer. Show more

DOI: 10.3233/BIR-1984-23S139

Citation: Biorheology, vol. 23, no. s1, pp. 227-230, 1984

Authors: Roggenkamp, H.G. | Jung, F. | Schneider, R. | Kiesewetter, H.

Article Type: Research Article

Abstract: We present a device for the routine measurement of the deformability of individual red blood cells, the so called Single-Erythrocyte-Rigidometer (SER). The time required for individual erythrocytes to traverse a single pore membrane (pore diameter = 5 μ m, pore length = 25 μ m) is taken as an index of red cell deformability. For example we present the results from patients with insult, polyneuropathy and morbus binswanger. Compared to the results of erythrocytes of healthy probands a significantly increased rigidity of the RBC of the patients can be diagnosed.

Keywords: RBC-Deformability, Single-Erythrocyte-Rigidometer(SER, Single Pore

DOI: 10.3233/BIR-1984-23S141

Citation: Biorheology, vol. 23, no. s1, pp. 241-243, 1984

Authors: Seiffge, D.

Article Type: Research Article

Abstract: Employing the “Singlepore Erythrocyte Rigidometer” (SER) in which small pore diameters were used, significant differences were measured between red blood cells from adjuvant arthritic rats compared to control from non-diseased animals. The results changed to opposite values using higher pore diameters, which may be due to differences in cell “rigidity” and MCV.

Keywords: RBC-Deformability, Single Erythrocyte Rigidometer, Pore Geometry, Passage Time

DOI: 10.3233/BIR-1984-23S142

Citation: Biorheology, vol. 23, no. s1, pp. 245-247, 1984