Biorheology - Volume 33, issue 6

Article Type: Other

DOI: 10.3233/BIR-1996-33610

Citation: Biorheology, vol. 33, no. 6, pp. III-VIII, 1996

Authors: Goldsmith, Harry

Article Type: Editorial

DOI: 10.3233/BIR-1996-33601

Citation: Biorheology, vol. 33, no. 6, pp. iii-iii, 1996

Authors: Li, X. | Hayashi, K.

Article Type: Research Article

Abstract: If an artery is cut transversely into rings, and the rings are then cut radially, they spring open into sectors. This phenomenon implies the existence of residual stresses and strains in the arterial wall in the non-loaded state. In the present paper, we propose a new method to calculate the residual strain from the measured wall dimensions and a polar angle of a specimen in the stress-free state, assuming that the wall is homogeneous and incompressible, and that a radially cut, stress-free specimen forms a circular sector. For this analysis, edge angles were measured at the edges of the opened-up …specimen. Residual strains were obtained for the descending thoracic aorta, the common carotid artery, and the femoral artery in the rabbit. The results obtained indicated that the magnitude of residual strain was largest in the femoral artery and smallest in the aorta among the three arteries. The opening angle did not depend upon the length of a ring specimen if the ratio of the length to the diameter was ⩽ 3. Show more

Keywords: Residual strain, arterial wall, opening angle

DOI: 10.3233/BIR-1996-33602

Citation: Biorheology, vol. 33, no. 6, pp. 439-449, 1996

Authors: Blahovec, J.

Article Type: Research Article

Abstract: Stress relaxation in three varieties of cherries was studied using the penetration test with a cylindrical pin, 4 mm in diameter, having a flat tip. One half of the fruit was modified by partial skinning, since experiments show that skin approximately doubles the apparent modulus of elasticity of the cherries. The skin also obscures a part of the fruit’s distinctiveness, and affects the experimental results, even if a part of the fruit has been removed. A thermal activation theory with the residual part of stress was used to evaluate the stress relaxation experiments, and yielded results very similar to those …previously obtained for vegetable flesh. Real consistency was observed mainly for residual stress and activation volume. It was observed that the relation between parameters Ct and log bt , and the initial relative slope of the relaxation curve provides information on fruit firmness. Show more

Keywords: Cherry, fruits, stress relaxation, penetration, skin, flesh, firmness

DOI: 10.3233/BIR-1996-33603

Citation: Biorheology, vol. 33, no. 6, pp. 451-462, 1996

Authors: Seki, J. | Sasaki, Y. | Oyama, T. | Yamamoto, J.

Article Type: Short Communication

Abstract: We have applied our developed fiber-optic laser-Doppler anemometer microscope (FLDAM) for the study of the cerebral microcirculation in the rat. The red cell velocity in single pial microvessels was successfully measured through a closed cranial window for the vessel diameter range from 7.8 to 230 µm. The temporal resolution of the FLDAM was sufficiently high to detect the pulsation in the arterioles. Arterio-venous distributions of the temporal mean red cell velocity and wall shear rate are also descri bed.

Keywords: Red cell velocity, laser-Doppler anemometer, wall shear rate, velocity-diameter relation, closed cranial window

DOI: 10.3233/BIR-1996-33604

Citation: Biorheology, vol. 33, no. 6, pp. 463-470, 1996

Authors: Sharp, M.K. | Cook, J. | McCarvill, W.T. | Lee, C.S. | Arleta, F. | Tarbell, J.M.

Article Type: Short Communication

Abstract: A transparent viscoelastic blood analog fluid was developed for use with Laser-Induced Photochemical Anemometry. To provide solubility of the photochemical tracer, 1’, 3’, 3’-trimethyl-6-nitroindoline-2-spiro-2-benzopyran (TNSB dye, Kodak Chemicals), the analog solvent needed to be nonpolar, thus currently available aqueous blood analogs were not suitable. An analog consisting of 0.04% ethylhydroxyethylcellulose dissolved in gamma-butyrolactone produced a pseudoplastic steady shear response with low elasticity in unsteady shear, while being compatible with the photochemical tracer.

Keywords: Blood analog, laser-induced photochemical anemometry, LIPA

DOI: 10.3233/BIR-1996-33605

Citation: Biorheology, vol. 33, no. 6, pp. 471-476, 1996

Authors: Woodland, N.B. | Cordatos, K. | Hung, W.T. | Reuben, A. | Holley, L.

Article Type: Research Article

Abstract: Erythrocyte Sedimentation Rate (ESR) is a simple, non-specific clinical test. Most models of erythrocyte sedimentation (ES) are formulated as a sigmoid function but consider the ES process to consist of three distinct phases: single-cell fall; fall of rouleaux and aggregates; cell packing. Recently, a piecewise (three-phase) continuous model has been developed. Our study applies ES data from 29 haematologically normal subjects to this model and re-evaluates the mechanism of ES using the derived model parameters. Using the Westergren technique, ES readings were taken every 10 minutes for 300 minutes. Three subjects remained in the first phase, while 26 displayed three …discrete phases. For the 26 subjects, the average rate of fall of the sedimenting particles in the first phase was 87 µm/min, while that of the second phase was 176 µm/min. The ratio of these two values suggests an alternative nature of sedimenting particles in the first phase. Further, the average duration of the first phase was 62 minutes, suggesting that, in 50% of subjects, aggregate formation is incomplete when ESR is measured at 60 minutes. Show more

Keywords: Erythrocyte sedimentation rate, ESR, Westergren, rouleaux, aggregation, model

DOI: 10.3233/BIR-1996-33606

Citation: Biorheology, vol. 33, no. 6, pp. 477-488, 1996

Authors: Baskurt, O.K. | Meiselman, H.J.

Article Type: Research Article

Abstract: Red blood cell (RBC) shape change under shear is generally reversible, with the time course of shape recovery a function of the elastic and viscous properties of the RBC membrane. RBC shape recovery can be investigated, using several different techniques, to provide information about the membrane material properties that are not directly accessible by frequently used methods to assess RBC deformability (e.g., micropore filtration). In the present study, RBC shape recovery was studied in a Couette system after abrupt cessation of shear, either by analyzing the time course of laser light reflection or by serial measurements of elongation indexes from …laser diffraction patterns. The time course of shape recovery monitored with both techniques can be described with an exponential equation. Calculated time constants for normal human RBC were 119 ± 17 msec and 97 ± 15 msec as measured by light reflection and ektacytometry, respectively. Treatment of RBC with glutaraldehyde resulted in dose-dependent decreases in the shape recovery time constant. Heat treatment (48° C, 20 min), which is known to increase mainly the shear elastic modulus of the membrane, decreased the time constant by 65%. In contrast, wheat germ agglutinin treatment increased the shape recovery time constant by 22%, presumably by increasing membrane surface viscosity. Our results indicate that the shape recovery time constant of RBC can be measured easily and accurately by computerized light reflection analysis. Show more

Keywords: Red blood cell, shape recovery, membrane mechanics, relaxation time

DOI: 10.3233/BIR-1996-33607

Citation: Biorheology, vol. 33, no. 6, pp. 489-503, 1996

Article Type: Research Article

DOI: 10.3233/BIR-1996-33608

Citation: Biorheology, vol. 33, no. 6, pp. 505-507, 1996

Article Type: Correction

DOI: 10.3233/BIR-1996-33609

Citation: Biorheology, vol. 33, no. 6, pp. 509-509, 1996