Biorheology - Volume 29, issue 5-6

Article Type: Other

DOI: 10.3233/BIR-1992-295-601

Citation: Biorheology, vol. 29, no. 5-6, pp. 431-432, 1992

Authors: Silberberg, A.

Article Type: Editorial

DOI: 10.3233/BIR-1992-295-602

Citation: Biorheology, vol. 29, no. 5-6, pp. 433-434, 1992

Authors: Witte, Siegfried

Article Type: Editorial

DOI: 10.3233/BIR-1992-295-603

Citation: Biorheology, vol. 29, no. 5-6, pp. 435-438, 1992

Authors: Silberberg, A.

Article Type: Editorial

DOI: 10.3233/BIR-1992-295-604

Citation: Biorheology, vol. 29, no. 5-6, pp. 439-441, 1992

Authors: Liu, S.Q. | Fung, Y.C.

Article Type: Research Article

Abstract: Rheological properties of blood vessels are expected to change in disease process if the structure of the vessel wall changes. This is illustrated in diabetes, which can be induced in rat by a single injection of Streptozocin. One of the rheological properties of the blood vessel is the stress-strain relationship. The nonlinear stress-strain relationship of arteries is best expressed as derivations of a strain-energy function. In this paper, the stress-strain relations are measured and the coefficients in the strain energy function of arteries are determined for diabetic and control rats. The meaning of these coefficients are explained. The influence of …diabetes on the elastic property of the arteries is expressed by the changes of these coefficients. A point of departure of the present paper from all other blood vessel papers published so far is that all strains used here are referred to the zero-stress state of the arteries, whereas all other papers refer strains to the no-load state . The existence of a large difference between the zero-stress state and no-load state of arteries is one of our recent findings. We have explained that the use of zero-stress state as a basis of strain measurements reveals that the in vivo circumferential stress distribution is quite uniform in the vessel wall at the homeostatic condition. It also makes the strain energy function much more accurate than those in which the residual stress is ignored. Using these new results, the stress and strain distributions in normal and diabetic arteries are presented. Show more

Keywords: Rheological properties, pulmonary and systemic arteries, diabetes

DOI: 10.3233/BIR-1992-295-605

Citation: Biorheology, vol. 29, no. 5-6, pp. 443-457, 1992

Authors: Zahm, I.M. | Pierrot, D. | Chevillard, M. | Puchelle, E.

Article Type: Research Article

Abstract: Epithelial wound repair represents an important process by which the epithelial barrier integrity recovers after wounding. To evaluate and quantify the dynamics of surface airway cell movement during the wound repair process, we developed an in vitro wounding model of human respiratory cells in culture and we analyzed the wound repair by using videomicroscopic and image analysis techniques. We observed that wound closure occurred within 6 hours, due to the spreading and migration of the cells surrounding the wounded surface. The migration rate of the cells at the leading edge of the wound surface increased progressively up to 26 …μ m/h during the repair process which was characterized by a uniform centripetal direction of cell movement. The distance travelled by these cells was 2.5 fold longer than the distance travelled by ciliated cells which were located far from the wound area. These results suggest that cell migration after wounding is an important process by which the respiratory epithelial barrier integrity is maintained. Show more

Keywords: Respiratory epithelium, wound repair, cell migration, image analysis

DOI: 10.3233/BIR-1992-295-606

Citation: Biorheology, vol. 29, no. 5-6, pp. 459-465, 1992

Authors: Chien, Shu | Sung, Lanping Amy | Lee, Mary M.L. | Skalak, Richard

Article Type: Research Article

Abstract: The elasticity of red cell membrane was determined in a rectangular flow channel under controlled shear flow. The relation between shear stress and cell extension ratio (λ ) has been analyzed with the use of Evans’ two-dimensional model. The deformed cell shapes observed experimentally agreed well with the model with λ up to 1.4. The best correlation was found at λ = 1.2. The analysis suggests a nonlinear extensional membrane modulus in the low stress range encountered in the flow channel. In terms of an appropriate strain parameter, the elastic modulus is shown to rise toward the level …encountered in micropipette aspiration experiments. The implications of the present findings in modeling of cell mechanics and in cell hemolysis are discussed. Show more

Keywords: Erythrocyte deformability, hemolysis, elastic modulus, cell membrane, scanning electron microscope, shear stress

DOI: 10.3233/BIR-1992-295-607

Citation: Biorheology, vol. 29, no. 5-6, pp. 467-478, 1992

Authors: Skalak, Richard

Article Type: Research Article

Abstract: The partial plug flow of a concentrated suspension of rigid particles in a circular tube has been previously studied experimentally. It has been shown that a central core may exist in which the mean velocities of the particles and the suspending fluid are equal and constant within a cylindrical core of the flow. This behavior has been attributed to hydrodynamic interaction of the particles within the core. In the present analysis this interaction is interpreted in terms of passing vs. non-passing motions of adjacent particles. A hypothesis of a critical parameter α c involving the shear stress and …the pressure gradient is explored and a new form of the relation of core diameter to particle size and concentration is developed based on α c . Show more

Keywords: Plug flow, suspensions

DOI: 10.3233/BIR-1992-295-608

Citation: Biorheology, vol. 29, no. 5-6, pp. 479-488, 1992

Authors: Sato, Masaaki | Onohara, Masayuki | Ookawa, Keiko | Ohshima, Norio

Article Type: Research Article

Abstract: Platelet adhesion and aggregation were induced on cultured endothelial cells using the fluorescent dye/light method. A cone-and-plate apparatus was newly developed to observe interactions between platelets and cultured endothelial cells under a shear flow condition. The platelet deposition grew on the light-irradiated area of the cells. Degree of endothelial cell injury induced by the dye/light reaction seemed to depend on the dye concentration. Application of either aspirin or indomethacin significantly inhibited the growth of platelet aggregation, but was not effective for the platelet adhesion to endothelial cells. The platelet thrombi were formed on endothelial cells without their denudation. It was …found by transmission electron microscopy that platelets directly adhered to endothelial cells which were not seriously damaged. This thrombus model is expected to be applicable to some physiological and pharmacological studies investigating platelet-endothelial cell interaction and mechanism of platelet thrombus formation in blood vessels. Show more

Keywords: Platelet thrombus, aggregation, cultured endothelial cell, shear flow, dye/light reaction, in vitro model

DOI: 10.3233/BIR-1992-295-609

Citation: Biorheology, vol. 29, no. 5-6, pp. 489-498, 1992

Authors: Engström, K. Gunnar | Meiselman, Herbert J.

Article Type: Research Article

Abstract: Micropipettes as research instruments are well established in cell biology, including blood rheology. However, the experimental results are, to some extent, dependent on the quality of the pipette itself; it is usually critical to have the desired pipette internal diameter and a perpendicular tip. Pipette fabrication is a two-step procedure involving: a) the pulling of the pipette from a glass capillary; b) the trimming of the pipette tip. A common method to trim and fracture the pipette tip is the use of a melted glass bead on a heated tungsten wire. Previous devices using this method were often associated with …problems because the heated wire varied in length with temperature. As a result, the bead together with the attached pipette tip moved markedly and thus hampered the possibility to obtain a perpendicularly cut pipette tip. An improved design, based on the same principle with a melted glass bead, is thus suggested; it eliminates the problem with a moving glass bead and, in addition, allows semi-automatic pipette trimming by utilizing the heat-induced elongation/retraction of the heated wire to fracture the tip without requiring manual assistance. Furthermore, a simple pipette storing technique is suggested, based on standard laboratory utensils, in order to more easily handle fragile pipettes without risk of breakage. Show more

Keywords: Micropipette, fabrication, trimming, fracturing, RBC

DOI: 10.3233/BIR-1992-295-610

Citation: Biorheology, vol. 29, no. 5-6, pp. 499-506, 1992