Biorheology - Volume 33, issue 1

Authors: Goldsmith, Harry L.

Article Type: Editorial

DOI: 10.3233/BIR-1996-33101

Citation: Biorheology, vol. 33, no. 1, pp. iii-iii, 1996

Authors: Tsai, M.A. | Waugh, R.E. | Keng, P.C.

Article Type: Research Article

Abstract: We have investigated changes in cellular deformability during promyelocytic leukemic HL-60 cell maturation. HL-60 cells were induced to mature with 1.25% dimethyl sulfoxide. Cellular deformability was evaluated by single-cell micropipette aspiration at one day, four days and seven days after induction. HL-60 cells were found to decrease in size and increase in deformability with maturation. When tested under the same aspiration pressures (0.5–1.3 kPa), cytoplasmic viscosity was found to vary from 210 to 85 Pa·s for cells prior to induction; it varied from 85 to 40 Pa·s for cells seven days after induction. Further, cytoplasmic viscosity exhibits power-law dependence on …shear rate, μ = μ c ( γ m / γ c ) − b , where μ is cytoplasmic viscosity, γ m is mean shear rate during cell entry, μ c is the characteristic viscosity at the characteristic shear rate, Ye, and b is a material coefficient. Cells of all maturities showed similar dependence on shear rate (b ≈ 0.5 ), but the characteristic viscosity decreased with maturation except for Day 1. When γ c was set to 1 s-1 , μ c = 236 ± 5   Pa · s for cells prior to induction, μ c = 239 ± 7 , 209 ± 7 and 175 ± 14 Pa·s for cells on Days 1, 4 and 7 of induction, respectively. Show more

Keywords: Leukocytes, differentiation, rheology, viscosity, cytoplasm, leukemia

DOI: 10.3233/BIR-1996-33102

Citation: Biorheology, vol. 33, no. 1, pp. 1-15, 1996

Authors: Whale, M.D. | Grodzinsky, A.J. | Johnson, M.

Article Type: Research Article

Abstract: We measured the specific hydraulic conductivity (K) of the human and bovine aortic wall, two tissues for which K has not been previously reported in the literature, and examined the effects of aging (human) and development (bovine) on K. As part of the study, we also examined the effects of mounting the tissue in a flat or cylindrical configuration and the effects of perfusion pressure. With aging, in the human, we found a modest increase of K with age in a flat geometry; this trend was not apparent in a limited number of measurements in a cylindrical geometry. No significant …dependence of K on developmental stage was found in the bovine aortic wall perfused in either a flat or cylindrical geometry. Our results indicate that aging and developmental changes of the aortic extracellular matrix have minimal effects on its hydrodynamic transport properties as measured. Mounting geometry for the aorta has been a concern reported in the literature since Yamartino et al. (1974) reported that K in the rabbit was 10-fold lower when measured in a flat geometry than in a cylindrical geometry. We found mounting geometry to make only a small difference in the calf and the cow, (Kflat approximately 2/3 of Kcylindrical ), and in the human, we found K to be somewhat higher in the flat geometry than in the cylindrical geometry. Higher perfusion pressures decreased K of bovine tissue in the flat geometry, but pressure was not found to have a significant effect on K in the cylindrical geometry. An analytical model demonstrated that the anisotropic nature of the aortic wall allows it to be compressible (water-expressing) and yet remain at nearly constant tissue volume as the aorta is pressurized in a cylindrical geometry. Show more

Keywords: Aorta, anisotropic, strain, permeability, compressible, perfusion

DOI: 10.3233/BIR-1996-33103

Citation: Biorheology, vol. 33, no. 1, pp. 17-44, 1996

Authors: Pitzer, J.E. | Del Zoppo, G.J. | Schmid-Schönbein, G.W.

Article Type: Research Article

Abstract: Smoking and elevated leukocyte counts are risk factors for cardiovascular disease. Experimental studies suggest that leukocyte activation may be a requirement for certain cardiovascular complications. Clinical studies have demonstrated activated leukocytes in the peripheral blood of stroke victims. Accordingly, neutrophil activation in unseparated whole blood of smokers as well as naive neutrophils of non-smokers exposed to plasma of smokers was investigated. Both spontaneous superoxide formation as determined by nitroblue tetrazolium reduction, as well as pseudopod formation, are significantly elevated in autologous neutrophils of smokers. The surface expression of CD18 and L-selectin on autologous circulating neutrophils of smokers is not significantly …different from non-smoker controls. In contrast, incubation of naive neutrophils with smoker plasma leads to significantly higher levels of superoxide formation, pseudopod formation, and L-selectin shedding, compared with non-smoker plasma, suggesting that the plasma of smokers contains a transferable factor which causes leukocyte activation. The results indicate that analysis of blood samples from large peripheral veins may not accurately reflect leukocyte activation in the circulation since activated leukocytes have a higher probability to be trapped in the microcirculation. Show more

Keywords: Adhesion, selectin, integrin, superoxide, actin, pseudopod formation, organ injury

DOI: 10.3233/BIR-1996-33104

Citation: Biorheology, vol. 33, no. 1, pp. 45-58, 1996

Authors: Prakash, B. | Singh, M.

Article Type: Research Article

Abstract: Based on the variation in the optical density due to erythrocyte concentration and movement, the axial tomographic and image velocimetry techniques are respectively applied to determine the flow field, i.e., the distribution of erythrocytes and axial and radial velocity components, in steady blood flow through a curved glass capillary with a diameter of 180 µm. The data at four positions (two straight and two curved segments of the capillary) are recorded by a video-microscopic system on a video cassette. The erythrocyte and velocity distribution profiles change from symmetric at the straight position to an asymmetric shape at the curved sections. …These profiles become symmetric again at the straight section of the capillary. The increase in the radial velocity component at curved portions is attributed to the secondary flow. The tomograms obtained by concentration profiles show respective changes in the cellular population at various cross-sectional positions. The kinetic energy dissipation, as calculated based on a determination of the flow field, is the minimum for the observed profiles. Any deviation towards parabolic form leads to the dissipation of a higher amount of energy. Show more

Keywords: Blood flow, glass capillary, curvature, tomography, image velocimetry, optimum energy

DOI: 10.3233/BIR-1996-33105

Citation: Biorheology, vol. 33, no. 1, pp. 59-74, 1996

Article Type: Abstract

DOI: 10.3233/BIR-1996-33106

Citation: Biorheology, vol. 33, no. 1, pp. 75-94, 1996

Article Type: Correction

DOI: 10.3233/BIR-1996-33107

Citation: Biorheology, vol. 33, no. 1, pp. 95-96, 1996

Article Type: Announcement

DOI: 10.3233/BIR-1996-33108

Citation: Biorheology, vol. 33, no. 1, pp. 97-97, 1996

Article Type: Other

DOI: 10.3233/BIR-1996-33109

Citation: Biorheology, vol. 33, no. 1, pp. 99-100, 1996