Biorheology - Volume 30, issue 2

Authors: Casley-Smith, J.R.

Article Type: Research Article

Abstract: The effects of the individual Factors controlling interstitial volume vary between the different steady-states. Partial derivatives of volume with respect to each Factor show only the effects near the steady-state. In passing from one steady-state to another, these partial derivatives vary greatly. The total effects of a Factor are those of the integral of the partial derivative from the initial steady-state to the final one. The simplest way to measure a Factor’s total effect is by setting it to zero and observing the difference in tissue volume when the model is perturbed. Thus, to find the effect of proteolysis in …lymphoedema, for example, let proteolysis = 0 and compare the final volume in lymphoedema with that when proteolysis is allowed to occur. While the effect of proteolysis is important in lymphoedema, it is of minimal importance in trauma or normal condition. It is again important if proteolysis is increased by benzo-pyrones. There is little correlation between a partial derivative at a steady-state and the integral of this from normal to the state. In low-to-moderate oedemas, many Factors influence the fluid volume. When this volume becomes very large, all Factors except tissue hydrostatic pressure decrease in importance. Tissue hydrostatic pressure can increase indefinitely and is the ultimate reason that oedemas do not increase without limit. Show more

Keywords: Interstitial fluid volume, oedemas-low and high protein, safety factors, steady-states, tissue proteolysis, benzo-pyrones

DOI: 10.3233/BIR-1993-30201

Citation: Biorheology, vol. 30, no. 2, pp. 93-105, 1993

Authors: Brookshier, K.A. | Tarbell, J.M.

Article Type: Research Article

Abstract: Aqueous solutions of Xanthan gum and glycerin were developed that match both the viscous and elastic components of the 2 Hz complex viscosity of blood over a broad range of shear rates (1–1000 s−1 ) and hematocrits (20%–80%). Measurements of wall shear rate in pulsatile flow were conducted in straight and atherogenic curved artery models using both the blood analog fluid and blood to compare their flow behavior. Peak wall shear rates determined in these models under nearly identical flow conditions with the two fluids were not statistically different (p > 0.05). These results indicate that aqueous Xanthan gum/glycerin solutions …provide a good blood analog fluid for flow conditions characteristic of large arteries. Because the fluid is transparent and made from readily available and fairly inexpensive materials, it may be generally useful for in vitro hemodynamic studies, particularly those employing optical techniques. Show more

Keywords: Blood analog fluid, hematocrit, wall shear rate, viscoelasticity, complex viscosity

DOI: 10.3233/BIR-1993-30202

Citation: Biorheology, vol. 30, no. 2, pp. 107-116, 1993

Authors: Kim, Y.H. | Chandran, K.B.

Article Type: Research Article

Abstract: A study using both experimental and numerical methods was conducted to determine flow dynamics in the vicinity of an end-to-end anastomosis. In vitro experiments were performed to determine the variations in the conduit cross-section at the anastomosis in specimens under static loading. The experimentally determined geometries were used to simulate steady flow through an end-to-end anastomosis using the finite analytic (FA) numerical solution technique in order to obtain solutions for the governing axisymmetric laminar flow equations. Wall shear stresses in the vicinity of end-to-end anastomoses under steady flow conditions were measured using a flush-mounted hot-film anemometer (FMHFA) probe. The experimental …measurements were in agreement with numerical results, except in flow with low Reynolds numbers. Wall shear stresses increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stresses were observed distal to the anastomosis. The present study suggests a correlation between regions of low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia (ANFH) in end-to-end anastomoses. Show more

Keywords: Vascular grafts, end-to-end anastomosis, compliance mismatch, wall shear stress, anastomotic neointimal fibrous hyperplasia

DOI: 10.3233/BIR-1993-30203

Citation: Biorheology, vol. 30, no. 2, pp. 117-130, 1993

Authors: Ookawa, K. | Sato, M. | Ohshima, N.

Article Type: Research Article

Abstract: Effects of extracellular matrices (ECMs) and fluid-imposed shear stress on the cell shape and the cytoskeletal structure of microfilaments were studied in cultured porcine aortic endothelial cells (PAECs). The PAECs were cultured until confluent on non-coated or on ECM-coated glass coverslips. The components of ECM used were type IV collagen, heparan sulfate, chondroitin sulfate and dermatan sulfate. The PAECs cultured on the mixed ECMs showed marked elongation and segmental orientation with randomly distributed cell axis even under a no-flow static condition, and the micro filaments were mostly observed in parallel with the cell axis. After shear flow exposure (2 Pa, …24–48 hrs), the PAECs on non-coated glass were significantly elongated and oriented to the flow direction, however the PAECs on ECM-coated glass showed more retarded responses than the ones on non-coated glass, indicating that the anchorage to the substrate was enhanced by ECMs. The stress fibers were reorganized in accordance with the cell shape and oriented to the flow direction. These findings suggest that ECM may act together with shear stress to modify and maintain the endothelial cell configuration. Show more

Keywords: Cell elongation, cell orientation, micro filament, porcine aortic endothelial cell, extracellular matrix

DOI: 10.3233/BIR-1993-30204

Citation: Biorheology, vol. 30, no. 2, pp. 131-140, 1993

Authors: van der Reijden, W.A. | Veerman, E.C.I. | Nieuw Amerongen, A.V.

Article Type: Research Article

Abstract: Rheological properties of unstimulated human whole saliva (CHWS) and human glandular salivas (parotid, submandibular, sublingual, and palatal) of 7 healthy persons were investigated. The viscosity η ′ an d elasticity η ″ of these salivas were measured as a function of oscillating shear rate γ ˙ on an oscillating capillary viscoelasticity analyzer (Vilastic 3). Viscosity η ′ and elasticity η ″ of total and glandular salivas decreased in the following order: …SL > Pal ≈ CHWS ≈ SM > Par. Rheological behavior of submandibular, palatal and sublingual saliva displayed a comparable pattern, although sublingual saliva showed significantly higher absolute values. The difference in viscoelasticity between submandibular and sublingual saliva was not due to differences in mucin concentration between SM and SL saliva. Flow curves of a range of SL saliva dilutions and flow curves of concentrated SM saliva showed that sublingual saliva was intrinsically more elastic than submandibular saliva. Show more

Keywords: Palatal, rheology, saliva, sublingual, submandibular, viscoelasticity

DOI: 10.3233/BIR-1993-30205

Citation: Biorheology, vol. 30, no. 2, pp. 141-152, 1993

Authors: Mchedlishvili, G. | Beritashvili, N. | Lominadze, D. | Tsinamdzvrishvili, B.

Article Type: Research Article

Abstract: An improved technique for the assessment of red blood cell aggregability in human (or animal) blood is proposed, which can provide medical workers and researchers with direct microscopic quantitative data on this essential index of blood rheological properties in the microcirculation. The procedure of treating the blood samples is optimized: the red cells remain in their natural environment (their own blood plasma), while the manipulations and effects that might distort their natural aggregability index is accomplished in glass chambers using an image analyzer. Examples of the erythrocyte aggregability changes in hypertensive patients as compared with those in the healthy control …group testify to the significance of the obtainable data. Show more

Keywords: Red blood cells: erythrocyte aggregation, blood rheology, hemorheological technology, microcirculation, arterial hypertension

DOI: 10.3233/BIR-1993-30206

Citation: Biorheology, vol. 30, no. 2, pp. 153-161, 1993

Article Type: Other

DOI: 10.3233/BIR-1993-30207

Citation: Biorheology, vol. 30, no. 2, pp. 163-164, 1993