Biorheology - Volume 12, issue 1

Authors: Rakow, Allen L. | Hochmuth, Robert M.

Article Type: Research Article

Abstract: Whole cells heated to 48.8°C for 2 min and then cooled to 25°C are less elastic than control cells maintained at 25°C. Cells heated to 47°C for the same time period and then cooled to 25°C have the same elasticity as the control. ATP levels of both heated and control cells are identical. The rate of cooling has no effect on elasticity indicating the occurrence of an irreversible membrane protein denaturation since membrane lipids and hemoglobin are reported not to undergo phase transition at these temperatures.

DOI: 10.3233/BIR-1975-12101

Citation: Biorheology, vol. 12, no. 1, pp. 1-3, 1975

Authors: Copley, A.L. | King, R.G.

Article Type: Research Article

Abstract: Observations of normal stress were made on whole blood, with hematocrits ranging from 40 to 48 per cent, anticoagulated with EDT A, from six healthy, adult human subjects. Two methods were used in connection with the Weissenberg Rheogoniometer. One technique employs a readout system, while the other concerns visual macroscopic observations. In these measurements, the blood was subjected to rotational testing using a cone and plate geometry at shear rates from 0.001 to 1.0 × 10−2 sec−1 . No positive normal stress at a minimum sensitivity of 1 was found in a study on the presence of normal forces …in non-clotted whole blood from healthy human subjects. The negative findings are discussed in relation to concepts by Weissenberg, and to findings of an elastic component in whole blood, recently reported by other authors and subsequently found by us in mutual studies with other investigators. Show more

DOI: 10.3233/BIR-1975-12102

Citation: Biorheology, vol. 12, no. 1, pp. 5-10, 1975

Authors: McMillan, Donald E.

Article Type: Research Article

Abstract: Surface tension has a measurable effect on the rate of flow in capillary viscometers of aqueous solutions of biological materials. Changing the surface tension of saline from 70 to 33 dyn/cm by adding sodium dodecyl sulfate reduces its flow time in Cannon-Ubbelohde semi-micro viscometers by 0.6 per cent. High surface tension not only increases flow time, but it decreases measurement reproducibility by producing variable drainage patterns. Addition of detergent to saline improves reproducibility of measurement so that calibration can be carried out more accurately and far more rapidly. Frequent calibration appears necessary in regular use when removal of biologic materials …from the viscometer requires strong acid and/or alkali. Analysis of surface tension effect in the Ubbelohde viscometer demonstrates three components: (1) a reduction in effective fluid column height due to the bulb meniscus, (2) an upward force due to concavity of the meniscus, and (3) a downward force produced by concavity of the fluid surface in the spherical area below the capillary. Estimations of the magnitude of these three components were in reasonable agreement with observed effects and demonstrated the importance of surface effects in the fiducial line and upper viscometer bulb areas. A method for adjusting solvent flow time to the surface tension of other solutions is described; such an adjustment is more appropriate for Ubbelohde than for Ostwald viscometers. Careful surface tension correction appears particularly important when developing derived viscometric values such as reduced or intrinsic viscosity. Show more

DOI: 10.3233/BIR-1975-12103

Citation: Biorheology, vol. 12, no. 1, pp. 11-19, 1975

Authors: Plowman, Fred | Young, John T. | Janicki, Joseph S.

Article Type: Research Article

Abstract: This paper describes an instrument to measure, in situ, the longitudinal stresses and strains that are developed in a blood vessel segment subjected to a small sinusoidal longitudinal deformation. The instrument generates length changes of arbitrary amplitude and frequency and measures electrically both the magnitude of these length changes and the corresponding longitudinal force in the segment. Even though the overall tissue response is nonlinear, the axial stress due to the small pulsatile changes in force is linearly related to the ensuing strain and, because of the viscous components of the tissue, the strain lags the stress. Experiments on ten …canine aortic segments indicate that for frequencies between 0.5 and 5 Hz this phase angle is small (less than 10°) and increases slightly with frequency. Show more

DOI: 10.3233/BIR-1975-12104

Citation: Biorheology, vol. 12, no. 1, pp. 21-25, 1975

Authors: Richardson, Elspeth

Article Type: Research Article

Abstract: A theoretical model for haemolysis in a uniform shear flow has been developed previously. The possibility of applying this model, and simple extensions of it, to in vitro high shear-rate experiments is explored. Criteria for adequate uniformity of the flow field are developed. For rotating viscometers the dependence of haemolysis time on shear rate is predicted; for capillary tubes the dependence of percentage haemolysis on flow rate and tube dimensions. The flows in the jet test and oscillating wire experiment are shown to be insufficiently uniform for this method of analysis, and the consequences of this are investigated.

DOI: 10.3233/BIR-1975-12105

Citation: Biorheology, vol. 12, no. 1, pp. 27-37, 1975

Authors: Richardson, Elspeth

Article Type: Research Article

Abstract: In discussion of red cells in suction there is some doubt about the importance of slip at the pipette mouth. The extreme assumption that there is no slip is considered here. Two theoretical models, Hookean and Mooney materials, are used to investigate the inflation of a spherical cap. The results of this analysis are then compared with the experimental data already available from suction experiments in an attempt to determine a lower bound for elastic moduli. The values derived are at the lower end of the generally accepted range, being close to those of Hochmuth and Mohandas. The no-slip assumption …is then critically reviewed in the light of these predictions. Show more

DOI: 10.3233/BIR-1975-12106

Citation: Biorheology, vol. 12, no. 1, pp. 39-55, 1975

Authors: Arakawa, M. | Kondo, T. | Tamamushi, B.

Article Type: Research Article

Abstract: Model red blood cells containing aqueous sheep hemoglobin solution within semipermeable poly (phthaloyl l -lysine) membrane are prepared and suspended in isotonic buffer solutions of different pH at volume concentrations of 20, 30 and 40 per cent. Suspensions of sheep red blood cells in the same isotonic buffer solutions at the same volume concentrations are also prepared. The flow properties of the above model and sheep red blood cell suspensions are measured by a capillary viscometer and compared with each other. The effect of dextran added to the suspension medium on the flow properties of the both suspensions is …detected. The effects of the pH of the suspension medium on the viscosity of the model suspension is also measured. The shear stress versus shear rate relations for both of the model and sheep erythrocyte suspensions are found in accord with the Casson equation. The dependence of the relative viscosity on the particle concentration is expressed by an empirical relation: η = 1 + a ϕ + b ϕ 2 + c ϕ 3 for the both suspensions in the same isotonic buffer solution. The result shows that the model suspension can serve as a model for blood in the sense of first approximation. Show more

DOI: 10.3233/BIR-1975-12107

Citation: Biorheology, vol. 12, no. 1, pp. 57-66, 1975

Authors: Puchelle, E. | Da Costa De Moraes, R. | Zahm, J.M.

Article Type: Research Article

Abstract: Les variations de la viscosité apparente et de la recouvrance des expectorations, recueillies au cours de la journée (09:00 h, 11:00 h et 15:00 h) chez 11 bronchitiques chroniques, ont été analysées à l’aide d’un rhéomètre rotatif à cylindres coaxiaux. L’analyse des résultats montre que la viscosité apparente, la recouvrance et le volume expectoré varient selon un profil comparable. Les valeurs les plus basses sont généralement observées à 11:00 h, les valeurs maxima sont notées à 9:00 h pour la viscosité apparente et à 15:00 h pour la recouvrance. Le profil des variations rhéologiques observées au cours de la journée …suggère l’existence d’un rythme circadien du potentiel sécrétoire bronchique. Show more

DOI: 10.3233/BIR-1975-12108

Citation: Biorheology, vol. 12, no. 1, pp. 67-71, 1975

Article Type: Correction

DOI: 10.3233/BIR-1975-12110

Citation: Biorheology, vol. 12, no. 1, pp. 73-73, 1975

Authors: Doerner Jr., Karl

Article Type: Letter

DOI: 10.3233/BIR-1975-12109

Citation: Biorheology, vol. 12, no. 1, pp. 73-73, 1975

Article Type: Abstract

DOI: 10.3233/BIR-1975-12111

Citation: Biorheology, vol. 12, no. 1, pp. 75-80, 1975