Biorheology - Volume 12, issue 5

Authors: Copley, A.L. | King, R.G. | Chien, S. | Usami, S. | Skalak, R. | Huang, C.R.

Article Type: Research Article

DOI: 10.3233/BIR-1975-12501

Citation: Biorheology, vol. 12, no. 5, pp. 257-263, 1975

Authors: Palmer, A.A. | Jedrzejczyk, H.J.

Article Type: Research Article

Abstract: 1 1 This abstract differs from that originally published in Biorheology 12, 81, 1975. The resistance to flow of 30% Hct. human red cell suspensions through capillary slits of 25 and 100μ m gap and through tubes of 400μ m and 1 mm diameter was measured in a constant flow rate microcapillary viscometer which could be set at flow rates corresponding to apparent shear rates at the wall (ASAW) from 20 sec−1 to 1000sec−1 . Suspending media were (1) 0.9% NaCl, (2) 3.5% Dextran 40 in 0.9% NaCl and (3) 2% Dextran 200 in 0.9% NaCl. …Rouleau formation was marked in medium (3) and negligible in media (1) and (2). Media (2) and (3) were isoviscous. At ASAW 1000 sec−1 η r was the same in media (2) and (3); at ASAW 20 sec−1 η r , was significantly lower in medium (3) than in either (1) or (2) for all capillaries but the lowest value was in the 100 μ m slit and the highest in the 1 mm tube. It is concluded that rouleau formation reduces resistance to flow in unbranched capillary channels with diameters from 25 to 400 μ m; markedly in a 100μ m channel and slightly in a 1 mm channel. This abstract differs from that originally published in Biorheology 12, 81, 1975. Show more

DOI: 10.3233/BIR-1975-12502

Citation: Biorheology, vol. 12, no. 5, pp. 265-270, 1975

Authors: Blank, Martin | Britten, John S.

Article Type: Research Article

DOI: 10.3233/BIR-1975-12503

Citation: Biorheology, vol. 12, no. 5, pp. 271-274, 1975

Authors: Charm, Stanley E. | Wong, Bing L.

Article Type: Research Article

Abstract: 1 1 The title of the paper and the abstract differ from that originally published in Biorheology 12 , 81, 1975 and was not corrected earlier by the authors-ALC and MJ. Shear inactivation of heparin is an important factor in its loss of anticoagulant activity. It is possible to predict the anticoagulant activity loss of heparin in plasma or water circulated through a teflon capillary tube. The title of the paper and the abstract differ from that originally published in Biorheology 12 , 81, 1975 and was not corrected earlier by the authors-ALC and …MJ. The shear inactivation of heparin in coating on implanted prosthetics may be calculated and is in close agreement with the literature data. Comparison of loss in heparin activity by shear inactivation calculated for the circulation is in close agreement with the unaccounted loss reported in the literature. Show more

DOI: 10.3233/BIR-1975-12504

Citation: Biorheology, vol. 12, no. 5, pp. 275-278, 1975

Authors: Huang, C.R. | Siskovic, N. | Robertson, R.W. | Fabisiak, W. | Smitherberg, E.H. | Copley, A.L.

Article Type: Research Article

DOI: 10.3233/BIR-1975-12505

Citation: Biorheology, vol. 12, no. 5, pp. 279-282, 1975

Authors: Palmer, A.A. | Betts, W.H.

Article Type: Research Article

Abstract: Axial drift (AD) of fresh and aldehyde-hardened erythrocytes was determined for suspensions of initial packed-cell volume (PCV), 10, 20 and 40 per cent, flowing along 25 μ m capillary slits, by measuring the PCV of effluents from 5 terminal slit branches. With both fresh and aldehyde-hardened cells AD increased progressively as the slit length was increased from 0.5 to 5 mm. In general in a slit of the physiologically significant length of 0.5 mm AD had already reached half the final value attained at 10 mm. The radial cell concentration gradient developed, with progression along the slit, more rapidly near …the walls than near the axis. At 10 mm, hardened cells showed much the same degree of axial drift as fresh cells of equal initial PCV but the cell concentration gradient developed more gradually with 10 per cent suspensions and more rapidly with 40 per cent suspensions of hardened cells than with corresponding suspensions of fresh cells. Show more

DOI: 10.3233/BIR-1975-12506

Citation: Biorheology, vol. 12, no. 5, pp. 283-292, 1975

Authors: Stein, Paul D. | Sabbah, Hani N. | Blick, Edward F.

Article Type: Research Article

Abstract: A determination was made of the contribution of erythrocytes to the intensity of turbulence in flowing blood. Blood of various hematocrits and a mixture of plasma and dextrose of nearly identical viscosity and density were caused to flow in a turbulent fashion through an in vitro flow system. The intensity of turbulence was measured with a hot film anemometer. The intensity of turbulence was dependent upon the hematocrit. At hematocrits between 20 and 30 per cent, the intensity of turbulence of the blood was over twice that of the equally viscous and dense plasma. The addition of more cells …(hematocrit 40 per cent) caused a smaller difference between blood and comparable plasma. It appears, therefore, that the presence of cells in suspension tends to increase the turbulence beyond that which would occur with an equally dense and viscous plasma. Show more

DOI: 10.3233/BIR-1975-12507

Citation: Biorheology, vol. 12, no. 5, pp. 293-299, 1975

Authors: Chmiel, H.

Article Type: Research Article

DOI: 10.3233/BIR-1975-12508

Citation: Biorheology, vol. 12, no. 5, pp. 301-307, 1975

Authors: Overholser, K.A. | Itin, J.P. | Brown, D.R. | Harris, T.R.

Article Type: Research Article

Abstract: It was demonstrated that pharmacological alteration of coagulating whole blood can influence the mechanical properties of the clot and can be assessed rheologically. The clot viscoelasticity was measured in a Weissenberg Rheogoniomcter as a function of the concentration of anticoagulant sodium heparin. The storage component of the elastic modulus was seen to be significantly and reproducibly lowered by heparin. Variation between donors was found to be minimized by adjustment of hematocrit, platelet count, and fibrinogen content to common values.

DOI: 10.3233/BIR-1975-12509

Citation: Biorheology, vol. 12, no. 5, pp. 309-316, 1975

Authors: Boyd, J.V. | Sherman, P.

Article Type: Research Article

Abstract: The force developed during stickiness measurements with an Instron machine has been studied at several crosshead speeds using a fast response (u.v.) recorder. In one series of tests the steel plate attached to the underside of the crosshead was pre-wetted with human saliva. Comparison of these data with data obtained previously using a standard, slow response, recorder indicates that in the u.v. recorder studies the maximum force increased with increasing crosshead speed; in the slow recorder studies the reverse was observed. Stress relaxation, cavitation effects and recorder response time may affect the maximum force registered, the last two named factors …becoming particularly active at high crosshead speeds. Panelists’ evaluations of stickiness in the mouth, or with a finger or spoon, and u.v. recorder data did not follow Steven’s power relationship. It is suggested that panelists’ evaluations of stickiness by these three methods involves a mechanical situation resembling that at high crosshead speeds during instrumental evaluation with a slow response recorder. The proteins in human saliva may reduce cavitation during panelists’ evaluation of stickiness in the mouth. Show more

DOI: 10.3233/BIR-1975-12510

Citation: Biorheology, vol. 12, no. 5, pp. 317-322, 1975