Clinical Hemorheology and Microcirculation - Volume 9, issue 6

Authors: McMillan, D.E. | Strigberger, J. | Utterback, N.G. | Romanoff, N.

Article Type: Research Article

Abstract: Blood from patients with diabetes has been found in many studies to offer more resistance to flow at low shear rate than blood from healthy subjects. Such shear-thinning has been proposed to decrease the stability of high Reynold’s non-Newtonian fluid flow. Flow destabilization could affect arterial flow patterns. Because of this possibility, diabetic and nondiabetic blood were compared for flow stability. When the inner cylinder of a Couette system (viscometer) is rotated rapidly, pairs of counter-rotating toroidal vortices develop at a critical rotation rate, as shown by Taylor. Newtonian fluid Taylor-Couette instability is very regular in onset compared to turbulence …in pipe flow, making it convenient for evaluating the flow stability of non-Newtonian fluids. The critical Taylor number (Tc ) of blood was determined in our Couette viscometer following shear-thinning assessment. Tc of blood from 88 diabetic and 100 nondiabetic subjects was measured using a computer-automated determination of torque inflection. Blood’s steady flow viscosity was measured at 25 rotation rates from .03 to 360 sec−1 . Low shear rate viscosity elevation in diabetes was again demonstrated, but Tc and the ratio in rotation rate to Tc at which wavy vortices first formed were highly comparable, Tc differing by 0.3% between the groups. A previously published technique for adjusting for variation in hematocrit was examined and found more useful for healthy than diabetic blood. Diabetes has no effect on blood’s essentially normal flow stability even though it alters its shear-thinning and viscoelastic behavior. Show more

Keywords: diabetes mellitus, flow instability, hematocrit, hemorheology, turbulence

DOI: 10.3233/CH-1989-9610

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 989-998, 1989

Authors: Tozzi-Ciancarelli, M.G. | Fedele, F. | Tozzi, E. | Di Massimo, C. | Oratore, A. | De Matteis, G. | D’Alfonso, A. | Troiani-Sevi, E. | Gallo, P. | Prencipe, M.

Article Type: Research Article

Abstract: The focus of this paper is mainly directed on the role that the structural and functional perturbations of the erythrocyte membranes could have in the incidence of abnormal microcirculation which occur with the elderly. Rheological parameters of whole blood and the activity of some enzymes involved in erythrocyte metabolism and permeability are studied.

Keywords: Microrheology, elderly, erythrocyte membrane, fluorescence

DOI: 10.3233/CH-1989-9611

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 999-1007, 1989

Authors: Ellory, J.C. | Player, M. | Chalder, S.M. | Stuart, J.

Article Type: Research Article

Abstract: The KCl-cotransport pathway in the membrane of normal human red cells was activated by incubation with the SH-group reagent N-ethylmaleimide. Activation of the pathway caused progressive efflux of cell K+ over 120 min with significant loss of red cell filterability through pores of 5 µm diameter. When the pathway was activated in sickle cells, by incubation at pH 6.8 for 30 min, there was again a significant loss of filterability in excess of that caused by enhanced polymerization of sickle haemoglobin at low pH. Activation of the KCl-cotransport pathway in vivo is therefore a potentially important cause of …dehydration and rheological impairment of sickle cells. Its activation in vitro is a useful new method for investigating the rheological effects of putative anti-sickling compounds, including specific inhibitors of the KCl-cotransporter. Show more

Keywords: Rheology, Erythrocyte deformability, Sickle cell anemia

DOI: 10.3233/CH-1989-9612

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1009-1016, 1989

Authors: Bilo, H.J.G. | Fonk, T. | Ybema, S.J. | Gans, R.O.B. | Donker, A.J.M.

Article Type: Research Article

Abstract: A recently recommended method supposedly estimating the mechanical properties of unmanipulated erythrocytes, was tested in our laboratory in various groups of subjects. Blood was spun for 15 minutes at 200×G (Ha15) and for 5 minutes at 12000×G (Ht). The difference between the obtained hematocrit values Ha15 and Ht, the “erythrocyte packing difference” (EPD), was expressed as a percentage of the hematocrit Ht (%EPD=[(Ha15–Ht)/Ht]× 100). Fifty-two healthy volunteers (N), thirty-seven diabetics (DM) and thirty-five patients with intermittent claudication (IC) were tested. No differences in EPD could be found between N and DM (N: %EPD=23.7±3.1%, DM: %EPD=22.9±3.1%, mean ± SD). In …the IC-group EPD was significantly lower compared to both other groups (IC: %EPD=16.2±2.6%, p < 0.01 vs N and vs DM). The EPD and %EPD in the IC-group correlated inversely with plasma fibrinogen concentration (r = −0.710, p < 0.001 and r = −.0784, p < 0.001, respectively) and with plasma viscosity (r = −.0694, p < 0.001 and r = −0.781, p < 0.001, respectively). We therefore suggest that the EPD is not a method which can be recommended for routine use as a measure for mechanical properties of erythrocytes. Plasma properties (plasma viscosity and plasma fibrinogen concentration) do appear to play a major role in the EPD. Thus, it might be possible that the EPD is more a measure of alterations in plasma viscosity c.q. fibrinogen concentration than of changes in intrinsic erythrocyte deformability. Show more

Keywords: Erythrocyte Deformability, Diabetes Mellitus, Intermittent Claudication, Fibrinogen, Plasma Viscosity

DOI: 10.3233/CH-1989-9613

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1017-1022, 1989

Authors: Rasia, R. | García Rosasco, M. | Valverde de Rasia, J. | Porta, P. | Rewald, E.

Article Type: Brief Report

Keywords: Erythrocyte deformability, hematocrit, red blood cell shear flow, anemia, polycythemia

DOI: 10.3233/CH-1989-9614

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1023-1028, 1989

Authors: Voerman, H.J. | Strack van Schijndel, R.J.M. | Fonk, T.

Article Type: Letter

Keywords: norepinephrine, dopamine, RBC deformability

DOI: 10.3233/CH-1989-9615

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1029-1031, 1989

Article Type: Abstract

Abstract: The following five Abstracts were obtained by H. Landgraf, Secretary-Treasurer of the Organizing Committee, too late for inclusion in the issue of the Conference Abstracts, Volume 9, Number 3 of CLINICAL HEMORHEOLOGY. They, therefore, are included in this issue.

DOI: 10.3233/CH-1989-9616

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1033-1035, 1989

Authors: Ernst, E.

Article Type: Other

DOI: 10.3233/CH-1989-9617

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1037-1050, 1989

Authors: Copley, Alfred L.

Article Type: Correction

DOI: 10.3233/CH-1989-9618

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1051-1051, 1989

Article Type: Other

DOI: 10.3233/CH-1989-9619

Citation: Clinical Hemorheology and Microcirculation, vol. 9, no. 6, pp. 1053-1053, 1989