Biorheology - Volume 16, issue 3

Authors: Niimi, Hideyuki

Article Type: Research Article

Abstract: In order to explain the pathogenesis of regional atherosclerotic plaques, the solid-dynamical force is emphasized. The regi.onal stress and deformation in the arterial wall near the ostium hole for branching is analyzed within the framework of shallow shell approximation. A high concentration in the stress and deformation is demonstrated. Following making a theoretical explanation how the regional stress and deformation could be involved for the transport of molecules across the endothelium, a new factor of the regional initiation of atherosclerosis is proposed.

DOI: 10.3233/BIR-1979-16311

Citation: Biorheology, vol. 16, no. 3, pp. 223-230, 1979

Authors: Karino, Takeshi | Kwong, Herman H.M. | Goldsmith, Harry L.

Article Type: Research Article

Abstract: Fluid mechanical factors are probably involved in the localization of atherosclerotic lesions and the deposition of platelet thrombi at arterial branches where secondary flows and vortices develop. Hence, we have studied the flow patterns in glass models of 3 mm diameter right angled T-junctions with square or rounded corners. With flow entering through the main tube, cine films of the paths of microspheres in dilute suspensions were taken at inflow Reynolds number Reo from 15 to 420 and flow ratios Q1 /Q2 main: side tube from 0.05 to 4.0. In the square T-junction, paired vortices symmetrical about the common …median plane formed at the entrances of the main and side daughter tubes over a wide range of Reo and Q1 /Q2 . Particles spiralled in open streamlines through the large main vortex; some then crossed above or below the mainstream to the side tube and through the side vortex, downstream of which there was a double helical flow. At high Q1 /Q2 , only the side vortex was present. At Q1 /Q2 < 0.1 and Re0 > 100, a third vortex formed downstream of the main vortex. In the rounded T-junction, the main vortex was formed at a lower, and the side vortex at a higher Reo than in the square T-junction. When flow entered through the side tube, paired connected vortices were also formed, but only when one daughter tube was severely occluded. Show more

DOI: 10.3233/BIR-1979-16312

Citation: Biorheology, vol. 16, no. 3, pp. 231-248, 1979

Authors: Stein, Paul D. | Sabbah, Hani N. | Anbe, Daniel T. | Walburn, Frederick J.

Article Type: Research Article

Abstract: In view of a possible contribution of turbulent flow upon atherogenesis, particularly at bifurcations of vessels, an evaluation of the nature of flow in man in the abdominal aorta and common iliac artery was made. Velocity was measured in eight resting patients with a hot film velocity probe. A particular effort was made to record velocity in the region of the bifurcation of the aorta at the common iliac arteries. No high frequency disturbances of velocity were observed in the abdominal aorta or common iliac arteries, either during systole or diastole in any of the patients. Peak velocity in the …aorta, at the level of the renal artery, was 28 ± 4 cm/sec (mean ± SEM), at the aortic bifurcation it was 27 ± 4 cm/sec and at the common iliac artery it was 24 ± 4 cm/sec. The peak Reynolds number, measured at the aortic bifurcation (in four patients), ranged from 400 to 1100, and in the common iliac artery it ranged from 390 to 620. Absence of turbulent flow in the abdominal aorta and common iliac arteries in resting patients suggests that turbulence does not initiate atherosclerosis in these areas. However, a possible contribution of turbulence to atherosclerosis, once plaque formation has caused an irregularity of arterial walls, cannot be excluded. Show more

DOI: 10.3233/BIR-1979-16313

Citation: Biorheology, vol. 16, no. 3, pp. 249-255, 1979

Authors: Péronneau, P. | Nakache, M.

Article Type: Research Article

Abstract: It is now recognized that relations exist between mechanical factor of blood and occurrence of atheromatous plates. Various phenomena can interfere, such as parietal friction, separated zones and instabilities. In particular, measurement of parietal flow depends on the instruments available and few of them are able to give an accurate evaluation of instantaneous local velocities without perturbing the blood flow. For this purpose, an ultrasonic Doppler method is proposed associating echo graphic and Doppler techniques whereby local velocities and gradient on the vascular wall can be obtained in vivo and in vitro. Specific procedures are established i) to get a …convenient spatial resolution, ii) to provide calibrated values of the longitudinal component of velocities, involving a biangulation method. Show more

DOI: 10.3233/BIR-1979-16314

Citation: Biorheology, vol. 16, no. 3, pp. 257-263, 1979

Authors: Nakache, M. | Péronneau, P.

Article Type: Research Article

Abstract: The study described is intended to demonstrate the relation which can exist in the parietal microenvironment between blood flow and metabolic surface phenomena. For this purpose modelisation technique is used. An enzymatic protein (beta galactosidase EC-3.2.1.23) is fixed on the internal surface of a nylon tube, throught which a calibrated flow of substrate (orthonitrophenyl β -D galactoside (ON PG) is generated by a pump. Variations in catalytic activity under influence of flow is monitored by enzymatic kinetic measurement. The influence of wall stresses GM induced by continuous flow of substrate is studied. Distinction should be made between Michaelis behavioural …reaction rate and reaction rate controlled by diffusion; for GM values less than 125 s−1 , the process of substrate transfer to the wall depending on diffusion. Show more

DOI: 10.3233/BIR-1979-16315

Citation: Biorheology, vol. 16, no. 3, pp. 265-276, 1979

Authors: Vincent, J.F.V. | Currey, J.D.

Article Type: Announcement

DOI: 10.3233/BIR-1979-16316

Citation: Biorheology, vol. 16, no. 3, pp. 277-278, 1979