Biorheology - Volume 23, issue s1

Authors: Duvivier, C. | Didelon, J. | Arnould, J.P. | Zahm, J.M. | Puchelle, E. | Kopp, C. | Obrecht, B.

Article Type: Research Article

Abstract: In clinical practice, a wide variety of drugs are given to modify the rheological properties of bronchial mucus but they are frequently not correctly chosen because there is not a simple apparatus available for the routine measurement of the mucus viscoelasticity. We designed a new viscoelastometer which is easy to operate and permit accurate measurement of the viscoelastic properties of mucus. The system has a Couette geometry and requires a sample of 1 ml. The outer cylinder is thermostated and rotates at a constant rate. The resulting torque is measured on the inner cylinder using a microdisplacement transducer. The …inner cylinder is suspended by a special wire system which maintains a constant 0.75 mm gap between the two cylinders. The apparent viscosity is calculated up to 100 Pa.s. at a low shear rate (0.4 s−1 ) and the elasticity is analyzed by a stress relaxation method The characteristics of the apparatus and the typical viscoelasticity behaviour of several sputum samples are reported. Show more

Keywords: rheology, viscoelastometer, bronchial mucus

DOI: 10.3233/BIR-1984-23S121

Citation: Biorheology, vol. 23, no. s1, pp. 119-122, 1984

Authors: Arnould, J.P. | Zahm, J.M. | Pottier, G. | Duvivier, C. | Puchelle, E.

Article Type: Research Article

Abstract: Spinability is a rheological parameter which characterizes the property of fluids to be drawn into threads when stretched. It has been shown that this property is of particular importance in the mucus transport process. This paper describes an automatic apparatus which measures the spinability of a calibrated volume (2g μ l) of sample at a stretching rate of 10 mm.sec−1 . The reproducibility of the measurements is analyzed on mucus simulants and on different types of bronchial mucus. Using this technique, we observed that the spinability of bronchial secretions is significantly correlated (r = 0.69, p < 0.001) with …their transport rate measured on the depleted frog palate. This device is suitable for measuring the spinability of all conductive types of mucus and other biological fluids. Show more

Keywords: Respiratory mucus, thread-forming property, spinability, mucociliary transport

DOI: 10.3233/BIR-1984-23S122

Citation: Biorheology, vol. 23, no. s1, pp. 123-126, 1984

Authors: Bell, Alan E. | James, Stuart L. | Marriott, Christopher

Article Type: Research Article

Abstract: In order to rationally test the efficacy of mucolytic and mucospissic compounds, their effects upon mucus viscoelasticity, ciliary beat frequency (c.b.f.) and total mucociliary transport rate (t.t.r.) must all be determined. Methods are described which allow the measurement of the viscoelastic modulii of small (10μ L) quantities of mucus, while c.b.f. and t.t.r. are determined using the frog palate model.

Keywords: mucus, mucociliary, mucolytic, viscoelasticity

DOI: 10.3233/BIR-1984-23S123

Citation: Biorheology, vol. 23, no. s1, pp. 127-130, 1984

Authors: Koyama, T. | Nitta, J. | Asakura, T. | Ushizaka, T. | Aizu, H. | Kikuchi, Y.

Article Type: Research Article

Abstract: A velocimeter for measurements of blood flow velocity in microvessels was constructed with a microscope, a grating, a photomultiplier and a wave-period measuring circuit. A differential detection system seemed to be useful when the probing area was extremely small. A pulsating flow velocity contour and the velocity reduction caused by an application of noradrenaline were on-line recorded in an arteriole of foot web of frogs.

Keywords: Grating laser microscope, differential detection, blood flow velocity, microvessels

DOI: 10.3233/BIR-1984-23S124

Citation: Biorheology, vol. 23, no. s1, pp. 131-134, 1984

Authors: Braasch, D.

Article Type: Research Article

Abstract: Capillary blood flow may be considered as the flow of two compartments a.) the low viscous cell free marginal layer, surrounding b.) the higher viscous axial core. If the flow of both compartments is calculated separately according to Poiseuille, the addition of the two calculations allows to adapt Poiseuille’s law to the non-Newtonian blood flow in small capillaries. The modified law correlates theoretical and experimental data with R2 =0.99. (H=0.3–0.7, τ W =0.1–1.2 Pa, blood viscosity 5 to 20 mPa·s, capillary I.D. 0.3 mm). The width of the marginal was calculated by relating the shear dependent change in electrical …resistance in blood perfused capillaries to the development of a cell free marginal layer. The viscosity of the core was determined with a bended glass fibre (⌀= 10 μ m). Show more

Keywords: Viscosity, marginal layer, axial core, Poiseuille’s law

DOI: 10.3233/BIR-1984-23S125

Citation: Biorheology, vol. 23, no. s1, pp. 135-143, 1984

Authors: Slaaf, Dick W. | Tangelder, Geert Jan | Reneman, Robert S.

Article Type: Research Article

Abstract: Blood platelets labeled in vivo with the fluorochrome acridine red can be localized objectively within a thin optical section, using fluorescence microscopy. This allows the study of the rheological behavior of platelets in vivo as exemplified by the assessment of the concentration distribution and the orientation of platelets flowing in small arterioles of the rabbit mesentery.

Keywords: blood platelets, rheology, in vivo, fluorescence

DOI: 10.3233/BIR-1984-23S126

Citation: Biorheology, vol. 23, no. s1, pp. 145-149, 1984

Authors: Bitoun, J.P. | Ly, D.P. | Bellet, D.

Article Type: Research Article

Abstract: This text recalls the main sequences of a videofilm in which we have looked at the blood flow through small diameter tubes, varying from 200 to 500 μ m diameter, using a video equipment where the camera is fixed to a phase contrast microscope. Flows of two fluid model through converging-diverging small tubes have been studied both theoretically and experimentally, where we have considered the influence of tube diameter, stenosis, flow rate, haematocrit upon the red blood cells repartitions and the thickness of peripheral plasma layer.

DOI: 10.3233/BIR-1984-23S127

Citation: Biorheology, vol. 23, no. s1, pp. 151-153, 1984

Authors: Kiesewetter, H. | Mrowietz, C. | Lazar, H. | Jung, F.

Article Type: Research Article

Abstract: An instrument was developed which can simultaneously determine the hematocrit and the total electrolyte concentration in blood and plasma respectively. It is possible to correct the hematocrit value for fluctuations of the total electrolyte concentration. Pilot studies of this device have been conducted on physiological and rigid erythrocyte suspensions and on plasma with various total electrolyte concentration. In the future, this device will be employed in analyzing blood and plasma of patients undergoing hemodialysis.

DOI: 10.3233/BIR-1984-23S128

Citation: Biorheology, vol. 23, no. s1, pp. 155-157, 1984

Authors: Bauer, R. Dietrich

Article Type: Research Article

Abstract: A fundamental problem of haemodynamics lies in the description of the rheological properties of arteries. The time and history dependency of stress and strain, the nonlinearity of the stress-radius relationship, and the activity of vascular smooth muscle complicate or even prevent a complete mathematical characterization of the arterial wall mechanics. Due to this nonlinearity, dynamic investigations were hitherto performed in excised arteries in vitro by means of small sinusoidal changes of stress and radius at different stress levels in a wide frequency range. To allow an analysis of the dynamic rheological properties of arteries in vivo, we have developed a …procedure which permits the separate determination of the elastic, the viscous, and the inertial forces acting on the arterial wall. The stress can be subdivided into an elastic stress which is a function of radius (r), a viscous stress which is a function of dr/dt, and an inertial stress which is a function of d2 r/dt2 . These stresses are formulated as polynomials. Under cyclic loading and unloading, hysteresis loops appear in the stress-radius diagrams of arteries. Since the elastic stress-radius diagram must be free from any loop, the coefficients of the viscous and the inertial stress can be found by a fitting procedure, using the criterion of loop elimination. Investigations were performed on exposed canine arteries in vivo. The main result was that the elastic stress-radius curve was markedly nonlinear at greater pulse pressures. The viscous wall behaviour, too, was nonlinear and depended mainly on the square of the vessel radius. Show more

Keywords: Arterial elasticity, arterial wall viscosity, arterial stress-radius relationship

DOI: 10.3233/BIR-1984-23S129

Citation: Biorheology, vol. 23, no. s1, pp. 159-167, 1984

Authors: Johnson, Marvin | Katz, J. Lawrence

Article Type: Research Article

Abstract: Bone has been shown to be a viscoelastic material which is thermorheologically complex. This implies that multiple mechanisms determine the viscoelastic response of bone. New calculations of the contribution of fluid flow to the viscoelastic behavior of bone have been made. The calculation of the relaxation time was based on Biot’s model for the relaxation of fluid flow in porous materials while the relaxation strength was estimated from simple composite models. These models together with recent measurements of the permeability of bone predict that part of the relaxation due to fluid flow will occur at fairly high frequencies, perhaps above …10 kHz for in vitro samples. Measurements of ultrasonic wave propagation and attenuation in wet bone have been performed from 0.5 MHz to 15 MHz and the mechanical damping was measured from 100 Hz to 1 kHz with fluid viscosities ranging from 10−3 to 5 × 10−2 (MKS). However, a complete understanding of the rheological properties or bone will require additional experiments to bridge the gap between the low frequency measurements and the ultrasonic measurements. Show more

DOI: 10.3233/BIR-1984-23S130

Citation: Biorheology, vol. 23, no. s1, pp. 169-174, 1984