Biorheology - Volume 18, issue 3-6

Authors: Silberberg, Alex

Article Type: Other

DOI: 10.3233/BIR-1981-183-601

Citation: Biorheology, vol. 18, no. 3-6, pp. 305-306, 1981

Authors: Skalak, Richard | Chien, Shu

Article Type: Research Article

Abstract: The history of capillary flow is presented from the earliest observations to the most recent experiments. Parallel theoretical developments are traced from early work on continuous fluids to modern work in which the discrete nature of each blood cell is taken into account. A comparison of theory and experiments shows that most features of capillary flow are well understood qualitatively, e.g. the variations of cell concentration and apparent viscosity with microvessel diameter. Quantitative comparisons between theory and experiments, however, are not yet possible. There is a need for the development of theoretical solution for non-axisymmetric flow of flexible particles …in a capillary, as well as flow at junctions. Show more

Keywords: Apparent viscosity, Erythrocytes, Fåhraeus-Lindqvist effect, Hematocrit, Hemorheology, Microcirculation

DOI: 10.3233/BIR-1981-183-602

Citation: Biorheology, vol. 18, no. 3-6, pp. 307-330, 1981

Authors: Bugliarello, George | Yanizeskio, George M.

Article Type: Research Article

Abstract: This paper describes the behavior of isolated neutrally buoyant particles and particle groupings flowing through a thin rectangular channel of high aspect ratio (Hele-Shaw flow). The most significant finding is the tendency of two or more particles travelling within a critical distance from each other to interact, moving toward each other and acquiring characteristic equilibrium configurations. This phenomenon helps explain previous observations of the behavior of low concentration suspensions of neutrally buoyant spherical particles flowing in the laminar inertial range through the same type of channel.

Keywords: multiphase flows, dilute suspensions, particle interactions

DOI: 10.3233/BIR-1981-183-603

Citation: Biorheology, vol. 18, no. 3-6, pp. 331-346, 1981

Authors: Oka, S.

Article Type: Research Article

Abstract: The apparent viscosity of blood measured with a capillary viscometer is influenced not only by the size of the capillary tube (sigma effect), but also by its wall surface condition. Copley, Scott Blair et al. reported that the apparent viscosities always showed a decrease when blood, plasma or serum were in contact with fibrin as compared with glass and other surfaces such as silicone (Copley-Scott Blair phenomenon). In order to offer a reasonable explanation of the Copley-Scott Blair phenomenon, the role of the electric double layer existing at the interface between the fibrin-coated glass surface and blood, plasma or serum …has been emphasized. The influence of an electric double layer upon the Poiseuille flow of an electrolyte solution has been treated theoretically. The effect of an electric double layer is expressed through a nondimensional parameter α = ε σ ζ / ( 2 π K η R ) where σ and ζ are respectively the surface charge density and zeta potential of the electric double layer, ε , K and η are respectively the dielectric constant, specific conductivity and viscosity of the Newtonian liquid, and R is the radius of the tube. The parameter α becomes significant when the product σ ζ is large, as is expected for fibrin surfaces, while it will take small values for glass, silicone and polyethylene surfaces. Moreover, the parameter α becomes significant for small values of R, showing that the effect of an electric double layer becomes especially significant in capillaries and microvessels. Experimental confirmation of our theory and the extension of our theory to blood are desirable. Show more

Keywords: Capillary blood flow, Electric double layer, Wall surface effect and Zeta potential

DOI: 10.3233/BIR-1981-183-604

Citation: Biorheology, vol. 18, no. 3-6, pp. 347-353, 1981

Authors: Pries, A.R. | Albrecht, K.H. | Gaehtgens, P.

Article Type: Research Article

Abstract: Phase separation between red cells and plasma were studied using blood perfused model systems which consisted of glass capillaries (I.D. between 3.3 and 11.0 μ m) branching from a large bore (I.D. 1.5 mm) feed channel. The orifice of the capillaries was either positioned in the centerline of the feed channel (model A) or flush with its wall (model B). Capillary discharge hematocrit (HD ) was measured at different flow conditions and related to the hematocrit in the feed channel (HF ). The ratio HD /HF was found to be correlated to the ratio between wall shear stress in …the capillary and in the feed channel (τ T / τ F ). While at low τ T / τ F almost no cells entered the capillary, HD increased with increasing τ T / τ F and approached HF in model A. In model B, HD did not reach HF within the experimental range of τ T / τ F ’ The flow fractionation in model B can be explained by “plasma skimming”. In model A cell entry into the capillary is determined by the relationship between forces acting on the red cell either in the direction of the feed channel or of the capillary. For this mechanism the term “screening effect” is proposed. This effect decreases with increasing HF and increasing capillary diameter and vanishes when capillary diameter approaches 12 μ m. Show more

Keywords: blood rheology, capillary blood flow, phase separation, plasma skimming, capillary bifurcation, capillary hematocrit

DOI: 10.3233/BIR-1981-183-605

Citation: Biorheology, vol. 18, no. 3-6, pp. 355-367, 1981

Authors: Fung, Y.C. | Tsang, Winston C.O. | Patitucci, Paul

Article Type: Research Article

Abstract: The need for accurate determination of the geometry of red blood cells is discussed. To overcome the difficulty of wave diffraction which casts a fuzzy border around any object in light microscopy and thus causing an uncertainty in measurements, the method of interference holography was used. Samples of human red blood cells were taken from 14 healthy subjects and the cell geometry was measured from photographs taken in a Leitz interference microscope of the Mach-Zender type. The images were analyzed as holographs. The method has a resolution of 0.02 μ m. Statistical results on cell diameter, minimum and maximum thickness, …surface area, volume and sphericity index, as well as the correlations between these parameters are reported. For the total samples collected, the average human red cell diameter was found to be 7.65 ± 0.05 μ m (SEM), with a standard deviation of 0.67 μ m. The mean values of the surface area and volume computed from holograms were 129.95 ± 1.03 μ m2 (SEM) and 97.91 ± 1.06 μ m3 (SEM) respectively. The standard deviations of the area and volume were 15.86 μ m2 and 16.16 μ m3 respectively. The correlation between diameter vs volume and diameter vs surface area are discussed. Applications of these data are illustrated. In the appendix the geometric parameters of the red cells of the rabbit are presented. Show more

Keywords: Red blood cells, human, rabbit, erythrocytes, diameter, surface area

DOI: 10.3233/BIR-1981-183-606

Citation: Biorheology, vol. 18, no. 3-6, pp. 369-385, 1981

Authors: Dintenfass, L. | Jedrzejczyk, H. | Willard, A.

Article Type: Research Article

Abstract: Stereological parameters d(Heyn), Lamda, and S* /V* , have been applied (for the first time, we believe) to evaluation of kinetics and morphology of aggregation of human red cells obtained from healthy and ill donors. Anticoagulated blood was allowed to flow at shear rate of 230 sec−1 , flow was stopped am microphotographs taken at intervals till 12 minutes elapses. Aggregates increased in size for a period of 4 to 10 minutes, depending on blood sample. Sedimentation could be noticed after 10 minutes. Morphology of aggregates differed, rouleaux formation or clumping of red cells being quite clear under high …magnification. Colour slides were analyzed by the Zeiss Videomat 2 image analyzer using a Zeiss Monochromator. Aggregation of red cells can be described by plotting stereological parameters vs square root of time. Morphology of aggregates can be described by plotting d(Heyn) vs Lamda, or d(Heyn) vs S* /V* . Different samples can be compared by comparing slopes and elevations of linear regressions, or by comparing means and standard deviations of stereological parameters. Show more

Keywords: RBC aggregation, kinetics, morphology, stereology, d(Heyn), Lamda, surface/volume ratio, microphotography, image analysis

DOI: 10.3233/BIR-1981-183-607

Citation: Biorheology, vol. 18, no. 3-6, pp. 387-404, 1981

Authors: Kaibara, M. | Fukada, E.

Article Type: Research Article

Abstract: The time variation of dynamic rigidity modulus G′ and loss modulus G″ of horse and human bloods was determined at 1 Hz after imposing the steady flow with different shear rates for a fixed period. At hematocrits below 45 %, the values of G′ and G′ increased and then decreased through a maximum, depending on the shear rate of the preceding steady flow. The rates of decrease of G′ and G″ after the maximum were greatest at the shear rate of about 10 sec−1 . The shortening of the duration of imposed steady flow reduced the shear rate dependence …of the time variation of G′ and G′. At high hematocrits the rate of decrease of G′ was independent of the shear rate. These observations indicate that the preceding steady flow gives a prolonged influence on the time change of the aggregation structure of red cells during viscoelastic measurement. Show more

Keywords: Red cells, Rouleaux network, Shear rate, Viscoelasticity

DOI: 10.3233/BIR-1981-183-608

Citation: Biorheology, vol. 18, no. 3-6, pp. 405-413, 1981

Authors: Schmid-Schönbein, H. | Born, G.V.R. | Richardson, P.D. | Cusack, N. | Rieger, H. | Forst, R. | Rohling-Winkel, I. | Blasberg, P. | Wehmeyer, A.

Article Type: Research Article

Abstract: Abnormally high shear stresses (Tw > 50–200 Pal are known to occur under exceptional conditions in vivo (e.g. during the formation of a hemostatic plug in a rapidly perfused artery after it has been cut). Likewise, blood flow over a stenosis and blood flow through many artificial organs produces shear stresses in the same order of magnitude. Shear stresses above 50 Pa are known to damage red cells and platelets. It is hypothesized that such “damage” of the blood cells provides a physiological stimulus which triggers key events of platelet activation (directly and indirectly via release of ADP …from ruptured red blood cells) and of the coagulation enzymes (via the demasking of procoagulatory phospholipids). Experiments are described in which the occurrence of the postulated biochemical events is documented under conditions of high shear tube flow. The concept of shear activation of platelets is incorporated in a combined biochemical-hemorheological theory of high shear thrombotic events such as they occur in arteries. In this theory, the process of thrombosis in high flow is considered to be initiated (on the afferent limb) by abnormally high shear stresses, but manifests itself subsequent to autokatalytic augmentation as the formation of white thrombi and deposits onto a wall (efferent limb). Show more

Keywords: Hemorheology, Thrombosis, Blood flow, High flow, Forces, Erythrocytes, Platelets

DOI: 10.3233/BIR-1981-183-609

Citation: Biorheology, vol. 18, no. 3-6, pp. 415-444, 1981

Authors: Joly, M. | Lacombe, C. | Quemada, D.

Article Type: Research Article

Abstract: We have studied the rheological behavior in transient flow of some pathological bloods (diabetic patients and patients with polycythemia). We have used a servo-controlled Couette microviscometer, which allowed us to plot the shear stress variations as a function of time for rectangular and triangular steps of shear rates. We have compared the rheological parameters so obtained with those of the controls, and thus deduced informations about the viscoelasticity, thixotropy and shear-thinning of the different pathological blood samples.

Keywords: Blood rheology, RBC Aggregability, Diabetic blood, Polycythemic blood

DOI: 10.3233/BIR-1981-183-610

Citation: Biorheology, vol. 18, no. 3-6, pp. 445-452, 1981

Authors: Stoltz, J.F. | Lucius, M.

Article Type: Research Article

Abstract: From an analysis of the researches works published on blood viscoelasticity and thixotropy, the authors suggest applying the models used for polymer solutions, in order to account for the phenomena observed with blood (transient and periodic flow). The authors also examine the main techniques and devices for approaching blood viscoelastic and thixotropie properties and cell aggregation (rouleaux). The clinical and pharmacological applications which have been carried out are also summarized.

Keywords: hemorheology, viscoelasticity, thixotropy, aggregation of erythrocytes, rheological models, clinical measurements

DOI: 10.3233/BIR-1981-183-611

Citation: Biorheology, vol. 18, no. 3-6, pp. 453-473, 1981

Authors: Yepsen, G. | Boutin, D. | Litt, M. | Kron, R.E.

Article Type: Research Article

Abstract: A method of determining the non-Newtonian viscosity of fresh blood at a low shear rate consists of analyzing the transient pressure in a capillary flow system subjected to a step function input in the flow rate. The procedure requires solution of the first order step response equation for the flow of a suitable model fluid. A power law model has been used here. The model parameters were sensitive to such variables as hematocrit, presence of anticoagulants, and red cell deformability.

Keywords: fresh Blood Viscosity, Power Law, transient response

DOI: 10.3233/BIR-1981-183-612

Citation: Biorheology, vol. 18, no. 3-6, pp. 475-484, 1981

Authors: Brooks, Donald E. | Easthope, Peter L.

Article Type: Research Article

Abstract: An examination has been made of the variation through the menstrual cycle of blood viscosity and some of the parameters, including the concentrations of some acute phase reactants, which affect blood flow. Effects on blood viscosity were determined by fitting values of shear stress, T, derived from a Contraves LS-2 rheometer, as a function of shear rate, D, and haematocrit, H, to the empirical constitutive function T = X 1 exp ( X 2 H + X 4 / H 2 …) D 1 − X 3 H where X1 to X4 are the adjustable parameters which characterize the intrinsic flow behaviour of the sample. Fibrinogen, albumin, α 2macroglobulin, IgM and antithrobmin III levels in the plasma, whole blood clotting times and erythrocyte sedimentation rates were also measured. Based on over 70 rheological determinations on 12 women and over 200 protein concentration determinations on 43 women it was concluded that no cyclical changes occurred in either the rheological characteristics of anticoagulated blood or the other parameters measured. Show more

Keywords: Menstrual Cycle, Blood viscosity, Constitutive function

DOI: 10.3233/BIR-1981-183-613

Citation: Biorheology, vol. 18, no. 3-6, pp. 485-492, 1981

Authors: Rusch, Ph. | Herrmann, T. | Geyssant, A. | Vasselon, C. | Champailler, A. | Healy, J.C.

Article Type: Research Article

Abstract: Using a new automatic device and a standardised protocole for looking the filterability of erythrocytes through 5 μ pores, we introduced the IF (Index of Filterability) parameter. We demonstrate that IF is dependent on the viscoelastic properties of RBC membranes when Hb is normal, and dependent on Hb and O2 saturation of Hb when Hb is unstable (Thalassemia or drepanocytosis). The molecular interpretation and the interest of that for clinical screening or extensive studies are discussed.

Keywords: Red blood cells, Filterability, Oxygen tension, Hematocrit, Intracellular Enzymes

DOI: 10.3233/BIR-1981-183-614

Citation: Biorheology, vol. 18, no. 3-6, pp. 493-499, 1981

Authors: Quemada, D.

Article Type: Research Article

Abstract: RBC-RBC and RBC-protein interactions are known as strongly influencing the rheological behaviour of blood. As (i) at physiological level in hematocrit these effects are imbricated and (ii) most of previous methods required experimental conditions more or less distant from the physiological ones, further analysis of rheological effects of these interactions seems needed. A new attempt is presented, which grounds on viscosity data processing in terms of an “actual packing concentration” (APC), as a structural parameter. At given hematocrit H and shear rate γ ˙ , the APC is the packing concentration which would be obtained if …particles (aggregates or single ones) were packed without change in their actual state (i.e. the state they have at Hand γ ˙ values). Discussion of hematocrit dependence of low and high shear APCs in the cases of Whole Blood, Defibrinated Blood and Ringer Suspension of cells (from CHIEN et al’s viscosity data) allows one to postulate reasonable structural changes at critical hematocrits, noticely at a percolation like threshold. Relative importance of RBC aggregation and RBC deformation by crowding 1S then deduced. Show more

Keywords: Hemorheology, Structural parameters, RBC Aggregation, Hematocrit Dependence, Viscosity model

DOI: 10.3233/BIR-1981-183-615

Citation: Biorheology, vol. 18, no. 3-6, pp. 501-516, 1981

Authors: Corry, W.D. | Jackson, L.J. | Seaman, G.V.F.

Article Type: Research Article

Abstract: Low molecular weight hydroxyethyl starch (HES) was examined for its capacity to aggregate human erythrocytes (RBC) suspended in phosphate buffered saline (PBS). Preliminary studies showed that the effect of RES was dependent not only on the concentration of HES present but on the shear history of the sample as well. After a procedure for standardizing the shear history of the samples was established, measurements of the low shear viscosity, erythrocyte sedimentation rate (ESR) and zeta sedimentation ratio (ZSR) of the RBC-RES suspensions showed that RBC aggregation increased with HES concentration. This trend continued until an HES concentration of ∼ 4% …was reached. Further increases in HES concentration reduced the extent of RBC aggregation. Decreases in the extent of aggregation may have arisen from electrostatic repulsive forces which increase monotonically with RES concentration. Show more

Keywords: Aggregation, electrophoretic mobility, erythrocyte, hydroxyethyl starch, rheology, viscosity

DOI: 10.3233/BIR-1981-183-616

Citation: Biorheology, vol. 18, no. 3-6, pp. 517-529, 1981

Authors: Goldsmith, Harry L. | Lichtarge, Olivier | Tessier-Lavigne, Marc | Spain, Samira

Article Type: Research Article

Abstract: We describe a traveling microtube technique, previously applied to polystyrene latices (11), in which the trajectories of colliding microscopic spheres in Poiseuille flow may be photographed and analyzed with the aid of hydrodynamic theory to calculate the interaction forces due to electrostatic repulsion, van der Waals attraction or polymer bridging which occur when surfaces approach closer than 50 nm. The method was applied to human red cells of antigenic type A or B, sphered at constant volume or surface area, fixed with glutaraldehyde and suspended in aqueous glycerol with or without the addition of the corresponding antibody. The trajectories of …transient doublets of colliding sphered red cells exhibited marked asymmetry, not due to electrostatic repulsion but due to the presence of surface asperities on the particles. In the presence of antisera, permanent doublets formed due to bridging of antibody between antigenic sites on adjacent cell surfaces. Forces of the order of 0.1 nN were required to break up these linkages. Measurements of the period of rotation showed that permanent doublets behaved as rigid dumbbells except at the lowest antiserum concentration. Trajectories of colliding rabbit granulocytes were also studied and found to be markedly asymmetric due to the ruffled surfaces of the cells. Nevertheless, some collisions resulted in the formation of permanent doublets. Show more

Keywords: Trajectories, collisions, sphered red cells, granulocytes

DOI: 10.3233/BIR-1981-183-617

Citation: Biorheology, vol. 18, no. 3-6, pp. 531-555, 1981

Authors: Whitmore, Raymond L.

Article Type: Research Article

Abstract: Fresh human erythrocytes were resuspended in phosphate-buffered dextran solutions at osmolarities ranging from normal down to hemolysis in order to change their shape. Another batch of the erythrocytes was hardened and resuspended. From rheological measurement made in Brookfield and Contraves viscometers it was concluded that the rigidity of an erythrocyte was much more important than its shape in determining the bulk rheology of blood.

Keywords: Blood, Erythrocyte Volume, Erythrocytes, Rheology, Suspensions, Viscosity

DOI: 10.3233/BIR-1981-183-618

Citation: Biorheology, vol. 18, no. 3-6, pp. 557-562, 1981

Authors: Palade, G.F. | Simionescu, M. | Simionescu, N.

Article Type: Research Article

Abstract: The distribution of anionic sites on the luminal surface of the fenestrated endothelium of intestinal and pancreatic blood capillaries was investigated using cationized ferritin (CF), pI 8.4, as a probe. CF was administered in vivo by i.v. injection, or added to perfusates in in situ experiments. Anionic sites were found distributed in differentiated micro domains clearly associated with structural elements involved in capillary permeability. The affinity and intensity of CF labelling decreased in this order: 1- fenestral diaphragms, 2- coated pits and vesicles, 3- plasmalemma proper. Neither the membranes, nor the associated stomatal diaphragms of plasmalemmal vesicles and transendothelial channels …were labelled by CF. All anionic sites could be removed from the luminal surface of the endothelium by perfusion with protases of broad specificity (pronase, papain). The anionic sites of the fenestral diaphragms were preferentially removed by perfusion with heparinase, an indication that they are contributed by heparan sulfates. The implications of these findings are discussed in relation to capillary permeability to charged macromolecules, primarily plasma proteins. Show more

Keywords: Capillary Endothelium, Ionic Sites, Differentiated Microdomains, Heparan Sulphate, Fenestral Diaphragms, Plasmalemmal Vesicles

DOI: 10.3233/BIR-1981-183-619

Citation: Biorheology, vol. 18, no. 3-6, pp. 563-568, 1981

Authors: Winlove, C.P. | Davis, Jane | Iacovides, A. | Chabane1, Ann

Article Type: Research Article

Abstract: A tracer system suitable for radioisotope, autoradiographic or electron microscopic investigations of macromolecule transport in tissues is described. The tracer consists of an electron dense nucleus of radioactive colloidal gold stabilised by a macromolecular coating into which a second radioactive label may be incorporated. The physical characteristics of the tracer system have been investigated. Commercially produced gelatin coated particles suspended in 0.9% NaCl had total hydrodynamic radii ranging between 70 Å and 200 Å and nuclear radii of between 15 and 25 Å. Particles of a single hydrodynamic radius showed similar electrophoretic mobility but had a wide range of iso- electric points. …Incubation in plasma produced an increase in the hydrodynamic radius of the particles. The rate of adsorption increased with the initial radius of the particles and with the temperature of incubation. From the temperature dependence an activation energy for the adsorption process of 46 ± 6 k Joule mole−1 was deduced. Incubation with serum or with fibronectin produced a smaller increase in particle size, but incubation with fibrinogen, albumin or γ -globulin, alone or in combination in either 0.9% NaCl or Tyrode’s solution, had no effect on particle size. Show more

Keywords: Macromolecule transport, Protein adsorption, Gold colloid

DOI: 10.3233/BIR-1981-183-620

Citation: Biorheology, vol. 18, no. 3-6, pp. 569-578, 1981

Authors: Witte, Siegfried

Article Type: Research Article

Abstract: Purified human fibrinogen conjugated in vitro with Fluorescein-Isothiocyanate (FITC) has been injected intravenously in rats (3–6.5 mg/100 g body weight). An intestinal loop with a well developed microvasculature was exposed into a transparent superfused chamber. By means of transmitting visible light and incident fluorescence illumination the microcirculatory blood vessels have been observed with an intravital fluorescence microscope. We found an accumulation of the fluorescent-labeled fibrinogen on the vascular wall beginning 5–15 minutes after the injection. Spots, streaks, nets and bands of labeled material appear with increasing intensity. They remain stationary at the vessel wall with undisturbed blood flow. A marked …affinity of such fibrinogen accumulation to the venular blood vessels has been found during an observation period of one hour. Topographically the labeled fibrinogen could be identified at the inner lining of the blood vessels, preferably at the interendothelial cell borders. Permeability processes of the labeled fibrinogen through the vessel walls into the perivascular tissue and into the lymph have also been found. The findings support some aspects of Copley’s concept of an endoendothelial fibrin lining. Show more

Keywords: Fibrinogen, Vitalmicroscopy, Fluorescence labeling, Microcirculation

DOI: 10.3233/BIR-1981-183-621

Citation: Biorheology, vol. 18, no. 3-6, pp. 579-588, 1981

Authors: Silberberg, A. | Klein, J.

Article Type: Research Article

Abstract: Two methods are applied to determine the thickness of an adsorbed soluble collagen layer on glass. One involves time of flow measurements in a glass capillary. Effects due to changes in contact angle and drainage, as the meniscus advances down the instrument, are eliminated. The results are compared with a direct force/distance curve determination for soluble collagen adsorbed to mica. At low pH layer thicknesses in excess of 325 nm are found, indicating that the collagen triple helices are standing end up on the surface. The amount of collagen adsorbed is only about 1 mg/m2 It can, therefore, be …calculated that some 12 nm separate the soluble collagen monomers. The surface layer is very diffuse. Raising the pH reduces layer thickness. Surface heat denaturation gives 70 nm thick layers. Show more

Keywords: Collagen, Glass, Protein Adsorption, Collagen Adsorption, Surface Layer Thickness, Surface wetting

DOI: 10.3233/BIR-1981-183-622

Citation: Biorheology, vol. 18, no. 3-6, pp. 589-599, 1981

Authors: Kukhareva, L.V. | Vorob’ev, V.I.

Article Type: Research Article

Abstract: The melting of collagen in rat tail tendons tanned by p-benzoquinone has been investigated. It was shown that the degree of tannage if it is not too high does not influence the tension-temperature dependence. Our data indicate that the isometric tension-temperature curves determined at any heating rate are not equilibrium. However the curves obtained at a moderate heating rate after preliminary partial melting of the fiber are practically coincident with the thermodynamically equilibrium melting curve. The rate of heating does not affect the relative contraction values derived from the isotonic length-temperature curves. Therefore the values of critical parameters of …the melting, critical stress and critical temperature, estimated from the isotonic data and from the tension-temperature curves of partially premelted fibers are equilibrium. The theoretical equilibrium tension-temperature dependence was first calculated from the Flory equation for the melting in fibrous proteins under load using the experimentally determined value of critical temperature. The resulting curve coincides with the experimental equilibrium curve accurate within the estimation of the number of polymer chains per unit of fiber cross-section. The applicability of the approach used in this study for the analysis of melting of various natural and synthetic polymer fibers is discussed. Show more

Keywords: Collagen Fibers, Rat Tail Tendons, Hydrothermal Contraction, Stress-Temperature Dependence, Equilibrium Melting and Critical Parameters

DOI: 10.3233/BIR-1981-183-623

Citation: Biorheology, vol. 18, no. 3-6, pp. 601-618, 1981

Authors: Maroudas, A. | Bannon, C.

Article Type: Research Article

Abstract: Swelling pressures of cartilage slices from human femoral heads and condyles have been measured against polyethylene glycol 20,000 solutions, standardised previously against mechanically applied pressure. In order to express the fixed charge density of cartilage on the basis of extrafibrillar water, the fraction of intrafibrillar water was determined from the partition of serum albumin between cartilage depleted of proteoglycans, and outside saline solution. The value for the intrafibrillar water was found to be 0.7 × collagen content. Provided the fixed charge density of cartilage slices is based on the equilibrium extrafibrillar water, the swelling pressure curve for cartilage coincides …with that for isolated proteoglycans, except at or near 100% hydration when the tensile stresses present in the collagen network counteract the osmotic pressure of the proteoglycans. These tensile stresses are relieved as soon as the tissue is compressed. The maintenance of the tissue hydration under load can thus be completely described in terms of a balance between the osmotic pressure of the proteoglycans and the applied pressure. Show more

Keywords: Swelling pressure, Osmotic pressure, Cartilage, Proteoglycan, Extrafibrillar water, Tissue stress

DOI: 10.3233/BIR-1981-183-624

Citation: Biorheology, vol. 18, no. 3-6, pp. 619-632, 1981

Authors: Kuroda, K. | Kamiya, N.

Article Type: Research Article

Abstract: Using the prototype of newly developed centrifuge-microscope loaded with a video camera to produce an unflickering image, we observed the behavior of cytoplasmic streaming in the young internodal cell of Nitella axilliformis during centrifugation. At 1500 rpm (250×g) the majority of the flowing endoplasm collected at the centrifugal end of the cell, when the boundary between the accumulated endoplasm and the cell sap was “horizontal” and flat. By slowing down the speed of rotation to 1000 rpm (110×g), a clearly recognizable streaming was started, in the form of a thin layer moving against the centrifugal force on one side …of the cell; and the endoplasm-cell sap boundary became tilted as if dragged by the stream overcoming the centrifugal force. When centrifugation was stopped, normal streaming soon resumed. The process was perfectly reversible. Prevention of streaming by cytochalasin B was shown to be due to the loss of motive force, and not to the increase in viscosity or gelation of the endoplasm. The streaming velocity-centrifugal force relation is not linear, which is explained by the thinning of the endoplasmic layer during centrifugation. Changes in streaming velocity induced by moderate centrifugal accelerations enabled us to estimate the motive force responsible for the streaming. It was calculated to be about 1 dyn·cm−2 , corresponding well with the data obtained by other methods. Show more

Keywords: Cytoplasmic streaming, Nitella, centrifuge-microscope, television

DOI: 10.3233/BIR-1981-183-625

Citation: Biorheology, vol. 18, no. 3-6, pp. 633-641, 1981

Authors: Yamamoto, Ryoichi | Fujihara, Suguru | Masuda, Yoshio

Article Type: Research Article

Abstract: A compression method for measurement of stress-relaxation proper- ties of the cell wall of storage tissues was developed, and the stress relaxation for the cell wall of Jerusalem artichoke tuber tissue was found to be represented by the equation S = b p · log ( t + T mp ) ( 1 + t p t + T mp ) t + T mp t p …( t + T op ) ( 1 + t p t + T op ) t + T op t p + c p where S is stress, t is time and bp , Top , Tmp and cp are constants. A synthetic auxin, 2,4-dichlorophenoxyacetic acid, induced cell wall loosening represented by a decrease in Top prior to the induction of expansion growth. Auxin and gibberellin synergistically stimulated the increase in bp and the decrease in cp in 2–3 days. Show more

Keywords: Stress-relaxation, Jerusalem artichoke, Auxin, Gibberellin, Cell wall

DOI: 10.3233/BIR-1981-183-626

Citation: Biorheology, vol. 18, no. 3-6, pp. 643-652, 1981

Authors: Charm, S.E. | Wong, B.L.

Article Type: Research Article

Abstract: Biological materials in flow are found to be degraded in flow through shear. Turbulent flow results in greater loss than streamline flow. It is possible to correlate a shear factor associated with flow with the Reynolds number. This preliminary study was carried out with lysozyme and covered a narrow range of Reynolds number. The plot of a shear factor vs the Reynolds number should be universal and independent of the material used to derive it. With this plot, it should be possible to determine the amount of inactivators expected for a material undergoing turbulent flow.

Keywords: Turbulence, shear, biomaterial, inactivation, Reynolds number, enzyme, lysozyme

DOI: 10.3233/BIR-1981-183-627

Citation: Biorheology, vol. 18, no. 3-6, pp. 653-657, 1981

Authors: Puchelle, Edith | Zahm, Jean-Marie | Aug, Françsois

Article Type: Research Article

Abstract: Viscoelasticity, protein content, and ciliary transport rate of sputum were studied in 3 groups of patients: 7 with recurrent bronchitis (group I), 13 “mild” chronic bronchitics (group II) and 19 “severe” chronic bronchitics (group III). The apparent viscosity (η o) and elastic modulus (G) were significantly higher in group I than group II and III. A four-fold decrease in secretory IgA to serum albumin ratio was observed in group III as compared to group II. The ciliary transport rate (Tr) on the depleted frog palate progressively decreased with the duration and severity of the disease. In group I, Tr remained …normal although 6 of the 7 sputa were outside predicted optimal viscoelastic range. These results suggest that other factors than viscosity and elasticity may control the mucociliary transport efficiency. Show more

DOI: 10.3233/BIR-1981-183-628

Citation: Biorheology, vol. 18, no. 3-6, pp. 659-666, 1981

Authors: Tamamushi, B.

Article Type: Research Article

Keywords: Liquid crystals, Rheology, Phase separation, Cell membrane

DOI: 10.3233/BIR-1981-183-629

Citation: Biorheology, vol. 18, no. 3-6, pp. 667-671, 1981

Authors: Papenfuss, Heinz-Dieter | Gross, Joseph F.

Article Type: Research Article

Abstract: The single-file flow of red blood cells in microcirculatory networks is studied theoretically. A phase-separation rule for the cells at the bifurcations is established and the flow-pressure drop relationship for the individual flexible cells is obtained from the work of Sutera and co-workers [Capillary blood flow. II. Deformable model cells in tube flow. Microvasc. Res. 2, 420–433, 1970]. Differences between tube and discharge hematocrit resulting from the kinematics of the blood flow in the capillaries and plasma skimming occurring at the bifurcations are taken into account The model provides flows, pressure drops, hematocrit values and relative viscosities in all …branches of the network. A purely fluid mechanical microhemoregulation is proposed. The mechanism of this peripheral blood regulation is the redistribution of red cells in the individual branches of the network corresponding to the morphology and the local flow rates, thus adjusting the hydraulic resistance to flow. Show more

Keywords: microhemodynarnics, hemorheology, microcirculation, network model, red cells

DOI: 10.3233/BIR-1981-183-630

Citation: Biorheology, vol. 18, no. 3-6, pp. 673-692, 1981

Authors: Hartert, Hellmut H.

Article Type: Research Article

Abstract: Resonance-Thrombography is a successor method of Thrombelastography. Clotting in this technique starts in blood or plasma in a flowing state and is after appearance of the first fibrin strands followed by measuring continuously the elasticity of the growing clot. In the measuring procedure the clot is subject to permanent strain by an orbital movement. Its oscillation causes a stretching procedure of fibrin molecules and gives an assay of clot elasticity by recording a differentiating resonance effect. The Resonance-Thrombogram (RTG) delivers distinguishable and characteristic types of graphs for qualitative and quantitative differences in fibrin production. Separated from the latter quantitative and …qualitative changes in platelet activity are evident. Examples for diagnostic screening are dysfibrinogenemia, disseminated intravascular clotting, thrombocytopathy and -penia. Another field is the panorama of thrombin-like substances as Ancrod and Thrombin-Coagulase, the surveying of which in the RTG will yield more revealing results in clinical situations than the corresponding one-stage tests. Show more

Keywords: Resonance-Thrombography, clot structure, dysfibrinogenemia, platelet shape-change, thrombopathy, thrombin-like substances

DOI: 10.3233/BIR-1981-183-631

Citation: Biorheology, vol. 18, no. 3-6, pp. 693-701, 1981

Article Type: Other

DOI: 10.3233/BIR-1981-183-632

Citation: Biorheology, vol. 18, no. 3-6, pp. 703-723, 1981

Authors: Copley, A.L.

Article Type: Other

DOI: 10.3233/BIR-1981-183-633

Citation: Biorheology, vol. 18, no. 3-6, pp. 725-727, 1981

Article Type: Other

DOI: 10.3233/BIR-1981-183-634

Citation: Biorheology, vol. 18, no. 3-6, pp. 729-729, 1981