Biorheology - Volume 17, issue 1-2

Authors: Betsch, D.F. | Baer, E.

Article Type: Research Article

DOI: 10.3233/BIR-1980-171-211

Citation: Biorheology, vol. 17, no. 1-2, pp. 83-94, 1980

Authors: Akeson, Wayne H. | Amiel, David | Woo, Savio L-Y.

Article Type: Research Article

Abstract: The purpose of this paper is to review the present knowledge of the effects of immobility on fibrous connective tissue and to outline present theories about the pathogenesis of joint contracture. A severe disordering of connective tissue homeostasis appears when the diarthrodial joints are subjected to prolonged immobilization. Not only are bone, muscle and cartilage affected by disuse, but the fibrous connective tissue structures are functionally disturbed. We found that the tissues lose significant lubricating and buffering volume of water and glycosaminoglycan in concert with increased inter- and intra-molecular cross-links of collagen which resulted in joint stiffness. The potential application …of D-penicillamine and 17β -estradiol in pharmacological doses are being investigated for the therapeutic manipulation of reduction of strength of contracture. Show more

DOI: 10.3233/BIR-1980-171-212

Citation: Biorheology, vol. 17, no. 1-2, pp. 95-110, 1980

Authors: Lai, W. Michael | Mow, Van C.

Article Type: Research Article

Abstract: Linear and nonlinear theories are used to study the one-dimensional permeation problem of liquids flowing through soft tissues under applied pressure gradients. It is found that the strain field induced by the drag of permeation is nonuniform with respect to depth, causing nonuniform permeability in the tissue sample for which the permeability is to be measured. As a consequence, permeability experiments on soft, porous and permeable tissues can only measure their apparent permeabilities. The concept of “intrinsic” permeability is introduced to define the permeability of the tissue under an imposed, uniform clamping strain and a vanishly small imposed pressure gradient …during a flow permeation experiment. Extra-polating from our experimental results for decreasing pressure gradients, we obtained the following intrinsic permeability function: k intrisic = k o exp ( M o e ) where ko and Mo are constants and e is the true strain. By using a nonlinear theory which incorporates the above intrinsic permeability function to describe the permeation experiment, we found that the dependence of apparent permeability on pressure gradient observed in our experiments can be predicted reasonably well by the theory. The results thus show that the intrinsic permeability function could be used to provide a better biphasic model whenever fluid flow becomes an important factor during the deformation of a soft, porous, permeable medium such as articular cartilage. Show more

Keywords: Theory, experiment, drag induced, compression, cartilage

DOI: 10.3233/BIR-1980-171-213

Citation: Biorheology, vol. 17, no. 1-2, pp. 111-123, 1980

Authors: Blake, J.R. | Winet, H.

Article Type: Research Article

Abstract: Although the internal structure of cilia on micro-organisms and in the lung is identical the mechanical principles of fluid (mucous) transport may be vastly different. Cilia on micro-organisms are generally quite long, less densely packed on the epithelium, have a pronounced aperiodic beating pattern and a highly coordinated metachronal wave compared to the short densely packed, multicellular coordination of cilia found in the lung. A simple hydrodynamic theory using two layers of Newtonian fluid of differing viscosity is developed to model muco-ciliary transport. Features include estimates for the mean force distribution, the likelihood that a cilium is located at a …given height above the epithelium for an idealised beat pattern, and allowance for the retardation of the serous layer by the cilia. Initial calculations suggest that if the cilia just penetrate the upper, much more viscous, layer that mucous transport rates are substantially enhanced. Other features of the results are the significant retardation of flow in the serous layer and the ‘plug’ flow in the mucous layer. Show more

DOI: 10.3233/BIR-1980-171-214

Citation: Biorheology, vol. 17, no. 1-2, pp. 125-134, 1980

Authors: Winet, H. | Blake, J.R.

Article Type: Research Article

Abstract: Cilia-generated fluid flow between two strips of frog palate epithelium has been measured and flow velocity profiles have been obtained from the data. The strips are mounted in a covered chamber so as to form a ciliated channel and fluid motion is marked by suspended 1.0 μ m polystyrene latex spheres which act as tracers. Results from a control non-mucus system and a 40% – 50% v/v mucus system are compared with predictions of a theoretical model. This theory for flow in mucociliated channels incorporates flow due to a static pressure drop between the channel ends and a difference in …the cilia tip speeds between the two strips. Show more

DOI: 10.3233/BIR-1980-171-215

Citation: Biorheology, vol. 17, no. 1-2, pp. 135-150, 1980

Authors: Yates, George T. | Wu, Theodore Y. | Johnson, Robert E. | Cheung, Anthony T.W. | Frand, Carol L.

Article Type: Research Article

Abstract: A series of experiments have been carried out to investigate the muco-ciliary transport in the trachea of rat, rabbit and chicken with cinemicrographic analyses of the movement, beat pattern and metachrony of the tracheal cilia. As a principal test case of the cilia-tip-penetration-into-mucus hypothesis, detailed studies have been made on the transport of a biochemically viable mucous plug artificially introduced into the chicken trachea both with and without a pressure differential across the mucous plug. Guided by the result of these pilot experiments, a theoretical two-layer model of the muco-ciliary transport is introduced, in which the cilia are assumed to …penetrate shallowly into the overlaying mucous layer during the effective stroke and to withdraw from the mucous layer during the recovery stroke. Both the mucus and the serous fluid are assumed to be Newtonian and with widely differ ing viscosities. Based on this model the mucus transport rate is found to depend linearly on the ciliary beat frequency and also on the time of ciliary tip penetration in the mucus. Results are also given on the propulsive force contributed by each individual cilium and an estimate of shear and shear rates within the mucous layer. Show more

DOI: 10.3233/BIR-1980-171-216

Citation: Biorheology, vol. 17, no. 1-2, pp. 151-162, 1980

Authors: Meyer, F.A. | Silberberg, A.

Article Type: Research Article

Abstract: In most instances where sliding transport has to occur over an epithelial tissue surface, the surface is covered by a system of cells capable of secreting a thick flowing fluid, mucus. The sliding motion can involve the transport of the whole organism, the transfer of food, the facilitation of sperm or ovum movement, the clearance of respiratory air ways, etc. There is considerable evidence that the major biopolymeric component involved is a glycoprotein, 80% of whose weight is carbohydrate and 20% is protein. The carbohydrate is attached in the form of short oligomeric side chains to about 4/5 of the …protein backbone leaving 1/5 of its length bare. The bare part of the protein involves disulphide bridges which mayor may not be intramolecular. These glycoproteins are crosslinked into a weak gel i.e. a system which is viscoelastic and is endowed with long, if not infinite, mechanical relaxation times. Where, as is often the case, mucus is in mechanical contact with an array of metachronously beating cilia it acts as coupler in facilitating transport by ciliary propulsion. In relation to the period of the ciliary beat its characteristic relaxation time is sufficiently long so that the response of the mucus layer lying on top of the bed of beating cilia is that of a semi-solid sheet having an essentially rigid interaction with the moving wave. The requirements are strongly linked to ciliary beat characteristics. While solid-like properties are essential they must fall into a certain class. The characteristics of an incipient gel are most favourable in establishing transport. Mucus also possesses properties whose effects and purposes are not yet understood. Mucus, for example is unstable and its gel-like structure declines with time. This occurs rather slowly at body, but more rapidly at higher temperature. Hence the crosslinks of mucus are labile and of a character not yet established. The glycoprotein molecules building the networks are but for the cross links molecularly disperse. This is indicated by measurements of the hydraulic permeability of mucus which is far too low for any other arrangement of the glycoprotein strands to be considered. Show more

Keywords: Mucus, Mucus glycoprotein, Transport, Ciliary beat, Muco-ciliary clearance, Muco-ciliary epithelium

DOI: 10.3233/BIR-1980-171-217

Citation: Biorheology, vol. 17, no. 1-2, pp. 163-168, 1980

Authors: Katz, D.F. | Berger, S.A.

Article Type: Research Article

Abstract: A new model was developed to characterize the hydrodynamics of the interaction between spermatoza and cervical mucus. In this model the local environment about a length element of a spermatozoon in the mucus is represented as a cell consisting of a Newtonian fluid within a rigid, cylindrical no-slip boundary. Such a cell models the mucous microstructure in the sense of “hydrodynamically equivalent” properties. A simple resistive force theory for sperm hydrodynamics was developed and applied to a human spermatozoon swimming within a mucous cell . The results included the prediction that the drag on the sperm head has …a substantial effect on swimming speed. This prediction was tested experimentally, by analyzing high-speed cine films of normal and headless human spermatozoa swimming in mucus. The theoretical result was confirmed, and a cell size of the order of 2 μ m was suggested. Show more

DOI: 10.3233/BIR-1980-171-218

Citation: Biorheology, vol. 17, no. 1-2, pp. 169-175, 1980

Authors: Fukada, Eiichi | Kaibara, Makoto

Article Type: Research Article

Abstract: The flow curves of rabbit blood, human fetal blood, and human adult blood show no hysteresis, a little hysteresis and considerable hysteresis, corresponding to their capacity of forming rouleaux. After the cessation of the steady flow, which was used to remove the original aggregation of cells, the time variations of the rigidity modulus G′ and the loss modulus G″ were determined at 1 Hz. For rabbit blood, almost no time change for G′ and G″ and no erythrocyte sedimentation was observed. For human adult blood, G′ and G″ first increased to a maximum value and then decreased. The rate of …erythrocyte sedimentation was correlated to the rates of increase and decrease of G′ and G″. These observations were accounted for by considering the change of structure of blood: i.e. the formation of rouleux, the association of rouleux, and the formation of nonhomogeneous structure. Show more

DOI: 10.3233/BIR-1980-171-219

Citation: Biorheology, vol. 17, no. 1-2, pp. 177-182, 1980

Authors: Gaehtgens, Peter

Article Type: Research Article

Abstract: The dynamic volume concentration of red cells in a narrow: capillary tube is a resultant of several mechanisms which take place either at the capillary orifice or within the tube. Both types of mechanisms have been studied in experiments in vitro. Human red cell suspensions were perfused through glass capillaries (I.D. 3.3 – 12μ m) branching from a larger feed channel. In addition, relative apparent viscosity was measured as a function of tube hematocrit. The results indicate that the red cell flow fraction is determined by the flow rate distribution at the branching point, and may even be reduced to …zero if the fraction of flow diverted into the capillary orifice is decreased. At any discharge hematocrit the hematocrit within the tube is further reduced due to the velocity difference between cells and plasma. At equal tube hematocrit, the relative apparent viscosity showed a minimum at a tube diameter of approx. 5μ m, whereas the dynamic hematocrit reduction was maximal at approx. 15μ m. These results were correlated with observations of the dynamic flow behaviour of the red cells in a “travelling capillary” which indicate that red cells tend to travel in groups rather than equally spaced, show a hematocrit dependent transition from single-file to multi-file arrangement in tubes larger than 6μ m, and, even in the smallest capillaries, exhibit a distinctly non-symmetric shape, regardless of flow rate and hematocrit. Show more

DOI: 10.3233/BIR-1980-171-220

Citation: Biorheology, vol. 17, no. 1-2, pp. 183-189, 1980