Biorheology - Volume 25, issue 1-2

Authors: Koyama, T. | Horimoto, M.

Article Type: Research Article

Abstract: Lymphatic microvessels were microscopically observed on the surface of frog lungs. Magnified images of lymphatic microvessels were recorded on video tapes. The lymphatic microcirculation was studied on a TV monitor at the magnification of 1500 times. 1) valves were observed in lymphatic microvessels, whose diameter was 15 μ m, in frog lungs, 2) the valves were incompetent, 3) contained particles repeatedly flowed backwards and forwards in each lymphatic section, 4) after repetition of the movements, particles passed through the outlet valve, 5) particles seldom flowed back through the inlet valve into the preceding section of the lymphatic, 6) the peak …flow velocity of particles attained 0.5 mm/sec, and 7) the mean flow velocity was II ± 4 μ m on an average and ± SD, 8) the diameter of a localized portion of the lymphatic rilicrovessels changed periodically. Show more

Keywords: lung, lymphatic microvessels, lymphatic valves, particle movement, flow velocity, contraction, bullfrog

DOI: 10.3233/BIR-1988-251-230

Citation: Biorheology, vol. 25, no. 1-2, pp. 219-226, 1988

Authors: Kajiya, F. | Hiramatsu, O. | Ogasawara, Y. | Mito, K. | Tsujioka, K.

Article Type: Research Article

Abstract: To obtain a smaller sample volume and a suitable sample position for the measurement of blood velocity, we fabricated a laser Doppler velocimeter (LDV) with a dual-fiber pickup. The two fibers (clad: 62.5 μ m and core: 50 μ m) were placed side by side. An He-Ne laser was introduced into the blood through one fiber and the backscattered light was collected by the other fiber. The Doppler signal was analyzed by a spectrum analyzer. The spectrum of the Doppler shift frequency showed a sharp peaked pattern for both forward and reverse flows and exhibited an excellent correlation with the …known blood velocity. The blood velocity in the poststenotic portion of canine coronary artery was successfully measured by the dual-fiber LDV. These results indicate that the dual-fiber LDV is useful for measuring blood velocity accurately with a small sample volume even in disturbed flow fields. Show more

Keywords: dual-optical fiber, laser Doppler velocimeter, coronary blood velocity, coronary artery stenosis, flow disturbance

DOI: 10.3233/BIR-1988-251-231

Citation: Biorheology, vol. 25, no. 1-2, pp. 227-235, 1988

Authors: Singh, Megha | Muralidharan, E.

Article Type: Research Article

Abstract: The mechanism of erythrocyte aggregation has been studied in normal plasma, dextran 40 and dextran 70 suspensions in presence and absence of magnetic field at a concentration of 5 percent by laser light scattering. The inhomogeneous magnetic field enhances the aggregating tendency of normal erythrocytes. The growth of aggregates due to dextran 70 is enhanced in presence Of magnetic field. On the other hand the disaggregating effect of dextran 40 is reduced due to this field. The induced changes due to magnetic field during the development of erythrocyte aggregates in these media are determined.

Keywords: Aggregation, magnetic field, dextrans, laser scattering, temporal fluctuations

DOI: 10.3233/BIR-1988-251-232

Citation: Biorheology, vol. 25, no. 1-2, pp. 237-244, 1988

Authors: Lerche, Dietmar | Bilsing, Rainer

Article Type: Research Article

Abstract: The separation process of blood and RBC suspensions in a hematocrit range between 0.3 – 0.7 was investigated with a centrifuge allowed to run at low accelerations (100 xg – 1000 xg). The position of the interface between the supernatant of plasma and the RBC column was continuously recorded by a new optoelectronic measuring system. The separation process could be mathematically described by an exponential decrease of the cell column approaching a final packing. At a given centrifugal acceleration the time constant is influenced by hematocrit, aggregation, deformation and plasma viscosity. The final packing depends linearly on the starting hematocrit …(0.3 – 0.7) and can be used as a measure of deformability. Show more

Keywords: RBC, sedimentation, packing, centrifugation, deformability, aggregability, hematocrit

DOI: 10.3233/BIR-1988-251-233

Citation: Biorheology, vol. 25, no. 1-2, pp. 245-252, 1988

Authors: Araiso, T. | Koyama, T.

Article Type: Research Article

Abstract: The absolute value of the viscosity in membrane lipid bilayers, which is different from the microviscosity advocated by Shinitzky, could be calculated from steady-state fluorescence depolarization of a hydrocarbon fluorophore, 1,6-diphenyl-1,3,5-hexatriene (DPH). This method was based on the theory of time-resolved fluorescence anisotropy and empirical relationships between fluorescence life time and the anisotropy parameters such as half cone angle in wobbling motion and wobbling diffusion rate of the fluorescent probe. Obtained viscosity values of various membranes from this method were consistent with those from time resolved method within experimental error.

Keywords: membrane fluidity, fluorescence anisotropy, wobbling motion of phospholipid

DOI: 10.3233/BIR-1988-251-234

Citation: Biorheology, vol. 25, no. 1-2, pp. 253-259, 1988

Authors: Fung, Y.C.

Article Type: Research Article

Abstract: The connection between microrheology and the constitutive equation of soft tissue is illustrated by an example of the incremental bulk modulus of the lung. It is shown that the following pieces of information are needed in order to make the connection: The detailed structure of the tissue embodied in a mathematical model, the morphometric data on the structural elements, the rheologic data of the materials, and the configuration at zero-stress state, or equivalently, the stress and strain at a homeostatic state. In the case of the lung, we have information on the first three items, but not the last one. …Hence hypotheses have to be introduced concerning the homeostatic condition, the most important of which are the uniform fiber stress and the “optimal design” assumptions. We have shown that these data and hypotheses lead to theoretical results that are in good agreement with experimental observations. Show more

DOI: 10.3233/BIR-1988-251-235

Citation: Biorheology, vol. 25, no. 1-2, pp. 261-270, 1988

Authors: Kamiya, Akira | Ando, Joji | Shibata, Masahiro | Masuda, Hirotake

Article Type: Research Article

Abstract: The effects of fluid shear stress on the function and structure of the vascular system are outlined, based on the findings obtained in our laboratory or of our colleagues. First, it is pointed out that the adaptive response of the vascular wall to flow changes which we observed the internal diameter to keep the wall shear stress constant (1), can attain the optimum vascular branching structure as predicted in the minimum work model by Murray (2). Electron-microscopic studies of similarly shunted arteries revealing various morphological changes in the endothelial cells have suggested that the shear stress initially affects the endothelium …(3,4,5). The in vitro experiments using cultured endothelial cells as well have exhibited that the mitotic activity of the cells significantly increases by applying fluid shear stress (6). From these findings, it is concluded that the adaptive response of the endothelium to the fluid shear stress is an inherent and key process locally regulating the vascular system to be in the most functional state. Show more

Keywords: shear stress, endothelium, microfilament, cell culture, mitosis

DOI: 10.3233/BIR-1988-251-236

Citation: Biorheology, vol. 25, no. 1-2, pp. 271-278, 1988

Authors: Sato, Masaaki | Ohshima, Norio

Article Type: Research Article

Abstract: Ten channels’ dual-sensor method newly developed was applied to the measurement of velocity profiles in arterioles and venules in the rat mesentery. In some experiments, red blood cells (RBC), labelled in vitro with a fluorescein isothiocyanate (FITC), were injected to compare the velocity profiles obtained by the RBC visualization technique with those measured by the dual-sensor method. It was found that the velocity profile of the FITC labelled RBC in straight microvessels was blunt as compared to a parabola. The centerline velocity measured by the dual-sensor method was smaller than that of the FITC labelled RBC by about 20 %. …The velocity profiles were also measured at the curved arterioles and venules as well as at the bifurcation and the confluence. It was found that the velocities were higher along the inner wall at the curved portion and along the outer wall at the bifurcation of arterioles. Show more

Keywords: microcirculation, intravital microscopy, hemorheology, fluorescence, velocity profile

DOI: 10.3233/BIR-1988-251-237

Citation: Biorheology, vol. 25, no. 1-2, pp. 279-288, 1988

Authors: Kawamoto, Yoshitaka | Kaibara, Makoto

Article Type: Research Article

Abstract: The behavior of a newly developed damped oscillation type rheometer was analyzed for fibrinogen solution and blood during coagulation. This rheometer consists of a cylindrical tube suspended from a torsion wire, that is filled with liquid to be tested. The logarithmic damping factor (LDF) during coagulation for blood and fibrinogen solution was obtained by this rheometer, which was closely related to the changes of viscosity and/or viscoelasticity of the blood sample. The slight increase of LDF prior to the rapid decrease was observed for blood. The increase of LDF would be reflected in the formation of the aggregation structure of …red blood cells (rouleaux network) prior to the formation of fibrin network. The value of LDF for fibrinogen solution sharply increased and then decreased through a maximum value with the progress of coagulation, although the change of LDF was remarkably dependent on the fibrinogen concentration. The initial increase in LDF for fibrinogen solution was considered to be due to the formation of small clots in the solution. The decrease in LDF after attaining a maximum value is ascribed to the formation of fully developed fibrin network. The maximum value of LDF during coagulation for fibrinogen solution is higher than that for blood. The behavior was compared with that for non-biological fluids such as viscosity standard liquids and polyvinyl alcohol solution. From those data, it was concluded that the higher value of LDF than that for Newtonian liquids was due to the formation of aggregation structure or inhomogeneous fine clots in the liquid, which was accompanied with the appearance of the elasticity. Show more

Keywords: Damped oscillation rheometer, Blood coagulation, Fibrinogen solution, Viscoelasticity

DOI: 10.3233/BIR-1988-251-238

Citation: Biorheology, vol. 25, no. 1-2, pp. 289-295, 1988

Authors: Fukada, Eiichi | Ando, Yutaka

Article Type: Research Article

Abstract: An optically active polymer, poly-β -hydroxybutyrate(PHB), is produced in cytoplasm of various bacteria. The bending piezoelectric effect was observed in oriented films of PHB. The coefficient between the electrical polarization and the stress gradient was found to be in the order of 10−18 Cm/N, which was similar to the value reported for bone. Anisotropy in the value of the coefficient was also observed.

Keywords: Bending piezoelectricity, Poly-β-hydroxybutyrate

DOI: 10.3233/BIR-1988-251-239

Citation: Biorheology, vol. 25, no. 1-2, pp. 297-302, 1988