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Biorheology is an international interdisciplinary journal that publishes research on the deformation and flow properties of biological systems or materials. It is the aim of the editors and publishers of
Biorheology to bring together contributions from those working in various fields of biorheological research from all over the world. A diverse editorial board with broad international representation provides guidance and expertise in wide-ranging applications of rheological methods to biological systems and materials.
The aim of biorheological research is to determine and characterize the dynamics of physiological processes at all levels of organization. Manuscripts should report original theoretical and/or experimental research promoting the scientific and technological advances in a broad field that ranges from the rheology of macromolecules and macromolecular arrays to cell, tissue and organ rheology. In all these areas, the interrelationships of rheological properties of the systems or materials investigated and their structural and functional aspects are stressed.
The scope of papers solicited by
Biorheology extends to systems at different levels of organization that have never been studied before, or, if studied previously, have either never been analyzed in terms of their rheological properties or have not been studied from the point of view of the rheological matching between their structural and functional properties. This biorheological approach applies in particular to molecular studies where changes of physical properties and conformation are investigated without reference to how the process actually takes place, how the forces generated are matched to the properties of the structures and environment concerned, proper time scales, or what structures or strength of structures are required.
Biorheology invites papers in which such 'molecular biorheological' aspects, whether in animal or plant systems, are examined and discussed. While we emphasize the biorheology of physiological function in organs and systems, the biorheology of disease is of equal interest. Biorheological analyses of pathological processes and their clinical implications are encouraged, including basic clinical research on hemodynamics and hemorheology.
In keeping with the rapidly developing fields of mechanobiology and regenerative medicine,
Biorheology aims to include studies of the rheological aspects of these fields by focusing on the dynamics of mechanical stress formation and the response of biological materials at the molecular and cellular level resulting from fluid-solid interactions. With increasing focus on new applications of nanotechnology to biological systems, rheological studies of the behavior of biological materials in therapeutic or diagnostic medical devices operating at the micro and nano scales are most welcome.
Abstract: Wall shear rates in arterioles and capillaries in the surface of exposed bull frog lung were estimated to be 436 and 975 sec−1 , respectively, at the intra-lung pressure at which a maximum flow velocity was observed. These high shear rates will probably permit an orientation of erythrocytes in a high degree. An orientation of erythrocytes was confirmed at a wall shear rate smaller than 16 sec−1 by means of a microscope connected with a video camera system. Erythrocytes kept their long axis along the direction of the overall blood flow, even when the blood flow transiently stopped flowing…during the diastolic phase. The orientation of erythrocytes in such a high degree will be effective to reduce the blood flow resistance in pulmonary microvessels.
Abstract: Important cellular functions, such as rheological properties of cells are presumably related to the membrane lipid fluidity which may be approached by the use of fluorescence polarization method. However, biological membranes represent very heterogenous media and the knowledge of the fluidity of membrane compartments requires the use of different probes. Two fluorescent probes,DPH and its cationic derivative, TMA-DPH, have been employed to probe the lipid fluidity of human platelets and red cell membranes. The results show that the informations given by DPH and TMA-DPH can present important differences, suggesting that DPH and TMA-DPH are localized in different regions of cell…membranes. In an attempt to investigate relations between lipid fluidity and rheological properties of red cells, the behavior of probes was studied in a “Couette” viscometer with a device for studying the emissive properties of probes when red cell membranes are under shear conditions.
Abstract: Platelets were found to be stimulated by high shear exposure for 5 minutes. Using a new technique, shear stresses up to 255 N/m2 , acting for pathophysiological relevant intervals of milliseconds did not elicit active release of β -TG, beyond the amount explained by LDH-monitored passive lysis. Neither the plasma level of ionized calcium (citrate vs heparin anticoagulation), nor a potent platelet inhibiting agent like PgI2 (20 nM) did Significantly alter platelet responses to short acting high shear stress. Ultrastructural signs of activation could largely be suppressed by adding ADP-scavengers. Direct “shear induced platelet activation” appears rather unlikely…and mostly reducable to secondary biochemical activation by mediators, probably adenine nucleotides, from a small percentage of passively shear-destroyed platelets. The extent of this secondary activation is largely a matter of experimental conditions.
Abstract: The non-newtonian viscous and elasto-thixotropic properties of native and lyophilized pathological bronchial mucus and of polymer solutions (3% and 6% PIB in decalin) used as mucus analogs were analyzed using a cone-plate Carri-Med rheometer and a Couette viscoelastometer that we have specifically developed for measuring the rheological properties of bronchial mucus in clinical practice. The master curves obtained for apparent viscosity under steady conditions as a function of shear rates (γ ˙ : 2.6×101 to 6.9×10 sec−1 ) were fairly similar, whatever the apparatus used. Under transient conditions, at low shear rate (γ ˙…< 1.4 sec−1 ), PIB and mucus exhibited a typical viscoelastic behavior: the shear stress increased slightly up to a steady-state value. At higher γ ˙ , a transitory overshoot of σ characteristic of the elastothixotropic systems appeared. Such a behavior can be interpreted as resulting from structural changes such as formation and rupture of the three-dimensional network present in bronchial mucus as in polymer solutions.
Abstract: In order to define various aspects of platelet rheological activation, samples of whole blood and platelet-rich plasma (PRP) from the same donors were subjected for 5 min to shear rates increasing from 10 to 10000 sec−1 (shear stresses from 10−2 to 30 Pa approximatively) in a Couette type viscometer. The following parameters were measured: erythrocyte hemolysis; lactic dehydrogenase activity; plasma B-Thromboglobulin(B-TG); adenine nucleotides, and platelet photometric aggregation. The experimental results reveal that: In whole blood, hemolysis only reached at maximum 2% of the total hemolysis. Plasma LDH activity increased regularly beyond 500 sec−1 , in close correlation…with B-TG plasma concentration. In contrast, ADP and ATP levels remained stable up to 1000 sec−1 then increased slowly. In PRP, the LDH, ADP and ATP levels remain practically stable up to shear rates around 5000 sec−1 . In contrast, B-TG appeared to be released in plasma at shear rate values of 3000 sec−1 and its progression is only correlated with the other parameters, when the platelet lysis occurred. Finally, a rapid and complete inhibition of platelet aggregation to ADP was observed from 5000 sec−1 .
Keywords: Rheology, red blood cell, platelet, shear activation
vol. 22, no. 5, pp. 425-435, 1985
Abstract: The predilection sites of arterial thrombosis are characterized by local increase in wall shear stress, flow separation with eddy formation and stagnation point flow. The defenders of high shear, as well as those of low shear theory of thrombogenesis, point to correlations of predilection sites and the respective flow abnormalities. Experimental evidence is provided, that high shear rates can damage both red cells and platelets, that lysed red cells constitute a potent platelet stimulant, due to their content of adenine nucleotides, and that platelets do not adhere to surfaces unless transported onto them by convective motion, the effectiveness of the…platelet-wall interaction being enhanced by platelet activation. Based on these facts, a resolution of the contrast between high and low shear theory of thrombosis is attempted in a way, that the different flow regimens, with blood cells sequentially passing them, are each considered important and interdependent steps on the way to thrombosis.