Influence of physicochemical factors on rheology of human neutrophils.

The effects of variations in temperature, pH, and osmolality on the rheological properties of human neutrophils were determined by studying the cell deformation in response to aspirational pressure applied via a micropipette. The time history of the deformation was analyzed by the use of a standard solid viscoelastic model consisting of an elastic element K1 in parallel with a Maxwell element (an elastic element K2 in series with a viscous element mu). With changes in temperature over a range of 9-40 degrees C, only mu varied inversely with temperature, while K1 and K2 did not show significant alterations. Variations in pH over the range of 5.4-7.8 did not significantly affect the viscoelastic coefficients, but K1 and mu rose at pH 8.4. An increase in osmolality caused all three coefficients to rise, but a decrease in osmolality had relatively little effect on the coefficients. These changes in response to physicochemical variations serve to provide insights into the viscoelastic properties of neutrophils and their possible roles in health and disease.     

Characterization of the human blood plasma proteome

We describe methods for broad characterization of the human plasma proteome. The combination of stepwise immunoglobulin G (IgG) and albumin protein depletion by affinity chromatography and ultrahigh-efficiency capillary liquid chromatography separations coupled to ion trap-tandem mass spectrometry enabled identification of 2392 proteins from a single plasma sample with an estimated confidence level of > 94%, and an additional 2198 proteins with an estimated confidence level of 80%. The relative abundances of the identified proteins span a range of over eight orders of magnitude in concentration (< 30 pg/mL to approximately 30 mg/mL), facilitated by the attomole-level sensitivity of the analysis methods. More than 80% of the observed proteins demonstrate interactions with IgG and/or albumin, and the human plasma protein loss in the affinity chromatography/strong cation exchange/reversed-phase liquid chromatography-tandem mass spectrometry methodology was investigated in detail. The results of this study provide a basis for a wide range of plasma proteomics studies, including broad quantitation of relative abundances in comparative studies of the identification of novel protein disease markers, as well as further studies of protein-protein interactions.     

Effects of changes in osmolarity on isolated human airways

The effects of hypo- and hyperosmolarity on the function of isolated human airways were studied. Changes in osmolarity induced an increasing bronchoconstriction that was proportional to the magnitude of the change in osmolarity. Hypertonicity-induced airway narrowing resulted when buffer was made hypertonic with sodium chloride or mannitol but not with urea. The airways showed no tachyphylaxis to repetitive exposure to hypo- and hypertonic buffer of 200 and 600 mosM, respectively. The bronchoconstriction was not secondary to stimulation of H1 or leukotriene C4/D4 receptors or the release of prostaglandins in the preparation. The bronchoconstriction in hypotonic buffer was totally dependent on extracellular calcium, whereas in hypertonic buffer the bronchoconstriction seemed partially dependent on intracellular calcium release. Isoprenaline prevented the bronchoconstriction in hyper- or hypotonic buffer of 450 and 250 mosM but not in buffer of 600 and 150 mosM. It is concluded that hypo- and hypertonic buffers lead to bronchoconstriction via different mechanisms, which relate to influx of extracellular calcium in hyposmolar buffer and probably to release of calcium from intracellular stores in hypertonic buffer. In strongly hypertonic buffer, part of the bronchoconstriction may be due to osmotic shrinkage. The relevance of our data for the mechanism of bronchoconstriction after inhalation of hypo- or hypertonic saline depends on whether changes in osmolarity around the airway smooth muscle occur in asthmatics but not in normal subjects, and this has not yet been established.     

Modulation of spiking of neurons of the cat anterior hypothalamus induced by experimental shifts in the osmolarity of the blood plasma

We examined changes in the impulse activity (IA) generated by neurons of the anterior hypothalamus (including the preoptic region) resulting from infusions of hyper-and hypotonic NaCl solutions (3.0 and 0.2%, respectively; hyper-and hypoosmotic stimulations, respectively); the infused volumes did not exceed 200 μl. The effects of hyper-and hypoosmotic stimulations were studied in detail in 83 and 88 neurons, respectively. In 31.2% (26 cells) and 29.6% (26 cells) of the neurons of the above groups, these stimulations evoked changes in the IA frequency greater than +40 or −40% of the mean background IA frequency. In approximately 50% of the responding neurons in each group, such shifts in the IA frequency were observed in the course of infusions of test solutions (5 sec long) and within the subsequent 5 min after termination of the infusion. In another 50% of the neurons, changes in the IA frequency occurred within the afterperiod (30 sec long); these shifts could develop exclusively within the latter interval, or these changes accompanied an initial early reaction. In general, activating responses dominated (they were observed in 65% of the cases where test stimulations of both modalities were used). The possible aspects of the involvement of neurons of the anterior hypothalamus in the control of the water/salt balance in the organism are discussed. Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 40–45, January–February, 2006.     

Red blood cell mechanics and capillary blood rheology

Blood contains a high vol fraction of erythrocytes (red blood cells), which strongly influence its flow properties. Much is known about the mechanical properties of red cells, providing a basis for understanding and predicting the rheological behavior of blood in terms of the behavior of individual red cells. This review describes quantitative theoretical models that relate red cell mechanics to flow properties of blood in capillaries. Red cells often flow in single file in capillaries, and rheological parameters can then be estimated by analyzing the motion and deformation of an individual red cell and the surrounding plasma in a capillary. The analysis may be simplified by using lubrication theory to approximate the plasma flow in the narrow gaps between the cells and the vessel walls. If red cell shapes are assumed to be axisymmetric, apparent viscosities are predicted that agree with determinations in glass capillaries. Red cells flowing in microvessels typically assume nonaxisymmetric shapes, with cyclic “tank-treading” motion of the membrane around the interior. Several analyses have been carried out that take these effects into account. These analyses indicate that nonaxisymmetry and tank-treading do not significantly influence the flow resistance in single-file or two-file flow.     

Influence of microbial concentration on the rheology of non-Newtonian fermentation broths

The objective of this study was to quantify the effect of fungal biomass concentration on the rheology of non-Newtonian fermentation systems. Batch fermentations of Penicillium chrysogenum were carried out with glucose as the sole carbon source. The flow behavior of the system was characterized at various fermentation times and was adequately described by the power-law model. The apparent viscosity of the fermentation broth was significantly affected by biomass concentrations in the fermenter. Fermentation broths containing 17.71 g/l biomass as dry weight were characterized by an apparent viscosity of 0.25 Pa s at a shear rate of 50 s⁻¹. Microbial concentration also affected the power-law flow-behavior index and the consistency index. The value of the consistency index ranged from 0.002 Pa s ⁿ at a biomass concentration of 0.1 g/l to 6.14 Pa s ⁿ at a biomass concentration of 17.71 g/l. The flow-behavior index decreased from an initial value of 1 to a final value of 0.17. Simple empirical correlations have been proposed to quantify the dependence of the power-law parameters on fungal biomass concentration. Experimental data obtained in this study were accurately described by these correlations. The general applicability of these relationships was tested, using previously published rheological data on Aspergillus awamori and Aspergillus niger fermentation broths, and good agreement was seen between experimental data and the predictions from the empirical correlations. Received: 24 March 1998 / Received revision: 10 September 1998 / Accepted: 16 October 1998     

Influence of the human blood serum on contractility and beta-adrenoreactyvity of the isolated human myocardium

On strips of the isolated myocardium of right hearts auriculum of the 43 patients with ischemic illness of heart and 9 patients with heart diseases of various ethyology at statement venous canule during aorto-coronary shunting, estimated influence of adrenaline (10(-9)-10(-4) g/ml) on amplitude caused by electrostimulus (1H, 5ms, 25-30 V) contractions, and also inotropic and adrenomodulation activity of serum blood (in dilution 1 : 10000, 1: 1000, 1 : 500, 1: 100, 1 : 50, 1: 10 and 1 : 5) nonpregnant women. Direct dependence of amplitude of contraction on size of fraction of of blood emission on Teyholts is revealed. It means, that strips of right auriculum myocardium reflect contractility of a left ventriculum myocardium. Adrenaline in concentration 10(-7)-10(-6) g/ml dependent of dose raised amplitude of the caused contraction not influencing it in concentration of 10(-9) and 10(-8) g/ml (the constant of dissotiation has 2 x 10(-7) g/ml), that as a whole, speaks about decrease in efficiency of activation beta-AP. Blood Serum in dissolutions 1 : 10000-1 : 50 did not influence on amplitude of contraction, and in dissolutions 1 : 10 and 1 : 5 strengthened it, that speaks presence in blood the endogenous activator of myocyte contractility (EAMC). Serum showed beta-adrenomodulation activity that speaks presence in it endogenous sensitizer of beta-adrenoreceptors (ESBAR) and endogenous blocker of beta-adrenoreceptors (EBBAR). In particular, in experiences with adrenaline in subthreshold concentration (10(-8) g/ml) serum showed ESBAR-activity (in dissolutions 1 : 1000, 1 : 500, 1 : 100 and 1 : 50), and in experiences with adrenaline in as much as possible effective concentration (10(-6) g/ml) serum showed ESBAR-activity (in dissolutions 1 : 50 and 1 : 10) and EBBAR-activity (in dissolutions 1:500) Hence, containing in blood serum endogenous modulators of beta-adrenoreactivity - ESBAR and EBBAR can modulate efficiency of beta-adrenoreceptors activation of human cardiomyocytes. It speaks about perspectivity of application of ES BAR analogues in cardiology.