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At least 19 recordsLinked to original sources
PubMed1994

Blood viscosity and plasma viscosity in patients with sudden deafness.

Blood viscosity and plasma viscosity were measured in 51 patients with sudden deafness (SD) and 70 controls with normal hearing. Blood viscosity and plasma viscosity in patients with SD at their first medical examination were significantly higher than in the control group. The difference in viscosimetry results between the two groups was greater at higher shear rates. The data obtained in viscosimetry and pure-tone audiometry were analyzed after dividing the patients into a high viscosity group and a normal viscosity group. The correlation between average hearing level in pure-tone audiogram and blood viscosity or plasma viscosity was positive. The values of the O2-transport capacity of the blood demonstrated a negative correlation with average hearing level in patients with SD before treatment. During the course of treatment, blood viscosity and plasma viscosity decreased with the improvement of hearing impairment. When the distribution of average hearing level was 40 to 79 dB, a few of the patients with "recovery" or "good improvement" and most of patients with "fair improvement" or "no change" belonged to the low viscosity group. And, most of the patients with flat type hearing impairment and a few patients with high tone type hearing impairment belonged to the high viscosity group. These results suggest that many patients with SD have increased blood viscosity and plasma viscosity, and that this increase may play a significant role in the etiology of SD. There are also some differences in etiologic factors concerning type of hearing impairment and prognosis. In conclusion, the present study points to the importance of measuring blood viscosity and plasma viscosity in patients with SD, since blood and/or plasma viscosity may be involved in its etiology and prognosis.

Adult↗
PubMed2002

Hypertriglyceridemia is associated with an elevated blood viscosity Rosenson: triglycerides and blood viscosity.

Elevated blood viscosity is a predictor of cardiovascular disease. The major determinants of blood viscosity are hematocrit and plasma viscosity. Plasma triglycerides elevate plasma viscosity; however, the contribution of plasma triglycerides to blood viscosity after adjustment for other major covariates has not been reported. This cross-sectional study of 257 adult subjects evaluated the associations between fasting plasma lipids, fibrinogen, total serum protein, hematocrit and blood viscosity. Blood viscosity was measured at 37 degrees C with a coaxial cylinder microviscometer at shear rates of 100 and 1 s(-1). Blood viscosity values are reported both as uncorrected measurements and measurements corrected to a hematocrit of 45% by a regression equation. Uncorrected blood viscosity at a shear rate of 100 s(-1) was significantly associated with triglycerides, fibrinogen, high density lipoprotein (HDL) cholesterol, total serum protein, and hematocrit using stepwise multivariate regression analysis. When corrected blood viscosity at 100 s(-1) was the dependent variable, there were statistically significant associations with triglycerides, HDL cholesterol, and total serum protein. Corrected blood viscosity at 1 s(-1) was significantly associated with triglycerides, fibrinogen, total serum protein, and an indicator variable for diabetes mellitus. This study supports an additional mechanism whereby triglycerides may contribute to cardiovascular risk.

Adult↗
PubMed1986

Viscosity of concentrated solutions and of human erythrocyte cytoplasm determined from NMR measurement of molecular correlation times. The dependence of viscosity on cell volume.

Metabolically active human erythrocytes were incubated with [alpha-13C]glycine which led to the specific enrichment of intracellular glutathione. The cells were then studied using 13C-NMR in which the longitudinal relaxation times (T1) and nuclear Overhauser enhancements of the free glycine and glutathione were measured. The T1 values of labelled glycine were also determined in various-concentration solutions of bovine serum albumin and glycerol and also of the natural abundance 13C of glycerol in glycerol solutions. From the T1 estimates the rotational correlation time (tau r) was calculated using a formula based on a model of an isotropic spherical rotor or that of a symmetrical ellipsoidal rotor; for glycine the differences in estimates of tau r obtained using the two models were not significant. From the correlation times and by use of the Stokes-Einstein equations viscosity and translational diffusion coefficients were calculated; thus comment can be made on the likelihood of diffusion control of certain enzyme-catalysed reactions in the erythrocyte. Bulk viscosities of the erythrocyte cytoplasm and the above-mentioned solutions were measured using Ostwald capillary viscometry. Large differences existed between the latter viscosity estimates and those based upon NMR-T1 measurements. We derived an equation from the theory of the viscosity of concentrated solutions which contains two phenomenological interaction parameters, a 'shape' factor and a 'volume' factor; it was fitted to data relating to the concentration dependence of viscosity measured by both methods. We showed, by using the equation and interaction-parameter estimates for a particular probe molecule in a particular solution, that it was possible to correlate NMR viscosity and bulk viscosity; in other words, given an estimate of the bulk viscosity, it was possible to calculate the NMR 'micro' viscosity or vice versa. However, the values of the interaction parameters depend upon the relative sizes of the probe and solute molecules and must be separately determined for each probe-solute-solvent system. Under various conditions of extracellular osmotic pressure, erythrocytes change volume and thus the viscosity of the intracellular milieu is altered. The volume changes resulted in changes in the T1 of [alpha-13C]glycine. Conversely, we showed that alterations in T1, when appropriately calibrated, could be used for monitoring changes in volume of metabolically active cells.

Cytoplasm↗
PubMed1981

Effects of increased plasma viscosity and red blood cell aggregation on blood viscosity in vivo.

The effects of increased plasma viscosity and induced red blood cell (RBC) aggregation on apparent viscosity of blood in vivo in the skeletal muscle of the dog were studied. Apparent viscosity in vivo was determined in the isolated and vasodilated calf muscles of one hindlimb by comparing pressure-flow relationships for RBC suspensions with pressure-flow relationships for a Newtonian solution of known viscosity. RBC suspensions of increased plasma viscosity with and without RBC aggregation were obtained by substituting plasma with isoviscous solutions of high- and low-molecular-weight dextran in saline. Hematocrits of the suspensions were adjusted to either 45 or 60%. The viscosities of the suspensions in vitro were determined in a Wells-Brookfield viscometer. Apparent viscosity of blood in vivo was found to be mainly dependent on the viscosity of plasma. RBC aggregation had no significant influence on the viscosity in vivo.

Animals↗
PubMed1978

Effect of ionic and non-ionic contrast media on whole blood viscosity, plasma viscosity and hematocrit in vitro.

The effect of the ionic contrast media diatrizoate, iocarmate and metrizoate and the non-ionic metrizamide on whole blood viscosity, plasma viscosity and hematocrit was investigated. All the contrast media increased whole blood and plasma viscosity and reduced the hematocrit. The whole blood viscosity increased with increasing osmolality of the contrast medium solutions, whereas the plasma viscosity increased with increasing viscosity of the contrast medium solutions. The higher the osmolality of the contrast media, the lower the hematocrit became. The normal shear-thinning (decreasing viscosity with increasing shear rate) property of blood was reduced when contrast medium was added to the blood. At 50% volume ratio (contrast medium to blood), the ionic contrast media converted the blood into a shear-thickening (increasing viscosity with increasing shear rate) suspension, indicating a marked rigidification of the single red cell, while the non-ionic contrast medium still produced shear-thinning, indicating less rigidification of the red cell (p less than 0.01).

Blood Viscosity↗
PubMed1983

[Relation of blood viscosity, plasma viscosity and hematocrit].

The results from 398 consecutive measurements of blood viscosity, plasma viscosity and hematocrit were submitted to a statistical analysis. Hematocrit appeared to be the main determinant of blood viscosity, even though its influence was not so strong as illustrated in previous investigations. The correlation between blood viscosity and hematocrit appeared strictly connected with the red cell amount of the blood sample, being higher when the latter exceeded its physiological range; this correlation disappeared when red blood cell amount was strongly reduced, while the correlation between plasma viscosity and blood viscosity had an opposite behaviour. From these results we can conclude that correlations between hematocrit and plasma viscosity with blood viscosity have opposite trends and that a reciprocal interference is often present.

Blood Viscosity↗
PubMed1987

Changes in the viscosity of the plasma membrane of flounder (Platichthys flesus L.) erythrocyte induced by varying the content of membrane cholesterol or by benzyl alcohol. Correlation of the activity of the intrinsic Mg2+-ATPase and the viscosity.

The order parameter S and the correlation time tau from the ESR-spectra of 5-DS and 5-DD, respectively, are used as measures of the viscosity of the plasma membrane. It is suggested that the membrane undergoes a thermotropic phase transition which correlates with a change of the activation energy of the (Na+ + K+)-ATPase but not of the Mg2+-ATPase. The viscosity varies almost proportionally with the amount of cholesterol in the membrane when 0 less than mg C/mg PL less than 0.5. It is suggested that cholesterol is uniformly distributed in the membrane when mg C/mg PL less than 0.5 and that cholesterol-rich domains appear when mg C/mg PL greater than 0.5. Benzyl alcohol decreases the viscosity of the membrane. The effect depends on the presence of cholesterol in the membrane. The onset of the effect of benzyl alcohol on the native membrane is delayed--in terms of alcohol concentration--relative to the cholesterol-depleted membrane. Benzyl alcohol affects only the outer part of the membrane bilayer. Changes of the viscosity and of the activity of the Mg2+-ATPase are proportional. The effect of cholesterol-depletion on the activity of the Mg2+-ATPase cannot be ascribed only to the simultaneous lowering of the viscosity.

Animals↗
PubMed1992

Spectral characterization of the effect of viscosity on Fura-2 fluorescence: excitation wavelength optimization abolishes the viscosity artifact.

A systematic study of the spectral characteristics of the viscosity artifact in Fura-2 based [Ca2+] measurements reveals that, by selecting excitation wavelengths approximately 10 nm longer than those routinely employed and modestly reducing excitation bandpasses, the magnitude of the artifact can be reduced to experimentally undetectable levels without greatly impairing [Ca2+] measurements. The feasibility of this approach was confirmed on a ratio imaging microscope; the magnitude of the artifact observed in dextran-conjugated Fura-2 solutions prepared in water or in 50% sucrose was not statistically significant using an excitation wavelength pair of 361/389 nm, whereas at 350/380 nm [Ca2+] was underestimated by 34% in the higher viscosity solution. Thus, provided potential pitfalls are taken into account, a simple change in imaging protocol can avoid the viscosity artifact without recourse to correction factors. This approach may be employed either routinely, or else merely to test whether apparent [Ca2+]i differences observed at more conventional wavelengths arise from the viscosity artifact.

Artifacts↗
PubMed1993

Viscosity sensing with lamb-wave microsensor: dimethylsulfoxide solution viscosity as a function of temperature.

Recently, a new microsensor employing low-velocity ultrasonic Lamb waves was developed and demonstrated to be capable of measuring the viscosity of solutions in small volumes. The microsensor, when attached to a temperature-controlled stage, can measure viscosity as a function of temperature. In this investigation, the ultrasonic Lamb-wave oscillator is employed to experimentally measure the viscosity of dimethylsulfoxide (Me2SO) solutions as a function of temperature. The microsensor and the experimental procedure are described and results for 1M, 3M, and 5M Me2SO aqueous solutions are presented. Dimethylsulfoxide is a compound commonly employed as a cryoprotectant in cryopreservation, the low-temperature preservation of biological materials. The temperature dependence of viscosity obtained through this study can be used in determining the probability for ice nucleation in biological materials, a parameter of importance during cryopreservation.

Calibration↗
PubMed1986

Sonically produced heat in a fluid with bulk viscosity and shear viscosity.

In a viscous fluid, sound produces heat in a spatial pattern which, in general, depends on the relative magnitudes of the shear viscosity coefficient eta and the bulk viscosity coefficient B'. It is well known that when the particle velocity components ui relative to Cartesian coordinates xi are given for an arbitrary sound field, or any field of flow, the volume rate of heat production qv can be determined from a dissipation function in the form B'T1 + eta T2. Here, T1 and T2 are quadratic functions involving derivatives of the type delta ui/delta xj. In this paper, examples are discussed for continuous monofrequency sound fields, including crossed plane waves, as well as focused and unfocused fields. In these examples, spatial distributions of the time-averaged quantity [qv] for media in which the loss mechanism is primarily bulk viscosity are compared to those for media in which shear viscosity dominates.

Acoustics↗
PubMed1982

Integral viscosity: a useful parameter in evaluating whole blood and plasma viscosities in health and disease.

An integral viscosity determination (Q) is proposed for whole blood (QB) and plasma (Qp). The integral viscosity determination was carried out at four shear rates in a Brookfield LTV Viscometer and calculation were obtained by means of a modification of Casson's mathematical model. Polycythemic and paraproteinemic patients resulted to be well differentiated from normals. The ratio QB/Qp represent a continuous sum of relative viscosities and may also supply information on erythrocytes deformability. Integral viscosity determinations are indicated for research purposes and for examining special cases.

Blood Viscosity↗
PubMed2003

Whole blood viscosity, plasma viscosity and erythrocyte aggregation in nine mammalian species: reference values and comparison of data.

In this study species-specific values for whole blood viscosity (WBV), plasma viscosity (PV) and erythrocyte aggregation (EA) were determined in a total of 360 animals. We used 40 individual adult animals of nine mammalian species: horse, pig, dog, cat, rat, cattle, sheep, rabbit and mouse. WBV measurements were carried out using a LS30 viscometer, PV was measured using OCR-D and EA was measured using a Myrenne aggregometer and the LS30 (aggregation index at low shear rate). At low shear rates (0.7 s(-1) and 2.4 s(-1)) haematocrit (Hct)-standardized (40 % Hct) samples showed a higher value of WBV and EA in horse, pig, dog and cat. In cattle, sheep, rabbit and mouse, EA and WBV were markedly decreased and EA was almost undetectable, although the plasma fibrinogen concentration was higher in these animals. Rats showed the highest WBV at low shear rate in native blood and WBV was not different from horse in Hct-standardized blood; however, EA was very low in the rat, a result that might be explained by mechanical or geometrical properties of the red blood cell. EA correlated with the plasma protein concentration in each species except dog and mouse. In horse, cattle and pig, EA correlated with the plasma fibrinogen concentration. At high shear rate (94 s(-1)), WBV was higher in cattle than cat and rat, and dog had higher values than horse, suggesting specific interspecies differences depending on low shear and high shear values of WBV, as a result of mechanisms that influence RBC flexibility. PV was highest in cattle and lowest in rabbit and mouse and did not correlate with WBV. Haemorheological parameters differed between the species. Each species has its own rheological fingerprint. The physiological significance of these variations among mammalian species has not yet been established. Viscosity contributes to endothelial cell shear stress. While haemorheological parameters differ across the species it may be postulated that factors influencing flow-mediated endothelial cell signal transduction are different among the species.

Animals↗
PubMed1995

Experimental retinal tolerance to very low viscosity silicone oil (100 cs) as a vitreous substitute compared to higher viscosity silicone oil (5000 cs).

We evaluated the toxicity of very low viscosity (100 centistokes) and higher viscosity silicone oil (5000 centistokes) in rabbit eyes as a short-to-long-term postoperative vitreous substitute (6 weeks to 5 months). Emulsification of 100-cs and 5000-cs silicone oil did not occur in eyes which were followed for as long as 5 months. No toxic effects to retinal cells were detected by light or electron microscopy. Because no toxic effects were seen with 100-cs silicone oil, it can be used in an outpatient setting as a short-term postoperative tamponading agent. Electroretinographic responses of silicone-injected eyes were normal.

Animals↗
PubMed1979

Is an average viscosity tenable in lipid bilayers and membranes? A comparison of semi-empirical equivalent viscosities given by unbound probes: a nitroxide and a fluorophore.

Relative variations of fluidity in bilayers and membranes are currently evaluated by numerous physical methods, but comparison between different systems remain difficult because the effects of order (anisotropy) and fluidity are involved in the diffusion coefficients for correlation times, or frictional coefficients) given by experiment. The present report represents an attempt to generalize the use of isotropic liquids as viscosity standards for disordered lipidic systems. It advances a simple check to verify the quasi-isotropic behaviour of probe environments and avoids the introduction of estimated values of the molecular dimensions in Perrin-Einstein relations. The equivalent viscosities obtained with 1,6-diphenyl hexatriene and with 2-pentyl-2'-butyl-4,4'-dimethyl oxazolidinoxyl are strikingly similar in egg lecithin vesicles above 0 degrees C, while in dipalmitoylphosphatidylcholine dispersions above their transition temperature, a discrepancy of about 30% seems to remain, even at high temperatures.

Chemical Phenomena↗
PubMed1999

Frequency-dependent shear viscosity, sound velocity, and sound attenuation near the critical point in liquids. III. The shear viscosity.

We compare theoretical results for the shear viscosity calculated in one-loop order within the field-theoretical method of the renormalization-group theory with experiments. Our expressions describe the nonasymptotic crossover in both temperature and density, and allow us to consider effects of finite gravitation and finite frequency at which the experiments are performed. In doing so we treat the critical exponent x(eta) of the shear viscosity as an independent parameter, keeping the one-loop value of the Kawasaki amplitude fixed. Within our model we also consider the temperature and density dependence of the thermal diffusion including gravitational effects.

Journal Article↗
PubMed1982

Whole-blood viscosity, as determined by plasma viscosity, haematocrit, and shear.

The viscometers used were: (a) a proprietary rotational coaxial-cylinder instrument; and (b) a Harkness capillary-tube viscometer. In (a), the mean shear-rate is selected by the choice of rotational speed. In (b), the wall shear-stress is selected by the choice of driving-pressure. If the viscosity is varied, the mean shear-rate varies, at constant wall shear-stress. The present paper attempts to show how, in principle, a complete family of "constant-rate" (rotational) curves can be computer-plotted from two suitably-spaced capillary-tube measurements. The reverse process, involving the correction of "playback" errors, is touched upon. A variable "Einstein coefficient" is derived from the principal parameters in the computer solution; and the basic problems of compatibility in "rates of shear" are discussed.

Blood Viscosity↗