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At least 1,171 records · Page 65Linked to original sources
PubMed1998

Effects of glucose in drinking water on the changes in whole blood viscosity and plasma osmolality of broiler chickens during high temperature exposure.

This study was conducted to elucidate the influence of glucose in drinking water on whole blood viscosity and plasma osmolality of broilers during high temperature exposure. Two groups of birds, which had ad libitum access to either a 4% glucose-water solution (Group G) or tap water (Group W), were exposed simultaneously to 30 C from 0300 h for 12 h each day for 3 d. During the experimental period, Group G birds had greater metabolic energy intake and body weight gain than Group W. Hematocrit and whole blood viscosity decreased significantly at 30 C compared to controls at 20 C in Group W, whereas, in Group G, no changes were found for these two variables. Plasma osmolality also decreased at 30 C compared to 20 C in Group W, whereas no change was noted in this variable in Group G. However, at 20 C, plasma osmolality was significantly higher in Group W than in Group G, but no difference was observed between the two groups at 30 C. Plasma protein concentration decreased during exposure to 30 C in both groups, but the decrease tended to be greater in Group W than in Group G. These results suggest that glucose intake may alleviate the influence of heat stress on whole blood viscosity and plasma osmolality.

Animals↗
PubMed1984

The correlation of clinical assessment of synovial fluid with its measured viscosity.

The viscosity of 10 specimens of rheumatoid synovial fluid was assessed using side-room tests as well as being measured in a viscometer. All of the tests, and particularly the 'mucin clot', correlated well with measured viscosity. We conclude that the mucin clot test does indeed reflect viscosity and can demonstrate the presence of inflammatory joint disease.

Arthritis, Rheumatoid↗
PubMed1993

Viscosity of plasma and blood in rheumatoid arthritis.

Blood rheology was studied in 130 consecutive RA outpatients, 33 with and 97 without extra-articular disease (EAD), and compared with that in 88 blood donors. All rheological variables were significantly elevated in the RA patients compared with the controls. Painful joint count (PJC), morning stiffness (MS) and radiographic changes (RC) correlated significantly with plasma viscosity (PV), CRP, ESR and fibrinogen concentration (FC), but only in the group without EAD. Corrected blood viscosity (CBV) at a shear rate of 92/s correlated significantly only with MS. Multiple regression with PJC, MS and RC as dependent variables showed significant associations of PJC with PV, MS and CRP and RC with PV. Multiple regression with PV as the dependent variable showed significant associations with FC and IgG. RA patients with EAD had higher PV (P < 0.01), CBV at 92/s (P < 0.05) and ESR (P < 0.05) than the RA patients without EAD. Differences in profiles of viscosity variables between subgroups of EAD in RA patients were observed.

Adult↗
PubMed2004

Effects of a moderate-intensity aerobic program on blood viscosity, platelet aggregation and fibrinolytic balance in young and middle-aged sedentary subjects.

Regular physical activity is associated with reduced risk of cardiovascular disease although the mechanisms are unclear. Recent population-based studies suggest that the effect of physical activity may be at least partly a result of action on hemostasis. We tested the hypothesis that moderate-intensity aerobic training improves fibrinolytic activity and reduces platelet aggregation and blood viscosity. In 15 young (11 males and four females; age, 24-32 years) and 15 middle-aged (11 males and four females; age, 45-65 years) healthy, non-smoker, sedentary subjects, the maximum oxygen consumption, adenosine diphosphate-induced platelet aggregation, tissue plasminogen activator and plasminogen activator inhibitor type 1, antigen, hematocrit and blood viscosity were measured at baseline and after 12 weeks of aerobic exercise training (40 min three times a week at a training intensity adjusted to 60% of the individual heart rate reserve). After training, the maximum oxygen consumption was increased by 9% (P < 0.01) in the young group and by 7.3% (P < 0.05) in the middle-aged group. Adenosine diphosphate-platelet aggregation significantly decreased in the young (-30%; P < 0.05). The middle-aged group showed a 10.4% decrease in hematocrit (P < 0.05), and a 11.6 and 16.6% decrease in blood viscosity at 450/s and at 90/s rates of shear, respectively (P < 0.05), while the plasminogen activator inhibitor type 1 antigen plasma level increased 135% (P < 0.01). These data, some not consistent with others, only partially support the hypothesis that the beneficial effects of physical activity result from action on hemostatic balance. In particular, the changes in the fibrinolytic system in middle-aged subjects might suggest increased thrombotic risk. Thus a simple, straightforward conclusion is not possible at present, and further studies are required.

Adenosine Diphosphate↗
PubMedDate not supplied

Blood viscosity changes after trauma. Use of dextran-40 in correction of microcirculatory insufficiency.

Trauma causes a definite increase in packed cell viscosity and intravascular cellular aggregation. As a result, total body oxygen consumption decreases markedly. When packed cell viscosity is lowered by infusion of dextran-40, total body oxygen consumption progressively increases to normal values. It does not appear unreasonable to conclude that in traumatized patients, restoration of microcirculatory blood flow is of great importance in reestablishing an effective circulating blood volume and that normalization of blood viscosity after trauma may be of considerable benefit.

Blood Flow Velocity↗
PubMedDate not supplied

The effects of media viscosity on hemodynamics in selective arteriography.

Radiographic contrast media used for arteriography are generally more viscous than plasma or blood; however, little consideration is given to the hemodynamic effects of contrast media viscosity. In this study, in vivo and in vitro injection of isotonic solutions of saline and polyvinylpyrrolidone, having viscosities from 0.8 to 26 centipoise, have been made. The results demonstrate that, when the viscous saline reaches the microcirculation, the resistance to flow increases. The viscous saline thus significantly decreases flow immediately after the injection. At that time the pressure in the artery equals aortic pressure, but the local vascular resistance is elevated because of the viscous material present in the arterioles. Viscous contrast media would cause similar hemodynamic changes during and immediately following an injection. The effects of contrast media hypertonicity, however, modify the viscosity-related changes shortly after the contrast media reaches the capillaries.

Angiography↗
PubMed1991

The effects of a hyperosmolar intravenous contrast medium on blood viscosity.

The effects of the hyperosmolar contrast medium, diatrizoate meglumine (Renografin-76) on blood viscosity and other metabolic parameters were measured in 20 immature piglets. Intravenous contrast medium caused a significant (P less than .5) increase in serum osmolality, cardiac output, and urine output, and a decrease in hematocrit. There was a fall in blood viscosity that was not statistically significant. These changes, which are attributed to an acute shift of fluid into the hyperosmolar vascular compartment, were greatest at 3 minutes following injection and subsequently returned towards baseline levels. We conclude that blood viscosity is not increased following intravenous injection of hyperosmolar radiocontrast media.

Animals↗
PubMed1981

Increased blood viscosity in patients with Legg-Perthes disease: a preliminary report.

Based on studies by others, it appears that Legg-Perthes disease is an avascular necrosis of the femoral head due to occlusion of the blood supply. In an effort to delineate the pathogenesis of the disorder, we determined blood viscosity and percent platelet aggregation in 22 patients with Legg-Perthes disease and 21 control patients. Statistically significant higher blood viscosities were found in our patients with Legg-Perthes when compared with normals. No difference was found in the platelet aggregation studies. In accordance with Poiseuille's law, we propose that increased blood viscosity in patients with the affliction could lead to a diminution in blood flow to the capital femoral epiphysis, ultimately resulting in osteonecrosis and symptomatic manifestations of the disease.

Adolescent↗
PubMed2004

Linear dependence of surface drag on surface viscosity.

Flow at an air-water interface is limited by drag from both the two-dimensional surface and three-dimensional subphase. Separating these contributions to the interfacial drag is necessary to measure surface viscosity as well as to understand the influence of the interface on flow. In these experiments, a magnetic needle floating on a monolayer-covered air-water interface is put in motion by applying a constant magnetic force, F(m). The needle velocity varies exponentially with time, reaching a terminal velocity F(m)/C, in which C is the drag coefficient. C is shown to be linearly proportional to the monolayer surface viscosity, eta(s), for dipalmitoylphosphatidylcholine monolayers in the condensed phase by comparison to surface viscosity measured by channel viscometry.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Effect of oxpentifylline on blood viscosity and cerebral blood flow in man.

The effects of intravenous oxpentifylline on blood viscosity and cerebral blood flow were studied in eight patients with cerebrovascular disease using a double-blind placebo controlled design. A single dose of 200 mg oxpentifylline in 10 ml saline was given by intravenous injection over 10 min and compared with 10 ml saline alone. Whole blood and plasma viscosity were measured in a Contraves LS 30 coaxial viscometer at shear rates of 0.7 and 94.5 s-1. Cerebral blood flow was measured by the non-invasive intravenous xenon133 clearance method. The measurements were made before and then 30 min after the start of the injection of drug or saline alone. Oxpentifylline was found to have no significant effect on blood viscosity or cerebral blood flow.

Adult↗
PubMed1979

The effect of iron deficiency on whole blood viscosity in polycythaemic patients.

Iron deficiency leads to a significant increase in whole blood viscosity in polycythaemic patients. This can be corrected by simultaneous treatment with iron and venesection. In patients with polycythaemia secondary to hypoxia the haemoglobin concentration may be increased by treating coexisting iron deficiency, without altering the whole blood viscosity, thus increasing oxygen availability to the tissues. Values for whole blood viscosity can be derived from the peripheral blood Hb and MCH, allowing therapeutic decisions to be made on the basis of a simple haematological examination.

Adult↗
PubMed1980

Management of relative polycythaemia: studies of cerebral blood flow and viscosity.

Cerebral blood flow has been shown to be reduced in a group of patients with high packed cell volume due to a reduced plasma volume (relative polycythaemia). 500 ml of intravenous Dextran 40 resulted in a significant fall in PCV and whole blood viscosity with a concomitant rise in cerebral blood flow (CBF). This effect, however, lasted less than 24 h. Oral fludrocortisone therapy (0.2 mg daily) resulted in no definite change in either PCV, viscosity or CBF. Venesection brought about a significant fall in PCV and whole blood viscosity with a significant rise in CBF. Of the methods used, venesection was the only practical long-term method of lowering PCV in this group of patients.

Aged↗
PubMed1988

Viscosity-dependent energy barriers and equilibrium conformational fluctuations in oxygen recombination with hemerythrin.

The recombination kinetics of photo-dissociated oxyhemerythrin (Sipunculus nudus) have been investigated between 298 K and 90 K. Fast geminate recombinations compete with oxygen escape into the solvent, from which a subsequent slower bimolecular rebinding takes place. In phosphate buffer (pH 7.7) at 278 K, the fast and slow processes are exponential and have comparable amplitudes. Whereas the oxygen escape rate rapidly decreases upon increasing the viscosity, the inward rate from the solvent is found to be independent of viscosity, up to about 50 cP (50 mPa.s). The data suggest that a Brownian-motion-driven displacement of one or several side-chain residues is implied in oxygen escape from within the protein and also that hemerythrin undergoes a conformational change in the deoxy state. At higher viscosities and lower temperature only the geminate phase is observed and the kinetics progressively depart from an exponential. Below about 130 K, the kinetics resemble those reported in the literature for heme proteins. They are consistent with a temperature-independent non-equilibrium frozen distribution of conformational substates. However, between 190 K and 130 K, the profile of the kinetics is invariant on a log/log plot and the results simply differ by a translation along the log t axis. It is shown that this property is expected only for a temperature-dependent distribution of substates in a Boltzmann equilibrium. From room temperature, where rebinding is exponential, down to the 'freezing' temperature, the geminate recombinations display a variety of kinetic laws. It can be shown, however, that for a broad class of substate distributions, the initial slope of the kinetic plot follows an Arrhenius relationship. The activation energy is equal to that of the exponential rate constant measured at high temperature. This result establishes the conditions under which protein data obtained from low-temperature kinetics can be extrapolated to physiological temperature.

Animals↗
PubMed1978

Raynaud's disease: reduced hand blood flows with normal blood viscosity.

Hand blood flows and the blood and plasma viscosities were measured in patients with Raynaud's disease in an attempt to identify the mechanism of the episodic vascular insufficiency. Using venous occlusion plethysmography the following observations were made: (1) the hand blood flows were significantly less than in normals at 32 degrees, 27 degrees and 20 degrees C; (2) the percentage decrease in flow with cooling was greater in normals and (3) cooling of one hand from 32 degrees to 27 degrees C caused an abnormal decrease in flow through the contralateral hand. Using a rotational viscometer the blood and plasma viscosities were found to be normal at both high and low shear rates. The percentage increase in the blood viscosity with cooling from 35 degrees to 25 degrees was also normal. These studies demonstrate an increased constrictive response of the cutaneous vasculature of the hand to both local and reflex stimulation, and exclude a rheological abnormality, under conditions similar to those of the present study.

Adolescent↗
PubMed1988

Maternal blood viscosity and uteroplacental blood flow velocity waveforms in normal and complicated pregnancies.

According to the Poiseuille-Hagen law, viscosity influences flow resistance. A possible effect of blood viscosity upon the resistance index of the uteroplacental circulation as measured by continuous wave Doppler ultrasound was investigated in 50 pregnant women. It was found that blood viscosity variables explained only about 10% of the variation in the resistance index in all patients, which was not statistically significant. It is suggested, therefore, that the vascular contribution to flow resistance may be more important.

Blood Flow Velocity↗
PubMed1989

Correlation between Doppler flow velocity waveforms and cord blood viscosity.

The contribution of rheological factors to the impedance of blood flow in the umbilical artery as determined by continuous-wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55% of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placental arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1998

Effect of temperature and viscosity on the motility of the spirochete Treponema denticola.

Treponema denticola is an oral spirochete associated with periodontal diseases. Because bacterial motility is likely to be a potential virulence factor, we investigated the effect of viscosity and temperature on cell speed. In agreement with the work of others, translational motility was a function of the macroscopic viscosity of the medium. In addition, we found that although the speed of spirochetes was slow at 25 degrees C (4 microns s-1), it increased quite markedly at 35 degrees C (19 microns s-1). The results indicate that both viscosity and temperature are critical factors in T. denticola translational motility.

Culture Media↗
PubMed1980

Cerebral blood flow, haematocrit and viscosity in subjects with a high oxygen affinity haemoglobin variant.

The cerebral blood flow is low in primary polycythaemia, and it has been suggested that this is due to the increase in viscosity which accompanies the elevated haematocrit. In the present study cerebral blood flow has been measured by a non-invasive 133Xenon technique in six subjects with an elevated haematocrit secondary to a haemoglobin variant with increased oxygen affinity. Flow was significantly higher than normal and 81% higher than in 11 subjects of comparable age, matched for haematocrit and viscosity, but without the haemoglobin variant. In patients with this unusual type of polycythaemia, cerebral blood flow is high despite the elevated blood viscosity and the implications of these results are discussed.

Adult↗