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PubMed1977

Effect of osmolality on red blood cell viscosity and transit through the lung.

The mean transit times of labeled red blood cells and albumin were compared in eight isolated rabbit lungs perfused with physiological albumin solutions. The osmolality of these solutions was adjusted by altering the concentration of sodium chloride. The ratios of the mean transit times of injected red blood cells to those of albumin increased as perfusion osmolality increased from hypotonic to isotonic and from isotonic to hypertonic levels. This change occurred despite a decline in pulmonary vascular resistance and red blood cell size as osmolality was increased. Red blood cell viscosity (determined with a cone-plate viscometer) increased with osmolality and it was concluded that this change of viscosity impaired the relative rate of red blood cell transit through the lungs. Passage of red blood cells through rigid homoporous membranes appeared to be related primarily to red cell size rather than vascosity. These observations suggest that both red blood cell viscosity and capillary distensibility play an important role in determining the velocity of red blood cells through the capillaries.

Animals↗
PubMed1975

Viscosity and osmolality of abnormal biles.

The mean osmolality of bile from the common bile duct is similar to that of bile obtained from the gallbladder of patients with non-functioning gallbladders, and both means are significantly lower than the mean of bile in functioning gallbladders. The mean viscosity of bile from both functioning and non-functioning gallbladders is on average considerably greater than that from the common bile duct, and the mean viscosity of bile from non-functioning gallbladders is greater than that from functioning ones. The presence of much mucus in gallbladders containing stones is likely to account for these differences in viscosity. The composition of the gallstones does not appear to have any influence on these observations, but the number of patients in each group is too small for the differences to be significant.

Bile↗
PubMed1976

Correlations between radioiodine uptake and blood viscosity factors in hypothyroid and hyperthyroid states.

A study of blood viscosity factors was undertaken in six hypothyroid and eleven thyrotoxic patients (females) whose thyroid function was defined by means of radioiodine uptake and protein bound (PB) 131I tests. Results indicate that: (i) significant differences exist between hypothyroid and hyperthyroid groups in correlations between radioiodine tests and blood viscosity factors (and fibrinogen levels); (ii) blood viscosity in thyrotoxic patients decreases as the degree of thyrotoxicity increases, while an opposite phenomenon is observed in hypothyroid patients, and (iii) degree of rigidity of the red cells is associated with the radioiodine uptake and PB 131I tests, the correlations being significant and negative.

Blood Viscosity↗
PubMed1994

Sex differences in susceptibility to etiologic factors for peripheral atherosclerosis. Importance of plasma fibrinogen and blood viscosity.

Cardiovascular risk factors in men, such as cigarette smoking, hypercholesterolemia, and hypertension, also increase risk in women, but the relative susceptibility to risk factors between the sexes is not established. Our aim was to investigate a wide range of possible etiologic factors in a single population study and identify those that were more strongly related to peripheral atherosclerosis in men or women. We studied personal factors (age and social class), lifestyle factors (smoking, exercise, alcohol intake, and dietary nutrients), and intermediary factors (obesity, diabetes, serum lipids, coagulation, and rheological factors). In the Edinburgh Artery Study in 1988 we measured cardiovascular risk factors in a random population sample of 1592 men and women aged 55 to 74 years. The ankle-brachial pressure index (ABPI), which is inversely related to the degree of peripheral atherosclerosis, was assessed in each subject. Lifetime cigarette smoking was correlated with a lower ABPI equally in men and women (r = -.27, P < .001). Dietary nutrients and alcohol intake were not related differently between the sexes with ABPI. However, recall of strenuous and moderate leisure time exercise during the age range of 35 to 45 years was related more strongly to a higher ABPI in men than in women (P < .05). Plasma fibrinogen, plasma viscosity, and blood viscosity were the only intermediary factors that had stronger univariate correlations with lower ABPI in men than in women. On multivariate analysis, the sex differences persisted for plasma fibrinogen (P < .05) and blood viscosity (P < .001); high-density lipoprotein cholesterol was related to ABPI in men only (sex difference, P < .1).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1981

Clinical relevance of blood viscosity and red cell deformability including newer therapeutic aspects.

Peripheral ischemia is mostly due to narrowing of the vessels, although blood supply is also influenced by the hemorheologic properties of the blood. Recent research has revealed that abnormally high blood viscosity can be a contributing cause in ischemia. Therapeutically decreasing the blood viscosity improves the ischemia by increasing flow through the narrowed vessels and may as such offer a valuable alternative to surgery. Different possible therapeutic approaches for decreasing blood viscosity and the related clinical evidence are discussed.

Adenosine Triphosphate↗
PubMed1992

Lowering of plasma viscosity by the oral administration of the glycosaminoglycan sulodexide in patients with peripheral vascular disease.

The aim of the double-blind, crossover, placebo-controlled study was to evaluate whether oral administration of sulodexide, a medium molecular weight glycosaminoglycan, had an effect on whole blood, plasma and serum viscosity, and/or plasma fibrinogen concentrations. The drug was administered orally at a dose of 500 lipoproteinlipase releasing units twice daily for 1 month to two groups of 20 patients with peripheral vascular disease; one group was administered a placebo--drug sequence and the other a drug--placebo sequence. Orally administered sulodexide had a marked effect on plasma viscosity and on plasma fibrinogen concentrations, whereas there were no effects on whole blood viscosity. No significant side-effects were observed. The fact that sulodexide was highly effective, even after oral administration, suggests it may be useful for the treatment of patients with atheromatous vascular diseases of the lower limbs requiring chronic therapy.

Administration, Oral↗
PubMed1979

A study of the effect of sulphinpyrazone ('Anturan') on blood viscosity.

A double-blind, placebo-controlled crossover study of the effect of sulphinpyrazone on blood viscosity and its determinants (haematocrit, plasma fibrinogen and plasma viscosity) was carried out in 7 healthy male volunteers. Apart from a transient rise in fibrinogen (p less than 0.05) after 3 days of sulphinpyrazone treatment, no significant change in viscosity factors was seen over a 14-day period.

Adult↗
PubMed1991

Effect of sulodexide on blood viscosity in patients with peripheral vascular disease.

Thirty patients with Stage II peripheral vascular disease were treated with sulodexide, a new, medium molecular weight glycosaminoglycan, and placebo using a double-blind, crossover study design. After a 1-month wash-out period, patients were treated for 1 month with one or other trial medication and then crossed over to the alternative preparation for a further month. Measurements were made at baseline and at the end of each treatment period of serum, plasma and whole blood viscosities (at various shear rates), fibrinogen levels and red cell filterability. Tolerance parameters were also assessed at the same times. The results showed that there were statistically significant reductions in plasma and whole blood viscosity and in fibrinogen levels after sulodexide, but not after placebo. Neither treatment had any marked effect on red blood cell filterability. Local and systemic tolerance of the treatment was excellent, and some patients reported an improvement in symptoms whilst they were taking sulodexide; this, however, could not be quantified in this study. It is suggested that the viscosity and fibrinogen reducing effect of sulodexide make it a useful form of treatment in patients with atheromatous vascular diseases of the lower limbs.

Adult↗
PubMed2006

Comparison of silicon oil removal with various viscosities after complex retinal detachment surgery.

BACKGROUND: Despite the progress in vitreoretinal surgery and the importance of silicone oil as an adjunct for the treatment of complex forms of retinal detachment, controversy still surrounds the issue of selecting the proper oil viscosity for clinical use. Herein, we evaluate the outcomes of retinal detachment (RD) surgery after removing silicone oils of different viscosities. METHODS: In this retrospective cohort study, eighty-two eyes with surgically re-attached retinas, of which 53 were filled with 5000 cs silicone oil and 29 with 1000 cs silicone oil were enrolled. We evaluated the outcomes and complications following silicone oil removal. Final anatomic success (stable re-attachment), final visual acuity (VA) and intraocular pressure (IOP)were recorded and analysed. RESULTS: Of 82 eyes, 41 had proliferative vitreoretinopathy (PVR), 24 were associated with intraocular foreign bodies, 10 had endophthalmitis and 7 had proliferative diabetic retinopathy with tractional retinal detachment. Prior to silicone oil removal, the retina was attached in all eyes, 29% had VA > or = 6/120 and 52% had IOP > or = 21 mmHg. After silicone oil removal, the retina remained attached in 59(72%) of the eyes, 34% had VA > or = 6/120 and 9% had IOP > or = 21 mmHg. Comparing 1000 cs and 5000 cs silicone oil filled eyes, redetachment occurred more frequently in the latter group especially in cases with associated PVR. Final VA worse than 6/120 was associated with initial VA < 6/120 (OR = 32.2 95%CI 7.4-140.2) and use of 5000 cs silicone oil (OR = 7.9 95%CI 1.9-32.2). No factor was significantly associated with final IOP > or = 21 mmHg. CONCLUSION: In complicated retinal detachment surgery, use of 5000 cs silicone oil may be associated with a poorer anatomic and visual outcome compared with 1000 cs silicone oil. However there was no difference between the two viscosities in IOP elevation. A randomized controlled study is necessary to further evaluate such a possibility.

Cohort Studies↗
PubMed1978

Translational movements of macrophages through media of different viscosities.

The extent of the migration of guinea-pig peritoneal macrophages from capillary tubes over the surfaces of plastic Petri dishes, was quantitated by planimetry. It was observed that the amount of migration decreased as the viscosity of the medium was increased by the addition of agarose. An essential component of translational movement is the formation of adhesions between cells and their substrata. It is suggested on the basis of the present migration and adhesion experiments, that the increased viscosity reduces migration by retarding the formation of adhesions between the cells and their substrata. The experiments do not support the suggestion that agarose adsorbed to the dish surface affects the adhesion-dependent arm of migration or that viscous 'drag' on whole cells (over the viscosity range of 0.71 to 3.9 x 10(-3) N s m-2) reduces their movements.

Animals↗
PubMed2000

Effect of long-term exercise training on blood viscosity during endurance exercise at an anaerobic threshold intensity.

Blood viscosity (etaB) is low in athletes, but the effect of exercise training on etaB during endurance exercise at an anaerobic threshold (AT) intensity in non-athletes is not well known, although it is known that exercise training sometimes induces the hyperviscosity syndrome. Fourteen subjects were recruited and divided into 2 groups: those who trained at an AT intensity for 30 min/day, 3 times weekly for 1 year (Group T, n=8), and sedentary subjects (Group C, n=6). The test protocol consisted of a single 30-min treadmill exercise at each individual's AT intensity, which was determined in advance. The etaB, plasma viscosity (etaP), and hematocrit were measured just before and at the end of the treadmill exercise. The subjects were not allowed to drink any water before exercise. In the Group C subjects, the hematocrit and etaP increased significantly and the etaB tended to increase. However, in the Group T subjects, the hematocrit and etaP did not increase and the etaB decreased significantly. These data indicate that long-term exercise training attenuates the increase in blood viscosity during exercise.

Adult↗
PubMed2003

Changes in blood viscosity with synthetic protease inhibitors.

We examined the effects on whole blood viscosity and coagulation time of various dosages of the synthetic low-molecular protease inhibitors gabexate mesilate and nafamostat mesilate with an oscillation-type viscometer. When either agent was added, blood viscosity decreased dose-dependently along a sigmoid-like curve. Furthermore, coagulation time was shorter with gabexate mesilate than with nafamostat mesilate owing to the differences of half-life in human blood. Thrombin generation, which results from the activation of coagulation factors, is inhibited by synthetic protease inhibitors and subsequently decreases blood viscosity dose-dependently.

Adult↗
PubMed2004

Changes in blood viscosity with mucopolysaccharide polysulfate.

We examined the dose-dependent effects of mucopolysaccharide polysulfate (MPS) on coagulation variables and whole-blood viscosity in human blood. Both 0.01% and 0.1% MPS significantly reduced levels of both fibrin monomer and thrombin-antithrombin III complex in a manner similar to that of 2.0 IU/ml heparin sodium. Furthermore, MPS dose-dependently decreased whole-blood viscosity, as measured with an oscillation viscometer. Because MPS can be applied in creams and gels, percutaneous application of MPS may effectively reduce whole-blood viscosity in local veins.

Adult↗
PubMed1995

Effect of the viscosity or deacetylation degree of chitosan on fecal fat excreted from rats fed on a high-fat diet.

Several chitosan preparations, either with a comparable degree of deacetylation but differing viscosity or with comparable viscosity but a differing degree of deacetylation, were examined for their effect on the fecal fat excreted from rats fed on a high-fat diet. As the viscosity or deacetylation degree of a chitosan preparation increased, the more its effect on the apparent fat digestibility by rats became conspicuous. A supplement of ascorbic acid to each chitosan diets resulted in a significant depression of fat digestion and absorption in the lumen. The chitosan intake caused a higher level of fat to be excreted in the feces of the corn oil-receiving rats than the lard-receiving ones, although the effect was strong with both diet groups.

Acetylation↗
PubMed2004

Modeling of complex viscosity changes in the curing of epoxy resins from near-infrared spectroscopy and multivariate regression analysis.

The present study investigates the relationship between the changes in complex viscosity and near-infrared spectra. Principal component regression analysis is applied to a near-infrared data set obtained from the in situ monitoring of the curing of diglycidyl ether of bisphenol A with the diamine 4,4'-diaminodiphenylmethane. The values of complex viscosity obtained by dynamic mechanical analysis during the cure process were used as a reference. The near-infrared spectra recorded throughout the reaction, unlike the univariate data analysis at some wavelengths of the spectra, contain a sufficient amount of information to estimate the complex viscosity. The relationship found was high and the results demonstrate the quality of the fitted model. Also, a simple user-friendly procedure for applying the model, focused on the user, is shown.

Algorithms↗
PubMed1979

A viscosity model of polyacrylamide gel electrophoresis.

In current theories of polyacrylamide gel electrophoresis, the idea prevails that molecular sieving relies on different accessibility of volume fractions and of cross-sectional area fractions (denoted "pores") to different-sized ions due to the effect of "geometric exclusion". This correlates with the assumption that all elements of a polyacrylamide network occupy fixed and unchangeable positions thus forcing colliding macro-ions to diffuse laterally in order to find an "accessible pore" and to resume motion in direction of the electrical field. However, the alternative conception would be equally well justified, i.e. the assumption that polyacrylamide chains represent smooth obstacles cleared aside under the electrokinetic pressure of a macro-ion. This explanation would even be preferable with respect to the molecular sieving effects occurring in solutions of "liquid polyacrylamide". Yet no theory exists as to describe such effects in quantitative terms. In the present article, a parameter is defined and discussed, which can be estimated by experiment, and which seems to be apt to characterize local resistivity of polymer structures against dislocation and deformation: the "fractional specific resistance". Definition of this parameter is based on the model of a "viscosity-emulsion" composed of two interpenetrating liquid compartments which are characterized by different levels of hydrodynamic friction and the spatial dimensions of which are inferred from Ogston's theory. This concept of "localized viscosity" may also serve as a link between theories of molecular sieving and of "macroscopic viscosity" of flexible polymers. The data of Morris, formerly taken as verifications of the "rigid-pore" concept, are now interpreted in terms of four factors responsible for sizediscrimination: collision frequency, duration of single contacts, size-dependent frictional force, and the extent of cooperation among fibres, due to crosslinking and to simultanous contacts of several fibres to a single macro-ion. Some functions relevant for problems of molecular weight determination by gel electrophoresis are discussed in relation to the suggested model.

Acrylamides↗
PubMed1999

A three-month repeated oral administration study of a low viscosity grade of hydroxypropyl methylcellulose in rats.

The toxicity of the lowest viscosity grade of hydroxypropyl methylcellulose (HPMC) that is currently commercially available was investigated by means of a three-month repeated oral administration study in male and female Crj:CD (SD) IGS rats at doses of 505, 1,020 and 2,100 mg/kg/day. Body weights of males and females in the 2,100 mg/kg group were lower than those of the control group on and after day 28 of administration, but the differences were not statistically significant. The degree of suppression of body weight gain in males was higher than that in females. This tendency was similar to the results in other toxicity studies of HPMC that have been reported. Males in the 2,100 mg/kg group showed a tendency (not significant) for decreased food consumption and urine volume. Examinations of general signs, hematology, blood chemistry, ophthalmology, absolute and relative organ weights, autopsy and histopathology revealed only a few, apparently coincidental, statistically significant differences from the control, and no evidence of any dose-dependent changes was found. It was concluded that the lowest viscosity grade of HPMC showed extremely low toxicity under the conditions of this study, as has been found for higher viscosity grades.

Administration, Oral↗
PubMed1978

High density, low viscosity barium for fine mucosal detail on double-contrast upper gastrointestinal examinations.

A high-density, low viscosity barium suspension was developed to maximize demonstration of very small mucosal details on double-contrast upper gastrointestinal examinations. The suspension is capable of 250% wt/vol densities without mechanical mixing, while retaining a low viscosity. In vitro tests showed the material to be superior to suspensions of greater viscosity and/or more moderate density in demonstrating fine surface detail. Clinical experience with more than 3,000 examinations with the 250% wt/vol barium suspension has shown the material to be capable of demonstrating areae gastricae or similar fine nodular patterns in approximately 70% of studies.

Absorptiometry, Photon↗