Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VISCOSITY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed1983

[Serum viscosity and chronic hepatopathies].

In 26 patients with chronic liver disease, the serum viscosity was studied. In 42% of subjects, the serum viscosity was found increased, almost always associated with clinical findings of central nervous system involvement. The remission of central nervous system symptoms occurs with fall into normal range of serum viscosity levels. Therefore, the serum hyperviscosity should be included among various causes of cirrhosis encephalopathy. When serum viscosity is increased, relates rather to immunoglobulins (IgG, IgA, IgM) increases then to increased amounts of total globulins.

Adolescent↗
PubMed1980

[Study of the effects of free radicals produced by ultraviolet rays on viscosity of human synovial fluid. Methodological details].

After having pointed out a method measurement of the synovial Fluid (S.F.) viscosity by means of a white blood cell diluting pipette, obtaining results similar to those of Ostwald's viscometer, the AA have studied the osteoarthrotic S.F. viscosity after Ultra Violet Illumination. The production of Free Radicals induced by U.V., determines a fall of osteoarthrotic S.F. viscosity towards the values found in arthritic S.F..So, the AA, indirectly, confirme the capacity of Free Radicals to induce a S.F. viscosity modification like that provoked by the phlogistic process.

Arthritis, Rheumatoid↗
PubMed1995

[An epidemiological study on blood viscosity and intraerythrocytic calcium in a group of high-school students selected according to their family histories].

An epidemiological study was performed in a group of secondary school students selected according to their family history to assess whether changes exist in blood viscosity and intraerythrocytic calcium levels in young healthy subjects with positive family histories of arterial hypertension or cerebral and cardiac ischemic vasculopathies, compared to a control group with a negative family history of these disorders. A population of 130 secondary school students without any pathologies were subdivided into 4 groups: 1) with a positive family history of ischemic cardiopathy (ICP); with a positive family history of cerebral ictus; 3) with a family history of arterial hypertension; 4) a negative family history of these diseases. Total blood viscosity, hematocrit, plasma fibrinogen and intraerythrocytic calcium was evaluated in all groups. The results show that these parameters were within the normal range, as was to be expected in healthy subjects. Blood viscosity was also normal in all groups; intraerythrocytic calcium levels were slightly higher in groups with histories of cardiovascular disease and in particular there was an increased percentage of cases with values above the threshold level. Higher fibrinogen levels were also recorded, but always within the normal range, in the group with a positive history of ICP. The epidemiological study is important to assess whether a family pattern of cardiovascular disease can also influence such independent risk parameters as blood viscosity and intraerythrocyte calcium, owing to the possible greater frequency of development of cardiovascular disease.

Adolescent↗
PubMedDate not supplied

[Urine viscosity in the evaluation of homeostasis in heart surgery patients in the early postoperative period].

A total of 100 dynamic measurements of the urinary viscosity were carried out in 38 patients subjected to open-heart surgery. Biochemical parameters and levels of electrolytes were measured in the cystic urine. The viscosity of the urine was found to be unchanged from 10 to 300 sec-1. A significant increase of its level was observed only in acute renal failure and led to the development of multiorgan abnormalities. The results indicate that urine viscosity in the early postoperative period was due to pH values (r = 0.47, p < 0.05) and free hemoglobin level (r = -0.52, p < 0.01) in coronary patients and due to concentrations of sodium (r = -0.57, p < 0.01) and chloride ions (r = 0.38, p < 0.01), osmolarity (r = -0.53, p < 0.1), and protein levels (e = -0.37, p < 0.1) in patients with acquired heart diseases. These causal relations were conditioned by the postoperative directions of regular reactions of homeostasis, because in coronary disease it is virtually the same as before surgery. Contrariwise, renal perfusion has a great impact on homeostasis stabilization in new bloodflow state in patients subjected to open-heart surgery for acquired heart diseases. As molecular and cellular disorders anticipate the clinical symptoms, we came to a conclusion that increase of urine viscosity may be an early sign predicting the development of multiorgan abnormalities.

Acute Kidney Injury↗
PubMedDate not supplied

Red blood cell aggregation and blood viscosity in an isolated heart preparation.

We studied the effects of moderate changes in red blood cell RBC aggregation on blood flow in the vasodilated vascular bed of an isolated rat heart. We compared a non-aggregating RBC suspension (in Krebs-albumin medium) with RBC suspensions in 1% and 2% Dextran 70 (MW 70000), exhibiting two different degrees of moderate aggregation. Degrees of aggregation were precisely estimated by in vitro laser aggregometry. Each heart was perfused by the non-aggregating RBC suspension and by one aggregating RBC suspensions. Blood flow was measured in a range of perfusion pressure from 40 to 80 mm Hg. For the three RBC suspensions, linear pressure/flow relationships were found. From the comparison between the pressure/flow relationships obtained with Krebs albumin medium and either 1% or 2% Dextran, it was possible to compare in vivo the contribution of RBC to the viscosity (i.e., the relative apparent viscosity) in the 2 aggregating RBC suspensions with that of the non-aggregating RBC suspension. The contribution of RBC to the viscosity was found to be 20% to 25% lower in the 1% RBC suspension than in the non-aggregating RBC suspension. With 2% Dextran which induced a higher degree of aggregation no differences were found between the relative apparent viscosities of the aggregating and the non-aggregating suspension. From the comparison between RBC in 1% Dextran and Krebs-albumin, we concluded that in vivo a moderate RBC aggregation reduces viscous resistance due to the presence of blood in a vascular network. Since no more effect of RBC aggregation per se was found when the degree of aggregation was higher (with RBC in 2% Dextran), this suggests that, in this case, aggregation induces opposite effects along the myocardial vascular network which cancel each other out, thus inducing a nil net balance.

Animals↗
PubMed1995

Effects of acute psychological stress on serum lipid levels, hemoconcentration, and blood viscosity.

BACKGROUND: While there is substantial evidence that psychological stress enhances risk for coronary artery disease, the mechanisms underlying such an influence remain unclear. We examined the effects of short-term psychological stress on serum lipid levels, hemoconcentration, fibrinogen level, and plasma viscosity. METHODS: Forty-four healthy young adults were randomly assigned to perform a distinctly frustrating cognitive task for 20 minutes (stress condition) or to rest quietly for the same period (control condition). RESULTS: Relative to controls, stressed subjects showed significant increases in blood pressure and heart rate; total, low-density, and high-density lipoprotein cholesterol levels; hematocrit; hemoglobin level; and total protein concentration. Stressed subjects also showed significant reductions in plasma volume and increased plasma viscosity and estimated whole-blood viscosity compared with controls. A similar trend in fibrinogen level was not statistically significant. Individual differences in blood pressure and heart rate response to stress correlated highly with changes in total cholesterol levels and hematocrit. CONCLUSIONS: Our investigation provides further evidence that exposure to short-term mental stress elicits hemoconcentration with associated increases in serum lipid concentrations, hemostatic factors, and blood viscosity.

Acute Disease↗
PubMed1993

[Blood viscosity and related factors in patients with primary open-angle glaucoma].

The blood viscosity and related factors were determined in 31 patients with primary open-angle glaucoma (POAG) and 30 normal subjects. It was found that (1) the blood viscosity was significantly higher in the POAG group than in the normal controls, as were also the plasma viscosity, the hematocrit, the fibrinogen content, the index of erythrocyte aggregation and the blood yielding stress, and (2) there was no difference in the value of TK which was a measure of erythrocyte deformability between the two groups. The study showed that patients with glaucoma had blood hyperviscosity which could be caused by the elevated hematocrit and plasma viscosity. The possible relevance of blood hyperviscosity to glaucomatous optic atrophy was discussed.

Adult↗
PubMed1978

No change of whole blood of plasma viscosity in cardiac patients after subcutaneous calcium heparin.

Whole blood viscosity, plasma viscosity and haematocrit were studied in a group of cardiac patients before and during subcutaneous heparin treatment. No significant change was noted in any of the parameters investigated. Relative viscosity (whole blood viscosity/plasma viscosity ratio) was also unaffected. These data indicate that heparin has no effect on the rheology of blood in vitro.

Adult↗
PubMed1993

[Prognostic significance of baseline state of platelet aggregation and blood viscosity during gravitational plasmapheresis in patients with angina pectoris].

The study was undertaken to examine 56 patients (mean age 54.9 +/- 1.1 years) who had functional class III (n = 12), IV (n = 32), and unstable (n = 12) angina pectoris. Due to inefficacy of conservative therapy, all the patients underwent gravitation plasmapheresis (GPA). The parameters of induced platelet aggregation were examined by the Born-O'Brien method and blood viscosity on a rotor viscometer before, immediately and on days 1 and 3 after GPA. It was found that the baseline blood viscosity and platelet aggregation should be known to predict the natural history of angina in the following 1-3 days after GPA. There was a pronounced positive clinical effect in higher blood viscosity and platelet aggregation. An improvement in the clinical course of the disease and its stabilization were not observed in the baseline lower blood viscosity and platelet in patients with progressive angina.

Adult↗
PubMed1993

[The ankle-arm index and whole blood viscosity in patients with type II diabetes mellitus with ischemia of the lower extremities].

The relationship was studied between the ankle-arm index (K/R) and whole blood and plasma viscosity in patients suffering from diabetes mellitus type II with ischemia of lower extremities. The measurements were carried out in 96 patients (80 males and 16 females), of whom 72 were in stage II of Fontaine progression. Immediately after determination of the K/R index blood was taken from vena mediana cubiti adding Na2EDTA for rheological test. Whole blood viscosity was measured with a Low-Shear 100 Contraves viscometer immediately after sampling, and plasma viscosity was measured with a capillary viscometer of Ubbvelohd within 2 hours after sampling. By the method of regression analysis and linear correlation it was found that increased whole blood and plasma viscosity significantly correlated with reduced K/R value in the patients. The obtained results are analysed in biophysical and clinical aspects.

Aged↗
PubMedDate not supplied

Plasma viscosity and the diagnosis of giant cell arteritis.

The level of plasma viscosity associated with the diagnosis of giant cell arteritis, and its use as a replacement for the erythrocyte sedimentation rate (ESR) is examined, by reviewing the records of 59 patients undergoing temporal artery biopsy. All patients with positive temporal artery biopsy had plasma viscosity above the upper limit of normal (1.72 mPa.s), range 1.88 to 2.28. There was a large group of patients with a possible diagnosis, supported by a raised plasma viscosity, who in the absence of a positive biopsy were not felt to have clinical disease requiring steroid treatment. The role of plasma viscosity appears to be similar to that of the ESR in the diagnosis of giant cell arteritis.

Aged↗
PubMed1993

Diltiazem reduces whole blood viscosity following trauma-hemorrhagic shock and resuscitation.

Although diltiazem improves function in several organs following trauma-hemorrhagic shock, the mechanism remains unknown. It is hypothesized that diltiazem maintains red blood cell calcium-to-magnesium ratio, resulting in better deformability of red blood cells. This should reduce blood viscosity, allowing red blood cells to traverse the microcirculation more efficiently and improve tissue oxygenation. To study this, rats (n = 23) underwent cannulation of various blood vessels and were divided into five groups: Group 1, control rats which had surgery only; Group 2, sham-operated rats which were not hemorrhaged but were infused with a volume of lactated Ringer's solution (LRS) equivalent to that given to the hemorrhaged animals (Groups 4 and 5); Group 3, hemodilution animals which were maintained at normal blood pressure but with the hematocrit lowered to values equivalent to hemorrhaged rats (Groups 4 and 5); Groups 4 and 5, animals which underwent fixed pressure (40 mm Hg) hemorrhage, followed by resuscitation with LRS, 5x the shed blood volume, and were given IV saline (Group 4) or 400 micrograms diltiazem/kg (Group 5) with the resuscitation. Blood viscosity was measured at the end of resuscitation with a Brookfield DV-III viscometer. Results showed that blood viscosity was markedly reduced in the diltiazem treatment group, but was unchanged in any of the other groups versus the control. Thus, the beneficial effects of diltiazem after trauma-hemorrhage and resuscitation may be due in part to the marked decrease in blood viscosity allowing for improved oxygen delivery and removal of metabolites.

Animals↗
PubMed1996

[Dynamic viscosity and corneal endothelial protection with Healonid, Healon GV, Provisc and Viscoat during phacoemulsification].

PURPOSE: To demonstrate the utility of a viscoelastic substance which maintains high viscosity during phacoemulsification, we conducted a double study. METHODS: We compared in vitro the corneal endothelial protection offered by Healon, Healon GV, Provisc and Viscoat after < > phacoemulsification. Eight samples of ten to fifteen freshly enucleated pig eyes were operated; the first four groups were the controls, whereas the other four tested the different viscous solutions. In parallel, we determined the rheologic properties of the four viscoelastic substances in a physicS laboratory. To measure the percentage of corneal endothelial cell damage, we used the Janus Green spectrometric technique. RESULTS: Corneal endothelial cell damage averaged 31.67% in eyes in which no viscoelastic substance was used. Damage was 14.29% in specimens that received Healon, 12.85% with Healon GV, 2.48% in the Viscoat group and 15.43 in those that received Provisc. There is a significant difference (p <0.001) between the Viscoat group and all other samples. The values of the viscosity at different shear rates and the graph of viscosities as a function of shear rate of the four viscous solutions are given. CONCLUSION: Viscoat has a very high dynamic viscosity at high shear rate. This property and a poor cohesion provide a better corneal endothelial protection during in vitro phacoemulsification.

Animals↗
PubMed1977

[Blood viscosity measurements in coronary infarct patients].

In 63 patients with myocardial infarctions happening longer ago as well as in 17 patients with acute myocardial infarction the viscosity of blood was measured and compared with the values of a control group of 34 healthy persons which was compiled after exclusion of known factors effecting on viscosity, such as hyperfibrinogenaemia or increase of hematocrit. The viscosities of the patients with infarction were significantly higher in all degrees of severity than those of the healthy persons. The hematocrit value, the fibrinogen and cholesterol level which were significantly higher in patients with infarction than in healthy persons were regarded as an explanation for this. Apart from this there existed an increase of the factors of risk total lipids, triglycerides and uric acid in the serum in cases with infarction. The increased blood viscosity may be regarded as a factor of risk for the myocardial infarction, according to our investigations.

Blood Viscosity↗
PubMed1997

[Clinical implications of high blood viscosity and its reduction bu photo-hemotherapy].

The paper is concerned with an essential blood characteristic--viscosity which is considered in relation of mechanisms responsible for its normal and abnormal characteristics, its role in the onset of circulatory disorders. High blood viscosity may contribute to development of vascular disturbances. Efficient methods of normalizing high blood viscosity are analyzed with special emphasis on photochemotherapy. Effects of ultraviolet, blue and red laser radiation on blood viscosity are outlined.

Blood Transfusion, Autologous↗
PubMed1976

Blood viscosity in man following decompression: correlations wiht hematocrit and venous gas emboli.

Whole blood viscosities were measured in U.S. Navy personnel before and after chamber compressions to 5 ATA (132FSW) and 7.4 ATA (210 FSW) by a new method described here. Bubble scores as a quantitative measure of venous gas emboli were determined during decompression and for 30 min thereafter. Hematocrit was measured both before and after each dive. There were five cases of decompression sickness in the two groups. No significant changes in whole blood viscosity, or hematocrit, were noted either in the group that was affected by decompression sickness or in all of the subjects taken as a group. No correlations between total bubble score and changes in viscosity or hematocrit could be made. These results imply that no major changes in viscosity occur in the usual forms of decompression sickness encountered in human beings.

Blood Viscosity↗
PubMed1996

Effects of viscosity and surface moisture on bond strengths of resin-modified glass ionomers.

PURPOSE: To evaluate the effects of surface moisture and material viscosity on the shear bond strength of resin-modified glass ionomers to dentin. MATERIALS AND METHODS: Sixty human teeth were mounted in phenolic rings and ground to obtain flat facial and lingual dentin surfaces. The specimens were assigned to six treatment groups. Three groups were first conditioned with 10% polyacrylic acid. On one surface of each specimen, dentin was left visibly moist prior to application of the restorative material. On the opposite surface the dentin was dried, but not desiccated, after conditioning. For these three groups, Fuji II LC resin-modified glass ionomer was mixed at powder/liquid (P/L) ratios of 1.4, 3.0 and 3.6 and applied to the conditioned dentin in 2.5 mm diameter molds. The other three groups were treated with Vitremer primer. One surface of each specimen was "dry" and one surface was "moist" before primer application. Vitremer restorative material was mixed at P/L ratios of 2.2, 2.5 and 2.8 and applied to the primed surfaces. Shear bond strengths were measured using a universal testing machine. Data were subjected to three-way ANOVA and Tukey's multiple comparisons test. RESULTS: Mean shear bond strengths of the two materials ranged from 6.9 to 10.4 MPa and varied little regardless of the viscosity of the materials or the degree of surface moistness. The differences among viscosities and surface moistness were not statistically significant. IN this in vitro study, the shear bond strengths of two resin-modified glass ionomers were unaffected by the viscosity of the materials and the surface moisture of the dentin substrate.

Analysis of Variance↗
PubMed1998

The non-ionic surfactant Poloxamer 188 (RheothRx) increases plasma and whole blood viscosity.

RheothRx injection is an intravenous formulation of Poloxamer 188, a non-ionic block copolymer surfactant which is actually used in clinical studies, e.g., during thrombolysis in acute myocardial infarction. We have analysed the influence of RheothRx on plasma and whole blood viscosity of healthy individuals in vitro. For that purpose plasma was incubated with 0, 0.75, 3.75 and 18.75 mg/ml RheothRx and whole blood with a constant hematocrit of 41.4% with 0, 0.4, 2 and 10 mg/ml RheothRx at 37 degrees C. Viscosity was measured with a Couette viscometer at shear rates of 94, 11, 0.9 and 0.1 s-1 as well as with a newly developed oscillating viscometer. In contrast to other studies, we found no favourable effect of RheothRx on plasma and whole blood viscosity. At the highest RheothRx concentration an increase in high and low shear viscosity was observed. Erythrocyte morphology remained unchanged. These data, although on normal blood in vitro, suggest that the positive effects of RheothRx in vivo may not be caused by improved flow properties of blood, but could rely on other mechanisms.

Adult↗