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PubMed1990

Blood viscosity and platelet function in thrombolytic therapy of acute myocardial infarction.

The mechanisms by which thrombolytic drugs accomplish their impressive clinical effects in the treatment of acute myocardial infarction are as yet incompletely appreciated. Factors other than lysis of thrombi and restoration of blood flow most likely play a role, and blood viscosity and platelet function probably are important factors. Blood viscosity is inversely related to oxygen supply to myocardial tissue and therefore a decrease in viscosity might contribute to preservation of myocardial function. Since fibrinogen is a major determinant of blood viscosity and this protein is largely degraded by some thrombolytic drugs, it is conceivable that a systemic fibrinogenolytic state is of additional benefit for the patient. Fibrinogen and other plasma proteins which change during thrombolytic therapy are also essential for adequate platelet function. Besides, thrombolytic drugs can directly affect platelet activity. Although the exact effects are still unknown, it is certain that changes in platelet function induced by thrombolytic drugs are important for the clinical efficacy and probably for the side-effects of thrombolytic therapy.

Anistreplase↗
PubMed1994

Dietary fiber viscosity and amino acid digestibility, proteolytic digestive enzyme activity and digestive organ weights in growing rats.

The effect of dietary fiber viscosity on apparent ileal nitrogen and amino acid digestibility, proteolytic enzyme activity and digestive organ weights was investigated. Eighteen growing rats were fed for 21 d purified casein-based diets containing carboxymethylcellulose (50 g/kg) of low (20 cP), medium (800 cP) and high (2000 cP) viscosity (LV, MV and HV treatment groups, respectively). Dietary fiber viscosity did not significantly affect apparent ileal (terminal 15 cm of the ileum) nitrogen or amino acid digestibility, trypsin or chymotrypsin activity in the small intestinal contents and pancreatic tissue, aminopeptidase-N activity in the small intestinal contents and tissue, or the weights of the stomach, pancreas, small or large intestines. Intragastric pepsin activity in LV rats was significantly higher than in MV or HV rats (P < 0.01), but fiber viscosity did not affect pepsin activity in the stomach tissue. The intragastric pH of the HV and MV rats was significantly higher than that for the LV rats (P < 0.01). The stomach contents (dry matter) of MV and HV rats were greater than in LV rats (P < 0.05). Delayed passage rate of the more viscous digesta may have resulted in greater absorption of amino acids, because the HV rats had a higher estimated true ileal digestibility than the LV animals for threonine, serine, aspartic acid, glutamic acid, histidine, tyrosine and phenylalanine.

Amino Acids↗
PubMed2005

Increasing digesta viscosity using carboxymethylcellulose in weaned piglets stimulates ileal goblet cell numbers and maturation.

Intestinal mucin, a family of glycoproteins secreted by goblet cells, is the main constituent of the mucus protecting the gastrointestinal tract. For optimal mucosal protection, both the quantitative and qualitative characteristics of mucin are essential. To evaluate how viscosity influences ileal apparent digestibility and mucin biology, a highly viscous nonfermentable soluble polysaccharide, carboxymethylcellulose (CMC), was fed to weaned piglets for 15 d. The ileal crude mucin concentration was determined by ethanol precipitation, and changes in goblet cell subtypes were analyzed by the histochemistry of ileal and colonic tissues. As expected, CMC increased the viscosity of ileal digesta and the moisture of feces (P < 0.001). The crude mucin concentration and output at the ileum were higher (P < 0.05) in pigs fed CMC than those fed the control diet. Increasing intestinal content viscosity in pigs fed CMC had no significant effects on the ileal apparent digestibility of dry matter, organic matter, nitrogen, and minerals. The number of total ileal goblet cells per villus also was higher (+30%, P < 0.05) in pigs fed the CMC diet compared with controls. This increase was essentially accounted for by increased numbers of acidic and acidic sulfated mucin-containing cells (+30%, P < 0.05). Trends (P = 0.06) toward decreased numbers of neutral and acidic mucin-containing cells in ileal crypts were also noted. In conclusion, increasing intestinal content viscosity in weaned piglets fed CMC increased the ileal mucin output and numbers and maturation of goblet cells in ileal villi without effects on the apparent digestibility of the diet.

Aging↗
PubMed1984

The relationship of plasma and serum viscosity to disease activity and smoking habit in rheumatoid arthritis.

Viscosity measurements of serum and plasma have been suggested as improvements on other indicators of activity in the rheumatic diseases. We compared the clinical assessment of disease activity in 71 patients with rheumatoid arthritis against various laboratory tests including viscosity measurements. The effects of smoking were also studied. While many of the tests showed correlations with each other, none was found to correlate with any of the clinical parameters. Smoking lowered the ESR, but did not affect the plasma viscosity in these patients. Thus viscosity measurements were no improvement in assessing activity in a cross section of patients, though its lack of dependence on smoking habit may be an advantage in sequential studies.

Arthritis, Rheumatoid↗
PubMed1988

Reserpine treatment increases viscosity of fluid in the epididymis of rats.

Reserpine treatment in rats induces morphological and functional disturbances in exocrine glands which resemble those produced by cystic fibrosis. The general feature is a decrease in fluid secretion with a rise in mucous concentration and altered electrolyte composition. Chronically reserpinized rats have therefore been used as an animal model for the disease. It is known that cystic fibrosis men are infertile due to obstruction of the epididymal duct with inspissated material, a phenomenon that may be secondary to abnormal electrolyte and water transport in the epididymis. Male rats were treated with reserpine (0.5 mg/kg/day) for 12 to 14 days. At the end of the treatment, epididymal fluids were flushed out from the cauda epididymidis for measurement of spermatocrit, viscosity, total protein concentration, sperm concentration and motility. It was found that reserpine treatment caused a rise in viscosity (by 40%), spermatocrit, sperm concentration, and protein concentration. These changes were observed in the epididymis of rats that had been efferent duct-ligated before reserpine treatment. Despite a rise in viscosity of the fluid bathing the spermatozoa, the viability of the stored spermatozoa was apparently normal. Spermatozoa were able to initiate forward motility when suspended in a sodium-containing medium. Testis fluid secretion measured by weight gain after efferent duct ligation for 16 h was not affected by reserpine treatment. The change in viscosity probably was due to a decrease in fluidity in the epididymis. It is concluded that reserpine treatment in rats produced changes in the exocrine functions of the epididymis similar to those seen in other exocrine glands.

Animals↗
PubMed2003

Measurement of plasma viscosity in stored frozen samples: a general population study.

To establish whether plasma viscosity could be accurately measured from frozen-stored (instead of fresh) plasma samples in epidemiological studies, we prospectively compared fresh and frozen-stored samples from 1361 men and women aged 25-74 years participating in the Glasgow MONICA survey. Mean plasma viscosity (37 degrees C) was significantly higher (P < 0.0001) in fresh samples (mean = 1.310 mPa/s, standard deviation = 0.079 mPa/s) compared with frozen samples (mean = 1.278 mPa/s, standard deviation = 0.075 mPa/s). However, this difference (mean = 0.030 mPa/s, 95% confidence interval = 0.029-0.031) did not vary significantly with increasing viscosity (kappa statistic for consistency of categorization by thirds = 0.824, standard error = 0.021). We conclude that frozen samples are acceptable for epidemiological studies of plasma viscosity, which should increase their utilization.

Adult↗
PubMed1993

Blood viscosity and peripheral vascular resistance in patients with untreated essential hypertension.

OBJECTIVES: The viscosity of blood is increased in patients with essential hypertension. The aim of the present study was to investigate the importance of the different variables of blood rheology to total peripheral resistance, and to elucidate whether inappropriate regulation of the formation of erythropoietin could be important. DESIGN: Nineteen consecutive patients with untreated essential hypertension were examined and compared with a group of matched healthy volunteers. METHODS: The haemorheologic variables were assessed by rotational viscometry and the haemodynamic variables by bioimpedance cardiography. The serum concentrations of erythropoietin were determined by radioimmunoassay. RESULTS: The whole blood viscosity and peripheral resistance index were elevated in the hypertensive group. The two variables were positively correlated with each other (r = 0.68, P = 0.0015). The plasma viscosity and erythrocyte aggregation tendency were increased and the erythrocyte deformability, measured as fluidity, was decreased in the hypertensive patients. In the male subpopulation (n = 12) the aggregation tendency was positively, and the deformability negatively, correlated with body mass index. The serum concentrations of erythropoietin were equal in the two groups. CONCLUSIONS: The increased total peripheral resistance in patients with essential hypertension may in part be explained by an increased blood viscosity, but the possibility of an opposite cause-effect relationship must also be taken into consideration. The haemorheological abnormalities observed in the present patients cannot be explained by high serum levels of erythropoietin.

Adult↗
PubMed2004

Ursodeoxycholic acid decreases viscosity and sedimentable fractions of gallbladder bile in patients with cholesterol gallstones.

OBJECTIVES: Ursodeoxycholic acid (UDCA) therapy is associated with reduced risk of biliary pain and acute cholecystitis or pancreatitis in patients with cholesterol gallstones. The underlying mechanisms are understood incompletely, which prompted us to study the influence of UDCA treatment on composition, viscosity and sedimentable fractions of gallbladder bile in 25 patients with symptomatic cholesterol gallstones. METHODS: In two randomised groups, either UDCA (750 mg daily) or placebo was given to each patient 10-12 days before cholecystectomy. Gallbladder bile was collected intraoperatively and analysed for protein, mucin, lipid composition, cholesterol crystal observation time, amount of cholesterol in vesicles, viscosity and sedimentable fractions (cholesterol, protein, mucin, bilirubin). RESULTS: UDCA-treated patients showed longer cholesterol crystal observation times and lower concentrations of total cholesterol and percentages of vesicular cholesterol in gallbladder bile. The concentrations of protein and mucin in gallbladder bile tended to be lower in the UDCA-treated group, but phospholipids, bile acids and bilirubin did not differ between the groups. Viscosity and the total sedimentable fractions of gallbladder bile decreased in the UDCA-treated patients. CONCLUSIONS: UDCA treatment reduces total and vesicular cholesterol, the formation of cholesterol crystals, viscosity, and the total amount of sedimentable fractions in gallbladder bile. These observations might explain, at least partially, why UDCA treatment attenuates the occurrence of biliary pain and complications in gallstone patients.

Adult↗
PubMed2005

Dynamics of fluid vesicles in shear flow: effect of membrane viscosity and thermal fluctuations.

The dynamical behavior of vesicles is investigated in simple shear flow. A simulation technique is presented that combines a three-dimensional particle-based mesoscopic model (multiparticle collision dynamics) for the solvent with a dynamically triangulated surface model for the membrane. In this model, thermal fluctuations of the solvent and of the membrane are consistently taken into account. The membrane viscosity can be varied by changing the bond-flip rate of the dynamically triangulated surface. Vesicles are found to transit from steady tank-treading to unsteady tumbling motion with increasing membrane viscosity. At small reduced volumes, the shear induces a transformation from a discocyte to a prolate shape at low membrane viscosity. On the other hand, at high membrane viscosity, the shear induces a transformation from prolate to discocyte, or tumbling motion accompanied by shape oscillations between these two states. Thermal fluctuations induce intermittent tumbling and smooth out the transitions. This effect can be understood from a simplified stochastic model.

Biophysics↗
PubMed2003

A novel small heat shock protein gene, vis1, contributes to pectin depolymerization and juice viscosity in tomato fruit.

We have characterized a novel small heat shock protein gene, viscosity 1 (vis1) from tomato (Lycopersicon esculentum) and provide evidence that it plays a role in pectin depolymerization and juice viscosity in ripening fruits. Expression of vis1 is negatively associated with juice viscosity in diverse tomato genotypes. vis1 exhibits DNA polymorphism among tomato genotypes, and the alleles vis1-hta (high-transcript accumulator; accession no. AY128101) and vis1-lta (low transcript accumulator; accession no. AY128102) are associated with thinner and thicker juice, respectively. Segregation of tomato lines heterogeneous for vis1 alleles indicates that vis1 influences pectin depolymerization and juice viscosity in ripening fruits. vis1 is regulated by fruit ripening and high temperature and exhibits a typical heat shock protein chaperone function when expressed in bacterial cells. We propose that VIS1 contributes to physiochemical properties of juice, including pectin depolymerization, by reducing thermal denaturation of depolymerizing enzymes during daytime elevated temperatures.

Acclimatization↗
PubMed1996

Oleic acid and linoleic acid are the major determinants of changes in keratinocyte plasma membrane viscosity.

Keratinocytes were grown in medium with no essential fatty acids as well as in media with specially selected fatty acid augmentations. Gas chromatographic determinations of 21 fatty acids in the phospholipids were correlated with plasma membrane viscosity obtained by electron paramagnetic resonance studies (n = 24). Using standard procedures from multivariate analysis, we derived an expression that modeled the viscosity data as a function of four key fatty acid levels: [formula see text] where the fatty acids are given in mole percent of total lipids and are identified as two number sequences: number of carbons followed by number of double bonds. No other fatty acid made a significant contribution to the regression equation. The range of viscosity was very large, varying from 60 to 120 cP over the sample population. The results are interpreted to indicate that polyunsaturated fatty acids are replaced with monounsaturated fatty acids by the keratinocytes and that dihomogamma-linolenic acid (20:3, n-6) plays an important role in membrane viscosity when essential fatty acids are available in the growth medium of these adult human cultured keratinocytes.

Cell Division↗
PubMed2006

The effect of bolus viscosity on swallowing function in neurogenic dysphagia.

AIM: To assess the pathophysiology and treatment of neurogenic dysphagia. METHODS: 46 patients with brain damage, 46 with neurodegenerative diseases and eight healthy volunteers were studied by videofluoroscopy while swallowing 3-20 mL liquid (20.4 mPa s), nectar (274.4 mPa s) and pudding (3931.2 mPa s) boluses. RESULTS: Volunteers presented a safe and efficacious swallow, short swallow response (< or =740 ms), fast laryngeal closure (< or =160 ms) and strong bolus propulsion (> or =0.33 mJ). Brain damage patients presented: (i) 21.6% aspiration of liquids, reduced by nectar (10.5%) and pudding (5.3%) viscosity (P < 0.05) and (ii) 39.5% oropharyngeal residue. Neurodegenerative patients presented: (i) 16.2% aspiration of liquids, reduced by nectar (8.3%) and pudding (2.9%) viscosity (P < 0.05) and (ii) 44.4% oropharyngeal residue. Both group of patients presented prolonged swallow response (> or =806 ms) with a delay in laryngeal closure (> or =245 ms), and weak bolus propulsion forces (< or =0.20 mJ). Increasing viscosity did not affect timing of swallow response or bolus kinetic energy. CONCLUSIONS: Patients with neurogenic dysphagia presented high prevalence of videofluoroscopic signs of impaired safety and efficacy of swallow, and were at high risk of respiratory and nutritional complications. Impaired safety is associated with slow oropharyngeal reconfiguration and impaired efficacy with low bolus propulsion. Increasing bolus viscosity greatly improves swallowing function in neurological patients.

Adult↗
PubMed1978

The effects of intravenous isoxsuprine on blood viscosity in patients with occlusive peripheral arterial disease.

1 Blood viscosity is thought to be a major factor in disorders of the peripheral circulation. 2 Ten patients with obliterative arterial disease received an infusion of isoxsuprine of 20 micrograms kg-1 for 30 min. The infusion was followed by a highly significant and prolonged fall in blood, plasma and serum viscosity, in haematocrit and in plasma fibrinogen concentration. Blood lipid levels were also studied: total lipids and total cholesterol did not alter; triglyceride level was significantly lowered at the end of, and after, drug infusion. 3 There was no change in blood, plasma or serum viscosity in the four patients receiving a control infusion 2 days before the infusion of isoxsuprine. 4 The relationships between lowered viscosity and increasing peripheral tissue perfusion are discussed.

Aged↗
PubMed1978

The relationship between serum viscosity, hypervolaemia and clinical manifestations associated with circulating paraprotein.

In 44 of 56 patients with malignant paraproteinaemia the relationship of serum viscosity, plasma volume (PV), estimated blood volume (BV) and clinical findings was investigated and in the remaining 12 patients one or more of these parameters was studied. There was a correlation between increased PV and serum viscosity (r = 0.66, P less than 0.001). The retinopathy characteristic of the hyperviscosity syndrome (HVS) was always associated with serum viscosity greater than or equal to 3.8 and with hypervolaemia. The evidence that the retinal changes were related more closely to serum hyperviscosity than to hypervolaemia is twofold. First, there was a considerable overlap in the degree of BV expansion, but not serum hyperviscosity, in patients with and without retinopathy. Second, the retinopathy in a patient with Waldenström's macroglobulinaemia (WM) improved after plasma exchange with little change in BV. While bleeding was often associated with retinopathy seven patients with multiple myeloma (MM) had no retinopathy, viscosities greater than or equal to 4.3 and BV in the same range as patients with no clinical signs. Haemorrhage in such patients may thus be unrelated to the property of the paraprotein responsible for hyperviscosity. Measurements of PV in a patient with WM having repeated plasma exchanges for bleeding suggested that hypervolaemia may contribute to haemorrhage in some patients. It is suggested that the term 'HVS' should be restricted to patients with retinopathy and that hypervolaemia should be considered a characteristic feature of this syndrome.

Blood Viscosity↗
PubMed1981

Viscosity and iron deficiency in treated polycythaemia.

An in vitro study of the effect of red-cell changes due to iron deficiency on whole-blood viscosity has been made on samples from patients with polycythaemia treated by venesection. When the PCV of the samples was adjusted to a standard value of 0.45, whole-blood viscosity was unrelated to decreasing MCH. In contrast, when samples were adjusted to a standard Hb concentration of 14 g/dl, whole-blood viscosity rose exponentially with decreasing MCH. This increase in whole-blood viscosity was shown to be a function of the increasing PCV that accompanies the falling MCH at this standard Hb value. It is suggested that in polycythaemia not due to hypoxia, hyperviscosity can be satisfactorily corrected by venesection controlled by monitoring the PCV alone. Other consideration may apply in hypoxic polycythaemia and these are discussed.

Blood Viscosity↗
PubMed1982

The influence of iron-deficient indices on whole blood viscosity in polycythaemia.

The relationship of the red-cell indices, packed-cell volume (PCV) and plasma viscosity to whole-blood viscosity was examined in 18 patients with polycythaemia. Sixteen were examined again following a course of venesection. The results were analysed by multiple regression analysis which allowed the effects of individual variables to be independently assessed. A reduction of the MCH or MCV was associated with increased whole-blood viscosity especially at low-shear rates. It is concluded that the reduced size of iron-deficient cells results in increased cell-cell interaction causing an increase in whole-blood viscosity.

Adult↗
PubMed1991

Leucocyte numbers and quality: their effect on viscosity.

Leucocyte suspension viscosity was measured using cells from a number of leukaemias. Samples from individuals with acute myelomonocytic and myeloid leukaemias, and chronic myelogenous and chronic lymphatic leukaemias were examined for their viscosity and flow properties. Leucocytes were suspended in native plasma and the effect of variable leucocyte numbers in the ranges seen in some leukaemias (100-600 x 10(9)/l) examined at different shear stresses. The effect of MCV was also determined in relation to viscosity. The results showed an increasing order of viscosity from the leucocytes of chronic lymphatic leukaemia through chronic myelogenous and acute myeloid leukaemia to the acute myelomonocytic variety. This bears some relation to the mean corpuscular volume, but confirms the fact that at high numbers of cells, patients with acute myelomonocytic, and to a lesser extent the myeloid leukaemias, are at considerable risk of blood hyperviscosity.

Blood Viscosity↗
PubMed1989

Effect of a soluble bacterial carbohydrate fraction on the viscosity of intestinal contents in healthy subjects and patients with Crohn's disease.

Supernatants of faecal suspensions from patients with Crohn's disease (CD) showed much lower viscosity than those from healthy subjects. Material responsible for the viscosity could be precipitated with ethanol. Gel filtration indicated that the viscosity was not due to the glycoprotein fraction but to a fraction with higher molecular weight and relatively high contents of muramic acid suggesting a bacterial origin. The concentration and viscosity of this fraction are less in faeces from patients with CD than in that of healthy subjects.

Adult↗