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 577 records · Page 32Linked to original sources
PubMed2000

Association between plasma viscosity and all-cause mortality: results from the MONICA-Augsburg Cohort Study 1984-92.

Several studies have reported a strong association between various markers of the acute-phase response and death from cardiovascular diseases and all-cause mortality. Inflammation at a low level of intensity may be a common phenomenon associated with the majority of causes of death owing to chronic diseases. We sought to investigate the association of plasma viscosity with all-cause mortality in a cohort of apparently healthy men. The study population consisted of 964 men aged 45-64 years at entry, randomly selected from the general population and taking part in the first MONICA-Augsburg survey 1984-85. The main outcome measure was all-cause mortality. During 8 years of follow-up, there were 81 deaths (37 cardiovascular deaths, 23 deaths from cancer and 21 deaths from other causes). There was a strong positive and statistically significant age-adjusted relationship between plasma viscosity and all-cause mortality. The relative risk of death for a one standard deviation increase in plasma viscosity (0.070 mPa/s) was 1.45 [95% confidence interval (CI) 1.19-1.76]. After further adjusting for smoking, total cholesterol, body mass index, blood pressure and education, a relative risk of 1.41 (95% CI 1.14-1.74) resulted. Other risk variables had only negligible confounding effects. The relative risk of the median of the top quintile of the plasma viscosity distribution compared with the median of the bottom quintile, computed from the adjusted model, was 2.68 (95% CI 1.63-4.42). These findings suggest that plasma viscosity may have considerable potential to predict death from all causes in middle-aged men.

Acute-Phase Reaction↗
PubMed2003

Does sticky blood predict a sticky end? Associations of blood viscosity, haematocrit and fibrinogen with mortality in the West of Scotland.

There is increasing evidence that blood viscosity and its major determinants (haematocrit, plasma viscosity and fibrinogen) are associated with an increased risk of incident cardiovascular events; however, their associations with mortality are not established. We therefore studied the associations of these variables with cardiovascular events and total mortality in 1238 men and women aged 25-64 years, followed for 13 years in the first North Glasgow MONICA (MONItoring CArdiovascular disease) survey and West of Scotland centres in the Scottish Heart Health Study. After adjustment for age and sex, increasing whole blood viscosity, plasma viscosity, haematocrit and fibrinogen (analysed by both von Clauss and heat precipitation assays) were significantly associated with mortality. Only the association for fibrinogen (von Clauss assay) remained significant after adjustment for major cardiovascular risk factors. We conclude that clottable fibrinogen may be independently associated with mortality. However, the significance of this association, and the extent to which viscosity is associated with mortality, remain to be established in larger studies and meta-analyses.

Adult↗
PubMed1978

[Blood viscosity during long-term intravenous infusion of low-molecular dextran (author's transl)].

The effect on whole-blood viscosity and haematocrit was investigated in 54 persons during intravenous infusion of 500 ml Rheomacrodex 10% or 500 ml 0.9% sodium chloride solution for two, four and six hours. Rheomacrodex 10% led to a significant decrease in whole-blood viscosity after all infusion periods and up to two hours afterwards. The decrease in viscosity was definitely more marked at lower degrees of shear than at higher ones and with long-term infusion (four and six hours) than short-term infusion (two hours). Physiological saline caused significant decrease in viscosity compared with initial values at the end of four and six-hour infusions and only at shear of 230 s-1. During all infusion periods and for all degrees of shear the decrease in viscosity was significantly greater with Rheomacrodex 10% than physiological saline.

Blood Viscosity↗
PubMed2001

Changes in intragastric meal distribution are better predictors of gastric emptying rate in conscious pigs than are meal viscosity or dietary fibre concentration.

The effect of dietary fibre on the gastric emptying rate of solids is controversial. Similarly, the mechanisms by which it modulates food intake are partially unknown. Gastric emptying and proximal v. distal stomach filling were evaluated in triplicate on four conscious pigs using scintigraphic imaging. Each animal received in an isoenergetic manner a concentrate low-fibre diet enriched in starch (S) and two high-fibre diets based on sugar beet pulp (BP) or wheat bran (WB). All meals had the same viscosity before ingestion (100.0-100.5 Pa.s). Viscosity of the gastric contents was measured in four additional animals fitted with a gastric cannula. The gastric emptying rate of BP diet was significantly slower than S and WB diets (t1/2 78.4 (sem 5.68), 62.8 (sem 10.01) and 111.6 (sem 10.82) min for S, WB and BP diets respectively, P<0.05). For BP diet only, rate of distal stomach filling was steady during the first 120 min after the meal whereas that of S and WB diets decreased in an exponential manner. Numerous backflow episodes from the distal into the proximal stomach were observed for BP diet that generated the larger intragastric viscosity (0.26 (sem 0.03), 0.3 (sem 0.02) and 0.52 (sem 0.002) Pa.s for S, WB and BP respectively). In conclusion, viscosity of the meal or the percentage total fibre, unlike viscosity of the gastric contents, are poor predictors for emptying. The reduced emptying rate observed with BP is associated with major changes in intragastric distribution of the meal absent with WB and S diets.

Animal Feed↗
PubMed1998

Viscosity of whole saliva.

This study investigates within-subject variations and associations of salivary viscosities and flow rates in a test panel of healthy adults. After several practice sessions, unstimulated and stimulated whole saliva samples were collected 5 times daily (at 0800, 1100, 1400, 1700, and 2000 h) from 30 university students. There was a significant within-subject variation in viscosity and flow rate of unstimulated saliva (P<0.001). Intra-item correlations were significantly different for salivary flow rates (r= 0.82 for unstimulated, r= 0.88 for stimulated, P< 0.001) and viscosity of unstimulated saliva (r= 0.54, P< 0.05), but viscosity of stimulated saliva was different in this respect. Our results indicate that there is a significant within-subject variation in viscosity of unstimulated saliva.

Adult↗
PubMedDate not supplied

Effects of long-term tobacco smoke exposure on whole blood viscosity in the rat.

The purpose of this study was to determine the effect of long-term tobacco smoke administration to rats on whole blood viscosity. Blood samples obtained from rats that had been administered tobacco smoke daily for a period of 10 wk and samples from normal cage control rats were placed in a cone-plate viscometer. Whole blood viscosities were measured at shear rates ranging from 23 to 230/sec. At every shear rate tested, blood viscosity from the smoke-treated animals was significantly higher than corresponding viscosities from the control rats. It is concluded that chronic tobacco smoke administration to rats increases the viscosity of whole blood, both at high shear rates where blood behaves rheologically as a Newtonian fluid and at low shear rates where blood displays non-Newtonian properties.

Animals↗
PubMed1992

Anti-nutritive effect of wheat pentosans in broiler chickens: roles of viscosity and gut microflora.

1. The mechanism of the anti-nutritive activity of isolated wheat pentosans was investigated by examining the roles of digesta viscosity and gut microflora in broiler chickens. 2. Wheat pentosans were isolated by alkaline extraction and purified by sequential treatment with pancreatin, alpha-amylase and lichenase, and high-speed centrifugation. Some of the pentosans were depolymerised using a beta-xylanase, which reduced the relative viscosity of the polysaccharides 4 fold. 3. Inclusion of 35 g alkali-extractable pentosans (containing 854 g arabinoxylans/kg DM) per kg diet significantly (P less than 0.05) depressed broiler performance and the viscosity of the digesta of these birds was significantly (P less than 0.05) higher than that of controls. Addition of the same amount of depolymerised pentosans had no significant effect on bird performance and had less effect on digesta viscosity. 4. Supplementation of the diet containing wheat pentosans (30 g/kg) with procaine penicillin (150 mg/kg) did not improve bird performance. 4. It is concluded that the wheat pentosans elicit their anti-nutritive activity predominantly through increasing the viscosity of digesta.

Animals↗
PubMed1992

Whole blood and plasma viscosity values in normal and ascitic broiler chickens.

1. Whole blood and plasma viscosity values in normal and ascitic broiler chickens were measured. 2. The mean blood viscosity value in ascitic broilers was greater than that of the controls. There was a small but significant difference in the opposite direction between plasma viscosity values of the respective groups of birds. 3. Although the haematocrit and arterial pressure index values in the ascitic birds were raised, there was a fall in the concentration of total plasma protein. 4. The data suggest that the raised viscosity in the ascitic birds was caused by a polycythemia and not by any influence of plasma protein. 5. The cumulative effect of these factors, such as raised blood viscosity values and larger deformed red cells flowing through constricted lung arterioles, may contribute to the pulmonary hypertension and ascites seen in some young commercial broilers.

Animals↗
PubMed2006

Viscosity as related to dietary fiber: a review.

Viscosity is a physicochemical property associated with dietary fibers, particularly soluble dietary fibers. Viscous dietary fibers thicken when mixed with fluids and include polysaccharides such as gums, pectins, psyllium, and beta-glucans. Although insoluble fiber particles may affect viscosity measurement, viscosity is not an issue regards insoluble dietary fibers. Viscous fibers have been credited for beneficial physiological responses in human, animal, and animal-alternative in vitro models. The following article provides a review of viscosity as related to dietary fiber including definitions and instrumentation, factors affecting viscosity of solutions, and effects of viscous polysaccharides on glycemic response, blood lipid attenuation, intestinal enzymatic activity, digestibility, and laxation.

Animals↗
PubMed2005

Effect of age of growing turkeys on digesta viscosity and nutrient digestibility of maize, wheat, barley and oats fed as such or with enzyme supplementation.

The effects of age of growing turkeys and beta-glucanase-xylanase activity-containing feed enzyme supplementation on digestibility and feeding value of pelleted maize, wheat, barley and oats were investigated in growing turkeys using excreta collection and ileal sampling by slaughter. Excreta were collected and turkeys were slaughtered at 4, 8 and 12 weeks of age. Viscosity of jejuno-duodenal digesta, caecal volatile fatty acid concentration, ileal crude protein digestibility, total tract fat digestibility and AMEN were assayed using titanium dioxide as an indigestible marker. The highest viscosities were observed in barley and wheat. Viscosity of wheat, barley and oats digesta decreased while caecal volatile fatty acid concentration, fat digestibility and AMEN increased with age. Ileal crude protein digestibility was highest in wheat and lowest in barley. Ileal crude protein digestibility significantly declined with age in most feeding treatments. Enzyme reduced digesta viscosity most efficiently in wheat and barley and improved ileal crude protein digestibility, total tract fat digestibility and AMEN in wheat, barley and oats, but interactions occurred, the effect of enzyme on viscosity being the most remarkable for wheat and barley and for the young birds.

Age Factors↗
PubMed1976

Blood viscosity and oral anticoagulant therapy.

During administration of bishydroxycoumarin, hematocrit, viscosity of whole blood, and viscosity of plasma decreased in samples from nine healthy volunteers and 31 patients who had coronary heart disease. The relationships between viscosity of blood and intensity of anticoagulant therapy varied from patient to patient. Discontinuation of the drug was followed by return of viscosities to pretreatment levels in two to four days. The decrease of viscosity of blood by anticoagulant therapy may explain the relief of anginal pain in patients who have coronary heart disease.

Administration, Oral↗
PubMed1992

Reduction of intestinal viscosity through manipulation of dietary rye and pentosanase concentration is effected through changes in the carbohydrate composition of the intestinal aqueous phase and results in improved growth rate and food conversion efficiency of broiler chicks.

The effect of dietary rye (0, 200, 400 and 600 g/kg substituting for wheat) and pentosanase concentration (0, 1, 2, 4, 8, 16 g/kg) on weight gain, molecular weight distribution of soluble carbohydrates in the intestinal lumen and lumenal viscosity in broiler chicks was investigated. A 4 x 6 factorial design was used with four replicates per treatment and six birds per replicate pen. Diets were fed from 1 to 19 d of age, at which time body weight, food intake and intestinal viscosity and molecular weight distribution of carbohydrate complexes in proximal and distal gut sections were determined. Weight gain and food conversion efficiency (FCE) improved with increasing pentosanase and decreasing rye concentration. Intestinal viscosity, which rose as digesta passed from the proximal to distal small intestine, fell with pentosanase addition and decreasing rye concentration. Intestinal viscosity, which correlated positively with reduced weight gain and FCE, was in turn correlated with the lumenal concentration of soluble high-molecular-weight carbohydrates (HMC, greater than 500 kDa), which constituted less than 15% of the total lumenal carbohydrate concentration. The arabinose and xylose content of the HMC increased with increasing rye concentration, suggesting that HMC composition in addition to concentration may determine intestinal viscosity. The results indicate that pentosanase isolated from rye by extraction methods may not be representative of those released by digestion.

Animal Feed↗
PubMed1997

Dietary carboxymethylcellulose with high instead of low viscosity reduces macronutrient digestion in broiler chickens.

The question addressed was whether the viscosity per se of dietary non-starch polysaccharides influences macronutrient digestion in broiler chickens. Water-soluble carboxymethylcellulose preparations of low (LCMC) or high viscosity (HCMC) were fed to broiler chickens (n = 10/group) from 21 to 35 d of age. The HCMC preparations reduced weight gain and raised water intake compared with LCMC. After the HCMC diet was fed, viscosity of the supernatant of small intestinal contents was significantly raised. The HCMC preparations raised the group mean ATP concentration in the digesta of duodenum plus jejunum, indicating that bacterial activity was increased. Consumption of HCMC depressed apparent fecal digestibility of lipids and nitrogen and also apparent ileal digestibility of starch. The dietary HCMC tended (P = 0.077) to reduce plasma triglyceride concentrations. After HCMC consumption, the weights of the small intestine and colon, without or with contents, were elevated. The data indicate that high viscosity of digesta in broiler chickens is associated with a reduced macronutrient digestion and impaired growth performance. Because the carboxymethylcellulose preparations were nonfermentable by fresh feces, we suggest that HCMC reduces macronutrient digestion by raising the viscosity of small intestinal contents, which is associated with enhanced bacterial fermentation due to accumulation of undigested material.

Animals↗
PubMed2003

Guar meal germ and hull fractions differently affect growth performance and intestinal viscosity of broiler chickens.

High concentrations of guar meal in poultry diets deleteriously affect growth, feed intake, and digesta viscosity. These effects are attributed to residual gum in the meal. A 2 x 5 factorial experiment investigated the impacts of two guar meal fractions (germ and hull) at five inclusion levels (0, 2.5, 5.0, 7.5, and 10.0%) on intestinal viscosity, measures of growth, and feed conversion in broiler chickens fed to 20 d of age. Growth and feed conversion ratio were not affected by inclusion of as much as 7.5% of the germ fraction into poultry diets, while inclusion of the hull fraction reduced growth at all concentrations. The hull fraction increased intestinal viscosity at all inclusion levels fed, although feed conversion was not affected until the inclusion rate exceeded 5.0%. The germ fraction significantly increased intestinal viscosity at 7.5 and 10% inclusion rates. When germ fraction was fed, relative organ weights remained constant through all concentrations except for the ventriculus and duodenum at 7.5 and 10% inclusion levels. Relative pancreas weight was significantly increased at the 10% level of the hull fraction. Increases in intestinal viscosity corresponded with growth depression. These results suggest that residual gum was responsible for some deleterious effects seen when guar meal was fed. The germ fraction was a superior ingredient when compared with the hull fraction. The guar meal germ fraction constituting as much as 7.5% of the diet supported growth and feed conversion measures similar to those observed with a typical corn-soybean poultry ration.

Animal Nutritional Physiological Phenomena↗
PubMed2003

beta-Mannanase ameliorates viscosity-associated depression of growth in broiler chickens fed guar germ and hull fractions.

High concentrations of guar meal in broiler chicken diets reduce body weight and feed efficiency. The increased intestinal viscosity that is responsible for reduced measures of performance results from residual guar gum present in guar meal. Two experiments were designed to study the effects of 2 guar meal fractions at 3 different concentrations, germ (0, 5.0, and 7.5%) and hull (0, 2.5, and 5.0%), and the effectiveness of a beta-mannanase at three levels (0, 1x, and 4x; 1x = 1.09 x 10(5) units/ kg) on broiler growth and feed conversion. Growth and performance were measured as a function of intestinal viscosity. Addition of the germ fraction to rations did not reduce body weight, although feed conversion ratio was increased at 7.5% of the diet. Intestinal viscosity also increased significantly at this level. Enzyme addition significantly reduced intestinal viscosity. Due to an interaction that was present between hull and enzyme concentration, each treatment was compared separately. Inclusion of the hull fraction significantly reduced body weight at both levels of inclusion and increased feed conversion ratio at 5% inclusion. Addition of the enzyme significantly increased body weight and reduced feed conversion ratio in diets containing guar hull fractions. Supplementation of beta-mannanase to feeds containing either fraction of guar meal reduced intestinal viscosity and alleviated the deleterious effects associated with guar meal feeding.

Animal Nutritional Physiological Phenomena↗
PubMed1987

Erythrocyte sedimentation rate, plasma and serum viscosity as measures of disease activity in rheumatoid arthritis.

The activity of rheumatoid arthritis was assessed in 96 unselected out-patients by performing a number of clinical measurements and comparing them to ESR, plasma and serum viscosity. It was found that ESR correlated with clinical parameters better than did both plasma and serum viscosity. These tests were repeated 3 months later in 87 of the same patients and again change in ESR correlated with change in disease activity better than did change in plasma viscosity. Plasma viscosity was a consistently more reliable measure of disease activity than was serum viscosity.

Arthritis, Rheumatoid↗
PubMed1991

The nature and reversibility of hypothermia-induced alterations of blood viscosity.

This study evaluates the nature and reversibility of the increase in whole blood viscosity known to be induced by hypothermia. Anticoagulated samples were obtained from normal volunteers and were assayed for cellular deformability by 4.7 microns membrane filtration of whole blood (n = 12) and washed RBCs (n = 10). Results were expressed as filtration rate. Specimens were evaluated for plasma (n = 10) and whole blood (n = 12) viscosity by cone plate viscometer. All assays were sequentially performed at 30 degrees, 34 degrees, and 37 degrees C and difference analyzed by paired t test. Hypothermia resulted in significant impairment of cellular deformability, which was reversed by rewarming: [table: see text] Hypothermia also resulted in a significant increase in plasma viscosity (mean difference = 0.5426 centipoise, p less than 0.02), which was likewise reduced on rewarming. The increase in whole blood viscosity associated with hypothermia is secondary to both diminished cellular deformability and increased plasma viscosity. Both of these alterations are reversible with appropriate rewarming.

Blood Viscosity↗
PubMed1998

Viscosities of implantable biomaterials in vocal fold augmentation surgery.

Vocal fold vibration depends critically on the viscoelasticity of vocal fold tissues. For instance, phonation threshold pressure, a measure of the "ease" of phonation, has been shown to be directly related to the viscosity of the vibrating mucosa. Various implantable biomaterials have been used in vocal fold augmentation surgery, with implantation sites sometimes close to or inside the mucosa. Yet their viscosities or other mechanical properties are seldom known. This study attempts to provide data on viscosities of commonly used phonosurgical biomaterials. Using a parallel-plate rotational rheometer, oscillatory shear experiments were performed on implantable polytetrafluoroethylene (Teflon or Polytef; Mentor Inc., Hingham, MA), collagen (Zyderm; Collagen Corp., Palo Alto, CA), glutaraldehyde crosslinked (GAX) collagen (Phonagel or Zyplast; Collagen Corp.), absorbable gelatin (Gelfoam; Upjohn Co., Kalamazoo, MI), and human abdominal subcutaneous fat. Samples of human vocal fold mucosal tissues were also tested. Under sinusoidal oscillatory shear at 10 Hz and at 37 degrees C, the dynamic viscosity was 116 Pascal-seconds (Pa-s) for polytetrafluoroethylene, 21 Pa-s for gelatin, 8-13 Pa-s for the two types of collagen, 3 Pa-s for fat, and 1 to 3 Pa-s for vocal fold mucosa. Results extrapolated to 100 Hz also show similar differences among the biomaterials, but all values are an order of magnitude lower because of the typical inverse frequency relation (shear thinning effect) for polymeric and biologic materials. The data suggest that the use of fat for vocal fold augmentation may be more conducive to the "ease" of phonation because of its relatively low viscosity, which is closest to physiologic levels. This implication is probably the most relevant in predicting initial outcome of the postoperative voice before there is any significant assimilation (e.g., resorption and fibrosis) of the implanted biomaterial.

Abdomen↗