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PubMed1988

[Hyperfibrinogenemia and pathological plasma viscosity. Pathogenetic factors in unstable angina pectoris?].

Plasma viscosity and erythrocyte aggregation, as the most important rheological factors in the microcirculation, and fibrinogen were measured in the blood of groups of patients in various stages of coronary-heart disease. Patients with unstable angina had viscosity and fibrinogen levels, even before any manifest infarction, that were higher than those of patients with stable angina. Plasma viscosity and hyperfibrinogenaemia (1.39 +/- 0.08 mPa.s in 48 patients and 394.4 +/- 82.7 mg/dl, respectively, in 33) were comparable to the values in patients with acute myocardial infarction (1.37 +/- 0.09 mPa.s [n = 45] and 390.2 +/- 126.9 mg/dl [n = 27], but significantly higher (P less than 0.02) than in those with stable angina (1.33 +/- 0.08 mPa.s [n = 78] and 295.3 +/- 68.6 mg/dl [n = 44], respectively). This abnormal viscosity in unstable angina plays a part in increasing myocardial ischaemia because oxygen delivery is already diminished and capillary flow slowed down. It thus contributes to progression of the angina and must be taken into account as an additional pathogenetic factor in the clinical instability.

Angina Pectoris↗

PubMed2000

Relationship of intracanal pressure with viscosity of endodontic sealer during warm Gutta-Percha vertical compaction.

OBJECTIVE: To test the association between endodontic sealer viscosity and intracanal pressure during warm gutta-percha vertical compaction. STUDY DESIGN: An artificial tooth model and pressure-sensing apparatus were developed so that reproducible, quantitative measurements could be determined. Intracanal pressure was measured at 3 phases of obturation: cone insertion, heat application, and force application. Samples were randomly assigned to 3 sealer viscosity groups (most viscous, normal, least viscous) and to a no-sealer group. Evaluations were blinded to group assignments (4 groups, 15 samples per group). RESULTS: Differences in intracanal pressure were detected between sealer viscosity groups. The most viscous group had the largest intracanal pressure. Throughout the phases of obturation, intracanal pressure did not remain constant; values at the time of heat application were lower than at cone insertion and force application. CONCLUSIONS: The results indicate that intracanal pressure increases as sealer viscosity is increased, and that intracanal pressure does not remain constant during obturation.

Analysis of Variance↗

PubMed2002

Increasing the viscosity of the intestinal contents stimulates proliferation of enterotoxigenic Escherichia coli and Brachyspira pilosicoli in weaner pigs.

The present study was designed to evaluate the effect of increased viscosity of the intestinal digesta on proliferation of enterotoxigenic Escherichia coli and the intestinal spirochaete Brachyspira pilosicoli in weaned pigs. Pigs were fed an experimental diet based on cooked white rice (R), which was supplemented with carboxymethylcellulose (CMC; 40 g/kg diet) to increase digesta viscosity. Thirty-six piglets weaned at 21 d of age were divided into six groups, three of which were fed R and three Addition of CMC increased digesta viscosity in the ileum (P=0.01), caecum (P=0.0007) and colon (P=0.0035), without increasing indices of large intestinal fermentation. Pigs fed developed a natural infection with enterotoxigenic E. coli after weaning and had more (P<0.0001) diarrhoea than pigs fed R. Subsequent experimental infection of two groups of pigs with B. pilosicoli resulted in more (P<0.0001) colonisation in pigs fed than R. At this time, all pigs fed had wetter (P<0.0001) faeces than those fed R, irrespective of whether they were infected with B. pilosicoli, but infected pigs also had an increased (P=0.025) number of days with diarrhoea post-infection irrespective of diet. In pigs fed it was not clear to what extent the increased viscosity associated with CMC, or the concurrent infection with enterotoxigenic E. coli, was responsible for the increased proliferation of B. pilosicoli. In a second experiment, five pigs that were weaned onto an R diet were transferred onto 3 weeks later. These pigs did not develop a natural infection with enterotoxigenic E. coli after the diet change, confirming the particular susceptibility of pigs to enterotoxigenic E. coli proliferation immediately post-weaning.

Analysis of Variance↗

PubMed2004

Addition of pearl barley to a rice-based diet for newly weaned piglets increases the viscosity of the intestinal contents, reduces starch digestibility and exacerbates post-weaning colibacillosis.

The purposes of the present study were to investigate the effects of feeding a cereal grain containing NSP on body growth and the intestinal microenvironment of recently weaned pigs, and to examine resultant associations with pathogenic Escherichia coli in the intestinal tract. In Expt 1, pearl barley, a grain rich in soluble NSP, was incorporated (250, 500 or 750 g/kg diet) into a low-fibre control diet based on cooked white rice and fed for 7-10 d following weaning. Consumption of pearl barley did not significantly alter piglet live-weight gain compared with the control cooked rice diet, but it accelerated large intestinal growth and fermentation, decreased ileal starch digestibility and increased intestinal viscosity. Expt 2 was conducted to determine whether these differences would favour proliferation of enterotoxigenic E. coli, the bacterium causing post-weaning colibacillosis (PWC). Three groups of pigs were weaned onto diets based on cooked white rice, rice with 500 g pearl barley/kg, or rice with 500 g pearl barley/kg supplemented with exogenous enzymes (Porzyme 8100; Danisco, Marlborough, Wilts., UK). Pigs were inoculated orally with haemolytic E. coli serovar O8;K87;K88 after weaning. Animals eating the pearl barley had increased viscosity of the intestinal contents, greater intestinal colonisation with the E. coli strain and more diarrhoea than pigs fed the rice-only diet. The enzymes did not reduce viscosity or protect from PWC. The results suggest that pearl barley alters the intestinal microenvironment and predisposes to PWC, whilst a low-viscosity, highly digestible diet based on cooked white rice is protective.

Animal Feed↗

PubMed2005

Interface evaluation after manual and ultrasonic insertion of standardized class I inlays using composite resin materials of different viscosity.

OBJECTIVE: The aim of the present study was to investigate the effect of manual and ultrasonic insertion of standardized class I inlays (Cerana) using three composite resin materials of different viscosity (Tetric Flow, Tetric, and Tetric Ceram) on time to seat inlays, film thickness, and filler distribution within the materials. METHODS: In a preliminary test, mean loads for manual and ultrasonic insertion were measured using the high viscosity composite resin material (Tetric Ceram). These loads were then applied with all composite resin materials to evaluate the times required to seat the inlays. In addition, film thickness was assessed using scanning electron microscopy, and filler distribution (wt% silicon, barium, ytterbium) was monitored using energy-dispersive spectroscopy. RESULTS: Ultrasonic insertion significantly reduced mean load applied to seat inlays (6.4+/-1.4 N; mean+/-SD) as compared to manual insertion (18.9+/-3.1 N; p < 0.001). Using an ultrasonic device, times for insertion values were significantly lower in the high and medium viscosity composite resin material groups compared to manual insertion (p < 0.05). The widest film thickness was recorded for the high viscosity composite resin material in combination with manual insertion (p < 0.05). However, when ultrasound was applied, there was no difference in film thickness between the three materials at any levels. Furthermore, the analysis of filler distribution revealed no significant differences between groups. CONCLUSION: Highly filled viscous composite resin materials may be used in combination with the ultrasonic insertion technique without untoward effects on film thickness or filler distribution.

Barium↗

PubMed2002

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24 kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine + cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276 mg per 12 h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150 mg per 12 h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.

Animal Feed↗

PubMed1996

Plasma viscosity values and the relationship with age and sex in normal commercial broiler and layer strains of chickens.

1. The plasma viscosity values of normal commercial broiler and layer strains of chicken were measured in relation to age and sex. 2. In both broilers and layers plasma viscosity values decreased at 2 weeks of age; probably reflecting the period of change from maternal plasma protein to the bird's self-synthesised proteins. 3. There was a progressive rise in plasma viscosity in both strains and sexes with age. The increase was greatest in female layers at 17 weeks of age before lay. 4. There was no overall significant difference in viscosity values between fresh and frozen-stored plasma samples.

Aging↗

PubMed1998

Effects of food and water withdrawal and high temperature exposure on diurnal variation in blood viscosity of broiler chickens.

1. Three experiments were conducted to investigate the diurnal variation of blood viscosity in broilers. In experiment 1 food and water were supplied freely at 20 degrees C (20-FW). In experiment 2 food and water were withdrawn at 20 degrees C (20-NFW), while in experiment 3 food and water were withdrawn at 30 degrees C (30-NFW). 2. Blood sampling time points were 09.00 h, 15.00 h, 21.00 h, 03.00 h and 09.00 h the next day in each experiment. 3. In all experiments, whole blood viscosity (WBV), red blood cell count (RBC) and haematocrit (HCT) were greater during the dark (21.00 h and 03.00 h) than during the light period. During the dark period, there were no differences in WBV, RBC and HCT between 20-FW and 20-NFW, or between 20-NFW and 30-NFW. At 09.00 h, WBV and HCT were higher in 20-FW than in 20-NFW. At 15.00 h and 09.00 h (day 2), WBV and HCT were greater in 20-NFW than in 30-NFW. 4. There were no light-dark differences in plasma viscosity (PV), plasma protein concentration (PPC) or mean corpuscular volume (MCV) in any experiment. However, 20-NFW birds had a lower PPC and higher MCV compared with 20-FW, and a higher PPC and lower MCV compared with 30-NFW, while no difference was found in PV. 5. WBV increased linearly with RBC and HCT. PV increased with PPC, while MCV decreased. 6. These results indicate that there is diurnal variation in whole blood viscosity, which is greater during the dark than during the light period. During the light period it is strongly influenced by high environmental temperature and food and water withdrawal.

Acclimatization↗

PubMed1995

Physical properties of cerebrospinal fluid of relevance to shunt function. 1: The effect of protein upon CSF viscosity.

Viscosity is the resistance to flow of a fluid and it is the only property of a fluid that will affect its flow through a system of valveless tubing (surface tension will affect the opening and closing of valves that are included in the system). The effect that an elevated protein concentration has upon CSF viscosity has received little study, yet many neurosurgeons believe that CSF with an elevated protein content is too viscous to flow satisfactorily through shunts. The total protein content and viscosity of 126 specimens of CSF from hydrocephalic patients were measured and analysed with reference to the aetiology of the hydrocephalus. The results indicate that high protein concentrations do not greatly affect the viscosity of CSF, and that the aetiology is also of little consequence. These findings were highly significant on linear regression analysis (p < 0.001). The flow of the most viscous CSF that is likely to be encountered would be reduced by only 7% through a given catheter, compared with that of the least viscous CSF.

Adolescent↗

PubMed1997

Urine viscosity after injections of iotrolan or iomeprol.

PURPOSE: Previous observations in rats caused us to speculate whether the injection of iotrolan, a nonionic dimeric contrast medium (CM), would increase urine viscosity enough to obstruct urine outflow in the collecting duct. MATERIAL AND METHODS: The urine viscosity in dogs was measured directly with a viscosimeter after injections of iotrolan or of iomeprol, a nonionic monomeric CM. RESULTS AND CONCLUSION: The injection of iotrolan increased urine viscosity considerably whereas iomeprol had little effect on this variable. The osmolality-dependent adverse reactions of CM have previously been emphasized but viscosity-dependent adverse reactions must also be considered when the CM is a polymer with a low osmolality.

Animals↗

PubMed1998

Iodine concentrations in the rat kidney measured by X-ray microanalysis. Comparison of concentrations and viscosities in the proximal tubules and renal pelvis after intravenous injections of contrast media.

PURPOSE: To measure the iodine concentrations in the proximal tubules and renal pelvis after i.v. injections of contrast media (CM) at 1600 mg I/kg b.w., using a micropuncture technique and X-ray microanalysis. MATERIAL AND METHODS: The correlation between the viscosity of each CM and its iodine concentration was evaluated and the viscosity of the fluid in the proximal tubule and renal pelvis was estimated in rats. RESULTS: After iotrolan injection, the iodine concentration in the proximal tubular fluid had increased to values about three times higher than those reached with diatrizoate, iohexol and ioxaglate. Similarly, iotrolan tended to produce a higher iodine concentration in the renal pelvis than did the other CM. The urine viscosity in the renal pelvis was much higher after the iotrolan injection than after the other CM injections. CONCLUSION: High urine viscosity after iotrolan injection can at least partly explain our previous findings of a prolonged increase in tubular hydrostatic pressure and a prolonged decrease in the single nephron glomerular filtration rate after administration of this CM.

Animals↗

PubMed2006

Prebiotic oligosaccharides reduce stool viscosity and accelerate gastrointestinal transport in preterm infants.

AIM: To investigate whether a mixture of prebiotic non-digestible oligosaccharides (GosFos; referring to galacto- and fructo-oligosaccharides) would improve feeding tolerance in preterm infants on full enteral formula feeding. We hypothesized that GosFos would: (1) reduce stool viscosity and (2) accelerate gastrointestinal transport. METHODS: In a placebo-controlled double-blind trial 20 preterm infants on full enteral nutrition (gestational age 27 (24-31) weeks, postnatal age 42 (11-84) days, and weight at study entry 1570 (1080-2300) g were randomly allocated to have their feedings supplemented with either GosFos (1 g/100 mL) or placebo for 14 days. Stool viscosity was measured by high-pressure capillary rheometry. Gastrointestinal transport time was assessed as the time from feeding carmine red to its appearance in the diaper. The hypotheses were tested as a priori ordered hypotheses. Data are shown as median (range). RESULTS: Birth weight, gestational age, postnatal age, and weight at study entry did not differ between groups. GosFos significantly reduced both stool viscosity, as measured by extrusion force (32 (2-67) versus 158 (24-314) N), and gastrointestinal transit time (12 (4-33) versus 26 (5-52) h). No adverse effects were observed. CONCLUSION: Formula supplementation with GosFos reduced stool viscosity and accelerated gastrointestinal transport. Further trials are required to investigate whether GosFos facilitates enteral feeding advancement and early enteral nutrition thereby eventually reducing the incidence of catheter-related nosocomial infections and improving long-term outcome.

Body Weight↗

PubMed2004

A novel thermodynamic relationship based on Kramers Theory for studying enzyme kinetics under high viscosity.

In most studies of enzyme kinetics it has been found sufficient to use the classical Transition State Theory (TST) of Eyring and others. This theory was based on the solvent being an ideal dilute substance treated as a heat bath. However, enzymes found in organisms adapted to very low (psychrophiles) and very high (thermophiles) temperatures are also subjected to variable solute concentrations and viscosities. Therefore, the TST may not always be applicable to enzyme reactions carried out in various solvents with viscosities ranging from moderate to very high. There have been numerous advances in the theory of chemical reactions in realistic non-ideal solvents such as Kramers Theory. In this paper we wish to propose a modified thermodynamic equation, which have contributions from kcat, Km and the viscosity of the medium in which the enzyme reaction is occurring. These could be very useful for determining the thermodynamics of enzymes catalyzing reactions at temperature extremes in the presence of substrate solutions of different compositions and viscosities.

Catalysis↗

PubMed1999

Development and evaluation of a laboratory-scale apparatus to simulate the scale-up of a sterile semisolid and effects of manufacturing parameters on product viscosity.

The purpose of this study was to develop a benchtop apparatus to simulate the scale-up of the moist-heat sterilization process of sodium carboxymethylcellulose (CMC) gel and identify critical process parameters that affect the sterilized gel viscosity. A 600-ml benchtop Parr reactor was modified and used to achieve good correlation with a previously established heating profile using different equipment at the manufacturing site. The Parr reactor is constructed with 316 stainless steel, pressure rated to 2000 psig, and temperature rated to 350 degrees C. After several trials, a low-wattage heater (300 W) was determined to be suitable for this sterilization process (122 degrees C for 20 min). An anchor stirrer was installed for more efficient mixing while the gel was being sterilized. Evacuation and nitrogen flushing of the vessel could easily be performed through the gas inlet valves. The temperature controller (model 4843) has a microprocessor-based control module that provides a temperature profile control with adjustable tuning parameters. This apparatus was used to mimic the full-scale sterilization process by simulating the production sterilization temperature profile. Using this device, we found that the critical process parameters that affected final product viscosity were heating time, the starting pressure, residual oxygen concentration in the vessel, and the inherent viscosity of the CMC raw material. This study indicated that it is possible to use the Parr reactor to simulate the scale-up sterilization process of a semisolid product. A product with a consistent viscosity range could be manufactured by controlling critical process parameters during sterilization.

Carboxymethylcellulose Sodium↗

PubMed1993

Effect of dietary viscosity on energy intake by breast-fed and non-breast-fed children during and after acute diarrhea.

To determine the effect of dietary viscosity on energy consumption by young children, 56 Peruvian children 9-20 mo of age with acute diarrhea were randomly assigned to either a liquid or semisolid diet, with or without added amylase to reduce viscosity. Intakes of the study diet, breast milk, and other foods were measured for 2 consecutive d during and again after illness. Total 24-h energy intake (chi +/- SD) during diarrhea, 349.4 +/- 121.8 kJ/kg (83.6 +/- 29.1 kcal/kg) was 18% less than intake after recovery, 428.9 +/- 141.0 kJ/kg (102.6 +/- 33.7), P < 0.001. In the ANOVA breast-fed children consumed significantly less total energy (P = 0.008) and energy from the study diet (P = 0.02) than non-breast-fed children. Breast milk intake did not change with illness. There was no significant relationship between viscosity of the study diet and either total energy intake or intake of energy from the study diet. Energy intake by these children was primarily determined by health status and breast-feeding practice, not by dietary viscosity.

Acute Disease↗

PubMed2004

Paradoxical increases in serum IgM and viscosity levels following rituximab in Waldenstrom's macroglobulinemia.

BACKGROUND: The anti-CD20 monoclonal antibody rituximab is an important therapeutic in Waldenstrom's macroglobulinemia (WM), producing response rates of 50-70%. Responses, which are based on serum IgM levels, have typically been evaluated at 12 weeks. Paradoxically, we have observed that serum IgM levels can abruptly rise following rituximab therapy in patients with WM, and can often lead to morbidity on the basis of hyperviscosity. PATIENTS AND METHODS: Eleven WM patients with CD20+ tumor cells who received rituximab at our Institution and had serum IgM levels measured within a 12-week period following start of therapy were evaluated. Therapy consisted of four weekly infusions of rituximab at 375 mg/m(2). Pre- and post-therapy serum IgM levels were determined by nephelometry and corresponding serum viscosity levels were determined by viscometry. RESULTS: Ten of the 11 patients demonstrated an abrupt rise in serum IgM levels, with a >25% increase occurring in eight (73%) patients. Mean serum IgM levels for all 10 spiking patients rose from 4370 (range, 655-7940) to a peak of 5865 (range, 872-11 800) mg/dl (P=0.004), which occurred at a mean of 4 (range, 1-8) weeks following initiation of therapy. Mean serum viscosity levels also increased from 3.5 to 5.6 centipoise (CP) (P=0.09) in eight patients for whom pre- and post-therapy studies were obtained. A subdural hemorrhage occurred in one patient when serum IgM levels rose from 7530 to 11 800 mg/dl, and serum viscosity increased from 3.9 to 10.1 CP. Two other spiking patients with pre-therapy IgM levels of >5000 mg/dl experienced worsening headaches and/or epistaxis attributed to increasing serum viscosity. CONCLUSIONS: Abrupt increases in serum IgM levels commonly occur following rituximab therapy in WM. Careful clinical and laboratory monitoring is warranted, particularly if patients have pre-therapy serum IgM levels of >5000 mg/dl. The mechanism of this effect is under active investigation, and may be related to CD20 signaling triggered by rituximab.

Antibodies, Monoclonal↗

PubMed1979

Plasma viscosity and cremophor-containing anaesthetics.

The cremophor-containing anaesthetic agents, Althesin, propanidid and diazepam, were added to plasma in vitro and administered to patients. In vitro these anaesthetics, and cremophor alone in concentrations equal to those obtained in vivo, decreased the viscosity of plasma 45% at shear rate 11.5 s-1. In 11 patients given cremophor-containing anaesthetics to induce anaesthesia, plasma samples obtained 5 min after injection showed a mean decrease in viscosity of 42% compared with the pre-induction values. The effect on viscosity after a single dose disappeared in 50 min. Triton x-100 added to plasma caused a decrease in viscosity similar to that of cremophor. The interaction in vitro of cremophor and Triton x-100 with concentrated urea was found to be identical both in plasma and dextran. This suggests that cremophor acts by increasing the sheet of structured water around the protein molecules, thereby preventing the aggregation of proteins.

Adult↗

PubMed2001

Viscosity and density of common anaesthetic gases: implications for flow measurements.

Although viscosity (mu) is a crucial factor in measurements of flow with a pneumotachograph, and density (rho) also plays a role in the presence of turbulent flow, these material constants are not available for the volatile anaesthetic agents commonly administered in clinical practice. Thus, we determined experimentally mu and rho of pure volatile anaesthetic agents. Input impedance of a rigid-wall polyethylene tube (Zt) was measured when the tube was filled with various mixtures of carrier gases (air, 100% oxygen, 50% oxygen+50% nitrogen) to which different concentrations of volatile anaesthetic inhalation agents (halothane, isoflurane, sevoflurane, and desflurane) had been added. Mu and rho were calculated from real and imaginary portions of Zt, respectively, using the appropriate physical equations. Multiple linear regression was applied to estimate mu and rho of pure volatile agents. Viscosity values of pure volatile agents were markedly lower than those for oxygen or nitrogen. Clinically applied concentrations, however, did not markedly affect the viscosity of the gas mixture (maximum of 3.5% decrease in mu for 2 MAC desflurane). In contrast, all of the volatile agents significantly affected rho even at routinely used concentrations. Our results suggest that the composition of the carrier gas has a greater impact on viscosity than the amount and nature of the volatile anaesthetic agent whereas density is more influenced by volatile agent concentrations. Thus, the need for a correction factor in flow measurements with a pneumotachograph depends far more on the carrier gas than the concentration of volatile agent administered, although the latter may play a role in particular experimental or clinical settings.

Anesthetics, Inhalation↗