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PubMedDate not supplied

[Cement delivery depends on cement gun performance and cement viscosity].

AIM: Retrograde cement application is considered an integral part of the modern femoral cementing technique. Both pressurisation and rapid cement application reduce the risk of interface bleeding and blood laminations. In this context cement gun performance has received little attention. METHOD: In our study we examined the handling characteristics of four different cement delivery systems (Syringe, Vaku-Mix, Optivac and MixOR-System). To allow for cement viscosity as another variable, six different bone cements (Palacos R, Palamed G, CMW 1 Radiopak, CMW 2000, Simplex P, VersaBond) were used with each system. We recorded cement gun performance and measured extrusion times and maximum cement delivery speeds of all possible combinations (gun/mixing system plus cement type). RESULTS: The fastest cement application could be achieved with the Vaku-Mix cement delivery system and the corresponding cement gun (Mark III). With regard to cement type, VersaBond and prechilled Palacos yielded significantly shorter extrusion times than most of the other cements due to their lower viscosities. CONCLUSION: Our results have shown significantly different efficacies of commonly used cement delivery systems/guns in clinical routine. Improved systems should be provided by the suppliers.

Arthroplasty, Replacement, Hip↗
PubMed1995

[Effects of viscosity, cannula size and temperature in mechanical contrast media administration in CT and magnetic resonance tomography].

PURPOSE: Mechanical contrast media application is used to improve image quality and allow better quantitative assessment of the contrast media kinetics for CT as well as MRI. The pressure within the i.v. line system must be known to enable safe and quantitatively exact application. MATERIAL AND METHODS: Experimental setup to analyse the inline pressure, the storage volume as well as the exactness of delivery within the i.v. line system was prepared. Representative contrast media Ultravist 300, Ultravist 370, Magnevist and Conray 60 as well as 0.9% NaCl were measured with ten different flow rates from 0.1 ml/sec to 5.0 ml/sec using the six most common i.v. cannula sizes (22G-14G). RESULTS: System pressures between 38-60 psi (maximum allowed system pressure = 60 psi) are commonly obtained with standard sizes of i.v. cannulas, such as an 18 G cannula and flow rates > or = 2.5 ml/sec using Ultravist 300 (viscosity 13 mPa.s at 20 degrees C). Higher system pressures (> 25 psi) produce an exponential increase of the storage volume within the i.v. line system. The additional storage volume within the i.v. line tubing (d = 2.9 mm, 76 shore) is at 60 psi and 20 degrees C 5 ml/m, and at 37 degrees C 11 ml/m in addition to the volume of the tubing of 7 ml/m. CONCLUSION: Based on the measured data, both the minimum and the recommended sizes of the i.v. cannulas in respect of flow rate and viscosity of the used contrast media were compiled for system pressures at < or = 60 psi as well as < or = 38 psi.

Catheterization↗
PubMed1983

Blood viscosity and erythrocyte filterability: their evaluation in diabetes mellitus.

Blood viscosity and erythrocyte filterability were assessed in forty-five diabetics subdivided for type and vascular complications. From the obtained data, it is evident that blood viscosity at high shear rates does not distinguish diabetics from normals nor diabetics from one another, whereas at low shear rates it is able to differentiate normals from diabetics and diabetics with and without vascular complications. As for the erythrocyte filterability, it is evident that the Vrbc, obtained by filtering whole-blood, distinguishes diabetics from normals, whereas this does not happen with the DI, obtained by filtering red blood suspended (5%) in prefiltered autologous plasma.

Adolescent↗
PubMed1991

Umbilical artery flow velocity waveforms and cord blood viscosity.

The role of cord blood viscosity in determining the umbilical artery Doppler flow velocity waveform (FVW) was investigated in 22 normal pregnancies and 29 complicated pregnancies. FVWs were quantified by calculating the pulsatility index (PI). There was a significant correlation between an abnormal PI (more than 2 SD from the mean) and fetal growth retardation (less than 5th birthweight centile), cesarean section for fetal distress, and raised cord blood hematocrit. However, there was no relationship between whole blood or plasma viscosity measurements and the umbilical artery PI.

Birth Weight↗
PubMed1989

[Effect of fenofibrate on fibrinogen concentration and blood viscosity. Consequences for myocardial microcirculation in coronary heart disease?].

The effect of fenofibrate (a clofibrate derivative) on fibrinogen concentration, blood viscosity and myocardial microcirculation was examined in 35 patients with coronary heart disease (n = 27) or hypertension (n = 8). After eight weeks' administration of 250 mg fenofibrate daily cholesterol and triglycerides levels decreased significantly, as did the fibrinogen concentration, from a mean of 300.7 +/- 75.1 mg/dl to 252.3 +/- 61.2 mg/dl (P less than 0.01). Plasma viscosity and erythrocyte aggregation were also significantly lowered (from 1.43 +/- 0.09 to 1.37 +/- 0.07 mPas and 15.0 +/- 3.1 to 13.5 +/- 2.2, respectively; P less than 0.01). In eight of twelve subjects selected from the whole group thallium myocardial scintigraphy demonstrated, after eight weeks of treatment with fenofibrate, a global (in two) or regional (in six) increase in blood flow. Reduction of fibrinogen concentration may in coronary heart disease achieve an improvement in myocardial microcirculation with decreased myocardial ischaemia.

Blood Viscosity↗
PubMed1980

[Improvement of blood viscosity in sickle-cell anaemia by pentoxifylline (author's transl)].

An 18-yer-old girl with homozygotic sickle-cell anaemia (HbSS: HbS 65% and HbF 4.9%) suffered from painful haemolytic crises since six years of age, these crises occurring almost weekly of late. Pentoxifylline (2.4 g daily in three divided doses) decreased blood viscosity in vitro from 6.7 to 4.9 (normal 4.3-5.3 at 46 s-1 shear rate) and erythrocyte filtration accelerated from 127 to 77 s (normally 30-49 s). Although pentoxifylline could not prevent haemolysis, previously necessary analgesics were no longer required, even during haemolytic crises. Thus the drug lowers viscosity also in vivo and thus improves microcirculation. It has a prophylactic effect against vaso-occlusive complications of sickle-cell anaemia.

Adolescent↗
PubMed1974

Homeoviscous adaptation--a homeostatic process that regulates the viscosity of membrane lipids in Escherichia coli.

E. coli incorporates increasing proportions of saturated and long-chain fatty acids into phospholipids as growth temperature is increased. It was found that this compositional variation results in the biosynthesis of phospholipids that have identical viscosities at the temperature of growth of the cells. This "homeoviscous adaptation" can also be observed in E. coli membrane preparations. Viscosities were determined by use of the electron spin resonance spin-label technique.

Cell Membrane↗
PubMed1990

Alpha-amylase (EC 3.2.1.1) susceptibility rather than viscosity or gastric emptying rate controls plasma responses to starch in healthy humans.

The relationship between starch alpha-amylase (EC 3.2.1.1) susceptibility, plasma responses and gastric emptying rates has been investigated in humans. Nine randomly chosen healthy subjects were given three carbohydrate test meals (25 g starch or equivalent glucose units): two maize starch pastes with (a) 240 (S24) or (b) 500 (S50) g amylose/kg, and a glucose solution (GS). At 30 min, in vitro starch alpha-amylolysis was 48 (SD 4)% for S24 and 35 (SD 4)% for S50. Test meals differed in viscosity (mPa x s: S24, 54,000; S50, 190; GS, 4). Carbohydrates were labelled with 99mTechnetium and isotope gastric emptying was measured by external gamma counting. Carbohydrate isotopic gastric emptying patterns were exponential. Half gastric emptying time (min) was significantly (P less than 0.05) shorter for S50 (19(SD 2] than for GS (26(SD 2] or S24 (29(SD 2]. No correlation was found between half gastric emptying time and plasma response values. Values for peak insulin (pmol/l) above fasting were significantly (P less than 0.05) different: GS, 306 (SD 11); S24, 227 (SD 11); S50, 187 (SD 11). It is concluded that alpha-amylase susceptibility of the test carbohydrates is a determining factor in the insulin response of healthy subjects, while viscosity of the test meals and gastric emptying rate have no effect.

Adult↗
PubMed2003

Effect of whole and demucilaged linseed in broiler chicken diets on digesta viscosity, nutrient utilisation and intestinal microflora.

1. A study was undertaken to evaluate the effects of the inclusion of linseed or demucilaged linseed in the diet on the performance, fat and fatty acid digestibilities, metabolisability of gross energy and intestinal microflora. 2. The dietary inclusions were 80 and 160 g/kg for linseed and 160 g/kg for demucilaged linseed. Diets were given to chickens from 1 to 23 d of age. 3. Incorporation of linseed in the diet, particularly at 160 g/kg, depressed weight gain and food utilisation. Digestibility of fat and single fatty acids and dietary metabolisable energy were reduced. 4. Inclusion of linseed in the diet markedly increased the viscosity of ileal digesta. Microbial activity in the ileum and caeca was not greatly affected, but there was a significant increase in the number of lactobacilli. 5. The antinutritional effects caused by feeding linseed were partially overcome by substituting demucilaged linseed for linseed in the diet. 6. Results from the current study suggest that the viscous properties of mucilage are a major factor in the observed antinutritional effects of linseed through increasing intestinal viscosity. Such effects might also be mediated by the gut microflora.

Animal Feed↗
PubMed1983

Improvement of the nutritive value of rye for broiler chickens by gamma irradiation-induced viscosity reduction.

A study was undertaken with chickens to determine the effect of irradiation treatment on the viscosity-inducing properties of polysaccharide components of rye. Three-week body weight, food utilisation, fat retention, and bone ash of chicks were substantially improved by irradiating rye (0 to 10 Mrad) and were maximal at 6 Mrad. Irradiation of the entire diet resulted in no further improvement over irradiating the rye fraction alone. The improved performance coincided with radiation-induced damage to rye polysaccharides, as indicated by reduced viscosity and increased concentrations of reducing sugars.

Animals↗
PubMed1997

Effects of early heat exposure on thermoregulatory responses and blood viscosity of broilers prior to marketing.

1. This study was to determine the effects of heat load early in life on thermoregulatory responses and whole blood viscosity of broilers during a subsequent exposure to high environmental temperature later in life. 2. The birds, which had been subjected to exposure to 38 degrees C for 24 h at 5-d-old, served as prior exposure group (group A). Both group A and control group B were exposed to 33 degrees C for 3 h when near marketable weight. 3. On exposure to 33 degrees C, although there were no significant differences in the increases in heat production (HP) between the two groups, abdominal temperature (Ta), temperature of external ear tract (Tee), shank skin temperature (Tss), standing-lying frequency and lying time were lower in group A than in group B. Heart rate (HR) and comb surface temperature (Tcs) did not differ but increased in both groups during exposure to 33 degrees C. Respiration rate (RR) was greater in group A. 4. Blood viscosity decreased markedly in both groups after exposure to 33 degrees C; the decrease was greater in group A. 5. These results suggest that early exposure may promote broilers' ability to cope with the subsequent heat load by altering thermoregulatory physiological responses and behavioural patterns, resulting in an alleviation of heat stress.

Aging↗
PubMed2006

The effect of poloxamer viscosity on liquid-filling of solid dispersions in hard gelatin capsules.

Preliminary studies were undertaken on poloxamers to investigate their suitability for liquid-fill formulations for hard gelatin capsules. Poloxamers with viscosity in the range (0.32-2.8 Pa s) and melting point 48-58 degrees C were used as the continuous phase, with alpha-lactose monohydrate of negligible solubility in the molten poloxamers, as a model insoluble disperse phase. Physicochemical characterization by rheology, melt solidification and moisture uptake indicated that poloxamers were suitable excipients for liquid-filling in hard gelatin capsules. 10% w/w lactose/poloxamer dispersions were thixotropic and shear thinning and exhibited good capsule-filling properties, disperse-phase uniformity and satisfactory apparent viscosity at 70 degrees C.

Capsules↗
PubMed1987

Effect of linoleic and oleic acids on blood pressure, blood viscosity, and erythrocyte cation transport.

It has been proposed that dietary linoleic acid lowers blood pressure (BP) by being converted to arachidonic acid and prostanoids of the two-ene series. We tested the effects of linoleic acid on plasma arachidonic acid, blood pressure, blood viscosity, and RBC cation transport. Oleic acid, the major dietary monounsaturated fat and which is not a prostanoid precursor, was used as a control. Seventeen adults consumed 23 g/d of linoleic acid or oleic acid provided by genetic variants of safflower seed, each for 4 weeks in a double-blind crossover design. Linoleic and oleic acids were enriched significantly in the plasma cholesteryl esters, phospholipids and triglycerides during the respective periods of supplementation but there was no increase in arachidonate. Mean BP was 116.1/76.8 during ingestion of oleic and 113.6/74.6 during ingestion of linoleic acid (p = 0.09 systolic, p = 0.12 diastolic). The power of the study was over 75% for detecting a significant (p less than 0.05) effect of 4 mm Hg in systolic BP or diastolic BP. Whole blood and plasma viscosity, and RBC Li/Na countertransport, Na/K cotransport, and Na pump systems (Vmax) were unchanged during the protocol. Therefore, variations in dietary linoleic or oleic acids are unlikely to have major effects on BP or on several membrane-dependent erythrocyte functions related to hypertension.

Adult↗
PubMed2002

Lower plasma noradrenaline and blood viscosity on carvedilol vs atenolol in men with recent myocardial infarction.

The Carvedilol Acute Myocardial Infarction Study (CAMIS) investigates cardiac remodeling in patients (n = 250) randomized to carvedilol vs atenolol and treated for 12 months after acute myocardial infarction. In a sub-study, we compared sympathetic, hemorrheological and vascular effects in small but particularly well-matched groups of participants who had been on reasonably equipotent but unchanged doses of carvedilol (n = 10) or atenolol (n = 10) for at least 4 weeks. Blood pressures (p < 0.05), plasma adrenaline (p = 0.034), plasma vasopressin (p = 0.022) and whole blood viscosity at shear rate 0.5 cp (p = 0.050), 1.1 cp (p = 0.023), 5.8 cp (p = 0.049) and 201 cp (p = 0.060) taken in the laboratory at baseline before 2 h of using the hyperinsulinemic, isoglycemic glucose clamp were lower on carvedilol. Plasma noradrenaline was lower on carvedilol at baseline and throughout the clamp (p < 0.0005). Forearm vascular resistance as measured by plethysmography during the clamp tended to be lower on carvedilol (p = 0.074). No significant difference was found between the groups in glucose disposal rate measured by clamp, maximal forearm blood flow and minimal forearm vascular resistance after 10 min of ischemia, or in ambulatory blood pressure and heart rate taken a few days later. Thus, potential benefits of carvedilol vs atenolol were seen in these post-infarction patients in a laboratory setting. These findings suggest that the inhibitory effects on the sympathetic nervous system and related blood viscosity are stronger with carvedilol than with atenolol.

Adrenergic alpha-Antagonists↗
PubMed2005

Time since menopause does not affect plasma viscosity, plasma thromboxane levels and Doppler findings.

OBJECTIVES: To evaluate whether the use of transdermal hormone replacement therapy (HRT), in women within 5 years of menopause compared with women who were postmenopausal for > 5 years, would significantly influence thromboxane B2 levels, plasma viscosity and Doppler flow parameters at the level of the uterine, internal carotid, ophthalmic and bladder wall arteries. METHODS: Thirty-five normal-weight (body mass index > 19 and < 25 kg/m(2)) postmenopausal women (age 54.6 +/- 3.9 years, mean +/- standard deviation) participated in the study and were divided into two groups (Group I: n = 19, time since menopause < 5 years; and Group II: n = 16, time since menopause > 5 years). Patients were treated with a continuous estradiol transdermal supplementation and 12-day courses of medroxyprogesterone acetate every 2 months. They were studied at baseline and after 6 months (in the estrogen-only phase of the cycle). RESULTS: Results showed a beneficial effect of hormone substitution after 6 months of therapy. Baseline plasma viscosity was similar in both groups, and decreased significantly after therapy in both Group I (-17.5%) and Group II (-15.6%). Plasma levels of thromboxane B(2) were similar at baseline and diminished equally in Group I and Group II (-85.6% and -85.2%, respectively) after treatment. Doppler assessment of the pulsatility index at the level of uterine, internal carotid, ophthalmic and bladder wall arteries showed no differences between groups at baseline and revealed a significant reduction of vascular impedance at the end of the treatment in both groups. CONCLUSIONS: Time since menopause does not affect the potential hemodynamic benefits of HRT in normal-weight women.

Blood Viscosity↗
PubMed2005

Effects of hormone replacement therapy on plasma viscosity and Doppler variations in postmenopausal non-smokers and heavy smokers.

OBJECTIVES: To evaluate the effects of transdermal hormone replacement therapy (HRT) on some biological cardiovascular risk factors, specifically thromboxane B2 level and plasma viscosity. Furthermore, we investigated Doppler flow modifications at the level of the uterine, internal carotid, ophthalmic and bladder wall arteries, and evaluated whether there were significant differences, in the examined parameters, between postmenopausal women who were non-smokers and heavy smokers. METHODS: Forty-three postmenopausal women (age 53.6 +/- 3.3 years, mean +/- standard deviation) participated in the study and were divided into two groups (Group I: n = 21, normal controls; and Group II: n = 22, heavy smokers). Patients were treated with continuous estradiol transdermal supplementation and 12-day courses of medroxyprogesterone acetate every 2 months. They were studied at baseline and after 6 months (in the estrogen-only phase of the cycle). RESULTS: Results showed a beneficial effect of hormone substitution after 6 months of therapy. Plasma viscosity decreased significantly after 6 months of therapy both in non-smokers and heavy smokers (-18% and -14%, respectively). Plasma levels of thromboxane B2, which were similar at baseline, underwent a dramatic reduction in both Group I and Group II (-93% and -88%, respectively). Doppler assessment of pulsatility index at the level of the uterine, internal carotid, ophthalmic and bladder wall arteries showed a significant reduction in vascular impedance at the end of treatment in both groups. However, the treatment was significantly less beneficial, in terms of the analyzed factors, in heavy smokers. CONCLUSIONS: Cigarette smoking represents a cardiovascular risk factor that can only partially be modified by the administration of transdermal HRT.

Administration, Cutaneous↗
PubMed2000

Intestinal digesta viscosity decreases during coccidial infection in broilers.

1. The effect of intestinal digesta viscosity on bird performance in chickens with coccidiosis was compared to those without coccidiosis. 2. Six hundred chicks were divided into five groups: one control group was fed a basal maize/soyabean-based diet and the other groups were fed the basal diet supplemented with 2, 4, 6 or 8 g carboxymethyl cellulose (CMC) per kg of feed. At 14 d of age half the birds were individually inoculated with sporulated oocysts of Eimeria acervulina and Eimeria praecox. 3. Intestinal digesta viscosity increased with increasing inclusion of CMC. This effect was considerably less pronounced in inoculated than in non-inoculated birds. 4. There was a significant negative effect on live weight gain and feed conversion ratio (FCR) with increasing CMC inclusion in non-inoculated birds, but in inoculated birds there was no clear relation between CMC inclusion and performance. Neither intestinal lesion scores, nor numbers of Clostridium pefringens in the caeca, were significantly affected by CMC inclusion. 5. Across all diets inoculation impaired growth rate by 9% and FCR by 8%, but did not affect the amount of C. perfringens in the caeca.

Animals↗
PubMed2002

The effect of erosion and swelling on the dissolution of theophylline from low and high viscosity sodium alginate matrices.

The extent of dissolution of theophylline from sodium alginate matrices has been studied in water and HCl. Surprisingly, it was observed that the dissolution rate was very fast for the low viscosity (LV) material in water and for the high viscosity (HV) in acid, whereas slow release was seen for LV in acid with very slow release for the HV in water. The extent of erosion and swelling of the matrices (with and without drug and with and without stirring) was determined from simple weighing experiments. Based on the extent of erosion and swelling, along with visual observations, it was concluded that the rapid release from LV in water was due to rapid and complete erosion of a weak gel layer. The rapid release of HV in HCl was due to an unexpected lamination of the tablet during swelling, which resulted in exposure of more of the tablet core, and caused increased erosion of the matrix. The slow release seen with the LV in HCl was due to the acid gel being tough and resistant to erosion. The very slow release observed with the HV in water was due to very substantial swelling, with the presence of near zero-order kinetics for this system being due to a balance of swelling and erosion, keeping the diffusion process at a constant rate. Furthermore, an anisotropic swelling behavior is indicated by the preferential expansion in the axial dimension relative to the radial dimension for both LV and HV alginates.

Alginates↗