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At least 1,693 records · Page 94Linked to original sources
PubMed1995

[Effect of acute hypoxia on blood viscosity, red blood cell deformability and the left ventricular function in rats].

Experiments were performed on SD rats anaesthetized with urethane and chloralose. The left ventricular function and the parameters of hemorrheology during acute hypoxia were investigated. It was found that during acute hypoxia of 15 min, arterial blood gas value PaO2 decreased markedly. The parameters of the left ventricular function such as +/- dP/dtmax, Peak, HR, Vce40, Vmp, Vmax, L0 (CFU), decreased markedly either. At the same time, hyperviscosity was induced and red blood cell filtration (IF) increased. All these parameters recovered to normal control level after reoxygenation of 15 min. By intravenous injection of propranolol (0.5 mg/kg) and then hypoxia, the left ventricular function were suppressed markedly; and so were to the elevation of blood viscosity and IF. Preinjection of regitine (3 mg/kg) prior hypoxia has the same effect on the blood viscosity and IF. Acute hypoxia induced hyperviscosity and elevation of IF could be suppressed by destruction of carotid sinus region with phenol, but the left ventricular function decreased markedly. These results suggest that acute hypoxia induces hyperviscosity and decreases of red blood cell deformability and left ventricular function, which is probably mediated via the sympathetic nervous system and carotid sinus region.

Animals↗
PubMedDate not supplied

Effects of omega-3 and omega-6 fatty acid-rich oils on the cardiovascular system of thermally injured rabbits: changes in plasma triglycerides, plasma cholesterol, relative blood viscosity, platelet count, and bleeding time.

New Zealand white male rabbits were studied to determine how supplements of soybean oil, soybean + MaxEPA oil, or MaxEPA oil affected their cardiovascular status when they were burned. Plasma triglyceride concentrations increased at 2 hours after burn injury (28 days after supplement administration) and declined by the end of the study in all three experimental groups of rabbits. These same animals showed no noticeable differences in the plasma concentrations of total cholesterol or in the high-density lipoprotein cholesterol subfractions. Plasma low-density/very-low-density lipoprotein cholesterol levels remained unchanged at 2 hours after burn injury/sham treatment but increased by the end of the study in all three experimental groups of rabbits. The mean platelet number was significantly higher in burned/sham treated rabbits given soybean oil supplement as compared with numbers in those given either soybean oil + MaxEPA oil or MaxEPA oil supplement. Plasma relative viscosity was highest in the soybean oil-supplemented rabbits, decreased in animals fed soybean oil + MaxEPA, and lowest in MaxEPA oil-supplemented rabbits. Mean bleeding time was lowest in soybean oil-fed rabbits. The bleeding time was higher in rabbits fed soybean oil+MaxEPA oil and highest in MaxEPA oil-supplemented animals. Platelet number and plasma viscosity were highest in the soybean oil-supplemented rabbits and lowest in the MaxEPA oil-supplemented group. The reverse pattern occurred when bleeding time was established. Overall results obtained suggest that supplementation with oils rich in omega-3 and omega-6 fatty acids may have significant effects on the cardiovascular health of burned male New Zealand white rabbits.

Animals↗
PubMed1995

[Supramolecular organization of erythrocyte glycolysis. II. Viscosity of the cytoplasm].

Based on the molecular composition of the human erythrocyte cytoplasm, the contribution of each of the components (proteins, metabolites, electrolytes) in the overall values of the cytoplasm viscosity has been estimated. The viscosity of the human erythrocyte cytoplasm may be thought of as being determined by the protein component and is no less than 10 mPa.s at 37 degrees C.

Cytoplasm↗
PubMedDate not supplied

Microbial retention characteristics of 0.2-microns-rated nylon membrane filters during filtration of high viscosity fluids at high differential pressure and varied temperatures.

Regulatory guidelines for aseptic manufacture of pharmaceuticals recommend validation of sterilizing filters by bacterial challenge under "worst case" conditions. The microbial retention characteristics of a sterilizing grade, 0.2-microns-rated Nylon 66 membrane filter were evaluated for filtration of high viscosity fluids. Glycerol (80%) was used as the carrier fluid and Pseudomonas diminuta ATCC 19146 as the challenge organism. Testing was carried out at a constant differential pressure of 60 psig over a six-hour test period. Test runs were undertaken at three different temperature conditions (25 +/- 5 degrees C, 42 +/- 1 degree C, and 50 +/- 1 degree C). Under the test conditions, the Nylon 66 membranes provided total retention of P. diminuta. The results demonstrated that a high pressure differential challenge using a high viscosity fluid over a six-hour test period at ambient and elevated temperatures did not alter the retention characteristics of the membrane filter.

Membranes, Artificial↗
PubMed1994

Oral rehydration solutions: increased water and sodium absorption by addition of a viscosity-enhancing agent in a rat model of chronic osmotic diarrhea.

Viscosity-enhancing agents such as carboxymethylcellulose (CMC) can alter absorption of solutes and fluid exchange in the small intestine. We investigated whether the standard World Health Organization oral rehydration solution (WHO-ORS) with the addition of CMC would improve net water and sodium absorption in rats using an in vivo intestinal perfusion technique. Four WHO-ORS, containing either 0, 2.5, 5.0, or 10.0 g/L of CMC, were perfused in rats with a well-tested model of cathartic-induced chronic osmotic diarrhea (D) and in normal controls (C). In D rats, the ORSs with CMC improved sodium absorption at the three concentrations used (p < 0.01). The same effect was shown in C rats. Net water absorption was also enhanced in D rats given ORSs with CMC, although the changes in C animals were less marked. The improvement in sodium and water absorption in both C and D rats positively correlated with the log of relative ORS viscosity. Ultrastructural examination of tissues perfused with 10 g/L of CMC showed an extended brush border glycocalyx. This study indicates that CMC added to WHO-ORS in the perfused rat jejunum improves the effectiveness of the solution by increasing sodium and water absorption.

Animals↗
PubMedDate not supplied

[Use of electron paramagnetic resonance in assessing viscosity of blood lipids in diabetes mellitus in children].

Viscosity of blood serum lipids was studied in children with insulin-dependent diabetes involving nitroxyl containing probes-registered by means of radiospectrometer RE 1307. The following parameters were studied: the ratios between values exhibiting the probe distribution in polar and hydrophobic phases [formula: see text] as well as between content of low polar (I+1) and high polar (I-1) spectral components. The "f' value showed the state of lipid density and the ratio [formula: see text] allowed to estimate the lipid microviscosity. 34 children of 7-15 years old with insulin-dependent diabetes were examined in dynamics of treatment under stationary conditions. Distinct metabolic impairments and aggravation of the lipid peroxidation syndrome were mainly responsible for pronounced increase in lipid viscosity. The procedure of spin probes may contribute to study of diabetes pathogenesis as well as to serve as a diagnostic means in evaluation of the disease complications at early stages.

Adolescent↗
PubMed1994

[The effect of high blood viscosity, caused by secondary polycythemia, on pulmonary circulation and gas exchange in patients with chronic cor pulmonale].

Blood viscosity, pressure of pulmonary artery, pulmonary functions, arterial and mixed venous oxygen content, cardiac output, oxygen transport capacity, oxygen consumption, ejection fraction have been examined at 25 patients with or without hypoxic cor pulmonale with or without secondary polycythaemia. Although secondary polycythaemia occurs in patients with hypoxic cor pulmonale as a compensatory process to increase the oxygen carrying capacity of the blood theoretically but as our findings: 1. The rise of haematocrit causes rise in blood viscosity significantly. 2. Polycythaemia secondary over 0.50 l/l of haematocrit contributes the rise of pressure in pulmonary artery. 3. The systemic oxygen carrying capacity is increasing with the rise of haematocrit up to 0.45 l/l but decreasing over 0.50 l/l. 4. Oxygen consumption is decreasing parallel with the rise of haematocrit. 5. Pulmonary functions, cardiac output do not change by the rise of haematocrit.

Blood Viscosity↗
PubMed1994

Alterations in blood viscosity in horses competing in cross country jumping.

Packed cell volume and plasma total protein (TP), serum albumin (Alb) and globulin (Glb), and plasma ionized calcium (PCa) concentrations, blood viscosity (BV), and plasma viscosity (PV) were measured in 42 horses at rest and after the cross country jumping phase of a horse trial competition. The BV and PV were determined at 6 shear rates (230, 115, 46, 23, 11.5, 5.75 s-1), using a digital rotational cone and plate microviscometer. A paired t-test was used to determine differences between PCV, TP, Alb, Glb and PCa values at rest and after exercise. The PCV, TP, Alb, and Glb values increased (P < 0.05) in horses after exercise. The PCa concentration decreased (P < 0.05) in horses after exercise. Mean BV and PV in the 42 horses at rest and after exercise were fitted to an asymptotic function. Significant (P < 0.05) correlation at all shear rates was seen between BV at rest and PCV, TP, Alb, Glb, and PCa values at rest; and between BV after exercise and PCV, TP, Alb, Glb, and PCa values after exercise. Significant correlation was not seen between PV at rest and TP, Alb, Glb, and PCa at rest, or between PV after exercise and TP, Alb, Glb, and PCa concentrations after exercise at any shear rate.

Animals↗
PubMed1993

Dichotomous response of whole blood viscosity in streptozotocin-diabetic rats.

Abnormalities of blood rheology may play an important role in the underlying mechanism of the development of diabetic complications. Although streptozotocin (STZ)-induced diabetic rats have been used extensively in the investigation of diabetic complications, blood rheological alterations in this model have not previously been assessed. To assess one aspect of blood rheology, we repeated whole blood viscosity (WBV) measurements at 4, 8, 12 and 16 weeks after the STZ injection in rats. Nine of fifteen diabetic rats showed increased WBV after the induction of diabetes. Although these rats had a higher haematocrit, the increase in WBV was maintained after correction to a standard haematocrit. Percentage changes of WBV were significantly greater in these diabetic rats than in control rats at low shear rates (0.1s-1 and 1.0s-1), but not at high shear rates. In contrast, WBV was lowered at all shear rates after the injection of STZ in the remaining six diabetic rats which had lower haematocrit, severe weight loss and high mortality; no rats survived for 16 weeks post-injection. Animals in this group may be implicated in the high mortality among STZ-diabetic rats. Although there was a clear distinction of rheological and clinical pictures between these two groups of STZ-diabetic rats, blood glucose and HbA1 concentrations did not differ significantly. This study demonstrates a dichotomy in blood viscosity response to STZ-induced diabetes.

Animals↗
PubMed1993

[Effect of treatment with indobufen on blood viscosity indices and exercise tolerance in patients with coronary disease].

The study included 20 patients aged from 50 to 65 years with stable coronary disease. In all patients exercise ECG test in Quinton moving track was performed before the treatment, and after one, three, and eight weeks of therapy. Besides that, before the treatment, and after each exercise, platelet aggregation, viscosity of whole blood and plasma, and filtration time of 1 ml of whole blood were evaluated. It was found that already after one week of treatment indobufen caused a decrease of platelet aggregation, reduction of viscosity of whole blood and plasma, and improvement of erythrocyte compliance which favourable effects increased with the continuation of the therapy up to eight weeks. At the same time as a result of eight weeks of treatment a significant improvement was achieved of exercise tolerance in the treated patients.

Adult↗
PubMed1993

Influence of blood viscosity on circulatory parameters determined by first-pass radionuclide angiocardiography in cor pulmonale.

First-pass radionuclide angiocardiography (FPRNA) with 99mTc-albumin was performed in 19 patients with cor pulmonale. Pulmonary circulation time (PCT), mean transit time (MTT), pulmonary stagnation index (PSI) were calculated from the time-activity curves for the estimation of cardiopulmonary circulation. Whole blood viscosity (WBV), plasma viscosity (PV) and hematocrit (HTC) were also measured on the same day. Significant prolongation of all parameters was observed (WBW: 5.04 +/- 1.19 mPas; PV: 1.36 +/- 0.17 mPas; HTC: 47.6 +/- 2.37%; PCT: 7.10 +/- 2.15 s; MTT: 9.33 +/- 4.11 s; PSI: 1.30 +/- 0.37) in patients with cor pulmonale. Significant positive correlations were found between PCT and WBV (r = 0.552; 0.001 < P < 0.01), MTT and WBV (r = 0.34; P < 0.05), furthermore between PCT and HTC (r = 0.356; P < 0.05). The results suggest that hemorheological parameters may influence the results of FPRNA, therefore, they should be determined in addition to the radionuclide study.

Adult↗
PubMed1993

Influence of viscosity and pressure on prosthetic valve regurgitation.

Blood viscosity varies during the course of artificial heart implants and is affected by pathological conditions. To gauge the potential effect of changing viscosity on valve performance, leakage rates were measured across a closed Medtronic-Hall valve with water, water/glycerol and fresh whole bovine blood for aortic and pulmonary pressure ranges. As might be expected from the low Reynolds numbers (< 140), losses across the valve were found to be primarily viscous. For the two Newtonian fluids, leakage was slightly less than linearly proportional to pressure. This is comparable with empirical data for orifice flow, which predicts three fifths power dependence on pressure. For blood, however, the greater than linear dependence on pressure found suggests that the pseudoplasticity (shear-thinning behavior) of blood is important. These data provide evidence that the viscous and non-Newtonian properties of blood must be taken into account in modelling prosthetic valve performance and may affect the test methods and flow regulation strategies for prosthetic blood pumps.

Animals↗
PubMed1995

[Influence of acupuncture on blood pressure, contents of NE, DA and 5-HT of SHR and the interrelation between blood pressure and whole blood viscosity].

Twenty spontaneous hypertensive rats (SHR) with systolic blood pressure (SBP) >or= 20 kPa were chosen and divided randomly into two groups (acupuncture group and control group). The former was acupunctured on bilateral Quchi (L1 11), Zusanli (ST 36). Another 46 immature SHRs which were about 7-week-old with SBP ranged from 16 kPa to 20 kPa were given 10% high molecular weight dextran (HMWD) or normal saline by intervention respectively. The results showed: 1. After three course of acupuncture, SHRs' SBP dropped remarkably from 25.493 +/- 0.73 kPa to 19.547 +/- 0.555 kPa (P < 0.01); 2. After three courses of acupuncture, NE and 5-HT contents in plasma were lowered (P < 0.05, < 0.01) and DA content in plasma was increased (P < 0.05) compared with that in the control group. 3. After three course of acupuncture, NE content in brainstem, hypothalamus, cerebral cortex increased (P < 0.005-0.01) and DA content in brainstem, cerebral cortex increased remarkably (P < 0.005-0.01) compared with that in the control group. 5-HT content in brainstem, hypothalamus, and cerebral cortex increased obviously compared with that in the control group. 4. After 1 or 2 hours of intervention of 10% HMWD to immature SHR, the whole blood viscosity and blood pressure rise remarkably compared with normal saline group. The experiment implies that the mechanism of lowering the blood pressure of SHR by acupuncture lies in that it can adjust NE, DA and 5-HT contents in plasma and central nervous system to adjust the activity of sympathetic, reduce whole blood viscosity etc.

Animals↗
PubMed1996

[Mechanical properties of new low viscosity bone cements--can be improved by vacuum mixing].

With the objective of improving mechanical properties by using a new catalyst, a new bone cement (Sulfix-60) and a new low-viscosity cement with added gentamycin (Allofix-G) were developed. Dynamic weakness was the major disadvantage of the older Sulfix-6 cement, especially in comparison with high-viscosity bone cement. Although static strength could be improved, investigations into improved fatigue strength and the effect of vacuum-mixing on the static and fatigue strength had yet to be carried out. To investigate fatigue stability specimens of the new bone cements were tested using loads under wet conditions until breakage or 20 million cycles. In a first series the cement was hand-mixed in a second series vacuum-mixed alone, and in a third series vacuum-mixed under pressure. Additionally, the ultimate static bending strength was investigated using the standard four-point bending test for the three series of bone cement. Vacuum-mixing brought about an improvement in the dynamic strength of Sulfix-60 from 6.3 MPa, to 9.1 MPa and for Allofix-G from 6.3 MPa to 8.2 MPa; additional pressure brought no further improvement. A 200% increased fatigue stability was detectable in comparison with the older cement. The ultimate bending strength was also significantly improved by vacuum-mixing for both bone cements.

Biomechanical Phenomena↗
PubMed1996

[Flow rates of roentgen contrast media of different viscosity in 4.1 Charrière coronary catheters].

The studies presented here investigated the obtainable flows of different contrast media (Iopromide 370 mg iodine/ml, ZK 119 095 370 mg iodine/ml, ZK 139 129 370 mg iodine/ml, Iopamidol 370 mg iodine/ml, Iopromide 300 mg iodine/ml, ZK 119 095 300 mg iodine/ml, ZK 139 129 300 mg iodine/ml, Iopamidol 300 mg iodine/ml, aqua dest.) in 4.1 Charrière coronary catheters. The measurements of the flow achieved by a standardised power of 100 N show that the highest values are reached with the substance ZK 119 095 (both for 300 mg iodine/ml and 370 mg iodine/ml). On comparison of the catheter types there are no differences in the delivery rate. The x-ray contrast-media, however, are significantly different: the lowest iodine delivery rate is found for iopromide 370 with 384.5 mg iodine/s; the highest rate for the test substance ZK 119 095 with 648.9 mg iodine/s. Although contrast media with low viscosity contain considerably less iodine/ml it is possible to achieve an iodine density in coronary vessels by about 86% higher than that achieved by contrast media with 370 mg iodine/ml. Therefore, the possibility to choose a viscosity-adapted x-ray contrast-medium allows the use of very thin cardiac catheter systems without leading to a worsening of picture quality.

Cardiac Catheterization↗
PubMed1996

[Effect of nutritional conditions on the viscosity and emulsifying capacity of V2-7 biopolymer from Volcaniella eurihalina].

Volcaniella eurihalina is a moderately halophilic bacterium able to produce an exopolysaccharide (EPS) under different culture conditions. Rheological behavior of 1% EPS solutions varied depending on the conditions under which EPS were produced. The maximum viscosity was reached when maltose was used as carbon source. Limitations of phosphorus and sulfur also increased its viscosity power. On the other hand, the addition of residual oil products to the culture medium enhanced the production of this biosurfactant polymer.

Excipients↗