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At least 1,261 records · Page 70Linked to original sources
PubMed2003

Is whole body impedance a predictor of blood viscosity?

Bioelectrical impedancemetry (BIA) has received a widespread interest as a non-invasive approach to body fluid volumes. Since similar techniques have been studied to assess in vitro rheological properties of blood, we investigated the relationships between whole body impedance and blood viscosity parameters in order to determine possible predictive equations. 30 sportsmen (24.6+/-1.01 years; 73.96+/-1.62 kg; 177.73+/-1.33 cm) were enrolled into the study. Body composition was assessed with a multifrequency bioelectrical impedancemeter (Dietosystem Human IM Scan) using low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Viscometric measurements were done at 1000 s(-1) with a falling ball viscometer (MT 90 Medicatest). Hematocrit (Hct) was measured with microcentrifuge. A standardized exercise test was performed on a cycloergometer during 25 minutes. Physical working capacity (W170) was calculated and VO2max was evaluated with Astrand nomograms. Two hemorheological parameters were independently correlated with impedance (Z) measurements: whole blood viscosity (WBV) at 100 kHz (r=0.518; p=0.01) and Hct at 1 kHz (r=-0.485; p=0.01). Plasma viscosity was correlated multilinearly with water/fat free mass and Z at 10 kHz (r=0.441; p=0.02). In addition both WBV and Z at 100 kHz exhibited correlations with aerobic working capacity (VO2max ) with r=-0.482 and r=-0.475 (p</=0.05), respectively. A stepwise regression analysis selects Z at 100 kHz instead of WBV as a predictor of VO2max. These findings confirm our previous reports about relationships between whole body conductance for high frequency and aerobic working capacity and suggest a new approach for non-invasive evaluation of blood rheology with BIA.

Adult↗
PubMedDate not supplied

[Study on the influence of silicone oils of various viscosities on anterior eye structures].

Intraocular silicone oil tamponade plays important role in the treatment of complicated retinal detachments. Aim of present study was an investigation of the effects of different silicone oil fluids on the anterior chamber structures. Standard silicone oils with 100, 990, 3690 mPa.s viscosity and highly purified silicone oil with viscosity 5000 mPa.s were used. Corneal silicone oil impregnation was observed in corneas which were in contact with silicone oil with 100 mPa.s. viscosity. Silicone oil impregnation of uveal structures was observed in all cases after the 4 months follow-up. "Posterior collagenous layer" was observed subendothelial in eyes injected with various silicone oil fluids including highly purified one. Results of our investigation show that use of highly purified silicone oil does not allow to reduce the side effects on ocular structures caused by emulsification or a barrier to the nutrition and exchange of products of metabolism provided by silicone oil bubble.

Animals↗
PubMed1992

The association between erythrocyte internal viscosity, protein non-enzymatic glycosylation and erythrocyte membrane dynamic properties in juvenile diabetes mellitus.

The association of intracellular viscosity of red blood cells and the dynamic properties of erythrocyte membranes in children suffering from diabetes has been investigated by means of ESR spectroscopy. It has been revealed that the slight decrease in the ratio hw/hs of maleimide bound to membrane protein-SH groups of erythrocytes in diabetes may ensue from the enhanced membrane protein immobilization in the plane of lipid bilayer. These alterations were accompanied by a corresponding increase in the relative rotational correlation time (tau c) of iodoacetamide spin label, thus suggesting that the conformational changes in membrane proteins may occur at both the intrinsic and more exposed thiol groups. The membranes of diabetic red blood cells were more glycosylated than those of relevant controls, and the extent of glycosylation was found to correlate significantly with h + 1/h0 and tau c (r = -0.652, P < 0.01 and r = 0.609, P < 0.01). Further, the conformational alterations in erythrocyte membranes from diabetic subjects were accompanied by a significant increase in the mobility parameter (h + 1/h0) of haemoglobin molecules in diabetic erythrocytes. The latter changes correlated well with the enhanced intracellular viscosity of diabetic red blood cells and the level of glycosylated haemoglobin. We conclude that the alterations in membrane lipid-protein interactions together with the increased glycosylation-derived internal viscosity may consequently imply altered viscoelastic properties of erythrocyte membranes and, underlying the impaired deformability of red blood cells in the diabetic state, contribute to the development of late diabetic sequelae.

Adolescent↗
PubMed2004

The influence of the viscosity classification of an acrylic bone cement on its in vitro fatigue performance.

The goal of the present work was to investigate the influence of the viscosity classification of an acrylic bone cement on its in vitro fatigue performance, as determined in fully-reversed tension-compression (+/-15 MPa) fatigue tests. The test matrix comprised six commercially available bone cements [Orthoset1, (OS1), Orthoset(R)3 (OS3), CemexRX (CRX), Cemex XL (CXL), Palacos R (PR) and Osteopal (OP)], two methods of mixing the cement constituents (hand-mixing and vacuum-mixing), two methods of fabricating the test specimens (direct molding and molding followed by machining), two specimen cross-sectional shapes (rectangular or "flat" and circular or "round"), and four test frequencies (1, 2, 5, and 10 Hz). In total, 185 specimens, distributed among 20 sets, were tested. The test results (number of fatigue stress cycles, N_f) were processed using the linearized transformation of the three-parameter Weibull distribution, whence estimates of the Weibull mean, N_[WM], were obtained. Statistical analysis of the ln N_f results (Mann-Whitney test; alpha<0.05) and a comparison of the N_[WM] estimates for specimen sets in which the formulations have essentially the same composition but different viscosity classification (namely, OS1 versus OS3, CRX versus CXL, and PR versus OP) showed that, in the majority of the comparisons carried out, the viscosity classification of a bone cement does not exert a significant influence on its in vitro fatigue performance.

Adult↗
PubMed2004

Plasma volume and blood viscosity during 4 h sitting in a dry environment: effect of prehydration.

BACKGROUND: Deep vein thrombosis and pulmonary thromboembolism are potential problems for travelers, including those who fly. We hypothesized that prehydration with an electrolyte-glucose beverage (EGB) would be better than water for maintaining body fluid balance and preventing increased blood viscosity in immobilized men. METHODS: There were 12 healthy men (24-38 yr) who participated in crossover trials of prehydration using EGB and H2O as well as a control condition (Con) with no prehydration. Fluid intake was set at 6 ml x kg(-1) body weight (mean 418 ml). For each trial, subjects sat for 4 h at a dry-bulb temperature of 23.0-23.5 degrees C and a relative humidity of 18-36%. Plasma volume (PV) and whole blood viscosity (Bvis) were determined every hour; routine laboratory hematological tests, urine volume, and body weight were recorded at 2 h and 4 h. RESULTS: For Con, subjects lost approximately 110 ml h(-1); at 2 h, PV had decreased significantly by 3.4%, and Bvis had increased significantly by 9.3%, with no further change at 4 h. For prehydration, retention of the consumed fluid at 2 h was significantly higher for EGB (57%) than for H2O (38%), while both drinks prevented significant change in PV and Bvis. There were no significant differences between trials in coagulation variables, but Bvis measured at higher shear rates for EGB were significantly attenuated compared with Con. CONCLUSION: EGB and water prevented the increase of blood viscosity that occurred without prehydration. EGB was better than water for maintaining body fluid balance and preventing hypovolemia.

Adult↗
PubMed2004

Extension of equations for predicting viscosity parameters with whole body bioelectrical impedance to a sedentary population.

In a previous paper we determined predictive equations for predicting viscosity parameters with whole body Bioelectrical impedance (BIA) in athletes. We have tried to extend this analysis to a sedentary population. 36 sedentary obese or insulin resistant patients (40.36+/-2.30 years; 85.77+/-3.54 kg; 165.93+/-1.56 cm) were enrolled into this study. Body composition was assessed with a multifrequency bioelectrical impedancemeter Dietosystem Human IM Scan that uses low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Analysis was performed with the software Master 1.0 that gives the choice among 25 published equations for body composition calculation. Viscometric measurements were done at 1000 s(-1) with a falling ball viscosimeter (MT 90 Medicatest). Hematocrit was measured with microcentrifuge. Two hemorheological parameters were independently correlated with impedance (Z) measurements at 50 kHz: whole blood viscosity (WBV) (r=0.541, p=0.01) and hematocrit (Hct) (r=-0.686, p=0.01). New equations slightly different from those we report in the previous paper were found. These findings confirm our previous reports of relationships between whole body electric properties and factors of blood viscosity in athletes and allow the use of BIA to a sedentary population. Obviously, extension of this study will be needed to determine if BIA can be used to generalize predictive equations in both sedentary and trained individuals.

Adult↗
PubMed2004

Biochemical relevance between oxidative/carbonyl stress and elevated viscosity of erythrocyte suspensions.

The effects of various aldehydes such as secondary products of peroxidized lipids and other aldehydes on rheological parameters and their relation with aging process were studied. Malondialdehyde (MDA) in different concentrations can increase significantly viscosity and plastic viscosity of erythrocytes suspended in plasma and HEPES buffer solution. Simultaneously, oxidation induced by Fe2+ can also enhance the viscosity of erythrocyte suspensions. All of these data suggest that MDA as one of the most studied unsaturated carbonyl products of lipid peroxidation leading to protein crosslinking may carry important information in understanding carbonyl stress-related rheological change in acute as well as chronic diseases and aging.

Blood Viscosity↗
PubMed2004

[Hemodynamics, blood gas composition and viscosity in patients with chronic obstructive bronchitis complicated by chronic cor pulmonale].

Hemodynamics, external respiratory function (ERF), blood gas composition and viscosity were studied in 120 patients with chronic obstructive bronchitis at different developmental stage of cor pulmonale. In pulmonary hypertension, there were moderate ERF disorders that became more marked in the compensatory and particularly decompensatory cor pulmonale. As bronchial patency deteriorated, the index of right ventricular performance increased from 0.76+0.081 to 1.23+0.022 in the examinees. Examination of blood gas composition revealed insignificant hypoxemia in pulmonary hypertension and compensatory cor pulmonale, which progressed with decompensation of chronic cor pulmonale (CCP). As bronchial obstruction progressed, there were increases in systolic, diastolic, and mean pressure in the pulmonary artery. The viscosity of blood and plasma and the indices of red blood cell aggregation and deformability were in the normal range in pulmonary hypertension and compensatory CCP. In CCP decompensation, the viscosity of blood and plasma and the index of red blood cell aggregation were increased and the index of red blood cell deformability was decreased.

Blood Gas Analysis↗
PubMed2004

Effects of intralipid infusion on blood viscosity and other haemorheological parameters in neonates and children.

AIM: To study acute haemorheological effects of intralipid in preterm and full-term neonates and children. Circulatory complications of intralipid infusion, such as increases in pulmonary and peripheral flow resistance, have been associated with impaired blood rheology. METHODS: During total parenteral nutrition, 10 preterm infants, 10 full-term neonates and 10 children received an initial dose of intralipid as continuous infusion (0.6 g/kg) over 4 h. Additionally, blood of 10 healthy preterm infants, 10 full-term neonates and 10 adults was incubated with intralipid. Whole blood and plasma viscosity (capillary viscometer), red blood cell (RBC) deformability (rheoscope) and RBC aggregation (Myrenne aggregometer) were measured before and after intralipid infusion and before and after in vitro incubation of blood with intralipid. RESULTS: During intralipid infusion, plasma triglyceride levels increased from 0.13 +/- 0.27 to 2.16 +/- 0.68 g/l in the preterm infants, from 0.14 +/- 0.21 to 1.64 +/- 0.54 g/l in the full-term neonates and from 0.65 +/- 0.31 to 2.26 +/- 0.60 g/l in the children. Whole blood viscosity decreased by about 10% after intralipid in all three groups due to similar decreases in haematocrit. RBC aggregation decreased by about 20% after intralipid infusion. Plasma proteins, plasma viscosity and RBC deformation were not affected by intralipid. In vitro incubation of blood with intralipid resulted in a marked reduction of RBC aggregation that was related to the intralipid concentration. At intralipid concentrations of 4 and 8 mg/ml, no RBC aggregation was noted in preterm and full-term neonates. In adults, RBC aggregation decreased by 50%. CONCLUSIONS: Previously described deleterious effects of intralipid on circulation can not be explained by changes in haemorheological properties.

Blood Viscosity↗
PubMed2005

Whole blood, plasma viscosity, and erythrocyte aggregation as a determining factor of competitiveness in standard bred trotters.

In situations where capillary perfusion in skeletal muscles is limited, changes in blood flow play an important role. Especially alterations in intrinsic erythrocyte factors like red cell aggregation and deformability would increase blood flow resistance. In our study we investigated whether whole blood and plasma viscosity influence exercise tolerance during submaximal training and whether a difference can be realized between trained and untrained standardbred trotters. Venous blood from 42 healthy adult trotters (20 horses at the beginning of their training and 22 well trained horses) was investigated before, immediately afterwards and 30 minutes after submaximal exercise. In both groups whole blood viscosity (WBV; LS30, Contraves, Switzerland) increased significantly (p<0.001) at all shear rates (94 s-1, 2.4 s-1, 0.7 s-1) and decreased after 30 minutes to baseline, as did plasma viscosity (PV; OCR-D, Paar, Austria; p<0.001). No changes in WBV could be seen in hematocrit (40%) standardized samples. Erythrocyte aggregation (EA) indices increased (Myrenne, Germany; p<0.001). Creatin-kinase (p<0.001), lactate (p<0.001), hemoglobine (p<0.001), heart rate and oxygen saturation (p<0.05) increased, while PH (p<0.05), and BE (p<0.001) decreased during the race. In our study, submaximal exercise was related to remarkable changes in hemorheologic variables in the single animal. It was also shown that exercise resulted in a more extensive change of fluidity in well trained horses in comparison to untrained animals, at least for low shear WBV and EA (p<0.05).

Animals↗
PubMedDate not supplied

[Ozone therapy and viscosity of blood and plasma, distance of intermittent claudication and certain biochemical plasma components in patients with occlusive arteriosclerosis of the lower limbs].

Blood and plasma viscosity, total lipids, triglycerides, total cholesterol, free fatty acids, fibrinogen, lipid-gram, and hematocrit were determined in 53 patients with occlusive arteriosclerosis in the lower limbs prior to and after ozone therapy. At the same time the distance of the intermittent claudication was measured. A significant prolongation of the distance walked painlessly, reduction in blood and plasma viscosity as well as the decrease in total cholesterol after therapy with ozone correlated with a decrease of the blood viscosity.

Aged↗
PubMedDate not supplied

[Ozone therapy and viscosity of blood and plasma, distance of intermittent claudication and certain biochemical components in patients with diabetes type II and ischemia of the lower extremities].

Blood and plasma viscosity, total blood lipids, triglycerides, total cholesterol, free fatty acids, fibrinogen, hematocrit, and lipidogram were determined in patients with diabetes mellitus type II and coexisting symptoms of the obliterative arteriosclerosis of the lower limbs. Intermittent claudication distance has been measured parallel. The same tests have been carried out after ozone therapy. A significant improvement in the intermittent claudication and reduction in blood and plasma viscosity have been noted. There was statistically significant correlation between intermittent claudication decrease and blood viscosity reduction following ozone therapy.

Aged↗
PubMed2006

Effects of nattokinase, a pro-fibrinolytic enzyme, on red blood cell aggregation and whole blood viscosity.

The vegetable cheese-like food, natto, is extremely popular in Japan with a history extending back over 1000 years. A fibrinolytic enzyme, termed nattokinase, can be extracted from natto; the enzyme is a subtilisin-like serine protease composed of 275 amino acid residues and has a molecular weight of 27.7 kDa. In vitro and in vivo studies have consistently demonstrated the potent pro-fibrinolytic effect of the enzyme. However, no studies to date have evaluated the effects of nattokinase on various hemorheological parameters and thus we have begun to assess the effects of the enzyme on RBC aggregation and blood viscosity. Blood samples were incubated with nattokinase (final activities of 0, 15.6, 31.3, 62.5 and 125 units/ml) for 30 minutes at 37 degrees C. RBC aggregation was measured using a Myrenne MA-1 aggregometer and blood viscosity assessed over 1-1000 s(-1) with a computer controlled scanning capillary rheometer (Rheolog). Our in vitro results showed a significant, dose-dependent decrease of RBC aggregation and low-shear viscosity, with these beneficial effects evident at concentrations similar to those achieved in previous in vivo animal trials. Our preliminary data thus indicate positive in vitro hemorheological effects of nattokinase, and suggest its potential value as a therapeutic agent and the need for additional studies and clinical trials.

Blood Viscosity↗
PubMed2006

Plasma lipids and blood viscosity in patients with cerebrovascular disease.

It is known that plasma lipids could increase the cerebrovascular risk through alteration of the hemorheological profile. The aim of the study was to evaluate the relationship between blood viscosity parameters and plasma lipids in patients with cerebrovascular disease (CVD). The study included 43 patients with transient ischemic attacks (TIAs), 53 patients with chronic unilateral cerebral infarctions (UCI) and 57 patients with risk factors (RF) for CVD. Whole blood viscosity (WBV) at different shear rates by Couette rotational viscometer Contraves Low Shear 30, plasma viscosity (PV) with capillary viscometer, hematocrit (Hct), fibrinogen (Fib), Cholesterol (Chol), triglycerides (Tg) and high-density lipoproteins (HDL) were examined in all patients and in a control group of 56 presumed healthy subjects. The hemorheological results showed increase of Hct, Fib, WBV and PV in the patients with TIAs and UCI; it was more pronounced in the UCI patients. Significant increase of Hct and WBV in the group with RF for CVD was also found. The elevation of Chol and Tg predominated in the patients with UCI and in the subjects with RF for CVD. These lipid variables correlated significantly with PV in the TIAs and RF for CVD groups. Conclusion is drawn about the significance of plasma Tg for decrease of blood fluidity and for impairment of the cerebral circulation in CVD.

Aged↗
PubMedDate not supplied

[Need to measure the viscosity of solutions of globular proteins when studying their rotational mobility by the spin probe method].

It is shown that for correct determination of correlation time of protein rotation, at least for high concentration, it is necessary to measure the viscosities of investigated solvents, whereas for definition by method of extrapolation values Azz the viscosity of water solution of sucrose may be taken as the viscosity of investigated solutions.

Electron Spin Resonance Spectroscopy↗
PubMed1991

[Correlation between the results of Doppler velocimetry with spectral analysis and the viscosity of cord blood].

The contribution of rheological factors to be impedance of blood flow in the umbilical artery as determined by continuous wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55 p. cent of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placenta arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1991

Microleakage at gingival margins of Class V composite resin restorations rebonded with various low-viscosity resin systems.

The failure of a composite resin restoration to seal at its interface with unetched tooth structures, resulting from polymerization shrinkage, creates an unwanted marginal microleakage. Rebonding with a low-viscosity resin system has been recommended to reseal the marginal gap and to reduce microleakage. Since no particular resin system is commercially available, any low-viscosity resin has been utilized for this purpose. However, findings of this study seem to indicate the importance of selecting the appropriate resin system to optimize the outcome of this rebonding procedure, emphasizing the lowest viscosity and good wettability of the system. With proper selection of the resin system, this rebonding procedure can significantly reduce the microleakage at gingival unetched margins of Class V composite restorations.

Analysis of Variance↗
PubMed1990

[Blood viscosity and blood factors in non-embolic cerebral infarction].

We compared blood viscosity at a high and a low shear rate, hematocrit, as well as levels of fibrinogen, cholesterol, triglyceride and high density lipoprotein-cholesterol between 42 patients with nonembolic cerebral infarction and 39 normal subjects. Blood viscosity, levels of fibrinogen, cholesterol and triglyceride were significantly higher, and high density lipoprotein-cholesterol levels were significantly lower, in patients than in normal persons. Blood viscosity had a positive correlation with hematocrit and fibrinogen, and a negative correlation with high density lipoprotein-cholesterol, but no correlation with cholesterol and triglyceride.

Adult↗