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PubMed1975

[Alterations in blood- and plasma-viscosity of patients with risk-factors (author's transl)].

In a series of tests, performed on patients with the risk-factors smoker and adiposity, a comparison with normal persons revealed a statistically significant hyperviscosity in plasma and whole blood for smokers and overweight patients. When both risk-factors occurred simultaneously, the blood- and plasma-viscosity displayed a distinctly additive increase. Furthermore, female patients taking contraceptives showed a significantly increased plasma- and blood-viscosity when comparing them with a group of normal persons. In a group of pregnant women, hyperviscosity could not be secured statistically.

Adult↗
PubMed2002

Investigation of deformability, viscosity, and aggregation of mPEG-modified erythrocytes.

Several techniques for the development of a universal blood type are under investigation in order to address the vast shortage of blood required during times of crisis and for those receiving chronic transfusions. Recently, the covalent attachment of methoxypolyethylene glycol (mPEG) has received attention as a means to conceal the major and minor blood antigens that can invoke an immune response. We have utilized a simple method to covalently bind mPEG to the surface of red blood cells and monitored the rheological properties including cellular deformability and suspension viscosity as a function of shear rate and aggregation. In order to simulate the deformability of mPEG-modified erythrocytes through small blood vessels, we have studied the flow of cells through a nickel-mesh membrane with a pore size of 5.8 microns. Using a gravity-based nickel-mesh filtration device, dilute solutions of red blood cells were filtered through a membrane. The pressure drop was monitored with time. We have examined the filterability of whole blood, washed erythrocytes, mPEG-altered erythrocytes, and mixtures of altered erythrocytes with whole blood. Results from this apparatus have suggested that there is a significant decrease in deformability using mPEG-modified erythrocytes compared to unaltered red blood cells at identical concentrations. Increasing the ratio of modified cells to unmodified cells resulted in decreased deformability of the suspension. Viscosity measurements of mPEG-modified red cells have shown a shear-thinning property, while results of aggregation measurements indicate reduced aggregation compared to whole blood.

Analysis of Variance↗
PubMed2002

Regular exercise (3x45 min/wk) decreases plasma viscosity in sedentary obese, insulin resistant patients parallel to an improvement in fitness and a shift in substrate oxidation balance.

UNLABELLED: Exercise training decreases blood viscosity in athletes parallel with metabolic improvements mostly characterized by an increase in insulin sensitivity. Patients with low insulin sensitivity exhibit a host of metabolic disorders that may also benefit from regular training. However, the hemorheologic aspects of training in such subjects are not known and we aimed at characterizing them. SUBJECTS: Thirty-two obese insulin resistant subjects were tested before and after 2 months. Twenty-one of them were trained (3x45 min/wk) at a level defined by exercise calorimetry and corresponding to the power at which lipid oxidation reaches a maximum (LIPOX(max )) and eleven served as controls. The two groups were matched for age and body mass index. There was no weight change in controls while the 2 months training period decreased weight by 2.5 kg (p<0.02). This change was totally explained by a loss in fat mass (-2.7 kg, p<0.02) while fat free mass remained unchanged. Blood rheology was unchanged in the control group while training improved plasma viscosity eta(pl) (before: 1.43+/-0.03 mPa.s; after: 1.35+/-0.03 mPa.s, p<0.02). There was no change in either hematocrit, red cell rigidity or red cell aggregation. The balance of substrates oxidation shifted towards a higher use of lipids (point of crossover where subjects oxidize 70% carbohydrates 30% lipids: before 39.3+/-6.9 watts; after 70.8+/-6 watts, p<0.001; point where lipid oxidation is maximal (LIPOX(max )) before: 16.5+/-1.4 watts; after: 21.4+/-1.3 watts, p<0.001) and V(O(2max )) increased by 74% (p<0.01). Consistent with observations in athletes, the metabolic and ergometric improvements induced by training reduces eta(pl) in sedentary, insulin resistant patients, but at those low levels training does not appear to induce "autohemodilution" (as reflected by hematocrit) neither it improves red cell deformability or aggregation. The reliability of eta(pl) as simple and unexpensive marker of efficiency of training in insulin resistant patients should be further evaluated.

Blood Physiological Phenomena↗
PubMed2002

[Effects of nebivolol on microcirculation, platelet aggregation and blood viscosity in patients with essential hypertension].

AIM: To assess effects of a selective beta1-adrenoreceptor blocker acting in part via nitric oxide nebivolol on microcirculation, platelet aggregation and blood viscosity. MATERIAL: Thirty patients with mild-to-moderate essential hypertension (mean age 54,1-/+9,3 years). METHODS: Ambulatory blood pressure monitoring, laser doppler flowmetry, registration of spontaneous and ADP-induced platelet aggregation. Nebivolol (5 mg/day) or its combination with hydrochlorothiazide (12,5 mg/day) were given for 3 months. RESULTS: Treatment with nebivolol caused significant reduction of systolic and diastolic blood pressures. Spontaneous and low dose ADP-induced platelet aggregation significantly decreased during treatment while blood viscosity did not change. In patients with hyperemic and spastic-hyperemic hemodynamic type of microcirculation improvement of microcirculation occurred due to changes of myogenic tone of arterioles and precapillary sphincters and 'damping' properties of resistance arterioles. CONCLUSION: In patients with essential hypertension hypotensive action of nebivolol was associated with antiaggregation effect and improvement of blood flow in microvascular networks.

Adult↗
PubMed2002

[Effects of refined konjac meal on lipid metabolism and blood viscosity of rats fed by high fat forage].

Male SD rats are fed by high fat diet supplemented with refined konjac meal for 6 weeks and the effect of refined konjac meal on the serum lipid peroxides (LPO) and blood viscosity are observed. The results showed that the refined konjac meal can obviously decrease serum cholesterol, triglyceride and serum LPO of rats in comparison with those of rats fed only by high fat forage, and can elevate, at the same time, the high density lipoprotein-cholesterol and high density lipoprotein-cholesterol/triglyceride value. It is also shown that the refined konjac meal can decrease the blood viscosity, but has no effect on forage intake and weight gain of rats.

Animals↗
PubMed1976

Scanning of viscosity in sputum.

A viscometer for measurement of sputum viscosity is described. The apparatus makes possible continuous measurement of sputum samples from 5 to 50 ml in volume. It has been calibrated against capillary and rotation viscometers with excellent correlation. The recordings obtained from sputum impressively display the heterogeneity of this material. They render the possibility of calculating a mean viscosity and of plotting the viscometer are given and the relationship between this instrument and other types of viscometers is discussed.

Bronchitis↗
PubMedDate not supplied

The effect of collagen removal and the use of a low-viscosity resin liner on marginal adaptation of resin composite restorations with margins in dentin.

This study evaluated the influence of collagen removal and the use of a low-viscosity liner on the marginal quality of composite restorations for the total-etch system, Prime & Bond 2.1 (PB) and the self-etching primer system, Clearfil SE Bond (CSEB), in high C-factor cavities with margins in dentin. High C-factor cavities were made on dentin exposed from ground labial surfaces of 100 bovine lower incisors, randomly assigned to 10 treatment groups and restored with composite Z 250, placed in bulk. In Group 1 (PB), control group, PB was applied according to the manufacturer's directions; in Group 2 (PB/PLF), an intermediate layer of low-viscosity composite Protect Liner F (PLF) was applied on the bonding resin surface; in Group 3 (PB/SH) following acid-etching, the surfaces were treated with 10% sodium hypochlorite (SH) for one minute and in Group 4 (PB/SH/PLF), the same procedure was conducted as for Group 3, plus an intermediate layer of PLF was applied as for Group 2. In Group 5 (CSEB), the control group, CSEB was applied according to the manufacturer's directions; in Group 6 (CSEB/PLF), an intermediate layer of PLF was applied; in Group 7 (SH/CSEB), the cavity surface was pre-treated with SH; in Group 8 (SH/CSEB/PLF), SH pre-treatment was conducted as for Group 7, then an intermediate layer of PLF was applied; in Group 9 (CSEB/SH), after CSEB-primer application, the surface was treated with SH, followed by CSEB-adhesive application and in Group 10 (CSEB/SH/PLF), the same was conducted as for Group 9, then an intermediate layer of PLF was applied. The specimens were stored at 37 degrees C for 24 hours, polished, molded and replicas were obtained in epoxy resin. The replicas were gold-sputter coated and observed by SEM (300x) for marginal quality classification. The Kruskal-Wallis non-parametrical multi-comparison Test (p<0.05) was used to obtain statistical analysis of the data. Results demonstrated that both adhesive systems in the control groups presented low marginal quality and a high variability. The use of an intermediate layer of PLF significantly improved the marginal quality with the CSEB system but had no effect with the PB system. Collagen depletion with SH enhanced marginal quality for the PB system and did not influence the CSEB system results.

Acetone↗
PubMedDate not supplied

[Blood viscosity factor in persons with high and low risk of ischemic heart disease].

In the years 1986-1987, the blood viscosity factor, the content of haemoglobin in erythrocytes, the concentration of glucose in blood, the lipids and the blood coagulation system were examined in 180 subjects. They were divided into three groups according to the exposure to risk factors: group performing light manual work (L), group performing hard manual work (C) and group of engine drivers (M). No statistically significant differences in regard to age, employment period, number of cigarettes smoked, as well as arterial systolic and diastolic blood pressure were found between the subjects. Workers from group M had the highest body weight (P > 99%) and increased concentration in blood of triglycerides (P > 99% and Apo B (P > 99%. Subjects from group C had the lowest concentration of cholesterol in blood (P > 99%) and the smallest number of members with hypertensions (3.8%) and overweight (7.5%). Group L included the highest percentage of persons with arterial hypertension (17.5%), the highest, among all examined, blood viscosity factor determined at the coagulation rate of 18.6 s-1, and the lowest prothrombin factor (P > 99%).

Adult↗
PubMed1977

[Viscosity of blood and sensorineural hearing loss (author's transl)].

A statistical survey about the results of treatment of Pentoxifyllin (Trental) in acute and long-standing sensorineural hearing losses is given. The pharmacological effect of viscosity lowering in such patients is demonstrated. The role of erythrocytes and their behaviour in relation to the viscosity of blood its showed by means of literature.

Acute Disease↗
PubMed2004

Influence of suspension viscosity and colloidal particles on permeability of membrane used in membrane bioreactor (MBR).

In this study, pilot scale experiments were carried out to examine membrane fouling occurring in membrane bioreactors (MBR) with or without pre-treatment (coagulation/sedimentation). Especially, the influence of suspension viscosity and dissolved organic matter (DOM) on membrane fouling was investigated. The pre-coagulation/sedimentation process improved the performance of a MBR in terms of membrane permeability by controlling irreversible fouling and formation of thick cake layer. The upper limit of MLSS concentration for an efficient operation in MBR without pre-treatment was suggested to be around 10 g/L based on the measurement of suspension viscosity. In this study, it was difficult to directly relate membrane fouling to DOM detected in the membrane chamber. A series of laboratory scale dead-end filtration experiments was carried out to investigate which fractions in biomass suspension would be the most influential in the deterioration of membrane permeability. Based on the dead-end tests, it was shown that the deterioration of membrane permeability was mainly caused by the colloidal particle fraction in the biomass suspension.

Biomass↗
PubMed2005

[Regional differences in viscosity, elasticity and wall buffering function in systemic arteries: pulse wave analysis of the arterial pressure-diameter relationship].

INTRODUCTION AND OBJECTIVES: Regional variations in the incidence of vascular diseases have been related to regional differences in arterial viscoelasticity. The aim of this study was to characterize the differences in the elastic and viscous modulus and in wall buffering function between central and peripheral systemic arteries, through a time-series analysis of the pressure-diameter relationship. MATERIAL AND METHOD: Pressure and diameter were measured in seven arterial segments (carotid, brachiocephalic trunk, ascending aorta, proximal, middle and distal descending thoracic aorta, and femoral artery) from six sheep. Each segment was mounted on an in vitro mock circulatory system and perfused with Tyrode solution, with a pulse frequency of 1.8 Hz and systemic pressure levels. We used the Kelvin-Voigt model to calculate the pressure-diameter elastic (Epd, mmHg/mm) and viscous (Vpd, mmHg.s/mm) modulus, and to quantify the local wall buffering function (Vpd/Epd). We also calculated the incremental Young's and pressure-strain elastic modulus and pulse wave velocity for each segment. RESULTS: The elastic and viscous modulus increased from proximal to distal segments. The wall buffering function did not differ significantly between arteries. The lower rigidity of the central arteries compared to the distal ones may indicate that the systolic arterial compliance function is concentrated in the central arterial segments. On the other hand, the greater viscosity in the distal segments may indicate that viscous energy loss is concentrated in these segments. CONCLUSIONS: Arterial elasticity and viscosity can be interpreted as properties that are dependent on the region of the vessel, whereas wall buffering function can be considered region-independent.

Animals↗
PubMedDate not supplied

Dental gel viscosity parameters and pharmaceutical availability of non-steroidal anti-inflammatory drugs.

Model prescription for dental anti-inflammatory gels with carboxymethylcellulose sodium salt and non-ionic surfactants have been worked out. Viscosity parameters of 10 variant gel forms were investigated and an attempt on their interpretation was undertaken in relation to pharmaceutical availability of non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen sodium). Viscosity tests demonstrated higher pharmaceutical availability of ibuprofen sodium than of diclofenac sodium particularly from model gels with surfactants of low number of oxyethylene segments in the structure. The above has been confirmed by in vitro studies on the kinetics of therapeutic agent penetration into external compartment.

Algorithms↗
PubMed2005

Blood viscosity changes in experimentally Trypanosoma cruzi-infected rats.

Microcirculatory alterations would explain focal lesions found in Chagas' cardiomyopathy. Trypanosoma cruzi (T. cruzi) infection induces host blood properties modifications and defensive responses capable of producing blood hyperviscosity, an ischemic risk factor able to affect microvascular blood flow. We studied whole blood viscosity (eta(b)) and plasmatic and cellular factors influencing it in rats, 7 and 14 days after experimental infection with T. cruzi. Increased plasma viscosity (eta(p)) was found in infected versus control rats and it was correlated with high blood parasite levels at 7 days and enhanced gamma-globulin fraction concentration at 14 days. The hematocrit, mean corpuscular volume (MCV) and eta(b) were higher in 14 days infected rats vs. 7 days and control animals. Also, electron microscopy observation showed morphological changes in red blood cells (RBC) at 7 and 14 days post-infection, with increased proportion of echinocyte and stomatocyte shapes transformation. In our rat model of Chagas' disease, BPL, increased plasmatic protein concentration, enhanced MCV and RBC shapes transformation would determine blood hyperviscosity, cause of microvascular blood flow abnormalities.

Animals↗
PubMedDate not supplied

A method for the obtaining of increased viscosity eye drops containing amikacin.

A method for the obtaining of increased viscosity (3.6-52.5 cP) eye drops, containing amikacin-aminoglycoside antibiotic and as increasing viscosity agents: polivinyl alkohol, hydroxyethylcellulose or sodium hyaluronate was elaborated. Physicochemical and biological properties of these eye drops were determined.

Amikacin↗
PubMed1992

[The effects of prostaglandin E1 infusion on the viscosity and pH of gastric fluid during general anesthesia].

We studied the protective effect of prostaglandin E1 (PGE1)-induced hypotensive anesthesia on gastric mucosa in 30 elective surgical patients. Three groups, each composed of 10 patients, received PGE1, nitroglycerin or none during general anesthesia. Then we measured the viscosity and pH of gastric fluid continuously in each group. In the PGE1 group the viscosity and pH increased significantly and rapidly (P less than 0.05) as compared with the other groups. This suggests that PGE1 offers prophylactic effect against postoperative acute gastric mucosal lesion (AGML).

Adult↗
PubMed1992

[Plasma viscosity. The effect of plasma proteins].

The authors assessed the plasma viscosity by means of a capillary viscosimeter of their own design and assessed at the same time the concentration of 22 plasma proteins or lipids. Based on the results of these examinations it proved possible to elaborate an original equation which describes the plasma viscosity as a function of the concentration of fibrinogen, alpha-2-globulins (and among them most probably haptoglobin), gammaglobulins, IgA and IgM. The authors discuss in detail the importance of this finding for clinical haemorheology.

Blood Proteins↗
PubMed2006

Viscosity, hemostasis and inflammation in atherosclerotic heart diseases.

BACKGROUND: In atherosclerotic diseases vascular reserve is impaired and pressure gradient is decreased, therefore the reduced blood fluidity can lead to tissue ischemia more rapidly. In previous investigations we demonstrated the deterioration of plasma and whole blood viscosities in patients with acute ischemic coronary syndromes, chronic coronary artery disease, and percutaneous transluminal coronary angioplasty. METHODS: Hemorheological variables (plasma and whole blood viscosities, hematocrit, red blood cell aggregation), hemostaseological parameters (plasma fibrinogen and von Willebrand factor (vWf)), and platelet aggregation were detected in more recent studies in cardio- and cerebrovascular diseases, and diabetes mellitus. Common risk factors (lipid profile, smoking, glucose level, previous diseases) and medication were also recorded. RESULTS: High portion of vascular patients were demonstrated to have poor ex vivo platelet inhibition. Effective antiplatelet treatment detected by aggregometry was related to lower plasma fibrinogen concentration and red blood cell aggregation and was also associated with less recurrent vascular events during the follow-up (p < 0.001). Beside the impaired hemorheological characteristics, the diabetic patients showed elevated vWf activity, which turned to correlate with hemoglobin A1c concentration (p < 0.01) rather than the fasting glucose. SUMMARY: Our studies indicate the active role and interaction of hemorheological and hemostaseological factors in atherosclerotic heart diseases.

Aged↗
PubMed2006

Is plasma viscosity a predictor of overtraining in athletes?

There is a lack of consensus about the biological diagnosis of the overtraining syndrome (OTS). Recently, efforts have been made to standardize its clinical diagnosis (e.g., standardized questionnaires like that of the French consensus group on overtraining of the Société Française de Médecine du Sport-SFMS). We previously reported that the early signs of overtraining (= "overreaching") in elite sportsmen are associated with a hemorheologic pattern (raised hematocrit and plasma viscosity etap) that suggests some degree of reversal of the "autohemodilution" which characterizes fitness, and that the feeling of heavy legs in overtrained athletes is related to higher etap and higher red cell aggregation. We thus investigated on a sample of 48 athletes (age 24 +/- 1 yr), referred for possible diagnosis of overtraining to what extent plasma viscosity is a predictor of OTS. From those 48 athletes 10 had a value of etap in the highest quartile (etap > 1.44 pPa.s) and 8 of them had a diagnosis of overreaching, while in the 38 whose etap was < 1.44 mPa.s there were 20 cases of overreachings. Overt cases of OTS were found in 1 subject of the highest quintile and two in the lowest. Thus the predictive value of etap for early stages (overreaching) or chronicized stages (overtraining syndrome) is as follows: (a) prediction of overreaching: sensitivity 28.57%; specificity 90%; positive predictive value 80%; negative predictive value 47.37%; (b) prediction of chronicized overtraining: sensitivity 2.70%; specificity 18.18%; positive predictive value; 10.00%; negative predictive value 5.26%. These results show that etap is a rather specific, although poorly sensitive predictor of overreaching but has no interest in the diagnosis of the overtraining syndrome itself.

Adult↗