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We studied the effects of novel sterically hindered phenol, 4-methyl-2,6-diisobornyl phenol (dibornol) on the rheological properties of the blood in the model of myocardial ischemia/reperfusion. Dibornol (100 mg/kg intraperitoneally for 3 days before and 5 days after ischemia/reperfusion) decreased blood viscosity by 9-25% in comparison with that in sham-operatedanimals by modulating cellular (erythrocyte deformability and aggregation) and plasma (plasma viscosity) rheological parameters. Normalization of blood rheology under the influence of dibornol increased the availability of oxygen to tissues at high shear rates by 9-18% after acute ischemia/reperfusion in rats.

We recently proposed a unifying hypothesis to reconcile unexpected findings in exercise hemorheology and the classical concepts of “hemorheologic fitness” and the “triphasic effects of exercise”, based on the “healthy primitive lifestyle” paradigm. This paradigm assumes that evolution has selected genetic polymorphisms leading to insulin resistance as an adaptative strategy to cope with continuous low intensity physical activity and a special alimentation moderately high in protein, rich in low glycemic index carbohydrates, and poor in saturated fat. According to this protocol the true physiological picture would be that of an individual whose exercise and nutritional habits are close from this lifestyle, both sedentary subjects and trained athletes representing situations on the edge of this model. Unfortunately samples of people truly adhering to this ancestral lifestyle are hard to obtain. In order to address this picture we tried to compare databases obtained with our preceding published studies. As a model of the “healthy primitive lifestyle” we selected patients trained at low intensity (LI) and given an advice of protein intake around 1.2 g/kg/day. Results show a continuum for plasma viscosity which seems to be lower in athletes than LI-trained and even more sedentaries. When sedentary subjects become obese the most obvious characteristic is an increase in red blood cell (RBC) aggregation correlated to the size of fat stores. It is clear that 3 months of LI are not a perfect model of “healthy primitive lifestyle”, but these data suggest that the most important effect of LI regular exercise is to decrease plasma viscosity and that sedentarity increases RBC aggregation mostly when it results in increased fat storage.

Hyperviscosity syndrome was described in Brattleboro rats. The aim of this study was to investigate the possibility of Brattleboro rats using, as a test system for the study of agents with hemorheological activity. Under conditions of this model of high blood viscosity syndrome in Brattleboro rats, Lychnis chalcedonica L. extract (150 mg/kg) administered intragastrically for 10 days exhibited hemorheological activity by modulating macro- (plasma viscosity, fibrinogen concentration) and microrheological (erythrocyte aggregation and deformability parameters. Hence, Brattleboro rats are an adequate model of hyperviscosity syndrome that can be used for search and testing of substances with hemorheological activity.

As a result of the first session of intravenous laser irradiation of blood, it has been established that changes in the blood cellular elements, according to the data of cytometry, and in the blood and plasma viscosity are analogous to the changes occurring when a blood specimen is being incubated at a temperature of 48°C for 1 h or during its storage for 18 days at 12°C in a refrigerator: average dimensions of leukocytes decrease, thrombocytes decline in number, the deformability of erythrocytes is impaired, and the viscosity of the blood increases. Analogous changes in the cytometric and rheological indices, as well as a small hemolysis of eryth-rocytes, were observed on irradiation of a blood specimen in vitro. The suggestion has been made that the therapeutic effect of intravenous laser irradiation of blood is due to the generation of young cellular elements and their ejection into the blood channel instead of those damaged by the laser radiation.

Aluminum (Al) is a nonessential element and humans are constantly exposed to Al as a result of an increase in industrialization and improving technology practices. Al toxicity can induce several clinical disorders such as neurotoxicity, gastrointestinal toxicity, hepatotoxicity, bone diseases, and anemia. This study aimed at evaluating the possible effects of short term and low dose Al exposure on hemorheological and hematological parameters in rats. Fourteen young, male Wistar albino rats were divided into two groups: 1 mg/200 g body weight of aluminum sulfate (Al2(SO4)3 was injected intraperitoneally to the first group for two weeks, three times a week. The animals of the control group received only physiological saline solution during this period. At the end of the experimental period, anticoagulated blood samples were collected and hematological parameters were determined using an electronic hematology analyzer. Red blood cell (RBC) deformability and aggregation were measured using an ektacytometer (LORCA) and plasma and whole blood viscosities were determined with a Wells-Brookfield cone-plate rotational viscometer. Significant decreases in mean corpuscular volume (MCV), red blood cell (RBC) deformability at low shear stress levels, the aggregation half time (t1/2) and the amplitude (AMP) of aggregation and significant increments in whole blood viscosity (WBV) at native and 40% hematocrit (Hct) of Al-treated rats have been observed. In conclusion, low dose Al2(SO4)3 exposure for a short-time may be responsible for alterations in either rheological properties of blood or hemorheological properties through a remarkable effect on RBC membrane mechanical properties .These alterations may also play an important role in the development of anemia in the Al-treated animals. © 2006 Springer-Verlag.

In this study, we examined the effects of acute psychological stress on hemorheology and hemoconcentration in humans and the associations between stress-induced cardiovascular reactivity and hemorheological changes. Stress-induced changes in hemorheology and hemorheological changes were assessed by measuring plasma viscosity, calculated plasma volume, and total plasma protein. Cardiovascular, hemorheologic, and hematologic variables were assessed in 29 healthy men during a 30-min baseline period and a 5-min speech task. Results indicated that the speech task produced a significant increase in plasma viscosity and total plasma protein and a significant decrease in calculated plasma volume. Significant correlations were observed between changes in blood pressure and heart rate and changes in plasma viscosity, total plasma protein, and calculated plasma volume. These results provide direct evidence that acute psychological stress can produce significant changes in hemorheology and hemoconcentration. The most likely mechanism for the stress-induced hemoconcentration effect is a fluid shift from the vascular to the interstitial spaces through increased blood pressure.

We studied the effect of UV-oxidized fibrinogen with oxidation degrees of 10 and 20% on rheological parameters of the blood. The effect of fibrinogen with 10% oxidation degree was moderate and variable, which attests to its partial compensation with the pool of natural antioxidants. The effect of fibrinogen with 20% oxidation degree was more pronounced. It dramatically decreased deformability of erythrocytes, delayed formation of linear aggregates, accelerated formation of 3D-aggregates, enhanced the total hydrodynamic strength of aggregates, but decreased stability of the largest aggregates. It did not increase plasma viscosity, but enhanced viscosity of the blood at all shear rates. At both degrees of oxidation, suspension stability of the blood decreased, the Caisson viscosity did not change, and the difference between the values of Caisson and asymptotic viscosities markedly increased. On the whole, oxidative fibrinogen produces negative changes in blood rheological parameters, and its effect depends on the degree of oxidation.

Background Fibrinogen, the precursor of fibrin in the coagulation cascade, is also a protein of the acute phase of inflammation, and it is the major determinant of plasma viscosity, all risk factors involved in the genesis of atherosclerotic vascular disease. The aim of this study was to evaluate the association between the fibrinogen plasma levels and blood pressure measured by ambulatory monitoring in 24 hours.

Plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) are considered to reflect the complex of acute phase reactants in inflammations. Both tests were studied with regard to their ability to discriminate between inflammatory and non-inflammatory rheumatic diseases. PV and ESR were measured using the Coulter Viscometer II and the Westergren method, respectively. ESR was found to be a better parameter for rheumatoid arthritis and ankylosing spondylitis than PV, independent of the chosen reference values, age, gender and the hemoglobin level. ESR may still be regarded as an acceptable parameter for monitoring inflammatory rheumatic diseases.

Polycythaemia in newborn infants may lead to a variety of clinical symptoms, probably as a result of impaired blood flow. Besides haematocrit (Hct), plasma viscosity (PV) is an important determinant for blood viscosity, we studied PV in 46 polycythaemic (mean Hct 72%, range 65-80) newborn infants. Fifteen were preterm, 12 small for gestational age (SGA), and 19 appropriate for gestational age (AGA). A control group (mean Elct 58%, range 52-64) consisted of 42 newborn infants. PV was measured using a capillary tube viscometer. Polycythaemic infants had a significantly (p< 0.05) lower PV level [1.060 (range 0.950-1.230)m Pa.s] than control infants [1.120 (range 0.960-1.540)m Pa.s]. Preterm polycythaemic and control infants had significantly lower PV levels than SGA and AGA polycythaemic and control infants. Thirty-three (71.7%) polycythaemic infants had clinical symptoms. The PV level in the group with clinical symptoms was significantly (p< 0.05) higher [1.067 (range 0.985-1.230)m Pa.s] than in the group without clinical symptoms [1.013 (range 0.950-1.183)m Pa.s]. We conclude that 1) PV in polycythaemic newborn infants is lower than in control infants, and 2) clinical symptoms seem to be associated with a combination of polycythaemia and higher PV.

Thirty patients with active rheumatoid arthritis participated in an open study of 6 months’ treatment with either 5-aminosalicylic acid or sulphapyridine, the two moieties of sulphasalazine. Patients were assessed at regular intervals using a number of clinical and biochemical tests designed to detect specific antirheumatic activity.

To determine reference ranges for rheologic parameters (hematocrit, plasma viscosity, erythrocyte aggregation, erythrocyte rigidity) a randomized study involving 653 subjects was carried out. Conditions of sampling, transportation and storing of blood specimens were established prior to the survey. Only 283 subjects met the criteria for enrollment in the study; the others were rejected because of inconspicuous history, normal findings in physical and Doppler-sonographic examination and absence of the risk factors hypertension, diabetes mellitus, overweight, rheumatic diseases, and smoking. The reference range for hematocrit was determined by an impedance-measuring device to equal 39–52% for males and 34–50% for females. The reference range for plasma viscosity, measured by a capillary-tube-plasma viscometer, was found to vary from 1.14 mPas to 1.34 mPas. The reference values for the standardized erythrocyte aggregation index was determined with the mini erythrocyte aggregometer to range from 8 to 21. Erythrocytes measured with the selecting-erythrocyte rigidometer showed a rigidity reference range between 0.83 and 1.19. Analysis of the results revealed that the parameters were independent of age (except in young children) and sex (with the exception of hematocrit).

Blood viscosity (shear rates 100s-1 and 0.94s-1) and several of its major determinants (haematocrit, plasma fibrinogen and plasma viscosity) have been measured in 38 male insulin-treated diabetics, aged 18-50 years, and in 38 non-diabetic control subjects matched for age and smoking habit. Diabetics without fundoscopic retinopathy (n=20) had higher mean blood viscosity than controls at the high shear rate (7.07 cP vs 6.75 cP, p0.05) and the low shear rate (21.2 cP vs 18.7 cP, p0.025). These differences persisted after correction of blood viscosity to a standard haematocrit, and were associated with increased plasma viscosity (1.41 cP vs 1.34 cP, p0.025) and plasma fibrinogen (2.9 g/L vs. 2.5 g/L, p0.025). Diabetics with retinopathy (n = 18) had higher mean blood viscosity than diabetics without retinopathy at the high shear rate (7.53 cP vs 7.07 cP, p0.05) and the low shear rate (24.3 cP vs. 21.2 cP, p0.05), associated with a higher haematocrit (p0.05). Blood viscosity and haematocrit correlated with the duration of diabetes (r0.32, p0.05).

In 21 patients with ischaemic strokes we have monitored plasma viscosity, total plasma concentration, numeric average molecular weight (Mn), and weight average molecular weight (Mw) of Dextran 40 (dextran) and hydroxyethylstarch 200/0.5 (HES) during 10 days of treatment (days 1-4, 2 X 500 ml; days 5-10, 1 X 500 ml). Plasma concentrations of dextran increased during the first 4 days (8.3 mg X ml-1 on the first day to 18.0 mg X ml-1 on the fifth day), reached an apparent steady state of 17.2 mg X ml-1 during the next 6 days, and declined subsequently with a half-time (t1/2) of 4.03 days. After ten days treatment Mn and Mw were shifted towards higher values. Plasma viscosity increased from 1.26 mPas to 1.69 mPas on Day 10 (p less than 0.01) and was linearly correlated with the total plasma concentration of dextran (p less than 0.001; r = 0.88). Total plasma concentrations of HES averaged 11.7 mg X ml-1 on Day 1 and 12.4 mg X ml-1 on Day 5. The molecular weight distribution did not change during the infusions but decreased in comparison with the administered solution. Plasma viscosity fell from 1.40 mPas to 1.30 mPas at Day 10 (p less than 0.05) and was not related to the concentration of HES. The haemodiluting effect, as indicated by a decrease of the haematocrit, was 22% and 16.8% for dextran and HES respectively. These data suggest several advantages of HES compared with dextran in haemodilution therapy of ischaemic stroke.

Correction of erythrocyte sedimentation rates (Westergren tubes) for haematocrit can be carried out using a chart based on equation:Q(cm/sec) =V s (1 —F)2 ⋅ 10−12 in whichV s isStokes sedimentation velocity, andF is the final sedimentation volume of the red cells, given as a volume fraction. The valueF can be replaced, with some loss of accuracy, by microhaematocrit. It is suggested that whenever possible ESR should be also corrected for plasma viscosity. The standard level, for the purpose of comparison, is suggested to be 1 cp for plasma viscosity, and 30% for haematocrit. In the case of very low haematocrits, when the erythrocite sedimentation is nearly completed within the first part of an hour, it is suggested to correct the experimental values for the sedimentation slope. The possible errors are discussed, and it is shown that the advantage of correction of ESR for haematocrit overweights any existing errors, and leads to better organization and standardization of experimental data.

Clinical and haemorheological data were recorded in 40 patients with lacunar strokes confirmed clinically and by computed tomography. The following haemorheological variables were monitored: haematocrit, erythrocyte aggregation, erythrocyte deformability, plasma viscosity, fibrinogen concentration and yield shear stress. Clinically, most patients had case histories and features according to the description of Fisher. All haemorheological parameters with the exception of the haematocrit were pathological when compared with values obtained from a normal control group. In descending order of frequency the pathological changes were in erythrocyte aggregation, plasma viscosity and erythrocyte deformability.

Die Zunahme hochmolekularer Substanzen bei beschleunigter BKS ist viscosimetrisch erfasbar. Auch experimentell last sich bei Zusatz von Fremdkolloiden zu Normalblut eine Viscositatszunahme parallel zur Senkungsbeschleunigung demonstrieren. Die Blockierung einer beschleunigten BKS durch Phenylbutazon oder Inkubation des Plasmas bei 37°C verandert die Viscositatswerte nicht. Moglicherweise kommt es auch klinisch zu gleichartigen Phanomenen und damit zu einer normalen BKS trotz hoher Plasmaviscositat.

For more then two decades, only the Harkness-Coulter viscometer was commercially available in routine clinical plasma viscosity testing. Three new clinical viscometers (manufacturers: Haake, FRG; Luckham, UK; Rheomed, FRG) have been compared to the Harkness viscometer in an extensive quality control program. Sample-to-sample, day-to-day and long term variations have been studied and compared, furthermore error sources, health and environmental hazards, sample volume, price, running costs and user friendliness have been evaluated. Among the four machines tested, the Luckham viscometer appeared to be the most versatile, especially because of its reliability and user friendliness. The smallest sample volume (10 times less than any of the others) is required by the Haake falling ball microviscometer. It provides repeated tests from a sample volume less than 0.1 ml, at comparable price, and with still acceptable accuracy. The exactness of the Rheomed machine is jeopardized by the varying diameter of disposable plastic capillary tubing used in this method.

This study was designed to analyse the flow behavior of red blood cells (RBC) by means of a mathematical model. According to this model, the flow resistance depends on the gap between RBC and vessel wall and on the plasma viscosity. Surface area (SA) and volume (V) of RBC from ten term neonates (N) and ten adults (A) were measured by means of a micropipette system and plasma viscosity (PV) was determined using a capillary viscometer. Neonatal RBC had larger V and SA than adult RBC (107 ± 6 vs 90±4 fl, and 154±7 vs 137±7 μm3). PV was lower in neonates (1.04±0.10 cP) than in adults (1.26±0.13 cP). The critical vessel diameter below that the gap becomes too small to allow sufficient lubrication is higher for neonatal RBC (3.3μm) than that for adult RBC (2.9μm). The driving pressure, hematocrit and viscosity of neonatal RBC is higher than that of adult RBC if both cell types have been suspended in the same medium. However, the driving pressure and viscosity of neonatal and adult RBC is similar for neonatal and adult RBC if the cells have been suspended in the corresponding neonatal and adult plasma. We conclude that the flow properties of neonatal and adult RBC in vessels with diameters of 3.5 to 6 μm are not different since the larger size of neonatal RBC is compensated by a lower PV.