Search

Diabetes mellitus (DM) is a complex, chronic metabolic disorder characterized by impaired regulation of blood glucose levels. Zinc (Zn) is an essential trace elements that plays a role in various physiological processes within the body, including those related to diabetes. The current study was investigated the effect of Zn supplementation on hemorheological parameters in a rat model of DM. After induction of DM, 32 male Wistar albino rats were divided into four groups: control, Zn, DM, and Zn+DM. Whole blood viscosity (WBV) was determined by using digital cone and plate viscometer and plasma viscosity (PV) was determined by a Coulter Harkness capillary viscometer. The rats in the DM Group showed a decrease in both Zn levels and body weight, as well as an increase in glucose levels when compared to the control group. Diabetic rats supplemented with Zn displayed lower blood glucose levels and higher concentrations of Zn compared to the DM Group. The higher PV and lower hematocrit level were measured in DM Group than control group and lower PV, higher hematocrit level were measured in Zn+DM group than DM Group. The WBV was measured at four different shear rates (57.6-115.2 - 172.8-230.4 s -1 ). A statistically significant increase was observed in the DM group compared to the control group. Additionally, a statistically significant decrease was observed in the Zn+DM Group compared to the DM Group at a shear rate of 230.4 s -1 . Erythrocyte rigidity index (T k ) and oxygen delivery index (ODI) were computed under conditions of high shear rate. The rats in the DM group exhibited a reduction in ODI and an elevation in T k in comparison to the control group. Conversely, the diabetic rats supplemented with Zn exhibited decreased T k and increased ODI compared to the DM Group. Zn supplementation seems to have a potential beneficial effect for protecting adverse affect of diabetes on hemorheogical parameters and for maintaining vascular health., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Devis Ozcelik reports financial support was provided by Istanbul University. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Background: Hemorheological parameters have been reported to be altered in cardiovascular disease. Major depression has been associated with increased risk of cardiovascular disease., Objective: Our hypothesis is that hemorheological parameters are disturbed in major depressive disorder., Methods: Major depressive disorder and control groups consisted of 50 subjects. Plasma viscosity, erythrocyte aggregation, erythrocyte deformability, hematological parameters and hematological parameters were examined., Results: Plasma viscosity was statistically significantly higher, erythrocyte elongation index at 0.53 Pa and 0.95 Pa was lower, and MCV, MCH, and MCHC values were also lower in the major depression group (P < 0.05). Elongation index and plasma viscosity were correlated with depressive symptomatology., Conclusions: The increased plasma viscosity and decreased elongation index of erythrocytes indicate an unfavorable hemorheological situation in patients with major depressive disorder compared with healthy controls. The results of this study confirm the findings of studies finding a potential threat to cardiovascular health from major depressive disorder. Increased plasma viscosity and decreased erythrocyte elongation index in depressed patients may be risk factors for cardiovascular events and provide data on the causality of the association between depression and cardiovascular disease.

Background: Selective Serotonin Reuptake Inhibitors (SSRIs), antidepressants commonly used in cardiovascular diseases (CVDs), inhibit the re-uptake of serotonin not only into neurons but also into platelets. Hence they increase the level of serotonin in plasma., Objective: This study was aimed to clarify the effects of two selected SSRIs on plasma serotonin level, hemorheological parameters (hematocrit, erythrocyte deformability, erythrocyte aggregation and plasma viscosity) and selected oxidative stress markers (MDA, GSH, GSSG levels in plasma and erythrocytes)., Methods: Two different SSRIs (Fluvoxamine and Sertraline) were administered to male Sprague-Dawley rats in acute (5 days) or chronic fashion (21 days) at 20 mg/kg/day dose., Results: Aggregation amplitude (AMP) decreased significantly in the chronic sertraline and acute fluvoxamine groups; aggregation half time (t1/2) decreased significantly in the chronic fluvoxamine group. Biochemical parameters indicating oxidative stress significantly increased in the chronic sertraline group., Conclusions: Since SSRI's are commonly used in patients with CVDs, complementary studies are needed to assess the impact of such changes in hemorheological parameters on the risk for CVD, and to reveal the effects of other SSRIs on hemorheological parameters.

Background/aim: Septic shock is an important health problem that vastly alters cardiovascular and hemodynamic status. Increased production of nitric oxide (NO) and endothelin is a counterpart of this endotoxemic state. This study was conducted to test the hypothesis that nonselective NO synthesis blocker (L-NAME), inducible NO synthesis blocker (L-canavanine), or endothelin receptor antagonist (bosentan) will reverse the effects of sepsis on hemorheological parameters., Materials and Methods: Forty-eight male Sprague-Dawley rats were used in 8 groups: saline (control), endotoxin, bosentan, L-NAME, L-canavanine, endotoxin + bosentan, endotoxin + L-NAME, and endotoxin + L-canavanine. Blood was withdrawn at the 4th hour of endotoxemic state. Erythrocyte deformability and erythrocyte aggregation were determined by laser-assisted optical rotational cell analyzer at 37 °C. Plasma viscosity (mPa.s) was measured by a cone-plate viscometer with 0.5 mL of plasma., Results: Endotoxin administration significantly increased aggregation half-time and lowered erythrocyte aggregation amplitude and aggregation index compared to the control, indicating a slower and weaker aggregation pattern. L-NAME and L-canavanine alleviated the effects of endotoxin on erythrocyte aggregation without altering the values in the control animals. However, bosentan did not perform such a restoration., Conclusion: This finding suggests that these restoration effects of the blockers occur via their modulation of nitric oxide synthesis rather than through the endothelin pathway.

Objective: The aim of this study was to analyze the effects of dance therapy on selected hematological and rheological indicators in older women., Methods: The study included 30 women (aged 71.8±7.4), and the control group comprised of 10 women of corresponding age. Women from the experimental group were subjected to a five-month dance therapy program (three 45-minute sessions per week); women from the control group were not involved in any regular physical activity. Blood samples from all the women were examined for hematological, rheological, and biochemical parameters prior to the study and five months thereafter., Results: The dance therapy program was reflected by a significant improvement of erythrocyte count and hematocrit. Furthermore, the dance therapy resulted in a significant increase in the plasma viscosity, while no significant changes in glucose and fibrinogen levels were noted., Conclusions: Dance therapy modulates selected hematological parameters of older women; it leads to increase in erythrocyte count and hematocrit level. Dance therapy is reflected by higher plasma viscosity. Concentrations of fibrinogen and glucose are not affected by the dance therapy in older women, suggesting maintenance of homeostasis. Those findings advocate implementation of dance therapy programs in older women.

Aim: To evaluate hemorheological parameters in patients with fibromyalgia syndrome (FMS) in order to elucidate the etiology of the disease., Methods: Twenty-three adult FMS patients and 20 healthy controls were enrolled in the study. Diabetics, hypertensives and those with any rheumatological disorder or use drugs or smoking cigarette were excluded from the study. Following parameters were analyzed in each subject; erythrocyte deformability, erythrocyte aggregation, plasma viscosity, complete blood count, fasting blood glucose, fibrinogen, albumin, globulin and lipid profile., Results: Erythrocyte elongation indices indicating deformability of erythrocytes were higher in FMS patients (0.564±0.002 at 16.87 mPa and 0.605±0.002 at 30 mPa shear rate) than controls (0.558±0.001 at 16.87 mPa and 0.600±0.003 at 30 mPa shear rate). Erythrocyte aggregation speed was higher in FMS patients (2.1±0.1 s) than controls (2.3±0.2 s). Erythrocyte aggregation index was also higher in FMS patients (65.5±1.3) than controls (62.9±1.5). Erythrocyte aggregation amplitude and plasma viscosity values were similar in both groups (both p > 0.05). Among the complete blood count and biochemical parameters, only albumin levels were lower in the FM patients than controls (p < 0.05)., Conclusion: Our results indicate higher erythrocyte deformability and quicker erythrocyte aggregation in FM patients.

Background: Cigarette smoking deteriorates human health via vascular disorders, cancer and especially respiratory diseases. The aim of this study is to investigate effects of cigarette smoking on hemorheologic parameters, plasma osmolality and lung function in individuals without diagnosis of chronic obstructive pulmonary disease (COPD)., Methods: Patients diagnosed without COPD utilizing respiratory function test were enrolled in the study with three groups, ex-smokers (n = 21), current-smokers (n = 35) and never-smokers (n = 43). Hemorheologic parameters and plasma osmolality were measured in hemorheology laboratory. SPSS 17.0 was used for statistical analysis., Results: Blood and plasma viscosity, fibrinogen and hematocrit levels, mean corpuscular volume and mean corpuscular hemoglobin concentration were significantly elevated in ex-smokers and current-smokers compared to never-smokers. The standardized red blood cell deformability and oxygen delivery index and lung function were statistically lower in current-smokers than never-smokers. Pulmonary blood flow rate was statistically lower in current-smokers and ex-smokers than never-smokers. Plasma osmolality was statistically significantly higher in ex-smokers and current-smokers than never-smokers., Conclusions: Our findings clearly show that cigarette smoking has severe effects on hemorheologic parameters, plasma osmolality and lung function even in individuals without COPD. Blood and plasma viscosity with plasma osmolality might be useful markers to detect early hemorheologic-hemodynamic alterations in cigarette smokers.

Background: Postmenopausal women often develop hemorheological disorders which may affect the systemic blood circulation and present a cardiovascular risk factor., Objective: We evaluated effects of secoisolariciresinol (SECO), a phytoestrogen, on hemorheological parameters and lipid peroxidation in a model of the age-related and/or surgical menopause induced by ovariectomy in rats., Methods: Arterial blood was sampled from sham-operated female rats, ovariectomized rats (OVX), and OVX treated with SECO (OVXSECO) (20 mg/kg/day intragastrically for two weeks). Plasma estrogen concentration and the following hemorheological parameters were measured: RBC aggregation (half-time of aggregation, T1/2; amplitude of aggregation, AMP; aggregation index, AI), RBC deformability (elongation index, EI), whole blood viscosity at the shear rate of 3-300 s-1, plasma viscosity, hematocrit, plasma fibrinogen. Lipid peroxidation was evaluated by measuring conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS) in plasma., Results: Ovariectomy in rats caused a 60% decrease in plasma estrogen level and triggered the development of macro- and microhemorheological abnormalities. Blood viscosity increased by 12-31%, RBC elongation index reduced by 16-28%, and T1/2 and AI increased by 35% and 29% respectively. The increase in blood viscosity correlated predominantly with reduced RBC deformability. Plasma CD and TBARS were elevated by 47% and 104% respectively. SECO therapy for OVX rats reduced blood viscosity by 9-18% and T1/2 by 32%, and increased EI by 4-17%. SECO therapy disrupted the correlation between blood viscosity and RBC deformability. Lipid peroxidation was significantly inhibited, as shown by the reduction in CD and TBARS plasma concentrations by 89% and 70% respectively. SECO did not affect plasma viscosity, estrogen or fibrinogen levels., Conclusions: SECO treatment for OVX rats improves blood macro- and microrheological parameters, possibly through antioxidant protection of RBC.

We previously reported that low intensity endurance training in sedentary patients suffering from the metabolic syndrome improves blood rheology, mostly due to a decrease in plasma viscosity correlated with an increase in cardiorespiratory fitness. We investigated whether these findings can be extended to type-2 diabetics. 22 diabetics (11 women and 10 men, age: 52.00 ± 2.9 yr, BMI: 32.47 ± 1.17 kg/m(2)) were tested before and after 2 months. Eight of them were trained (2 to 3×45 min/wk) at the power intensity where lipid oxidation reaches a maximum (LIPOX max) and thirteen served as controls. Over this period the only significant hemorheological effect of training was a decrease in RBC aggregation "M" (-1.25 ± 0.357 p = 0.01) in the trained group. Subjects who lost weight exhibited a decrease in plasma viscosity (from 1.46 ± 0.013 to 1.38 ± 0.02 p <  0.01). Changes in waist circumference are associated with changes in hematocrit (r =-0.952 p = 0.01); plasma viscosity (r =-0.91; p = 0.03); RBC aggregation ("M" r = 0.940; p = 0.02). Subjects can also be divided into those who improved their aerobic capacity VO(2max) and those whose VO(2max) decreased or remained unchanged. An increase in VO(2max) is associated with a decrease in whole blood viscosity (r =-0.79 p = 0.06) explained by an improvement in RBC rigidity "Tk" (r =-0.963 p = 0.002). This study suggests that in Type 2 diabetic patients: (a) viscosity factors might be less responsive to training than in non diabetic individuals; (b) visceral fat loss is the main determinant of changes in hematocrit, plasma viscosity and RBC aggregation;, ((c) improvements in aerobic capacity improves blood viscosity via an increase in RBC deformability.)

Acute carbon monoxide (CO) poisoning seriously hinders oxygen delivery to tissues. This harmful effect of CO may be aggravated by accompanying changes in the viscosity of blood. We had previously reported increased plasma viscosity in people chronically exposed to CO. This study was planned to test our hypothesis that acute CO poisoning increases blood viscosity. For this purpose four main parameters contributing to blood viscosity - hematocrit, erythrocyte deformability, erythrocyte aggregation and plasma viscosity - were determined in patients with acute CO poisoning and compared with healthy controls. Plasma viscosity and erythrocyte aggregation tendency were lower in the CO group (p <  0.05). Erythrocyte deformability was also lower in CO group (p <  0.05). Our results indicate that acute CO poisoning has diverse effects on hemorheological parameters such as attenuating hematocrit value, plasma viscosity, erythrocyte aggregation tendency and erythrocyte deformability.

Objective: An association between maternal and fetal blood rheology has not yet been investigated nor is it known whether and to what extent fetal blood rheology may be affected by maternal conditions., Methods: At delivery, blood was drawn from the cubital vein of 4985 consecutive mothers and from the umbilical cord during birth for determination of blood rheological parameters (erythrocyte aggregation stasis [E0], low shear [E1], plasma viscosity [Pv]) in addition to hemoglobin (Hb) values and hematocrit (Hct)., Results: Maternal and newborn Pv (r = 0.2; p < 0.0001) correlated statistically significant. There was a remarkable correlation between fetal Pv and gestational age (r = 0.197; p < 0.001). Iron supplementation during pregnancy led to increased fetal Hb, Hct as well as E0 and E1 (p < 0.0001), did not have a significant impact on neonatal Pv (p = 0.068). Smoking mothers gave birth to neonates with significantly higher Pv (p = 0.049), E0 (p = 0.016) and E1 (p = 0.013)., Conclusions: The increase of fetal plasma viscosity at advanced delivery time-points refers to a more gaining protein synthesis by the fetal liver and thus maturity of the fetus. Iron supplementation as well as smoking during pregnancy is associated with a relative hyper-viscosity in the fetus at delivery.

Periodontal diseases are frequently associated with cardiovascular diseases (CVD). On the other hand, occurrence of CVD has also been related with increased blood viscosity. This study was planned to investigate four main hemorheological parameters contributing to blood viscosity - hematocrit, erythrocyte deformability, erythrocyte aggregation and plasma viscosity - and also some biochemical parameters (hs-CRP, fibrinogen, globulin etc.) in patients with periodontal disease. We hypothesized that poor periodontal health would be associated with deterioration of hemorheological properties. According to periodontal health status, subjects were divided into three groups as control (healthy), with plaque induced gingivitis and with chronic periodontitis. All groups included 15 males who had not received periodontal therapy in the last six months before the study, were non-smokers, had no systemic diseases and were not on any medication. Erythrocyte deformability and erythrocyte aggregation were measured with laser-assisted optical rotational cell analyzer (LORCA). Plasma viscosity was measured by a cone-plate viscometer. Data were analyzed with Kruskal-Wallis, Mann-Whitney U Test and Spearman Correlation Coefficient. Plasma viscosity (1.36 ± 0.01 mPa.s in the control group and 1.43 ± 0.02 mPa.s in the chronic periodontitis group, P <  0.01), erythrocyte aggregation tendency (aggregation index, amplitude and t½ were 58.82 ± 1.78% , 20.22 ± 0.40 au, 2.80 ± 0.25 s respectively in the control group, and 67.05 ± 1.47% , 22.19 ± 0.50 au, 1.84 ± 0.15 s in the chronic periodontitis group, P <  0.01), hs-CRP, fibrinogen and globulin levels were significantly higher, whereas HDL level was significantly lower in the chronic periodontitis group (P <  0.05) compared to the control group. All of these conditions may contribute to cardiovascular morbidity and mortality observed in people with periodontal disease, via increasing blood viscosity.

Background and Aim: The relationship between hyperlipidemia and blood and plasma viscosity is not completely clear. While increasing viscosity is often reported with increasing blood lipids, lipid-lowering treatments are often unable to normalize the viscosity values. Aim of this study is to try to clarify the relationship between blood lipids and viscosity., Methods and Results: Apparently healthy subjects were enrolled (n = 410). Smokers, diabetics, obese, and hypertriglyceridemic (above 400 mg/dl) were excluded. Blood (at shear rate 225/s) and plasma viscosity were measured at 37°C. Erythrocyte rigidity (Tk) was calculated according to Dintenfass. Blood lipids and glucose were measured by routine methods. Hyperlipidemic subjects (n = 315) had higher values of plasma viscosity (1.44 ± 0.13 vs. 1.40 ± 0.12 cP, p = 0.007), and blood viscosity (4.51 ± 0.54 vs. 4.35 ± 0.55 cP, p = 0.013), compared to normolipidemic subjects (n = 95). In simple correlation analysis, plasma viscosity was directly associated with LDL cholesterol, and inversely with Tk and HDL cholesterol. In multiple regression analysis the association with LDL and HDL was strengthened, though these two variables as a whole accounted for only 5% (adjusted R2) of the variability of plasma viscosity. Blood viscosity was significantly associated with haematocrit, plasma viscosity, Tk and all considered variables but age in simple correlation analysis, but only with haematocrit, plasma viscosity and Tk in multiple regression analysis., Conclusions: LDL cholesterol and HDL cholesterol influence plasma viscosity, but not blood viscosity. Triglycerides up to values of 400 mg/dl do not seem to have important effects, at least in apparently healthy subjects and at the shear rates used in the present study. The contribution of LDL and HDL cholesterol to plasma viscosity seems however quite limited.

Body composition and nutrition have been reported to be correlated with blood rheology. However, in sedentary and in physically active individuals these relationships seem to be not exactly similar. This study investigated whether exercise training status influences these relationships. 32 athletes (ATH) (age: 25 ± 0.7 yr; body mass index (BMI): 23.75 ± 0.23 kg/m2) were compared to 21 sedentary subjects (SED) (age: 45.19 ± 2.90; BMI = 33.41 ± 1.33) with nutritional assessment (autoquestionnaire), bioelectrical impedancemetry, viscometry at high shear rate (MT90) and Myrenne aggregometer. Subjects differ according to age, weight and adiposity parameters. Their eating behavior is different: ATH eat a higher percentage of protein (p < 0.005), a lower percentage of lipid (p < 0.05), and a higher total amount of carbohydrate (+31% p < 0.02). Their viscosity factors are similar except plasma viscosity which is higher in SED than ATH (1.51 ± 0.03 vs 1.43 ± 0.02 mPa.s, p < 0.05). In both ATH and SED, abdominal obesity (waist-to-hip ratio or WHR) is associated with impairments in blood rheology, but not exactly the same. In ATH, WHR is associated with an increase in hematocrit (r = 0.647; p = 0.009), plasma viscosity (r = 0.723; p = 0.002), and caloric (and CHO) intake moderately increase RBC rigidity (r = 0.5405; p = 0.0251) and aggregability (r = 0.3366 p = 0.0596). In SED the picture is different, adiposity increases hematocrit (r = 0.460; p = 0.048), abdominal fatness increases blood viscosity independent of hematocrit, and CHO intake is associated with lower RBC aggregability (r = -0.493; p = 0.0319).

Classic studies on exercise hemorheology evidenced that blood fluidity is impaired during exercise (short term exercise-induced hyperviscosity) and is improved as a result of regular exercise practice (hemorheologic fitness). Extensive description of these events led to the concepts of "the triphasic effects of exercise", "the paradox of hematocrit", and "the hemorheological paradox of lactate". However, some results obtained in training studies do not fit with this classical picture and cannot be explained by a simplistic paradigm based on the Hagen-Poiseuille law. Taking into account the non-linearity of the effects of viscosity factors on blood flow and oxygen delivery helps to elaborate another picture. For example, moderately high values of hematocrit and erythrocyte rigidity induced by high intensity exercise are likely to trigger a physiological vasodilation improving circulatory adaptation (rather than limiting performance as was previously assumed). This may apply to the acute rise in red cell rigidity observed during strenuous exercise, and also to the paradoxical rise in hematocrit or red cell rigidity observed after some training protocols and that did not fit with the previous (simplistic) paradigms. The "healthy primitive lifestyle" hypothesis 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 based on lean meat and wild herbs (i.e., moderately high in protein, rich in low glycemic index carbohydrates, and poor in saturated fat). We propose here that this model may help to explain on an evolutionary perspective these apparently inconsistent findings. The pivotal explanation is that 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.

Background. Yield shear stress (YSS) well characterizes the thixotropic status of blood, that exemplifies a reversible loss of blood fluidity due to a low shear rate. At the stable haematocrit ratio YSS depends mainly on the fibrinogen level. Aim. Since the role of other biochemical factors in the YSS phenomenon in cerebral ischaemia has not been well known, we have undertaken this problem in a group of stroke patients. Material and Methods. The study was carried out in 36 patients with acute ischaemic stroke and in 12 controls. YSS was estimated by means of microviscometric method. In all subjects the concentration of the following biochemical factors were assayed: albumin, IgG, IgA, IgM, apolipoprotein A, and B, cholesterol, triglycerides, LDL, HDL and fibrinogen. Then the thixotroipic effect of all biochemical factors and their correlations to fibrinogen were estimated by means of mathematical formulas. Results. We found a positive correlation in relation to the following thixotropic effects: for all subjects and separately for patients’ group: Alb(YSS) (p

Background. Yield shear stress (YSS) well characterizes the thixotropic status of blood, that exemplifi es a reversible loss of blood fluidity due to a low shear rate. At the stable haematocrit ratio YSS depends mainly on the fi brinogen level. Aim. Since the role of other biochemical factors in the YSS phenomenon in cerebral ischaemia has not been well known, we have undertaken this problem in a group of stroke patients. Material and Methods. The study was carried out in 36 patients with acute ischaemic stroke and in 12 controls. YSS was estimated by means of microviscometric method. In all subjects the concentration of the following biochemical factors were assayed: albumin, IgG, IgA, IgM, apolipoprotein A, and B, cholesterol, triglycerides, LDL, HDL and fi brinogen. Then the thixotroipic effect of all biochemical factors and their correlations to fi brinogen were estimated by means of mathematical formulas. Results. We found a positive correlation in relation to the following thixotropic effects: for all subjects and separately for patients' group: Alb(YSS) (p < 0.001), ApoA(YSS) (p < 0.001), ApoB(YSS) (p < 0.05), chol(YSS) (p < 0.01), HDL(YSS) (p < 0.05); for patients group without additional diseases: Alb(YSS) (p < 0.05), ApoA(YSS) (p < 0.005), chol(YSS) (p < 0.05), HDL(YSS) (p < 0.02), LDL(YSS) (p < 0.05). There were not any signifi cant correlations in controls. Conclusion. Results of the study indicated that in the interaction between the red cells and fi brinogen some additional factors appearing or activating during ischaemic process may play a role. [ABSTRACT FROM AUTHOR]

The hemorheological profile in multiple myeloma (MM) has been extensively studied. Our investigation regarded the behavior of whole-blood viscosity, plasma viscosity and erythrocyte deformability in MM. We enrolled 24 MM patients; 13 of them had been recently diagnosed and were at the initial stage of therapy, 6 were on consolidation/conservation therapy and 5 had achieved a complete remission. On fasting venous blood we evaluated whole-blood and plasma viscosity at high and low shear rates, haematocrit, the ratios between whole-blood viscosity (at high and low shear rate) and haematocrit×100, the ratio between plasma viscosity at low and high shear rate and the erythrocyte deformability examined by using laser diffractometry and expressed as elongation index. A significant increase in plasma viscosity at low shear rate and a marked decrease in haematocrit were observed in MM patients compared with normal controls. Also the ratio between the high shear rate whole-blood viscosity and haematocrit ×100 and the ratio between the low and high shear rate plasma viscosity were significantly increased in MM patients. A significant decrease in erythrocyte deformability, especially at low shear stresses, was found. We discuss some hypotheses that might explain the behavior of red blood cell deformability in MM, considering that its impairment, in addition to the increase of plasma viscosity, can alter the microcirculatory flow in these patients. [ABSTRACT FROM AUTHOR]

There is scarcity of information about the hemorheological pattern in subjects with Monoclonal Gammopathy of Undetermined Significance (MGUS). This preliminary research is focused on the behaviour of whole-blood and plasma viscosity, haematocrit and erythrocyte deformability in the above clinical condition. We enrolled 21 MGUS subjects (10 women and 11 men; mean age 66.4±11.6 years). In fasting venous blood we examined whole-blood and plasma viscosity at high and lowshear rates, haematocrit, the ratios between whole-blood viscosity (at high and lowshear rate) and haematocrit× 100, the ratio between plasma viscosity at low and high shear rate, and the erythrocyte deformability expressed as elongation index. By comparing normal controls to MGUS subjects a significant increase in whole-blood viscosity at high shear rate and in plasma viscosity at low shear rate were observed. In MGUS subjects the ratios between the high and low shear rate blood viscosity and haematocrit × 100, as well as the ratio between the low and high shear rate plasma viscosity were significantly higher. In MGUS subjects a marked decrease in erythrocyte deformability was also observed. The alteration of the hemorheological profile found in these subjects might be involved in the pathogenesis of thromboembolic events, which occur with a high frequency in MGUS. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Elastic properties of the vessel wall are associated with atherosclerosis and major cardiovascular events. Several physiological and pathological conditions can affect arterial elasticity, but few studies have considered the role of hemorheological parameters. The present study aimed to investigate the relationship between hemorheological parameters and vascular stiffness in the carotid artery district. METHODS: One hundred and two individuals were enrolled. Blood and plasma viscosity were measured by a cone-plate viscometer (Wells-Brookfield DV-III, Stoughton, U.S.A.). Echo-Doppler evaluation of carotid arteries was performed in order to calculate elastic indexes (strain, β-stiffness index and distensibility). The association between hemorheological parameters and carotid elasticity indexes was assessed by simple and multiple regression analyses. RESULTS: In simple correlation analysis, only blood viscosity was directly associated with β-stiffness index (r = 0.20, p = 0.05) and inversely with strain (r= -0.26,p = 0.01) and distensibility (r= - 0.34,p = 0.001). After adjusting for cardiovascular risk factors, blood viscosity, but not plasma viscosity or hematocrit, was independently associated carotid arterial measures, together with age, obesity, hypertension, and dyslipidemia. CONCLUSIONS: The results of the present study demonstrate a strong association between blood viscosity and common carotid elasticity indexes. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Structure and mechanical properties of red blood cells are markedly influenced by pathophysiology of many diseases which in turn potentially impair microcirculatory blood flow. The physiological association between blood rheological parameters and red blood cell indices was investigated in otherwise healthy unselected mid-age women prior to elective gynaecological surgery. METHODS: Red Blood Cell-deformability (RBC 1.2, 3.0; 6.0, 12.0; 30.0, 60.0) during exposure to low (RBC 1.2, 3.0), moderate (RBC 16.0, 12.0) and high shear forces (RBC 30.0, 60.0; Rheodyn; Myrenne), -aggregation (MA1; Myrenne) during low shear (E1; 4-1 S) and in stasis (E0) and plasma viscosity (Pv; KSV 1; Fresenius) were correlated with red blood cell indices (RBC-I: MCV, MCH and MCHC) and subjects' characteristics in 286 healthy women the day before undergoing gynaecologic standard surgery. Women with known pregnancy, malign-, infective-, chronic-disease or extreme BMI (<16; >40 Kg/m²) were excluded from this trial. RESULTS: From June 2014 to December 2014 a total of 286 healthy women (age: 46.5 ± 17.6 y; BMI: 25.5 ± 5.2kg/m²) were eligible for inclusion into this prospective evaluation. Pv (mean±SD: 1.17 ±0.12 mPa s) and RBC aggregation (E0:12.6±6.3; E1:17.9±7.3) were not significantly correlated with RBC-I but with age and BMI. In contrast, RBC-deformability correlated significantly with MCV and MCH but significantly inversely correlated with MCHC. Deformability significantly increased with age but was unaffected by BMI of women. The correlation between RBC-I and RBC deformability was most remarkable during moderate shear force exposure. Neither haemoglobin nor haematocrit were correlated with RBC deformability or RBC-I. CONCLUSIONS: Cell volume and haemoglobin content had a strong impact on deformability in apparently healthy mid age women, whereas low MCHC and large MCV were associated with an increase in deformability while high MCHC and small MCV correlated with increased rigidity of RBC. BMI had no impact on deformability while age was associated with an increase in all determinants of blood viscosity. RBC aggregability was not affected by MCV, MCHC or MCH in mid-age women. [ABSTRACT FROM AUTHOR]

Acute carbon monoxide (CO) poisoning seriously hinders oxygen delivery to tissues. This harmful effect ofCOmay be aggravated by accompanying changes in the viscosity of blood.We had previously reported increased plasma viscosity in people chronically exposed to CO. This study was planned to test our hypothesis that acute CO poisoning increases blood viscosity. For this purpose four main parameters contributing to blood viscosity -hematocrit, erythrocyte deformability, erythrocyte aggregation and plasma viscosity - were determined in patients with acute CO poisoning and compared with healthy controls. Plasma viscosity and erythrocyte aggregation tendency were lower in the CO group (p < 0.05). Erythrocyte deformability was also lower inCOgroup (p < 0.05). Our results indicate that acuteCOpoisoning has diverse effects on hemorheological parameters such as attenuating hematocrit value, plasma viscosity, erythrocyte aggregation tendency and erythrocyte deformability. [ABSTRACT FROM AUTHOR]

We previously reported that low intensity endurance training in sedentary patients suffering from the metabolic syndrome improves blood rheology, mostly due to a decrease in plasma viscosity correlated with an increase in cardiorespiratory fitness. We investigated whether these findings can be extended to type-2 diabetics. 22 diabetics (11 women and 10 men, age: 52.00±2.9 yr, BMI: 32.47±1.17 kg/m²) were tested before and after 2 months. Eight of them were trained (2 to 3×45 min/wk) at the power intensity where lipid oxidation reaches a maximum (LIPOX max) and thirteen served as controls. Over this period the only significant hemorheological effect of training was a decrease in RBC aggregation "M" (-1.25±0.357 p = 0.01) in the trained group. Subjects who lost weight exhibited a decrease in plasma viscosity (from 1.46±0.013 to 1.38±0.02 p < 0.01). Changes in waist circumference are associated with changes in hematocrit (r =-0.952 p = 0.01); plasma viscosity (r =-0.91; p = 0.03); RBC aggregation ("M" r = 0.940; p = 0.02). Subjects can also be divided into those who improved their aerobic capacity VO2max and those whose VO2max decreased or remained unchanged. An increase in VO2max is associated with a decrease in whole blood viscosity (r =-0.79 p = 0.06) explained by an improvement in RBC rigidity "Tk" (r =-0.963 p = 0.002). This study suggests that in Type 2 diabetic patients: (a) viscosity factors might be less responsive to training than in non diabetic individuals; (b) visceral fat loss is the main determinant of changes in hematocrit, plasma viscosity and RBC aggregation; (c) improvements in aerobic capacity improves blood viscosity via an increase in RBC deformability. [ABSTRACT FROM AUTHOR]

Rheohaemapheresis aims to normalize major rheological parameters and is used to treat patients with dry age-related macular degeneration (AMD). While effective, this approach is invasive and requires specially trained personnel. Therefore, the search for novel effective compounds with hemorheological properties that can be taken orally to treat AMD is justified. The use of a robust rodent model of AMD with high blood viscosity is crucial to test the efficacy of potential hemorheological drugs to treat this disease. The objective of this study was to investigate whether OXYS rats, generally used as an animal model of AMD, have hyperviscosity syndrome. The results of this study show that blood viscosity in OXYS rats at low (3-10 s-1) and high (45-300 s-1) shear rates were 14-20% and 7-10% higher than in Wistar rats, while hematocrit and plasma viscosity were not different. Red blood cells (RBCs) in OXYS rats were more prone to aggregation as shown by 39% shorter half-time than in Wistar rats. RBCs were also more rigid in OXYS than in Wistar rats as shown by 21-33% lower index of elongation at the shear stress of 1-7 Pa. These data indicate that OXYS rats have hyperviscosity syndrome as the result of abnormal RBC deformability and aggregation. We propose to use OXYS rats as an animal model for preclinical studies to test compounds with hemorheological properties aimed to treat AMD. [ABSTRACT FROM AUTHOR]

As the underlying mechanisms of the adverse effects of cold spells on cardiac events are not well understood, we explored the effects of cold spells on plasma viscosity, a blood parameter linked to cardiovascular disease. This cross-sectional study involved 3622 participants from the KORA S1 Study (1984–1985), performed in Augsburg, Germany. Exposure data was obtained from the Bavarian State Office for the Environment. Cold spells were defined as two or more consecutive days with daily mean temperatures below the 3rd, 5th, or 10th percentile of the distribution. The effects of cold spells on plasma viscosity were explored by generalized additive models with distributed lag nonlinear models (DLNM). We estimated cumulative effects at lags 0–1, 0–6, 0–13, 0–20, and 0–27 days separately. Cold spells (mean temperature <3rd, <5th or <10th percentile) were significantly associated with an increase in plasma viscosity with a lag of 0–1 days [%change of geometric mean (95% confidence interval): 1.35 (0.06–2.68), 1.35 (0.06–2.68), and 2.49 (0.34–4.69), respectively], and a lag of 0–27 days [18.81 (8.97–29.54), 17.85 (8.29–28.25), and 7.41 (3.35–11.0), respectively]. For the analysis with mean temperature <3rd or 10th percentile, we also observed significant associations at lag 0–20 days [8.34 (0.43–16.88), and 4.96 (1.68, 8.35), respectively]. We found that cold spells had significant immediate and longer lagged effects on plasma viscosity. This finding supports the complex interplay of multiple mechanisms of cold on adverse cardiac events and enriches the knowledge about how cold exposure acts on the human body. [Display omitted] • This is a cross-sectional study to explore the effect of cold spells on plasma viscosity. • We explored the effects of different cold spell definitions on plasma viscosity. • Cold spells were significantly associated with increases in plasma viscosity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Genetic and acquired thrombophilic risk factors may play role on developing venous thromboembolism (VTE). In many cases of pulmonary thromboembolism (PE) it can not be defined any explicit risk factor. In this study we aimed to identify the role of plasma viscosity level on PE. The investigation was planned prospectively and 33 patients with PE and 36 apparently healthy and nonsmoker volunteers as control group were enrolled in the study. The mean plasma viscosity levels were determined in patients with PE and in healthy volunteers as 1.42 ± 0.30 cP and 1.29 ± 0.22 cP respectively. The mean plasma viscosity levels was found to be different between PE and healthy group (p = 0.009). The mean levels of triglyceride, fibrinogen and hematocrit were found different between patients with PE and control group (p < 0.05). Variables including sex, age, smoking habits, levels of hematocrit, fibrinogen, total cholesterol and triglyceride were not associated with plasma viscosity values in patients with PE. Plasma viscosity levels were found higher in patients with PE compared with healthy indivudials. But it is needed to further studies to define the interactions between factors effecting blood rheology and development of thrombosis. [ABSTRACT FROM AUTHOR]

Peripheral arterial disease (PAD), is a common manifestation of systemic atherosclerosis. Advances on the development of such vascular disease have described with a number of novel risk factors. Hyperviscosity, due to alterations of blood cells and plasma components, may play a role on the pathogenesis of the disease. Aim of this study was to evaluate the possible association between hemorheological variables and PAD. The hemorheological variables [whole blood viscosity (WBV), erythrocyte deformability index (DI), plasma viscosity (PLV)] were analyzed in 90 patients and in 180 healthy subjects. WBV and PLV were measured by a Rotational Viscosimeter and DI by a filtrometer. DI and PLV were significantly different in patients as compared to controls. To investigate the possible association between these parameters and the disease we divided the study population into tertiles. At the univariate analysis, we found a significant association between the highest tertiles of PLV, of DI and the disease. A model adjusted for traditional risk factors showed an association between highest tertiles of PLV and PAD. After adjustment for confounding parameters highest tertiles of PLV remained to be significantly associated with the disease. Our data indicate that an alteration of plasma viscosity may modulate the predisposition to PAD. [ABSTRACT FROM AUTHOR]

In a precedent study we observed that overall adiposity evaluated with the body mass index (BMI) was correlated with plasma viscosity and red blood cells (RBC) aggregation while abdominal obesity as assessed with the waist to hip ratio (WHR) was correlated with hematocrit. We investigated this issue in 129 women (age 15-65 years, BMI: 15 to 44 kg/m2, WHR: 0.65 to 1.13, fatness: 12-58%) who were divided into fatness groups: 17 underweight women (BMI <18.5), 75 normal weigh (BMI 18.5-24.9), 11 overweight (BMI 25-29.9), and 26 obese (BMI >30) divided according to WHR into 13 lower body and 13 upper body obese women. Whole blood viscosity significantly increases across obesity classes, and is higher in upper body than in lower body obesity (2.84 ± 0.08 vs 3.29 ± 0.09 mPa.s, p < 0.05). The correlations between whole blood viscosity and BMI (r = 0.383 p < 0.01) and WHR (r = 0.364 p < 0.01) are found again. The former is explained by correlations of BMI with plasma viscosity (r = 0.303 p < 0.01) and red cell rigidity (r = 0.356 p < 0.01) and the latter is only explained by a correlation between WHR and hematocrit (r = 0.524 p < 0.01). BMI is also correlated with RBC aggregation parameters. Actually, when total fatness is evaluated with the percentage of fat (%fat) given by bioimpedance analysis (BIA), the picture is slightly different, since %fat is correlated with whole blood viscosity and RBC aggregation parameters but not with hematocrit, plasma viscosity and red cell rigidity. Fat free mass is also correlated with whole blood viscosity (r = 0.227 p < 0.02) due to a correlation with hematocrit (r = 0.483 p < 0.01) but neither RBC rheology nor plasma viscosity. This study shows that fatness by its own is associated with increased red cell aggregation, that abdominal fat increases blood viscosity due to a rise in hematocrit, and that overall body size as assessed with the BMI is associated with increased plasma viscosity and red cell rigidity. [ABSTRACT FROM AUTHOR]

Background: Hemorheology is the study of low properties of blood and its elements (plasma and formed elements). Blood viscosity is correlated with cerebral blood low and cardiac output, and increased viscosity may increase the risk of thrombosis or thromboembolic events. Objective: To analyze and identify social, behavioral, and hemorheological factors related to smoking among young males in the community in Al-Jouf, Saudi Arabia. Methods: Three hundred and twenty one male subjects (smokers (195), ex smokers (105) and never smokers (21)) with different age groups were enrolled into the study as a randomized sample. Social information was collected from all study groups. Hematocrit (HCT), Whole Blood Viscosity (WBV) and Plasma Viscosity (PV) were measured at room temperature. The relationships of variables with whole blood or plasma viscosity were analyzed by SPSS 17.0 and Origin 6.0 statistical software. Results: Percentage of cigarette smokers is high compared to ex and never smoked persons. The common reason for smoking was the influence of the family which can be parent imitation, family careless, family breakdown or other reasons. The smoking leads to a rise in hematocrit and alters the rheological properties by increasing whole blood viscosity and plasma viscosity levels. Together these changes cumulate in a significant deterioration of the low properties of blood. Conclusions: Alterations of blood rheology in turn can promote atherothrombogenesis in several ways. Smoking increases the risk of vascular diseases through its effects on blood rheology. Further prospective and public health studies would be required to deal with common reasons which influence smoking behavior as well as to deal with the blood rheological changes. [ABSTRACT FROM AUTHOR]

In studies using the intravenous glucose tolerance test with minimal model analysis we reported that low insulin sensitivity (SI) is associated with increased erythrocyte aggregability and plasma viscosity, that appeared to be markers of insulin resistance. Recently, development of modelling has made available a new approach of insulin sensitivity from oral glucose tolerance test data (oral minimal model). We aimed at determining in 111 subjects (51 men, 62 women, age 11-77 yr), insulin sensitivity with this approach together with blood viscosity parameters. With this approach the Myrenne indexes of red cell aggregation were negatively correlated to SI (M; r = -0.456; p = 0.0007; M1; r = -0.397; p = 0.004) while plasma viscosity was not. Correlations with fasting insulin levels (Ib) were weaker (M; r = 0.2711; p = 0.05; M1; r = 0.373; p = 0.007). Accordingly, a stepwise regression analysis selects M as the best correlate of SI and M1 as the best correlate of Ib. With this approach plasma viscosity does not exhibit any clear relationship with SI. This study supports the concept that RBC hyperaggregability is the prominent hemorheologic symptom of insulin resistance. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to examine the effects of age on the acute responses of hemorheological variables and biochemical parameters to a single bout of sub-maximal endurance exercise. Fifteen young (20-30 years), 15 middle-aged (40-50 years) and 12 old (60-70 years) male subjects participated in the study. All subjects performed one single bout of endurance exercise encompassed 30-min cycling at 70-75% of maximal heart rate which was followed by 30-min recovery. Three blood samples were taken before, immediately after exercise and after 30-min recovery. Resting levels of hematocrit, red blood cells count, plasma albumin and fibrinogen concentrations, plasma viscosity and whole blood viscosity were significantly different among the three groups (P < 0.01). Thirty minutes of cycling resulted in significant increases (P < 0.05) in all parameters; while these changes were temporary and returned to pre-exercise level at the end of recovery. Responses of all parameters to exercise and recovery were not significantly different among the three groups (P > 0.05). Fibrinogen changes during exercise and recovery were corrected for exercise- and recovery-induced changes in plasma volume. Data analysis showed effects of exercise and recovery only for raw data (P > 0.05). In addition, raw and corrected fibrinogen data in response to exercise and recovery were not age-related. Our results demonstrate that age does not affect the hemorheological responses to an acute endurance exercise in healthy men. [ABSTRACT FROM AUTHOR]

It is well known that body composition influences blood rheology (higher blood viscosity and RBC aggregation in obese individuals). On the other hand, blood rheology is related to exercise performance (the fitter the athlete the more fluid the blood). The 'paradox of hematocrit' is that most of the time trained athletes have a lower hematocrit while doping aims at increasing it, a situation which seems to challenge physiology and can be explained by the fact that systemic hematocrit may have poor physiological relevance at the microcirculatory level in exercising muscles. However, recent studies dealing with the marked differences among hemorheologic profiles observed in selected sports lead to the concept that the relationships between hemorheology and performance on one hand and body composition and hemorheology on the other hand are more complex and somewhat different according to the variety of exercise and the physiological and/or pathophysiological background. Increased fat mass, but also fat free mass independently of fat mass, are both correlated to impairments of blood fluidity, consistent with the emerging concept that beside increases in fat mass, increases in fat free mass may also be related to metabolic and circulatory disturbances. [ABSTRACT FROM AUTHOR]

Aerobic capacity and performance are associated with increased blood fluidity, while sedentarity leads to decreased exercise performance, and blood hyperviscosity. We aimed at investigating the relationships among body composition, blood rheology and exercise performance in this situation. In 46 sedentary subjects (53.09 ± 1.79 yr old; BMI = 32,35 ± 0,80) attending our unit for an exercise prescription we performed an exercise test to assess aerobic capacity, together with blood lipid profile and blood viscosity (MT 90 viscometer, Myrenne erythroaggregometer). The maximal aerobic capacity VO2max was not correlated to blood rheology but its changes were negatively correlated to those of plasma viscosity (r = -0.679) and pre-training VO2max values were negatively correlated to the BMI (r = -0.45873; p = 0.00430) and fatness (waist circumference r = -0.53476; p = 0.00406). Hemorheological parameters were as expected correlated to blood lipids. The main determinant of the RBC rigidity index Tk was HDL-cholesterol (r = -0.70026; p = 0.00121). The main determinant of M1 is HDL-cholesterol (r = -0.5157; p = 0.0238). RBC aggregability 'M' is negatively correlated to total cholesterol (r = -0.758932; p = 0.000105); HDL-cholesterol (r = -0.62232; p = 0.00444); LDL-cholesterol (r = -0.64486; p = 0.00386). Whole blood viscosity is correlated to triglycerides (r = 0.8569; p = 0.00000140) and negatively correlated to HDL-cholesterol (r = -0.5622; p = 0.0122). Waist circumference (an index of abdominal fatness) is correlated to blood viscosity (r = 0.597; p = 0.00888). The waist to hip ratio is correlated to Hct (r = 0.70075 p = 0.00120) and to blood viscosity (r = 0.8124334; p = 0.0000420). Fat-free mass is correlated to blood viscosity (r = 0.66528; p = 0.00137) and hematocrit (r = 0.64350; p = 0.00220). Hip circumference is negatively correlated to plasma viscosity (r = -0.5007; p = 0.0290). Therefore, this study confirms that hemorheological parameters are influenced by blood lipids, that changes in plasma viscosity are correlated to those of aerobic capacity, and that abdominal fat mass is associated with a worsening of blood rheology and of exercise performance. By contrast, gluteal fat (a factor associated with favorable lipid profile and high insulin sensitivity) is associated with a decrease in plasma viscosity, and fat-free mass is associated with higher blood viscosity and hematocrit, consistent with recent literature linking its size in abdominal obesity with a deleterious metabolic profile. [ABSTRACT FROM AUTHOR]

Regular exercise has been reported to improve blood rheology, but all the studies investigating this issue included a reduced number of subjects, and thus it was logic to perform a meta-analysis of them in order to better characterize this physiological effect. Research was handed on Medline from 1950 to 2010. Studies were selected if they were in English and if they had one or several of these following outcomes: lactate, blood viscosity, RBC rigidity, hematocrit (%), RBC aggregation, fibrinogen and plasma viscosity. They were also kept if they included exercise in their protocol. Results were computed with the fixed effect model and the weighting method was the inverse variance. 11 studies with 175 people were found and included in this meta-analysis. None of these studies had the whole mentioned outcomes. The meta-analysis shows significant effects on on RBC aggregation (-0.59 CI 95% [-0.72; -0.46]), whole blood viscosity (-0.30 [-0.31; -0.28] p < 0.001) and hematocrit (-0.296%; CI 95% [-0.57; -0.01]). Aggregation, hematocrit and viscosity data showed significant heterogeneity, aggregation I2 = 94.95%, hematocrit I2 = 96.46%, viscosity I2 = 99.25%. RBC aggregation (0.53 CI 95% [0.40; 0.66]). Three studies could be included for an intervention versus control analysis which shows significant effects on hematocrit (-1.06% CI 95% [-1.43; -0.68]) but bot on aggregation, with again a significant heterogeneity (hematocrit I2 = 96.46%). These results confirm that regular exercise decreases hematocrit and RBC aggregation, but the heterogeneity which is evidenced should be pointed out. This heterogeneity will require a new computation taking into account a 'random effect' by using a pooling method. In addition, this heterogeneity leads to conclude that more studies are needed to further analyze these effects which are described by a low number of articles, which could explain some of the non-significant results. [ABSTRACT FROM AUTHOR]

Athletes involved in rugby are characterized by a very specific pattern of body composition with an unusually important muscle mass. In a preceding study about rugbymen we evidenced that they exhibit a correlation between red blood cell aggregability and the amount of body fat although it remains within a normal range, and that red cell rigidity was correlated to isometric adductor strength. We had the opportunity of studying the relationships among exercise performance, body composition and hemorheology in 19 female rugby players (age 19-26, mean: 24.47 ± 0.67 yr) practising 4 - 10 hr/wk (mean 7.15 ± 0.3) since 1-12 yr (mean 4,05 ± 0,694). VO2max was not related by its own to blood rheology, either hematocrit (r = -0.0717 p = 0.7706) or plasma viscosity (r = 0.0144; p = 0.9533), but other markers of performance exhivited a correlation with red cell rheology. Relationships between fitness and body composition were evidenced. Isometric handgrip strength was negatively correlated to red blood cell aggregability (Myrenne M, r = -0.57839; p = 0.00948 M1 r = -0.58910; p = 0.00795). Adductor isometric strength was negatively correlated to red blood cell aggregability Myrenne M (r = -0.5033; p = 0.0280) but not to M1 (r = -0.4227; p = 0.0714). Fat mass is a major determinant of the maximal oxygen consumption VO2max either measured by a field test (r = -0.766; p = 0.00013) or exercise test (r = -0.575; p = 0.00994) and was also negatively correlated to both handgrip (r = -0.4918; p = 0.0325) and RBC aggregability M (r = -0.57839; p = 0.00948 and M1 r = -0.5891; p = 0.00795). Independently of fat mass, FFM appears to be a determinant of blood viscosity (r = 0.4622; p = 0.0463) due to its correlation with RBC rigidity (r = 0.4781; p = 0.0384). Thus, trained young women exercising 4-10 hr/wk and thus exhibiting a low percentage of body fat exhibit clear relationships between body composition and hemorheology, but fat mass being low, the parameter correlated with blood rheology is in this case fat-free mass, consistent with recent findings indicating that high fat mass in women is sometimes correlated with parameters of the metabolic syndrome such as insulin resistance or inflammation. In addition, parameters quantifying fatness even within such a physiological range are in this sample negatively related with exercise performance. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess on a large series of soccer players our previous reports on blood rheology and exercise performance. In 99 soccer players (Age 24,17 ± 0,42 yr; weight 75,87 ± 0,89 kg; VO2max 46,86 ± 0,95 mL/min/kg) an exercise test was performed for measuring maximal aerobic capacity and we measured blood viscosity at high shear rate (MT90 viscometer) and RBC aggregation (Myrenne MK1). The French questionnaire developped by the consensus group on overtraining of the French Society of Sports Medicine (SFMS) was also employed. The only hemorheologic statistical determinant of VO2max was hematocrit (Hct r = -0.2439; p = 0.0303). The lactate threshold 2 mmol/l was negatively correlated to M1 (r = -0.43224; p = 0.00847). There was a borderline correlation between the overtraining score at the questionnaire of the SFMS and plasma viscosity (r = 0.3080; p = 0.0532). Therefore, our study confirms that aerobic capacity in this sport is negatively correlated to hematocrit, that RBC aggregation is positively associated with blood lactate accumulation in blood during exercise, and that plasma viscosity is one of the parameters that increase when the athlete is on the edge of the overtraining syndrome. These data are consistent with previous reports about soccer players but caution is needed to extrapolate to other sports. [ABSTRACT FROM AUTHOR]

. [ABSTRACT FROM AUTHOR]

Bioelectrical impedancemetry (BIA) has been used to evaluate hemorheological parameters in vitro, and whole body impedance measurements are also correlated to some hemorheologic factors, due to their close relationship with determinants of electric properties of blood. In previous studies, we have determined a set of predictive equations for hematocrit, whole blood viscosity and plasma viscosity in both sedentary and trained individuals. Recent developments of the interpretation of BIA analysis based on Hanai's mixture conductivity theory allows a more interpretative analysis of the relationships between these electric measurements and body composition. Impedance can be analyzed in terms of resistance and resistivity of the whole body and even more, assuming some simplifications, resistance R and resistivity ρ of total body water (TBW), extracellular water (ECW) and intracellular water (ICW). In this study we thus investigated relationships between blood rheology and these calculations of R and ρ in a sample of 83 subjects (age: 9-64 yr; BMI: 17-44 kg/m2). BIA was performed with a multifrequency bioelectrical impedancemeter using low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Viscometric measurements were done with a falling ball viscometer. Hematocrit was measured with microcentrifuge. We found a new prediction of Quemada's viscometric index of RBC rigidity 'k' which was positively correlated to the resistance of ECW (Re) and even more if it was related to this volume: k = 0.005809 Re/ECW + 1.1784 (r = 0.487; Bland-Altman mean difference: 0.0124; range: -0.00481 to 0.00296). A new finding was that red blood cells (RBC) aggregability, that in the previous studies was not related to whole body impedance, despite its in vitro measurability with such measurements, was correlated to extracellular resistance and resistivity. The Myrenne index 'M' was negatively correlated to the resistivity of the extracellular fluid ρe and is predicted by: M = -27.4755 ρe + 1121.57029 (r = 0.463; Bland-Altman mean difference: 0.00194; range: -0.842 to 0.842). Furthermore, the SEFAM index 'S10' is correlated to the ρe and is predicted by S10 = -59.38579 (ρe-40) + 63.083 (r = 0.761; Bland-Altman mean difference: 0.000722; range: -1.77 to 1.77). Therefore, a more in-depth analysis of electric properties of the body provides a closer approach of RBC rheology, although, of course, most remains to be understood in this intriguing domain. [ABSTRACT FROM AUTHOR]

Although growing number of evidences supports the gender differences of hemorheological variables in human, little is known about this question in experimental animals. Investigating this question and giving laboratory-specific reference values, blood samples from healthy male and female CD rats and beagle dogs were tested for hematological parameters (microcell counter), blood and plasma viscosity (capillary viscometer), erythrocyte deformability (bulk filtrometry and ektacytometry), erythrocyte aggregation (light transmission aggregometer) and fibrinogen concentration (coagulometer). Besides the inter-species alterations we found hematological gender differences too regarding the red blood cell count and hematocrit. In rats the erythrocyte aggregation index was higher in females, while in beagle dogs the males showed significantly higher aggregation index values. In rats the red blood cell deformability showed better values in females. In beagle dogs this was the opposite, the males had better elongation index (EI) values in the function of shear stress (SS). Besides this it was also experienced that the shape of the canine EI – SS curves differed from the rats’ values. Gender differences with inter-species alterations can be observed in laboratory animals (rats and dogs) that have to be taken under consideration during planning experiments and evaluating results. [ABSTRACT FROM AUTHOR]

Bioelectrical impedancemetry has been used to evaluate hemorheological parameters in vitro but whole body impedance measurements are also correlated to some hemorheologic factors, due to their close relationship with determinants of electric properties of blood. In previous studies, we have determined a set of predictive equations for hematocrit, whole blood viscosity and plasma viscosity in both sedentary and trained individuals. In this study we aimed at verifying those findings and investigating for other equations in a sample of 62 subjects whose body composition was assessed with a multifrequency bioelectrical impedancemeter using low intensity at the following frequencies: 1, 5, 10, 50 and 100kHz. Viscometric measurements were done with a falling ball viscometer. Hematocrit was measured with microcentrifuge. We confirm that hematocrit was correlated with impedance measurements at 50 kHz (r=-0.671, p < 0.01), and describe a new predictive equation for RBC rigidity index «k» calculated with the equation of Quemada, (“k” index = 0.0003 Z50 + 1.2815; mean difference: -0.0506; 95% confidence interval of -0.0134 to 0.00324) that is also correlated with impedance measurements at 50 kHz (r = 0.526, p < 0.01). Although the precision of these formulae is not sufficient for allowing true «predictions» of hematocrit and red cell deformability, these findings confirm that factors of viscosity are to some extent reflected by whole body electric properties. [ABSTRACT FROM AUTHOR]

Both blood viscosity and carbon monoxide (CO) has been associated with cardiovascular diseases (CVDs). In order to investigate the effects of chronic low-level CO exposure on the determinants of blood viscosity (hematocrit, plasma viscosity, erythrocyte deformability, and erythrocyte aggregation), 10 men exposed to CO at work for at least 6 months and 10 healthy controls were included in the study. Plasma viscosity was determined by a cone-plate viscometer, erythrocyte deformability and erythrocyte aggregation by laser-assisted optical rotational cell analyzer. Mean plasma viscosity of the group exposed to CO (1.4 ± 0.1 mPa·sn) was significantly higher than that of the controls (1.2 ± 0.06 mPa·sn) (p < .05). Plasma fibrinogen level of the CO group (275 ± 11 mg/dL) was slightly higher than that of the controls (263 ± 14 mg/dL). The rise in plasma viscosity by chronic low-level CO exposure may be the mechanism of CO-induced increase in the risk for CVDs. [ABSTRACT FROM AUTHOR]

The article presents a study that aims to analyze the changes in the plasma viscosity (PV) in patients with liver cirrhosis and to identify the correlation of PV with Child score or Model for End-Stage Liver Disease (MELD) score. It mentions that upper endoscopic and ultrasonographic examinations as well as serum biochemistry fibrinogen and complete blood count were conducted in 92 patients and 28 volunteers. Results show that PV diminished with the increase in Child scores and MELD.

Our aim was to analyze rheological properties of blood and plasma in patients (n=31) with obstructive sleep apnea (OSA) before and after five nights of continuous positive airway pressure (CPAP) therapy as compared with a well-matched control group (n=19). Rheology measurements included blood viscosity, plasma viscosity, erythrocyte elongation and erythrocyte deformability variables specific to the aggregation process. The mean whole blood viscosity of the OSA groups was 18.6% higher than that of the control group (P<0.001), plasma viscosity was 7.2% higher (P<0.001), and the blood count was 6% higher (P<0.001). The corrected viscosity of the OSA group was elevated 6.6% (P<0.05) and the aggregation index was 9.3% higher (P<0.05) relative to the control group. Aggregation half-time of the OSA group was 23.5% shorter than that of the control group (P<0.05). Following CPAP therapy, the rheological variables of the OSA group were significantly reduced: whole blood viscosity was 10.5% lower (P<0.001), plasma viscosity was 4.1% lower (P<0.05), corrected blood viscosity was 4.8% lower (P<0.05), and the aggregation index was 7% lower (P<0.05), while the aggregation half-time was increased 25.4% (P<0.05). There were significant correlations between rheologic and polysomnographic variables for the OSA group. Therefore, five consecutive nights of CPAP therapy improved blood rheological properties in patients with OSA. These findings may help to determine cardiovascular prognoses in these patients. [ABSTRACT FROM AUTHOR]

Abstract: Background: Hemorrhagic shock is associated with severe rheological abnormalities. We hypothesized that in the setting of hemorrhagic shock, resuscitation can alter hemorheological characteristics dramatically, and different fluids cause different effects. The aim of this study was to investigate whether the type of fluid administered has an impact on hemorheological characteristics at the early stage of resuscitation in a rodent model of hemorrhagic shock. Methods: Animals were randomized into five groups: (1) sham hemorrhage (SHAM); (2) shock and sham resuscitation (SHOCK); (3) shock and resuscitation with normal saline 32ml/kg (NS); (4) shock and resuscitation with 7.5% hypertonic saline 4ml/kg (HS); (5) shock and resuscitation with 7.5% hypertonic saline/6% Dextran 70 4ml/kg (HSD). Hemorheological characteristics were measured at 60min after resuscitation. Results: Results showed that NS resuscitation deteriorated red blood cell (RBC) deformability compared with the SHOCK group. The HS group showed improved RBC deformability compared with the NS group, although the differences were not statistically significant. There were significant improvements of RBC deformability at all shear rates in the HSD group compared with the NS group. Whole blood and plasma viscosities decreased significantly in the SHOCK group compared with the SHAM group. At shear rates of 60 and 150s−1, the NS group decreased whole blood viscosity compared with the SHOCK group. The HSD group showed elevated plasma viscosity compared with the SHOCK, NS and HS groups. Conclusion: These results suggested that at the early stage of hemorrhagic shock resuscitation, hypertonic–hyperoncotic resuscitation could improve RBC deformability compared with isotonic crystalloid resuscitation. Dextran 70 could elevate plasma viscosity to nearly baseline level. These effects of hypertonic–hyperoncotic resuscitation could be beneficial to maintain microcirculation. [Copyright &y& Elsevier]

Increased blood viscosity has not been associated with mortality risk in coronary heart disease (CHD). We aimed to investigate the predictive power of hematocrit per blood viscosity (Hct/BV) ratio as a marker of rheological oxygen carrying capacity of the blood to assess mortality risk of CHD. Elective coronary angiography was performed and CHD was proved in 109 patients in 1996 and 1997. In 78 cases (72%) complete follow up information was obtained in February 2006. During the follow up time (mean 8.9 years) 10 patients died due to cardiac cause (group C). Two patients died due to non-cardiac cause and 66 were still alive at the end of the follow up period (group NC, n=68). Mean hematocrit per blood viscosity (Hct/BV) ratio was significantly lower in group C comparing to NC (87±5; 93±9 Pa-1s-1, SD, respectively, p=0.022). Other factors (body mass index, serum cholesterol, fibrinogen, hematocrit, plasma and blood viscosity, cardiac index, left ventricular ejection fraction) provided no statistical differences. Kaplan–Meier survival analysis showed only the impact of fibrinogen and Hct/BV ratio on cardiac mortality (p=0.029 and 0.009, respectively). Receiver operating characteristic curves proved only Hct/BV ratio to be able to differentiate between groups (area under curve: 0.716, p=0.028). Hct/BV ratio showed significant negative correlation with the frequency of hospital admissions (r=-0.377, p=0.03). Low Hct/BV ratio can be regarded as a risk factor of cardiac death in CHD. [ABSTRACT FROM AUTHOR]

Plasma viscosity (PV) and blood viscosity (BV) have been scarcely evaluated in morbid obese patients with no other concomitant cardiovascular risk factors. Contradictory results have been published regarding the influence of insulin resistance on these rheological parameters in obesity. In 67 severe or morbid obese patients without other cardiovascular risk factors (51 women and 11 men, aged 34±11 years), fibrinogen, PV and BV at native (nBV) and corrected 45% hematocrit (cBV) have been determined, and insulin resistance has been calculated with homeostasis model assessment (HOMA) index, in basal conditions and after a three month diet period. The same determinations were performed in 67 healthy volunteers (45 women, 22 men, aged 32±10 years) at baseline and three months later. When cases and controls were compared, obese patients showed higher fibrinogen levels (P<0.001), PV (P=0.050) and cBV (P=0.035), and showed a higher insulin resistance than the control group (P<0.001). Differences in PV were maintained after adjusting for BMI (P=0.001), but disappeared after adjusting for HOMA (P=0.391) fibrinogen (P=0.367) and LDL-chol (P=0.097). Differences between obese patients and the control group for cBV disappeared after adjusting for BMI (P=0.739), HOMA (P=0.744), fibrinogen (P=0.907), LDL-chol (P=0.283) and PV (P=0.112). The achieved weight loss (8.7±3.53%) was not accompanied by any changes in these rheological parameters (P>0.050). Obese patients show increased fibrinogen levels, PV and cBV. These rheological disturbances seem to be associated with insulin resistance and the metabolic syndrome, and do not seem to improve with moderate weight loss. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]