Search

Fibrinogen is one of the plasmatic proteins which has a major influence on erythrocyte aggregation. The level of fibrinogen at which erythrocyte aggregation does not further increase is not well established. Therefore we aim to determine erythrocyte aggregation with two devices: Myrenne aggregometer (M0 and M1) and Sefam erythro-aggregometer (Ta, AI10 and γD) in relation with fibrinogen levels, in patients with several diseases with fibrinogen levels ranging between 200–1100 mg/dl. With the Myrenne aggregometer a plateau can be observed for fibrinogen levels higher than 400 mg/dl, while with the Sefam erythro-aggregometer, aggregation increases proportionally with fibrinogen levels higher than 400 mg/dl. In addition, for fibrinogen values higher than 400 mg/dl, only statististically significant correlations could be observed between fibrinogen and erythrocyte aggregation parameters with the Sefam erythro-aggregometer: r(Ta)=-0.463; r(AI10)=0.624, r(γD)=0.817, p<0.01, but not with the Myrenne: r(M0)=0.01, r(M1)=0.02, ns. Although the Sefam erythro-aggregometer is a better tool for determining erythrocyte aggregation both at low and high fibrinogen levels, the Myrenne aggregometer may be useful for assessing the erythrocyte aggregation as an indicator of cardiovascular risk, as in such circumstances fibrinogen levels do not usually exceed values higher than 400 mg/dl. [ABSTRACT FROM AUTHOR]

The association of hemorheological alterations with morbid obesity remains a question of debate. In order to ascertain whether morbid obese subjects show certain hemorheological alterations which might be involved in the higher thrombotic risk which characterizes these subjects, we determine glucose, plasma lipids, apolipoproteins, fibrinogen, hematocrit, blood viscosity (Brookfield DVIII viscosimeter), both at native and corrected hematocrit of 45%, plasma viscosity (Fresenius capillary viscosimeter), erythrocyte aggregation (Myrenne aggregometer), both at stasis and at 3 s-1 at 45% hematocrit and erythrocyte indexes in 41 morbid obese subjects (32 female, 9 male aged 33±10 years), and in a well matched non‐obese control group (40 female, 15 male, aged 32±10 years). Mean BMI in the morbid obese group was 44.9±6.7 kg/m2 vs 23.5±4.8 kg/m2 in the control group (p<0.001). Morbid obese subjects when compared with the control group showed a statistically higher glucose level (p<0.001), LDL‐cholesterol (p=0.019), triglycerides (p<0.001), apoB (p=0.019), apoB/A1 (p<0.001), fibrinogen (p<0.001), erythrocyte aggregation (p<0.001), and a statistically lower HDL‐cholesterol (p<0.001). No differences between both groups were observed regarding total‐cholesterol, plasma viscosity, blood viscosity and hematocrit (p=0.109; p=0.690; p=0.510; p=0.950), respectively. After the adjustment for BMI, differences in glucose, LDL‐cholesterol, triglycerides, apoB, apoB/A1, and erythrocyte aggregation did not reach the statistical significance, and differences in fibrinogen were borderline significant (p=0.051), showing a direct effect of BMI on the detected differences between obese and non‐obese. Our results suggest that in morbid obese subjects the increased fibrinogen levels and the altered lipid profile associated with their higher BMI, could in addition to its known mechanisms on haemostasis, favour both venous and arterial thrombotic events by enhancing erythrocyte aggregation. [ABSTRACT FROM AUTHOR]

Behçet's disease (BD) is associated with an increased thrombotic risk, although the prothrombotic mechanisms are not clearly defined. Alterations in blood rheology, specially increased erythrocyte aggregation has been suggested to play an important role in the development of thrombotic events in patients with Behçet's disease. In order to ascertain whether any rheological parameter could be involved in the pathogenesis of thrombotic events in Behçet's disease we have determined plasmatic lipids, fibrinogen, hematocrit, erythrocyte aggregation (Myrenne aggregometer), erythrocyte deformability (Rheodyn SSD), blood viscosity (Brookfield viscosimeter), plasma viscosity (Fresenius capillary viscosimeter) and erythrocyte indexes in Behçet's patients with a non‐active disease when sampling, and a well matched control group. The patient group was made up of 40 Behçet's patients (20 male, 20 female aged 43±12 years) and the control group comprised 70 healthy volunteers (24 male, 46 female aged 45±13 years). Twelve of the 40 Behçet's patients have had a previous documented history of deep vein thrombosis at least six months before entering the study, and the other 28 did not. When patients and controls were compared, patients showed a statistically higher fibrinogen level (p=0.002), plasma viscosity (p=0.003), blood viscosity (p=0.021) and erythrocyte aggregation (p=0.049), the other rheological parameters not being statistically significant. No differences were observed in the rheological parameters when patients with and without a previous thrombotic episode were compared. Our results suggest that rheological alterations do not seem to play any role in the development of thrombotic events in patients with Behçet's disease. [ABSTRACT FROM AUTHOR]

Erythrocyte aggregation index determined with the Myrenne aggregometer gives a wide range of values both in healthy and disease, as observed in the literature, making results less comparable. This is due to the fact that it gives two aggregation indexes depending on the rotation speed of the cone, M[sub 0] (at stasis) and M[sub 1] (at 3 s[sup -1] ) and time elapsed (5 or 10 sec), after the cone is stopped abruptly. We determined in 112 healthy volunteers both indexes at two modes and at two times, along with fibrinogen, plasmatic lipids and hematimetric indexes. The correlations between both the 5 and 10 sec mode, and the different variables were analysed and although a statistically significant correlation was observed in both modes, M[sub 1] at 5 sec gave the highest correlation values: 0.445, 0.485, 0.364, 0.460 for T‐Chol, LDL‐Chol, Apo B/A[sub 1] and fibrinogen, respectively; p<0.01. Therefore, we suggest that all the erythrocyte aggregation measurements should be performed at a hematocrit adjusted to 45%, with autologous plasma, and that an aggregation time of 5 sec (as opposed to 10 sec) should be used in order to avoid confusion and misunderstanding and to allow for comparability of results with the de Myrenne aggregometer between laboratories. [ABSTRACT FROM AUTHOR]