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Vent-Schmidt J.,French Institute of Health and Medical Research | Waltz X.,French Institute of Health and Medical Research | Waltz X.,University of Paris Pantheon Sorbonne | Waltz X.,University of the French West Indies and Guiana | And 12 more authors.

We compared the blood thixotropic/shear-thinning properties and the red blood cells' (RBC) rheological properties between a group of patients with sickle cell anaemia (SS) and healthy individuals (AA). Blood thixotropy was determined by measuring blood viscosity with a capillary viscometer using a "loop" protocol: the shear rate started at 1 s-1 and increased progressively to 922 s-1 and then redecreased to the initial shear rate. Measurements were performed at native haematocrit for the two groups and at 25% and 40% haematocrit for the AA and SS individuals, respectively. RBC deformability was determined by ektacytometry and RBC aggregation properties by laser backscatter versus time. AA at native haematocrit had higher blood thixotropic index than SS at native haematocrit and AA at 25% haematocrit. At 40% haematocrit, SS had higher blood thixotropic index than AA. While RBC deformability and aggregation were lower in SS than in AA, the strength of RBC aggregates was higher in the former population. Our results showed that 1) anaemia is the main modulator of blood thixtropy and 2) the low RBC deformability and high RBC aggregates strength cause higher blood thixotropy in SS patients than in AA individuals at 40% haematocrit, which could impact blood flow in certain vascular compartments. © 2014 Vent-Schmidt et al. Source

Lemaire C.,Service Route | Lamarre Y.,French Institute of Health and Medical Research | Lemonne N.,Unite Transversale de la Drepanocytose | Waltz X.,French Institute of Health and Medical Research | And 8 more authors.
Clinical Hemorheology and Microcirculation

Little is known about the impact of blood rheology on the occurrence of retinopathy in sickle cell disease (SCD). Fifty-nine adult SCD patients in steady-state condition participated to the study: 32 with homozygous SCD (sickle cell anemia; SCA) and 27 with sickle cell hemoglobin-C disease (SCC). The patients underwent retinal examination and were categorized according to the classification of Goldberg: 1) no retinopathy (group 1), 2) non-proliferative or proliferative stage I-II retinopathy (group 2) and 3) proliferative stage III-IV-V retinopathy (group 3). Hematological and hemorheological (whole blood viscosity, RBC deformability and aggregation properties) measurements were performed for each patient. In the whole SCD group (SCA + SCC patients) and in SCC patients, the group 3 had higher platelets count than group 2 but the difference between group 3 and group 1 did not reach statistical significance. No difference was observed for the other parameters between the three groups. SCC patients from the group 3 exhibited higher whole blood viscosity than SCC patients from the group 1. No significant difference was observed between the three groups in SCA patients. This study revealed that severe sickle proliferative retinopathy is associated with blood hyperviscosity in SCC patients but not in SCA patients. © 2013 - IOS Press and the authors. Source

Nebor D.,University of the French West Indies and Guiana | Durpes M.C.,University of the French West Indies and Guiana | Mougenel D.,Unite Transversale de la Drepanocytose | Mukisi-Mukaza M.,University of the French West Indies and Guiana | And 3 more authors.
Clinical Immunology

Since inflammation plays a prominent role in the pathogenesis of sickle cell anemia (SCA) and Duffy antigen receptor for chemokines (DARC) modulates the function of inflammatory processes, we analyzed the relationship between the erythrocyte DARC phenotype and clinical expression of SCA. DARC locus was genotyped in 212 SS adult patients followed by the sickle cell center of Guadeloupe (French West Indies). After patients' stratification according to RBC DARC expression, the prevalence of renal disease, leg ulcers, priapism and osteonecrosis was compared between patient groups as well as hematological variables and plasma levels of chemokines. Duffy-positive patients exhibited higher counts of white blood cells (9.95 ± 2.36 vs 8.88 ± 2.32 109/L, p = 0.0066), polynuclear neutrophils (5.1 ± 1.73 vs 4.51 ± 1.71 109/L, p = 0.0227), higher plasma levels of IL-8 (4.46 ± 1.22 vs 1.47 ± 0.5 pg/mL, p = 0.0202) and RANTES (27.8 ± 4.3 vs 18.1 ± 2.3 ng/mL, p = 0.04) than Duffy-negative patients. No association was detected between RBC expression of DARC and the studied complications. © 2010 Elsevier Inc. All rights reserved. Source

Hierso R.,French Institute of Health and Medical Research | Hierso R.,University of the French West Indies and Guiana | Hierso R.,Laboratory of Excellence GR Ex | Waltz X.,French Institute of Health and Medical Research | And 16 more authors.
British Journal of Haematology

Sickle cell anaemia (SS) and sickle cell-haemoglobin C disease (SC) patients exhibit severe red blood cell (RBC) rheological alterations involved in the development of several complications. The contribution of oxidative stress in these haemorheological abnormalities is still unknown. We compared RBC reactive oxygen species (ROS) and glutathione (GSH) content, and the haemorheological profile of SS (n = 11), SC (n = 11) and healthy subjects (n = 12) at baseline and after in-vitro treatment with t-butyl hydroperoxide (TBHP). We showed: (i) higher RBC ROS content in SS and SC patients, with the highest level observed in SS patients; (ii) lower RBC GSH content in sickle syndrome patients, especially in SS patients; (iii) TBHP increased RBC ROS production and decreased RBC GSH content in all groups; (iv) TBHP decreased RBC aggregation and increased the strength of RBC aggregates in all groups but the increase in RBC aggregates strength was greater in sickle cell patients; (v) TBHP decreased RBC deformability in the three groups but with a higher magnitude in sickle cell patients. These data suggest that RBCs from sickle cell patients have an exaggerated response to oxidative stress, which is accompanied by a profound abnormal haemorheological profile, with greater alterations in SS than in SC patients. © 2014 John Wiley & Sons Ltd. Source

Charlot K.,University of the French West Indies and Guiana | Charlot K.,University of Paris Pantheon Sorbonne | Romana M.,University of the French West Indies and Guiana | Romana M.,University of Paris Pantheon Sorbonne | And 18 more authors.
Blood Cells, Molecules, and Diseases

Vascular resistance and tissue perfusion may be both affected by impaired vascular function and increased blood viscosity. Little is known about the effects of vascular function on the occurrence of painful vaso-occlusive crises (VOC) in children with sickle cell anemia (SCA). The aim of the present study was to determine which side of the balance (blood viscosity or vascular function) is the most deleterious in SCA and increases the risk for frequent hospitalized VOC. Microvascular function, microcirculatory oxygenation and blood viscosity were determined in a group of 22 SCA children/adolescents at steady state and a group of 13 healthy children/adolescents. Univariate analyses demonstrated blunted microvascular reactivity during local thermal heating test and decreased microcirculatory oxygenation in SCA children compared to controls. Multivariate analysis revealed that increased blood viscosity and decreased microcirculatory oxygenation were independent risk factors of frequent VOC in SCA. In contrast, the level of microvascular dysfunction does not predict VOC rate. In conclusion, increased blood viscosity is usually well supported in healthy individuals where vascular function is not impaired. However, in the context of SCA, microvascular function is impaired and any increase of blood viscosity or decrease in microcirculatory oxygenation would increase the risks for frequent VOC. © 2015 Elsevier Inc. Source

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