Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s-1), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r = 0.28; p = 0.03 and r = 0.38; p = 0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R2 < 0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
ISSN: 1386-0291

inserm-01081701
http://www.hal.inserm.fr/inserm-01081701
http://www.hal.inserm.fr/inserm-01081701/document
http://www.hal.inserm.fr/inserm-01081701/file/2013%2C%20Waltz%20-%20Is%20there%20a%20relationship%20between%20the%20hematocrit-to-viscosity%20ratio%20and%20microvascular%20oxygenation%20in%20brain%20and%20muscle.pdf
PUBMED : 23719422

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s −1), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r = 0.28; p = 0.03 and r = 0.38; p = 0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R 2 < 0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
ISSN: 1386-0291

hal-01163460
https://hal.univ-antilles.fr/hal-01163460
DOI : 10.3233/CH-131742

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Because of the metabolic changes induced by a physical activity, the hemorheological properties of patients with sickle cell anemia could be further impaired and increase the risks for vaso-occlusive complications. However, few studies suggest that moderate physical activity could be beneficial rather than harmful in patients with sickle cell anemia (SCA). However, the definition of what can be considered as a moderate physical activity in SCA patients is imprecise. The present study tested the effects of a short incremental cycling exercise test conducted until the first ventilatory threshold on different biomarkers. Hematological and hemorheological parameters were compared between 8 patients with SCA and 13 healthy subjects (CONT) before, immediately after the end of the exercise and at 12, 36 and 60 hours after the exercise. We observed no significant hematological or hemorheological alteration induced by the exercise in the two groups. However, the exercise resulted in a delayed improvement of the red blood cell disaggregation threshold at 36 and 60 hrs after exercise in the SCA group which was paralleled to the decrease in the platelet count in this group. The present study suggests that such an exercise might be beneficial for microcirculatory blood flow.
ISSN: 1386-0291

hal-01137567
https://hal.univ-antilles.fr/hal-01137567

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Studies performed in the last decades have highlighted the need to better understand the contribution of the endothelium, vascular function, oxidative stress, inflammation, coagulation, hemolysis and vascular adhesion mechanisms to the pathophysiology of acute vaso-occlusive like events and chronic organ damages in sickle cell disease (SCD). Although SCD is a hemorheological disease, a few works focused on the contribution of blood viscosity, plasma viscosity, red blood cell deformability and aggregation in the pathophysiology of SCD. After a brief description of basic hemorheology, the present review focuses on the role of the hemorheological abnormalities in the causation of several SCD complications, mainly in sickle cell anemia and hemoglobin (Hb) SC disease. Several genetic and cellular modulators of blood rheology in SCD are discussed, as well as unresolved questions and perspectives.
ISSN: 0268-960X

hal-01668334
https://hal.univ-antilles.fr/hal-01668334
DOI : 10.1016/j.blre.2015.08.005

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
This document, supported by both the International Society for Clinical Hemorheology and the European Society for Clinical Hemorheology and Microcirculation, proposes new guidelines for hemorheological methods used in experimental and clinical studies. It is based on a similar document entitled: "Guidelines for measurement of blood viscosity and erythrocyte deformability" published in 1986 by the Expert Panel on Blood Rheology of the International Committee for Standardization in Hematology. Recent methods, techniques and instruments, as well as new approaches to interpretation of results, are added to these new guidelines; wide spread adoption should improve comparability between hemorheological laboratories and increase the reliability of rheological tests.
ISSN: 1386-0291

hal-00709840
https://hal.archives-ouvertes.fr/hal-00709840
https://hal.archives-ouvertes.fr/hal-00709840/document
https://hal.archives-ouvertes.fr/hal-00709840/file/New_Guidelines_accepted_1-4-2009.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Leg ulcer is a disabling complication in patients with sickle cell anemia (SCA) but the exact pathophysiological mechanisms are unknown. The aim of this study was to identify the hematological and hemorheological alterations associated with recurrent leg ulcers. Sixty-two SCA patients who never experienced leg ulcers (ULC-) and 13 SCA patients with a positive history of recurrent leg ulcers (ULC+) - but with no leg ulcers at the time of the study - were recruited. All patients were in steady state condition. Blood was sampled to perform hematological, biochemical (hemolytic markers) and hemorheological analyses (blood viscosity, red blood cell deformability and aggregation properties). The hematocrit-to-viscosity ratio (HVR), which reflects the red blood cell oxygen transport efficiency, was calculated for each subject. Patients from the ULC+ group were older than patients from the ULC- group. Anemia (red blood cell count, hematocrit and hemoglobin levels) was more pronounced in the ULC+ group. Lactate dehydrogenase level was higher in the ULC+ group than in the ULC- group. Neither blood viscosity, nor RBC aggregation properties differed between the two groups. HVR was lower and RBC deformability tended to be reduced in the ULC+ group. Our study confirmed increased hemolytic rate and anemia in SCA patients with leg ulcers recurrence. Furthermore, our data suggest that although systemic blood viscosity is not a major factor involved in the pathophysiology of this complication, decreased red blood cell oxygen transport efficiency (i.e., low hematocrit/viscosity ratio) may play a role.
ISSN: 1932-6203

inserm-00922105
http://www.hal.inserm.fr/inserm-00922105
http://www.hal.inserm.fr/inserm-00922105/document
http://www.hal.inserm.fr/inserm-00922105/file/2013_Connes_-_Decreased_Hematocrit.pdf
DOI : 10.1371/journal.pone.0079680

Éditeur(s) : HAL CCSD IOS Press
Résumé : The main objectives of the present work were to test the effects of heat stress on blood rheology and to determine whether the responses can change according to the pig breeds. Thirty-six pigs from three pig's lines (n = 12 for each line) with assumed different tolerance to heat stress were compared: Large White (LW, little tolerance), Creole (CR, good tolerance) and LW × CR pigs (produced from a cross between LW and CR lines). In a first period, all pigs were exposed to a 9-d period of thermo-neutral environment (24°C; d-9 to d-1; P0). At the end of P0, six pigs from each line were slaughtered (n = 18). Then in a second period, the remaining pigs (6/breed; n = 18) were exposed to a 5-d period of heat stress (32°C; d + 1 -d + 5; P1) and thereafter slaughtered at d + 5. Rectal and skin temperatures, as well as respiratory rate, were recorded on d-1 and d + 5. At slaughter, blood was sampled for hematological and hemorheological measurements. Heat stress caused a rise of the skin temperature and respiratory rate without any changes in the rectal temperature or on the hematological and hemorheological parameters when all pigs' lines were considered. We observed a pig line effect on blood viscosity at high shear rate (375 s-1) and red blood cell deformability at 30 Pa with CR pigs having lower blood viscosity and higher red blood cell deformability than LW pigs. While the changes of blood viscosity under heat stress did not reach statistical significance in LW and CR lines, blood viscosity (at 375 s-1) increased above the temperate values in the LW × CR line. Red blood cell deformability at 30 Pa was higher in CR pigs exposed to heat stress compared to LW pigs in the same condition. In conclusion, thermal loading caused physiological stress but did not widely change the hematological and hemorheological profiles. Although some blood rheological parameters seem to vary with the pig breeds, the responses to heat stress are very similar.
ISSN: 1386-0291

hal-01210926
https://hal.archives-ouvertes.fr/hal-01210926
DOI : 10.3233/CH-131722
PRODINRA : 286489
PUBMED : 23603327

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
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.
ISSN: 1386-0291

inserm-00849032
http://www.hal.inserm.fr/inserm-00849032
http://www.hal.inserm.fr/inserm-00849032/document
http://www.hal.inserm.fr/inserm-00849032/file/inserm-00849032.pdf
DOI : 10.3233/CH-2012-1622

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Heat stress is one of the major limiting factors of production efficiency in the swine industry. The aims of the present study were 1) to observe if hemorheological and hematological parameters could be associated to physiological acclimation during the first days of heat stress exposure and 2) to determine if water restriction could modulate the effect of thermal heat stress on physiological, hematological and hemorheological parameters. Twelve Large White male pigs were divided into an ad libitum and a water restricted group. All pigs were submitted to one week at 24 °C (D-7 to D-1). Then, at D0, temperature was progressively increased until 32 °C and maintained during one week (D1 to D7). We performed daily measurements of water and feed intake. Physiological (i.e., skin temperature, rectal temperature, respiratory rate), hematological and hemorheological parameters were measured on D-6, D-5, D0, D1, D2 and D7. Water restriction had no effect on physiological, hematological and hemorheological parameters. The first days of heat stress caused an increase in the three physiological parameters followed by a reduction of these parameters suggesting a successful acclimation of pigs to heat stress. We showed an increase in hematocrit, red blood cell aggregation and red blood cell aggregation strength during heat stress. Further, we observed an important release of reticulocytes, an increase of red blood cell deformability and a reduction of feed intake and blood viscosity under heat stress. This study suggests that physiological acute adaptation to heat stress is accompanied by large hematological and hemorheological changes.
ISSN: 1932-6203

hal-01210648
https://hal.archives-ouvertes.fr/hal-01210648
DOI : 10.1371/journal.pone.0102537
PRODINRA : 269557
PUBMED : 25013960

Éditeur(s) : HAL CCSD Ferrata Storti Foundation
Résumé : International audience
The aim of the study was to determine the factors associated with resting and exercise-induced hemoglobin oxygen desaturation. The well-established six-minute walk test was conducted in 107 sickle cell children (50 with sickle hemoglobin C disease and 57 with sickle cell anemia) at steady state. Hemoglobin oxygen saturation was measured before and immediately after the six-minute walk test. Blood samples were obtained on the same day to measure hematologic and hemorheological parameters. Exercise-induced hemoglobin oxygen desaturation was defined as a drop in hemoglobin oxygen saturation of 3% or more at the end of the six-minute walk test compared to resting levels. No children with sickle hemoglobin C disease, but approximately 50% of children with sickle cell anemia showed mild or moderate oxygen desaturation at rest, which was independently associated with the percentage of reticulocytes. Exercise-induced hemoglobin oxygen desaturation was observed in 18% of children with sickle hemoglobin C disease and 34% of children with sickle cell anemia, and was independently associated with the six-minute walk test, acute chest syndrome rate and the strength of red blood cell aggregates in children with sickle cell anemia. No association was found in children with sickle hemoglobin C disease between exercise-induced hemoglobin oxygen desaturation and the measured parameters. Hemoglobin oxygen desaturation at rest was common in children with sickle cell anemia but not in children with sickle hemoglobin C disease, and was mainly associated with greater hemolysis. Physiological strain during exercise and red blood cell aggregation properties may predict the occurrence of exercise-induced hemoglobin oxygen desaturation in children with sickle cell anemia.
ISSN: 0390-6078

inserm-00838989
http://www.hal.inserm.fr/inserm-00838989
http://www.hal.inserm.fr/inserm-00838989/document
http://www.hal.inserm.fr/inserm-00838989/file/Waltz_et_al._Ferrata_Storti_Foundation.pdf
DOI : 10.3324/haematol.2013.083576

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Hemorheological abnormalities have been well characterized in sickle cell disease (SCD) and seem to modulate the clinical severity [1]. For instance, increased blood viscosity raises the risk for frequent vaso-occlusive crisis (VOC) and increased red blood cell (RBC) aggregates robustness (i.e., RBC disaggregation threshold) enhances the risks for acute chest syndrome (ACS) [2]. Moreover, patients with the most rigid RBCs are characterized by high hemolytic rate, which increases the risks to develop leg ulcers or glomerulopathy [3]. However, except few studies supporting an effect of alpha-thalassemia and oxidative stress [1] on RBC rheological properties of SCD patients, very few experiments focused on the genetic and cellular factors modulating blood rheology in this disease.
ISSN: 1079-9796

hal-01263890
https://hal.archives-ouvertes.fr/hal-01263890
https://hal.archives-ouvertes.fr/hal-01263890/document
https://hal.archives-ouvertes.fr/hal-01263890/file/Ferdinand%20et%20al.%20eNOS%20and%20RBC%20rheology%20in%20SCD_BCMD.pdf
PUBMED : 26142331

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The aim of the present study was to test the effects of hydroxyurea (HU) therapy on clinical, hematological and hemorheological parameters in adult patients with sickle cell anemia (SCA). Hematological and hemorheological parameters were measured in 28 SCA patients before HU therapy (i.e., baseline) and at 6, 12 and 24 months of treatment. RBC deformability was determined by ektacytometry at 30 Pa. RBC aggregation properties were investigated by light-backscatter method. Blood viscosity was measured at 225 s-1 by a cone-plate viscometer. The rates of vaso-occlusive crises and acute chest syndrome were lower at 1 and 2 years of HU therapy compared to baseline. The proportion of patients with leg ulcers tended to decrease after 2 years of treatment. Hemoglobin oxygen saturation improved with HU therapy. HU therapy induced a decrease of platelet and white blood cell counts and a rise in fetal hemoglobin level and mean cell volume. While hemoglobin concentrations increased under HU, blood viscosity remained unchanged all along the study. RBC deformability increased over baseline values at 6 months of HU therapy and continued to rise until the end of the follow-up period. In conclusion, the improvement in RBC deformability probably compensates the increase of hemoglobin on blood viscosity and participates to the improvement of the clinical status of patients.
ISSN: 1386-0291

hal-01668327
https://hal.univ-antilles.fr/hal-01668327
DOI : 10.3233/CH-170280

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND/AIM: Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue. METHODS: We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients. RESULTS: Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects. CONCLUSIONS: Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit mitochondrial respiration but increases muscle microvascular blood flow.
ISSN: 1932-6203

inserm-00849035
http://www.hal.inserm.fr/inserm-00849035
http://www.hal.inserm.fr/inserm-00849035/document
http://www.hal.inserm.fr/inserm-00849035/file/2013_Waltz_-_Normal_muscle_oxygen_consumption_and_fatigability_in_sickle_cell_patients.pdf
DOI : 10.1371/journal.pone.0052471

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Patients with hemoglobin C disease (CC) usually do not develop severe complications in comparison with individuals with sickle cell anemia (SS) or with sickle cell hemoglobin C disease (SC). The present study compared the hematological, biochemical, hemorheological and clinical characteristics of CC patients to those of SS, SC and healthy individuals (AA). Blood viscosity was measured at 225 s(-1) with a cone plate viscometer. The hematocrit-to-blood viscosity ratio (HVR), i.e. an index of red blood cell (RBC) oxygen transport effectiveness, was calculated. RBC deformability was determined at 30 Pa by ektacytometry, and RBC aggregation properties by syllectometry. CC and SC had higher blood viscosity and lower HVR than AA. Nevertheless, HVR was higher in CC compared to SS and tended to be higher than in SC. The CC group exhibited very rigid hyperchromic RBC compared to the three other groups. RBC aggregation abnormalities were observed in CC: low RBC aggregation index and high RBC aggregates strength. Despite these hemorheological abnormalities, CC never had hospitalized painful vaso-occlusive crisis or acute chest syndrome. In contrast, all of them had splenomegaly. Of note, 2 out of 7 CC developed retinopathy or otologic disorders. Whether the blood hyperviscosity and decreased RBC deformability are responsible for these complications is unknown. The higher oxygen transport effectiveness (i.e., HVR) of CC compared to SS is probably at the origin of the very low risk of medical complication in this population.
ISSN: 1386-0291

hal-01668336
https://hal.univ-antilles.fr/hal-01668336
DOI : 10.3233/CH-141906

Éditeur(s) : HAL CCSD Ferrata Storti Foundation
Résumé : International audience
Lionnet et al. recently reported a high prevalence of retinopathy (RET) and otologic disorders (OTD) in patients with sickle cell-hemoglobin C disease (SC), while a significant number of patients had renal diseases (mainly glomerulopathy; GLO) and osteonecrosis (OST). The pathophysiological processes of these complications in SC are not well defined, although blood hyperviscosity has been suspected, but never tested to the best of our knowledge, as responsible for several chronic complications in SC disease1,2. The aim of this study was to analyze the associations between hematological and hemorheological parameters and chronic complications in adult SC patients.
ISSN: 0390-6078

inserm-01081709
http://www.hal.inserm.fr/inserm-01081709
http://www.hal.inserm.fr/inserm-01081709/document
http://www.hal.inserm.fr/inserm-01081709/file/2014%2C%20Lemonne%20-%20Impaired%20blood%20rheology%20plays%20a%20role%20in%20the%20chronic%20disorders%20associated%20with%20sickle%20cell-hemoglobin%20C%20disease.pdf
PUBMED : 24633868

Résumé : Nous avons étudié les marqueurs hémorhéologiques, hématologiques et biochimiques chez des sujets drépanocytaires homozygotes SS (HbS/HbS) et hétérozygotes composites SC (HbS/HbC) dans deux cohortes, pédiatriques et adultes, de patients drépanocytaires, et ce, à travers 7 complications récurrentes de la drépanocytose : 2 appartenant au profil hémolytique (l’ulcère de jambes et la glomérulopathie) et 5 appartenant au phénotype visqueux/vaso-occlusif (l’hypertension artérielle, le syndrome thoracique aigu (STA), la crise vaso-occlusive (CVO), la rétinopathie et l’ostéonécrose). Nous avons montré que : 1) une viscosité sanguine et une déformabilité érythrocytaire élevées sont des facteurs de risques de CVO chez les enfants homozygotes ; 2) Une viscosité sanguine élevée est associée à une hypertension artérielle systémique relative chez des adultes SS ; 3) les enfants SC présente une fonction vasculaire mieux préservée que les enfants SS pour faire face à une augmentation de la viscosité sanguine ; 4) les patients adultes SS avec une ostéonécrose présentent une déformabilité érythrocytaire plus élevée que les patients sans ostéonécrose ; 5) une viscosité sanguine élevée est associée à la présence d’une rétinopathie chez les adultes SC mais pas chez les SS ; 6) les patients adultes SS présentant une glomérulopathie ont un taux d’hémolyse élevé, une déformabilité érythrocytaire réduite et des agrégats érythrocytaires très robustes ; 7) les patients adultes SS avec des ulcères de jambes récurrents ont un taux d’hémolyse accru et une déformabilité érythrocytaire réduite. De plus, nos travaux confirment que l’-thalassémie module les propriétés de déformabilité érythrocytaire, mais montrent pour la première fois qu’elle module aussi les propriétés d’agrégation érythrocytaire, et notamment la force des agrégats érythrocytaires. En conclusion, ces travaux permettent de préciser le rôle de la rhéologie sanguine dans un certain nombre de complications de la drépanocytose et d’enrichir le modèle préexistant divisant les complications de la drépanocytose selon 2 phénotypes : hémolytique versus visqueux/vaso-occlusif. Nous montrons pour la première fois que le phénotype hémolytique est caractérisé aussi par des anomalies de la rhéologie du globule rouge : rigidité accrue et agrégats érythrocytaire robustes.
Hemorheological, hemathological, and biochemical marquers of patients with sickle cell anemia (SS) and patients with sickle cell SC disease (SC) were studied in 2 cohorts: children and adults. We focused on 7 recurrent complications: 5 belonging to the viscosity/vaso-occlusion phenotype (systemic hypertension, acute chest syndrome (ACS), vaso-occlusive crisis (VOC), retinopathy and osteonecrosis) and 2 belonging to the hemolytic phenotype (leg ulcer and glomerulopathy). Our results show that 1) high viscosity is associated with increased risk for VOC in SS children; 2) blood viscosity is increased in SS adults with systemic relative hypertension; 3) SC children have preserved vascular function compared to SS children; 4) SS adults with osteonecrosis are characterized by higher red blood cell (RBC) deformability than SS adults without osteonecrosis; 5) high blood viscosity is associated with retinopathy in SC adults but not in SS adults; 6) SS adults affected by glomerulopathy have high hemolytic rate, low RBC deformability and increased RBC aggregates strenght; 7) SS adults with recurrent leg ulcers have high hemolytic rate and reduced RBC deformability. Moreover, our studies shows that alpha-thalassemia modulate RBC deformability and RBC aggregation properties. In conclusion, this work shows for the first time that the hemolytic phenotype is characterized by an abnormal RBC rheology which may play a role in several sickle cell complications.

http://www.theses.fr/2013AGUY0684/document

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The six-minute walk test is a well-established submaximal exercise reflecting the functional status and the clinical severity of sickle cell patients. The aim of the present cross-sectional study was to investigate the biological determinants of the six-minute walk test performance in children with sickle cell anemia. Hematological and hemorheological parameters, pulmonary function and the six-minute walk test performance were determined in 42 children with sickle cell anemia at steady state. The performance during the six-minute walk test was normalized for age, sex and height and expressed as percentage of the predicted six-minute walk distance. We showed that a high level of anemia, a low fetal hemoglobin expression and low red blood cell deformability were independent predictors of a low six-minute walk test performance. This study describes for the first time the impact of blood rheology in the six-minute walk test performance in children with sickle cell anemia.
ISSN: 1932-6203

inserm-00922110
http://www.hal.inserm.fr/inserm-00922110
http://www.hal.inserm.fr/inserm-00922110/document
http://www.hal.inserm.fr/inserm-00922110/file/2013_Waltz_-_Hematological_and_hemorheological_determinants_6_minutes.pdf
DOI : 10.1371/journal.pone.0077830

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Purpose: The aim of this study was to clarify whether exercising in a tropical climate induces blood rheology alterations despite ad libitum hydration. Methods: Hematological, biochemical and hemorheological changes were investigated in young healthy adults (N = 9 men, 20.7 ± 0.8 yrs) after a 10-km race in hot and humid conditions. Subjects' maximal aerobic abilities were tested using a maximal ramp exercise. Blood was sampled at rest (T R), at the end of the race (T Ex), and after 24 hours of recovery (T 24). Ad libitum hydra-tion was allowed during the race. Blood viscosity (b), red blood cell deformability (EI), aggregation (AI) and disaggregation shear rate (␥) were measured. Results: Hematocrit, hemoglobin and plasma concentration of chlorine, sodium and potassium did not change in response to exercise. No functional consequence was observed on RBC deformability since EI remained unchanged. Percentages of echinocytes, schizocytes and stomatocytes remained in the subclinical range at all times. AI, µ and ßb did not present change. Conclusion: Running exercise in tropical climate with ad libitum hydration does not alter the main rheological properties of blood.
ISSN: 1386-0291

hal-01163975
https://hal.univ-antilles.fr/hal-01163975
DOI : 10.3233/CH-2011-1388

Résumé : La drépanocytose est une hémoglobinopathie aux formes et aux sévérités cliniques très hétérogènes qui affectent de nombreux organes chez les patients touchés. Pour cette raison le terme de syndrome drépanocytaire majeur est généralement employé. Tous les syndromes drépanocytaires majeurs ont en commun une mutation ponctuelle du gène β-globine appelée mutation βs . Cette mutation βs conduit à la synthèse de la protéine d'hémoglobine S (HbS) caractérisée par sa capacité à polymériser dans sa forme désoxygénée. La polymérisation de l'HbS est l'élément déclencheur de la falciformation du globule rouge et conduit à de nombreuses altérations hématologiques et hémorhéologiques. Ces dernières sont à l'origine de troubles de l'hémodynamique, de l'oxygénation sanguine et de la perfusion tissulaire en oxygène. Il en résulte de nombreuses complications aigues (crise vaso-occlusive, accident vasculaire cérébral, syndrome thoracique aigu etc.) et/ou chroniques (glomérulopathie, ostéonécrose de la tête fémorale etc.) causés par un défaut d'oxygénation des tissus.
Sickle cell anemia is a hemoglobinopathy forms and severities very heterogeneous clinical affecting many organs in affected patients. For this reason the term major sickle cell syndrome is generally used. All major sickle cell syndromes have a common point mutation in the gene called β-globin mutation βs. This βs mutation leads to the synthesis of the protein hemoglobin S (HbS) is characterized by its ability to polymerize in its deoxygenated form. The polymerization of HbS is the trigger for the sickling of red blood cells and leads to many Hematological and hemorheological. These are at the origin of disorders hemodynamics, blood oxygenation and tissue perfusion with oxygen. This results in many acute complications (vaso-occlusive crisis, stroke, acute chest syndrome, etc..) And / or chronic (glomerulopathy, osteonecrosis of the femoral head etc.). Caused by a defect of tissue oxygenation.

http://www.theses.fr/2012AGUY0563/document

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The levels and duration of physical activity that can be considered as completely safe in patients with sickle cell anemia (SCA) is unknown. The present study compared the hemorheological and hematological profile, cell density distribution and basic biochemistry between a group of 17 patients with SCA and 21 healthy subjects before and after a 20 min duration submaximal cycling exercise at the same absolute workload. Blood was sampled at rest and 3 min after the end of exercise for measurement of biological parameters. Exercise did not affect the hematocrit and blood viscosity in the two groups. Plasma viscosity was not different between the two groups at rest and similarly increased with exercise. The proportion of intermediary dense cells (with density between 1.11 and 1.12 g/ml) decreased with exercise in the SCA group resulting in an increase in the proportion of red blood cells with a density > 1.12 g/ml. No change was observed in the control group. The present study suggests that mild-moderate exercise is not very harmful for SCA patients. The hemorheological and hematological changes very mild, except for the formation of dense cells but no clinically significant signs of medical complication were present in any of the patients.
ISSN: 0007-1048

hal-00640629
https://hal.archives-ouvertes.fr/hal-00640629
https://hal.archives-ouvertes.fr/hal-00640629/document
https://hal.archives-ouvertes.fr/hal-00640629/file/PEER_stage2_10.1111%252Fj.1365-2141.2011.08728.x.pdf
DOI : 10.1111/j.1365-2141.2011.08728.x