The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform

Sverre E. Kjeldsen - One of the best experts on this subject based on the ideXlab platform.

Pierre Godeau - One of the best experts on this subject based on the ideXlab platform.

  • [Raynaud's phenomenon and Blood Viscosity].
    Journal des maladies vasculaires, 1992
    Co-Authors: Catherine Lacombe, J M Mouthon, C. Bucherer, J.c. Lelièvre, Olivier Bletry, Pierre Godeau
    Abstract:

    Raynaud's phenomenon is mainly linked with cold provoked vasomotor perturbations, but also with rheological alterations since Blood Viscosity is enhanced by lowering temperature. Several methods are available for studying distal vascularization: peri-ungual capillaroscopy, digital plethysmography and laser-Doppler. Digital arteriography must be reserved to serious ischemia regarding the general anesthesia needed to avoid spasm. All these methods explore especially the vessel wall. Conservely, Blood Viscosity which has been developed for 25 years investigates the content of the vessel. Since 1965, numerous hemorheological studies pointed out the rheological disorders, especially those concerning plasma and Blood Viscosity. The most usual viscometry abnormalities revealed erythrocyte hyperaggregation, red cell hypodeformability, Blood and plasmatic hyperViscosity. In a comparative study, 46 patients with Raynaud's phenomenon were studied: we performed peri-ungual capillaroscopy, plethysmography and Viscosity measurements. The results demonstrated a link between capillaroscopy and thixotropy. Both investigations are never normal at the same time in connectivites and never abnormal at the same time in Raynaud's disease (primary Raynaud's phenomenon). In conclusion hemorheological studies showed nearly normal rheological parameters in Raynaud's disease, but abnormal rheological parameters in secondary Raynaud's phenomenon.

Pierre Bouzat - One of the best experts on this subject based on the ideXlab platform.

  • Blood Viscosity and Its Determinants in the Highest City in the World
    The Journal of Physiology, 2020
    Co-Authors: Emeric Stauffer, Emmanuelle Loyrion, Ivan Hancco, Xavier Waltz, Mathilde Ulliel‐roche, Laura Oberholzer, Paul Robach, Aurélien Pichon, Julien V. Brugniaux, Pierre Bouzat
    Abstract:

    Key points: Highlanders develop unique adaptative mechanisms to chronic hypoxic exposure, including substantial haemoglobin and haematocrit increases. However, a significant proportion of populations living permanently at high altitude develop maladaptive features known as chronic mountain sickness (CMS). This study aimed to assess the effects of permanent life at high altitude on clinical and haemorheological parameters (Blood Viscosity and red Blood cell aggregation) and to compare clinical and haemorheological parameters of dwellers from the highest city in the world according to CMS severity. Blood Viscosity increased with altitude, together with haemoglobin concentration and haematocrit. At 5100 m, highlanders with moderate-to-severe CMS had higher Blood Viscosity mainly at high shear rate and even at corrected haematocrit (40%), with a lower red Blood cell aggregation. Blood Viscosity may contribute to CMS symptomatology but the increased Blood Viscosity in CMS patients cannot solely be explained by the rise in haematocrit. Abstract: Chronic mountain sickness (CMS) is a condition characterised by excessive erythrocytosis (EE). While EE is thought to increase Blood Viscosity and subsequently to trigger CMS symptoms, the exact relationship between Blood Viscosity and CMS symptoms remains incompletely understood. We assessed the effect of living at high altitude on haemoglobin, haematocrit and haemorheological parameters (Blood Viscosity and red Blood cell aggregation), and investigated their relationship with CMS in highlanders living in the highest city in the world (La Rinconada, Peru, 5100 m). Ninety-three men participated in this study: 10 Caucasian lowlanders, 13 Andean highlanders living at 3800 m and 70 Andean highlanders living at 5100 m (35 asymptomatic, CMS score ≤5; 15 with mild CMS, CMS score between 6 and 10; 20 with moderate-to-severe CMS, CMS score >10). Blood Viscosity was measured at native and corrected haematocrit (40%). Haemoglobin concentration and haematocrit increased with the altitude of residency. Blood Viscosity also increased with altitude (at 45 s-1 : 6.7 ± 0.9 mPa s at sea level, 14.0 ± 2.0 mPa s at 3800 m and 27.1 ± 8.8 mPa s at 5100 m; P < 0.001). At 5100 m, Blood Viscosity at corrected haematocrit was higher in highlanders with moderate-to-severe CMS (at 45 s-1 : 18.9 ± 10.7 mPa s) than in highlanders without CMS (10.2 ± 5.9 mPa s) or with mild CMS (12.1 ± 6.1 mPa s) (P < 0.05). In conclusion, Blood Viscosity may contribute to CMS symptomatology but the increased Blood Viscosity in CMS patients cannot solely be explained by the rise in haematocrit.

Eugene Butkowski - One of the best experts on this subject based on the ideXlab platform.

  • Whole Blood Viscosity assessment issues III: Association with international normalized ratio and thrombocytopenia
    North American journal of medical sciences, 2010
    Co-Authors: Ezekiel Uba Nwose, Nathan Cann, Eugene Butkowski
    Abstract:

    Background : Anticoagulant and antiplatelet therapies are being used interchangeably or in combination. While international normalized ratio is assessed to determine anticoagulant's contraindication/need, whole Blood Viscosity is not assessed to determine the need for antiplatelet. Aims : The objective of this study is to investigate whether whole Blood Viscosity value is associated with levels of international normalized ratio and platelet count. Materials and Methods : De-identified archived clinical pathology data for the year 2008 were audited. All cases of international normalized ratio, which were concomitantly tested for haematocrit and total proteins, were extracted (n=7,387). Whole Blood Viscosity levels were extrapolated. Whether differences are associated with normal vs. high international normalized ratio and thrombocytopenia vs. thrombocytosis were evaluated. Results : Multivariate analysis show that whole Blood Viscosity levels statistically significantly differs between international normalized ratio and platelet counts (p Conclusion : The observation corroborates with previous reports to suggest putting into perspective the specificity of whole Blood Viscosity relative to stasis, against which antiplatelet is employed. It indicates that low whole Blood Viscosity is synonymous to high international normalized ratio whereby anticoagulant and antiplatelet therapies are contraindicated. International normalized ratio, platelet count and Blood Viscosity are laboratory indices to consider in constituting antiplatelet monitoring panel.

Karniadakis Ge - One of the best experts on this subject based on the ideXlab platform.

  • Predicting human Blood Viscosity in silico.
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Fedosov Da, Wenxiao Pan, Bruce Caswell, Gerhard Gompper, Karniadakis Ge
    Abstract:

    The Viscosity of Blood has long been used as an indicator in the understanding and treatment of disease, and the advent of modern viscometers allows its measurement with ever-improving clinical convenience. However, these advances have not been matched by theoretical developments that can yield a quantitative understanding of Blood's microrheology and its possible connection to relevant biomolecules (e.g., fibrinogen). Using coarse-grained molecular dynamics and two different red Blood cell models, we accurately predict the dependence of Blood Viscosity on shear rate and hematocrit. We explicitly represent cell-cell interactions and identify the types and sizes of reversible rouleaux structures that yield a tremendous increase of Blood Viscosity at low shear rates. We also present the first quantitative estimates of the magnitude of adhesive forces between red cells. In addition, our simulations support the hypothesis, previously deduced from experiments, of yield stress as an indicator of cell aggregation. This non-Newtonian behavior is analyzed and related to the suspension's microstructure, deformation, and dynamics of single red Blood cells. The most complex cell dynamics occurs in the intermediate shear rate regime, where individual cells experience severe deformation and transient folded conformations. The generality of these cell models together with single-cell measurements points to the future prediction of Blood-Viscosity anomalies and the corresponding microstructures associated with various diseases (e.g., malaria, AIDS, and diabetes mellitus). The models can easily be adapted to tune the properties of a much wider class of complex fluids including capsule and vesicle suspensions.