The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Christian Wagner - One of the best experts on this subject based on the ideXlab platform.
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vortical flow structures induced by red Blood Cells in capillaries
Microcirculation, 2021Co-Authors: Francois Yaya, Johannes Romer, Achim Guckenberger, Thomas John, Stephan Gekle, Thomas Podgorski, Christian WagnerAbstract:Objective Knowledge about the flow field of the plasma around the red Blood Cells in capillary flow is important for a physical understanding of Blood flow and the transport of micro- and nanoparticles and molecules in the flowing plasma. We conducted an experimental study on the flow field around red Blood Cells in capillary flow that is complemented by simulations of vortical flow between red Blood Cells. Methods Red Blood Cells were injected in a 10 × 12 µm rectangular microchannel at a low hematocrit, and the flow field around one or two Cells was captured by a high-speed camera that tracked 250 nm nanoparticles in the flow field, acting as tracers. Results While the flow field around a steady "croissant" shape is found to be similar to that of a rigid sphere, the flow field around a "slipper" shape exhibits a small vortex at the rear of the red Blood cell. Even more pronounced are vortex-like structures observed in the central region between two neighboring croissants. Conclusions The rotation frequency of the vortices is to a good approximation, inversely proportional to the distance between the Cells. Our experimental data are complemented by numerical simulations.
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vortical flow structures induced by red Blood Cells in capillaries
arXiv: Biological Physics, 2021Co-Authors: Francois Yaya, Johannes Romer, Achim Guckenberger, Thomas John, Stephan Gekle, Thomas Podgorski, Christian WagnerAbstract:Knowledge about the flow field of the plasma around the red Blood Cells in capillary flow is important for a physical understanding of Blood flow and the transport of micro- and nanoparticles and molecules in the flowing plasma. We conduct an experimental study on the flow field around red Blood Cells in capillary flow that are complemented by simulations of vortical flow between red Blood Cells. Red Blood Cells were injected in a 10x12 micrometer rectangular microchannel at a low hematocrit and the flow field around a single or two Cells have been characterized thanks to a highspeed camera and by tracking 250 nm nanoparticles in flow behaving as tracers. While the flow field around a steady croissant shape is found to be relatively similar to that of a rigid sphere, the flow field around a slipper shape exhibits a small vortex at the rear of the red Blood cell. Even more pronounced are vortex-like structures observed in the central region between two neighboring croissants. Conclusions: The rotation frequency of the vortices is to a good approximation, inversely proportional to the distance between the Cells. Our experimental data are confirmed and complemented by numerical simulations.
Axel Voigt - One of the best experts on this subject based on the ideXlab platform.
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margination of white Blood Cells a computational approach by a hydrodynamic phase field model
Journal of Fluid Mechanics, 2016Co-Authors: Wieland Marth, Sebastian Aland, Axel VoigtAbstract:We numerically investigate margination of white Blood Cells and demonstrate the dependency on a number of conditions including haematocrit, the deformability of the Cells and the Reynolds number. The approach, which is based on a mesoscopic hydrodynamic Helfrich-type model, reproduces previous results, e.g. a decreasing tendency for margination with increasing deformability and a non-monotonic dependency on haematocrit. The consideration of inertia effects, which may be of relevance in various parts of the cardiovascular system, indicates a decreasing tendency for margination with increasing Reynolds number. The effect is discussed by analysing inertial and non-inertial lift forces for single Cells under different flow conditions and large-scale two-dimensional simulations of interacting red Blood Cells and white Blood Cells in an idealized Blood vessel.
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margination of white Blood Cells a computational approach by a hydrodynamic phase field model
arXiv: Biological Physics, 2015Co-Authors: Wieland Marth, Axel VoigtAbstract:We numerically investigate margination of white Blood Cells and demonstrate the dependency on a number of conditions including hematocrit, the deformability of the Cells and the Reynolds number. A detailed mesoscopic hydrodynamic Helfrich-type model is derived, validated and used for the simulations to provides a quantitative description of the margination of white Blood Cells. Previous simulation results, obtained with less detailed models, could be confirmed, e.g. the largest probability of margination of white Blood Cells at an intermediate range of hematocrit values and a decreasing tendency with increasing deformability. The consideration of inertia effects, which become of relevance in small vessels, also shows a dependency and leads to less pronounced margination of white Blood Cells with increasing Reynolds number.
Maxey C M Chung - One of the best experts on this subject based on the ideXlab platform.
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membrane proteins of human fetal primitive nucleated red Blood Cells
Journal of Proteomics, 2012Co-Authors: Sukumar Ponnusamy, Huoming Zhang, Priya Kadam, Jaspal Singh Sandhu, Narasimhan Kothandaraman, Aniza Puteri Mahyuddin, Arijit Biswas, Annapoorna Venkat, Shashikant B Joshi, Maxey C M ChungAbstract:Abstract In humans, primitive fetal nucleated red Blood Cells (FNRBCs) are thought to be as vital for embryonic life as their counterpart, adult red Blood Cells (adult RBCs) are in later-gestation fetuses and adults. Unlike adult RBCs, the identity and functions of FNRBC proteins are poorly understood owing to a scarcity of FNRBCs for proteomic investigations. The study aimed to investigate membrane proteins of this unique cell type. We present here, the first report on the membrane proteome of human primitive FNRBCs investigated by two-dimensional liquid chromatography coupled with mass-spectrometry (2D-LCMS/MS) and bioinformatics analysis. A total of 273 proteins were identified, of which 133 (48.7%) were membrane proteins. We compared our data with membrane proteins of adult RBCs to identify common, and unique, surface membrane proteins. Twelve plasma membrane proteins with transmembrane domains and eight proteins with transmembrane domains but without known sub-cellular location were identified as unique-to-FNRBCs. Except for the transferrin receptor, all other 19 unique-to-FNRBC membrane proteins have never been described in RBCs. Reverse-transcriptase PCR (RT-PCR) and immunocytochemistry validated the 2D-LCMS/MS data. Our findings provide potential surface antigens for separation of primitive FNRBCs from maternal Blood for noninvasive prenatal diagnosis, and to understand the biology of these rare Cells.
M C Hermansen - One of the best experts on this subject based on the ideXlab platform.
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nucleated red Blood Cells in the fetus and newborn
Archives of Disease in Childhood-fetal and Neonatal Edition, 2001Co-Authors: M C HermansenAbstract:Although nucleated red Blood Cells (nRBCs) are rarely found circulating in older children,1 they are commonly seen in the Blood of newborns. They are primarily produced in the fetal bone marrow in response to erythropoietin and are stored in the marrow as precursors to reticulocytes and mature erythrocytes. Many acute and chronic stimuli cause increases in the number of circulating nRBCs from either increased erythropoietic activity or a sudden release from the marrow storage pools. This paper reviews the various pathological processes associated with increased production and release of nRBCs. It emphasises the effects of acute, subacute, and chronic asphyxia on nRBC counts.#### Key message 1 Common causes of increased nucleated red Blood Cells include prematurity, increased erythropoiesis from chronic hypoxia, anaemia, and maternal diabetes, from acute stress mediated release from the marrow stores, and from postnatal hypoxia. Extreme increases may occasionally be idiopathic. #### Key message 2 When increased nRBC counts are seen with acute and subacute asphyxia, the magnitude of the increase is a function of the severity and duration of the asphyxia. However, there is a large overlap between the nRBC values found after acute, subacute, and chronic asphyxia; asphyxia of any duration does not always cause an increased nRBC count, and extreme increases may be found without asphyxia. Nucleated red Blood Cells are sometimes called erythroblasts, normoblasts, or normocytes. For this review, the term “normoblasts” will be used to refer to the Cells when they are in the bone marrow and “nRBCs” when they are in circulating Blood. Clinically it is best to express nRBCs as an absolute number of Cells per unit volume, either “nRBCs/mm3” or “nRBCs/l”. However, most clinical laboratories and many research publications report nRBCs relative to 100 white Blood Cells (WBCs). Unfortunately the extreme variability in the number of leucocytes …
L Mahadevan - One of the best experts on this subject based on the ideXlab platform.
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statistical dynamics of flowing red Blood Cells by morphological image processing
PLOS Computational Biology, 2009Co-Authors: John M Higgins, David T Eddington, Sangeeta N Bhatia, L MahadevanAbstract:Blood is a dense suspension of soft non-Brownian Cells of unique importance. Physiological Blood flow involves complex interactions of Blood Cells with each other and with the environment due to the combined effects of varying cell concentration, cell morphology, cell rheology, and confinement. We analyze these interactions using computational morphological image analysis and machine learning algorithms to quantify the non-equilibrium fluctuations of cellular velocities in a minimal, quasi-two-dimensional microfluidic setting that enables high-resolution spatio-temporal measurements of Blood cell flow. In particular, we measure the effective hydrodynamic diffusivity of Blood Cells and analyze its relationship to macroscopic properties such as bulk flow velocity and density. We also use the effective suspension temperature to distinguish the flow of normal red Blood Cells and pathological sickled red Blood Cells and suggest that this temperature may help to characterize the propensity for stasis in Virchow's Triad of Blood clotting and thrombosis.
