Influence of erythrocyte aggregation on leukocyte margination in postcapillary venules of rat mesentery

2000 ◽  
Vol 279 (4) ◽  
pp. H1460-H1471 ◽  
Author(s):  
Mark J. Pearson ◽  
Herbert H. Lipowsky
Keyword(s):  
Steady State ◽  
Blood Cell ◽  
Aggregate Size ◽  
State Level ◽  
Erythrocyte Aggregation ◽  
Shear Rates ◽  
Rat Mesentery ◽  
Rbc Aggregation ◽  
Proximal Occlusion

The role of erythrocyte (red blood cell; RBC) aggregation in affecting leukocyte (white blood cell; WBC) margination in postcapillary venules of the mesentery (rat) was explored by direct intravital microscopy. Optical techniques were refined and applied to relate the light-scattering properties of RBCs to obtain a quantitative index of aggregate size ( G), which, under idealized conditions, represents the number of RBCs per aggregate. WBC margination, defined as the radial migration of WBCs to the venular wall and their subsequent rolling along the endothelium, was measured as the percentage of the potentially maximal WBC volumetric flux within the microvessel lumen ( F WBC ∗). In normal blood, F WBC ∗ increased exponentially fourfold, and G increased from 1 to 1.15 as wall shear rates (γ˙) were reduced from a steady-state value of ∼600 to <100 s−1 by proximal occlusion with a blunt microprobe. Enhancement of aggregation by infusion (iv) of dextran 500 (428 kDa), to attain a systemic concentration of 3 g/100 ml, resulted in a four- and sevenfold increase in G and F WBC ∗, respectively, as γ˙was reduced below 100 s−1. Inhibition of RBC aggregation by infusion of dextran 40 (37.5 kDa) caused F WBC ∗ to fall to one-half of its steady-state level for γ˙ < 100 s−1. Thus it appears that the well-known increase of WBC margination with reductions in γ˙ is strongly dependent on the occurrence of RBC aggregation. Increasing the extent of RBC aggregation during reductions in γ˙ also increased the firm adhesion of WBCs to the endothelium because of an enhanced probability of contact between leukocytes and the postcapillary venular wall.

Effects of red blood cell aggregation on myocardial hematocrit gradient using two approaches to increase aggregation

2006 ◽  
Vol 290 (2) ◽  
pp. H765-H771 ◽  
Author(s):  
Ozlem Yalcin ◽  
Funda Aydin ◽  
Pinar Ulker ◽  
Mehmet Uyuklu ◽  
Firat Gungor ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Control Level ◽  
Three Dimensional ◽  
Cell Aggregation ◽  
Plasma Viscosity ◽  
Covalent Attachment ◽  
Erythrocyte Aggregation ◽  
Rbc Aggregation ◽  
A New Technique

The normal transmyocardial tissue hematocrit distribution (i.e., subepicardial greater than subendocardial) is known to be affected by red blood cell (RBC) aggregation. Prior studies employing the use of infused large macromolecules to increase erythrocyte aggregation are complicated by both increased plasma viscosity and dilution of plasma. Using a new technique to specifically alter the aggregation behavior by covalent attachment of Pluronic F-98 to the surface of the RBC, we have determined the effects of only enhanced aggregation (i.e., Pluronic F-98-coated RBCs) versus enhanced aggregation with increased plasma viscosity (i.e., an addition of 500 kDa dextran) on myocardial tissue hematocrit in rapidly frozen guinea pig hearts. Although both approaches equally increased aggregation, tissue hematocrit profiles differed markedly: 1) when Pluronic F-98-coated cells were used, the normal transmyocardial gradient was abolished, and 2) when dextran was added, the hematocrit remained at subepicardial levels for about one-half the thickness of the myocardium and then rapidly decreased to the control level in the subendocardial layer. Our results indicate that myocardial hematocrit profiles are sensitive to both RBC aggregation and to changes of plasma viscosity associated with increased RBC aggregation. Furthermore, they suggest the need for additional studies to explore the mechanisms affecting RBC distribution in three-dimensional vascular beds.

Steady-state level of kit ligand mRNA in goat ovaries and the role of kit ligand in preantral follicle survival and growth in vitro

2009 ◽  
Vol 77 (3) ◽  
pp. 231-240 ◽  
Author(s):  
Juliana J.H. Celestino ◽  
Jamily B. Bruno ◽  
Isabel B. Lima-Verde ◽  
Maria Helena T. Matos ◽  
Mércia Viviane A. Saraiva ◽  
...  
Keyword(s):  
Steady State ◽  
State Level ◽  
Steady State Level ◽  
Preantral Follicle ◽  
Kit Ligand ◽  
Survival And Growth

scholarly journals Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Frequency Domain Analysis ◽  
Spectral Slope ◽  
Spectral Parameters ◽  
Oxygen Saturation Level ◽  
Oxygenation Level ◽  
Rbc Aggregation

Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (∼0.3  dB/MHz∼0.3  dB/MHz). The experimental midband fit increased by ∼5  dB∼5  dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20%>20% greater than the nonaggregated sample. The results provide a framework for using PA signals’ spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

scholarly journals Red blood cell (RBC) aggregation and its influence on non-Newtonian nature of blood in microvasculature

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Chitra Murali ◽  
Perumal Nithiarasu
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Aggregation ◽  
Time Dependent ◽  
Shear Rates ◽  
Red Blood Cell Aggregation ◽  
Significant Difference ◽  
Rbc Aggregation ◽  
Rouleaux Formation

AbstractA robust computational model is proposed to investigate the non-Newtonian nature of blood flow due to rouleaux formation in microvasculature. The model consists of appropriate forces responsible for red blood cell (RBC) aggregation in the microvasculature, tracking of RBCs, and coupling between plasma flow and RBCs. The RBC aggregation results have been compared against the available data. The importance of different hydrodynamic forces on red blood cell aggregation has been delineated by comparing the time dependent path of the RBCs. The rheological changes to the blood flow have been investigated under different shear rates and hematocrit values and quantified with and without RBC aggregation. The results obtained in terms of wall shear stress (WSS) and blood viscosity indicate a significant difference between Newtonian and powerlaw fluid assumptions.

scholarly journals Role of STE genes in the mating factor signaling pathway mediated by GPA1 in Saccharomyces cerevisiae.

1988 ◽  
Vol 8 (9) ◽  
pp. 3777-3783 ◽  
Author(s):  
N Nakayama ◽  
Y Kaziro ◽  
K Arai ◽  
K Matsumoto
Keyword(s):  
Steady State ◽  
Signaling Pathway ◽  
State Level ◽  
G1 Arrest ◽  
Gene Products ◽  
Mating Efficiency ◽  
Protein Functions ◽  
Steady State Levels ◽  
Mating Factor

The ste mutants (ste2, ste4, ste5, ste7, ste11, and ste12) are insensitive to mating factors and are, therefore, sterile. Roles of the STE gene products in the GPA1-mediated mating factor signaling pathway were studied by using ste gpa1 double mutants. Mating efficiency of a ste2 mutant defective in the alpha-factor receptor increased 1,000-fold in a gpa1 background, while G1 arrest and aberrant morphology (shmoo) caused by gpa1 were not suppressed by ste2. Furthermore, the steady-state level of the FUS1 transcript, which normally increases in response to mating factors, was also elevated when the GPA1 function was impaired. These results suggest that the GPA1 protein functions downstream of the STE2 receptor. Conversely, the sterility of ste4, ste5, ste7, ste11, and ste12 mutants was not suppressed by gpa1, but the lethal phenotype of gpa1 was suppressed by these ste mutations. Northern (RNA) blotting analysis revealed that the ste7, ste11, and ste12 mutations caused reductions of 50 to 70% in the steady-state levels of the GPA1 transcript, while ste4 had a slight effect and ste5 had no effect. This implies that the suppression by ste7, ste11, and ste12 could be due to reduced syntheses of additional components, including an effector, and that suppression by ste4 and ste5 may result from direct effects on the signaling pathway. The STE4, STE5, STE7, STE11, and STE12 products, therefore, appear to specify components of the signal transduction machinery, directly or indirectly, which function together with or downstream of GPA1.

scholarly journals On the use of photoacoustics to detect red blood cell aggregation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Spectral Power ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Dominant Frequency ◽  
Red Blood Cell Aggregation ◽  
Theoretical Predictions ◽  
Rbc Aggregation ◽  
Simulation Results

The feasibility of detecting red blood cell (RBC) aggregation with photoacoustics (PAs) was investigated theoretically and experimentally using human and porcine RBCs. The theoretical PA signals and spectra generated from such samples were examined for several hematocrit levels and aggregates sizes. The effect of a finite transducer bandwidth on the received PA signal was also examined. The simulation results suggest that the dominant frequency of the PA signals from non-aggregated RBCs decreases towards clinical frequency ranges as the aggregate size increases. The experimentally measured mean spectral power increased by ~6 dB for the largest aggregate compared to the non-aggregated samples. Such results confirm the theoretical predictions and illustrate the potential of using PA imaging for detecting RBC aggregation.

Estimation of aggregate size of red blood cell by introducing reference power spectrum measured for hemispherical ultrafine wire

2021 ◽  
Author(s):  
Kyohei Higashiyama ◽  
Shohei MORI ◽  
Mototaka ARAKAWA ◽  
Satoshi Yashiro ◽  
Yasushi Ishigaki ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Power Spectra ◽  
Aggregate Size ◽  
Posterior Wall ◽  
Size Estimation ◽  
Scattering Spectrum ◽  
Rbc Aggregation

Abstract Noninvasive measurement of the degree of red blood cell (RBC) aggregation is useful for evaluating blood properties. In the present paper, we proposed a method to estimate the size of RBC aggregates without using the power spectrum of the posterior wall by introducing a reference scattering spectrum. The reference power spectra were calculated using the power spectrum measured for an ultrafine wire with a hemispherical tip. They were applied to the size estimation of microparticles simulating RBC aggregates. The estimated sizes were close to the true values, which shows that the calculated reference power spectra were suitable for accurate size estimation. The proposed method was also applied to in vivo measurements, and the estimated sizes between at rest and in RBCs aggregated by avascularization were successfully differentiated. This demonstrates that the proposed method will be useful for estimating the size of RBC aggregates.

scholarly journals A Pathogenic CytochromebMutation Reveals New Interactions between Subunits of the Mitochondrialbc1Complex

2002 ◽  
Vol 277 (51) ◽  
pp. 49397-49402 ◽  
Author(s):  
Yann Saint-Georges ◽  
Nathalie Bonnefoy ◽  
Jean Paul di Rago ◽  
Stephane Chiron ◽  
Geneviève Dujardin
Keyword(s):  
Steady State ◽  
High Temperature ◽  
State Level ◽  
Energy Transduction ◽  
Steady State Level ◽  
Catalytic Subunits ◽  
Suppressor Mutations ◽  
Human Cytochrome ◽  
New Interactions

Energy transduction in mitochondria involves five oligomeric complexes embedded within the inner membrane. They are composed of catalytic and noncatalytic subunits, the role of these latter proteins often being difficult to assign. One of these complexes, thebc1complex, is composed of three catalytic subunits including cytochromeband seven or eight noncatalytic subunits. Recently, several mutations in the human cytochromebgene have been linked to various diseases. We have studied in detail the effects of a cardiomyopathy generating mutationG252Din yeast. This mutation disturbs the biogenesis of thebc1complex at 36 °C and decreases the steady-state level of the noncatalytic subunit Qcr9p. In addition, theG252Dmutation and the deletion ofQCR9show synergetic defects that can be partially bypassed by suppressor mutations at position 252 and by a new cytochromebmutation,P174T. Altogether, our results suggest that the supernumerary subunit Qcr9p enhances or stabilizes the interactions between the catalytic subunits, this role being essential at high temperature.

Nitric oxide generation by endothelial cells exposed to shear stress in glass tubes perfused with red blood cell suspensions: role of aggregation

2008 ◽  
Vol 294 (5) ◽  
pp. H2098-H2105 ◽  
Author(s):  
Ozlem Yalcin ◽  
Pinar Ulker ◽  
Ugur Yavuzer ◽  
Herbert J. Meiselman ◽  
Oguz K. Baskurt
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Vessel Wall ◽  
Plasma Viscosity ◽  
Autologous Plasma ◽  
Rbc Aggregation

Endothelial function is modulated by wall shear stress acting on the vessel wall, which is determined by fluid velocity and the local viscosity near the vessel wall. Red blood cell (RBC) aggregation may affect the local viscosity by favoring axial migration. The aim of this study was to investigate the role of RBC aggregation, with or without altered plasma viscosity, in the mechanically induced nitric oxide (NO)-related mechanisms of endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultured on the inner surface of cylindrical glass capillaries that were perfused with RBC suspensions having normal and increased aggregation at a nominal shear stress of 15 dyn/cm2. RBC aggregation was enhanced by two different approaches: 1) poloxamer-coated RBC suspended in normal, autologous plasma, resulting in enhanced aggregation but unchanged plasma viscosity and 2) normal RBC suspended in autologous plasma containing 0.5% dextran (mol mass 500 kDa), with a similar level of RBC aggregation but higher plasma viscosity. Compared with normal cells in unmodified plasma, perfusion with suspensions of poloxamer-coated RBC in normal plasma resulted in decreased levels of NO metabolites and serine 1177 phosphorylation of endothelial nitric oxide synthase (eNOS). Perfusion with normal RBC in plasma containing dextran resulted in a NO level that remained elevated, whereas only a modest decrease of phosphorylated eNOS level was observed. The results of this study suggest that increases of RBC aggregation tendency affect endothelial cell functions by altering local blood composition, especially if the alterations of RBC aggregation are due to modified cellular properties and not to plasma composition changes.

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