scholarly journals Effects of Platelet Agonists and Priming on the Formation of Platelet Populations

2021 ◽  
Author(s):  
Alicia Veninga ◽  
Constance C. F. M. J. Baaten ◽  
Ilaria De Simone ◽  
Bibian M. E. Tullemans ◽  
Marijke J. E. Kuijpers ◽  
...  
Keyword(s):  
Clustering Analysis ◽  
State Of The Art ◽  
Bioactive Molecules ◽  
Dense Granules ◽  
Flow Cytometric ◽  
Activated Platelets ◽  
Healthy Donors ◽  
Response Thresholds ◽  
Dose Dependent ◽  
Circulating Levels

AbstractPlatelets from healthy donors display heterogeneity in responsiveness to agonists. The response thresholds of platelets are controlled by multiple bioactive molecules, acting as negatively or positively priming substances. Higher circulating levels of priming substances adenosine and succinate, as well as the occurrence of hypercoagulability, have been described for patients with ischaemic heart disease. Here, we present an improved methodology of flow cytometric analyses of platelet activation and the characterisation of platelet populations following activation and priming by automated clustering analysis.Platelets were treated with adenosine, succinate, or coagulated plasma before stimulation with CRP-XL, 2-MeSADP, or TRAP6 and labelled for activated integrin αIIbβ3 (PAC1), CD62P, TLT1, CD63, and GPIX. The Super-Enhanced Dmax subtraction algorithm and 2% marker (quadrant) setting were applied to identify populations, which were further defined by state-of-the-art clustering techniques (tSNE, FlowSOM).Following activation, five platelet populations were identified: resting, aggregating (PAC1 + ), secreting (α- and dense-granules; CD62P + , TLT1 + , CD63 + ), aggregating plus α-granule secreting (PAC1 + , CD62P + , TLT1 + ), and fully active platelet populations. The type of agonist determined the distribution of platelet populations. Adenosine in a dose-dependent way suppressed the fraction of fully activated platelets (TRAP6 > 2-MeSADP > CRP-XL), whereas succinate and coagulated plasma increased this fraction (CRP-XL > TRAP6 > 2-MeSADP). Interestingly, a subset of platelets showed a constant response (aggregating, secreting, or aggregating plus α-granule secreting), which was hardly affected by the stimulus strength or priming substances.

Flow cytometric quantitation and characterization of the T-lymphocyte memory response to CMV in healthy donors

Cytotherapy ◽  
2002 ◽  
Vol 4 (1) ◽  
pp. 29-40 ◽  
Author(s):  
N. Hensel ◽  
J.J. Melenhorst ◽  
K. Bradstock ◽  
A.P. Schwarer ◽  
R. Eniafe ◽  
...  
Keyword(s):  
T Lymphocyte ◽  
Memory Response ◽  
Flow Cytometric ◽  
Healthy Donors

Strategies for EELS Data Analysis. Introducing UMAP and HDBSCAN for Dimensionality Reduction and Clustering

2021 ◽  
pp. 1-14
Author(s):  
Javier Blanco-Portals ◽  
Francesca Peiró ◽  
Sònia Estradé
Keyword(s):  
Dimensionality Reduction ◽  
Clustering Analysis ◽  
Manganese Oxides ◽  
Spatial Clustering ◽  
State Of The Art ◽  
Core Loss ◽  
Nonnegative Matrix ◽  
Case Scenario ◽  
Electron Energy Loss ◽  
Iron And Manganese

Hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and uniform manifold approximation and projection (UMAP), two new state-of-the-art algorithms for clustering analysis, and dimensionality reduction, respectively, are proposed for the segmentation of core-loss electron energy loss spectroscopy (EELS) spectrum images. The performances of UMAP and HDBSCAN are systematically compared to the other clustering analysis approaches used in EELS in the literature using a known synthetic dataset. Better results are found for these new approaches. Furthermore, UMAP and HDBSCAN are showcased in a real experimental dataset from a core–shell nanoparticle of iron and manganese oxides, as well as the triple combination nonnegative matrix factorization–UMAP–HDBSCAN. The results obtained indicate how the complementary use of different combinations may be beneficial in a real-case scenario to attain a complete picture, as different algorithms highlight different aspects of the dataset studied.

Extracellular fibrinogen binding protein, Efb, from Staphylococcus aureus binds to platelets and inhibits platelet aggregation

2004 ◽  
Vol 91 (04) ◽  
pp. 779-789 ◽  
Author(s):  
Oonagh Shannon ◽  
Jan-Ingmar Flock
Keyword(s):  
Platelet Aggregation ◽  
Potent Inhibitor ◽  
Specific Binding ◽  
Binding Protein ◽  
Dependent Manner ◽  
Platelet Surface ◽  
Putative Receptor ◽  
Activated Platelets ◽  
Fibrinogen Binding ◽  
Dose Dependent

Summary S. aureus produces and secretes a protein, extracellular fibrinogen binding protein (Efb), which contributes to virulence in wound infection. We have shown here that Efb is a potent inhibitor of platelet aggregation. Efb can bind specifically to platelets by two mechanisms; 1) to fibrinogen naturally bound to the surface of activated platelets and 2) also directly to a surface localized component on the platelets. This latter binding of Efb is independent of fibrinogen. The specific binding of Efb to the putative receptor on the platelet surface results in a stimulated, non-functional binding of fibrinogen in a dose dependent manner, distinct from natural binding of fibrinogen to platelets. The natural binding of fibrinogen to GPIIb/IIIa on activated platelets could be blocked by a monoclonal antibody against this integrin, whereas the Efb-mediated fibrinogen binding could not be blocked. The enhanced Efb-dependent fibrinogen binding to platelets is of a nature that does not promote aggregation of the platelets; instead it inhibits aggregation. The anti-thrombotic action of Efb may explain the effect of Efb on wound healing, which is delayed in the presence of Efb.

Reticulated Platelets: Changing Focus from Basics to Outcomes

2018 ◽  
Vol 118 (09) ◽  
pp. 1517-1527 ◽  
Author(s):  
Bashar Hannawi ◽  
Yousef Hannawi ◽  
Neal Kleiman
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Essential Role ◽  
State Of The Art ◽  
Specific Marker ◽  
Messenger Ribonucleic Acid ◽  
Coronary Syndrome ◽  
Reticulated Platelets ◽  
Artery Disease ◽  
Circulating Levels

AbstractPlatelets play an essential role in the pathophysiology of atherothrombosis. Reticulated platelets (RPs) are the youngest platelet population in the circulation; their presence is an indicator of platelet turnover. Circulating levels of RPs are increased in patients with coronary artery disease and stroke. Preliminary indications are that the proportion of circulating RP is associated with the likelihood of ischaemic events such as acute coronary syndrome and stroke. Plausible mechanisms include: (1) increased participation of these platelets in thrombosis due to messenger ribonucleic acid that may be translated to active proteins, (2) lack of exposure to anti-platelet drugs since they are newly released from the bone marrow or (3) their presence is a non-specific marker of inflammation. In this state-of-the-art review, we discuss the implication of RP in coronary artery disease and in hypo-responsiveness to the most commonly used anti-platelet drugs.

Role of the cytoskeleton in rapid activation of CD11b/CD18 function and its subsequent downregulation in neutrophils

2000 ◽  
Vol 113 (15) ◽  
pp. 2737-2745
Author(s):  
S.I. Anderson ◽  
N.A. Hotchin ◽  
G.B. Nash
Keyword(s):  
Cytochalasin D ◽  
Calpain Inhibitor ◽  
Cytoskeletal Rearrangement ◽  
Activated Platelets ◽  
Binding Inhibition ◽  
Formyl Peptide ◽  
Intracellular Ca ◽  
Rapid Activation ◽  
Dose Dependent

When rolling adherent neutrophils are stimulated, they rapidly immobilize through activation of integrin CD11b/CD18, and then modulate attachment through this integrin to allow migration. We investigated links between cytoskeletal rearrangement and changes in function of integrin CD11b/CD18 in neutrophils stimulated with formyl peptide (fMLP). Neutrophils treated with the actin-polymerizing agent jasplakinolide became rolling adherent on monolayers of activated platelets, but could not use CD11b/CD18 to become immobilised when fMLP was perfused over them. If treated with jasplakinolide after fMLP, the cells stopped migrating but could not detach when fMLP was removed. Jasplakinolide did not inhibit changes in intracellular Ca(2+) seen after fMLP treatment, or inhibit neutrophil immobilisation induced by externally added Mn(2+). Thus cytoskeletal rearrangement was directly implicated in upregulation and, later, downregulation of CD11b/CD18 binding. Inhibition of RhoA with C3-transferase caused a dose-dependent reduction of initial rolling adhesion of neutrophils, and reduced the rate of migration after stimulation; however, neither the conversion of rolling to stationary adhesion, nor the ability of neutrophils to detach on removal of the stimulus, were inhibited. Thus, Rho may regulate actin polymerisation and motility in neutrophils, but did not appear to control integrin-mediated adhesion itself. Integrin binding may be promoted by disruption of links to the cytoskeleton, effected through depolymerisation of actin or cleavage of linking protein talin by calpain. Disruption of actin filaments with cytochalasin D did not, however, cause integrin-mediated immobilisation of rolling neutrophils. Although the calpain inhibitor calpeptin did inhibit the adhesion response to fMLP, this was only at doses where actin polymerisation was also ablated. We suggest that the cytoskeleton actively regulates binding conformation of CD11b/CD18 as well as its mobility in the membrane.

Cytotoxic effects of cisplatin, cis-dichlorodiammineplatinum(II), on Tetrahymena

1988 ◽  
Vol 90 (4) ◽  
pp. 707-716
Author(s):  
J.R. Nilsson
Keyword(s):  
Mitochondrial Membrane ◽  
Prolonged Treatment ◽  
Dependent Manner ◽  
Inner Mitochondrial Membrane ◽  
Cell Organelles ◽  
Cell Content ◽  
Cytotoxic Effects ◽  
Dense Granules ◽  
High Concentrations ◽  
Dose Dependent

A study was made of the effects of cisplatin, cis-dichlorodiammineplatinum(II) (5–250 mg l-1), on the physiology and fine structure of Tetrahymena. The physiological effects observed were dose-dependent. Endocytosis was inhibited reversibly in all, but late in the high, concentrations. After an initial dose-related increase, due to division of cells most advanced in the cell cycle, proliferation ceased for at least two normal cell generations (6 h) in 50 and 100 mg drug l-1, but for 24 h in 250 mg l-1, after which multiplication was resumed in a dose-dependent manner. Exposure to cisplatin resulted in the appearance of small, refractive granules and platinum (i.e. electron-dense material) accumulated in these granules. Fine structural observations of cells exposed to 250 mg drug l-1 showed nucleolar fusion and appearance initially of lipid droplets, dense granules and autophagosomes. A time-dependent redistribution of cell organelles was revealed by morphometry; in particular, the mitochondria increased in number, but decreased in size. Moreover, after prolonged treatment (24 h) and without cell division, the inner mitochondrial membrane had diminished and the ratio of the inner to the outer mitochondrial membrane was only half of the value for control mitochondria. Concomitantly with this decrease, the cell content of ATP was reduced to a similar extent. The findings indicate a specific action of cisplatin on mitochondria, resembling that induced in Tetrahymena by chloramphenicol and methotrexate.

Dose-Dependent Effect of 17β-Estradiol Determined by Growth Curves and Flow Cytometric DNA Analysis of a Human Breast Carcinoma (T61) Grown in Nude Mice

Pathobiology ◽  
1985 ◽  
Vol 53 (4) ◽  
pp. 220-232 ◽  
Author(s):  
N. Brünner ◽  
M. Spang-Thomsen ◽  
L. Vindeløv ◽  
A. Nielsen ◽  
S.A. Engelholm ◽  
...  
Keyword(s):  
Breast Carcinoma ◽  
Nude Mice ◽  
Dna Analysis ◽  
Growth Curves ◽  
Human Breast Carcinoma ◽  
Human Breast ◽  
Dependent Effect ◽  
Flow Cytometric ◽  
Dose Dependent ◽  
Dose Dependent Effect

scholarly journals Hyperinsulinemia, But Not Other Factors Associated with Insulin Resistance, Acutely Enhances Colorectal Epithelial Proliferation in Vivo

Endocrinology ◽  
2006 ◽  
Vol 147 (4) ◽  
pp. 1830-1837 ◽  
Author(s):  
Thien T. Tran ◽  
Dinaz Naigamwalla ◽  
Andrei I. Oprescu ◽  
Loretta Lam ◽  
Gail McKeown-Eyssen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Epithelial Cells ◽  
Dependent Manner ◽  
Epithelial Proliferation ◽  
Euglycemic Clamp ◽  
The Individual ◽  
Dose Dependent ◽  
Circulating Levels

The similarity in risk factors for insulin resistance and colorectal cancer (CRC) led to the hypothesis that markers of insulin resistance, such as elevated circulating levels of insulin, glucose, fatty acids, and triglycerides, are energy sources and growth factors in the development of CRC. The objective was thus to examine the individual and combined effects of these circulating factors on colorectal epithelial proliferation in vivo. Rats were fasted overnight, randomized to six groups, infused iv with insulin, glucose, and/or Intralipid for 10 h, and assessed for 5-bromo-2-deoxyuridine labeling of replicating DNA in colorectal epithelial cells. Intravenous infusion of insulin, during a 10-h euglycemic clamp, increased colorectal epithelial proliferation in a dose-dependent manner. The addition of hyperglycemia to hyperinsulinemia did not further increase proliferation. Intralipid infusion alone did not affect proliferation; however, the combination of insulin, glucose, and Intralipid infusion resulted in greater hyperinsulinemia than the infusion of insulin alone and further increased proliferation. Insulin infusion during a 10-h euglycemic clamp decreased total IGF-I levels and did not affect insulin sensitivity. These results provide evidence for an acute role of insulin, at levels observed in insulin resistance, in the proliferation of colorectal epithelial cells in vivo.

Interaction of Thrombin-Stimulated Platelets with Vitronectin (S-Protein of Complement) Substrate: Inhibition by a Monoclonal Antibody to Glycoprotein IIb-IIIa Complex

1988 ◽  
Vol 60 (03) ◽  
pp. 514-517 ◽  
Author(s):  
Perumal Thiagarajan ◽  
Kathleen Kelly
Keyword(s):  
Synthetic Peptides ◽  
Vessel Wall ◽  
Divalent Cations ◽  
Substrate Inhibition ◽  
Adhesion Assay ◽  
Dependent Manner ◽  
Activated Platelets ◽  
Subendothelial Matrix ◽  
Dose Dependent ◽  
Adhesion Of Platelets

SummaryPlatelets adhere to vitronectin substrate following activation with physiological concentrations of thrombin. Adhesion of activated platelets to vitronectin substrate is dependent upon the presence of divalent cations, the amount of vitronectin, and the duration of adhesion assay. The adhesion of platelets is inhibited by synthetic peptides containing the sequence of Arg-Gly-Asp. In addition, monoclonal antibodies to glycoprotein IIb-IIIa complex inhibit the adhesion of activated platelets to vitronectin substrate in a dose-dependent manner. These studies suggest that the glycoprotein IIb-IIIa complex on activated platelets may interact with vitronectin substrate through the Arg-Gly-Asp mechanism. Since vitronectin is present in the subendothelial matrix, it might be involved in platelet-vessel wall interactions

Salidroside Inhibits Endogenous Hydrogen Peroxide Induced Cytotoxicity of Endothelial Cells

2013 ◽  
Vol 750-752 ◽  
pp. 1529-1532 ◽  
Author(s):  
Xing Yu Zhao ◽  
Lian Hai Jin ◽  
Dong Jun Wang ◽  
Bin Xu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Endothelial Cells ◽  
Glucose Oxidase ◽  
Flow Cytometric Analysis ◽  
Steady States ◽  
Protective Effects ◽  
Human Endothelial Cells ◽  
Flow Cytometric ◽  
Dose Dependent ◽  
Mtt Assays

To explore the protective effects of salidroside against endogenous hydrogen peroxide (H2O2) -induced cytotoxicity in human endothelial cells (EVC-304). EVC-304 cells were incubated in the presence or absence of low steady states of H2O2 (34μM) generated by glucose oxidase (GOX) with or without salidroside. MTT assays were performed, together with flow cytometric analysis using propidium (PI) label. The results indicated that salidroside could attenuate H2O2 induced cytotoxicity in EVC-304 cells in a dose-dependent pattern. Furthermore, flow cytometric analysis revealed that salidroside could also inhibited the G2/M arrest induced by endogenous hydrogen. The present study demonstrates that salidroside could inhibit endogenous hydrogen peroxide induced cytotoxicity of endothelial cells .

Sign in / Sign up

Export Citation Format

Share Document