scholarly journals Fibronectin binding to thrombin-stimulated platelets: evidence for fibrin(ogen) independent and dependent pathways

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 26-32
Author(s):  
EF Plow ◽  
GA Marguerie ◽  
MH Ginsberg
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Living Cells ◽  
Plasma Fibronectin ◽  
Divalent Ions ◽  
Fibrinogen Binding ◽  
Calcium Requirement ◽  
Variable Extent ◽  
Fibronectin Binding ◽  
Dependent Pathway

Plasma fibronectin binds in a specific and saturable manner to thrombin- stimulated platelets. gamma-Thrombin stimulated 80% as much fibronectin binding to platelets as alpha-thrombin with conversion of less than or equal to 1% of platelet fibrinogen to fibrin. Afibrinogenemic and normal platelets bound similar quantities of fibronectin in the presence of calcium or magnesium-ethylene glycol tetra-acetic acid (EGTA). These observations indicate that fibronectin can interact with platelets without involvement of fibrin or fibrinogen. Nevertheless, two different effects of fibrin(ogen) on fibronectin binding were observed. First, exogenous fibrinogen inhibited fibronectin binding to thrombin-stimulated platelets. This inhibition was unidirectional, as fibronectin did not inhibit fibrinogen binding to ADP or thrombin- stimulated cells. Second, formaldehyde-fixed cells with surface- associated fibrin bound significant quantities of fibronectin. This interaction required calcium and did not occur on fixed cells with or without surface-bound fibrinogen. A portion of the ligand bound to fixed cells with surface-associated fibrin was modified to form a derivative with a molecular weight identical to that of the fibronectin subunit cross-linked to the alpha-chain of fibrin. This high mol wt derivative was also observed to a variable extent with living cells in the presence of magnesium or calcium but not in the presence of magnesium-EGTA. Thus, fibronectin binds to platelets by at least two mechanisms: (1) a fibrin(ogen)-independent pathway that requires divalent ions and is inhibited by exogenous fibrinogen; and (2) a fibrin-dependent pathway with an absolute calcium requirement. With nonaggregated, thrombin-stimulated platelets, the former pathway appears to predominate.

scholarly journals Fibronectin binding to thrombin-stimulated platelets: evidence for fibrin(ogen) independent and dependent pathways

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 26-32 ◽  
Author(s):  
EF Plow ◽  
GA Marguerie ◽  
MH Ginsberg
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Living Cells ◽  
Plasma Fibronectin ◽  
Divalent Ions ◽  
Fibrinogen Binding ◽  
Calcium Requirement ◽  
Variable Extent ◽  
Fibronectin Binding ◽  
Dependent Pathway

Abstract Plasma fibronectin binds in a specific and saturable manner to thrombin- stimulated platelets. gamma-Thrombin stimulated 80% as much fibronectin binding to platelets as alpha-thrombin with conversion of less than or equal to 1% of platelet fibrinogen to fibrin. Afibrinogenemic and normal platelets bound similar quantities of fibronectin in the presence of calcium or magnesium-ethylene glycol tetra-acetic acid (EGTA). These observations indicate that fibronectin can interact with platelets without involvement of fibrin or fibrinogen. Nevertheless, two different effects of fibrin(ogen) on fibronectin binding were observed. First, exogenous fibrinogen inhibited fibronectin binding to thrombin-stimulated platelets. This inhibition was unidirectional, as fibronectin did not inhibit fibrinogen binding to ADP or thrombin- stimulated cells. Second, formaldehyde-fixed cells with surface- associated fibrin bound significant quantities of fibronectin. This interaction required calcium and did not occur on fixed cells with or without surface-bound fibrinogen. A portion of the ligand bound to fixed cells with surface-associated fibrin was modified to form a derivative with a molecular weight identical to that of the fibronectin subunit cross-linked to the alpha-chain of fibrin. This high mol wt derivative was also observed to a variable extent with living cells in the presence of magnesium or calcium but not in the presence of magnesium-EGTA. Thus, fibronectin binds to platelets by at least two mechanisms: (1) a fibrin(ogen)-independent pathway that requires divalent ions and is inhibited by exogenous fibrinogen; and (2) a fibrin-dependent pathway with an absolute calcium requirement. With nonaggregated, thrombin-stimulated platelets, the former pathway appears to predominate.

scholarly journals Collective regulation of cell motility using an accurate density-sensing system

2018 ◽  
Vol 15 (140) ◽  
pp. 20180006 ◽  
Author(s):  
Joseph d'Alessandro ◽  
Lauriane Mas ◽  
Laurence Aubry ◽  
Jean-Paul Rieu ◽  
Charlotte Rivière ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Living Cells ◽  
Physical Contact ◽  
Persistence Time ◽  
Sensing System ◽  
Physiological Processes ◽  
Extracellular Signal ◽  
Scattered Population ◽  
Dependent Pathway ◽  
Density Threshold

The capacity of living cells to sense their population density and to migrate accordingly is essential for the regulation of many physiological processes. However, the mechanisms used to achieve such functions are poorly known. Here, based on the analysis of multiple trajectories of vegetative Dictyostelium discoideum cells, we investigate such a system extensively. We show that the cells secrete a high-molecular-weight quorum-sensing factor (QSF) in their medium. This extracellular signal induces, in turn, a reduction of the cell movements, in particular, through the downregulation of a mode of motility with high persistence time. This response appears independent of cAMP and involves a G-protein-dependent pathway. Using a mathematical analysis of the cells' response function, we evidence a negative feedback on the QSF secretion, which unveils a powerful generic mechanism for the cells to detect when they exceed a density threshold. Altogether, our results provide a comprehensive and dynamical view of this system enabling cells in a scattered population to adapt their motion to their neighbours without physical contact.

scholarly journals Fibronectin‐Binding Proteins and Fibrinogen‐Binding Clumping Factors Play Distinct Roles in Staphylococcal Arthritis and Systemic Inflammation

2005 ◽  
Vol 191 (5) ◽  
pp. 791-798 ◽  
Author(s):  
Niklas Palmqvist ◽  
Timothy Foster ◽  
J. Ross Fitzgerald ◽  
Elisabet Josefsson ◽  
Andrzej Tarkowski
Keyword(s):  
Systemic Inflammation ◽  
Binding Proteins ◽  
Fibrinogen Binding ◽  
Fibronectin Binding

Ruthenium Recovery from Acetic Acid Waste Solution by Using PEI-Coated Biomass-Chitosan Composite Fiber

2015 ◽  
Vol 1130 ◽  
pp. 577-580 ◽  
Author(s):  
Jeong Ae Kim ◽  
Myung Hee Song ◽  
Yeoung Sang Yun
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Freeze Drying ◽  
Ion Exchange Resin ◽  
Composite Fiber ◽  
Drying Methods ◽  
Drying Method ◽  
Waste Solution ◽  
Chitosan Composite ◽  
Acid Waste

Polyethylenimine (PEI)-coated biomass-chitosan composite fiber (PBCF) was fabricated to recover Ru from acetic acid waste solution. The present work aimed to understand the effects of molecular weight of chitosan and drying method on stability and sorption performance of the PBCF. For this, the PBCF was prepared by extruding the mixed solutions of chitosan and Corynebacteriumglutamicum to form the composite fibers which were modified with ionic polymer, PEI. The degree of swelling of PBCFs prepared by hot-air, natural, and freeze drying methods were 1.25, 1.34, and 1.07 %, respectively, indicating that the freeze-drying method was the best. Batch biosorption studies showed that the maximum Ru uptake could be achieved with PBCF prepared with medium molecular weight chitosan, and could reach 34.1 mg/g, which was 7.9 times higher than that of the commercial ion exchange resin, LEWATIT® MonoPlus M 500 (4.3 mg/g). Therefore, PBCF can be considered as an alternative sorbent to synthetic resin for recovery of Ru form industrial acetic acid waste solution.

Instabilities in the System NMMO/Water/Cellulose (Lyocell Process) Caused by Polonowski Type Reactions

Holzforschung ◽  
2002 ◽  
Vol 56 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Thomas Rosenau ◽  
Antje Potthast ◽  
Andreas Hofinger ◽  
Herbert Sixta ◽  
Paul Kosma
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Exchange Resin ◽  
Degradation Products ◽  
Ion Exchange Resin ◽  
Low Molecular Weight ◽  
Acid Component ◽  
Degradation Reactions ◽  
Polyglucuronic Acid

Summary Polonowski type degradation reactions are a major reason for the frequently observed instability of solutions of cellulose in N-methylmorpholine-N-oxide monohydrate (NMMO, 1). The degradation is induced by degradation products of cellulose and NMMO generated in situ in the Lyocell system. The presence of both an amine component, such as morpholine or N-methylmorpholine, and an acid component is required for the decomposition process to proceed. The latter might be a low-molecular-weight compound, such as formic acid, acetic acid or gluconic acid, or also a high-molecular-weight acid, such as polyglucuronic acid or ion exchange resin.

scholarly journals Steric stabilization of nanoparticles with grafted low molecular weight ligands in highly concentrated brines including divalent ions

Soft Matter ◽  
2016 ◽  
Vol 12 (7) ◽  
pp. 2025-2039 ◽  
Author(s):  
Andrew J. Worthen ◽  
Vu Tran ◽  
Kevin A. Cornell ◽  
Thomas M. Truskett ◽  
Keith P. Johnston
Keyword(s):  
Molecular Weight ◽  
Environmental Science ◽  
Oil And Gas ◽  
Biological Fluids ◽  
Steric Stabilization ◽  
Low Molecular Weight ◽  
Divalent Ions ◽  
Gas Reservoirs ◽  
Oil And Gas Reservoirs

Whereas numerous studies of stabilization of nanoparticles (NPs) in electrolytes have examined biological fluids, the interest has grown recently in media with much higher ionic strengths including seawater and brines relevant to environmental science and subsurface oil and gas reservoirs.

γ-Ray Irradiation Practical Conditions for Low Molecular Weight Chitosan Material Production

2003 ◽  
Vol 792 ◽  
Author(s):  
Rangrong Yoksan ◽  
Mitsuru Akashi ◽  
Mikiji Miyata ◽  
Siriratana Biramontri ◽  
Suwabun Chirachanchai
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Solid State ◽  
Primary Structure ◽  
Low Molecular Weight ◽  
Aqueous Acetic Acid ◽  
Low Molecular Weight Chitosan ◽  
Backbone Structure ◽  
Γ Ray ◽  
Terminal Chain

ABSTRACTThe present work focuses on the γ-ray irradiation doses and conditions (dry solid state, solid state dispersing in 0.5–2 % aqueous H2O2 solution, solid state dispersing in 1% aqueous acetic acid, and 2% aqueous K2S2O8) to determine the level that the molecular weight of chitosan is lowered significantly without changing its primary structure. Molecular weight of chitosan (105-106 Dalton) is reduced approximately 50% under the γ-ray dose of 20 kGy in the dry solid state. The decrease in molecular weight is enhanced up to 80% when chitosan is suspended in 0.5–2 % aqueous H2O2 solution during γ-ray irradiation. In either condition, the backbone structure of the irradiated product is maintained with little change in the terminal chain. In the cases of (i) chitosan suspended in 2% aqueous K2S2O8 and (ii) chitosan in 1% aqueous acetic acid, chitosans lose their primary structures and physical properties.

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