Interaction of platelets with liposomes containing dodecapeptide sequence from fibrinogen

2004 ◽  
Vol 91 (06) ◽  
pp. 1158-1167 ◽  
Author(s):  
Chikaho Toma ◽  
Takako Nishiya
Keyword(s):  
Platelet Aggregation ◽  
Binding Site ◽  
Synthetic Peptide ◽  
Surface Density ◽  
The Other ◽  
Interaction Site ◽  
Ligand Affinity ◽  
Rgd Sequence ◽  
Activated Platelets ◽  
Other Hand

SummaryLiposomes with a covalently bound synthetic peptide containing the dodecapeptide sequence HHLGGAKQAGDV, the putative platelet interaction site at γ400-411 of fibrinogen (dodecapeptide-liposomes), were prepared. These liposomes enhanced platelet aggregation and specifically adhered to platelets activated on the collagen surface. Dodecapeptide-liposomes released encapsulated materials upon interacting with platelets activated on the collagen surface.The rate of content release was dependent on the peptide surface density, indicating that the interaction between the dodecapeptide-liposomes and platelets activated on the collagen surface induces clustering of the surfacecoupled ligands at the binding site on the receptor matrix to facilitate release of the internal contents through the liposome membranes. The level of lipid mixing between the dodecapeptide-liposomes and platelets activated on the collagen surface was relatively low, however it was increased in liposome preparations containing octa-arginine, the (R)8GDV sequence, while content release was maintained at the same level as that of the dodecapeptide-liposomes. The level of content release and lipid mixing for liposome preparations containing the RGD sequence as a ligand (RGD-liposomes) upon interacting with platelets activated on the collagen surface was extremely low. Both the level of the content release and lipid mixing, however, were enhanced in liposome preparations containing octa-arginine, the (R)8RGD sequence. Dodecapeptide-liposomes and RGD-liposomes were not internalized by activated platelets. On the other hand, liposomes containing (R)8PPQ, (R)8RGD, or (R)8GDV were internalized by activated platelets, and the extent of internalization was inversely related to ligand affinity to the target.

A Comparison of the Effect of Decorsin and Two Disintegrins, Albolabrin and Eristostatin, on Platelet Function

1995 ◽  
Vol 74 (05) ◽  
pp. 1316-1322 ◽  
Author(s):  
Mary Ann McLane ◽  
Jagadeesh Gabbeta ◽  
A Koneti Rao ◽  
Lucia Beviglia ◽  
Robert A Lazarus ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Sequence Similarity ◽  
Platelet Aggregation Inhibitors ◽  
Antiplatelet Drug ◽  
Rgd Sequence ◽  
Fibrinogen Receptor ◽  
Activated Platelets

SummaryNaturally-occurring fibrinogen receptor antagonists and platelet aggregation inhibitors that are found in snake venom (disintegrins) and leeches share many common features, including an RGD sequence, high cysteine content, and low molecular weight. There are, however, significant selectivity and potency differences. We compared the effect of three proteins on platelet function: albolabrin, a 7.5 kDa disintegrin, eristostatin, a 5.4 kDa disintegrin in which part of the disintegrin domain is deleted, and decorsin, a 4.5 kDa non-disintegrin derived from the leech Macrobdella decora, which has very little sequence similarity with either disintegrin. Decorsin was about two times less potent than albolabrin and six times less potent than eristostatin in inhibiting ADP- induced human platelet aggregation. It had a different pattern of interaction with glycoprotein IIb/IIIa as compared to the two disintegrins. Decorsin bound with a low affinity to resting platelets (409 nM) and to ADP-activated platelets (270 nM), and with high affinity to thrombin- activated platelets (74 nM). At concentrations up to 685 nM, it did not cause expression of a ligand-induced binding site epitope on the (β3 subunit of the GPIIb/IIIa complex. It did not significantly inhibit isolated GPIIb/IIIa binding to immobilized von Willebrand Factor. At low doses (1.5-3.0 μg/mouse), decorsin protected mice against death from pulmonary thromboembolism, showing an effect similar to eristostatin. This suggested that decorsin is a much more potent inhibitor of platelet aggregation in vivo than in vitro, and it may have potential as an antiplatelet drug.

scholarly journals Decreased ligand affinity rather than glucocorticoid receptor down-regulation in patients with endogenous Cushing's syndrome

2000 ◽  
pp. 472-476 ◽  
Author(s):  
NA Huizenga ◽  
WW De Herder ◽  
JW Koper ◽  
P de Lange ◽  
D AJ v Lely ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Cushing’S Syndrome ◽  
Cushing's Syndrome ◽  
The Body ◽  
The Other ◽  
Down Regulation ◽  
Ligand Affinity ◽  
Other Hand ◽  
Receptor Number ◽  
Cortisol Levels

OBJECTIVE: Glucocorticoids (GCs) serve a variety of important functions throughout the body. The synthesis and secretion of GCs are under the strict influence of the hypothalamo-pituitary-adrenal axis. The mechanisms of action of GCs are mediated by the intracellular glucocorticoid receptor (GR). Over the years, many studies have been performed concerning the regulation of GR expression by GC concentrations. METHODS: In the present study, we determined the characteristics of the GR in peripheral mononuclear blood leukocytes (PBML) from thirteen patients with endogenous Cushing's syndrome and fifteen control subjects, using a whole cell dexamethasone binding assay. Furthermore, cortisol concentrations were determined in order to investigate a possible relationship between serum cortisol levels and receptor characteristics. RESULTS: There were no differences in mean receptor number between patients and controls. On the other hand, a significantly lower ligand affinity was identified in cells from patients with Cushing's syndrome compared with controls. A complete normalisation of the ligand affinity was observed after treatment in the only patient tested in this respect, whereas the receptor number was not affected. In patients, there was a statistically significant negative correlation between cortisol concentrations and ligand affinity, which was not found in controls. CONCLUSION: Receptor down-regulation does not occur in PBML from patients with endogenous Cushing's syndrome. On the other hand, there seems to be a diminished ligand affinity which possibly reflects receptor modification in response to exposure to the continuously high cortisol levels in patients with Cushing's syndrome. This assumption is substantiated by the fact that in one patient a normalisation of the ligand affinity after complete remission of the disease was seen.

scholarly journals The C-terminal sequences of the gamma 57.5 chain of human fibrinogen constitute a plasmin sensitive epitope that is exposed in crosslinked fibrin

Blood ◽  
1989 ◽  
Vol 74 (7) ◽  
pp. 2437-2444
Author(s):  
PJ Haidaris ◽  
EI Peerschke ◽  
VJ Marder ◽  
CW Francis
Keyword(s):  
Platelet Aggregation ◽  
Binding Site ◽  
Synthetic Peptide ◽  
Synthetic Peptides ◽  
Competitive Inhibition ◽  
Plasma Fibrinogen ◽  
Enzyme Linked Immunosorbent Assay ◽  
Post Translational Modification ◽  
Gamma Chain ◽  
Human Fibrinogen

The gamma chain of human plasma fibrinogen is heterogeneous with three forms differing in length at the C-terminus. Alternative RNA splicing produces two gamma chain mRNAs encoding gamma 50 and gamma 57.5 polypeptides, while fibrinogen gamma 55 is produced by post- translational modification of the gamma 57.5 chain. The composition of purified variant gamma chain fibrinogens, which comprise 10% to 13% total plasma fibrinogen, is predominantly heterodimeric (A alpha, B beta, gamma 50/gamma 55 or A alpha, B beta, gamma 50/gamma 57.5), whereas the composition of purified fibrinogen with the major form of the gamma chain is homodimeric (A alpha, B beta, gamma 50/gamma 50). These gamma chain variations interrupt sequences that mediate platelet- fibrinogen interactions. Therefore, the structure and function of gamma 57.5 C-terminal sequences were investigated using synthetic peptides and a specific monoclonal antibody (MoAb), L2B. The L2B epitope was localized and included gamma 57.5 chain residues 409–412 (Arg-Pro-Glu- His), as determined by differential enzyme-linked immunosorbent assay (ELISA) reactivity with a His-412 deleted synthetic peptide and by Western blot analysis of plasmin cleaved fibrinogen gamma 57.5. L2B had no effect on adenosine diphosphate (ADP)-induced platelet aggregation supported by either fibrinogen gamma 50 or gamma 57.5. High concentrations (0.5 to 1 mmol/L) of synthetic peptide gamma 57.5 405– 416 only weakly inhibited ADP-induced platelet aggregation supported by either fibrinogen gamma 50 or gamma 57.5. Binding of fibrinogen gamma 50 (IC50 = 780 mumol/L) or gamma 57.5 (IC50 = 650 mumol/L) to ADP- stimulated platelets was weakly inhibited, and MoAb L2B failed to inhibit fibrinogen gamma 57.5 binding. Peptide gamma 57.5 408–416 failed to dissociate platelet-bound fibrinogens. These data indicate that the gamma 408–416 sequence of fibrinogen gamma 55 or gamma 57.5 alone is unlikely to bind to the platelet fibrinogen receptor, glycoprotein llb-llla (GPllb-llla), in support of platelet aggregation under physiologic conditions. The sequence recognized by L2B does not resemble known GPllb-llla binding site peptide sequences [Arg-Gly-Asp- Ser (RGDS) or gamma 50 400–411] as determined by competitive inhibition ELISA comparing these binding site synthetic peptides with gamma 57.5 408–416. This epitope is available for binding MoAb L2B in gamma 55 or gamma 57.5 chain dimers and binds to all gamma 57.5 408–416 epitopes equally in non-crosslinked and factor Xllla crosslinked fibrin clots.(ABSTRACT TRUNCATED AT 400 WORDS).

Specific Inhibition of Platelet Agglutination and Aggregation by Aromatic Amidino Compounds

1978 ◽  
Vol 39 (02) ◽  
pp. 411-425 ◽  
Author(s):  
J D Geratz ◽  
R R Tidwell ◽  
K M Brinkhous ◽  
S F Mohammad ◽  
O Dann ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Human Plasma ◽  
Inhibitory Effect ◽  
The Other ◽  
Specific Inhibition ◽  
Test Systems ◽  
Other Hand ◽  
Bovine Plasma ◽  
Inhibitory Activities ◽  
High Concentrations

SummaryA series of aromatic amidino compounds were investigated for their inhibitory effect on platelet agglutination and platelet aggregation. Agglutination of fresh or fixed platelets was produced by bovine plasma or by human plasma in combination with ristocetin, while aggregation of fresh platelets was induced by ADP, thrombin or collagen. Highly effective inhibitors were found for both types of platelet clumping, but there was no parallelism between the inhibitory activities in the two test systems. 5-(5-amidino-2-benzimidazolyl)-2-(4-hydroxyben-zene)benzimidazole suppressed agglutination exclusively. Pentamidine, on the other hand, strongly blocked the aggregation reactions, but did not interfere with agglutination, even at high concentrations. Compounds which inhibited aggregation also prevented the liberation of serotonin from the platelets.

Potentiating Effect of Adenosine on Other Inhibitors of Platelet Aggregation

1972 ◽  
Vol 27 (02) ◽  
pp. 252-262 ◽  
Author(s):  
M. Murakami ◽  
K. Odake ◽  
M. Takase ◽  
K. Yoshino
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Prostaglandin E1 ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
The Other ◽  
Other Hand ◽  
Adp Release

SummaryAdenosine was rapidly incorporated into human platelets, and the inhibitory effect of adenosine on platelet aggregation was correlated with the incorporation process. Adenosine potentiated the inhibitory action of other inhibitors, such as dipyridamole, prostaglandin E1 and Y-3642. The inhibition of aggregation was associated with the preservation of platelet adenine nucleotides and the prevention of ADP release. On the other hand, the radioactive adenine nucleotide pattern of platelets was not substantially affected by inhibitors. The relation of inhibition of aggregation with ADP release was discussed.

scholarly journals The C-terminal sequences of the gamma 57.5 chain of human fibrinogen constitute a plasmin sensitive epitope that is exposed in crosslinked fibrin

Blood ◽  
1989 ◽  
Vol 74 (7) ◽  
pp. 2437-2444 ◽  
Author(s):  
PJ Haidaris ◽  
EI Peerschke ◽  
VJ Marder ◽  
CW Francis
Keyword(s):  
Platelet Aggregation ◽  
Binding Site ◽  
Synthetic Peptide ◽  
Synthetic Peptides ◽  
Competitive Inhibition ◽  
Plasma Fibrinogen ◽  
Enzyme Linked Immunosorbent Assay ◽  
Post Translational Modification ◽  
Gamma Chain ◽  
Human Fibrinogen

Abstract The gamma chain of human plasma fibrinogen is heterogeneous with three forms differing in length at the C-terminus. Alternative RNA splicing produces two gamma chain mRNAs encoding gamma 50 and gamma 57.5 polypeptides, while fibrinogen gamma 55 is produced by post- translational modification of the gamma 57.5 chain. The composition of purified variant gamma chain fibrinogens, which comprise 10% to 13% total plasma fibrinogen, is predominantly heterodimeric (A alpha, B beta, gamma 50/gamma 55 or A alpha, B beta, gamma 50/gamma 57.5), whereas the composition of purified fibrinogen with the major form of the gamma chain is homodimeric (A alpha, B beta, gamma 50/gamma 50). These gamma chain variations interrupt sequences that mediate platelet- fibrinogen interactions. Therefore, the structure and function of gamma 57.5 C-terminal sequences were investigated using synthetic peptides and a specific monoclonal antibody (MoAb), L2B. The L2B epitope was localized and included gamma 57.5 chain residues 409–412 (Arg-Pro-Glu- His), as determined by differential enzyme-linked immunosorbent assay (ELISA) reactivity with a His-412 deleted synthetic peptide and by Western blot analysis of plasmin cleaved fibrinogen gamma 57.5. L2B had no effect on adenosine diphosphate (ADP)-induced platelet aggregation supported by either fibrinogen gamma 50 or gamma 57.5. High concentrations (0.5 to 1 mmol/L) of synthetic peptide gamma 57.5 405– 416 only weakly inhibited ADP-induced platelet aggregation supported by either fibrinogen gamma 50 or gamma 57.5. Binding of fibrinogen gamma 50 (IC50 = 780 mumol/L) or gamma 57.5 (IC50 = 650 mumol/L) to ADP- stimulated platelets was weakly inhibited, and MoAb L2B failed to inhibit fibrinogen gamma 57.5 binding. Peptide gamma 57.5 408–416 failed to dissociate platelet-bound fibrinogens. These data indicate that the gamma 408–416 sequence of fibrinogen gamma 55 or gamma 57.5 alone is unlikely to bind to the platelet fibrinogen receptor, glycoprotein llb-llla (GPllb-llla), in support of platelet aggregation under physiologic conditions. The sequence recognized by L2B does not resemble known GPllb-llla binding site peptide sequences [Arg-Gly-Asp- Ser (RGDS) or gamma 50 400–411] as determined by competitive inhibition ELISA comparing these binding site synthetic peptides with gamma 57.5 408–416. This epitope is available for binding MoAb L2B in gamma 55 or gamma 57.5 chain dimers and binds to all gamma 57.5 408–416 epitopes equally in non-crosslinked and factor Xllla crosslinked fibrin clots.(ABSTRACT TRUNCATED AT 400 WORDS).

scholarly journals Increased surface expression of the membrane glycoprotein IIb/IIIa complex induced by platelet activation. Relationship to the binding of fibrinogen and platelet aggregation

Blood ◽  
1987 ◽  
Vol 70 (2) ◽  
pp. 475-483 ◽  
Author(s):  
K Niiya ◽  
E Hodson ◽  
R Bader ◽  
V Byers-Ward ◽  
JA Koziol ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Dissociation Constants ◽  
Surface Expression ◽  
The Other ◽  
Membrane Glycoprotein ◽  
Myristate Acetate ◽  
Fab Fragment ◽  
Activated Platelets ◽  
Fibrinogen Binding

Platelet activation altered the binding of three monoclonal antibodies (monovalent Fab' fragment) directed against the glycoprotein (GP) IIb/IIIa complex. An increased binding of two- to threefold occurred after stimulation with thrombin or phorbol myristate acetate (PMA), with slight but significant increase in the dissociation constants (Kd) of two antibodies (LJ-CP8 and LJ-P9). In contrast, no statistically significant changes were observed with ADP-stimulated platelets. The increased binding of LJ-CP3, but not of the other two antibodies, to activated platelets decreased by 30% to 40% in the presence of EDTA at 22 to 25 degrees C. Platelets stimulated by thrombin or PMA bound more fibrinogen than did those stimulated by ADP, and significant differences in the extent but not in the affinity of fibrinogen binding were observed with various platelet agonists. When the pool of GP IIb/IIIa molecules exposed on the surface of unstimulated platelets was reacted with the monoclonal antibody LJ-CP3 to block ADP-induced fibrinogen binding and platelet aggregation, stimulation with thrombin or PMA still induced substantial binding of antibody and fibrinogen, and aggregation ensued. Therefore, platelets exposed to “strong” agonists exhibit an increased number of surface-oriented epitopes associated with GP IIb/IIIa. The GP IIb/IIIa molecules bearing these newly exposed epitopes are functional in that they can bind fibrinogen and mediate platelet aggregation.

Note on Centrobaric Shells

1897 ◽  
Vol 21 ◽  
pp. 117-118
Author(s):  
Tait
Keyword(s):  
Spherical Shell ◽  
Simple Proof ◽  
Surface Density ◽  
Natural Philosophy ◽  
Direct Proof ◽  
The Other ◽  
Internal Point ◽  
Other Hand ◽  
Internal Particle ◽  
As If

It is singular to observe the comparative ease with which elementary propositions in attraction can be proved by one of the obvious methods, while the proof by the other is tedious.Thus nothing can be simpler than Newton's proof that a uniform spherical shell exerts no gravitating force on an internal particle. But, so far as I know, there is no such simple proof (of a direct character) that the potential is constant throughout the interior.On the other hand the direct proof that a spherical shell, whose surface-density is inversely as the cube of the distance from an internal point, is centrobaric is neither short nor simple. (See, for instance, Thomson and Tait's Elements of Natural Philosophy, § 491.) But we may prove at once that its potential at external points is the same as if its mass were condensed at the internal point.

STIMULUS-DEPENDENT CHANGES IN THE SURFACE EXPRESSION OF GPIIb/IIIa AND FIBRINOGEN RECEPTORS. RELATIONSHIP TO PLATELET AGGREGATION

1987 ◽  
Author(s):  
K Niiya ◽  
E Hodson ◽  
R Bader ◽  
V Byers-Ward ◽  
E F Plow ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Platelet Aggregation ◽  
Divalent Cation ◽  
Surface Expression ◽  
The Other ◽  
Fab Fragment ◽  
Activated Platelets ◽  
Fibrinogen Binding ◽  
Dissociation Constant Kd

Platelet stimulation altered the binding of three monoclonal antibodies (monovalent Fab’ fragment) directed against the glycoprotein (GP)IIb/IIIa complex. We found that 47,600-60,300 molecules of antibody bound per platelet before stimulation, as compared to 89,200-146,500 molecules per platelet after thrombin stimulation. These changes were observed in parallel with a small but significant increase in the dissociation constant (Kd) of two antibodies. In contrast, no statistically significant changes were observed with ADP-stimulated platelets. The increased binding of LJ-CP3, but not of the other two antibodies, to activated platelets decreased by 3040% in the presence of EDTA at 22-25°C, suggesting the occurrence of divalent-cation mediated, activation-dependent changes in the corresponding GPIIb/IIIa epitope. Platelets stimulated by thrombin bound more fibrinogen than those stimulated by ADP, and significant differences in the extent but not in the affinity of fibrinogen binding were observed with different platelet agonists. When the pool of GPIIb/IIIa molecules exposed on the surface of unstimulated platelets was reacted with monoclonal antibody LJ-CP3 to block ADP-induced fibrinogen binding and platelet aggregation, thrombin stimulation still induced substantial binding and aggregation. This effect of thrombin required exposure of platelets to the active agonist and was not mediated by molecules released by thrombin into the medium. Therefore, platelets activated with “strong” agonists exhibit increased number of surface-oriented epitopes associated with GPIIb/IIIa. The GPIIb/IIIa molecules bearing these newly exposed epitopes are functional in that they bind fibrinogen and mediate platelet aggregation.

scholarly journals Increased surface expression of the membrane glycoprotein IIb/IIIa complex induced by platelet activation. Relationship to the binding of fibrinogen and platelet aggregation

Blood ◽  
1987 ◽  
Vol 70 (2) ◽  
pp. 475-483 ◽  
Author(s):  
K Niiya ◽  
E Hodson ◽  
R Bader ◽  
V Byers-Ward ◽  
JA Koziol ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Dissociation Constants ◽  
Surface Expression ◽  
The Other ◽  
Membrane Glycoprotein ◽  
Myristate Acetate ◽  
Fab Fragment ◽  
Activated Platelets ◽  
Fibrinogen Binding

Abstract Platelet activation altered the binding of three monoclonal antibodies (monovalent Fab' fragment) directed against the glycoprotein (GP) IIb/IIIa complex. An increased binding of two- to threefold occurred after stimulation with thrombin or phorbol myristate acetate (PMA), with slight but significant increase in the dissociation constants (Kd) of two antibodies (LJ-CP8 and LJ-P9). In contrast, no statistically significant changes were observed with ADP-stimulated platelets. The increased binding of LJ-CP3, but not of the other two antibodies, to activated platelets decreased by 30% to 40% in the presence of EDTA at 22 to 25 degrees C. Platelets stimulated by thrombin or PMA bound more fibrinogen than did those stimulated by ADP, and significant differences in the extent but not in the affinity of fibrinogen binding were observed with various platelet agonists. When the pool of GP IIb/IIIa molecules exposed on the surface of unstimulated platelets was reacted with the monoclonal antibody LJ-CP3 to block ADP-induced fibrinogen binding and platelet aggregation, stimulation with thrombin or PMA still induced substantial binding of antibody and fibrinogen, and aggregation ensued. Therefore, platelets exposed to “strong” agonists exhibit an increased number of surface-oriented epitopes associated with GP IIb/IIIa. The GP IIb/IIIa molecules bearing these newly exposed epitopes are functional in that they can bind fibrinogen and mediate platelet aggregation.

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