Interactions of Staphylokinase with Human Platelets

1995 ◽  
Vol 73 (03) ◽  
pp. 472-477 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
D Collen
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Specific Binding ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Normal Plasma ◽  
Atp Secretion ◽  
Platelet Disaggregation ◽  
Activation Rate

SummaryThe interactions of recombinant staphylokinase (SakSTAR) with human platelets were investigated in a buffer milieu, in a human plasma milieu in vitro, and in plasma from patients with acute myocardial infarction (AMI) treated with SakSTAR.In a buffer milieu, the activation rate of plasminogen by SakSTAR or streptokinase (SK) was not significantly altered by addition of platelets. Specific binding of SakSTAR or SK to either resting or thrombin- activated platelets was very low. ADP-induced or collagen-induced platelet aggregation in platelet-rich plasma (PRP) was 94 ± 2.7% or 101 ± 1.7% of control in the presence of 0.1 to 20 μM SakSTAR, with corresponding values of 95 ± 2.8% or 90 ± 4.6% of control in the presence of 0.1 to 4 μM SK. No effects were observed on platelet disaggregation. ATP secretion following collagen-induced platelet aggregation was 4.3 ± 0.26 μM for SakSTAR (at concentrations of 0.1 to 20 μM) and 4.4 ± 0.35 μM for SK (at concentrations of 0.1 to 4 μM), as compared to 3.4 ± 0.70 μM in the absence of plasminogen activator.Fifty % lysis in 2 h (C50) of 60 μl 125I-fibrin labeled platelet-poor plasma (PPP) clots prepared from normal plasma or from plasma of patients with Glanzmann thrombasthenia and immersed in 0.5 ml normal plasma, was obtained with 12 or 16 nM SakSTAR and with 49 or 40 nM SK, respectively. C50 values for lysis of 60 μl PRP clots prepared from normal or patient plasma were also comparable for SakSTAR (19 or 21 nM), whereas SK was 2-fold more potent toward PRP clots prepared from Glanzmann plasma as compared to normal plasma (C50 of 130 versus 270 nM).No significant effect of SakSTAR on platelet function was observed in plasma from patients with AMI treated with SakSTAR, as revealed by unaltered platelet count, platelet aggregation and ATP secretion.Thus, no effects of high SakSTAR concentrations were observed on human platelets in vitro, nor of therapeutic SakSTAR concentrations on platelet function in plasma.

Effects of Lead Acetate on Platelet Aggregation, Ultrastructure and Serotonin Release

1971 ◽  
Vol 26 (03) ◽  
pp. 455-466 ◽  
Author(s):  
R. B Davis ◽  
G. C Holtz
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Lead Acetate ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Human Platelets ◽  
Serotonin Release ◽  
Aggregation Of Platelets

SummaryThe effects of lead on blood platelet function and ultrastructure have been investigated. Lead acetate was injected intravenously in 27 rats and was added to rat and human platelet rich plasma in vitro. In vitro studies showed that concentrations of 2.5 × 10-3 M lead acetate reduced or blocked aggregation of rat and human platelets by adenosine diphosphate, collagen, and thrombin. Radioactive serotonin release from human platelets was inhibited by 10-4 M lead acetate. One hour after the injection of lead, platelet aggregation by thrombin was reduced, but platelet aggregation by adenosine diphosphate and collagen showed little change. Three days after lead, aggregation of platelets by collagen and thrombin was blocked and aggregation by adenosine diphosphate reduced. Thrombocytopenia was present 4 days after intravenous lead acetate. Electron micrographs of platelets showed that the mean number of mitochondria per platelet was increased, whereas alpha granules were reduced. Dense bodies were not significantly changed. Lead acetate affects platelet function in concentrations reported in human bone marrow in lead poisoning, and may relate to the binding of free sulfhydryl groups by lead.

GSK3β Is a Negative Regulator of Platelet Function In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 395-395
Author(s):  
Donna S. Woulfe ◽  
Shelley August ◽  
Dongjun Li
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Ferric Chloride ◽  
Arterial Thrombosis ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Negative Regulator ◽  
Response Curves

Abstract GSK3β is a ser-thr kinase that is itself phosphorylated on ser9 by the kinase Akt. Because Akt has recently been shown to regulate platelet aggregation and arterial thrombosis in mice, we sought to identify Akt substrates in platelets that may play important roles in platelet function. We show here that the Akt effector, GSK3β, is present in platelets and becomes phosphorylated after treatment of mouse or human platelets with ADP or thrombin receptor-activating peptides (TRAP). Agonist-dependent phosphorylation of GSK3β is reduced by pre-treatment of mouse or human platelets with the PI3K inhibitor LY294002 and is also reduced in platelets from Akt2−/−Akt1+/− mice relative to non-littermate controls, suggesting that agonist-induced GSK3β phosphorylation is partially PI3K- and Akt-dependent. To determine whether GSK3β plays a role in platelet function, aggregation and secretion of dense granule contents were evaluated in human platelets treated with the GSK3 inhibitors, LiCl or SB216763. The dose-response curves for agonist-induced platelet aggregation and secretion were left-shifted in the presence of either inhibitor compared to untreated control platelets, suggesting that GSK3 activity suppresses platelet aggregation. Comparative immunoblots suggest that GSK3β is more highly expressed in platelets than GSK3α. Therefore, to confirm that GSKβ plays a suppressive role in platelet function, the aggregation of platelet-rich plasma (PRP) from GSK3β+/− mice was compared to that of non-littermate controls (GSK3β −/− mice die in utero). PRP from GSK3β+/− mice showed enhanced aggregation and secretion in response to U46619 or TRAP compared to control PRP. TRAP-induced binding of AlexaFluor-fibrinogen to platelet surfaces was also enhanced in washed platelets from GSK3β+/− mice compared to control platelets. Finally, the effect of GSK3β on platelet function in vivo was evaluated using two thrombosis models: a ferric chloride injury model of arterial thrombosis and a collagen-induced model of disseminated thrombosis. In the arterial thrombosis model, all GSK3β+/− mice (n=5) formed stable occlusive thrombi after ferric chloride injury to the carotid artery, whereas the majority of wildtype mice (67%) formed no thrombi, 27% formed stable occlusive thrombi, and 7% formed unstable thrombi under the same conditions (n=15). In a model of disseminated thrombosis, injection of a combination of collagen (170 μg/kg) and epinephrine (350 μM/kg) resulted in reduced survival of GSK3β+/− mice 10 minutes post-injection relative to wildtype mice (20%, n=5 versus 83%, n=6, respectively). Histological examination of lung sections suggested that all mice that died did so due to pulmonary embolism. These data suggest that removal of a single allele of GSK3β in mice confers enhanced sensitivity to thrombotic insult. Taken together, these results suggest that GSK3β is a substrate of Akt-dependent phosphorylation in platelets and, in contrast to the function of Akt, acts as a negative regulator of platelet function in vitro and in vivo.

Reaction of Acetaldehyde with Human Platelets

1992 ◽  
Vol 67 (01) ◽  
pp. 126-130 ◽  
Author(s):  
Olivier Spertini ◽  
Jacques Hauert ◽  
Fedor Bachmann
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Reaction Medium ◽  
Human Platelets ◽  
Membrane Glycoproteins ◽  
Neutral Ph

SummaryPlatelet function defects observed in chronic alcoholics are not wholly explained by the inhibitory action of ethanol on platelet aggregation; they are not completely reproduced either in vivo by short-term ethanol perfusion into volunteers or in vitro by the addition of ethanol to platelet-rich plasma. As acetaldehyde (AcH) binds to many proteins and impairs cellular activities, we investigated the effect of this early degradation product of ethanol on platelets. AcH formed adducts with human platelets at neutral pH at 37° C which were stable to extensive washing, trichloracetic acid hydrolysis and heating at 100° C, and were not reduced by sodium borohydride. The amount of platelet adducts formed was a function of the incubation time and of the concentration of AcH in the reaction medium. At low AcH concentrations (<0.2 mM), platelet bound AcH was directly proportional to the concentration of AcH in the reaction medium. At higher concentrations (≥0.2 mM), AcH uptake by platelets tended to reach a plateau. The amount of adducts was also proportional to the number of exposures of platelets to pulses of 20 pM AcH.AcH adducts formation severely impaired platelet aggregation and shape change induced by ADP, collagen and thrombin. A positive correlation was established between platelet-bound AcH and inhibition of aggregation.SDS-PAGE analysis of AcH adducts at neutral pH demonstrated the binding of [14C]acetaldehyde to many platelet proteins. AcH adduct formation with membrane glycoproteins, cytoskeleton and enzymes might interfere with several steps of platelet activation and impair platelet aggregation.This in vitro study shows that AcH has a major inhibitory action on platelet aggregation and may account for the prolonged ex vivo inhibition of aggregation observed in chronic alcoholics even in the absence of alcoholemia.

Effects of Halothane on Platelet Function

1980 ◽  
Vol 44 (03) ◽  
pp. 143-145 ◽  
Author(s):  
J Dalsgaard-Nielsen ◽  
J Gormsen
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Halothane Anaesthesia ◽  
Inhibition Of Platelet Aggregation ◽  
Transient Impairment ◽  
High Concentrations ◽  
Uptake And Release ◽  
Platelet Functions

SummaryHuman platelets in platelet rich plasma (PRP) incubated at 37° C with 0.3–2% halothane for 5–10 min lost the ability to aggregate with ADP, epinephrine and collagen.At the same time uptake and release of 14C-serotonin was inhibited. When halothane supply was removed, platelet functions rapidly returned to normal. However, after high concentrations of halothane, the inhibition of platelet aggregation was irreversible or only partially reversible.The results suggest that halothane anaesthesia produces a transient impairment of platelet function.

The Effect of Barbituric Acid Derivatives on Platelet Function in Vitro and in Vivo

1973 ◽  
Vol 30 (02) ◽  
pp. 315-326
Author(s):  
J. Heinz Joist ◽  
Jean-Pierre Cazenave ◽  
J. Fraser Mustard
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Barbituric Acid ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Primary Response ◽  
Sodium Pentobarbital ◽  
Barbituric Acid Derivatives

SummarySodium pentobarbital (SPB) and three other barbituric acid derivatives were found to inhibit platelet function in vitro. SPB had no effect on the primary response to ADP of platelets in platelet-rich plasma (PRP) or washed platelets but inhibited secondary aggregation induced by ADP in human PRP. The drug inhibited both phases of aggregation induced by epinephrine. SPB suppressed aggregation and the release reaction induced by collagen or low concentrations of thrombin, and platelet adherence to collagen-coated glass tubes. The inhibition by SPB of platelet aggregation was readily reversible and isotopically labeled SPB did not become firmly bound to platelets. No inhibitory effect on platelet aggregation induced by ADP, collagen, or thrombin could be detected in PRP obtained from rabbits after induction of SPB-anesthesia.

scholarly journals Are Platelet Aggregation Tests the Best Way to Assess New Drugs for Arterial Disease

2018 ◽  
Vol 1 (1) ◽  
pp. 01-03
Author(s):  
Mark I. M. Noble
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Platelet Rich Plasma ◽  
New Drugs ◽  
In Vitro Test ◽  
In Vivo Efficacy ◽  
Experimental Animals ◽  
Stenosed Artery

Over many years, laboratory testing of platelet aggregability have been carried out in attempts to develop drugs that would prevent thrombosis in arteries. The problems encountered included the question of methodology. Blood samples have to be anticoagulated in order to study the platelets. Anti-coagulation with citrate and tests on derived platelet rich plasma did not correlate at all well with thrombus growth in the stenosed coronary arteries of experimental animals and citrate removes the calcium ions which are vital for platelet function. Anticoagulation with heparin also interfered with platelet function, so that now, hirudins are the preferred anticoagulant. However it was observed that if, instead of stimulating platelet aggregation with adrenaline or ADP, serotonin was applied to the preparation, very little aggregation took place in spite of serotonin 5HT2A antagonists being the most potent inhibitors of thrombus growth in experimental animals. Another indicator that primary platelet agggregation is not a predictor of in vivo efficacy was the finding that 5HT2A antagonism inhibited aggregate growth. In a stenosed artery the platelets are activated by increased shear stress and blood turbulence with release of platelet serotonin causing positive feedback activation of more platelets. At present, there does not seem to be a bench in vitro test that accurately predicts in vivo efficacy in stenosed artery occlusive thrombosis.

Arginine vasopressin release from human platelets after irreversible aggregation

1990 ◽  
Vol 78 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Giovanni Anfossi ◽  
Elena Mularoni ◽  
Mariella Trovati ◽  
Paola Massucco ◽  
Luigi Mattiello ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Arginine Vasopressin ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Vasopressin Release ◽  
Irreversible Aggregation ◽  
Local Release

1. The release of arginine vasopressin from human platelets was investigated in platelet-rich plasma after irreversible aggregation induced by adenosine 5′-pyrophosphate, collagen, sodium arachidonate, thrombin and adrenaline in vitro. 2. Arginine vasopressin levels were significantly higher in the supernatant from stimulated platelet-rich plasma than from unstimulated samples, reaching 3.5 × 10−12 (range 1.6–12.5 × 10−12) mol/l in the absence of an aggregating agent, 8.8 × 10−12 (range 4.2–17.5 × 10−12) mol/l after adenosine 5′-pyrophosphate, 13.7 × 10−12 (2.2–63.2 × 10−12) mol/l after collagen, 7.8 × 10−12 (2.2–14.6 × 10−12) mol/l after sodium arachidonate, 7.8 × 10−12 (2.2–16.3 × 10−12) mol/l after thrombin and 12.2 × 10−12 (4.8–32.1 × 10−12) mol/l after adrenaline. 3. An arginine vasopressin level of 18 × 10−12 mol/l, which can be achieved physiologically, increased the sensitivity of platelets to adenosine 5′-pyrophosphate and collagen in vitro; the same concentration of arginine vasopressin caused a potentiation of the effect of catecholamines on the response of platelets to sodium arachidonate. 4. These results indicate that intraplatelet arginine vasopressin is released during aggregation and suggest that a local release of arginine vasopressin could occur after complete platelet aggregation in vivo.

Endotoxin-Induced Platelet Activation in Human Whole Blood In Vitro

1988 ◽  
Vol 59 (03) ◽  
pp. 378-382 ◽  
Author(s):  
Gyorgy Csako ◽  
Eva A Suba ◽  
Ronald J Elin
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Atp Release ◽  
Human Platelets ◽  
Lag Phase ◽  
Human Whole Blood ◽  
Dose Dependent

SummaryThe effect of purified bacterial endotoxin was studied on human platelets in vitro. In adding up to 1 μg/mL of a highly purified endotoxin, we found neither aggregation nor ATP release in heparinized or citrated human platelet-rich plasma. On the other hand, endotoxin at concentrations as low as a few ng/mL (as may be found in septic patients) caused platelet aggregation in both heparinized and citrated human whole blood, as monitored by change in impedance, free platelet count, and size. Unlike collagen, the platelet aggregation with endotoxin occurred after a long lag phase, developed slowly, and was rarely coupled with measurable release of ATP. The platelet aggregating effect of endotoxin was dose-dependent and modified by exposure of the endotoxin to ionizing radiation. Thus, the activation of human platelets by “solubilized” endotoxin in plasma requires the presence of other blood cells. We propose that the platelet effect is mediated by monocytes and/or neutrophils stimulated by endotoxin.

Effect Of Factor XIII On Platelet Aggregation. Study Of Platelet Function And Fibrin Stabilization Inhibitors

1981 ◽  
Author(s):  
M Maamer ◽  
O Demay ◽  
M Aurousseau
Keyword(s):  
Platelet Aggregation ◽  
Acetylsalicylic Acid ◽  
Platelet Function ◽  
Factor Xiii ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Photometric Method

There is little information on the participation of Factor XIII in platelet aggregation. Using BORN’s photometric method to study platelet aggregation induced by ADP in vitro on platelet rich plasma (PRP) of rabbit; clot solubility in 1 % monochloracetic acid and incorporation of dansylcadaverin into casein (LORAND L. et al.) to measure plasma FXIII concentration ; we showed that addition of activated F.XIII (F.XIIIa) to a PRP, aggregating power of platelets was significantly increased (+ 30.4 %, p<0.00l). Addition of inactive F.XIII or thrombin + Ca++ in concentrations used to activate F.XIII, had no significant effect on platelet aggregation induced by ADP.When F.XIIIa was added to plasma in presence of F.XIII inhibitors as 3178 AQ (a new synthetic benzothiophen keton derivative) or monodansylcadaverin (DC) in concentrations of (3.27 × 10-4 M and 9.31 × 10-4 m respectively), the platelet aggregation was significantly inhibited (- 48.8 % and - 35.4 % respectively, p<0.001). This inhibitory effect was not seen when dipyridamole or Acetylsalicylic Acid (ASA) in concentrations of (6.18 × 10-4 M and 17.3 × 10-4 M respectively) ware added in PRP in presence of F.XIIIa When platelet aggregation was performed without addition of F.XIIIa the inhibitory effect of 3178 AQ and DC was respectively (- 76.6 % and - 65.1 %, p<0.001), dipyridamole (- 37.6 %, p<0.00l) and ASA (-4.1%, no significant)These results suggest that F.XIIIa increased the platelet aggregation induced by ADP and compounds which are both inhibitors of platelet aggregation and F.XIII would be more potent antithrombotic by acting on platelets and fibrin stabilization, than drugs which are inhibitors of platelet aggregation only.

Effect of Heparin on Aggregation, Release Reaction and Thromboxane A2synthesis in Human Platelets

1979 ◽  
Author(s):  
H.Y.K. Chuang ◽  
S.F. Mohammad ◽  
R.G. Mason
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Thromboxane A2 ◽  
Rabbit Aorta ◽  
Human Platelets ◽  
Appreciable Effect ◽  
Layer Chromatography ◽  
Aggregation Of Platelets ◽  
Platelet Functions

Studies on the effect of heparin on platelet functions have resulted in conflicting observations: heparin has been reported to cause aggregation of platelets, potentiate aggregation induced by various aggregating agents, or cause inhibition of aggregation. Using paritally purified heparin (beef lung or porcine mucosa) we observed that addition of heparin to citrated platelet rich plasma(C-PRP)potentiated the aggregation of platelets induced by ADP, epinephrine, or arachidonic acid. Presence of heparin in C-PRP results in complete inhibition of thrombin induced effects and partial inhibition of platelet aggregation induced by collagen. Presence of heparin in C-PRP also resulted in release of significantly higher concentrations of 14C-serotonin when platelets were challenged by appropriate aggregating agents. Those concentrations of heparin that resulted in potentiation of aggregation had no appreciable effect on c-AiMP or c-GMP levels of platelets. However, the presence of heparin results in a significant elevation of thromboxane A2 as determined by contraction of rabbit aorta or after conversion to thromboxane B2 by thin layer chromatography. These observations are of interest since increased production of thromboxane A2 in the presence of heparin may explain in part, the potentiation of platelet aggregation in vitro or thrombocytopenia observed frequently in patients receiving heparin intravenously Supported in part by grants HL22583 & 20679 from NHLBI of NIH.

Sign in / Sign up

Export Citation Format

Share Document