scholarly journals The Effects of Varying Concentrations of Human Platelets and Their Stored Derivatives on the Recalcification Time of Plasma

Blood ◽  
1956 ◽  
Vol 11 (10) ◽  
pp. 910-915 ◽  
Author(s):  
EDMUND KLEIN ◽  
SIDNEY FARBER ◽  
GUSTAVE FREEMAN ◽  
ROSEMARY FIORENTINO
Keyword(s):  
Normal Values ◽  
Human Platelets ◽  
Clotting Time ◽  
High Concentrations ◽  
Recalcification Time

Abstract Human platelets and their stored, frozen and lyophilized derivatives do not excessively promote coagulation, as indicated by the calcium clotting time. High concentrations of platelet material inhibit coagulation, while dilution to physiologic levels returns the recalcification time to normal values.

Inhibition of Thrombin-, Epinephrine- and Collagen-Induced Platelet Aggregation by α1-Acid Glycoprotein

1979 ◽  
Author(s):  
P. Andersen ◽  
C. Eika
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Clotting Time ◽  
Acid Glycoprotein ◽  
High Concentrations ◽  
Spontaneous Platelet Aggregation ◽  
Induced Aggregation

α1-Acid glycoprotein (α1,-acid GP) isolated from human plasma was found to inhibit thrombin-induced aggregation of washed human platelets (0.05 NIH U/ml final conc.), and inhibition was complete with physiological concentrations of α1-acid GP (1.0-1.5 g/1 final conc.). The inhibitory effect seemed to occur immediately on thrombin addition, thus similar to the effect of heparin previously observed. As opposed to heparin, however, α1-acid GP did not affect spontaneous platelet aggregation. Furthermore, α1-acid GP (in optimal cone.) reduced the combined inhibitory effect of heparin and antithrombin III on thrombin-induced platelet aggregation, thus consistent with the previous findings using heparin thrombin clotting time.Snyder and Coodley (1976) found α1-acid GP to inhibit platelet aggregation induced by epinephrine and adenosine diphosphate in platelet-rich plasma. As we also found α1-acid GP to inhibit collagen-induced platelet aggregation, α1-acid GP may possibly act as an inhibitor of the release reaction though fairly high concentrations (10 mg/ml final cone.) was needed for complete inhibition.

scholarly journals STUDIES ON THROMBIN-INDUCED PLATELET AGGLUTINATION

1961 ◽  
Vol 114 (6) ◽  
pp. 905-920 ◽  
Author(s):  
Richard W. Shermer ◽  
Reginald G. Mason ◽  
Robert H. Wagner ◽  
Kenneth M. Brinkhous
Keyword(s):  
Ionic Strength ◽  
Divalent Cations ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
High Ionic Strength ◽  
Clotting Time ◽  
Cadmium Ions ◽  
Ph Values ◽  
Human Thrombin ◽  
High Concentrations

A one-stage macroscopic test for platelet agglutination was used to study the effect of thrombin and thrombin-cation mixtures on washed platelets. Conclusions regarding platelet agglutination are as follows: (a) Canine, bovine, or human thrombin alone does not cause agglutination of canine or human platelets. (b) Thrombin with calcium or magnesium causes rapid platelet agglutination. Both calcium and magnesium are active at physiologic concentrations. Divalent manganese or cadmium ions can be substituted for calcium or magnesium. (c) The agglutination reaction is affected but little by the species of origin of thrombin or platelets, or by variations in ionic strength or pH over a broad range. (d) Temperature at which the reaction is carried out is critical; optimal temperature for the test is 28°C. (e) Agglutination is inhibited by high ionic strength, by pH values outside the range 6.4–8.6, and by temperatures outside the range 25–28°C. High concentrations of calcium have a specific inhibitory effect. (f) Platelet agglutination time is as sensitive an index of thrombin concentration as is the fibrinogen clotting time. A comparison is made between divalent cations which influence platelet agglutination induced by thrombin, TAg', and TAg. A similar comparison is made of cations influencing the action of thrombin on the "substrates," fibrinogen, TAMe, and platelets.

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.

A Simple Method for Estimation of Lipoxygenase and Cyclo-Oxygenase Pathways in Human Platelets - the Use of Thiobarbituric Acid Reaction

1980 ◽  
Vol 44 (02) ◽  
pp. 111-114 ◽  
Author(s):  
Hiroshi Takayama ◽  
Minoru Okuma ◽  
Haruto Uchino
Keyword(s):  
Time Course ◽  
Normal Values ◽  
Human Platelet ◽  
Thiobarbituric Acid ◽  
Human Platelets ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Simple Method ◽  
Acid Reaction ◽  
Optimal Ph

SummaryTo develop a simple method for estimation of platelet lipoxygenase (PLO) and cyclo-oxygenase (PCO) pathways, the arachidonic acid (AA) metabolism of human platelet was investigated under various experimental conditions by the use of the thiobarbituric acid (TBA) reaction and a radioisotope technique. A TBA-reactive substance different from malondialdehyde (MDA) via PCO pathway was detected and shown to be derived from the PLO pathway. Since the optimal pH and time course of its formation were different from those of MDA formation via PCO pathway, PLO and PCO pathways were estimated by quantitating the TBA-reactive substances produced by the incubation of AA either with aspirin-treated platelets or with untreated ones, respectively, each under optimal conditions. Normal values expressed in terms of nmol MDA/108 platelets were 1.17±0.34 (M±SD, n = 31) and 0.79±0.15 (n = 31) for PLO and PCO pathways, respectively.

Coagulation Findings in Rats with Experimental Hypersplenism and Their Changes after Splenectomy and after Administration of Adrenaline

1970 ◽  
Vol 23 (03) ◽  
pp. 593-600
Author(s):  
P Pudlák ◽  
I Farská ◽  
V Brabec ◽  
V Pospíšilová
Keyword(s):  
Factor Viii ◽  
Normal Control ◽  
Normal Values ◽  
Coagulation Factors ◽  
Factor Vii ◽  
Factor V ◽  
Thrombin Time ◽  
Factor Ii ◽  
Recalcification Time

Summary1. The following coagulation changes were found in rats with experimental hypersplenism: a mild prolongation of the recalcification time, shortened times in Quick’s test, a lowered activity in plasma thrombin time and shortened times in the partial thromboplastin test. Concentrations of factor II, V, VII (+X), VIII and X did not differ from those of normal control rats.2. The administration of adrenaline to hypersplenic rats induced the correction of the partial thromboplastin test, Quick’s test and plasma thrombin time to normal values. Concentrations of coagulation factors were not significantly changed. An increase was found in factor V.3. Splenectomy performed in hypersplenic rats was followed by a shortened recalcification time, a prolongation of the partial thromboplastin test and of the test with partial thromboplastin and kaolin. A prolongation was also observed in Quick’s test. Complete correction of plasma thrombin time was not observed. The concentration of factor VII increased.4. The administration of adrenaline to splenectomized rats with experimental hypersplenism did not induce any significant changes with the exception of a corrected plasma thrombin time and a decreased concentration of factor VIII.5. A different reaction of factor VIII to adrenaline in normal and hypersplenic rats is pointed out.

Interactions of Purified Rat Factor VIII/von Willebrand Factor with Rat and Human Platelets – Effect of Albumin and Ristocetin

1984 ◽  
Vol 52 (01) ◽  
pp. 057-059 ◽  
Author(s):  
E Dejana ◽  
M Furlan ◽  
B Barbieri ◽  
M B Donati ◽  
E A Beck
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Rat Plasma ◽  
Human Platelets ◽  
High Concentrations ◽  
Low Sensitivity ◽  
Von Willebrand ◽  
Induced Aggregation ◽  
Willebrand Factor ◽  
Rat Platelets

SummaryRat platelets do not respond to ristocetin in their own plasma nor do they aggregate in the presence of bovine or porcine factor VIII von Willebrand factor (F VIII R:WF) or human F VIII R:WF in presence of ristocetin. However, rat plasma supports ristocetin induced aggregation of washed human platelets. In this study we report on purification of rat F VIII R:WF from cryoprecipitate. Similarly to porcine or bovine material, purified rat F VIII R:WF induced aggregation of human washed fixed platelets. This effect was enhanced by addition of ristocetin and was not modified by addition of albumin. Rat washed platelets were aggregated by ristocetin in the presence of rat or human F VIII R:WF provided that high concentrations of ristocetin are added in a system essentially free of extraneous proteins. Increasing concentrations of albumin dramatically reduced the ability of ristocetin to aggregate rat platelets while human platelet aggregation by human or rat F VIII R:WF was only moderately affected.These studies show that rat F VIII R:WF can interact with rat and human platelets. The lack of response of rat platelets to ristocetin in their own plasma is most likely due to a low sensitivity of rat platelets to this drug and to an inhibitory activity of plasma proteins on this reaction.

THE REDUCED CAPACITY OF THROMBOXANE FORMATION IN THROMBIN-PREACTIVATED PLATELETS IS NOT CAUSED BY DEPLETION OF THEIR ARACHIDONIC ACID POOL

1987 ◽  
Author(s):  
R E Scharf ◽  
M Stockschläder ◽  
H J Reimers ◽  
W Schneider
Keyword(s):  
Arachidonic Acid ◽  
Human Platelets ◽  
Thrombin Receptor ◽  
Precursor Pool ◽  
Acid Pool ◽  
Exogenous Arachidonic Acid ◽  
High Concentrations ◽  
Short Time ◽  
Thromboxane Formation

Thromboxane (TX) synthesis of washed human platelets pretreated with high concentrations of thrombin (0.5-2.0 U/ml) for 20 sec is significantly reduced upon further thrombin stimulation. Compared to controls (tyrode-pretreated platelets), thrombin-preactivated platelets recover normal TX synthesis following exposure to exogenous arachidonic acid (AA) indicating that short-time thrombin treatment does not inactivate platelet cyclooxygenase or TX synthetase (Blood 63: 858, 1984). To evaluate whether the reduced TX synthesis upon -the second thrombin exposure is due to depletion of their AA precursor pool, thrombin-pretreated platelets and tyrode-pretreated platelets (5×108/ml) were resuspended in autologous ACD plasma and incubated at 37°C with 0.2 μCi 14C-AA (20 μM) for 60 to 90 min in the presence of PGE1 (10 μM). Mean platelet uptake of 14C-AA (disappearance of radioactivity from the supernatant) was 12+3 nmoles AA/109 platelets and did not differ significantly between thrombin-pretreated platelets and controls. Thrombin-pretreated platelets released 10% or 4.5% of their 14c-activity upon further exposure to thrombin (2 U/ml) or collagen (8 μg/ml), respectively. The release from control platelets (15% with thrombin, 6.5% with collagen) did not differ from that of thrombin-pretreated platelets. However, even after incubation in ACD plasma, thrombin-pretreated platelets continued to form significantly less TXB2 (5.0±1.6 nmoles/109 platelets) than controls (9.7±2.2 nmoles/109 platelets, p< 0.05). These data indicate that the reduced capacity of thrombin-pretreated platelets is due neither to a depletion of the endogenous AA pool nor to an inactivation of cyclooxygenase or TX synthetase. The reduced TX synthesis capacity may be caused by a modification, destruction or desensitization of the platelet thrombin receptor as a consequence of the preceding thrombin stimulation.

Combined blockade of thrombin anion binding exosite-1 and PAR4 produces synergistic antiplatelet effect in human platelets

2011 ◽  
Vol 105 (01) ◽  
pp. 88-95 ◽  
Author(s):  
Wei-Ya Wang ◽  
Chien-Kei Wei ◽  
Che-Ming Teng ◽  
Chin-Chung Wu
Keyword(s):  
Platelet Aggregation ◽  
Active Site ◽  
Antithrombotic Therapy ◽  
Specific Binding ◽  
Anticoagulant Activity ◽  
Human Platelets ◽  
Anion Binding ◽  
Inhibitory Effects ◽  
Clotting Time ◽  
Potential Strategy

SummaryThrombin exosite-1 mediates the specific binding of thrombin with fibrinogen and protease-activated receptor (PAR) 1. Exosite-1 inhibitors have been shown to effectively decrease the clotting activity of thrombin, while their antiplatelet effects are relatively weak. In the present study, the inhibitory effects of two exosite-1 inhibitors, hirugen and HD1, but not the exosite-2 inhibitor HD22, on thrombin-induced platelet aggregation and P-selectin expression were dramatically enhanced by a PAR4 antagonist, YD-3. In contrast, the PAR1 antagonist SCH-79797 did not affect the antiplatelet effects of exosite-1 inhibitors. The exosite-1 inhibitors and YD-3 prevented the Ca2+ spike and the prolonged Ca2+ response in thrombin-stimulated platelets, respectively; and combination of these two classes of agents led to abolishment of Ca2+ signal. Unlike exosite-1 inhibitors, the antiplatelet effects of the active site inhibitor PPACK and the bivalent inhibitor bivalirudin were not significantly enhanced by YD-3. In addition, the platelet-stimulating activity of γ-thrombin, an autolytic product of α-thrombin which lacks exosite-1, was inhibited by YD-3. These results suggest that the synergistic antiplatelet effects of exosite-1 inhibitor and PAR4 antagonist are resulted from combined blockade of PAR1 and PAR4 in platelets. In fibrinogen or plasma clotting assay, YD-3 neither prolonged the clotting time on its own nor enhanced the anticoagulant activity of exosite-1 inhibitors. Therefore, the combined blockade of exosite-1 and PAR4 may offer a potential strategy for improving the balance of benefits and risks of antithrombotic therapy.

scholarly journals Activation of human platelets by immune complexes prepared with cationized human IgG

Blood ◽  
1993 ◽  
Vol 82 (10) ◽  
pp. 3045-3051
Author(s):  
M Schattner ◽  
M Lazzari ◽  
AS Trevani ◽  
E Malchiodi ◽  
AC Kempfer ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Immune Complexes ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Human Igg ◽  
Experimental Conditions ◽  
Induce Platelet Aggregation ◽  
Soluble Immune Complexes ◽  
High Concentrations

The present study shows that the ability of soluble immune complexes (IC), prepared with human IgG and rabbit IgG antibodies against human IgG, to trigger platelet activation was markedly higher for IC prepared with cationized human IgG (catIC) compared with those prepared with untreated human IgG (cIC). CatIC induced platelet aggregation and adenosine triphosphate release in washed platelets (WP), gel-filtered platelets (GFP), or platelet-rich plasma (PRP) at physiologic concentrations of platelets (3 x 10(8)/mL) and at low concentrations of catIC (1 to 30 micrograms/mL). On the contrary, under similar experimental conditions, cIC did not induce aggregation in PRP, WP, or GFP. Low aggregation responses were only observed using high concentrations of both WP (9 x 10(8)/mL) and cIC (500 micrograms/mL). Interestingly, catIC were also able to induce platelet activation under nonaggregating conditions, as evidenced by P-selectin expression. Cationized human IgG alone did not induce platelet aggregation in PRP but triggered either WP or GFP aggregation. However, the concentration needed to induce these responses, was about eightfold higher than those required for catIC. The responses induced either by catIC or cationized human IgG were completely inhibited by treatment with heparin, dextran sulphate, EDTA, prostaglandin E1, or IV3, a monoclonal antibody against the receptor II for the Fc portion of IgG (Fc gamma RII). The data presented in this study suggest that IgG charge constitutes a critical property that conditions the ability of IC to trigger platelet activation.

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