Aggregation of Human Platelets by Acidic Mucopolysaccharide Extracted from Stichopus japonicus Selenka

1988 ◽  
Vol 59 (03) ◽  
pp. 435-439 ◽  
Author(s):  
Jia-Zeng Li ◽  
Eric Chun-Yet Lian
Keyword(s):  
Platelet Aggregation ◽  
Sea Cucumber ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Human Platelets ◽  
Second Phase ◽  
Platelet Inhibitors ◽  
Stichopus Japonicus ◽  
Human Platelet Aggregation

SummaryThe acidic mucopolysaccharide extracted from sea cucumber (Stichopus japonicus Selenka) (SJAMP) has been shown to cause platelets to aggregate. Using citrated platelet-rich plasma (PRP), washed platelets and formaldehyde-fixed platelets from humans, we investigated the effects of platelet inhibitors and various plasmas and their fractions on SJAMP-induced platelet aggregation. It was found that the lowest concentration of SJAMP required for the aggregation of human platelets was about 0.4 μg/ ml and the magnitude of aggregation induced by SJAMP was concentration dependent. The platelets were aggregated by SJAMP at 10 μg/ml in 25 out of 28 (89%) normal subjects tested. Platelet inhibitors such as PGE1, aspirin, indomethacin, apyrase, antimycin, 2-deoxy-D-glucose and EDTA inhibited by 70 to 100% the aggregation induced by SJAMP. Washed platelets alone were not aggregated by SJAMP. In the presence of fibrinogetr, washed platelets were aggregated by SJAMP, but formaldehyde-fixed platelets were not. These data indicate that the SJAMP-induced human platelet aggregation requires extracellular calcium, fibrinogen, and energy metabolism. The second phase of aggregation is dependent upon the release of ADP, and cyclooxygenase pathway.

Human Platelet Aggregation and Release Reaction Induced by Platelet Activating Factor (PAF-Acether) – Effects of Acetylsalicylic Acid and External Ionized Calcium

1985 ◽  
Vol 53 (02) ◽  
pp. 221-224 ◽  
Author(s):  
Marco Cattaneo ◽  
Maria Teresa Canciani ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Platelet Aggregation ◽  
Acetylsalicylic Acid ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Human Platelet Aggregation ◽  
Low Concentrations ◽  
Before And After ◽  
Platelet Secretion

SummaryThe effects of the cyclo-oxygenase inhibition on PAF-acether- induced human platelet aggregation and secretion are controversial. We studied the above parameters on citrated platelet-rich plasma of 12 normal subjects before and after the in vivo administration of acetylsalicylic acid (ASA). Individual sensitivities to PAF-acether were highly variable. ASA completely inhibited the platelet secretion induced by low concentrations of PAF-acether, but caused only partial inhibition when platelets were exposed to high concentrations of PAF-acether. The concentration of PAF-acether which overcame the cyclo-oxygenase inhibition varied substantially, depending on the individual sensitivity of the platelets to it. The addition of CaCl2 2 mM to the samples did not affect the extent of the platelet secretion, but increased irreversible aggregation in samples taken both before and after the ASA administration. These data suggest that low concentrations of PAF-acether stimulate the human platelet secretion by activating the cyclo-oxygenase pathway, whereas higher concentrations also trigger other mechanism(s) that suffice to induce human platelet secretion and full aggregation.

scholarly journals The Effect of Imidazole on Human Platelet Aggregation

Blood ◽  
1971 ◽  
Vol 38 (4) ◽  
pp. 417-421 ◽  
Author(s):  
JAMES W. DAVIS ◽  
PHYLLIS E. PHILLIPS
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Glass Bead ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Second Phase ◽  
Platelet Function Tests ◽  
Human Platelet Aggregation ◽  
Function Tests ◽  
Induced Aggregation

Abstract Since imidazole buffers have been used in platelet function tests and the compound has been reported to alter several biochemical activities of platelets, it seemed important to determine whether imidazole influenced platelet aggregation. ADP-induced, collagen-induced, and norepinephrine-induced platelet aggregations were tested in platelet-rich plasma by turbidimetric techniques. Glass bead-induced platelet aggregation in whole blood was tested by a method dependent upon platelet counts. Imidazole, in concentrations of 5mM or less, inhibited aggregation induced by each of these four agents and had negligible effect on the pH of platelet-rich plasma. The second phase of both ADP- and norepinephrine-induced aggregation was inhibited or abolished by imidazole, and 5mM imidazole also inhibited the first phase of norepinephrine-induced aggregation. As little as 0.5 mM imidazole inhibited collagen-induced aggregation in some plasmas. Imidazole appears to be unsuitable for use as a buffer in platelet function tests.

Highly Efficient Induction of Human Platelet Aggregation in Heparinized Platelet-Rich Plasma by Diadenosine Triphosphate (Ap3A)

1985 ◽  
Vol 54 (02) ◽  
pp. 469-471 ◽  
Author(s):  
Jürgen Lüthje ◽  
Johann Baringer ◽  
Adaling Ogilvie
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Human Platelet Aggregation ◽  
Efficient Induction ◽  
Diadenosine Triphosphate ◽  
Hydrolysis Of

SummaryDiadenosine triphosphate (Ap3A), which is a releasable dinucleotide of human platelets, induces platelet aggregation when added to heparinized platelet-rich plasma. The concentration dependence of the dinucleotide is similar to ADP. This finding is fully compatible with our recent report of the low potency of Ap3A in citrated platelet-rich plasma relative to ADP.The aggregatory effect of Ap3A in heparinized versus citrated plasma is reflected in the corresponding rates of Ap3A degradation. In citrated plasma, the hydrolysis of Ap3A is drastically slowed down because the hydrolase needs divalent metal ions. The results strongly support the assumption that the aggregatory effect of Ap3A is mediated by the enzymatic hydrolysis of Ap3A which generates ADP as the ultimate stimulus.

scholarly journals The Combined Effects of 2,3-Diphosphoglycerate and Phospholipase-A on Platelet Aggregation Induced by ADP, Epinephrine, Norepinephrine and Collagen

1977 ◽  
Author(s):  
M.F. Asterita ◽  
P.G. Iatridis ◽  
S.G. Iatridis ◽  
R. Torrella ◽  
B.H. Ragatz ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Phospholipase A ◽  
Time Dependent ◽  
Second Phase ◽  
Combined Effects ◽  
Dual Channel ◽  
Human Platelet Aggregation ◽  
2,3 Dpg

It has been shown recently, that under specific conditions, phospholipase-A (Phl-A) or 2,3-diphosphoglycerate (2,3-DPG) can inhibit human platelet aggregation induced by ADP, epinephrine, norepinephrine or collagen. In this report, by using a dual channel Payton Aggregometer, the effects of 2,3-DPG and Phl-A on platelet aggregation were further studied. When 2,3-DPG (2μM) was added in human platelet rich plasma with Phl-A (200μU), 30, 60, 120 or 300 sec. before the addition of ADP (0.5-2.0μM), epinephrine (2-5uM) or norepinephrine (2-5μM) an enhancement of platelet aggregation was observed, whereas the same concentration of 2,3-DPG alone or Phl-A alone, inhibited both the rate and extent of the second phase of platelet aggregation induced by the same aggregating substances. The combined effects of 2,3-DPG and Phl-A on collagen induced platelet aggregation remained inhibitory. Aspirin on the other hand abolished the enhancement of platelet aggregation induced by 2,3-DPG and Phl-A. These combined effects of 2,3-DPG and Phl-A were both a concentration and a time dependent response. The results indicate that the combined effects of 2,3-DPG and Phl-A were probably mediated through prostaglandin formation. Since Phl-A is a physiological platelet enzyme which releases arachidonic acid, then we may postulate that 2,3-DPG probably activates the synthetases and/or cyclooxygenases which are the enzymes necessary for the formation of the important platelet aggregating substances, namely the endoperoxides and thromboxanes. Supported by USPHS HL-15425.

Inhibitory Effect of Staphylokinase on Platelet Aggregation

1993 ◽  
Vol 70 (05) ◽  
pp. 834-837 ◽  
Author(s):  
Akira Suehiro ◽  
Yoshio Oura ◽  
Motoo Ueda ◽  
Eizo Kakishita
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Degradation Products ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Effective Concentration ◽  
Inhibit Platelet Aggregation ◽  
Platelet Suspension ◽  
Washed Platelet ◽  
Human Platelet Aggregation

SummaryWe investigated the effect of staphylokinase (SAK), which has specific thrombolytic properties, on human platelet aggregation. Platelet aggregation induced with collagen was observed following preincubation of platelets in platelet-rich plasma (PRP) or washed platelet suspension (WP) with SAK at 37° C for 30 min. SAK inhibited platelet aggregation in PRP only at the highest examined concentration (1 x 10-4 g/ml). Although SAK did not inhibit platelet aggregation in WP which contained fibrinogen, it did when the platelets had been preincubated with SAK and plasminogen. The most effective concentration in WP was 1 x 10-6 g/ml. The effect could be inhibited by adding aprotinin or α2-antiplasmin. The highest generation of plasmin in the same preincubation fluid was detected at 1 x 10-6 g/ml SAK. We concluded that SAK can inhibit platelet aggregation in WP by generating plasmin and/or fibrinogen degradation products, but is only partially effective in PRP because of the existence of α2-antiplasmin.

Differential Ability of Agonists to Express Distinct Pools of Fibrinogen (Gpllb/llla) Receptors which Can Mediate the Aggregation of Human Platelets

1989 ◽  
Vol 62 (03) ◽  
pp. 955-961 ◽  
Author(s):  
Ian S Watts ◽  
Rebecca J Keery ◽  
Philip Lumley
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Surface Membrane ◽  
Blood Platelet ◽  
Human Platelets ◽  
Membrane Glycoprotein ◽  
Platelet Surface ◽  
Human Platelet Aggregation ◽  
Differential Ability ◽  
Blood Platelet Aggregation

SummaryWe have investigated the effect of two procedures that modify human platelet surface membrane glycoprotein (Gp) IIb and IIIa complexes upon whole blood platelet aggregation to a range of agonists. (A) Irreversible disruption of complexes by temporary (30 min) Ca2+-deprivation with EGTA at 37° C. (B) Binding of a monoclonal antibody M148 to the complex. EGTA exposure abolished aggregation to ADP, adrenaline and PAF. In contrast, full aggregation curves to collagen and U-46619 could still be established. EGTA exposure reduced M148 binding to platelets by 80%. Excess M148 abolished aggregation to ADP, PAF, collagen and U-46619. However, upon removal of unbound antibody from platelets full aggregation curves to collagen and U-46619 but not to ADP and PAF could be re-established. Thus human platelet aggregation to ADP, PAF and adrenaline appears absolutely dependent upon surface membrane GpIIb/IIIa complexes. In contrast, collagen and U-46619 cause expression of an additional distinct pool of Gp complexes inaccessible to EGTA and M148 in unstimulated platelets which is intimately involved in aggregation to these agonists.

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.

MECHANISMS OF PLATELET AGGREGATION BY ACIDIC MUCOPOLYSACCHARIDE EXTRACTED FROM STICHOPUS JAPONICUS SELENKA IN HUMANS AND RABBITS

1987 ◽  
Author(s):  
J Z Li ◽  
E C-Y Lian
Keyword(s):  
Platelet Aggregation ◽  
Ammonium Sulfate ◽  
Human Platelets ◽  
Platelet Inhibitors ◽  
Rabbit Plasma ◽  
Human Fibrinogen ◽  
Stichopus Japonicus ◽  
Saturated Ammonium Sulfate ◽  
Rabbit Platelets ◽  
Induced Aggregation

It has been reported that acidic mucopolysaccharide extracted from sea cucumber (Stichopus japonicus selenka) (SJAMP) induced the aggregation of human and animal platelets by an unknown mechanism, using platelet-rich plasma (prp) and washed human and rabbit platelets we studied the effects of storage, platelet inhibitors, and various plasmas and their fractions on SJAMP-induced platelet aggregation. we found that the lowest concentrations of SJAMP required for aggregation of human and rabbit platelets were 0.4 and 2 ug/ml respectively. The reactivity of human platelets to SJAMP decreased with time after drawing of blood; rabbit platelets did not show this phenomenon. Platelet inhibitors such as aspirin, indomethacin, apyrase, antimycin, 2-deoxy-D-glucose, and EDTA inhibited by 50 to 100% the aggregation of human platelets induced by SJAMP; but these inhibitors had no effect on SJAMP-induced aggregation of rabbit platelets. Washed human and rabbit platelets were not aggregated by SJAMP. The aggregation of washed human platelets by SJAMP was restored completely by human or rabbit plasma, by human fibrinogen, or by 0 to 30% saturated ammonium sulfate fraction but not by serum. The aggregation of rabbit platelets by SJAMP could only be restored by rabbit plasma or serum, or by 50 to 60% saturated ammonium sulfate fraction. The data indicate that the mechanisms of aggregation of human and rabbit platelets by SJAMP are different. THe SJAMP-induced human platelet aggregation is dependent upon metabolism, release of ADP and the cyclooxygenase pathway requiring fibrinogen and Ca++. The aggregation of rabbit platelets induced by SJAMP is independent of metabolism, release of ADP and cyclooxygenase pathway, and does not require fibrinogen and Ca++, but needs certain protein(s) in the 50 to 60% saturated ammonium sulfate fraction of rabbit plasma.

Dependence of Human Platelet Functional Responses on Divalent Cations: Aggregation and Secretion in Heparin- and Hirudin-Anticoagulated Platelet-Rich Plasma and the Effects of Chelating Agents

1981 ◽  
Vol 45 (02) ◽  
pp. 173-179 ◽  
Author(s):  
Bruce Lages ◽  
Harvey J Weiss
Keyword(s):  
Platelet Aggregation ◽  
Chelating Agents ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Divalent Cations ◽  
Normal Subjects ◽  
Concentration Addition ◽  
Functional Responses ◽  
Induced Aggregation

SummaryThe dependence of ADP- and epinephrine-induced platelet aggregation and secretion on extracellular divalent cations was examined by quantitating these responses in citrate-, heparin-, and hirudin-anticoagulated platelet-rich plasma. ADP-induced 14C-5HT secretion in heparin-PRP and hirudin-PRP was generally decreased, relative to that in citrate-PRP, without corresponding reductions in aggregation, whereas in response to epinephrine, both aggregation and secretion were decreased in heparin-PRP, and abolished in hirudin-PRP. In heparin-PRP, but not in hirudin-PRP, the degree to which these responses were altered was highly variable among normal subjects, and was dependent on the anticoagulant concentration. Addition of citrate restored the extent of ADP-induced secretion and of epinephrine-induced aggregation and secretion in heparin-PRP to that observed in citrate-PRP, and increased the extent of ADP-induced secretion in hirudin-PRP. Addition of EDTA or EGTA, however, had no effect on ADP-induced secretion in heparin-PRP. These results suggest that ADP-induced aggregation and secretion, as well as responses to ADP vs. epinephrine, have different dependencies on extracellular or surface-bound divalent cations. The variable responses observed in heparin-PRP may reflect direct interactions of heparin with platelets, and this variability may account for the conflicting results of previous studies.

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