Time Dependence of Whole Blood Aggregation in Response to Platelet Activating Factor (PAF)

1988 ◽  
Vol 59 (02) ◽  
pp. 162-163 ◽  
Author(s):  
R R Taylor ◽  
J Strophair ◽  
M Sturm ◽  
R Vandongen ◽  
L J Beilin
Keyword(s):  
Time Dependence ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Sampling Time ◽  
Blood Sampling ◽  
Impedance Aggregometry

SummaryThe aggregation/adhesion response to platelet activating factor (PAF) was studied in diluted whole blood by impedance aggregometry. The extent of aggregation varied directly with the interval between blood sampling and aggregation measurement over the first 30 minutes from sampling, then remained stable for the next 60 minutes of observation. This is an effect opposite to that described for aggregation to PAF in platelet rich plasma which, however, cannot be studied soon after sampling. Time dependence of aggregation is important and comparative measurements should be made during the period of stable aggregability.

Comparison of Rapid Platelet Function Assay with Whole Blood Platelet Impedance Aggregometry for the Definition of Aspirin Resistance.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4018-4018
Author(s):  
Anna M. Dyszkiewicz-Korpanty ◽  
Anne Kim ◽  
James D. Burner ◽  
Eugene P. Frenkel ◽  
Ravindra Sarode
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Blood Platelet ◽  
Aspirin Resistance ◽  
Impedance Aggregometry ◽  
Definition Of ◽  
Induced Aggregation

Abstract The reported incidence of aspirin (ASA) resistance ranges from 5 to 30%. Various platelet function assays have been employed to detect aspirin resistance in patients with cardio- and cerebrovascular disease. Such a high proposed incidence of ASA resistance poses a critical need for a rapid point-of -care (POC) platelet function test. Unfortunately, no uniformly accepted definition of ASA resistance exists. Platelet aggregation studies that have been used to define ASA resistance are time consuming and require special technical expertise. The Ultegra Rapid Platelet Function -ASA (RPFA-ASA) has been developed as a POC test that is performed without sample processing. This optical method measures agglutination of fibrinogen-coated beads upon platelet activation with arachidonic acid. In the presence of aspirin effect, however, the agglutination of the beads is inhibited. The described cutoff of ≥ 550 Aspirin Reaction Units (ARU) is termed non-responsiveness to ASA based on a preclinical study and subsequent correlation with epinephrine-induced platelet aggregation in platelet rich plasma. Since RPFA-ASA uses whole blood, we validated its performance characteristics against a classic whole blood platelet aggregation assay (WBA). We studied 50 healthy volunteers, aged 25–75 (24 men, 26 women) with normal CBC, who had not ingested anti-platelet drugs for 14 days prior to the study. Baseline studies included WBA (dual channel aggregometer, Chrono-log Inc., Havertown, PA) using both arachidonic acid (AA -0.5; 0.25 mM) and collagen (1; 2 μg/mL) as well as an RPFA-ASA assay (Accumetrics Inc., San Diego, CA). These studies were repeated after 3 days of ASA (325 mg/d) intake. Based on a review of the literature, we defined an adequate ASA response as a completely inhibited AA-induced platelet aggregation and at least 30% inhibition of collagen-induced aggregation (both concentrations of the agonist). Thus, those with < 30% inhibition of aggregation response to collagen were considered ASA resistant. Eleven subjects were ASA resistant by WBA (20%; 8 females and 3 males (aged 25–63). In contrast, since all 50 subjects achieved ARU values of < 550 ARU, none were recognized as an ASA non-responder by the RPFA-ASA. While the current cutoff of < 550 ARU posed by the Ultegra RPFA-ASA does identify those who have taken ASA, the assay is unable to recognize ASA non-responders. Thus, based on these data, the appropriate cutoff for the recognition of ASA resistance by the RPFA-ASA should be re-adjusted to a significantly lower level to ensure appropriate assay results.

Levels of Platelet Factor 3 in Citrate Plasma and in Whole Blood as Determined by A Chromogenic Peptide Substrate Assay

1979 ◽  
Author(s):  
H. Sandberg ◽  
A.-K. Gellerbring ◽  
L.-O. Andersson
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Blood Sampling ◽  
Chromogenic Substrate ◽  
Plasma Samples ◽  
Peptide Substrate ◽  
Platelet Factor ◽  
No Release ◽  
Sensitive Method

A newly developed sensitive method for determination of platelet factor 3 (PF 3) using a chromogenic substrate (S 2238) (Sandberg and Andersson, Thromb. Res., in press) was used for comparison of the PF 3 levels in platelet-rich plasma (PRP) in citrate with the levels in PRP in the anticoagulant EDTA/citrate/PCE 1/theophylline. It was shown that in citrate PRP, release of PF 3 was started after about 20 minutes from blood sampling. Release of β-thromboglobulin (β-tg) was found to occur simultaneously with the release of PF 3. No release of PF 3 or β-tg could be detected within 3 hours from blood sampling in PRP in the EDTA/citrate/PCE 1/theophylline anticoagulant.The PF 3 level in whole blood was measured by a method which was a modification of the method used for plasma samples. It was found that, using the same donor, the PF 3 level of plasma and blood in the EDTA/citrate/PCE 1/theophylline anticoagulant was essentially the same. The levels of PF 3 found in blood upon standing in citrate or in EDTA/citrate/PCE 1/theophy11ine anticoagulant were in accordance with the levels found in plasma. Experiments with whole blood without any anticoagulant showed that release of PF 3 begin to occur simultaneously with release of β-tg, about 5 minutes before clotting. Thus the data show that PF 3 and βtg are released in parallel.

Complexes of Nitric Oxide with Nucleophiles as Agents for the Controlled Biological Release of Nitric Oxide: Antiplatelet Effect

1993 ◽  
Vol 70 (04) ◽  
pp. 654-658 ◽  
Author(s):  
Jean G Diodati ◽  
Arshed A Quyyumi ◽  
Nabeen Hussain ◽  
Larry K Keefer
Keyword(s):  
Nitric Oxide ◽  
Aqueous Solution ◽  
Platelet Aggregation ◽  
Sodium Nitroprusside ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agents ◽  
Platelet Inhibition ◽  
Impedance Aggregometry

SummaryNitric oxide (NO) inhibits platelet aggregation. Accordingly, we hypothesized that complexes of diethylamine and spermine with NO (DEA/NO and SPER/NO, respectively), two vasodilators previously shown to release NO spontaneously in aqueous solution, may also be useful antiplatelet agents. Platelet aggregation was measured in whole blood or platelet-rich plasma by impedance aggregometry after addition of collagen. In whole blood, the dose response curve for DEA/NO added 1 min before collagen was similar to that for aspirin (60% inhibition at 10-4 M), while SPER/NO and sodium nitroprusside were less potent by an order of magnitude. In platelet-rich plasma, 10-6 M DEA/NO caused 60% inhibition, while SPER/NO and sodium nitroprusside were as active only at 10-5 M; aspirin’s potency was unchanged from that in whole blood. In vivo, DEA/NO and sodium nitroprusside produced significant platelet inhibition 1 min after intravenous injection in the rabbit at 50 nmol/kg. Similar in vivo platelet inhibition was observed with SPER/NO and aspirin, but only at higher dose. The effects of DEA/NO and sodium nitroprusside were transient, lasting less than 30 min after treatment, while the activity of SPER/NO and aspirin was sustained throughout the 30 min experiment. The magnitude and duration of the antiplatelet effects of DEA/NO and SPER/NO correlate with the rates at which they release nitric oxide spontaneously in aqueous solution. Thus, NO/nucleophile complexes merit further exploration both as research tools and as potential antiplatelet agents.

Levels of platelet factor 3 in citrate plasma and in whole blood as determined by a chromogenic peptide substrate assay

1979 ◽  
Author(s):  
H Sandberg ◽  
A.-K. Gellerbring ◽  
L.-O. Andersson
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Blood Sampling ◽  
Chromogenic Substrate ◽  
Plasma Samples ◽  
Peptide Substrate ◽  
Platelet Factor ◽  
No Release ◽  
Sensitive Method

A newly developed sensitive method for determination of platelet factor 3 (PF 3) using a chromogenic substrate (S 2238) (Sandberg and Andersson, Thromb. Res., in press) was used for comparison of the PF 3 levels in platelet-rich plasma (PRP) in citrate with the levels in PRP in the anticoagulant EDTA/citrate/PGE 1/theophylline. It was shown that in citrate PRP, release of PF 3 was started after about 20 minutes from blood sampling. Release of β-thromboglobulin (β-tg) was found to occur simultaneously with the release of PF 3. No release of PF 3 or β-tg could be detected within 3 hours from blood sampling in PRP in the EDTA/citrate/PGE 1/theophylline anticoagulant.The PF 3 level in whole blood was measured by a method which was a modification of the method used for plasma samples. It was found that, using the same donor, the PF 3 level of plasma and blood in the EDTA/citrate/PGE 1/theophylline anticoagulant was essentially the same. The levels of PF 3 found in blood upon standing in citrate or in EDTA/citrate/PGE 1/theophylline anticoagulant were in accordance with the levels found in plasma. Experiments with whole blood without any anticoagulant showed that release of PF 3 begin to occur simultaneously with release of β-tg, about 5 minutes before clotting. Thus the data show that PF 3 and β-tg are released in parallel.

Effect of Platelet Activating Factor(PAF) on the collagen induced platelet aggregation in whole blood.

1987 ◽  
Author(s):  
Y Oura ◽  
N Sakiyama ◽  
R Ueshima ◽  
M Higuchi ◽  
E Kakishitha ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Creatine Phosphokinase ◽  
Platelet Activating Factor ◽  
Inhibitory Effect ◽  
Platelet Aggregability ◽  
Aggregation Rate ◽  
Impedance Aggregometry ◽  
Specific Antagonist ◽  
Induced Aggregation

Studies of platelet aggregation are generally performed in p1ate1et-rich plasma(PRP) by the transmittance method. Recently, impedance aggregometry has been introduced which shows the platelet aggregability in whole blood. We compared the impedance aggregometry in whole blood with the transmittance method in PRP, with regard to collagen induced platelet aggregation. The aggregation rate in whole blood increased with increasing concentration of collagen, but remained unchanged in PRP. The factors which influence the platelet aggregation rate in whole blood were studied. CV-3988, that is the specific antagonist of PAF, acetylsalicylic acid (ASA) and phosphocreatine / creatine phosphokinase (CP/CPK) were used in order to evaluate the contribution of PAF, thromboxane and ADP in whole blood. CV-3988 dose-dependently inhibited platelet aggregation induced by collagen in whole blood, but did not inhibit the aggregation in PRP. ASA(10mM) inhibited the aggregation in whole blood incompletely too, but completely in PRP. And the inhibition of CP/CPK(CP/CPK : 1.5mM/50U/ml) was very weak in whole blood compared to that of other antagonists. The inhibitory effect of CV-3988 was investigated on the collagen induced platelet aggregation in whole blood which was pretreated with ASA ( 1 OmM ) and CP/CPK (1.5mM/50U/ml), resulting in a collagen induced aggregation in whole blood that was not completely inhibited. We conclude that there are some other different factors, which influence platelet aggregation in whole blood, in addition to thromboxane, ADP and PAF.

Platelet Shape Change in Whole Blood: Differential Effects of Endotoxin

1994 ◽  
Vol 71 (05) ◽  
pp. 646-650 ◽  
Author(s):  
M L Nystrom ◽  
M A Barradas ◽  
J Y Jeremy ◽  
D P Mikhailidis
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Platelet Activating Factor ◽  
Final Concentration ◽  
Platelet Volume ◽  
Differential Effects ◽  
Platelet Shape

SummaryThe effect of endotoxic lipopolysaccharide (LPS) on platelet shape change (PSC; a preaggregation event) was investigated. PSC is accompanied by an increase in median platelet volume (MPV), which was measured using a channelyzer. In whole blood, but not in platelet rich plasma (PRP), LPS (final concentration 80 mg/1) caused an increase in MPV that could be detected for 2 h. When PRP (prepared from LPS- and saline-pretreated whole blood) was incubated for 40 min, the LPS-mediated increase in MPV could no longer be detected. Taken together, these data imply that PSC is both initiated and maintained by a labile factor(s) present in whole blood, but not in PRP.PRP was prepared from LPS-pretreated whole blood and incubated for 40 min to allow reversal of the LPS-induced PSC; further stimulation with LPS caused PSC. Platelets from LPS-pretreated whole blood also showed enhanced PSC with seioloum (J-HT), diminished PSC with platelet activating factor (PAF), and no change of response to ADP and collagen. Hence, LPS pretreatment of whole blood differentially alters responses of platelets to further stimulation with LPS and other agonists. A specific PAF antagonist completely abolished the effect of LPS on MPV. These data may contribute to an understanding of the cascading thrombotic events and thrombocylopeuia assoeialed wiib septicaemia.

Phospholipase C from Clostridium Perfringens Induces Human Platelet Aggregation in Plasma

1988 ◽  
Vol 59 (02) ◽  
pp. 236-239 ◽  
Author(s):  
Giovanna Barzaghi ◽  
Chiara Cerletti ◽  
Giovanni de Gaetano
Keyword(s):  
Platelet Aggregation ◽  
Receptor Antagonist ◽  
Phospholipase C ◽  
Clostridium Perfringens ◽  
Human Platelet ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Inhibitory Effect ◽  
Thromboxane Receptor Antagonist

SummaryWe studied the aggregating effect of different concentrations of phospholipase C (PLC) (extracted from Clostridium perfringens) on human platelet-rich plasma (PRP). PRP was preincubated with PLC for 3 min at 37° C and the platelet aggregation was followed for 10 min. The threshold aggregating concentration (TAG) of PLC was 3-4 U/ml.We also studied the potentiation of PLC with other stimuli on platelet aggregation. Potentiating stimuli, such as arachidonic acid (AA), ADP. Platelet Activating Factor (PAF) and U-46619 (a stable analogue of cyclic endoperoxides) were all used at subthreshold concentrations. We also studied the possible inhibitory effect of aspirin, apyrase, TMQ, a prostaglandin endoper- oxide/thromboxane receptor antagonist and BN-52021, a PAF receptor antagonist. Only aspirin and apyrase were able to reduce aggregation induced by PLC alone and PLC + AA and PLC + ADP respectively. TMQ and BN-52021 were inactive. In ex vivo experiments oral aspirin (500 mg) partially inhibited platelet aggregation induced by PLC alone, PLC + AA and PLC + ADP 2 and 24 h after administration. Aspirin 20 mg for 7 days also reduced aggregation induced by PLC + AA.

Macroaggregation of Platelets in Plasma, as Distinct from Microaggregation in Whole Blood (and Plasma), as Determined Using Optical Aggregometry and Platelet Counting respectively, is Specifically Impaired following Cardiopulmonary Bypass in Man

1994 ◽  
Vol 72 (04) ◽  
pp. 511-518 ◽  
Author(s):  
Valentine C Menys ◽  
Philip R Belcher ◽  
Mark I M Noble ◽  
Rhys D Evans ◽  
George E Drossos ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Platelet Count ◽  
Cardiopulmonary Bypass ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Interquartile Range ◽  
Contributory Factor ◽  
Platelet Aggregability ◽  
Aggregate Growth

SummaryWe determined changes in platelet aggregability following cardiopulmonary bypass, using optical aggregometry to assess macroaggregation in platelet-rich plasma (PRP), and platelet counting to assess microaggregation both in whole blood and PRP. Hirudin was used as the anticoagulant to maintain normocalcaemia.Microaggregation (%, median and interquartile range) in blood stirred with collagen (0.6 µg/ml) was only marginally impaired following bypass (91 [88, 93] at 10 min postbypass v 95 (92, 96] prebypass; n = 22), whereas macroaggregation (amplitude of response; cm) in PRP stirred with collagen (1.0µg/ml) was markedly impaired (9.5 [8.0, 10.8], n = 41 v 13.4 [12.7,14.3], n = 10; p <0.0001). However, in PRP, despite impairment of macroaggregation (9.1 [8.5, 10.1], n = 12), microaggregation was near-maximal (93 [91, 94]), as in whole blood stirred with collagen. In contrast, in aspirin-treated patients (n = 14), both collagen-induced microaggregation in whole blood (49 [47, 52]) and macroaggregation in PRP (5.1 [3.8, 6.6]) were more markedly impaired, compared with control (both p <0.001).Similarly, in PRP, macroaggregation with ristocetin (1.5 mg/ml) was also impaired following bypass (9.4 [7.2, 10.7], n = 38 v 12.4 [10.0, 13.4]; p <0.0002, n = 20), but as found with collagen, despite impairment of macroaggregation (7.2 [3.5,10.9], n = 12), microaggregation was again near-maximal (96 [93,97]). The response to ristocetin was more markedly impared after bypass in succinylated gelatin (Gelo-fusine) treated patients (5.6 [2.8, 8.6], n = 17; p <0.005 v control), whereas the response to collagen was little different (9.3 v 9.5). In contrast to findings with collagen in aspirin-treated patients, the response to ristocetin was little different to that in controls (8.0 v 8.3). Impairment of macroaggregation with collagen or ristocetin did not correlate with the duration of bypass or the platelet count, indicating that haemodilution is not a contributory factor.In conclusion: (1) Macroaggregation in PRP, as determined using optical aggregometry, is specifically impaired following bypass, and this probably reflects impairment of the build-up of small aggregates into larger aggregates. (2) Impairment of aggregate growth and consolidation could contribute to the haemostatic defect following cardiac surgery.

Haemostatic Platelet Plug Formation in the Isolated Rabbit Mesenteric Preparation - An Analysis of Red Blood Cell Participation

1980 ◽  
Vol 44 (01) ◽  
pp. 006-008 ◽  
Author(s):  
D Bergqvist ◽  
K-E Arfors
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
In Vitro Test ◽  
Pharmacological Agents ◽  
Vitro Test ◽  
Releasing Effect ◽  
Plug Formation

SummaryIn a model using an isolated rabbit mesenteric preparation microvessels were transected and the time until haemostatic plugs formed was registered. Perfusion of platelet rich plasma gave no haemostasis whereas whole blood did. Addition of chlorpromazine or adenosine to the whole blood significantly prolonged the time for haemostasis, and addition of ADP to the platelet rich plasma significantly shortened it. It is concluded that red cells are necessary for a normal haemostasis in this model, probably by a combination of a haemodynamic and ADP releasing effect.The fundamental role of platelets in haemostatic plug formation is unquestionable but there are still problems concerning the stimulus for this process to start. Three platelet aggregating substances have been discussed – thrombin, adenosine diphosphate (ADP) and collagen. Evidence speaking in favour of thrombin is, however, very minimal, and the discussion has to be focused on collagen and ADP. In an in vitro system using polyethylene tubings we have shown that "haemostasis" can be obtained without the presence of collagen but against these results can be argued that it is only another in vitro test for platelet aggregation (1).To be able to induce haemostasis in this model, however, the presence of red blood cells is necessary. To further study this problem we have developed a model where haemostatic plug formation can be studied in the isolated rabbit mesentery and we have briefly reported on this (2).Thus, it is possible to perfuse the vessels with whole blood as well as with platelet rich plasma (PRP) and different pharmacological agents of importance.

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