Effect of Temperature on ADP-Induced Platelet Aggregation

1973 ◽  
Vol 29 (01) ◽  
pp. 183-189
Author(s):  
C. A Praga ◽  
E. M Pogliani
Keyword(s):  
Platelet Aggregation ◽  
Incubation Period ◽  
Room Temperature ◽  
Important Variable ◽  
Practical Significance ◽  
Effect Of Temperature ◽  
Induce Platelet Aggregation ◽  
Cuvette Holder ◽  
Exact Temperature

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.

Effect of Temperature on Incubation Time for Spontaneous Morphology Change in Electrodeposited Copper Metallization

2005 ◽  
Vol 863 ◽  
Author(s):  
S. Ahmed ◽  
D.N. Buckley ◽  
S. Nakahara ◽  
Y. Kuo
Keyword(s):  
Incubation Period ◽  
Incubation Time ◽  
Annealing Time ◽  
Room Temperature ◽  
Diffusion Mechanism ◽  
Systematic Investigation ◽  
Effect Of Temperature ◽  
Copper Metallization ◽  
Morphology Change ◽  
A Value

AbstractA systematic investigation of the effect of annealing time and temperature on the incubation period for spontaneous morphology change (SMC) in electrodeposited copper metallization is reported. The incubation time is greatly reduced at higher temperatures. At each temperature, the remaining incubation time at room temperature was found to decrease approximately linearly with increasing annealing time. An Arhennius plot of the measured rates of decrease showed good linearity and yielded a value of 0.48 eV for the activation energy. This is consistent with a vacancy diffusion mechanism for the process occurring during the incubation period and supports our proposed mechanism for SMC.

Synergism Between Platelet Aggregating Agents: Possible Trigger Mechanisms During Hemostatic Plug And/Or Thrombus Formation

1981 ◽  
Author(s):  
S C Wong ◽  
G A Rock
Keyword(s):  
Platelet Aggregation ◽  
Serine Protease ◽  
Protease Inhibitors ◽  
Synergistic Effects ◽  
Thrombus Formation ◽  
Thrombotic Event ◽  
Atp Release ◽  
Serine Protease Inhibitors ◽  
Induce Platelet Aggregation

number of in-vitro studies have shown that various pair-combinations of aggregating agents such as ADP, epinephrine, collagen, thrombin, arachidonate and ionophore A 23187 can produce synergistic responses to induce platelet aggregation and release reactions. We have also produced synergistic effects by combining much lower doses of 3 or more aggregating agents and found markedly enhanced responses. It appears that the potential for synergistic effects is based both on the combination of the various agents and on the amount of each agent used for stimulation. Epinephrine is the most potent agent among them, although fibrinogen and Ca++ play a very important role. Indomethacin, ASA, PGE 1, and synthetic serine protease inhibitors (carboxylate and sulphonate analog) completely inhibit the platelet aggregation and release response. Of particular interest is the fact that addition of as little as 0.04% of the usual aggregating dose of epinephrine in the presence of 4% of collagen, 2% of thrombin and 10% of the normal plasma level of fibrinogen will initiate a marked response both of platelet aggregation and ATP release. This suggests a possible mechanism whereby acute insults such as stress or exercise, with release of epinephrine, can precipitate a thrombotic event in a patient who has normal or near-normal circulating levels of fibrinogen but who also has exposure of a very limited amount of the vascular endothelium (thereby exposing collagen). Since the effects of the acute insults of epinephrine secretion can be blocked by the presence of indomethacin, ASA, PGE 1 and specific serine protease inhibitors, prostaglandin synthesis must play a major role in this reaction.

scholarly journals Novel Antibodies Against Glycoprotein Ibα Inhibit Pulmonary Metastasis By Affecting Vwf-Gpibα Interaction

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1133-1133
Author(s):  
Qi Yingxue ◽  
Wenchun Chen ◽  
Ke Xu ◽  
Fengying Wu ◽  
Xuemei Fan ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Binding Sites ◽  
Tumor Metastasis ◽  
Cancer Metastasis ◽  
Platelet Glycoprotein ◽  
Induce Platelet Aggregation ◽  
Metastasis Model

Abstract Background: Platelet glycoprotein Ibα (GPIbα) extracellular domain, which is part of the receptor complex GPIb-IX-V, plays an important role in tumor metastasis. However, the mechanism through which GPIbα participates in the metastatic process remains unclear. In addition, potential bleeding complication remains an obstacle for the clinical use of anti-platelet agents in cancer therapy. Methods and Results: To generate antibodies that bind to mouse platelet GPIbα, washed mouse platelet lysate was used as the antigen for rat immunization. Obtained hybridoma clones were screened in ELISA for binding affinity to the GPIb-IX complex. Positive clones were further screened for their abilities to inhibit platelet-cancer cell adhesion. Finally, at static condition, two antibodies, 2B4 and 1D12, had virtually no effect on the activation of integrin αIIbβ3, which is used to indicate platelet activation. Then, we characterized the binding sites of 2B4 and 1D12 by 20 purified recombinant GPIbα fragments binding. Results showed that 2B4 and 1D12 shared the same binding sites with vWF. To determine whether 2B4 and 1D12 affect vWF binding, we tested the binding by flow cytometry using recombined mouse vWF, and then, we investigated platelet aggregation induced by several agonists, including vWF binding agonist ristocetin. Our data demonstrated clearly that 2B4 and 1D12 could inhibit vWF binding. To investigate whether the inhibition of vWF-GPIbα interaction was associated with tumor metastasis, we examined the effect of 2B4 and 1D12 in each of the following interactions in vitro: between activated platelets and tumor cells, platelets and endothelial cells. Meanwhile, We further investigated the inhibitory effect of these antibodies in vivo using the experimental metastasis model and the spontaneous metastasis model. Results showed that 2B4 and 1D12 could potently inhibit the adhesion of cancer cells in vitro, and metastasisin vivo. We next investigated whether 2B4 and 1D12 could affect platelet activation and/or induce thrombocytopenia in vivo. Results showed that the addition of 2B4 or 1D12 to PRP did not induce platelet aggregation and injection of 2B4 or 1D12 Fab at appropriate dose did not affect tail-bleeding time and platelet count. Based on the above findings, we obtained anti-human platelet GPIbα monoclonal antibody YQ3 using the same approach to explore the role of human GPIbα in cancer metastasis. As expected, YQ3 inhibited lung cancer adhesion and demonstrated similar value in metastasis. More importantly, for all three mAbs in our study, none of their Fabs induced thrombocytopenia. Conclusion: Our results therefore supported the hypothesis that GPIbα contributes to tumor metastasis, and suggested potential value of using anti-GPIbα mAb to suppress cancer metastasis. Disclosures Li: Neoletix: Consultancy, Equity Ownership.

In Vitro and In Vivo Effects of Adrenaline and Phentolamine on Platelet Function

1978 ◽  
Vol 40 (02) ◽  
pp. 428-438 ◽  
Author(s):  
Oreste Ponari ◽  
Emilio Civardi ◽  
Alessandro Megha ◽  
Mario Pini ◽  
Raffaele Poti’ ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Threshold Concentration ◽  
Two Phase ◽  
Platelet Factor ◽  
Induce Platelet Aggregation ◽  
In Vivo Effects ◽  
In Vivo Administration

Summary In vitro and in vivo effects of adrenaline (ADR) on platelet aggregation, on platelet factor 3 (PF3) availability and on platelet factor 4 (PF4) release were studied in man. Inhibitory action of an alpha-blocker, phentolamine (PHEN) was investigated in the same conditions.The threshold concentration (TC) of ADR inducing the typical two-phase response in aggregation tests when added to platelet-rich plasma (PRP) varied in different pools of plasma, but always induced an evident PF4 release and increased PF3 availability. A further increase in both parameters was obtained with higher concentrations but without any significant dose/response correlation.Adding PHEN alone to PRP did not induce platelet aggregation or modify PF4 release induced by stirring, but it reduced PF3 availability. On the other hand, PHEN prevented the effects of ADR in different platelet tests, at appropriate concentrations.Intravenous infusion of ADR lowered the TC, and increased PF3 availability and PF4 release. In vivo administration of PHEN, in contrast, increased TC and reduced PF3 availability, while PF4 remained unchanged.

scholarly journals Thrombopoietin as Biomarker and Mediator of Cardiovascular Damage in Critical Diseases

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Enrico Lupia ◽  
Alberto Goffi ◽  
Ornella Bosco ◽  
Giuseppe Montrucchio
Keyword(s):  
Platelet Aggregation ◽  
Research Group ◽  
Burn Injury ◽  
Pathogenic Role ◽  
Cigarette Smokers ◽  
Induce Platelet Aggregation ◽  
Cardiovascular Damage ◽  
Proliferation And Differentiation

Thrombopoietin (TPO) is a humoral growth factor originally identified for its ability to stimulate the proliferation and differentiation of megakaryocytes. In addition to its actions on thrombopoiesis, TPO directly modulates the homeostatic potential of mature platelets by influencing their response to several stimuli. In particular, TPO does not induce platelet aggregationper sebut is able to enhance platelet aggregation in response to different agonists (“priming effect”). Our research group was actively involved, in the last years, in characterizing the effects of TPO in several human critical diseases. In particular, we found that TPO enhances platelet activation and monocyte-platelet interaction in patients with unstable angina, chronic cigarette smokers, and patients with burn injury and burn injury complicated with sepsis. Moreover, we showed that TPO negatively modulates myocardial contractility by stimulating its receptor c-Mpl on cardiomyocytes and the subsequent production of NO, and it mediates the cardiodepressant activity exertedin vitroby serum of septic shock patients by cooperating with TNF-αand IL-1β. This paper will summarize the most recent results obtained by our research group on the pathogenic role of elevated TPO levels in these diseases and discuss them together with other recently published important studies on this topic.

Platelet Aggregation Induced by DAS in Vitro: Some Investigations on Its Mechanism of Action

1974 ◽  
Vol 31 (02) ◽  
pp. 354-362
Author(s):  
K. U Benner ◽  
K. A Schumacher ◽  
H. G Classen
Keyword(s):  
Platelet Aggregation ◽  
Mechanism Of Action ◽  
Active Substance ◽  
Platelet Rich Plasma ◽  
The Other ◽  
Second Phase ◽  
Induce Platelet Aggregation ◽  
Release Reaction

SummaryThe effect of the depressor active substance (DAS) on platelets of men, cats, pigs, dogs, rats, and rabbits has been studied by the method of Born (1962). DAS was found to induce platelet aggregation only in human and feline platelet rich plasma (PRP). Nevertheless, there are some striking similarities between platelet aggregation induced by DAS and ADP (i.e. inhibition by the same compounds, such as adenosine, tosylarginine methylester, or p-chloromercuribenzoic acid). The species specifity and a marked tachyphylactic action on platelets of both species makes DAS clearly discernible from all the other aggregation inducing substances which have been studied so far. From additional experiments there is evidence that DAS acts on human and cat platelets via a release reaction of cellular substances known to enhance platelet aggregation in a second phase. This process is strongly dependent on the presence of Ca++.

scholarly journals Inhibition of coagulation and thrombin-induced platelet activities by a synthetic dodecapeptide modeled on the carboxy-terminus of hirudin

Blood ◽  
1990 ◽  
Vol 75 (2) ◽  
pp. 399-406 ◽  
Author(s):  
JA Jakubowski ◽  
JM Maraganore
Keyword(s):  
Platelet Aggregation ◽  
Antithrombin Iii ◽  
Thromboxane A2 ◽  
Serotonin Release ◽  
Dependent Manner ◽  
Thrombin Time ◽  
Platelet Factor ◽  
Induce Platelet Aggregation ◽  
Apparent Lack

A synthetic, tyrosine-sulfated, dodecapeptide (BG8865) modeled on residues 53–64 of hirudin was found to elevate the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) of human plasma in a dose-dependent manner. The most sensitive assay was the TT, which was prolonged 2 and 3 times control values at 2.2 and 4.1 micrograms/mL hirudin peptide, respectively. The sulfated dodecapeptide exhibited no dependency on antithrombin III as monitored by the APTT in the presence of sheep anti-human antithrombin III antibodies, and its activity was not neutralized by platelet releasates or platelet factor 4. In studies of thrombin-induced platelet activation, the hirudin peptide was found to block aggregation, serotonin release and thromboxane A2 generation. At thrombin concentrations of 0.25 U/mL, the IC50 (concentration resulting in 50% inhibition) for inhibition of platelet aggregation was 0.72 micrograms/mL peptide. Inhibition of TXA2 generation and serotonin release correlated closely with inhibition of aggregation. Using platelets from patients with clinically documented heparin-induced thrombocytopenia anticoagulant doses of heparin were found to induce platelet aggregation and thromboxane A2 generation. In sharp contrast, anticoagulant-equivalent doses of hirudin peptide had no effect on patient platelets, as evidenced by a lack of platelet aggregation and thromboxane A2 generation. These data provide compelling in vitro evidence that the hirudin peptide has several potential advantages over heparin, namely effective inhibition of thrombin-induced platelet activities, co-factor independence, insensitivity to endogenous heparin- neutralizing factors, and an apparent lack of direct or immune-mediated platelet stimulating properties.

ADP induces partial platelet aggregation without shape change and potentiates collagen-induced aggregation in the absence of Gαq

Blood ◽  
2000 ◽  
Vol 96 (6) ◽  
pp. 2134-2139 ◽  
Author(s):  
Philippe Ohlmann ◽  
Anita Eckly ◽  
Monique Freund ◽  
Jean-Pierre Cazenave ◽  
Stefan Offermanns ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Adenylyl Cyclase ◽  
Ex Vivo ◽  
Shape Change ◽  
Induce Platelet Aggregation ◽  
Cyclic Amp Accumulation ◽  
Simultaneous Activation ◽  
High Concentrations ◽  
Induced Aggregation

Platelets from Gαq knockout mice are unable to aggregate in response to physiological agonists like adenosine 5′-diphosphate (ADP), thromboxane A2, thrombin, or collagen, although shape change still occurs in response to all of these agonists except ADP. ADP-induced platelet aggregation results from simultaneous activation of the purinergic P2Y1receptor coupled to calcium mobilization and shape change and of a distinct P2 receptor, P2cyc, coupled through Gi to adenylyl cyclase inhibition, which is responsible for completion and amplification of the response. P2cyc could be the molecular target of the antithrombotic drug clopidogrel and the adenosine triphosphate (ATP) analogs AR-C69931MX, AR-C67085, and AR-C66096. The aim of the present study was to determine whether externally added ADP could still act through the Gi pathway in Gαq-deficient mouse platelets and thereby amplify the residual responses to agonists such as thrombin or collagen. It was found that (1) ADP and adrenaline still inhibited cyclic AMP accumulation in Gαq-deficient platelets; (2) both agonists restored collagen- but not thrombin-induced aggregation in these platelets; (3) the effects of ADP were selectively inhibited in vitro by the ATP analog AR-C69931MX and ex vivo by clopidogrel and hence were apparently mediated by the P2cyc receptor; and (4) high concentrations of ADP (100 μmol/L) induced aggregation without shape change in Gαq-deficient platelets through activation of P2cyc. Since adrenaline was not able to induce platelet aggregation even at high concentrations, we conclude that the effects of ADP mediated by P2cyc are not restricted to the inhibition of adenylyl cyclase through Gi2.

In Vitro Interaction between Cultured Cells and Human Blood Platelets

1978 ◽  
Vol 40 (01) ◽  
pp. 089-102 ◽  
Author(s):  
Randi Holme ◽  
Reidar Oftebro ◽  
Torstein Hovig
Keyword(s):  
Platelet Aggregation ◽  
Human Blood ◽  
Cultured Cells ◽  
Blood Platelets ◽  
Tumour Cells ◽  
Coagulation Activity ◽  
Induce Platelet Aggregation ◽  
Human Blood Platelets ◽  
Chang Cells

SummaryThe effects of washed human cultured cells (tumour cells and Chang liver cells) on human blood platelets in heparinized plasma were studied. Platelet aggregation was induced by suspensions of the tumour cells. Ultrastructural examination showed that the platelets, especially in the central regions of the aggregates, were tightly packed and the α-granules were mostly present. In the periphery of the aggregates the platelets appeared swollen and devoid of organelles, and fibrin strands were seen. The platelet aggregation was not completely abolished by incubation with apyrase. The washing fluids from the tumour cells also induced platelet aggregation, but the aggregation could be abolished by incubation with apyrase.When three different lines of the Chang cells were used, suspensions of two lines of these cells induced platelet aggregation, but the third line did not. Presence of ADP could be demonstrated in the washing fluids from the cultured cells, except for the one line of Chang cells which did not induce platelet aggregation. The experiments indicated that the platelet aggregation induced by the various types of cells was mediated via ADP, but with a possible additional effect of coagulation activity.

scholarly journals Inhibition of coagulation and thrombin-induced platelet activities by a synthetic dodecapeptide modeled on the carboxy-terminus of hirudin

Blood ◽  
1990 ◽  
Vol 75 (2) ◽  
pp. 399-406
Author(s):  
JA Jakubowski ◽  
JM Maraganore
Keyword(s):  
Platelet Aggregation ◽  
Antithrombin Iii ◽  
Thromboxane A2 ◽  
Serotonin Release ◽  
Dependent Manner ◽  
Thrombin Time ◽  
Platelet Factor ◽  
Induce Platelet Aggregation ◽  
Apparent Lack

Abstract A synthetic, tyrosine-sulfated, dodecapeptide (BG8865) modeled on residues 53–64 of hirudin was found to elevate the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) of human plasma in a dose-dependent manner. The most sensitive assay was the TT, which was prolonged 2 and 3 times control values at 2.2 and 4.1 micrograms/mL hirudin peptide, respectively. The sulfated dodecapeptide exhibited no dependency on antithrombin III as monitored by the APTT in the presence of sheep anti-human antithrombin III antibodies, and its activity was not neutralized by platelet releasates or platelet factor 4. In studies of thrombin-induced platelet activation, the hirudin peptide was found to block aggregation, serotonin release and thromboxane A2 generation. At thrombin concentrations of 0.25 U/mL, the IC50 (concentration resulting in 50% inhibition) for inhibition of platelet aggregation was 0.72 micrograms/mL peptide. Inhibition of TXA2 generation and serotonin release correlated closely with inhibition of aggregation. Using platelets from patients with clinically documented heparin-induced thrombocytopenia anticoagulant doses of heparin were found to induce platelet aggregation and thromboxane A2 generation. In sharp contrast, anticoagulant-equivalent doses of hirudin peptide had no effect on patient platelets, as evidenced by a lack of platelet aggregation and thromboxane A2 generation. These data provide compelling in vitro evidence that the hirudin peptide has several potential advantages over heparin, namely effective inhibition of thrombin-induced platelet activities, co-factor independence, insensitivity to endogenous heparin- neutralizing factors, and an apparent lack of direct or immune-mediated platelet stimulating properties.

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