Time and Temperature Dependent Changes of Platelet Aggregation

ADP-, collagen and epinephrine-induced aggregation change markedly if citrate blood or PRP are kept at different incubation temperatures or/and if the time interval between blood sampling and testing varies. With a growing time interval the response of PRP to ADP, collagen or epinephrine increases. Desaggregation after ADP-aggregation decreases with time. If PRP is incubated at 4°C or 10°C aggregation is increased in comparison with room temperature. At 37°C aggregation is markedly inhibited. This inhibitory effect is almost fully reversible several hours after blood sampling. Corresponding results were obtained with PAT III, measuring spontaneous aggregation tendency. Morphologic platelet changes show some correlation with the time and temperature dependent changes of the aggregation pattern. In clinical studies the time interval between blood sampling and testing and the incubation temperature of PRP should be strictly controlled. If enhanced platelet aggregation is to be studied the time interval between venepuncture and performance of the test should be 30 - 60 min for ADP-or collagen-induced aggregation and between 90 and 360 min for PAT III. PRP should always be kept at 20 - 25°C.

Effect of Dipyridamole on Spontaneous Platelet Aggregation in Whole Blood Decreases with the Time After Venepuncture: Evidence for the Role of ADP

10.1055/s-0038-1645978 ◽

1987 ◽

Vol 58 (02) ◽

pp. 744-748 ◽

Cited By ~ 11

Author(s):

A R Saniabadi ◽

G D O Lowe ◽

J C Barbenel ◽

C D Forbes

Keyword(s):

Platelet Aggregation ◽

Correlation Coefficient ◽

Whole Blood ◽

Blood Platelet ◽

Inhibitory Effect ◽

Time Interval ◽

Adp Receptor ◽

Spontaneous Platelet Aggregation

SummarySpontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40 and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37° C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 μM at each time interval; (b) 0.5-100 μM at 3 and 30 minutes and (c) 15 μM in combination with 100 μM adenosine, 8 μM 2-chloroadenosine (2ClAd, an ADP receptor blocker) and 50 μM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 μM Dipy and 10 μM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 μM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

Opposite Effect of Lysine on Platelet Aggregation Induced by Arachidonate and by Other Aggregants

10.1055/s-0038-1657221 ◽

1982 ◽

Vol 48 (01) ◽

pp. 078-083 ◽

Cited By ~ 3

Author(s):

C Ts'ao ◽

S J Hart ◽

D V Krajewski ◽

P G Sorensen

Keyword(s):

Platelet Aggregation ◽

Secondary Phase ◽

Aminocaproic Acid ◽

Adenosine Diphosphate ◽

Inhibitory Effect ◽

Human Platelets ◽

Primary Phase ◽

High Doses ◽

The Many ◽

SummaryEarlier, we found that ε-aminocaproic acid (EACA) inhibited human platelet aggregation induced by adenosine diphosphate (ADP) and collagen, but not aggregation by arachidonic acid (AA). Since EACA is structurally similar to lysine, yet these two agents exhibit vast difference in their antifibrinolytic activities, we chose to study the effect of lysine on platelet aggregation. We used L-lysine-HCl in these studies because of its high solubility in aqueous solutions while causing no change in pH when added to human plasma. With lysine, we repeatedly found inhibition of ADP-, collagen- and ristocetin-induced aggregation, but potentiation of AA-induced aggregation. Both the inhibitory and potentiation effects were dose-dependent. Low doses of lysine inhibited the secondary phase of aggregation; high doses of it also inhibited the primary phase of aggregation. Potentiation of AA-induced aggregation was accompanied by increased release of serotonin and formation of malondialdehyde. These effects were not confined to human platelets; rat platelets were similarly affected. Platelets, exposed to lysine and then washed and resuspended in an artificial medium not containing lysine, remained hypersensitive to AA, but no longer showed decreased aggregation by collagen. Comparing the effects of lysine with equimolar concentrations of sucrose, EACA, and α-amino-n-butyric acid, we attribute the potent inhibitory effect of lysine to either the excess positive charge or H+ and C1− ions. The -NH2 group on the α-carbon on lysine appears to be the determining factor for the potentiation effect; the effect seems to be exerted on the cyclooxygenase level of AA metabolism. Lysine and other chemicals with platelet-affecting properties similar to lysine may be used as a tool for the study of the many aspects of a platelet aggregation reaction.

Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

10.26686/wgtn.17059868 ◽

2021 ◽

Author(s):

◽

Kelly Maree Hare

Keyword(s):

Hatching Success ◽

Incubation Temperature ◽

Unit Length ◽

Condition Index ◽

Egg Laying ◽

Maternal Influence ◽

Temperature Dependent ◽

Sprint Speed ◽

Fitness Traits ◽

Incubation Temperatures

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

Inhibition of Human Platelet Aggregation by the Proteolytic Effect of Streptokinase (SK). Role of the Factor VIII Related Antigen

10.1055/s-0039-1689380 ◽

1975 ◽

Cited By ~ 1

Author(s):

R. Castillo ◽

S. Maragall ◽

J. A. Guisasola ◽

F. Casals ◽

C. Ruiz ◽

...

Keyword(s):

Platelet Aggregation ◽

Factor Viii ◽

Platelet Rich Plasma ◽

Gel Filtration ◽

Inhibitory Effect ◽

Factor Viii Related Antigen ◽

Human Factor Viii ◽

Defective ADP-induced platelet aggregation has been observed in patients treated with streptokinase. This same effect appears “in vitro” when adding SK to platelet rich plasma (PRP). Classic hemophilia and normal platelet poor plasmas (PPP) treated with SK inhibit the aggregation of washed platelets; plasmin-treated normal human serum also shows an inhibitory effect on platelet aggregation. However, von Willebrand SK-treated plasmas do not inhibit the aggregation of washed platelets. The same results appear when plasmas are previously treated with a rabbit antibody to human factor VIII.This confirms that the antiaggregating effect is mainly linked to the digested factor VIII related antigen.The inhibition of ADP-induced platelet aggregation has been proved in gel filtration-isolated and washed platelets from SK-treated PRP.Defective ristocetin-induced platelet aggregation has also been observed- This action does not appear in washed platelets from SK-treated PRP in presence of normal PPP, but it does in presence of SK-treated PPP, which suggests that the inhibition of the ristocetin-induced aggregation is due to the lack of factor VIII and not to the factor VIII-related products.Heparin, either “in vivo” or “in vitro”, has corrected the antiaggregating effect of SK.

Ex vivo evaluation of anti-GPVI antibody in Cynomolgus monkeys: Dissociation between anti-platelet aggregatory effect and bleeding time

10.1160/th06-05-0266 ◽

2006 ◽

Vol 96 (08) ◽

pp. 167-175 ◽

Cited By ~ 27

Author(s):

Yutaka Matsumoto ◽

Hisao Takizawa ◽

Kazuhiro Nakama ◽

Xiaoqi Gong ◽

Yoshihisa Yamada ◽

...

Keyword(s):

Platelet Aggregation ◽

Bleeding Time ◽

Ex Vivo ◽

Thrombus Formation ◽

Inhibitory Effect ◽

Bleeding Tendency ◽

Fab Fragment ◽

Dose Escalation Study ◽

Cynomolgus Monkeys ◽

SummaryRecent progress in the understanding of thrombus formation has suggested an important role of glycoprotein (GP)VI. In contrast to its pivotal role in collagen-induced platelet activation, it has been suggested that its blockade does not induce massive bleeding tendency. To demonstrate the dissociation between inhibitory effect on platelet aggregation and bleeding by GPVI blockade, we examined the effects of Fab fragment of OM2, an anti-human GPVI monoclonal antibody on ex vivo collagen-induced platelet aggregation and skin bleeding time after intravenous injection in cynomolgus monkeys. In a dose-escalation study, OM2 potently (>80%) inhibited collagen-induced platelet aggregation at the cumulative dose of 0. 2 mg/kg with a slight prolongation of bleeding time (1. 3 times baseline value). Furthermore, at 18. 8 mg/kg, the highest dose tested, prolongation of bleeding time was still mild (1. 9 times). In contrast, abciximab, Fab fragment of anti-GPIIb/IIIa antibody prolonged bleeding time by 5. 0 times at 0. 35 mg/kg, the lowest effective dose on platelet aggregation. Ina pharmacodynamic study,a bolus injection of OM2 at 0. 4 mg/kg produced potent inhibition of collagen-induced aggregation up to six hours after injection, showing longer half-life than that of abciximab. The injection of OM2 Fab did not induce thrombocytopenia and GPVI depletion in monkeys. These results suggest that blockade of GPVI by antibody can exerta potent inhibitory effect on collagen-induced platelet aggregation with a milder prolongation of bleeding time than blockade of GPIIb/IIIa. This study indicates that OM2 has the potential to be developed as a new class of therapeutic tool.

Cigarette Smoke Extract Inhibits Platelet Aggregation by Suppressing Cyclooxygenase Activity

TH Open ◽

10.1055/s-0037-1607979 ◽

2017 ◽

Vol 01 (02) ◽

pp. e122-e129

Author(s):

Hitoshi Kashiwagi ◽

Koh-ichi Yuhki ◽

Yoshitaka Imamichi ◽

Fumiaki Kojima ◽

Shima Kumei ◽

...

Keyword(s):

Platelet Aggregation ◽

Cigarette Smoke ◽

Platelet Function ◽

Inhibitory Effect ◽

Cigarette Smoke Extract ◽

Human Platelets ◽

Receptor Subtypes ◽

Ic50 Value ◽

Induced Aggregation ◽

Cox 1

AbstractThe results of studies that were performed to determine whether cigarette smoking affects platelet function have been controversial, and the effects of nicotine- and tar-free cigarette smoke extract (CSE) on platelet function remain to be determined. The aim of this study was to determine the effect of CSE on platelet aggregation and to clarify the mechanism by which CSE affects platelet function. CSE inhibited murine platelet aggregation induced by 9,11-dideoxy-9α,11α-methanoepoxy-prosta-5Z,13E-dien-1-oic acid (U-46619), a thromboxane (TX) A2 receptor agonist, and that induced by collagen with respective IC50 values of 1.05 ± 0.14% and 1.34 ± 0.19%. A similar inhibitory action of CSE was also observed in human platelets. CSE inhibited arachidonic acid–induced TXA2 production in murine platelets with an IC50 value of 7.32 ± 2.00%. Accordingly, the inhibitory effect of CSE on collagen-induced aggregation was significantly blunted in platelets lacking the TXA2 receptor compared with the inhibitory effect in control platelets. In contrast, the antiplatelet effects of CSE in platelets lacking each inhibitory prostanoid receptor, prostaglandin (PG) I2 receptor and PGE2 receptor subtypes EP2 and EP4, were not significantly different from the effects in respective control platelets. Among the enzymes responsible for TXA2 production in platelets, the activity of cyclooxygenase (COX)-1 was inhibited by CSE with an IC50 value of 1.07 ± 0.15% in an uncompetitive manner. In contrast, the activity of TX synthase was enhanced by CSE. The results indicate that CSE inhibits COX-1 activity and thereby decreases TXA2 production in platelets, leading to inhibition of platelet aggregation.

Prostaglandins and Platelet Function in Diabetes

10.1055/s-0039-1687328 ◽

1979 ◽

Author(s):

J. García-Conde ◽

J.A. Amado ◽

J. Merino ◽

I. Benet

Keyword(s):

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Normal Subjects ◽

Inhibitory Effect ◽

Rat Aorta ◽

Diabetic Group ◽

Diabetic Patients ◽

Prostaglandin I2 ◽

Induced Aggregation ◽

Normal Controls

We have studied platelet aggregation induced by 0,5 mM. Araquidonic acid (AA) addition to platelet-rich-plasma (PRP) from 21 insulin treated diabetic patients and in 21 non-diabetic controls. The velocity of aggregation was significantly higher in the diabetic group. There was no differences in the velocity of aggregation in patients with or without retinopathy.The incubation of PRP of normal subjects at 37- during 5 minutes with 5,8 10-4 M. Imidazole changed the pattern of aggregation: The velocity of aggregation was slower and appeared a wave of disaggregation. Imida zole had not effect on aggregation in the diabetic group. This data add support to the findings published by COLWLLL showing that platelets from diabetics have hyperactive AA metabolism. Prostaglandin I2 (PGI2) obtained from rat aorta shows an inhibitory effect on ADP or AA induced aggregation. This effect is less marked in diabetic PRP than in PRP of normal controls. PGI2 release in platelet-poor-plasma from diabetics is normal. This can represent a resistance ot diabetic platelet to the anti aggregating effect of PGI 2. A similar finding was also appreciated with the PGE1 in three out of six patients so tar stu

Temperature-dependent sex-biased embryo mortality in a bird

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2008.0954 ◽

2008 ◽

Vol 275 (1652) ◽

pp. 2703-2706 ◽

Cited By ~ 28

Author(s):

Yvonne A Eiby ◽

Jessica Worthington Wilmer ◽

David T Booth

Keyword(s):

Low Temperatures ◽

Incubation Temperature ◽

Sex Ratios ◽

Molecular Sexing ◽

Temperature Dependent ◽

Female Embryo ◽

Male Embryo ◽

Diverse Range ◽

Embryo Mortality ◽

Incubation Temperatures

Sex ratios have important evolutionary consequences and are often biased by environmental factors. The effect of developmental temperature on offspring sex ratios has been widely documented across a diverse range of taxa but has rarely been investigated in birds and mammals. However, recent field observations and artificial incubation experiments have demonstrated that the hatching sex ratio of a megapode, the Australian brush-turkey ( Alectura lathami ), varied with incubation temperature; more females hatched at high incubation temperatures and more males hatched at low temperatures. Here, we investigated the causes of this temperature-dependent sex-biasing system. Molecular sexing of chicks and embryos confirmed that male embryo mortality was greater at high temperatures while female embryo mortality is greater at low temperatures, with mortality in both sexes similar at intermediate incubation temperatures. Temperature-dependent sex-biased embryo mortality represents a novel mechanism of altering sex ratios in birds. This novel mechanism, coupled with the unique breeding biology of the brush-turkey, offers a potentially unparalleled opportunity in which to investigate sex allocation theory in birds.

Endothelium-derived relaxing factor inhibits thrombin-induced platelet aggregation by inhibiting platelet phospholipase C

Blood ◽

10.1182/blood.v79.1.110.bloodjournal791110 ◽

1992 ◽

Vol 79 (1) ◽

pp. 110-116

Author(s):

W Durante ◽

MH Kroll ◽

PM Vanhoutte ◽

AI Schafer

Keyword(s):

Platelet Aggregation ◽

Phospholipase C ◽

Calcium Concentration ◽

Umbilical Vein ◽

Inhibitory Effect ◽

Human Platelets ◽

Relaxing Factor ◽

Kinase C ◽

Endothelium Derived Relaxing Factor ◽

Endothelium-derived relaxing factor (EDRF) inhibits platelet function, but the mechanism underlying this inhibitory effect is not known. To examine this, cultured acetylsalicylic acid (ASA)-treated endothelial cells (EC) from bovine aorta (BAEC) or from human umbilical vein (HUVEC) were incubated with washed, ASA-treated human platelets. Incubation of platelets with either BAEC or HUVEC resulted in inhibition of thrombin-induced platelet aggregation that was dependent on the number of EC added. This effect was potentiated by superoxide dismutase and reversed by treating EC with NG-nitro-L-arginine or by treating platelets with methylene blue, indicating that the inhibition of platelet aggregation was due to the release of EDRF by EC. EC significantly blocked the thrombin stimulated breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2) and the production of phosphatidic acid in [32P]orthophosphate-labeled platelets and of inositol trisphosphate in [3H]myoinositol-labeled platelets. In addition, the thrombin-mediated activation of protein kinase C (PKC) and phosphorylation of myosin light chain were inhibited in the presence of EC. Finally, thrombin stimulated an increase in cytosolic ionized calcium concentration ([Ca2+]i) in fura2-loaded platelets that was abolished by concentrations of EC which also blocked thrombin- induced aggregation. These data indicate that EDRF blocks thrombin- induced platelet aggregation by inhibiting the activation of PIP2- specific phospholipase C and thereby suppressing the consequent activation of PKC and the mobilization of [Ca2+]i.

The Relationship between Platelet Aggregation and Time Interval after Venepuncture

10.1055/s-0038-1649151 ◽

1974 ◽

Vol 31 (01) ◽

pp. 133-141 ◽

Cited By ~ 19

Author(s):

Charles Warlow ◽

Anne Corina ◽

D Ogston ◽

A. S Douglas

Keyword(s):

Platelet Aggregation ◽

Time Interval ◽

Second Phase ◽

Aggregation And Disaggregation ◽

Induced Aggregation ◽

The Relationship

SummaryThe relationship between the rate of platelet aggregation and the time interval after venepuncture has been studied. Considerable changes in the rates of aggregation and disaggregation of platelets in citrated plasma take place between 30 and 120 minutes after venepuncture. There is a reduction in the rates of irreversible ADP-induced aggregation, the first and second phase of the double wave of ADP-induced aggregation, disaggregation after reversible ADP-induced aggregation, collagen-induced aggregation and the second phase of the double wave of adrenaline-induced aggregation. In contrast, the rate of the first wave of adrenaline-induced aggregation increases with time after venepuncture. 5-HT induced aggregation appears to be unaffected. These effects were not due to changes in the pH of the plasma. It is suggested that any attempt to quantify platelet aggregation during the comparison of groups of individuals, or in the study of the effect of anti-platelet drugs in single individuals must take into account the time interval between venepuncture and the measurement of platelet aggregation.