Platelet Aggregation, Malondialdehyde Generation and Production Time in Children with Sickle Cell Anaemia

SummaryIn view of prior reports of platelet activation in the sickling disorders, platelet aggregation, malondialdehyde (MDA) production following stimulation with N-ethylmaleimide, and/or production time (survival) measurements were examined in 44 children with homozygous sickle cell disease. Aggregation in response to epinephrine, collagen, and adenosine diphosphate was similar to or only slightly less than in normal black controls, rendering highly unlikely the circulation of a sizable population of refractory or “exhausted” platelets. The platelets from the normal blacks aggregated less in response to epinephrine than those from white control subjects. MDA generation in sickle cell platelets was not increased, and platelet production time was not shortened in 6 patients studied during crisis. These observations do not support the occurrence of a marked degree of platelet activation and consumption in sickle cell anaemia.

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Evaluation Of In Vivo Platelet Activation In Sickle Cell Disease

10.1055/s-0038-1652036 ◽

1981 ◽

Author(s):

E J Watson-Williams ◽

J Westwick ◽

S Krishnamurthi ◽

G Marks ◽

J White ◽

...

Keyword(s):

Platelet Aggregation ◽

Sickle Cell Disease ◽

Platelet Activation ◽

Sickle Cell ◽

Venous Blood ◽

Cell Disease ◽

Platelet Factor ◽

Normal Health ◽

Homozygous Sickle Cell Disease

This study was made to identify indicators of in vivo platelet activation in patients with sickle cell disease. Seven patients, homozygotes for sickle cell haemoglobin and seven age, sex and race matched controls were each studied 2 or 3 times in a six week period of normal health. Venous blood was drawn with minimal use of a tourniquet and, after 5ml was taken for other tests, 2.5ml was collected into ice- cold “Amersham BTG” tubes. The samples were centrifuged at 2,600g for 25 minutes at 4°C and the plasma immediately separated and stored at -20°C until assayed for Betathromboglo- bulin (BTG), platelet factor 4 (PF4), Thromboxane (TXB2) and 6-oxo-PGF1α. Circulating platelet aggregation was measured by the method of Wu and Hoak (1974).BTG was greater than 60ng/ml in 17 of 20 samples from the patients but in only 4 of 17 samples from the controls. This difference remained significant when corrected for the platelet count. In vivo aggregation was above 25% on 8 of 16 occasions in patients and on 3 of 16 occasions in controls. Plasma PF4, TXB2 and 6-oxo-PGF1α levels were not significantly different in the two groups. BTG and in vivo platelet aggregation may be useful parameters with which to assess in vivo platelet activation in patients with homozygous sickle cell disease whilst not in crisis.

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Increased Procoagulant Activity of Red Blood Cells from Patients with Homozygous Sickle Cell Disease and β-Thalassemia

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650577 ◽

1996 ◽

Vol 76 (03) ◽

pp. 322-327 ◽

Cited By ~ 73

Author(s):

Dominique Helley ◽

Amiram Eldor ◽

Robert Girot ◽

Rolande Ducrocq ◽

Marie-Claude Guillin ◽

...

Keyword(s):

Sickle Cell Disease ◽

Red Blood Cells ◽

Sickle Cell ◽

Blood Cells ◽

Annexin V ◽

Mean Value ◽

Procoagulant Activity ◽

Dependent Manner ◽

Cell Disease ◽

Homozygous Sickle Cell Disease

SummaryIt has recently been proved that, in vitro, red blood cells (RBCs) from patients with homozygous β-thalassemia behave as procoagulant cells. The procoagulant activity of β-thalassemia RBCs might be the result of an increased exposure of procoagulant phospholipids (i. e. phosphatidylserine) in the outer leaflet of the membrane. In order to test this hypothesis, we compared the catalytic properties of RBCs of patients with β-thalassemia and homozygous sickle cell disease (SS-RBCs) with that of controls. The catalytic parameters (Km, kcat) of prothrombin activation by factor Xa were determined both in the absence and in the presence of RBCs. The turn-over number (kcat) of the reaction was not modified by normal, SS- or (3-thalassemia RBCs. The Km was lower in the presence of normal RBCs (mean value: 9.1 µM) than in the absence of cells (26 µM). The Km measured in the presence of either SS-RBCs (mean value: 1.6 µM) or β-thalassemia RBCs (mean value: 1.5 pM) was significantly lower compared to normal RBCs (p <0.001). No significant difference was observed between SS-RBCs and p-thalassemia RBCs. Annexin V, a protein with high affinity and specificity for anionic phospholipids, inhibited the procoagulant activity of both SS-RBCs and (3-thalassemia RBCs, in a dose-dependent manner. More than 95% inhibition was achieved at nanomolar concentrations of annexin V. These results indicate that the procoagulant activity of both β-thalassemia RBCs and SS-RBCs may be fully ascribed to an abnormal exposure of phosphatidylserine at the outer surface of the red cells.

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Clinical findings associated with homozygous sickle cell disease in the Barbadian population – do we need a national SCD registry?

BMC Research Notes ◽

10.1186/1756-0500-7-102 ◽

2014 ◽

Vol 7 (1) ◽

Cited By ~ 7

Author(s):

Kim R Quimby ◽

Stephen Moe ◽

Ian Sealy ◽

Christopher Nicholls ◽

Ian R Hambleton ◽

...

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Clinical Findings ◽

Cell Disease ◽

Homozygous Sickle Cell Disease

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Aprotinin: is it prothrombotic?

Perfusion ◽

10.1177/026765910101600510 ◽

2001 ◽

Vol 16 (5) ◽

pp. 401-409 ◽

Cited By ~ 3

Author(s):

M Poullis ◽

R C Landis ◽

K M Taylor

Keyword(s):

Platelet Aggregation ◽

Platelet Activation ◽

Mechanism Of Action ◽

Adenosine Diphosphate ◽

Platelet Membrane ◽

Calcium Flux ◽

Thrombin Receptor ◽

Proteolytic Activation ◽

Agonist Peptide ◽

Receptor Family

Controversy continues as to whether aprotinin (Trasylol) is prothrombotic. The recent discovery of the thrombin receptor family, known as the protease-activated receptor family (PAR) has been essential in aiding our understanding of the mechanism of action of aprotinin. Our results show that aprotinin has no effect on platelet aggregation induced by adrenaline, adenosine diphosphate, phorbol-12-myristate-13-acetate, collagen or PAR 1 agonist peptide. However, aprotinin inhibits thrombin-induced platelet activation as assessed by macroaggregation, microaggregation and platelet membrane calcium flux. Aprotinin inhibits proteolytic activation of platelets, but platelets can still be activated by non-proteolytic mechanisms.

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