Related Experiment Video

Updated: Aug 7, 2026

Procoagulant Platelet Characterization by Measuring Phosphatidylserine Exposure and Microvesicle Release from Human Purified Platelets
05:49

Procoagulant Platelet Characterization by Measuring Phosphatidylserine Exposure and Microvesicle Release from Human Purified Platelets

Published on: November 29, 2024

Pathogenetic analysis of three cases with a bleeding disorder characterized by defective platelet aggregation induced

I Fuse1, W Higuchi, Y Uesugi

  • 1First Department of Internal Medicine, Niigata University School of Medicine, 1-757 Asahimachi, Niigata 951-8510, Japan. fuse@med.niigata-u.ac.jp

British Journal of Haematology
|March 22, 2001
PubMed

Insights

Three patients showed defective platelet aggregation due to impaired calcium ionophore response, despite normal thromboxane A2 (TXA2) production. This platelet dysfunction affects bleeding tendencies and reveals a defect distal to key signaling pathways.

Area of Science:

  • Hematology
  • Molecular Biology
  • Biochemistry

Background:

  • Platelet aggregation is crucial for hemostasis.
  • Defective platelet function can lead to bleeding disorders.
  • Understanding signaling pathways in platelet activation is vital.

Observation:

  • Three patients presented with bleeding tendencies.
  • Platelet aggregation induced by calcium ionophore A23187 was significantly reduced.
  • Aggregation responses to ADP, collagen, arachidonic acid, and stable TXA2 were also impaired.

Findings:

  • Normal thromboxane A2 (TXA2) production was observed.
  • Ristocetin- and thrombin-induced platelet aggregation were unaffected.
  • Normal inositol 1,4,5-triphosphate formation and calcium mobilization occurred.
  • Phosphorylation of pleckstrin and myosin light chain (MLC) was normal.

Implications:

  • The defect appears downstream of protein kinase C activation, calcium mobilization, and MLC phosphorylation.
  • This suggests a novel mechanism of platelet dysfunction.
  • Further research is needed to pinpoint the exact molecular defect.

More Related Videos

Analyzing Platelet Subpopulations by Multi-color Flow Cytometry08:04

Analyzing Platelet Subpopulations by Multi-color Flow Cytometry

Published on: June 10, 2025

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation04:37

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation

Published on: May 23, 2025

Related Concept Videos

Anticoagulant Drugs: Low-Molecular-Weight Heparins01:30

Anticoagulant Drugs: Low-Molecular-Weight Heparins

Hemostasis is a crucial process that prevents excessive blood loss from damaged blood vessels. It involves various mechanisms such as vasoconstriction, platelet adhesion and activation, and fibrin formation. The importance of each mechanism depends on the type of vessel injury. In contrast, thrombosis is the abnormal formation of a blood clot within the blood vessels, leading to potential complications if the clot obstructs blood flow. Thrombosis can be caused by increased coagulability of the...
Structure and Function of Platelets01:18

Structure and Function of Platelets

The cell fragments known as platelets are disc-shaped, with an average diameter of about 3 μm and a thickness of roughly 1 μm. They play a crucial role in the body's vascular clotting system, which also involves plasma proteins, blood cells, and blood vessel tissues.
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000 platelets, with...
Introduction to Hemostasis01:05

Introduction to Hemostasis

Hemostasis is a complex physiological process that prevents excessive bleeding when a blood vessel is injured. It's crucial for maintaining the integrity of the circulatory system, as it ensures that our blood remains fluid while still within the vascular network and yet clots to prevent blood loss upon vessel injury.
The three phases of hemostasis involve many clotting factors present in plasma and several substances released by platelets and injured tissue cells. It is a fast, localized, and...
Formation of the Platelet Plug01:22

Formation of the Platelet Plug

The platelet phase, the second stage of hemostasis, commences around 15-20 seconds after an injury. It follows and overlaps with the vascular phase, during which blood vessels constrict to minimize blood loss.
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
Extrinsic and Intrinsic Pathways of Hemostasis01:20

Extrinsic and Intrinsic Pathways of Hemostasis

Blood clotting or coagulation involves extrinsic and intrinsic pathways, which ultimately merge into the common pathway, forming a fibrin clot.
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
Disorders of Hemostasis01:24

Disorders of Hemostasis

Hemostasis, the process that stops bleeding after a blood vessel injury, is crucial for maintaining the integrity of the circulatory system. However, disorders of hemostasis can disrupt this delicate balance, leading to either excessive clotting or bleeding. These disorders can be broadly classified into thromboembolic disorders and bleeding disorders.
Thromboembolic Disorders
Two factors primarily cause thromboembolic conditions.