Platelets and experimental scurvy

Fibrinogen coagulation without thrombin: reaction with vitamin C and copper(II)

We describe a novel method for inducing fibrinogen derived clots. The addition of vitamin C (0.1-1 mM) to a solution of fibrinogen (1 mg/ml) and Cu(II) (20-150 microM) results in protein coming out of solution. This phenomenon can be "read" by fibrometers as "clotting time". The reaction requires Cu(II) and can be prevented by a chelating agent, such as citrate, as well by a hydroxyl radical scavenger, such as mannitol. The insoluble protein, called "neofibe", is soluble in 4 M urea and 2% SDS. Isoelectric focusing and SDS-electrophoretic comparison of native fibrinogen with neofibe reveal molecular modifications of the starting protein. This reaction is an interesting example of a free radical mediated transformation of soluble protein into insoluble material. Some findings on the connection between hemostasis, vitamin C and Cu(II) are discussed.

Clinical evaluation of the patient with bruising and bleeding

Abnormal bleeding or bruising is frequently encountered in the clinical practice of dermatology. A working knowledge of mechanisms of normal hemostasis, a complete history (general, bleeding, familial), a thorough physical examination, and an appropriate laboratory evaluation are the integral steps in the diagnostic process. Cutaneous bruising and/or bleeding may be a manifestation of a previously unrecognized hereditary coagulation deficiency such as mild hemophilia or von Willebrand's disease (vWD), hereditary or acquired qualitative or quantitative platelet disorder, disturbance of the vascular or supporting structure, or it may be due to one of several acquired systemic disorders.