Acquired von Willebrand's syndrome with IgM inhibitor against von Willebrand's factor.

This report describes a patient without evident underlying disease, in whom an acquired von Willebrand's syndrome was discovered before surgery. Coagulation abnormalities included a borderline bleeding time, a low retention of platelets on glass beads, decreased levels of factor VIII procoagulant activity (VIIIAHF), factor VIII-related antigen (VIIIAg), and ristocetin-induced agglutination cofactor (VIIIVWF). After cryoprecipitate infusion the patient did not have the expected rise and there was no secondary increment in VIIIAHF. The patient was treated with prednisone for three weeks without significant improvement in the laboratory findings. Spontaneous resolution was observed long after this therapy. The haemostatic abnormalities were attributable to the presence of an inhibitor directed against VIIIVWF. The inhibitor was found in the IgM fraction. Its autoimmune nature is probable although we failed to demonstrate any inhibitory effect of Fab obtained from the patient's purified IgM. Despite the lack of inhibitory effect against VIIIAHF and VIIIAg, the low levels of all three activities of the factor VIII complex could be explained by the short half-life of immune complexes between factor VIII and the inhibitor.

Acquired factor VII deficiency associated with pleural liposarcoma.

Isolated acquired factor VII (FVII) deficiency (0.15 U/ml) was identified in a 30-year-old man with pleural liposarcoma. The patient underwent surgery with continuous FVII concentrate infusion. No anti-FVII antibody or FVII/anti-FVII complex was detected. However, the short half-life and low recovery of FVII after concentrate infusion suggested the presence of an antibody. Whatever the mechanism, this FVII deficiency was related to the presence of the liposarcoma. FVII level normalized during tumour regression and fell again when the liposarcoma relapsed.

[Occurrence of lupus-type circulating anticoagulant in syphilis (author's transl)]. / Inhibiteur acquis de la coagulation de type anti-prothrombinase et syphilis récente.

Screening tests for circulating anticoagulant were performed systematically in fifteen patients with different stages of syphilis. The lupus-type anticoagulant, an inhibitor of the prothrombin activator complex, was demonstrated in one primary and three secondary stages, without any hemorrhagic complications. The possible relationship between the occurrence of this type of inhibitor and positive antilipoidal tests is discussed in reference to the well-known association of circulating anticoagulant and biologic false positive serologic tests for syphilis observed in patients with SLE.

[Electra 600 d : results of a three year study (author's transl)]. / Expérience de trois années d'utilisation de l'Electra 600 D.

Electra 600 D has been used in our laboratory for 3 years. The Quick's prothrombine time is the only test routinely performed with satisfactory results. The measure of activated partial thromboplastin time, the assays of factor II, factor V and complex VII + X are unsatisfactory, probably because of the type of the reagents which are used.

Differential stability of two apo-isocytochromes c in the yeast Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae contains two forms of cytochrome c, iso-1-cytochrome c and iso-2-cytochrome c, encoded by the genes CYC1 and CYC7, respectively. The amino acid sequences of these two isozymes are approximately 80% identical. Cyc3- mutants lack both holocytochromes c, because of a deficiency of cytochrome c heme lyase, the enzyme catalyzing covalent attachment of the heme group to apocytochrome c. A deficiency of heme lyase also prevents import into mitochondria. Surprisingly, apo-iso-1-cytochrome c is absent in cyc3- strains, although apo-iso-2-cytochrome c is present at approximately the same level at which holo-iso-2-cytochrome c is found in CYC3+ strains. The lack of apo-iso-1-cytochrome c is not due to a deficiency of either transcription or translation, but to rapid degradation of the protein. Apocytochromes c encoded by composite cytochrome c genes composed of the central portion of iso-2-cytochrome c flanked by amino and carboxyl regions of iso-1-cytochrome c exhibit increased stability compared with apo-iso-1-cytochrome c. A region encompassing no more than four amino acid differences between iso-1- and iso-2-cytochromes c is sufficient to partially stabilize the protein. In contrast to what is observed in vivo with the apo forms, the holo forms of the composite isocytochromes c are even less stable to thermal denaturation than iso-1-cytochrome c or iso-2-cytochrome c. Either a small region of the sequence of apo-iso-1-cytochrome c is involved in degradation of the protein, or the corresponding region in apo-iso-2-cytochrome c is preventing degradation. The differential stability of the two isocytochromes c may be part of a regulatory process that increases the proportion of iso-2-cytochrome c under certain physiological conditions.

Prothrombin Poissy: a new variant of human prothrombin.

A new congenital dysprothrombinaemia is described in a newborn baby girl who presented severe bleeding from the second day of life. Routine coagulation tests showed very prolonged prothrombin time and activated partial thromboplastin time with about 2% prothrombin activity in a one-stage assay. Staphylocoagulase and Echis carinatus venom prothrombin assays were respectively 35% and 25%. The prothrombin antigen level was 47% and its migration in crossed immuno-electrophoresis was abnormal. Family study revealed the presence of both normal and abnormal prothrombin in the plasma of three family members: the father, the mother and the brother. Thrombin generation in a system free from natural inhibitors showed that the abnormal prothrombin was slowly and incompletely activated. The propositus is thought to be homozygous for a 'lazy' dysprothrombin.