Diagnosis of protein C deficiency in patients on oral anticoagulant treatment: comparison of three different functional protein C assays.

The efficacy of three different protein C activity assays and of protein C antigen determination for the diagnosis of protein C deficiency was studied in 13 protein C deficient patients (11 with type I, 2 with type II deficiency) and in 51 presumably non-deficient patients (control group), both groups being on oral anticoagulant (OAC) treatment. For protein C activity measurement (1) the assay according to Francis (slightly modified) with thrombin activation and measurement of activated protein C in the aPTT system, (2) an assay using Protac activation and chromogenic substrate (Protac-CS) and (3) an assay using Protac activation and the aPTT system (Protac-PTT) were used. Protein C antigen was determined by Laurell immunoelectrophoresis.

Specific attachment of desmin filaments to desmosomal plaques in cardiac myocytes.

Intercellular junctions which are similar in ultrastructure and protein composition to typical desmosomes have so far only been found in epithelial cells and in heart tissue, specifically in the intercalated disks of cardiac myocytes and at cell boundaries between Purkinje fiber cells. In epithelial cells the cytoplasmic side of desmosomes, the 'desmosomal plaque', represents a specific attachment structure for the anchorage of intermediate filaments (IF) of the cytokeratin type. Cardiac myocytes do not contain cytokeratin filaments.