Abstract
Protein C is a vitamin K-dependent anticoagulant plasma zymogen. In plasma protein C there is an inactive precursor, but it is converted to a serine protease called activated protein C through a catalyzing reaction of the thrombin-thrombomodulin complex.
Protein C deficiency is known to be associated with a risk factor for thrombosis. In this paper plasma protein C levels were studied in healthy Japanese adults and patients with cerebral infarction with respect to antigenicities and biological activities. Some relationship between the level of plasma protein C and the occurrence of cerebral infarction was found. Protein C antigen was measured with enzyme-linked immuno-sorbent assay and enzymatic activity with a new amidolytic method. This amidolytic measurement was free from the influence of thrombin-a2macroglobulin complex of protein C like fraction and protein C inhibitors.
In healthy Japanese adults, there was no significant difference in plasma protein C levels between subjects of different ages. The plasma protein C levels in patients with cerebral infarction, however, was found to be significantly lower than those in Japanese adults.
The protein C level did not correlate with clinical courses or location of the infarction on CT-scan: no significant difference was recognized in the plasma antigen and enzymatic activity of protein C between patients with acute or subacute cerebral infarction or with lesions in the cortical or perforating arteries.
The protein C level was significantly lower in patients with severe symptoms, at onset than in those with mild symptoms and in patients with bad clinical courses.
It was suggested that the low level of plasma protein C has some relevance to the occurrence of cerebral infarction and, furthermore, that a low protein C level at the first attack might indicate poor prognosis with likelihood of relapse.
