Abstract
Summary
Marked species variations in the staphylocoagulation phenomenon are encountered and can be explained in terms of several factors. Comparing with rabbit plasma as an empirical standard (shortest staphylocoagulation times encountered), the ability to shorten staphylocoagulation time by addition of co-factor (human serum albumin) is evidence for lesser amounts of cofactor in such plasmas as horse and bovine. Cofactor cannot be recovered completely or uniformly in plasma fractions obtained with the classical (NH4)2 SO4 salting procedures. Nevertheless, the “albumin” is consistently rich in cofactor (for activation of prostaphylocoagulase) and devoid of thrombin (which interferes in tests on some euglobulins).
Excess of inhibitor (s), in part at least directed against active staphylocoagulase as shown by pre-incubation of prostaphylocoagulase with cofactor before adding to plasma (or plasma dilution + fibrinogen) is a feature of some plasmas, notably rat and chicken. Owing to this, the demonstration of cofactor requires plasma fractionation, in these instances.
Fibrinogenolytic and possibly other proteolytic effects may interfere with tests, especially at higher (37°C) temperatures, and are exemplified in guinea-pig and dog plasmas.
The quantitative evaluation of staphylocoagulation times must, therefore, take cognizance of variability not only in the two bacterial factors but, even more significantly, in the various plasma factors on which they operate in the systems devised for testing the staphylocoagulation and proteolytic 9 phenomena. There are marked species differences in these plasma factors.
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