PHYSIOLOGIC ROLE OF VITAMIN K 



765 



Table 1 

 Characteristics of Several Common Types of Bleeding" 



" Adapted from W. H. Sebrell, Jr., and R. S. Harris, The Vitamins, Volume II, Acad. 

 Press, New York, 1954, p. 420. 



'' Unless there is a coexisting vitamin K deficienc}^ 



of ecchymoses associated with mild trauma and, in surgical cases, by 

 hematomas and persistent bleeding at the site of the operation. Massive 

 hemorrhage may occur within the muscles and beneath the skin, partic- 

 ularly in the extremities.^-" For an extensive study of the gross and 

 microscopic features of experimental vitamin K deficiency, the reader is 

 referred to the article of Ferraro and Roizin.^-- 



d. Various Factors Associated with Vitamin K and with the Clotting 

 Mechanism. Dam and S0ndergaard^2^ discovered that, when chicken 

 plasma from vitamin K-deficient chicks was added to dicumarol plasma, 

 the prothrombin time of the latter was reduced. Conversely, the clotting 

 time of the chicken plasma was shortened by the addition of dicumarol 

 plasma. S0rbye et a/.^-^ succeeded in concentrating the active factor from 

 oxalated plasma of vitamin K-deficient chicks. It was called factor k; its 

 adsorption characteristics resemble those of prothrombin, but it was foimd 

 to be distinctly different from the latter protein. It also differs from the 

 labile factor in chicken plasma corresponding to factor V of mammalian 

 plasma. It is believed that the synthesis of this factor k is independent of 

 vitamin K. 



In a later study, S0rbye and co-workers'-" concentrated a factor in di- 



'" A. Ferraro and L. Roizin, Am. J. Pathol., 22, 1109-1179 (1946). 

 ''•^ H. Dam and K. S0ndergaard, Biochim. Biophys. Acta, 2, 409-41.3 (1948). 

 •2^ 0. S0rbye, I. Kruse, and H. Dam, Ada Chem. Scayid., 4, 549-550 (1950). 

 •^ 0. S0rbye, I. Kruse, and H. Dam, Ada Chem. Scand., 4, 831-832 (1950). 



