VITAMINS 



221 



by severe hemorrhages, but this is now very effectively prevented by 

 prior administration of vitamin K, either by injection or by use of a 

 water-soluble derivative which is easily absorbed. The deficiency of 

 prothrombin associated with certain intestinal conditions — for example, 

 obstruction and severe diarrheal diseases such as ulcerative colitis, sprue, 

 and celiac disease — also responds to treatment with compounds possess- 

 ing antihemorrhagic activity. 



Since the concentration of prothrombin in the blood of a newborn 

 baby is quite low, a large percentage of deaths during the first few days 

 of life are due to hemorrhages resulting from injuries suffered at birth. 

 Fortunately, however, investigations have revealed that prothrombin 

 levels may be markedly increased within a short time by administra- 

 tion of vitamin K to the newborn. Administration of vitamin K to the 

 mother prior to childbirth has been shown to raise the level of prothrombin 

 in the foetus. These treatments should effect a drastic reduction in 

 mortality of infants due to hemorrhage. The hereditary disease, hemo- 

 philia, does not respond to treatment with vitamin K. 



A substance, dicumarol, which has a specific antagonistic effect toward 

 vitamin K has been found in improperly cured sweet-clover hay. If 

 freshly cut, partially dried, sweet clover is piled up for a few days, it 

 undergoes a fermentation during which coumarin, a normal component 

 of the hay, is converted into dicumarol. The chemical formulas of these 

 substances are indicated below: 



The blood of cattle eating such hay soon loses its normal clotting power, 

 with the result that any injury is followed by severe and often fatal 

 bleeding. Dicumarol was discovered by Link and co-workers. 



The administration of dicumarol to experimental animals or man inter- 

 feres with the formation of prothrombin, so that the result is similar to 

 that of vitamin K deficiency. In fact, it is now well established that 

 extra doses of the vitamin will counteract the effect of dicumarol, and 

 vice versa. Neither substance affects the clotting power of blood in vitro, 

 that is, if added after the blood is removed from the body. Dicumarol 

 has been put to good use clinically to reduce the danger of the forma- 

 tion of blood clots inside the blood vessels following surgery. 



A chemically related substance, sold under the trade name "Warfarin," 

 is an effective poison for rats and mice. It acts by causing fatal hemor- 

 rhages. Warfarin's advantages for this purpose are that the effects are 



