The modulation of phosphosphingolipid synthesis by vitamin K depletion has been observed in the vitamin K-dependent microorganism, Bacteriodes levii. When cultured briefly without the vitamin, a reduction occurred in the activity of the first enzyme of the sphingolipid pathway, 3-ketodihydrosphingosine synthase. In this report, 16-day-old mice were treated with the vitamin K antagonist, warfari...

BACKGROUND Combinations of aspirin, clopidogrel, and vitamin K antagonists are widely used in patients after myocardial infarction. However, data for the safety of combinations are sparse. We examined the risk of hospital admission for bleeding associated with different antithrombotic regimens. METHODS By use of nationwide registers from Denmark, we identified 40 812 patients aged 30 years or...

Editorial The key question of vitamin K nutrition in humans may be how much is enough. As with other vitamins, the answer could depend on which biological effect is observed. Vitamin K was first discovered as an antihemorrhagic factor, and it is now known to be required for the synthesis of several proteins involved in blood coagulation (prothrombin; Factors VII, IX, and X; proteins S and C). O...