The demonstration by Martius and Nitz-Litzow (4), and Martius (5), that vitamin K1 may play a functional role in oxidative phosphorylation in animals has led to an increased interest in the participation of vitamin Ki and related quinones in electron transport, oxidative phosphorylation, and photosynthetic phosphorylation. Since vitamin K1 is altered by the action of ultraviolet radiation (6), ...

This study investigated the incidences of undercarboxylated (protein induced by vitamin K absence: PIVKA) prothrombin and protein C in 496 neonates across a wide range of gestational ages. These findings are related to vitamin K1 levels (an indicator of cofactor availability) and vitamin K1 epoxide levels (a measure of the efficiency of the hepatic vitamin K cycle). PIVKA protein C was present ...

The demonstration by Martius and Nitz-Litzow (4), and Martius (5), that vitamin K1 may play a functional role in oxidative phosphorylation in animals has led to an increased interest in the participation of vitamin Ki and related quinones in electron transport, oxidative phosphorylation, and photosynthetic phosphorylation. Since vitamin K1 is altered by the action of ultraviolet radiation (6), ...

If gamma-carboxylation, by the vitamin K1 - cycle, of glutamate residues of bone-matrix peptides is essential for the formation of bone, the circulating levels of this vitamin might indicate the potential efficiency of this process. Methods involving HPLC with electrochemical detection have very recently been developed for assaying the low levels of vitamin K1 that occur in normal plasma. Using...

A liquid chromatographic (LC) method is described for the determination of vitamin K1 in medical foods. The sample is enzymatically digested with lipase and alpha-amylase and extracted with 1% sodium bicarbonate solution-isopropanol (1 + 1). After C18 solid-phase extraction, vitamin K1 is separated by nonaqueous reversed-phase LC, converted to the hydroquinone by postcolumn zinc reduction, and ...

Suboptimal vitamin D status is common among humans, and might increase bone resorption with subsequent negative effects on bone health. Fatty fish, including Atlantic salmon, is an important dietary vitamin D source. However, due to a considerable change in fish feed composition, the contribution of vitamin D from salmon fillet has been reduced. The main objective was to investigate if intake o...

An extraction technique is described for vitamin K1 in medical foods, using accelerated solvent extraction (ASE) in conjunction with matrix solid-phase dispersion (MSPD). The medical food sample is treated as it would be with MSPD extraction, followed by ASE for a hands-free automated extraction. The vitamin K1 in the ASE extract is then quantitated by reversed-phase liquid chromatography with ...

A liquid chromatographic method for vitamin K1 in milk-based infant formula is described. The vitamins are extracted from infant formula by matrix solid-phase dispersion and quantitated by reversed-phase chromatography with fluorescence detection. Vitamin K1 is converted to the fluorescent hydroquinone with a postcolumn zinc reductive reactor. The limit of detection is 12 pg, and the limit of q...

By CHARLES W. MUSHErF, KANE L. KELLEY AND RALPH HLRSCHMANN H YPOPROTHROMBINEMIA, resulting from simple vitamin K lack such as occurs in dietary deficiency in the chick or in absorptive difficulties in man, responds almost equally well to treatment with vitamin K1 (2-methyl3-phytyl-1,4-naphthoquinone) or Menadione (2-methyl-1,4-naphthoquinone) and water-soluble Menadione analogues.13 That this m...

Vitamin K1 was determined in a variety of foods by using reversed-phase liquid chromatography with a C30 column followed by post-column reduction to the fluorescent hydroquinone derivatives. Lipids were removed by lipase digestion, followed by single extraction into hydrocarbon, and the protocol was extended to selected natural and processed foods. Biologically active trans- and inactive ci-vit...