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Vitamin K was originally identified as an essential cofactor for activation of blood coagulants, and thereafter, it was found to activate anti-coagulants as well. Thus, vitamin K has now been recognized to play pivotal roles in the regulation of blood coagulation system by through participating into γ-glutamyl carboxylation of several vitamin K-dependent proteins. As a momentum with the finding of its bone-fracture healing potency, it became evident that vitamin K is deeply involved in the calcification of skeletal tissues and vasculatures, resulting in the discoveries of osteocalcin, matrix gla protein (MGP) or protein S in these tissues. Intriguingly, osteocalcin in bone promotes calcification while MGP in cardiovascular endothelial cells inhibits calcification. This phenomenon resembles the vitamin K actions on coagulants and anticoagulants in the blood coagulation system, and makes us feel that complicated regulatory systems via interacting with vitamin K may exist in the body. Beyond carboxylation, vitamin K has been found to modulate the transcription factor (Msx2)-related gene expression via binding to nuclear receptor (SXR/PXR) in target cells. These findings should contribute to the elucidation of novel molecular mechanism of vitamin K action on the inhibition of cancer cell proliferation, the suppression of cancer cell metastasis and invasion, and the induction of apoptosis not only in cancer cells but also in normal cells.

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In prokaryotes, C-atom of formate is incorporated into the C-2 atom of the pyrimidine moiety of thiamin, while in eukaryotes, it is incorporated into the C-4 atom. We confirmed the incorporation of the C-atom of formate into the C-4 atom of the pyrimidine portion in mitochondria as well as in cytosol of Saccharomyces cerevisiae, which means, the thiamin in mitochondria was biosynthesized via the eukaryotic biosynthetic pathway, not the prokaryotic pathway. While the question remains of whether the thiamin in mitochondria was biosynthesized in situ or transported from the cytoplasm, we were able to confirm that the thiamin in mitochondria of S. cerevisiae was synthesized via eukaryotic pathway.

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We measured the plasma vitamin C concentrations in 370 smoking and 533 nonsmoking males. In our 11 studies the mean values of smokers were distributed from 0.39 to 0.59mg/100mL, the total mean value being 0.52mg/l00mL. The mean values of nonsmokers were distributed from 0.55 to 0.86mg/100mL, the total mean value being 0.76mg/l00mL. With plasma vitamin C concentrations, the percentages of smokers to nonsmokers were distributed from 57〜84%, the total mean value being 68%. In conclusion, the plasma vitamin C concentrations of smokers are average 68% of those of nonsmokers. Smokers have a vitamin C requirement of approximately 1.5 times greater than that of nonsmokers.

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