Vitamin plasma kinetics

Bode. W., Hekman, P., and van den Berg, H. (1987). Influence of vitamin B-6 nutritional status upon plasma kinetics of PLP after i.v. dosing to rats. In Biochemistry of Vitamin B-6 (T. Korpela, and P. Christen, eds.), pp. 407-410. Birkhaeuser, Boston. 

D von Reinersdorff, E Bush, DJ Liberato. Plasma kinetics of vitamin A in humans after a single oral dose of [8,9,19-13C]retinyl palmitate. J Lipid Res 37 1875-1885,... 

Haskell MJ, Handelman GJ, Peerson JM, Jones AD, Rabbi MA, Awal MA, Wahed MA, Mahalanabis D, Brown KH (1997) Assessment of vitamin A status by the deuterated-retinol-dilution technique and comparison with hepatic vitamin A concentration in Bangladeshi surgical patients. Amer J Clin Nutr 66 61-1A Haskell MJ, Islam MA, Handelman GJ, Peerson JM, Jones AD, Wahed MA, Mahalanabis D, Brown KH (1998) Plasma kinetics of an oral dose of [ H4]retinyl acetate in human subjects with estimated low or high total body stores of vitamin A. Amer J Clin Nutr 68 90-95... 

Epidemiological smdies suggest that hyperhomocysteineima is most significantly correlated with low folate status, but there is also a significant association with low vitamin Bg status (SeUiub et al., 1993). Trials of supplementation have shown that whereas folate supplements lower fasting homocysteine in moderately hyperhomocysteinemic subjects, supplements of 10 mg per day of vitamin Bg have no effect, although supplements do reduce the peak plasma concentration of homocysteine after a test dose of methionine (Ubbink et al., 1994 Ubbink, 1997 Dierkes et al., 1998). This can probably be explained on the basis of the kinetics of the enzymes involved the of cystathionine... 

After Underwood wondered in 1977 whether we could use kinetic methods to estimate vitamin A disposal rate in the rat, we collaborated on an in vivo kinetic experiment in vitamin A-deficient and control rats (Lewis et al, 1981). We measured plasma [ HJvitamin A disappearance for 48 hr after intravenous administration of pH]retinol-labeled plasma and used graphical methods to calculate vitamin A disposal rate. The results sug-... 

Many short-term kinetic studies have been reported on the basis of plasma and senun folate levels in humans. Typical protocols involve the administration of a folate tracer dose to folate-saturated subjects or else a large folate dose given to subjects of more normal folate status (Reich and Gonczy, 1979 Bunni et aL, 1989 Wolfrom et al, 1990 Priest et al, 1991 von der Porten et al, 1992). Although these studies have clinical relevance with respect to the short-term kinetics of acute doses of the vitamin (e.g., postchemotherapy 5-formyl-tetrahydrofolate), they often provide little or no information about the major body folate pool that exhibits much slower kinetics. 

Thermospray is said to be inherently unstable and Watson et al. (159) suggested that this technique might never be suitable for routine plasma vitamin D metabolite measurement. This view, however, was not endorsed by Vreeken et al. (118), who suggested that their system was sufficiently sensitive for the measurement of vitamin D and several of its metabolites but not for l,25-(OH)2D3, which would still require large volumes of plasma. Vicchio et al. (160) have used this technique to measure 25-OH-D3 and study its kinetics. 

In summary, plasma lipoproteins are dynamic structures that transport lipids in the circulation. They also contain important minor components such as vitamins and environmentally derived contaminants. The studies of lipoprotein dynamics suggest that many aspects of the metabolism of the triglyceride-rich lipoproteins are kinetically limited. For the smaller lipoproteins, such as HDL and LDL that have relatively long life times in the circulation, the structure of these lipoproteins reflect a thermodynamic equili-... 

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