E uptake

Mardones, P and Rigotti, A, 2004. Cellular mechanisms of vitamin E uptake Relevance in alpha-tocopherol metabolism and potential implications for disease. J Nutr Biochem 15, 252-260. 

Traber, M. G. et al. (1990). Vitamin E uptake by human intestinal cells during lipolysis in vitro. Gastroenterology 98(1) 96-103. 

Trivially, photo-excitation will drastically enhance the oxidation potential of the flavin chromophore and might give rise to a great variety of reversible chemical reactions, depending on the structure of the environment and/or the pathway of potential e - as well as H -conductivity. It must be emphasized, that the oxidative action of the flavin triplet Tj is by no means confined to 1 e -uptake from suitable aromatic... 

DeBruyn, W. J., Shorter, J. A., Davidovits, P, Worsnop, D. R., Zahniser, M. S., and Kolb, C. E. Uptake of Gas-Phase Sulfur Species Methanesulfonic-Acid, Dimethylsulfoxide, and Dimethyl Sulfone by Aqueous Surfaces, J. Geophys. Res.-A., 99, 16927-16932, 1994. 

E. Uptake of cholesterol-derived bile salts in the intestine... 

Nitrogen is the most commonly limiting nutrient in North American forest ecosystems (20, 21). The form of N used by terrestrial ecosystems strongly affects the acidifying potential of N deposition (Figure 1). Ammonium uptake is an acidifying process (i.e., uptake of NH4+ releases 1 mole of H per mole of N assimilated). 

The hepatic transport of bilirubin from plasma to bile involves three independent, but related mechanisms, i.e., uptake, conjugation, and... 

It has become increasingly clear that there is a non-mitochondrial, intracellular calcium pool which plays an important role in cell activation in a large number of nonmuscle cells as well as in smooth and skeletal muscle. This pool is relatively enormous in skeletal muscle, provides the bulk of the Ca2+ needed to regulate skeletal muscle contraction, and is located in a distinct organelle, the sarcoplasmic reticulum. The pool is smaller in non-muscle and in smooth muscle cells, and its location less obvious [10,11]. To fill the pool requires ATP, i.e., uptake of Ca2+ into the pool is driven by a distinct Ca2+-ATPase, an enzyme which purifies with the mi-... 

In rodents, the extent of uptake increased linearly with concentration for exposures up to 200 ppm. At concentrations of >200 ppm, zero-order kinetics were observed (i.e., uptake became nonlinear, indicating... 

Figure 37.3 Uptake versus irradiance plots for two stations from Monterey Bay, California showing carbon (A, D) nitrate (B, E) and silicate (C, E) uptake estimated using stable ( N) and radiotracers Si).The first station (A-C) was collected from freshly upwelled surface waters ...

Measurement of active surface area (zero-valent iron) by hydrogen chemisorption after synthesis indicates that deactivation of K-promoted iron occurs readily at mild reaction conditions. For example, after a series of reaction experiments, the uptake of Fe/K-A-402 decreases from 19.3 to 8.75 pmoles/g. Upon regenerating the catalyst in hydrogen at 400 C for 24 hours, some of the active surface area is regained, but significant permanent deactivation occurred as indicated by a final uptake of 12.6 pmoles/g. On the other hand, the active surface area of the unpromoted catalyst is the same within experimental error before and after reaction, i.e. uptakes of two different unpromoted samples, one fresh and the other spent, were nearly identical. 

For aquatic life living in a large lake, we can assume that c (aq) is constant, i.e., uptake of the pollutant by aquatic life does not appreciably change the concentration in the water. This will be true for the fish in a large lake, but might not be true for a fish in an experimental aquarium. 

COMT) are widely distributed enxymes that caiabolize catecholamines. Inhibition of MAO and COMT ha.s little potentiating effect on responses to sympathetic nerve stimulation or injected catecholamines (norepinephrine, epinephrine) because they are largely maciivaicd by I e uptake. 

Figure 12.3 Tooopherols distribution In commonly used dietary oils. More than 50% of total vitamin E uptake Is derived from dietary oils. Olive and sunflower oils (common to European diet) contain mainly a-tocopherol, corn oils (common to U.S. diet) contain mainly ytocopherol, and soy oils (common to Asian diet) contain mainly Y- and 5-tooopherol. With the exception of palm oil, which has high levels of toootrienols (13% a-tooopherol, 75% tocotrienols), most oils contain only low amounts of toootrienols (not shown). However, the uptake and retention of tocotrienols from the human diet are generally low.

VITAMIN E UPTAKE AND DISTRIBUTION Vitamin E Transport from the Intestine... 

Cole, L. Hyde, G. J. Ashford, A. E. Uptake and compartmentalization of fluorescent probes by Pisolithus tinctorius hyphae evidence for an anion transport mechanism at the tonoplast but not for fluid-phase endocytosis. Protoplasma 1997,199, 18-29. 

The measurement of the uptake kinetics indicated that high-density lipoprotein might be the primary source of the vitamin E uptake by type II pneumocytes (Kolleck et al. 1999). Vitamin E depletion of rats caused an increase of vitamin E uptake by isolated type II pneumocytes from high-density hpoprotein but not from low-density lipoprotein or very low-density lipoprotein. Type II pneumocytes express the scavenger receptor class B type 1 (SR-Bl), a high-density lipoprotein-specific receptor. Vitamin E depletion caused an increased expression of SR-Bl by a post-transcriptional mechanism. The increased vitamin E uptake from high-density lipoprotein and the increased expression of the SR-Bl were reversed by refeeding the vitamin. 

Though widely studied, piezoelectric polyamides have not been widely used in applications partly because of their low room temperature piezoelectric response and the problem of moistin-e uptake. 

Polymer Blends. Commercial blends of nylon with other polsrmers have also been produced in order to obtain a balance of the properties of the two materials or to reduce moistin-e uptake. Blends of nylon-6,6 with poly(phenylene oxide) have been most successful, but blends of nylon-6,6 and nylon-6 with polyethylene or polypropylene have also heen introduced (24). 

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