Nutrients transport

Potassium is required for enzyme activity in a few special cases, the most widely studied example of which is the enzyme pymvate kinase. In plants it is required for protein and starch synthesis. Potassium is also involved in water and nutrient transport within and into the plant, and has a role in photosynthesis. Although sodium and potassium are similar in their inorganic chemical behavior, these ions are different in their physiological activities. In fact, their functions are often mutually antagonistic. For example, increases both the respiration rate in muscle tissue and the rate of protein synthesis, whereas inhibits both processes (42). 

True zwitterionic compounds are rare among drugs. The oral absorption of truly zwitterionic compounds is poor unless the compound is a substrate for an absorptive biological transporter as in an a-amino acid which is a substrate for the PepTl nutrient transporter. The aqueous solubility of a true zwitterionic compound will be at a minimum at the isoelectric point which unfortunately for many compounds happens close to the neutral pH at which oral absorphon occurs. Species extrapolation predicting oral absorphon and pk/pD from preclinical animal tests to man are difficult for zwitterions. 

D. T. Clarkson and U. Liittge, Mineral nutrition Inducible and repressible nutrient transport systems. Progress in Botany Vol. 52 (H.-D. Behnke et al., eds.), Springer-Verlag, Berlin, 1991, p. 61. 

S. E. Smith and F. A. Smith, Structure and function of the interfaces in biotrophic symbiosis as they relate to nutrient transport. New Phytol. 114 (1990). 

Control of nutrient transport dictates significant coupling between transported components in G1 epithelia. This complicates solute transport analysis by requiring a multicomponent description. Flux equations written for each component constitute a nonlinear system in which the coupling nonlinearities are embodied in the coefficients modifying individual transport contributions to flux. 

U Kompella, KJ Kim, VHL Lee. (1992). Active ion and nutrient transport mechanisms of the pigmented rabbit conjunctiva. Pharm Res 9(Suppl) 3. 

Targeting poorly absorbed drugs to nutrient transport system is a successful approach to increasing oral bioavailability [7]. The two most important nutrient... 

Daniel, H., Nutrient transporter function studied in heterologous expression systems, Ann. N. Y. Acad. Sci. 2000, 915, 184-192. 

Pseudomonas aeruginosa One of the largest pathogenic bacterial genomes, with an expansion of nutrient transport proteins( 200) and two-component regulatory system proteins( 160) features that likely reflect adaptation to thrive in diverse environments and resist antibiotics... 

Primarily to elucidate transporter localization and function, vesicles enriched in trophoblast apical or basolateral membranes have frequently been utilized. To give a few instances, they have been used to investigate P-gp-mediated transport, mechanisms of transport of cationic compounds, drug interactions with nutrient transport, and differences in amino acid transport in pathological conditions of the placenta [36, 40-42], Briefly, for preparation of microvillus membrane vesicles the cord, amniochorion and decidua are removed from placenta, and the tissue cut on the maternal side. The mince is stirred to loosen... 

Other gases with significant anthropogenic sources contribute to acid rain (NO and SO ), the reduction of the ozone layer (chlorofluorocarbons), nutrient transport (NHj... 

An alternative delivery strategy for small molecules is based on the presence of the nutrient transporters. Drugs that are structurally similar to substrates of a carrier system can undergo facilitated brain uptake as pseudoneutrients. The best example of this is the therapeutic use of L-DOPA in Parkinson s disease. Unlike the neurotransmitter dopamine itself, which cannot cross the BBB in significant amounts, its precursor L-DOPA is a substrate for LAT, the transporter of large neutral amino acids [56]. Its uptake by the brain is saturable, and subject to competition by the other substrates of the carrier present in plasma. 

Promotes red blood cell count for improved oxygen/nutrient transport and vascularity. 

The body has 3 periods when creatine uptake is highest After a nights sleep, the body is in a fasted stated due to a period of natural GH pulses (about half of your daily total GH production is released during the first 4 hours of sleep) and a prolonged period without nutrients. This results in an up-regulation of nutrient transporters and enzymes which favor intramuscular uptake of nutrients, including Creatine. 

Owing to their particular chemical structure, amide prodrugs can be designed for targeting peptide and nutrient transporters to enhance permeability. In this application, amide prodrugs are also shown to generally... 

Even if membranous vesicles were commonplace on the early Earth and had sufficient permeability to permit nutrient transport to occur, these structures would be virtually impermeable to larger polymeric molecules that were necessarily incorporated into molecular systems on the pathway to cellular life. The encapsulation of macromolecules in lipid vesicles has been demonstrated by hydration-dehydration cycles that simulate an evaporating lagoon [53] or by freeze-thaw cycles [54]. Molecules as large as DNA can be captured by such processes. For instance, when a dispersion of DNA and fatty acid vesicles is dried, the vesicles fuse to form a multilamellar sandwich structure with... 

Correll, D.L., Jordan, T.E., and Weller, D.E. (1992) Nutrient flux in a landscape effects of coastal land use and terrestrial community mosaic on nutrient transport to coastal waters. Estuaries 15, 431 142. 

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