Transporter involving

Pipeline transport involves the appHcation of force to the material being moved, either through the use of pumps to transport Hquids, compressors to move gases, or flowing water to move soHds. In some appHcations, vacuum may create the pressure differential. 

Transfer and Transport The func tional element of transfer and transport involves two steps (1) the transfer of wastes from the smaller collection vehicle to the larger transport equipment and (2) the subsequent transport of the wastes, usually over long distances, to the disposal site. 

ABC Transporters. Table 1 Substrates of ABC-transporters involved in multidrug resistance (MDR)... 

The tissue distribution of substrates of transporters involved in the active transport into or out of tissues... 

The co-administration of drugs which inhibit the transporters involved in renal tubular secretion can reduce the urinaty excretion of drugs which are substrates of the transporter, leading to elevated plasma concentrations of the drugs. For example, probenecid increases the plasma concentration and the duration of effect of penicillin by inhibiting its renal tubular secretion. It also elevates the plasma concentration of methotrexate by the same mechanism, provoking its toxic effects. 

Note These are examples of important transporters involved in substrate and ADP uptake into the matrix compartment as indicated, and most are reversible. These transporters are proteins and several have been isolated and sequenced. Other specific carriers occur in mitochondria from other tissues. The inner membrane does not allow rapid exchange of NAD or CoA but there are mechanisms for the slow uniport of cofactors synthesized extramitochondrially. 

Nickel is required by plants when urea is the source of nitrogen (Price and Morel, 1991). Bicarbonate uptake by cells may be limited by Zn as HCOT transport involves the zinc metal-loenzyme carbonic anhydrase (Morel et al., 1994). Cadmium is not known to be required by organisms but because it can substitute for Zn in some metalloenzymes it can promote the growth of Zn-limited phytoplankton (Price and Morel, 1990). Cobalt can also substitute for Zn but less efficiently than Cd. 

We now describe a relatively simple MD model of a low-index crystal surface, which was conceived for the purpose of studying the rate of mass transport (8). The effect of temperature on surface transport involves several competing processes. A rough surface structure complicates the trajectories somewhat, and the diffusion of clusters of atoms must be considered. In order to simplify the model as much as possible, but retain the essential dynamics of the mobile atoms, we will consider a model in which the atoms move on a "substrate" represented by an analytic potential energy function that is adjusted to match that of a surface of a (100) face-centered cubic crystal composed of atoms interacting with a Lennard-Jones... 

Importantly, the currently available transporter models only cover a small fraction of all transporters involved in drug disposition. Other than incorporating current stand-alone transporter models into systemic models to directly predict drug pharmacokinetic properties, continued efforts are still needed to investigate other transporters such as MRP, BCRP, NTCP, and OAT, to get a more complete understanding of the drug pharmacokinetic profile. 

The mechanism of the coupling between ATP hydrolysis and Ca transport is determined by the spatial relationship of the phosphorylation and ATP binding domains of the Ca -ATPase to the Ca channel involved in the translocation of calcium. Two alternative coupling mechanisms have been proposed, based on two rather different hypothetical models of the structure of the Ca -ATPase. In the conformational coupling mechanism the energy transfer between ATP hydrolysis and transport involves a mechanical coupling over long distances between... 

The mechanism of facilitated transport involves using the metal ion only in its reduced state in the oxidized state the oxygen-carrying capacity is virtually nil. It is thus natural that electrochemical processes should be attempted to improve both the flux and selectivity obtained with the membranes described above by exploiting this 02 capacity difference. For example, the best of the ultra-thin membranes developed by Johnson et al. [24] delivered oxygen at a rate equivalent to a current density of only 3 mA/cm2, at least an order lower than that achievable electrochemically. Further, the purity was but 85% and the lifetime of the carrier less than a year. 

Cytostatic drugs for which inhibitors are primarily needed are often not only substrates of P-gp but also inducers of P-gp overexpression with one or even several type II units. An important point to clarify would be whether or not type II units are required to achieve a cytostatic effect. If they were not required, it might be possible to eliminate the P-gp-inducing effect that causes multidrug resistance by eliminating type II units. So far, the only other possibility of overcoming multidrug resistance is to inhibit the transporters involved. Inhibition can be achieved essentially by two different concepts ... 

Dresser MJ, Leabman MK, Giacomini KM. Transporters involved in the elimination of drugs in the kidney organic anion transporters and organic cation transporters. J Pharm Sci 2001 90(4) 397-421. 

Apart from the reactions described above for the formation of thin films of metals and compounds by the use of a solid source of the material, a very important industrial application of vapour phase transport involves the preparation of gas mixtures at room temperature which are then submitted to thermal decomposition in a high temperature furnace to produce a thin film at this temperature. Many of the molecular species and reactions which were considered earlier are used in this procedure, and so the conclusions which were drawn regarding choice and optimal performance apply again. For example, instead of using a solid source to prepare refractory compounds, as in the case of silicon carbide discussed above, a similar reaction has been used to prepare titanium boride coatings on silicon carbide and hafnium diboride coatings on carbon by means of a gaseous input to the deposition furnace (Choy and Derby, 1993) (Shinavski and Diefendorf, 1993). 

A more detailed view also highlighting the special features of ABC transporters involved in iron uptake is provided in Sections 7.3.3. to 7.3.5. 

ABC transporters involved in the uptake of siderophores, haem, and vitamin B]2 are widely conserved in bacteria and Archaea (see Figure 10). Very few species lack representatives of the siderophore family transporters. These species are mainly intracellular parasites whose metabolism is closely coupled to the metabolism of their hosts (e.g. mycoplasma), or bacteria with no need for iron (e.g. lactobacilli). In many cases, several systems of this transporter family can be detected in a single species, thus allowing the use of structurally different chelators. Most systems were exclusively identified by sequence data analysis, some were biochemically characterised, and their substrate specificity was determined. However, only very few systems have been studied in detail. At present, the best-characterised ABC transporters of this type are the fhuBCD and the btuCDF systems of E. coli, which might serve as model systems of the siderophore family. Therefore, in the following sections, this report will mainly focus on the components that mediate ferric hydroxamate uptake (fhu) and vitamin B12 uptake (htu). 

Kehres, D. G., Zaharik, M. L., Finlay, B. B. and Maguire, M. E. (2000). The NRAMP proteins of Salmonella typhimurium and Escherichia coli are selective manganese transporters involved in the response to reactive oxygen, Mol. Microbiol., 36, 1085-1100. 

Groeger, W. and Koster W. (1998). Transmembrane topology of the two FhuB domains representing the hydrophobic components of bacterial ABC transporters involved in the uptake of siderophores, haem and vitamin B12, Microbiology, 144, 2759-2769. 

Wadleigh RW, Yu SJ (1988) Detoxification of iso thiocyanate allelochemicals by glutathione transferase in three lepidopterous species. J Chem Ecol 14 1279-1288 Werck-Reichhart D, Feyereisen R (2000) Cytochromes P450 a success story. Genome Biol 1 1-9 Williams AB, Jacobs RS (1993) A marine natural product, patellamide D, reverses multidrug resistance in a human leukemic cell line. Cancer Lett 71 97-102 Yazaki K (2006) ABC transporters involved in the transport of plant secondary metabolites. FEBS Lett 580 1183-1191... 

In Sections 4.1 and 4.2, the electron transfer and the mass transport involved in a simple electrode reaction [simple = not complicated by preceding or following reactions, by absorption, or by formation of phases (see Section 2.2)] have been treated separately. However, it is to be expected that in reality both phenomena act in a concerted manner during a faradaic process. Thus, as seen previously, even the simple electrode process ... 

R. Agu, H. V. Dang, M. Jorissen, T. Willems, S. Vandoninck, J. Van Lint, J. V. Vandenheede, R. Kinqet, and N. Verbeke. In vitro polarized transport of L-phenylalanine in human nasal epithelium and partial characterization of the amino acid transporters involved. Pharm Res 20 1125-1132 (2003). 

To describe and quantify these complex dynamics, models are used. Modeling of contaminant transport involves formulation of a conceptual framework and corresponding quantitative relationships that lead to determination of contaminant distributions over space and time. Models also can be used to investigate the relative influence of different physical and (geo)chemical mechanisms on contaminant transport and to assist in designing management and remediation strategies. 

Figure 2.1 Schematic diagram of a DMFC, its electrode reactions and material transport involved, where (b) is the anode backing, (f) the cathode backing, (c) the Pt-Ru anode catalyst layer, (d) the Nafion 117 membrane and (e) the Pt cathode catalyst layer.

Yazaki, K. 2006. ABC transporters involved in the transport of plant secondary metabolities. FEBS Letters, 580(4) 1183-1191. 

One of the main in vitro permeability assays used in the pharmaceutical industry has been for many years the Caco-2 monolayer. Therefore, most of the in silica models developed to predict permeability were based on Caco-2 data. Hou and Johnson produced a couple of reviews that comprehensibly summarizes the recent efforts using Caco-2 permeability data [92, 94]. All those models are designed to predict the influx or apparent permeability of drugs in the same direction as intestinal absorption occurs, that is, from the apical to the basal side of the cell line, regardless of the extent of active transport involved in the permeation process. 

F. Transporters involved in facilitated diHiision are a diverse group, but they share the properties of substrate specificity and saturability. 

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