Inhibition function

The classification of these dmgs as antimetaboHtes stems from the mode of action as antagonists to the natural metaboHc processes leading to either DNA, RNA, or proteiu synthesis (13) (see Nucleic acids Proteins). They either inhibit function of a key en2yme involved in protein synthesis or are recmited into the cell division process as DNA synthesis terrninators. For example, methotrexate (8) is a foHc acid [59-30-3], antagonist and... 

Inhibitory substrates at high concentrations reduce the specific growth rate below that predicted by the simple Monod equation. The inhibition function may... 

Transport of NO3 formed from NH4+ towards the root and its consumption in denitrification and uptake by the root. Denitrification is described with Michaelis-Menten kinetics with an inhibition function related to [O2]. 

Other stimulation or inhibition functions may be appropriate as well. 

Mechanism of Action A 5-aminosalicylic acid derivative that changes intestinal microflora, altering prostaglandin production and inhibiting function of natural killer cells, mast cells, neutrophils, and macrophages. Therapeutic Effect Diminishes inflammatory effect in colon. 

Mecfianism of Action A monoclonal antibody that binds to tumor necrosis factor (TNF), inhibiting functional activity of TNF. Reduces infiltration of inflammatory cells. Therapeutic Effect Decreases inflamed areas of the intestine. 

Mechanism of Action A calcium regulator that inhibits functioning osteoclasts through disruption of cytoskeletal ring structure and inhibition of osteoclasticproton pump. Therapeutic Effect Inhibits bone resorption. 

At the end of mitosis imtil the restriction point R, pRb exists in an underphosphory-lated form. In the underphosphorylated form, pRb has a growth-inhibiting function in that it blocks the activity of activity of transcription factors that control expression of S phase genes. 

This discussion clearly demonstrates that drugs do not create functions, but merely stimulate or inhibit functions already inherent in cells. These pharmacodynamic-related interactions occur at various levels of cellular activity, including ion transport, enzymes, coenzymes, nucleic acids, and numerous other biochemical events yet to be delineated. 

Recently, the mechanism of corrosion protection by soluble chromate inhibitors has been the subject of active research, which has attempted to understand and replicate its inhibiting functions with less toxic chemical substances. In this section, some recent findings on chromate corrosion inhibition are reviewed, particularly as they pertain to corrosion of light metals, with a focus on the use of techniques that are useful for studying mechanisms of inhibition. 

It is also necessary to bear in mind that the proper application technique is used and also the dependence of the effectiveness of the inhibition on temperature, the secondary inhibitive function, poisoning nature, synergistic and antagonistic effects of mixtures of inhibitors before the actual application of an inhibitor for a specific purpose. 

Since lanthanides usually block cellular uptake of Ca2+, they also naturally inhibit physiological processes that depend on Ca2+ influx. Some of the inhibited functions are nerve impulses, contraction of muscles, and hormonal responses. 

A terbium complex (Figure 5.13) is a molecular logic gate corresponding to a two-input INHIBIT function the output (a terbium emission line) is observed only when the inputs , the presence of proteins and the absence of oxygen, are both satisfied. 

The dynamic model presented herein builds on that reported previously (I) by incorporating the interactions between volatile acids, pH, alkalinity, gas production rate, and gas composition. The model is developed from material balances on the biological, liquid, and gas phases of a continuous-flow, complete mixing reactor. Appropriate relationships such as yield constants, an inhibition function, Henry s law, charge balances, and ionization equilibria are used to express the interactions between variables. The inputs and outputs for the reactor and the reactions considered are illustrated in Figure 2. 

Inhibition Function. Incorporation of an inhibition function into the model in lieu of the Monod function is essential for process failure to be caused by high concentrations of volatile acids at residence times exceeding the wash-out residence time as is observed in the field. Koga and Humphry (IJ) have shown that continuous cultures obeying the Monod function are stable except at the wash-out residence time. The function proposed by Haldane (12) for the inhibition of enzymes by high substrate concentration will be used as an inhibition function and may be expressed as ... 

Andrews (13) has discussed the basis for the use of this function, and a more detailed treatment of its properties is given by Dixon and Webb (14). Yano and Koga (15) and Edwards (16) have discussed the properties of other functions which may be used to reflect inhibition by substrate. Figure 3 illustrates the properties of the inhibition function with the Monod function shown for comparison. For low values of substrate concentration or high values of Ki (less inhibitory substrates) the inhibition function reduces to the Monod function. There is a considerable reduction in the maximum growth rate attainable as compared with the case without inhibition. The maximum rate attainable may be obtained by setting the first derivative of Equation 9 equal to zero and can be expressed as ... 

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