Biochemical pathway affected

Other biochemical pathways affected by NOx include inhibition of lipid biosynthesis, oxidation of unsaturated fatty acids in vivo, and stimulation of peroxidase activity. 

H. G. Holzhtitter, G. Jacobasch, and A. Bisdorff, Mathematical modeling of metabolic pathways affected by an enzyme deficiency. A mathematical model of glycolysis in normal and pyruvate kinase deficient red blood cells. Eur. J. Biochem. 149(1), 101 111 (1985). 

The role of many hormones, and particularly those discussed in this chapter, is to change the flux through a biochemical pathway or process. In order to identify the mechanism by which the hormone affects the biochemistry in the cell, it is necessary to know or to predict which... 

Plant cell culture is useful in laboratory and in industry because it allows plant natural products to be produced in a relatively controlled manner, and provides a supply of plant material that is not affected by sourcing problems, such as environmental, seasonal, geographical, and political factors.Also, plant cell culture allows for the tweaking and rearrangement of secondary metabolite biochemical pathways in order to produce novel metabolites, and to increase target compound yields, as well as allowing derivatives to be formed by introduction of analogs of natural intermediates.Plant cell culture can be performed with callus and suspension cultures, as well as with shoot cultures and hairy root cultures. These latter two approaches are especially useful when a metabolite is found to be produced more readily in differentiated cells. 

Folacin deficiency produces a megaloblastic anaemia not unlike that produced by vitamin B12 deficiency (120,122,126-130). This is a result of the interdependence of folacin and vitamin B,2 in at least two biochemical pathways in vivo. Folacin deficiency also appears to affect neurological function. 

Of the various biochemical pathways identified as being affected by herbicides, the chloroplast-mediated reactions have received the greatest attention. Approximately 70 percent of the current commercial herbicides, while they may also affect other systems, interfere with chloroplast reactions. Hence, the objectives of this paper are to review some of the work conducted with isolated chloroplasts, evaluate the status of these studies, and relate the observed interferences to the expression of phytotoxicity. 

Almost every phase of biomedical engineering involves the measurement, replacement, or modification of tissues and organs. For this reason it is essential that workers in biology, medicine, and biomedical engineering understand the relationship among biochemical pathways, mechanical loading, tissue structure, and normal function. The purpose of this text is to integrate this material in order to provide a conceptual framework needed to understand how external forces affect tissue metabolism. 

The purpose of this chapter is to review the types of proteins that interact with or respond to cisplatin-damaged DNA, and to discuss how these proteins can modulate cellular sensitivity to the drug through their participation in various biochemical pathways (Fig. 2). Included are proteins dedicated to dealing with genotoxic stress, such as components of the DNA repair and p53-regulated pathways, but also proteins affected by the DNA structural distortions induced by cisplatin adduct formation, such as transcription factors and architectural proteins. The manner by which such proteins affect the processing of cisplatin-DNA adducts can determine wheth-... 

The individual reactions affected by iron stress can be considered as regulated biochemical pathways, although regulation by iron is not understood. The mechanism of iron absorption and transport involves the release of hydrogen ions by the root, which lowers the pH of the root zone. This favors Fe3+ solubility and reduction of Fe3 to Fe2+. Reductants are released by roots or accumulate in roots of plants that are under iron stress. These "reductants, along with Fe3+ reduction by the root, reduce Fe3+ to Fe2+, and Fe2+ can enter the root. Ferrous iron has been detected throughout the protoxylem of the young lateral roots. The Fe2+ is probably kept reduced by the reductant in the root, and it may or may not have entered the root by a carrier mechanism. The root-absorbed Fe2+ is believed to be oxidized to Fe3, chelated by citrate, and transported in the metaxylem to the tops of the plant for use. We assume Fe2+ is oxidized as it enters the metaxylem because there is no measureable Fe2+ there (13), and Fe3+ citrate is transported in the xylem exudate (30, 31,32). 

In many cases, multiple biochemical pathways are activated by the intake of therapeutical drugs. The activation of side mechanisms coincides with the consequent side effects. This concept has led to research areas like polypharmacology as well as re-purposing studies. In such cases, the possibility of activating of multiple biochemical pathways is employed to explore alternative therapeutic uses of the same compound. In addition to the ligand-receptor process, it is necessary to take into consideration the other mechanistic features that might also be involved and affect the analysis, such as the metabolism, transport based on carry proteins, co-factors, influence of metals, etc. 

Despite only a minor difference in the chemical structures of vinblastine and vincristine, the clinical effects differ considerably. Surprisingly there is no clinical evidence of cross resistance between them, or with radiation and other presently known oncolytic agents. The rise and fall of the blood activity level of vincristine is steeper than that of vinblastine.The dosage requirements of both alkaloids differ markedly the weekly intravenous dose of vinblastine for humans is 0.1—0.2 mg per kg, that of vincristine, however, is approximately one tenth of this. Concerning the side-effects, vincristine shows more neurotoxic effects and vinblastine is considered to have more potency in bone-marrow depression. This is not without consequences on human therapy therapy is limited by bone-marrow depression with vinblastine and neuromuscular effects, with vincristine. Early symptoms of side-effects are vomiting, fever, and exanthemes. Late symptoms are C.N.S. disturbances, alopecia, and leukopenia. C.N.S. disturbances are manifested by various symptoms such as paresthesias, neuritis, paresis, and muscular atrophy, accompanied by quenched reflexes. Even behaviour may be affected after a long period of treatment. But why do all these side-effects happen, when Vinca alkaloids are unable to pass the blood-brain barrier The only explanation we have at hand is that they are possibly caused by metabolites or breakdown products of the normal biochemical pathways, which are disturbed by the alkaloids. 

Most allosteric enzymes are multisubunit proteins. The binding of substrate to one protomer in an allosteric enzyme affects the binding properties of adjacent protomers. In addition, the activity of allosteric enzymes is affected by effector molecules that bind to additional sites called allosteric or regulatory sites. Allosteric enzymes generally catalyze key regulatory steps in biochemical pathways. (Regulation of allosteric enzymes is discussed on p. 190.)... 

As with other biochemical pathways, hormones affect gluconeogenesis by altering the concentrations of allosteric effectors and the rate key enzymes are synthesized. As mentioned previously, glucagon depresses the synthesis of fructose-2,6-bisphosphate, activating the phosphatase function of PFK-2. The lowered concentration of fructose-2,6-bisphosphate reduces activation of PFK-1 and releases the inhibition of fructose-1,6-bisphosphatase. 

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