Principal physiological mechanisms

Four principal mechanisms have been cited to explain the diverse physiological mechanisms of ginger. Broadly, these are (1) eicosanoid inhibition, (2) serotonin antagonism, (3) substance P release, and (4) Ca2-i-/ATPase activity. 

From this point of view, the obvious issues that need addressing are those of the achievement of the equilibrium or pseudoequilibrium condition (i.e. the critical chemical kinetics in the medium), of the nature and rate of the slow step in the chain of processes that link the principal metal species to the physiological response (i.e. the actual physiological mechanism of metal action) and, of course, the environmental meaning of it all. 

There are currently five reported routes for the metabolism of anandamide, and these are outlined in Figure 8.9 (Di Marzo, De Petrocellis, et al., 1999). The principal route for the metabolism of anandamide is mediated by an amidase called FAAH that releases free arachidonic acid and ethanolamine (Ueda et al., 1997 Ueda, Katayama, et al., 1999 Ueda, Yamanaka, et al., 1999 Ueda et al., 2000 Ueda and Yamamoto, 2000 Ueda, 2002). The free acid could either be re-incorporated into phospholipids or transformed into eicosanoids with potent biological actions of their own. At this time there is little evidence to support the latter suggestion however, should this turn out to be true, it would have interesting implications for the mechanism of anandamide action. This hydrolytic transformation of anandamide is considered to be an important physiological mechanism for regulating in vivo levels of anandamide, and FAAH has become a popular target for therapeutic intervention where it is desired to maintain or elevate anandamide tissue concentrations. 

In conclusion, it should be stressed that the competition between pro- and antiapoptotic effects of nitric oxide must probably depends on its relevant levels [137] the low physiological levels of NO principally suppress the apoptotic pathway by several mechanisms, whereas the higher rates of NO production may overcome cellar protective mechanisms and stimulate apoptosis. Furthermore, the simultaneous formation of nitric oxide and superoxide increases the possibility of apoptosis activation due to the formation of peroxynitrite. 

In summary, the physiological control of silk protein conversion shows an ingenious balance of activating and inhibiting mechanisms that are dependent on composition and sequence arrangement (Krejchi et al., 1994). Denaturing effects observed in silks appear to be identical to those found in amyloid-forming proteins, and they principally alter the competitive outcome of the hydration of nonpolar and polar residues (Anfinsen, 1973 Dill, 1990 Dobson and Karplus, 1999 Kauzmann, 1959). The key differences to amyloids may lie in the hierarchical level of the structures (Muthukumar et al., 1997) involved in the assembly of silks compared to amyloids. 

Hecker, M., Mtilsch, A., Bassenge, E., and Busse, R. (1993) Vasoconstriction and increased flow two principal mechanisms of shear stress-dependent endothelial autocoid release. American Journal of Physiology 265 (Heart Cir. Physiol. 34) H828-H833... 

Heavy metal tolerance remains one of the clearest examples of microevolution, and one of the best systems to study the relationship between adaptation and ecology. It provides a model for the evolution of ecotypes and edaphic endemics. At the physiological and biochemical level, it is a model system for the study of the mechanisms of resistance to stress and pollution. Many questions remain unanswered, however, among the principal ones of which are ... 

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