Biological Contexts

Ionic Equilibria.. The ion product constant of D2O (see Table 3) is an order of magnitude less than the value for H2O (24,31,32). The relationship pD = pH + 0.41 (molar scale 0.45 molal scale) for pD ia the range 2—9 as measured by a glass electrode standardized ia H2O has been established (33). For many phenomena strongly dependent on hydrogen ion activity, as is the case ia many biological contexts, the difference between pH and pD may have a large effect on the iaterpretation of experiments. 

Strictly speaking, growth refers specifically to an increase in mass. In biological contexts, and increase in mass is often coupled to (and is indeed often a prerequisite for) proliferation (an increase in cell number). Importantly, growth and proliferation are distinct processes that can be both physiologically and experimentally uncoupled. 

Cheek AC, Vonier PM, Oberdorster E, et al. 1998. Enviromnental Signaling A biological context for endocrine disruption. Environ Health Perspect 106(Suppl. 1) 5-10. 

Testa, B. Drugs as chemical messages molecular structure, biological context, and structure-activity relationships. Med. Chem. Res. 1997, 7, 340-365. 

Binding activity does not amount to biological function or value importance of biological context multiple functions appear during evolution... 

It may seem curious to make specific mention of this matter, but in a biological context, it is crucial. The nuclei of porphyrins and related systems are hydrophobic it appears to be generally desirable that the photosensitizer has some degree of intermediate polarity (i.e., amphiphilic properties Section 9.22.3) and the incorporation of a metal, such as zinc(II), which can take on an axial ligand (e.g., H20 in aqueous media, or RNH2 in a biological fluid), or magnesium(II), which can take on two, is expected to enhance solubility in hydroxylic solvents, and shift the... 

Abstract This is a short review of how neuronal sensors fit in the broader biological context of animal survival. This may help those involved in the development of engineered sensors to put in perspective their task with what the evolutionary process has achieved. Most of the information reported here is available in the educational field of neuroscience, with mention of some recent relevant findings. I have attempted to place these findings in an evolutionary perspective as it clarifies better the intrinsic role of some of the extraordinary particularities of the biological solutions of neuronal sensors. 

An a priori classification of these various reactions as either toxification or detoxification is simply impossible, since each product from these various pathways may be toxic or not depending on its chemical properties and own products. Furthermore, the biological context plays a critical role [154], yet this role, best viewed as the influence of biological factors on the relative importance of competitive routes of metabolism, is often underplayed by those who venture to make predictions of metabolic outcome. Indeed, in the cascade of intertwined metabolic routes exemplified by haloalkenes, a small difference in pathway selectivity at an early metabolic crossroad may be amplified downstream, giving rise to major differences in relative levels of metabolites and overall toxicity. 

Such groups are relevant in our context since they occur in drugs, drug metabolites, prodrugs, and other xenobiotics. Their hydrolysis is essentially a nonenzymatic process, the rates depending not only on the biological context, but also on the structure and properties of the compounds. 

Basic electron transfer theory, summarized eompactly by Sutin [8, see also Bertrand, Chapter 1 in this volume], and reviewed in the biological context by Jortner [9], separates the reaction dynamics into nuclear and electronic dynamics. This basic separation is very central to the simplification of a complex dynamical phenomenon, and a few words about the nuclear factors are in order here, before we proceed to the electronic factors. 

These oxidation and acetylation reactions have not yet been examined in a biologic context. 

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