Biological significance

A major goal of continuing research is to demonstrate that these acrolein, croton-aldehyde, and HNE-derived interstrand cross-links are present in vivo, utilizing MS-based analysis [10, 47—49]. Since the cross-links equilibrate with non-cross-linked species and require the presence of the 5 -CpG-3 sequence, they may be present at very low levels in tissue samples. Nevertheless, it has been reported that acrolein preferentially binds at 5 -CpG-3 sites-a consequence of cytosine methyla-hon at these sequences [15]. 

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Sulfolane causes minimal and transient eye and skin irritation (19,20). Inhalation of sulfolane vapors in a saturated atmosphere is not considered biologically significant. However, when aerosol dispersions have been used to elevate atmospheric concentration, blood changes and convulsions have been observed in laboratory animals (22,31). Convulsions caused by sulfolane injected intraperitoneaHy have also been studied (32). 

A synthesis of possible biological significance was effected by Spath and Berger, who ozonised eugenol methyl ether to 3 4-dimethoxyphenyl-acetaldehyde (Villa), which was then condensed with 3 4-dimethoxy-phenylethylamine (Vlllb), and the resulting Schiff s base (IX) treated wit hot 19 per cent, hydrochloric acid, whereby it was transformed into... 

This technique has been applied to the synthesis of fluormated dopamine and other compounds of biological significance Fluoroheterocycles such as fluoro-imidazoles [JJ, 36] and fluoropyrazoles [37] can also be prepared by the photo Balz-Schiemann technique (equation 9) Photochemically induced in situ fluoro dediazoniation can also be applied to arenediazonium fluorides in hydrogen fluo nde-pyndine media Thus, o-fluoroanisole is obtained in 73% yield at 20 °C after I8h [dS]... 

Lowcst-Obsciwcd-Advcrsc-El fcct-Lcvel (LOAEL) In dose-response experiments, the lowest exposure level at which there are statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control group. 

That is, the H-bonded network provides a natural route for rapid transport. This phenomenon of proton jumping thus occurs with little actual movement of the water molecules themselves. Ice has an electrical conductivity close to that of water because such proton jumps also readily occur even when the water molecules are fixed in a crystal lattice. Such conduction of protons via H-bonded networks has been offered as an explanation for a number of rapid proton transfers of biological significance. 

Tliere are several reasons for this great interest in the tautomerism of porphyrins (which could justify its own review) (1) their biological significance, (2) their applications in material science ( hole burning is related to their tautomerism), (3) the simplicity of the system (annular tautomerism involving intramolecular proton transfer both in solution and in the solid state), and (4) the possibility of elucidating the kinetic processes in great detail. 

G. A. Codd, Cyanobacterial toxins occuixance, properties and biological significance . WaterSci. Technol. 32 149-156(1995). 

Dissolved oxygen is a very important factor in the corrosion of metals immersed in sea water. Because of its biological significance, a vast amount... 

W F Smyth, Polarography of Molecules of Biological Significance, Academic Press, New York, 1979... 

Aspects of organotransition metal photochemistry and their biological significance. E. A. Koerner von Gustorf. L. H. G. Leenders, I. Fischler and R. N. PerutZ, Adv. Inorg. Chem. Radiochem., 1976,19, 65-183 (632). 

On the discriminating behaviour of metal ions and ligands with regard to their biological significance. H. Sigel and D. B. McCormick, Acc. Chem. Res., 1970,3,201-208 (66). 

Distinctive coordination chemistry and biological significance of complexes with macrocyclic ligands. D. H. Busch, Acc. Chem. Res., 1978,11, 392-400 (61). 

The widespread occurrence and biological significance of polyoxygenated carbocycles provided the impetus to apply RCM to sugar-derived dienes. Carbohydrate carbocyclization based on a sequence of Vasella reductive opening of iodo-substituted methyl glycosides [25], and RCM of the dienes available from the resulting unsaturated aldehydes, were used to prepare a series of natural compounds (Schemes 5-7). 

Why Do We Need to Know This Material The dynamic equilibrium toward which every chemical reaction tends is such an important aspect of the study of chemistry that four chapters of this book deal with it. We need to know the composition of a reaction mixture at equilibrium because it tells us how much product we can expect. To control the yield of a reaction, we need to understand the thermodynamic basis of equilibrium and how the position of equilibrium is affected by conditions such as temperature and pressure. The response of equilibria to changes in conditions has considerable economic and biological significance the regulation of chemical equilibrium affects the yields of products in industrial processes, and living cells struggle to avoid sinking into equilibrium. 

The biological significance of chitosan biomaterials in the hiunan body depends largely on the actions that certain hydrolases exert on them. The resulting chitoohgomers stimulate various cells, while the released monomers are phosphorylated and incorporated into hyaluronan, keratan sulphate and chondroitin sulphate, components of the intracellular matrix and connective tissue [348]. 

The fact that the concentration of G-actin at steady-state in the presence of ATP varies with the number of filaments may have some biological significance indeed, in cells, large pools of G-ADP-actin may accumulate in regions where a large number of short filaments exist. This behavior is the direct consequence of two combined features of actin polymerization namely, the hydrolysis of ATP, and the relatively slow rate of ATP exchange for ADP on G-actin. 

Jameel, A., Skilton, R.A., Campbell, T.A., Chander, S.K., Coombes, R.C., Luzmani, Y.A. (1992). Clinical and biological significance of hsp89 alpha in human breast cancer. Inti. J. Cancer 50, 409-415. 

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