Enzyme activity physiological patterns affecting

Irwin and Hein (13) reported a family in which DN and FN values indicated that the father was of the usual phenotype, the mother the atypical phenotype, and the two sons the intermediate phenotype. However, one of the sons had about 25% more cholinesterase activity with benzoylcholine as substrate than did his father. Furthermore, the son s cholinesterase activity was greater than that of his father when tested with several other substrates. The pattern of values for this son indicated that his cholinesterase was qualitatively different from that of anyone else in his family. An unidentified gene that affects the amount of enzyme activity, as well as the qualitative properties of cholinesterase, might exist in this family. However, the findings may have been complicated by a physiologically high level of cholinesterase activity which is found in some children, and which decreases to normal adult values at puberty. 

In humans, circadian rhythms governed by the SCN affect a large number of physiological functions, including the sleep-wake cycle and nutrition (Moore-Ede et al, 1982 Touitou Haus, 1992). Moreover, a variety of hormone levels (Van Cauter Aschoff, 1989) or enzyme activities display circadian patterns. Circadian rhythms, accordingly, play important roles in both health and disease (Moore-Ede, Czeisler Richardson, 1983). Clinical applications of circadian rhythm research include the use of light to treat maladaptation to night work (Czeisler et al, 1990), jet lag, or seasonal affective disorder (Lewy et al, 1987). 

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