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  • Title: Assessment of the risk of mesor-hypertension.
    Author: Hermida-Dominguez RC, Halberg F.
    Journal: Chronobiologia; 1984; 11(3):249-62. PubMed ID: 6510120.
    Abstract:
    A small number of selected (rather than randomly picked) women of three age groups was extensively sampled in two geographic locations. Data on twelve of the plasma hormones in addition to those on some systemic variables, including blood pressure (BP), determined around the clock and along the calendar were here analyzed further. The risk of developing certain diseases was assessed by epidemiologically designed questionnaires. The risk of cerebro-, reno-, cardiovascular disease was here approached by focus upon the risk of developing a high rhythm-adjusted mean (mesor) of BP. The risk of mesor-hypertension (RMH) for a selected group of young adult women was inversely correlated with the circannual amplitude (a measure of the extent of predictable since rhythmic change along the scale of a year) and the circannual mesor of plasma aldosterone. These indices are costly in several ways since it takes at least a year and quite a few samples to estimate them reliably. In the attempt to reduce sampling requirements to one or at most two plasma samples, a chronobiologic pattern discrimination analysis was undertaken on the original data from the subgroup of young adult women. Data were normalized by the sample standard deviation of each variable and processed according to proximity (so-called nearest neighbor) rules, for dimension reduction and classification. For each variable, each subject's samples were classified by reference to those of all others. The results objectively identify certain variables for further testing on larger, properly stratified and randomized cohorts followed preferably for a life-time and also illustrate the computer method of pattern discrimination used. Pattern discrimination not only singles out plasma aldosterone as the primary classifier for RMH, but shows further the circannual- and circadian-stage dependence of the classification. The clock-hour for optimal classification of RMH by aldosterone and by hormonal co-classifiers changes with the season. Furthermore, the relation between the circadian mesor of aldosterone concentration and RMH is an inverse one in summer, fall and winter, but a direct one in spring. A validated inverse relation to RMH of the circannual amplitude and mesor as well as any added differences in acrophase or waveform of aldosterone as a function of circannual stage all contribute to the change in sign of the relationship between aldosterone and RMH observed in spring. The latter change renders mandatory the specification as to clock-hour and season of any spot-check for risk assessment, whether it is based upon single or multiple samples.(ABSTRACT TRUNCATED AT 400 WORDS)
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