title: The genetic background of circadian and ultradian rhythm patterns of 17-hydroxycorticosteroids: a cross-twin study.
abstract: Circadian and ultradian rhythms in urinary excretion of 17-hydroxycorticosteroids were documented individually during an 8-day span in two pairs of young male twins. Studies were performed once at the age of 6 years for dizygotic twins and twice at the ages of 4.3 and 10.3 years for monozygotic twins. Four different methods were used for time-series analyses: chronograms (raw data), best-fitting curves resulting from cosinor analyses, power spectra and correlations of time-qualified data. Estimates of rhythm parameters (prominent periods, acrophases, etc.) as well as shapes of curves were closer in mono- than in dizygotic twins. Both similarities and small differences in rhythm characteristics of monozygotic twins were detected at both ages considered.
mesh_terms: D015065:17-Hydroxycorticosteroids / Q000235:genetics* / Q000652:urine; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D010507:Periodicity; D011247:Pregnancy; D013223:Statistics as Topic; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D014867:Water / Q000378:metabolism
chemical_list: D015065:17-Hydroxycorticosteroids; D014867:Water; D003404:Creatinine