title: Circadian variation of urinary type I collagen crosslinked C-telopeptide and free and peptide-bound forms of pyridinium crosslinks.
abstract: This study was performed to investigate the circadian variation of urinary CrossLaps (CTx), which was the type I collagen peptide released during bone matrix degradation, and peptide-bound and free forms of urinary pyridinium crosslinks. Urine was obtained during the 24 h of the study in seven separate collections as follows: from 23:00 h to the first void (FV) followed by FV at 11:00, 11:00-14:00, 14:00-17:00, 17:00-20:00, 20:00-23:00, and 23:00 h to FV the next morning. Total, free, and peptide-bound pyridinoline (Pyr) and deoxypyridinoline (Dpyr) excretion measured by high-performance liquid chromatography (HPLC) and CTx measured by enzyme-linked immunosorbent assay in nine premenopausal women aged 22-40 years and nine osteoporotic women aged 65-83 years was analyzed. Among three parameters of Pyr measured by HPLC, a significant day and night difference was found only in total Pyr (21.9% higher at night than during the day in premenopausal women and 24.0% in osteoporotic women, whereas no significant day and night variation was found in free and peptide-bound Pyr in either group. In contrast, total and peptide-bound Dpyr were significantly (37.9% and 66.9%) higher at night than those during the day in premenopausal women (38.0%) and osteoporotic women (48.8%). For free Dpyr, there were no day and night differences in the two groups. The day and night variances were significantly greater in peptide-bound Dpyr than with total Dpyr in both groups. In urinary CTx, a significant circadian variation with a peak at night and a nadir at 17:00 h was found (p < 0.0001) (premenopausal was 54.0% higher at night than during the day; osteoporotic was 38.4%. In conclusion, urinary CTx represented remarkable circadian variation compared with urinary pyridinium crosslinks measured by HPLC. Furthermore, free pyridinium crosslinks did not undergo a circadian variation. Peptide-bound crosslinks might contribute mostly to the circadian variation of total excretion of pyridinium crosslinks.
authors.affiliation: Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Shizuoka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Aoshima
authors.forename: K
authors.initials: K
authors.lastname: Kushida
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Ohishi
authors.forename: H
authors.initials: H
authors.lastname: Hoshino
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Inoue
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000276:immunology / Q000652:urine*; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm / Q000502:physiology*; D003094:Collagen / Q000652:urine*; D024042:Collagen Type I; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D010024:Osteoporosis / Q000652:urine*; D010455:Peptides / Q000652:urine*; D017697:Premenopause / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; C015484:pyridinoline; C036020:deoxypyridinoline; D003094:Collagen