title: Exploring the time dependence of serum clara cell protein as a biomarker of pulmonary injury in humans.
abstract: We have previously demonstrated Clara cell protein (CC16) [secretoglobin 1A1] in serum to be a highly sensitive biomarker of altered lung epithelial permeability after ozone challenge. As a previous experimental study has indicated a diurnal variation in serum CC16 in humans, the aims of the present investigation were to confirm this observation and to attempt to model the diurnal variation in CC16 concentrations. In 18 healthy nonsmoking subjects, peripheral blood samples were drawn at six sampling points over a 15-h period and repeated twice within 3 to 4 weeks. A clear within-day variation was revealed in serum CC16 concentrations, falling significantly from baseline levels between the 11:30 am and 10:00 pm time points (p = 0.000). Furthermore, it was shown that this within-day variation was reproducible regardless of subject or day, enabling the diurnal variation in serum CC16 to be modeled and fitted a second-degree polynomial for the observed time span. In conclusion, the present data demonstrate a pronounced time-dependent diurnal variation in serum levels of CC16, which can be mathematically compensated for, when addressing the issue of an air pollution-induced effect on CC16 in field studies.
authors.affiliation: Department of Respiratory Medicine and Allergy, Umea University, Umeå, Sweden.
authors.forename: Ragnberth
authors.initials: R
authors.lastname: Helleday
authors.forename: Bo
authors.initials: B
authors.lastname: Segerstedt
authors.forename: Bertil
authors.initials: B
authors.lastname: Forsberg
authors.forename: Ian
authors.initials: I
authors.lastname: Mudway
authors.forename: Gunnar
authors.initials: G
authors.lastname: Nordberg
authors.forename: Alfred
authors.initials: A
authors.lastname: Bernard
authors.forename: Anders
authors.initials: A
authors.lastname: Blomberg
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002940:Circadian Rhythm; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010126:Ozone / Q000009:adverse effects* / Q000494:pharmacology; D020545:Respiratory Mucosa / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D012137:Respiratory System / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology; D014598:Uteroglobin / Q000097:blood*
chemical_list: D015415:Biomarkers; C556389:SCGB1A1 protein, human; D010126:Ozone; D014598:Uteroglobin