title: Within-Day Baseline Variation in Salivary Biomarkers in Healthy Men.
abstract: Saliva is an easily accessible sample and offers practical and noninvasive biomarker solutions as an alternative to blood and urine-based diagnostics. Saliva contains a plethora of biomolecules such as nucleic acids, hormones, proteins, and electrolytes. On the other hand, little is known on the extent to which the biomolecules in saliva vary over time within a given person. This baseline information is crucial for future development of robust saliva-based diagnostics. We have collected unstimulated whole mouth saliva from 20 healthy young men at four times during the day, including before and after a meal. We measured the salivary cortisol, testosterone, C-reactive protein (CRP), stability of genomic DNA (gDNA) and DNA methylation levels of APC, P16INK4a, and PCQAP in these samples. We found that the salivary CRP, DNA methylation, and CD44 gDNA levels did not vary significantly across four time points (p > 0.05) while the salivary cortisol and testosterone levels significantly varied from the morning collection to the afternoon collection (p < 0.05). Furthermore, salivary cortisol levels were significantly affected by eating (p < 0.05). Our study offers a within-person baseline temporal assessment of several clinically relevant biomolecules and diagnostics, and suggests that salivary cortisol and testosterone levels vary over time in a given day whereas CRP and DNA methylation of tumor suppressor genes and CD44 amplification are stable throughout the day. Future research and clinical applications of salivary biomarkers and diagnostics should take into consideration their temporal variations.
authors.affiliation: 1 School of Biomedical Science, Institute of Health and Biomedical Innovation, Queensland University of Technology , Kelvin Grove, Australia .|2 School of Chemistry and Molecular Biosciences, University of Queensland , Brisbane, Australia .
authors.forename: Firman Prathama
authors.initials: FP
authors.lastname: Idris
authors.affiliation: 1 School of Biomedical Science, Institute of Health and Biomedical Innovation, Queensland University of Technology , Kelvin Grove, Australia .
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Wan
authors.affiliation: 1 School of Biomedical Science, Institute of Health and Biomedical Innovation, Queensland University of Technology , Kelvin Grove, Australia .
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.affiliation: 1 School of Biomedical Science, Institute of Health and Biomedical Innovation, Queensland University of Technology , Kelvin Grove, Australia .
authors.forename: Chamindie
authors.initials: C
authors.lastname: Punyadeera
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis* / Q000737:chemistry*; D002097:C-Reactive Protein / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics; D064368:Healthy Volunteers; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D057285:Precision Medicine; D012463:Saliva / Q000737:chemistry*; D013739:Testosterone / Q000032:analysis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018960:Hyaluronan Receptors; D013739:Testosterone; D002097:C-Reactive Protein; D006854:Hydrocortisone
keywords: biomarkers; diagnostic medicine; personalized medicine