To evaluate diurnal variation of plasma bone markers, blood samples were
collected from five calves at 2-hr intervals throughout a 24-hr period. Tartrate-resistant
acid phosphatase isoform 5b (TRAP5b), carboxy-terminal collagen crosslinks of type-I
collagen (CTX), hydroxyproline, bone specific alkaline phosphatase (BALP) and osteocalcin
were measured. Cosinor analysis showed a significant rhythm in all bone markers. The
acrophase of each bone marker appeared from the early to late morning. The percentage
ratio of the amplitude to mesor and the within-subject variability for CTx and osteocalcin
were significantly larger than those for TRAP5b and BALP. This marked diurnal variation in
five bone markers suggested that the time of blood sampling should be fixed when studying
bone marker concentrations in bovine plasma.
This paper reports an on-line sample preconcentration by a sweeping technique based on the surface complexation between TiO 2 (titania) nanoparticles and phosphate groups in the capillary electrophoresis (CE) analysis of phosphopeptides. It is well-known that titania particles can trap phosphopeptides under an acidic condition, while under an alkaline condition they are eluted from the titania surfaces. In the sweeping via solid phase extraction using the titania nanoparticles, a phosphopeptide solution is injected as a long plug into a capillary filled with an acidic background solution. Due to the complexation onto the titania surfaces, the analytes in a long sample zone are swept by the titania particles to a narrow zone. This preconcentration technique was applied to the analysis of monophosphopeptide from β-casein. When an 1% titania dispersion and 100 ppm phosphopeptide solution was successively introduced into the capillary at the injection time of 30 s and 60 s, respectively, a sharp peak of the phosphopeptide was obtained by UV detection without any optical interferences of the titania. Comparing with a conventional CE analysis, a 22-fold sensitivity increase was achieved by the preconcentration effect.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.