| 1. |
- Ivaska, KK, et al.
(författare)
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Identification of novel proteolytic forms of osteocalcin in human urine
- 2003
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Ingår i: Biochemical and Biophysical Research Communications. - 1090-2104. ; 306:4, s. 973-980
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we report the isolation and characterization of osteocalcin in human urine using mass spectrometry and N-terminal sequencing. Multiple proteolytic forms of osteocalcin were found, which consisted of 16-27 residues from the middle region of the molecule. Several fragments had residue Gly7 at the N-terminus and the most predominant was fragment 7-31. Additional fragments starting from residue Asp14 were detected in the samples of children and young adults. Immunochemical detection of urine osteocalcin fragments had a statistically significant negative correlation to bone mineral density in evaluation of urine samples from 75-year-old women. Thus, the measurement of osteocalcin fragments in urine may have potential applications in diagnostics related to disorders of bone metabolism.
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| 2. |
- Ivaska, KK, et al.
(författare)
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Urinary osteocalcin as a marker of bone metabolism
- 2005
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 51:3, s. 618-628
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Tidskriftsartikel (refereegranskat)abstract
- Background: Osteocalcin (OC) is produced by osteoblasts during bone formation, and circulating OC has been used in clinical investigations as a marker of bone metabolism. OC is excreted into urine by glomerular filtration and can be found in urine as midmolecule fragments. Methods: We developed and evaluated three immunoassays (U-MidOC, U-LongOC, and U-TotalOC) for the detection of various molecular forms of urine OC (U-OC. We evaluated the association of U-OC with other markers of bone turnover and with bone mass in 1044 elderly women and studied seasonal and circadian variation of U-OC. Results: U-OC correlated with other bone turnover markers [Spearman correlation (r), 0.30-0.57; P <0.0001], demonstrating the association between U-OC and skeletal metabolism. There was also a significant association between bone metabolism assessed by U-OC quartiles and bone mass assessed by total body bone mineral content (P <0.0001). The seasonal effects appeared to be rather small, but we observed A significant circadian rhythm similar to the one reported for serum OC with high values in the morning and low values in the afternoon. Conclusions: The three immunoassays had unique specificities toward different naturally occurring U-OC fragments. U-OC concentrations measured with any of these assays correlated with bone turnover rates assessed by conventional serum markers of bone metabolism. The measurement of OC in urine samples could be used as an index of bone turnover in monitoring bone metabolism.
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