Colwell A, Hamer A, Blumsohn A, Eastell R
Department of Human Metabolism and Clinical Biochemistry, Northern General Hospital, Sheffield, UK.
Eur J Clin Invest. 1996 Dec;26(12):1107-14. doi: 10.1046/j.1365-2362.1996.460602.x.
The aims of the study were to characterize the denaturation of urinary free and conjugated pyridinoline (Pyr) and deoxypyridinoline (Dpyr) on exposure to ultraviolet (UV) and natural light at different pH levels and to study the effects of X- and gamma-irradiation on Pyr and Dpyr in urine and in the mineralized and non-mineralized compartments of human bone. Urine samples from six normal subjects, adjusted to pH 3.0, 7.0 and 9.0 were exposed to UV light for up to 3 days. Urine collections (2 mL and 24 h) from three subjects, pH adjusted to 1.0, 2.0, 3.0, 4.0 and 5.0, were exposed to natural light for up to 1 day. Urine samples and bone slices from seven human cadaveric femurs were irradiated with increasing doses of X-rays (0-100 Gy) and high-dose gamma-radiation (28 kGy). Mineralized and non-mineralized bone were separated using a modification of a published method employing heat denaturation followed by trypsin hydrolysis and analysed for Pyr, Dpyr and hydroxyproline (Hypro). The rate of UV photolysis of urinary Pyr and Dpyr increased with pH and was faster in the free fraction (after 3 days' exposure: free Pyr and Dpyr at pH 7.0 vs. 9.0, P < 0.05, conjugated pH 3.0 vs. 9.0, P < 0.05). Exposure to natural light for 3 h did not significantly decrease urinary Pyr and Dpyr in either sample collections, but levels were reduced in the 2-mL aliquots after exposure for 1 day (P < 0.05). X-irradiation of urine and bone did not affect Pyr and Dpyr. Pyr content was similar in both bone compartments (Pyr/ Hypro = 0.12 +/- 0.004), but Dpyr was higher in the non-mineralized compartment (Dpyr/Hypro = 0.047 +/- 0.002 vs. 0.038 +/- 0.002, P < 0.001). UV light and gamma-irradiation result in denaturation of pyridinium cross-links in urine. These cross-links are present in both the mineralized and non-mineralized bone compartments but are not affected by the doses of gamma-irradiation that denature these cross-links in urine.
本研究的目的是表征尿中游离和结合的吡啶啉（Pyr）及脱氧吡啶啉（Dpyr）在不同pH值下暴露于紫外线（UV）和自然光时的变性情况，并研究X射线和γ射线辐照对尿液以及人骨矿化和非矿化部分中Pyr和Dpyr的影响。将来自6名正常受试者的尿液样本调节至pH 3.0、7.0和9.0，暴露于紫外线下长达3天。将来自3名受试者的尿液收集物（2 mL和24小时），pH调节至1.0、2.0、3.0、4.0和5.0，暴露于自然光下长达1天。用递增剂量的X射线（0 - 100 Gy）和高剂量γ射线（28 kGy）辐照来自7例人类尸体股骨的尿液样本和骨切片。采用一种已发表方法的改良方法，通过热变性后用胰蛋白酶水解来分离矿化和非矿化骨，并分析其中的Pyr、Dpyr和羟脯氨酸（Hypro）。尿中Pyr和Dpyr的UV光解速率随pH升高而增加，且在游离部分更快（暴露3天后：pH 7.0与9.0时的游离Pyr和Dpyr，P < 0.05；结合型pH 3.0与9.0时，P < 0.05）。在任何一种尿液收集物中，暴露于自然光3小时均未显著降低尿中Pyr和Dpyr，但暴露1天后2 mL等分试样中的水平降低（P < 0.05）。尿液和骨的X射线辐照未影响Pyr和Dpyr。两个骨部分中的Pyr含量相似（Pyr / Hypro = 0.12 ± 0.004），但非矿化部分中的Dpyr更高（Dpyr / Hypro = 0.047 ± 0.002对0.038 ± 0.002，P < 0.001）。紫外线和γ射线辐照导致尿中吡啶鎓交联物变性。这些交联物存在于矿化和非矿化骨部分中，但不受使尿中这些交联物变性的γ射线剂量的影响。
