Hasegawa Kosei, Kataoka Kyoko, Inoue Masaru, Seino Yoshiki, Morishima Tsuneo, Tanaka Hiroyuki
Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan.
J Bone Miner Metab. 2008;26(4):394-9. doi: 10.1007/s00774-007-0827-z. Epub 2008 Jul 4.
Patients with osteogenesis imperfecta (OI) show various degrees of bone fragility. Nevertheless, details of the mechanisms causing bone fragility remain unclear. We hypothesized that differences in pyridinoline cross-link formation at the N-and C-termini in type I collagen molecules partly contribute to bone fragility of OI. To verify this hypothesis, urinary N and C terminal telopeptides of type I collagen (uNTx and ubetaCTx, respectively) and urinary hydroxyproline (uHyp) were measured using second morning void urine samples obtained from OI patients and healthy control children. Ratios of uNTx and ubetaTx to uHyp (uNTx/uHyp and ubetaCTx/uHyp, respectively) of OI patients and healthy normal control children were analyzed. Ratios of uNTx to ubetaCTx (uNTx/ubetaCTx) were also analyzed. In OI patients, uNTx and ubetaCTx were lower than in healthy control children. Also, uNTx/uHyp and ubetaCTx/uHyp were significantly lower than in healthy children. Among OI patients, uNTx/uHyp and uNTx/ubetaCTx of type III OI were significantly lower than of either type I or type IV OI. These results show that pyridinoline cross-link formation is lower than in healthy control children and that pyridinoline cross-link formation at the N-and C-termini in type I collagen molecules might be differently disrupted in OI patients according to the severity of OI.
成骨不全症（OI）患者表现出不同程度的骨脆性。然而，导致骨脆性的机制细节仍不清楚。我们推测I型胶原分子N端和C端吡啶啉交联形成的差异部分导致了OI的骨脆性。为了验证这一假设，我们使用从OI患者和健康对照儿童采集的晨尿样本测量了I型胶原的尿N端和C端末端肽（分别为uNTx和uβCTx）以及尿羟脯氨酸（uHyp）。分析了OI患者和健康正常对照儿童的uNTx和uβTx与uHyp的比值（分别为uNTx/uHyp和uβCTx/uHyp）。还分析了uNTx与uβCTx的比值（uNTx/uβCTx）。在OI患者中，uNTx和uβCTx低于健康对照儿童。此外，uNTx/uHyp和uβCTx/uHyp显著低于健康儿童。在OI患者中，III型OI的uNTx/uHyp和uNTx/uβCTx显著低于I型或IV型OI。这些结果表明，吡啶啉交联形成低于健康对照儿童，并且I型胶原分子N端和C端的吡啶啉交联形成在OI患者中可能根据OI的严重程度而受到不同程度的破坏。
