Sarathchandra P, Kayser M V, Ali S Y
Department of Experimental Pathology, Institute of Orthopaedics University of London, Royal National Orthopeadic Hospital, Stanmore, Middlesex, HA7 4LP, UK.
Calcif Tissue Int. 1999 Jul;65(1):11-5. doi: 10.1007/pl00005829.
Osteogenesis imperfecta (OI) is a genetic disorder of the connective tissue characterized by frequent bone fractures. The cause of bone fragility is still unknown even though substantial work on collagen has been done. We measured the calcium to phosphorus ratio (Ca/P) of bone mineral from 35 OI bone samples and 25 age- and site-matched control specimens, using electron probe X-ray microanalysis in the transmission electron microscope. Ultra-thin cryosections and conventionally prepared resin sections were used. Cryo-ultramicrotomy avoids any possible artifactual demineralization that may occur in conventional aqueous media. The Ca/P ratio obtained by these two methods was compared and there was no statistical difference between them. The results were differentiated according to the clinical types of OI for the first time. The Ca/P ratio of OI bone mineral was lower than normal in both resin and cryosections, and mirrored the severity of the disease. OI type II had the lowest ratio (Ca/P = 1.49) compared with normal age- and site-matched controls (Ca/P = 1.69). This abnormal mineral composition in OI type II could be a contributory factor to bone fragility in OI bone.
成骨不全症（OI）是一种结缔组织的遗传性疾病，其特征为频繁发生骨折。尽管在胶原蛋白方面已经开展了大量工作，但骨骼脆弱的原因仍然未知。我们使用透射电子显微镜中的电子探针X射线微分析法，测量了35份OI骨样本以及25份年龄和部位匹配的对照样本的骨矿物质钙磷比（Ca/P）。使用了超薄冷冻切片和常规制备的树脂切片。冷冻超薄切片术避免了在传统水性介质中可能发生的任何人为脱矿现象。对通过这两种方法获得的Ca/P比进行了比较，两者之间没有统计学差异。首次根据OI的临床类型对结果进行了区分。在树脂切片和冷冻切片中，OI骨矿物质的Ca/P比均低于正常水平，并且反映了疾病的严重程度。与年龄和部位匹配的正常对照（Ca/P = 1.69）相比，II型OI的比值最低（Ca/P = 1.49）。II型OI中这种异常的矿物质组成可能是OI骨骨骼脆弱的一个促成因素。
