Fratzl P, Paris O, Klaushofer K, Landis W J
Ludwig Boltzmann Institute for Osteology, 4th Medical Department, Hanusch Hospital, Vienna, Austria.
J Clin Invest. 1996 Jan 15;97(2):396-402. doi: 10.1172/JCI118428.
We have studied the size and orientation of mineral crystals in cortical bone of oim/oim mice, which are known to produce only alpha 1(I) collagen homotrimers and which may serve as a model for human osteogenesis imperfecta. Long bones (femur and tibia) from young (5 wk old) oim/oim mice and from unaffected heterozygous counterparts were investigated by small-angle x-ray scattering (SAXS), which is sensitive to structures smaller than 50 nm. Mineral crystals were compared in terms of their thickness and their alignment with respect to the long bone axis. While electron microscopic tomography has recently shown the existence of large mineral blocks (with all dimensions typically exceeding 50 nm) in mineralized tendons of oim/oim mice, SAXS revealed a family of thin, possibly needle-like, crystals in cortical bone. These crystals were similar in shape to those observed previously in normal mice, but they were thinner and less well aligned in oim/oim mice relative to heterozygotes. Moreover, the crystal thickness and their alignment with the bone axis were more variable in oim/oim bone, with a close correlation (r = 0.94, P < 0.001) between the two parameters. The presence of smaller crystals with more variable alignment in corticalis of oim/oim mice may contribute to the brittleness of their bone, similar to that of human osteogenesis imperfecta.
我们研究了骨质疏松小鼠（oim/oim）皮质骨中矿物晶体的大小和取向，已知该小鼠仅产生α1（I）胶原同三聚体，可作为人类成骨不全症的模型。通过小角X射线散射（SAXS）对5周龄的年轻oim/oim小鼠及其未受影响的杂合子对应体的长骨（股骨和胫骨）进行了研究，SAXS对小于50nm的结构敏感。比较了矿物晶体的厚度及其相对于长骨轴的排列。虽然最近电子显微镜断层扫描显示oim/oim小鼠矿化肌腱中存在大的矿物块（所有尺寸通常超过50nm），但SAXS显示皮质骨中有一族薄的、可能呈针状的晶体。这些晶体的形状与先前在正常小鼠中观察到的相似，但相对于杂合子，它们在oim/oim小鼠中更薄且排列更差。此外，oim/oim骨中晶体厚度及其与骨轴的排列变化更大，这两个参数之间存在密切相关性（r = 0.94，P < 0.001）。oim/oim小鼠皮质骨中存在排列更可变的较小晶体可能导致其骨骼易碎，类似于人类成骨不全症。
