Bone Water & Mineralization: Nuclear Magnetic Resonance

骨水

• 批准号: 6671095
• 负责人: Felix W Wehrli
• 金额: $ 32.61万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-09 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6671095
• 关键词: bone density; bone development; bone imaging /visualization /scanning; laboratory rabbit; laboratory rat; mathematical model; normal ossification; nuclear magnetic resonance spectroscopy; osteocytes; osteoporosis; photon absorptiometry; substantia spongiosa

DESCRIPTION (provided by applicant): The mechanical competence of bone is determined by the amount of bone per unit volume (also referred to as apparent density), its structural arrangement and its chemical make-up. Age and osteoporosis-related deterioration of the bone has typically been attributed to a net loss of bone mass and architectural impairment but it has been widely assumed that the bone's intrinsic material properties remain invariant. This notion is in conflict with a substantial body of literature indicating significant decreases in the degree of mineralization of bone (DMB) following ovariectomy and increased DMB in response to antiresorptive treatment. Such a behavior is plausible since the bone turnover rate determines the average age of the bone and younger bone is known to be hypomineralized. Paralleling changes in DMB are the bone's biomechanical properties in that decreased DMB is associated with decreased static strength and Young's modulus. The extent to which mechanical failure in the form of fractures is related to changes in the bone's mineral content is not known. Unfortunately, DMB cannot currently be measured noninvasively. However, since DMB is related to the bone's osteoid water content, information on mineral density can be obtained indirectly. There is evidence that during mineralization some of the matrix water is displaced and its space taken by mineral in such a manner that osteoid volume remains constant. In this proposal we advance the hypothesis that there is an inverse relationship between osteoid water and bone mineral volume and that a measure of DMB can be obtained indirectly by quantitative proton magnetic resonance of solid bone. We provide evidence in preliminary work that decreased mineralization is associated with higher water content and that the matrix water can be imaged with appropriate imaging techniques in intact bone. In two disease models in which DMB is expected to be altered (rabbit osteomalacia and rat ovariectomy) we test the hypothesis using proton and 31P NMR that changes in DMB occur at the expense of a commensurate change in bone water and further that increased bone water decreases static strength and elastic modulus. The long-term goal of this project is to provide a noninvasive method for probing the intrinsic properties of bone in laboratory animals and ultimately in humans.

描述(由申请人提供)： 骨的机械能力取决于单位体积的骨量(也称为表观密度)、其结构排列及其化学组成。与年龄和骨质疏松症相关的骨骼退化通常被归因于骨量的净损失和结构损伤，但人们普遍认为骨骼的内在材料特性保持不变。这一观点与大量文献相矛盾，这些文献表明卵巢切除后骨矿化程度显著降低，而抗吸收治疗增加了骨矿化程度。这种行为是合理的，因为骨转换率决定了骨骼的平均年龄，而年轻的骨骼被认为是矿物质含量较低的。与DMB的变化平行的是骨的生物力学特性，因为DMB的减少与静态强度和杨氏模数的降低有关。骨折形式的机械故障在多大程度上与骨骼矿物质含量的变化有关尚不清楚。不幸的是，目前还不能非侵入性地测量DMB。然而，由于DMB与骨骼的类骨水分含量有关，因此可以间接获得有关矿物质密度的信息。有证据表明，在矿化过程中，一些基质水被置换，其空间被矿物以一种保持类骨体积不变的方式占据。在这一建议中，我们提出了这样的假设，即类骨水与骨矿容量之间存在反向关系，并且可以通过固体骨的定量质子磁共振间接获得DMB的量度。我们在初步工作中提供了证据，证明矿化减少与较高的水含量有关，并且基质水可以通过适当的成像技术在完整的骨骼中成像。在两种疾病模型中，DMB预计会发生改变(兔骨软化症和大鼠卵巢切除)，我们使用质子和31P核磁共振来验证这一假设，即DMB的变化是以骨骼水分的相应变化为代价的，而且骨骼水分的增加会降低静态强度和弹性模数。该项目的长期目标是提供一种非侵入性的方法，用于在实验动物身上并最终在人类身上探测骨骼的内在特性。