Department of Mechanical Engineering, University of Wisconsin, Madison, United States.
Med Eng Phys. 2010 Dec;32(10):1116-23. doi: 10.1016/j.medengphy.2010.08.001.
This study investigated whether the deficits in bone strength of pre-pubertal pigs, induced by short-term deficits in dietary calcium can be recovered if followed by a calcium-fortified diet. Young pigs were divided into two groups based on diet: a marginal Ca diet (70% of established Ca requirements) or an excess Ca diet (150% of established Ca requirements) for 4 weeks. Each group was then randomly sub-divided into two groups and fed diets with either marginal or excess dietary Ca for 6 weeks in a cross-over design, resulting in four treatment groups: H150-H150, H150-L70, L70-H150, and L70-L70. Animals were DXA scanned at 2-week intervals during the 10-week period to obtain whole body bone mineral content (BMC) and density (BMD). After animals were euthanized, right femurs were collected for this study. Traits such as bone mineral density, mass, volume, area moment of inertia (MI) and the section modulus (SM) were computed from computed tomography (CT) data and failure load was measured from four-point bending tests. DXA results showed significant reduction in BMC (61.6%) and BMD (37.5%) in the (L70-L70) group compared to the (H150-H150) group. DXA results additionally showed that deficiencies induced by the 4-week marginal Ca diet in the (L70-H150) group were not recovered with a subsequent excess Ca diet. While mechanical test results also showed significant reduction (75%) in strength in the L70-L70 group, compared to the H150-H150 group, they revealed no differences between the failure loads of the (L70-H150) group and the (H150-H150) group. Similar results were also found for bone mineral mass and volume, indicating that recovery from a short-term dietary Ca deficiency is possible at the pre-pubertal stage. Furthermore, bone mineral content and bone volume calculated from CT data correlated highly with failure load (R(2)=0.78 and 0.84, respectively), while density, MI and SM only showed weak-to-moderate correlations (R(2)=0.40-0.56), implying that bone mineral mass and volume calculated from CT data are good non-invasive surrogates for strength of growing bones.
本研究旨在探讨短期饮食钙缺乏导致的未成年猪骨强度缺陷是否可以通过随后的补钙饮食来恢复。根据饮食将幼猪分为两组：低钙饮食组（钙需求量的 70%）或高钙饮食组（钙需求量的 150%），喂养 4 周。然后，每个组随机分为两组，以交叉设计的方式分别用低钙或高钙饮食喂养 6 周，共分为 4 个治疗组：H150-H150、H150-L70、L70-H150 和 L70-L70。在 10 周期间，每隔两周对动物进行双能 X 线吸收法（DXA）扫描，以获得全身骨矿物质含量（BMC）和密度（BMD）。动物安乐死后，收集右侧股骨进行研究。从计算机断层扫描（CT）数据中计算出骨矿物质密度、质量、体积、截面惯性矩（MI）和截面模数（SM）等特征，并从四点弯曲试验中测量断裂载荷。DXA 结果显示，与 H150-H150 组相比，L70-L70 组 BMC（61.6%）和 BMD（37.5%）显著降低。DXA 结果还表明，4 周低钙饮食引起的（L70-H150）组缺陷未随随后的高钙饮食恢复。虽然机械测试结果还显示 L70-L70 组的强度显著降低（与 H150-H150 组相比，降低 75%），但（L70-H150）组和 H150-H150 组之间的断裂载荷无差异。骨矿物质质量和体积也有类似的结果，表明在青春期前阶段，短期饮食钙缺乏是可以恢复的。此外，从 CT 数据计算的骨矿物质含量和骨体积与断裂载荷高度相关（R²=0.78 和 0.84），而密度、MI 和 SM 仅显示出弱到中度的相关性（R²=0.40-0.56），这意味着从 CT 数据计算的骨矿物质质量和体积是生长骨骼强度的良好非侵入性替代指标。
