Background

Amyloid plaque in the brain is associated with a wide range of neurodegenerative diseases such as Alzheimer's and Parkinson's and defined as aggregates of amyloid fibrils rich in β-sheet structures.

New method

We report a label-free method based on small-angle X-ray scattering (SAXS) to estimate amyloid load in an intact mouse head with skull. The method is based on recording and analyzing the X rays elastically scattered from the β-sheets of amyloid plaques in a mouse head at angles smaller than 10° and energies between 30 and 45 keV. The method is demonstrated by acquiring the spectral SAXS data of an amyloid model and an excised head from a wild-type mouse for 600 s.

Results

We captured the distinct scattering peaks of the amyloid plaques at momentum transfer (q) of 6 and 13 nm⁻¹ associated with β-sheet structure. We first show linear correlation between the mass fraction of the amyloid target and the area under the peak (AUP) of the scattering curve. We report results for estimating amyloid load in a fixed mouse head by recovering the characteristic scattering signal from the amyloid target situated at various locations. The coefficient of variation in the amyloid load estimate is found to be less than 10%.

Comparison with existing methods

There are no previously described label-free X-ray methods for the estimation of amyloid load in an intact head.

Conclusions

We demonstrated the feasibility of a label-free method based on SAXS to potentially estimate brain amyloid in small animals.

中文翻译：

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无标记X射线方法评估小型动物脑淀粉样蛋白负荷的可行性。

背景

大脑中的淀粉样斑块与多种神经退行性疾病（例如阿尔茨海默氏病和帕金森氏病）有关，并定义为富含β-折叠结构的淀粉样蛋白原纤维的聚集体。

新方法

我们报告基于小角度X射线散射（SAXS）的无标签方法来估计完整的颅骨小鼠头部中的淀粉样蛋白负荷。该方法基于记录和分析以小于10°的角度和30至45 keV的能量从小鼠头部的淀粉样蛋白斑块的β-片弹性散射的X射线。通过在600 s内从野生型小鼠获取淀粉样蛋白模型和切除的头部的光谱SAXS数据来证明该方法。

结果

我们捕获了与β-片状结构相关的动量转移（q）为6和13 nm ^-1的淀粉样蛋白斑块的独特散射峰。我们首先显示淀粉样蛋白靶的质量分数与散射曲线的峰下面积（AUP）之间的线性相关性。我们报告了通过从位于不同位置的淀粉样蛋白靶标回收特征散射信号来估计固定鼠标头中淀粉样蛋白负荷的结果。发现淀粉样蛋白负荷估算中的变异系数小于10％。

与现有方法的比较

以前没有描述用于评估完整头中淀粉样蛋白负荷的无标记X射线方法。

结论

我们证明了基于SAXS的无标记方法潜在地估计小动物脑淀粉样蛋白的可行性。