Optical and acoustical dynamics of microbubble contrast agents inside neutrophils
Optical and acoustical dynamics of microbubble contrast agents inside neutrophils
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DOI：
10.1016/s0006-3495(01)76127-9
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发表时间：
2001-03-01
影响因子：
3.4
通讯作者：
Ferrara, KW
中科院分区：
文献类型：
--
作者：
Dayton, PA;Chomas, JE;Ferrara, KW
声学活性微泡用于器官灌注的对比增强超声评估。在炎症区域，造影剂被粘附在小静脉壁上的活化中性粒细胞捕获和吞噬。使用直接的光学观察与高速摄像机和声学询问的个别气泡和细胞，我们评估了吞噬和自由微泡的物理和声学响应。光学分析的气泡径向振荡过程中的声波表明，吞噬的微泡的细胞质内的粘性阻尼，但仍然保持声学活性，并能够在声脉冲的大体积振荡。拟合的瑞利-Plesset方程，描述了薄壳的机械性能的光学半径-时间数据的振荡气泡提供的细胞内介质的表观粘度的估计的修改版本。吞噬的微泡经历了一个粘性阻尼约7倍大于自由微泡。自由和吞噬的微泡之间的声学比较表明，吞噬的微泡产生的回声具有较高的平均频率比自由的微泡在响应于稀疏第一单周期脉冲。此外，这种频率增加预测使用修改的瑞利-Plesset方程。我们的结论是，对比增强超声可以检测不同的声学信号从微泡内的中性粒细胞，并可能提供一个独特的工具，以确定激活的中性粒细胞在炎症部位。
Acoustically active microbubbles are used for contrast-enhanced ultrasound assessment of organ perfusion. In regions of inflammation, contrast agents are captured and phagocytosed by activated neutrophils adherent to the venular wall. Using direct optical observation with a high-speed camera and acoustical interrogation of individual bubbles and cells, we assessed the physical and acoustical responses of both phagocytosed and free microbubbles. Optical analysis of bubble radial oscillations during insonation demonstrated that phagocytosed microbubbles experience viscous damping within the cytoplasm and yet remain acoustically active and capable of large volumetric oscillations during an acoustic pulse. Fitting a modified Version of the Rayleigh-Plesset equation that describes mechanical properties of thin shells to optical radius-time data of oscillating bubbles provided estimates of the apparent viscosity of the intracellular medium. Phagocytosed microbubbles experienced a viscous damping approximately sevenfold greater than free microbubbles. Acoustical comparison between free and phagocytosed microbubbles indicated that phagocytosed microbubbles produce an echo with a higher mean frequency than free microbubbles in response to a rarefaction-first single-cycle pulse. Moreover, this frequency increase is predicted using the modified Rayleigh-Plesset equation. We conclude that contrast-enhanced ultrasound can detect distinct acoustic signals from microbubbles inside of neutrophils and may provide a unique tool to identify activated neutrophils at sites of inflammation.