School of Molecular Bioscience, University of Sydney, Sydney, NSW, 2006, Australia,
Eur Biophys J. 2013 Jan;42(1):3-16. doi: 10.1007/s00249-012-0822-8. Epub 2012 May 29.
q-Space plots obtained experimentally using pulsed field-gradient stimulated echo (PGSTE) nuclear magnetic resonance (NMR) spectroscopy from water diffusing in red blood cells (RBCs) of different canonical (distinct variant) morphologies have "signature" features. The experimental q-space plots from suspensions of stomatocytes, echinocytes and spherocytes generated chemically had no diffraction features; in contrast a sample of blood from a patient with hereditary spherocytosis showed diffraction minima. To understand the forms of q-space plots, mathematical/geometrical models of discocytes, stomatocytes, echinocytes and spherocytes were used as restricting boundaries in simulations of water diffusion with Monte Carlo random walks. These simulations indicated that diffusion-diffraction minima are expected for each of the cell shapes considered. The absence of diffusion-diffraction minima in stomatocytes generated by dithiothreitol treatment was surmised to be due to non-alignment of the cells with the magnetic field of the NMR spectrometer. Differential interference contrast microscopy images of the chemically generated spherocyte and echinocyte suspensions showed them to be heterogeneous in cell shape. Therefore, we concluded that the shape heterogeneity caused the loss of the diffusion-diffraction features, which were observed in the more homogeneous sample from a patient with hereditary spherocytosis, and in the simulations of homogeneous cell suspensions. This understanding of factors that affect q-space plots from RBC suspensions will assist morphological studies of other cell and tissue types.
使用脉冲梯度场激励回波（PGSTE）核磁共振（NMR）光谱技术从不同典型（不同变体）形态的红细胞（RBC）中扩散的水获得的 q 空间图谱具有“特征”。通过化学方法产生的口形细胞、棘形细胞和球形细胞悬浮液的实验 q 空间图谱没有衍射特征；相比之下，遗传性球形红细胞增多症患者的血液样本显示出衍射最小值。为了理解 q 空间图谱的形式，使用圆盘细胞、口形细胞、棘形细胞和球形细胞的数学/几何模型作为限制边界，在蒙特卡罗随机漫步模拟水扩散。这些模拟表明，考虑到的每种细胞形状都有望出现扩散-衍射最小值。二硫苏糖醇处理产生的口形细胞中没有扩散-衍射最小值，据推测是由于细胞与 NMR 光谱仪的磁场未对齐。化学生成的球形细胞和棘形细胞悬浮液的微分干涉对比显微镜图像显示它们在细胞形状上存在异质性。因此，我们得出结论，形状异质性导致了从遗传性球形红细胞增多症患者更均匀样本以及均匀细胞悬浮液模拟中观察到的扩散-衍射特征的丢失。这种对影响 RBC 悬浮液 q 空间图谱因素的理解将有助于其他细胞和组织类型的形态研究。
