Ramakrishnan Nagarajan, Xia Yang, Bidthanapally Aruna
Department of Physics and Center for Biomedical Research, Oakland University, Rochester, MI 48309, USA.
Phys Med Biol. 2007 Aug 7;52(15):4601-14. doi: 10.1088/0031-9155/52/15/016. Epub 2007 Jul 10.
The objective of this spectroscopic imaging study is to understand the anisotropic behavior of articular cartilage under polarized infrared radiation at 6.25 microm pixel resolution. Paraffin embedded canine humeral cartilage-bone blocks were used to obtain 6 microm thick tissue sections. Two wire grid polarizers were used to manipulate the polarization states of IR radiation by setting them for various polarizer/analyzer angles. The characteristics of the major chemical components (amide I, amide II, amide III and sugar) of articular cartilage were investigated using (a) a polarizer and (b) a combination of a polarizer and an analyzer. These results were compared to those obtained using only an analyzer. The infrared anisotropy (variation in infrared absorption as a function of polarization angles) of amide I, amide II and amide III bands correlates with the orientation of collagen fibrils along the tissue depth in different histological zones. An 'anisotropic flipping' region of amide profiles indicates the possibility of using Fourier transform infrared imaging (FTIRI) to determine the histological zones in cartilage. Cross-polarization experiment indicates the resolution of overlapping peaks of collagen triple helix and/or proteoglycan in articular cartilage.
这项光谱成像研究的目的是在6.25微米像素分辨率下，了解偏振红外辐射下关节软骨的各向异性行为。使用石蜡包埋的犬肱骨软骨-骨块获取6微米厚的组织切片。使用两个线栅偏振器，通过将它们设置为不同的起偏器/检偏器角度来操纵红外辐射的偏振态。使用（a）一个偏振器和（b）一个偏振器与一个检偏器的组合，研究关节软骨主要化学成分（酰胺I、酰胺II、酰胺III和糖）的特征。将这些结果与仅使用检偏器获得的结果进行比较。酰胺I、酰胺II和酰胺III带的红外各向异性（红外吸收随偏振角的变化）与不同组织学区域中胶原纤维沿组织深度的取向相关。酰胺谱的“各向异性翻转”区域表明使用傅里叶变换红外成像（FTIRI）确定软骨组织学区域的可能性。交叉偏振实验表明了关节软骨中胶原三螺旋和/或蛋白聚糖重叠峰的分辨率。
