Peto S, Gillis P, Henri V P
Physique Expérimentale, Faculté de Médecine, Université de Mons-Hainaut, Belgium.
Biophys J. 1990 Jan;57(1):71-84. doi: 10.1016/S0006-3495(90)82508-X.
Nuclear magnetic relaxation times were measured in collagen tissue when varying the orientation of the fiber with respect to the static field. T1 was found to be only slightly dependent on theta, the fiber-to-field angle, but T2 was very sensitive to the orientation, with a maximum value at the magic angle. The transverse decay curves were multiexponential. Their deconvolution displayed four components; the ones that decayed most slowly were almost independent of theta, but the two fastest ones showed a strong angular dependence that was interpreted with a cross-relaxation model. Quadrupolar dips were visible in the 1/T1 dispersion curves. These dips were independent of theta, so that the magnetization transfer could also be assumed to be independent of the fiber orientation. Finally, each component was assigned to a fraction of protons localized in the macromolecular structure and characterized by particular dynamics. The model of Woessner was applied to the water molecules tightly bound into the macromolecules, which resulted in a dynamical description of this water fraction. This description is compatible with the two-sites model of Ramachandran based on x-ray diffraction and with the extensive studies of Berendsen. However, the important indications obtained from the deconvolution lead to a less static representation of the tissue.
在改变纤维相对于静磁场的取向时，测量了胶原组织中的核磁弛豫时间。发现T1仅略微依赖于θ（纤维与磁场的夹角），但T2对取向非常敏感，在魔角处有最大值。横向衰减曲线是多指数的。它们的反褶积显示出四个分量；衰减最慢的那些分量几乎与θ无关，但最快的两个分量表现出强烈的角度依赖性，可用交叉弛豫模型来解释。在1/T1色散曲线中可见四极凹陷。这些凹陷与θ无关，因此也可以认为磁化传递与纤维取向无关。最后，每个分量都被分配给位于大分子结构中的一部分质子，并由特定的动力学特征来表征。将沃斯纳模型应用于紧密结合在大分子中的水分子，从而得到了这部分水的动力学描述。这种描述与基于X射线衍射的拉马钱德兰两点模型以及贝伦森的广泛研究是兼容的。然而，从反褶积中获得的重要迹象导致对组织的静态描述减少。
