Analysis and Simulation of Molecular Dynamics of Lysozyme in Water Cluster System

The influence of water on protein conformation was investigated by simulating the molecular dynamics of a model protein lysozyme in different water systems.The lysozyme-water system with TIP3P water model and lysozyme-water cluster system with six-ring water model were evaluated.In addition,the radial distribution function of solvent around lysozyme was calculated.It is found that the distribution of water molecules around lysozyme is similar to that of water clusters.The analyses of dihedral angles and disulfide bonds of lysozyme show that the conformation of lysozyme is severely damaged in the lysozyme-water cluster system compared with that in the lysozyme-water system.This difference can be attributed to the formation of larger number of intermolecular hydrogen bonds between lysozyme and water cluster.It is in agreement with the analysis that water clusters can change the degree of denaturation in the process of heat denaturation of lysozyme.

超声软标记及结构畸形在染色体异常胎儿产前诊断中的临床价值

目的:探讨超声软标记及结构畸形在染色体异常胎儿产前诊断中的临床价值。方法:回顾性纳入2017年1月~2019年12月在我院检查具有超声软标记或结构畸形的1510例胎儿,对染色体核型分析结果及超声征象特点进行总结分析,比较超声软标记与结构畸形胎儿中的染色体异常情况。结果:1510例胎儿中染色体异常胎儿90例(6.0%),21-三体(65例,72.2%)、18-三体(14例,15.6%)为主要染色体异常类型。90例染色体异常胎儿中单个超声软标记27例(30.0%)、多个超声软标记30例(33.3%)、单发结构畸形20例(22.2%)、多发结构畸形13例(14.4%)。单个超声软标记以鼻骨发育不良多见(10例,37.0%);多个超声软标记中17例(56.7%)伴有鼻骨发育不良,15例(50.7%)伴有NT增厚;单发结构畸形以心血管畸形为主(14例,70.0%);多发结构畸形均伴有心血管畸形。多发结构畸形胎儿中的染色体异常检出率[15.5%(13/84) vs 9.5%(20/210)]明显高于单发结构畸形(P<0.05),结构畸形胎儿中的染色体异常检出率[11.2%(33/294) vs 4.7%(57/1216)]明显高于超声软标记(P<0.05)。结论:超声软标记或结构畸形胎儿中染色体异常的检出率较高。对存在结构畸形特别是多发结构畸形的胎儿,建议行染色体核型分析明确诊断。