Acardiac anomaly: current issues in prenatal assessment and treatment

Acardiac anomaly is a rare condition affecting monochorionic multiple pregnancies. We review this condition with emphasis on its prenatal diagnostic features and treatment options. Due to the parasitic hemodynamic dependence of the acardiac twin on the pump twin, it is important to monitor the pump twin for signs of decompensation and, if indicated, intervene by interrupting vascular supply to the acardiac twin. The goal of treatment is to maximize the pump-twin's chance of survival. To assist with the decision of when to treat, we suggest a new classification system based on prognostic factors, specifically the size and growth of the acardiac twin and the cardiovascular condition of the pump twin. When the acardiac twin is small and no signs of cardiovascular impairment in the pump twin are present, we suggest serial ultrasound surveillance to detect any worsening of the condition. In cases with a large acardiac twin or rapid growth of the acardiac mass, we recommend prompt intervention. Once treatment is indicated, the intrafetal approach to interrupt the vascular supply to the acardiac twin appears to be superior to cord occlusion techniques as it is simpler, safer and more effective. The first line of treatment, if available, should be ultrasound-guided laser coagulation or radiofrequency ablation of the intrafetal vessels. Copyright © 2005 John Wiley & Sons, Ltd.     

用改进的TRAP法测定树木端粒酶活性

TRAP法是一种常用的测定端粒酶活性的方法,但并不太适合测定木本植物的端粒酶活性.因此以油松针叶为实验材料,对TRAP法进行改进.参照前人的研究通过对比实验证明,在端粒酶提取过程中将PEG8000加入上清液,可获得高效的端粒酶.在此基础上,对PCR先导引选择TS、模板浓度选择100 ng,最终获得油松针叶高质量的端粒酶PCR产物.应用SYBR Green I替代银染液对电泳凝胶进行染色,获得条带清晰、重复性好的电泳结果.通过对油松针叶、银杏叶片、胡杨愈伤组织、沙冬青悬浮细胞等4种木本植物实验材料进行测定,证明该改进的技术体系可能是适合于木本植物端粒酶活性测定的稳定的、灵敏度高的可行方法.图5表1参17     

First-trimester ultrasonic diagnosis of twin reversed arterial perfusion sequence

Twin reversed arterial perfusion (TRAP) syndrome sequence is a rare specific anomaly of twin gestation with fused placentae and umbilical anastomosis. This syndrome occurs once in very 35 000–48 000 births and has been described in the second trimester (23-29 weeks of gestation). We report on early sonographic diagnosis (10 and 12 weeks' gestation) of two cases of TRAP sequence, together with their umbilical cord Doppler studies.