Intrauterine growth restriction (IUGR): biometric and Doppler assessment

Intrauterine growth restriction (IUGR) is a common complication in pregnancy and influences morbidity and mortality at all stages of life. Historically, the management of IUGR has been dependent on antenatal biophysical testing and umbilical artery Doppler studies. With recent Doppler studies of the fetal central circulation, including intracardiac flows and the ductus venosus, better timing of delivery to minimize morbidity may be possible. This review will provide the reader with tools to diagnose IUGR, more accurately date the IUGR pregnancy with poor dating criteria, and better assess the condition of the IUGR fetus. A brief review of animal models of IUGR is presented to demonstrate research directions for answering human clinical questions and potentially carrying therapeutic intervention from the bench to the bedside. Copyright © 2002 John Wiley & Sons, Ltd.     

沉积物再悬浮对浮游细菌群落结构的影响

本研究通过小宇宙的模拟实验,设置3组处理,即无再悬浮的对照组(C)、强(SR)和弱(WR)2个不同再悬浮强度的处理组,采用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)分析不同处理组中浮游细菌群落结构的变化.结果表明,再悬浮处理组浮游细菌的物种丰度高于对照组,并且弱再悬浮中浮游细菌物种丰度高于强再悬浮处理.弱再悬浮中细菌多样性也高于强再悬浮处理.浮游细菌与环境因子的典型对应分析(CCA)和冗余分析(RDA)结果表明,浮游动物枝角类(Cladocera)生物量和颗粒态磷(PP)浓度与浮游细菌群落结构动态变化均表现出显著的相关性(p0.05).由此可见,沉积物再悬浮对浅水湖泊浮游细菌的种类和多样性存在重要影响,其可能通过影响浮游动物群落结构以及水体中营养盐的形态和浓度对浮游细菌群落产生影响.     

黄土高原六道沟流域8种植物根际细菌与AMF群落多样性研究

采用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,研究了神木县六道沟流域8种植物根际细菌与丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性及其相互关系.目的是获得有关植物根际细菌和AMF群落的多样性指数,为生态环境修复提供科学依据.结果表明,8种植物根际细菌和AMF的种类和数量有较大差异,其中刺槐根际细菌的Shannon指数最高(4.01),垂柳最低(2.18),根际AMF的Shannon指数最高为小叶杨(2.07),最低为沙棘(1.21);聚类分析(cluster analysis)和冗余分析(redundancy analysis)结果表明,不同植物根际细菌和AMF的群落结构有较大差异,但同时部分植物间也存在相似性;8种植物根际细菌和AMF的多样性指数总体呈极显著的正相关(P<0.01);冗余分析结果表明在根际土壤环境因子中,对根际微生物群落多样性影响最大的环境因子为有机质含量.植物种类和根际环境对根际微生物群落结构有较大影响,同时,刺槐的根际细菌和AMF群落多样性指数均较高,故可作为六道沟流域植被恢复的先锋树种.     

Non-mosaic trisomy 22: a report of 2 cases

Non-mosaic trisomy 22 is a common cause of first trimester miscarriage and has a livebirth incidence of 1 in 30 000–50 000. Consequently there is a paucity of information for counselling parents. Detection in the second trimester is rare. It is commonly associated with severe growth retardation and multiple structural abnormalities. Oligohydramnios is frequently seen and can make detection of other abnormalities difficult. The outlook is uniformly poor and survival beyond the first trimester may present management dilemmas. A thorough fetal assessment including high-resolution cytogenetics with or without FISH is required for counselling. Careful plans for intrapartum and neonatal management may be necessary. The recurrence risk is thought to be low but information is very limited as there have been no reported cases of recurrence. We present two case of non-mosaic trisomy 22 including the first to be diagnosed subsequent to investigation for a high serum screening Down's risk. Copyright © 2006 John Wiley & Sons, Ltd.