Rapid prenatal diagnosis of trisomy 18 and triploidy in interphase nuclei of uncultured amniocytes by non-radioactive in situ hybridization

Two biotinylated chromosome-specific DNA probes were used to quantify the number of chromosomes 18 and 1 in uncultured amniocytes. Thirty-three samples of uncultured amniocytes were hybridized with a chromosome 18-specific DNA probe. Uncultured cells from two of the 33 samples were also hybridized with a chromosome 1-specific probe. Thirty of the samples were disomic with respect to chromosome 18; two samples were trisomic with respect to chromosome 18, and one sample was trisomic with respect to chromosomes 1 and 18. The two cases of trisomy 18 and the single case of triploidy were identified on uncultured celis within 48-72 h after amniocentesis. They were found among five samples from pregnant women who had amniocentesis because of an ultrasonographically identified fetal malformation. A trisomic karyotype could be diagnosed with certainty in uncultured amniocytes because the majority of the responding nuclei exhibited three hybridization signals. In normal cells, the majority of nuclei exhibited two signals. In no cases was there discordance between the genotype as predicted by in situ hybridization and that determined by cytogenetic analysis.     

Umbilical cord pseudocyst in trisomy 18

Prenatal diagnosis of cord defects by means of ultrasound examination is possible and highly accurate. Although this is a rare pathological finding, we report two cases in which umbilical cord pseudocysts were associated with trisomy 18. These observations underscore the need of umbilical blood sampling for establishing the karyotype in fetuses with such umbilical cord anomalies and the importance of careful examination of placentas and infants born with such defects.     

The significance of choroid plexus cysts in fetuses at 18–20 weeks. An indication for amniocentesis?

Over a period of 25 months, all antenatal patients were offered a detailed ultrasound scan at 18–20 weeks' gestation. The lateral cerebral ventricles were scanned for the presence of choroid plexus cysts. Fifty-one patients found to have choroid plexus cysts were offered amniocentesis to exclude chromosomal abnormalities. One pregnancy, in which the only abnormality found was bilateral choroid plexus cysts, was terminated after trisomy 18 was detected on amniocentesis at 19 weeks. The other 50 pregnancies had normal fetal outcomes. The significance of the isolated finding of choroid plexus cysts is reviewed.     

Retrospective study of trisomy 18 in chorionic villi with fluorescent in situ hybridization on archival direct preparations

Trisomy 18 in direct chorionic villus preparations needs further investigation since the chromosome abnormality may be confined to the placenta and may not represent the actual fetal karyotype. We performed, retrospectively, fluorescent in situ hybridization (FISH) with the chromosome 18 centromere probe (L1.84) on interphase nuclei of destained slides of all cases of full trisomy 18 (n=22) and mosaic trisomy 18 (n=8) detected among 7600 first-trimester chorionic villus samples during an 8-year period (1985–1992). More nuclei displaying three signals were encountered in cases of full and mosaic trisomy 18 confirmed in fetal tissue than in non-confirmed cases. FISH can be useful for the verification of trisomy 18 in direct chorionic villus preparations.     

18CrNi4WA 钢渗碳针阀体开裂失效分析

目的研究18CrNi4WA钢渗碳针阀体开裂失效原因。方法通过化学成分分析、断口扫描分析、金相组织分析、能谱分析等测试手段,对18CrNi4WA钢渗碳针阀体的断裂模式及失效原因进行分析。结果针阀体失效件原始材料符合针阀体制造要求,但渗碳淬火温度过高,未得到最优的渗碳层组织,燃油中存在的硫元素导致喷油孔位置产生严重腐蚀,燃油局部压力的变化导致针阀体表面产生空蚀损伤,裂纹起始于喷油孔圆周面,自裂纹源向外发散呈月牙状,为典型疲劳断裂特征。结论腐蚀与空蚀损伤的协同作用加快裂纹的萌生,使针阀体在热疲劳及机械振动等交变载荷的作用下产生疲劳开裂,使用寿命大为降低。     

Regional economic conditions and crash fatality rates--a cross-county analysis

INTRODUCTION: Most studies that evaluate the relationship between economic conditions and traffic fatalities focus on the time-series relationship between the two factors. This analysis considers the cross-sectional perspective by estimating the cross-county correlation between per capita income and fatalities per vehicle mile traveled (VMT) in Ohio. METHOD: The empirical model employed in this analysis allows for interaction effects between per capita income and highway usage, in the determination of fatality rates. RESULTS: The resultant least squares estimates indicate that a significant interaction effect exists between per capita income and the percentage of highway VMT, indicating a nonlinear correlation between per capita income and fatality rates. This correlation rises as the proportion of VMT on highways rises, such that there is an inverse relationship with fatality rates when the highway share of county VMT is low and a direct relationship with fatality rates when the highway share of county VMT is high. Additionally, population density, the presence of interstate highways in rural counties, the prior prevalence of severe alcohol abuse, and the proportion of teen drivers all proved to be significant correlates with county fatality rates. CONCLUSIONS: These observations suggest factors that state and federal policy makers should consider when allocating resources that impact (whether directly or indirectly) traffic fatalities.     

HPLC法测定镉、砷胁迫下水稻根系的植物螯合肽

利用monobromobimane衍生试剂,通过反相高效液相色谱-荧光检测体系对镉、砷胁迫下水稻根系内的植物螯合肽(PCs)等巯基化合物进行形态和含量的分析测定.结果表明,采用乙腈和0.1％三氟乙酸组成的两元梯度流动相,可以将标准样品中的谷胱甘肽(GSH)和PCs等巯基化合物很好地分离.利用上述方法,能较好地分离Cd、...     

Gas stable isotopic ratio mass spectrometry for measuring δ^13C and δ^18O in background atmospheric CO2

将商用MAT253稳定同位素比质谱仪、Airtrap高效预浓缩气体捕集阱与自加工16口自动进样器集成,建立了高精度气体稳定同位素比质谱分析系统,用于程序化自动分析本底大气CO2的δ^13C和δ^18O．气样分析时用工作标气定量并穿插目标气测定,还定期用实验室上一级标气对工作标气和参比气进行标校,以保证分析结果的可靠和可比．结果表明,利用不同稳定同位素比范围的标气重复进样测试,发现该系统对δ^13C和δ^18O的分析精度分别优于0．03‰和0．06‰,能基本满足本底大气CO2的碳氧稳定同位素比分析需求和WMO／GAW质量目标．     

一种新的有机污染物C18 EmporeTM膜/水分配系数测定方法的探讨

本文采用C18Empore^TM膜替代正辛醇模拟生物体,建立了一套新的C18Empore^TM膜／水分配系数的测定方法,并从理论和实验两方面分析了C18Empore^TM膜／水分配 系数与正辛醇／水分配系数的异同点。实验结果表明,此法测定混合有机化合物的C18Empore^TM膜／水分配系数,可以取得较为满意的结果,这种新的有机污染物C18Empore^TM膜／水分配系数测定方法的建立,可为受污染可流中混合有机物生物富集因子（BCF）的预测和水环境纳污容量的评价提供技术支持,也为多经且分有机化合物定量结果－活性相关（QSARs）的研究和实际应用开辟广阔前景。     

2,4-二硝基苯肼衍生高效液相色谱法测定水中乙醛、丙烯醛

采用2,4-二硝基苯肼高效液相色谱法测定水中乙醛、丙烯醛,方法干扰少,精密度高,检出限达到1μg/L。