Maternal cell contamination in chorionic villus samples assessed by direct preparations and three different culture methods

Presumptive maternal cell contamination (MCC) was monitored in identified male cases during cytogenetic comparison of direct techniques and three different culture regimes from 140 thoroughly dissected chorionic villus samples. Of the 66 identified male cases, 11(16·7 per cent) showed MCC, the mean number of cells examined per case being 8·2 (direct) and 14·5 (cultures); in the direct preparations only one of a total of 457 cells examined was female, while preparations from cultures revealed MCC in 11 cases. Four of these had MCC in more than one culture regime and four had only a single female cell. The results showed that (1) dependence on the culture system alone would have given a diagnosis based on maternal cells in one (1·5 per cent) male case, thus underlining the danger of this approach (a similar undetected rate of misdiagnosis being expected in the female cases) and (2) MCC was significantly lower in cultures grown in Chang medium as compared with the other two regimes, McCoy's 5A + 15 per cent fetal calf serum and 1 per cent Ultroser G, and McCoy's 5A + 25 per cent fetal calf serum, the latter expressing the highest level of MCC.     

Follow-up of pregnancies complicated by placental mosaicism diagnosed by chorionic villus sampling

Thirty-nine (2.3 per cent) of 1724 chromosome studies from diagnostic chorionic villus samplings (CVS) done between 1983 and 1990 showed either level III (true) mosaicism (1.2 per cent) or level II (pseudo-) mosaicism (1.1 per cent) for chromosomal aneuploidy. Follow-up information on these 39 pregnancies was collected from questionnaires to families, paediatricians, and obstetricians. For all cases in which the pregnancy was continued and further testing was accomplished, the mosaicism was felt to be confined to the placenta. As compared with a control group of pregnancies evaluated by CVS with normal karyotypes, there was no increased incidence of pregnancy loss, congenital malformations, or developmental delay in the infants. Although intrauterine growth retardation occurred in several of the level III mosaic cases, adequate catch-up growth has been demonstrated.     

Cytogenetic diagnoses after chorionic villus sampling are less reliable in very-high- or very-low-risk pregnancies

An increasing number of cytogenetic prenatal diagnoses are performed on chorionic villus samplings. The accuracy of this method is influenced by chromosomal mosaicism, mostly confined to direct preparation methods. Especially those investigators who have experienced false-negative and false-positive findings propagate the combined use of direct and culture methods. Yet large collaborative studies have shown that in approximately two-thirds of diagnostic cases only one procedure is applied. Moreover, the accuracy of a cytogenetic investigation depends not only on the ontogenetic origin of the tissues investigated, but also on interacting factors such as the ‘a priori risk’ and the ‘predictive value of a cytogenetic finding’. On this basis a differentiated prenatal diagnostic procedure is discussed, including either sole short-term culture (STC), combined STC and long-term culture (LTC), primary amniocentesis (AC), or primary percutaneous umbilical blood sampling (PUBS). The predictive value of the cytogenetic diagnosis from CVS varies significantly dependent on the a priori risk of a chromosome aberration and, in the case of an abnormal karyotype, on the specific chromosome involved. A non-mosaic and ‘non-lethal’ trisomy detected in STC is highly representative of the embryo/fetus, but there are exceptions of limited predictive value, e.g., trisomy 18. Guided by the strategy of an optional follow-up by LTC, AC, or PUBS in 1317 successive CV samplings, we are not aware of a false-negative diagnosis, but probably had one false-positive diagnosis: 47,XXY after STC; 46,XY after LTC. When referring to the rate of fetuses with an unbalanced karyotype expected in the different indication groups, a relative increase of false-positive findings in the very-low-risk group (maternal age ⩽35 years of age) and of false-negative findings in the very-high-risk group (abnormal ultrasonographic findings) of pregnant women when only performing CVS becomes obvious. Because of this dilemma, AC or—especially in the latter group—PUBS might be primarily offered to these indication groups instead of CVS.     

网格采样-聚类分析在优化环境监测点中的应用

为了在最少的采样点位获得具有代表性的监测数据，采用网格采样—聚类分析法对沈阳经济技术开发区的空气监测采样点进行了优化研究，从14个采样点位中优选出了4个采样点位。在保证监测数据的可靠性的前提下，节省了监测费用。     

悬浮液进样FAAS法测定黄棕壤中的微量铜

本文采用悬浮进样火焰原子吸收光谱法测定黄棕壤中微量铜 ,并对样品的研磨时间、悬浮液浓度、酸度选择及校正方法等进行了探讨。实验表明 :该法的检出限 (K =3)为 0 .12μg· g-1,精密度 (RSD)为4.6 % ,加标回收率为 98～ 10 6 % ,对水系沉积物 GSD5、GSD6标准样品测定结果与推荐值吻合。     

Ultrastructure of first trimester chorionic villi with regard to the prenatal diagnosis of genodermatoses

Hopes are held out for chorion villus sampling, a technique which is gaining more and more importance for the first trimester prenatal diagnosis of chromosomal aberrations and metabolic abnormalities. A variety of inherited skin diseases can be diagnosed postnatally and prenatally (in the second trimester) by ultrastructural diagnostic markers. For evaluation of prenatal diagnosis in the first trimester, we investigated chorionic villi derived from the trophoblast layer of the early pregnancy by light microscopy and conventional electron microscopy. The ultrastructure of the cellular layers covering the villi, i.e., the inner cytotrophoblast and the outer syncytiotrophoblast, as well as that of the connective tissue of the inner extraembryonic mesoderm, are thoroughly described in relation to the ultra-structural changes in certain genodermatoses including epidermolyses and keratinization disorders. We found that chorionic villi have only a few of the characteristics differentiated in skin, and none of the structures which are relevant to the diagnosis of genodermatoses. In our view, the ultrastructural approach is not suitable for first trimester prenatal diagnosis of genodermatoses in chorionic villi.     

环境监测中油的采样技术探讨

结合实际工作经验，分析研究了环境监测中油的采样受采样体积、深度以及布点的影响。认为计算含油量时应考虑水域的总体积、采样体积、水体表面积等，这样才能较准确地估算受污水域中的含油量。     

石油类废水采样器分析

讨论了现有的石油类废水的采样器。用分液漏斗和普通玻璃漏斗组装成石油类污水采样器，用CY-2000多功能红外测油仪对模拟水样进行分析。结果表明水样中石油类平均值为11．00mg／L，显著性检验t值为1．476〈t0.05（6）=2．45，无显著性差别。说明设计的采样器更符合实际要求。     

环境空间分析中常用采样方法及其对空间结构表达的影响

采用几种采样方法在不同的采样密度下分别在两套模拟数据集上进行模拟采样，并以实验半变异函数为结构分析工具探讨了采样方案对具有不同空间分布特征数据的空间结构表达的影响。研究发现，采样密度与采样方法的选取都对空间结构的表达有显著影响。     

Evaluation of US EPA Environmental Monitoring and Assessment Program's (EMAP)-Wetlands sampling design and classification

The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) will monitor the nation's resources by evaluating the status and trends of selected indicators of condition using a probability-based sampling design. The EMAP-Wetlands program will monitor the condition of the nation's wetlands. The EMAP classification system is an aggregation of the many subclasses of the US Fish and Wildlife Service's National Wetlands Inventory (NWI) classification system. This aggregation results in fewer wetland classes with more wetlands per class than the NWI system. Aggregation of the NWI classification was based primarily on dominant vegetation cover, flooding regimes, dominant water source, and adjacency to rivers and lakes. We evaluated the EMAP classification system and sampling design using NWI digital wetlands data for portions of Illinois, Washington, North Dakota, and South Dakata. Relative numbers of wetlands, total areas, average areas, and common versus rare classes were compared between the EMAP and NWI classification systems. As expected, the EMAP classification provided fewer wetland polygons, each with larger areas, without altering total wetland area. Summary statistics comparing sample estimates to true population parameters (represented by the NWI data) demonstrated the effectiveness of the EMAP sampling design with the exception of rare EMAP classes in the selected regions. Although simple random sampling is inadequate for both large and small wetlands, the EMAP sampling design is readily adapted to provide better estimates for these categories. Aggregating the NWI classification to the EMAP classification provides fewer wetland classes, with more wetlands per class, for EMAP's annual reports and statistical summaries. The research in this report has been funded by the United States Environmental Protection Agency (EPA) under contracts 68-C8-0006 to ManTech Environmental Technology, Inc. and 68-03-3532 to The Bionetics Corporation. Mention of trade names does not constitute endorsement or recommendation for use.