Chromosomal prenatal diagnosis: Study of 936 cases of intrauterine abnormalities after ultrasound assessment

Nine hundred and thirty-six prenatal chromosomal analyses were performed by four cytogenetic centres after ultrasound diagnosis of fetal abnormalities, amniotic fluid disorders, fetal growth retardation, and fetal or placental abnormalities. During the same period, 6515 fetal karyotypes were analysed because of maternal age. Frequencies of chromosomal aberrations in each case were respectively 4·4, 6·7 and 15·8 per cent, compared with 3·18 per cent when the fetal karyotype was performed because of maternal age. High rates of chromosomal aberrations are observed in cases of cervical hygroma, limb abnormalities, omphaloceles, duodenal stenosis, hydrocephalus, and facial abnormalities. In the case of polymalformations, this rate was 29·2 per cent. When malformations were seen together with an amniotic fluid disorder or growth retardation, 21·5 per cent chromosomal aberrations were observed. This frequency was 10·4 per cent when growth retardation was associated with an amniotic fluid disorder. Trisomy 13, 18, 21 and monosomy X accounted for 4/5 of all abnormalities in which we observed a high rate of triploidies (4·9 per cent) and balanced (3·3 per cent) or unbalanced (9·8 per cent) non-Robertsonian structural abnormalities. Sonographic ascertainment of these aberrations and prenatal characteristics of major anomalies are discussed.     

染色体步行PCR技术

染色体步行是一种常用的克隆已知基因旁侧序列的技术.本文综述了现有的染色体步行PCR技术,如反向PCR、锅柄PCR、连接介导PCR、热不对称PCR、SON PCR等,并在此基础上提出了一种新的染色体步行PCR技术的构思.它运用特异引物与随机引物的搭配,在普通PCR程序下扩增目的序列.实验中设置相应随机引物的RAPD对照,识别非目的扩增产物.文中介绍了新方法的原理,分析了这种方法的优缺点.这种方法可能是一种新的有效进行染色体步行的PCR技术,国内外尚未见相关报道.图2参26     

好氧颗粒污泥处理高浓度氨氮废水的研究

在不同接种源污泥颗粒化过程中污泥理化性状对比研究的基础上,采用成熟好氧颗粒污泥处理高浓度氨氮废水,对其脱氮行为以及不同C/N条件下好氧颗粒污泥微生物的比耗氧速率、好氧颗粒污泥对氨氮的比降解速率随时间的变化等进行了研究.实验结果表明,在进水氨氮质量浓度较高(480 mg/L)、温度30℃左右的条件下,稳定运行15 d,氨氮的去除率维持在85%左右;进水氨氮的浓度越高,随着微生物对环境的逐渐适应,硝化菌的活性也逐步增加;随着进水氨氮浓度的提高,好氧颗粒污泥对氨氮的比降解速率也逐渐上升.     

Experimental verification for real-time environmental emergency response system: WSPEEDI by European tracer experiment

Japan Atomic Energy Research Institute has developed an emergency response system WSPEEDI to forecast long-range atmospheric dispersions of radionuclides discharged into the atmosphere. The latest version of WSPEEDI consists of an atmospheric dynamic model MM5 for calculating meteorological fields and a particle random-walk model for atmospheric dispersion. The performance of WSPEEDI was evaluated by data obtained from a field tracer experiment over Europe (ETEX) in this paper. The model validation was done with respect to the following points: (1) the dependence of model accuracy on the temporal and spatial resolutions of the meteorological fields and (2) the superiority of an atmospheric dynamic model over a mass-consistent wind model. Regarding (1), it was shown that the calculation accuracy of the new version with high temporal resolution was improved, especially at the edge of the plume. Moreover, although the increase in horizontal spatial resolution of the old version had no substantial effect on the model performance, increase in horizontal resolution of the new version contributed to the significant improvement of the calculation accuracy. These results showed that the dynamically calculated meteorological field with the spatial resolution of the meso-β–γ scale greatly improved calculation accuracy.     

Artificial indoor streams as a method to investigate the impact of chemicals on lotic communities

The potential hazard of chemicals on aquatic communities are generally evaluated by standardised single-species bioassays. Safety assessment is based on results gained from organisms adapted to lentic systems and biological interactions in ecosystems are neglected. While lotic communities are often at first in contact with chemicals, it is astonishing that microcosms with lentic communities are mainly used as a bridge between laboratory bioassays and outdoor aquatic systems. Hence, we established five artificial indoor streams to simulate abiotic factors of small rivers. The closed-circuit system was filled with nutrients added to tap water. Washed pebbles were used as sediment. The dynamics of a simple biocoenoses consisting of aufwuchs, Lumbriculus variegatus Asellus aquaticus and Gammarus fossarum was investigated. The dynamic of aufwuchs and periphyton was determined as dry weight and chlorophyll-a, respectively and qualitatively by pigment pattern. The abundance of different developmental stages of L. variegatus was determined at the end of the experiment as well as the population dynamics of G. fossarum and A. aquaticus. Survival rates of gammarids and juveniles per female were investigated and data were used for modelling the population dynamics. The experiment was carried out to investigate the performance of the established artificial streams and the developed approaches to investigate effects of chemicals on a basic lotic community. The prime reason to establish this approach was to close a gap between complex artificial stream systems and laboratory single species tests to assess the impact of chemicals on the aquatic environment.     

电离辐射对人类染色体的影响

通过对２６例静电加速器工作者染色体的观测，研究电离辐射引起的人类染色体畸变。效应与辐射剂量相关，畸变的类型和频率反映细胞损伤程度。     

Prenatal diagnosis of the derivative chromosome 22 associated with cat eye syndrome by fluorescence in situ hybridization

Cytogenetic studies of cultured amniocytes demonstrated a karyotype of 46, XX/47, XX,+mar. A bisatellited, dicentric, distamycin-DAPI negative, NOR-positive marker was present in 76 per cent of the metaphases examined. Similar markers have been associated with cat eye syndrome (CES). We report on the utilization of fluorescence in situ hybridization (FISH) with a 14/22 a-satellite probe and a chromosome 22-specific cosmid for locus D22S9 to determine the origin of the prenatally detected supernumerary marker chromosome. FISH studies demonstrated that the marker is a derivative of chromosome 22 and enabled us to provide the family with additional prognostic information.     

Diagnosis of Bloom's syndrome by sister chromatid exchange evaluation in chorionic villus cultures

Cultures of a chorion biopsy taken from a pregnancy at risk of Bloom's syndrome revealed the high sister chromatid exchange frequency diagnostic of this rare disorder. To obtain the result, cultures were grown under standard conditions, with the addition of 10μM 5′;-bromodeoxyuridine for the final 48 h of incubation. This result demonstrates the feasibility of early prenatal diagnosis of Bloom's syndrome.     

Early amniocentesis: Experience of 222 consecutive patients, 1987–1988

Early amniocentesis from 9 to 14 weeks' gestation provides a safe and accurate method of prenatal diagnosis of cytogenetic and biochemical disorders. There was a 100 per cent success rate in culturing the amniotic cells from 222 samples obtained between 9 and 14 weeks' gestation. Follow-up of the patients to delivery revealed an abortion rate of 1·4 per cent. Among the 207 live- and stillborn infants, only one had a congenital abnormality (bilateral talipes equino-varus) and no infant had respiratory distress syndrome or pneumonia. Eleven pregnancies were terminated following the detection of a chromosomal, biochemical, or congenital abnormality (5·0 per cent). However, before the procedure of early amniocentesis becomes routine clinical practice, it requires appraisal by a randomized clinical trial.     

Cytogenetic analysis of 1375 amniotic fluid specimens from pregnancies with gestational age less than 14 weeks

Our laboratory has received 1375 early amniotic fluid (EA) specimens during the past 5-year period for cytogenetics analysis. The gestational ages of the EA specimens were less than 14 weeks as estimated by ultrasound. The average volume of specimen received was 16 ml. Specimens were typically received in two collection tubes and cultured in Chang A and in supplemented MEM media using the in situ technique. Of the 1375 EA specimens received, 1356 were successfully cultured and yielded results. Abnormal results were found in 67 (4.9 per cent) of the cases. Nineteen specimens (1.4 per cent) failed to yield a result. The mean turn-around time (TAT) for all EA specimens was 8.28 days. In 1991, the average TAT for the EA specimens was 8.00 days compared with a TAT of 6.59 days for all specimens received over 14 weeks gestational age. The number of EA specimens received has increased from 1.5 per month in 1986 to 57 per month in 1991. In summary, our experience with EA specimens for cytogenetic analysis has demonstrated that the success rate is 98.6 per cent and that an increasing number of obstetricians are performing early amniocentesis as they seek to provide their patients with earlier results and an alternative to chorionic villus sampling.