发光细菌对化合物的致突效应与检测研究

从明亮发光杆菌Ｔ３小种分离到的自发暗变种（Ｋ变种）Ｔ９１７１菌种对三种化合物呈致空变阳性反应，对二种化合物呈可疑阳性，发光细菌暗变种对遗传毒性化合物致突效应的灵敏度高于Ａｍｅｓ试验和浦乳动物致癌试验，可望成为一种简易灵敏的测试环境致突变物的短期生物学试验方法。     

Serum PAPP-A levels are depressed in women with fetal Down syndrome in early pregnancy

The value of maternal serum pregnancy-associated plasma protein (PAPP)-A in screening for Down syndrome in early pregnancy was assessed using stored samples. Seventeen cases of Down syndrome and 66 unaffected control pregnancies were studied. The median PAPP-A level in the cases was 0.42 multiples of the expected value in controls (p <0.0001). Eleven cases (65 per cent) had levels less than half the expected value compared with only six controls (9 per cent). A commercial assay kit is now needed so that prospective screening with this marker can begin.     

Expanding multiple marker screening for Down's syndrome to include Edward'S syndrome

Information on maternal age and maternal serum alpha-fetoprotein, unconjugated oestriol (uE₃), and human chorionic gonadotrophin (hCG) levels was used to investigate retrospectively the effect of estimating Edward's syndrome risk in women having multi-marker screening for Down's syndrome. The screened population comprised 15 pregnancies affected by Edward's syndrome, 15 with Down's syndrome and 5472 unaffected pregnancies. The use of all three markers to estimate Edward's syndrome risk would have led to the detection of 10–12 (67–80 per cent) cases with a false-positive rate of 0.3–0.6 per cent depending on the risk cut-off. A further case would have been detected as a result of screening for Down's syndrome alone. Similar results were obtained when the Edward's syndrome risk was based on uE₃ and hCG only. These data suggest that extending Down's syndrome screening to include Edward's syndrome risk will yield a high detection rate with only a small increase in the false-positive rate.     

Dystrophin protein and rflp analyis for fetal diagnosis and carrier confirmation of duchenne muscular dystrophy

A pregnant woman with indeterminate Duchenne muscular dystrophy (DMD) carrier status, but with DMD diagnosed in her deceased brother (unavailable for study), presented for prenatal diagnosis, intending to continue the pregnancy only if proven unaffected with DMD with near absolute certainty. Creatine kinase (CK) assays to clarify carrier status were inconclusive. Male sex in the fetus was identified, but DNA restriction fragment length polymorphism (RFLP) analysis was not yet available to this centre to investigate the possible transmission of the DMD gene, and the pregnancy was terminated. Tissue histology and dystrophin protein analysis demonstrated the absence of DMD. In a situation with proven maternal carrier status, future fetal inheritance of the opposite maternal X chromosome would indicate the presence of DMD. However, maternal carrier status remained in doubt through a second pregnancy, even with RFLP studies, and was finally established when dystrophin analysis confirmed the presence of DMD in the second fetus. Histologic findings are presented, contrasting features in the two fetuses. The value of dystrophin analysis for establishing the diagnosis of fetal DMD, in this case proving maternal carrier status in a difficult situation, and for demonstrating DMD gene:RFLP haplotype relationships is illustrated.     

Service transformation—managing a shift from business travel to virtual meetings

It has been shown that the potential for environmental, and financial improvements through the increased substitution of in-person meetings by virtual communication is considerable. However, it has also been shown that this potential is not automatically realized by investing in the technology that can enable virtual meetings. This paper describes two case studies that explored the factors that influenced communication and meeting behavior. A number of drivers and barriers for virtual meetings are identified, and, in addition, measures are proposed to improve the utilization of virtual tools for business communication.     

紫木凼金矿开采过程中的环境效应:2.污染趋势分析

主要对紫木凼金矿区CN- 、As、Hg、Pb、Zn五个污染项目进行了趋势分析和污染预测。氰化物虽然是剧毒污染物 ,但它具有很强的自净降解作用 ,对矿区的污染影响不大 ,只是对于废液池的清洗外排必须先治理后排放。建立了As、Hg、Pb、Zn在各个污染途径中的定量分配模式。该模式表明 ,开采过程中As、Hg、Pb的大部分 ( 64 %以上 )进入废液池外排 ,其余的进入矿渣。在此基础上 ,对这些元素从 1 989年到 2 0 0 0年的开采总量、进入废液、土壤、积水坑的分量进行了计算 ,并给出了在堆场下伏粘土中各元素的饱和吸附量和开始外排的时间。     

论深入广泛推行清洁生产

在全面分析了国内推行清洁生产现状的基础上，根据中国的工业和资源特点，阐述了推行清洁生产的必要必,现时，从技术和管理两方面指出了中国推行清洁生产的巨大潜力，最后，有针对性地提出了深入广泛推行清洁生产的4条措施：（1）加快完善清洁生产政策，（2）深入实施清洁生产审计，（3）加强清洁生产技术的理论研究，（4）积极在中小企业中广泛推广清洁生产。     

电活性铝凝剂EAF对炼油废水的絮凝作用

采用电化学方法制取电活性铝凝剂ＥＡＦ．对照测定了３种传统的含铝絮凝剂和ＥＡＦ对模拟和实际含油废水的絮凝净化作用．结果表明，６０℃温度下，ｐＨ＝６～７，ＥＡＦ的用量为１０～３０ｍｇ／Ｌ时，油与ＣＯＤｃｒ去除率分别在９０％和８０％以上．简单讨论了ＥＡＦ的絮凝作用机理．     

Hepatic calcifications in a fetus with trisomy 9 that underwent cordocentesis

Foci of calcification were observed at autopsy in the liver of a fetus with complete trisomy 9 on which two cordocenteses had been performed. It is suggested that liver calcifications are a possible complication of the procedure. As several other cases of calcifications in the liver and other organs of fetuses with autosomal trisomies have been described without a history of cordocentesis, further studies should be carried out to determine whether fetuses with chromosomal anomalies are more prone to thrombus formation and embolization.     

Serum PAPP-A measurements in first-trimester screening for Down syndrome

Serum PAPP-A measurements taken from 254 women in the first trimester are reported. Eleven chromosomal abnormalities were detected. The mean serum PAPP-A levels in cases of Down syndrome were 0.44 MOM at 9 weeks gestation, 0.15 MOM at 10 weeks, and 0.29 MOM at 11 weeks. The PAPP-A level at 10 weeks was below those of pregnancies which aborted spontaneously. At 11 weeks, the pregnancies with Down syndrome recorded the lowest PAPP-A levels at that gestation. On this small sample, offering chorionic villus sampling to women with singleton pregnancies and a PAPP-A level below 0.3 MOM (approximately 6.5 per cent of this at-risk group) would have detected all the Down syndrome fetuses at 10 weeks and 50 per cent at 11 weeks without selecting those cases destined to abort. This suggests that serum PAPP-A should continue to be investigated as a potential first-trimester screening test for Down syndrome.