First trimester amniocentesis between the seventh and 13th weeks: Evaluation of the earliest possible genetic diagnosis

Amniocentesis performed at the 12th week and later gives reliable results. The procedure can be performed using regimens developed for mid-trimester amniotic fluid (AF) cells. Extension to the 10th–11th week is, in principle, feasible. However, the high cytogenetic failure rate is a difficulty and despite a high clone count, the culture time is prolonged. The problem of the relatively high loss of AF could be overcome by cell filtration techniques and replacement of the fluid. Because of the short turnover rate of the AF, this may be unnecessary or replacement with an isotonic solution may be sufficient. (Pseudo)mosaicism appears to occur more frequently in early than in late amniocentesis. As yet, data are too sparse to allow a comparison with chorionic villus sampling. There are no reliable follow-up data from which to estimate the abortion rate and the number of embryonic malformations.     

废旧干电池对泥鳅的致毒作用

以抗污染能力强的泥鳅(Misgurnus anguillicadatus)为实验材料,研究了废旧干电池污染的水源对水生生物的毒害作用。结果表明,泥鳅受毒害程度与水体中废旧干电池的数量和暴露时间成正相关关系;对受毒害但未死亡的个体断尾取血,显微镜下观察血红细胞的形态、结构,发现在废旧干电池污染的水体中残存的个体,其血红细胞的变异率远远超过生活在正常水体中的个体。     

Phenotypic analysis of fetal blood leucocytes: Potential for prenatal diagnosis of immunodeficiency disorders

Recent technological advances allow the detection and quantitation of subsets of leucocytes using monoclonal antibodies. We have taken advantage of this to study the ontogeny of fetal blood leucocytes, using very small blood samples obtained at fetoscopy. By 14 weeks gestation T cells represent 35 per cent or more of fetal leucocytes and the distribution of the helper/inducer and suppressor/cytotoxic subsets is similar to that of adults. B lymphocytes before 161/2 weeks are low (4–20 per cent), but rise to a mean of 28 per cent in 17–26 week fetuses. Granulocytic cells, many of which are phenotypically immature, represent 18–34 per cent of total leucocytes. The methodology employed is very reliable and offers the opportunity for the prenatal diagnosis of some immunodeficiency disorders, since using the same reagents we have diagnosed children with severe combined immunodeficiency shortly after birth.     

平阳霉素三种成分诱发CHO-K1细胞株染色体畸变和姐妹染色单体交换的研究

本文报道平阳霉素(Pingyangmycin,PYM)的三种成分A_2、A_5和A_6诱发CHO-K1细胞染色体畸变和姐妹染色单体交换(SCEs)。处理后第一次分裂中期染色体型畸变占优势,其中有大量的染色体碎裂(Disintegration),在含染色体碎裂的细胞中三分之一伴随出现双微体(Double minutes,DMs)。细胞畸变的频率随处理浓度升高而增加。 处理后第二次分裂中期,细胞畸变的频率仍随处理试剂浓度增加而升高,SCEs频率随处理浓度升高而递增。 上述三种成分诱发染色休畸变的类型没有质的差异。     

氯化镉对不同鼠肝肿瘤细胞的毒性及对金属硫蛋白的诱导研究

本文比较了氯化镉对两种去分化和五种分化的鼠肝肿瘤细胞株的细胞毒性以及对金属硫蛋白的诱导能力。结果表明,经2μM氯化镉处理18h后,90—95％的细胞浆中镉同金属硫蛋白结合,而只有5—10％的镉同高分子量部分相连。在IIE细胞中镉与金属硫蛋白的结合取决于氯化镉的浓度与处理时间。当氯化镉浓度高达20μM时对去分化细胞的存活率未见有明显影响,但当浓度为3—10μM时则对分化细胞的存活率有显著影响。这种细胞毒性似与高分子量部分结合的镉的量有关,且氯化镉对这两种细胞的金属硫蛋白有不同的诱导能力。     

燃料电池汽车燃料储运方案经济性分析

综合案例研究结果，结合氢气、甲醇在不同储运方式时的成本，从固定设计成本、尾气排放、燃料价格、汽车造价4个方面比较了氢气、甲醇、汽油3种燃料电池汽车的经济性。结果表明：（1）直接氢燃料电池是燃料电池汽车的首选动力；（2）天然气重整制氢是目前氢燃料电池汽车获得燃料优先考虑的方式；（3）高压氢气、液氢是当前燃料电池汽车的首选燃料。     

固定化细胞单级生物脱氮动力学模型研究

以PVA为载体 ,采用冷冻 解冻法混合固定硝化菌和反硝化菌 ,在鼓泡床中研究了固定化细胞单级生物脱氮的动力学。结果表明 :在固定化细胞单级生物脱氮过程中 ,内扩散对反应的影响非常小 ,脱氮速率受化学反应控制。反应的动力学可以用Monod方程来表示 ,其动力学常数Ks 和vmax分别为 30 3 0mg L和 0 0 96mg L·s。用模型计算的脱氮速率与实测值非常接近     

Experience with 500 prenatal diagnoses of sickle cell diseases: The effect of gestational age on affected pregnancy outcome

Prenatal diagnosis of sickle cell diseases is obtained rapidly and precisely by polymerase chain reaction (PCR) with Ddel restriction analysis and dot-blotting with alllele-specific oligonucleotides (ASO). Prenatal diagnosis of HgbSS and HgbSC was performed in 500 pregnancies, 196 by Southern blot and 304 by PCR. PCR drastically shortened the interval from sampling to reporting, allowing acceptance even of samples with unknown paternal phenotype, and resulted in an overall four-fold increase in diagnoses. In 108 pregnancies, the diagnosis was an affected fetus; 25 were HgbSC: 3 (12 per cent) were terminated; 83 were HgbSS: four ended in miscarriage; 40/79 (51 per cent) were terminated. The gestational age at the time of report to the mother appeared to be a major outcome determinant when the fetal diagnosis was HgbSS. The change-point in the maternal decision was found at 20 weeks of gestation. Before the 20th week, most mothers (64 per cent) chose termination; thereafter, the majority (72 per cent) chose continuation. The odds ratio of termination in earlier relative to later reporting was 4·7. In order to offer a choice to the mothers at risk of delivering a fetus affected by sickle cell disease, the diagnosis should be reported before the 20th week of gestation.     

Nickel phosphide on Ni foam as anode and peroxymonosulfate as the chemical oxidizer for effective direct urea fuel cell

The direct urea fuel cell (DUFC) is a low cost and competitive approach for contemporaneous urine or urea-contaminated wastewater treatment and electricity generation. However, the lack of efficient urea oxidation reaction (UOR) electrocatalysts and suitable electron acceptors remains a challenge for practical applications. Here, we developed a DUFC system using Ni₂[email protected] foam as the anode and peroxymonosulfate (PMS) as the chemical oxidizers. The Ni₂[email protected] foam anode showed a high oxidation activity for UOR with an onset potential of 0.30 V vs. Ag/AgCl and Tafel slope of 34.4 mV/dec. PMS with high theoretical potential improved the cell voltage to 1.43 V. A power density of DUFC up to 4.91 mW/cm² was achieved using PMS at room temperature, which was approximately twice as high as using H₂O₂ (2.38 mW/cm²). Ni^II/Ni^III was the redox active species on the Ni₂P anode in the DUFC process, and Ni^II was electrochemically oxidized to Ni^III, which reverted to Ni^II by urea reduction. When real human urine was used as the fuel, a power density of 4.46 mW/cm² can be achieved at room temperature. This DUFC with high cell performance showed potential application in urea wastewater treatment.