不同粒径大气颗粒物几种重金属成分分析及其致突变性研究

采集冬季太原市一采样点不同粒径大气颗粒物,经分析,总悬浮颗粒物日均浓度为1.04mg/m~3,严重超标。其中粒径小于7.0μm的占49.6％,小于3.3μm的占33.5％。颗粒物无机提取液中5种金属元素的浓度由高到低依次为Pb、Mn、Cr、Ni和Cd。每一种元素均呈随颗粒物粒径减小浓度增高的趋势。以SOS显色法和小鼠体内骨髓细胞染色体畸变试验检测颗粒物的无机提取液和模拟肺泡液溶出液的遗传毒性,表明小粒径颗粒物遗传毒性较强;小于1.1μm的颗粒物,仅用相当于5m~3或10m~3空气量的样品液,即可诱发SOS反应或致染色体损伤。     

A study of chromosomal aberrations in amniotic fluid cell cultures

This paper represents the analysis of 1916 routine amniotic fluid specimens harvested by an in situ fixation technique in a prospective study with regard to cultural chromosome anomalies. Excluding constitutional abnormalities, 2·9 per cent of 19432 cells analysed showed some form of chromosome anomaly, terminal deletions (57 percent) and chromatid/chromosome breaks and gaps (18 per cent) being the most frequent, followed by interchange aberrations (13 per cent) and trisomy (5 per cent). No case was found of more than one colony from the same culture showing the same anomaly without it being present in other cultures from the same fluid. The wholly abnormal colonies had a surplus of trisomies and from the mathematical considerations presented one may infer that these are likely to reflect the presence of abnormal cells in the amniotic fluid. Partly abnormal colonies appeared at a frequency that would correspond to virtual absence of selection against chromosomally abnormal cells when cultured in vitro. The aberrations found were similar to those seen as single cell anomalies, except for chromatid breaks and exchanges. The data suggest a basic preferential induction of trisomy for chromosomes 2,18,21, and the Y-chromosome. Structural aberrations showed a marked clustering of breakpoints around the centromeres. The frequency of mutant cells was low (1·4 × 10⁻³) before culture was initiated. At harvest, the frequency of abnormal cells was much higher (3 × 10⁻²) corresponding to 3 × 10⁻³ mutations per cell per generation accumulating over approximately ten generations in vitro.     

Effects of Zn~（2＋） on root growth，cell division，and nucleoli of Allium cepa L．

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Extra embryonic/fetal karyotypic discordance during diagnostic chorionic villus sampling

From a total of 1312 diagnostic chorionic villus samplings (CVS) there were 22 which showed discordance between the karyotype of the chorionic villi and that of the fetus. This frequency was some 20-fold higher than that reported at amniocentesis. In the majority of discordant cases, the fetal karyotype was normal while the placenta! karyotype was mosaic. In four cases, the placenta! karyotype was non-mosaic (a trisomy 16, a monosomy X, and two tetraploids) while the fetal karyotype was normal. In one case, the placenta was trisomy 18 while the fetus was mosaic. There were two ‘false-negative’ results where short-term methods showed only normal cells while both long-term cultures of chorionic villi and fetal cells were mosaic, in one 46,XY/47.XXY and in the other 46,X Y/47.X Y, + 21.     

Variation in prenatal cytogenetic diagnosis: Policies in 13 european countries, 1989–1991

The livebirth prevalence of autosomal chromosomal anomalies is determined by several factors, including maternal age distribution and the impact of prenatal cytogenetic diagnosis (PCD). The impact of PCD varies between countries, as the indications and the uptake vary. In a previous study we described differences in Down syndrome prevalence and the proportion of older mothers. We have now made a survey of the official PCD policies in 25 regions in 13 European countries for the period 1989–1991. In two countries, termination of pregnancy was not available. In the other 11 countries, international agreement existed on five indications: advanced maternal age, a previous child with a chromosomal anomaly, parents who are carriers of a balanced translocation, mothers who are carriers of an X-linked disorder, and malformations at ultrasound. The exact limit for advanced maternal age varied from 35 to 38 years. There was a considerable variation for the indications advanced paternal age, amniocentesis for AFP or DNA, parental anxiety, a previous child with a congenital anomaly, abnormal maternal serum markers, and exposure to radiation/chemotherapy. The PCD uptake for mothers above the maternal age limit varied from 10 to 88 per cent. International harmonization of the indications for PCD is not considered feasible at present, because of the rapid changes in PCD policies even within countries.     

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.     

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。     

Chromosomal mosaicism confined to chorionic tissue

Chorionic villus samples from two healthy pregnant females were obtained for first trimester fetal diagnosis. The karyotypes were 46, XX/47, XX, +3 and 46, XX/47, XX, +15, respectively. In both cases fibroblast cultures after termination of pregnancy were shown to have normal karyotypes.     

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.