Identification of a case of maternal uniparental disomy of chromosome 10 associated with confined placental mosaicism

We report a case of maternal uniparental disomy of chromosome 10 discovered after chorionic villus sampling (CVS). Direct preparations revealed mosaic trisomy 10, while cultured CVS cells, as well as amniotic fluid cells, showed only a normal 46,XY complement. DNA analysis using microsatellite markers showed both chromosomes 10 to have been inherited from the mother. The pregnancy was complicated by polyhydramnios. A phenotypically normal male infant of appropriate size was delivered by Caesarean section at 41 weeks' gestation. Since only the direct preparations showed trisomy 10, this case illustrates the importance of CVS direct preparations in the detection of pregnancies at risk of uniparental disomy (UPD). Although the increased frequency of confined placental mosaicism (CPM) diagnosed when direct preparations are performed has been viewed negatively, identification of both CPM and UPD may have biological and clinical significance for a pregnancy. Even though only a single case of maternal disomy 10 is reported here, the apparently normal phenotype provides evidence that there are no major imprinted loci on chromosome 10 that affect in utero growth and development. However, other potential effects such as mental retardation will require long-term follow-up of this as well as additional cases.     

Cardiac defects in chromosomally abnormal human embryos of 10–14 weeks' gestation

Cardiac defects were studied in five chromosomally abnormal embryos of 10–14 weeks' gestation by free-hand microdissection of hearts measuring 2·5–6 mm in diameter. The type of cardiac malformation alone or in association with other anomalies helped to confirm the chromosome diagnosis established prenatally by chorionic villus sampling or after spontaneous abortion. It was suggestive of a chromosomal disorder in one case in which cytogenetic investigation had failed.     

生物炭的13C标记方法及对镉、铜的吸附性能探究

生物炭施入土壤后很难分离和检测，因而难以直观研究生物炭在土壤中的环境行为.本文采用稳定同位素标记法制备¹³C标记的生物炭，研究了¹³C标记生物炭的制备方法，以及标记前后生物炭的基本理化性质及其对Cd²⁺和Cu²⁺的吸附效果和吸附机理.结果表明，脉冲标记法可有效提高玉米植株的δ¹³C值，经过550℃限氧热解法制备的¹³C玉米秸秆生物炭（¹³C BC）的δ¹³C值为249.3‰，显著高于土壤（-23.5‰）及未标记的玉米秸秆生物炭（-25.7‰），具有显著的生物炭示踪效果.¹³C标记的生物炭的pH、CEC、比表面积、表面官能团种类及数量等理化性质与未标记生物炭相似，说明脉冲标记法制备的¹³C标记生物炭不改变生物炭的基本理化性质.吸附动力学和吸附热力学实验结果表明，¹³C标记生物炭与未标记生物炭对Cu²⁺、Cd²⁺的吸附均符合准二级动力学方程和Langmuir等温吸附方程，且吸附平衡时间、最大吸附量基本相同，表明¹³C标记生物炭不改变生物炭对Cd²⁺、Cu²⁺的吸附效果和吸附特征.XRD、FT-IR结果表明，¹³C标记生物炭和未标记生物炭具有相同的吸附机理，均为离子交换作用、静电吸附作用和阳离子-π键作用.因此，脉冲标记法制备的¹³C标记生物炭具有与生物炭相同的基本理化性质和对镉、铜的吸附行为，同时具有显著高于土壤背景的δ¹³C值，可为土壤中生物炭迁移、生物炭与重金属相互作用行为的研究提供一条途径.     

Ultrasound screening for chromosomal anomalies in the first trimester of pregnancy

For the last 6 years, sonographic signs for excessive fluid accumulation in the backs of 10- to 12-week-old fetuses have been looked for prior to transabdominal chorionic biopsy. In 1400 pregnancies, subsequent karyotype analyses revealed 28 cases of Down syndrome. In 15 ( = 54 per cent), a large fluid cushion over most of the back had been documented at the time of biopsy. Only a few chromosomally normal fetuses with the same peculiarity were observed. The cushion was also present in fetuses with trisomies 18 and 13 , and in Turner syndrome. Systematic first-trimester screening for nuchal fluid accumulation seems to be a recommended method for the detection of Down syndrome and other chromosome anomalies in young pregnant women at low risk. It compares favourably with current methods of maternal serum screening performed at 16–18 weeks which require a higher number of invasive procedures.     

Maternal urinary β-core fragment of hCG/creatinine ratios and fetal chromosomal abnormalities in the second trimester of pregnancy

Our aim was to evaluate the potential value of the ratio of the maternal urinary beta-core fragment of human chorionic gonadotropin (βC-hCG) to creatinine (Cr) in discriminating between normal pregnancies and pregnancies associated with fetal chromosomal abnormalities. We hypothesized that pregnancies with fetal chromosomal abnormalities had abnormal quantities of βC-hCG in the urine. The aims of the present study were to investigate retrospectively whether maternal urinary ratios of βC-hCG/Cr are abnormal in women carrying fetuses with chromosome aberrations and to determine normative median values and a reference range for βC-hCG/Cr between 14 and 19 weeks' gestation. Maternal urinary βC-hCG and Cr concentrations were measured in 150 healthy women from 14 to 19 weeks and compared with ten cases of fetal chromosomal abnormalities matched for gestational age. The preliminary cut-off points corresponded to 0·29 multiple of the normal median (MOM) and 2·83 MOM, which were equivalent to the tenth and 90th centiles of the normal range. Of ten cases of fetal chromosomal abnormalities, one out of one (100 per cent) case with trisomy 18 and three of four (75 per cent) cases of variant 9 chromosome had low βC-hCG/Cr (≤0·29 MOM). One of five (20 per cent) cases with Down syndrome had elevated βC-hCG/Cr (≤2·83 MOM). Urinary βC-hCG/Cr ratios obtained in the second trimester may be useful for improved detection efficiency of Down syndrome, trisomy 18, and inversion of chromosome 9. Second-trimester maternal urinary βC-hCG/Cr should be investigated further as a potential marker for fetal chromosome anomalies.     

聚合氯化铝中纳米Al13形态的混凝效应

采用聚丙烯酰胺凝胶柱层析法分离纯化聚合氯化铝(PAC)中的Al13形态,用透光率脉动检测技术并结合絮凝效能和Zeta电位测定结果,对纳米Al13形态以及PAC、AlCl3絮凝过程中絮集物形成和增长的变化差异作了对比性研究.结果表明,混凝剂的不同铝形态分布在混凝过程中起着十分重要的作用.Al13形态是在絮凝过程中起电中和作用的主要形态,可以大大增加颗粒间的有效碰撞率,其凝聚速度和所形成絮集物颗粒大小在实验条件下呈现最大值.而对于PAC,其Alc含量较高,可起到吸附架桥和网捕卷扫作用,所以在低投加量表现出较快的絮体增长速率.     

Prenatal diagnosis of trisomy 8 mosaicism in cvs after abnormal ultrasound findings at 12 weeks

We describe a case of trisomy 8 mosaicism in which fetal chromosome analysis was prompted by ultrasound abnormalities, i.e., hygroma colli and dilatation of the renal pelves. Chorionic villus sampling (CVS) was performed, with a false-negative result on direct karyotype analysis, although cultured trophoblasts revealed trisomy 8 mosaicism. Fetal autopsy confirmed the abnormalities found on ultrasound examinations and fetal tissue examination showed different levels of trisomy 8 mosaicism. To our knowledge, this is the first prenatal diagnosis of trisomy 8 made on ultrasound findings.     

Risk-based prenatal screening for trisomy 18 using alpha-fetoprotein,unconjugated oestriol and human chorionic gonadotropin

Nine centres collaborated to examine the feasibility of a screening method for trisomy 18 that was based on assigning individual risk, using a combination of maternal age and measurements of alpha-fetoprotein (AFP), unconjugated oestriol (uE3), and human chorionic gonadotropin (hCG). Second-trimester measurements of these analytes were obtained from 94 trisomy 18 pregnancies. In the 89 pregnancies without an associated open defect, the median levels for AFP, uE3, and hCG were 0.65, 0.43 and 0.36 multiples of the unaffected population median, respectively. The strongest individual predictor of risk for trisomy 18 was uE3, followed by hCG, AFP, and maternal age, in that order. Using a method of individual risk estimation that is based on the three markers and maternal age, 60 per cent of pregnancies associated with trisomy 18 would be detected at a risk cut-off level of 1:100, with a false-positive rate of about 0.2 per cent. One in nine pregnancies identified as being at increased risk for trisomy 18 would be expected to have an affected pregnancy. This risk-based screening method is more efficient than an existing method that is based on fixed analyte cut-off levels. Even though the birth prevalence of trisomy 18 is low, prenatal screening can be justified when performed in conjunction with Down syndrome screening and when a high proportion of women offered amniocentesis have an affected fetus.