Genetic amniocentesis in biamniotic twin pregnancies by a single transabdominal insertion of the needle

We present a technique to aspirate amniotic fluid from both sacs in biamniotic twin pregnancies using a single abdominal insertion with a spinal needle. It was successful in 48 out of 55 cases of biamniotic twin pregnancies referred to our perinatal unit between 1985 and 1994. The single insertion technique was used when the inter-amniotic membrane was clearly evident and two separate free amniotic fluid pools could be reached by the operator with a single puncture. An adequate amount of amniotic fluid was sampled from both sacs to make a cytogenetic diagnosis in all cases. There were four fetuses with trisomy 21 in three twin pregnancies. In two cases, only one twin was affected whilst the co-twin was normal, so that a selective feticide was performed. No miscarriages due to genetic amniocentesis were reported. After 1990, all genetic amniocenteses in biamniotic twin pregnancies (except for one case due to late booking) were performed between 14 and 15 weeks of gestation and with all cases except one, it was possible to sample both twins by a single puncture. We suggest that early amniocentesis (14–15 weeks) by a single abdominal puncture could be a reliable and safe alternative to first-trimester chorionic villus sampling in twin pregnancies.     

An accessory marker derived from chromosome 20 and its co-existence with a mosaic trisomy 20 cell line

We report a 16-month-old boy with delayed psychomotor development, dysmorphic features, and failure to thrive. He had a mosaic karyotype detected prenatally: mos 46,XY/47,XY,+r(20)/47,XY,+20. After birth, the abnormal cell lines were confirmed in a number of tissues. The small ring chromosome was identified using fluorescence in situ hybridization as derived from chromosome 20. We compared our patient with previously reported cases of mosaic trisomy 20 detected prenatally and associated with an abnormal phenotype. In an attempt to characterize an r(20) syndrome, we also compared our case with two similar reports in the literature.     

Thyroid antibodies are not a risk factor for pregnancies with down syndrome

The observation that thyroid disease is frequent in mothers of children with Down syndrome (DS) has suggested that maternal thyroid antibodies could be a factor predisposing to trisomy 21 in their offspring. In this study, the incidences of thyroglobulin (Tg) and thyroid peroxidase (TPO) antibodies were analysed with a sensitive solid-phase immunosorbent radioassay in sera from 29 mothers giving birth to children with trisomy 21 and 87 control mothers. The serum samples were collected at delivery. There was no statistical difference regarding the proportion of thyroid antibodies (against Tg and/or TPO) in the two groups. Thyroid antibodies were detected in 6/29 (20.7 per cent) of the DS mothers and in 23/87 (26.4 per cent) of the control mothers. Among the women with thyroid antibodies, 4/6 (66.7 per cent) of the DS mothers and 12/23 (52 per cent) of the control mothers had antibodies against both Tg and TPO. There was no increase in the relative risk of having a child with DS if the titre of either Tg or TPO antibodies or both were positive, i.e. ≥ 1/5. The results indicate that the presence of thyroid antibodies in the serum of a pregnant woman has no prognostic value for the birth of an infant with DS.     

“华夏古陆”考异

自葛利普创名“华夏古陆”以来,经过半个多世纪的论辩与考订,对其地质构造属性,至今仍然否定与肯定交迭起伏,莫衷一是,本文从推覆构造,陆地漂移等实际资料着手,加以论证,认为它是经历深刻改造和发生巨大位移的变质岩断片体,地质构造属性已非“华夏古陆”原义。     

Release of bioactive active iodine in kelp

The release process and influencing factors of bioactive iodine of kelp are systemically studied by leaching experiment. The results showed that the bioactive iodine of kelp can be released rapidly and the principal form of iodine in lixivium is I^- . There is a dynamic process between the release and absorption of iodine. With the increase of leaching water, the gross amounts of released iodine rise.There also exists a transforming process among I^- , IO3^- and organic iodine in lixivium.     

Distribution characteristics of ammonia-oxidizing bacteria in the Typha latifolia constructed wetlands using fluorescent in situ hybridization(FISH)

A molecular biology method, fluorescent in situ hybridization（FISH）, in which the pre-treatment was improved in allusion to the media of the constructed wetlands（CW）, e.g. the soil and the grit, was used to investigate the vertical distribution characteristics of ammonia-oxidizing bacteria（AOB） quantity and the relation with oxidation-reduction potential（ORP） in the Typha latifolia constructed wetlands under three different Ioadings in summer from May to September. Results showed that the quantity of the AOB decreased in the Typha latifolia CW with the increase of vertical depth. However, the AOB quantity was 2-4 times the quantity of the control in the root area. Additionally, ORP in the rhizosphere was found to be higher than other areas, which showed that Typha latifolia CW was in an aerobic state in summer when using simulated non-point sewage at the rural area of Taihu Lake in China and small town combined sewage.     

电极旋转放电条件下O3合成效率的理论研究

根据低温等离子体理论和电磁场理论，在实验的基础上研究了电极旋转条件下低温等离子体的产生机制和臭氧的合成机制，分析了放电过程中二次放电重叠对臭氧合成的影响，建立了旋转放电与二次放电的理论模型，并根据这一理论模型导出电极旋转条件下的臭氧合成效率与二次放电重叠概率以及电极旋转速度间的理论关系．这一理论结果表明：二次放电重叠使得臭氧合成效率降低，而电极以适当地速度旋转则可以有效地避免二次放电的重叠，从而提高臭氧的合成效率．理论值和实验结果能够较好地吻合．     

沸腾炉底灰的特性研究

用化学分析、Ｘ射线能谱、扫描电子显微镜、偏光显微、激光粒度分析仪等仪器地沸腾炉燃烧所产生的底灰的化学成分、颗粒形貌、粒度、物理性质和工艺性质等系统的分析，并一全国电厂煤粉炉产煤灰的特性进行了对比，结果表明，沸腾炉产底灰具有形态不规则、矿物相中无莫来石矿物、未燃烬炭量低、细底低、比表面积小、火山炭活性高等特点，为沸腾炉底灰的加工利用提供了重要的科学依据。