Fetal cystic hygromata: Insights gained from fetal blood sampling

Twelve second-trimester fetuses with cystic hygroma underwent fetal blood sampling for rapid karyotyping, haematologic evaluation, and blood gas analysis. An abnormal karyotype was found in seven cases: monosomy X in five, trisomy 21 in one, and trisomy 13 in the other. Eight often fetuses undergoing blood gas analysis showed hypoxaemia, five of which were growth-retarded. Nine pregnancies were terminated. Of the remaining three, only one fetus survived the perinatal period.     

Activities of alkaline phosphatase in first trimester chorion biopsy tissue

We have determined the activity of alkaline phosphatase in chorionic villous tissue obtained in the first trimester of pregnancy, in order to obtain the normal range of values as a prerequisite for application to the prenatal diagnosis of the rare bone disease hypophosphatasia. The activities found were a combination of intestinal and liver/bone/kidney types; traces of placental type were present in only one sample.     

Assessment and management of fetal agenesis of the corpus callosum

Prenatal counselling for fetal agenesis of the corpus callosum is difficult as the prognosis until now has been so uncertain. We have reviewed the current world English literature to provide the best probabilistic information for prospective parents. In total, there are 70 cases where the diagnosis was made prenatally. The diagnosis of apparently isolated agenesis of the corpus callosum (in the absence of other sonographically detectable anomalies) appears to carry an excellent prognosis, with an 85 per cent chance of a normal developmental outcome and a 15 per cent risk of handicap. Fetal karyotyping is recommended as there is a 1 in 10 risk of aneuploidy. If other anomalies are detected prenatally, the outcome is very poor. Termination of pregnancy is advised in these circumstances.     

上海市扬尘污染源遥感解译及其管理信息系统

利用遥感影像资料,分析了上海市扬尘污染源的空间分布特征与规律,并计算了上海市主要扬尘源的起尘量。利用获取的基础数据,建立了上海市扬尘污染源管理地理信息系统,为上海市扬尘污染源的控制管理提供了依据。     

A survey of diagnostic amniocenteses in Oxford from 1974–1981

A survey was conducted of the results of mid-trimester diagnostic amniocenteses in the Oxford Region from 1974 to 1981. The survey used data relating to all 4357 singleton pregnancies in which an amniocentesis was performed during this period. Follow-up information on outcome was obtained in respect of 4284 (98 per cent) pregnancies. A cell culture to determine karyotype and an alpha-fetoprotein determination was carried out in all cases. From 1974 to 1981 amniocenteses became increasingly common, rising from 2 to 32 per 1000 births. The most common indication for amniocentesis was a high risk of a chromosome abnormality–56 per cent of all amniocenteses. Within this group advanced maternal age was responsible for 89 per cent of the cases. The next most common indication was a high risk of a neural tube defect (37 per cent of all amniocenteses)–in 1974 a raised maternal serum alpha-fetoprotein level accounted for only 4 per cent of these; by 1981 this had risen to 67 per cent. There were seven false-positive and 132 true-positive diagnoses of neural tube defect; since 1981, with the introduction of amniotic fluid acetylocholinesterase determination as a secondary diagnostic test for neural tube defects, there have been no further false-positive diagnoses. In 1981 76 per cent of women aged 35 years or more did not have an amniocentesis. It is not known to what extent this was due to not offering women in this age group amniocentesis or to women not accepting such an offer.     

遥感方法应用于湖泊富营养化评价的研究

利用武汉东湖各子湖多年可靠的地面监测资料和1999年9月Landsat—7的TM各波段的卫星遥感数据,建立了各子湖的营养状态指数与TM各波段图像上灰度值之间的关系模型：一元线性模型、多元回归模型。运用这些模型对武汉各湖泊进行富营养化评价。同时基于地面监测资料,用日本学者相崎守弘提出的修正富营养化指数法对武汉主要湖泊的富营养化程度进行评价。结果显示,武汉湖泊多处于中富营养状态,遥感评价结果与地面监测结果基本一致。指出利用遥感方法进行湖泊水体富营养化监测评价是可行的、有效的、利用该方法可进行大范围的湖泊富营养化调查评价。     

航天器在轨自主热故障诊断专家系统研究

航天器在轨自主进行热故障诊断对其顺利完成任务具有非常重要的意义。文中所提出的专家系统推理机制采取基于事例和基于规则相结合的方法构造;而知识获取广泛吸取历史经验和专家知识,采用产生式规则进行知识表示。最后利用VB完成了该专家系统,通过验证,发现它具有很好的实用性。     

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.     

Transabdominal chorionic villus sampling in the second and third trimesters of pregnancy: Chromosome quality,reporting time,and feto-maternal bleeding

Transabdominal chorionic villus sampling (TA-CVS) was performed in 210 pregnancies from 13 to 38 weeks using a double-needle technique. The sampling success was comparable to first-trimester TA-CVS and the diagnostic success rate was 98.2 per cent for the short-term technique and 99.3 per cent for cultured villi. Two fetuses could not be karyotyped. We found the chromosome quality to be similar to that in the first trimester, comparing the number of G-bands and other chromosome attributes. There were no unintended losses in a group (n = 142) with no sonographic abnormality, except for one death in utero at 38 weeks, 20 weeks after sampling. Chromosomal aberrations were seen in 19 per cent of cases with abnormal sonograms (n = 58). One case of a discordant karyotype was found (false-negative prediction of Down's syndrome by the short-term preparation). There were no cases of fetal demise due to feto-maternal bleeding. It is suggested that double-needle TA-CVS in advanced pregnancies combines the advantages of rapid karyotyping of chromosomes of good quality and low risk for the fetus, and seems to be easier to practise and is probably safer than cordocentesis.     

Prenatal ultrasound diagnosis of Apert's syndrome

A mother affected with Apert's syndrome was diagnosed by ultrasound scan at 16–17 weeks to have a fetus similarly affected. The typical features of acrocephaly and symmetrical syndactyly were seen. This is probably the first time that this condition has been diagnosed at such a gestation by ultrasound scan. The patient decided to continue the pregnancy, and intrauterine death occurred at 34 weeks. The diagnosis was confirmed by pathological examination.