安全科学基本理论规律研究

通过对事物发展过程中的安全与危险的矛盾运动过程分析,抽象出一些基本概念和事故从孕育到发生发展及结束和后效阶段的基本特征,并对部分事例进行了分析。提出了安全科学的统一规律——安全流变与突变论,并初步建立了安全流变论的数学模型     

Duchenne muscular dystrophy associated with fetal pleural effusion and polyhydramnios

A case of fetal pleural effusion in a fetus affected with Duchenne muscular dystrophy (DMD) is reported. This case is discussed in the context of the previous observation of frequent stillbirths among male fetuses in DMD families.     

Maternal cell contamination of amniotic fluid cell cultures from two consecutive pregnancies complicated by fibroids

The detection of maternal cells in amniocyte cultures is thought to be due to the outgrowth of cells from small fragments of maternal tissue removed by the amniocentesis needle. An unusual case is reported in which maternal cell contamination (MCC) was found in the cell cultures from a woman in two different amniocenteses from two consecutive pregnancies. Both pregnancies were complicated by the presence of fibroids and the fibroid tissue may have been the source of the maternal cells. A history of an amniocentesis in which there was MCC of cell cultures, or the detection of fibroids, may pose an additional risk for MCC attributable misdiagnosis in prenatal genetic studies.     

Amniotic fluid levels of human chorionic gonadotropin and its alpha and beta subunits in second-trimester chromosomally abnormal pregnancies

Amniotic fluid from 135 pregnancies was assayed for human chorionic gonadotropin (hCG) and its free alpha (ahCG) and free beta (bhCG) subunits. Forty-six chromosomally abnormal pregnancies between 14 and 20 weeks' gestation were matched with 89 chromosomally normal samples. Compared with controls, trisomy 21 pregnancies exhibited significantly elevated levels of all three peptides, whereas trisomy 18 gestations gave rise only to significant elevation of ahCG. Female fetuses in both the trisomy 21 and trisomy 18 pregnancies provided significantly elevated levels of hCG and bhCG compared to their male counterparts. On converting the values to multiples of the median, it was determined that 6 of 7 trisomy 18 samples had abnormally elevated alpha/beta ratios, as did 6 of 21 Down's syndrome pregnancies. Further, 11 of 21 trisomy 21 gestations had abnormal amniotic fluid hCG levels. Using only ahCG, bhCG and their ratio, a 61 per cent sensitivity was found for these trisomies, with a 96 per cent specificity.     

Prenatal diagnosis of metatropic dwarfism

We present a case of prenatal diagnosis of severe metatropic dysplasia at 20 weeks' gestation. The characteristic prenatal features of this rare autosomal recessive chondrodysplasia appear to be significant dwarfism with an enlarged head and a narrow thorax associated with enlargement of the hands and feet, and the radiographic ‘dumb-bell’ appearance of the long bones.     

A fetus with a chromosome 13 ring and placenta with chromosome 13 rod/ring mosaicism

A fetus was identified by prenatal cytogenetic diagnosis as having a karyotype 46,XY,r(13) (p11q13). Termination of the pregnancy yielded a severely malformed fetus. Fetal abnormalities included anencephaly, imperforate anus and urethral meatus, severe talipes, syndactyly, cardiac defects and other anomalies. Confirmatory studies on cultured placental villi cells indicated a second cell line, 46,XY, −13,+ 13qter→cen::13ql3→qter. This cell line was not detectable in cells derived from the fetus despite extensive studies. It seems likely that the two cell lines arose simultaneously with selection favouring the 46,XY,r(13) line. How the chromosome rearrangements may have arisen is discussed. We are unaware of other cases where a cell line identifiable by a chromosome abnormality appeared to be confined to placental tissue. However, studies on placental tissue may be helpful in understanding the origin of other unbalanced de novo rearrangements.     

Placental mosaicism in a case of 46,XY, −22, +t(22;22)(p11;q11) or i(22q) diagnosed at amniocentesis

46,XY, −22,+t(22;22)(p11;q11) or i(22q) was diagnosed in 15/15 cells from two cultures from the amniotic fluid culture of a 31-year-old patient whose fetus demonstrated cystic hygroma on ultrasound. Cytogenetic studies performed on fetal skin from the abortus revealed the same karyotype as that seen on amniocentesis, but the placenta demonstrated a 46,XY,46,XY, −22,+t(22;22) or i(22q) mosaicism, with 65 per cent of the cells being 46,XY. This case provides an example of placental mosaicism for a normal male karyotype, while the fetus demonstrated non-mosaic trisomy 22.