AP9/AE9/SPM辐射环境模型研究

对辐射环境模型AP9/AE9/SPM进行了系统研究,重点分析了AP9/AE9/SPM辐射环境模型的发展历程、建模数据、模型能力、模型使用方法、模型特点和局限性以及发展趋势。总结了AP9/AE9/SPM辐射环境模型“螺旋式上升”研发途径中所发布的11个版本的特点、数据覆盖时间范围和能量范围。指出AP9/AE9/SPM辐射环境模型在研发过程中是通过不断地将最新的观测数据和理论知识进行整合,达到扩展模型能量覆盖范围、增加空间粒子分布的目的。最新的AP9/AE9/SPM辐射环境模型具备了命令行和图形用户接口应用程序2种灵活便捷的使用方式,能覆盖完整的辐射带空间,基本实现了电子和质子能量范围的全覆盖。但目前最新版本的AP9/AE9/SPM仍然存在一些局限,这些局限会随着辐射带探测数据的积累和人类对辐射带机理的进一步认知而逐渐得到改善。该研究可帮助用户快速了解并正确使用AP9/AE9/SPM辐射环境模型,为我国自主辐射环境模型研发提供重要参考。     

Contents Volume 9

Volume Contents

Contents Volume 9     

An infant with trisomy 9 mosaicism presenting as a complete trisomy 9 by amniocentesis

We present a case in which amniocentesis performed at 33 weeks' gestation because of symmetrical intrauterine growth retardation and decreased amniotic fluid volume led to the prenatal diagnosis of a fetus with a karyotype of 47,XX,+9, t(1;20)(q42;p11.2) pat, i.e., with an extra chromosome 9 and a balanced translocation between chromosomes 1 and 20. At delivery, the baby showed clinical features of trisomy 9, yet chromosome analysis of the cord blood revealed no trisomy 9 cells, a finding confirmed by neonatal blood karyotyping. The balanced translocation was present in all cells. A skin biopsy confirmed trisomy 9 mosaicism with 10 per cent trisomy 9 cells. The baby died at 6 weeks and an autopsy was obtained. Chromosome analysis of different organs demonstrated different frequencies of the mosaicism of trisomy 9. The possible underlying mechanism for the discrepancy between the karyotype results by amniocentesis and those of other tissues is discussed.     

Prenatal detection of trisomy 9 mosaicism

Chromosomal mosaicism in amniotic fluid cells poses a serious dilemma in prenatal diagnosis since the observation may represent: (1) pseudomosaicism—an inconsequential tissue culture artefact; or (2) true mosaicism—occurring in approximately 0.0 per cent of amniocenteses with a significant impact on pregnancy outcome. Mosaicism for trisomy 9 was observed in an amniotic fluid specimen obtained for advanced maternal age with two cell lines [46,XX (46 per cent)/47,XX, + 9 (54 per cent)] present in each of four culture flasks. Since more than 75 per cent of newborns with trisomy 9 mosaicism have complex cardiac malformations, a fetal echocardiogram was obtained at 20 weeks' gestation and interpreted as normal. A fetal blood sample (22 weeks' gestation) disclosed only a single trisomy 9 cell among the 100 metaphases analysed. However, a second fetal echocardiogram performed at the time of blood sampling suggested a non-specific cardiac anomaly. Fetal autopsy following elective pregnancy termination revealed several malformations including severe micrognathia, persistence of the left superior vena cava, and skeletal anomalies. Cytogenetic studies of cell cultures derived from several fetal tissues demonstrated trisomy 9 ranging from 12 to 24 per cent.     

Complex mosaicism associated with trisomy 9

Fetal karyotypes can be routinely obtained by chorionic villus biopsy, amniocentesis, or fetal blood sampling. Interpretation of results and subsequent counselling can be complicated by pseudomosaicism or mosaicism confined to the placenta or other tissues. We illustrate this by reporting a case of an abnormal fetus with a total of three karyotypically different cell lines (46,XXrpar; 47,XX, + 9; and 47,XX, + del (9) (q11) in different tissues (placenta, lung, gonad, and skin).     

Prenatal diagnosis of mosaic trisomy 9

Mosaic trisomy 9 was detected in an amniotic fluid cell culture from a 40-year-old woman evaluated because of advanced maternal age. After counselling, parents elected to terminate the pregnancy. On autopsy the fetus was found to have hydrocephalus and a single kidney. The diagnosis of trisomy 9 mosaicism was confirmed in cultured skin fibroblasts. This is the third reported case of trisomy 9 mosaicism diagnosed prenatally.     

Prenatal diagnosis of a case of tetrasomy 9p

A male fetus with tetrasomy 9p [47,XY, + i(9p)] is presented. The cytogenetic interpretation of the marker chromosome was confirmed by assessing the activity of the enzyme galactose I-phosphate uridyl transferase. The clinical findings of the case show features in common with previously reported cases.     

Prenatal diagnosis of trisomy 9 mosaicism: Two new cases

We present two prenatal cases of trisomy 9 mosaicism, both of which presented intrauterine growth retardation (IUGR) and other abnormal ultrasound findings. In case A, mosaicism was found in amniotic fluid cell cultures, of which 65 per cent were trisomic cells, on average. In case B, trisomic cells were present in amniotic fluid cell cultures (12 per cent) but none were found in fetal cord blood. After autopsy, cytogenetic findings were confirmed in different tissue cultures. It is concluded that echographic indicators are a very useful tool for a correct prenatal diagnostic interpretation of trisomy 9. Suspected trisomy 9 mosaicism always requires further investigation and fetal cord blood cytogenetic analysis may not be considered as providing an accurate diagnosis of fetal trisomy 9.