Prenatal diagnosis of familial ring 21 chromosome

Ring chromosome 21 is a rare chromosome anomaly often associated with mental retardation and dysmorphic features. Less commonly, the ring chromosome can be familial and associated with a normal phenotype. Phenotypically normal female carriers, however, are at increased risk of having children with Down syndrome, mosaic monosomy 21, and variable duplication or deletion of chromosome 21. Because of the relative mitotic and meiotic instability of ring chromosomes, abnormal cytogenetic findings encountered during prenatal diagnosis may not reflect the true genetic status of the fetus. This is a report of a phenotypically normal female carrier of a familial ring 21 chromosome. Prenatal diagnosis on her twin pregnancy revealed a mosaic 46,XX,r(21)(p13;q22) (77 per cent)/45,XX, – 21 in one fetus and a normal male karyotype in the second. The pregnancy was carried to term. Both infants are completely normal, with a non-mosaic ring 21 karyotype from the lymphocytes of one twin. The diagnostic uncertainty and problematic genetic counselling related to fetal cytogenetic abnormalities are the subjects of this report.     

Prenatal diagnosis of tetrasomy 21

Amniocentesis and prenatal diagnosis were done for late maternal age and an abnormality consistent with Tetrasomy 21 (47,XX,+t(21;21)) was found in every cell examined of the initial amniotic fluid. Clinical examination revealed a fetus with many of the signs of Down Syndrome and pathological examination revealed gross abnormalities of the internal structures. Follow-up tissues showed mosaic Tetrasomy 21.     

Prenatal diagnosis of mosaicism 46, XX/46, XX, −21, +t(21q21q)

Mosaicism for a structural chromosome abnormality in amniotic cell cultures indicative of true fetal mosaicism is a rare event. In addition to the laboratory findings the clinical interpretation for counselling in such cases is based on observation of the same abnormality in liveborns as well as previous experience with prenatal diagnosis of the same or similar abnormalities. We report here the prenatal diagnos is of 46,XX/46,XX,−21,+t(21q21q) which was confirmed in fetal skin cell and amnion cell cultures.     

Sustainable development and environmental protection: A perspective on current trends and future options for universities

Problems of sustainable development and environmental protection pose a challenge to humanity unprecedented in scope and complexity. Whether and how the problems are resolved have significant implications for human and ecological well-being. In this paper, I discuss briefly recent international recommendations to promote sustainable development and environmental protection. I then offer a perspective on the roles and prospects of the university in promoting sustainable development and environmental protection.     

我国水资源开发利用中亟待解决的几个认识问题

本文在分析８０年代在以来我国用水变化趋势基础上，探讨了北方地区的缺水程度，并对南水北调工程和可调水量提出了下些看法；文章还从水资源管理模式、法制和法规建设等方面阐述了对当前我国水资源管理政策方面的认识，从水的有效利用与水源保护、水的定价与成本回收、与水有关的社会与环境问题等方面论述了我国２１世纪将面临的有关水问题。