Pitfalls in the prenatal diagnosis of peroxisomal β-oxidation defects by chorionic villus sampling

Variability in the level of expression of very long chain fatty acids (VLCFAs) is documented in cultured chorionic villus (CV) cells derived from two fetuses, one at risk for an unusual peroxisomal fatty acid β-oxidation defect, and the other at risk for the X-linked form of adrenoleucodystrophy (ALD). Cells from early subcultures of chorionic cells from both cases gave normal values for VLCFA ratios. The results for the fetus at risk for the β-oxidation defect were interpreted to indicate that the fetus was not affected; however, at birth, the infant was clinically and biochemically affected. In the case of the fetus at risk for X-linked ALD, although VLCFAs were normal in subculture 1, the levels of these fatty acids increased dramatically in subculture 3, suggesting an abnormal fetus. Termination of the pregnancy and subsequent biochemical and morphological follow-up confirmed that the fetus was indeed affected by ALD.     

Rapid prenatal diagnosis of aneuploidy from uncultured amniotic fluid cells using five-colour fluorescence in situ hybridization

In this paper we describe the use of five-colour fluorescence in situ hybridization for prenatal diagnosis of aneuploidy using uncultured amniotic fluid cells. The analysis is based on ratio mixing of dual-labelled probes and digital imaging for the detection and visualization of five different probes specific for the five target chromosomes, 13, 18, 21, X, and Y. A retrospective blind analysis of 30 coded uncultured amniotic fluid samples correctly detected fetal sex and five trisomy 21 cases. Multicolour fluorescence in situ hybridization used in this way allows rapid and simultaneous detection of the most frequent aneuploidies.     

Flow cytometric method to measure urea-resistant alkaline phosphatase from blood neutrophils for use in the prenatal screening of Down's syndrome

The histochemical measurement of urea-resistant alkaline phosphatase from maternal blood neutrophils is known to have a high detection rate for the prenatal detection of Down's syndrome pregnancies. However, because the histochemical method is laborious and subjective to use, it has not gained widespread acceptance in prenatal screening programmes. We present a simple and objective method for the measurement of urea-resistant alkaline phosphatase by flow cytometry. The method should allow the design of larger studies aimed at evaluating the role of neutrophil urea-resistant alkaline phosphatase in the prenatal screening for Down's syndrome.     

Selenium metabolism in animals and humans

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Environmental impact on the development of agricultural technology in China: the case of the dike-pond (‘jitang’) system of integrated agriculture-aquaculture in the Zhujiang Delta of China

The development of the environmentally conserving dike-pond system of integrated agriculture and aquaculture in the Zhujiang Delta of south China is traced to illustrate the impact of environmental changes on technological innovations. The technologies of dike building, land reclamation, pond fish culture, and crop cultivation on dikes, which were either independently developed or modified from ideas brought in by migrant farmers from northern China, represented farmers' efforts to adapt to the new characteristics of a changed environment as population pressure increased. The new technologies revealed the farmers' awareness of the need for environmental conservation. However, increased population pressure also necessitated more intensive use of the land, both in the highland and lowland regions, giving rise to inappropriate dike building and premature reclamation activities, which in turn brought about more frequent flooding in the delta region. Careless application of a new technology tended to have harmful effects on the environment. Political conditions in different periods of China's economic development have also caused changes in the dike-pond system which has to maintain high productivity and profitability. Recent advances in dike-pond system technology have focused on crop diversification and animal husbandry to match the three-dimensional characteristics of its ecological components. New agricultural technologies can be successful in China only if they can provide a balance between land use and conservation.     

Management Options to Conserve and Sequester Carbon in the Agricultural Sector of the Former Soviet Union

Several management practices are available to conserve and sequester C in the agricultural sector of the former Soviet Union (FSU). The highest rate of C accumulation would result from the implementation of a no-till management option which will only continue during the first ten years until new C equilibrium is reached. Agroforestry management options provide a longer period for C accumulation, but at a lower rate. It is possible that the longest period of C conservation may be achieved by increasing the area under perennial grasses in the crop rotation. During the first decade of implementation of the management practices, the amount of C conserved or sequestered would be approximately equal to the current rate of net C sequestration in FSU forest sector. At present, agricultural soils and vegetation of the FSU store approximately 120 Pg C; the accumulation of soil organic matter is 0.032 Pg C yr^-1. The annual C loss in the FSU agricultural sector was estimated at 0.21 Pg C yr^-1.