Abnormal amniotic fluid levels of CA 125 in second-trimester Down syndrome pregnancies

The aim of this study was to evaluate the concentration of CA 125 in second trimester amniotic fluid from Down syndrome pregnancies. CA 125 was measured in stored amniotic fluid samples from pregnancies of 14–19 weeks' gestation with and without Down syndrome fetuses. CA 125 levels were expressed in multiples of the median (MOM) for normal pregnancies of the same gestational age. Twenty-one pregnancies with Down syndrome fetuses and 63 unaffected controls matched for maternal age, gestational age, and duration of storage were studied. The median MOM values of the affected pregnancies were significantly higher than those of the controls (1·41 MOM versus 0·99 MOM). These findings show that there is an increased concentration of CA 125 in second-trimester amniotic fluid from Down syndrome pregnancies.     

Sirenomelia,the mermaid syndrome—detection in the first trimester

The sirenomelia sequence with fusion, rotation, hypotrophy or atrophy of the lower limbs in combination with severe urogenital and gastrointestinal malformations is a rare and usually lethal disorder. We present the case of a 28-year-old woman, who was referred to our department because of an intraabdominal cystic structure in the 9th week of gestation. Subsequent scans confirmed the diagnosis of a sirenomelia sequence with the fusion of the lower extremities without fusion of the bones according to Stocker I classification. The size of the intraabdominal cyst decreased during follow-up. After counseling, termination of pregnancy was induced. The postmortem X-ray confirmed the ultrasound diagnosis. The exact etiological mechanism of this malformation is still unknown. An early alteration of the embryological vascular network damaging the caudal mesoderm is thought to lead to arrested development of the lower limbs and other affected organs. The cyst we saw in the 9th week might fit with this theory, either as an expression of the complex malformation of the lower abdomen or as the sonographic appearance of necrosis. Copyright © 2003 John Wiley & Sons, Ltd.     

Life-history patterns of two Southern CaliforniaNebalia species (Crustacea: Leptostraca): the failure of form to predict function

Laboratory and field studies onNebalia hessleri andN. daytoni off the toast of San Diego, Southern California, showed that although morphologically similar, the habitats, behavior, and natural history of these two species are surprisingly different. In laboratory experiments, Bach species avoided the other's habitat (sand and mats of macrophyte detritus), and in the field, transplanted individuals failed to survive in the other species' habitat.N. hessleri, which inhabits subtidal mats of macrophyte detritus, survived and reproduced well in the laboratory, was iteroparous, and a large percentage of adults were male. This species occurred at very high densities in the field, and ate essentially everything offered in the laboratory, with a diet in the field consisting largely of plant detritus and carrion. The other species,N. daytoni, differed in nearly every way, it inhabited organically impoverished sands, survived poorly in the laboratory, was apparently semelparous, and a small percentage of the adult population was male.     

Detection of trisomy 21 by quantitative fluorescent–polymerase chain reaction in uncultured amniocytes

Prenatal diagnosis of fetal trisomy 21 is usually performed by cytogenetic analysis. This requires lengthy laboratory procedures, high costs and is unsuitable for large-scale screening of pregnant women. Today, trisomy 21 can be rapidly diagnosed within 24 h by molecular analysis of uncultured fetal cells using the semi-quantification of fluorescent PCR products from short tandem repeat (STR) polymorphic markers. The aim of our study was to test a chromosome quantification method on the basis of the analysis of fluorescent PCR products derived from non-polymorphic target genes. Co-amplification of a portion of DSCR1 (Down syndrome Critical Region 1) and the reference gene, CFTR (cystic fibrosis transmembrane regulator) enabled molecular detection of trisomy 21. Our method was successfully tested on a total of 154 amniotic fluids in a blind prospective study. Calculation of the DSCR1/CFTR ratio allowed us to distinguish between 152 normal amniotic fluids (mean ratio 0.99) and 2 amniotic fluids presenting a trisomy 21 status (DSCR1/CFTR ratio of 1.53 and 1.61, respectively). The results obtained by conventional cytogenetic analysis and our quantitative PCR method were concordant in every case. Our gene-based fluorescent PCR approach represents an alternative molecular method for rapid and reliable detection of trisomy 21, which can be helpful in the prenatal diagnosis of women at high risk of fetal trisomy 21. Copyright © 2003 John Wiley & Sons, Ltd.     

Molecular genetic prenatal diagnosis for a case of autosomal recessive spondylocostal dysostosis

Autosomal recessive spondylocostal dysostosis type 1 (ARSCD1) is a member of the heterogeneous group of disorders termed the spondylocostal dysostoses that are characterized by multiple vertebral segmentation defects and rib anomalies. In these patients, the entire vertebral column is malformed and is replaced by multiple hemivertebrae giving rise to truncal shortening, abdominal protrusion and non-progressive spinal curvature. Genetic studies have shown that some cases of ARSCD are due to mutations in the somitogenesis gene, Delta-like 3 (DLL3), that encodes a ligand for the Notch signalling pathway—ARSCD type 1. To date, 17 different DLL3 gene mutations have been reported. A consanguineous family of Turkish origin with ARSCD type 1 due to a homozygous DLL3 mutation requested genetic prenatal diagnosis. Using DNA from a chorionic villus sample, both linkage analysis of the DLL3/19q region and direct sequencing for the familial mutation demonstrated that the unborn fetus was an unaffected carrier. This is the first case of molecular genetic prenatal diagnosis in any form of SCD. Copyright © 2003 John Wiley & Sons, Ltd.     

Ventilation efficiency

Research indicates that ventilating systems can be designed for higher ventilation efficiency in the zone of occupation than systems designed for complete mixing. Expressions for ventilation efficiency are derived using a two-box theoretic model. These definitions of ventilation efficiency can be used for practical measurements, and also seem to be valid for multibox schemes. Measurements reviewed show that diagonal schemes are the most efficient. Short-circuiting schemes, with warm air supply along the ceiling and high wall exhaust, produce very low efficiencies. The mathematical model predicts high efficiencies using diffuse air supply directly to the zone of occupation, if the air is not used heating.     

Tests appropriate for the prenatal diagnosis of ataxia telangiectasia

A fetus ‘at-risk’ for ataxia telangiectasia (A-T) was monitored prenatally by several approaches which, in concert, might yield information of diagnostic value: measurement of amniotic fluid AFP levels; the clastogenic potential of ‘at-risk’ amniotic fluid; and cytogenic evaluation of fetal amniocytes. All three parameters proved negative and normality, based primarily on the chromosomal study of fetal cells, was therefore presumed. This conclusion was confirmed shortly after birth by normal serum AFP levels and the lack of increased spontaneous or clastogen-induced chromosome breakage in the infant's cells. Based on previous observations from four normal and one affected fetus, the coordination of these techniques provides adequate methodology for the antenatal assessment of the phenotypes associated with A-T.