不同来源腐殖酸的光解及过氧化氢对其影响

为探讨腐殖酸在环境中的行为及光解除去腐殖酸的可能性，利用大于２９０ｎｍ的模拟日光辐照，探讨了大骨节病病区、非病区腐殖酸和泥炭腐殖酸的光解过程和光解机理及过氧化氢对其光解的影响，发现随着光照时间的延长，腐殖酸水体系的总有机碳（ＴＯＣ）含量降低，ｐＨ值下降，过氧化氢可以促进腐殖酸的光解，其光解过程遵循一级动力学规律。计算了不同来源腐殖酸光解的速率及光解半衰期，发现土壤和泥炭腐殖酸比大骨节病病区饮水中腐     

Implications of maternal serum alpha-fetoprotein elevation caused by transabdominal and transcervical CVS

Of 2882 women allocated to either transabdominal CVS (TA) or transcervical CVS (TC) at two large obstetric centres in Denmark, 2707 had blood samples drawn before and 30 min after CVS for maternal serum-alpha-fetoprotein (MSAFP) measurement. 2535 of these women had cytogenetically normal pregnancies and 2091 of them went on to have samples drawn at the 18–20 week follow-up. Post-procedure MSAFP values were correlated to the biopsy method used, with mean MSAFP values significantly higher after TA than TC, 33 and 15 kU/l, respectively (P<0·001). Following TA procedures, 18 per cent of cases had feto-maternal transfusion higher than 0·1 ml; this occurred in only 5 per cent of TC cases. MSAFP levels were associated with spontaneous fetal loss in the TA group but not in the TC group. TC, however, was followed by more losses than TA. The post-CVS MSAFP value was positively correlated with the amount of villi aspirated. The difference in post-procedure elevation in MSAFP 30 min later (average 18 kU/l higher for TA than for TC) was not reflected in raised levels at the 18–20 week follow-up. Study medians at mid-trimester did not differ from reference group medians established from a group of singleton pregnancies with sonographically determined gestational age who did not experience invasive procedures and delivered normal infants. Our findings suggest that CVS does not compromise mid-trimester MSAFP for screening for neural tube defects (NTDs). Extremely high mid-trimester MSAFP values in the TC group could predict imminent loss.     

Evaluation of X,Y, 18, and 13/21 alpha satellite DNA probes for interphase cytogenetic analysis of uncultured amniocytes by fluorescence in situ hybridization

The major aneuploidies diagnosed prenatally involve the autosomes 13, 18, and 21, and sex chromosomes. Fluorescence in situ hybridization (FISH) allows rapid analysis of chromosome copy number in interphase cells. This prospective study evaluated the use of four commercially available centromeric DNA probes (DXZ1, DYZ1, D18Z1, and D13Z1/D21Z1) for direct analysis of uncultured amniocytes. One hundred and sixteen amniotic fluid samples were analysed by FISH and standard cytogenetics. This evaluation demonstrated that FISH with, X, Y, and 18 alpha satellite DNA probes could accurately and rapidly detect aneuploidies involving these chromosomes and could be used in any prenatal clinical laboratory. In contrast, the 13/21 alpha satellite DNA probe hybridizing both chromosomes 13 and 21 was unreliable for prenatal diagnosis in uncultured amniocytes.     

Maternal serum inhibin levels in second-trimester down's syndrome pregnancies

Maternal serum inhibin levels were measured in 19 second-trimester pregnancies affected by fetal Down's syndrome and 95 unaffected control pregnancies matched for gestational age. A statistically significant elevation was found in the affected pregnancies compared with the controls (Wilcoxon rank sum test: one-tail P=0·02). The median level in the cases was 1·3 times that in the controls, with 95 per cent confidence limits of 0·9–1·9. Although the inhibin levels were unrelated to those of alpha-fetoprotein and unconjugated oestriol in the same samples, there was a statistically significant correlation with human chorionic gonadotropin. This together with the relatively small elevation in cases suggests that inhibin would be of limited value in maternal serum screening for Down's syndrome.     

Fetal nuchal oedema and antenatal diagnosis of trisomy 10

Trisomy 10 was detected at amniocentesis undertaken following observation of fetal nuchal oedema. This is the first report of fetal trisomy 10 in association with nuchal oedema. The physical features of fetal trisomy 10 are described.     

Early amniocentesis—a cytogenetic evaluation of over 1500 cases

We report our cytogenetic experience of 1554 early amniocenteses between weeks 11 and 14 of gestation, of which 44 per cent were performed prior to week 14. The mean culture time was 14·5 days. Karyotyping was successful in 99·7 per cent of cases. In 9·9 per cent of cases, there was pseudomosaicism with a high rate of loss of an X-chromosome and structural aberration of chromosome 1, which may be due to the Chang medium. The mosaic rate was 0·5 per cent. The overall aberration rate was 2·8 per cent. Our data confirm the reliability of early amniocentesis, which is a serious alternative to standard amniocentesis and chorionic villus sampling (CVS).