First trimester amniocentesis between the seventh and 13th weeks: Evaluation of the earliest possible genetic diagnosis

Amniocentesis performed at the 12th week and later gives reliable results. The procedure can be performed using regimens developed for mid-trimester amniotic fluid (AF) cells. Extension to the 10th–11th week is, in principle, feasible. However, the high cytogenetic failure rate is a difficulty and despite a high clone count, the culture time is prolonged. The problem of the relatively high loss of AF could be overcome by cell filtration techniques and replacement of the fluid. Because of the short turnover rate of the AF, this may be unnecessary or replacement with an isotonic solution may be sufficient. (Pseudo)mosaicism appears to occur more frequently in early than in late amniocentesis. As yet, data are too sparse to allow a comparison with chorionic villus sampling. There are no reliable follow-up data from which to estimate the abortion rate and the number of embryonic malformations.     

Incidence of fetal chromosome abnormalities in 2264 low-risk women

Among a population of 6305 pregnant women, aged 25 to 34 years and estimated to be at no increased risk of genetic disease in the fetus, 4606 women participated in a randomized controlled trial of genetic amniocentesis between 1980 and 1984. In the study group having amniocentesis (2264 women), 23 fetal chromosome abnormalities (1.0 per cent) were found: eight autosomal aneuploidies, seven sex chromosome aneuploidies, seven balanced structural rearrangements and one case of a marker some. The structural rearrangements and the marker chromosome were all shown to be inherited. The study group seemed representative for the whole population of younger women at low genetic risk. Therefore, a 1.0 per cent total rate of fetal chromosome abnormalities, consisting of one-third autosomal aneuploidies, one-third sex chromosome aneuploidies and one-third structural rearrangements, may be expected in the second trimester in younger low-risk women. In the same period of time, 562 women in the same age group were offered amniocentesis because of an estimated increased risk of fetal genetic disease. The total rate of fetal chromosome abnormality in this ‘high-risk’ group was 0.9 per cent and thus no different from the rate in the low-risk group.     

The development and applications of a Drought Early Warning System in Botswana*

This article describes the indicators and data sources used by the Botswana Drought Early Warning System formally established in early 1984, the main uses of the indicators in the assessment of drought conditions and the design of relief programmes are outlined. Limitations of the sources of data available are discussed, as is the feasibility of adding some possible further indicators. In conclusion, the importance of a functioning Early Warning System in a country highly susceptible to repeated droughts is stressed, in the context of die current effort to elaborate a comprehensive National Food Strategy and to establish a Regional Early Warning System for Southern Africa.     

Risk of amniocentesis in women screened positive for Down syndrome with second trimester maternal serum markers

In routine obstetrical practice, prior to offering invasive prenatal diagnosis, it is crucial to weigh the risks attendant on amniocentesis against the individual's risk of aneuploidy. We took advantage of a policy of follow-up of patients undergoing Down syndrome maternal serum screening to compare the rates of fetal loss before 24 weeks and of early premature delivery at 24–28 weeks between women who underwent amniocentesis and women who did not. A total of 54 902 patients entered the study, of whom 4039 (7.35%) were lost to follow-up and 387 were excluded because of a severe fetal abnormality. Of the 50 476 remaining patients, 3472 had an amniocentesis whereas 47 004 had not and served as controls. In the amniocentesis group, the fetal loss rate before 24 weeks was 1.12% (95% CI=1.08–1.15) and the 24–28 weeks premature delivery rate was 0.40% (95% CI=0.39–0.41) which was significantly higher than in controls (0.42% with 95% CI 0.41–0.43 and 0.24% with 95% CI 0.23–0.25, respectively). The 0.86% difference in adverse outcome rates between the amniocentesis and control groups may be attributable to amniocentesis and compares favourably with the positive predictive value of maternal serum markers (1.70%) observed in the present study. Copyright © 2002 John Wiley & Sons, Ltd.     

Digit length ratio (2D/4D): comparing measurements from X-rays and photographs in field voles (<Emphasis Type="Italic">Microtus agrestis</Emphasis>)

The ratio of second-to-fourth digit length (2D/4D) has been suggested to be a useful adult age marker of intrauterine exposure to steroids because it should be sexually dimorphic and fixed already in utero. Numerous studies mainly on humans have supported this conclusion, but it is yet unclear how well this applies to other vertebrates. This information would be especially valuable to field biologists to whom measuring steroids in utero is often impossible. The non-human studies conducted so far have yielded inconsistent results, perhaps due to the variety of different methods employed in measuring 2D/4D. We examined the age and sex dependency and lateral asymmetry of 2D/4D in field voles (Microtus agrestis) and compared whether these effects differed between 2D/4D measurements taken from photographs and X-rays. Our results show that 2D/4D measurements from photos had a higher measurement error and gave consistently higher 2D/4D than those from X-rays. According to both measurement methods, the right paw showed higher 2D/4D values than the left paw (lateral asymmetry). Adult voles had a lower 2D/4D than juveniles when measured from X-rays, but not when measured from photographs. We found no evidence for a sex difference in 2D/4D using either of the measurement methods. Our findings thus suggest that X-rays, due to their greater accuracy, should be preferred over photographs for measuring digit ratios in rodents. Our results also indicate that in this species, 2D/4D is laterally asymmetric, but it may not be either fixed in utero or sexually dimorphic. In conclusion, 2D/4D appears to be a rather species- and method-specific measure and researchers should be careful when generalising its applicability to study early hormonal effects in vertebrates.     

An early warning method of landscape ecological security in rapid urbanizing coastal areas and its application in Xiamen, China

Based on the Pressure-State-Response (P-S-R) approach, an index system for landscape ecological security (LES) was suggested using three dimensions, six factors, and three weights. The indicators in the system were divided into two groups: spatial interpolation (acquired by the remote sensing data) and non-spatial interpolation (acquired by consultation with experts). According to data of 2003 and 2006, coupled with current tendencies, the early warning method was classified into four categories: security and degradation, sub-security and slow degradation, sub-security and rapid degradation, and insecurity. Our research with early warning method finds three interesting phenomena: (1) mean value of LES in 2003 was 0.586, indicating medium security; while in 2006 it was 0.650, an upper medium security. The LES level within each districts of Xiamen in 2006 was better than the level in 2003. In terms of LES, the comprehensive condition within each district of Xiamen in 2006 was enhanced compared with 2003. Overall, there was improvement in 80.5% of areas from 2003 to 2006, showing promising signs of positive development. (2) The LES of Xiang’an District and Jimei District were in stages of high early warning given that the percentage of land in these districts that showed symptoms of insecurity and degradation was 41.03 and 34.89%, respectively. (3) On the whole, the areas that showed notable signs of insecurity and rapid landscape, and which can already be identified as early warning areas requiring immediate attention, correspond closely with the distribution of coastal industrial parks in these regions. In conclusion, the consequences of rapid industrialization and urbanization are far reaching and affect local and regional ecological security.     

Early prenatal diagnosis of A lethal syndrome of multiple congenital contractures

An ultrasonic diagnosis of a lethal, autosomally recessive syndrome of multiple congenital contractures was made in seven high-risk pregnancies on the 13rd to 17th gestational weeks. The diagnostic findings were the development of progressive subcutaneous oedema from the 13th gestational week on and the decrease of fetal limb movements.