First-trimester prenatal diagnosis of aspartylglucosaminuria

Fetal aspartylglucosaminuria (AGU) was studied during the first trimester of pregnancy in six at-risk pregnancies using chorionic villus samples. The activity of aspartylglucosaminidase (AGA) was high in five cases, indicating an unaffected fetus. This was confirmed through delivery of healthy newborns with a normal pattern of urinary oligosaccharides. Low enzyme activity in an uncultured biopsy specimen and in cultured amniotic fluid cells in one case demonstrated that the fetus was affected. The pregnancy was terminated and the prenatal diagnosis was confirmed by showing reduced AGA activity in cultured fibroblasts of the fetus.     

A Framework for Monitoring and Evaluating Carbon Mitigation by Farm Forestry Projects: Example of a Demonstration Project in Chiapas,Mexico

Mitigation and Adaptation Strategies for Global Change - In Mexico an estimated 4.5 × 106ha are available for farm forestry, while up to 6.1 × 106 ha could be saved from deforestation by...     

LPG降低城市废气的环保能源

为了缓解火气污染，广州市交委于2003年赵在广州市公交、出租行业全面推广使用LPG燃料。在两年多的推广应用过程中，LPG车辆在广州市公交、出租行业中已得到成功的应用。LPG作为环保能源，它的环保功能体现在哪些方而？让我们一起了解。     

Second-trimester cancer antigen 125 and Down's syndrome

This study explores if assay of cancer antigen 125 (CA 125) in maternal serum might aid the detection of Down's syndrome in the second trimester of pregnancy. CA 125 levels were determined retrospectively in stored maternal serum samples from ten Down's syndrome pregnancies and 78 controls matched for gestational and maternal age. In addition, second-trimester amniotic fluid samples from nine Down's syndrome and 109 unaffected pregnancies were analysed for CA 125. Maternal serum CA 125 values for Down's syndrome pregnancies were lower, with the median being 0.72 multiples of the unaffected population median. The medians for affected and unaffected pregnancies did not differ significantly and there was a considerable overlap in the range of values of cases and controls. The distribution of amniotic fluid CA 125 levels for Down's syndrome pregnancies resembled that for controls. From our present results, we could not find an association between Down's syndrome and second-trimester maternal serum or amniotic fluid CA 125 levels.     

Extraction of DNA from amniotic fluid cells for the early prenatal diagnosis of genetic disease

Ten-ml samples of amniotic fluid were taken from pregnancies being terminated at 8–14 weeks' gestation. DNA was extracted from the amniotic cells by sequential centrifugation and analysed using the polymerase chain reaction (PCR). Fifteen samples were analysed for evidence of maternal contamination using Mfd5 oligo-nucleotide primers for repeat polymorphisms. Ten amniotic fluid samples were tested for the Delta-F₅₀₈ deletion characteristic of cystic fibrosis to demonstrate a diagnostic application for the technique. In each case, DNA extracted from fetal tissue from the same pregnancy was included in the controls. In 14 of the 15 cases tested with the Mfd5 primers, both the amniotic fluid DNA and the fetal DNA showed no evidence of contaminating DNA. In one case, neither the amniotic fluid cells nor the fetal cells yielded results. In nine of the ten cases tested with the Delta-F₅₀₈ primers, the amniotic fluid cell DNA provided accurate information about the genetic status of the fetus; in the tenth, the fetal DNA failed to amplify. The results indicate that adequate DNA can be extracted from amniotic fluid from 8 weeks' gestation onward and these samples are suitable for prenatal diagnosis using PCR.     

Vitamins,folic acid and neural tube defects: Comments on investigations in the United States

No clear answer concerning whether multivitamin/folate supplementation prevents neural tube defects (NTDs) is provided by three studies in the United States. All these studies are occurrence in nature, no recurrence studies having been conducted. The Atlanta Birth Defects Study is subject to pronounced memory and recall biases, the length between event and interview being as long as 16 years. In a second study (Boston University), objections can be raised to certain aspects of the experimental design, and the claim that 22 per cent of women started vitamins sufficiently early after pregnancy diagnosis to influence NTD formation is suspicious. Our NICHD case control study of 541 women in California and Illinois revealed no evidence for multivitamins or folic acid preventing NTDs. U.S. public policy-makers face difficulties in applying results of recurrence or occurrence studies in high-risk areas to low-risk areas in the U.S.     

Prenatal screening and diagnosis of neural tube defects in England and Wales in 1985

A survey was carried out to determine the effect of prenatal screening and therapeutic abortion on births in 1985 with anencephaly and spina bifida in England and Wales. Maternal serum alpha-fetoprotein tests were done on 399 288 women (60 per cent of pregnant women): 4 per cent were reported as being screen-positive and 1 per cent had an amniocentesis. An estimated 534 pregnancies associated with anencephaly were terminated and an estimated 445 pregnancies associated with spina bifida (but without anencephaly) were terminated. Most (63 per cent) of the anencephalic pregnancies were first suspected from an ultrasound examination; 57 per cent of the spina bifida pregnancies were first suspected from a positive maternal serum alpha-fetoprotein test, 35 per cent by ultrasound, and the remaining 8 per cent by other means. The birth prevalence of anencephaly declined by 94 per cent between 1964–1972 and 1985, but when the terminations of pregnancy on account of having a fetus with anencephaly are added to the births the decline in prevalence was only 50 per cent. The birth prevalence of spina bifida declined by 68 per cent over the same period but when the terminations were added to the births the decline in prevalence was only 32 per cent. Among births with anencephaly 66 per cent had had no screening or diagnostic tests in early pregnancy, but in those that did nearly all were positive–usually in twin pregnancies where one fetus was affected but not the other. Among births with spina bifida, 48 per cent had no tests and in those that did the results were mainly negative. We conclude that in order to monitor adequately the national screening programme for anencephaly and spina bifida a special neural tube defects register should be formed.