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791.
A study was performed to investigate the concentrations of the α and β free sub-units of human chorionic gonadotrophin (free α-hCG and free β-hCG) in maternal serum between 15 and 22 weeks of pregnancy in 126 pregnancies among 92 women with insulin-dependent diabetes mellitus (IDDM). Each IDDM pregnancy was matched with two control singleton pregnancies for gestational age (same completed week) and duration of sample storage (same calendar quarter). The median free α-hCG level in the IDDM pregnancies was 0·86 multiples of the median (MOM) for pregnancies without IDDM at the same gestational age (P<0·002) (95 per cent confidence interval 0·80–0·94). The corresponding free β-hCG level was 0·96 MOM (95 per cent confidence interval 0·85–1·09). These results enable free α-hCG values to be adjusted so that antenatal screening for Down's syndrome can be performed using this marker in IDDM pregnancies as well as in non-diabetic pregnancies. 相似文献
792.
The technology has been available to detect carriers of haemoglobin disorders since the late 1960s. Prenatal diagnosis has been available since 1978. First trimester diagnosis by chorionic villus sampling and DNA analysis was introduced in 1982, and subsequent simplifications in DNA technology have made screening, counselling and prenatal diagnosis cost-effective at the community level, in countries at all levels of development. Audit of prenatal diagnosis for haemoglobin disorders in countries which have the resources and infrastructure necessary for genetic population screening (such as the UK and other European countries), has shown that the number of prenatal diagnoses actually performed fall far short of expectation. The demonstration that this reflects failures in delivering information, screening and counselling to the populations at risk, rather than rejection of prenatal diagnosis, shows the importance of placing more emphasis on the organisational and social requirements for genetic population screening. In some countries current attitudes towards abortion exclude provision of prenatal diagnosis within the health service, but in many such cases it has been set up in the private sector. It is also being introduced through combined private and charitable efforts in an increasing number of developing countries, including some with extremely limited health resources: such centres are likely to act as nuclei for emergence of genetics services in these communities. A particularly notable recent achievement is the introduction of prenatal diagnosis in Nigeria, where 1–2% of all children born suffer from sickling disorders. 相似文献
793.
Many monoclonal antibodies have been produced against tumour-associated cell surface antigens for cancer therapy. They have therefore been selected for minimal reactivity with normal tissues and in particular for lack of binding to blood cells or serum components. Many of the antigens recognized are of fetal origin. These monoclonal antibodies may therefore be ideal candidates to recognize and sort fetal trophoblasts from maternal blood for prenatal diagnosis of genetic abnormalities. A panel of 19 anti-tumour antibodies were therefore screened for reactivity with early trimester placenta and two, 340 and 154, were shown to stain trophoblasts. If MAb 340 is linked to magnetic beads, it can efficiently sort trophoblast cell lines from whole blood. 相似文献
794.
A case of focal nodular hyperplasia of the liver presenting in a 36-week-old fetus is reported. The tumour appeared on antenatal ultrasound as a 4·0 cm × 3·0 cm × 2·7 cm hypoechoic mass at the periphery of the right lobe of the liver. Colour Doppler imaging showed it to have prominent vascularity. Postnatally, sonography confirmed the presence of a vascular mass within the liver. The tumour was removed at laparotomy and was diagnosed as an area of focal nodular hyperplasia on histopathological examination. 相似文献
795.
Dr David A. Aitken Gary McCaw Jennifer A. Crossley Esther Berry J. Michael Connor Kevin Spencer James N. Macri 《黑龙江环境通报》1993,13(8):681-689
Alpha-fetoprotein (AFP), unconjugated oestriol (UE3), intact human chorionic gonado-trophin (intHCG), and the free β subunit of chorionic gonadotrophin (FβHCG) were investigated in a series of 21 chromosomally abnormal and 14 open neural tube defect pregnancies ascertained from a series of 14 000 prospectively collected maternal serum samples at 6–14 weeks' gestation. In 16 cases of Down's syndrome, significant reductions were found for AFP (0.65 multiples of the normal median) and UE3 (0.67 MOM). IntHCG levels were unaltered (0.97 MOM) but a significant increase was found for FβHCG (1.96 MOM). Significant correlations were found for AFP and UE3 in the controls and for int HCG and FβHCG in both the control and the Down's syndrome pregnancies. In a group of five trisomy 18 pregnancies, median MOMs were for AFP 0. 71 , for UE3 0. 34 , for intHCG 0. 27 , and for FβHCG 0.15. None of 13 pregnancies with open neural tube defects at 8-13 weeks gestation had elevated maternal serum AFP levels, whereas matched second-trimester samples from the same pregnancies at 16-18 weeks gestation all had significantly elevated AFP levels. Thus, biochemical screening for chromosome abnormalities may be practicable in the first trimester using free β human chorionic gonadotrophin in combination with AFP and maternal age. However, a separate screening protocol using AFP at 15-18 weeks gestation would still be required for effective detection of neural tube defects. 相似文献
796.
含机油废水微生物降解实验研究 总被引:1,自引:0,他引:1
从油污土壤中筛选分离出两株高效机油降解菌ZL1,ZL2,初步鉴定了黄杆菌属和微球菌属,通过生长条件正交实验测定了温度,底物浓度和pH对其降解能力的影响,在废水油浓度较高条件下进行了连续降解实验。结果表明:2d左右对于含油270mg/L的去除率分别达到67.9%和76.2%,其中ZL2菌对底物浓度和pH值有较广的适应范围。 相似文献
797.
V. Nikora R. Nokes W. Veale M. Davidson G. H. Jirka 《Environmental Fluid Mechanics》2007,7(2):159-172
The hydrodynamics of super- and sub-critical shallow uniform free-surface flows are assessed using laboratory experiments
aimed at identifying and quantifying flow structure at scales larger than the flow depth. In particular, we provide information
on probability distributions of horizontal velocity components, their correlation functions, velocity spectra, and structure
functions for the near-water-surface flow region. The data suggest that for the high Froude number flows the structure of
the near-surface layer resembles that of two-dimensional turbulence with an inverse energy cascade. In contrast, although
large-scale velocity fluctuations were also present in low Froude number flow its behaviour was different, with a direct energy
cascade. Based on our results and some published data we suggest a physical explanation for the observed behaviours. The experiments
support Jirka’s [Jirka GH (2001) J Hydraul Res 39(6):567–573] hypothesis that secondary instabilities of the base flow may
generate large-scale two-dimensional eddies, even in the absence of transverse gradients in the time-averaged flow properties. 相似文献
798.
R. H. Lindenbaum M. Ryynänen M. Holmes-Siedle E. Puhakainen J. Jonasson J. Keenan 《黑龙江环境通报》1987,7(7):511-519
Maternal serum and amniotic fluid alpha-fetoprotein levels were studied retrospectively in a total of 58 pregnancies with trisomy 18. In those pregnancies uncomplicated by either fetal exomphalos or neural tube defect the midtrimester maternal serum alpha-fetoprotein (MSAFP) levels were markedly reduced, the median value for 38 such pregnancies being 0.6 multiples of the median (MoM). Trisomy 18 with exomphalos was associated with a higher median MSAFP, but still within the normal range: 1.1 MoM, (nine pregnancies); trisomy 18 with exomphalos and neural tube defect (NTD) was associated with grossly raised levels: median MSAFP was 4-5 MoM (three pregnancies). Amniotic fluid alpha-fetoprotein (AFAFP) levels were normal in uncomplicated trisomy 18 pregnancies: median AFAFP, for 19 pregnancies, was 1.1 MoM. Exomphalos alone, or together with neural tube defect, was associated with greatly elevated levels of AFAFP; for exomphalos alone median AFAFP was 9.59 MoM (four pregnancies), and for exomphalos with neural tube defect the median AFAFP was 23.95 Mom (three pregnancies). Screening with low and high MSAFP, routine ultrasound, and amniocentesis on all women aged 35 years or over, together might identify over 50 per cent of pregnancies with trisomy 18. 相似文献
799.
James N. Macri Kevin Spencer Kenneth Garver Philip D. Buchanan Burhan Say Nancy J. Carpenter Francoise Muller Andre Boué 《黑龙江环境通报》1994,14(2):97-103
The median maternal serum free beta human chorionic gonadotropin (hCG) multiple of the median (MOM) of 480 Down syndrome cases in the second trimester was 2·64, significantly greater than the reported median MOM of intact hCG (p<0·0001). In 234 of these cases from retrospective and prospective studies, the effectiveness of maternal serum free beta hCG was evaluated in combination with alpha-fetoprotein (AFP) and maternal age in second-trimester Down syndrome screening. Down syndrome detection in the gestational age range of 14–16 weeks was 82 per cent. In all gestational weeks (14–22), a 77·7 per cent Down syndrome detection rate was achieved. In prospective screening of 44 272 patients under the age of 35 years, 69 per cent of Down syndrome cases were detected (73 per cent in gestational weeks 14–16). The false-positive rate for the prospective study was 3·8 per cent. The use of free beta hCG combined with maternal serum AFP and maternal age-related risk for Down syndrome in a screening population (i.e., women under 35 years) yields an improved detection efficiency over other protocols. 相似文献
800.
We assayed maternal serum samples from 134 black and 268 white women from 16 to 18 weeks of gestation for intact human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3). Serum from women with high ( ⩾ 2·5 MOMs) or low (risk for Down syndrome ⩾ 1/365) maternal serum alpha-fetoprotein (MSAFP) levels were excluded. After correcting for maternal weight, we found that median hCG levels were 16 per cent higher in black women but uE3 levels were not significantly different. These results confirm three other studies for hCG and one study for uE3. Corrections are recommended for both maternal serum hCG and AFP before calculating the risk for Down syndrome in black women. 相似文献