Alpha-fetoprotein levels and yolk sac size in the first trimester of pregnancy

Transvaginal ultrasound measurement of the yolk sac and transvaginal amniocentesis were carried out on 94 women prior to first-trimester termination of pregnancy. Maternal serum and fluids from the amniotic cavity and extraembryonic coelom were analysed for alpha-fetoprotein (AFP). No correlation was found between the yolk sac size and the levels of AFP in any of these sites.     

Prenatal diagnosis of Lesch-Nyhan syndrome: Experience with three fetuses at risk

Our experience with the prenatal detection of the Lesch-Nyhan syndrome (LNS; hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency) in three fetuses at risk is reported. Enzyme activities were measured in cultured amniocytes in two pregnancies, and in tissues and cultures obtained from chorionic villus sampling (CVS) in a third pregnancy. In all tissues the specific activities of HGPRT and adenine phosphoribosyltransferase (APRT) were determined and APRT/HGPRT ratios were calculated. In addition to the enzyme assays, the rate of purine synthesis de novo was assessed in the two amniocyte cultures, and the rate of [¹⁴C]hypoxanthine incorporation into nucleotides and sensitivity to azaguanine were measured in one of the amniocyte cultures. We report the diagnosis of normal fetuses by study of amniocytes in two pregnancies and of LNS using CVS in one pregnancy. In all three cases the diagnosis was confirmed.     

Exophthalmus–prenatal ultrasonic features for diagnosis of Crouzon syndrome

Prenatal real-time ultrasonographic diagnosis of exophthalmus is presented. Diagnosis was made at the 35th week of gestation in a fetus of a patient affected with Crouzon syndrome (craniofacial dysotosis). Recognition of exophthalmus as a part of Crouzon syndrome and the easy visualization of the eye balls and palpebrae in the third trimester made the diagnosis possible.     

The early prenatal sonographic diagnosis of renal agenesis: Techniques and possible pitfalls

Out of 13 252 cases in which fetal bilateral echogenic kidneys were detected by transvaginal sonography between 12 and 18 weeks' gestation, there were nine fetuses where oval hypoechogenic masses were detected in the renal bed. In five fetuses where hypoechogenic masses in the renal bed were sonographically visualized, postabortal examination was compatible with renal agenesis and the hypoechogenic masses proved to be enlarged adrenals. In three additional cases, unilateral renal agenesis was accompanied by unilateral enlarged adrenals, radiologically confirmed postnatally. In one case, a false-positive sonographic diagnosis of Potter syndrome was made because of bilateral hypoechogenic masses in the renal bed. Postabortal examination detected hypoplastic kidneys, but of normal histology, in a dyskaryotic fetus with trisomy 22. In four cases of renal agenesis, the amniotic fluid was of normal volume until the 17th week. In two of the five cases of Potter syndrome, a cystic structure, compatible with the urinary bladder, was detected in the pelvis at 14 weeks. The diagnostic criteria for renal agenesis in the early fetus differ from those used in the second half of gestation.     

Identification of key issues for further investigation in improving the reliability of life-cycle assessments

The interative nature of life-cycle assessment (LCA) means that more details are looked for until a certain level of reliability has been achieved. This paper is concerned with the identification of key issues for further investigation in such an iterative procedure. Key issues in this context are defined as those aspects of an LCA which need more detailed research to arrive at a solid conclusion. The main concept in the context of finding key issues is the study of the propagation of uncertainties in underlying data. The structured procedure of LCA can be described in mathematical terms, so that standard mathematical techniques for the study of the propagation of uncertainties can be employed. The influence of uncertainties in input data on uncertainties in output data can be calculated, and the main source of the resulting uncertainties can be identified. The result of the analysis is a list of prioritized key issues for more detailed research and more accurate data.     

盐度变化对日本对虾暴发白斑综合症病毒病的影响

为研究盐度在对虾暴发白斑综合症 (whitespotsyndrome)过程中所起的作用 ,进行了盐度变化对日本对虾免疫水平的影响实验及不同盐度下的人工感染实验。结果显示 :(1)盐度是影响日本对虾生理、存活的重要环境因子 ;(2 )盐度变化能够影响对虾的免疫状况 ,盐度升高和降低都会降低日本对虾的免疫水平 ;(3)在偏离对虾正常生存盐度的环境中 ,对虾抵御外来感染能力降低 ,易受病原体如WSSV的感染 ;(4)盐度变化是导致对虾爆发白斑综合症的重要诱因之一。     

Prenatal diagnosis of zellweger's syndrome by chorionic villus sampling-and a caveat

At 7·5 weeks gestation, two small chorionic villous biopsies were obtained from a woman at risk for Zellweger's cerebro-hepato-renal syndrome, and were separately established in culture. After 3 weeks, dihydroxyacetone phosphate acyltransferase (DHAP-AT) activity was measured in both cultures. The enzyme was markedly deficient in one cell strain and this was subsequently shown to have a male karyotype. However, the second culture had normal enzyme activity and a female karyotype. The pregnancy was terminated at 11·5 weeks gestation, and follow-up studies on fetal tissues confirmed a male fetus with markedly deficient DHAP-AT activity.     

A case of partial sirenomelia and possible vitamin A teratogenesis

Prenatal echographical findings of a partial sirenomelic fetus are described. An attempt was made to terminate pregnancy by administration of prostaglandin F₂a, but uterine rupture occurred. The teratogenic role of vitamin A ingested by the mother in the penconceptional period is discussed.     

Amniotic band syndrome in second trimester associated with fetal malformations

The Possibility of severe fetal malformations, including neural tube defects, secondary to early amniotic rupture followed by formation of fibrous bands (amniotic band syndrome) is a well-known entitity. The fact that these pregnancies are usually uneventful makes prenatal diagnosis difficult, but routine determination of serum alphafetoprotein, followed by ultrasound scanning, may detect some of the malformations. We present a case, where detection of a neural tube defect led to induced second trimester abortion of a fetus severely affected by this syndrome. There appeared to be a causal relationship between maternal trauma and the amniotic rupture.