Reactivity of amniotic fluid alpha-fetoprotein with concanavalin A in relation to gestational age: clinical implications

We used concanavalin A crossed-line affinity immunoelectrophoresis to determine the percentage of concanavalin A nonreactive alpha-fetoprotein in amniotic fluid samples from pregnancies with normal and abnormal fetuses. In 167 samples from pregnancies with a normal outcome and normal values for total alpha-fetoprotein concentration in amniotic fluid the percentage decreased from a median value of 27.4% in the 13th week to 8.5% in the 21st week of gestation, and a statistically significant (p < 0.001) average decrease of 1.7% per week was found from the 14th to the 19th week. A similar average decrease (2.2%) was found in 22 pregnancies from which two or more samples were obtained. The clinical significance of this decrease is discussed. Of 108 samples from patients with above-normal values for total alpha-fetoprotein and a normal outcome, seven had a total alpha-fetoprotein above recommended cut-off values, and only one of these had a low percentage of concanavalin A nonreactive alpha-fetoprotein. In contrast, for all 27 samples from pregnancies with a severe fetal malformation this percentage was low, even in one case where the total alpha-fetoprotein concentration was below the recommended cut-off value.     

羊水量正常时胎儿肾发育不良的超声诊断及临床意义

目的 探讨产前超声检查对于羊水量正常时胎儿肾发育不良的诊断价值和临床意义.方法 于孕中晚期对羊水量正常胎儿中发现的单侧或双侧肾超声表现异常(包括大小、回声、形态异常,出现囊肿等)病例进行系统二维超声检查、孕期及生后随访观察、病理学检查等,并进行总结分析.仅有肾盂增宽的胎儿不包括在本组研究中.结果 发现羊水量正常但单侧或双侧肾发育不良的胎儿11例.其中单侧多囊性肾发育不良5例,4例不合并其他异常,1例合并同侧手缺如;单侧肾缺如2例,其中1例不合并其他畸形,另1例合并多发畸形包括脑积水、骶尾部脊柱裂、同侧桡骨缺失及单脐动脉,符合VACTERL综合征;盆腔.肾1例,马蹄肾1例,生后超声证实;常染色体显性遗传多囊肾1例,胎儿一侧肾可见多发囊肿,合并心脏横纹肌瘤,孕妇为双侧多囊肾;双侧肾发育不良1例,产前超声表现为双侧肾回声增强.结论 单侧多囊性肾发育不良是羊水量正常时产前超声最常检出的胎儿肾发育不良性疾病.根据产前超声表现并结合家族史,能在大多数胎儿肾发育不良病例中进行病因学诊断并帮助判断预后.     

Concanavalin A binding of alpha-fetoprotein in amniotic fluid as an aid in the diagnosis of neural tube defects

Concanavalin A nonreactive alpha-fetoprotein was determined in samples of amniotic fluid from 16 abnormal pregnancies complicated by anencephaly (7), open spina bifida (6), intra-uterine death (1), anencephaly with exomphalos (1), or open spina bifida with exomphalos (1), and in amniotic fluid from 50 normal pregnancies with gestational age between 13 and 24 weeks. In all 16 cases with fetal malformations, the proportion of nonreactive alpha-fetoprotein was significantly decreased (median 5.3%) as compared with amniotic fluid from pregnancies with a normal outcome (median 39.7%). The results confirm that this measurement is useful in the diagnosis of neural tube defects, especially when the concentration of alpha-fetoprotein in amniotic fluid is normal or only slightly above normal and gestational age is uncertain.     

Acetylcholinesterase and butyrylcholinesterase measurement in the pre-natal detection of neural tube defects and other fetal malformations

Acetylcholinesterase activity in amniotic fluid was measured at 30 degree C by a reaction rate method employing acetyl-beta-methyl thiocholine as substrate and ethopropazine as a selective inhibitor of butyrylcholinesterase. This assay proved more specific than previously reported methods. Activity was greater in five cases of anencephaly (4.8-9.7 U/l) and nine cases of spinal bifida (5.1-8.6 U/l) than in 50 pregnancies with normal outcome (mean activity 2.0 +/- 0.9 (S.D.) U/l). There was no overlap between results from normal and neural-tube-defect groups, and the results showed no significant correlation with gestational age. Butyrylcholinesterase activity in amniotic fluid was measured using butyrylthiocholine as substrate. In accordance with previous reports, levels were elevated in pregnancies affected by neural tube defects. The ratio butyrylcholinesterase/acetylcholinesterase activity showed similar values for anencephalic, spina bifida and normal pregnancies; however, the two cases of exomphalos investigated could be clearly distinguished from all other groups on this basis.     

Association of amniotic fluid index with estimated fetal weight.

OBJECTIVE: The relationship between amniotic fluid volume and gestational age has been described previously. The association of body weight and urine output has been observed in human neonates. Our goal was to assess the correlation of the amniotic fluid index (AFI) with estimated fetal weight (EFW) in the third trimester. METHODS: We conducted a retrospective observational study on 426 pregnant women with singleton gestations who were referred to our unit for sonographic evaluation in the third trimester. The AFI, EFW, and EFW percentile corrected for gestational age were evaluated. The sonographic examinations were stratified into 3 gestational age categories: 28 through 33.9 weeks, 34 through 37.9 weeks, and 38 weeks and later. Maternal and fetal outcome variables were collected from medical records. Linear regression, Mann-Whitney U, and Kruskal-Wallis tests were used for statistical analysis. RESULTS: There was no significant relationship between the AFI and EFW in the entire group of patients (R = 0.08; P = .096). There was a significant relationship between the AFI and EFW after 38 weeks' gestation (R = 0.30; P = .003). In addition, in female fetuses the EFW percentile correlated with higher AFI values at all gestational ages (R = 0.31; P < .001); this, however, was not observed in male fetuses. CONCLUSIONS: There is no relationship between the AFI and EFW during the third trimester, although a positive relationship between the AFI and EFW was noted late in gestation. In pregnancies with female fetuses, the AFI was positively associated with EFW percentile before 38 weeks' gestation.     

Rapid determination of alpha-fetoprotein in amniotic fluid using an automated immunoturbidimetric technique

A rapid and precise immunoturbidimetric assay for the measurement of alpha-fetoprotein in amniotic liquor has been developed. The method is an 'end-point' technique without blank correction since non-specific turbidity does not occur with amniotic liquor. The assay is able to distinguish 4 mg/l from zero and is unaffected by gross blood staining of the liquor. The protocol requires a duplicate analysis of the liquor to detect high levels of alpha-fetoprotein.     

Acid glycosidase and arylsulfatase activities of human cerebrospinal fluid as measured by concanavalin A-sepharose affinity chromatography.

An affinity chromatographic method using concanavalin A-Sepharose is described for the determination of N-acetyl-beta-D-glucosaminidase, arylsulfatase. alpha-L-Fucosidase and alpha-D-mannosidase activities in the human cerebrospinal fluid. By this method (starting with 12 to 20 ml samples of cerebrospinal fluid) the above enzymes could be obtained in a concentrated form and their activities could be determined within incubation periods of 30 min to 1 h under the assay conditions described. The pH optima of the enzymes were in the range of pH 4 to 5. About 80% of the total cerebrospinal fluid N-acetyl-beta-D-glucosaminidase was found to be the A form by DEAE-Sephadex A-50 chromatography. About 60% of the total arylsulfatase was also found to be the A form. Determination of these enzyme activities in a few samples of human cerebrospinal fluid indicated a rough proportionality between the enzyme activities and the protein concentration in the cerebrospinal fluid.     

Current perspectives in assessment of fetal pulmonary surfactant status with amniotic fluid

In recent years, improvements in analytical methodology and clinical management of maternal-fetal diseases have altered the understanding of data from amniotic fluid analysis. Delays in phospholipid production or lung function are not currently reported in maternal diabetes. Fetal lung function following glucocorticoid therapy or premature membrane rupture is uncoupled from amniotic fluid phospholipid concentrations, which do not have the usual significance in these circumstances. Phosphatidylglycerol (PG) is present prior to the usual time it is detected by thin layer chromatography (TLC) methods, which vary in sensitivity for PG. Consequently, the significance of its "absence" is highly varied. These observations are discussed in light of the earlier methods and data, along with new perceptions of the functions of the individual phospholipids and apoproteins, the regulatory mechanism of surfactant production, and the relationship of amniotic fluid components to neonatal lung function.     

Determination of amniotic fluid acetylcholinesterase activity in the antenatal diagnosis of foetal malformations: the first ten years

The concentration of amniotic fluid acetylcholinesterase activity is elevated in cases of foetal open malformations, the levels being higher in cases of open neural tube defects than in cases of abdominal wall defects. Determination of amniotic fluid acetylcholinesterase activity is an established procedure for the antenatal diagnosis of foetal neural tube defects. Performance data, technical advantages and limitations for three procedures for the determination of acetylcholinesterase activity are reviewed in this paper: an immunoassay, a gel electrophoretic procedure and a spectrophotometric procedure. An immunoassay using the monoclonal antibody 4F19 and the gel electrophoretic procedure show nearly identical diagnostic performances, with detection rates for open spina bifida close to 100% and overall false positive rates of approximately 0.2%. The spectrophotometric procedure is not suitable for the antenatal diagnosis of foetal open neural tube defects and abdominal wall defects. It is possible to distinguish open neural tube defects from abdominal wall defects by determination of the ratio of acetylcholinesterase activity to butyrylcholinesterase activity, either by combining the 4F19 immunoassay with a butyrylcholinesterase immunoassay or by gel electrophoresis followed by densitometry, on samples that display elevated levels of acetylcholinesterase activity.     

胎儿手畸形的产前超声诊断

目的 探讨产前二维及三维超声在胎儿手畸形分类中的作用.方法 回顾性分析14例胎儿严重手畸形病例的产前声像图特征,结合家谱分析、染色体核型分析与引产后尸检病理结果等进行形态学分类.结果 孕16～28周共检出严重手畸形胎儿14例,其中10例为双手同时受累,8例双侧畸形形态相同.13例合并其他超声异常表现.按畸形形态分为3类:手腕部姿势异常9例,3例合并桡骨完全缺失、手向桡侧偏斜,6例手向掌侧偏斜,包括家族遗传性先天性多发性关节弯曲畸形-远端1型、羊膜带综合征、体蒂异常、18-三体、四肢短小畸形各1例.手(指)缺如畸形3例,1例单纯性单侧手缺如,1例为5个手指缺如合并多囊性肾发育不良,1例为裂手裂足畸形.手指重叠畸形4例,3例为18-三体,2例合并手腕部姿势异常.结论 产前二维及三维超声在严重胎儿手畸形的检出、形态学分析和分类诊断等方面有重要作用.     

胎儿颅脑畸形的产前超声诊断

目的探讨胎儿颅脑畸形的超声表现及产前超声对颅脑畸形的诊断价值。方法回顾性分析59例(包括误诊的3例)颅脑畸形胎儿的超声表现及临床资料。结果59例颅脑畸形包含12种类型,单纯颅脑畸形35例,24例合并其他畸形,25例羊水过多。结论胎儿颅脑畸形种类繁多,大部分畸形可在产前超声检查时发现,认识各种颅脑畸形的声像图特征对诊断及鉴别诊断至关重要。     

Time-resolved immunofluorometric assay of alpha-fetoprotein in serum and amniotic fluid, with a novel detection system

We describe a new "sandwich"-type nonisotopic immunoassay of alpha-fetoprotein (AFP) in serum and amniotic fluid. In the assay, AFP binds to a monoclonal antibody immobilized in a microtiter well and to a polyclonal soluble biotinylated antibody. A fluorescent product is created on the solid-phase after adding streptavidin labeled with a new Eu3+ chelate, 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA), and excess Eu3+. The fluorescent complex, monoclonal antibody-AFP-polyclonal antibody-biotin-streptavidin-BCPDA-Eu3+, is quantified by nitrogen laser excitation at 337.1 nm, the emission at 615 nm being monitored in an especially designed gated fluorometer working in a time-resolved mode. This assay of AFP has a broad dynamic range (up to 1 mg/L), and is precise and accurate. The detection limit is approximately 0.1 microgram/L. Results agree well with those obtained by established techniques.     

超声诊断和鉴别诊断胎儿颅后窝池畸形

胎儿颅后窝池畸形主要包括Dandy-Walker综合征、Blake囊肿和颅后窝蛛网膜囊肿,其中Dandy-Walker综合征又包括典型的Dandy-Walker畸形、小脑蚓部发育不良(Dandy-Walker变异型)及巨大枕大池。各种颅后窝池畸形的预后差异较大,约90%Blake囊肿和巨大枕大池胎儿神经系统发育正常,而Dandy-Walker畸形和小脑蚓部发育不良胎儿中,约50%伴神经系统发育异常。各类型颅后窝畸形超声表现相似,鉴别诊断困难,应用二维超声与三维超声相结合,可获得理想的胎儿头部正中矢状切面,对鉴别诊断胎儿颅后窝池畸形帮助极大。     

Gel electrophoresis of amniotic fluid acetylcholinesterase as an aid to the prenatal diagnosis of fetal defects

The presence of absence of a specific acetylcholinesterase (AChE) band was determined by polyacrylamide gel electrophoresis on 272 second trimester amniotic fluid samples. The AChE band was absent from 176 normal samples, including seven which had been scored as false positives by alphafetoprotein (AFP) assay. It was present in all 30 samples from open neural tube defects, of which four had been scored as false negatives by AFP assay. In remaining 66 pregnancies with abnormal outcome, an AChE band was in general present when AFP was raised and absent when it was normal. However, all six cases of congenital nephrosis had raised AFP and no AChE band, while two of 30 pregnancies ending in spontaneous abortion had an AChE band and normal AFP. These results suggest that AChE electrophoresis is a valuable confirmatory technique for the early prenatal diagnosis of fetal abnormalities.     

Tetranectin in amniotic fluid, maternal serum and fetal fluids

The concentration of the newly discovered protein tetranectin has been measured in different fetal and maternal compartments. In amniotic fluid a significant, positive correlation between the tetranectin concentration and gestational age was found (a mean of 0.2 mg l-1 at week 14 to a mean of 0.5 mg l-1 at week 21). In maternal serum a slight negative correlation was found between tetranectin concentration and gestational week (a mean of 6.17 mg l-1 at week 14 to a mean of 5.79 mg l-1 at week 21). In-term cord blood collected at delivery a mean level of 6.0 mg l-1 was found, and no difference was found between arterial- and venous-blood tetranectin concentration. In fetal serum the overall mean level was 2.6 mg l-1 and a significant positive correlation between tetranectin concentration and gestational age was found. The mean level was 1.1 mg l-1 in fetal cerebrospinal fluid and no correlation to gestational age was found. Fetal tetranectin may, therefore, be correlated to fetal maturation.