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Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Among 93 acetylcholinesterase determinations performed on amniotic fluid samples from pregnancies at 11-14 weeks' gestation, five unexplained false-positive results were observed. In four of the five cases, the ratio of acetylcholinesterase to pseudocholinesterase was compatible with that observed in association with open neural tube defects in later gestation. In contrast, no false-positive results were noted among 951 acetylcholinesterase determinations performed on samples from women at 15-20 weeks' gestation. Repeat amniocentesis was performed several weeks after the first procedure in four of the five cases of early amniocentesis and false-positive results; in each case, the acetylcholinesterase was negative on the second sample. All four pregnancies had a normal outcome. In the remaining case, trisomy 21 was diagnosed in the fetus and the pregnancy was terminated. Positive acetylcholinesterase results should be interpreted cautiously in samples from early amniocentesis, especially when the amniotic fluid alpha-fetoprotein level is not markedly elevated. The acetylcholinesterase-to-pseudocholinesterase ratio is not useful in identifying fetal neural tube defects before 15 weeks' gestation. Repeat amniocentesis may help in determining the significance of a positive acetylcholinesterase result from early amniocentesis when no fetal defect is identified by ultrasonography.
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PMID:False-positive acetylcholinesterase with early amniocentesis. 279 38

Using a monoclonal antibody to bromodeoxyuridine, we studied the cell kinetics of human hepatocellular carcinoma, liver cirrhosis, chronic active hepatitis and alcoholic liver fibrosis. Specimens were taken either by biopsy or surgery and immediately incubated with 0.1% bromodeoxyuridine solution at 37 degrees C for 45 min. After in vitro labeling, the bromodeoxyuridine taken up by the nuclei of S-phase cells was determined by the avidin-biotin-peroxidase complex method, using an anti-bromodeoxyuridine monoclonal antibody as the first antibody. The number of positive nuclei in 1,000 hepatic cells was counted, and the bromodeoxyuridine labeling index was expressed per thousand. The mean bromodeoxyuridine labeling index +/- S.D. of the cancerous portion of hepatocellular carcinoma, the noncancerous portion of hepatocellular carcinoma, liver cirrhosis, chronic active hepatitis and alcoholic liver fibrosis were 64.1 +/- 31.3, 33.6 +/- 14.4, 23.2 +/- 20.8, 9.1 +/- 6.1 and 21.6 +/- 13.0, respectively. The mean bromodeoxyuridine labeling index of the hepatocellular carcinoma cancerous portion was statistically higher than that of any other group. There was no statistical difference by the t test or the Wilcoxon test between the noncancerous portion of hepatocellular carcinoma and liver cirrhosis, and these two groups were proved interdependent by chi 2 test (Fisher's exact test), whether they were subdivided by bromodeoxyuridine labeling index greater than or equal to 10 or not. Bromodeoxyuridine labeling index was not significantly correlated with the usual biochemical parameters such as serum AST, ALT, gamma-GTP, alkaline phosphatase, lactate dehydrogenase, cholinesterase, albumin, and alpha-fetoprotein.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:S-phase cells in diseased human liver determined by an in vitro BrdU-anti-BrdU method. 284 68

Elevated amniotic fluid alpha-fetoprotein and presence of acetylcholinesterase were detected in a pregnancy that resulted in an infant whose only abnormality was a hydrocele. Although these amniotic fluid findings are usually indicative of a serious fetal anomaly, our report indicates that this is not always the case.
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PMID:Elevated alpha-fetoprotein and acetylcholinesterase associated with hydrocele. 608 26

Fifteen centres collaborated in a study to determine the value of amniotic fluid acetyl cholinesterase (AChE) electrophoresis in the diagnosis of fetal open neural-tube defects (NTDs) between 13 and 24 weeks of gestation among women with positive amniotic fluid alpha-fetoprotein (AFP) results. Pregnancies with positive amniotic fluid AFP results were identified from about 34 000 tested; on average they had values greater than the 99.6th percentile for non-NTD pregnancies. Amniotic fluid samples were available from 1099 pregnancies with positive AFP results, and the percentages which yielded positive AChE results were as follows: anencephaly 99.6% (476/478); open spina bifida 99.4% (333/335); non-NTD pregnancies (i) without serious malformation and not ending in miscarriage 6% (8/125), (ii) without serious malformation but ending in miscarriage 47% (34/73), (iii) exomphalos 75% (47/63), (iv) congenital nephrosis 0% (0/11), (v) other serious malformations 50% (7/14). The gel-AChE test was thus found to be very effective when applied to amniotic fluid samples with positive AFP results, substantially reducing the number of false positives with only a very small loss in the detection of open neural-tube defects. Among women with positive amniotic fluid AFP results, the risk of having a fetus with an open NTD compared to having one without a serious malformation or a miscarriage is raised about 16-fold if the AchE test is also positive. The actual risk will depend on the birth prevalence and the reason for amniocentesis. For example, in the U.K. the risk of open spina bifida (expressed as an odds ratio) when both the amniotic fluid AFP result and the gel AChE results are positive would be as follows for women referred for amniocentesis in different categories; approximately 288:1 for those referred because of single raised serum AFP level (greater than or equal to 2.5 time the normal median at 16-18 weeks of gestation, 80:1 for women referred because of having previously had an infant with an NTD, and 8:1 for women referred for other reasons. It the amniotic fluid sample is stained with blood which is mainly fetal in origin, the corresponding odds are much lower (36:1, 10:1, and 1:1 respectively): if it is not blood-stained or is stained mainly with maternal blood, they are higher (954:1, 265:1, and 26:1 respectively).
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PMID:Amniotic fluid acetylcholinesterase electrophoresis as a secondary test in the diagnosis of anencephaly and open spina bifida in early pregnancy. Report of the Collaborative acetylcholinesterase Study. 611 8

Amniotic fluid total cholinesterase (ChE) and acetylcholinesterase (AChE) activities have been measured in 404 pregnancies without fetal malformation and 79 pregnancies associated with open neural-tube defects (NTDs). Neither measurement, either alone or in combination, gave complete separation of the two groups. However, measurement of ChE can be used to assess the probability that a woman is carrying a fetus with an open NTD. Since ChE can be measured within 15 minutes and shows at least 70% of women selected for amniocentesis by serum alpha-fetoprotein screening to have a less than 1 in 100 chance of carrying a fetus with an open NTD, we suggest that this test may be used in an amniocentesis clinic both to reassure women with normal pregnancies and to select probable abnormalities for immediate further investigation.
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PMID:Amniotic fluid cholinesterase measurement as a rapid method for the exclusion of fetal neural tube defects. 611 9

Total cholinesterase activity in amniotic fluid obtained from 150 fetuses was measured. Elevated values were found in 94% of samples from fetuses known to have neural tube defects (spina bifida, anencephaly) when compared to nonbloody samples from normal fetuses. Contamination of amniotic fluid with blood was observed to elevate total cholinesterase activity in some, but not all, such specimens. Total cholinesterase activity did not vary with gestational age between 15 and 24 weeks. These data were compared to our large alpha-fetoprotein (AFP) assay experience used for the prenatal detection of neural tube defects. We concluded that the assay of total cholinesterase activity in amniotic fluid could be a useful adjunct to the AFP assay, especially in those samples contaminated with blood.
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PMID:Prenatal diagnosis of neural tube defects. V. The value of amniotic fluid cholinesterase studies. 615 84

The qualitative assay of the cholinesterases (ChE) in amniotic fluid on polyacrylamide gel gave a single major band (cholinesterase) in all samples from normal pregnancies, and two major bands (cholinesterase and acetylcholinesterase) in all cases from fetuses with open neural tube defects. Five fluids which were true false positive on alpha-fetoprotein (AFP) assay (elevated AFP in a clear fluid but normal fetus) had a single band, and two fluids which were false negative on AFP testing (normal AFP but spina bifida fetus) had two bands. The second 'diagnostic' ChE band sometimes occurred, together with other extra bands, in some fluids which were very severely contaminated by maternal or fetal blood, but in four of six fluids from normal fetuses where fetal blood staining was sufficient to cause the AFP to be elevated, there was only one ChE band. It is suggested that the qualitative assay of ChE should be performed in addition to AFP in the prenatal diagnosis of neural tube defects.
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PMID:Polyacrylamide gel electrophoresis of amniotic fluid cholinesterases: a good prenatal test for neural tube defects. 615 18

A single-blind study involving amniotic-fluid samples from 214 pregnancies of known outcome confirms that an electrophoretically distinct isoenzyme of acetylcholinesterase is associated with fetal open neural tube defects. Furthermore, only one of 13 amniotic-fluid samples with false-positive results for alpha-fetoprotein showed the characteristic isoenzyme, indicating that qualitative acetylcholinesterase assessment can decrease the proportion of false positives from the alpha-fetoprotein assay. We have also identified this characteristic isoenzyme in amniotic fluids from pregnancies in which other serious fetal defects occurred. A detailed electrophoresis protocol for identifying this characteristic isoenzyme is described.
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PMID:Acetylcholinesterase and fetal malformations: modified qualitative technique for diagnosis of neural tube defects. 616 Sep 26

Principle and logistic of alpha-1-fetoprotein (AFP-) screening is explained. It is estimated that approximately 2% of women pregnant for 16 to 18 weeks have elevated circulating AFP. By again measuring serum-AFP and by ultrasound examination such abnormal values can be explained by multiple pregnancies, wrongly estimated duration of pregnancy, abortus, etc, in approximately half of the cases. In 0.8 to 1% of all pregnant women the high-serum-AFP remains unexplained and an amniocentesis is indicated. An elevated amniotic AFP (0.1 to 0.2% of all pregnant women) strongly points to a fetus with an open neural tube defect. By also measuring amniotic acetylcholinesterase, this diagnosis can be distinguished from other fetal abnormalities associated with high amniotic AFP, such as omphalocele.
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PMID:[Alpha-1-fetoprotein screening--development and problems]. 617 Nov 16

The most reliable tool at present for the prenatal detection of open neural tube defects is the amniotic fluid alpha-fetoprotein assay. Nevertheless its nonspecificity and false-positive results produced by fetal blood admixture and other less well-defined causes have spurred the search for a more specific test. Increased amniotic fluid acetylcholinesterase activity has been reported in association with open neural tube defects. The authors have assayed acetylcholinesterase in second-trimester amniotic fluid samples with previously determined alpha-fetoprotein values from 200 pregnancies with 96.5% of the outcomes known. These pregnancies were selected because of known fetal abnormalities or difficulties in prenatal diagnosis. High alpha-fetoprotein and acetylcholinesterase activity was detected in all 66 cases of open neural tube defects. The authors were able to reclassify correctly 89% of normal pregnancies with spuriously high alpha-fetoprotein by demonstrating no acetylcholinesterase band after slab gel in electrophoresis. Nine cases with a normal outcome but high alpha-fetoprotein values and acetylcholinesterase activity constitute the remaining false-positive results. Notwithstanding the false-positive results, which may have been due to undetected fetal blood admixture, the acetylcholinesterase gel electrophoresis assay is clearly a valuable adjunctive test to the alpha-fetoprotein assay for the prenatal detection of neural tube defects. Although no specific for open neural tube defects, acetylcholinesterase analysis by gel electrophoresis of amniotic fluid is significantly less influenced by fetal blood than is alpha-fetoprotein and, furthermore, may prove as reliable a diagnostic test for open neural tube defect.
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PMID:Prenatal diagnosis of open neural tube defects using the amniotic fluid acetylcholinesterase assay. 617 22


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