Positive Acetylcholinesterase Research Articles

Isoelectric focusing pattern of human amniotic fluid α‐fetoprotein

Isoelectric focusing (IEF) of amniotic fluid alpha-fetoprotein (AFP) in thin-layer polyacrylamide gels containing 8 M urea followed by immunoblotting reveals at least nine bands, band I lying next to the cathode. Compared with 298 amniotic fluid samples from normal pregnancies, we found that the density of band V was increased in seven cases of fetal death. In 16 amniotic fluid samples from pregnancies with open neural tube defects (ONTD), band V disappeared or was markedly decreased. In seven cases with elevated AFP and positive acetylcholinesterase (AChE) due to contamination with fetal blood, no difference in pattern was observed compared with samples from normal pregnancies. It is suggested that IEF of AFP and subsequent immunoblotting are an apparently diagnostic test for ONTD and intrauterine fetal death (IUFD).

Risks associated with an elevated amniotic fluid α‐fetoprotein level

Two and two-tenths percent of 85,000 consecutive amniotic fluid (AF) samples had alpha-fetoprotein (AFP) levels greater than or equal to 2.0 MoM. Half measured 2.0-2.4 MoM, and 93% had a normal outcome. Sixty-seven percent of those with higher levels had abnormalities. A positive acetylcholinesterase (AChE) increased the risk from 67% for levels between 2.0 and 2.4 MoM to 99% at greater than or equal to 5.0 MoMs. After a normal ultrasound and chromosome studies, the risk for a fetal abnormality was 1% for AF AFP measuring 2.0-2.4 MoM and 3% for higher levels.

A Co-Twin Fetus Papyraceus as a Cause of Elevated AFP and Acetylcholinesterase in the Amniotic Fluid of the Normal Co-Twin

An elevated amniotic fluid alpha-fetoprotein (AF-AFP) level together with a positive acetylcholinesterase (AChE) band is strongly predictive of neural tube defect (NTD) in the fetus. We report such results in a pregnancy in which the fetus was found to be normal after termination. Among the placental fragments was found a sac containing a prenatally undetected co-twin fetus papyraceus. We suggest that pregnant women with such laboratory results but lacking sonographic evidence of NTD should have a high-level untrasonographic investigation, as well as a thorough pathologic examination of both placenta and fetus in cases of termination.

Localization of acetylcholinesterase positive neurons and substance P and enkephalin positive fibers by histochemistry and immunohistochemistry in the sympathetic intermediate zone of the developing human spinal cord

Localization of acetylcholinesterase positive neurons and substance P and enkephalin fibers were studied by histochemistry and immunohistochemistry in the intermediate sympathetic zone of the spinal cords of 39 human embryos/fetuses from gestation ages five to 40 weeks. Acetylcholinesterase positive neurons were observed in the nucleus intermediolateralis pars principalis as early as the fifth week of gestation. By the ninth to 13th weeks of gestation, positive neurons were also seen in the nuclei intermedialis pars funicularis, intercalatus spinalis and intercalatus pars paraependymalis. Increase in amount of these positive acetylcholinesterase neurons was demonstrated till term. Substance P and enkephalin fibers were initially observed by the eighth gestation week in the intermediolaterlis pars principalis nucleus and positive fibers were then detected in the nucleus intermedialis pars funicularis as well as the nucleus intercalatus spinalis by the 14th week of gestation. By the 26th week of gestation, all the major nuclei intermediolateralis par principalis, intermedialis pars funicularis, intercalatus spinalis and intercalatus pars paraependymalis has substance P and enkephalin fibers. Initial demonstration of acetylcholinesterase positive neurons appeared to be at an earlier stage than that of our substance P and enkephalin positive fibers.

Alpha‐fetoprotein and acetylcholinesterase in twins discordant for neural tube defect

Twins concordant for elevated alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) and discordant for neural tube defect (NTD) and sex are reported. A literature review reveals instances of termination of twin pregnancies with one normal and one abnormal fetus, partly based on concordant high AFP and positive AChE (although discordant on ultrasound examination). The levels of AFP and AChE in twin pregnancies are probably a function of the number of layers of fetal membranes separating twin sacs; dichorionic, diamniotic membranes allow transfer of AFP; monochorionic, diamniotic membranes allow transfer of both AFP and AChE. Cautious interpretation of biochemical findings and reliance on high resolution ultrasonography are suggested.

Amniotic fluid alpha‐fetoprotein and acetylcholinesterase measurements in pregnancies associated with gastroschisis

In this study we define for the first time the distribution of alpha-fetoprotein levels and acetylcholinesterase ratios in amniotic fluid samples associated with fetal gastroschisis. Elevated alpha-fetoprotein levels and positive acetylcholinesterase measurements are found in virtually all cases, indicating that these combined measurements are highly reliable in detecting this lesion.

Amniotic fluid acetylcholinesterase ratios in prenatal diagnosis of fetal abnormalities

This study examined 141 pregnancies with acetylcholinesterase in the amniotic fluid to determine if an acetylcholinesterase/pseudocholinesterase ratio cutoff could be set to distinguish between neural tube defects, ventral wall defects, other fetal defects, and pregnancy problems. Amniotic fluid specimens with positive or faintly positive acetylcholinesterase bands were studied. They were scanned and analyzed for the acetylcholinesterase/pseudocholinesterase ratio. In 62 of 65 fluid samples from open neural tube defects, the acetylcholinesterase/pseudocholinesterase ratios were > 0.13. All cases with ventral wall defects (n = 29), fetal blood contamination (n = 16), or fetal ascites (n = 2) had acetylcholinesterase/pseudocholinesterase ratios < 0.13. Samples of cystic hygroma fluid (n = 10) had acetylcholinesterase/pseudocholinesterase ratios > 0.13. Two patients with fetal teratomas had intermediate values. All patients with normal outcomes but positive acetylcholinesterase had ratios of < 0.12. Acetylcholinesterase/pseudocholinesterase ratios are a valuable part of a prenatal program to accurately diagnose fetal abnormalities.

Amniotic Fluid Alpha-Fetoprotein Levels in the Differential Diagnosis of Cystic Hygroma

In 7 second trimester pregnancies ultrasound (US) demonstrated cystic hygroma colli (CHC); amniocentesis was performed in 6 patients. In the 7th patient, because of oligohydramnios, the fluid for karyotype was aspirated from the CHC. Five pregnancies had been referred secondary to abnormalities on US and 2 others because of low maternal serum alpha-fetoprotein (MSAFP). Four karyotypes were abnormal (45,X;47,XX+21; 47,XY+21; 46,XX/45,X), and 3 had normal karyotypes. Amniotic fluid alpha-fetoprotein (AFAFP) was normal in 4 pregnancies and low in 2 (0.09 MOM, 0.41 MOM). Of 2 pregnancies with trisomy 21 one had been referred for low MSAFP. In 2 pregnancies with normal karyotypes, US findings at early gestational age (14-17 weeks) of small, nonseptated, bilateral CHC disappeared during pregnancy; these women delivered normal, term babies. Most prenatally diagnosed CHC are not in fetuses with Turner syndrome. With a normal karyotype and CHC as the only finding on early US in utero, normal neonatal survival is possible. AFAFP is not elevated in pregnancies with CHC. If AFAFP is elevated with a positive acetylcholinesterase, such results may suggest that the CHC was inadvertently aspirated.

Histochemical and cytochemical localization of acetylcholinesterase in the cerebellar cortex of the chicken.

The localization of acetylcholinesterase (AChE) was studied in the cerebellar cortex of the crossbred trembler chickens by means of histo- and cytochemical methods. No essential differences between the crossbred normal and the crossbred trembler chickens were observed. The common results were as follows: Under a light microscope AChE activity was predominantly evident in the molecular layer, and secondly in the granular layer. AChE was ultrastructurally distributed principally in the cisternae of rough endoplasmic reticulum (ER) and in a part of nuclear envelope of the Purkinje, the Golgi and some of the basket and granule cells, and in a portion of the sacculus of the Golgi apparatus of the Purkinje cell only. In dendrites and the initial axon of the Purkinje cells the smooth ER also showed AChE activity. Although dendritic terminals of the Golgi cells contained AChE reaction products, the axon terminal did not. Some of the afferent terminal fibers forming the cerebellar glomerulus exhibited weakly a positive AChE reaction, while others in the vicinity did not show any AChE activity at all. However, the enzyme reaction product was localized in the intercellular spaces between a presynaptic afferent terminal and the postsynaptic granule cell dendritic terminals in the glomerulus. In addition, AChE activity was found in the form of spots in the intercellular spaces of both molecular and granular layers.

Biamnial elevated alpha‐fetoprotein and positive acetylcholinesterase in twins, one with anencephaly

Anencephaly in twin B was accompanied by elevated amniotic fluid alpha-fetoprotein (AFP) and a positive acetylcholinesterase (AChE) band on gel electrophoresis in both twin sacs, although twin A was normal. AChE results did not help distinguish the false positive AFP in this set of twins, implying that AChE may diffuse transamniotically as has been previously postulated for AFP. In light of the low concordance rate for neural tube defects in twins, patient counselling in this situation must include the information that AFP and AChE may be falsely elevated in normal twin when the other twin has a neural tube defect.

Positive amniotic fluid acetylcholinesterase: Distinguishing between open spina bifida and ventral wall defects

The ratio of amniotic fluid acetylcholinesterase to pseudocholinesterase was determined by scanning densitometry on 43 amniotic fluid samples with positive acetylcholinesterase associated with open fetal defects. The mean ratio was 0.587 (range 0.204 to 0.979) in 21 amniotic fluid samples from pregnancies affected with open spina bifida and 0.052 (range 0.026 to 0.075) in 12 pregnancies affected with ventral wall defects. These data confirm previous observations and indicate that scanning densitometry of electrophoretic gels is a useful method for distinguishing between open spina bifida and ventral wall defects in the fetus.

The relationship of saccular efferent neurons to the superior olive in the eel, Anguilla anguilla

In the eel, horseradish peroxidase was applied to the saccular ramus of the eighth nerve to label auditory efferent neurons and was injected into the torus semicircularis to identify the superior olive. Efferent somata cluster close to the lateral lemniscus. The superior olive is also associated with the lateral lemniscus and is situated just rostral to and contiguous with the efferent population. Efferent cells can be distinguished from superior olivary neurons because of their larger size and their positive acetylcholinesterase reaction. It appears that in these fishes, as in mammals, auditory efferent neurons are closely associated with the superior olive.

Persistently elevated AFP and AChE in amniotic fluid from a normal fetus following demise of its twin

Intrauterine fetal demise (IUFD) in one of twins at 12 weeks of gestation was accompanied by markedly elevated maternal serum alpha-fetoprotein (AFP) at 17 and 18 weeks. Amniotic fluid AFP from the healthy surviving twin's sac at 18.5 and 23 weeks was also greatly increased along with a positive acetylcholinesterase (AChE) band. Persistently elevated AFP and positive AChE so long after fetal demise--6.5 and 11 weeks post IUFD--has not, to our knowledge, been previously described. In similar cases, high level ultrasound and careful placental examination at birth should be utilized to search for fetal abnormalities or multiple pregnancy with IUFD.

Pregnancy outcome in relation to the concentration and concanavalin A reactivity of α-fetoprotein and the presence of acetylcholinesterase activity in amniotic fluid

SummaryReactivity of α-fetoprotein with concanavalin A and detection of acetylcholinesterase activity in amniotic fluid were evaluated as secondary tests for fetal neural tube defect in pregnancies with a high or a low risk of such a defect. A retrospective study was done on 72 fluids and a prospective study on selected samples from 342 fluids in all of which total a-fetoprotein had been measured. Both additional tests were useful in discriminating between normal and abnormal outcome in pregnancies with raised total α-fetoprotein.In the prospective series there were four false positive total α-fetoprotein tests and one false positive acetylcholinesterase test in viable pregnancies without fetal abnormality. None of the three tests was falsely negative for fetal neural tube defect.Specific abnormality and other poor pregnancy outcomes were much commoner when amniocentesis followed from high maternal serum α-fetoprotein than any other indication.

Predictive value of amniotic acetylcholinesterase analysis in the diagnosis of fetal abnormality in 3700 pregnancies.

The value of acetylcholinesterase (AChE) analysis as an adjunctive test to amniotic alpha fetoprotein (amAFP) for the diagnosis of fetal abnormality has been investigated in a series of 3785 amniotic fluid samples. Quantitative analysis of AChE performed retrospectively on a selected group of 541 amniotic fluid samples failed to discriminate between normal and open neural tube defect pregnancies. Qualitative analysis of AChE by polyacrylamide gel (PAG) electrophoresis in the same series of 541 fluids correctly identified 251 of the 255 pregnancies with open neural tube defect and 29 of the 31 pregnancies with false positive amAFP results. The failure of the test to diagnose 4 cases of open neural tube defect was probably attributable to the age and condition of the stored AF samples. Routine diagnostic testing of AChE isoenzymes in a further 3244 AF samples successfully identified all 170 cases of open neural tube defect and 20 cases with other fetal defects. Thirteen fluids gave false positive AChE results (0.4 per cent) compared to 59 of the series in which there were false positive amAFP results (1.8 per cent). Six of the 13 false positive AChE cases had AChE bands of low intensity which would not be regarded as diagnostic of fetal abnormality, and in five the AChE band may have been the result of significant blood contamination. False positive AChE results contributed to the decision to abort three apparently normal fetuses, but a normal AChE result undoubtedly helped to save a number of pregnancies with false positive amAFP results. Our experience suggests that repeating the amniocentesis may help in resolving the rare diagnostic difficulty of a positive AChE result with or without an elevated amAFP in the absence of ultrasound evidence of fetal abnormality, particularly where there is blood contamination of the amniotic fluid sample.

Histochemical confirmation of the acetylcholinesterase-activity in rectal suction biopsy from neonates with Hirschsprung's disease.

Proliferating patterns of acetylcholinesterase (AChE) positive nerve fibres were investigated in 23 neonates with Hirschsprung's disease. All subjects were separated into three groups, according to age. In group A (0-10 days old) adn groups B (11-20 days old, no increase in AChE positive nerve fibres was evidenced in the lamina propria mucosae, whereas 7 out of 9 cases in group C (21-28 days old) showed a moderate or marked increase in AChE positive nerve fibres in the lamina propria mucosae. A typical pattern of this proliferation up to the lamina propria mucosae was seen in 30.4% only of all cases in the series, and was limited to group C, where the positive AChE reaction from the submucosa to the muscularis mucosae (including the submucosa only), the rate was 91.3%. Re-examination was preformed in 14 cases over sthe neonatal period. All showed a positive AChE reaction up to the lamina propria mucosae. Suction biopsy specimen from neonates is sometimes inadequate with respect to the lack of inclusion of the muscularis mucosae and submucosa, as a result of a weakly negative pressure by suction. The normal reactions of AChE activity in the lamina propria mucosae do not exclude Hirschsprung's disease in neonates. Therefore, when a histochemical diagnosis of Hirschsprung's disease using rectal suction biopsy for staining of AChE activity is required in the neonatal period, the diagnosis is safe and relatively easy at least over three weeks of age as mentioned above.

Progressive partial lipodystrophy in association with intrauterine death and growth retardation

Atresia and fistula of the esophagus are among the most common congenital anomalies, but their prenatal diagnosis is only rarely achieved by ultrasonography, amniofetography or cu-fetoprotein (AFP) determination. Intra-amniotic injection of radiopaque dye into the amniotic cavity and radiologic imaging of the fetal gastrointestinal tract have been used most frequently in pregnancies with hydramnios and the sonographic finding of absent fluid in the gastrointestinal tract. It is known, however, that partial passage of the x-ray contrast medium into the fetal intestine in cases of esophageal atresia can occur, thus giving rise to a false negative diagnosis. A simple and reliable biochemical marker present in the amniotic fluid would be of great practical importance. Amniotic fluid acetylcholinesterase as a possible marker for the prenatal diagnosis of esophageal atresia was recently suggested by a case report of a pregnancy characterized by fetal esophageal atresia, polyhydramnios, ambiguous amniofetography, a normal amniotic fluid AFP concentration, and an elevated amniotic fluid acetylcholinesterase level.’ To test the reliability of this proposed marker we retrospectively examined samples of clear amniotic fluid obtained at second-trimester amniocenteses of three pregnancies, each of which proved to be complicated by upper gastrointestinal atresia. Two of these cases had a positive acetylcholinesterase band on gel electrophoresis and normal AFP concentrations. In one case of an esophageal atresia with tracheoesophageal fistula a normal AFP value and no specific acetylcholinesterase band was found on electrophoresis.

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

Fifteen centres collaborated in a study to determine the value of amniotic fluid acetylcholinesterase (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

Histochemical and ultrastructural study of the nervous elements in the pineal organ of the eel, Anuilla anguilla.

The pineal organ of the eel, Anguilla anguilla was studied light-and electron-microscopically. The tissue consists predominantly of glia-like supporting cells and photoreceptor-like sensory cells, which establish synaptic contacts with pineal nerve cells. Histochemically, a positive acetylcholinesterase (AchE) reaction can be observed in the perinuclear cytoplasm of the nerve cells and in the inner segments of the photoreceptor cells. Based on the intensity of the AchE reaction and the dimensions of the perikarya, at least two different types of nerve cells can be distinguished: type I with a large, intensely staining perikaryon, located mainly in the pineal end-vesicle, and type II with a smaller, moderately staining perikaryon, found predominantly in the pineal stalk. The total number of AchE-positive neurons in the pineal organ is approximately 370. About 140 neurons are found in the end-vesicle and 230 in the pineal stalk. Electron microscopical observations of transverse sections through the proximal-most part of the pineal stalk near the subcommissural organ in the diencephalic roof reveal the presence of approximately 530 nerve fibers was found distally from the site of transection. Consequently, it is assumed that the majority of the pineal-tract fibers is afferent (pinealofugal) and that the difference between the number of AchE-positive perikarya and the number of pineal-tract fibers in mainly caused by the presence of AchE-negative perikarya. It is possible, however, that in the proximal-most part of the stalk, inside the diencephalic roof, nerve fibers from other parts of the brain establish synaptic contacts with pineal elements.

Mammalian central nervous system axolemma: histochemical evidence for axonal plasma membrane origin of bovine and rat axolemma-enriched membrane fractions

Purified myelinated axons were isolated from fresh bovine corpus callosum and rat brainstem and osmotically shocked to strip myelin and axolemma from axon filaments. Two axolemma-enriched fractions, myelin, and a pellet of myelin-free axons were harvested by discontinuous sucrose centrifugation of the shocked myelinated axons. By electron microscopy the axolemma-enriched fraction was composed of trilaminar membrane vesicles (diameter 50–1000 nm) and linear membrane fragments; myelin fragments were seldom seen but some mitochondria) membrane contamination was evident. The classical myelin stain Luxol Fast Blue never counter-stained the myelin-free axons, but did stain myelin, myelinated axons, and to a lesser extent, both axolemmal fractions. The staining of the axolemma-enriched fraction was amorphous and seemed incommensurate with the level of myelin contamination. Acetylcholinesterase staining of the axolemma-enriched fraction counterstained with Luxol Fast Blue revealed a number of acetylcholinesterase-positive membrane vesicles by light microscopy. Occasional enzyme-positive vesicles were also evident in the myelin while myelin-free axons showed virtually no Luxol Fast Blue stain but were heavily stained for the enzyme. Higher resolution histochemical staining by electron microscopy confirmed the light microscopy, showing acetylcholinest erase reaction product lining the axolemma of bovine and rat CNS neurons. Myelin, mitochondria, and other diverse membranes showed no reaction product. About 30% of bovine corpus callosal axons showed some acetylcholinesterase staining but only 3% of the total lengths of all the bovine CNS axolemma showed reaction product. Positive acetylcholinesterase staining could also be demonstrated in a small proportion of the bovine axolemma-enriched membranes, with reaction product lining the membrane fragments and captured within their vesicles. The percentage of vesicles that were stained closely agreed with the percentage of axolemma) length stained in the whole white matter. Since acetylcholinesterase staining was highly localized to the axonal plasma membrane, the acetylcholinesterase-positive membrane fragments in the axolemma-enriched membranes could only originate from the axolemma. We conclude on the basis of the operational behavior of these axolemmal vesicles that many of the membranes found in these fractions are derived from the axonal plasma membrane.